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Sample records for suspension polymerization technique

  1. Photoluminescent Patterned Papers Resulting from Printings of Polymeric Nanoparticles Suspension

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    Pierre Sarrazin

    2010-01-01

    Full Text Available The printability of a copolyfluorene-fluorenone (PFFO photoluminescent nanoparticle aqueous suspension on commercial tracing paper was here investigated. The nanoparticles suspension was obtained by miniemulsification of a suitable preformed photoluminescent organic polymer. The structural, physicochemical, and rheological characteristics of the nanoparticles suspension were first studied before considering its printability by inkjet and flexography techniques. The native properties of the nanoparticles suspension revealed to be more suitable for inkjet printing which was successfully used to print photoluminescent patterns using a very low amount of PFFO.

  2. 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.

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

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    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.

  4. 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.

  5. Preparation and Properties of Branched Polystyrene through Radical Suspension Polymerization

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    Wenyan Huang

    2017-01-01

    Full Text Available Radical solvent-free suspension polymerization of styrene with 3-mercapto hexyl-methacrylate (MHM as the branching monomer has been carried out using 2,2′-azobisisobutyronitrile (AIBN as the initiator to prepare branched polymer beads of high purity. The molecular weight and branching structure of the polymers have been characterized by triple detection size exclusion chromatography (TD-SEC, proton nuclear magnetic resonance spectroscopy (1H-NMR, and Fourier transform infrared spectroscopy (FTIR. The glass transition temperature and rheological properties have been measured by using differential scanning calorimetry (DSC and rotational rheometry. At mole ratios of MHM to AIBN less than 1.0, gelation was successfully avoided and branched polystyrene beads were prepared in the absence of any solvent. Branched polystyrene has a relatively higher molecular weight and narrower polydispersity (Mw.MALLS = 1,036,000 g·mol−1, Mw/Mn = 7.76 than those obtained in solution polymerization. Compared with their linear analogues, lower glass transition temperature and decreased chain entanglement were observed in the presently obtained branched polystyrene because of the effects of branching.

  6. Preparing polymeric biomaterials using "click" chemistry techniques

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    Lin, Fei

    Significant efforts have been focused on preparing degradable polymeric biomaterials with controllable properties, which have the potential to stimulate specific cellular responses at the molecular level. Click reactions provide a universal tool box to achieve that goal through molecular level design and modification. This dissertation demonstrates multiple methodologies and techniques to develop advanced biomaterials through combining degradable polymers and click chemistry. In my initial work, a novel class of amino acid-based poly(ester urea)s (PEU) materials was designed and prepared for potential applications in bone defect treatment. PEUs were synthesized via interfacial polycondensation, and showed degradability in vivo and possessed mechanical strength superior to conventionally used polyesters. Further mechanical enhancement was achieved after covalent crosslinking with a short peptide crosslinker derived from osteogenic growth peptide (OGP). The in vitro and in an in vivo subcutaneous rat model demonstrated that the OGP-based crosslinkers promoted proliferative activity of cells and accelerated degradation properties of PEUs. As a continuous study, extra efforts were focused on the development of PEUs with functional pendant groups, including alkyne, azide, alkene, tyrosine phenol, and ketone groups. PEUs with Mw exceeding to 100K Da were obtained via interfacial polycondensation, and the concentration of pendent groups was varied using a copolymerization strategy. Electrospinning was used to fabricate PEU nanofiber matrices with mechanical strengths suitable for tissue engineering. A series of biomolecules were conjugated to nanofiber surface following electrospinning using click reactions in aqueous media. The ability to derivatize PEUs with biological motifs using high efficient chemical reactions will significantly expand their use in vitro and in vivo. Based on similar principles, a series of mono- and multifunctionalized polycaprolactone (PCL

  7. Suspension suture techniques in nasal valve surgery

    NARCIS (Netherlands)

    Page, Meile S.; Menger, Dirk J.

    2011-01-01

    Impaired nasal breathing or collapse of the lateral side wall of the nasal valve region during inspiration is a frequently encountered symptom. In general, this is caused by a cross-sectional area that is too small, a weak lateral side wall, or a combination of both. Over the years, many techniques

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

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    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.

  9. Synthesis of poly(vinyl acetate-methyl methacrylate) copolymer microspheres using suspension polymerization.

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    Islam, Md Shahidul; Yeum, Jeong Hyun; Das, Ajoy Kumar

    2012-02-15

    Poly(vinyl acetate-methyl methacrylate) (VAc-MMA) copolymer microspheres were prepared using suspension polymerization at low temperature initiated with 2,2'-azobis(2,4-dimethyl valeronitrile) (ADMVN). The poly(VAc-MMA) copolymer microspheres can be used over a large area where homopolymers, polyvinyl acetate (PVAc) and methyl methacrylate (PMMA) microspheres are capable of being put to use. The prepared microspheres were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Obtained copolymer microspheres which have 200 μm average diameter and higher thermal stability than those of homopolymer. Crown Copyright © 2011. Published by Elsevier Inc. All rights reserved.

  10. Evaluating polymeric biomaterial-environment interfaces by Langmuir monolayer techniques.

    Science.gov (United States)

    Schöne, Anne-Christin; Roch, Toralf; Schulz, Burkhard; Lendlein, Andreas

    2017-05-01

    Polymeric biomaterials are of specific relevance in medical and pharmaceutical applications due to their wide range of tailorable properties and functionalities. The knowledge about interactions of biomaterials with their biological environment is of crucial importance for developing highly sophisticated medical devices. To achieve optimal in vivo performance, a description at the molecular level is required to gain better understanding about the surface of synthetic materials for tailoring their properties. This is still challenging and requires the comprehensive characterization of morphological structures, polymer chain arrangements and degradation behaviour. The review discusses selected aspects for evaluating polymeric biomaterial-environment interfaces by Langmuir monolayer methods as powerful techniques for studying interfacial properties, such as morphological and degradation processes. The combination of spectroscopic, microscopic and scattering methods with the Langmuir techniques adapted to polymers can substantially improve the understanding of their in vivo behaviour. © 2017 The Author(s).

  11. Development and validation of a fluorimetric method to determine curcumin in lipid and polymeric nanocapsule suspensions

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    Letícia Mazzarino

    2010-06-01

    Full Text Available A simple, rapid, and sensitive fluorimetric method was developed and validated to quantify curcumin in lipid and polymeric nanocapsule suspensions, using acetonitrile as a solvent. The excitation and emission wavelengths were set at 397 nm and 508 nm, respectively. The calibration graph was linear from 0.1 to 0.6 µg/mL with a correlation coefficient of 0.9982. The detection and quantitation limits were 0.03 and 0.10 µg/mL, respectively. The validation results confirmed that the developed method is specific, linear, accurate, and precise for its intended use. The current method was successfully applied to the evaluation of curcumin content in lipid and polymeric nanocapsule suspensions during the early stage of formulation development.Um método fluorimétrico simples, rápido e sensível foi desenvolvido e validado para quantificação da curcumina em suspensões de nanocápsulas lipídicas e poliméricas, usando acetonitrila como solvente. Os comprimentos de onda de excitação e emissão foram 397 nm e 508 nm, respectivamente. Nas condições testadas, a curva de calibração demonstrou-se linear na faixa de 0,1 a 0,6 µg/mL, exibindo coeficiente de correlação de 0,9982. Os limites de detecção e quantificação foram 0,03 e 0,10 µg/mL, respectivamente. Os resultados da validação confirmaram que o método desenvolvido é específico, linear, exato e preciso para o uso proposto. O presente método foi aplicado com sucesso para a avaliação do teor de curcumina nas suspensões de nanocápsulas lipídicas e poliméricas durante o estágio inicial do desenvolvimento da formulação.

  12. FATIGUE LIFE EVALUATION OF SUSPENSION KNUCKLE USING MULTIBODY SIMULATION TECHNIQUE

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    A.G.A. Rahman

    2012-12-01

    Full Text Available Suspension is part of automotive systems, providing both vehicle control and passenger comfort. The knuckle is an important part within the suspension system, constantly encountering the cyclic loads subjecting it to fatigue failure. This paper presents an evaluation of the fatigue characteristics of a knuckle using multibody simulation (MBS techniques. Load time history extracted from the MBS is used for stress analysis. An actual road profile of road bumps was used as the input to MBS. The stress fluctuations for fatigue simulations are considered with the road profile. The strain-life method is utilized to assess the fatigue life. The instantaneous stress distributions and maximum principal stress are used for fatigue life predictions. Mesh sensitivity analysis has been performed. The results show that the steering link in the knuckle is found to be the most susceptible region for fatigue failure. The number of times the knuckle can manage a road bump at 40 km/hr is determined to be approximately 371 times with a 50% certainty of survival. The proposed method of using the loading time history extracted from MBS simulation for fatigue life estimation is found to be very promising for the accurate evaluation of the performance of suspension system components.

  13. Remote Monitoring System Based on GPRS Technique for Polymerizer

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    Shuzhi Gao

    2014-05-01

    Full Text Available In order to the make the production of PVC safety and efficiency, a remote monitoring system based on GPRS technique for PVC polymerizer was introduced in this paper, the overall structure of the device was designed, and the dissertation presented a new communication protocol of the communications terminal, monitoring center, and client-side based on CDT communication convention and polling communication convention, the advantages of which are integrated and disadvantages improved and in the design of monitoring and management system, using the structs+spring+hibernate architecture develop remote monitoring software, realized the real-time data display, remote control, historical data query, and other functions. Thus efficient and reliable data transmission was achieved, the remote dynamic monitoring on the real-time operation date and faults for different sets of PVC polymerizers was also realized.

  14. Dispersion of alumina suspension using comb-like and diblock copolymers produced by RAFT polymerization of AMPS and MPEG.

    Science.gov (United States)

    Bouhamed, H; Boufi, S; Magnin, A

    2007-08-15

    Different copolymers of 2-acrylamido-2-methylpropanesulfonic acid sodium salt (AMPS) methoxypolyethyleneglycol methacrylate (MPEG) with statistical and diblock distributions were prepared using RAFT-controlled radical polymerization. The effect of polymer architecture and monomer ratio on the adsorption behavior, electrokinetic, and stability properties of the alumina suspensions was investigated. Adsorption isotherms showed that copolymer interaction depended on both the ratio of the monomers and their distribution within the macromolecular backbone. Changes in the electrokinetic properties of the alumina suspension after addition of the copolymers were investigated by monitoring the particle zeta-potential as a function of pH. A continuous shift in the isoelectric point IEP to a more acidic value was observed and particle charges were reversed when the amount of copolymer added exceeded a critical level.

  15. Trapezoid-quadrilateral technique of frontalis suspension with synthetic material.

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    Recep, Omer F; Karadag, Remzi; Hasiripi, Hikmet

    2008-04-01

    To describe a new method of frontalis suspension (FS) to prevent recurrences, undercorrection, and cosmetic problems, and to share our experiences in treatment of congenital ptosis using the trapezoid quadrilateral technique (TQT) and synthetic materials. Twenty-four eyes of 18 patients, admitted to Ankara Numune Training and Research Hospital 3rd Eye Clinic, Ankara, Turkey, between January 2002 to December 2004, were operated with a new method. All the patients had congenital ptosis, and they were 2-27 years old. Twelve of them were female and 6 of them were male. In this new method, the upper eyelid is fixed to the frontalis muscle from 2 points. The visual axis was open, and there was good symmetry between both eyes at the end of a mean of 14 months follow-up. There was granuloma formation in both eyes of one patient, exposure keratopathy in both eyes of another patient, and recurrence of ptosis in one eye of one patient. The TQT of FS with synthetic material does not cause any esthetic deformity and produces a balanced lifting in the upper eyelid. Therefore, we propose that it could be the preferred method in FS procedures performed with inorganic materials.

  16. 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).

  17. Facile iron-mediated dispersant-free suspension polymerization of methyl methacrylate via reverse ATRP in water.

    Science.gov (United States)

    Cao, Jun; Zhang, Lifen; Jiang, Xiaowu; Tian, Chun; Zhao, Xiaoning; Ke, Qi; Pan, Xiangqiang; Cheng, Zhenping; Zhu, Xiulin

    2013-11-01

    An iron-mediated reverse ATRP of methyl methacrylate (MMA) is successfully carried out in water in the absence of any dispersants, using a water-soluble 2,2'-azobis(2-methylpropionamidine) dihydrochloride (V-50) as the initiator and the stabilizer, and using an oil-soluble N,N-butyldithiocarbamate ferrum (Fe(S2 CN(C4 H9 )2 )3 ) as the catalyst without adding any additional ligands. Micron-sized PMMA particles with UV light-sensitive -S2 CN(C4 H9 )2 end group are obtained, and monomer droplet nucleation and suspension polymerization mechanism are proposed. Polymerization results demonstrated typical "living"/controlled characteristics of ATRP: first-order polymerization kinetics, linear increase of molecular weights with monomer conversion and narrow molecular weight distributions for the resultant PMMA particles. NMR spectroscopy and chain-extension experiments under UV light irradiation confirm the attachment and livingness of UV light-sensitive -S2 CN(C4 H9 )2 group in the chain end. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Skeletal response to simulated weightlessness - A comparison of suspension techniques

    Science.gov (United States)

    Wronski, T. J.; Morey-Holton, E. R.

    1987-01-01

    Comparisons are made of the skeletal response of rats subjected to simulated weightlessness by back or tail suspension. In comparison to pair-fed control rats, back-suspended rats failed to gain weight whereas tail-suspended rats exhibited normal weight gain. Quantitative bone histomorphometry revealed marked skeletal abnormalities in the proximal tibial metaphysis of back-suspended rats. Loss of trabecular bone mass in these animals was due to a combination of depressed longitudinal bone growth, decreased bone formation, and increased bone resorption. In contrast, the proximal tibia of tail-suspended rats was relatively normal by these histologic criteria. However, a significant reduction trabecular bone volume occurred during 2 weeks of tail suspension, possibly due to a transient inhibition of bone formation. The findings indicate that tail suspension may be a more appropriate model for evaluating the effects of simulated weightlessness on skeletal homeostasis.

  19. The calculation scheme for prediction of viscosity for polymeric nano-suspensions

    Science.gov (United States)

    Xu, Fengwei; Kurskaya, Elena; Matseevich, Tatyana; Popova, Marina; Askadskii, Andrey; Jiang, Shengling

    2017-05-01

    The calculation model for prediction of zero shear viscosity is suggested. Consideration is made on the basis of the equation of Einstein and Moony. The chemical structure of the surface modifier of nano-particles, its van der Waals volume, concentration and size of nanoparticles is taken into account. The relations obtained allow calculation the shear viscosity depending both of concentration and radius of nano-particles. Experiments conducted for nano-suspensions of silver particles in water, showed a good agreement between the calculated and experimental values of viscosity.

  20. Multi-focus two-photon polymerization technique based on individually controlled phase modulation.

    Science.gov (United States)

    Obata, Kotaro; Koch, Jürgen; Hinze, Ulf; Chichkov, Boris N

    2010-08-02

    Multi-focus two-photon polymerization with a spatial light modulator is demonstrated. The spatial light modulator generates multi-focus spots via phase modulation technique controlled by a computer generated hologram (CGH) pattern. Each focus spot can be individually addressed in position and laser intensity. The multi-focus two-photon polymerization technique allows the fabrication of complex 2-D and 3-D structures both symmetric and asymmetric. Smooth sine curved polymerized lines with amplitude of 5 microm and a period of 200 microm were obtained by fast switching of the CGH patterns.

  1. Comparison of the flexural strength of polymethyl methacrylate resin reinforced with multiwalled carbon nanotubes and processed by conventional water bath technique and microwave polymerization

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    Surabhi Somkuwar

    2017-01-01

    Conclusion: Heat polymerized denture base resin with and without reinforcement of MWCNTs and polymerized by microwave technique possess higher flexural strength than heat polymerized fiber reinforced denture resin polymerized by water bath technique. MWCNTs could be used as an effective reinforcement material for denture base resin polymerized by either water bath technique or microwave energy.

  2. 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.

  3. FTIR and Raman Spectroscopic Investigations of a Norfloxacin/Carbopol934 Polymeric Suspension

    Science.gov (United States)

    Sahoo, S; Chakraborti, CK; Behera, PK; Mishra, SC

    2012-01-01

    Till now very few formulations are available from which the drug is uniformly absorbed, so that the safe and effective blood level of norfloxacin could be maintained for a prolonged period. To fulfill this requirement, a controlled release mucoadhesive suspension was prepared by using a mucoadhesive carbopol934 polymer. The chemical interaction between norfloxacin and the polymer in formulation (prepared by an ultrasonication method) has been studied by FTIR and Raman spectroscopy. From the spectral interpretation, it has been found that in formulation, the carboxylic groups of norfloxacin and hydroxyl groups of carbopol934 undergo chemical interaction, leading to esterification and hydrogen bonding. The formation of micellies due to esterification and hydrogen bonding causes more drug entrapment and a stable formulation. From this it can be concluded that the formulation of norfloxacin may give a better controlled release and mucoadhesive action in the gastrointestinal tract. Hence, carbopol934 could be considered as an effective carrier for norfloxacin. PMID:23112532

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

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    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.

  5. Scale-up of a suspension-like polymerization process for the microencapsulation of phase change materials.

    Science.gov (United States)

    Sánchez-Silva, Luz; Carmona, Manuel; de Lucas, Antonio; Sánchez, Paula; Rodríguez, Juan F

    2010-01-01

    Microcapsules of polystyrene with a high level of encapsulated paraffin wax and a narrow size distribution were prepared by a suspension-like polymerization process. The scale-up of this microencapsulation process was carried out by designing a pilot plant that was geometrically proportional to that used on the laboratory scale with the aim of preparing microcapsules with a similar particle size and with the same phase change material (PCM) content as those obtained in the laboratory. In order to verify the effectiveness of the scale-up procedure, a number of experiments on the pilot plant were carried out using the optimal formulation found on the laboratory scale. Only slight differences in mean particle size and encapsulated paraffin content were observed between the two scales at higher stirring rates. The experimental values were fitted to the theoretical expression for the average dissipation rate as a function of the mean particle size. This showed that the classical nonintermittent Kolmogoroff theory is applicable on the laboratory scale, whereas in the pilot plant a large intermittence took place, thus limiting the scale-up to higher stirring rates at which an equal average dissipation rate in both scales led to the same mean particle size. The final results indicated that the assumptions made during the scale-up process were correct.

  6. The effect of polymerization and preparation techniques on the microleakage of composite laminate veneers

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    Neslihan Celik

    2017-01-01

    Full Text Available Background: Marginal leakage is the important factor influencing the maintenance of dental esthetic. Aim: The purpose of this study was to evaluate the relationship between the preparation techniques and type of polymerization techniques on microleakage of composite laminate veneers. Materials and Methods: Ninety-one same sized, caries-free human maxillary central incisors were randomly assigned to 13 groups (n = 7 and were designed with four different preparation techniques (window type, feather type, bevel type, and incisal overlap type. One group determined as control group and any preparation was applied. Nanohybrid resin composite was used for restoration. Composite laminate veneers polymerized with three different techniques (direct light curing, indirect polymerization with a combination of pressure, light and heat using a light cup and heat cup, direct polymerization, and additionally heat cured in an oven. The specimens were thermocycled, and then immersed in 5% basic fuchsine solution. Following 24 h, all specimens were immersed in 65% nitric acid solutions for volumetric dye extraction test. Samples diluted with distilled water and centrifuged and microleakage determined by a spectrophotometer. Statistical Analysis Used: Data were analyzed with two-way ANOVA and Tukey honest significant difference post hoc multiple comparisons test (P < 0.05. Results: For comparing the microleakage value of preparation and polymerization techniques, Window type preparation showed a significant difference in direct polymerization + additional cured group (P < 0.05. Control group was statistically different from the other groups (P < 0.05. Conclusions: Window type laminate preparation can be preferred in indirect polymerization technique because it caused less leakage in this present study.

  7. The Effect of Polymerization and Preparation Techniques on the Microleakage of Composite Laminate Veneers

    Science.gov (United States)

    Celik, Neslihan; Yapar, Merve Iscan; Taşpınar, Numan; Seven, Nilgun

    2017-01-01

    Background: Marginal leakage is the important factor influencing the maintenance of dental esthetic. Aim: The purpose of this study was to evaluate the relationship between the preparation techniques and type of polymerization techniques on microleakage of composite laminate veneers. Materials and Methods: Ninety-one same sized, caries-free human maxillary central incisors were randomly assigned to 13 groups (n = 7) and were designed with four different preparation techniques (window type, feather type, bevel type, and incisal overlap type). One group determined as control group and any preparation was applied. Nanohybrid resin composite was used for restoration. Composite laminate veneers polymerized with three different techniques (direct light curing, indirect polymerization with a combination of pressure, light and heat using a light cup and heat cup, direct polymerization, and additionally heat cured in an oven). The specimens were thermocycled, and then immersed in 5% basic fuchsine solution. Following 24 h, all specimens were immersed in 65% nitric acid solutions for volumetric dye extraction test. Samples diluted with distilled water and centrifuged and microleakage determined by a spectrophotometer. Statistical Analysis Used: Data were analyzed with two-way ANOVA and Tukey honest significant difference post hoc multiple comparisons test (P microleakage value of preparation and polymerization techniques, Window type preparation showed a significant difference in direct polymerization + additional cured group (P < 0.05). Control group was statistically different from the other groups (P < 0.05). Conclusions: Window type laminate preparation can be preferred in indirect polymerization technique because it caused less leakage in this present study. PMID:29042725

  8. Comparison of Two Polypropylene Frontalis Suspension Techniques in 92 Patients With Oculopharyngeal Muscular Dystrophy.

    Science.gov (United States)

    Kalin-Hajdu, Evan; Attas-Fox, Liat; Huang, Xi; Hardy, Isabelle; Codère, François

    To compare the functional outcome of the polypropylene trapezoid frontalis suspension with the polypropylene modified Crawford frontalis suspension in a large cohort of patients with oculopharyngeal muscular dystrophy. Retrospective, nonrandomized comparative case series. Patients with oculopharyngeal muscular dystrophy who underwent bilateral polypropylene frontalis suspension were selected for chart review. Main outcome measures were margin reflex distance, duration of surgery, and ptosis recurrence. Ninety-two patients qualified for chart review; 39 patients underwent the trapezoid sling and 53 patients the modified Crawford sling. There was no difference in preoperative margin reflex distance or levator function between the 2 surgical groups. Postoperative improvement in margin reflex distance was 2.95 ± 1.56 mm in the trapezoid group compared with 2.85 ± 1.65 mm in the modified Crawford group (p = 0.67). Duration of surgery was 40.49 ± 13.33 minutes in the trapezoid group compared with 53.77 ± 16.04 minutes in the modified Crawford group (p polypropylene frontalis suspension techniques generated an equivalent increase in margin reflex distance. However, the trapezoid frontalis suspension required less operative time and trended toward a lower rate of ptosis recurrence.

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

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    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.

  10. Evaluation of the color stability of two techniques for reproducing artificial irides after microwave polymerization.

    Science.gov (United States)

    Goiato, Marcelo Coelho; Santos, Daniela Micheline dos; Moreno, Amália; Gennari-Filho, Humberto; Pellizzer, Eduardo Piza

    2011-01-01

    The use of ocular prostheses for ophthalmic patients aims to rebuild facial aesthetics and provide an artificial substitute to the visual organ. Natural intemperate conditions promote discoloration of artificial irides and many studies have attempted to produce irides with greater chromatic paint durability using different paint materials. The present study evaluated the color stability of artificial irides obtained with two techniques (oil painting and digital image) and submitted to microwave polymerization. Forty samples were fabricated simulating ocular prostheses. each sample was constituted by one disc of acrylic resin N1 and one disc of colorless acrylic resin with the iris interposed between the discs. The irides in brown and blue color were obtained by oil painting or digital image. The color stability was determined by a reflection spectrophotometer and measurements were taken before and after microwave polymerization. Statistical analysis of the techniques for reproducing artificial irides was performed by applying the normal data distribution test followed by 2-way ANOVA and Tukey HSD test (α=.05). Chromatic alterations occurred in all specimens and statistically significant differences were observed between the oil-painted samples and those obtained by digital imaging. There was no statistical difference between the brown and blue colors. Independently of technique, all samples suffered color alterations after microwave polymerization. The digital imaging technique for reproducing irides presented better color stability after microwave polymerization.

  11. 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

  12. Strengthening Techniques of RC Columns Using Fibre Reinforced Polymeric Materials

    Directory of Open Access Journals (Sweden)

    Ciprian Cozmanciuc

    2009-01-01

    Full Text Available Fibre reinforced composite materials are becoming more frequently used in civil engineering structures. One of the most practical applications of these new materials concerns the strengthening of reinforced concrete columns by means of confinement with fibre composite sheets. In the literature, various theoretical models have been proposed to describe the behaviour of confined concrete columns. The principal advantages of this technique are the high strength-to-weight ratio, good fatigue properties, non-corroding characteristics of the fibre reinforced polymers (FRP, and the facility of its application. The maximum efficiency of confining systems using FRP materials is reached in case of columns with circular cross-section and is explained by the fact that the entire section of the column is involved into the confinement effect. Rectangular confining reinforcement is less efficient as the confinement action is mostly located at the corners This paper reveals the most utilized techniques of performing composite confining systems for reinforced concrete columns, with their advantages and also disadvantages.

  13. 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.

  14. Electrophoretic deposition of unstable colloidal suspensions for superhydrophobic surfaces.

    Science.gov (United States)

    Joung, Young Soo; Buie, Cullen R

    2011-04-05

    A novel method to fabricate superhydrophobic surfaces using electrophoretic deposition (EPD) is presented. EPD presents a readily scalable, customizable, and potentially low cost surface manufacturing process. Low surface energy materials with high surface roughness are achieved using EPD of unstable hydrophobic SiO(2) particle suspensions. The effect of suspension stability on surface roughness is quantitatively explored with optical absorbance measurements (to determine suspension stability) and atomic force microscopy (to measure surface roughness). Varying suspension pH modulates suspension stability. Contrary to most applications of EPD, we show that superhydrophobic surfaces favor mildly unstable suspensions since they result in high surface roughness. Particle agglomerates formed in unstable suspensions lead to highly irregular films after EPD. After only 1 min of EPD, we obtain surfaces with low contact angle hysteresis and static contact angles exceeding 160°. We also present a technique to enhance the mechanical durability of the superhydrophobic surfaces by adding a polymeric binder to the suspension prior to EPD.

  15. Cotton fabric coated with nano TiO{sub 2}-acrylate copolymer for photocatalytic self-cleaning by in-situ suspension polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Xue, E-mail: jiangx@jiangnan.edu.cn [Key Laboratory of Eco-textiles of Ministry of Education, College of textiles and Clothing, Jiangnan University, Wuxi, Jiangsu 214122 (China); State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, Guangdong, 510640 (China); Tian Xiuzhi; Gu Jian; Huang Dan [Key Laboratory of Eco-textiles of Ministry of Education, College of textiles and Clothing, Jiangnan University, Wuxi, Jiangsu 214122 (China); Yang Yiqi [Key Laboratory of Eco-textiles of Ministry of Education, College of textiles and Clothing, Jiangnan University, Wuxi, Jiangsu 214122 (China); Department of Textiles, Clothing and Design, 234 HECO Bldg, University of Nebraska-Lincoln, Lincoln, NE 68583-0802 (United States)

    2011-08-01

    Two kinds of nano TiO{sub 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{sub 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{sub 2}. Transmission electron microscope illustrated that there was a polymeric layer on the surface of nano TiO{sub 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{sub 2}-polymer hybrid had excellent self-cleaning property.

  16. Cotton fabric coated with nano TiO 2-acrylate copolymer for photocatalytic self-cleaning by in-situ suspension polymerization

    Science.gov (United States)

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

    2011-08-01

    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.

  17. The controlled placement and delayed polymerization technique for the direct Class 2 posterior composite restoration.

    Science.gov (United States)

    Atlas, Alan M

    2005-11-01

    Adhesion dentistry and its application to the direct posterior composite restoration is the most controversial topic in dentistry today. The concepts behind this procedure are now the backbone of restorative dentistry. Adhesion dentistry influences basic fillings, crown buildups, post-and-core restorations, cementation, orthodontics, and endodontics. Yet, controversy remains about the correct way to place a direct Class 2 posterior composite restoration. This article will examine the scientific evidence to determine which materials and placement techniques will achieve the optimum direct Class 2 posterior composite restoration at or below the cementoenamel junction using the controlled placement and delayed polymerization technique.

  18. 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.

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

    National Research Council Canada - National Science Library

    NITTA, Keiko; NOMOTO, Rie; TSUBOTA, Yuji; TSUCHIKAWA, Masuji; HAYAKAWA, Tohru

    2017-01-01

    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...

  20. 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.

  1. Adhesive Bonding Techniques in Hybrid Structures Made from Fibre Reinforced Polymeric Composites and Concrete

    Directory of Open Access Journals (Sweden)

    Ruxandra Oltean

    2009-01-01

    Full Text Available Mechanical joining techniques are used in construction industry all over the world on a daily basis. A further method of joining has proven to be highly successful – adhesive bonding. Known for thousands of years, adhesive bonding has become as important as other joining techniques as a result of the pace of developments in recent years. In many areas, this bonding technology has become a key technology. Virtually, all solid materials can be connected with one another using adhesives. Although bonding fibre reinforced polymeric composites to the concrete substrate is a relatively simple technique, the proper installation of the fibre reinforced polymeric composites is essential to ensure the adequate performance of the hybrid system. Since the installation procedures differ from one system to another, appropriate specifications will be clearly presented. The paper will include requirements to provide a quality joint assembly, meaning the special pre-treatments of the concrete surface. The material to be bonded is cleaned and prepared so that adhesives can adhere better to them.

  2. 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.

  3. Design, characterization, and evaluation of meloxicam gel prepared by suspension and solution polymerization using solubility parameter as the basis for development.

    Science.gov (United States)

    Jain, Deepika; Pathak, Kamla

    2010-03-01

    Meloxicam gel was designed based on the matching of the solubility parameter (delta) of the drug with that of the polymer and subsequently with skin for improved dermal delivery of meloxicam. The delta of meloxicam (11.48 (cal/cm(3))(0.5)) determined by solubility measurement was matched statistically to the solubility parameter of monomers, n-vinyl-2-pyrrolidone, polyvinyl alcohol (PVA), hydroxyl ethyl methacrylate, ethylene glycol methacrylate (EGMA) determined by intrinsic viscosity measurement. Consequently gels were formulated by polymerization in selected solvent blend of water/ethyl acetate (20:80) in which the drug showed maximum solubility. Thus, F1-F16 formulations designed were evaluated for physicochemical properties, textural analysis, and in vitro drug release. On the basis of optimum characteristics, F2 (PVA, delta = 16.96 (cal/cm(3))(0.5)) and F8 (EGMA, delta = 18.35 (cal/cm(3))(0.5)) formulated by suspension polymerization were selected and subjected to skin irritation and topical anti-inflammatory studies. The formulation F8 demonstrated significant (p < 0.05) of anti-inflammatory activity in comparison to marketed piroxicam gel and was free from irritation.

  4. Deterministic embedding of a single gold nanoparticle into polymeric microstructures by direct laser writing technique

    Science.gov (United States)

    Nguyen, Dam Thuy Trang; Pelissier, Aurélien; Montes, Kevin; Tong, Quang Cong; Ngo, Hoang Minh; Ledoux-Rak, Isabelle; Lai, Ngoc Diep

    2016-04-01

    We have precisely positioned and embedded a single gold nanoparticle (Au NP) into a desired polymeric photonic structure (PS) using a simple and low-cost technique called low one-photon absorption direct laser writing (LOPA DLW), with a two-step process: identification and fabrication. First, the position of the Au NP was identified with a precision of 20 nm by using DLW technique with ultralow excitation laser power (μW). This power did not induce the polymerization of the photoresist (SU8) due to its low absorption at the excitation wavelength (532 nm). Then, the structure containing the NP was fabricated by using the same DLW system with high excitation power (mW). Different 2D photonic structures have been fabricated, which contain a single Au NP at desired position. In particular, we obtained a microsphere instead of a micropillar at the position of the Au NP. The formation of such microsphere was explained by the thermal effect of the Au NP at the wavelength of 532 nm, which induced thermal polymerization of surrounding photoresist. The effect of the post-exposure bake on the quality of structures was taken into account, revealing a more efficient fabrication way by exploiting the local thermal effect of the laser. We studied further the influence of the NP size on the NP/PS coupling by investigating the fabrication and fluorescence measurement of Au NPs of different sizes: 10, 30, 50, 80, and 100 nm. The photon collection enhancements in each case were 12.9 +/- 2.5, 12.6 +/- 5.6, 3.9 +/- 2.7, 5.9 +/- 4.4, and 6.6 +/- 5.1 times, respectively. The gain in fluorescence could reach up to 36.6 times for 10-nm gold NPs.

  5. Synthesis of polyHEMA hydrogels for using as biomaterials. Bulk and solution radical-initiated polymerization techniques

    Directory of Open Access Journals (Sweden)

    Juliana Matos Seidel

    2000-07-01

    Full Text Available Dense and porous polyHEMA hydrogels were synthesized by bulk and solution radical-initiated polymerization techniques. The morphologic analysis (SEM of obtained hydrogels showed an amorphous dense structure for the samples obtained by bulk polymerization and a porous structure with non connected porous as a result of bulk polymerization in the presence of water soluble crystals (sucrose/NaCl. The use of solution polymerization technique using different amounts of water as diluent resulted in the formation of a sponge-like structure with connected microporous in case of using water amount equal or higher than 57.5%. The saline solution uptake and dynamic mechanical behavior of dense hydrogels were influenced by the amount of crosslinking between the polymer chains.

  6. Mechanical characterization of polymeric thin films by atomic force microscopy based techniques.

    Science.gov (United States)

    Passeri, Daniele; Rossi, Marco; Tamburri, Emanuela; Terranova, Maria Letizia

    2013-02-01

    Polymeric thin films have been awakening continuous and growing interest for application in nanotechnology. For such applications, the assessment of their (nano)mechanical properties is a key issue, since they may dramatically vary between the bulk and the thin film state, even for the same polymer. Therefore, techniques are required for the in situ characterization of mechanical properties of thin films that must be nondestructive or only minimally destructive. Also, they must also be able to probe nanometer-thick ultrathin films and layers and capable of imaging the mechanical properties of the sample with nanometer lateral resolution, since, for instance, at these scales blends or copolymers are not uniform, their phases being separated. Atomic force microscopy (AFM) has been proposed as a tool for the development of a number of techniques that match such requirements. In this review, we describe the state of the art of the main AFM-based methods for qualitative and quantitative single-point measurements and imaging of mechanical properties of polymeric thin films, illustrating their specific merits and limitations.

  7. Spray freeze drying as an alternative technique for lyophilization of polymeric and lipid-based nanoparticles.

    Science.gov (United States)

    Ali, Mohamed Ehab; Lamprecht, Alf

    2017-01-10

    The use of nanoparticles for drug delivery is still restricted by their limited stability when stored in an aqueous medium. Freeze drying is the standard method for long-term storage of colloidal nanoparticles; however the method needs to be elaborated for each formulation. Spray freeze drying (SFD) is proposed here as a promising alternative for lyophilizing colloidal nanoparticles. Different types of polymeric and lipid nanoparticles were prepared and characterized. Afterwards, samples were spray freeze dried by spraying into a column of cold air with a constant concentration of different cryoprotectants, and the frozen spherules were collected for further freeze drying. Similar samples were prepared using the commonly used technique, freeze drying, as controls. Using SFD, fast-dissolving, spherical and porous nanocomposite microparticles with remarkably high flowability (CI≤10) were produced. On the contrary to similar samples prepared using the freeze drying technique, the investigated polymeric and lipid nanoparticles were completely reconstituted (S f /S i ratio <1.5) after SFD. SFD proved to be an effective platform for improving the long-term stability of colloidal nanoparticles. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. A review of polymeric refabrication techniques to modify polymer properties for biomedical and drug delivery applications.

    Science.gov (United States)

    Pillay, Viness; Seedat, Ahmed; Choonara, Yahya E; du Toit, Lisa C; Kumar, Pradeep; Ndesendo, Valence M K

    2013-06-01

    Polymers are extensively used in the pharmaceutical and medical field because of their unique and phenomenal properties that they display. They are capable of demonstrating drug delivery properties that are smart and novel, such properties that are not achievable by employing the conventional excipients. Appropriately, polymeric refabrication remains at the forefront of process technology development in an endeavor to produce more useful pharmaceutical and medical products because of the multitudes of smart properties that can be attained through the alteration of polymers. Small alterations to a polymer by either addition, subtraction, self-reaction, or cross reaction with other entities have the capability of generating polymers with properties that are at the level to enable the creation of novel pharmaceutical and medical products. Properties such as stimuli-responsiveness, site targeting, and chronotherapeutics are no longer figures of imaginations but have become a reality through utilizing processes of polymer refabrication. This article has sought to review the different techniques that have been employed in polymeric refabrication to produce superior products in the pharmaceutical and medical disciplines. Techniques such as grafting, blending, interpenetrating polymers networks, and synthesis of polymer complexes will be viewed from a pharmaceutical and medical perspective along with their synthetic process required to attain these products. In addition to this, each process will be evaluated according to its salient features, impeding features, and the role they play in improving current medical devices and procedures.

  9. 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.

  10. 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.

  11. Polymerization of Vinylpyrrolidone to Form a Neutral Coating on Anionic Nanomaterials in Aqueous Suspension for Rapid Sedimentation

    Directory of Open Access Journals (Sweden)

    Edward P. C. Lai

    2014-05-01

    Full Text Available Nanomaterials in water present an array of identifiable potential hazards to ecological and human health. There is no general consensus about the influence of anionic or cationic charge on the toxicity of nanomaterials on environmental ecology. One challenge is the limited number of scalable technologies available for the removal of charged nanomaterials from water. A new method based on polymer coating has been developed in our laboratory for rapid sedimentation of nanomaterials in aqueous suspension. Using colloidal silica as a model inorganic oxide, coating of polyvinylpyrrolidone (PVP around the SiO2 nanoparticles produced SiO2@PVP particles, as indicated by a linear increase of nephelometric turbidity. Purification of the water sample was afforded by total sedimentation of SiO2@PVP particles when left for 24 h. Characterization by capillary electrophoresis (CE revealed nearly zero ionic charge on the particles. Further coating of polydopamine (PDA around those particles in aqueous suspension produced an intense dark color due to the formation of SiO2@PVP@PDA. The SiO2@PVP@PDA peak appeared at a characteristic migration time of 4.2 min that allowed for quantitative CE-UV analysis to determine the original SiO2 concentration with enhanced sensitivity and without any ambiguous identity.

  12. 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.

  13. 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.

  14. Vibration control of a class of semiactive suspension system using neural network and backstepping techniques

    Science.gov (United States)

    Zapateiro, M.; Luo, N.; Karimi, H. R.; Vehí, J.

    2009-08-01

    In this paper, we address the problem of designing the semiactive controller for a class of vehicle suspension system that employs a magnetorheological (MR) damper as the actuator. As the first step, an adequate model of the MR damper must be developed. Most of the models found in literature are based on the mechanical behavior of the device, with the Bingham and Bouc-Wen models being the most popular ones. These models can estimate the damping force of the device taking the control voltage and velocity inputs as variables. However, the inverse model, i.e., the model that computes the control variable (generally the voltage) is even more difficult to find due to the numerical complexity that implies the inverse of the nonlinear forward model. In our case, we develop a neural network being able to estimate the control voltage input to the MR damper, which is necessary for producing the optimal force predicted by the controller so as to reduce the vibrations. The controller is designed following the standard backstepping technique. The performance of the control system is evaluated by means of simulations in MATLAB/Simulink.

  15. Minimal Undermining Suspension Technique (MUST): Combined Eyebrow and Mid-face Lift via Temporal Access.

    Science.gov (United States)

    Gualdi, Alessandro; Cambiaso-Daniel, Janos; Gatti, Jonatann; Bertossi, Dario; Pietramaggiori, Giorgio; Scherer, Saja S; Wurzer, Paul; Lumenta, David B

    2017-02-01

    Less downtime following esthetic interventions leads to the popularity of injectable solutions for facial rejuvenation treatments. Surgical interventions for esthetic purposes are usually associated with higher complication rates and longer recovery times when compared to less invasive treatments. Here we present for the first time a minimally invasive surgical technique for a simultaneous mid-face and eyebrow lift using one small temporal incision. We prospectively studied patients who underwent facial rejuvenation using a minimal undermining suspension technique (MUST) in an outpatient setting. Postoperatively, surgical complications were classified according to the Clavien-Dindo classification. Preoperatively and at 12-month post-intervention, patient-reported outcomes were described using the FACE-Q questionnaire. Pre- and postoperative pictures were compared using MERZ Aesthetic Scales. Fifty-five patients (50 females and 5 males) with a mean age of 47 years were studied. The overall complication rate was 19%, whereas 18 patients (15%) developed an ecchymosis of the orbicular temporal region and two patients (4%) developed a dimple caused by the anchor of the suture. No displacements of the palpebral rim or injuries to the facial nerve were observed. Recovery time was in average 7 days and no long-term complications were seen. Both, the FACE-Q and the MERZ Aesthetic Scales showed significant improvements at 12-month post-surgery (p face and eyebrow lift. Further studies are warranted to prove long-term outcomes. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the A3 online Instructions to Authors. www.springer.com/00266 .

  16. 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

    of the solution ATRP conditions and extending those conditions to the SI-ATRP. As a result, the new acetone/methyl methacrylate medium was found to be optimal for MMA polymerization both in the solution and on the surface. The reaction mixture was studied thoroughly; in addition to ex-situ techniques...

  17. Complementary analysis techniques applied on optimizing suspensions of yttria stabilized zirconia

    DEFF Research Database (Denmark)

    Della Negra, Michela; Foghmoes, Søren Preben Vagn; Klemensø, Trine

    2016-01-01

    Three different polymers with different functional groups and similar molecular weight were tested as dispersing agents for suspensions of yttria stabilized zirconia in ethanol: polyvinyl pyrrolidone, polyethylene imine, polyvinyl butyral/acetal. The stability of the system was assessed considering...

  18. Physics-based Modeling Techniques for Analysis and Design of Advanced Suspension Systems with Experimental Validation

    OpenAIRE

    Farjoud, Alireza

    2011-01-01

    This research undertakes the problem of vibration control of vehicular and structural systems using intelligent materials and controllable devices. Advanced modeling tools validated with experimental test data are developed to help with understanding the fundamentals as well as advanced and novel applications of smart and conventional suspension systems. The project can be divided into two major parts. The first part is focused on development of novel smart suspensions using Magneto-Rheolo...

  19. 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.

  20. Applications of Fast, Facile, Radiation-Free Radical Polymerization Techniques Enabled by Room Temperature Alkylborane Chemistry.

    Science.gov (United States)

    Ahn, Dongchan; Wier, Kevin A; Mitchell, Timothy P; Olney, Patricia A

    2015-11-04

    Fast, robust, and scalable techniques for covalent materials assembly are shown to be enabled by variants of a simple mixing-induced free radical initiation scheme broadly termed room-temperature alkylborane (RTA) chemistry. Unique process versatility, speed of reaction, high conversion, and structural control at ambient conditions occur by exploiting air-stable alkylborane-amine complexes that rapidly initiate upon mixing with common amine-reactive decomplexing agents such as carboxylic acid compounds. Three diverse application examples are presented, illustrating facile ambient routes to covalent assembly varying in length scale: (1) copolymers with controllable pressure-sensitive adhesive properties, (2) hydrophilically modified silicone microparticles from heterophase reactions, and (3) UV-free inkjet printable materials suitable for thick-textured patterning and printing, all conducted in open air with no radiation or atmospheric control. These examples demonstrate that this simple "bucket chemistry" can create intriguing degrees of freedom for polymerization, cross-linking and covalent macromolecular assembly with controllable structure and properties, suggesting further opportunities for both fundamental mechanistic investigation and application to a range of old and new materials assembly problems across length scales.

  1. Polymerization efficacy of simplified adhesive systems studied by NMR and MRI techniques.

    Science.gov (United States)

    Nunes, T G; Garcia, F C P; Osorio, R; Carvalho, R; Toledano, M

    2006-10-01

    To ascertain the efficacy of polymerization of self-etching dental adhesives in different solvent evaporation conditions. Four self-etching adhesive systems were studied. Two of them are classified as mild two-step self-etching adhesives (Clearfil SE Bond, Protect Bond) and the other two are strong one-step systems (Xeno III, ADP-Prompt-L-Pop). The influence of temperature and duration of the air-drying period on photo-polymerization was followed by: gravimetry, (1)H solid-state NMR spectroscopy and stray-field MRI. The evolution of proton magnetization with irradiation time was recorded and correlated with volumetric polymerization shrinkage and extent of reaction; evaporation and hardening effects were identified. Main variables determining water-solvent evaporation of the tested adhesives are: (1) water/HEMA relative concentration, (2) presence of photoinitiator compounds in the primer (SEB) and (3) presence of ethanol (XENO). SEB shows the highest extent of photo-polymerization of the tested adhesives. The lowest volumetric contraction was obtained for APLP and XENO and the attempt to remove the solvents did not increase the extent of polymerization significantly. Temperature increase following photo-polymerization reaction is dominant towards the effect of the drying step for solvent evaporation in self-etching systems. Attempts to remove the solvents did not increase the extent of polymerization, so other problems are impairing the polymerization of one-step adhesives. The use of tested one-step adhesives is discouraged as the attained low extent of polymerization may lead to low bond strength, high susceptibility to degradation and also will favor a continuing etching effect on the underlying dentin.

  2. Fabrication of porous polymeric matrix drug delivery devices using the selective laser sintering technique.

    Science.gov (United States)

    Leong, K F; Phua, K K; Chua, C K; Du, Z H; Teo, K O

    2001-01-01

    New techniques in solid freeform fabrication (SFF) have prompted research into methods of manufacturing and controlling porosity. The strategy of this research is to integrate computer aided design (CAD) and the SFF technique of selective laser sintering (SLS) to fabricate porous polymeric matrix drug delivery devices (DDDs). This study focuses on the control of the porosity of a matrix by manipulating the SLS process parameters of laser beam power and scan speed. Methylene blue dye is used as a drug model to infiltrate the matrices via a degassing method; visual inspection of dye penetration into the matrices is carried out. Most notably, the laser power matrices show a two-stage penetration process. The matrices are sectioned along the XZ planes and viewed under scanning electron microscope (SEM). The morphologies of the samples reveal a general increase in channel widths as laser power decreases and scan speed increases. The fractional release profiles of the matrices are determined by allowing the dye to diffuse out in vitro within a controlled environment. The results show that laser power and scan speed matrices deliver the dye for 8-9 days and have an evenly distributed profile. Mercury porosimetry is used to analyse the porosity of the matrices. Laser power matrices show a linear relationship between porosity and variation in parameter values. However, the same relationship for scan speed matrices turns out to be rather inconsistent. Relationships between the SLS parameters and the experimental results are developed using the fractional release rate equation for the infinite slab porous matrix DDD as a basis for correlation.

  3. Conductive Polymer Synthesis with Single-Crystallinity via a Novel Plasma Polymerization Technique for Gas Sensor Applications

    Directory of Open Access Journals (Sweden)

    Choon-Sang Park

    2016-09-01

    Full Text Available This study proposes a new nanostructured conductive polymer synthesis method that can grow the single-crystalline high-density plasma-polymerized nanoparticle structures by enhancing the sufficient nucleation and fragmentation of the pyrrole monomer using a novel atmospheric pressure plasma jet (APPJ technique. Transmission electron microscopy (TEM, Fourier transform infrared spectroscopy (FT-IR, X-ray photoelectron spectroscopy (XPS, and field emission scanning electron microscopy (FE-SEM results show that the plasma-polymerized pyrrole (pPPy nanoparticles have a fast deposition rate of 0.93 µm·min−1 under a room-temperature process and have single-crystalline characteristics with porous properties. In addition, the single-crystalline high-density pPPy nanoparticle structures were successfully synthesized on the glass, plastic, and interdigitated gas sensor electrode substrates using a novel plasma polymerization technique at room temperature. To check the suitability of the active layer for the fabrication of electrochemical toxic gas sensors, the resistance variations of the pPPy nanoparticles grown on the interdigitated gas sensor electrodes were examined by doping with iodine. As a result, the proposed APPJ device could obtain the high-density and ultra-fast single-crystalline pPPy thin films for various gas sensor applications. This work will contribute to the design of highly sensitive gas sensors adopting the novel plasma-polymerized conductive polymer as new active layer.

  4. The synthesis and characteristics of polymer nanoballs by plasma polymerization cooperating with DC plasma sputtering technique

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Zhongqing, E-mail: zhongqingjiang@hotmail.co [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Yu Xinyao; Shi Yicai; Meng Yuedong [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2010-09-01

    Multi-composition of the polymer nanoball carrying sulfonic acid groups, silicon oxide and pyridine groups with diameter of {approx} 25 nm was made from a plasma polymerization of 2-vinylpyridine and trifluoromethanesulfonic acid cooperating with direct current (DC) plasma sputtering of methyl etheneyl silicone rubber in a low-frequency after-glow capacitively coupled plasma (CCP) discharge apparatus. It is concluded that the size and composition of the core-polymerized polymer nanoball can be controlled by altering the partial pressure ratio of trifluoromethanesulfonic acid and 2-vinylpyridine. Pyridine groups tethered to the polymer backbone can act as a medium through the basic nitrogen for transfer of protons between the sulfonic acid groups of proton exchange membrane, and a polymeric form of silicon oxide in polymer nanoball can improve water retention. Thus, doping these polymer nanoballs into polymer membranes as a proton transport facilitator for polymer electrolyte membrane fuel cells seems promising.

  5. Test techniques: A survey paper on cryogenic tunnels, adaptive wall test sections, and magnetic suspension and balance systems

    Science.gov (United States)

    Kilgore, Robert A.; Dress, David A.; Wolf, Stephen W. D.; Britcher, Colin P.

    1989-01-01

    The ability to get good experimental data in wind tunnels is often compromised by things seemingly beyond our control. Inadequate Reynolds number, wall interference, and support interference are three of the major problems in wind tunnel testing. Techniques for solving these problems are available. Cryogenic wind tunnels solve the problem of low Reynolds number. Adaptive wall test sections can go a long way toward eliminating wall interference. A magnetic suspension and balance system (MSBS) completely eliminates support interference. Cryogenic tunnels, adaptive wall test sections, and MSBS are surveyed. A brief historical overview is given and the present state of development and application in each area is described.

  6. Comparative effect of different polymerization techniques on residual monomer and hardness properties of PMMA-based denture resins.

    Science.gov (United States)

    Ayaz, Elif Aydogan; Durkan, Rukiye; Koroglu, Ayşegul; Bagis, Bora

    2014-12-30

    The aim of this study was to compare the residual monomer and microhardness of poly(methyl methacrylate) (PMMA)-based denture resins processed by using autoclave and conventional water bath techniques. To determine the amount of residual methyl methacrylate (MMA) monomer, disk-shaped specimens (n=5) were prepared from 3 different acrylic resins (Meliodent, Paladent and Qc-20). Control groups were polymerized in water bath for 30 minutes at 100°C. The study groups were prepared in an autoclave device for 60°C/30 min followed 130°C/10 min and the other group for 60°C/30 min followed by 130°C/20 min. According to standard calibration curves, ultraviolet spectrophotometry at 230 nm was used to determine the residual monomer. For the Vickers hardness measurements, disk-shaped specimens (n=5) were prepared for each test group. Hardness measurements were performed with a Vickers hardness tester under a 4.91-N press load for a 30 seconds, after immersion in distilled water at 37ºC for 48 hours. The data were analyzed by ANOVA and Tukey HSD test (phardness for all resin groups (p0.05). The autoclave polymerization technique exhibited significantly lower residual monomer content and greater hardness than conventional heat polymerization.

  7. Novel surface-modification techniques for polymer-based separation media. Stimulus-responsive phenomena based on double polymeric selectors.

    Science.gov (United States)

    Hosoya, Ken; Watabe, Yoshiyuki; Kubo, Takuya; Hoshino, Naoaki; Tanaka, Nobuo; Sano, Tomoharu; Kaya, Kunimitsu

    2004-03-19

    A pair of polymeric selectors potentially responding to stimulation was introduced onto monosized porous polymer particles to be evaluated as a packing material for HPLC. Possible complexes formed between polyacrylamide (PAAm) and poly(methacrylic acid) (PMAA) were utilized as stimulus responsive polymeric selectors. Uniformly sized base polymer particle was prepared by multi-step swelling and polymerization method, while the introduction of PAAm and PMAA was done by newly invented modification technique. In this technique, a solvent in which both acrylamide (AAm) and methacrylic acid (MAA) monomers are soluble, but PAAm and PMAA are insoluble, was utilized as a modification medium. The polymer particle doubly modified with PAAm and PMAA was utilized as packing material for HPLC and the stimulus responses were evaluated by changing temperature or pH to check change of the slope of a Van't Hoff plot. By using water as a mobile phase, the expected inflection point of the Van't Hoff plot was observed at upper critical solution temperature (UCST) of the polymer complexes and the temperature responsive ability was observed. Moreover, pH responsive ability was studied by using buffer of either pH 4 or 10 as mobile phase. Slope of the plot was changed in buffer of pH 4, but no change of slope was observed in the buffer of pH 10.

  8. 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

  9. 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...

  10. Vibration Control of a Semiactive Vehicle Suspension System Based on Extended State Observer Techniques

    Directory of Open Access Journals (Sweden)

    Ze Zhang

    2014-01-01

    Full Text Available A feedback control method based on an extended state observer (ESO method is implemented to vibration reduction in a typical semiactive suspension (SAS system using a magnetorheological (MR damper as actuator. By considering the dynamic equations of the SAS system and the MR damper model, an active disturbance rejection control (ADRC is designed based on the ESO. Numerical simulation and real-time experiments are carried out with similar vibration disturbances. Both the simulation and experimental results illustrate the effectiveness of the proposed controller in vibration suppression for a SAS system.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Effect of thermocycling and varying polymerization techniques on the restorative interface of class V cavities restored with different composite resin systems.

    Science.gov (United States)

    Pereira, Jefferson-Ricardo; Júnior, Lindomar-Corrêa; Só, Marcus-Vinicius-Reis; Júnior, Newton-Fahl

    2017-03-01

    To evaluate marginal microleakage of two composite resins - a methacrylate- and a silorane-based submitted to different polymerization techniques and thermocycling. Ninety-six class V cavities were prepared in sound human molars and restored under different polymerization and thermocycling regimens. The adhesive systems employed were Adper Scotchbond Multipurpose and Filtek P-90 for cavities restored with Z250 and P-90. The specimens were restored with Z250 or P-90, and divided into 3 subgroups with different polymerization techniques. The data were analyzed by Three way Analysis of Variance Test (p0.001). Silorane-based composite resins present lower marginal microleakage values when compared to methacrylate-based composites resins. Key words:Composite resin, microleakage, polymerization.

  16. Urban transport without catenary suspension and new storage techniques; Transport urbain sans catenaire et nouvelles techniques de stockage

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, G.; Bartholomeux, P.; Le Moigne, Ph.; Rombaut, Ch. [Ecole Centrale de Lille, L2EP, 59 - Villeneuve d' Ascq (France); Van Berten, Ph. [Bombardier transport' t, 59 - Crespin (France); Poli, G. [Technicatome, 13 - Aix en Provence (France)

    2000-07-01

    In this article are described two new plans for electric vehicles used in the sector of urban transport. The constraints due to the use of new techniques of electric power production that is to say: super-capacitors and fuel cells are presented. (O.M.)

  17. 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.

  18. Reducing the effect of polymerization shrinkage of temporary fixed dental prostheses by using different materials and fabrication techniques.

    Science.gov (United States)

    Libecki, Wojtek; Elsayed, Adham; Freitag-Wolf, Sandra; Kern, Matthias

    2016-12-01

    The aim of this laboratory study was to evaluate the horizontal and vertical effects of the polymerization shrinkage of three-unit temporary fixed dental prostheses (FDPs) on the position of the prepared teeth. In addition, the reduction of these effects by using different fabrication techniques was evaluated. A total of 192 temporary FDPs were fabricated using one methacrylate (MA) and two dimethacrylate (DMA) materials. Each material group (n=64) was divided into two groups according to the fabrication methods (M1: curing on the prepared teeth, M2: curing in a silicone mold). Each fabrication group was divided into four subgroups (n=8) according to the relining method used (B: no relining, S: spacer foil 300μm, DG: grinding-out with 500μm cutting depth, and FG: free grinding). The experimental apparatus consisted of two abutment teeth lowered at right angles into a silicone mold. One prepared tooth was embedded in silicone to simulate the periodontium and permit slight horizontal tooth movement. The dimensional changes were recorded with an optical microscope. The test images were superimposed and measured using image analysis software. The statistical analysis showed that there were significantly higher horizontal changes for the MA than the DMA resins in M1, while there was none in M2. Regarding the vertical changes, there were significant differences between the baseline group and all relining and fabrication groups in all materials. Relining of directly fabricated temporary FDPs significantly reduces the effect of polymerization shrinkage and thus secures the position of the prepared teeth. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  19. Emulsion-cryogelation technique for fabricating a versatile toolbox of hierarchical polymeric monolith and its application in chromatography.

    Science.gov (United States)

    Li, Yaping; Qi, Li; Li, Nan; Ma, Huimin

    2016-05-15

    A novel poly (glycidyl methacrylate-co-ethylene dimethacrylate) monolith has been fabricated via the environmental friendly cryogelation-emulsion technique. The polymerization process is assisted by self-assembly of typical tri-block copolymer Pluronic F127 at sub-zero temperature using ice crystal as template, which can avoid consumption of organic porogenic solvents and thermal unstability of emulsion system. The developed monolith possesses hierarchical networks, which is confirmed by nitrogen adsorption measurement, mercury intrusion porosimetry, scanning electron microscopy and permeability testing. Further, the effect of the amounts of Pluronic F127 on the microstructure has been investigated. Moreover, the prepared polymer monolith undergoes acidic hydrolysis of epoxy groups into hydroxyl groups on the surface and its liquid chromatographic performance is explored by separating model analytes. The results indicate that the unique porous polymer monolith with hierarchical networks could be prepared via an organic porogen-free approach and used for analysis of polar and nonpolar molecules, extending the application of cryogelation-emulsion technique and methacrylate-based monolith. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    OpenAIRE

    Ioannis S. Tsagkalias; Triantafyllos K. Manios; Achilias, Dimitris S.

    2017-01-01

    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) d...

  1. 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

  2. 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.

  3. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Wenming [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Liu, Lukuan [School of the Environment, Jiangsu University, Zhenjiang 212013 (China); Zhou, Zhiping, E-mail: zhouzp@ujs.edu.cn [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Liu, Hong [Institute of Theoretical Chemistry, State Key Laboratory of Theoretical and Computational Chemistry, Jilin University, Changchun 130023 (China); Xie, Binze; Xu, Wanzhen [School of the Environment, Jiangsu University, Zhenjiang 212013 (China)

    2013-10-01

    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.

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

    National Research Council Canada - National Science Library

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

    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...

  6. 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.

  7. 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.

  8. 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...

  9. 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

  10. Polymeric microspheres

    Science.gov (United States)

    Walt, David R.; Mandal, Tarun K.; Fleming, Michael S.

    2004-04-13

    The invention features core-shell microsphere compositions, hollow polymeric microspheres, and methods for making the microspheres. The microspheres are characterized as having a polymeric shell with consistent shell thickness.

  11. Characterizing Fullerene Nanoparticles in Aqueous Suspensions

    Science.gov (United States)

    Studies have indicated that fullerenes can form stable colloidal suspensions in water when introduced to the aqueous phase through solvent exchange, sonication, or extended mixing. The colloidal suspensions created using these techniques have effective aqueous phase concentratio...

  12. Toward living radical polymerization.

    Science.gov (United States)

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

    2008-09-01

    Radical polymerization is one of the most widely used processes for the commercial production of high-molecular-weight polymers. The main factors responsible for the preeminent position of radical polymerization are the ability to polymerize a wide array of monomers, tolerance of unprotected functionality in monomer and solvent, and compatibility with a variety of reaction conditions. Radical polymerization is simple to implement and inexpensive in relation to competitive technologies. However, conventional radical polymerization severely limits the degree of control that researchers can assert over molecular-weight distribution, copolymer composition, and macromolecular architecture. This Account focuses on nitroxide-mediated polymerization (NMP) and polymerization with reversible addition-fragmentation chain transfer (RAFT), two of the more successful approaches for controlling radical polymerization. These processes illustrate two distinct mechanisms for conferring living characteristics on radical polymerization: reversible deactivation (in NMP) and reversible or degenerate chain transfer (in RAFT). We devised NMP in the early 1980s and have exploited this method extensively for the synthesis of styrenic and acrylic polymers. The technique has undergone significant evolution since that time. New nitroxides have led to faster polymerization rates at lower temperatures. However, NMP is only applicable to a restricted range of monomers. RAFT was also developed at CSIRO and has proven both more robust and more versatile. It is applicable to the majority of monomers subject to radical polymerization, but the success of the polymerization depends upon the selection of the RAFT agent for the monomers and reaction conditions. We and other groups have proposed guidelines for selection, and the polymerization of most monomers can be well-controlled to provide minimal retardation and a high fraction of living chains by using one of just two RAFT agents. For example, a

  13. 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

  14. An investigation into force-moment calibration techniques applicable to a magnetic suspension and balance system. M.S. Thesis

    Science.gov (United States)

    Eskins, Jonathan

    1988-01-01

    The problem of determining the forces and moments acting on a wind tunnel model suspended in a Magnetic Suspension and Balance System is addressed. Two calibration methods were investigated for three types of model cores, i.e., Alnico, Samarium-Cobalt, and a superconducting solenoid. Both methods involve calibrating the currents in the electromagnetic array against known forces and moments. The first is a static calibration method using calibration weights and a system of pulleys. The other method, dynamic calibration, involves oscillating the model and using its inertia to provide calibration forces and moments. Static calibration data, found to produce the most reliable results, is presented for three degrees of freedom at 0, 15, and -10 deg angle of attack. Theoretical calculations are hampered by the inability to represent iron-cored electromagnets. Dynamic calibrations, despite being quicker and easier to perform, are not as accurate as static calibrations. Data for dynamic calibrations at 0 and 15 deg is compared with the relevant static data acquired. Distortion of oscillation traces is cited as a major source of error in dynamic calibrations.

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

    Energy Technology Data Exchange (ETDEWEB)

    Pople, John A

    2001-03-22

    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) < 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.

  16. Condensation Polymerization

    Indian Academy of Sciences (India)

    Condensation polymerizations, as thename suggests, utilizes bond-forming reactions that generatea small molecule condensate, which often needs to be continuouslyremoved to facilitate the formation of the polymer. Inthis article, I shall describe some of the essential principles ofcondensation polymerizations or more ...

  17. 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.

  18. 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.

  19. 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.

  20. 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...

  1. Independent suspension

    National Research Council Canada - National Science Library

    Chaikin, Don

    1992-01-01

    ... independent suspension. INDEPENDENCE! An independent system is simply one in which each of the vehicle's wheels is free to react totally separate from any of the other wheels. If the right rear wheel hits a bump, the left rear wheel is undisturbed. Since the whole car does not bounce and shake every time one of the wheels hits a potho...

  2. Differences in estimates of size distribution of beryllium powder materials using phase contrast microscopy, scanning electron microscopy, and liquid suspension counter techniques

    Directory of Open Access Journals (Sweden)

    Day Gregory A

    2007-02-01

    Full Text Available Abstract Accurate characterization of the physicochemical properties of aerosols generated for inhalation toxicology studies is essential for obtaining meaningful results. Great emphasis must also be placed on characterizing particle properties of materials as administered in inhalation studies. Thus, research is needed to identify a suite of techniques capable of characterizing the multiple particle properties (i.e., size, mass, surface area, number of a material that may influence toxicity. The purpose of this study was to characterize the morphology and investigate the size distribution of a model toxicant, beryllium. Beryllium metal, oxides, and alloy particles were aerodynamically size-separated using an aerosol cyclone, imaged dry using scanning electron microscopy (SEM, then characterized using phase contrast microscopy (PCM, a liquid suspension particle counter (LPC, and computer-controlled SEM (CCSEM. Beryllium metal powder was compact with smaller sub-micrometer size particles attached to the surface of larger particles, whereas the beryllium oxides and alloy particles were clusters of primary particles. As expected, the geometric mean (GM diameter of metal powder determined using PCM decreased with aerodynamic size, but when suspended in liquid for LPC or CCSEM analysis, the GM diameter decreased by a factor of two (p

  3. Mechanistic Features of the TiO2 Heterogeneous Photocatalysis of Arsenic and Uranyl Nitrate in Aqueous Suspensions Studied by the Stopped-Flow Technique.

    Science.gov (United States)

    Meichtry, Jorge M; Levy, Ivana K; Mohamed, Hanan H; Dillert, Ralf; Bahnemann, Detlef W; Litter, Marta I

    2016-03-16

    The dynamics of the transfer of electrons stored in TiO2 nanoparticles to As(III) , As(V) , and uranyl nitrate in water was investigated by using the stopped-flow technique. Suspensions of TiO2 nanoparticles with stored trapped electrons (etrap (-) ) were mixed with solutions of acceptor species to evaluate the reactivity by following the temporal evolution of etrap (-) by the decrease in the absorbance at λ=600 nm. The results indicate that As(V) and As(III) cannot be reduced by etrap (-) under the reaction conditions. In addition, it was observed that the presence of As(V) and As(III) strongly modified the reaction rate between O2 and etrap (-) : an increase in the rate was observed if As(V) was present and a decrease in the rate was observed in the presence of As(III) . In contrast with the As system, U(VI) was observed to react easily with etrap (-) and U(IV) formation was observed spectroscopically at λ=650 nm. The possible competence of U(VI) and NO3 (-) for their reduction by etrap (-) was analyzed. The inhibition of the U(VI) photocatalytic reduction by O2 could be attributed to the fast oxidation of U(V) and/or U(IV) . © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yabin [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin, 150001 (China); Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, Qinghai, 810008 (China); Liu, Zhong [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, Qinghai, 810008 (China); Huang, Yudong, E-mail: ydhuang.hit1@yahoo.com.cn [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin, 150001 (China); Qi, Yutai, E-mail: inqdsd@yahoo.com.cn [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin, 150001 (China)

    2015-11-30

    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.

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

    Science.gov (United States)

    Sahoo, Subhashree; Chakraborti, Chandra Kanti; Mishra, Subash Chandra

    2011-01-01

    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 (2θ) 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. PMID:22171318

  6. 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.

  7. 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.

  8. 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.

  9. Developments in polymerization lamps.

    Science.gov (United States)

    Jiménez-Planas, Amparo; Martín, Juan; Abalos, Camilo; Llamas, Rafael

    2008-02-01

    Polymerization shrinkage of composite resins and the consequent stress generated at the composite-tooth interface continue to pose a serious clinical challenge. The development of high-intensity halogen lamps and the advent of curing units providing higher energy performance, such as laser lamps, plasma arc units, and, most recently, light-emitting diode (LED) curing units, have revolutionized polymerization lamp use and brought major changes in light-application techniques. A comprehensive review of the literature yielded the following conclusions: (1) the most reliable curing unit for any type of composite resin is the high-density halogen lamp, fitted with a programming device to enable both pulse-delay and soft-start techniques; (2) if any other type of curing unit is used, information must be available on the compatibility of the unit with the composite materials to be used; (3) polymerization lamp manufacturers need to focus on the ongoing development of LED technology; (4) further research is required to identify the most reliable light-application techniques.

  10. 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.

  11. 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...

  12. High temperature structural, polymeric foams from high internal emulsion polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Hoisington, M.A.; Duke, J.R.; Apen, P.G.

    1996-02-01

    In 1982, a high internal phase emulsion (HIPE) polymerization process to manufacture microcellular, polymeric foam systems was patented by Unilever. This patent discloses a polymerization process that occurs in a water-in-oil emulsion in which the water represents at least 76% of the emulsion by volume. The oil phase consists of vinyl monomers such as styrene and acrylates that are crosslinked by divinyl monomers during polymerization. After polymerization and drying to remove the water phase, the result is a crosslinked polymer foam with an open cell microstructure that is homogeneous throughout in terms of morphology, density, and mechanical properties. Since 1982, numerous patents have examined various HIPE polymerized foam processing techniques and applications that include absorbents for body fluids, cleaning materials, and ion exchange systems. All the published HIPE polymerized foams have concentrated on materials for low temperature applications. Copolymerization of styrene with maleic anhydride and N-substituted maleimides to produce heat resistant thermoplastics has been studied extensively. These investigations have shown that styrene will free radically copolymerize with N-substituted maleimides to create an alternating thermoplastic copolymer with a Tg of approximately 200{degrees}C. However, there are many difficulties in attempting the maleimide styrene copolymerization in a HIPE such as lower polymerization temperatures, maleimide solubility difficulties in both styrene and water, and difficulty obtaining a stable HIPE with a styrene/maleimide oil phase. This work describes the preparation of copolymer foams from N-ethylmaleimide and Bis(3-ethyl-5-methyl-4-maleimide-phenyl)methane with styrene based monomers and crosslinking agents.

  13. 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.

  14. Shear History Extensional Rheology Experiment II (SHERE II) Microgravity Rheology with Non-Newtonian Polymeric Fluids

    Science.gov (United States)

    Jaishankar, Aditya; Haward, Simon; Hall, Nancy Rabel; Magee, Kevin; McKinley, Gareth

    2012-01-01

    The primary objective of SHERE II is to study the effect of torsional preshear on the subsequent extensional behavior of filled viscoelastic suspensions. Microgravity environment eliminates gravitational sagging that makes Earth-based experiments of extensional rheology challenging. Experiments may serve as an idealized model system to study the properties of lunar regolith-polymeric binder based construction materials. Filled polymeric suspensions are ubiquitous in foods, cosmetics, detergents, biomedical materials, etc.

  15. 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

  16. 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......With the advent of the controlled free radical polymerization techniques and the novel highly efficient coupling technique (“click chemistry”1) a number of new design principles for biomedical polymeric materials emerge. We’ve recently initiated a comprehensive research programme aiming...

  17. Polymeric slot waveguide for photonics sensing

    Science.gov (United States)

    Chovan, J.; Uherek, F.

    2016-12-01

    Polymeric slot waveguide for photonics sensing was designed, simulated and studied in this work. The polymeric slot waveguide was designed on commercial Ormocer polymer platform and operates at visible 632.8 nm wavelength. Designed polymeric slot waveguide detects the refractive index change of the ambient material by evanescent field label-free techniques. The motivation for the reported work was to design a low-cost polymeric slot waveguide for sensing arms of integrated Mach-Zehnder interferometer optical sensor with reduced temperature dependency. The minimal dimensions of advanced sensing slot waveguide structure were designed for researcher direct laser writing fabrication by nonlinear two-photon polymerization. The normalized effective refractive index changes of TE and TM fundamental modes in polymeric slot waveguide and slab waveguides were compared. The sensitivity of the normalized effective refractive index changes of TE and TM fundamental modes on refractive index changes of the ambient material was investigated by glucose-water solutions.

  18. 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)

  19. Positive selection of Wharton's jelly-derived CD105(+) cells by MACS technique and their subsequent cultivation under suspension culture condition: A simple, versatile culturing method to enhance the multipotentiality of mesenchymal stem cells.

    Science.gov (United States)

    Amiri, Fatemeh; Halabian, Raheleh; Dehgan Harati, Mozhgan; Bahadori, Marzie; Mehdipour, Ahmad; Mohammadi Roushandeh, Amaneh; Habibi Roudkenar, Mehryar

    2015-05-01

    Wharton's jelly (WJ), an appropriate source of mesenchymal stem cells (MSCs), has been shown to have a wide array of therapeutic applications. However, the WJ-derived MSCs are very heterogeneous and have limited expression of pluripotency markers. Hence, improvement of their culture condition would promote the efficiency of WJ-MSCs. This study aims to employ a simple method of cultivation to obtain WJ-MSCs which express more pluripotency markers. CD105(+) cells were separated by magnetic-associated (activated) cell sorting from umbilical cord mucous tissue. CD105(+) cells were added to Methocult medium diluted in α-minimum essential medium (α-MEM) and seeded in poly(2-hydroxyethyl methacrylate) (poly-HEMA)-coated plates for suspension culture preparation. Differentiation capacity of isolated cells was evaluated in the presence of differentiation-inducing media. The expression of pluripotency markers such as Oct3/4, Nanog, and Sox2 was also analyzed by RT-PCR and western blot techniques. Moreover, immunocytochemistry was performed to detect alpha-smooth muscle actin (antigene) (α-SMA) protein. WJ-MSCs grew homogeneously and formed colonies when cultured under suspension culture conditions (Non-adhesive WJ-MSCs). They maintained their growth ability in both adherent and suspension cultures for several passages. Non-adhesive WJ-MSCs expressed Oct3/4, Nanog, and Sox2 both at transcriptional and translational levels in comparison to those cultured in conventional adherent cultures. They also expressed α-SMA protein. In this study, we isolated WJ-MSCs using a slightly modified culture condition. Our simple non-genetic method resulted in a homogeneous population of WJ-MSCs, which highly expressed pluripotency markers. In the future, more multipotent WJ-MSCs can be harnessed as a non-embryonic source of MSCs in MSC-based cell therapy.

  20. Suspension Threads.

    Science.gov (United States)

    De Masi, Elen C D J; De Masi, Flávia D J; De Masi, Roberta D J

    2016-12-01

    Suture threads are a minimally invasive surgical technique for facial rejuvenation. Its use was initiated by Sulamanidze et al with propylene after Serdev introduced suture with polycaproamide; however, these types of suture increased inflammatory reaction. For correction of the aging face, surgeons are devising more procedures with fewer incisions and shorter postoperative recovery periods. Many of these procedures use absorbable and nonabsorbable sutures in the dermis and subcutis to lift lax skin. The polydioxanone suture is currently a great option for antiaging treatment, because besides the ease of applicability and good results, it also has a low incidence of adverse reactions. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  1. Suspension as an Emergency Power

    National Research Council Canada - National Science Library

    Amanda L. Tyler

    2009-01-01

    ... Legislation B. Suspension During Reconstruction: Putting Down the Klan in South Carolina IV. UNDERSTANDING SUSPENSION AS AN EMERGENCY POWER A. Reading the Suspension Clause in Context B. Giving Meaning to the Suspension Power C. Mapping the Suspension Clause Within the Constitution V. SUSPENSION AND THE SEPARATION OF POWERS CONCLUSION [A] suspensio...

  2. Modeling and analytical simulation of anterior polymerization in the ...

    African Journals Online (AJOL)

    The study shows that the Frank-Kamenetskii number and frequency factors of the two reactions have significant effects on the propagation of the polymerization wave. Keywords: Polymerization, anterior polymerization, polymers, Arrhenius kinetics, parameter-expanding method, eigenfunctions expansion technique ...

  3. X-ray Mapping of Dynamic Suspensions

    Science.gov (United States)

    Gholami, Mohammad; Lenoir, Nicolas; Ovarlez, Guillaume; Hormozi, Sarah

    2016-11-01

    Dense non-colloidal suspensions are materials with broad application both in industrial processes and natural phenomena. In most of these applications, the suspensions are either far from equilibrium or strongly non-Newtonian (i.e., non-colloidal particles are suspended in non-Newtonian fluid) meaning that the flow kinetics are not only strain-dependent but also strain-rate dependent. Therefore, experimental techniques must be developed to analyze the flows of these complex suspensions over a wide range of steady and transient shear rates. Techniques such as Nuclear Magnetic Resonance/Imaging (NMR/I) are inapplicable due to low sampling frequency and low image resolution (typically 10 minutes per averaged NMR image of 1x1cm). We introduce a new technique using an X-ray/CT-scan system to study dynamic suspensions. We show our recent results on the application of this technique for the study of shear induced migration of particles in a yield stress matrix fluid in a wide-gap cylindrical Couette cell. This work opens new avenues to study dynamic non-colloidal suspensions and the suspensions with other types of nonlinear suspending fluids such as viscoelastic and shear thickening fluids. NFS(CBET-1554044-CAREER).

  4. Optical analysis of red blood cell suspension

    Science.gov (United States)

    Szołna, Alicja A.; Grzegorzewski, Bronisław

    2008-12-01

    The optical properties of suspensions of red blood cells (RBCs) were studied. Fresh human venues blood was obtained from adult healthy donors. RBCs were suspended in isotonic salt solution, and in autologous plasma. Suspensions with haematocrit 0.25 - 3% were investigated. Novel technique was proposed to determine the scattering coefficient μs for the suspensions. The intensity of He-Ne laser light transmitted through a wedge-shape container filled with a suspension was recorded. To find the dependence of the intensity on the thickness of the sample the container was moved horizontally. The dependence of μs on the haematocrit was determined for RBCs suspended in the isotonic salt solution. RBCs suspended in plasma tend to form rouleaux. For the RBCs suspended in plasma, the scattering coefficient as a function of time was obtained. It is shown that this technique can be useful in the study of rouleaux formation.

  5. Polymeric nanoparticles: the future of nanomedicine.

    Science.gov (United States)

    Banik, Brittany L; Fattahi, Pouria; Brown, Justin L

    2016-01-01

    Polymeric nanoparticles (NPs) are one of the most studied organic strategies for nanomedicine. Intense interest lies in the potential of polymeric NPs to revolutionize modern medicine. To determine the ideal nanosystem for more effective and distinctly targeted delivery of therapeutic applications, particle size, morphology, material choice, and processing techniques are all research areas of interest. Utilizations of polymeric NPs include drug delivery techniques such as conjugation and entrapment of drugs, prodrugs, stimuli-responsive systems, imaging modalities, and theranostics. Cancer, neurodegenerative disorders, and cardiovascular diseases are fields impacted by NP technologies that push scientific boundaries to the leading edge of transformative advances for nanomedicine. © 2015 Wiley Periodicals, Inc.

  6. A Survey on Synthesis Processes of Structured Materials for Biomedical Applications: Iron-based Magnetic Nanoparticles, Polymeric Materials and Polymerization Processes.

    Science.gov (United States)

    Neto, Weslany Silvério; Jensen, Alan Thyago; Ferreira, Gabriella Ribeiro; Valadares, Leonardo Fonseca; Gambetta, Rossano; Gonçalves, Sílvia Belém; Machado, Fabricio

    2015-01-01

    Magnetic materials based on iron oxides are extensively designed for several biomedical applications. Heterogeneous polymerization processes are powerful tools for the production of tailored micro-sized and nanosized magneto-polymeric particles. Although several polymerization processes have been adopted along the years, suspension, emulsion and miniemulsion systems deserve special attention due to its ability to produce spherical polymer particles containing magnetic nanoparticles homogeneously dispersed into the polymer thermoplastic matrices. The main objective of this paper is to review the main methods of synthesis of iron-based magnetic nanoparticles and to illustrate how typical polymerization processes in different dispersion medium can be successfully used to produce engineered magnetic core-shell structures. It is exemplified the use of suspension, emulsion and miniemulsion polymerization processes in order to support experimental methodologies required for the production of magnetic polymer particles intended for biomedical applications such as intravascular embolization treatments, drug delivery systems and hyperthermia treatment.

  7. 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...

  8. "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...

  9. Electrorheology of nanofiber suspensions

    National Research Council Canada - National Science Library

    Yin, Jianbo; Zhao, Xiaopeng

    2011-01-01

    .... In this review, we especially focus on the recent researches on electrorheology of various nanofiber-based suspensions, including inorganic, organic, and inorganic/organic composite nanofibers...

  10. 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.

  11. Novel ionic polymeric hydraulic actuators

    Science.gov (United States)

    Shahinpoor, Mohsen; Kim, Kwang J.

    2001-07-01

    It is now well recognized that a strip of ionic polymer- metal composite (IPMC) exhibits a spontaneous bending capability under the influence of an electric potential. A key observation is the appearance and disappearance of water on the expansion and contraction surfaces of the strip, respectively. Such water appearing/disappearing activities occur near the permeable metal electrodes. The imposition of en elctric field causes the mobile cations that are conjugated to the polymeric anions to undergo electrophoretic dynamic migration that can result in local deformation of the material. Such an electrophoretic behavior of the IPMC causes the water to leak out of the permeable electroded boundary so as to lower the actuation performance. This situation is similar to a leaking hydraulic actuator (hydraulic jack), which has the highest force density notwithstanding the compressor unit weight. Herein, a new category of actuators as ionic polymeric hydraulic actuators (IPHA's) is defined. The IPMC is a good example of such ionic polymeric hydraulic actuators. The advantage of ionic polymeric hydraulic actuators is their potential to generate substantially high force densities, theoretically better than current hydraulic actuators. Based upon this ionic polymer hydraulic actuator concept, a certain manufacturing technique was developed to increase the force density of the conventional IPMC's by a factor of two (100% improvement in force). This technology and associated experimental results are presented in this paper.

  12. Reducing Transmitted Vibration Using Delayed Hysteretic Suspension

    Directory of Open Access Journals (Sweden)

    Lahcen Mokni

    2011-01-01

    Full Text Available Previous numerical and experimental works show that time delay technique is efficient to reduce transmissibility of vibration in a single pneumatic chamber by controlling the pressure in the chamber. The present work develops an analytical study to demonstrate the effectiveness of such a technique in reducing transmitted vibrations. A quarter-car model is considered and delayed hysteretic suspension is introduced in the system. Analytical predictions based on perturbation analysis show that a delayed hysteretic suspension enhances vibration isolation comparing to the case where the nonlinear damping is delay-independent.

  13. Research of a labelling technique for using {sup 99m}Tc as an adsorbable radiotracer for hydrodynamics studies of fine sediments in suspension

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Sung Hee; Kim, Jong Bum; Moon, Jin Ho; Hong, Young Don [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2010-03-15

    The radioisotope labelling study was carried out for the sediment transport investigation. The fate of suspended solid materials is deeply related to the harbour siltation and the shoreline deformation that take place as a result of the artificial development of coastal area. In the experiment, {sup 99m}TcO{sub 4}{sup -} was chemically reduced and labelled in such a way that the labelled particles have the similar settling characteristics with the natural sediment. The radioisotope labelling techniques can be widely used for the natural resource exploration where the hydraulic dynamics of underground water and surface water are of importance.

  14. Suspension Trauma / Orthostatic Intolerance

    Science.gov (United States)

    ... Emphasis Programs Directives Severe Violators TOPICS By Sector Construction Health Care Agriculture Maritime Oil and Gas Federal ... such fatalities often are referred to as "harnessinduced pathology" or "suspension trauma." Signs & symptoms that may be ...

  15. Urinary incontinence - retropubic suspension

    Science.gov (United States)

    ... your doctor will have you try bladder retraining, Kegel exercises, medicines, or other options. If you tried ... retropubic colposuspension; Needle suspension; Burch colposuspension Patient Instructions Kegel exercises - self-care Self catheterization - female Suprapubic catheter ...

  16. 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...

  17. Articulated suspension system

    Science.gov (United States)

    Bickler, Donald B. (Inventor)

    1989-01-01

    The invention provides a rough terrain vehicle which maintains a substantially constant weight, and therefore traction, on all wheels, despite one wheel moving considerably higher or lower than the others, while avoiding a very soft spring suspension. The vehicle includes a chassis or body to be supported and a pair of side suspensions at either side of the body. In a six wheel vehicle, each side suspension includes a middle wheel, and front and rear linkages respectively coupling the front and rear wheels to the middle wheel. A body link pivotally connects the front and rear linkages together, with the middle of the body link rising or falling by only a fraction of the rise or fall of any of the three wheels. The body link pivotally supports the middle of the length of the body. A transverse suspension for suspending the end of the body on the side suspensions includes a middle part pivotally connected to the body about a longitudinal axis and opposite ends each pivotally connected to one of the side suspensions along at least a longitudinal axis.

  18. Tangential Ultrafiltration of Aqueous "Saccharomyces Cerevisiae" Suspensions

    Science.gov (United States)

    Silva, Carlos M.; Neves, Patricia S.; Da Silva, Francisco A.; Xavier, Ana M. R. B.; Eusebio, M. F. J.

    2008-01-01

    Experimental work on ultrafiltration is presented to illustrate the practical and theoretical principles of this separation technique. The laboratory exercise comprises experiments with pure water and with aqueous "Saccharomyces cerevisiae" (from commercial Baker's yeast) suspensions. With this work students detect the characteristic phenomena…

  19. Step-Growth Polymerization.

    Science.gov (United States)

    Stille, J. K.

    1981-01-01

    Following a comparison of chain-growth and step-growth polymerization, focuses on the latter process by describing requirements for high molecular weight, step-growth polymerization kinetics, synthesis and molecular weight distribution of some linear step-growth polymers, and three-dimensional network step-growth polymers. (JN)

  20. 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...

  1. Energy-Efficient and Environmentally Sound Technique of Emulsification and Phase Inversion for Producing Stable Droplets – Application of Membrane Emulsification to Polymerization: A Review

    Directory of Open Access Journals (Sweden)

    Sultan Ali

    2012-12-01

    Full Text Available Emulsification plays an important role in the formation of many products such as milk products, pharmaceuticals, lubricants, paints, dyes, and many food items. Their application in industry such as mining, crude oil extraction, pulp and paper, textile, and polymer, is immense. Over the last two decades there has been a growing interest in making emulsions by a new technique known as membrane emulsification. This is because it requires lesser energy as compared to the other conventional turbulence based methods like homogenization and rotor-stator systems, with the added advantage of producing droplets of a given size by just selecting the average pore size of the membrane. It is the distinguished feature of membrane emulsification that the resulting droplet size is controlled primarily by the membrane type and its pore size and not by the generation of turbulent droplet breakup. This article provides a review of the currently available emulsification processes with special focus on polymer emulsification. The main characteristics of emulsification processes including membrane emulsification process and its principles, influence of process parameters, industrial applications as well as an outlook to further improvement of the processes are discussed.

  2. Autologous epidermal cell suspension: A promising treatment for chronic wounds.

    Science.gov (United States)

    Zhao, Hongliang; Chen, Yan; Zhang, Cuiping; Fu, Xiaobing

    2016-02-01

    Chronic wounds have become an increasing medical and economic problem of aging societies because they are difficult to manage. Skin grafting is an important treatment method for chronic wounds, which are refractory to conservative therapy. The technique involving epidermal cell suspensions was invented to enable the possibility of treating larger wounds with only a small piece of donor skin. Both uncultured and cultured autologous epidermal cell suspensions can be prepared and survive permanently on the wound bed. A systematic search was conducted of EMBASE, Cochrane Library, PubMed and web of science by using Boolean search terms, from the establishment of the database until May 31, 2014. The bibliographies of all retrieved articles in English were searched. The search terms were: (epithelial cell suspension OR keratinocyte suspension) and chronic and wound. From the included, 6 studies are descriptive interventions and discussed the use of autologous keratinocyte suspension to treat 61 patients' chronic wound. The various methods of preparation of epidermal cell suspension are described. The advantages and shortcomings of different carriers for epidermal cell suspensions are also summarised. Both uncultured and cultured autologous epidermal cell suspensions have been used to treat chronic wounds. Although the limitations of these studies include the small number of patient populations with chronic wounds and many important problems that remain to be solved, autologous epidermal cell suspension is a promising treatment for chronic wounds. Copyright © 2015 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.

  3. Estimation of tracked vehicle suspension parameters

    Directory of Open Access Journals (Sweden)

    Aldélio Bueno Caldeira

    2017-02-01

    Full Text Available This work aims to estimate the suspension stiffness and damping coefficient of a tracked vehicle by using an inverse problem technique based on Particle Swarm Optimization (PSO and on Random Restricted Window (R2W. The tracked vehicle has ten road wheels. Each road wheel is linked to a passive and independent suspension. A half car model with seven degrees of freedom describes the bounce and pitch dynamics of the chassis and the vertical dynamics of the wheels. Bounce and pitch accelerations are evaluated when the vehicle traverses a bump terrain. The inverse problem approach minimizes the total quadratic error between estimated and pseudo-experimental data for bounce and pitch accelerations. The viability of a field experiment to estimate the suspension parameters is analyzed, as well as the performance of the employed optimization methods and the effects of the noise on pseudo-experimental data.

  4. Comparison of atomic absorption, mass and X-ray spectrometry techniques using dissolution-based and solid sampling methods for the determination of silver in polymeric samples

    Energy Technology Data Exchange (ETDEWEB)

    Schrijver, Isabel de [Ghent University, Department of Analytical Chemistry, Krijgslaan 281-S12, B-9000 Ghent (Belgium); University College West-Flanders, Department of Industrial Engineering and Technology, Research group EnBiChem, Graaf Karel de Goedelaan 5, B-8500 Kortrijk (Belgium); Aramendia, Maite; Vincze, Laszlo [Ghent University, Department of Analytical Chemistry, Krijgslaan 281-S12, B-9000 Ghent (Belgium); Resano, Martin [University of Zaragoza, Department of Analytical Chemistry, Pedro Cerbuna 12, E-50009 Zaragoza (Spain); Dumoulin, Ann [University College West-Flanders, Department of Industrial Engineering and Technology, Research group EnBiChem, Graaf Karel de Goedelaan 5, B-8500 Kortrijk (Belgium); Vanhaecke, Frank [Ghent University, Department of Analytical Chemistry, Krijgslaan 281-S12, B-9000 Ghent (Belgium)], E-mail: Frank.Vanhaecke@UGent.be

    2007-11-15

    In this work, the capabilities and limitations of solid sampling techniques - laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS), wavelength dispersive X-ray fluorescence spectrometry (WD-XRFS) and solid sampling electrothermal atomic absorption spectrometry (SS-ETAAS) - for the determination of silver in polymers have been evaluated and compared to those of acid digestion and subsequent Ag determination using pneumatic nebulization ICPMS (PN-ICPMS) or flame AAS (FAAS). In a first stage, two dissolution procedures were examined: conventional acid digestion in a Kjeldahl flask and the combination of dry ashing and microwave-assisted digestion. Accurate results for Ag could be obtained, although occasionally, problems of analyte losses and/or incomplete dissolution were observed. LA-ICPMS shows potential for direct analysis of solid materials, but calibration was found to be difficult. A polypropylene sample was used as standard. This approach provided satisfactory results for other polypropylene samples and even for other types of plastics, provided that the {sup 13}C{sup +} signal was used as internal reference, correcting for variations in ablation efficiency. However, the results for polyoxymethylene were overestimated. Similar calibration problems appeared with WD-XRFS, due to differences in absorption efficiency of X-rays. In this case, the accuracy could be improved by using a matrix correction procedure, which however required the matrix composition to be known into sufficient detail. SS-ETAAS, proved to be a fast approach that allowed accurate determination of Ag in polymers using aqueous standard solutions for calibration. Due to the high Ag content and the excellent sensitivity, the use of a 3-field mode Zeeman-effect background correction system was essential for the extension of the working range.

  5. 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.

  6. 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...... 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...

  7. 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

  8. Roll- and pitch-plane coupled hydro-pneumatic suspension. Part 1: Feasibility analysis and suspension properties

    Science.gov (United States)

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

    2010-03-01

    Passive fluidically coupled suspensions have been considered to offer a promising alternative solution to the challenging design of a vehicle suspension system. A theoretical foundation, however, has not been established for fluidically coupled suspension to facilitate its broad applications to various vehicles. The first part of this study investigates the fundamental issues related to feasibility and properties of the passive, full-vehicle interconnected, hydro-pneumatic suspension configurations using both analytical and simulation techniques. Layouts of various interconnected suspension configurations are illustrated based on two novel hydro-pneumatic suspension strut designs, both of which provide a compact design with a considerably large effective working area. A simplified measure, vehicle property index, is proposed to permit a preliminary evaluation of different interconnected suspension configurations using qualitative scaling of the bounce-, roll-, pitch- and warp-mode stiffness properties. Analytical formulations for the properties of unconnected and three selected X-coupled suspension configurations are derived, and simulation results are obtained to illustrate their relative stiffness and damping properties in the bounce, roll, pitch and warp modes. The superior design flexibility feature of the interconnected hydro-pneumatic suspension is also discussed through sensitivity analysis of a design parameter, namely the annular piston area of the strut. The results demonstrate that a full-vehicle interconnected hydro-pneumatic suspension could provide enhanced roll- and pitch-mode stiffness and damping, while retaining the soft bounce- and warp-mode properties. Such an interconnected suspension thus offers considerable potential in realising enhanced decoupling among the different suspension modes.

  9. Transient inter-cellular polymeric linker.

    Science.gov (United States)

    Ong, Siew-Min; He, Lijuan; Thuy Linh, Nguyen Thi; Tee, Yee-Han; Arooz, Talha; Tang, Guping; Tan, Choon-Hong; Yu, Hanry

    2007-09-01

    Three-dimensional (3D) tissue-engineered constructs with bio-mimicry cell-cell and cell-matrix interactions are useful in regenerative medicine. In cell-dense and matrix-poor tissues of the internal organs, cells support one another via cell-cell interactions, supplemented by small amount of the extra-cellular matrices (ECM) secreted by the cells. Here we connect HepG2 cells directly but transiently with inter-cellular polymeric linker to facilitate cell-cell interaction and aggregation. The linker consists of a non-toxic low molecular-weight polyethyleneimine (PEI) backbone conjugated with multiple hydrazide groups that can aggregate cells within 30 min by reacting with the aldehyde handles on the chemically modified cell-surface glycoproteins. The cells in the cellular aggregates proliferated; and maintained the cortical actin distribution of the 3D cell morphology while non-aggregated cells died over 7 days of suspension culture. The aggregates lost distinguishable cell-cell boundaries within 3 days; and the ECM fibers became visible around cells from day 3 onwards while the inter-cellular polymeric linker disappeared from the cell surfaces over time. The transient inter-cellular polymeric linker can be useful for forming 3D cellular and tissue constructs without bulk biomaterials or extensive network of engineered ECM for various applications.

  10. Results of Abductor Pollicis Longus Suspension Ligamentoplasty for Treatment of Advanced First Carpometacarpal Arthritis

    National Research Council Canada - National Science Library

    Lee, Hyun-Joo; Kim, Poong-Taek; Deslivia, Maria Florencia; Jeon, In-Ho; Lee, Suk-Joong; Nam, Sang-Jin

    2015-01-01

    Suspension ligamentoplasty using abductor pollicis longus (APL) tendon without bone tunneling, was introduced as one of the techniques for treatment of advanced first carpometacarpal (CMC) arthritis...

  11. 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.

  12. Viscosity of colloidal suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, E.G.D. [Rockefeller Univ., New York, NY (United States); Schepper, I.M. de [Delft Univ. of Technology (Netherlands)

    1995-12-31

    Simple expressions are given for the effective Newtonian viscosity as a function of concentration as well as for the effective visco-elastic response as a function of concentration and imposed frequency, of monodisperse neutral colloidal suspensions over the entire fluid range. The basic physical mechanisms underlying these formulae are discussed. The agreement with existing experiments is very good.

  13. Flywheel Magnetic Suspension Developments

    Science.gov (United States)

    Palazzolo, Alan; Kenny, Andrew; Sifford, Curtiss; Thomas, Erwin; Bhuiyan, Mohammad; Provenza, Andrew; Kascak, Albert; Montague, Gerald; Lei, Shuliang; Kim, Yeonkyu; hide

    2002-01-01

    The paper provides an overview of many areas of the flywheel magnetic suspension (MS) R&D being performed at the Texas A&M Vibration Control and Electromechanics Lab (TAMU-VCEL). This includes system response prediction, actuator optimization and redundancy, controller realizations and stages, sensor enhancements and backup bearing reliability.

  14. Current trends in interfacial polymerization chemistry

    NARCIS (Netherlands)

    Raaijmakers, Michiel; Benes, Nieck Edwin

    2016-01-01

    Interfacial polymerization is an enabling technique for the large-scale production of ultrathin layers, hollow nanospheres and nanofibers. The availability of a wide range of suitable monomer reactants allows for the synthesis of an impressive collection of polymers, including polyamides,

  15. Cryonic Suspension and the Law.

    Science.gov (United States)

    Smith, George P.; Hall, Clare

    1987-01-01

    Analyzes three central problems which adversely affect use, development, and perfection of cryonic suspension of individuals: the extent to which a physician may be guilty of malpractice in assisting with a suspension; the need for a recognition of suspension; and the present effect of the law's anachronistic treatment of estate devolution upon a…

  16. Homogeneous vs heterogeneous polymerization catalysis revealed by single-particle fluorescence microscopy.

    Science.gov (United States)

    Esfandiari, N Melody; Blum, Suzanne A

    2011-11-16

    A high-sensitivity and high-resolution single-particle fluorescence microscopy technique differentiated between homogeneous and heterogeneous metathesis polymerization catalysis by imaging the location of the early stages of polymerization. By imaging single polymers and single crystals of Grubbs II, polymerization catalysis was revealed to be solely homogeneous rather than heterogeneous or both.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. Catalytic Polymerization of Acrylonitrile by Khulays Bentonite

    Directory of Open Access Journals (Sweden)

    Matar M. Al-Esaimi

    2007-04-01

    Full Text Available The aqueous polymerization of acrylonitrile (AN catalyzed with exchanged Khulays bentonite . The influence of various polymerization parameters ( e.g., concentrations of Potassium Persulfate (K2S2O8 and monomer , various of organic solvents, and different temperature has been investigated. It was found that the rate of polymerization of AN was found to be dependent on monomer concentration, initiator and temperature. The activation energy of polymerization was calculated .Thermal properties of the polymer were studied by TGA and DSC techniques. © 2007 CREC UNDIP. All rights reserved.Received: 5 February 2007; Received in revised: 19 April 2007; Accepted: 7 May 2007[How to Cite: M. M. Al-Esaimi. (2007. Catalytic Polymerization of Acrylonitrile by Khulays Bentonite. Bulletin of Chemical Reaction Engineering and Catalysis, 2 (2-3: 32-36.  doi:10.9767/bcrec.2.1.4.6-10][How to Link/DOI: http://dx.doi.org/10.9767/bcrec.2.1.4.6-10 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/4] 

  3. 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.

  4. Heteropolar Magnetic Suspension

    Science.gov (United States)

    Misovec, Kathleen; Johnson, Bruce; Downer, James; Eisenhaure, David; Hockney, Richard

    1990-01-01

    Compact permanent-magnet/electromagnet actuator has six degrees of freedom. Heteropolar magnetic actuator conceived for use as actively controlled vibration-isolating suspension device. Exerts forces along, and torques about, all three principal coordinate axes to resist all three components of translational vibration and all three components of rotational vibration. Inner cylinder suspended magnetically within outer cylinder. Electro-magnet coils interact with fields of permanent magnets to provide active control of suspending force and torque.

  5. 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.

  6. Evaluation of Antibacterial properties of the suspension of Ginger, Black Pepper, Vinegar, Honey and its application in Shelf life extension of Agaricus bisporus

    OpenAIRE

    Nitin Jain,; Himanshu Karaiya; Kumari Amrita; Swapnil Tiwari; Vishakha Dubey; C. Ramalingam

    2013-01-01

    Suspensions of vinegar, honey, black pepper and ginger were examined for antibacterial activity against Salmonella sp., Pseudomonas sp. and E.coli by agar well diffusion technique. The prepared suspensions were applied on Agaricus bisporus to evaluate suspensions effect for increasing the shelf life of it. Vinegar suspension showed better antibacterial effect and good result on Agaricus bisporus to increase its shelf life as compared to honey suspension. Enzymatic spoilage of Agaricus bisporu...

  7. 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....

  8. 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

  9. Polymeric coordination compounds

    Indian Academy of Sciences (India)

    Administrator

    Metal coordination polymers with one- and two-dimensional structures are of current interest due to their possible relevance to material science 1. In continuation of our previous studies 2,3, several new polymeric compounds are reported here. Among the complexes of silver with aminomethyl pyridine (amp) ...

  10. 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 ...

  11. Evaluation of the rotating disk sorptive extraction technique with polymeric sorbent for multiresidue determination of pesticides in water by ultra-high-performance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Donato, Filipe F; Bandeira, Nelson M G; Dos Santos, Gabriel C; Prestes, Osmar D; Adaime, Martha B; Zanella, Renato

    2017-09-22

    The use of pesticides has been associated with the increase of productivity of crops and control of vectors that cause diseases. However, excessive use of these compounds can cause human health and environmental problems, especially regarding to water resources. In this work, a method for multiresidue determination of 62 pesticides in surface water using the rotating disk sorptive extraction (RDSE) technique for sample preparation and ultra-high-performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) for analysis was optimized and validated. The parameters time and rotational disk velocity for the extraction step, types and amounts of sorbents, sample pH, ionic strength, time and velocity of the rotating disk in the desorption step, as well different desorption solvents were evaluated. The best results were obtained using 50mL of sample, acidified at pH 2.0, and 2.5g of sodium chloride. The selected velocity of rotation in the extraction step was 1600rpm for 80min. Inside the disk cavity, a small amount (20mg) of the polymeric sorbent Oasis(®) HLB was used. The desorption step was performed immerging the disk in 3mL of methanol and rotating the disk at 1600rpm for 60min. Procedural calibration curves showed linearity between 0.05 or 0.1-2μgL(-1), with r(2)>0.99 for all compounds. The method presented practical limit of quantification of 0.05 or 0.1μgL(-1) and suitable accuracy and precision, with recoveries from 70.1 to 119.9% and RSD≤20% for the levels 0.05, 0.1, 0.5 and 2μgL(-1). The validated method was applied to surface water samples from different river and residues of atrazine, azoxystrobin, clomazone, difenoconazole, epoxiconazole, propoxur, simazine and tebuconazole were found in the range of 0.06-0.35μgL(-1). The results indicate that the proposed method is suitable for the determination of pesticide residues in surface water, allowing an easy and simultaneously preparation of several samples with low material consumption

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

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Lopez, Jaime [Centro de Acustica Aplicada y Evaluacion No Destructivos (CAEND), CSIC-UPM, C/Serrano 144, 28006, Madrid (Spain); Shum, Ho Cheung, E-mail: ashum@hku.hk [Department of Mechanical Engineering, University of Hong Kong, 7/F Haking Wong Building, Pokfulam Road (Hong Kong); Elvira, Luis; Montero de Espinosa, Francisco [Centro de Acustica Aplicada y Evaluacion No Destructivos (CAEND), CSIC-UPM, C/Serrano 144, 28006, Madrid (Spain); Weitz, David A., E-mail: weitz@seas.harvard.edu [Department of Physics and School of Engineering and Applied Sciences, Harvard University, 9 and 15 Oxford Street, Cambridge, MA 02138 (United States)

    2013-01-15

    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: Black-Right-Pointing-Pointer Polymeric microparticles encapsulating MR fluids have been fabricated. Black-Right-Pointing-Pointer A double-emulsion-templated approach using microfluidic techniques has been used. Black-Right-Pointing-Pointer The monodisperse microparticles obtained are easily manipulated under magnetic field. Black-Right-Pointing-Pointer These microparticles have great potential for encapsulation-and-release applications.

  13. 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.

  14. 31 CFR 10.82 - Expedited suspension.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false Expedited suspension. 10.82 Section... INTERNAL REVENUE SERVICE Rules Applicable to Disciplinary Proceedings § 10.82 Expedited suspension. (a... suspension. A suspension under this section will commence on the date that written notice of the suspension...

  15. On the Complexity of Electrostatic Suspension Stabilization of Functionalized Silica Nanoparticles for Biotargeting and Imaging Applications

    Directory of Open Access Journals (Sweden)

    Lotta Bergman

    2008-01-01

    Full Text Available Different means of attaching streptavidin to surface functionalized silica particles with a diameter of 240 nm were investigated with special focus on suspension stability for electrostatically stabilized suspensions. The influence of two different fluorescent dyes covalently linked to the streptavidin on suspension stability was also studied. The results clearly show that the stability of the suspensions is crucially dependent on all functional groups present on the surface. The surface functions may either directly affect the effective surface charge if the functions contain charged groups, or indirectly by affecting the relative concentration of charged groups on the particle surface. Poly(ethylene imine-functionalized silica particles, where the polymer is grown by surface hyperbranching polymerization, are shown to be promising candidates for bioapplications, as the zeta-potential can remain strongly positive even under biologically relevant conditions.

  16. Triblock Terpolymers by Simultaneous Tandem Block Polymerization (STBP).

    Science.gov (United States)

    Freudensprung, Ines; Klapper, Markus; Müllen, Klaus

    2016-02-01

    A route of synthesizing triblock terpolymers in a one-pot, "one-step" polymerization approach is presented. The combination of two distinct polymerization techniques through orthogonal catalyst/initiator functionalities attached to a polymeric linker furnishes novel pathways to ABC-terpolymers. Both polymerizations have to be compatible regarding mechanisms, chosen monomers, and solvents. Here, an α,ω-heterobifunctional poly(ethylene glycol) serves as poly-meric catalyst/initiator to obtain triblock terpolymers of poly(norbornene)-b-poly(ethylene glycol)-b-poly(L-lactic acid) PNB-PEG-PLLA via simultaneous ring opening metathesis poly-merization and ring opening polymerization in a fast one-pot polymerization. Structural characterization of the polymers is provided via (1)H-, DOSY-, and (1)H,(1)H-COSY-NMR, while solution and thin film self-assembly are investigated by dynamic light scattering and atomic force microscopy. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. 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 ...

  18. Self Organization via Frontal Polymerization

    Science.gov (United States)

    Pojman, John

    2007-03-01

    There are three modes of frontal polymerization: Isothermal, Photo and Thermal Isothermal frontal polymerization (IFP) is a directional polymerization that utilizes the Norish-Trommsdorff effect, to produce optical gradient materials. When a solution of methyl methacrylate and thermal initiator contacts a polymer seed (a small piece of poly(methyl methacrylate), a viscous region is formed in which the polymerization rate is faster than in the bulk solution. PhotoFP is driven by a continuous input of light. Thermal frontal polymerization is the propagation of a localized reaction zone through the coupling of thermal transport with the Arrhenius dependence of the kinetics of an exothermic polymerization. We will examine IFP and its use in making Gradient Optical Materials (GRIN) and our work on elucidating the mechanism. We will consider how thermal frontal polymerization can be used rapid rapid repair, making gradient materials and to study interesting nonlinear modes of thermal front propagation.

  19. 48 CFR 209.407 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 3 2010-10-01 2010-10-01 false Suspension. 209.407... OF DEFENSE ACQUISITION PLANNING CONTRACTOR QUALIFICATIONS Debarment, Suspension, and Ineligibility 209.407 Suspension. ...

  20. Novel Complex Polymers with Carbazole Functionality by Controlled Radical Polymerization

    Directory of Open Access Journals (Sweden)

    Kazuhiro Nakabayashi

    2012-01-01

    Full Text Available This review summarizes recent advances in the design and synthesis of novel complex polymers with carbazole moieties using controlled radical polymerization techniques. We focus on the polymeric architectures of block copolymers, star polymers, including star block copolymers and miktoarm star copolymers, comb-shaped copolymers, and hybrids. Controlled radical polymerization of N-vinylcarbazole (NVC and styrene and (methacrylate derivatives having carbazole moieties is well advanced, leading to the well-controlled synthesis of complex macromolecules. Characteristic optoelectronic properties, assembled structures, and three-dimensional architectures are briefly introduced.

  1. Thermally bisignate supramolecular polymerization

    Science.gov (United States)

    Venkata Rao, Kotagiri; Miyajima, Daigo; Nihonyanagi, Atsuko; Aida, Takuzo

    2017-11-01

    One of the enticing characteristics of supramolecular polymers is their thermodynamic reversibility, which is attractive, in particular, for stimuli-responsive applications. These polymers usually disassemble upon heating, but here we report a supramolecular polymerization that occurs upon heating as well as cooling. This behaviour arises from the use of a metalloporphyrin-based tailored monomer bearing eight amide-containing side chains, which assembles into a highly thermostable one-dimensional polymer through π-stacking and multivalent hydrogen-bonding interactions, and a scavenger, 1-hexanol, in a dodecane-based solvent. At around 50 °C, the scavenger locks the monomer into a non-polymerizable form through competing hydrogen bonding. On cooling, the scavenger preferentially self-aggregates, unlocking the monomer for polymerization. Heating also results in unlocking the monomer for polymerization, by disrupting the dipole and hydrogen-bonding interactions with the scavenger. Analogous to 'upper and lower critical solution temperature phenomena' for covalently bonded polymers, such a thermally bisignate feature may lead to supramolecular polymers with tailored complex thermoresponsive properties.

  2. Gelcasting polymeric precursors for producing net-shaped graphites

    Science.gov (United States)

    Klett, James W.; Janney, Mark A.

    2005-02-15

    The present invention discloses a method for molding complex and intricately shaped high density monolithic carbon, carbon-carbon, graphite, and thermoplastic composites using gelcasting technology. The method comprising a polymeric carbon precursor, a solvent, a dispersant, an anti-foaming agent, a monomer system, and an initiator system. The components are combined to form a suspension which is poured into a mold and heat-treated to form a thermoplastic part. The thermoplastic part can then be further densified and heat-treated to produce a high density carbon or graphite composite. The present invention also discloses the products derived from this method.

  3. Elasticity of polymeric nanocolloidal particles

    National Research Council Canada - National Science Library

    Riest, Jonas; Athanasopoulou, Labrini; Egorov, Sergei A; Likos, Christos N; Ziherl, Primož

    2015-01-01

    .... Elasticity of individual particles directly controls their swelling, wetting, and adsorption behaviour, their aggregation and self-assembly as well as structural and rheological properties of suspensions...

  4. 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.

  5. 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.

  6. 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.

  7. Formation Kinetics of Aqueous Suspensions of Fullerenes:Meeting in New Orleans.

    Science.gov (United States)

    Stable colloidal suspension of C60 is commonly achieved through various solvent exchange techniques. Nevertheless, the additives such as tetrahydrofuran may be retained in the C60 aggregates, which may influence the surface properties of the suspension. In this study, colloidal...

  8. Fiber Drawn 2D Polymeric Photonic Crystal THz Filters

    DEFF Research Database (Denmark)

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

    2012-01-01

    In this paper, we report on different polymeric 2D photonic crystal filters for THz frequencies which are fabricated by a standard fiber drawing technique. The bandstop filters were simulated and designed by the generalized multipole technique (GMT). The frequency and angle dependent transmission...

  9. Revisiting the Anionic Polymerization of Methyl Ethacrylate

    Energy Technology Data Exchange (ETDEWEB)

    Kennemur, Justin G. [Department of Chemistry and Biochemistry, Florida State University, Tallahassee FL 32306-4390 USA; Bates, Frank S. [Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis MN 55455-0431 USA; Hillmyer, Marc A. [Department of Chemistry, University of Minnesota, Minneapolis MN 55455-0431 USA

    2017-09-26

    Synthesis of poly(methyl ethacrylate), (PMEA), in tetrahydrofuran at -78 °C using anionic polymerization techniques results in high molar mass (>30 kg mol-1), low dispersity (1.3), and high conversion (>81%). The molar masses of a series of samples are consistent with values anticipated by the monomer-to-initiator ratio and conversion. These results represent a significant improvement to earlier reported attempts to prepare PMEA using anionic methods. Successful diblock polymerization of polystyrene-block-PMEA, (PS-PMEA), and poly(4-tert-butylstyrene)-block-PMEA, (PtBS-PMEA), is achieved through sequential anionic polymerization techniques with dispersities as low as 1.06 and segment molar fractions close to those targeted. Broad principal scattering peaks observed by small-angle X-ray scattering (SAXS) for symmetric PS-PMEA at relatively high molar mass (39 kg mol-1) suggests an effective interaction parameter (χeff) that is smaller than for PS-block-poly(methyl methacrylate). On the other hand, PtBS-PMEA block polymers form a well-ordered morphology based on SAXS measurements and is attributable to the more hydrophobic PtBS segment. These results confirm the viability of PMEA as a new constituent in the expanding suite of polymers suitable for preparing nanostructured block polymers.

  10. Kinetics and Mechanism of Bulk Polymerization of Vinyl Chloride in a Polymerization Reactor

    Directory of Open Access Journals (Sweden)

    A. S. Ibrahim

    2015-12-01

    Full Text Available Polyvinyl chloride (PVC is the third most commonly produced polymer and is important because of its mechanical characteristics. The most common method of PVC manufacturing is the process of suspension. Although, there are several benefits associated with suspension, this study will focus on the bulk polymerization of vinyl chloride; highlight the physical and chemical properties of PVC, which can be changed through an estimation of the optimum ratio that exists between the hydrophilic and hydrophobic parts of the polymer’s surface, and propose a new mathematical model which will be helpful for the conversion of PVC into a useful form. The result will be the proposal of a new dynamic mathematical model for the three-phase structure model. All particles have been taken into account in the proposed model, which helped contribute to the reaction in gel, solid, and liquid phases, emphasizing the use of mercury (Hg as a catalyst. The proposed mathematical model considers the heat and mass transfer between the liquid, gel, and solid phases with chemical reactions that occur between the liquid and solid phases, and between the gel and solid phases. The effect of the catalyst and volumetric flow rates of vinyl chloride monomer (VCM on the system have been evaluated through the proposed mathematical model. Furthermore, the study’s experimental data have been compared with the findings of the suggested model in the context of concentration and temperature reaction. Obtained results show good agreement between the proposed mathematical model and the actual plant data.

  11. 49 CFR 238.427 - Suspension system.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Suspension system. 238.427 Section 238.427... Equipment § 238.427 Suspension system. (a) General requirements. (1) Suspension systems shall be designed to... equipment. (2) Passenger equipment shall meet the safety performance standards for suspension systems...

  12. 78 FR 57525 - Suspension of Community Eligibility

    Science.gov (United States)

    2013-09-19

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...) that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  13. 48 CFR 2909.407 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 7 2010-10-01 2010-10-01 false Suspension. 2909.407... CONTRACTOR QUALIFICATIONS Debarment, Suspension, and Ineligibility 2909.407 Suspension. (a) The Senior... authorized to make an exception, regarding suspension by another agency suspending official under the...

  14. 14 CFR 1267.670 - Suspension.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Suspension. 1267.670 Section 1267.670... WORKPLACE (FINANCIAL ASSISTANCE) Definitions § 1267.670 Suspension. Suspension means an action taken by a..., subpart 9.4) and the common rule, Government-wide Debarment and Suspension (Nonprocurement), that...

  15. 22 CFR 1008.670 - Suspension.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Suspension. 1008.670 Section 1008.670 Foreign... ASSISTANCE) Definitions § 1008.670 Suspension. Suspension means an action taken by a Federal agency that...-wide Debarment and Suspension (Nonprocurement), that implements Executive Order 12549 and Executive...

  16. 2 CFR 182.670 - Suspension.

    Science.gov (United States)

    2010-01-01

    ... 2 Grants and Agreements 1 2010-01-01 2010-01-01 false Suspension. 182.670 Section 182.670 Grants... Suspension. Suspension means an action taken by a Federal agency that immediately prohibits a recipient from... guidance on nonprocurement debarment and suspension (2 CFR part 180, which implements Executive Orders...

  17. 40 CFR 36.670 - Suspension.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Suspension. 36.670 Section 36.670... REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Definitions § 36.670 Suspension. Suspension means... contracts (48 CFR part 9, subpart 9.4) and the common rule, Government-wide Debarment and Suspension...

  18. 78 FR 5734 - Suspension of Community Eligibility

    Science.gov (United States)

    2013-01-28

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...) that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  19. 77 FR 53775 - Suspension of Community Eligibility

    Science.gov (United States)

    2012-09-04

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...) that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  20. 29 CFR 94.670 - Suspension.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 1 2010-07-01 2010-07-01 true Suspension. 94.670 Section 94.670 Labor Office of the... § 94.670 Suspension. Suspension means an action taken by a Federal agency that immediately prohibits a... Debarment and Suspension (Nonprocurement), that implements Executive Order 12549 and Executive Order 12689...

  1. 45 CFR 1173.670 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Suspension. 1173.670 Section 1173.670 Public... (FINANCIAL ASSISTANCE) Definitions § 1173.670 Suspension. Suspension means an action taken by a Federal..., subpart 9.4) and the common rule, Government-wide Debarment and Suspension (Nonprocurement), that...

  2. 45 CFR 1641.11 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 4 2010-10-01 2010-10-01 false Suspension. 1641.11 Section 1641.11 Public Welfare Regulations Relating to Public Welfare (Continued) LEGAL SERVICES CORPORATION DEBARMENT, SUSPENSION AND REMOVAL OF RECIPIENT AUDITORS Suspension § 1641.11 Suspension. (a) IPAs suspended from providing audit...

  3. 77 FR 2646 - Suspension of Community Eligibility

    Science.gov (United States)

    2012-01-19

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...) that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  4. 31 CFR 19.1015 - Suspension.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false Suspension. 19.1015 Section 19.1015 Money and Finance: Treasury Office of the Secretary of the Treasury GOVERNMENTWIDE DEBARMENT AND SUSPENSION (NONPROCUREMENT) Definitions § 19.1015 Suspension. Suspension is an action taken by a suspending...

  5. 41 CFR 105-68.1015 - Suspension.

    Science.gov (United States)

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Suspension. 105-68.1015 Section 105-68.1015 Public Contracts and Property Management Federal Property Management Regulations...-GOVERNMENTWIDE DEBARMENT AND SUSPENSION (NONPROCUREMENT) Definitions § 105-68.1015 Suspension. Suspension is an...

  6. 15 CFR 29.670 - Suspension.

    Science.gov (United States)

    2010-01-01

    ... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Suspension. 29.670 Section 29.670... WORKPLACE (FINANCIAL ASSISTANCE) Definitions § 29.670 Suspension. Suspension means an action taken by a..., subpart 9.4) and the common rule, Government-wide Debarment and Suspension (Nonprocurement), that...

  7. 13 CFR 147.670 - Suspension.

    Science.gov (United States)

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Suspension. 147.670 Section 147...-FREE WORKPLACE (NONPROCUREMENT) Definitions § 147.670 Suspension. Suspension means an action taken by a..., subpart 9.4) and the common rule, Government-wide Debarment and Suspension (Nonprocurement), that...

  8. 78 FR 2622 - Suspension of Community Eligibility

    Science.gov (United States)

    2013-01-14

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...) that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  9. 10 CFR 607.670 - Suspension.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Suspension. 607.670 Section 607.670 Energy DEPARTMENT OF... ASSISTANCE) Definitions § 607.670 Suspension. Suspension means an action taken by a Federal agency that...-wide Debarment and Suspension (Nonprocurement), that implements Executive Order 12549 and Executive...

  10. 76 FR 9666 - Suspension of Community Eligibility

    Science.gov (United States)

    2011-02-22

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...), that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  11. 29 CFR 1471.1015 - Suspension.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 4 2010-07-01 2010-07-01 false Suspension. 1471.1015 Section 1471.1015 Labor Regulations Relating to Labor (Continued) FEDERAL MEDIATION AND CONCILIATION SERVICE GOVERNMENTWIDE DEBARMENT AND SUSPENSION (NONPROCUREMENT) Definitions § 1471.1015 Suspension. Suspension is an action taken by a suspending...

  12. 22 CFR 133.670 - Suspension.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Suspension. 133.670 Section 133.670 Foreign... ASSISTANCE) Definitions § 133.670 Suspension. Suspension means an action taken by a Federal agency that...-wide Debarment and Suspension (Nonprocurement), that implements Executive Order 12549 and Executive...

  13. 43 CFR 43.670 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Suspension. 43.670 Section 43.670 Public... WORKPLACE (FINANCIAL ASSISTANCE) Definitions § 43.670 Suspension. Suspension means an action taken by a..., subpart 9.4) and 2 CFR part 180. Suspension of a recipient is a distinct and separate action from...

  14. 22 CFR 312.670 - Suspension.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Suspension. 312.670 Section 312.670 Foreign... § 312.670 Suspension. Suspension means an action taken by a Federal agency that immediately prohibits a... Debarment and Suspension (Nonprocurement), that implements Executive Order 12549 and Executive Order 12689...

  15. 34 CFR 84.670 - Suspension.

    Science.gov (United States)

    2010-07-01

    ... 34 Education 1 2010-07-01 2010-07-01 false Suspension. 84.670 Section 84.670 Education Office of... ASSISTANCE) Definitions § 84.670 Suspension. Suspension means an action taken by a Federal agency that...-wide Debarment and Suspension (Nonprocurement), that implements Executive Order 12549 and Executive...

  16. 77 FR 7537 - Suspension of Community Eligibility

    Science.gov (United States)

    2012-02-13

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...) that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  17. 19 CFR 146.82 - Suspension.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Suspension. 146.82 Section 146.82 Customs Duties U... (CONTINUED) FOREIGN TRADE ZONES Penalties; Suspension; Revocation § 146.82 Suspension. (a) For cause. The... for a period not to exceed 90 days. Upon order of the Board the suspension may be continued. If...

  18. 77 FR 24858 - Suspension of Community Eligibility

    Science.gov (United States)

    2012-04-26

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...) that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  19. 75 FR 5890 - Suspension of Community Eligibility

    Science.gov (United States)

    2010-02-05

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...), that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  20. 76 FR 39782 - Suspension of Community Eligibility

    Science.gov (United States)

    2011-07-07

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...), that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  1. 22 CFR 1509.670 - Suspension.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Suspension. 1509.670 Section 1509.670 Foreign... ASSISTANCE) Definitions § 1509.670 Suspension. Suspension means an action taken by a Federal agency that...-wide Debarment and Suspension (Nonprocurement), that implements Executive Order 12549 and Executive...

  2. 22 CFR 210.670 - Suspension.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Suspension. 210.670 Section 210.670 Foreign... (FINANCIAL ASSISTANCE) Definitions § 210.670 Suspension. Suspension means an action taken by a Federal agency..., subpart 9.4) and the common rule, Government-wide Debarment and Suspension (Nonprocurement), that...

  3. 45 CFR 1206.1-4 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 4 2010-10-01 2010-10-01 false Suspension. 1206.1-4 Section 1206.1-4 Public... GRANTS AND CONTRACTS-SUSPENSION AND TERMINATION AND DENIAL OF APPLICATION FOR REFUNDING Suspension and Termination of Assistance § 1206.1-4 Suspension. (a) General. The responsible Corporation official may suspend...

  4. 31 CFR 20.670 - Suspension.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false Suspension. 20.670 Section 20.670...-FREE WORKPLACE (FINANCIAL ASSISTANCE) Definitions § 20.670 Suspension. Suspension means an action taken..., subpart 9.4) and the common rule, Government-wide Debarment and Suspension (Nonprocurement), that...

  5. 78 FR 68999 - Suspension of Community Eligibility

    Science.gov (United States)

    2013-11-18

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...) that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  6. 29 CFR 1472.670 - Suspension.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 4 2010-07-01 2010-07-01 false Suspension. 1472.670 Section 1472.670 Labor Regulations... DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Definitions § 1472.670 Suspension. Suspension means an... CFR part 9, subpart 9.4) and the common rule, Government-wide Debarment and Suspension (Nonprocurement...

  7. 24 CFR 21.670 - Suspension.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Suspension. 21.670 Section 21.670... GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (GRANTS) Definitions § 21.670 Suspension. Suspension means an... CFR part 9, subpart 9.4) and the common rule, Government-wide Debarment and Suspension (Nonprocurement...

  8. 77 FR 9856 - Suspension of Community Eligibility

    Science.gov (United States)

    2012-02-21

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...) that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  9. 49 CFR 32.670 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Suspension. 32.670 Section 32.670 Transportation... ASSISTANCE) Definitions § 32.670 Suspension. Suspension means an action taken by a Federal agency that...-wide Debarment and Suspension (Nonprocurement), that implements Executive Order 12549 and Executive...

  10. 21 CFR 1405.670 - Suspension.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Suspension. 1405.670 Section 1405.670 Food and... (FINANCIAL ASSISTANCE) Definitions § 1405.670 Suspension. Suspension means an action taken by a Federal..., subpart 9.4) and the common rule, Government-wide Debarment and Suspension (Nonprocurement), that...

  11. 50 CFR 13.27 - Permit suspension.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 1 2010-10-01 2010-10-01 false Permit suspension. 13.27 Section 13.27... GENERAL PERMIT PROCEDURES Permit Administration § 13.27 Permit suspension. (a) Criteria for suspension... Government. Such suspension shall remain in effect until the issuing officer determines that the permittee...

  12. 45 CFR 1155.670 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Suspension. 1155.670 Section 1155.670 Public... ASSISTANCE) Definitions § 1155.670 Suspension. Suspension means an action taken by a Federal agency that...-wide Debarment and Suspension (Nonprocurement), that implements Executive Order 12549 and Executive...

  13. 78 FR 57523 - Suspension of Community Eligibility

    Science.gov (United States)

    2013-09-19

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...) that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  14. 5 CFR 919.1015 - Suspension.

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Suspension. 919.1015 Section 919.1015 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL SERVICE REGULATIONS (CONTINUED) GOVERNMENTWIDE DEBARMENT AND SUSPENSION (NONPROCUREMENT) Definitions § 919.1015 Suspension. Suspension is an...

  15. 78 FR 2624 - Suspension of Community Eligibility

    Science.gov (United States)

    2013-01-14

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...) that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  16. 76 FR 2596 - Suspension of Community Eligibility

    Science.gov (United States)

    2011-01-14

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...), that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  17. 75 FR 52861 - Suspension of Community Eligibility

    Science.gov (United States)

    2010-08-30

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...), that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  18. 28 CFR 83.670 - Suspension.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Suspension. 83.670 Section 83.670... WORKPLACE (GRANTS) Definitions § 83.670 Suspension. Suspension means an action taken by a Federal agency..., subpart 9.4) and the common rule, Government-wide Debarment and Suspension (Nonprocurement), that...

  19. 39 CFR 957.27 - Suspension.

    Science.gov (United States)

    2010-07-01

    ... 39 Postal Service 1 2010-07-01 2010-07-01 false Suspension. 957.27 Section 957.27 Postal Service... SUSPENSION FROM CONTRACTING § 957.27 Suspension. (a) Any firm or individual suspended under chapter 3, section 7 of the Postal Service Purchasing Manual who believes that the suspension has not been in...

  20. 7 CFR 3021.670 - Suspension.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Suspension. 3021.670 Section 3021.670 Agriculture... Suspension. Suspension means an action taken by a Federal agency that immediately prohibits a recipient from... Debarment and Suspension (Nonprocurement), that implements Executive Order 12549 and Executive Order 12689...

  1. 76 FR 5284 - Suspension of Community Eligibility

    Science.gov (United States)

    2011-01-31

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...), that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  2. 78 FR 69001 - Suspension of Community Eligibility

    Science.gov (United States)

    2013-11-18

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...) that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  3. 45 CFR 630.670 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Suspension. 630.670 Section 630.670 Public Welfare... DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Definitions § 630.670 Suspension. Suspension means an action... CFR part 9, subpart 9.4) and the common rule, Government-wide Debarment and Suspension (Nonprocurement...

  4. 20 CFR 439.670 - Suspension.

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Suspension. 439.670 Section 439.670 Employees... ASSISTANCE) Definitions § 439.670 Suspension. Suspension means an action taken by a Federal agency that...-wide Debarment and Suspension (Nonprocurement), that implements Executive Order 12549 and Executive...

  5. 75 FR 9111 - Suspension of Community Eligibility

    Science.gov (United States)

    2010-03-01

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...), that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  6. 77 FR 63753 - Suspension of Community Eligibility

    Science.gov (United States)

    2012-10-17

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...) that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  7. 77 FR 2650 - Suspension of Community Eligibility

    Science.gov (United States)

    2012-01-19

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...) that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  8. 78 FR 5736 - Suspension of Community Eligibility

    Science.gov (United States)

    2013-01-28

    ... SECURITY Federal Emergency Management Agency 44 CFR Part 64 Suspension of Community Eligibility AGENCY...) that are scheduled for suspension on the effective dates listed within this rule because of... measures prior to the effective suspension date given in this rule, the suspension will not occur and a...

  9. "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...

  10. "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...

  11. "Point de suspension"

    CERN Document Server

    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...

  12. [Endoprosthesis of the frontonasal anastomosis after extranasal radical operations using biocompatible tubular polymeric materials].

    Science.gov (United States)

    Klochikhin, A L; Markov, G I; Shilenkova, V V

    1996-01-01

    The authors present pilot experience of extranasal radical operations on the frontal sinuses with the use of polymeric tube endoprostheses made of biocompatible polymeric materials EFOS 1, 2, 3 containing antimicrobial drugs (dioxidin, chinoxidin) and active substances promoting regeneration and epithelization (orotic acid derivatives). The above technique was employed in operations on frontal sinuses in 12 patients. Polymeric endoprostheses EFOS provide adequate lumen of the formed frontonasal anastomosis, reduce the occurrence of postoperative complications and recurrences as well as hospital stay.

  13. Multiscale simulation of heterophase polymerization : application to the synthesis of multicomponent colloidal polymer particles

    OpenAIRE

    Hernandez Garcia, Hugo Fernando

    2008-01-01

    Heterophase polymerization is a technique widely used for the synthesis of high performance polymeric materials with applications including paints, inks, adhesives, synthetic rubber, biomedical applications and many others. Due to the heterogeneous nature of the process, many different relevant length and time scales can be identified. Each of these scales has a direct influence on the kinetics of polymerization and on the physicochemical and performance properties of the final product. There...

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

    Science.gov (United States)

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

    2015-05-01

    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.

  15. Biotransformation of Dydrogesterone by Cell Suspension Cultures of Azadirachta indica

    OpenAIRE

    KHAN, Saifullah; CHOUDHARY, Muhammad Iqbal

    2008-01-01

    Biotransformation of dydrogesterone (1) by using cell suspension cultures of Azadirachta indica yielded a metabolite 20R-hydroxy-9b ,10a-pregna-4,6-diene-3-one (2). The structure of this compound was deduced on the basis of various spectroscopic techniques.

  16. 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.

  17. 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.

  18. Target-triggered polymerization for biosensing.

    Science.gov (United States)

    Wu, Yafeng; Wei, Wei; Liu, Songqin

    2012-09-18

    Because of the potential applications of biosensors in clinical diagnosis, biomedical research, environmental analysis, and food quality control, researchers are very interested in developing sensitive, selective, rapid, reliable, and low-cost versions of these devices. A classic biosensor directly transduces ligand-target binding events into a measurable physical readout. Because of the limited detection sensitivity and selectivity in earlier biosensors, researchers have developed a number of sensing/signal amplification strategies. Through the use of nanostructured or long chain polymeric materials to increase the upload of signal tags for amplification of the signal readout associated with the ligand-target binding events, researchers have achieved high sensitivity and exceptional selectivity. Very recently, target-triggered polymerization-assisted signal amplification strategies have been exploited as a new biosensing mechanism with many attractive features. This strategy couples a small initiator molecule to the DNA/protein detection probe prior to DNA hybridization or DNA/protein and protein/protein binding events. After ligand-target binding, the in-situ polymerization reaction is triggered. As a result, tens to hundreds of small monomer signal reporter molecules assemble into long chain polymers at the location where the initiator molecule was attached. The resulting polymer materials changed the optical and electrochemical properties at this location, which make the signal easily distinguishable from the background. The assay time ranged from minutes to hours and was determined by the degree of amplification needed. In this Account, we summarize a series of electrochemical and optical biosensors that employ target-triggered polymerization. We focus on the use of atom transfer radical polymerization (ATRP), as well as activator generated electron transfer for atom transfer radical polymerization (AGET ATRP) for in-situ formation of polymer materials for

  19. 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

  20. Suspension biomechanics of swimming microbes.

    Science.gov (United States)

    Ishikawa, Takuji

    2009-10-06

    Micro-organisms play a vital role in many biological, medical and engineering phenomena. Some recent research efforts have demonstrated the importance of biomechanics in understanding certain aspects of micro-organism behaviours such as locomotion and collective motions of cells. In particular, spatio-temporal coherent structures found in a bacterial suspension have been the focus of many research studies over the last few years. Recent studies have shown that macroscopic properties of a suspension, such as rheology and diffusion, are strongly affected by meso-scale flow structures generated by swimming microbes. Since the meso-scale flow structures are strongly affected by the interactions between microbes, a bottom-up strategy, i.e. from a cellular level to a continuum suspension level, represents the natural approach to the study of a suspension of swimming microbes. In this paper, we first provide a summary of existing biomechanical research on interactions between a pair of swimming micro-organisms, as a two-body interaction is the simplest many-body interaction. We show that interactions between two nearby swimming micro-organisms are described well by existing mathematical models. Then, collective motions formed by a group of swimming micro-organisms are discussed. We show that some collective motions of micro-organisms, such as coherent structures of bacterial suspensions, are satisfactorily explained by fluid dynamics. Lastly, we discuss how macroscopic suspension properties are changed by the microscopic characteristics of the cell suspension. The fundamental knowledge we present will be useful in obtaining a better understanding of the behaviour of micro-organisms.

  1. Characterization of Magnetic Polymeric Microparticles

    Directory of Open Access Journals (Sweden)

    Kazım Köse

    2016-08-01

    Full Text Available The separation process is very important in a variety of scientific fields, especially in biochemistry and biotechnology. The separation performance of a method can be determined by the separation time and the purity of the separated molecule, which is directly proportional with the ligand chosen for the target molecule. The separation time is actually a very important step for the cost and the time-dependent analysis, especially in medical applications. Magnetic separation is a very advantageous technique because it eliminates the time-consuming sample preparation and centrifugation steps. However, the magnetic performance of adsorbent may not be strong enough to respond the magnetic force applied externally. Therefore, in nanoparticle studies, magnetic performance of nanoparticles is highly important. In this study, the magnetic performance of polymeric microparticles synthesized using different magnetic cores (Fe2O3&Fe3O4, Fe&Ni, Ni&Co, Fe&Ni&Co with a solid support, HEMA (2-hydroxyl ethylmethacrylate, and a functional monomer, AdeM (adenine methacrylate, were compared. Some other properties such as size, zeta potential, surface morphology, etc. were also studied.

  2. Problems of millipound thrust measurement. The "Hansen Suspension"

    Energy Technology Data Exchange (ETDEWEB)

    Carta, David G.

    2014-03-31

    Considered in detail are problems which led to the need and use of the 'Hansen Suspension'. Also discussed are problems which are likely to be encountered in any low level thrust measuring system. The methods of calibration and the accuracies involved are given careful attention. With all parameters optimized and calibration techniques perfected, the system was found capable of a resolution of 10 {mu} lbs. A comparison of thrust measurements made by the 'Hansen Suspension' with measurements of a less sophisticated device leads to some surprising results.

  3. Performance of selected polymeric materials on LDEF

    Science.gov (United States)

    Young, Philip R.; Slemp, Wayne S.; Stein, Bland A.

    1993-01-01

    The NASA Long Duration Exposure Facility (LDEF) provided a unique environmental exposure of a wide variety of materials for potential advanced spacecraft application. This paper examines the molecular level response of selected polymeric materials which flew onboard this vehicle. Polymers include epolyimide, polysulfone, and polystyrene film and polyimide, polysulfone, and epoxy matrix resin/graphite fiber reinforced composites. Several promising experimental films were also studied. Most specimens received 5.8 years of low Earth orbital (LEO) exposure on LDEF. Several samples received on 10 months of exposure. Chemical characterization techniques included ultraviolet-visible and infrared spectroscopy, thermal analysis, x-ray photoelectron spectroscopy, and selected solution property measurements. Results suggest that many molecular level effects present during the first 10 months of exposure were not present after 5.8 years of exposure for specimens on or near Row 9. Increased AO fluence near the end of the mission likely eroded away much environmentally induced surface phenomena. The objective of this work is to provide fundamental information for use in improving the performance of polymeric materials for LEO application. A secondary objective is to gain an appreciation for the constraints and limitations of results from LDEF polymeric materials experiments.

  4. Preparation, characterisation and antibacterial activity of a florfenicol-loaded solid lipid nanoparticle suspension.

    Science.gov (United States)

    Wang, Ting; Chen, Xiaojin; Lu, Mengmeng; Li, Xihe; Zhou, WenZhong

    2015-12-01

    A florfenicol-loaded solid lipid nanoparticle (FFC-SLN) suspension was prepared by hot homogenisation and ultrasonic technique. The suspension was characterised for its release profile, stability, toxicity, and the physicochemical properties of the nanoparticles. Antibacterial activity of the suspension was evaluated in vitro and in vivo. The results showed that the mean diameter, polydispersity index and zeta potential of the nanoparticles were 253 ± 3 nm, 0.409 ± 0.022 and 47.5 ± 0.21 mV, respectively. In vitro release profile showed the FFC-SLN suspension had sustained release effect. The minimum inhibition concentration values of the FFC-SLN suspension were 6 and 3 µg/mL against Staphylococcus aureus and Escherichia coli respectively, compared with 3.5 and 2 µg/mL of native florfenicol. The suspension was relatively stable at 4°C and less stable at room temperature during 9 months storage. Although the nanoparticle carriers exhibited cytotoxicity in cell cultures, the LD50 of the lyophilised dry power of the suspension was higher than 5 g/kg body weight. Mortality protection against E. coli lethal infection in mice showed that the nanoparticle suspension had much better efficacy (6/10) than native drug (1/10). These results indicate that FFC-SLN suspension could be a promising formulation in veterinary medicine.

  5. Two Photon Polymerization of Microneedles for Transdermal Drug Delivery

    Science.gov (United States)

    Gittard, Shaun D.; Ovsianikov, Aleksandr; Chichkov, Boris N.; Doraiswamy, Anand; Narayan, Roger J.

    2010-01-01

    Importance of the field Microneedles are small-scale devices that are finding use for transdermal delivery of protein-based pharmacologic agents and nucleic acid-based pharmacologic agents; however, microneedles prepared using conventional microelectronics-based technologies have several shortcomings, which have limited translation of these devices into widespread clinical use. Areas covered in this review Two photon polymerization is a laser-based rapid prototyping technique that has been recently used for direct fabrication of hollow microneedles with a wide variety of geometries. In addition, an indirect rapid prototyping method that involves two photon polymerization and polydimethyl siloxane micromolding has been used for fabrication of solid microneedles with exceptional mechanical properties. What the reader will gain In this review, the use of two photon polymerization for fabricating in-plane and out-of-plane hollow microneedle arrays is described. The use of two photon polymerization-micromolding for fabrication of solid microneedles is also reviewed. In addition, fabrication of microneedles with antimicrobial properties is discussed; antimicrobial microneedles may reduce the risk of infection associated with formation of channels through the stratum corneum. Take home message It is anticipated that the use of two photon polymerization as well as two photon polymerization-micromolding for fabrication of microneedles and other microstructured drug delivery devices will increase over the coming years. PMID:20205601

  6. Two-photon polymerization of microneedles for transdermal drug delivery.

    Science.gov (United States)

    Gittard, Shaun D; Ovsianikov, Aleksandr; Chichkov, Boris N; Doraiswamy, Anand; Narayan, Roger J

    2010-04-01

    Microneedles are small-scale devices that are finding use for transdermal delivery of protein-based pharmacologic agents and nucleic acid-based pharmacologic agents; however, microneedles prepared using conventional microelectronics-based technologies have several shortcomings, which have limited translation of these devices into widespread clinical use. Two-photon polymerization is a laser-based rapid prototyping technique that has been used recently for direct fabrication of hollow microneedles with a wide variety of geometries. In addition, an indirect rapid prototyping method that involves two-photon polymerization and polydimethyl siloxane micromolding has been used for fabrication of solid microneedles with exceptional mechanical properties. In this review, the use of two-photon polymerization for fabricating in-plane and out-of-plane hollow microneedle arrays is described. The use of two-photon polymerization-micromolding for fabrication of solid microneedles is also reviewed. In addition, fabrication of microneedles with antimicrobial properties is discussed; antimicrobial microneedles may reduce the risk of infection associated with the formation of channels through the stratum corneum. It is anticipated that the use of two-photon polymerization as well as two-photon polymerization-micromolding for fabrication of microneedles and other microstructured drug delivery devices will increase over the coming years.

  7. Formulation and Evaluation of Hydrotropic Solublization Based Suspensions of Griseofulvin

    OpenAIRE

    A. S. Shete,; Yadav, A. V.; A.P. Dabke; Sakhare, S. S.

    2010-01-01

    Purpose: Hydrotropes increases the solubility of organics in water. Objective of present investigation was to enhance the solubility of griseofulvin using the technique of hydrotropic solubilization technique and convert them into suitable oral liquid dosage form (suspension) useful for enhancement of bioavailability. Methods: 0.5M, 1M, 2M of the hydrotropes (tri sodium citrate, urea, sodium acetate, sodium benzoate and sodium salicylates) were used to study the saturation solubility. Solubil...

  8. Numerical study of stress tensors in Poiseuille flow of suspensions.

    Science.gov (United States)

    Chatterjee, Athonu; Heine, David R

    2010-08-01

    In this paper, the flow of dense suspensions of monodisperse spheres in wall-bounded channels is studied using a mesoscopic numerical model based on the dissipative particle dynamics (DPD) technique. Experimental observations [for instance, L. Isa, Phys. Rev. Lett. 98, 198305 (2007)] have confirmed that understanding the relevant physics of this problem requires probing at the mesoscopic level to account for the particle scale behavior. The DPD-based approach presented here enables us to explore various aspects of suspension flow at the particle scale. The yielding behavior of the suspensions is studied using macroscopic stress components calculated from the particle level. The relationship between various normal and shear stress components at the yielding plane is presented and discussed. It is seen that in dense suspensions, yielding is characterized by a strong dependence on all the stress components: τ{xx} , τ{xy} , and τ{yy} . It is also seen that different stress components have different length-scale dependencies. While the normal stress in the flow direction, τ{xx} , depends on macroscopic parameters such as the driving force, τ{yy} , the normal stress transverse to the flow, depends on particle level parameters and is independent of the driving force. Wall topologies with characteristic dimensions on the order of the suspension particle size have a strong effect on the flow characteristics and the stress components.

  9. Physical theory for near-bed turbulent particle suspension capacity

    Science.gov (United States)

    Eggenhuisen, Joris T.; Cartigny, Matthieu J. B.; de Leeuw, Jan

    2017-05-01

    The inability to capture the physics of solid-particle suspension in turbulent fluids in simple formulas is holding back the application of multiphase fluid dynamics techniques to many practical problems in nature and society involving particle suspension. We present a force balance approach to particle suspension in the region near no-slip frictional boundaries of turbulent flows. The force balance parameter Γ contains gravity and buoyancy acting on the sediment and vertical turbulent fluid forces; it includes universal turbulent flow scales and material properties of the fluid and particles only. Comparison to measurements shows that Γ = 1 gives the upper limit of observed suspended particle concentrations in a broad range of flume experiments and field settings. The condition of Γ > 1 coincides with the complete suppression of coherent turbulent structures near the boundary in direct numerical simulations of sediment-laden turbulent flow. Γ thus captures the maximum amount of sediment that can be contained in suspension at the base of turbulent flow, and it can be regarded as a suspension capacity parameter. It can be applied as a simple concentration boundary condition in modelling studies of the dispersion of particulates in environmental and man-made flows.

  10. 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

  11. Does the degree of polymerization of haptoglobin influence the results of the radial immunodiffusion assay?

    NARCIS (Netherlands)

    Rijn, H.J.M. van; Wisman, J.P.W.; Meyling, F.G.

    1987-01-01

    The degree of polymerization of haptoglobin (Hp) phenotypes 2-1 and 2-2 was studied. In individual samples the degree of polymerization tends to be positively correlated with the Hp concentration as determined by the radial immunodiffusion technique (RID), while an inverse relationship between the

  12. Novel hybrid polymeric materials for barrier coatings

    Science.gov (United States)

    Pavlacky, Erin Christine

    Polymer-clay nanocomposites, described as the inclusion of nanometer-sized layered silicates into polymeric materials, have been widely researched due to significant enhancements in material properties with the incorporation of small levels of filler (1--5 wt.%) compared to conventional micro- and macro-composites (20--30 wt.%). One of the most promising applications for polymer-clay nanocomposites is in the field of barrier coatings. The development of UV-curable polymer-clay nanocomposite barrier coatings was explored by employing a novel in situ preparation technique. Unsaturated polyesters were synthesized in the presence of organomodified clays by in situ intercalative polymerization to create highly dispersed clays in a precursor resin. The resulting clay-containing polyesters were crosslinked via UV-irradiation using donor-acceptor chemistry to create polymer-clay nanocomposites which exhibited significantly enhanced barrier properties compared to alternative clay dispersion techniques. The impact of the quaternary alkylammonium organic modifiers, used to increase compatibility between the inorganic clay and organic polymer, was studied to explore influence of the organic modifier structure on the nanocomposite material properties. By incorporating just the organic modifiers, no layered silicates, into the polyester resins, reductions in film mechanical and thermal properties were observed, a strong indicator of film plasticization. An alternative in situ preparation method was explored to further increase the dispersion of organomodified clay within the precursor polyester resins. In stark contrast to traditional in situ polymerization methods, a novel "reverse" in situ preparation method was developed, where unmodified montmorillonite clay was added during polyesterification to a reaction mixture containing the alkylammonium organic modifier. The resulting nanocomposite films exhibited reduced water vapor permeability and increased mechanical properties

  13. Polymeric lithography editor: Editing lithographic errors with nanoporous polymeric probes

    Science.gov (United States)

    Rajasekaran, Pradeep Ramiah; Zhou, Chuanhong; Dasari, Mallika; Voss, Kay-Obbe; Trautmann, Christina; Kohli, Punit

    2017-01-01

    A new lithographic editing system with an ability to erase and rectify errors in microscale with real-time optical feedback is demonstrated. The erasing probe is a conically shaped hydrogel (tip size, ca. 500 nm) template-synthesized from track-etched conical glass wafers. The “nanosponge” hydrogel probe “erases” patterns by hydrating and absorbing molecules into a porous hydrogel matrix via diffusion analogous to a wet sponge. The presence of an interfacial liquid water layer between the hydrogel tip and the substrate during erasing enables frictionless, uninterrupted translation of the eraser on the substrate. The erasing capacity of the hydrogel is extremely high because of the large free volume of the hydrogel matrix. The fast frictionless translocation and interfacial hydration resulted in an extremely high erasing rate (~785 μm2/s), which is two to three orders of magnitude higher in comparison with the atomic force microscopy–based erasing (~0.1 μm2/s) experiments. The high precision and accuracy of the polymeric lithography editor (PLE) system stemmed from coupling piezoelectric actuators to an inverted optical microscope. Subsequently after erasing the patterns using agarose erasers, a polydimethylsiloxane probe fabricated from the same conical track-etched template was used to precisely redeposit molecules of interest at the erased spots. PLE also provides a continuous optical feedback throughout the entire molecular editing process—writing, erasing, and rewriting. To demonstrate its potential in device fabrication, we used PLE to electrochemically erase metallic copper thin film, forming an interdigitated array of microelectrodes for the fabrication of a functional microphotodetector device. High-throughput dot and line erasing, writing with the conical “wet nanosponge,” and continuous optical feedback make PLE complementary to the existing catalog of nanolithographic/microlithographic and three-dimensional printing techniques. This new

  14. Polymerization of anionic wormlike micelles.

    Science.gov (United States)

    Zhu, Zhiyuan; González, Yamaira I; Xu, Hangxun; Kaler, Eric W; Liu, Shiyong

    2006-01-31

    Polymerizable anionic wormlike micelles are obtained upon mixing the hydrotropic salt p-toluidine hydrochloride (PTHC) with the reactive anionic surfactant sodium 4-(8-methacryloyloxyoctyl)oxybenzene sulfonate (MOBS). Polymerization captures the cross-sectional radius of the micelles (approximately 2 nm), induces micellar growth, and leads to the formation of a stable single-phase dispersion of wormlike micellar polymers. The unpolymerized and polymerized micelles were characterized using static and dynamic laser light scattering, small-angle neutron scattering, 1H NMR, and stopped-flow light scattering. Stopped-flow light scattering was also used to measure the average lifetime of the unpolymerized wormlike micelles. A comparison of the average lifetime of unpolymerized wormlike micelles with the surfactant monomer propagation rate was used to elucidate the mechanism of polymerization. There is a significant correlation between the ratio of the average lifetime to the monomer propagation rate and the average aggregation number of the polymerized wormlike micelles.

  15. 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...

  16. Kinetics of silica polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Weres, O.; Yee, A.; Tsao, L.

    1980-05-01

    The polymerization of silicic acid in geothermal brine-like aqueous solutions to produce amorphous silica in colloidal form has been studied experimentally and theoretically. A large amount of high quality experimental data has been generated over the temperature rang 23 to 100{sup 0}C. Wide ranges of dissolved silica concentration, pH, and sodium chloride concentration were covered. The catalytic effects of fluoride and the reaction inhibiting effects of aluminum and boron were studied also. Two basic processes have been separately studied: the formation of new colloidal particles by the homogeneous nucleation process and the deposition of dissolved silica on pre-existing colloidal particles. A rigorous theory of the formation of colloidal particles of amorphous silica by homogeneous nucleation was developed. This theory employs the Lothe-Pound formalism, and is embodied in the computer code SILNUC which quantitatively models the homogeneous nucleation and growth of colloidal silica particles in more than enough detail for practical application. The theory and code were extensively used in planning the experimental work and analyzing the data produced. The code is now complete and running in its final form. It is capable of reproducing most of the experimental results to within experimental error. It is also capable of extrapolation to experimentally inaccessible conditions, i.e., high temperatures, rapidly varying temperature and pH, etc.

  17. 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 ...

  18. 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)

  19. 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.

  20. Avaliação do uso de técnicas FT-IR para caracterização de cobertura polimérica de material energético Evaluation of FT-IR techniques for polymeric coating characterization of energetic material

    Directory of Open Access Journals (Sweden)

    Elizabeth C. Mattos

    2004-06-01

    Full Text Available Técnicas FT-IR de transmissão, reflexão e fotoacústica (PAS foram utilizadas para a caracterização da cobertura polimérica do hexahidro-1,3,5-trinitro-1,3,5-triazina (RDX usando um poliuretano (Estane. Verificou-se no decorrer deste trabalho que, embora seja possível observar as bandas do polímero por meio das diferentes técnicas, as de transmissão (filme vazado e fotoacústica foram aquelas que melhor evidenciaram as absorções do poliuretano na amostra analisada da cobertura polimérica do material energético. Entre as técnicas consideradas de análise de superfície, a espectroscopia PAS apresentou melhor resultado, provavelmente em função da espessura de poucos micra da camada polimérica.The transmission, reflection and photoacoustic FTIR techniques have been used for characterization of polymeric coating of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX using a polyurethane (Estane. Although the bands characteristic of the polymer were indicated by the various techniques, the transmission (casting film and photoacoustic techniques showed better evidence of polyurethane absorptions in the polymer coating of energetic material. Among the surface-sensitive techniques, PAS spectroscopy shows better result, probably because the polymer coating is at few microns from the surface.

  1. Lyophilized Oral Sustained Release Polymeric Nanoparticles of Nateglinide

    OpenAIRE

    Kaleemuddin, Mohammad; Srinivas, Prathima

    2012-01-01

    The objective of this study is to formulate lyophilized oral sustained release polymeric nanoparticles of nateglinide in order to decrease dosing frequency, minimize side effects, and increase bioavailability. Nateglinide-loaded poly Ɛ-caprolactone nanoparticles were prepared by emulsion solvent evaporation with ultrasonication technique and subjected to various studies for characterization including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, photon correlati...

  2. 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.

  3. Modeling and Analytical Simulation of Anterior Polymerization in the ...

    African Journals Online (AJOL)

    ADOWIE PERE

    We solve the systems of coupled nonlinear partial differential equations describing polymerization in the presence of an inert material analytically. We decouple the equations using parameter-expanding method and solve the resulting equations using Eigen functions expansion technique. Analytical solutions of equations ...

  4. 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...

  5. 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

  6. Flow induced orientation in carbon nanotube suspensions: Modeling and experiments

    Science.gov (United States)

    Natale, Giovanniantonio

    Due to their unique properties, carbon nanotubes (CNTs) hold remarkable promise for the next generation of materials, with potential applications in organic electronics, reinforced and electrically conducting plastic composites, new alloys, and even new types of biological sensors and devices. Despite these promises and potentialities, carbon nanotube composites and suspensions are inherently difficult to process, and efficient processing schemes are only just starting to be formulated. The success of CNTs, in all potential applications, depends on the understanding and ability to control the microstructure evolution during processing. During flow, CNTs dispersed in a polymeric matrix orient and interact, inducing spatial and orientation correlations. Agglomerates can also break if the hydrodynamic forces are sufficient, increasing the probability of contact between different nanotubes and improving the interactions with the matrix and the flowability of the composite. At rest, the microstructure of the CNT suspension keeps changing due to Brownian motion and van der Waals attractive forces, and the CNTs diffuse in the suspending fluid and eventually form a network of particles. To analyze such a complex system, a low viscosity epoxy was used as the matrix to disperse the multiwall carbon nanotubes (MWCNTs). Nearly Newtonian polymers are particularly useful because they can impart significant shear stress to break the CNT agglomerates and facilitate their dispersion, while their Newtonian behavior does not mask the viscoelastic properties of the overall system. From dilute to concentrated regimes, CNT suspensions were rheologically probed to obtain information ranging from the orientation and transport of individual carbon nanotubes to the viscoelastic properties of dense and isotropic network of rods. Rheology was used to understand the microstructure evolution under flow and in static conditions. The effects of flow history, shearing velocity, rest time and

  7. 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...

  8. Rotational diffusion in dense suspensions

    NARCIS (Netherlands)

    Hagen, M. H. J.; Frenkel, D.; Lowe, C.P.

    1999-01-01

    We have computed the rotational diffusion coefficient for a suspension of hard spheres. We find excellent agreement with experimental results over a density range up to, and including, the colloidal crystal. However, we find that theories derived to second order in the volume fraction overestimate

  9. Transmission function of pneumatic suspension

    OpenAIRE

    Turenko, A.; Bogomolov, V.; Klimenko, V.; Shilov, A.

    2006-01-01

    The transmission function of pneumatic suspension at assumption, that walls of pneumatic elastic element is absolute not stretched; the rubber buffers of compression and of retreat are absent; description of shock absorber is linear and symmetric; the processes of compression and expansion of air are adiabatic; motion of the oscillating system carry out without separation of wheel from a road is received.

  10. 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 Transportation Other Regulations Relating to Transportation (Continued) NATIONAL HIGHWAY TRAFFIC SAFETY... 10,000 Pounds § 570.61 Suspension system. (a) Suspension condition. Ball joint seals shall not be cut...

  11. 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...

  12. 49 CFR 393.207 - Suspension systems.

    Science.gov (United States)

    2010-10-01

    ... 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 § 393.207 Suspension systems. (a) Axles. No axle positioning part shall be cracked, broken, loose or missing...

  13. 45 CFR 1210.3-3 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 4 2010-10-01 2010-10-01 false Suspension. 1210.3-3 Section 1210.3-3 Public... § 1210.3-3 Suspension. (a) The ACTION State Director may suspend a Volunteer for up to 30 days in order... Volunteer. Suspension is not warranted if the State Director determines that sufficient grounds already...

  14. 48 CFR 2509.407 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 6 2010-10-01 2010-10-01 true Suspension. 2509.407 Section 2509.407 Federal Acquisition Regulations System NATIONAL SCIENCE FOUNDATION ACQUISITION PLANNING CONTRACTOR QUALIFICATIONS Debarment, Suspension, and Ineligibility 2509.407 Suspension. ...

  15. 32 CFR 26.670 - Suspension.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 1 2010-07-01 2010-07-01 false Suspension. 26.670 Section 26.670 National... GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Definitions § 26.670 Suspension. Suspension means an action taken by a Federal agency that immediately prohibits a recipient from...

  16. 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...-GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Definitions § 105-74.670 Suspension. Suspension means an action taken by a Federal agency that immediately prohibits a recipient from...

  17. 48 CFR 609.407 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 4 2010-10-01 2010-10-01 false Suspension. 609.407 Section 609.407 Federal Acquisition Regulations System DEPARTMENT OF STATE COMPETITION AND ACQUISITION PLANNING CONTRACTOR QUALIFICATIONS Debarment, Suspension, and Ineligibility 609.407 Suspension. ...

  18. 25 CFR 558.5 - License suspension.

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 2 2010-04-01 2010-04-01 false License suspension. 558.5 Section 558.5 Indians NATIONAL... MANAGEMENT OFFICIALS § 558.5 License suspension. (a) If, after the issuance of a gaming license, the... tribe shall suspend such license and shall notify in writing the licensee of the suspension and the...

  19. 48 CFR 1309.407 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Suspension. 1309.407 Section 1309.407 Federal Acquisition Regulations System DEPARTMENT OF COMMERCE COMPETITION AND ACQUISITION PLANNING CONTRACTOR QUALIFICATIONS Debarment, Suspension, and Ineligibility 1309.407 Suspension. ...

  20. 36 CFR 1212.670 - Suspension.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Suspension. 1212.670 Section... GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Definitions § 1212.670 Suspension. Suspension means an action taken by a Federal agency that immediately prohibits a recipient from...

  1. 25 CFR 23.52 - Grant suspension.

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Grant suspension. 23.52 Section 23.52 Indians BUREAU OF... Grant Administration Provisions and Requirements § 23.52 Grant suspension. (a) When a grantee has... assistance, suspend the grant. The notice preceding the suspension shall include the effective date of the...

  2. 22 CFR 34.20 - Suspension.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Suspension. 34.20 Section 34.20 Foreign Relations DEPARTMENT OF STATE CLAIMS AND STOLEN PROPERTY DEBT COLLECTION Collection Adjustments § 34.20 Suspension. The suspension of collection action shall be made in accordance with the standards set forth in...

  3. 32 CFR 552.80 - Suspension period.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 3 2010-07-01 2010-07-01 true Suspension period. 552.80 Section 552.80 National... Suspension period. All solicitation privileges suspended by installation commanders will be for a specific time. Normally, it will not exceed 2 years. When the suspension period expires, the agent may reapply...

  4. 48 CFR 509.407 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 4 2010-10-01 2010-10-01 false Suspension. 509.407 Section 509.407 Federal Acquisition Regulations System GENERAL SERVICES ADMINISTRATION COMPETITION AND ACQUISITION PLANNING CONTRACTOR QUALIFICATIONS Debarment, Suspension, and Ineligibility 509.407 Suspension. ...

  5. 7 CFR 3015.123 - Suspension.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Suspension. 3015.123 Section 3015.123 Agriculture... AGRICULTURE UNIFORM FEDERAL ASSISTANCE REGULATIONS Grant and Subgrant Closeout, Suspension and Termination § 3015.123 Suspension. (a) When a recipient has materially failed to comply with the provisions...

  6. 21 CFR 520.1806 - Piperazine suspension.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Piperazine suspension. 520.1806 Section 520.1806... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1806 Piperazine suspension. (a) Specifications. Each milliliter of suspension contains piperazine monohydrochloride equivalent to...

  7. 48 CFR 9.407 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Suspension. 9.407 Section 9.407 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION ACQUISITION PLANNING CONTRACTOR QUALIFICATIONS Debarment, Suspension, and Ineligibility 9.407 Suspension. ...

  8. 48 CFR 909.407 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Suspension. 909.407 Section 909.407 Federal Acquisition Regulations System DEPARTMENT OF ENERGY COMPETITION ACQUISITION PLANNING CONTRACTOR QUALIFICATIONS Debarment, Suspension, and Ineligibility 909.407 Suspension. ...

  9. 48 CFR 809.407 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Suspension. 809.407 Section 809.407 Federal Acquisition Regulations System DEPARTMENT OF VETERANS AFFAIRS COMPETITION AND ACQUISITION PLANNING CONTRACTOR QUALIFICATIONS Debarment, Suspension, and Ineligibility 809.407 Suspension. ...

  10. 48 CFR 1509.407 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 6 2010-10-01 2010-10-01 true Suspension. 1509.407 Section 1509.407 Federal Acquisition Regulations System ENVIRONMENTAL PROTECTION AGENCY ACQUISITION PLANNING CONTRACTOR QUALIFICATIONS Debarment, Suspension and Ineligibility 1509.407 Suspension. ...

  11. 21 CFR 522.1289 - Lufenuron suspension.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Lufenuron suspension. 522.1289 Section 522.1289 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Lufenuron suspension. (a) Specifications. Each milliliter of sterile aqueous suspension contains 10...

  12. 32 CFR 776.82 - Interim suspension.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 5 2010-07-01 2010-07-01 false Interim suspension. 776.82 Section 776.82... Complaint Processing Procedures § 776.82 Interim suspension. (a) Where the Rules Counsel determines there is... interim suspension, pending completion of a professional responsibility investigation. The covered...

  13. 48 CFR 409.407 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 4 2010-10-01 2010-10-01 false Suspension. 409.407 Section 409.407 Federal Acquisition Regulations System DEPARTMENT OF AGRICULTURE COMPETITION AND ACQUISITION PLANNING CONTRACTOR QUALIFICATIONS Debarment, Suspension and Ineligibility 409.407 Suspension. ...

  14. 48 CFR 2009.407 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 6 2010-10-01 2010-10-01 true Suspension. 2009.407 Section 2009.407 Federal Acquisition Regulations System NUCLEAR REGULATORY COMMISSION COMPETITION AND ACQUISITION PLANNING CONTRACTOR QUALIFICATIONS Debarment, Suspension, and Ineligibility 2009.407 Suspension. ...

  15. 75 FR 24494 - Nonprocurement Debarment and Suspension

    Science.gov (United States)

    2010-05-05

    ...; ] ELECTION ASSISTANCE COMMISSION 2 CFR Chapter 58 Nonprocurement Debarment and Suspension AGENCY: U.S... proposed debarment and suspension regulations. These proposed regulations will apply to nonprocurement... Management and Budget (OMB) in a document on nonprocurement debarment and suspension published in the Federal...

  16. 21 CFR 520.1630 - Oxfendazole suspension.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Oxfendazole suspension. 520.1630 Section 520.1630... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1630 Oxfendazole suspension. (a) Specifications. Each milliliter of suspension contains: (1) 90.6 milligrams (mg) oxfendazole (9...

  17. 32 CFR 552.79 - Suspension action.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 3 2010-07-01 2010-07-01 true Suspension action. 552.79 Section 552.79 National... Suspension action. (a) When suspended for cause, immediately notify the company and the agent, in writing, of the reason. When the installation commander determines that suspension should be extended throughout...

  18. 36 CFR 223.141 - Suspension.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 2 2010-07-01 2010-07-01 false Suspension. 223.141 Section... DISPOSAL OF NATIONAL FOREST SYSTEM TIMBER Suspension and Debarment of Timber Purchasers § 223.141 Suspension. (a) The suspending official may, in the public interest, suspend a purchaser on the basis of...

  19. 22 CFR 127.8 - Interim suspension.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Interim suspension. 127.8 Section 127.8 Foreign... Interim suspension. (a) The Managing Director of the Directorate of Defense Trade Controls or the Director of the Office of Defense Trade Controls Compliance is authorized to order the interim suspension of...

  20. 38 CFR 48.670 - Suspension.

    Science.gov (United States)

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Suspension. 48.670...) GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Definitions § 48.670 Suspension. Suspension means an action taken by a Federal agency that immediately prohibits a recipient from...

  1. 48 CFR 309.407 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 4 2010-10-01 2010-10-01 false Suspension. 309.407 Section 309.407 Federal Acquisition Regulations System HEALTH AND HUMAN SERVICES COMPETITION AND ACQUISITION PLANNING CONTRACTOR QUALIFICATIONS Debarment, Suspension, and Ineligibility 309.407 Suspension. ...

  2. 48 CFR 1409.407 - Suspension.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Suspension. 1409.407 Section 1409.407 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR COMPETITION AND ACQUISITION PLANNING CONTRACTOR QUALIFICATIONS Debarment, Suspension, and Ineligibility 1409.407 Suspension. ...

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

    Science.gov (United States)

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

    2012-11-15

    Titania nanoparticles were modified by free-radical graft polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) at the particle surface, resulting in the formation of a 1-2 nm thick polymer brush. The zwitterionic nature of the polymer layer suggests that the suspension stability is a delicate function of pH, as well as volume fraction, salt concentration and the presence of charged or un-charged additives which may act as depletants or to screen charge interactions in the system. In this context, we characterized the suspension rheology as a function of volume fraction, pH, ionic strength and the concentration of surfactants in the suspension. Near-neutral pH, the brush layer is effective in stabilizing particles against aggregation with Newtonian behavior observed for volume fractions approaching 14%. Flocculation of particles and an onset of shear-thinning behavior was observed on decreasing pH from near-neutral. Conversely, suspension stability was maintained on increasing pH from near-neutral. Likewise, flocculation could be quickly induced by the addition of salt and cationic surfactant in small amounts, but the suspensions displayed greater stability to anionic and non-ionic surfactant additives. These results have important implications for the successful formulation of complex fluids employing zwitterionic colloids. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. Platysma suspension and platysmaplasty during neck lift: anatomical study and analysis of 30 cases.

    Science.gov (United States)

    Labbé, Daniel; Franco, R G; Nicolas, J

    2006-05-01

    The authors developed a technique for the treatment of the cervical area during face lifts. The authors called this technique platysma suspension and platysmaplasty rather than plication. After an anatomical study on 10 corpses on which the authors tested the various platysma suspension techniques, they carried out platysma suspension associated with platysmaplasty in 30 patients. This technique consists of suspending the free edge of the platysma muscle and fixing it to a resistant tissue close to the earlobe (Loré's fascia or tympanoparotid fascia). The anterior triangle of the neck was well defined, and there was no need to undermine the platysma muscle because of a perfect sliding plane between the platysma and sternocleidomastoid muscles. This technique is both simple and effective. It generates long-lasting results, without the inconveniences or complications associated with other techniques.

  5. The role of bladder neck suspension in the era of mid-urethral sling surgery.

    Science.gov (United States)

    Rashid, T G; De Ridder, D; Van der Aa, F

    2015-09-01

    Mid-urethral slings are currently considered to be the gold standard for the surgical treatment of stress urinary incontinence, replacing bladder neck suspension techniques which previously occupied this position. In recent years, however, there have been concerns with regard to the use of synthetic material in vaginal surgery. We performed a review of the literature to discuss the role of bladder neck suspension techniques in the current clinical setting. Bladder neck suspension techniques consist of vaginal techniques, needle suspension techniques and retropubic techniques. The latter two techniques have been proven to offer durable outcomes for stress urinary incontinence. As compared to autologous slings, the long-term success rates may be considered inferior, but so is the rate of complication, resulting in higher patient satisfaction. Bladder neck suspension techniques may have a role in treating recurrent and/or persisting stress urinary incontinence after (failed) sling surgery and remain of particular interest in patients with stress urinary incontinence when performing concomitant surgery, for example for prolapse.

  6. Biodegradability of biobased polymeric materials in natural environments: Structures and Chemistry

    CSIR Research Space (South Africa)

    Muniyasamy, S

    2017-03-01

    Full Text Available for biodegradability of polymers, as well as the involved physical, chemical, and biological mechanisms, are reviewed. Various analytical techniques and standard test methods for evaluating the potential biodegradability and its toxicity level of polymeric materials...

  7. 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.

  8. Quenching Phase Separation by Vapor Deposition Polymerization

    Science.gov (United States)

    Tao, Ran; Anthamatten, Mitchell

    2015-03-01

    Initiated chemical vapor deposition (iCVD) is a solventless, free radical technique predominately used to deposit homogeneous films of linear and crosslinked polymers directly from gas phase feeds. We report a template-free method to fabricate continuous-phase porous polymer films by simultaneous phase separation during iCVD. Phase separation during film growth is achieved by condensing an inert porogen, along with initiator, monomer, and crosslinker. When the vapor mixture transports to the cooled substrate, phase separation occurs along with polymerization and crosslinking, which quench the state of phase separation. The kinetics of spontaneously phase separation can be qualitatively understood on the basis of Cahn-Hilliard theory. A series of films were grown by varying monomer and porogen's degree of saturation. Deposited films were studied by electron microscopy and spectroscopic techniques.

  9. REVIEW ARTICLE Multiphoton polymerization of hybrid materials

    Science.gov (United States)

    Farsari, Maria; Vamvakaki, Maria; Chichkov, Boris N.

    2010-12-01

    Multiphoton polymerization has been developed as a direct laser writing technique for the preparation of complex 3D structures with resolution beyond the diffraction limit of light. The combination of two or more hybrid materials with different functionalities in the same system has allowed the preparation of structures with advanced properties and functions. Furthermore, the surface functionalization of the 3D structures opens new avenues for their applications in a variety of nanobiotechnological fields. This paper describes the principles of 2PP and the experimental set-up used for 3D structure fabrication. It also gives an overview of the materials that have been employed in 2PP so far and depicts the perspectives of this technique in the development of new active components.

  10. 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; 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....

  11. 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.

  12. Effective viscosity of actively swimming algae suspensions

    Science.gov (United States)

    Ewoldt, Randy; Caretta, Lucas; Chengala, Anwar; Sheng, Jian

    2010-11-01

    Suspensions of actively swimming microorganisms exhibit an effective viscosity which may depend on volume fraction, cell shape, and the nature of locomotion (e.g. "pushers" vs. "pullers"). Here we report experimental measurements of shear viscosity for suspensions of unicellular green algae (Dunaliella primolecta, a biflagellated "puller"). We use a cone-and-plate rheometer to measure the dynamic shear viscosity for both motile and non-motile suspensions of D. primolecta. Viscosity increases with concentration for both cases, but the active suspensions of "pullers" have a comparatively lower effective viscosity than passive suspensions. This observation contrasts recently proposed theories which predict that "pullers" should instead have a higher viscosity than non-motile suspensions. Additionally, we observe shear-induced migration of active suspensions and consider its impact on the resulting effective shear viscosity.

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

    Science.gov (United States)

    Demir, Yusuf K; Akan, Zafer; Kerimoglu, Oya

    2013-01-01

    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.

  14. Applications of polymeric micelles with tumor targeted in chemotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Ding Hui; Wang Xiaojun; Zhang Song; Liu Xinli, E-mail: Vip.lxl@163.com [Shandong Polytechnic University, Shandong Provincial Key Laboratory of Microbial Engineering (China)

    2012-11-15

    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 {approx} 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. MicroScale Thermophoresis (MST) for studying actin polymerization kinetics.

    Science.gov (United States)

    Topf, Andrea; Franz, Peter; Tsiavaliaris, Georgios

    2017-10-01

    Here, we present a MicroScale Thermophoresis (MST)-based assay for in vitro assessment of actin polymerization. By monitoring the thermophoretic behavior of ATTO488-labeled actin in a temperature gradient over time, we could follow polymerization in real time and resolve its three characteristic phases: nucleation, elongation, and steady-state equilibration. Titration experiments allowed us to evaluate the effects of actin-binding proteins (ABPs) on polymerization, including DNase I-induced inhibition and mDia2FH1FH2 (mDia2)-assisted acceleration of nucleation. The corresponding rates of actin filament elongation were quantitatively determined, yielding values in good agreement with those obtained using the pyrene-actin polymerization assay. Finally, we measured the effect of myosin on actin polymerization, circumventing the problems of fluorescence quenching and signal disturbance that occur with other techniques. MST is a simple and valuable research tool for investigating actin kinetics covering a wide range of molecular interactions, with low protein consumption.

  17. 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.

  18. 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.

  19. An adaptive pneumatic suspension based on the estimation of the excitation frequency

    Science.gov (United States)

    Nieto, A. J.; Morales, A. L.; Trapero, J. R.; Chicharro, J. M.; Pintado, P.

    2011-04-01

    A pneumatic suspension that can adapt itself to the incoming vibration is presented in this paper. A switching control strategy between two different configurations is proposed and studied. The objective is to avoid undesirable resonant frequencies. The control procedure is based on the pre-knowledge of the incoming vibration frequency, and when this frequency is unknown, a very efficient prediction technique is used. The results show that the adaptable suspension has improved performance as compared to any of its passive counterparts. The transient response when switching typically takes less than three cycles and does not hinder the suspension performance.

  20. Extensional viscosity of copper nanowire suspensions in an aqueous polymer solution

    OpenAIRE

    McDonnell, Amarin G.; Jason, Naveen N.; Yeo, Leslie Y.; James R. Friend; Cheng, Wenlong; Prabhakar, Ranganathan

    2015-01-01

    Suspensions of copper nanowires are emerging as new electronic inks for next-generation flexible electronics. Using a novel surface acoustic wave driven extensional flow technique we are able to perform currently lacking analysis of these suspensions and their complex buffer. We observe extensional viscosities from 3 mPa$\\cdot$s (1 mPa$\\cdot$s shear viscosity) to 37.2 Pa$\\cdot$s via changes in the suspension concentration, thus capturing low viscosities that have been historically very challe...

  1. 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.

  2. 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.

  3. Covalent Organic Frameworks as a Platform for Multidimensional Polymerization

    Science.gov (United States)

    2017-01-01

    The simultaneous polymerization and crystallization of monomers featuring directional bonding designs provides covalent organic frameworks (COFs), which are periodic polymer networks with robust covalent bonds arranged in two- or three-dimensional topologies. The range of properties characterized in COFs has rapidly expanded to include those of interest for heterogeneous catalysis, energy storage and photovoltaic devices, and proton-conducting membranes. Yet many of these applications will require materials quality, morphological control, and synthetic efficiency exceeding the capabilities of contemporary synthetic methods. This level of control will emerge from an improved fundamental understanding of COF nucleation and growth processes. More powerful characterization of structure and defects, improved syntheses guided by mechanistic understanding, and accessing diverse isolated forms, ranging from single crystals to thin films to colloidal suspensions, remain important frontier problems. PMID:28691064

  4. 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.

  5. 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.

  6. Dynamics of magnetic nanoparticle suspensions

    OpenAIRE

    Singh, Vanchna; Banerjee, Varsha; Sharma, Manish

    2012-01-01

    We study the dynamics of a suspension of magnetic nanoparticles. Their relaxation times are strongly size-dependent. The dominant mode of relaxation is also governed by the size of the particles. As a result the dynamics is greatly altered due to polydispersity in the sample. We study the effect of polydispersity on the response functions. These exhibit significant changes as the parameters characterizing polydispersity are varied. We also provide a procedure to extract the particle size dist...

  7. Relaxation of jammed colloidal suspensions after shear cessation.

    Science.gov (United States)

    Ianni, Francesca; Lasne, David; Sarcia, Régis; Hébraud, Pascal

    2006-07-01

    The dynamics of heterogeneities in a shear thickening, concentrated colloidal suspension is investigated through speckle visibility spectroscopy, a dynamic light scattering technique recently introduced [P. K. Dixon and D. J. Durian, Phys. Rev. Lett. 90, 184302 (2003)]. Formation of shear-induced heterogeneities is observed in the jamming regime, and their relaxation after shear cessation is monitored as a function of the applied shear stress. The relaxation time of these heterogeneities increases when a higher stress is applied.

  8. Static facial suspension with Surgisis ES (Enhanced Strength) sling.

    Science.gov (United States)

    Leventhal, Douglas D; Pribitkin, Edmund A

    2008-01-01

    Static suspension procedures stabilize and support paralyzed facial muscles and enhance facial symmetry, appearance, mastication, and speech production in patients with facial palsy. A variety of autografts and allografts have been used for static facial suspension, but each has its limitations, and few studies document the efficacy or benefit of one substance over another. Xenograft tissue scaffoldings potentially offer both the compatibility of autografts and the convenience of allografts. Pilot study to evaluate efficacy of Surgisis ES (Enhanced Strength) static facial suspension in a series of six patients with facial paralysis. Retrospective chart review, illustrative case series, and review of the literature. Six patients with facial paralysis were treated with the Surgisis ES facial sling procedure. Four patients achieved satisfactory results after the initial procedure. One patient was displeased with the esthetic outcome and required a revision procedure to increase the tautness of the implant. In the initial four cases, the sling was tunneled subcutaneously and sutured to the muscle. In two cases, the sling was tunneled subcutaneously and subperiosteally, thereby suspending all the soft tissue in the midface. Static facial suspension with Surgisis ES improved cosmesis and function in this limited pilot study. In particular, a two-plane dissection technique provided excellent results. Further studies need to be conducted to evaluate the ongoing benefit over time.

  9. 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.

  10. Alumina interaction with AMPS-MPEG copolymers produced by RAFT polymerization: stability and rheological behavior.

    Science.gov (United States)

    Bouhamed, H; Boufi, S; Magnin, A

    2009-05-01

    Different copolymers of 2-acrylamido-2-methylpropanesulfonic acid sodium salt (AMPS), methoxypolyethyleneglycol methacrylate (MPEG), were prepared using two methods of radical polymerization: classical and RAFT-controlled radical polymerization. The effect of polymer structure and architecture on the adsorption behavior, electrokinetic and rheological properties of the alumina suspensions was investigated. Adsorption isotherms showed that copolymer interaction depended not only on the ratio of the monomers and their distribution within the macromolecular backbone, but also on the method of copolymerization. Electrokinetic analysis indicated that adsorption of the copolymer is accompanied by a shift in the isoelectric point (IEP) towards acid pH values. Above a certain concentration, of the order of 1 wt%, the absolute value of the zeta-potential reaches a saturation plateau. At this stage, the maximum zeta-potential value (in absolute value) depends on both the ratio of the monomers for statistical copolymer and the length of the two blocks in the case of block distribution. The rheological behavior is greatly affected in the presence of added polymer; the viscosity of the alumina suspension decreases and reaches an optimum, which depends on both the ratio of the monomers and their distribution within the macromolecular backbone. The viscoelastic properties of the suspensions were found to be functions of both the structure and the architecture of the copolymer. Adding AMPS-MPEG copolymer increases the stability of the suspension via electrostatic effects, but also via steric effects induced by the polyethylene glycol (PEG) segments. The steric contribution to the stabilization process is much important in the presence of block distribution, which is more efficient as dispersant for concentrated alumina suspensions.

  11. The determination of {sup 14}C in stack effluent gases by carbonate suspension counting method

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Sang Ki; Woo, Hyung Joo; Cho, Soo Young; Kim, Nak Bae [Korea Institute of Geology Minning and Meterials, Taejon (Korea, Republic of); Lee, Jong Dae [Chungbuk Univ., Cheongju (Korea, Republic of)

    1999-08-01

    The purpose of this study was to optimize carbonate suspension counting method for the measurements of high level activity of{sup 14}C in a reactor stack effluent gases. Although it is less sensitive method, the carbonate suspension counting method has been found to be a suitable technique for the{sup 14}C monitoring of samples with small amount but with high specific activity and to be relatively simple and fast.

  12. Synthesis and Characterization of the in Situ Bulk Polymerization of PMMA Containing Graphene Sheets Using Microwave Irradiation

    OpenAIRE

    Mohammad A. Aldosari; Ali A. Othman; Alsharaeh, Edreese H.

    2013-01-01

    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 app...

  13. Biomimetic polymeric membranes for water treatment

    DEFF Research Database (Denmark)

    Habel, Joachim Erich Otto

    This project is about the interplay of the three major components of aquaporin based biomimetic polymeric membranes (ABPMs): Aquaporins (AQPs), amphiphilic block copolymers, serving as a vesicular matrix for the hydrophobic AQP exterior (proteopolymersomes) and a polymeric membrane as embedment...

  14. Polymeric Slippery Coatings: Nature and Applications

    Directory of Open Access Journals (Sweden)

    Mohamed A. Samaha

    2014-04-01

    Full Text Available We review recent developments in nature-inspired superhydrophobic and omniphobic surfaces. Water droplets beading on a surface at significantly high static contact angles and low contact-angle hystereses characterize superhydrophobicity. Microscopically, rough hydrophobic surfaces could entrap air in their pores resulting in a portion of a submerged surface with air–water interface, which is responsible for the slip effect. Suberhydrophobicity enhances the mobility of droplets on lotus leaves for self-cleaning purposes, so-called lotus effect. Amongst other applications, superhydrophobicity could be used to design slippery surfaces with minimal skin-friction drag for energy conservation. Another kind of slippery coatings is the recently invented slippery liquid-infused porous surfaces (SLIPS, which are one type of omniphobic surfaces. Certain plants such as the carnivorous Nepenthes pitcher inspired SLIPS. Their interior surfaces have microstructural roughness, which can lock in place an infused lubricating liquid. The lubricant is then utilized as a repellent surface for other liquids such as water, blood, crude oil, and alcohol. In this review, we discuss the concepts of both lotus effect and Nepenthes slippery mechanism. We then present a review of recent advances in manufacturing polymeric and non-polymeric slippery surfaces with ordered and disordered micro/nanostructures. Furthermore, we discuss the performance and longevity of such surfaces. Techniques used to characterize the surfaces are also detailed. We conclude the article with an overview of the latest advances in characterizing and using slippery surfaces for different applications.

  15. Mixing in polymeric microfluidic devices.

    Energy Technology Data Exchange (ETDEWEB)

    Schunk, Peter Randall; Sun, Amy Cha-Tien; Davis, Robert H. (University of Colorado at Boulder, Boulder, CO); Brotherton, Christopher M. (University of Colorado at Boulder, Boulder, CO)

    2006-04-01

    This SAND report describes progress made during a Sandia National Laboratories sponsored graduate fellowship. The fellowship was funded through an LDRD proposal. The goal of this project is development and characterization of mixing strategies for polymeric microfluidic devices. The mixing strategies under investigation include electroosmotic flow focusing, hydrodynamic focusing, physical constrictions and porous polymer monoliths. For electroosmotic flow focusing, simulations were performed to determine the effect of electroosmotic flow in a microchannel with heterogeneous surface potential. The heterogeneous surface potential caused recirculations to form within the microchannel. These recirculations could then be used to restrict two mixing streams and reduce the characteristic diffusion length. Maximum mixing occurred when the ratio of the mixing region surface potential to the average channel surface potential was made large in magnitude and negative in sign, and when the ratio of the characteristic convection time to the characteristic diffusion time was minimized. Based on these results, experiments were performed to evaluate the manipulation of surface potential using living-radical photopolymerization. The material chosen to manipulate typically exhibits a negative surface potential. Using living-radical surface grafting, a positive surface potential was produced using 2-(Dimethylamino)ethyl methacrylate and a neutral surface was produced using a poly(ethylene glycol) surface graft. Simulations investigating hydrodynamic focusing were also performed. For this technique, mixing is enhanced by using a tertiary fluid stream to constrict the two mixing streams and reduce the characteristic diffusion length. Maximum mixing occurred when the ratio of the tertiary flow stream flow-rate to the mixing streams flow-rate was maximized. Also, like the electroosmotic focusing mixer, mixing was also maximized when the ratio of the characteristic convection time to the

  16. 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

  17. Polymeric materials for corrosion control

    Energy Technology Data Exchange (ETDEWEB)

    Dickie, R.A.; Floyd, F.L. (eds.)

    1986-01-01

    This volume of 31 typescript chapters is concerned with polymeric coatings. The papers originated in a symposium held in Chicago in 1985 and are divided into three categories: Evaluation of Material Performance; Adhesion and Interfacial Aspects of Corrosion Protection; and Materials for Corrosion Protection. An extensive subject index is included.

  18. 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 ...

  19. Fabrication of a polymer with three-dimensional structure by the ion beam graft polymerization method

    Science.gov (United States)

    Taniike, Akira; Kida, Yasutomo; Furuyama, Yuichi; Kitamura, Akira

    2011-12-01

    The graft polymerization method is one of the most effective techniques to produce a new polymer with unique function. To produce the polymer, we conducted experiments on radiation graft polymerization using ion beams of several hundred keV energy. A high density polyethylene (PE) film was irradiated with H + beams, then, graft polymerization with monomer solution such as acrylic acid or acrylonitrile was conducted. Radicals generated by the interaction between the beam ions and the PE molecules become the starting point of the graft polymerization. Since the range in PE depends on ion energy, the density distribution of the graft chain can be controlled by the ion energy. Using a mask which restricts the ion beam incidence, PE sheets containing graft chains only in the unmasked area were obtained. Multiple ion beam graft polymerization can produce a polymer which has some functional bases at specified position. We have demonstrated the production of a polymer film with a three-dimensional structure.

  20. Electrochemistry, a technique to prepare redox nano-structured composite materials (polymer/nano-particles) - Characterizations - Applications; L'electrochimie, un outil pour elaborer des materiaux composites redox nanostructures (polymere/nanoparticules) - Caracterisations - Applications

    Energy Technology Data Exchange (ETDEWEB)

    Chardon-Noblat, S. [Grenoble-1 Univ. Joseph Fourier, Lab. d' Electrochimie Organique et de Photochimie Redox, UMR 5630, Institut de Chimie Moleculaire de Grenoble, FR CNRS 2607, 38 - Grenoble (France)

    2006-07-01

    In this work is presented at first the preparation by an electrochemical way of bi functional nano-structured composite materials. It is shown that with the pulsed electrolysis techniques, it is possible to obtain metallic particles whose size and organization are controlled at the nano-scopic scale in redox matrices. Then, are presented the physico-chemical characterizations of these nano-objects (coupled in situ or ex situ at the electrochemistry). The first results relative to the catalytic activation of CO{sub 2} with these materials used as composite cathodes are indicated. (O.M.)

  1. Thermal Polymerization of N-Butyl Acrylate

    Science.gov (United States)

    Ingham, J. D.

    1982-01-01

    Simple new polymerization method enables production of n-butyl acrylate polymer of desired high molecular weight, without disadvantages that usually attend more conventional methods. Process, which is hybrid of thermal, solution, and emulsion polymerization methods, involves controlled thermal polymerization of monomer at moderate temperatures without use of catalysts or additives.

  2. 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.

  3. Drag Reduction of Bacterial Cellulose Suspensions

    Directory of Open Access Journals (Sweden)

    Satoshi Ogata

    2011-01-01

    Full Text Available Drag reduction due to bacterial cellulose suspensions with small environmental loading was investigated. Experiments were carried out by measuring the pressure drop in pipe flow. It was found that bacterial cellulose suspensions give rise to drag reduction in the turbulent flow range. We observed a maximum drag reduction ratio of 11% and found that it increased with the concentration of the bacterial cellulose suspension. However, the drag reduction effect decreased in the presence of mechanical shear.

  4. 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.

  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...... 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. 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

    2017-12-13

    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).

  7. 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.

  8. Nose-to-brain transport of melatonin from polymer gel suspensions: a microdialysis study in rats

    Science.gov (United States)

    Babu, R. Jayachandra; Dayal, Pankaj Patrick; Pawar, Kasturi; Singh, Mandip

    2012-01-01

    Purpose Exogenous melatonin (MT) has significant neuroprotective roles in Alzheimer’s and Parkinson’s diseases. This study investigates the delivery MT to brain via nasal route as a polymeric gel suspension using central brain microdialysis in anesthetized rats. Methods Micronized MT suspensions using polymers [carbopol, carboxymethyl cellulose (CMC)] and polyethylene glycol 400 (PEG400) were prepared and characterized for nasal administration. In vitro permeation of the formulations was measured across a three-dimensional tissue culture model EpiAirway™. The central brain delivery into olfactory bulb of nasally administered MT gel suspensions was studied using brain microdialysis in male Wistar rats. The MT content of microdialysis samples was analyzed by high performance liquid chromatography (HPLC) using electrochemical detection. The nose-to-brain delivery of MT formulations was compared with intravenously administered MT solution. Results MT suspensions in carbopol and CMC vehicles have shown significantly higher permeability across Epiairway™ as compared to control, PEG400 (P carbopol, CMC and PEG400, respectively, than that of intravenous MT in rats. In conclusion, microdialysis studies demonstrated increased brain levels of MT via nasal administration in rats. PMID:21428693

  9. POLYMERIZATION OF PROPENE WITH tBuNSiMe2C5Me4TiMe2 ...

    African Journals Online (AJOL)

    a

    polymerization, we report, under “living” conditions, the polymerization of propylene with. tBuNSiMe2C5Me4TiMe2 1 activated with MAO and other trialkylaluminiums as additives. EXPERIMENTAL. Materials. All operations were carried out under nitrogen atmosphere using standard Schlenk techniques. Dried MAO was ...

  10. Polymerization shrinkage assessment of dental resin composites: a literature review.

    Science.gov (United States)

    Kaisarly, Dalia; Gezawi, Moataz El

    2016-09-01

    Composite restorations are widely used worldwide, but the polymerization shrinkage is their main disadvantage that may lead to clinical failures and adverse consequences. This review reports, currently available in vitro techniques and methods used for assessing the polymerization shrinkage. The focus lies on recent methods employing three-dimensional micro-CT data for the evaluation of polymerization shrinkage: volumetric measurement and the shrinkage vector evaluation through tracing particles before and after polymerization. Original research articles reporting in vitro shrinkage measurements and shrinkage stresses were included in electronic and hand-search. Earlier methods are easier, faster and less expensive. The procedures of scanning the samples in the micro-CT and performing the shrinkage vector evaluation are time consuming and complicated. Moreover, the respective software is not commercially available and the various methods for shrinkage vector evaluation are based on different mathematical principles. Nevertheless, these methods provide clinically relevant information and give insight into the internal shrinkage behavior of composite applied in cavities and how boundary conditions affect the shrinkage vectors. The traditional methods give comparative information on polymerization shrinkage of resin composites, whereas using three-dimensional micro-CT data for volumetric shrinkage measurement and the shrinkage vector evaluation is a highly accurate method. The methods employing micro-CT data give the researchers knowledge related to the application method and the boundary conditions of restorations for visualizing the shrinkage effects that could not be seen otherwise. Consequently, this knowledge can be transferred to the clinical situation to optimize the material manipulation and application techniques for improved outcomes.

  11. 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.

  12. Measurements of scattering and absorption in mammalian cell suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Mourant, J.R.; Johnson, T.M.; Freyer, J.P.

    1996-03-01

    During the past several years a range of spectroscopies, including fluorescence and elastic-scatter spectroscopy, have been investigated for optically based detection of cancer and other tissue pathologies. Both elastic-scatter and fluorescence signals depend, in part, on scattering and absorption properties of the cells in the tissue. Therefore an understanding of the scattering and absorption properties of cells is a necessary prerequisite for understanding and developing these techniques. Cell suspensions provide a simple model with which to begin studying the absorption and scattering properties of cells. In this study we have made preliminary measurements of the scattering and absorption properties of suspensions of mouse mammary carcinoma cells (EMT6) over a broad wavelength range (380 nm to 800 nm).

  13. The large-angle magnetic suspension test fixture

    Science.gov (United States)

    Britcher, Colin P.; Ghofrani, Mehran; Britton, Thomas C.; Groom, Nelson J.

    1992-01-01

    As part of a NASA effort to develop the technology and techniques required to demonstrate the magnetic suspension of objects over wide ranges of attitudes, a small-scale demonstration project was undertaken. The objectives here are to suspend a cylindrical element containing a permanent magnet core, to demonstrate stability and control in five degrees-of-freedom, and to permit controlled rotation of the model in one degree-of-freedom over the full range of 360 deg. Further constraints are that all suspension and control electromagnets are to be behind a flat plane, located some distance from the model. Since this is a ground-based experiment and in order to maintain generality, the plane is chosen to be horizontal with the model levitated above the plane by repulsive forces.

  14. Measurements of scattering and absorption in mammalian cell suspensions

    Science.gov (United States)

    Mourant, Judith R.; Freyer, James P.; Johnson, Tamara M.

    1996-04-01

    During the past several years a range of spectroscopies, including fluorescence and elastic- scatter spectroscopy, have been investigated for optically based detection of cancer and other tissue pathologies. Both elastic-scatter and fluorescence signals depend, in part, on scattering and absorption properties of the cells in the tissue. Therefore an understanding of the scattering and absorption properties of cells is a necessary prerequisite for understanding and developing these techniques. Cell suspensions provide a simple model with which to begin studying the absorption and scattering properties of cells. In this study we have made preliminary measurements of the scattering and absorption properties of suspensions of mouse mammary carcinoma cells (EMT6) over a broad wavelength range (380 nm to 800 nm).

  15. Clogging by sieving in microchannels: Application to the detection of contaminants in colloidal suspensions

    CERN Document Server

    Sauret, Alban; Perro, Adeline; Villermaux, Emmanuel; Stone, Howard A; Dressaire, Emilie

    2014-01-01

    We report on a microfluidic method that allows measurement of a small concentration of large contaminants in suspensions of solid micrometer-scale particles. To perform the measurement, we flow the colloidal suspension through a series of constrictions, i.e. a microchannel of varying cross-section. We show and quantify the role of large contaminants in the formation of clogs at a constriction and the growth of the resulting filter cake. By measuring the time interval between two clogging events in an array of parallel microchannels, we are able to estimate the concentration of contaminants whose size is selected by the geometry of the microfluidic device. This technique for characterizing colloidal suspensions offers a versatile and rapid tool to explore the role of contaminants on the properties of the suspensions.

  16. Non-linear buffeting response analysis of long-span suspension bridges with central buckle

    Science.gov (United States)

    Wang, Hao; Li, Aiqun; Zhao, Gengwen; Li, Jian

    2010-06-01

    The rigid central buckle employed in the Runyang Suspension Bridge (RSB) was the first time it was used in a suspension bridge in China. By using a spectral representation method and FFT technique combined with measured data, a 3D fluctuating wind field considering the tower wind effect is simulated. A novel FE model for buffeting analysis is then presented, in which a specific user-defined Matrix27 element in ANSYS is employed to simulate the aeroelastic forces and its stiffness or damping matrices are parameterized by wind velocity and vibration frequency. A nonlinear time history analysis is carried out to study the influence of the rigid central buckle on the wind-induced buffeting response of a long-span suspension bridge. The results can be used as a reference for wind resistance design of long-span suspension bridges with a rigid central buckle in the future.

  17. Polymeric Nanofibers in Tissue Engineering

    Science.gov (United States)

    Dahlin, Rebecca L.; Kasper, F. Kurtis

    2011-01-01

    Polymeric nanofibers can be produced using methods such as electrospinning, phase separation, and self-assembly, and the fiber composition, diameter, alignment, degradation, and mechanical properties can be tailored to the intended application. Nanofibers possess unique advantages for tissue engineering. The small diameter closely matches that of extracellular matrix fibers, and the relatively large surface area is beneficial for cell attachment and bioactive factor loading. This review will update the reader on the aspects of nanofiber fabrication and characterization important to tissue engineering, including control of porous structure, cell infiltration, and fiber degradation. Bioactive factor loading will be discussed with specific relevance to tissue engineering. Finally, applications of polymeric nanofibers in the fields of bone, cartilage, ligament and tendon, cardiovascular, and neural tissue engineering will be reviewed. PMID:21699434

  18. 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.

  19. Plasma polymerized acetylene deposition using a return corona enhanced plasma reactor

    Science.gov (United States)

    Islam, Rokibul; Xie, Shuzheng; Englund, Karl R.; Pedrow, Patrick D.

    2017-08-01

    A corona based weakly ionized plasma source was developed to deposit plasma polymerized acetylene coating at atmospheric pressure. The plasma source included a distinctive point-to-point geometry consisting of an array of high voltage needles and an array of protrusions placed over a grounded screen. The geometry facilitated various corona discharge modes that included return corona to contribute plasma polymerized acetylene deposition downstream from the corona section. Scanning probe techniques were used to investigate deposition on both the leading surface and the trailing surface of substrates. Deposition was initiated as distinct nodules that merged to form a thin plasma polymerized coating.

  20. Electroactive Polymeric Materials for Supercapacitors

    Science.gov (United States)

    2017-06-16

    solvent resistant (SR) polymers that are insoluble, while retaining high redox activity, in both organic and aqueous electrolytes. The polymers are...FINAL REPORT Electroactive Polymeric Materials for Supercapacitors N00014-14-1-0399 John R. Reynolds School of Chemistry and Biochemistry...program was directed to the use of conjugated and highly electroactive polymers (EAPs) as the active redox materials in electrochemical supercapacitors

  1. Two Photon Polymerization of Ormosils

    Science.gov (United States)

    Matei, A.; Zamfirescu, M.; Jipa, F.; Luculescu, C.; Dinescu, M.; Buruiana, E. C.; Buruiana, T.; Sima, L. E.; Petrescu, S. M.

    2010-10-01

    In this work, 3D structures of hybrid polymers—ORMOSILS (organically modified silicates) were produced via Two Photon Polymerization (2PP) of hybrid methacrylates based on silane derivates. Synthetic routes have been used to obtain series of hybrid monomers, their structure and purity being checked by NMR Spectroscopy and Fourier Transform Infrared Spectroscopy. Two photon polymerization method (a relatively new technology which allows fast micro and nano processing of three-dimensional structures with application in medical devices, tissue scaffolds, photonic crystals etc) was used for monomers processing. As laser a Ti: Sapphire laser was used, with 200 fs pulse duration and 2 kHz repetition rate, emitting at 775 nm. A parametric study on the influence of the processing parameters (laser fluence, laser scanning velocity, photo initiator) on the written structures was carried out. The as prepared polymeric scaffolds were tested in mesenchymal stem cells and fibroblasts cell cultures, with the aim of further obtaining bone and dermal grafts. Cells morphology, proliferation, adhesion and alignment were analyzed for different experimental conditions.

  2. 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.

  3. Emulsion polymerization of vinyl acetate initiated by intermittent. gamma. radiation

    Energy Technology Data Exchange (ETDEWEB)

    Sundardi, F.

    1979-08-15

    The reaction kinetics of emulsion polymerization of vinyl acetate (VAc) monomer have been studied by using intermittent ..gamma.. radiation. The purpose of this technique is to take advantage of the polymerization reaction which still continues after the radiation production has been stopped, as expected by the Smith-Ewart rate theory. Tween 20 (polyoxyethylene sorbitan monolaurate), was used as the emulsifier. The polymer conversion was determined by using the dilatometric method. The polymerization rate R/sub p/ decreased with increase in emulsifier content. The Smith-Ewart rate theory cannot explain the experimental evidence satisfactorily. The average polymerization rate anti R/sub p/ between 20% and 80% conversion is a function of irradiation dose rate and can be written anti R/sub p/ = a/sub 1/I/sup a2/ where a/sub 1/ and a/sub 2/ is a constant in which the value depends on the emulsifier content in the emulsion and I is the irradiation dose rate.

  4. 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.

  5. 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)

  6. X-ray initiated polymerization of wood impregnants

    Science.gov (United States)

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

    2009-07-01

    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.

  7. Photoelectrochemical studies on aqueous suspensions of some ...

    Indian Academy of Sciences (India)

    pensions meet these requirements. The suspension media are equally as important as the suspension particles in generating an efficient photolysis process. Previous studies used semi- conductor particles as major producers of photonic outcome through heterogeneous charge transfer processes at the par- ticle/electrolyte ...

  8. 49 CFR 238.227 - Suspension system.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Suspension system. 238.227 Section 238.227 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Equipment § 238.227 Suspension system. On or after November 8, 1999— (a) All passenger equipment shall...

  9. Phase diagram of vertically vibrated dense suspensions

    NARCIS (Netherlands)

    von Kann, S.; Snoeijer, Jacobus Hendrikus; van der Meer, Roger M.

    2014-01-01

    When a hole is created in a layer of a dense, vertically vibrated suspension, phenomena are known to occur that defy the natural tendency of gravity to close the hole. Here, an overview is presented of the different patterns that we observed in a variety of dense particulate suspensions.

  10. Active suspension for a field sprayer boom

    DEFF Research Database (Denmark)

    Nielsen, Henrik Skovsgaard; Sørensen, Paul Haase

    1998-01-01

    The possibilities of implementing an active boom suspension is investigated. The performance improvement of an active suspension over a traditional passive one is studied in simulation, and shows a significant improvement. A closed-loop control system involving two ultrasonic distance transducers...

  11. Time Variance of the Suspension Nonlinearity

    DEFF Research Database (Denmark)

    Agerkvist, Finn T.; Pedersen, Bo Rohde

    2008-01-01

    . This paper investigates the changes in compliance the driving signal can cause, this includes low level short duration measurements of the resonance frequency as well as high power long duration measurements of the non-linearity of the suspension. It is found that at low levels the suspension softens...

  12. 32 CFR 1609.5 - Suspension.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 6 2010-07-01 2010-07-01 false Suspension. 1609.5 Section 1609.5 National Defense Other Regulations Relating to National Defense SELECTIVE SERVICE SYSTEM UNCOMPENSATED PERSONNEL § 1609.5 Suspension. The Director of Selective Service may suspend from duty any uncompensated person...

  13. 25 CFR 242.7 - Suspension.

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Suspension. 242.7 Section 242.7 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR FISH AND WILDLIFE COMMERCIAL FISHING ON RED LAKE INDIAN RESERVATION § 242.7 Suspension. All commercial fishing operations may be suspended by order of the Secretary at any...

  14. 39 CFR 955.28 - Suspension.

    Science.gov (United States)

    2010-07-01

    ... 39 Postal Service 1 2010-07-01 2010-07-01 false Suspension. 955.28 Section 955.28 Postal Service UNITED STATES POSTAL SERVICE PROCEDURES RULES OF PRACTICE BEFORE THE POSTAL SERVICE BOARD OF CONTRACT APPEALS § 955.28 Suspension. (a) Whenever at any time it appears that the parties are in agreement as to...

  15. 32 CFR 552.77 - Suspension approval.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 3 2010-07-01 2010-07-01 true Suspension approval. 552.77 Section 552.77 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY MILITARY RESERVATIONS AND....77 Suspension approval. The installation commander will personally approve all cases in which...

  16. 21 CFR 520.1289 - Lufenuron suspension.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Lufenuron suspension. 520.1289 Section 520.1289 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1289 Lufenuron suspension. (a...

  17. Functionalized ormosil scaffolds processed by direct laser polymerization for application in tissue engineering

    DEFF Research Database (Denmark)

    Matei, A.; Schou, Jørgen; Canulescu, Stela

    2013-01-01

    Synthesized N,N′-(methacryloyloxyethyl triehtoxy silyl propyl carbamoyl-oxyhexyl)-urea hybrid methacrylate was polymerized by direct laser polymerization using femtosecond laser pulses with the aim of using it for subsequent applications in tissue engineering. The as-obtained scaffolds were...... modified either by low pressure argon plasma treatment or by covering the structures with two different proteins (lysozyme, fibrinogen). For improved adhesion, the proteins were deposited by matrix assisted pulsed laser evaporation technique. The functionalized structures were tested in mouse fibroblasts...

  18. Effects of Surface-modification of Carbon Black on the Characteristics of Polymerized Toner

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eun Ho; Kim, Dae Su [Chungbuk National University, Cheongju (Korea, Republic of)

    2013-10-15

    Carbon black was surface-modified to prepare styrene-based suspension polymerized toner with excellent carbon black dispersibility inside toner particles. Carbon black was oxidized first to introduce hydroxyl groups on the surfaces, then esterification between the hydroxyl groups and carboxyl groups of organic acids (oleic acid, palmitic acid, acrylic acid) was followed to obtain organically surface-modified carbon black. The surface-modification of carbon black was confirmed by FTIR. Apparent carbon black dispersibility in the monomer mixture of the binder resin was tested and the particle size of dispersed carbon black was measured by particle size analyzer. Optical micrographs showed that carbon black dispersibility inside toner particles was improved considerably when the carbon black surface-modified with oleic acid was used. The polymerized toner prepared with the carbon black surface-modified with oleic acid showed ideal particle size and size distribution as a toner.

  19. Organic/Inorganic Composite Latexes: The Marriage of Emulsion Polymerization and Inorganic Chemistry

    Science.gov (United States)

    Bourgeat-Lami, Elodie; Lansalot, Muriel

    This review article describes recent advances in the synthesis and properties of waterborne organic/inorganic colloids elaborated through conventional emulsion polymerization, a well-established technology. These materials can be defined as aqueous suspensions of composite latex particles made up of organic and inorganic domains organized into well-defined core-shell, multinuclear, raspberry-like, multipod-like, or armored morphologies. Particular emphasis is placed on the synthetic strategies for fabrication of these colloidal materials. Two main approaches are described: the polymerization of organic monomers in the presence of preformed inorganic particles, and the reverse approach by which inorganic materials are synthesized in the presence of preformed polymer latexes. The list of examples provided in this review is by no means exhaustive but rather intends to give an overview of synthetic methods for selected inorganic compounds (e.g., silica, iron oxide, pigments, clays, quantum dots, and metals), and briefly reports on potential applications of the resulting materials.

  20. Coating individual single-walled carbon nanotubes with nylon 6,10 through emulsion polymerization.

    Science.gov (United States)

    Chen, Wei-Chiang; Wang, Randy K; Ziegler, Kirk J

    2009-08-01

    Solvent microenvironments are formed around individual single-walled carbon nanotubes (SWNTs) by mixing SWNT suspensions with water-immiscible organic solvents. These microenvironments are used to encapsulate the SWNTs with the monomer sebacoyl chloride. Hexamethylene diamine is then injected into the aqueous phase so the formation of nylon 6,10 is restricted to the interface between the microenvironment and water. This emulsion polymerization process results in uniform coatings of nylon 6,10 around individual SWNTs. The nylon-coated SWNTs remain dispersed in the aqueous phase and are highly luminescent at pH values ranging from 3 to 12. This emulsion polymerization method provides a general approach to coat nanotubes with various polymers.

  1. FTIR and Raman Spectroscopic Investigations of a Norfloxacin/Carbopol934 Polymeric Suspension

    National Research Council Canada - National Science Library

    Sahoo, S; Chakraborti, Ck; Behera, Pk; Mishra, Sc

    2012-01-01

    ...) has been studied by FTIR and Raman spectroscopy. From the spectral interpretation, it has been found that in formulation, the carboxylic groups of norfloxacin and hydroxyl groups of carbopol934 undergo chemical interaction, leading...

  2. Electrophoretic study of nitrofurantoin in aqueous suspensions. Effect of the addition of a polymeric thickener.

    Science.gov (United States)

    Gallardo, V; Delgado, A; Parera, A; Salcedo, J

    1990-04-01

    The electrophoretic mobility of nitrofurantoin (based on the microelectrophoresis method) has been studied in dilute dispersions of the drug. Specifically, the effect of NaCl, CaCl2 and AlCl3, pH, and a thickener, Carbopol 934, was determined. The electrophoretic mobility (mu) increases in absolute terms when the pH is raised between 3 and 9, although mu remains negative in this pH range. The variation of absolute mobility ([mu[) with NaCl concentration shows a pronounced maximum for a concentration of about 10(-4) M. However, when the concentration of CaCl2 in the medium is increased, [mu[ decreases steadily. The effect of AlCl3 concentration on the mobility is markedly influenced by the pH of the dispersing medium although a general trend is observed for mu to become more positive with increasing concentration of the salt. Finally, Carbopol 934 appears to impart an extra negative charge to the nitrofurantoin surface, since higher negative mobilities were measured in the presence of the polymer.

  3. 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.

  4. 48 CFR 9.407-4 - Period of suspension.

    Science.gov (United States)

    2010-10-01

    ... ACQUISITION PLANNING CONTRACTOR QUALIFICATIONS Debarment, Suspension, and Ineligibility 9.407-4 Period of... notice, the suspension shall be terminated unless an Assistant Attorney General requests its extension...

  5. Orbitomalar suspension during high SMAS facelift.

    Science.gov (United States)

    Cohen, Steven R; Kikkawa, Don O; Korn, Bobby S

    2010-01-01

    Traditional facelift techniques have some limitations: superficial musculo-aponeurotic system (SMAS) dissection may be incomplete in the superior medial orbitomalar region, and the centrofacial approach does not incorporate SMAS elevation. Orbitomalar suspension (OMS) during high SMAS facelift combines the best of other techniques and may enhance aesthetic results and improve blending of the eyelid-cheek junction while minimizing the risk of lower eyelid ectropion. The authors examine the efficacy and complication rates of the OMS procedure. Sixty patients underwent OMS as a primary component of high SMAS facelift and lower blepharoplasty. The technique is designed to accomplish superior-medial repositioning of the cheek while stabilizing lower eyelid position, reducing the risk of postoperative ectropion. Minor complications related to the OMS procedure occurred in three patients, all of whom had palpable and slightly visible Vicryl knots on one or both lateral upper eyelids. In one patient, the right side was reopened with a limited incision and the knot was removed. One case of lower eyelid malposition occurred and required revision. This patient presented on day three with unilateral left ectropion (2 mm), but the broken suture was easily replaced under local anesthesia, and the patient had no further ectropion. Two patients had transient lower eyelid malposition, which resolved within four weeks of surgery after gentle massage and lateral eyelid support with steri-strips. Two patients with prominent eyes and inferior orbital rim recession (negative vector) were not fully corrected; however, their lid position was no worse than the preoperative position and curvature. OMS during high SMAS facelift complements the deeper plane by adding a medial and superior vector of elevation to the cheek. Blending of the lower eyelid-cheek junction is accomplished with little risk of lower eyelid malposition.

  6. 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.

  7. Polymerization and polymerization shrinkage stress: fast cure versus conventional cure.

    Science.gov (United States)

    Strydom, C

    2005-07-01

    Dentists nowadays have a choice of conventional halogen lights, halogen lights with more sophisticated curing cycles (step-cure, rapid-cure, ramp-cure & pulse-cure), fast halogen lights, laser lights, plasma arc lights (PAC) and, lately, LED lights. While the manufacturers of some of the curing units try to improve on the operational reliability of their lights with a slower initial rate of cure, other manufacturers simply wish to offer as fast a curing time as possible. The conventional approach to cure accepts that sufficient light intensity of at least 400 mW/cm2 at a wavelength of 400-500 nm, and an exposure time of at least 40 seconds is needed to cure a 2-mm layer of composite. When a halogen light with higher or very high intensity is used, alternative curing strategies provide for an initial slower cure to allow flow, and after that a higher-intensity cure to improve the degree of cure. In contrast, in the fast-cure or rapid-cure approach it is suggested that a layer of composite can be cured for only 5- 10 seconds at >2000 mW/cm2. Some go so far as to say that an exposure time of 3 seconds per layer may be enough. This contradictory approach is compounded by the fact that this support for fast cure does not seem to consider the negative consequences. Therefore, to address these concerns, this review discusses the possible effects of a fast cure approach compared to a more conventional approach in polymerization and polymerization shrinkage, and the consequences there-off. Other factors that play an influencing role in polymerization shrinkage stress are also included in the discussion.

  8. A forecast of new test capabilities using Magnetic Suspension and Balance Systems

    Science.gov (United States)

    Lawing, Pierce L.; Johnson, William G., Jr.

    1988-01-01

    This paper outlines the potential of Magnetic Suspension and Balance System (MSBS) technology to solve existing problems related to support interference in wind tunnels. Improvement of existing test techniques and exciting new techniques are envisioned as a result of applying MSBS. These include improved data accuracy, dynamic stability testing, two-body/stores release testing, and pilot/designer-in-the-loop tests. It also discusses the use of MSBS for testing exotic configurations such as hybrid hypersonic vehicles. A new facility concept that combines features of ballistic tubes, magnetic suspension, and cryogenic tunnels is described.

  9. 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.

  10. 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 flue...... gas temperature (600–1050 °C) on ash deposit formation rate has been investigated. Investigations of deposit formation rate were made by use of an advanced online deposit probe that allowed nearly continuous measurement of the deposited mass. Two different measures of deposit formation rate are used...... in the analysis of the data. The first is the integral deposit formation rate (IDF-rate) found by dividing the integral mass change over integral time intervals (of order several hours) by the time interval. The IDF-rate is similar to deposit formation rates based on total deposit mass uptake divided by probe...

  11. 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

  12. Quadruple suspension design for Advanced LIGO

    CERN Document Server

    Robertson, N A; Crooks, D R M; Elliffe, E; Faller, J E; Fritschel, P; Gossler, S; Grant, A; Heptonstall, A; Hough, J; Lück, H B; 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 ...

  13. Shear thinning in non-Brownian suspensions.

    Science.gov (United States)

    Chatté, Guillaume; Comtet, Jean; Niguès, Antoine; Bocquet, Lydéric; Siria, Alessandro; Ducouret, Guylaine; Lequeux, François; Lenoir, Nicolas; Ovarlez, Guillaume; Colin, Annie

    2018-02-14

    We study the flow of suspensions of non-Brownian particles dispersed into a Newtonian solvent. Combining capillary rheometry and conventional rheometry, we evidence a succession of two shear thinning regimes separated by a shear thickening one. Through X-ray radiography measurements, we show that during each of those regimes, the flow remains homogeneous and does not involve particle migration. Using a quartz-tuning fork based atomic force microscope, we measure the repulsive force profile and the microscopic friction coefficient μ between two particles immersed into the solvent, as a function of normal load. Coupling measurements from those three techniques, we propose that (1) the first shear-thinning regime at low shear rates occurs for a lubricated rheology and can be interpreted as a decrease of the effective volume fraction under increasing particle pressures, due to short-ranged repulsive forces and (2) the second shear thinning regime after the shear-thickening transition occurs for a frictional rheology and can be interpreted as stemming from a decrease of the microscopic friction coefficient at large normal load.

  14. Facial thread lifting with suture suspension

    Directory of Open Access Journals (Sweden)

    Joana de Pinho Tavares

    Full Text Available Abstract Introduction: The increased interest in minimally-invasive treatments, such as the thread lifting, with lower risk of complications, minimum length of time away from work and effectiveness in correcting ptosis and aging characteristics has led many specialists to adopt this technique, but many doubts about its safety and effectiveness still limit its overall use. Objective: To analyze data published in the literature on the durability of results, their effectiveness, safety, and risk of serious adverse events associated with procedures using several types of threading sutures. Methods: Literature review using the key words "thread lift", "barbed suture", "suture suspension" and "APTOS". Due to the scarcity of literature, recent reports of facial lifting using threads were also selected, complemented with bibliographical references. Result: The first outcomes of facial lifting with barbed sutures remain inconclusive. Adverse events may occur, although they are mostly minor, self-limiting, and short-lived. The data on the maximum effect of the correction, the durability of results, and the consequences of the long-term suture stay are yet to be clarified. Conclusion: Interest in thread lifting is currently high, but this review suggests that it should not yet be adopted as an alternative to rhytidectomy.

  15. Facial thread lifting with suture suspension.

    Science.gov (United States)

    Tavares, Joana de Pinho; Oliveira, Carlos Augusto Costa Pires; Torres, Rodolfo Prado; Bahmad, Fayez

    2017-05-09

    The increased interest in minimally-invasive treatments, such as the thread lifting, with lower risk of complications, minimum length of time away from work and effectiveness in correcting ptosis and aging characteristics has led many specialists to adopt this technique, but many doubts about its safety and effectiveness still limit its overall use. To analyze data published in the literature on the durability of results, their effectiveness, safety, and risk of serious adverse events associated with procedures using several types of threading sutures. Literature review using the key words "thread lift", "barbed suture", "suture suspension" and "APTOS". Due to the scarcity of literature, recent reports of facial lifting using threads were also selected, complemented with bibliographical references. The first outcomes of facial lifting with barbed sutures remain inconclusive. Adverse events may occur, although they are mostly minor, self-limiting, and short-lived. The data on the maximum effect of the correction, the durability of results, and the consequences of the long-term suture stay are yet to be clarified. Interest in thread lifting is currently high, but this review suggests that it should not yet be adopted as an alternative to rhytidectomy. Copyright © 2017 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  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. The liposuction apparatus "suspension device": hi-plane liposculpture.

    Science.gov (United States)

    Weber, P; Dryden, R M; Foster, J A

    2000-06-01

    The improvement of liposuction equipment and techniques has resulted in a cumbersome operating room array of aspirator hoses, irrigation/infiltration tubing, and the insulated command and control wiring of current ultrasonic or power liposuction devices. This situation is further complicated by the presence of a second surgeon, the concomitant use of additional traditional or ultrasonic cannulas, and the suction hose of a second aspirator. To solve the problems of sterility and operating room organization, the authors describe a simple, releasable suspension design. This apparatus can be temporarily or permanently installed in minutes and is easily maintained to control numerous sterile hoses and wires required for certain liposuction procedures. This suspension method appeared to enhance the efficiency and ease of use by single and dual surgeons during cases utilizing ultrasonic and nonultrasonic cannulas. The time savings and ease of use was most noticeable in cases of dual surgeons using both ultrasonic and nonultrasonic systems simultaneously. In addition, surgical personnel were freed for other tasks. Single-surgeon, traditional liposuction was less notably facilitated in terms of speed and fewer personnel. However, wiring and tubing control is facilitated in any case. A simple liposuction suspension system facilitates the liposuction procedure to varying degrees depending upon the number of surgeons and devices in simultaneous use.

  18. Performance of VIDISCA-454 in Feces-Suspensions and Serum

    Directory of Open Access Journals (Sweden)

    Lia van der Hoek

    2012-08-01

    Full Text Available Virus discovery combining sequence unbiased amplification with next generation sequencing is now state-of-the-art. We have previously determined that the performance of the unbiased amplification technique which is operational at our institute, VIDISCA-454, is efficient when respiratory samples are used as input. The performance of the assay is, however, not known for other clinical materials like blood or stool samples. Here, we investigated the sensitivity of VIDISCA-454 with feces-suspensions and serum samples that are positive and that have been quantified for norovirus and human immunodeficiency virus type 1, respectively. The performance of VIDISCA-454 in serum samples was equal to its performance in respiratory material, with an estimated lower threshold of 1,000 viral genome copies. The estimated threshold in feces-suspension is around 200,000 viral genome copies. The decreased sensitivity in feces suspension is mainly due to sequences that share no recognizable identity with known sequences. Most likely these sequences originate from bacteria and phages which are not completely sequenced.

  19. 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.

  20. Restructuring and aging in a capillary suspension.

    Science.gov (United States)

    Koos, Erin; Kannowade, Wolfgang; Willenbacher, Norbert

    2014-12-01

    The rheological properties of capillary suspensions, suspensions with small amounts of an added immiscible fluid, are dramatically altered with the addition of the secondary fluid. We investigate a capillary suspension to determine how the network ages and restructures at rest and under applied external shear deformation. The present work uses calcium carbonate suspended in silicone oil (11 % solids) with added water as a model system. Aging of capillary suspensions and their response to applied oscillatory shear is distinctly different from particulate gels dominated by the van der Waals forces. The suspensions dominated by the capillary force are very sensitive to oscillatory flow, with the linear viscoelastic regime ending at a deformation of only 0.1% and demonstrating power-law aging behavior. This aging persists for long times at low deformations or for shorter times with a sudden decrease in the strength at higher deformations. This aging behavior suggests that the network is able to rearrange and even rupture. This same sensitivity is not demonstrated in shear flow where very high shear rates are required to rupture the agglomerates returning the apparent viscosity of capillary suspensions to the same viscosity as for the pure vdW suspension. A transitional region is also present at intermediate water contents wherein the material response depends very strongly on the type, strength, and duration of the external forcing.

  1. Stability of extemporaneously prepared rosuvastatin oral suspension.

    Science.gov (United States)

    Zaid, Abdel Naser; Shtayah, Rania; Qadumi, Ayman; Ghanem, Mashour; Qedan, Rawan; Daibes, Marah; Awwad, Somud Abu; Jaradat, Nidal; Kittana, Naim

    2017-10-01

    The stability of an extemporaneously prepared rosuvastatin suspension stored over 30 days under various storage conditions was evaluated. Rosuvastatin suspension was extemporaneously prepared using commercial rosuvastatin tablets as the source of active pharmaceutical ingredient. The organoleptic properties, dissolution profile, and stability of the formulation were investigated. For the stability studies, samples of the suspension were stored under 2 storage conditions, room temperature (25 °C and 60% relative humidity) and accelerated stability chambers (40 °C and 75% relative humidity). Viscosity, pH, organoleptic properties, and microbial contamination were evaluated according to the approved specifications. High-performance liquid chromatography was used for the analysis and quantification of rosuvastatin in selected samples. Microbiological investigations were also conducted. The prepared suspension showed acceptable organoleptic properties. It showed complete release of rosuvastatin within 15 minutes. The pH of the suspension was 9.8, which remained unchanged during the stability studies. The microbiological investigations demonstrated that the preparation was free of any microbial contamination. In addition, the suspension showed stability within at least the period of use of a 100-mL rosuvastatin bottle. Extemporaneously prepared rosuvastatin 20-mg/mL suspension was stable for 30 days when stored at room temperature. Copyright © 2017 by the American Society of Health-System Pharmacists, Inc. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

    Nemati, Mahsa; Hosseini, Sayed Mohsen; Bagheripour, Ehsan [Faculty of Engineering, Arak University, Arak (Iran, Islamic Republic of); Madaeni, Sayed Siavash [Faculty of Engineering, Razi University, Kermanshah (Iran, Islamic Republic of)

    2016-03-15

    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.

  3. 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...

  4. Control system design of active seat suspensions

    Science.gov (United States)

    Maciejewski, I.

    2012-03-01

    This paper presents an approach to the control system design of seat suspension systems for the active vibration attenuation. The paper presents the studies of the active vibration control strategy based on the reverse dynamics of force actuator and the primary controller. The multi-criteria optimization procedure is utilized in order to calculate the primary controller settings which subsequently define the vibro-isolation characteristics of active suspensions. As an example of the proposed control system design, the seat with a pneumatic suspension is investigated and its vibro-isolation properties are shaped by an appropriate selection of the controller settings.

  5. 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.

  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. Formulation of Diblock Polymeric Nanoparticles through Nanoprecipitation Technique

    Science.gov (United States)

    Karve, Shrirang; Werner, Michael E.; Cummings, Natalie D.; Sukumar, Rohit; Wang, Edina C.; Zhang, Ying-Ao; Wang, Andrew Z.

    2011-01-01

    Nanotechnology is a relatively new branch of science that involves harnessing the unique properties of particles that are nanometers in scale (nanoparticles). Nanoparticles can be engineered in a precise fashion where their size, composition and surface chemistry can be carefully controlled. This enables unprecedented freedom to modify some of the fundamental properties of their cargo, such as solubility, diffusivity, biodistribution, release characteristics and immunogenicity. Since their inception, nanoparticles have been utilized in many areas of science and medicine, including drug delivery, imaging, and cell biology1-4. However, it has not been fully utilized outside of "nanotechnology laboratories" due to perceived technical barrier. In this article, we describe a simple method to synthesize a polymer based nanoparticle platform that has a wide range of potential applications. The first step is to synthesize a diblock co-polymer that has both a hydrophobic domain and hydrophilic domain. Using PLGA and PEG as model polymers, we described a conjugation reaction using EDC/NHS chemistry5 (Fig 1). We also discuss the polymer purification process. The synthesized diblock co-polymer can self-assemble into nanoparticles in the nanoprecipitation process through hydrophobic-hydrophilic interactions. The described polymer nanoparticle is very versatile. The hydrophobic core of the nanoparticle can be utilized to carry poorly soluble drugs for drug delivery experiments6. Furthermore, the nanoparticles can overcome the problem of toxic solvents for poorly soluble molecular biology reagents, such as wortmannin, which requires a solvent like DMSO. However, DMSO can be toxic to cells and interfere with the experiment. These poorly soluble drugs and reagents can be effectively delivered using polymer nanoparticles with minimal toxicity. Polymer nanoparticles can also be loaded with fluorescent dye and utilized for intracellular trafficking studies. Lastly, these polymer nanoparticles can be conjugated to targeting ligands through surface PEG. Such targeted nanoparticles can be utilized to label specific epitopes on or in cells7-10. PMID:21968609

  8. Decorrelation correction for nanoparticle tracking analysis of dilute polydisperse suspensions in bulk flow

    Science.gov (United States)

    Hartman, John; Kirby, Brian

    2017-03-01

    Nanoparticle tracking analysis, a multiprobe single particle tracking technique, is a widely used method to quickly determine the concentration and size distribution of colloidal particle suspensions. Many popular tools remove non-Brownian components of particle motion by subtracting the ensemble-average displacement at each time step, which is termed dedrifting. Though critical for accurate size measurements, dedrifting is shown here to introduce significant biasing error and can fundamentally limit the dynamic range of particle size that can be measured for dilute heterogeneous suspensions such as biological extracellular vesicles. We report a more accurate estimate of particle mean-square displacement, which we call decorrelation analysis, that accounts for correlations between individual and ensemble particle motion, which are spuriously introduced by dedrifting. Particle tracking simulation and experimental results show that this approach more accurately determines particle diameters for low-concentration polydisperse suspensions when compared with standard dedrifting techniques.

  9. Surface modification of textile fibers and cords by plasma polymerization for improvement of adhesion to polymeric matrices

    Science.gov (United States)

    Luo, Shijian

    In this work, aramid and polyester fibers and cords were treated in a continuous or pulsed DC plasma containing organic monomer vapor in custom-built reactors. Characterization indicated that, with one monomer under different deposition conditions, plasma-polymerized films were formed on the surface of fibers and cords with a variety of properties. The films significantly improve the adhesion performance of fibers and cords to polymeric matrices. The pull-out forces of treated samples were increased up to 90% compared to untreated ones. The lower power/high pressure (LW/HP) condition consistently gave better pull-out results than high power/low pressure (HW/LP) condition, no matter what monomer was used. Pulsing the input power also affected the adhesion performance positively. The effect of plasma polymerization on fiber strength is minimal. Plasma-polymerized films were thoroughly characterized by a range of analytical techniques. All the plasma polymer films were found highly unsaturated. The films prepared in LW/HP conditions were more unsaturated and less crosslinked than those deposited in HW/LP conditions. Some pyrrole ring structures were maintained in the plasma-polymerized pyrrole (PPy) films, while more rings remained intact in the mild LW/HP conditions. During atmospheric exposure, oxidation was found in both PPy and PAc (plasma-polymerized acetylene) films. It finished quickly in PPy films but occurred gradually in PAc films. Thin film interferometry and nano-indentation test showed that films deposited in LW/HP conditions had lower hardness, modulus and density. Partial rupture of the plasma film on the fiber surface was found in SFM after the fiber was pulled out from epoxy matrix. Based on the extensive data and failure interface analysis, a mechanical penetrating network mechanism for adhesion improvement was proposed. Besides the effect of oxygen-containing functional groups on the plasma-polymerized films, their hardness, modulus and crosslinking

  10. Formation and Properties of Molecular Loops at Polymeric Interfaces

    Science.gov (United States)

    Rice, J. Kevin

    2005-03-01

    In this study, we investigate the formation, kinetics, and resultant strength improvements of multiply bound polymer loops at multicomponent polymeric interfaces. We have first studied a model system consisting of a silicon substrate, an epoxy terminated monolayer, and dicarboxy terminated polystyrene to characterize the formation of the surface bound molecular loops. Interfacial strength improvement via loop formation in this model system has also been investigated using asymmetric double cantilever beam (ADCB) analysis. Further, the kinetics of loop formation at a soft interface between polystyrene and poly(methyl methacrylate) has been investigated with neutron reflectivity. This data will then be used to apply the technique to a range of real systems, such as layered-silicate or carbon nanotube filled polymeric systems, with the goal of improving dispersion and desired property enhancement within these systems.

  11. 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

  12. Integration of CuAAC Polymerization and Controlled Radical Polymerization into Electron Transfer Mediated "Click-Radical" Concurrent Polymerization.

    Science.gov (United States)

    Xue, Wentao; Wang, Jie; Wen, Ming; Chen, Gaojian; Zhang, Weidong

    2017-03-01

    The successful chain-growth copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) polymerization employing Cu(0)/pentamethyldiethylenetriamine (PMDETA) and alkyl halide as catalyst is first investigated by a combination of nuclear magnetic resonance, gel-permeation chromatography, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. In addition, the electron transfer mediated "click-radical" concurrent polymerization utilizing Cu(0)/PMDETA as catalyst is successfully employed to generate well-defined copolymers, where controlled CuAAC polymerization of clickable ester monomer is progressed in the main chain acting as the polymer backbone, the controlled radical polymerization (CRP) of acrylic monomer is carried out in the side chain. Furthermore, it is found that there is strong collaborative effect and compatibility between CRP and CuAAC polymerization to improve the controllability. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. 48 CFR 42.1302 - Suspension of work.

    Science.gov (United States)

    2010-10-01

    ... MANAGEMENT CONTRACT ADMINISTRATION AND AUDIT SERVICES Suspension of Work, Stop-Work Orders, and Government Delay of Work 42.1302 Suspension of work. A suspension of work under a construction or architect... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Suspension of work. 42...

  14. 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.

  15. Fabrication and the rheology of crystalline polyethylene microgels for thermo-responsive suspensions

    Science.gov (United States)

    Ling, Gerald H.

    Microgel suspensions have been studied and characterized extensively by many research groups in recent years. However, most of these suspensions are aqueous in nature with those exhibiting thermo-responsive characteristics being almost exclusively aqueous. The original impetus for this research dissertation was to develop a thermo-responsive microgel suspension that was completely organic in nature for use in high-performance lubricants. These suspensions would maintain or even increase in viscosity with increasing temperature. The focus of the dissertation eventually broadened to a more general approach encompassing soft, swellable particles in organic media. PE microgels were developed using mechanical fragmentation techniques as well as from immiscible blends of PS and PE. The microgels ranged in size from 127 +/- 2 microm to 0.944 +/- 0.003 microm and the size distributions were well-described using Log-Normal and Weibull distributions. The mechanical fragmentation method produced PE microgels with long surface chains that were capable of interparticle interactions when suspended in squalane. To study the effect of these interactions, the PE microgels produced from immiscible blends were modified to have minimal terminal PE chains or PS chains grafted on the surface. A variety of spectroscopy and electron microscopy techniques were employed to characterize the PE microgels especially the topology of PE microgels with grafted PS chains. Steady flow and small-strain oscillatory viscoelastic experiments were performed on the PE microgel suspensions to characterize the thermal response and interparticle interactions. The PE microgel suspensions exhibited an increase in steady-shear viscosity when the PE microgels melted and the magnitude of the increase was dependent on the PE microgel concentration. Dynamic temperature sweeps of the PE microgel suspensions showed evidence of interparticle interactions as evident from the formation of a gel.

  16. 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)

  17. 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...

  18. Numerical Study of Suspension Plasma Spraying

    CERN Document Server

    Farrokhpanah, Amirsaman; Mostaghimi, Javad

    2016-01-01

    A numerical study of suspension plasma spraying (SPS) is presented in the current work. The liquid suspension jet is replaced with a train of droplets containing the suspension particles injected into the plasma flow. Atomization, evaporation, and melting of different components are considered for particles as they travel towards the substrate. Effect of different parameters on particle conditions during flight and upon impact on the substrate are investigated. Initially, influence of the torch operating conditions such as inlet flow rate and power are studied. Additionally, effect of injector parameters like injection location, flow rate, and angle are examined. The model used in current study takes high temperature gradients and non-continuum effects into account. Moreover, the important effect of change in physical properties of suspension droplets as a result of evaporation is included in the model. These mainly include variations in heat transfer properties and viscosity. Utilizing this improved model, s...

  19. Suspension of rigid spheres in shear flows

    Science.gov (United States)

    Rahmani, Mona; Esteghamatian, Amir; Wachs, Anthony

    2017-11-01

    Suspension of rigid spheres in a plane Couette flow is studied using three-dimensional particle resolved numerical simulations. We use a fixed mesh that resolves each particle diameter using 24 points and a Distributed Lagrange Multi- plier/Fictitious Domain (DLM/FD) method. The effects of particle volume fraction and particle Reynolds number on the macrcoscopic and microscopic stresses in the suspension are examined. The kinematics of particle are also studied for a range of dilute to dense suspensions and Stokes to inertial flows. For dense suspensions and also for higher particle Reynolds numbers the particle/particle and particle/wall contacts are enhanced. For such cases, lubrication forces need to be taken into account. We compare simulations with and without the lubrication forces to conclude for what range of parameters lubrication should be incorporated into the simulations.

  20. 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 %.

  1. 21 CFR 26.16 - Suspension.

    Science.gov (United States)

    2010-04-01

    ... PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT REPORTS, AND CERTAIN... Provisions for Pharmaceutical Good Manufacturing Practices § 26.16 Suspension. (a) Each party has the right...

  2. Tips and tricks for uterosacral ligament suspension: how to avoid ureteral injury.

    Science.gov (United States)

    Manodoro, Stefano; Frigerio, Matteo; Milani, Rodolfo; Spelzini, Federico

    2018-01-01

    Uterosacral ligament (USL) suspension is an effective and versatile surgical technique for repairing pelvic organ prolapse. However, ureteral injury is a feared complication that may act as a significant deterrent to the use of USL suspension. The aim of the video is to provide key steps to minimize the risk of ureteral injury while achieving successful transvaginal USL suspension. The featured video provides a series of surgical tips and tricks that can be applied to protect the ureters while achieving USL suspension whether the procedure contemplated is vaginal hysterectomy, vaginal vault repair after hysterectomy, or hysteropexy. The tips and tricks are classified into four categories: identification of the USLs, identification of the ureters, passage of the sutures, and final measures. The USL suspension technique requires adequate surgical training and an understanding of pelvic anatomy. This tips and tricks video tutorial may be an important tool for improving surgical know-how, and thus for reducing the risk of ureteral injury. In particular, identification of the USLs and ureters, proper suture positioning and final cystoscopy are key points to minimize ureteral damage.

  3. 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.

  4. The Stabilizer-Free Emulsion Polymerization

    NARCIS (Netherlands)

    Dobrowolska, M.E.

    2013-01-01

    The research described in this thesis has been performed with the goal to understand and develop a method for stabilizer-free emulsion polymerization. In order to develop rules for this method, three main issues had to be understood: colloidal stability, emulsification method and polymerization

  5. Thermal bulk polymerization of cholesteryl acrylate

    NARCIS (Netherlands)

    de Visser, A.C.; de Groot, K.; Feijen, Jan; Bantjes, A.

    1971-01-01

    The thermal bulk polymerization of cholesteryl acrylate was carried out in the solid phase, the mesomorphic phase, and the liquid phase to study the effect of monomer ordering on polymerization rate and polymer properties. The rate increased with decreasing ordering (or enhanced mobility) of the

  6. Core Muscle Activation in Suspension Training Exercises

    OpenAIRE

    Cugliari, Giovanni; Boccia, Gennaro

    2017-01-01

    Abstract A quantitative observational laboratory study was conducted to characterize and classify core training exercises executed in a suspension modality on the base of muscle activation. In a prospective single-group repeated measures design, seventeen active male participants performed four suspension exercises typically associated with core training (roll-out, bodysaw, pike and knee-tuck). Surface electromyographic signals were recorded from lower and upper parts of rectus abdominis, ext...

  7. A comparison between two pneumatic suspension architectures

    OpenAIRE

    Scopesi, Marco; Franco, Walter; Quaglia, Giuseppe

    2012-01-01

    The aim of this work is to assess and compare the mathematical models of two pneumatic suspension architectures and show how they can converge, after appropriate simplifications, to a general linear form. After making this model dimensionless, it will be used to study, with a transmissibility analysis, the behaviour of a mono-suspension (quarter-car model). Finally, an example of a design process will be shown to highlight the strengths and weaknesses of both architectures and to provide the ...

  8. Rheology of Confined Non-Brownian Suspensions.

    Science.gov (United States)

    Fornari, Walter; Brandt, Luca; Chaudhuri, Pinaki; Lopez, Cyan Umbert; Mitra, Dhrubaditya; Picano, Francesco

    2016-01-08

    We study the rheology of confined suspensions of neutrally buoyant rigid monodisperse spheres in plane-Couette flow using direct numerical simulations. We find that if the width of the channel is a (small) integer multiple of the sphere diameter, the spheres self-organize into two-dimensional layers that slide on each other and the effective viscosity of the suspension is significantly reduced. Each two-dimensional layer is found to be structurally liquidlike but its dynamics is frozen in time.

  9. Melting in temperature sensitive suspensions

    Science.gov (United States)

    Alsayed, Ahmed M.

    We describe two experimental studies about melting in colloidal systems. In particular we studied melting of 1-dimensional lamellar phases and 3-dimensional colloidal crystals. In the first set of experiments we prepared suspensions composed of rodlike fd virus and the thermosensitive polymer, poly(N-isopropylacrylamide). The phase diagram of this systems is temperature and concentration dependent. Using video microscopy, we directly observed melting of lamellar phases and single lamellae into nematic phase. We found that lamellar phases swell with increasing temperature before melting into the nematic phase. The highly swollen lamellae can be superheated as a result of topological nucleation barriers that slow the formation of the nematic phase. In another set of experiments we prepared colloidal crystals from thermally responsive microgel spheres. The crystals are equilibrium close-packed three-dimensional structures. Upon increasing the temperature slightly above room temperature, particle volume fraction decreased from 0.74 to less than 0.5. Using video microscopy, we observed premelting at grain boundaries and dislocations within bulk colloidal crystals. Premelting is the localized loss of crystalline order at surfaces and defects at sample volume fractions above the bulk melting transition. Particle tracking revealed increased disorder in crystalline regions bordering defects, the amount of which depends on the type of defect, distance from the defect, and particle volume fraction. In total these observations suggest that interfacial free energy is the crucial parameter for premelting in colloidal and in atomic scale crystals.

  10. Ride responses of macpherson suspension systems

    Directory of Open Access Journals (Sweden)

    Yu Cheng-Chi

    2017-01-01

    Full Text Available The main purpose of this study is to obtain more correct vehicle ride responses by using a nonlinear ride model considering the effect of Macpherson suspension geometry. Traditional ride model applied to analysis and controller design uses a two degree of freedom linear model, which includes sprung mass and unsprung mass and a spring and a damper vertically connect them. In fact, suspension components do not vertically position above the tire. The motions of body and tire are not going straight up and down. Therefore, the analysis results obtained by the simple model are often different from the experimental values of the actual vehicle. Because of the difference between simple model and actual vehicle, the control strategy almost cannot apply to actual vehicle. In order to understand the effect of suspension geometry on the vehicle ride responses and design a more practical control strategy, a nonlinear model including the geometric parameters of the suspension is constructed in this study. To estimate the initial equilibrium position of the suspension assembly under load, the static equilibrium analysis and mechanism motion analysis are synchronous implemented at the same time. The nonlinear model describes not only the relative position and velocity but also the force transmission between body and tire. Furthermore, by linearize this nonlinear model the development of control strategy for subsequent (semi active suspension system could be expected.

  11. Core muscle activity during suspension exercises.

    Science.gov (United States)

    Mok, Nicola W; Yeung, Ella W; Cho, Jeran C; Hui, Samson C; Liu, Kimee C; Pang, Coleman H

    2015-03-01

    Suspension exercise has been advocated as an effective means to improve core stability among healthy individuals and those with musculoskeletal complaints. However, the activity of core muscles during suspension exercises has not been reported. In this study, we investigated the level of activation of core muscles during suspension exercises within young and healthy adults. The study was conducted in a controlled laboratory setting. Surface electromyographic (sEMG) activity of core muscles (rectus abdominis, external oblique, internal oblique/transversus abdominis, and superficial lumbar multifidus) during four suspension workouts (hip abduction in plank, hamstring curl, chest press, and 45° row) was investigated. Muscle activity during a 5-s hold period of the workouts was measured by sEMG and normalized to the individual's maximal voluntary isometric contraction (MVIC). Different levels of muscle activation were observed during the hip abduction in plank, hamstring curl, and chest press. Hip abduction in plank generated the highest activation of most abdominal muscles. The 45° row exercise generated the lowest muscle activation. Among the four workouts investigated, the hip abduction in plank with suspension was found to have the strongest potential strengthening effect on core muscles. Also, suspension training was found to generate relatively high levels of core muscle activation when compared with that among previous studies of core exercises on stable and unstable support surfaces. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  12. 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...

  13. Using a double-layered palmaris longus tendon for suspension of facial paralysis

    DEFF Research Database (Denmark)

    Toyserkani, Navid Mohamadpour; Bakholdt, Vivi; Sørensen, Jens Ahm

    2015-01-01

    INTRODUCTION: Facial palsy is a debilitating condition entailing both cosmetic and functional limitations. Static suspension procedures can be performed when more advanced dynamic techniques are not indicated. Since 2006, we have used a double-layered palmaris longus tendon graft through an ovula...

  14. Hemoglobin: Modification, Crystallization, Polymerization (Review

    Directory of Open Access Journals (Sweden)

    V. A. Sergunova

    2016-01-01

    Full Text Available The purpose of this review is to present the most significant modifications and transformations of a hemoglobin molecule potentially related to developing a strategy of resuscitation and treatment of lifethreatening forms of anemia. Hemoglobin is one of the wellstudied proteins. The paper reviews the history of hemoglobin studies from 1839 untill present. Methodically, the hemoglobin studies included electrophoresis, spectrophotometric method, Xray diffraction method, atomicforce microscopy. The basic forms of hemoglobin include oxyhemoglobin, deoxyhemoglobin and methemoglobin. Data on protein crystallization and polymerization are discussed. Many forms of hemoglobin have the ability to form crystals or polymers in vitro, some pathological forms can be modified in vivo. The studies of structural features of various hemoglobin forms represent a contemporary task for fundamental researches.

  15. Positron studies of polymeric coatings

    Energy Technology Data Exchange (ETDEWEB)

    Jean, Y.C. E-mail: jeany@umkc.edu; Mallon, P.E.; Zhang, R.; Chen Hongmin; Li Ying; Zhang Junjie; Wu, Y.C.; Sandreczki, T.C.; Suzuki, R.; Ohdaira, T.; Gu, X.; Nguyen, T

    2003-11-01

    In complicated coating systems, positrons have shown sensitivity in detecting the early stage of deterioration due to weathering, specially, in probing a specific location or depth of coatings from the surface through interfaces and the bulk. Existing extensive experimental positron data show that positron annihilation signals respond quantitatively to the deterioration process due to weathering. Now it is possible to detect the very early stage of coating deterioration at the atomic and molecular scale by using positrons, typically in days as compared to years by conventional methods. This paper summarizes recent positron studies in polymeric coatings. Correlations between positron data and a variety of chemical, physical and engineering data from ESR, AFM, cross-link density, gloss, and cyclic loading are presented.

  16. 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.

  17. Hemocompatibility of Polymeric Nanostructured Surfaces

    Science.gov (United States)

    Leszczak, Victoria; Smith, Barbara S.; Popat, Ketul C.

    2013-01-01

    Tissue integration is an important property when inducing transplant tolerance, however, the hemocompatibility of the biomaterial surface also plays an important role in the ultimate success of the implant. Therefore, in order to induce transplant tolerance, it is critical to understand the interaction of blood components with the material surfaces. In this study, we have investigated the adsorption of key blood serum proteins, in vitro adhesion and activation of platelets and clotting kinetics of whole blood on flat polycaprolactone (PCL) surfaces, nanowire (NW) surfaces and nanofiber (NF) surfaces. Previous studies have shown that polymeric nanostructured surfaces improve cell adhesion, proliferation and viability; however it is unclear how these polymeric nanostructured surfaces interact with the blood and its components. Protein adsorption results indicate that while there were no significant differences in total albumin adsorption on PCL, NW and NF surfaces, NW surfaces had higher total fibrinogen and immunoglobulin-G adsorption compared to NF and PCL surfaces. In contrast, NF surfaces had higher surface FIB and IgG adsorption compared to PCL and NW surfaces. Platelet adhesion and viability studies show more adhesion and clustering of platelets on the NF surfaces as compared to PCL and NW surfaces. Platelet activation studies reveal that NW surfaces have the highest percentage of unactivated platelets, whereas NF surfaces have the highest percentage of fully activated platelets. Whole blood clotting results indicate that NW surfaces maintain an increased amount of free hemoglobin during the clotting process compared to PCL and NF surface, indicating less clotting and slower rate of clotting on their surfaces. PMID:23848447

  18. Synthesis and characterization of the in situ bulk polymerization of PMMA containing graphene sheets using microwave irradiation.

    Science.gov (United States)

    Aldosari, Mohammad A; Othman, Ali A; Alsharaeh, Edreese H

    2013-03-11

    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, (1)H-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.

  19. 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.

  20. Stability of propranolol in extemporaneously compounded suspensions.

    Science.gov (United States)

    Ensom, Mary H H; Kendrick, Jennifer; Rudolph, Susan; Decarie, Diane

    2013-03-01

    Propranolol is a drug of choice for many diseases occurring in neonates and infants, an age group for which oral suspensions are required almost exclusively. Many adult and elderly patients for whom propranolol is prescribed are also unable to swallow solid dosage forms. In Canada, propranolol is not commercially available in a liquid dosage form, and existing recipes for extemporaneously compounded suspensions of propranolol (1 mg/mL) are limited by concerns regarding diabetes mellitus in certain subpopulations, the need for a more concentrated suspension for patients taking larger doses, and the tediousness of compounding. To evaluate the stability of propranolol suspensions in a sugar-free, commercially available vehicle after storage at room temperature and under refrigeration for up to 120 days. Suspensions of propranolol (2 and 5 mg/mL) were prepared in the sugar-free vehicle (Ora-Blend SF), placed in 100-mL amber plastic prescription bottles, and stored at 25°C and 4°C. Samples were collected from each bottle once weekly for 120 days, stored frozen, and analyzed by a validated, stability-indicating high-performance liquid chromatography - ultraviolet detection method. A suspension was considered stable if it maintained at least 90% of its initial concentration of propranolol. Physical compatibility was evaluated in terms of colour, taste, precipitation, and pH. Propranolol suspensions 2 mg/mL and 5 mg/mL stored at 25°C maintained at least 94.7% of their initial concentration for 120 days, and suspensions stored at 4°C maintained at least 93.9% of their initial concentration for 120 days. There were no notable changes in pH, and all samples remained physically unchanged except for a slight change in colour, around day 70, of suspensions stored at room temperature. Propranolol suspensions (2 mg/mL and 5 mg/mL) prepared in Ora-Blend SF and stored in plastic prescription bottles at either 25°C or 4°C are expected to remain stable for 120 days.

  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. Inorganic Surface Modification of Nonwoven Polymeric Substrates

    Science.gov (United States)

    Halbur, Jonathan Chandler

    In this study, atomic layer deposition (ALD), a vapor phase inorganic thin film deposition technique, is used to modify the surface of a range of industrially relevant polymers to enhance surface properties or impart additional functionalities. Several unique demonstrations of polymer surface modification are presented including uniform nanomaterial photodeposition to the surface of nonowoven fabrics and the first application of photocatalytic thin film coated nonwovens for advanced filtration of heavy metals from solution. Recent advances in polymer synthesis and processing technologies have resulted in the production of novel polymer systems with unique chemistries and sub-micron scale dimensions. As a result, advanced fiber systems have received much attention for potential use in a wide range of industrially and medically important applications such as advanced and selective filtration, catalysis, flexible electronics, and tissue engineering. However, tailoring the surface properties of the polymer is still needed in order to realize the full range of advanced applications, which can be difficult given the high complexity and non-uniformity of nonwoven polymeric structures. Uniform and controllable inorganic surface modification of nonwovens allows the introduction or modification of many crucial polymer properties with a wide range of application methods.

  3. Fenton-RAFT Polymerization: An "On-Demand" Chain-Growth Method.

    Science.gov (United States)

    Reyhani, Amin; McKenzie, Thomas G; Ranji-Burachaloo, Hadi; Fu, Qiang; Qiao, Greg G

    2017-05-29

    Fine control over the architecture and/or microstructure of synthetic polymers is fast becoming a reality owing to the development of efficient and versatile polymerization techniques and conjugation reactions. However, the transition of these syntheses to automated, programmable, and high-throughput operating systems is a challenging step needed to translate the vast potential of precision polymers into machine-programmable polymers for biological and functional applications. Chain-growth polymerizations are particularly appealing for their ability to form structurally and chemically well-defined macromolecules through living/controlled polymerization techniques. Even using the latest polymerization technologies, the macromolecular engineering of complex functional materials often requires multi-step syntheses and purification of intermediates, and results in sub-optimal yields. To develop a proof-of-concept of a framework polymerization technique that is readily amenable to automation requires several key characteristics. In this study, a new approach is described that is believed to meet these requirements, thus opening avenues toward automated polymer synthesis. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Measurement of rapid membrane permeation in cell suspensions by application of a generalized capillary method

    DEFF Research Database (Denmark)

    Klösgen, Beate; Schönert, Hansjürgen; Deuticke, Bernhard

    1988-01-01

    the diffusion process of a solute in a composite system was derived using a series-parallel-pathway model with explicit consideration of the diffusion pathways inside and between the cells. This renders the technique insensitive to unstirred layer effects. Any single cell population of known size distribution...... may be investigated. High permeabilities (above 5 · 10-3 cm/s) can be measured with the greatest precision, but lower permeabilities, down to a limit of about 5 · 10-4 cm/s, may also be determined by the method. Measurements in erythrocyte suspensions have been made using non...... of suspensions of membrane vesicles....

  5. 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.

  6. Melanosomal proteins--role in melanin polymerization.

    Science.gov (United States)

    Sharma, Savitha; Wagh, Sushama; Govindarajan, Raman

    2002-04-01

    Melanin, the major determinant of skin colour, is a tyrosine-based heteropolymer of indeterminate molecular weight. In vivo, melanin synthesis occurs within highly specialized organelles called melanosomes. Coated vesicles encapsulating the enzyme tyrosinase and tyrosinase related proteins, fuse with premelanosomes that contain structural proteins to form mature melanosomes. Coated vesicles and premelanosomes have been shown to have only melanin monomers but not the polymer. Our earlier results have clearly shown that the presence of proteins other than tyrosinase are critical for the post-tyrosinase steps of melanin polymerization at acidic pH. Proteins in melanosomes are difficult to purify because of their firm association with melanin. Thus, with progressive melanization, melanoproteins become progressively insoluble. In this paper, we discuss the isolation and purification of melanosomal proteins and their role in melanin polymerization. We have hypothesized that the initiation of polymerization and the binding of melanin to proteins are two discrete events and we have developed assays to quantify these events. Purified melanosomal proteins differ in their ability to polymerize melanin monomers. Further, we have also shown that two polypeptides (28 and 45 kDa) purified from melanosomes inhibit melanin polymerization but can bind preformed melanin. In conclusion, melanosomal proteins regulate melanin polymerization and differ in their ability to bind melanin. Polymerization and binding abilities of melanosomal proteins are specific to each protein and melanin-protein interaction is not nonspecific.

  7. Rheological behavior of oxide nanopowder suspensions

    Science.gov (United States)

    Cinar, Simge

    Ceramic nanopowders offer great potential in advanced ceramic materials and many other technologically important applications. Because a material's rheological properties are crucial for most processing routes, control of the rheological behavior has drawn significant attention in the recent past. The control of rheological behavior relies on an understanding of how different parameters affect the suspension viscosities. Even though the suspension stabilization mechanisms are relatively well understood for sub-micron and micron size particle systems, this knowledge cannot be directly transferred to nanopowder suspensions. Nanopowder suspensions exhibit unexpectedly high viscosities that cannot be explained with conventional mechanisms and are still a topic of investigation. This dissertation aims to establish the critical parameters governing the rheological behavior of concentrated oxide nanopowder suspensions, and to elucidate the mechanisms by which these parameters control the rheology of these suspensions. Aqueous alumina nanopowders were chosen as a model system, and the findings were extrapolated to other oxide nanopowder systems such as zirconia, yttria stabilized zirconia, and titania. Processing additives such as fructose, NaCl, HCl, NaOH, and ascorbic acid were used in this study. The effect of solids content and addition of fructose on the viscosity of alumina nanopowder suspensions was investigated by low temperature differential scanning calorimetry (LT-DSC), rheological, and zeta potential measurements. The analysis of bound water events observed in LT-DSC revealed useful information regarding the rheological behavior of nanopowder suspensions. Because of the significance of interparticle interactions in nanopowder suspensions, the electrostatic stabilization was investigated using indifferent and potential determining ions. Different mechanisms, e.g., the effect of the change in effective volume fraction caused by fructose addition and electrostatic

  8. Exploring release and recovery of nanomaterials from commercial polymeric nanocomposites

    Science.gov (United States)

    Busquets-Fité, Martí; Fernandez, Elisabet; Janer, Gemma; Vilar, Gemma; Vázquez-Campos, Socorro; Zanasca, R.; Citterio, C.; Mercante, L.; Puntes, Víctor

    2013-04-01

    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.

  9. 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.

  10. 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).

  11. Intrinsic viscosity of actively swimming microalgae suspensions

    Science.gov (United States)

    Ewoldt, Randy; Caretta, Lucas; Chengala, Anwar; Sheng, Jian

    2011-11-01

    Suspensions of actively swimming microorganisms exhibit an effective viscosity which may depend on volume fraction, cell shape, and the nature of locomotion (e.g. ``pushers'' vs. ``pullers''). Although several dilute-regime theories have been offered for active suspensions, no experimental study to our knowledge has been able to resolve the dilute-regime intrinsic viscosity of actively swimming microorganism suspensions. Here we use a cone-and-plate rheometer to experimentally measure the dynamic shear viscosity for motile and non-motile suspensions of unicellular green algae (Dunaliella primolecta, a biflagellated ``puller''). The low viscosity biological samples require careful experimental protocols to avoid settling and flow-induced migration, and to minimize precision error. With these protocols in place we can distinguish the intrinsic viscosity which we show is higher for the motile ``puller'' swimmers compared to the immobilized counterparts. This observation is consistent with recently proposed dilute-regime theories which predict that ``pullers'' should have a higher viscosity than non-motile suspensions.

  12. Inhalation delivery of proteins from ethanol suspensions.

    Science.gov (United States)

    Choi, W S; Murthy, G G; Edwards, D A; Langer, R; Klibanov, A M

    2001-09-25

    To circumvent inherent problems associated with pulmonary administration of aqueous-solution and dry-powder protein drugs, inhalation delivery of proteins from their suspensions in absolute ethanol was explored both in vitro and in vivo. Protein suspensions in ethanol of up to 9% (wt/vol) were readily aerosolized with a commercial compressor nebulizer. Experiments with enzymic proteins revealed that nebulization caused no detectable loss of catalytic activity; furthermore, enzyme suspensions in anhydrous ethanol retained their full catalytic activity for at least 3 weeks at room temperature. With the use of Zn(2+)-insulin, conditions were elaborated that produced submicron protein particles in ethanol suspensions. The latter (insulin/EtOH) afforded respirable-size aerosol particles after nebulization. A 40-min exposure of laboratory rats to 10 mg/ml insulin/EtOH aerosols resulted in a 2-fold drop in the blood glucose level and a marked rise in the serum insulin level. The bioavailability based on estimated deposited lung dose of insulin delivered by inhalation of ethanol suspension aerosols was 33% (relative to an equivalent s.c. injection), i.e., comparable to those observed in rats after inhalation administration of dry powder and aqueous solutions of insulin. Inhalation of ethanol in a relevant amount/time frame resulted in no detectable acute toxic effects on rat lungs or airways, as reflected by the absence of statistically significant inflammatory or allergic responses, damage to the alveolar/capillary barrier, and lysed and/or damaged cells.

  13. Extracted hair follicle outer root sheath cell suspension for pigment cell restoration in vitiligo

    Directory of Open Access Journals (Sweden)

    Anil Kumar

    2013-01-01

    Full Text Available Vitiligo surgery has come up a long way from punch skin grafts to epidermal cell suspension and latest to the extracted hair follicle outer root sheath cell suspension (EHF-ORS-CS transplantation. The progressive development from one technique to the other is always in a quest for the best. In the latest development- EHF-ORS-CS, which is an enriched source of follicular inactive melanocyte (melanocyte stem cells, seems to be a good addition to the prevailing cell-based therapies for vitiligo; however, need to be explored further in larger, and preferably randomized blinded studies. This review discusses the principle, technical details, and stem cell composition of hair follicular outer root sheath cell suspension.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

    2013-01-01

    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. PMID:23910263

  19. Monoacryloyl esters of carbohydrates: synthesis, polymerization and application in ceramic technology.

    Science.gov (United States)

    Wiecinska, Paulina; Mizerski, Tadeusz; Szafran, Mikolaj

    2014-10-13

    The article presents the interdisciplinary research among organic synthesis, chemistry of polymers and ceramic technology. It presents the synthesis of monoacryloyl esters of fructose and glucose that is 1-O-acryloyl-D-fructose and 3-O-acryloyl-D-glucose, conditions of their polymerization and application in shaping of advanced ceramic powders by the so called gelcasting method. The paper presents the influence of carbohydrate esters on the viscosity of Al2O3 suspensions and microstructure of final ceramic samples. The results showed that synthesized esters of saccharides can play the role of organic monomers able to polymerize in situ and self-cross-linking compounds in gelcasting. The paper presents the proposed structure of polymeric network which is formed from acryloyl ester of glucose during gelcasting process. The paper describes rheological behaviour of slurries composed of synthesized substances and A2O3 powders, wetting angles of alumina substrate by synthesized compounds, differences in glass transition temperatures of polymers and the microstructure of obtained final ceramic samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. 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 (

  1. Plasma polymerized hexamethyldisiloxane thin films for corrosion protection

    Science.gov (United States)

    Saloum, S.; Alkhaled, B.; Alsadat, W.; Kakhia, M.; Shaker, S. A.

    2018-01-01

    This study focused on the corrosion protection performance of plasma polymerized HMDSO thin films in two different corrosive medias, 0.3M NaCl and 0.3M H2SO4. The pp-HMDSO thin films were deposited on steel substrates for electrochemical tests using the potentiodynamic polarization technique, they were deposited also on aluminum and silicon substrates to investigate their resistance to corrosion, through the analysis of the degradation of microhardness and morphology, respectively, after immersion of the substrates for one week in the corrosive media. The results showed promising corrosion protection properties of the pp-HMDSO thin films.

  2. Radiolabeling of liposomes and polymeric micelles with PET-isotopes

    DEFF Research Database (Denmark)

    Jensen, Andreas Tue Ingemann

    This thesis is divided into three separate chapters that can be read independently. Chapter 1 is a general introduction, touching upon liposomes and polymeric micelles and radiolabeling with 18F and 64Cu. Chapter 2 and 3 address two separate research projects, each described below. A complete...... be done by labeling with radio isotopes. Isotopes that emit positrons (PET‐isotopes) can be detected by PET (positron emission tomography) technology, an accurate technique that has gained popularity in recent years. PET‐isotopes of interest include 18F and 64Cu. In addition to being a research tool...

  3. An Adaptive Neuro Fuzzy Hybrid Control Strategy for a Semiactive Suspension with Magneto Rheological Damper

    Directory of Open Access Journals (Sweden)

    Pipit Wahyu Nugroho

    2014-04-01

    Full Text Available The main function of a vehicle suspension system is to isolate the vehicle body from external excitation in order to improve passenger comfort and road holding and to stabilise its movement. This paper considers the implementation of an adaptive neuro fuzzy inference system (ANFIS with a fuzzy hybrid control technique to control a quarter vehicle suspension system with a semiactive magneto rheological (MR damper. A quarter car suspension model is set up with an MR damper and a semiactive controller consisting of a fuzzy hybrid skyhook-groundhook controller and an ANFIS model is also designed. The fuzzy hybrid controller is used to generate the desired control force, and the ANFIS is designed to model the inverse dynamics of MR damper in order to obtain a desired current. Finally, numerical simulations of the semiactive suspensions with the ANFIS-hybrid controller, the traditional hybrid controller, and passive suspension are compared. The results of simulations show that the proposed ANFIS-hybrid controller provides better isolation performance than the other controllers.

  4. 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.

  5. Backward-mode photoacoustic transducer for sensing optical scattering and ultrasonic attenuation: determining fraction consistencies in pulp suspensions

    Science.gov (United States)

    Zhao, Zuomin; Törmänen, Matti; Myllylä, Risto

    2010-02-01

    An innovative backward-mode photoacoustic transducer was developed, consisting of an optical fibre, a composite absorber, piezoelectric film and high impedance preamplifier. By receiving scattering light from a turbid suspension, the transducer produces a photoacoustic source in it. This source emits two photoacoustic waves travelling in opposite directions. The waves' amplitudes relate to the optical scattering properties of the suspension, and the echo of a wave returning from the suspension carries information of acoustic attenuation. By assessing the optical scattering and acoustic attenuation, fraction consistencies in a two-fractional suspension can be determined if one fraction dominantly scatters light and the other mainly attenuates ultrasound. This technique is used in this paper to investigate paper pulp suspensions. Pulp consists of wood celluloses and wood fines (or extra-added fillers in some cases), where cellulose lengths range from a few sub-millimetres to millimetres and fines/filler sizes are a few tens of micrometres or smaller. Due to their different size and shape, celluloses and fines (or fillers) have different optical scattering and acoustic attenuation properties. Experimental results showed that the transducer can measure pulp consistency with good linearity at least in the range from 0.5% to 3%, and that it can distinguish pulp cellulose from fines or fillers (TiO2 particles). Needless to say, this technique is also suitable for determining other suspensions in the food, pharmaceutical and mineral industries.

  6. Stability of dynamic response of suspension bridges

    Science.gov (United States)

    Capsoni, Antonio; Ardito, Raffaele; Guerrieri, Andrea

    2017-04-01

    The potential occurrence of internal parametric resonance phenomena has been recently indicated as a potential contributory cause of the appearance of critical dynamic states in long-span suspension bridges. At the same time, suspension bridges, in view of their flexibility, are prone to aeroelastic response, such as vortex shedding, torsional divergence and flutter. In this paper, a non-linear dynamic model of a suspension bridge is devised, with the purpose of providing a first attempt toward a unified framework for the study of aeroelastic and internal resonance instabilities. Inspired by the pioneering work of Herrmann and Hauger, the analyses have been based on a linearized formulation that is able to represent the main structural non-linear effects and the coupling given by aerodynamic forces. The results confirm that the interaction between aeroelastic effects and non-linear internal resonance leads to unstable conditions for wind speeds which can be lower than the critical threshold for standard aeroelastic predictions.

  7. 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.

  8. Anomalous electrical conductivity of nanoscale colloidal suspensions.

    Science.gov (United States)

    Chakraborty, Suman; Padhy, Sourav

    2008-10-28

    The electrical conductivity of colloidal suspensions containing nanoscale conducting particles is nontrivially related to the particle volume fraction and the electrical double layer thickness. Classical electrochemical models, however, tend to grossly overpredict the pertinent effective electrical conductivity values, as compared to those obtained under experimental conditions. We attempt to address this discrepancy by appealing to the complex interconnection between the aggregation kinetics of the nanoscale particles and the electrodynamics within the double layer. In particular, we model the consequent alterations in the effective electrophoretic mobility values of the suspension by addressing the fundamentals of agglomeration-deagglomeration mechanisms through the pertinent variations in the effective particulate dimensions, solid fractions, as well as the equivalent suspension viscosity. The consequent alterations in the electrical conductivity values provide a substantially improved prediction of the corresponding experimental findings and explain the apparent anomalous behavior predicted by the classical theoretical postulates.

  9. 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...

  10. Hydrocarbon polymeric binder for advanced solid propellant

    Science.gov (United States)

    Potts, J. E. (Editor)

    1972-01-01

    A series of DEAB initiated isoprene polymerizations were run in the 5-gallon stirred autoclave reactor. Polymerization run parameters such as initiator concentration and feed rate were correlated with the molecular weight to provide a basis for molecular weight control in future runs. Synthetic methods were developed for the preparation of n-1,3-alkadienes. By these methods, 1,3-nonadiene was polymerized using DEAB initiator to give an ester-telechelic polynonadiene. This was subsequently hydrogenated with copper chromite catalyst to give a hydroxyl terminated saturated liquid hydrocarbon prepolymer having greatly improved viscosity characteristics and a Tg 18 degrees lower than that of the hydrogenated polyisoprenes. The hydroxyl-telechelic saturated polymers prepared by the hydrogenolysis of ester-telechelic polyisoprene were reached with diisocyanates under conditions favoring linear chain extension gel permeation chromatography was used to monitor this condensation polymerization. Fractions having molecular weights above one million were produced.

  11. 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.

  12. 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...

  13. Characterization of Polymeric Nanofiltration Membranes

    Directory of Open Access Journals (Sweden)

    Simoncic, B.

    2007-11-01

    Full Text Available As membrane processes are increasingly used in industrial applications, there is a growing interest in methods of membrane characterization. Traditional membrane characteristics, such as cut-off value and pore size distribution, are being supplemented by membrane surface characteristics, such as charge density or zeta potential and hydrophobicity. This study, therefore, characterizes the three different polymeric membranes used (NFT-50, DL and DK. The molecular mass cut-off (MMCO value was determined using a set of reference solutes within the molecular range 150-600 Da, whereas streaming potential measurements enabled quantification of the surface charge characteristics. Hydrophobicity was studied using contact angle measurements. The results indicated that even though all three membranes had very similar layer compositions which consisted of poly(piperazneamide, as top layers they showed different values of measured quantitive. The NFT-50 membrane had the lowest MMCO value and the most hydrophilic membrane surface, followed by DK and DL. Membrane fouling as measured by flux reduction was determined by streaming potential measurements and accompanied by a positive change in zeta potential.

  14. Sono-RAFT Polymerization in Aqueous Medium.

    Science.gov (United States)

    McKenzie, Thomas G; Colombo, Enrico; Fu, Qiang; Ashokkumar, Muthupandian; Qiao, Greg G

    2017-09-25

    The ultrasonic irradiation of aqueous solution is demonstrated to be a suitable source of initiating radicals for a controlled radical polymerization when conducted in the presence of a thiocarbonylthio-containing reversible addition-fragmentation chain transfer (RAFT) agent. This allows for a highly "green" method of externally regulated/controlled polymerization with a potentially broad scope for polymerizable monomers and/or polymer structures. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. 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.

  16. 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.

  17. From Living Carbocationic to Living Radical Polymerization.

    Science.gov (United States)

    1994-06-30

    one another because of electrostatic repulsions. On the other hand, free radicals, which are the growing species in radical polymerization, very easily...1) degrees of polymerization will be observed. In ionic reactions, active species with various reactivities coexist ( free ions, ion pairs...between the active and dormant speches Is fast. In real systems, chain-breaking reactions do occur and cannot be entirely b avoided; bimolecular

  18. 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.

  19. 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.

  20. [Idiopathic loss of lateral tarsal suspension].

    Science.gov (United States)

    Troyano, J; Martín, E; Genol-Saavedra, I; García-Sánchez, J

    2007-06-01

    A 53-year-old man who showed a loss of tarsal suspension in the lateral third of both lower eyelids underwent lateral canthoplasty with a good post-operative result. Disinsertion of the union of the inferior tarsus with the lateral canthus, of unknown cause, is a very uncommon finding that has almost never been reported in the world literature. There are two cases described of eyelid elastolysis with loss of lateral tarsal suspension, as in our case, but both showed eyelid skin atrophy and had histopathologic confirmation. Our case did not have skin atrophy.