Methyl methacrylate oligomerically-modified clay and its poly(methyl methacrylate) nanocomposites

International Nuclear Information System (INIS)

Zheng Xiaoxia; Jiang, David D.; Wilkie, Charles A.

2005-01-01

A methyl methacrylate oligomerically-modified clay was used to prepare poly(methyl methacrylate) clay nanocomposites by melt blending and the effect of the clay loading level on the modified clay and corresponding nanocomposite was studied. These nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, thermogravimetric analysis and cone calorimetry. The results show a mixed intercalated/delaminated morphology with good nanodispersion. The compatibility between the methylacrylate-subsituted clay and poly(methyl methacrylate) (PMMA) are greatly improved compared to other oligomerically-modified clays

Thermal Properties of Polyurethane-Polyisocyanurate Foams Based on Poly(ethylene terephthalate) Waste

OpenAIRE

Irena VITKAUSKIENĖ; Ričardas MAKUŠKA; Uldis STIRNA; Ugis CABULIS

2011-01-01

A series of polyurethane-polyisocyanurate (PU-PIR) foams synthesized from PET-waste-derived aromatic polyester polyols (APP) was studied using thermogravimetric analysis, Cone calorimeter and burning tests. The effect of chemical structure of the APP containing fragments of glycerol, adipic acid, poly(propylene glycol) or hexanediol on thermal stability and flame resistance of the PU-PIR foams was elucidated. PU-PIR foams prepared from APP containing fragments of glycerol and/or adipic acid h...

In-situ Polymerization-modification Process and Foaming of Poly(ethylene terephthalate)

Institute of Scientific and Technical Information of China (English)

仲华; 奚桢浩; 刘涛; 赵玲

2013-01-01

Most of traditional linear poly(ethylene terephthalate) (PET) resins of relatively low molecular mass and narrow molecular mass distribution have low melt strength at foaming temperatures, which are not enough to support and keep cells. An in-situ polymerization-modification process with esterification and polycondensation stages was performed in a 2 L batch stirred reactor using pyromellitic dianhydride (PMDA) or pentaerythritol (PENTA) as modifying monomers to obtain PETs with high melt strength. The influence of amounts of modifying monomers on the properties of modified PET was investigated. It was found that the selected modifying monomers could effectively introduce branched structures into the modified PETs and improve their melt strength. With in-creasing the amount of the modifying monomer, the melt strength of the modified PET increased. But when the amount of PENTA reached 0.35%or PMDA reached 0.9%, crosslinking phenomenon was observed in the modified PET. Supercritical carbon dioxide (ScCO2) was employed as physical foaming agent to evaluate the foaming ability of modified PETs. The modified PETs had good foaming properties at 14 MPa of CO2 pressure with foaming tem-perature ranging from 265 °C to 280 °C. SEM micrographs demonstrated that both modified PET foams had ho-mogeneous cellular structures, with cell diameter ranging from 35 μm to 49 μm for PENTA modified PETs and 38μm to 57μm for PMDA modified ones. Correspondingly, the cell density had a range of 3.5×107 cells·cm-3 to 7×106 cells·cm-3 for the former and 2.8×107 cells·cm-3 to 5.8×106 cells·cm-3 for the latter.

Poly (ADP-ribose) metabolism in alkylated mouse L5178Y cells

International Nuclear Information System (INIS)

Boyle, J.M.

1985-01-01

Poly ADP-ribosylation of two mouse lymphoma cell lines, L5178Y (LS) and the radiation and alkylating agent resistant derivative AII, was investigated by uptake of [ 3 H]NAD by permeabilised cells into acid-precipitable material that was sensitive to phosphodiesterase but insensitive to DNase and RNase. Basal activities in both lymphoma lines were 3-4-fold greater than in mouse L1210 leukaemia cells. However, total endogenous poly (ADP-R) polymerase activity in both L5178Y cell lines, stimulated by a large excess of DNase in the presence of Triton X-100, was less than half the activity in L1210 cells. Doses of N-methyl-N-nitrosourea (MNU) that produced 20-50% survival of colony-forming units increased poly (ADP-R) in both lymphoma lines by only 25% compared with 377% in L1210 cells when synthesis was measured immediately after a 30-min exposure of MNU. Concentrations of 3-aminobenzamide (3AB) above 2.5 mM inhibited colony-forming ability of lymphoma cells and equally inhibited uptake of [ 14 C]formate into protein, RNA and DNA indicating that 3AB behaves as a general metabolic poison. Non-toxic concentrations of 3AB potentiated cell killing by MNU to a similar degree in both lymphoma cell lines. In conclusion, the authors have found little evidence to support the hypothesis that the differential sensitivity of LS and AII is related to poly ADP-ribosylation. Compared with other mouse cells, L5178Y cells appear deficient in poly (ADP-R) polymerase and poly (ADP-R) glycohydrolase activities

Dehydrogenation mechanism of LiBH{sub 4} by Poly(methyl methacrylate)

Energy Technology Data Exchange (ETDEWEB)

Huang, Jianmei [School of Materials Science and Engineering, and Key Laboratory of Advanced Energy Storage Materials of Guangdong Province, South China University of Technology, Guangzhou 510641 (China); China-Australia Joint Laboratory for Energy & Environmental Materials, South China University of Technology, Guangzhou 510641 (China); Yan, Yurong [School of Materials Science and Engineering, and Key Laboratory of Advanced Energy Storage Materials of Guangdong Province, South China University of Technology, Guangzhou 510641 (China); Ouyang, Liuzhang, E-mail: meouyang@scut.edu.cn [School of Materials Science and Engineering, and Key Laboratory of Advanced Energy Storage Materials of Guangdong Province, South China University of Technology, Guangzhou 510641 (China); China-Australia Joint Laboratory for Energy & Environmental Materials, South China University of Technology, Guangzhou 510641 (China); Key Laboratory for Fuel Cell Technology in Guangdong Province, South China University of Technology, Guangzhou 510641 (China); Wang, Hui [School of Materials Science and Engineering, and Key Laboratory of Advanced Energy Storage Materials of Guangdong Province, South China University of Technology, Guangzhou 510641 (China); China-Australia Joint Laboratory for Energy & Environmental Materials, South China University of Technology, Guangzhou 510641 (China); Zhu, Min, E-mail: memzhu@scut.edu.cn [School of Materials Science and Engineering, and Key Laboratory of Advanced Energy Storage Materials of Guangdong Province, South China University of Technology, Guangzhou 510641 (China); China-Australia Joint Laboratory for Energy & Environmental Materials, South China University of Technology, Guangzhou 510641 (China)

2015-10-05

Highlights: • LiBH{sub 4} is amorphous after modified with PMMA. • Dehydrogenation temperature of LiBH{sub 4} decreases by 120 °C after modifying with PMMA. • The LiBH{sub 4}@PMMA composite releases 10 wt.% hydrogen at 360 °C within 1 h. • C=O group of PMMA weakens the B−H bonds to lower dehydrogenation temperature. - Abstract: We investigated the dehydrogenation properties and mechanism of Poly(methyl methacrylate) (PMMA) confined LiBH{sub 4}. Thermal stability of LiBH{sub 4} was reduced by PMMA, with a decrease in dehydrogenation temperature by 120 °C. At 360 °C, the composite showed fast dehydrogenation kinetics with 10 wt.% of hydrogen released within 1 h. The improved dehydrogenation performance was mainly attributed to the reaction between LiBH{sub 4} and PMMA forming Li{sub 3}BO{sub 3} as a final product. Furthermore, the presence of electrostatic interaction between B atom of LiBH{sub 4} and O atom in the carbonyl group of PMMA may weaken the B−H bonding of [BH{sub 4}]{sup −} and lower the hydrogen desorption temperature.

Silica-Assisted Nucleation of Polymer Foam Cells with Nanoscopic Dimensions : Impact of Particle Size, Line Tension, and Surface Functionality

NARCIS (Netherlands)

Liu, Shanqiu; Eijkelenkamp, Rik; Duvigneau, Joost; Vancso, G. Julius

2017-01-01

Core-shell nanoparticles consisting of silica as core and surface-grafted poly(dimethylsiloxane) (PDMS) as shell with different diameters were prepared and used as heterogeneous nucleation agents to obtain CO2-blown poly(methyl methacrylate) (PMMA) nanocomposite foams. PDMS was selected as the shell

Hydroxyapatite fiber reinforced poly(alpha-hydroxy ester) foams for bone regeneration

Science.gov (United States)

Thomson, R. C.; Yaszemski, M. J.; Powers, J. M.; Mikos, A. G.; McIntire, L. V. (Principal Investigator)

1998-01-01

A process has been developed to manufacture biodegradable composite foams of poly(DL-lactic-co-glycolic acid) (PLGA) and hydroxyapatite short fibers for use in bone regeneration. The processing technique allows the manufacture of three-dimensional foam scaffolds and involves the formation of a composite material consisting of a porogen material (either gelatin microspheres or salt particles) and hydroxyapatite short fibers embedded in a PLGA matrix. After the porogen is leached out, an open-cell composite foam remains which has a pore size and morphology defined by the porogen. By changing the weight fraction of the leachable component it was possible to produce composite foams with controlled porosities ranging from 0.47 +/- 0.02 to 0.85 +/- 0.01 (n = 3). Up to a polymer:fiber ratio of 7:6, short hydroxyapatite fibers served to reinforce low-porosity PLGA foams manufactured using gelatin microspheres as a porogen. Foams with a compressive yield strength up to 2.82 +/- 0.63 MPa (n = 3) and a porosity of 0.47 +/- 0.02 (n = 3) were manufactured using a polymer:fiber weight ratio of 7:6. In contrast, high-porosity composite foams (up to 0.81 +/- 0.02, n = 3) suitable for cell seeding were not reinforced by the introduction of increasing quantities of hydroxyapatite short fibers. We were therefore able to manufacture high-porosity foams which may be seeded with cells but which have minimal compressive yield strength, or low porosity foams with enhanced osteoconductivity and compressive yield strength.

Thermal Properties of Polyurethane-Polyisocyanurate Foams Based on Poly(ethylene terephthalate Waste

Directory of Open Access Journals (Sweden)

Irena VITKAUSKIENĖ

2011-09-01

Full Text Available A series of polyurethane-polyisocyanurate (PU-PIR foams synthesized from PET-waste-derived aromatic polyester polyols (APP was studied using thermogravimetric analysis, Cone calorimeter and burning tests. The effect of chemical structure of the APP containing fragments of glycerol, adipic acid, poly(propylene glycol or hexanediol on thermal stability and flame resistance of the PU-PIR foams was elucidated. PU-PIR foams prepared from APP containing fragments of glycerol and/or adipic acid had higher thermal stability and lower weight loss at 330 °C. The foams based on APP derived from industrial PET waste were characterized by relatively low heat release and low smoke production. The presence of the fragments of the functional additives glycerol and/or adipic acid in the structure of APP used for production of PU-PIR foams, marginally decreased the heat release and slightly increased the smoke production.http://dx.doi.org/10.5755/j01.ms.17.3.588

High-Surface-Area, Emulsion-Templated Carbon Foams by Activation of polyHIPEs Derived from Pickering Emulsions

Directory of Open Access Journals (Sweden)

Robert T. Woodward

2016-09-01

Full Text Available Carbon foams displaying hierarchical porosity and excellent surface areas of >1400 m2/g can be produced by the activation of macroporous poly(divinylbenzene. Poly(divinylbenzene was synthesized from the polymerization of the continuous, but minority, phase of a simple high internal phase Pickering emulsion. By the addition of KOH, chemical activation of the materials is induced during carbonization, producing Pickering-emulsion-templated carbon foams, or carboHIPEs, with tailorable macropore diameters and surface areas almost triple that of those previously reported. The retention of the customizable, macroporous open-cell structure of the poly(divinylbenzene precursor and the production of a large degree of microporosity during activation leads to tailorable carboHIPEs with excellent surface areas.

Synthesis of block copolymers derived from N-trityl-(S)-serine and pyrene end-labeled poly(methyl methacrylate) or poly(N-isopropylacrylamide) via ATRP

International Nuclear Information System (INIS)

Buruiana, Emil C.; Podasca, Viorica; Buruiana, Tinca

2012-01-01

A new monomer bearing N-trityl-L-serine methyl ester in structure, methacryloyloxyethyl carbamoyloxy–N-trityl methyl serine (MTS), was prepared to be further polymerized by atom transfer radical polymerization (ATRP) with pyrene-endcapped poly(methyl methacrylate) (Py–PMMA–Br) or poly(N-isopropylacrylamide) (Py–PNIPA–Br). The resulting block copolymers, poly(methyl methacrylate–block–methacryloyloxyethyl carbamoyloxy–N-trityl methyl serine) (Py–PMMA–b–PMTS) and poly(N-isopropylacrylamide–block–methacryloyloxyethyl carbamoyloxy–N-trityl methyl serine (Py–PNIPA–b–PMTS) were characterized by 1 H ( 13 C) NMR, ultraviolet, FTIR and fluorescence spectroscopy, thermal analysis, differential scanning calorimetry (DSC), atomic force microscopy (AFM), scanning electron microscopy (SEM), and gel permeation chromatography (GPC) measurements. The chemical composition in Py–PMMA–b–PMTS was estimated from the 1 H NMR analysis that indicated a ratio of the repeating units of 46:19 (MMA:MTS). For the Py–PNIPA–b–PMTS the composition rate in the copolymer was 61:25 (NIPA:MTS). Quenching of the pyrene species with N,N-diethylaniline, nitrobenzene, nitrophenol, potassium iodide, p-nitrotoluene and tetracyanoquinodimethane (TCNQ) in DMF solution excited at 348 nm was evidenced, more efficiently being nitrophenol and TCNQ. In this case, the monomer emission at 388–409 nm underwent a significant decrease caused of an electron transfer from the electron-reach photoexcited pyrene molecule to the electron-deficient quenchers. - Highlights: ► Diblock copolymers combine the fluorescence of pyrene–PMMA (PNIPA) with the characteristics of PMTS. ► Such copolymers could be used for nitroderivatives detecting. ► UV/vis and fluorescence measurements give a good correlation for LCST of Py–PNIPA–Br.

Synthesis of block copolymers derived from N-trityl-(S)-serine and pyrene end-labeled poly(methyl methacrylate) or poly(N-isopropylacrylamide) via ATRP

Energy Technology Data Exchange (ETDEWEB)

Buruiana, Emil C., E-mail: emilbur@icmpp.ro [Petru Poni Institute of Macromolecular Chemistry, 41A Gr. Ghica Voda Alley 700487, Iasi (Romania); Podasca, Viorica; Buruiana, Tinca [Petru Poni Institute of Macromolecular Chemistry, 41A Gr. Ghica Voda Alley 700487, Iasi (Romania)

2012-10-15

A new monomer bearing N-trityl-L-serine methyl ester in structure, methacryloyloxyethyl carbamoyloxy-N-trityl methyl serine (MTS), was prepared to be further polymerized by atom transfer radical polymerization (ATRP) with pyrene-endcapped poly(methyl methacrylate) (Py-PMMA-Br) or poly(N-isopropylacrylamide) (Py-PNIPA-Br). The resulting block copolymers, poly(methyl methacrylate-block-methacryloyloxyethyl carbamoyloxy-N-trityl methyl serine) (Py-PMMA-b-PMTS) and poly(N-isopropylacrylamide-block-methacryloyloxyethyl carbamoyloxy-N-trityl methyl serine (Py-PNIPA-b-PMTS) were characterized by {sup 1}H ({sup 13}C) NMR, ultraviolet, FTIR and fluorescence spectroscopy, thermal analysis, differential scanning calorimetry (DSC), atomic force microscopy (AFM), scanning electron microscopy (SEM), and gel permeation chromatography (GPC) measurements. The chemical composition in Py-PMMA-b-PMTS was estimated from the {sup 1}H NMR analysis that indicated a ratio of the repeating units of 46:19 (MMA:MTS). For the Py-PNIPA-b-PMTS the composition rate in the copolymer was 61:25 (NIPA:MTS). Quenching of the pyrene species with N,N-diethylaniline, nitrobenzene, nitrophenol, potassium iodide, p-nitrotoluene and tetracyanoquinodimethane (TCNQ) in DMF solution excited at 348 nm was evidenced, more efficiently being nitrophenol and TCNQ. In this case, the monomer emission at 388-409 nm underwent a significant decrease caused of an electron transfer from the electron-reach photoexcited pyrene molecule to the electron-deficient quenchers. - Highlights: Black-Right-Pointing-Pointer Diblock copolymers combine the fluorescence of pyrene-PMMA (PNIPA) with the characteristics of PMTS. Black-Right-Pointing-Pointer Such copolymers could be used for nitroderivatives detecting. Black-Right-Pointing-Pointer UV/vis and fluorescence measurements give a good correlation for LCST of Py-PNIPA-Br.

Synthesis of Poly(cinnam-4'-yl methyl methacrylate) derivatives and their thermal stability as photoalignment layer

International Nuclear Information System (INIS)

Lee, Jong Woo; Kim, Hak Won; Kim, Hong Doo

2001-01-01

Photocyclizable poly(cinnam-4'-yl methyl methacrylate) derivatives bearing methoxy benzene (PMCMMA), anthracene (PACMMA), and coumarin (PCCMMMA) have been synthesized via Heck type reaction. Three different types of polymers are photoreactable using linearly polarized UV light and applicable as liquid crystal alignment layer. Anthracene and coumarin containing polymers (PACMMA, PCCMMA) have better thermal stability than PMCMMA. This observation may be attributed to the glass transition temperature elevation due to the bulky size and another photocrosslinking site provided by anthracene or coumarin group

The decolouration of methyl orange using aluminum foam, ultrasound and direct electric current

Science.gov (United States)

Liu, C. M.; Huang, X. Y.; Zhang, H. Y.; Dai, J. D.; Ning, C. C.

2018-01-01

The decolouration of methyl orange (MO) using aluminum (Al) foam, ultrasound and direct electric current (DC) is investigated. The decolouration rate (DR) of MO using only Al foam is low because there is a passivation oxide layer on the Al foam surface. Due to the low utilization of ultrasound in MO water solution medium, the DR of MO using only ultrasonic irradiation is also poor. The DR of MO is greatly increased when Al foam, ultrasonic irradiation and DC are used together. There is good synergistic effect between Al foam, ultrasound and DC in decolouration of MO. This enhancement of DR may be related to the cavitation, cleaning of Al foam surface and water electrolysis. Due to the surface charge on wire carrying stationary current, Al foam with DC acts like a serious anodes and cathodes and makes water electrolysis giving hydrogen gas to cleavage azo bond. The DC applied on Al foam is beneficial for reductive decolouration of MO. Our results show that DC is a new way for the reductive decolouration MO in water.

Bioglass {sup trademark} coated poly(DL-lactide) foams for tissue engineering scaffolds

Energy Technology Data Exchange (ETDEWEB)

Gough, J.E. [Materials Science Centre, UMIST, Manchester M1 7HS (United Kingdom); Arumugam, M. [Department of Materials Science and Metallurgy, University of Cambridge, Cambridge (United Kingdom); Blaker, J. [Department of Materials and Centre for Tissue Engineering and Regenerative Medicine, Imperial College London, London SW7 2BP (United Kingdom); Boccaccini, A.R. [Dept. of Materials and Center for Tissue Engineering and Regenerative Medicine, Imperial College London, London SW7 28P (United Kingdom)

2003-07-01

The purpose of this study was to prepare poly(DL-lactic acid) (PDLLA)/Bioglass trademark composites of foam-like structure, to measure the degree of bioactivity of the composites by studying the formation of hydroxyapatite (HA) after immersion in simulated body fluid (SBF) and to test the initial attachment of human osteoblasts within the porous network. It was found that crystalline HA formed on the Bioglass trademark coated PDLLA foams after 7 days of immersion in SBF. HA formed also on the surfaces of non-coated PDLLA foams, however the rate and amount of HA formation were much lower than in the composites. The rapid formation of HA on the Bioglass trademark /PDLLA foam surfaces confirmed the high bioactivity of these materials. Osteoblasts attached within the porous network throughout the depth of the foams. Cell density was found to be higher in the PDLLA/Bioglass trademark composites compared to the pure PDLLA foams. The composite foams developed here exhibit the required bioactivity to be used as scaffolds for bone tissue engineering. (Abstract Copyright [2003], Wiley Periodicals, Inc.) [German] Die vorliegende Arbeit befasst sich mit der Herstellung von poroesen Verbundwerkstoffen bestehend aus Poly(DL-Laktidsaeure) (PDLLA) und Bioglass trademark und der anschliessenden Untersuchung der Bioaktivitaet. Die Bioaktivitaet wurde anhand von In-vitro-Methoden untersucht: Durch Ermittlung der Bildungsrate von Hydroxylapatit (HA) auf der Oberflaeche nach Eintauchen in simulierter Koerperfluessigkeit (SBF) und mittels Zellkulturstudien mit menschlichen Osteoblasten. Nach 7 Tagen in SBF hatte die Bildung von kristallinem HA auf der Oberflaeche von mit Bioglass trademark -beschichteten PDLLA Schaeumen stattgefunden. Auf der Oberflaeche von unbeschichtetem PDLLA konnte ebenfalls die Bildung von HA gezeigt werden, jedoch war die Bildungsrate hier bedeutend langsamer verglichen mit den Verbundwerkstoffen. Die rasche Formung von HA auf der Bioglass trademark /PDLLA

Synthesis and Analysis of Methacryloyl-L-Alanine Methyl Ester using fourier Transform Nuclear Magnetic Resonance

International Nuclear Information System (INIS)

Tri Darwinto

2008-01-01

Methacryloyl-L-alanine methyl ester was synthesized by reacting methacrylic acid with L-alanine methyl ester hydrochloride in triethylamine at temperature of 90 o C. Hydrogel polymer of poly(methacryloyl-L-alanine methyl ester) was much used for diagnosis and therapy of vascular tumor. The molecular structure methacryloyl-L-alanine methyl ester analyzed by fourier transform nuclear magnetic resonance (FT-NMR) for analyzing of carbon atom ( 13 C) using Distortionless Enhancement by Polarization Transfer (DEPT) measurement mode with coupling as well as without coupling from proton atom ( 1 H). Molecular structure analysis result showed that DEPT FT-NMR measurement mode with coupling as well as without coupling from 1 H was very fast, exact and accurate method for molecular analysis of organic compound especially methacryloyl-L-alanine methyl ester. (author)

Process Development for Reactive-Ion Etching of Molybdenum Disulfide (MoS2) Utilizing a Poly(methyl methacrylate) (PMMA) Etch Mask

Science.gov (United States)

2017-10-01

Nichols, Matthew L Chin, Sina Najmaei, Eugene Zakar, and Madan Dubey Sensors and Electron Devices Directorate, ARL Approved for public...EBL; Vistec EBPG5000+) with an exposure dose of 850 μC/cm2 and development in 25 mL of isopropyl alcohol (IPA): 10 mL methyl isobutyl ketone for...deposition EBL electron beam lithography IPA isopropyl alcohol MoS2 molybdenum disulfide O2 oxygen PMMA poly(methyl methacrylate) RIE reactive

Segmental dynamics in poly(methyl acrylate)-poly(methyl methacrylate) sequential interpenetrating polymer networks: structural relaxation experiments

International Nuclear Information System (INIS)

Ribelles, J L Gomez; Duenas, J M Meseguer; Cabanilles, C Torregrosa; Pradas, M Monleon

2003-01-01

The miscibility of poly(methyl acrylate)-poly(methyl methacrylate) sequential interpenetrating polymer networks (IPNs) has been studied by probing the conformational mobility of the component polymer chains. These IPNs exhibit the phenomenon of forced compatibilization. In a conventional heating differential scanning calorimetry (DSC) thermogram, the highly cross-linked IPN shows a single glass transition which covers a temperature interval of around 100 d eg C; in contrast, loosely cross-linked IPNs show two glass transitions. The conformational mobility in these IPNs is studied by subjecting them to isothermal annealings at temperatures in the region of the glass transition and below it. The DSC scans measured after these treatments allow one to determine the temperature interval in which the sample is out of thermodynamic equilibrium but keeps enough conformational mobility to relax during the isothermal annealing in such a way that the enthalpy loss is measurable with the sensitivity of a conventional DSC. The results allow one to reach some conclusions about the compositional distribution of the IPN on the nanometre scale

Cytocompatibility of Plasma and Thermally Treated Biopolymers

Directory of Open Access Journals (Sweden)

Petr Slepička

2013-01-01

Full Text Available This paper is focused on the surface characterization of plasma and consequently thermally treated biocompatible polymers. PLLA (poly(L-lactide acid and PMP (poly-4-methyl-1-pentene are studied. The influence of Ar plasma treatment on the surface polarity of substrate measured immediately after treatment and during the polymer surface aging is studied. Surface roughness, morphology, wettability, and surface chemistry were determined. Plasma treatment leads to significant changes in PLLA surface morphology and chemistry, with the PMP being slightly affected. The higher resistance to plasma fluence results in smaller ablation of PMP than that of PLLA. The plasma treatment improves cell adhesion and proliferation on the PMP. Plasma treatment of PLLA influences mostly the homogeneity of adhered and proliferated VSMC.

Adsorption of lead from aqueous solutions by poly (methyl methacrylate)

International Nuclear Information System (INIS)

Din, M.; Hussain, R.

1992-01-01

The adsorption capability of commercially manufactured poly (methyl methacrylate) for lead in aqueous medium has been investigated. Percent adsorption and distribution coefficient values have been determined in relation to the shaking time, amount of adsorbent, pH effects and concentration of lead in the solution. The experimental results are compatible with Freundlich type of adsorption behavior. It is discernible from the experimental results that poly (methyl methacrylate) can be used for the removal of lead from slightly acidic aqueous solutions. (author)

Interfacial electrostatics of poly(vinylamine hydrochloride), poly(diallyldimethylammonium chloride), poly-l-lysine, and poly-l-arginine interacting with lipid bilayers.

Science.gov (United States)

McGeachy, A C; Dalchand, N; Caudill, E R; Li, T; Doğangün, M; Olenick, L L; Chang, H; Pedersen, J A; Geiger, F M

2018-04-25

Charge densities of cationic polymers adsorbed to lipid bilayers are estimated from second harmonic generation (SHG) spectroscopy and quartz crystal microbalance with dissipation monitoring (QCM-D) measurements. The systems surveyed included poly(vinylamine hydrochloride) (PVAm), poly(diallyldimethylammonium chloride) (PDADMAC), poly-l-lysine (PLL), and poly-l-arginine (PLR), as well as polyalcohol controls. Upon accounting for the number of positive charges associated with each polyelectrolyte, the binding constants and apparent free energies of adsorption as estimated from SHG data are comparable despite differences in molecular masses and molecular structure, with ΔGads values of -61 ± 2, -58 ± 2, -57 ± 1, -52 ± 2, -52 ± 1 kJ mol-1 for PDADMAC400, PDADMAC100, PVAm, PLL, and PLR, respectively. Moreover, we find charge densities for polymer adlayers of approximately 0.3 C m-2 for poly(diallyldimethylammonium chloride) while those of poly(vinylamine) hydrochloride, poly-l-lysine, and poly-l-arginine are approximately 0.2 C m-2. Time-dependent studies indicate that polycation adsorption to supported lipid bilayers is only partially reversible for most of the polymers explored. Poly(diallyldimethylammonium chloride) does not demonstrate reversible binding even over long timescales (>8 hours).

21 CFR 177.1635 - Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene).

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene). 177.1635 Section 177.1635 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components...

ToF-SIMS analysis of poly(L-lysine)-graft-poly(2-methyl-2-oxazoline) ultrathin adlayers.

Science.gov (United States)

Pidhatika, Bidhari; Chen, Yin; Coullerez, Geraldine; Al-Bataineh, Sameer; Textor, Marcus

2014-02-01

Understanding of the interfacial chemistry of ultrathin polymeric adlayers is fundamentally important in the context of establishing quantitative design rules for the fabrication of nonfouling surfaces in various applications such as biomaterials and medical devices. In this study, seven poly(L-lysine)-graft-poly(2-methyl-2-oxazoline) (PLL-PMOXA) copolymers with grafting density (number of PMOXA chains per lysine residue) 0.09, 0.14, 0.19, 0.33, 0.43, 0.56, and 0.77, respectively, were synthesized and characterized by means of nuclear magnetic resonance spectroscopy (NMR). The copolymers were then adsorbed on Nb2O5 surfaces. Optical waveguide lightmode spectroscopy method was used to monitor the surface adsorption in situ of these copolymers and provide information on adlayer masses that were then converted into PLL and PMOXA surface densities. To investigate the relationship between copolymer bulk architecture (as shown by NMR data) and surface coverage as well as surface architecture, time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis was performed. Furthermore, ToF-SIMS method combined with principal component analysis (PCA) was used to verify the protein resistant properties of PLL-PMOXA adlayers, by thorough characterization before and after adlayer exposure to human serum. ToF-SIMS analysis revealed that the chemical composition as well as the architecture of the different PLL-PMOXA adlayers indeed reflects the copolymer bulk composition. ToF-SIMS results also indicated a heterogeneous surface coverage of PLL-PMOXA adlayers with high grafting densities higher than 0.33. In the case of protein resistant surface, PCA results showed clear differences between protein resistant and nonprotein-resistant surfaces. Therefore, ToF-SIMS results combined with PCA confirmed that the PLL-PMOXA adlayer with brush architecture resists protein adsorption. However, low increases of some amino acid signals in ToF-SIMS spectra were detected after the adlayer has

Reversed preparation of low-density poly(divinylbenzene/styrene) foam columns coated with gold films

Energy Technology Data Exchange (ETDEWEB)

Dai, Yinhai; Wang, Ni; Li, Yaling; Yao, Mengqi; Gan, Haibo; Hu, Wencheng, E-mail: huwc@uestc.edu.cn

2016-06-15

Highlights: • A reversed fabrication of low density foam columns coated with gold films was proposed. • The uniformity in thickness and purity of gold film are easy to be controlled. • A compact layer is prepared through an electrophoretic deposition method. • A low density (12 mg/cc) foam column coated with gold film is obtained. - Abstract: This work aims to fabricate low-density, porous, non-conductive, structural poly(divinylbenzene/styrene) foam columns by high-internal-phase emulsion templating. We prepare these non-conductive foam columns coated with a thin gold layer by electrochemical deposition and the reversed preparation technique. As expected, the density of the foam obtained through this novel method was about 12 mg cm{sup −3}, and the thickness of the gold coating was about 3 μm. We performed field emission scanning electron microscopy to morphologically and microstructurally characterize the products and X-ray diffraction and energy dispersive spectroscopy to determine the composition of the gold coating.

Rheological Properties and Foaming Behavior of Poly(Ethylene Terephthalates) Modified with Pyromellitic Dianhydride

Science.gov (United States)

Yang, Zhao-Ping; Xin, Chun-Ling; Guo, Ya-Feng; Luo, Yi-Wei; He, Ya-Dong

2016-05-01

Improving the melt viscoelasticity of poly(ethylene terephthalate) (PET) is a well-known method to obtain foamable PET. The aim of this study is to prepare high melt strength PET and evaluate the influence of rheological properties of PET on the foaming behavior. For this purpose, pyromelliticdianhydride was used as the chain extender to modify a linear PET through melt reactive processing. The rheological properties of the unmodified and modified PETs were measured by a dynamic rheometer. Results showed that the modified PET had higher complex viscosity than the unmodified one. Furthermore, the batch foaming by using supercritical CO2 as a blowing agent was carried to evaluate the foamability of modified PETs. It was found that an enlarged foaming temperature window was obtained for modified PETs compared to unmodified PET. Moreover, the modified PETs foams exhibited higher expansion ratio, smaller cell size and higher cell density at high temperatures than the neat PET.

New Poly(amide-imide)/Nanocomposites Reinforced Silicate Nanoparticles Based on N-pyromellitimido-L-phenyl Alanine Containing Ether Moieties

Science.gov (United States)

Faghihi, Khalil; Shabanian, Meisam; Dadfar, Ehsan

2012-02-01

A series of Poly(amide-imide)/montmorillonite nanocomposites containing N-pyromellitimido-L-phenyl alanine moiety in the main chain were synthesized by a convenient solution intercalation technique. Poly(amide-imide) (PAI) 5 as a source of polymer matrix was synthesized by the direct polycondensation reaction of N-pyromellitimido-L-phenyl alanine 3 with 4,4'-diamino diphenyl ether 4 in the presence of triphenyl phosphite (TPP), CaCl2, pyridine and N-methyl-2-pyrrolidone (NMP). The resulting nanocomposite films were characterized by Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The results showed that organo-modified clay was dispersed homogeneously in PAI matrix. TGA indicated an enhancement of thermal stability of new nanocomposites compared with the pure polymer.

Biodegradable poly (lactic acid)/Cellulose nanocrystals (CNCs) composite microcellular foam: Effect of nanofillers on foam cellular morphology, thermal and wettability behavior.

Science.gov (United States)

Borkotoky, Shasanka Sekhar; Dhar, Prodyut; Katiyar, Vimal

2018-01-01

This article addresses the elegant and green approach for fabrication of bio-based poly (lactic acid) (PLA)/cellulose nanocrystal (CNCs) bionanocomposite foam (PLA/CNC) with cellular morphology and hydrophobic surface behavior. Highly porous (porosity >80%) structure is obtained with interconnected pores and the effect of CNCs in the cell density (N f ) and cell size of foams are thoroughly investigated by morphological analysis. The thermo-mechanical investigations are performed for the foam samples and almost ∼1.7 and ∼2.2 fold increase in storage modulus is observed for the compressive and tensile mode respectively. PLA/CNC based bionanocomposite foams displayed similar thermal stability as base PLA foam. Detailed investigations of decomposition behavior are studied by using hyphenated thermogravimetric analysis-fourier transmission infrared spectroscopy (TGA-FTIR) system. Almost ∼13% increment is observed in crystallinity at highest loading of CNCs compared to neat counterpart. To investigate the splitting and spreading phenomenon of the wettability of the samples, linear model is used to find the Young's contact angle and contact angle hysteresis (CAH). Besides, ∼6.1 folds reduction in the density of PLA and the nanocomposite foams compared to PLA carries much significance in specialized application areas where weight is an important concern. Copyright © 2017 Elsevier B.V. All rights reserved.

Construction of horizontal stratum landform-like composite foams and their methyl orange adsorption capacity

International Nuclear Information System (INIS)

Chen, Jiajia; Shi, Xiaowen; Zhan, Yingfei; Qiu, Xiaodan; Du, Yumin; Deng, Hongbing

2017-01-01

Highlights: • CS/REC/CNTs composite foams were prepared by unidirectional freeze-casting. • Horizontal stratum landform-like structure was successful built up in foam. • The addition of REC and CNTs promoted the mechanical properties of foam. • The introduction of REC and CNTs enhanced the adsorption capacity of foam on dye. - Abstract: Chitosan (CS)/rectorite (REC)/carbon nanotubes (CNTs) composite foams with good mechanical properties were successfully fabricated by unidirectional freeze-casting technique. The morphology of the foam showed the well-ordered porous three-dimensional layers and horizontal stratum landform-like structure. The holes on the layers looked like the wings of butterfly. Additionally, the X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy results indicated the successful addition of CNTs and REC. The intercalated REC with CS chains was confirmed by small-angle X-ray diffraction. The surface structure of the foams was also analyzed by Raman spectroscopy. The adsorption experiments showed that when the mass ratio of CS to REC was 10:1 and CNTs content was 20%, the composite foam performed best in adsorbing low concentration methyl orange, and the largest adsorption capacity was 41.65 mg/g.

Construction of horizontal stratum landform-like composite foams and their methyl orange adsorption capacity

Energy Technology Data Exchange (ETDEWEB)

Chen, Jiajia; Shi, Xiaowen; Zhan, Yingfei; Qiu, Xiaodan; Du, Yumin; Deng, Hongbing, E-mail: hbdeng@whu.edu.cn

2017-03-01

Highlights: • CS/REC/CNTs composite foams were prepared by unidirectional freeze-casting. • Horizontal stratum landform-like structure was successful built up in foam. • The addition of REC and CNTs promoted the mechanical properties of foam. • The introduction of REC and CNTs enhanced the adsorption capacity of foam on dye. - Abstract: Chitosan (CS)/rectorite (REC)/carbon nanotubes (CNTs) composite foams with good mechanical properties were successfully fabricated by unidirectional freeze-casting technique. The morphology of the foam showed the well-ordered porous three-dimensional layers and horizontal stratum landform-like structure. The holes on the layers looked like the wings of butterfly. Additionally, the X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy results indicated the successful addition of CNTs and REC. The intercalated REC with CS chains was confirmed by small-angle X-ray diffraction. The surface structure of the foams was also analyzed by Raman spectroscopy. The adsorption experiments showed that when the mass ratio of CS to REC was 10:1 and CNTs content was 20%, the composite foam performed best in adsorbing low concentration methyl orange, and the largest adsorption capacity was 41.65 mg/g.

Methylation effect on the ohmic resistance of a poly-GC DNA-like chain

Energy Technology Data Exchange (ETDEWEB)

Moura, F.A.B.F. de, E-mail: fidelis@fis.ufal.br [Instituto de Física, Universidade Federal de Alagoas, Maceió AL 57072-970 (Brazil); Lyra, M.L. [Instituto de Física, Universidade Federal de Alagoas, Maceió AL 57072-970 (Brazil); Almeida, M.L. de; Ourique, G.S.; Fulco, U.L.; Albuquerque, E.L. [Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970, Natal-RN (Brazil)

2016-10-14

We determine, by using a tight-binding model Hamiltonian, the characteristic current–voltage (IxV) curves of a 5-methylated cytosine single strand poly-GC DNA-like finite segment, considering the methyl groups attached laterally to a random fraction of the cytosine basis. Striking, we found that the methylation significantly impacts the ohmic resistance (R) of the DNA-like segments, indicating that measurements of R can be used as a biosensor tool to probe the presence of anomalous methylation. - Highlights: • Ohmic resistance of finite segments of poly-CG DNA-like segments. • Possibility for the development of biosensor devices. • Methylation effect and electronic transport in DNA-like segments.

Increased cellular uptake of lauryl gallate loaded in superparamagnetic poly(methyl methacrylate) nanoparticles due to surface modification with folic acid.

Science.gov (United States)

Feuser, Paulo Emilio; Arévalo, Juan Marcelo Carpio; Junior, Enio Lima; Rossi, Gustavo Rodrigues; da Silva Trindade, Edvaldo; Rocha, Maria Eliane Merlin; Jacques, Amanda Virtuoso; Ricci-Júnior, Eduardo; Santos-Silva, Maria Claudia; Sayer, Claudia; de Araújo, Pedro H Hermes

2016-12-01

Lauryl gallate loaded in superparamagnetic poly(methyl methacrylate) nanoparticles surface modified with folic acid were synthesized by miniemulsion polymerization in just one step. In vitro biocompatibility and cytotoxicity assays on L929 (murine fibroblast), human red blood, and HeLa (uterine colon cancer) cells were performed. The effect of folic acid at the nanoparticles surface was evaluated through cellular uptake assays in HeLa cells. Results showed that the presence of folic acid did not affect substantially the polymer particle size (~120 nm), the superparamagnetic behavior, the encapsulation efficiency of lauryl gallate (~87 %), the Zeta potential (~38 mV) of the polymeric nanoparticles or the release profile of lauryl gallate. The release profile of lauryl gallate from superparamagnetic poly(methyl methacrylate) nanoparticles presented an initial burst effect (0-1 h) followed by a slow and sustained release, indicating a biphasic release system. Lauryl gallate loaded in superparamagnetic poly(methyl methacrylate) nanoparticles with folic acid did not present cytotoxicity effects on L929 and human red blood cells. However, free lauryl gallate presented significant cytotoxic effects on L929 and human red blood cells at all tested concentrations. The presence of folic acid increased the cytotoxicity of lauryl gallate loaded in nanoparticles on HeLa cells due to a higher cellular uptake when HeLa cells were incubated at 37 °C. On the other hand, when the nanoparticles were incubated at low temperature (4 °C) cellular uptake was not observed, suggesting that the uptake occurred by folate receptor mediated energy-dependent endocytosis. Based on presented results our work suggests that this carrier system can be an excellent alternative in targeted drug delivery by folate receptor.

Screening for Methylated Poly(⌊-histidine with Various Dimethylimidazolium/Methylimidazole/Imidazole Contents as DNA Carrier

Directory of Open Access Journals (Sweden)

Shoichiro Asayama

2015-08-01

Full Text Available Methylated poly(l-histidine (PLH-Me, our original polypeptide, has controlled the contents of dimethylimidazolium, τ/π-methylimidazole and imidazole groups for efficient gene delivery. The screening for the PLH-Me as DNA carrier has been carried out by use of the PLH with 25 mol% (τ-methyl, 16 mol%; π-methyl, 17 mol%; deprotonated imidazole, 41 mol%, 68 mol% (τ-methyl, 16 mol%; π-methyl, 8 mol%; deprotonated imidazole, 8 mol% and 87 mol% (τ-methyl, 7 mol%; π-methyl, 4 mol%; deprotonated imidazole, 2 mol% dimethylimidazolium groups, that is, PLH-Me(25, PLH-Me(68 and PLH-Me(87, respectively. The screening of the chemical structure of PLH-Me has been carried out for DNA carrier properties, which are the stability of its DNA polyion complexes and gene expression. The DNA complexes with the 25 mol% and 68 mol% dimethylated PLH-Me possessed almost same ability to retain DNA, as compared with the 87 mol% dimethylated PLH-Me, which was examined by competitive exchange with dextran sulfate. From the gene transfection experiment against HepG2 cells, human hepatoma cell line, the PLH-Me(25/DNA complex was revealed to mediate highest gene expression. These results suggest that the dimethyl-imidazolium/methylimidazole/imidazole balance of the PLH-Me is important for DNA carrier design.

Combretastatin A4/poly(L-glutamic acid-graft-PEG conjugates self-assembled to nanoparticles

Directory of Open Access Journals (Sweden)

Yang Ou

2018-03-01

Full Text Available Combretastatin A4 (CA4 possesses varying ability to cause vascular disruption in tumors, while the short half-life, low water solubility and deactivation of many CA4 analogs during storage limited its antitumor efficacy and drug stability. A novel macromolecular conjugate of CA4 (CA4-PL was synthesized by covalent bonding of CA4 onto poly(L-glutamic acid-graft-polyethylene glycol (PLG-g-PEG via Yamaguchi reaction. The obtained CA4-PL was characterized by 1H NMR, GPC, and UV methods, and the properties of the nanoparticles composed of CA4-PL, including critical aggregation concentration, size and size distribution, and morphology, were investigated. CA4-PL can self-assemble to form micelle-like nanoparticles of 80~120 nm in diameter, which may have potential to improve the blood circulation period as well as the targetability of CA4, and find applications to treat various tumors when combined with traditional chemotherapy or radio therapy. Keywords: Combretastatin A4, Macromolecular conjugate, Poly(L-glutamic acid-graft-polyethylene glycol, Self-assemble, Nanoparticles

Controlled Grafting of Poly(methyl methacrylate) Brushes on Poly(vinylidene fluoride) Powders by Surface-initiated Atom Transfer Radical Polymerization

Institute of Scientific and Technical Information of China (English)

TANG Zhaoqi; LI Wei; LIU Lanqin; HUANG Lei; ZHOU Jin; YU Haiyin

2009-01-01

Controlled grafting of well-defined polymer brushes of methyl methacrylate (MMA) on the poly(vinylidene fluoride) (PVDF) powders was carded out by the surface-initiated atom transfer radical polymerization (ATRP). The ATRP initiator was anchored on the PVDF surface by alkaline treatment, followed by UV-induced bromination; then methyl methacrylate (MMA) was grafted onto the brominated PVDF by the ATRP technique. The chemical composition changes of PVDF were characterized by Fourier transform-infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). FT-IR and XPS results clearly indicated the successful graft of poly(methyl methacrylate) onto the PVDF surface.

Effects of water on starch-g-polystyrene and starch-g-poly(methyl acrylate) extrudates

International Nuclear Information System (INIS)

Henderson, A.M.; Rudin, A.

1982-01-01

Polystyrene and poly(methyl acrylate) were grafted onto wheat starch by gamma radiation and chemical initiation, respectively. The respective percent add-on values were 46 and 45; 68% of the polystyrene formed was grafted to starch, and corresponding proportion of poly(methyl acrylate) was 41%. The molecular weight distributions of the homopolymer and graft portions were characterized, and extrusion conditions were established for production of ribbon samples of starch-g-PS and starch-g-PMA. Both copolymer types were considerably weakened by soaking in water, and this effect was more immediate and drastic for starch-g-poly(methyl acrylate). Both graft copolymers regained their original tensile strengths on drying, but the poly(methyl acrylate) specimens did not recover their original unswollen dimensions and retained high breaking elongations characteristic of soaked specimens. Tensile and dynamic mechanical properties of extruded and molded samples of both graft polymers are reported, and plasticizing effects of water are summarized

Analysis of poly(styrene-co-methyl acrylate) and poly(styrene-co-butyl acrylate) by high-performance liquid chromatography

NARCIS (Netherlands)

Sparidans, R.W.; Claessens, H.A.; van Doremaele, G.H.J.; Herk, van A.M.

1990-01-01

Poly(styrene—co-methyl acrylate) and poly(styrene—co-butyl acrylate) were separated according to their chemical composition by gradient elution. The chromatographic separation on silica was optimized for a gradient ranging from n-heptane as a non-solvent to dichloromethane containing a small amount

40 CFR 721.9900 - Urea, condensate with poly[oxy(methyl-1,2-ethanediyl)]-α- (2-aminomethylethyl)-μ-(2-amino...

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Urea, condensate with poly[oxy(methyl... Substances § 721.9900 Urea, condensate with poly[oxy(methyl-1,2-ethanediyl)]-α- (2-aminomethylethyl)-μ-(2.... (1) The chemical substance urea, condensate with poly[oxy(methyl-1,2-ethanediyl)]-α-(2...

Supercritical Carbon Dioxide Assisted Processing of Silica/PMMA Nanocomposite Foams

Science.gov (United States)

Rende, Deniz; Schadler, Linda S.; Ozisik, Rahmi

2012-02-01

Polymer nanocomposite foams receive considerable attention in both scientific and industrial communities. These structures are defined as closed or open cells (pores) surrounded by bulk material and are widely observed in nature in the form of bone structure, sponge, corals and natural cork. Inspired by these materials, polymer nanocomposite foams are widely used in advanced applications, such as bone scaffolds, food packaging and transportation materials due to their lightweight and enhanced mechanical, thermal, and electrical properties compared to bulk polymer foams. The presence of the nanosized fillers facilitates heterogeneous bubble nucleation as a result, the number of bubbles increases while the average bubble size decreases. Therefore, the foam morphology can be controlled by the size, concentration, and surface chemistry of the nanofiller. In the current study, we used supercritical carbon dioxide as a foaming agent for silica/poly(methyl methacrylate), PMMA, foams. The silica nanoparticles were chemically modified by fluoroalkane chains to make them CO2-philic. The surface coverage was controlled via tethering density, and the effect of silica surface coverage and concentration on foam morphology was investigated through scanning electron microscopy and image processing. Results indicated that nanofiller concentration and filler surface chemistry (CO2-philicity) had tremendous effect on foam morphology but surface coverage did not have any effect.

Studies on mushroom flavours 2. Flavour compounds in coprinus comatus.

Science.gov (United States)

Dijkstra, F Y; Wikén, T O

1976-01-01

In an aqueous extract of fruit bodies of Coprinus comatus 3-octanone, 3-octanol, 1-octen-3-ol, 1-octanol, 2-methyl-2-penten-4-olide, 1-dodecanol and caprylic acid were identified conclusively and n-butyric and isobutyric acids preliminarily. Amino-acids, nucleotides and sugars were also determined. A mixture of 37 compounds found in the extract had a stronger flavour than the natural extract. 3-Octanol, 1-octen-3-ol, 1-octanol and 2-methyl-2-penten-4-olide were the volatiles with the strongest flavour. Mass and IR spectra of 2-methyl-2-penten-4-olide are presented.

Investigation of Complexation of Linear Poly(N-vinyl-2-pyrrolidone) with Poly(methacrylic acid-co-methyl methacrylate) Gel

OpenAIRE

Liu, Guoqin; Yan, Guojin; Zou, Wenjun; Li, Zhengxin

2011-01-01

The contraction of poly(methacrylic acid-co-methyl methacrylate) (P(MAA-co-MMA)) gel induced by complexation with linear poly(N-vinyl-2-pyrrolidone) (PVP) is quite different from that of poly(acrylic acid) (PAA) or poly(methacrylic acid) (PMAA) gel. It was found that the concentration of PVP has a strong effect on the complexation with P(MAA-co-MMA) gel. When PVP was introduced into the P(MAA-co-MMA) network, its dynamic mechanic properties vary greatly between complexed and uncomplexed netwo...

Observations of crystallization and melting in poly(ethylene oxide)/poly(methyl methacrylate) blends by hot-stage atomic-force microscopy

NARCIS (Netherlands)

Pearce, R.; Vancso, Gyula J.

1998-01-01

The binary blend of poly(ethylene oxide)/atactic poly(methyl methacrylate) is examined using hot-stage atomic-force microscopy (AFM) in conjunction with differential scanning calorimetry and optical microscopy. It was found possible to follow in real time the melting process, which reveals itself to

Synthesis and Phase Behavior of Poly(N-isopropylacrylamide-b- Poly(L-Lysine Hydrochloride and Poly(N-Isopropylacrylamide- co-Acrylamide-b-Poly(L-Lysine Hydrochloride

Directory of Open Access Journals (Sweden)

Milica Spasojević

2014-07-01

Full Text Available The synthesis of poly(N-isopropylacrylamide-b-poly(L-lysine and poly(N- isopropylacrylamide-co-acrylamide-b-poly(L-lysine copolymers was accomplished by combining atom transfer radical polymerization (ATRP and ring opening polymerization (ROP. For this purpose, a di-functional initiator with protected amino group was successfully synthetized. The ATRP of N-isopropylacrylamide yielded narrowly dispersed polymers with consistent high yields (~80%. Lower yields (~50% were observed when narrowly dispersed random copolymers of N-isopropylacrylamide and acrylamide where synthesized. Amino-terminated poly(N-isopropylacrylamide and poly(N-isopropylacrylamide- co-acrylamide were successfully used as macroinitiators for ROP of N6-carbobenzoxy-L- lysine N-carboxyanhydride. The thermal behavior of the homopolymers and copolymers in aqueous solutions was studied by turbidimetry, dynamic light scattering (DLS and proton nuclear magnetic resonance spectroscopy (1H-NMR.

Modification of Foamed Articles Based on Cassava Starch

International Nuclear Information System (INIS)

Ponce, P.

2006-01-01

This work reports the influence of radiation, plasticizers and poly vinyl alcohol (PVA) on the barrier properties [water vapour permeability (WVP)) and mechanical properties (tensile strength and elongation; compression resistance and flexibility) of foamed articles based on cassava starch. The starch foam was obtained by thermopressing process. Poly ethylene glycol (PEG, 300) was selected as plasticizer and water was necessary for the preparation of the foams. The foamed articles based on cassava starch were irradiated at low doses of 2 and 5 kGy, commonly used in food irradiation. The mechanical properties of starch foams are influenced by the plasticizer concentration and by irradiation dose. An increase in PEG content showed a considerable increase in elongation percentage and a decrease in the tensile strength of the foams; also increase the permeability of the foams in water. After irradiation, the barrier properties and mechanical properties of the foams were improved due to chemical reactions among polymer molecules. Irradiated starch cassava foams with poly vinyl alcohol (PVA) have good flexibility and low water permeability. WVP can be reduced by low doses of gamma radiation

Influence of acrylonitrile butadiene rubber on recyclability of blends prepared from poly(vinyl chloride) and poly(methyl methacrylate).

Science.gov (United States)

Suresh, Sunil S; Mohanty, Smita; Nayak, Sanjay K

2018-06-01

The current investigation deals with the recycling possibilities of poly(vinyl chloride) and poly(methyl methacrylate) in the presence of acrylonitrile butadiene rubber. Recycled blends of poly(vinyl chloride)/poly(methyl methacrylate) are successfully formed from the plastic constituents, those are recovered from waste computer products. However, lower impact performance of the blend and lower stability of the poly(vinyl chloride) phase in the recycled blend restricts its further usage in industrial purposes. Therefore, effective utilisation acrylonitrile butadiene rubber in a recycled blend was considered for improving mechanical and thermal performance. Incorporation of acrylonitrile butadiene rubber resulted in the improvement in impact performance as well as elongation-at-break of the recycled blend. The optimum impact performance was found in the blend with 9 wt% acrylonitrile butadiene rubber, which shows 363% of enhancement as compared with its parent blend. Moreover, incorporated acrylonitrile butadiene rubber also stabilises the poly(vinyl chloride) phase present in the recycled blend, similarly Fourier transform infrared spectroscopy studies indicate the interactions of various functionalities present in the recycled blend and acrylonitrile butadiene rubber. In addition to this, thermogravimetric analysis indicates the improvement in the thermal stability of the recycled blend after the addition of acrylonitrile butadiene rubber into it. The existence of partial miscibility in the recycled blend was identified using differential scanning calorimetry and scanning electron microscopy.

2′-O Methylation of Internal Adenosine by Flavivirus NS5 Methyltransferase

Science.gov (United States)

Dong, Hongping; Chang, David C.; Hua, Maggie Ho Chia; Lim, Siew Pheng; Chionh, Yok Hian; Hia, Fabian; Lee, Yie Hou; Kukkaro, Petra; Lok, Shee-Mei; Dedon, Peter C.; Shi, Pei-Yong

2012-01-01

RNA modification plays an important role in modulating host-pathogen interaction. Flavivirus NS5 protein encodes N-7 and 2′-O methyltransferase activities that are required for the formation of 5′ type I cap (m7GpppAm) of viral RNA genome. Here we reported, for the first time, that flavivirus NS5 has a novel internal RNA methylation activity. Recombinant NS5 proteins of West Nile virus and Dengue virus (serotype 4; DENV-4) specifically methylates polyA, but not polyG, polyC, or polyU, indicating that the methylation occurs at adenosine residue. RNAs with internal adenosines substituted with 2′-O-methyladenosines are not active substrates for internal methylation, whereas RNAs with adenosines substituted with N6-methyladenosines can be efficiently methylated, suggesting that the internal methylation occurs at the 2′-OH position of adenosine. Mass spectroscopic analysis further demonstrated that the internal methylation product is 2′-O-methyladenosine. Importantly, genomic RNA purified from DENV virion contains 2′-O-methyladenosine. The 2′-O methylation of internal adenosine does not require specific RNA sequence since recombinant methyltransferase of DENV-4 can efficiently methylate RNAs spanning different regions of viral genome, host ribosomal RNAs, and polyA. Structure-based mutagenesis results indicate that K61-D146-K181-E217 tetrad of DENV-4 methyltransferase forms the active site of internal methylation activity; in addition, distinct residues within the methyl donor (S-adenosyl-L-methionine) pocket, GTP pocket, and RNA-binding site are critical for the internal methylation activity. Functional analysis using flavivirus replicon and genome-length RNAs showed that internal methylation attenuated viral RNA translation and replication. Polymerase assay revealed that internal 2′-O-methyladenosine reduces the efficiency of RNA elongation. Collectively, our results demonstrate that flavivirus NS5 performs 2′-O methylation of internal adenosine of

Investigation of Complexation of Linear Poly(N-vinyl-2-pyrrolidone with Poly(methacrylic acid-co-methyl methacrylate Gel

Directory of Open Access Journals (Sweden)

Guoqin Liu

2011-01-01

Full Text Available The contraction of poly(methacrylic acid-co-methyl methacrylate (P(MAA-co-MMA gel induced by complexation with linear poly(N-vinyl-2-pyrrolidone (PVP is quite different from that of poly(acrylic acid (PAA or poly(methacrylic acid (PMAA gel. It was found that the concentration of PVP has a strong effect on the complexation with P(MAA-co-MMA gel. When PVP was introduced into the P(MAA-co-MMA network, its dynamic mechanic properties vary greatly between complexed and uncomplexed networks. It had the following results: (1 the higher modulus ratio; (2 a slight contraction of gel.

A novel polymer of Al2(SO43-poly(acrylamide-co-2-acrylamido-2-methyl-1-propanesulfonate ionic hybrid prepared by dispersion polymerization

Directory of Open Access Journals (Sweden)

2010-03-01

Full Text Available A novel polymer Al2(SO43-poly(acrylamide-co-2-acrylamido-2-methyl-1-propanesulfonate (Al2(SO43-P(AM/AMPS had been synthesized by dispersion polymerization in an aqueous solution of ammonium sulfate and aluminum sulfate, using poly(2-acrylamido-2-methyl-1-propanesulfonate P(AMPS as stabilizer, acrylamide (AM and 2-acrylamido-2-methyl-1-propanesulfonate (AMPS as monomers, poly(2-acrylamido-2-methyl-1-propanesulfonate (PAMPS as stabilizer and [2-(2-imidazdino-2-ylpropane]dihydrochloride (VA-044 as initiator. The average particle size of polymer dispersion ranged from 0.2 to 0.3 µm, the molecular weight was from 4.3•106 to 5.7•106 g•mol-1. The polymer was characterized by infrared (IR spectroscopy, thermogravimetry (TGA and transmission electron microscopy (TEM. The swelling property of the dispersion polymer was studied by particle size distribution. When the polymer dispersion was diluted with deionized water, particle sizes decreased several times. When the polymer dispersion was diluted with salt water, the particle size increased with increasing concentration of salt. The effects of Al2(SO43 and stabilizer on the particle size and the relative molecular weight of the polymer were investigated, respectively. The optimum conditions for the stable Al2(SO43-P(AM/AMPS dispersion were that the concentration of Al2(SO43 was 1.12 wt%, the concentration of PAMPS stabilizer was 3 wt% and the concentration of initiator was 0.2 mol•l-1 and the monomers concentration was 14 wt%.

Emissivity Measurements of Foam-Covered Water Surface at L-Band for Low Water Temperatures

Directory of Open Access Journals (Sweden)

En-Bo Wei

2014-11-01

Full Text Available For a foam-covered sea surface, it is difficult to retrieve sea surface salinity (SSS with L-band brightness temperature (1.4 GHz because of the effect of a foam layer with wind speeds stronger than 7 m/s, especially at low sea surface temperature (SST. With foam-controlled experiments, emissivities of a foam-covered water surface at low SST (−1.4 °C to 1.7 °C are measured for varying SSS, foam thickness, incidence angle, and polarization. Furthermore, a theoretical model of emissivity is introduced by combining wave approach theory with the effective medium approximation method. Good agreement is obtained upon comparing theoretical emissivities with those of experiments. The results indicate that foam parameters have a strong influence on increasing emissivity of a foam-covered water surface. Increments of experimental emissivities caused by foam thickness of 1 cm increase from about 0.014 to 0.131 for horizontal polarization and 0.022 to 0.150 for vertical polarization with SSS increase and SST decrease. Contributions of the interface between the foam layer and water surface to the foam layer emissivity increments are discussed for frequencies between 1 and 37 GHz.

Hyperproduction of poly(4-hydroxybutyrate) from glucose by recombinant Escherichia coli

DEFF Research Database (Denmark)

Zhou, Xiao-Yun; Yuan, Xiao-Xi; Shi, Zhen-Yu

2012-01-01

inactivated to enhance the carbon flux to poly(4HB) biosynthesis. Four PHA binding proteins (PhaP or phasins) including PhaP1, PhaP2, PhaP3 and PhaP4 from R. eutropha were heterologously expressed in the recombinant E. coli, respectively, leading to different levels of improvement in poly(4HB) production......-hydroxybutyrate or 1,4-butanediol (1,4-BD) are provided as precursor which are much more expensive than glucose. At present, high production cost is a big obstacle for large scale production of poly(4HB). RESULTS: Recombinant Escherichia coli strain was constructed to achieve hyperproduction of poly(4....... Among them PhaP1 exhibited the highest capability for enhanced polymer synthesis. The recombinant E. coli produced 5.5 g L(-1) cell dry weight containing 35.4% poly(4HB) using glucose as a sole carbon source in a 48 h shake flask growth. In a 6-L fermentor study, 11.5 g L(-1) cell dry weight containing...

Poly(vinyl methyl ether/maleic anhydride)-Doped PEG-PLA Nanoparticles for Oral Paclitaxel Delivery To Improve Bioadhesive Efficiency.

Science.gov (United States)

Wang, Qian; Li, Chan; Ren, Tianyang; Chen, Shizhu; Ye, Xiaoxia; Guo, Hongbo; He, Haibing; Zhang, Yu; Yin, Tian; Liang, Xing-Jie; Tang, Xing

2017-10-02

Bioadhesive nanoparticles based on poly(vinyl methyl ether/maleic anhydride) (PVMMA) and poly(ethylene glycol) methyl ether-b-poly(d,l-lactic acid) (mPEG-b-PLA) were produced by the emulsification solvent evaporation method. Paclitaxel was utilized as the model drug, with an encapsulation efficiency of up to 90.2 ± 4.0%. The nanoparticles were uniform and spherical in shape and exhibited a sustained drug release compared with Taxol. m-NPs also exhibited favorable bioadhesive efficiency at the same time. Coumarin 6 or DiR-loaded nanoparticles with/without PVMMA (C6-m-NPs/DiR-m-NPs or C6-p-NPs/DiR-p-NPs) were used for cellular uptake and intestinal adhesion experiments, respectively. C6-m-NPs were shown to enhance cellular uptake, and caveolae/lipid raft mediated endocytosis was the primary route for the uptake of the nanoparticles. Favorable bioadhesive efficiency led to prolonged retention in the intestine reflected by the fluorescence in isolated intestines ex vivo. In a ligated intestinal loops model, C6-m-NPs showed a clear advantage for transporting NPs across the mucus layer over C6-p-NPs and free C6. The apparent permeability coefficient (Papp) of PTX-m-NPs through Caco-2/HT29 monolayers was 1.3- and 1.6-fold higher than PTX-p-NPs and Taxol, respectively, which was consistent with the AUC 0-t of different PTX formulations after oral administration in rats. PTX-m-NPs also exhibited a more effective anticancer efficacy, with an IC 50 of 0.2 ± 1.4 μg/mL for A549 cell lines, further demonstrating the advantage of bioadhesive nanoparticles. The bioadhesive nanoparticles m-NPs demonstrated both mucus permeation and epithelial absorption, and thus, this bioadhesive drug delivery system has the potential to improve the bioavailability of drugs that are insoluble in the gastrointestinal environment.

Development of a sirolimus-eluting poly (L-lactide)/poly(4-hydroxybutyrate) absorbable stent for peripheral vascular intervention.

Science.gov (United States)

Grabow, Niels; Bünger, Carsten M; Kischkel, Sabine; Timmermann, J Hinrich; Reske, Thomas; Martin, David P; Williams, Simon F; Schareck, Wolfgang; Sternberg, Katrin; Schmitz, Klaus-Peter

2013-10-01

Fully absorbable drug-eluting stent platforms are currently entering the clinical arena for the interventional treatment of coronary artery disease. This new technology also holds potential for application in peripheral vascular settings. Our study reports on the development of a sirolimus- (SIR) eluting absorbable polymer stent made from a blend of poly(l-lactide) and poly(4-hydroxybutyrate) (PLLA/P4HB) for peripheral vascular intervention. Stent prototypes were laser-cut from PLLA/P4HB tubes (I.D.=2.2 mm, t=250 µm), spray-coated with different PLLA/P4HB/SIR solutions, and bench-tested to determine expansion properties, fatigue, trackability and in vitro drug release kinetics. The stent prototypes were expanded with a 5.0 × 20 mm balloon catheter, and exhibited a recoil of 3.6% upon balloon deflation. Stent collapse pressure of 0.4 bar (300 mm Hg) was measured under external pressure load. Sustained scaffolding properties were observed in vitro over 14 weeks of radial fatigue loading (50 ± 25 mm Hg at 1.2 Hz). Trackability was demonstrated in bench tests with an 8 French contralateral introducer sheath. SIR release kinetics were adjusted over a broad range by varying the PLLA/P4HB ratio of the coating matrix. The newly developed absorbable SIR-eluting PLLA/P4HB stent successfully fulfilled the requirements for peripheral vascular intervention under in vitro conditions.

Preparation of new series of poly(amide-imide) reinforced layer silicate nano composite containing N-trimellitimide-L-alanine

International Nuclear Information System (INIS)

Faghihi, K.; Soleimani, M.; Shabanian, M.

2011-01-01

A new poly(amide-imide)-montmorillonite series were generated through solution intercalation technique. Cloisite 20A was used as a modified montmorillonite for ample compatibility with the poly(amide-imide) (PAI) matrix. The PAI 5 chains were synthesized by the direct polycondensation reaction of N-trimellitylimido-L-alanine (3) with 4,4'-diamino diphenyl ether (4) in the presence of tryphenyl phosphites (TPP), CaCl 2 , pyridine and N-methyl-2-pyrrolidone (NMP). Morphology and structure of the resulting PAI-nano composite films 5a-5d with (5-20 Wt%) silicate particles were characterized by Ftir spectroscopy, X-ray diffraction and scanning electron microscopy. The effect of clay dispersion and the interaction between clay and polymeric chains on the properties of nano composites films were investigated by using UV-Vis spectroscopy, thermogravimetric analysis and water uptake measurements. (Author)

Preparation of new series of poly(amide-imide) reinforced layer silicate nano composite containing N-trimellitimide-L-alanine

Energy Technology Data Exchange (ETDEWEB)

Faghihi, K.; Soleimani, M. [Polymer Research Laboratory, Department of Chemistry, Faculty of Science, Islamic Azad University, Arak Branch, Arak (Iran, Islamic Republic of); Shabanian, M., E-mail: k-faghihi@araku.ac.ir [Young Researches Club, Islamic Azad University, Arak Branch, Arak (Iran, Islamic Republic of)

2011-07-01

A new poly(amide-imide)-montmorillonite series were generated through solution intercalation technique. Cloisite 20A was used as a modified montmorillonite for ample compatibility with the poly(amide-imide) (PAI) matrix. The PAI 5 chains were synthesized by the direct polycondensation reaction of N-trimellitylimido-L-alanine (3) with 4,4'-diamino diphenyl ether (4) in the presence of tryphenyl phosphites (TPP), CaCl{sub 2}, pyridine and N-methyl-2-pyrrolidone (NMP). Morphology and structure of the resulting PAI-nano composite films 5a-5d with (5-20 Wt%) silicate particles were characterized by Ftir spectroscopy, X-ray diffraction and scanning electron microscopy. The effect of clay dispersion and the interaction between clay and polymeric chains on the properties of nano composites films were investigated by using UV-Vis spectroscopy, thermogravimetric analysis and water uptake measurements. (Author)

Preparation and characterization of new poly(amide–imide reinforced layer silicate nanocomposite containing N,N′-pyrromellitoyl-bis-l-phenyl acetic acid

Directory of Open Access Journals (Sweden)

Khalil Faghihi

2014-12-01

Full Text Available Two new samples of poly(amide–imide/montmorillonite reinforced nanocomposites containing N,N′-pyrromellitoyl-bis-l-phenyl acetic acid moiety in the main chain were synthesized by a convenient solution intercalation technique. Poly(amide–imide (PAI 3 as a source of polymer matrix was synthesized by the direct polycondensation reaction of N,N′-pyrromelitoyl-bis-l-phenyl acetic acid 1 with 4,4′-diamino diphenyl ether 2 in the presence of triphenyl phosphite (TPP, CaCl2, pyridine and N-methyl-2-pyrrolidone (NMP. Morphology and structure of the resulting PAI-nanocomposite films 4a and 4b with 10% and 20% silicate particles were characterized by FTIR spectroscopy, X-ray diffraction (XRD and scanning electron microscopy (SEM. The effect of clay dispersion and the interaction between clay and polymeric chains on the properties of nanocomposite films were investigated by using UV–vis spectroscopy, thermogravimetric analysis (TGA and water uptake measurements.

A rapid approach to prepare poly(2-methyl-2-oxazoline)-based antifouling coating by UV irradiation

Science.gov (United States)

Zhu, Haikun; Mumtaz, Fatima; Zhang, Chong; Tan, Lin; Liu, Songtao; Zhang, Yalin; Pan, Chao; Wang, Yanmei

2017-12-01

A series of brush copolymers, poly[(2-methyl-2-oxazoline)-random-4-vinylpyridine] (PMOXA-r-4VP), with a variety of compositions was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization of the poly(2-methyl-2-oxazoline) methacrylate macromonomer (PMOXA-MA) and 4-vinylpyridine (4VP), and then characterized by 1H NMR spectroscopy and gel permeation chromatography (GPC). The PMOXA-based coatings on the surfaces of glass, silicon, gold and polydimethylsiloxane (PDMS) substrates were then produced by short-time ultraviolet (UV) irradiation of PMOXA-r-4VP. Water contact angel (WCA), ellipsometry, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and ζ-potential techniques were used to characterize the coatings. The results showed that copolymers can be successfully bonded on the surfaces of glass, silicon, gold, and PDMS substrate. Besides, the PMOXA-based coatings displayed a superior resistance to bovine serum albumin, human blood platelets, Human Umbilical Vein Endothelial Cells adsorption and good biocompatibility. Finally, stability test indicated that the stability of coatings can be improved with the content of the 4VP segment. Furthermore, PMOXA-r1/2-4VP immobilized surfaces displayed good antifouling property in long-term applications.

Poly(Poly(Ethylene Glycol Methyl Ether Methacrylate Grafted Chitosan for Dye Removal from Water

Directory of Open Access Journals (Sweden)

Bryan Tsai

2017-03-01

Full Text Available As the demand for textile products and synthetic dyes increases with the growing global population, textile dye wastewater is becoming one of the most significant water pollution contributors. Azo dyes represent 70% of dyes used worldwide, and are hence a significant contributor to textile waste. In this work, the removal of a reactive azo dye (Reactive Orange 16 from water by adsorption with chitosan grafted poly(poly(ethylene glycol methyl ether methacrylate (CTS-GMA-g-PPEGMA was investigated. The chitosan (CTS was first functionalized with glycidyl methacrylate and then grafted with poly(poly(ethylene glycol methyl ether methacrylate using a nitroxide-mediated polymerization grafting to approach. Equilibrium adsorption experiments were carried out at different initial dye concentrations and were successfully fitted to the Langmuir and Freundlich adsorption isotherm models. Adsorption isotherms showed maximum adsorption capacities of CTS-g-GMA-PPEGMA and chitosan of 200 mg/g and 150 mg/g, respectively, while the Langmuir equations estimated 232 mg/g and 194 mg/g, respectively. The fundamental assumptions underlying the Langmuir model may not be applicable for azo dye adsorption, which could explain the difference. The Freundlich isotherm parameters, n and K, were determined to be 2.18 and 17.7 for CTS-g-GMA-PPEGMA and 0.14 and 2.11 for chitosan, respectively. An “n” value between one and ten generally indicates favorable adsorption. The adsorption capacities of a chitosan-PPEGMA 50/50 physical mixture and pure PPEGMA were also investigated, and both exhibited significantly lower adsorption capacities than pure chitosan. In this work, CTS-g-GMA-PPEGMA proved to be more effective than its parent chitosan, with a 33% increase in adsorption capacity.

Methylated DNMT1 and E2F1 are targeted for proteolysis by L3MBTL3 and CRL4DCAF5 ubiquitin ligase.

Science.gov (United States)

Leng, Feng; Yu, Jiekai; Zhang, Chunxiao; Alejo, Salvador; Hoang, Nam; Sun, Hong; Lu, Fei; Zhang, Hui

2018-04-24

Many non-histone proteins are lysine methylated and a novel function of this modification is to trigger the proteolysis of methylated proteins. Here, we report that the methylated lysine 142 of DNMT1, a major DNA methyltransferase that preserves epigenetic inheritance of DNA methylation patterns during DNA replication, is demethylated by LSD1. A novel methyl-binding protein, L3MBTL3, binds the K142-methylated DNMT1 and recruits a novel CRL4 DCAF5 ubiquitin ligase to degrade DNMT1. Both LSD1 and PHF20L1 act primarily in S phase to prevent DNMT1 degradation by L3MBTL3-CRL4 DCAF5 . Mouse L3MBTL3/MBT-1 deletion causes accumulation of DNMT1 protein, increased genomic DNA methylation, and late embryonic lethality. DNMT1 contains a consensus methylation motif shared by many non-histone proteins including E2F1, a key transcription factor for S phase. We show that the methylation-dependent E2F1 degradation is also controlled by L3MBTL3-CRL4 DCAF5 . Our studies elucidate for the first time a novel mechanism by which the stability of many methylated non-histone proteins are regulated.

Fatty acid methyl ester (FAME) technology for monitoring biological foaming in activated sludge: full scale plant verification.

Science.gov (United States)

Lee, J W; Cha, D K; Kim, I; Son, A; Ahn, K H

2008-02-01

Fatty acid methyl ester (FAME) technology was evaluated as a monitoring tool for quantification of Gordonia amarae in activated sludge systems. The fatty acid, 19:1 alcohol, which was identified as a unique fatty acid in G. amarae was not only confirmed to be present in foaming plant samples, but the quantity of the signature peak correlated closely with the degree of foaming. Foaming potential experiment provided a range of critical foaming levels that corresponded to G. amarae population. This range of critical Gordonia levels was correlated to the threshold signature FAME amount. Six full-scale wastewater treatment plants were selected based on a survey to participate in our full-scale study to evaluate the potential application of the FAME technique as the Gordonia monitoring tool. Greater amounts of signature FAME were extracted from the mixed liquor samples obtained from treatment plants experiencing Gordonia foaming problems. The amounts of signature FAME correlated well with the conventional filamentous counting technique. These results demonstrated that the relative abundance of the signature FAMEs can be used to quantitatively monitor the abundance of foam-causing microorganism in activated sludge.

Thermodynamics of poly(7-methoxy-2-acetylbenzofurane methyl methacrylate-co-styrene) and poly(2-acetylbenzofurane methyl methacrylate-co-styrene)-probe interactions at different temperatures by inverse gas chromatography

International Nuclear Information System (INIS)

İlter, Zülfiye; Demir, Abdullah; Kaya, İsmet

2016-01-01

Highlights: • Thermodynamic of methacrylate-co-styrene polymers were studied by the inverse gas chromatography. • The sorption parameters of polymer-solute systems were determined under glass transition temperature of polymers. • The solubility parameter (δ 2 ) of the polymer was obtained from the slope and intercepts. • Flory-Huggins interaction parameter (χ 12 ∞ ) were determined for polymer-solute systems. - Abstract: In this study, some thermodynamic properties of poly(7-methoxy-2-acetylbenzofurane methyl methacrylate-co-styrene) Poly(MABMM-co-St) and poly(2-acetylbenzofurane methyl methacrylate-co-styrene) Poly(ABMM-co-St) were studied by the inverse gas chromatography (IGC) technique. The retention times (t r ) of selected organic probes were determined from the interactions with Poly(MABMM-co-St) and Poly(ABMM-co-St) of four groups of solvents with different chemical natures and polarities. Then, specific volume (V g 0 ) values of probes were calculated at different column temperatures. The glass transition temperatures (T g ) of Poly(MABMM-co-St) and Poly(ABMM-co-St) were found as 393, 413 K from inverse gas chromatography measurements, respectively. Under the glass transition temperatures adsorption heat (ΔH a ) and above the glass transition molar heat (ΔH 1 S ), free energies (ΔG 1 S ) and entropies (ΔS 1 S ) belonging to sorption for every probe were calculated from inverse gas chromatography measurements. The partial molar heat (ΔH 1 ∞ ), partial molar free energy (ΔG 1 ∞ ), Flory-Huggins interaction parameter (χ 12 ∞ ) and weight fraction activity coefficient (a 1 /w 1 ) ∞ , values for infinite dilute solutions were calculated for polymer-probe systems. The solubility parameter (δ 2 ) of the polymer was obtained from the slope and intercepts of Flory-Huggins interaction parameter (χ 12 ∞ ) graphs with solubility parameters (δ 1 ) of probes.

Adsorption of Poly(ethylene oxide)-Poly(lactide) Copolymers. Effects of Composition and Degradation.

Science.gov (United States)

Muller, Dries; Carlsson, Fredrik; Malmsten, Martin

2001-04-01

The effect of chemical degradation of two diblock copolymers of poly(ethylene oxide) (E) and poly(lactide) (L), E(39)L(5) and E(39)L(20), on their adsorption at silica and methylated silica was investigated with in situ ellipsometry. Steric stablization of polystyrene dispersions was investigated in relation to degradation. Hydrolysis of the poly(lactide) block of the copolymers was followed at different temperatures and pH by using HPLC to measure the occurrence of lactic acid in solution. The block copolymers were quite stable in pH-unadjusted solution at low temperature, whereas degradation was facilitated by increasing temperature or lowering of the pH. Lower degradation rates of E(39)L(20) where observed at low temperature in comparison with those of E(39)L(5), whereas the degradation rates of the copolymers were quantitatively similar at high temperature. The adsorption of the copolymers at methylated silica substrates decreased with increasing degree of degradation due to the reduction in the ability of hydrophobic block to anchor the copolymer layer at the surface. At silica the adsorption initially increased with increasing degradation, particularly for E(39)L(20) due to deposition of aggregates onto the surface. After extensive degradation the adsorption of the copolymers at both silica and methylated silica resembled that of the corresponding poly(ethylene oxide) homopolymer. Overall, it was found that the eventual reduction in adsorption occurred at a lower degree of degradation for E(39)L(5) than for E(39)L(20). Mean-field calculations showed a reduced anchoring for the block copolymers with decreasing poly(lactide) block length at hydrophobic surfaces. In accordance with this finding, it was observed that polystyrene dispersions were stabilized by E(39)L(20) or E(39)L(5) in a way that depended on both the lactide block length and the degree of degradation. Upon degradation of the hydrophobic block, stabilization of the polystyrene dispersions was

Large, Linear, and Tunable Positive Magnetoresistance of Mechanically Stable Graphene Foam-Toward High-Performance Magnetic Field Sensors.

Science.gov (United States)

Sagar, Rizwan Ur Rehman; Galluzzi, Massimiliano; Wan, Caihua; Shehzad, Khurram; Navale, Sachin T; Anwar, Tauseef; Mane, Rajaram S; Piao, Hong-Guang; Ali, Abid; Stadler, Florian J

2017-01-18

Here, we present the first observation of magneto-transport properties of graphene foam (GF) composed of a few layers in a wide temperature range of 2-300 K. Large room-temperature linear positive magnetoresistance (PMR ≈ 171% at B ≈ 9 T) has been detected. The largest PMR (∼213%) has been achieved at 2 K under a magnetic field of 9 T, which can be tuned by the addition of poly(methyl methacrylate) to the porous structure of the foam. This remarkable magnetoresistance may be the result of quadratic magnetoresistance. The excellent magneto-transport properties of GF open a way toward three-dimensional graphene-based magnetoelectronic devices.

Mössbauer studies of iron doped poly(methyl methacrylate) before ...

Indian Academy of Sciences (India)

Unknown

Mössbauer studies of iron doped poly(methyl methacrylate) before and after ion beam modification. D R S SOMAYAJULU, C N MURTHY†, D K AWASTHI‡, N V PATEL and M SARKAR. Physics Department, Faculty of Science, MS University of Baroda, Vadodara 390 002, India. †Applied Chemistry Department, Faculty ...

Preparation and characterization of poly (methyl methacrylate) and sulfonated poly (ether ether ketone) blend ultrafiltration membranes for protein separation applications

International Nuclear Information System (INIS)

Arthanareeswaran, G.; Thanikaivelan, P.; Raajenthiren, M.

2009-01-01

Poly (methyl methacrylate) (PMMA) and poly (methyl methacrylate)/sulfonated poly (ether ether ketone) (SPEEK) blend membranes were prepared by phase inversion technique in various composition using N,N'-dimethylformamide as solvent. The prepared membranes were characterized in terms of pure water flux, water content, porosity and thermal stability. The addition of SPEEK to the casting solution resulted in membranes with high pure water flux, water content, porosity and slightly low thermal stability. The cross sectional views of the blend membranes under electron microscope confirm the porosity and water flux results. The effect of the addition of SPEEK into the PMMA matrix on the extent of bovine serum albumin (BSA) separation was studied. It was found that the permeate flux increased significantly while the rejection of BSA from aqueous solution reduced moderately during ultrafiltration (UF) process. The effect was attributed to the increase in porosity and charge of the membrane due to the addition of SPEEK into the PMMA blend solution

Facile synthesis of polypyrrole functionalized nickel foam with catalytic activity comparable to Pt for the poly-generation of hydrogen and electricity

Science.gov (United States)

Tang, Tiantian; Li, Kan; Shen, Zhemin; Sun, Tonghua; Wang, Yalin; Jia, Jinping

2016-01-01

Polypyrrole functionalized nickel foam is facilely prepared through the potentiostatic electrodeposition. The PPy-functionalized Ni foam functions as a hydrogen-evolution cathode in a rotating disk photocatalytic fuel cell, in which hydrogen energy and electric power are generated by consuming organic wastes. The PPy-functionalized Ni foam cathode exhibits stable catalytic activities after thirteen continuous runs. Compared with net or plate structure, the Ni foam with a unique three-dimensional reticulate structure is conducive to the electrodeposition of PPy. Compared with Pt-group electrode, PPy-coated Ni foam shows a satisfactory catalytic performance for the H2 evolution. The combination of PPy and Ni forms a synergistic effect for the rapid trapping and removal of proton from solution and the catalytic reduction of proton to hydrogen. The PPy-functionalized Ni foam could be applied in photocatalytic and photoelectrochemical generation of H2. In all, we report a low cost, high efficient and earth abundant PPy-functionalized Ni foam with a satisfactory catalytic activities comparable to Pt for the practical application of poly-generation of hydrogen and electricity.

A highly selective sorbent for removal of Cr(VI) from aqueous solutions based on Fe3O4/poly(methyl methacrylate) grafted Tragacanth gum nanocomposite: Optimization by experimental design

International Nuclear Information System (INIS)

Sadeghi, Susan; Rad, Fatemeh Alavi; Moghaddam, Ali Zeraatkar

2014-01-01

In this work, poly(methyl methacrylate) grafted Tragacanth gum modified Fe 3 O 4 magnetic nanoparticles (P(MMA)-g-TG-MNs) were developed for the selective removal of Cr(VI) species from aqueous solutions in the presence of Cr(III). The sorbent was characterized by Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), a vibrating sample magnetometer (VSM), and thermo-gravimetric analysis (TGA). A screening study on operational variables was performed using a two-level full factorial design. Based on the analysis of variance (ANOVA) with 95% confidence limit, the significant variables were found. The central composite design (CCD) has also been employed for statistical modeling and analysis of the effects and interactions of significant variables dealing with the Cr(VI) uptake process by the developed sorbent. The predicted optimal conditions were situated at a pH of 5.5, contact time of 3.4 h, and 3.0 g L −1 dose. The Langmuir, Freundlich, and Temkin isotherm models were used to describe the equilibrium sorption of Cr(VI) by the absorbent, and the Langmuir isotherm showed the best concordance as an equilibrium model. The adsorption process was followed by a pseudo-second-order kinetic model. Thermodynamic investigations showed that the biosorption process was spontaneous and exothermic. - Highlights: • Fe3O4 nanoparticles were modified with Poly(methyl methacrylate) grafted Tragacanth gum • P(MMA)-g-TG -MNPs can preferentially adsorb Cr(VI) in the presence of Cr(III) • The effects of operational parameters on Cr(VI) removal were evaluated by RSM • Adsorption mechanism, kinetics, and isotherm have been explored • The sorbent was successfully used to remove Cr(VI) from different water samples

Characterization of polar organosulfates in secondary organic aerosol from the unsaturated aldehydes 2-E-pentenal, 2-E-hexenal, and 3-Z-hexenal

Directory of Open Access Journals (Sweden)

M. S. Shalamzari

2016-06-01

group at the C-4 position. Evidence is also presented that the MW 214 positional isomer, 2-sulfooxy-3-hydroxypentanoic acid, is unstable and decarboxylates, giving rise to 1-sulfooxy-2-hydroxybutane, a MW 170 organosulfate. Furthermore, evidence is obtained that lactic acid sulfate is generated from 2-E-pentenal. This chemistry could be important on a regional and local scale where GLV emissions such as from grasses and cereal crops are substantial.

Air Activated Self-Decontaminating Polydicyclopentadiene PolyHIPE Foams for Rapid Decontamination of Chemical Warfare Agents.

Science.gov (United States)

McGann, Christopher L; Daniels, Grant C; Giles, Spencer L; Balow, Robert B; Miranda-Zayas, Jorge L; Lundin, Jeffrey G; Wynne, James H

2018-06-01

The threat of chemical warfare agents (CWA) compels research into novel self-decontaminating materials (SDM) for the continued safety of first-responders, civilians, and active service personnel. The capacity to actively detoxify, as opposed to merely sequester, offending agents under typical environmental conditions defines the added value of SDMs in comparison to traditional adsorptive materials. Porous polymers, synthesized via the high internal phase emulsion (HIPE) templating, provide a facile fabrication method for materials with permeable open cellular structures that may serve in air filtration applications. PolyHIPEs comprising polydicyclopentadiene (polyDCPD) networks form stable hydroperoxide species following activation in air under ambient conditions. The hydroperoxide-containing polyDCPD materials react quickly with CWA simulants, Demeton-S and 2-chloroethyl ethyl sulfide, forming oxidation products as confirmed via gas chromatography mass spectrometry. The simplicity of the detoxification chemistry paired with the porous foam form factor presents an exciting opportunity for the development of self-decontaminating filter media. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pharmacokinetic Comparison of Once-Daily Topical Minocycline Foam 4% vs Oral Minocycline for Moderate-to-Severe Acne.

Science.gov (United States)

Jones, Terry M; Ellman, Herman; deVries, Tina

2017-10-01

To characterize minocycline pharmacokinetics and relative bioavailability following multiple-dose topical administration of minocycline hydrochloride (HCl) foam 4% (FMX101 4%) as compared with single-dose oral administration of minocycline HCl extended-release tablets (Solodyn®) in subjects with moderate-to-severe acne. A Phase 1, single-center, nonrandomized, open-label, active-controlled, 2-period, 2-treatment crossover clinical study. The study included 30 healthy adults (mean age, 22.6 years; 90% white, and 60% females) who had moderate-to-severe acne. Subjects were assigned to first receive a single oral dose of a minocycline HCl extended-release tablet (approximately 1 mg/kg). At 10 days after the oral minocycline dose, topical minocycline foam 4% was applied, once daily for 21 days. Serial blood samples were obtained before and after administration of oral minocycline and each topical application of minocycline foam 4% on days 1, 12, and 21. Following oral administration of minocycline (approximately 1 mg/kg), plasma minocycline concentration increased until 3 hours, followed by a log-linear decrease over the remainder of the 96-hour sampling period. Following topical application of a 4-g maximal-use dose of minocycline foam 4% for 21 days, plasma minocycline concentration was very low, with geometric mean Cmax values ranging from 1.1 ng/mL to 1.5 ng/mL. Steady state was achieved by day 6. Overall, minocycline exposure with topical minocycline foam 4% was 730 to 765 times lower than that with oral minocycline. There was no evidence of minocycline accumulation over the 21 days of topical application of minocycline foam 4%. Topical minocycline foam 4% appeared to be safe and well tolerated, with no serious treatment-emergent adverse events (TEAEs), treatment-related TEAEs, or TEAEs that led to treatment discontinuation. Once-daily topical application of minocycline foam 4% did not lead to significant systemic exposure to minocycline. It appears to be a well

Effect of lithium salt concentrations on blended 49% poly(methyl methacrylate) grafted natural rubber and poly(methyl methacrylate) based solid polymer electrolyte

International Nuclear Information System (INIS)

Su’ait, M.S.; Ahmad, A.; Hamzah, H.; Rahman, M.Y.A.

2011-01-01

The effect of lithium salts (lithium tetrafluoroborate, LiBF 4 and lithium perchlorate, LiClO 4 ) as doping salts in rubber-polymer blends, 49% poly(methyl methacrylate) grafted natural rubber (MG49) and poly(methyl methacrylate) (PMMA) in solid polymer electrolyte (SPE) film for electrochemical devices application was investigated. The electrolyte films were prepared via the solution casting technique using 0–25 wt.% lithium salt. The effect of the lithium salts on chemical interaction, ionic conductivity and structural and morphological studies of (70:30) MG49-PMMA films was analyzed using Fourier Transform Infrared (FT-IR) Spectroscopy, Electrochemical Impedance Spectroscopy (EIS), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Infrared analysis showed that the interactions between lithium ions and oxygen atoms occur at the ether group (C–O–C) (1500–1100 cm −1 ) on the MMA structure in both MG49 and PMMA. The oxygen atoms in the structure of the polymer host act as electron donor atoms and form a coordinate bond with the lithium ions from the doping salt to form polymer–salt complexes. The ionic conductivity was investigated at room temperature as well as at a temperature range from 303 K to 373 K. The ionic conductivity without the addition of salt was 1.1 × 10 −12 S cm −1 . The highest conductivity at room temperature for (70:30) MG49-PMMA–LiBF 4 was 8.6 × 10 −6 S cm −1 at 25 wt.% of LiBF 4 . The ionic conductivity of (70:30) MG49-PMMA–LiClO 4 was 1.5 × 10 −8 S cm −1 at 25 wt.% of LiClO 4 . However, both electrolyte systems do not exhibit Arrhenius-like behavior. Systems with LiBF 4 salt have higher ionic conductivity than those with LiClO 4 salt because of the differences in anionic size and lattice energy of the appropriate salt. The observations from structural and morphology studies showed that complexation and re-crystallization occur in the system. The XRD studies showed a reduction of the MMA peak

Copolymerization of poly (ethylene oxide) and poly (methyl methacrylate) initiated by ceric ammonium nitrate

International Nuclear Information System (INIS)

Gomes, A.S.; Ferreira, A.A.; Coutinho, F.M.B.; Marinho, J.R.D.

1984-01-01

Cerium (IV) salts such as the ceric ammonium nitrate and ceric ammonium sulfate in aqueous acid solution with reducing agents such as alcohols, thiols, glycols, aldehydes and amines are well known initiators of vinyl polymerization. In this work, the polymerization of methyl methacrylate initiated by ceric ammonium nitrate/HNO 3 -poly(ethylene oxide) with hydroxyl end group system was studied in aqueous solution at 25 0 C to obtain block copolymers. (Author) [pt

Fabrication of poly(methyl methacrylate)-block-poly(methacrylic acid) diblock copolymer as a self-embrittling strippable coating for radioactive decontamination

International Nuclear Information System (INIS)

Liu Renlong; Zhang Huiyan; Li Yintao; Zhou Yuanlin; Zhang Quanping; Zheng Jian; Wang Shanqiang

2016-01-01

The poly(methyl methacrylate)-block-poly(methacrylic acid) diblock copolymer with different monomer compositions was synthesized via reversible addition-fragmentation chain transfer polymerization. Meanwhile, a novel self-embrittling strippable coating was prepared using the diblock copolymers, which is proposed to be used as radioactive decontamination agents without manual operation. Furthermore, the decontamination efficiencies of self-embrittling strippable coatings for radioactive contamination on glass, marble, and stainless steel surfaces were studied. (author)

Refractive microlenses produced by excimer laser machining of poly(methyl methacrylate)

DEFF Research Database (Denmark)

Jensen, Martin Frøhling; Krühne, Ulrich; H., L.

2005-01-01

A method has been developed whereby refractive microlenses can be produced in poly (methyl methacrylate) by excimer laser irradiation at λ = 248 nm. The lenses are formed by a combined photochemical and thermal process. The lenses are formed as depressions in the substrate material (negative foca...

The involvement of poly(ADP-ribose) polymerase in the degradation of NAD caused by γ-radiation and N-methyl-N-nitrosourea

International Nuclear Information System (INIS)

Skidmore, C.J.; Davies, M.I.; Goodwin, P.M.; Halldorsson, H.; Lewis, P.J.; Shall, S.; Zia'ee, A.

1979-01-01

Both N-methyl-N-nitrosourea and γ-radiation lower cellular NAD in mouse leukaemia cells (L1210) in a dose-dependent way. The minimum NAD level is reached 2 h after a brief exposure to N-methyl-N-nitrosourea, but within 15 min of γ-irradiation. The cells remain metabolically active; they are able to recover their control NAD levels and are impermeable to trypan blue. Several inhibitors of poly(ADP-ribose) polymerase inhibit the drop in cellular NAD caused by these two agents: 2 mM 5-methylnicotinamide, 1 mM theophylline or 1 mM theobromine inhibit the effect of N-methyl-N-nitrosourea on cellular NAD level; 200 μM thymidine, 500 μM 5-methylnicotinaminde, 500 μM thephylline and 500 μM theobromine prevent the lowering of cellular NAD by γ-irradiation. The extent to which the drop in cellular NAD is inhibited is dependent on both the concentration of cytotoxic agent and of polymerase inhibitor. Caffeine will inhibit the drop in NAD but only at 10 mM, while nicotonic acid is ineffictive even at this dose. The activity of poly(ADP-ribose) polymerase is permeabilized cells immediately after γ-radiation increases with dose up to 12 krad, giving a maximal 3.4-fold stimulation of the enzyme activity, whereas the degradation of NAD under conditions optimal for NAD glycohydrolase does not change. The activity of the polymerase shows a close temporal correlation with the NAD drop following both γ-radiation and N-methyl-N-nitrosourea. The enzyme activity is maximal when the NAD content. (orig./AJ) 891 AJ/orig.- 892 HIS [de

Thermodynamic and Kinetic Behavior of the Polystyrene/Poly(vinyl methyl ether) Blend as Studied by Excimer Fluorescence.

Science.gov (United States)

1986-01-02

AD-A±63 895 THERMODYNAMIC AND KINETIC BEHAVIOR OF THE / POLYSTYRENE/POLY(YINYL METHYL E..(U) STANFORD UNIY CALIFDEPT OF CHEMICAL ENGINEERING C N...Polystyrene/Poly(vinyl methyl ether) Blend 7. DEcFRMN 81 toOR 30USptE8 00~ as Studied by Excimer Fluorescence 6 EFRIGOG EOTNME *AUTHOR() a. CONTRACT OR GRANT...werea fondoare ihemoriisof * ~ Ex e sp fluodecositionsdu to deud Gen e and hoog Pinus Florsneis shownhase migrationprocSECURITY CLASIFICTIO OFd

In situ forming poly(ethylene glycol)- Poly(L -lactide) hydrogels via michael addition: Mechanical properties, degradation, and protein release

NARCIS (Netherlands)

Buwalda, S.J.; Dijkstra, Pieter J.; Feijen, Jan

2012-01-01

Chemically crosslinked hydrogels are prepared at remarkably low macromonomer concentrations from 8-arm poly(ethylene glycol)-poly(L-lactide) star block copolymers bearing acrylate end groups (PEG-(PLLAn)8-AC, n = 4 or 12) and multifunctional PEG thiols (PEG-(SH)n, n = 2, 4, or 8) through a

DC conduction mechanism and dielectric properties of Poly (methyl methacrylate)/Poly (vinyl acetate) blends doped and undoped with malachite green

International Nuclear Information System (INIS)

Abd-El Kader, F.H.; Osman, W.H.; Hafez, R.S.

2013-01-01

Cast thin films of Poly (methyl methacrylate)/Poly (vinyl acetate) blends of different concentrations undoped and doped with malachite green have been prepared and subjected to both dc electrical conduction and dielectric spectroscopy measurements. The analysis of dc electrical conduction data showed that the space charge limited current mechanism has been dominant for Poly (vinyl acetate) while Schottky-Richardson conduction mechanism prevailed for the Poly (methyl methacrylate) and blended samples. The values of field lowering constant β and the thermal activation energy ΔE involved in the dc conduction were reported, which provide another support for the suggested Schottky-Richardson mechanism. The increase in current for the blend sample doped with malachite green has been attributed to the formation of charge transfer complexes inside the polyblend matrix. The dielectric constant as a function of temperature for all samples have been calculated which are affected by the composition ratio and the addition of dye. The relaxation peak that appeared in the dielectric loss curve at 347 K for the doped blend sample is related to local dipoles that are present in the dye material. The obtained relaxation process spectra present in the investigated samples were analyzed with the well-known model of Havriliak-Negami.

Synthesis, characterization and photo behavior of new poly(amide-imide/montmorillonite nanocomposite containing N,N'-pyrromellitoyl-bis-L-alanine

Directory of Open Access Journals (Sweden)

M. Hajibeygi

2013-09-01

Full Text Available Two new samples of poly(amide-imide-nanocomposites were synthesized by insertion nano silicate particles in poly(amide-imide (PAI chains using a convenient solution intercalation technique. PAI as a source of polymer matrix was synthesized by the direct polycondensation reaction of N,N'-pyrromelitoyl-bis-L-alanine with 4,4'-diamino diphenyl ether in the presence of triphenyl phosphite (TPP, CaCl2, pyridine and N-methyl-2-pyrrolidone (NMP. Morphology and structure of the resulting PAI-nanocomposite films with 5 and 10% silicate particles were characterized by FTIR spectroscopy, X-ray diffraction (XRD and scanning electron microscopy (SEM. The effect of clay dispersion and the interaction between clay and polymeric chains on the properties of nanocomposites films were investigated by using UV-Vis spectroscopy, thermogravimetric analysis (TGA and water uptake measurements.DOI: http://dx.doi.org/10.4314/bcse.v27i3.15

Differential pulse voltammetric determination of methyl parathion based on multiwalled carbon nanotubes–poly(acrylamide) nanocomposite film modified electrode

International Nuclear Information System (INIS)

Zeng, Yanbo; Yu, Dajun; Yu, Yanyan; Zhou, Tianshu; Shi, Guoyue

2012-01-01

Highlights: ► A sensitive electrochemical sensor for detecting methyl parathion in environmental samples. ► The preparation, characterization and application of this novel MWCNTs–PAAM nanocomposite. ► The MWCNTs–PAAM/GCE exhibited a high adsorption and strong affinity toward methyl parathion. ► Wide linear range and low detection limit of the proposed method for detecting methyl parathion. - Abstract: A sensitive electrochemical differential pulse voltammetry method was developed for detecting methyl parathion based on multiwalled carbon nanotubes–poly(acrylamide) (MWCNTs–PAAM) nanocomposite film modified glassy carbon electrode. The novel MWCNTs–PAAM nanocomposite, containing high content of amide groups, was synthesized by PAAM polymerizing at the vinyl group functionalized MWCNTs surface using free radical polymerization. The MWCNTs–PAAM nanocomposite was characterized by Fourier transform infrared spectroscopy, thermal gravimetric analysis and scanning electron microscopy. Electrochemical behavior and interference studies of MWCNTs–PAAM/GCE for methyl parathion were investigated. The experimental results demonstrated that the MWCNTs–PAAM/GCE exhibited a high adsorption and strong affinity toward methyl parathion compared with some metal ions and nitroaromatic compounds, which exist in environmental samples. The adsorbed amount of methyl parathion on the MWCNTs–PAAM/GCE approached the equilibrium value upon 5 min adsorption time. A linear calibration curve for methyl parathion was obtained in the concentration range from 5.0 × 10 −9 to 1.0 × 10 −5 mol L −1 , with a detection limit of 2.0 × 10 −9 mol L −1 . The MWCNTs–PAAM/GCE was proved to be a suitable sensing tool for the fast, sensitive and selective determination of methyl parathion in environmental water samples.

Rheological, mechanical and morphological properties of poly(methyl methacrylate/poly(ethylene terephthalate blend with dual reactive interfacial compatibilization

Directory of Open Access Journals (Sweden)

Juciklécia da Silva Reinaldo

2015-10-01

Full Text Available Abstract In this work, the rheological, mechanical and morphological behavior of immiscible blend poly (methyl methacrylate with elastomeric particles (PMMAelast and post-consumer poly (ethylene terephthalate (PET with and without the use of the interfacial compatibilizer poly (methyl methacrylate-co-glycidyl methacrylate-co-ethyl acrylate (MGE was studied. The significant increase in torque presented in rheological analyses has shown a indication of chemical reactions between the epoxy group of MGE with end groups of PET chains and also with the elastomeric phase of PMMAelast. The increased concentration of PET yielded an increase in maximum strength and elasticity modulus and a decrease in elongation at break. The PMMAelast/PET binary blend (50/50 wt% and PMMAelast/PET/MGE compatibilized blend (65/30/5 wt% showed pronounced results in elongation at break compared to PMMAelast, whereas, in the first results were due to the evidence of a co-continuous morphological structure and in the second, due to the efficiency of the dual reactive interfacial compatibilization of PMMAelast/PET blends. Scanning electron microscopy (SEM and transmission electron microscopy (TEM analyses showed that PMMAelast/PET/MGE blends exhibit complex phase morphology due to the presence of elastomeric particles in the PMMAelast copolymer and in the use of MGE terpolymer.

An intelligent biopolymer gel with pendant L-proline methyl ester

International Nuclear Information System (INIS)

Yoshida, Masaru; Safranj, A.; Omichi, Hideki; Katakai, Ryoichi.

1995-01-01

Linear poly(acryloyl-L-proline methyl ester, A-ProOMe), obtained by radiation-induced polymerization of its monomer in ethanol, exhibits a lower critical solution temperature (LCST) at 14degC. A-ProOMe was copolymerized with a minor amount of 2-hydroxypropyl methacrylate (HPMA) or 2-hydroxyethyl methacrylate (HEMA), to obtain intelligent biopolymer gels for application in drug delivery systems. The poly(A-ProOMe/HPMA) gel was characterized by an initial rapid shrinkage at the surface in the swollen state, as resulting in formation of a rigid membrane barrier devoid of micropores. This gel is called a surface regulated matrix. In the case of poly(A-ProOMe/HEMA), no such a barrier formed, instead, the whole matrix shrunk without the disappearance of micropores. This gel is called a matrix pumping gel. Testosterone (T) was incorporated into the poly(A-ProOMe/HPMA) gel, and it was found that the daily dose of T released in vivo from this formulation remained constant at approximately 30 μg/day throughout an experimental period of 54 weeks. On the other hand, 9-β-D-arabinofuranosyladenine (Ara-A) was incorporated into the poly(A-ProOMe/HEMA) gel to evaluate the pulsatile drug release when cycled at 10 and 37degC. The in vitro release rate of Ara-A was found to be 11 ng/h at 10degC and 33 ng/h at 37degC. (author)

Formation of O2-methylthymine in poly(dA-dT) on methylation with N-methyl-N-nitrosourea and dimethyl sulphate. Evidence that O2-methylthymine does not miscode during DNA synthesis.

Science.gov (United States)

Saffhill, R; Abbott, P J

1978-01-01

The alternating co-polymer has been methylated with either N methyl-N-nitrosourea (MNU) or dimethyl sulphate (DMS) and the levels of the various methylated thymidines (O2-methylthymidine, 3-methylthymidine and O4-methylthymidine) measured. MNU produced all three compounds whereas DMS only produced 3-methylthymidine and O2-methylthymidine at detectable levels. These results have been combined with our earlier results concerning the misincorporation of dGMP with E. coli DNA polymerase using MNU-methylated poly(dA-dT). These results indicate that O2-methylthymidine does not miscode during DNA synthesis. PMID:353735

Effect of epoxidation on 30% poly(methyl methacrylate)-grafted natural rubber polymer electrolytes

Energy Technology Data Exchange (ETDEWEB)

Nazir, Khuzaimah; Aziz, Ahmad Fairoz [Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Adam, Nurul Ilham [Faculty of Applied Sciences, Universiti Teknologi MARA, KampusTapah, 35400 Tapah Road, Tapah, Perak (Malaysia); Yahya, Muhd Zu Azhan [Faculty of Defence Sciences and Technology, Universiti Pertahanan Nasional Malaysia, Kem Sungai Besi, 57000 Kuala Lumpur (Malaysia); Ali, Ab Malik Marwan [Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia)

2015-08-28

Epoxidized 30% poly(methyl methacrylate)-grafted natural rubber (EMG 30) as a polymer host in solid polymer electrolytes (SPEs) has been investigated. EMG30 was synthesized via performicepoxidation method onto 30% poly(methyl methacrylate)-grafted natural rubber (MG30) and the formations of epoxy group were discussed. The EMG30 were characterized by proton nuclear magnetic resonance ({sup 1}HNMR) to investigate their chemical structure and differential scanning calorimeter to determine their crystallinity. A new peak in {sup 1}HNMR spectra (2.71 ppm) confirmed the appearance of epoxy group. SPE based on EMG30 doped with 40 wt% LiCF{sub 3}SO{sub 3} show the highest conductivity. The complexation between EMG30 and LiCF{sub 3}SO{sub 3} were confirmed by attenuated total reflection Fourier transform infrared (ATR-FTIR)

Effect of epoxidation on 30% poly(methyl methacrylate)-grafted natural rubber polymer electrolytes

International Nuclear Information System (INIS)

Nazir, Khuzaimah; Aziz, Ahmad Fairoz; Adam, Nurul Ilham; Yahya, Muhd Zu Azhan; Ali, Ab Malik Marwan

2015-01-01

Epoxidized 30% poly(methyl methacrylate)-grafted natural rubber (EMG 30) as a polymer host in solid polymer electrolytes (SPEs) has been investigated. EMG30 was synthesized via performicepoxidation method onto 30% poly(methyl methacrylate)-grafted natural rubber (MG30) and the formations of epoxy group were discussed. The EMG30 were characterized by proton nuclear magnetic resonance ( 1 HNMR) to investigate their chemical structure and differential scanning calorimeter to determine their crystallinity. A new peak in 1 HNMR spectra (2.71 ppm) confirmed the appearance of epoxy group. SPE based on EMG30 doped with 40 wt% LiCF 3 SO 3 show the highest conductivity. The complexation between EMG30 and LiCF 3 SO 3 were confirmed by attenuated total reflection Fourier transform infrared (ATR-FTIR)

Effect of epoxidation on 30% poly(methyl methacrylate)-grafted natural rubber polymer electrolytes

Science.gov (United States)

Nazir, Khuzaimah; Aziz, Ahmad Fairoz; Adam, Nurul Ilham; Yahya, Muhd Zu Azhan; Ali, Ab Malik Marwan

2015-08-01

Epoxidized 30% poly(methyl methacrylate)-grafted natural rubber (EMG 30) as a polymer host in solid polymer electrolytes (SPEs) has been investigated. EMG30 was synthesized via performicepoxidation method onto 30% poly(methyl methacrylate)-grafted natural rubber (MG30) and the formations of epoxy group were discussed. The EMG30 were characterized by proton nuclear magnetic resonance (1HNMR) to investigate their chemical structure and differential scanning calorimeter to determine their crystallinity. A new peak in 1HNMR spectra (2.71 ppm) confirmed the appearance of epoxy group. SPE based on EMG30 doped with 40 wt% LiCF3SO3 show the highest conductivity. The complexation between EMG30 and LiCF3SO3 were confirmed by attenuated total reflection Fourier transform infrared (ATR-FTIR).

A highly selective sorbent for removal of Cr(VI) from aqueous solutions based on Fe{sub 3}O{sub 4}/poly(methyl methacrylate) grafted Tragacanth gum nanocomposite: Optimization by experimental design

Energy Technology Data Exchange (ETDEWEB)

Sadeghi, Susan, E-mail: ssadeghi@birjand.ac.ir; Rad, Fatemeh Alavi; Moghaddam, Ali Zeraatkar

2014-12-01

In this work, poly(methyl methacrylate) grafted Tragacanth gum modified Fe{sub 3}O{sub 4} magnetic nanoparticles (P(MMA)-g-TG-MNs) were developed for the selective removal of Cr(VI) species from aqueous solutions in the presence of Cr(III). The sorbent was characterized by Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), a vibrating sample magnetometer (VSM), and thermo-gravimetric analysis (TGA). A screening study on operational variables was performed using a two-level full factorial design. Based on the analysis of variance (ANOVA) with 95% confidence limit, the significant variables were found. The central composite design (CCD) has also been employed for statistical modeling and analysis of the effects and interactions of significant variables dealing with the Cr(VI) uptake process by the developed sorbent. The predicted optimal conditions were situated at a pH of 5.5, contact time of 3.4 h, and 3.0 g L{sup −1} dose. The Langmuir, Freundlich, and Temkin isotherm models were used to describe the equilibrium sorption of Cr(VI) by the absorbent, and the Langmuir isotherm showed the best concordance as an equilibrium model. The adsorption process was followed by a pseudo-second-order kinetic model. Thermodynamic investigations showed that the biosorption process was spontaneous and exothermic. - Highlights: • Fe3O4 nanoparticles were modified with Poly(methyl methacrylate) grafted Tragacanth gum • P(MMA)-g-TG -MNPs can preferentially adsorb Cr(VI) in the presence of Cr(III) • The effects of operational parameters on Cr(VI) removal were evaluated by RSM • Adsorption mechanism, kinetics, and isotherm have been explored • The sorbent was successfully used to remove Cr(VI) from different water samples.

Glass transition of poly (methyl methacrylate) filled with nanosilica and core-shell structured silica

DEFF Research Database (Denmark)

Song, Yihu; Bu, Jing; Zuo, Min

2017-01-01

transition and segmental dynamics of PMMA in the nanocomposites prepared via solution casting was compared. The remarkable depression (≥10 °C) of glass transition temperature (Tg) induced by the incorporation of SiO2 and CS was both observed at low loadings. Here, different mechanisms were responsible...... for the effect of SiO2 and CS on the segmental acceleration of PMMA matrix. The formation of rigid amorphous fraction (RAF) layer around SiO2 with the thickness of 16.4 nm led to the adjacent molecular packing frustration, while the “lubrication” effect of nonwetting interface between the grafted crosslinked......Core-shell (CS) nanocomposite particles with 53.4 wt% cross-linked poly (methyl methacrylate) (PMMA) shell of 11.6 nm in thickness were fabricated via miniemulsion polymerization of methyl methacrylate in the presence of modified nanosilica. The influence of nanosilica and CS nanoparticles on glass...

Development of superconducting cryo-electron microscope and its applications

International Nuclear Information System (INIS)

Iwatsuki, Masashi

1988-01-01

Recently, a superconducting cryo-electron microscope in which specimens are cooled to the liquid helium temperature (4.2 K) has been developed. The main components and functional features of this new microscope are reported together with application data on polyethylene, poly (4-methyl-1-pentene), valonia cellulose, rock salt, ice crystallites and ceramic superconductor. The resistance to electron radiation damage, of beam-sensitive specimens including polymers has been increased more than ten times. Thus, the microscope has made it possible to take high resolution images and to analyze the crystal-structure of micro-areas. (orig.) [de

Differential pulse voltammetric determination of methyl parathion based on multiwalled carbon nanotubes-poly(acrylamide) nanocomposite film modified electrode

Energy Technology Data Exchange (ETDEWEB)

Zeng, Yanbo [Department of Chemistry and Shanghai Key Laboratory of Green Chemistry and Chemical Process, East China Normal University, 3663 Zhongshan Road(N), Shanghai, 200062 (China); College of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001 (China); Yu, Dajun; Yu, Yanyan [Department of Chemistry and Shanghai Key Laboratory of Green Chemistry and Chemical Process, East China Normal University, 3663 Zhongshan Road(N), Shanghai, 200062 (China); Zhou, Tianshu [Department of Environmental Science, East China Normal University, 3663 Zhongshan Road(N), Shanghai, 200062 (China); Shi, Guoyue, E-mail: gyshi@chem.ecnu.edu.cn [Department of Chemistry and Shanghai Key Laboratory of Green Chemistry and Chemical Process, East China Normal University, 3663 Zhongshan Road(N), Shanghai, 200062 (China)

2012-05-30

Highlights: Black-Right-Pointing-Pointer A sensitive electrochemical sensor for detecting methyl parathion in environmental samples. Black-Right-Pointing-Pointer The preparation, characterization and application of this novel MWCNTs-PAAM nanocomposite. Black-Right-Pointing-Pointer The MWCNTs-PAAM/GCE exhibited a high adsorption and strong affinity toward methyl parathion. Black-Right-Pointing-Pointer Wide linear range and low detection limit of the proposed method for detecting methyl parathion. - Abstract: A sensitive electrochemical differential pulse voltammetry method was developed for detecting methyl parathion based on multiwalled carbon nanotubes-poly(acrylamide) (MWCNTs-PAAM) nanocomposite film modified glassy carbon electrode. The novel MWCNTs-PAAM nanocomposite, containing high content of amide groups, was synthesized by PAAM polymerizing at the vinyl group functionalized MWCNTs surface using free radical polymerization. The MWCNTs-PAAM nanocomposite was characterized by Fourier transform infrared spectroscopy, thermal gravimetric analysis and scanning electron microscopy. Electrochemical behavior and interference studies of MWCNTs-PAAM/GCE for methyl parathion were investigated. The experimental results demonstrated that the MWCNTs-PAAM/GCE exhibited a high adsorption and strong affinity toward methyl parathion compared with some metal ions and nitroaromatic compounds, which exist in environmental samples. The adsorbed amount of methyl parathion on the MWCNTs-PAAM/GCE approached the equilibrium value upon 5 min adsorption time. A linear calibration curve for methyl parathion was obtained in the concentration range from 5.0 Multiplication-Sign 10{sup -9} to 1.0 Multiplication-Sign 10{sup -5} mol L{sup -1}, with a detection limit of 2.0 Multiplication-Sign 10{sup -9} mol L{sup -1}. The MWCNTs-PAAM/GCE was proved to be a suitable sensing tool for the fast, sensitive and selective determination of methyl parathion in environmental water samples.

Fatigue characterization of Poly Vinyl Chloride (PVC) foam core sandwich composite using the G-control method

DEFF Research Database (Denmark)

Manca, Marcello; Berggreen, Christian; Carlsson, Leif A.

2016-01-01

This paper presents experimental results from cyclic crack propagation tests performed on sandwich specimens with glass/epoxy face sheets and Poly Vinyl Chloride (PVC) foam cores using the G-controlled cyclic energy release rate (ΔG) test procedure. The face material was tested in tension......, compression and shear to determine in-plane and out-of-plane mechanical properties, such as Young’s modulus, Poisson’s ratio and shear modulus. These properties were then used in an analytical model of the mixed-mode bending sandwich specimen to calculate compliance and energy release rate. Finite element...... on tested specimens, highlighting the influence of mode mixity and foam density on the crack path. Crack propagation diagrams showing da/dN versus ΔG curves were obtained to establish the Paris-Erdogan relation for each material combination tested at the two mode-mixities. Results showed constant crack...

Strontium doped poly-ε-caprolactone composite scaffolds made by reactive foaming

Energy Technology Data Exchange (ETDEWEB)

Zehbe, Rolf, E-mail: zehbe@bls-germany.com [BLS Laboratories GmbH, Berlin (Germany); University of Potsdam, Institute of Physics and Astronomy, Potsdam (Germany); Zehbe, Kerstin [University of Potsdam, Department of Chemistry, Potsdam (Germany)

2016-10-01

In the reconstruction and regeneration of bone tissue, a primary goal is to initiate bone growth and to stabilize the surrounding bone. In this regard, a potentially useful component in biomaterials for bone tissue engineering is strontium, which acts as cationic active agent, triggering certain intracellular pathways and acting as so called dual action bone agent which inhibits bone resorption while stimulating bone regeneration. In this study we established a novel processing for the foaming of a polymer (poly-ε-caprolactone) and simultaneous chemical reaction of a mixture of calcium and strontium hydroxides to the respective carbonates using supercritical carbon dioxide. The resultant porous composite scaffold was optimized in composition and strontium content and was characterized via different spectroscopic (infrared and Raman spectroscopy, energy dispersive X-ray spectroscopy), imaging (SEM, μCT), mechanical testing and in vitro methods (fluorescence vital staining, MTT-assay). As a result, the composite scaffold showed good in vitro biocompatibility with partly open pore structure and the expected chemistry. First mechanical testing results indicate sufficient mechanical stability to support future in vivo applications. - Highlights: • Reactive foaming has been established for the synthesis of a PCL matrix with integrated strontium and calcium species • This material can potentially be useful in bone tissue engineering applications • Comparative in vitro cell culture experiments, imaging and spectroscopy analysis have been conducted.

Reaction rate and isomer-specific product branching ratios of C2H + C4H8: 1-butene, cis-2-butene, trans-2-butene, and isobutene at 79 K.

Science.gov (United States)

Bouwman, Jordy; Fournier, Martin; Sims, Ian R; Leone, Stephen R; Wilson, Kevin R

2013-06-20

The reactions of C2H radicals with C4H8 isomers 1-butene, cis-2-butene, trans-2-butene, and isobutene are studied by laser photolysis-vacuum ultraviolet mass spectrometry in a Laval nozzle expansion at 79 K. Bimolecular-reaction rate constants are obtained by measuring the formation rate of the reaction product species as a function of the reactant density under pseudo-first-order conditions. The rate constants are (1.9 ± 0.5) × 10(-10), (1.7 ± 0.5) × 10(-10), (2.1 ± 0.7) × 10(-10), and (1.8 ± 0.9) × 10(-10) cm(3) s(-1) for the reaction of C2H with 1-butene, cis-2-butene, trans-2-butene, and isobutene, respectively. Bimolecular rate constants for 1-butene and isobutene compare well to values measured previously at 103 K using C2H chemiluminescence. Photoionization spectra of the reaction products are measured and fitted to ionization spectra of the contributing isomers. In conjunction with absolute-ionization cross sections, these fits provide isomer-resolved product branching fractions. The reaction between C2H and 1-butene yields (65 ± 10)% C4H4 in the form of vinylacetylene and (35 ± 10)% C5H6 in the form of 4-penten-1-yne. The cis-2-butene and trans-2-butene reactions yield solely 3-penten-1-yne, and no discrimination is made between cis- and trans-3-penten-1-yne. Last, the isobutene reaction yields (26 ± 15)% 3-penten-1-yne, (35 ± 15)% 2-methyl-1-buten-3-yne, and (39 ± 15)% 4-methyl-3-penten-1-yne. The branching fractions reported for the C2H and butene reactions indicate that these reactions preferentially proceed via CH3 or C2H3 elimination rather than H-atom elimination. Within the experimental uncertainties, no evidence is found for the formation of cyclic species.

Radiosynthesis of 3-{l_brace}[4-(4-[{sup 18}F]fluorobenzyl)]piperazin-1-yl{r_brace}methyl-1H-pyrrolo[2,3-b]pyridine: A potential dopamine D{sub 4} receptor imaging agent

Energy Technology Data Exchange (ETDEWEB)

Haibin Tian; Duanzhi Yin; Junling Li; Lan Zhang; Cunfu Zhang; Yongxian Wang; Wei Zhou [Radiopharmaceutical Research Center, Shanghai Inst. of Nuclear Research, The Chinese Academy of Sciences, Shanghai, SH (China)

2003-07-01

The dopamine D{sub 4} receptor (D{sub 4}R) is expressed in low density in various extrastriatal brain regions. This receptor subtype is discussed in relation to the pathophysiology and treatment of schizophrenia but to date no selective positron emission tomography (PET) ligand is available to study its distribution in vivo. The 7-azaindole derivative 3-([4-(4-iodophenyl)piperazin-1-yl]-methyl)-1H-pyrrolo [2,3-b]pyridine (L-750,667) is a novel, high-affinity (K{sub i}=0.51nM) and selective D{sub 4}R ligand. L-750,667 analogue 3-[4-(4-[{sup 18}F]fluorobenzyl)]piperazin-1-yl methyl-1H-pyrrolo[2,3-b]-pyridine was prepared by reacting 3-(piperazin-1-yl)-methyl-1H-pyrrolo[2,3-b]pyridine with 4-[ 18F]fluorobenzaldehyde, which was labeled with no carrier added [ 18F]fluoride. The radiochemical yield of 3-[4-(4-[{sup 18}F]fluorobenzyl)]piperazin-1-yl methyl-1H-pyrrolo[2,3-b]pyridine was 12.0% at end of synthesis (EOS), and the synthesis time was 73min. The labeled benzaldehydes may be useful precursors for the radiosyntheses of other complex radiotracers for PET.

Poly(l-lysine)-graft-folic acid-coupled poly(2-methyl-2-oxazoline) (PLL-g-PMOXA-c-FA): a bioactive copolymer for specific targeting to folate receptor-positive cancer cells.

Science.gov (United States)

Chen, Yin; Cao, Wenbin; Zhou, Junli; Pidhatika, Bidhari; Xiong, Bin; Huang, Lu; Tian, Qian; Shu, Yiwei; Wen, Weijia; Hsing, I-Ming; Wu, Hongkai

2015-02-04

In this study, we present the preparation, characterization and application of a novel bioactive copolymer poly(l-lysine)-graft-folic acid-coupled poly(2-methyl-2-oxazoline) (PLL-g-PMOXA-c-FA), which has a specific interaction with folate receptor (FR)-positive cancer cells. Glass surface immobilized with PLL-g-PMOXA-c-FA was demonstrated to be adhesive to FR-positive cancer cells (HeLa, JEG-3) while nonadhesive to FR-negative ones (MCF-7, HepG2) in 3 h. The specific interaction between conjugated FA on the substrate and FRs on the cells could hardly be inhibited unless a high concentration (5 mM) of free FA was used due to the multivalent nature of it. The FA functionality ratio of the copolymer on the substrate had a significant influence on the adhesion of HeLa cells, and our experiments revealed that the affinity of the substrate to the cells declined dramatically with the decrease of functionality ratio. This was believed to be caused by the polydispersity of PMOXA tethers, as supported by GPC and ToF-SIMS data. As a proof of concept in the application of our material, we demonstrated successful recovery of HeLa cells from mixture with MCF-7 (1:100) on the copolymer-coated glass, and our results showed that both high sensitivity (95.6 ± 13.3%) and specificity (24.3 ± 8.6%) were achieved.

Chemical structure of chromium(III) crosslinked collagen-poly(methyl methacrylate) copolymers in radiation grafting

International Nuclear Information System (INIS)

Pietrucha, K.

1991-01-01

Upon γ-irradiation of aqueous emulsions of methyl methacrylate embedded into chrome tanned skin, the formation of graft copolymers is observed. The number-average molecular weight of the grafted poly(methyl methacrylate) side chains was in the range of 430000 (for a dose of 10 kGy) and practically independent of grafting degree. However, the number of branches per graft copolymer molecule increases from 0.3 to 0.8 when the degree of grafting increases from 32% to 88%. Similarly, the radiation yield, i.e. the number of branches formed per 100 eV of energy absorbed in the substrate polymer increases from 0.75 to 1.94. The value and meaning of molecular weight of graft copolymer is discussed along with the mechanism of polymer chain termination. (author) 14 refs.; 3 figs.; 4 tabs

PREPARATION OF POLY(METHYL METHACRYLATE)/LAYERED DOUBLE HYDROXIDES NANOCOMPOSITES via in situ SOLUTION POLYMERIZATION

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

An exfoliated layered double hydroxides/poly(methyl methacrylate) (LDHs/PMMA) nanocomposite was prepared by in situ solution polymerization of methyl methacrylate (MMA) in the presence of 4-vinylbenzenesulfonate intercalated LDHs(MgAl-VBS LDHs). MgAl-VBS LDHs was prepared by the ion exchange method, and the structure and composition of the MgAl-VBS LDHs were determined by X-ray diffraction (XRD), infrared spectroscopy and elemental analysis. XRD and transmission electron microscopy (TEM) were employed to examine the structure of LDHs/PMMA nanocomposite. It was indicated that the LDHs layers were well exfoliated and dispersed in the PMMA matrix. The grafting of PMMA onto LDHs was confirmed by the extraction result and the weight fraction of grafted PMMA increased as the weight fraction of LDHs in the nanocomposites increased.

Metal Adsorbent Prepared from Poly(Methyl Acrylate)-Grafted Cassava Starch via Gamma Irradiation

Energy Technology Data Exchange (ETDEWEB)

Suwanmala, P; Hemvichian, K; Srinuttrakul, W [Nuclear Research and Development Group, Thailand Institute of Nuclear Technology, Bangkok (Thailand)

2012-09-15

Metal adsorbent containing hydroxamic acid groups was successfully synthesized by radiation-induced graft copolymerization of methyl acrylate (MA) onto cassava starch. The optimum conditions for grafting were studied in terms of % degree of grafting (Dg). Conversion of the ester groups present in poly(methyl acrylate)-grafted-cassava starch copolymer into hydroxamic acid was carried out by treatment with hydroxylamine (HA) in the presence of alkaline solution. The maximum percentage conversion of the ester groups of the grafted copolymer, %Dg = 191 (7.63 mmol/g of MA), into the hydroxamic groups was 70% (5.35 mmol/g of MA) at the optimum conditions: in a mixture solution of 20% HA (w/v) and methanol solution (methanol:H{sub 2}O = 5:1) 300 mL, pH 13, reaction time 2 h, and 20 g of grafted copolymer. The adsorbent was characterized by FTIR, TGA, and DSC. The presence of electron donating groups in adsorbent containing hydroxamic acid groups gives the ability to form polycomplexes with metal ions. The ability of the adsorbent to adsorb various metals was investigated in order to evaluate the possibility of its use in metal adsorption. The adsorbent exhibited a remarkable % adsorption for Cd{sup 2+}, Al{sup 3+}, UO{sub 2} {sup 2+}, V{sup 5+} and Pb{sup 2+} at pH 3, 4, 5, 4, and 3, respectively. The adsorbent of 191%Dg had total adsorption capacities of 2.6, 1.46, 1.36, 1.15, and 1.6 mmol/g adsorbent for Cd{sup 2+}, Al{sup 3+}, UO{sub 2} {sup 2+}, V{sup 5+} and Pb{sup 2+}, respectively, in the batch mode adsorption. (author)

Biocompatibility of 17-4 PH stainless steel foam for implant applications.

Science.gov (United States)

Mutlu, Ilven; Oktay, Enver

2011-01-01

In this study, biocompatibility of 17-4 PH stainless steel foam for biomedical implant applications was investigated. 17-4 PH stainless steel foams having porosities in the range of 40-82% with an average pore size of around 600 μm were produced by space holder-sintering technique. Sintered foams were precipitation hardened for times of 1-6 h at temperatures between 450-570 °C. Compressive yield strength and Young's modulus of aged stainless steel foams were observed to vary between 80-130 MPa and 0.73-1.54 GPa, respectively. Pore morphology, pore size and the mechanical properties of the 17-4 PH stainless steel foams were close to cancellous bone. In vitro evaluations of cytotoxicity of the foams were investigated by XTT and MTT assays and showed sufficient biocompatibility. Surface roughness parameters of the stainless steel foams were also determined to characterize the foams.

Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance

Science.gov (United States)

Asfaw, Habtom D.; Roberts, Matthew R.; Tai, Cheuk-Wai; Younesi, Reza; Valvo, Mario; Nyholm, Leif; Edström, Kristina

2014-07-01

In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol-gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating with battery components. After coating with a cathode material (LiFePO4 nanoparticles), the 3D electrode presents a hierarchically structured electrode in which a porous layer of the cathode material is deposited on the rigid and bicontinuous carbon foam. The composite electrodes exhibit impressive cyclability and rate performance at different current densities affirming their importance as viable power sources in miniature devices. Footprint area capacities of 1.72 mA h cm-2 at 0.1 mA cm-2 (lowest rate) and 1.1 mA h cm-2 at 6 mA cm-2 (highest rate) are obtained when the cells are cycled in the range 2.8 to 4.0 V vs. lithium.In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol-gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating

Application of La-ZSM-5 Coated Silicon Carbide Foam Catalyst for Toluene Methylation with Methanol

Directory of Open Access Journals (Sweden)

Debarpita Ghosal

2015-07-01

Full Text Available The performance of toluene methylation reaction was studied on H-ZSM-5 catalyst modified with La, Ce and Nb at different percentage loading. It was found that 10% metal loading produced the best performance in the reaction in terms of toluene conversion. The catalyst was coated on silicon carbide foam support which showed better conversion than the pelleted catalyst. Again, among the treated and untreated H-ZSM-5, the La-ZSM-5 catalyst is chosen for the reaction for its highest selectivity towards xylene, the main product. All catalysts were characterized in terms of surface properties, SEM, XRD and NH3-TPD. Kinetic study was done on La-ZSM-5 catalyst with 10% loading. In this kineticstudy, Langmuir Hinshelwood kinetic model with surface reaction as rate controlling step was selected as the rate equation. The activation energy was found to be 47 kJ/mol. © 2015 BCREC UNDIP. All rights reserved. Received: 9th December 2014; Revised: 27th April 2015; Accepted: 29th April 2015  How to Cite: Ghosal, D., Basu, J.K., Sengupta, S. (2015. Application of La-ZSM-5 Coated Silicon Carbide Foam Catalyst for Toluene Methylation with Methanol. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (2: 201-209. (doi:10.9767/bcrec.10.2.7872.201-209 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.2.7872.201-209  

Investigation of Poly(3,4-ethylenedioxythiophene:Poly(styrenesulfonate Hole Transport Layer for Solution-Processed Polymer Solar Cells

Directory of Open Access Journals (Sweden)

Chengxi Zhang

2015-01-01

Full Text Available The inverted polymer solar cell was prepared by self-made spray-coating system, and the poly(3,4-ethylenedioxythiophene:poly(styrenesulfonate (PEDOT:PSS hole transport layer was studied. 220 nm poly-(3-hexylthiophene:[6,6]-phenylC61butyric-acid methyl-ester (P3HT:PCBM and 40 nm PEDOT:PSS were deposited on ZnO thin film subsequently by solution spray coating. Different volume of isopropyl alcohol was introduced into PEDOT:PSS to decrease the contact angle and obtain the optimum Marangoni flow. The surface morphology and roughness of PEDOT:PSS films were characterized by atomic force microscopy with varied deposition temperature from 70°C to 160°C. The improvement of power conversion efficiency (PCE was attributed to the enhancement of vertical phase separation in PEDOT:PSS film, which improved the charge transfer in the bulk cell. The highest PCE of spray-coated PSCs reached 2.80% after postannealing for 10 min.

Determination of airborne, volatile amines from polyurethane foams by sorption onto a high-capacity cation-exchange resin based on poly(succinic acid).

Science.gov (United States)

Seeber, G; Buchmeiser, M R; Bonn, G K; Bertsch, T

1998-06-05

A high-capacity carboxylic acid-functionalized resin prepared by ring-opening metathesis polymerization based on cross-linked endo,endo-poly(norborn-2-ene-5,6-dicarboxylic acid) was used for the sampling of volatile, airborne amines from polyurethane (PU) foams. Six tertiary amines which represent commonly used promotors for the formation of PUs from diisocyanates and polyols, namely pentamethyldiethylenetriamine, diazabicyclooctane, N-methylmorpholine, N-ethylmorphine, 1,4-dimethylpiperazine and N,N-dimethylethanolamine, were sorbed onto the new resin. The sorption behavior of the new material was investigated in terms of loading capacities, the influence of concentration, flow-rate as well as of the amount of resin. Breakthrough curves were recorded from each single component as well as of mixtures thereof. Finally, the resin was used for the sampling of amines evaporating from PU foams applied in buildings. Further information about time dependent concentration profiles were obtained using a combination of GC-MS and Fourier transform IR spectroscopy.

Influence of assembling pH on the stability of poly(L-glutamic acid) and poly(L-lysine) multilayers against urea treatment.

Science.gov (United States)

Zhou, Jie; Wang, Bo; Tong, Weijun; Maltseva, Elena; Zhang, Gang; Krastev, Rumen; Gao, Changyou; Möhwald, Helmuth; Shen, Jiacong

2008-04-01

Polyelectrolyte multilayers of poly(L-glutamic acid) (PGA) and poly(L-lysine) (PLL) were built up using the layer-by-layer (LbL) technique in low pH (3.6, PM3.6) and in neutral pH (7.4, PM7.4) solutions. The multilayers were then treated with a concentrated urea (one kind of denaturant for proteins and polypeptides) solution (8M) and rinsed with corresponding buffer. The buildup and treatment processes were investigated by ultraviolet visible spectroscopy and ellipsometry. The surface morphology was observed by scanning force microscopy (SFM). The inner structures were determined by X-ray reflectometry and circular dichroism spectroscopy (CD). An exponential growth of the optical mass and the layer thickness was observed for both PM3.6 and PM7.4. After urea treatment, a significant mass loss for PM3.6 was found, while no mass change was recorded for PM7.4. The dominant driving force for PM7.4 is electrostatic interaction, resulting in multilayers with an abundant beta-sheet structure, which has higher stability against urea treatment. By contrast, the dominant driving force for PM3.6 is hydrogen bonding and hydrophobic interaction, which are sensitive to the urea treatment. The mechanism is substantiated by molecular mechanics calculation. This has offered a convenient pathway to mediate the multilayer properties, which is of great importance for potential applications.

Additive effects on phase transition and interactions in poly(vinyl methyl ether) solutions

Czech Academy of Sciences Publication Activity Database

Starovoytova, Larisa; Šťastná, J.; Šturcová, Adriana; Konefal, Rafal; Dybal, Jiří; Velychkivska, Nadiia; Radecki, M.; Hanyková, L.

2015-01-01

Roč. 7, č. 12 (2015), s. 2572-2583 ISSN 2073-4360 R&D Projects: GA ČR(CZ) GA13-23392S Institutional support: RVO:61389013 Keywords : additives * LCST * poly(vinyl methyl ether) Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.944, year: 2015

Preparation and Characterization of InP/Poly(methyl methacrylate) Nanocomposite Films.

Science.gov (United States)

Kwon, Younghoon; Kim, Jongsung

2017-04-01

Quantum dots (QDs) are nanocrystalline semiconductors with many unusual optical properties. They exhibit very high fluorescence intensities and possess exceptional stability against photo-bleaching. In this study, we report the preparation of InP QDs-poly(methyl methacrylate) (PMMA) hybrids by fabricating QDs via a thermal decomposition reaction, followed by radical polymerization. The InP QDs were synthesized using indium(III) chloride and tris(dimethylamino)phosphine. Flexible composite films were obtained by radical polymerization using methyl methacrylate (MMA) as the monomer and 2,2′-azobis(2-methylpropionitrile) (AIBN) as a radical initiator. The PL intensity of the QDs was lowered upon composite formation with PMMA. However, the composites exhibited higher thermal stability than pure PMMA.

A new method to make poly acrylate foam shells

International Nuclear Information System (INIS)

Fan Yongheng; Luo Xuan; Fang Yu; Ren Hongbo; Zhang Lin; Cui Yi

2009-01-01

A triple-orifice droplet generator was designed and developed for the size-controllable continuous fabrication of hollow foam micro-shells. Solutions of an internal water phase, an oil phase (trimethylpropane triacrylate monomer, dibutyl phthalate solvent, and benzoin ethyl ether initiator), and an external water phase were used to prepare micro-shells whose diameters are between 1.5 mm and 4.0 mm successfully. Characterization of the foam shells was carried out using a scanning electron microscope and X-ray radiography. The results show that cell diameters of the shells are not above 1 um. The refractive index of the polymer framework is around 1.50. Furthermore, the shells fabricated through the triple-orifice droplet generator have a high survival probability of 93% and exhibit narrow size distribution. (authors)

Physicochemical properties of poly(lactic acid-co-glycolic acid film modified via blending with poly(butyl acrylate-co-methyl methacrylate

Directory of Open Access Journals (Sweden)

Guoquan Zhu

2013-01-01

Full Text Available A series of poly(lactic acid-co-glycolic acid (PLGA/poly(butyl acrylate-co-methyl methacrylate (P(BA-co-MMA blend films with different P(BA-co-MMA mole contents were prepared by casting the polymer blend solution in chloroform. Surface morphologies of the PLGAP(BA-co-MMA blend films were studied by scanning electron microscopy (SEM. Thermal, mechanical, and chemical properties of PLGAP(BA-co-MMA blend films were investigated by differential scanning calorimeter (DSC, thermogravimetric analysis (TGA, tensile tests, and surface contact angle tests. The introduction of P(BA-co-MMA could modify the properties of PLGA films.

Origin and fate of 4-methyl steroid hydrocarbons. I. Diagenesis of 4-methyl sterenes

Energy Technology Data Exchange (ETDEWEB)

Wolff, G.A.; Lamb, N.A.; Maxwell, J.R.

1986-03-01

Treatment of 4-methylcholest-4-ene under mild acid conditions at low temperatures gives chemical evidence for certain features seen in the distributions of sedimentary 4-methyl steroid hydrocarbons, and further indicates that many low temperature diagenetic reactions of steroids are explicable in terms of acid catalyzed rearrangements. Specifically, the results provide: (i) Indirect evidence that the 4-ene skeleton is a key intermediate in the dehydration of 4-methyl stanols in sediments. (ii) An explanation for the distribution of 4-methyl sterenes and A-nor sterenes in the lacustrine Messel shale (Eocene). (iii) An explanation for the presence of 4..beta..-methyl steranes in relatively immature sedimentary rocks, despite the precursor stanols having the 4..cap alpha..-methyl configuration. With increasing maturity in the Paris Basin shales (Lower Toarcian), the less stable 4..beta..-methyl steranes decrease gradually in abundance relative to their 4..cap alpha..-methyl counterparts, at a rate fairly similar to the change in pristane stereochemistry.

PRMT1-mediated arginine methylation controls ATXN2L localization

Energy Technology Data Exchange (ETDEWEB)

Kaehler, Christian; Guenther, Anika; Uhlich, Anja; Krobitsch, Sylvia, E-mail: krobitsc@molgen.mpg.de

2015-05-15

Arginine methylation is a posttranslational modification that is of importance in diverse cellular processes. Recent proteomic mass spectrometry studies reported arginine methylation of ataxin-2-like (ATXN2L), the paralog of ataxin-2, a protein that is implicated in the neurodegenerative disorder spinocerebellar ataxia type 2. Here, we investigated the methylation state of ATXN2L and its significance for ATXN2L localization. We first confirmed that ATXN2L is asymmetrically dimethylated in vivo, and observed that the nuclear localization of ATXN2L is altered under methylation inhibition. We further discovered that ATXN2L associates with the protein arginine-N-methyltransferase 1 (PRMT1). Finally, we showed that neither mutation of the arginine–glycine-rich motifs of ATXN2L nor methylation inhibition alters ATXN2L localization to stress granules, suggesting that methylation of ATXN2L is probably not mandatory. - Highlights: • ATXN2L is asymmetrically dimethylated in vivo. • ATXN2L interacts with PRMT1 under normal and stress conditions. • PRMT1-mediated dimethylation of ATXN2L controls its nuclear localization. • ATXN2L localization to stress granules appears independent of its methylation state.

Radiation-induced copolymerization of hexafluoroacetone with α-olefins

International Nuclear Information System (INIS)

Matsuda, O.; Watanabe, S.; Okamoto, J.; Machi, S.; Tabata, Y.

1977-01-01

The copolymerization of hexafluoroacetone with higher α-olefins above butene, such as 1-pentene (I), 1-hexene (II), 1-octene (III), 2-methyl-1-butene (IV), 2-methyl-1-pentene (V), 3-methyl-1-butene (VI), and 4-methyl-1-pentene (VII) was studied at relatively low temperatures by γ-ray irradiation. Copolymerization of II, IV, V, and VII with hexafluoroacetone was found to scarcely take place at -78 0 C in bulk, but the addition of trichlorotrifluoroethane in amounts to yield equimolar mixtures resulted in conversion of 15.7 percent for IV and of 2.1 to 4.0 percent for the other α-olefins. Higher conversion of V at -78 0 C than at 0 0 C suggest that copolymerization may take place via an ionic mechanism. The effects of various additives on the copolymerization are reported. Infrared spectral studies indicated that the double bond of the α-olefins is opened to form a polymer. The C--O double bond of the hexafluoroacetone and the α-olefin double bond are opened to form the copolymer

Two Players Make a Formidable Combination: In Situ Generated Poly(acrylic anhydride-2-methyl-acrylic acid-2-oxirane-ethyl ester-methyl methacrylate) Cross-Linking Gel Polymer Electrolyte toward 5 V High-Voltage Batteries.

Science.gov (United States)

Ma, Yue; Ma, Jun; Chai, Jingchao; Liu, Zhihong; Ding, Guoliang; Xu, Gaojie; Liu, Haisheng; Chen, Bingbing; Zhou, Xinhong; Cui, Guanglei; Chen, Liquan

2017-11-29

Electrochemical performance of high-voltage lithium batteries with high energy density is limited because of the electrolyte instability and the electrode/electrolyte interfacial reactivity. Hence, a cross-linking polymer network of poly(acrylic anhydride-2-methyl-acrylic acid-2-oxirane-ethyl ester-methyl methacrylate) (PAMM)-based electrolyte was introduced via in situ polymerization inspired by "shuangjian hebi", which is a statement in a traditional Chinese Kungfu story similar to the synergetic effect of 1 + 1 > 2. A poly(acrylic anhydride) and poly(methyl methacrylate)-based system is very promising as electrolyte materials for lithium-ion batteries, in which the anhydride and acrylate groups can provide high voltage resistance and fast ionic conductivity, respectively. As a result, the cross-linking PAMM-based electrolyte possesses a significant comprehensive enhancement, including electrochemical stability window exceeding 5 V vs Li + /Li, an ionic conductivity of 6.79 × 10 -4 S cm -1 at room temperature, high mechanical strength (27.5 MPa), good flame resistance, and excellent interface compatibility with Li metal. It is also demonstrated that this gel polymer electrolyte suppresses the negative effect resulting from dissolution of Mn 2+ ions at 25 and 55 °C. Thus, the LiNi 0.5 Mn 1.5 O 4 /Li and LiNi 0.5 Mn 1.5 O 4 /Li 4 Ti 5 O 12 cells using the optimized in situ polymerized cross-linking PAMM-based gel polymer electrolyte deliver stable charging/discharging profiles and excellent rate performance at room temperature and even at 55 °C. These findings suggest that the cross-linking PAMM is an intriguing candidate for 5 V class high-voltage gel polymer electrolyte toward high-energy lithium-on batteries.

MALDI-TOF MS coupled with collision-induced dissociation (CID) measurements of poly(methyl methacrylate)

NARCIS (Netherlands)

Baumgaertel, A.; Becer, C.R.; Gottschaldt, M.; Schubert, U.S.

2008-01-01

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was chosen for an in-detail analysis of poly(methyl methacrylate) (PMMA) in order to determine the possible fragmentation mechanism with the help of collision-induced dissociation (CID). All experiments were

Silica-Assisted Nucleation of Polymer Foam Cells with Nanoscopic Dimensions: Impact of Particle Size, Line Tension, and Surface Functionality.

Science.gov (United States)

Liu, Shanqiu; Eijkelenkamp, Rik; Duvigneau, Joost; Vancso, G Julius

2017-11-01

Core-shell nanoparticles consisting of silica as core and surface-grafted poly(dimethylsiloxane) (PDMS) as shell with different diameters were prepared and used as heterogeneous nucleation agents to obtain CO 2 -blown poly(methyl methacrylate) (PMMA) nanocomposite foams. PDMS was selected as the shell material as it possesses a low surface energy and high CO 2 -philicity. The successful synthesis of core-shell nanoparticles was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy. The cell size and cell density of the PMMA micro- and nanocellular materials were determined by scanning electron microscopy. The cell nucleation efficiency using core-shell nanoparticles was significantly enhanced when compared to that of unmodified silica. The highest nucleation efficiency observed had a value of ∼0.5 for nanoparticles with a core diameter of 80 nm. The particle size dependence of cell nucleation efficiency is discussed taking into account line tension effects. Complete engulfment by the polymer matrix of particles with a core diameter below 40 nm at the cell wall interface was observed corresponding to line tension values of approximately 0.42 nN. This line tension significantly increases the energy barrier of heterogeneous nucleation and thus reduces the nucleation efficiency. The increase of the CO 2 saturation pressure to 300 bar prior to batch foaming resulted in an increased line tension length. We observed a decrease of the heterogeneous nucleation efficiency for foaming after saturation with CO 2 at 300 bar, which we attribute to homogenous nucleation becoming more favorable at the expense of heterogeneous nucleation in this case. Overall, it is shown that the contribution of line tension to the free energy barrier of heterogeneous foam cell nucleation must be considered to understand foaming of viscoelastic materials. This finding emphasizes the need for new strategies including the use of

Synthesis and Characterization of Metal Sulfides Nanoparticles/Poly(methyl methacrylate) Nanocomposites

OpenAIRE

Ajibade, Peter A.; Mbese, Johannes Z.

2014-01-01

Metal sulfides nanoparticles in poly(methyl methacrylate) matrices were prepared and characterized by infrared spectroscopy, thermogravimetric analysis, powder X-ray diffraction, scanning electron microscope (SEM), and transmission electron microscope (TEM). The FTIR confirms the dispersion of the nanoparticles in PMMA matrices with the C=O and C–O–C bonds of the PMMA shifting slightly which may be attributed to the interactions between the nanoparticles and PMMA. The ZnS nanoparticles in PMM...

Third-order nonlinear optical properties of the poly(methyl methacrylate)-phenothiazinium dye hybrid thin films

International Nuclear Information System (INIS)

Sun, Ru; Lu, Yue-Ting; Yan, Bao-Long; Lu, Jian-Mei; Wu, Xing-Zhi; Song, Ying-Lin; Ge, Jian-Feng

2014-01-01

The third-order nonlinear optical properties of poly(methyl methacrylate) films doped with charge flowable 3,7-di(piperidinyl)phenothiazin-5-ium chloride, which tested by Z-scan method with nanosecond laser beam at 532 nm, are reported. Large third-order nonlinear optical susceptibilities (up to 10 −7 esu) and high second hyperpolarizabilities (up to 10 −27 esu) are found. The third-order nonlinear absorptions change from reverse saturated absorptions to saturated absorptions with different percentage of the phenothiazinium dye in the poly(methyl methacrylate) films, which can be explained by the accumulation phenomenon of the phenothiazinium. The results suggest that the phenothiazinium salt is a promising material for third order non-linear applications. - Highlights: • Phenothiazinium containing optical films • Strong third-order nonlinear optical (NLO) absorption • Large third-order NLO susceptibilities

Crosslinked superhydrophobic films fabricated by simply casting poly(methyl methacrylate-butyl acrylate-hydroxyethyl methacrylate)-b-poly(perfluorohexylethyl methacrylate) solution

Science.gov (United States)

Wen, Xiufang; Ye, Chao; Cai, Zhiqi; Xu, Shouping; Pi, Pihui; Cheng, Jiang; Zhang, Lijuan; Qian, Yu

2015-06-01

This study focuses on the preparation of superhydrophobic films by crosslinkable polymer material-Poly(methyl methacrylate-butyl acrylate-hydroxyethyl methacrylate)-b-Poly(perfluorohexylethyl methacrylate) (P (MMA-BA-HEMA)-b-PFMA) with a simple one-step casting process. Nanoscale micelle particles with core-shell structure was obtained by dissolving the polymer and curing agent in the mixture of acetone and 1H, 1H, 5H octafluoropentyl-1,1,2,2 tetrafluoroethyl ether (FHT). Superhydrophobic films were fabricated by casting the micelle solution on the glass slides. By controlling the polymer concentration and acetone/FHT volume ratio, superhydrophobic polymer film with water contact angle of 153.2 ± 2.1° and sliding angle of 4° was obtained. By introducing a curing agent into the micelle solution, mechanical properties of the films can be improved. The adhension grade and hardness of the crosslinked superhydrophobic films reached 2 grade and 3H, respectively. The hydrophobicity is attributed to the synergistic effect of micro-submicro-nano-meter scale roughness by nanoscale micelle particles and low surface energy of fluoropolymer. This procedure makes it possible for widespread applications of superhydrophobic film due to its simplicity and practicability.

Size and pressure effects on glass transition temperature of poly (methyl methacrylate) thin films

International Nuclear Information System (INIS)

Lang, X.Y.; Zhang, G.H.; Lian, J.S.; Jiang, Q.

2006-01-01

A simple and unified model, without any adjustable parameter, is developed for size and pressure effects on glass transition temperatures of nanopolymers. The model is based on a model for size dependent glass transition temperature of nanopolymer glasses under ambient pressure, and a pressure-dependent function of the root of mean-square displacement of atom vibration. It is found that the size- and pressure-dependent glass transition temperatures of free-standing films or supported films having weak interaction with substrates decreases with decreasing of pressure and size. However, the glass transition temperature of supported films having strong interaction with substrates increases with the increase of pressure and the decrease of size. The predicted results correspond with available experimental evidences for atactic-Poly (methyl methacrylate) thin films under hydrostatic pressure or under the pressure induced by supercritical fluid CO 2 . In addition, the predicted glass transition temperature of isotactic-Poly (methyl methacrylate) thin films under ambient pressure is consistent with available experimental evidences

Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance.

Science.gov (United States)

Asfaw, Habtom D; Roberts, Matthew R; Tai, Cheuk-Wai; Younesi, Reza; Valvo, Mario; Nyholm, Leif; Edström, Kristina

2014-08-07

In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol-gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating with battery components. After coating with a cathode material (LiFePO4 nanoparticles), the 3D electrode presents a hierarchically structured electrode in which a porous layer of the cathode material is deposited on the rigid and bicontinuous carbon foam. The composite electrodes exhibit impressive cyclability and rate performance at different current densities affirming their importance as viable power sources in miniature devices. Footprint area capacities of 1.72 mA h cm(-2) at 0.1 mA cm(-2) (lowest rate) and 1.1 mA h cm(-2) at 6 mA cm(-2) (highest rate) are obtained when the cells are cycled in the range 2.8 to 4.0 V vs. lithium.

New results in pulsed laser deposition of poly-methyl-methacrylate thin films

International Nuclear Information System (INIS)

Cristescu, R.; Socol, G.; Mihailescu, I.N.; Popescu, M.; Sava, F.; Ion, E.; Morosanu, C.O.; Stamatin, I.

2003-01-01

Thin organic films based on poly-methyl-methacrylate (PMMA) polymer have been obtained by pulsed laser deposition (PLD) on silicon substrates. The films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and Raman spectroscopy (RS). We observed that the film composition and structure depend on the laser fluence and on the temperature of the substrate during deposition

Synthesis of Poly(N-vinyl-2-pyrrolidone-co-methyl methacrylate by Maghnite-H+ a Non-toxic Catalyst

Directory of Open Access Journals (Sweden)

Mohamed Benadda

2014-10-01

Full Text Available In the present work poly (N-vinyl-2-pyrrolidone-co-methyl methacrylate copolymers were prepared successfully and cleanly by a one step process via cationic copolymerization of N-vinyl-2-pyrrolidone (NVP with methyl methacrylate (MMA, in heterogeneous phase using “Maghnite-H+” (Mag-H+ as catalyst in bulk, Maghnite is a montmorillonite sheet silicate clay exchanged with protons to produce Maghnite-H+. Temperature is varied between 20 and 80 °C. The effects of reaction temperature, amount of Mag-H+ on the yield and the intrinsic viscosity (η were investigated. A typical reaction product of poly (NVP-co- MMA was analyzed by infra red spectroscopy (FTIR and 1H-NMR, 13C-NMR spectroscopy as well as by viscosimetry. © 2014 BCREC UNDIP. All rights reservedReceived: 24th November 2013; Revised: 30th June 2014; Accepted: 8th July 2014How to Cite: Benadda, M., Ferrahi, M.I., Belbachir, M. (2014. Synthesis of Poly(N-vinyl-2-pyrrolidone-co-methyl methacrylate by Maghnite-H+ a Non-toxic Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis, 9 (3: 201-206. (doi: 10.9767/bcrec.9.3.5743.201-206Permalink/DOI: http://dx.doi.org/10.9767/bcrec.9.3.5743.201-206

The origin and fate of 4-methyl steroid hydrocarbons. I. Diagenesis of 4-methyl sterenes

Science.gov (United States)

Wolff, George A.; Lamb, Neil A.; Maxwell, James R.

1986-03-01

Treatment of 4-methylcholest-4-ene under mild acid conditions at low temperatures gives chemical evidence for certain features seen in the distributions of sedimentary 4-methyl steroid hydrocarbons, and further indicates that many low temperature diagenetic reactions of steroids are explicable in terms of acid catalysed rearrangements. Specifically, the results provide: (i) Indirect evidence that the 4-ene skeleton is a key intermediate in the dehydration of 4-methyl stanols in sediments. (ii) An explanation for the distribution of 4-methyl sterenes and A-nor sterenes in the lacustrine Messel shale (Eocene). (iii) An explanation for the presence of 4β-methyl steranes in relatively immature sedimentary rocks, despite the precursor stanols having the 4α-methyl configuration. With increasing maturity in the Paris Basin shales (Lower Toarcian), the less stable 4β-methyl steranes decrease gradually in abundance relative to their 4α-methyl counterparts, at a rate fairly similar to the change in pristane stereochemistry.

Safety and complications of absorbable threads made of poly-L-lactic acid and poly lactide/glycolide: Experience with 148 consecutive patients.

Science.gov (United States)

Sarigul Guduk, Sukran; Karaca, Nezih

2018-04-01

Thread lifting is a minimally invasive procedure for lifting and repositioning tissues. Few articles with absorbable sutures exist in the literature. Furthermore there is no study focusing on complications of absorbable sutures. To describe complications of thread lifting using a totally absorbable suture composed of poly-L-lactic acid affixed with poly lactide/glycolide cones. Data regarding complications were analyzed retrospectively for 148 patients underwent thread lifting between June 2014 and February 2017. A total of 321 pairs of sutures used in the 148 patients studied. Overall 40 (27%) patients had complications regarded as minimal or moderate without permanent sequela. The most common complication was skin dimpling and irregularity (n = 17, 11.4%) followed by ecchymosis (n = 12, 8.1%), suture extrusion (n = 4, 2.7%), and pain (n = 4, 2.7%) Except one patient, dimpling, and irregularity resolved in all patients after 3-7 days spontaneously. Suture migration was observed in 2 (1.35%) patients. Hematoma and infection were seen in 2 patients one for each. The procedure using sutures made of absorbable poly-L-lactic acid and poly lactide/glycolide is a relatively safe procedure without major complications. © 2018 Wiley Periodicals, Inc.

Direct sputtering- and electro-deposition of gold coating onto the closed surface of ultralow-density carbon-hydrogen foam cylinder

Energy Technology Data Exchange (ETDEWEB)

Luo, Jiaqiu; Yin, Jialing; Zhang, Hao; Yao, Mengqi; Hu, Wencheng, E-mail: huwc@uestc.edu.cn

2016-12-15

Highlights: • The surface pores of P(DVB/St) foam cylinder are sealed by CVD method. • Gold film was deposited on the surface of foam cylinder by magnetron sputtering. • Electroless plating was excluded in the present experiments. • The gold coatings were thickened through the electrodeposition process. - Abstract: This work aimed to fabricate a gold coating on the surface of ultralow-density carbon-hydrogen foam cylinder without electroless plating. Poly (divinylbenzene/styrene) foam cylinder was synthetized by high internal phase emulsion, and chemical vapor deposition polymerization approach was used to form a compact poly-p-xylylene film on the foam cylinder. Conducting gold thin films were directly deposited onto the poly-p-xylylene-modified foam cylinder by magnetron sputtering, and electrochemical deposition was adopted to thicken the gold coatings. The micro-structures and morphologies of poly (divinylbenzene/styrene) foam cylinder and gold coating were observed by field-emission scanning electron microscopy. The gold coating content was investigated by energy-dispersive X-ray. The thicknesses of poly-p-xylylene coating and sputtered gold thin-film were approximately 500 and 100 nm, respectively. After electrochemical deposition, the thickness of gold coating increased to 522 nm, and the gold coating achieved a compact and uniform structure.

Poly(4-vinylphenol-co-methyl methacrylate) / titanium dioxide nanocomposite gate insulators for 6,13-bis(triisopropylsilylethynyl)-pentacene thin-film transistors

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xue; Park, Jiho; Baang, Sungkeun; Park, Jaehoon [Hallym University, Chuncheon (Korea, Republic of); Piao, Shanghao; Kim, Sohee; Choi, Hyoungjin [Inha University, Incheon (Korea, Republic of)

2014-12-15

Poly(4-vinylphenol-co-methyl methacrylate) / titanium dioxide (TiO{sub 2}) nanocomposite insulators were fabricated for application in 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-Pn) thin-film transistors (TFTs). The capacitance of the fabricated capacitors with this nanocomposite insulator increased with increasing content of the high-dielectric-constant TiO{sub 2} nanoparticles. Nonetheless, particle aggregates, which were invariably produced in the insulator at higher TiO{sub 2} contents, augmented gate-leakage currents during device operation while the rough surface of the insulator obstructed charge transport in the conducting channel of the TIPS-Pn TFTs. These results suggest a significant effect of the morphological characteristics of nanocomposite insulators on TFT performance, as well as on their dielectric properties. Herein, the optimal particle composition was determined to be approximately 1.5 wt%, which contributed to characteristic improvements in the drain current, field-effect mobility, and threshold voltage of TIPS-Pn TFTs.

An effective approach to synthesis of poly(methyl methacrylate)/silica nanocomposites

International Nuclear Information System (INIS)

Ding Xuefeng; Wang Zichen; Han Dongxue; Zhang Yuanjian; Shen Yanfei; Wang Zhijuan; Niu Li

2006-01-01

A novel synthetic route for nearly monodispersed poly(methyl methacrylate)/SiO 2 composite particles (PMSCP) is reported. Silica nanoparticles modified with oleic acid were used as 'seeds'. Methyl methacrylate (MMA) monomer was copolymerized with oleic acid via in situ emulsion polymerization, in the presence of an initiator; it resulted finally in the formation of composites with core-shell morphology. The composite particles were examined by transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). The number of silica particles inside the composite particles increases with an increase in the silica concentration. The effect of grafted silica concentration on the morphology of PMSCP is also reported in detail. It was found by thermogravimetric analysis that PMSCP show a potential application for fire retardance

Mechanical, relaxation behavior and thermal degradation of UV irradiated poly(vinyl acetate)/poly( methyl methacrylate) blends

International Nuclear Information System (INIS)

Mansour, S.A.; Hafez, M.; Hussien, K.A.

2005-01-01

The effect of different doses of UV- irradiation on the mechanical and relaxation properties of poly(vinyl acetate)/poly(methyl methacrylate) blends were studied. Films of PVAc/PMMA blend with different contents were prepared using the casting technique. Also, PMMA could be blended with PVAc to improve its impact strength. Moreover UV-irradiation causes degradation of PVAc and formation of ketonic and aldehyde carbonyl groups according to a suggested scheme. Irradiation of PvAc/ PMMA blends causes a higher degree of degradation as compared to the PVAc alone although the PMMA is more susceptible than PVAc to the influence of radiation. Recognizable differences are observed for all parameters between the unirradiated and irradiated samples. Existence of a relaxation mechanism within the first 200s is reported. The shear modulus for all samples is also obtained and discussed. These data are used to calculate the strain energy density using the equation proposed by Blatzetal(1974 trans. Soc.Rheol. 18 145-61), based on the n-measure of Sethe

Reversal of methylation silencing of Apo2L/TRAIL receptor 1 (DR4) expression overcomes resistance of SK-MEL-3 and SK-MEL-28 melanoma cells to interferons (IFNs) or Apo2L/TRAIL.

Science.gov (United States)

Bae, S I; Cheriyath, V; Jacobs, B S; Reu, F J; Borden, E C

2008-01-17

Human melanoma cell lines, SK-MEL-3 and SK-MEL-28, despite induction of the proapoptotic cytokine, Apo2L/TRAIL, did not undergo apoptosis in response to interferons (IFN-alpha2b or IFN-beta). Postulating that genes important for apoptosis induction by IFNs might be silenced by methylation, the DNA demethylating agent 5-aza-2'-deoxycytidine (5-AZAdC) was assessed. DR4 (TRAIL-R1) was identified as one of the genes reactivated by 5-AZAdC with a >3-fold increase in 8 of 10 melanoma cell lines. Pretreatment with 5-AZAdC sensitized SK-MEL-3 and SK-MEL-28 cells to apoptosis induced by IFN-alpha2b and IFN-beta; methylation-specific PCR and bisulfite sequencing confirmed demethylation of 5'CpG islands of DR4 and flow cytometry showed an increase in DR4 protein on the cell surface. In cells with reactivated DR4, neutralizing mAB to TRAIL reduced apoptosis in response to IFN-beta or Apo2L/TRAIL. To further confirm the role of DR4, it was expressed by retroviral vector in SK-MEL-3 and SK-MEL-28 cells with reversal of resistance to IFN-beta and Apo2L/TRAIL. Thus, reexpressing DR4 by 5-AZAdC or retroviral transfection in melanoma cell in which promoter methylation had suppressed its expression, potentiated apoptosis by IFN-alpha2b, IFN-beta and Apo2L/TRAIL. Reactivation of silenced proapoptotic genes by inhibitors of DNA methylation may enhance clinical response to IFNs or Apo2L/TRAIL.

New optically active and thermally stable poly(amide-imide)s containing N,N'-(Bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic)-bis-L-alanine and aromatic diamines: synthesis and characterization

International Nuclear Information System (INIS)

Faghihi, Khalil; Absalar, Morteza; Hajibeygi, Mohsen

2009-01-01

Five new optically active poly(amide-imide)s (PAIs) 6a-e were prepared by direct polycondensation reaction of the newly synthesized N,N'-(bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetra carboxylic)-bis-L-alanine 4 with various aromatic diamines 5a-e using polar aprotic solvents such as N-methyl-2-pyrrolidone (NMP). In this technique triphenyl phosphite (TPP) and pyridine were used as condensing agents to form poly(amide-imide)s through the N-phosphonium salts of pyridine. All of the polymers were obtained in quantitative yields with inherent viscosities between 0.29-0.46 dL g -1 and were highly soluble in polar aprotic solvents such as N,N-dimethyl acetamide (DMAc), N,N-dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), N-methyl- 2-pyrrolidone (NMP) and solvents such as sulfuric acid. They were fully characterized by means of 1 H NMR, FTIR spectroscopy, elemental analyses, inherent viscosity, solubility test, specific rotation and thermal properties of these polymers were investigated using thermogravimetric analysis techniques (TGA and DTG). (author)

Economic process to co-produce poly(ε-l-lysine) and poly(l-diaminopropionic acid) by a pH and dissolved oxygen control strategy.

Science.gov (United States)

Xu, Zhaoxian; Feng, Xiaohai; Sun, Zhuzhen; Cao, Changhong; Li, Sha; Xu, Zheng; Xu, Zongqi; Bo, Fangfang; Xu, Hong

2015-01-01

This study tended to apply biorefinery of indigenous microbes to the fermentation of target-product generation through a novel control strategy. A novel strategy for co-producing two valuable homopoly(amino acid)s, poly(ε-l-lysine) (ε-PL) and poly(l-diaminopropionic acid) (PDAP), was developed by controlling pH and dissolved oxygen concentrations in Streptomyces albulus PD-1 fermentation. The production of ε-PL and PDAP got 29.4 and 9.6gL(-1), respectively, via fed-batch cultivation in a 5L bioreactor. What is more, the highest production yield (21.8%) of similar production systems was achieved by using this novel strategy. To consider the economic-feasibility, large-scale production in a 1t fermentor was also implemented, which would increase the gross profit of 54,243.5USD from one fed-batch bioprocess. This type of fermentation, which produces multiple commercial products from a unified process is attractive, because it will improve the utilization rate of raw materials, enhance production value and enrich product variety. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fabrication and characterization of perovskite solar cells added with MnCl2, YCl3 or poly(methyl methacrylate)

Science.gov (United States)

Taguchi, Masaya; Suzuki, Atsushi; Tanaka, Hiroki; Oku, Takeo

2018-01-01

Perovskite-type CH3NH3PbI3-based photovoltaic devices were fabricated and characterized. Effects of manganese (Mn), yttrium (Y) compounds addition into the perovskite crystal on the photovoltaic properties were investigated. Also, the effects of poly(methyl methacrylate) (PMMA) addition on perovskite layer on the photovoltaic properties were investigated. When 3 % MnCl2 was added, the short circuit current density and conversion efficiency were improved by promoting the crystal growth of perovskite phase. The photoelectric conversion efficiency for 0.9 mg mL-1 PMMA added was 7.36 %. Open circuit voltage and fill factor were improved by 5 % YCl3 addition.

Investigation of nanocomposites made with poly(methacrylic acid-co-methyl methacrylate/poly(N-vinyl-2-pyrrolidone/multi-walled carbon nanotubes

Directory of Open Access Journals (Sweden)

Liu Guoqin

2014-01-01

Full Text Available Poly(methacrylic acid-co-methyl methacrylate (P(MAA-co-MMA was prepared in the presence of poly(N-vinyl-2-pyrrolidone (PVP and multiwalled carbon nanotubes (MWNTs via ultrasonic assisted solution free radical polymerization, i.e., P(MAA-co-MMA/PVP/MWNTs nanocomposites. The morphology, glassy-state storage modulus, thermal behavior and swelling characteristics of P(MAA-co-MMA/PVP/MWNTs nanocomposites were investigated. Scanning electron micrographs (SEM revealed that MWNTs at low concentration could be uniformly dispersed into P(MAA-co-MMA/PVP blends. With increasing MWNTs weight fraction, the average glassy-state modulus, glass transition temperatures and decomposition temperature of the nanocomposites increased, but their swelling characteristics decreased.

Investigation of nanocomposites made with poly(methacrylic acid-co-methyl methacrylate)/poly(N-vinyl-2-pyrrolidone)/multi-walled carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Guoqin, Liu; Wei, Miao [College of Material Science and Engineering, Henan University of Technology (China); Lin-Jian, Shangguan, E-mail: mikepolymer@126.com [School of Mechanical Engineering, North China University of Water Conservancy and Electric Power (China)

2014-06-01

Poly(methacrylic acid-co-methyl methacrylate) (P(MAA-co-MMA)) was prepared in the presence of poly(N-vinyl-2-pyrrolidone) (PVP) and multi-walled carbon nanotubes (MWNTs) via ultrasonic assisted solution free radical polymerization, i.e., P(MAA-co-MMA)/PVP/MWNTs nanocomposites. The morphology, glassy-state storage modulus, thermal behavior and swelling characteristics of P(MAA-co-MMA)/PVP/MWNTs nanocomposites were investigated. Scanning electron micrographs (SEM) revealed that MWNTs at low concentration could be uniformly dispersed into P(MAA-co-MMA)/PVP blends. With increasing MWNTs weight fraction, the average glassy-state modulus, glass transition temperatures and decomposition temperature of the nanocomposites increased, but their swelling characteristics decreased. (author)

Insight into the theoretical and experimental studies of 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone N(4)-methyl-N(4)- phenylthiosemicarbazone - A potential NLO material

Science.gov (United States)

Sangeetha, K. G.; Aravindakshan, K. K.; Safna Hussan, K. P.

2017-12-01

The synthesis, geometrical parameters, spectroscopic studies, optimised molecular structure, vibrational analysis, Mullikan population analysis, MEP, NBO, frontier molecular orbitals and NLO effects of 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone N-(4)-methyl-N-(4)-phenylthiosemicarbazone, C25H23N5OS (L1) have been communicated in this paper. A combined experimental and theoretical approach was used to explore the structure and properties of the compound. For computational studies, Gaussian 09 program was used. Starting geometry of molecule was taken from X-ray refinement data and has been optimized by using DFT (B3LYP) method with the 6-31+G (d, p) basis sets. NBO analysis gave insight into the strongly delocalized structure, responsible for the nonlinearity and hence the stability of the molecule. Frontier molecular orbitals have been defined to forecast the global reactivity descriptors of L1. The computed first-order hyperpolarizability (β) of the compound is 2 times higher than that of urea and this account for its nonlinear optical property. Simultaneously, a molecular docking study of the compound was performed using GLIDE Program. For this, three biological enzymes, histone deacetylase, ribonucleotide reductase and DNA methyl transferase, were selected as receptor molecules.

Moisture sorption characteristics of extrusion-cooked starch protective loose-fill cushioning foams

Science.gov (United States)

Combrzyński, Maciej; Mościcki, Leszek; Kwaśniewska, Anita; Oniszczuk, Tomasz; Wójtowicz, Agnieszka; Sołowiej, Bartosz; Gładyszewska, Bożena; Muszyński, Siemowit

2017-10-01

The aim of this work was to determine the water vapour sorption properties of thermoplastic starch filling foams processed by extrusion-cooking technique from various combinations of potato starch and two foaming agents: poly(vinyl) alcohol and Plastronfoam, in amount of 1, 2 and 3% each. Foams were processed with the single screw extruder-cooker at two different screw rotational speeds 100 and 130 r.p.m. The sorption isotherms of samples were determined and described using the Guggenheim-Anderson-de Boer model. Also, the kinetics of water vapour adsorption by foams, as a function of time, was measured and fitted with Peleg model. On the basis of the analysis the influence of the applied foaming agents, as well as the technological parameters of extrusion-cooking process in relation to water vapour adsorption by thermoplastic starch foams was demonstrated. There was no difference between the shapes of the isotherms for poly(vinyl) alcohol foams while for Plastronfoam foams a notable difference among foams extruded at 100 r.p.m. was observed in the regions of low and high humidity content. The analysis of the Guggenheim-Anderson-de Boer model parameters showed that the water molecules were less strongly bound with the foam surface when extruded at a lower screw speed.

Preparation of poly(methyl methacrylate) microcapsules by in situ polymerization on the surface of calcium carbonate particles.

Science.gov (United States)

Sato, Katsuhiko; Nakajima, Tatsuya; Anzai, Jun-ichi

2012-12-01

Poly(methyl methacrylate) (PMMA) microcapsules were prepared by the in situ polymerization of methyl methacrylate (MMA) and N,N'-methylenebisacrylamide on the surface of calcium carbonate (CaCO(3)) particles, followed by the dissolution of the CaCO(3) core in ethylenediaminetetraacetic acid solution. The microcapsules were characterized using fluorescence microscopy, atomic force microscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy. The average sizes of the CaCO(3) particles and PMMA capsules were 3.8±0.6 and 4.0±0.6 μm, respectively. A copolymer consisting of MMA and rhodamine B-bearing MMA was also used to prepare microcapsules for fluorescent microscopy observations. Fluorescein isothiocyanate-labeled bovine serum albumin was enclosed in the PMMA microcapsules and its release properties were studied. Copyright © 2012 Elsevier Inc. All rights reserved.

Generation of ozone foam and its application for disinfection

Science.gov (United States)

Hiragaki, Keisuke; Ishimaru, Tomiya; Nakanishi, Masaru; Muraki, Ryouji; Nieda, Masanori; Yamabe, Chobei

2015-07-01

Generated ozone foam was applied to the disinfection of Pseudomonas fluorescens. The effect of disinfection has been confirmed experimentally and new equipment for the disinfection of hands using this ozone foam has been put on the market for the practical use. The ozone foam was produced in the foam generator after mixing the water including surfactant (30 mL/min) and air including ozone (1000 ppm = 2.14 g/m3 ~ 1600 ppm = 3.4 g/m3, 300 mL/min). The liquid-to-gas ratio is 100 L/m3. The concentration of dissolved ozone in the thin liquid films of the bubbles was about 3 mg/L which was measured by the chemical method of the KI absorption and titration of sodium thiosulfate solution. The disinfection test samples were prepared using the PET disk on which Pseudomonas fluorescens of its number of more than 108 were attached. Test sample was inserted into ozone foam set on the glass plate for one to 6 min. The survival rate log (N/N0 decreased with time and its value of about-2.6 (i.e., ~1/400) was obtained at 6 min (2 min × 3 times repeated). It was also confirmed that the ozone foam was useful for the disinfection of hands. For more effective disinfection (in case of taking a long time for foam melting), the ozone foam was broken by force and changed into ozone water by which the survival rate decreased ×4 (i.e., N/N0 = 1/10 000) at 4 ~ 6 min. Contribution to the topical issue "The 14th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XIV)", edited by Nicolas Gherardi, Ronny Brandenburg and Lars Stollenwark

Surface modification of hydroxyapatite with poly(methyl methacrylate) via surface-initiated ATRP

Energy Technology Data Exchange (ETDEWEB)

Wang Yan; Zhang Xi; Yan Jinliang; Xiao Yan [Shanghai Key Laboratory of Advanced Polymeric Materials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China); Lang Meidong, E-mail: mdlang@ecust.edu.cn [Shanghai Key Laboratory of Advanced Polymeric Materials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China)

2011-05-01

This article describes the fabrication of hydroxyapatite (HAP) nanocomposites grafted with poly(methyl methacrylate) (PMMA). Surface-initiated atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was carried out from hydroxyapatite particles derivatized with ATRP initiators. The structure and properties of the nanocomposites were investigated by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), differential scanning calorimeter (DSC) measurements, and contact angle analyses. TGA was used to estimate the grafting density of ATRP initiators (0.49 initiator/nm{sup 2}) and the amount of grafted PMMA on the HAP surface. The contact angle analyses indicated that grafting PMMA onto the HAP surface dramatically increased the hydrophobicity of the surface. Moreover, the HAP nanocomposites showed excellent dispersibility in both aqueous solution and organic solvent.

Surface modification of hydroxyapatite with poly(methyl methacrylate) via surface-initiated ATRP

International Nuclear Information System (INIS)

Wang Yan; Zhang Xi; Yan Jinliang; Xiao Yan; Lang Meidong

2011-01-01

This article describes the fabrication of hydroxyapatite (HAP) nanocomposites grafted with poly(methyl methacrylate) (PMMA). Surface-initiated atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was carried out from hydroxyapatite particles derivatized with ATRP initiators. The structure and properties of the nanocomposites were investigated by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), differential scanning calorimeter (DSC) measurements, and contact angle analyses. TGA was used to estimate the grafting density of ATRP initiators (0.49 initiator/nm 2 ) and the amount of grafted PMMA on the HAP surface. The contact angle analyses indicated that grafting PMMA onto the HAP surface dramatically increased the hydrophobicity of the surface. Moreover, the HAP nanocomposites showed excellent dispersibility in both aqueous solution and organic solvent.

New optically active and thermally stable poly(amide-imide)s containing N,N'-(Bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic)-bis-L-alanine and aromatic diamines: synthesis and characterization

Energy Technology Data Exchange (ETDEWEB)

Faghihi, Khalil; Absalar, Morteza; Hajibeygi, Mohsen [Arak University (Iran, Islamic Republic of). Faculty of Science. Organic Polymer Chemistry Research Lab.

2009-07-01

Five new optically active poly(amide-imide)s (PAIs) 6a-e were prepared by direct polycondensation reaction of the newly synthesized N,N'-(bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetra carboxylic)-bis-L-alanine 4 with various aromatic diamines 5a-e using polar aprotic solvents such as N-methyl-2-pyrrolidone (NMP). In this technique triphenyl phosphite (TPP) and pyridine were used as condensing agents to form poly(amide-imide)s through the N-phosphonium salts of pyridine. All of the polymers were obtained in quantitative yields with inherent viscosities between 0.29-0.46 dL g{sup -1} and were highly soluble in polar aprotic solvents such as N,N-dimethyl acetamide (DMAc), N,N-dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), N-methyl- 2-pyrrolidone (NMP) and solvents such as sulfuric acid. They were fully characterized by means of {sup 1}H NMR, FTIR spectroscopy, elemental analyses, inherent viscosity, solubility test, specific rotation and thermal properties of these polymers were investigated using thermogravimetric analysis techniques (TGA and DTG). (author)

One-dimensional poly(L-lysine)-block-poly(L-threonine) assemblies exhibit potent anticancer activity by enhancing membranolysis.

Science.gov (United States)

Chen, Yu-Fon; Shiau, Ai-Li; Chang, Sue-Joan; Fan, Nai-Shin; Wang, Chung-Teng; Wu, Chao-Liang; Jan, Jeng-Shiung

2017-06-01

Herein, we report the oncolytic activity of cationic, one-dimensional (1D) fibril assemblies formed from coil-sheet poly(L-lysine)-block-poly(L-threonine) (PLL-b-PLT) block copolypeptides for cancer therapy. The 1D fibril assemblies can efficiently interact with negatively charged cellular and mitochondrial membranes via electrostatic interactions, leading to necrosis via membrane lysis and apoptosis via the mitochondria-lytic effect. The concept is analogous to that of 1D drug carriers that exhibit enhanced cell penetration. In comparison to free PLL chains, PLL-b-PLT fibril assemblies exhibit selective cytotoxicity toward cancer cells, low hemolysis activity, enhanced membranolytic activity, and a different apoptosis pathway, which may be due to differences in the peptide-membrane interactions. Antitumor studies using a metastatic LL2 lung carcinoma model indicate that the fibril assemblies significantly inhibited tumor growth, improved survival in tumor-bearing mice and suppressed lung metastasis without obvious body weight loss. An additive efficacy was also observed for treatment with both PLL-b-PLT and cisplatin. These results support the feasibility of using 1D fibril assemblies as potential apoptotic anticancer therapeutics. We report that cationic, one-dimensional (1D) fibril assemblies formed by coil-sheet poly(L-lysine)-block-poly(L-threonine) (PLL-b-PLT) block copolypeptides exhibited potent anticancer activity by enhancing membranolysis. The 1D fibril assemblies can efficiently interact with negatively charged cellular and mitochondrial membranes via electrostatic interactions, leading to necrosis via membrane lysis and apoptosis via mitochondria-lytic effect. Moreover, the fibril assemblies exhibited low hemolytic activity and selective cytotoxicity toward cancer cell, which is advantageous as compared to PLL and most antimicrobial/anticancerous peptides. This study provides a new concept of using cationic, 1D fibril assemblies for cancer therapy

Synthesis of methyl-2 O-tolyl-3 quinazolone-4 {sup 14}C-2; Synthese de la methyl-2 O-tolyl-3 quinazolone-4 {sup 14}C-2

Energy Technology Data Exchange (ETDEWEB)

Herbert, M; Pichat, L [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1959-07-01

Description of the preparation of methyl-2 O-tolyl-3 quinazolone-4 {sup 14}C-2 (abbreviated to M.T.Q.), using N-acetyl {sup 14}C-1 anthranilic acid. The overall yield reaches 72 per cent with respect to acetyl chloride {sup 14}C-1. By applying the same method to acetyl chloride {sup 14}C-2, M.T.Q. labelled on the methyl group could be obtained. (author) [French] Description de la preparation de la methyl-2 O-tolyl-3 quinazolone-4 {sup 14}C-2 (abregee en M.T.Q.) par l'intermediaire de l'acide N-acetyl {sup 14}C-1 anthranilique. Le rendement global atteint 72 pour cent par rapport au chlorure d'acetyle {sup 14}C-1. La meme methode appliquee au chlorure d'acetyle {sup 14}C-2 permettrait d'obtenir la M.T.Q. marquee sur le groupement methyle. (auteur)

A simple and sensitive fluorescent sensor for methyl parathion based on L-tyrosine methyl ester functionalized carbon dots.

Science.gov (United States)

Hou, Juying; Dong, Jing; Zhu, Haishuang; Teng, Xue; Ai, Shiyun; Mang, Minglin

2015-06-15

In this paper, a simple and sensitive fluorescent sensor for methyl parathion is developed based on L-tyrosine methyl ester functionalized carbon dots (Tyr-CDs) and tyrosinase system. The carbon dots are obtained by simple hydrothermal reaction using citric acid as carbon resource and L-tyrosine methyl ester as modification reagent. The carbon dots are characterized by transmission electron microscope, high resolution transmission electron microscopy, X-ray diffraction spectrum, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The carbon dots show strong and stable photoluminescence with a quantum yield of 3.8%. Tyrosinase can catalyze the oxidation of tyrosine methyl ester on the surface of carbon dots to corresponding quinone products, which can quench the fluorescence of carbon dots. When organophosphorus pesticides (OPs) are introduced in system, they can decrease the enzyme activity, thus decrease the fluorescence quenching rate. Methyl parathion, as a model of OPs, was detected. Experimental results show that the enzyme inhibition rate is proportional to the logarithm of the methyl parathion concentration in the range 1.0×10(-10)-1.0×10(-4) M with the detection limit (S/N=3) of 4.8×10(-11) M. This determination method shows a low detection limit, wide linear range, good selectivity and high reproducibility. This sensing system has been successfully used for the analysis of cabbage, milk and fruit juice samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Ecological approach to graphene oxide reinforced poly (methyl methacrylate) nanocomposites.

Science.gov (United States)

Morimune, Seira; Nishino, Takashi; Goto, Takuya

2012-07-25

Graphene oxide (GO) possesses the desirable characteristic of aqueous solution processability attributed to the oxygen-containing functional groups on the basal planes and edges of graphene. To provide an alternative to conventional procedures for fabricating poly (methyl methacrylate) (PMMA)/GO nanocomposites, which use organic solutions and/or surfactants, we have developed an environmentally friendly technique in which PMMA is polymerized by soap-free emulsion polymerization and incorporated with GO using water as a processing medium. Experimental results showed that the fabricated PMMA/GO nanocomposites had excellent mechanical, thermal, and O2 barrier properties with the nanodispersion of GO.

Synthesis of polymer gel electrolyte with high molecular weight poly(methyl methacrylate)-clay nanocomposite

International Nuclear Information System (INIS)

Meneghetti, Paulo; Qutubuddin, Syed; Webber, Andrew

2004-01-01

Polymer nanocomposite gel electrolytes consisting of high molecular weight poly(methyl methacrylate) PMMA-clay nanocomposite, ethylene carbonate (EC)/propylene carbonate (PC) as plasticizer, and LiClO 4 electrolyte are reported. Montmorillonite clay was ion exchanged with a zwitterionic surfactant (octadecyl dimethyl betaine) and dispersed in methyl methacrylate, which was then polymerized to synthesize PMMA-clay nanocomposites. The nanocomposite was dissolved in a mixture of EC/PC with LiClO 4 , heated and pressed to obtain polymer gel electrolyte. X-ray diffraction (XRD) of the gels indicated intercalated clay structure with d-spacings of 2.85 and 1.40 nm. In the gel containing plasticizer, the clay galleries shrink suggesting intercalation rather than partial exfoliation observed in the PMMA-clay nanocomposite. Ionic conductivity varied slightly and exhibited a maximum value of 8 x 10 -4 S/cm at clay content of 1.5 wt.%. The activation energy was determined by modeling the conductivity with a Vogel-Tamman-Fulcher expression. The clay layers are primarily trapped inside the polymer matrix. Consequently, the polymer does not interact significantly with LiClO 4 electrolyte as shown by FTIR. The presence of the clay increased the glass transition temperature (Tg) of the gel as determined by differential scanning calorimetry. The PMMA nanocomposite gel electrolyte shows a stable lithium interfacial resistance over time, which is a key factor for use in electrochemical applications

Synthesis and Characterization of Solution and Melt Processible Poly(Acrylonitrile-Co-Methyl Acrylate) Statistical Copolymers

Science.gov (United States)

Pisipati, Padmapriya

Polyacrylonitrile (PAN) and its copolymers are used in a wide variety of applications ranging from textiles to purification membranes, packaging material and carbon fiber precursors. High performance polyacrylonitrile copolymer fiber is the most dominant precursor for carbon fibers. Synthesis of very high molecular weight poly(acrylonitrile-co-methyl acrylate) copolymers with weight average molecular weights of at least 1.7 million g/mole were synthesized on a laboratory scale using low temperature, emulsion copolymerization in a closed pressure reactor. Single filaments were spun via hybrid dry-jet gel solution spinning. These very high molecular weight copolymers produced precursor fibers with tensile strengths averaging 954 MPa with an elastic modulus of 15.9 GPa (N = 296). The small filament diameters were approximately 5 im. Results indicated that the low filament diameter that was achieved with a high draw ratio, combined with the hybrid dry-jet gel spinning process lead to an exponential enhancement of the tensile properties of these fibers. Carbon fibers for polymer matrix composites are currently derived from polyacrylonitrile copolymer fiber precursors where solution spinning accounts for ˜40 % of the total fiber production cost. To expand carbon fiber applications into the automotive industry, the cost of the carbon fiber needs to be reduced from 8 to ˜3-5. In order to develop an alternative melt processing route several benign plasticizers have been investigated. A low temperature, persulfate-metabisulfite initiated emulsion copolymerization was developed to synthesize poly(acrylonitrile-co-methyl acrylate) copolymers with acrylonitrile contents between 91-96 wt% with a molecular weight range of 100-200 kg/mol. This method was designed for a potential industrial scale up. Furthermore, water was investigated as a potential melting point depressant for these copolymers. Twenty-five wt% water lead to a decrease in the Tm of a 93/7 wt/wt % poly(acrylonitrile-co-methyl

Block copolymers of poly(l-lactide) and poly(e-caprolactone) or poly(ethylene glycol) prepared by reactive extrusion

NARCIS (Netherlands)

Stevels, W.M.; Bernard, A.; van de Witte, P.; van de Witte, P.; Dijkstra, Pieter J.; Feijen, Jan

1996-01-01

Blends of poly(L-lactide) (PLLA) and poly(-caprolactone) (PCL) were prepared in a co-rotating twin screw miniextruder (40 rpm, 200°). It was attempted to prepare multiblock copolymers by allowing a controlled number of transesterification reactions. Various cat-alysts (n-Bu3SnOMe, Sn(Oct)2,

Foam-mat drying technology: A review.

Science.gov (United States)

Hardy, Z; Jideani, V A

2017-08-13

This article reviews various aspects of foam-mat drying such as foam-mat drying processing technique, main additives used for foam-mat drying, foam-mat drying of liquid and solid foods, quality characteristics of foam-mat dried foods, and economic and technical benefits for employing foam-mat drying. Foam-mat drying process is an alternative method that allows the removal of water from liquid materials and pureed materials. In this drying process, a liquid material is converted into foam that is stable by being whipped after adding an edible foaming agent. The stable foam is then spread out in sheet or mat and dried by using hot air (40-90°C) at atmospheric pressure. Methyl cellulose (0.25-2%), egg white (3-20%), maltodextrin (0.5-05%), and gum Arabic (2-9%) are the commonly utilized additives for the foam-mat drying process at the given range, either combined together for their effectiveness or individual effect. The foam-mat drying process is suitable for heat sensitive, viscous, and sticky products that cannot be dried using other forms of drying methods such as spray drying because of the state of product. More interest has developed for foam-mat drying because of the simplicity, cost effectiveness, high speed drying, and improved product quality it provides.

Dip-coating of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) anodes for efficient polymer solar cells

International Nuclear Information System (INIS)

Huang, Like; Hu, Ziyang; Zhang, Ke; Chen, Peipei; Zhu, Yuejin

2015-01-01

The fabrication of anodes and active layers by dip-coating in indium tin oxide (ITO)-free polymer solar cells (PSCs) is investigated. A highly conductive poly(3, 4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS) layer was used as an anode while a blend film of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) was employed as an active layer. The transmittance and sheet resistance of dip-coated PEDOT:PSS layers prepared with different thickness were studied. These layers were integrated into PSCs. The PSCs with the dip-coated PEDOT:PSS and P3HT:PCBM films exhibited power conversion efficiencies of 3.21% and 3.03% on glass and polyethylene terephthalate substrates, respectively, comparable to those of conventional ITO-based cells. Our research results suggest the feasibility of fabricating PSCs without a traditional spin-coating process and the possibility to substitute the ITO electrodes for conducting polymer films using the facile dip-coating method. - Highlights: • ITO-free polymer solar cells (PSCs) were fabricated by dip coating method. • Highly conductive PEDOT:PSS films used as anode were prepared. • The ITO-free PSCs performance was comparable with that of the spin coated devices. • Our results suggest the possibility of replacing ITO with dip coated PEDOT:PSS

Dip-coating of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) anodes for efficient polymer solar cells

Energy Technology Data Exchange (ETDEWEB)

Huang, Like; Hu, Ziyang, E-mail: huziyang@nbu.edu.cn; Zhang, Ke; Chen, Peipei; Zhu, Yuejin, E-mail: zhuyuejin@nbu.edu.cn

2015-03-02

The fabrication of anodes and active layers by dip-coating in indium tin oxide (ITO)-free polymer solar cells (PSCs) is investigated. A highly conductive poly(3, 4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS) layer was used as an anode while a blend film of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) was employed as an active layer. The transmittance and sheet resistance of dip-coated PEDOT:PSS layers prepared with different thickness were studied. These layers were integrated into PSCs. The PSCs with the dip-coated PEDOT:PSS and P3HT:PCBM films exhibited power conversion efficiencies of 3.21% and 3.03% on glass and polyethylene terephthalate substrates, respectively, comparable to those of conventional ITO-based cells. Our research results suggest the feasibility of fabricating PSCs without a traditional spin-coating process and the possibility to substitute the ITO electrodes for conducting polymer films using the facile dip-coating method. - Highlights: • ITO-free polymer solar cells (PSCs) were fabricated by dip coating method. • Highly conductive PEDOT:PSS films used as anode were prepared. • The ITO-free PSCs performance was comparable with that of the spin coated devices. • Our results suggest the possibility of replacing ITO with dip coated PEDOT:PSS.

Morphology in binary blends of poly(vinyl methyl ether) and epsilon-caprolactone-trimethylene carbonate diblock copolymer

NARCIS (Netherlands)

Luyten, MC; Bogels, EJF; vanEkenstein, GORA; tenBrinke, G; Bras, W; Komanschek, BE; Ryan, AJ

The morphology of symmetric diblock copolymer of epsilon-caprolactone (PCL) and trimethylene carbonate (PTMC), in blends with poly(vinyl methyl ether) (PVME) is investigated with (modulated) differential scanning calorimetry (d.s.c.), time resolved small angle (SAXS) and wide angle (WAXS) X-ray

Morphology in binary blends of poly(vinyl methyl ether) and ε-caprolactone-trimethylene carbonate diblock copolymer

NARCIS (Netherlands)

Luyten, M.C.; Bögels, E.J.F.; Alberda van Ekenstein, G.O.R.; Brinke, G. ten; Bras, W.; Komanschek, B.E.; Ryan, A.J.

1997-01-01

The morphology of symmetric diblock copolymer of ε-caprolactone (PCL) and trimethylene carbonate (PTMC), in blends with poly(vinyl methyl ether) (PVME) is investigated with (modulated) differential scanning calorimetry (d.s.c.), time resolved small angle (SAXS) and wide angle (WAXS) X-ray

Effects of poly(L-lactide-ε-caprolactone) and magnesium hydroxide additives on physico-mechanical properties and degradation of poly(L-lactic acid).

Science.gov (United States)

Kang, Eun Young; Lih, Eugene; Kim, Ik Hwan; Joung, Yoon Ki; Han, Dong Keun

2016-01-01

Biodegradable poly(L-lactic acid) (PLLA) is one of the most widely used polymer in biomedical devices, but it still has limitations such as inherent brittleness and acidic degradation products. In this work, PLLA blends with poly(L-lactide-ε-caprolactone) (PLCL) and Mg(OH)2 were prepared by the thermal processing to improve their physico-mechanical and thermal properties. In addition, the neutralizing effect of Mg(OH)2 was evaluated by degradation study. The elongation of PLLA remarkably increased from 3 to 164.4 % and the glass transition temperature (Tg) of PLLA was slightly reduced from 61 to 52 °C by adding PLCL additive. Mg(OH)2 in polymeric matrix not only improved the molecular weight reduction and mechanical strength of PLLA, but also neutralized the acidic byproducts generated during polyester degradation. Therefore, the results demonstrated that the presence of PLCL and Mg(OH)2 additives in PLLA matrix could prevent the thermal decomposition and control degradation behavior of polyester.

Radiosynthesis of dimethyl-2-[{sup 18}F]-(fluoromethyl)-6-methyl-4-(2-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate for L-type calcium channel imaging

Energy Technology Data Exchange (ETDEWEB)

Sadeghpour, H. [Nuclear Medicine Research Group, Agricultural, Medical and Industrial Research School (AMIRS), Karaj (Iran); Faculty of Pharmacy and Pharmaceutical Sciences Research Center, Tehran Univ. of Medical Sciences, Tehran (Iran); Jalilian, A.R.; Akhlaghi, M.; Mirzaei, M. [Nuclear Medicine Research Group, Agricultural, Medical and Industrial Research School (AMIRS), Karaj (Iran); Shafiee, A. [Faculty of Pharmacy and Pharmaceutical Sciences Research Center, Tehran Univ. of Medical Sciences, Tehran (Iran); Miri, R. [Medicinal and Natural Products Chemistry Research Center, Shiraz Univ. of Medical Sciences, Shiraz (Iran)

2008-07-01

Dimethyl 2-(fluoromethyl)-6-methyl-4-(2-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate 4a, a fluorinated nifedipine analog, has been shown to elicit significant calcium channel blocker activity using a guinea pig ileal longitudinal smooth muscle model. In order to perform biological studies for detection of L-type calcium channel distribution, we decided to prepare the [{sup 18}F]-labeled compound. The latter compound was prepared in no-carrier-added (n.c.a.) form from dimethyl 2-(bromomethyl)-6-methyl-4-(2-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate 2 in one step at 80 C in Kryptofix[222]/K[{sup 18}F]F and acetonitrile as a solvent in 15 min. Column chromatography afforded the radiochemically pure compound in 20 min. Radiochemical purity of the {sup 18}F-nifedipine was determined by RTLC and HPLC (> 98%) and specific activity of 21-48 GBq/{mu}mol (EOB). (orig.)

Thermal Properties of Methyl Ester-Containing Poly(2-oxazolines

Directory of Open Access Journals (Sweden)

Petra J. M. Bouten

2015-10-01

Full Text Available This paper describes the synthesis and thermal properties in solution and bulk of poly(2-alkyl-oxazolines (PAOx containing a methyl ester side chain. Homopolymers of 2-methoxycarbonylethyl-2-oxazoline (MestOx and 2-methoxycarbonylpropyl-2-oxazoline (C3MestOx, as well as copolymers with 2-ethyl-2-oxazoline (EtOx and 2-n-propyl-2-oxazoline (nPropOx, with systematic variations in composition were prepared. The investigation of the solution properties of these polymers revealed that the cloud point temperatures (TCPs could be tuned in between 24 °C and 108 °C by variation of the PAOx composition. To the best of our knowledge, the TCPs of PMestOx and PC3MestOx are reported for the first time and they closely resemble the TCPs of PEtOx and PnPropOx, respectively, indicating similar hydrophilicity of the methyl ester and alkyl side chains. Furthermore, the thermal transitions and thermal stability of these polymers were investigated by DSC and TGA measurements, respectively, revealing amorphous polymers with glass transition temperatures between -1 °C and 54 °C that are thermally stable up to >300 °C.

Separator Membrane from Crosslinked Poly(Vinyl Alcohol and Poly(Methyl Vinyl Ether-alt-Maleic Anhydride

Directory of Open Access Journals (Sweden)

Charu Vashisth Rohatgi

2015-03-01

Full Text Available In this work, we report separator membranes from crosslinking of two polymers, such as poly vinyl alcohol (PVA with an ionic polymer poly(methyl vinyl ether-alt-maleic anhydride (PMVE-MA. Such interpolymer-networked systems were extensively used for biomedical and desalination applications but they were not examined for their potential use as membranes or separators for batteries. Therefore, the chemical interactions between these two polymers and the influence of such crosslinking on physicochemical properties of the membrane are systematically investigated through rheology and by critical gel point study. The hydrogen bonding and the chemical interaction between PMVE-MA and PVA resulted in highly cross-linked membranes. Effect of the molecular weight of PVA on the membrane properties was also examined. The developed membranes were extensively characterized by studying their physicochemical properties (water uptake, swelling ratio, and conductivity, thermal and electrochemical properties using differential scanning calorimetry (DSC, dynamic mechanical analysis (DMA, thermo-gravimetric analysis (TGA and electrochemical impedance spectroscopy (EIS. The DSC study shows the presence of a single Tg in the membranes indicating compatibility of the two polymers in flexible and transparent films. The membranes show good stability and ion conductivity suitable for separator applications.

Separator Membrane from Crosslinked Poly(Vinyl Alcohol) and Poly(Methyl Vinyl Ether-alt-Maleic Anhydride)

Science.gov (United States)

Rohatgi, Charu Vashisth; Dutta, Naba K.; Choudhury, Namita Roy

2015-01-01

In this work, we report separator membranes from crosslinking of two polymers, such as poly vinyl alcohol (PVA) with an ionic polymer poly(methyl vinyl ether-alt-maleic anhydride) (PMVE-MA). Such interpolymer-networked systems were extensively used for biomedical and desalination applications but they were not examined for their potential use as membranes or separators for batteries. Therefore, the chemical interactions between these two polymers and the influence of such crosslinking on physicochemical properties of the membrane are systematically investigated through rheology and by critical gel point study. The hydrogen bonding and the chemical interaction between PMVE-MA and PVA resulted in highly cross-linked membranes. Effect of the molecular weight of PVA on the membrane properties was also examined. The developed membranes were extensively characterized by studying their physicochemical properties (water uptake, swelling ratio, and conductivity), thermal and electrochemical properties using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermo-gravimetric analysis (TGA) and electrochemical impedance spectroscopy (EIS). The DSC study shows the presence of a single Tg in the membranes indicating compatibility of the two polymers in flexible and transparent films. The membranes show good stability and ion conductivity suitable for separator applications. PMID:28347019

Processing, Characterization, and Modeling of Polymer/Clay Nanocomposite Foams

Science.gov (United States)

Jo, Choonghee; Naguib, Hani E.

2007-04-01

The effects of the material parameters and processing conditions on the foam morphologies, and mechanical properties of polymer/clay nanocomposite foams were studied. Microcellular closed-cell nanocomposite foams were manufactured with poly(methylmethacrylate) (PMMA) and high density polyethylene (HDPE), where the nanoclay loadings of 0.5, 1.0, and 2.0 wt% were used. The effect of clay contents and foaming conditions on the volume expansion ratio, cell size, elastic modulus, tensile strength, and elongation at break were investigated and compared between amorphous and semicrystalline polymers. An elastic modulus model for tensile behavior of foams was proposed by using the micromechanics theory. The model was expressed in terms of microstructural properties of polymer and physical properties of the foams. The tensile experimental data of the foams were compared with those predicted by the theoretical model.

Polydimethylsiloxane microspheres with poly(methyl methacrylate) coating: Modelling, preparation, and characterization

DEFF Research Database (Denmark)

Ma, Baoguang; Hansen, Jens Henrik; Hvilsted, Søren

2015-01-01

functional PDMS microspheres were coated with poly(methyl methacrylate) (PMMA) by spin coating with different concentrations of PMMA solutions. The quality of the resulting PMMA shell is investigated using rheological measurements at 50 8C with a timesweep procedure. The results strongly suggest that PMMA-coated...... PDMS microspheres react around 20 times slower than the uncoated ones, and that the PMMA shell significantly hinders the reaction between the PDMS microsphere and cross-linker. Thus the thin PMMA shells are very efficient in protecting the reactive PDMS microspheres, since the PMMA shell forms...

Synthesis and Characterization of Metal Sulfides Nanoparticles/Poly(methyl methacrylate Nanocomposites

Directory of Open Access Journals (Sweden)

Peter A. Ajibade

2014-01-01

Full Text Available Metal sulfides nanoparticles in poly(methyl methacrylate matrices were prepared and characterized by infrared spectroscopy, thermogravimetric analysis, powder X-ray diffraction, scanning electron microscope (SEM, and transmission electron microscope (TEM. The FTIR confirms the dispersion of the nanoparticles in PMMA matrices with the C=O and C–O–C bonds of the PMMA shifting slightly which may be attributed to the interactions between the nanoparticles and PMMA. The ZnS nanoparticles in PMMA have average crystallite sizes of 4–7 nm while the CdS has particle size of 10 nm and HgS has crystallite sizes of 8–20 nm. The increasing order of particle sizes as calculated from the XRD is ZnS/PMMA

Propionyl-l-carnitine: Labelling in the N-methyl position with Carbon-11 and pharmacokinetic studies in rats

International Nuclear Information System (INIS)

Davenport, Raymond J.; Law, Marilyn P.; Pike, Victor W.; Osman, Safiye; Poole, Keith G.

1995-01-01

The prospective therapeutic, propionyl-l-carnitine, was labelled in the N-methyl position with the positron-emitter, carbon-11 (t (1(2)) = 20.4 min), with a view to studying its pharmacokinetics in humans using PET. Labelling was achieved by methylating nor-propionyl-l-carnitine hydrochloride with no-carrier-added [ 11 C]iodomethane (produced from cyclotron-produced [ 11 C]carbon dioxide) in ethanol in the presence of 1,2,2,6,6,-pentamethylpiperidine. HPLC of the reaction mixture on a strong cation exchange column provided high purity [N-methyl- 11 C]propionyl-l-carnitine in 62% radiochemical yield (decay-corrected from [ 11 C]iodomethane), ready for intravenous administration within 35 min from the end of radionuclide production. [N-methyl- 11 C]Propionyl-l-carnitine, given intravenously to rats, cleared rapidly from plasma. A slow uptake of radioactivity into myocardium and striated muscle was observed. In plasma, unchanged tracer represented 84% of the radioactivity at 2.5 min and 2.5% of the radioactivity at 60 min. In heart, unchanged tracer represented 18% of radioactivity at 2.5 min and 2.4% at 15 min. The remainder of radioactivity detected in plasma and heart was identified as [N-methyl- 11 C]l-carnitine and [N-methyl- 11 C]acetyl-l-carnitine

Macromolecular Colloids of Diblock Poly(amino acids) That Bind Insulin.

Science.gov (United States)

Constancis; Meyrueix; Bryson; Huille; Grosselin; Gulik-Krzywicki; Soula

1999-09-15

The diblock polymer poly(l-leucine-block-l-glutamate), bLE, was synthesized by acid hydrolysis of the ester poly(l-leucine-block-l-methyl glutamate). During the hydrolysis reaction the leucine block precipitates from the reaction mixture, forming nanosized particulate structures. These particles can be purified and further suspended in water or in 0.15 M phosphate saline buffer (PBS) to give stable, colloidal dispersions. TEM analysis shows the predominant particle form to be that of platelets with a diameter of 200 nm. Smaller cylindrical or spherical particles form a relatively minor fraction of the sample. After fractionation, analysis shows the platelets to be compositionally rich in leucine, while the spheres are glutamate-rich. (1)H NMR, CD, and X-ray diffraction indicate that the core of the platelets is composed of crystalline, helical leucine segments. The poly(l-glutamate) polyelectrolyte brush extending out from the two faces of the disk stabilizes individual particles from flocculation. At pH 7.4, the nanoparticles (platelets and cylinders) spontaneously adsorb proteins, such as insulin, directly from solution. Partial desorption of the protein in its native configuration can be induced by simple dilution. The reversibility of the insulin-nanoparticle complex is the basis for a potential new delivery system. Copyright 1999 Academic Press.

Adhesive PEG-based binder for aqueous fabrication of thick Li4Ti5O12 electrode

International Nuclear Information System (INIS)

Tran, Binh; Oladeji, Isaiah O.; Wang, Zedong; Calderon, Jean; Chai, Guangyu; Atherton, David; Zhai, Lei

2013-01-01

We report the first fully compressed Li 4 Ti 5 O 12 electrode designed by an aqueous process. An adhesive, elastomeric, and lithium ion conductive PEG-based copolymer is used as a binder for the aqueous fabrication thick, flexible, and densely packed Li 4 Ti 5 O 12 (LTO) electrodes. Self-adherent cathode films exceeding 200 μm in thickness and withholding high active mass loadings of 28 mg/cm 2 deliver 4.2 mAh/cm 2 at C/2 rate. Structurally defect-free electrodes are fabricated by casting aqueous cathode slurries onto nickel foam, dried, and hard-calendared at 10 tons/cm 2 . As a multifunctional material, the binder is synthesized by the copolymerization of poly(ethylene glycol) methyl ether methacrylate (PEGMA), methyl methacrylate (MMA), and isobutyl vinyl ether (IBVE) in optimal proportions. Furthermore, coordinating the binder with lithium salt is necessary for the electrode to function

Determination of 4-Chloroindole-3-Acetic Acid Methyl Ester in Lathyrus Vicia and Pisum by Gas Chromatography - Mass Spectrometry

DEFF Research Database (Denmark)

Engvild, Kjeld Christensen; Egsgaard, Helge; Larsen, Elfinn

1980-01-01

4-Chloroindole-3-acetic acid methyl ester was identified unequivocally in Lathyrus latifolius L., Vicia faba L. and Pisum sativum L. by thin layer chromatography, gas chromatography and mass spectrometry. The gas chromatographic system was able to separate underivatized chloroindole-3-acetic acid...... methyl ester isomers. The quantitative determination of 4-chloroindole-3-acetic acid methyl ester in immature seeds of these three species was performed by gas chromatography – mass spectrometry using deuterium labelled 4-chloro-indole-3-acetic acid methyl ester as an internal standard. P. sativum...

One-pot synthesis of zeolitic imidazolate framework-8/poly (methyl methacrylate-ethyleneglycol dimethacrylate) monolith coating for stir bar sorptive extraction of phytohormones from fruit samples followed by high performance liquid chromatography-ultraviolet detection.

Science.gov (United States)

You, Linna; He, Man; Chen, Beibei; Hu, Bin

2017-11-17

In this work, zeolitic imidazolate framework-8 (ZIF-8)/poly (methyl methacrylate-ethyleneglycol dimethacrylate) (MMA-EGDMA) composite monolith was in situ synthesized on stir bar by one-pot polymerization. Compared with the neat monolith, ZIF-8/poly(MMA-EGDMA) composite monolith has larger surface area and pore volume. It also exhibits higher extraction efficiency for target phytohormones than poly(MMA-EGDMA) monolith and commercial polyethylene glycol (PEG) coated stir bar. Based on it, a method of ZIF-8/poly(MMA-EGDMA) monolith coated stir bar sorptive extraction (SBSE)-high performance liquid chromatography-ultraviolet detection (HPLC-UV) was established for the analysis of five phytohormones in apple and pear samples. The developed method exhibited low limits of detection (0.11-0.51μg/L), wide linear range (0.5-500μg/L) and good recoveries (82.7-111%), which demonstrated good application potential of the ZIF-8/monolith coated stir bar in trace analysis of organic compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

Novel transparent ternary nanocomposite films of trialkoxysilane-capped poly(methyl methacrylate)/zirconia/titania with incorporating networks

International Nuclear Information System (INIS)

Wang Yuan; Zhang Dengsong; Shi Liyi; Li Li; Zhang Jianping

2008-01-01

Novel ternary nanocomposite trialkoxysilane-capped poly(methyl methacrylate)/zirconia/titania optical films were successfully prepared through a nonaqueous in situ sol-gel method. The acrylic monomers used were methyl methacrylate (MMA) and 3-(trimethoxysilyl)propyl methacrylate (MSMA). PMMA/ZrO 2 -TiO 2 incorporating networks formed from alcoholysis of poly(MMA-co-MSMA), zirconium n-butoxide and titanium isoproproxide. The structure, morphology and property of the obtained nanocomposite films were investigated by X-ray photoelectron spectra, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, scanning probe microscopy, thermogravimetric analyses, UV-vis spectrum and spectro-ellipsometer. The nanoparticle size, roughness, thermal stability, UV-shielding property, and refractive index of nanocomposite films increase with the increasing of inorganic contents. The formation mechanism and reason of such improvements were examined and interpreted in a theoretical model. The nanocomposite films possess interesting properties in thermal stability and optical response due to the uniform incorporating networks between organic polymer chains and inorganic clusters

Novel transparent ternary nanocomposite films of trialkoxysilane-capped poly(methyl methacrylate)/zirconia/titania with incorporating networks

Energy Technology Data Exchange (ETDEWEB)

Wang Yuan [Research Center of Nano Science and Technology, Department of Chemistry, Shanghai University, Shanghai 200444 (China); Zhang Dengsong [Research Center of Nano Science and Technology, Department of Chemistry, Shanghai University, Shanghai 200444 (China)], E-mail: dszhang@shu.edu.cn; Shi Liyi [Research Center of Nano Science and Technology, Department of Chemistry, Shanghai University, Shanghai 200444 (China)], E-mail: sly0726@163.com; Li Li; Zhang Jianping [Research Center of Nano Science and Technology, Department of Chemistry, Shanghai University, Shanghai 200444 (China)

2008-08-15

Novel ternary nanocomposite trialkoxysilane-capped poly(methyl methacrylate)/zirconia/titania optical films were successfully prepared through a nonaqueous in situ sol-gel method. The acrylic monomers used were methyl methacrylate (MMA) and 3-(trimethoxysilyl)propyl methacrylate (MSMA). PMMA/ZrO{sub 2}-TiO{sub 2} incorporating networks formed from alcoholysis of poly(MMA-co-MSMA), zirconium n-butoxide and titanium isoproproxide. The structure, morphology and property of the obtained nanocomposite films were investigated by X-ray photoelectron spectra, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, scanning probe microscopy, thermogravimetric analyses, UV-vis spectrum and spectro-ellipsometer. The nanoparticle size, roughness, thermal stability, UV-shielding property, and refractive index of nanocomposite films increase with the increasing of inorganic contents. The formation mechanism and reason of such improvements were examined and interpreted in a theoretical model. The nanocomposite films possess interesting properties in thermal stability and optical response due to the uniform incorporating networks between organic polymer chains and inorganic clusters.

Separation and determination of trace amounts of zinc, lead, cadmium and mercury in tap and Qaroun lake water using polyurethane foam functionalized with 4-hydroxytoluene and 4-hydroxyacetophenone

International Nuclear Information System (INIS)

Burham, N.; Abdel-Azeem, S.M.; El-Shahat, M.F.

2006-01-01

A stable chelating sorbent was synthesized by covalently linking 4-hydroxytoluene or 4-hydroxyacetophenone with the polyurethane foam (PUF) through -N=N- group. The synthesized chelating sorbents were characterized by IR and UV/vis measurements. The modified foams show excellent stability towards various solvents. Factors influencing the extraction process of Zn(II), Pb(II), Cd(II) and Hg(II) were studied and evaluated as a function of pH of metal ion solution and equilibration shaking time. The values of sorption capacity of metal ions (μg g -1 ) were determined with the two types of bonded foams. The two phenolic bonded foams were studied comparatively. The potential applications of the two newly synthesized foams for the removal and separation of the examined metal ions from two natural water samples (drinking tap water and Qaroun lake water at Fayoum City, Egypt) were investigated. Precision (assessed as a relative standard deviation, R.S.D.) was also evaluated and found to be ≤7.3% (N = 5) with a detection limit under 0.46 μg L -1

Separation and determination of trace amounts of zinc, lead, cadmium and mercury in tap and Qaroun lake water using polyurethane foam functionalized with 4-hydroxytoluene and 4-hydroxyacetophenone

Energy Technology Data Exchange (ETDEWEB)

Burham, N. [Chemistry Department, Faculty of Science, Fayoum University, Fayoum City (Egypt)]. E-mail: n_burham@yahoo.com; Abdel-Azeem, S.M. [Chemistry Department, Faculty of Science, Fayoum University, Fayoum City (Egypt); El-Shahat, M.F. [Chemistry Department, Faculty of Science, Ain-Shams University, Cairo (Egypt)

2006-10-10

A stable chelating sorbent was synthesized by covalently linking 4-hydroxytoluene or 4-hydroxyacetophenone with the polyurethane foam (PUF) through -N=N- group. The synthesized chelating sorbents were characterized by IR and UV/vis measurements. The modified foams show excellent stability towards various solvents. Factors influencing the extraction process of Zn(II), Pb(II), Cd(II) and Hg(II) were studied and evaluated as a function of pH of metal ion solution and equilibration shaking time. The values of sorption capacity of metal ions ({mu}g g{sup -1}) were determined with the two types of bonded foams. The two phenolic bonded foams were studied comparatively. The potential applications of the two newly synthesized foams for the removal and separation of the examined metal ions from two natural water samples (drinking tap water and Qaroun lake water at Fayoum City, Egypt) were investigated. Precision (assessed as a relative standard deviation, R.S.D.) was also evaluated and found to be {<=}7.3% (N = 5) with a detection limit under 0.46 {mu}g L{sup -1}.

Tuning Surface Properties of Poly(methyl methacrylate) Film Using Poly(perfluoromethyl methacrylate)s with Short Perfluorinated Side Chains.

Science.gov (United States)

Sohn, Eun-Ho; Ha, Jong-Wook; Lee, Soo-Bok; Park, In Jun

2016-09-27

To control the surface properties of a commonly used polymer, poly(methyl methacrylate) (PMMA), poly(perfluoromethyl methacrylate)s (PFMMAs) with short perfluorinated side groups (i.e., -CF3, -CF2CF3, -(CF3)2, -CF2CF2CF3) were used as blend components because of their good solubility in organic solvents, low surface energies, and high optical transmittance. The surface energies of the blend films of PFMMA with the -CF3 group and PMMA increased continuously with increasing PMMA contents from 17.6 to 26.0 mN/m, whereas those of the other polymer blend films remained at very low levels (10.2-12.6 mN/m), similar to those of pure PFMMAs, even when the blends contained 90 wt %PMMA. Surface morphology and composition measurements revealed that this result originated from the different blend structures, such as lateral and vertical phase separations. We expect that these PFMMAs will be useful in widening the applicable window of PMMA.

DPPC/poly(2-methyl-2-oxazoline)-grad-poly(2-phenyl-2-oxazoline) chimeric nanostructures as potential drug nanocarriers

International Nuclear Information System (INIS)

Pippa, Natassa; Kaditi, Eleni; Pispas, Stergios; Demetzos, Costas

2013-01-01

In this study, we report on the self assembly behavior and on stability studies of mixed (chimeric) nanosystems consisting of dipalmitoylphosphatidylcholine (DPPC) and poly(2-methyl-2-oxazoline)-grad-poly(2-phenyl-2-oxazoline) (MPOx) gradient copolymer in aqueous media and in fetal bovine serum (FBS). A gamut of light scattering techniques and fluorescence spectroscopy were used in order to extract information on the size and morphological characteristics of the nanoassemblies formed, as a function of gradient block copolymer content, as well as temperature. The hydrodynamic radii (R h ) of nanoassemblies decreased in the process of heating up to 50 °C, while the fractal dimension (d f ) values, also increased. Indomethacin was successfully incorporated into these chimeric nanocarriers. Drug release was depended on the components ratio. The present studies show that there are a number of parameters that can be used in order to alter the properties of chimeric nanosystems, and this is advantageous to the development of “smart” nanocarriers for drug delivery.

Non-crystalline composite tissue engineering scaffolds using boron-containing bioactive glass and poly(d,l-lactic acid) coatings

International Nuclear Information System (INIS)

Mantsos, T; Chatzistavrou, X; Roether, J A; Boccaccini, A R; Hupa, L; Arstila, H

2009-01-01

The aim of this study was the fabrication of three-dimensional, highly porous, bioactive scaffolds using a recently developed bioactive glass powder, denominated '0106', with nominal composition (in wt%): 50 SiO 2 , 22.6 CaO, 5.9 Na 2 O, 4 P 2 O 5 , 12 K 2 O, 5.3 MgO and 0.2 B 2 O 3 . The optimum sintering conditions for the fabrication of scaffolds by the foam-replica method were identified (sintering temperature: 670 deg, C and dwell time: 5 h). Composite samples were also fabricated by applying a biopolymer coating of poly( D,L -lactic acid) (PDLLA) using a dip coating process. The average compressive strength values were 0.4 MPa for uncoated and 0.6 MPa for coated scaffolds. In vitro bioactivity studies in simulated body fluid (SBF) showed that a carbonate hydroxyapatite (HCAp) layer was deposited on uncoated and coated scaffolds after only 4 days of immersion in SBF, demonstrating the high in vitro bioactivity of the scaffolds. It was also confirmed that the scaffold structure remained amorphous (no crystallization) after the specific heat treatment used, with scaffolds exhibiting mechanical properties and bioactivity suitable for use in bone tissue engineering applications.

Non-crystalline composite tissue engineering scaffolds using boron-containing bioactive glass and poly(d,l-lactic acid) coatings

Energy Technology Data Exchange (ETDEWEB)

Mantsos, T; Chatzistavrou, X; Roether, J A; Boccaccini, A R [Department of Materials, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Hupa, L; Arstila, H, E-mail: a.boccaccini@imperial.ac.u [Process Chemistry Centre, Abo Akademi University, Piispankatu 8, FI-20500 Turku (Finland)

2009-10-15

The aim of this study was the fabrication of three-dimensional, highly porous, bioactive scaffolds using a recently developed bioactive glass powder, denominated '0106', with nominal composition (in wt%): 50 SiO{sub 2}, 22.6 CaO, 5.9 Na{sub 2}O, 4 P{sub 2}O{sub 5}, 12 K{sub 2}O, 5.3 MgO and 0.2 B{sub 2}O{sub 3}. The optimum sintering conditions for the fabrication of scaffolds by the foam-replica method were identified (sintering temperature: 670 deg, C and dwell time: 5 h). Composite samples were also fabricated by applying a biopolymer coating of poly({sub D,L}-lactic acid) (PDLLA) using a dip coating process. The average compressive strength values were 0.4 MPa for uncoated and 0.6 MPa for coated scaffolds. In vitro bioactivity studies in simulated body fluid (SBF) showed that a carbonate hydroxyapatite (HCAp) layer was deposited on uncoated and coated scaffolds after only 4 days of immersion in SBF, demonstrating the high in vitro bioactivity of the scaffolds. It was also confirmed that the scaffold structure remained amorphous (no crystallization) after the specific heat treatment used, with scaffolds exhibiting mechanical properties and bioactivity suitable for use in bone tissue engineering applications.

Enhanced linear and nonlinear optical properties of thermally stable ZnO/poly(styrene)–poly(methyl methacrylate) nanocomposite films

International Nuclear Information System (INIS)

Jeeju, P.P.; Jayalekshmi, S.; Chandrasekharan, K.; Sudheesh, P.

2013-01-01

Highly transparent and thermally stable zinc oxide (ZnO)/poly(styrene)–poly(methyl methacrylate) (PS–PMMA) nanocomposite films have been deposited on glass substrates, from the ZnO incorporated (PS–PMMA) solutions in toluene, using spin coating technique. A chemical route at room temperature is used to synthesize the ZnO nanoparticles. Transmission electron microscope and high-resolution transmission electron microscope images show that the ZnO nanoparticles are of size around 10 nm. The composite films have been characterized by X-ray diffraction, Fourier transform infrared spectroscopy, atomic force microscopy, Ultraviolet–visible–Near Infrared (UV–vis–NIR) spectroscopy, Thermo-gravimetric analysis, photoluminescence (PL) spectroscopy and Z-scan technique. From the UV–vis–NIR spectra it is observed that the ZnO/PS–PMMA nanocomposite films with 10 wt.% ZnO content exhibit excellent shielding property in the UV region and, high transparency in the visible region. The PL spectrum of the composite films is different from that of ZnO and PS–PMMA blend and exhibits an excitonic emission peak at ∼ 375 nm. The optical absorptive nonlinearity in the nanocomposite films is investigated using open aperture Z-scan technique. The results indicate optical limiting type nonlinearity in the films due to two photon absorption. A transmittance minimum of around 0.25 has been observed in the ZnO/PS–PMMA nanocomposite films which is much lower compared to that in ZnO/PMMA and ZnO/PS nanocomposite films. The ZnO/PS–PMMA nanocomposite films also show a self-defocusing type negative nonlinear refraction in closed aperture Z-scan experiment. These nanocomposite films extend ample scope of applications as excellent optical limiters and efficient UV protectors. - Highlights: ► Transparent, ZnO/poly(styrene)–poly(methyl methacrylate) composite films are prepared. ► The nanocomposite films with 10 wt.% ZnO content exhibit good UV-shielding property. �

Enhanced linear and nonlinear optical properties of thermally stable ZnO/poly(styrene)–poly(methyl methacrylate) nanocomposite films

Energy Technology Data Exchange (ETDEWEB)

Jeeju, P.P., E-mail: jeejupp@gmail.com [Division for Research in Advanced Materials, Department of Physics, Cochin University of Science and Technology, Kochi 682 022, Kerala (India); Jayalekshmi, S., E-mail: jayalekshmi@cusat.ac.in [Division for Research in Advanced Materials, Department of Physics, Cochin University of Science and Technology, Kochi 682 022, Kerala (India); Chandrasekharan, K.; Sudheesh, P. [Department of Physics, National Institute of Technology, Calicut, Kerala (India)

2013-03-01

Highly transparent and thermally stable zinc oxide (ZnO)/poly(styrene)–poly(methyl methacrylate) (PS–PMMA) nanocomposite films have been deposited on glass substrates, from the ZnO incorporated (PS–PMMA) solutions in toluene, using spin coating technique. A chemical route at room temperature is used to synthesize the ZnO nanoparticles. Transmission electron microscope and high-resolution transmission electron microscope images show that the ZnO nanoparticles are of size around 10 nm. The composite films have been characterized by X-ray diffraction, Fourier transform infrared spectroscopy, atomic force microscopy, Ultraviolet–visible–Near Infrared (UV–vis–NIR) spectroscopy, Thermo-gravimetric analysis, photoluminescence (PL) spectroscopy and Z-scan technique. From the UV–vis–NIR spectra it is observed that the ZnO/PS–PMMA nanocomposite films with 10 wt.% ZnO content exhibit excellent shielding property in the UV region and, high transparency in the visible region. The PL spectrum of the composite films is different from that of ZnO and PS–PMMA blend and exhibits an excitonic emission peak at ∼ 375 nm. The optical absorptive nonlinearity in the nanocomposite films is investigated using open aperture Z-scan technique. The results indicate optical limiting type nonlinearity in the films due to two photon absorption. A transmittance minimum of around 0.25 has been observed in the ZnO/PS–PMMA nanocomposite films which is much lower compared to that in ZnO/PMMA and ZnO/PS nanocomposite films. The ZnO/PS–PMMA nanocomposite films also show a self-defocusing type negative nonlinear refraction in closed aperture Z-scan experiment. These nanocomposite films extend ample scope of applications as excellent optical limiters and efficient UV protectors. - Highlights: ► Transparent, ZnO/poly(styrene)–poly(methyl methacrylate) composite films are prepared. ► The nanocomposite films with 10 wt.% ZnO content exhibit good UV-shielding property. �

Release of Bacteriocins from Nanofibers Prepared with Combinations of Poly(D,L-lactide (PDLLA and Poly(Ethylene Oxide (PEO

Directory of Open Access Journals (Sweden)

Leon Dicks

2011-03-01

Full Text Available Plantaricin 423, produced by Lactobacillus plantarum, and bacteriocin ST4SA produced by Enterococcus mundtii, were electrospun into nanofibers prepared from different combinations of poly(D,L-lactide (PDLLA and poly(ethylene oxide (PEO dissolved in N,N-dimethylformamide (DMF. Both peptides were released from the nanofibers with a high initial burst and retained 88% of their original antimicrobial activity at 37 °C. Nanofibers have the potential to serve as carrier matrix for bacteriocins and open a new field in developing controlled antimicrobial delivery systems for various applications.

Crystalline structures and crystallization behaviors of poly(L-lactide) in poly(L-lactide)/graphene nanosheet composites

DEFF Research Database (Denmark)

Li, Jingqing; Xiao, Peitao; Li, Hongfei

2015-01-01

Poly(L-lactide) (PLLA)/graphene nanosheet (GNS) composites and pure PLLA were prepared by the solution blending method. Crystalline structures and crystallization behaviors of PLLA in the composite were investigated by XRD, POM, SAXS, and DSC. It was found that α′ form PLLA formation seemed...

Polyol mediated nano size zinc oxide and nanocomposites with poly(methyl methacrylate

Directory of Open Access Journals (Sweden)

2011-07-01

Full Text Available Organophilic nano ZnO particles have been synthesized in various diols (ethylene glycol – EG, 1,2 propane diol – PD, 1,4 butane diol – BD and tetra(ethylene glycol – TEG in the presence of p-toluenesulfonic acid, p-TsOH, as an end capping agent. The addition of p-TsOH reduces the ZnO particle size and increases its crystallite size. With increasing diol main chain length the ZnO particle size increases (EG (32 nm < PD (33 nm < BD (72 nm < TEG (86 nm. Using the assynthesized and unmodified ZnO nanocomposites with poly(methyl methacrylate, PMMA, matrix have been prepared by the in-situ bulk polymerization of methyl methacrylate, MMA. The addition of surface modifiers is avoided which is an advantage for the application since they can influence other properties of the material. ZnO particles, especially those with smaller particle sizes (EG – 32 nm, PD – 33 nm showed enhanced effect on the thermal stability of PMMA, ultraviolet, UV, absorption and transparency for visible light. Transparent materials with high UV absorption and with enhanced resistance to sunlight were obtained by optimizing the nanocomposite preparation procedure using ZnO particles of about 30 nm size in concentrations between 0.05 and 0.1 wt%. The reported nanocomposite preparation procedure is compatible with the industrial process of PMMA sheet production.

Poly-L-arginine: Enhancing Cytotoxicity and Cellular Uptake of Doxorubicin and Necrotic Cell Death.

Science.gov (United States)

Movafegh, Bahareh; Jalal, Razieh; Mohammadi, Zobeideh; Aldaghi, Seyyede Araste

2018-04-11

Cell resistance to doxorubicin and its toxicity to healthy tissue reduce its efficiency. The use of cell penetrating peptides as drug delivery system along with doxorubicin is a strategy to reduce its side effects. In this study, the influence of poly-L-arginine on doxorubicin cytotoxicity, its cellular uptake and doxorubicin-induced apoptosis on human prostate cancer DU145 cells are assessed. The cytotoxicity of doxorubicin and poly-L-arginine, alone and in combination, in DU145 cells was evaluated at different exposure times using MTT assay. The influence of poly-L-arginine on doxorubicin delivery into cells was evaluated by fluorescence microscopy and ultraviolet spectroscopy. DAPI and ethidium bromide-acridine orange stainings, flow cytometry using annexin V/propidium iodide, western blot analysis with anti-p21 antibody and caspase-3 activity were used to examine the influence of poly-L-arginine on doxorubicin-induced cell death. Poly-L-arginine had no cytotoxicity at low concentrations and short exposure times. Poly-L-arginine increased the cytotoxic effect of doxorubicin in DU145 cells in a time-dependent manner. But no significant reduction was found in HFF cell viability. Poly-L-arginine seems to facilitate doxorubicin uptake and increase its intracellular concentration. 24 h combined treatment of cells with doxorubicin (0.5 μM) and poly-L-arginine (1 μg ml-1) caused a small increase in doxorubicin-induced apoptosis and significant elevated necrosis in DU145 cells as compared to each agent alone. Conlusion: Our results indicate that poly-L-arginine at lowest and highest concentrations act as proliferation-inducing and antiproliferative agents, respectively. Between these concentrations, poly-L-arginine increases the cellular uptake of doxorubicin and its cytotoxicity through induction of necrosis. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Crystallization and degradation behaviors of poly(butylene succinate)/poly(Z-L-lysine) composites

International Nuclear Information System (INIS)

Tan, Licheng; Hu, Jun; Ye, Suwen; Wei, Junchao; Chen, Yiwang

2014-01-01

Highlights: • A new biodegradable poly(butylene succinate) (PBS)/poly(Z-L-lysine) (PZlys) composites were successfully prepared through physical blend. • PZlys may greatly affected the crystallization behaviors of PBS without changing its crystalline structure. • The degradation speed of PBS may be greatly accelerated by introduction of PZlys in PBS matrix. - Abstract: A new type of biodegradable poly(butylene succinate) (PBS)/poly(Z-L-lysine) (PZlys) composites were prepared. The crystallization behaviors were investigated by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and polarizing optical microscopy (POM) and the results showed that PZlys can restrict the crystallization of PBS, the crystallization speed of PBS/PZlys were slower than that of PBS, and the crystallization degree of the composites were smaller than that of PBS. However, the WAXD results showed that the incorporation of PZlys did not change the crystalline structure of PBS. The in vitro degradation experiments demonstrated that the degradation speed of the composites were faster than that of PBS. Moreover, the mechanical properties of the composites showed that the composites with a proper composition (for example, 80/20) can keep the mechanical properties of PBS without evident difference, which implied that the composites might be potentially useful as biodegradable materials

Peel/seal properties of poly(ethylene methyl acrylate)/polybutene-1 blend films

Science.gov (United States)

Mohammdi, Seyedeh Raziyeh; Ajji, Abdellah; Tabatabaei, Seyed H.

2015-05-01

Nowadays, the possibility to easy open a food package is of great interest both from the consumer and food producers' perspective. In this study, the peel/seal properties of poly (ethylene methyl acrylate) (EMA)/polybutene-1 (PB-1) blend films were investigated. Three blends of EMA/PB-1 with different methyl acrylate (MA) content were prepared using cast extrusion process. Differential Scanning Calorimetry (DSC) was used to investigate the thermal behavior as well as the crystalinity of the blends. The effect of polymer matrix on the crystalline structure of PB-1 was studied using Wide Angle X-ray Diffraction (WAXD) and DSC. T-peel tests were carried out on the heat sealed films at various seal temperatures. The effect of MA content and heat seal temperature on peel/seal properties (i.e. peel initiation temperature, temperature window of sealability and peel strength) of the films were studied.

Peel/seal properties of poly(ethylene methyl acrylate)/polybutene-1 blend films

Energy Technology Data Exchange (ETDEWEB)

Mohammdi, Seyedeh Raziyeh; Ajji, Abdellah; Tabatabaei, Seyed H. [Department of Chemical Engineering, École Polytechnique de Montréal, Montréal, Québec, H3C3A7 (Canada)

2015-05-22

Nowadays, the possibility to easy open a food package is of great interest both from the consumer and food producers’ perspective. In this study, the peel/seal properties of poly (ethylene methyl acrylate) (EMA)/polybutene-1 (PB-1) blend films were investigated. Three blends of EMA/PB-1 with different methyl acrylate (MA) content were prepared using cast extrusion process. Differential Scanning Calorimetry (DSC) was used to investigate the thermal behavior as well as the crystalinity of the blends. The effect of polymer matrix on the crystalline structure of PB-1 was studied using Wide Angle X-ray Diffraction (WAXD) and DSC. T-peel tests were carried out on the heat sealed films at various seal temperatures. The effect of MA content and heat seal temperature on peel/seal properties (i.e. peel initiation temperature, temperature window of sealability and peel strength) of the films were studied.

Peel/seal properties of poly(ethylene methyl acrylate)/polybutene-1 blend films

International Nuclear Information System (INIS)

Mohammdi, Seyedeh Raziyeh; Ajji, Abdellah; Tabatabaei, Seyed H.

2015-01-01

Nowadays, the possibility to easy open a food package is of great interest both from the consumer and food producers’ perspective. In this study, the peel/seal properties of poly (ethylene methyl acrylate) (EMA)/polybutene-1 (PB-1) blend films were investigated. Three blends of EMA/PB-1 with different methyl acrylate (MA) content were prepared using cast extrusion process. Differential Scanning Calorimetry (DSC) was used to investigate the thermal behavior as well as the crystalinity of the blends. The effect of polymer matrix on the crystalline structure of PB-1 was studied using Wide Angle X-ray Diffraction (WAXD) and DSC. T-peel tests were carried out on the heat sealed films at various seal temperatures. The effect of MA content and heat seal temperature on peel/seal properties (i.e. peel initiation temperature, temperature window of sealability and peel strength) of the films were studied

REMOVE AND RELEASE OF NUTRIENTS AFTER HYBRID PRE-TREATMENT OF ACTIVATED SLUDGE FOAM

Directory of Open Access Journals (Sweden)

Alicja Machnicka

2017-02-01

Full Text Available One of the problems in wastewater treatment technologies is the formation of foam/scum on the surface of bioreactors. The foam elimination/destruction can be carried out by various methods among which disintegration is included. Hybrid disintegration (chemical decomposition and hydrodynamic cavitation of the foam microorganisms results in phosphates, ammonium nitrogen, magnesium and potassium transferred from the foam solids into the liquid phase. Application of both methods as a hybrid pre-treatment process caused in an increased concentration of phosphates of about 677 mg PO43- L-1, ammonium nitrogen about 41 mg N-NH4+ L-1. The concentration of Mg2+ and K+ in the solution increased from 6.2 to 31.1 mg Mg2+ L-1 and from 22.4 to 102.0 mg K+ L-1, respectively. The confirmation of physicochemical changes and release of cellular matter as a result of cellular lysis (hybrid disintegration was IR analysis. It was demonstrated that the disintegration of foam permits removal of a part of nutrients in the form of struvite.

Synthesis of rigid polyurethane foams from phosphorylated biopolyols.

Science.gov (United States)

de Haro, Juan Carlos; López-Pedrajas, Daniel; Pérez, Ángel; Rodríguez, Juan Francisco; Carmona, Manuel

2017-08-18

Renewable resources are playing a key role on the synthesis of biodegradable polyols. Moreover, the incorporation of covalently linked additives is increasing in importance in the polyurethane (PU) market. In this work, previously epoxidized grape seed oil and methyl oleate were transformed into phosphorylated biopolyols through an acid-catalyzed ring-opening hydrolysis in the presence of H 3 PO 4 . The formation of phosphate polyesters was confirmed by FT-IR and 31 P-NMR. However, the synthesis of a high-quality PU rigid foam was not possible using exclusively these polyols attending to their low hydroxyl value. In that way, different rigid PU foams were prepared from the phosphorylated biopolyols and the commercial polyol Alcupol R4520. It was observed that phosphorylated biopolyols can be incorporated up to a 57 wt.% in the PU synthesis without significant structural changes with respect to the commercial foam. Finally, thermogravimetric and EDAX analyses revealed an improvement of thermal stability by the formation of a protective phosphorocarbonaceous char layer.

Superparamagnetic poly(methyl methacrylate) nanoparticles surface modified with folic acid presenting cell uptake mediated by endocytosis

Energy Technology Data Exchange (ETDEWEB)

Feuser, Paulo Emilio [Federal University of Santa Catarina, Department of Chemical Engineering and Food Engineering (Brazil); Jacques, Amanda Virtuoso [Federal University of Santa Catarina, Department of Clinical Analyses (Brazil); Arévalo, Juan Marcelo Carpio; Rocha, Maria Eliane Merlin [Federal University of Paraná, Department of Biochemistry and Molecular Biology (Brazil); Santos-Silva, Maria Claudia dos [Federal University of Santa Catarina, Department of Clinical Analyses (Brazil); Sayer, Claudia; Araújo, Pedro H. Hermes de, E-mail: pedro.h.araujo@ufsc.br [Federal University of Santa Catarina, Department of Chemical Engineering and Food Engineering (Brazil)

2016-04-15

The encapsulation of superparamagnetic nanoparticles (MNPs) in polymeric nanoparticles (NPs) with modified surfaces can improve targeted delivery and induce cell death by hyperthermia. The goals of this study were to synthesize and characterize surface modified superparamagnetic poly(methyl methacrylate) with folic acid (FA) prepared by miniemulsion polymerization (MNPsPMMA-FA) and to evaluate their in vitro cytotoxicity and cellular uptake in non-tumor cells, murine fibroblast (L929) cells and tumor cells that overexpressed folate receptor (FR) β, and chronic myeloid leukemia cells in blast crisis (K562). Lastly, hemolysis assays were performed on human red blood cells. MNPsPMMA-FA presented an average mean diameter of 135 nm and a saturation magnetization (Ms) value of 37 emu/g of iron oxide, as well as superparamagnetic behavior. The MNPsPMMA-FA did not present cytotoxicity in L929 and K562 cells. Cellular uptake assays showed a higher uptake of MNPsPMMA-FA than MNPsPMMA in K562 cells when incubated at 37 °C. On the other hand, MNPsPMMA-FA showed a low uptake when endocytosis mechanisms were blocked at low temperature (4 °C), suggesting that the MNPsPMMA-FA uptake was mediated by endocytosis. High concentrations of MNPsPMMA-FA showed hemocompatibility when incubated for 24 h in human red blood cells. Therefore, our results suggest that these carrier systems can be an excellent alternative in targeted drug delivery via FR.

Superparamagnetic poly(methyl methacrylate) nanoparticles surface modified with folic acid presenting cell uptake mediated by endocytosis

International Nuclear Information System (INIS)

Feuser, Paulo Emilio; Jacques, Amanda Virtuoso; Arévalo, Juan Marcelo Carpio; Rocha, Maria Eliane Merlin; Santos-Silva, Maria Claudia dos; Sayer, Claudia; Araújo, Pedro H. Hermes de

2016-01-01

The encapsulation of superparamagnetic nanoparticles (MNPs) in polymeric nanoparticles (NPs) with modified surfaces can improve targeted delivery and induce cell death by hyperthermia. The goals of this study were to synthesize and characterize surface modified superparamagnetic poly(methyl methacrylate) with folic acid (FA) prepared by miniemulsion polymerization (MNPsPMMA-FA) and to evaluate their in vitro cytotoxicity and cellular uptake in non-tumor cells, murine fibroblast (L929) cells and tumor cells that overexpressed folate receptor (FR) β, and chronic myeloid leukemia cells in blast crisis (K562). Lastly, hemolysis assays were performed on human red blood cells. MNPsPMMA-FA presented an average mean diameter of 135 nm and a saturation magnetization (Ms) value of 37 emu/g of iron oxide, as well as superparamagnetic behavior. The MNPsPMMA-FA did not present cytotoxicity in L929 and K562 cells. Cellular uptake assays showed a higher uptake of MNPsPMMA-FA than MNPsPMMA in K562 cells when incubated at 37 °C. On the other hand, MNPsPMMA-FA showed a low uptake when endocytosis mechanisms were blocked at low temperature (4 °C), suggesting that the MNPsPMMA-FA uptake was mediated by endocytosis. High concentrations of MNPsPMMA-FA showed hemocompatibility when incubated for 24 h in human red blood cells. Therefore, our results suggest that these carrier systems can be an excellent alternative in targeted drug delivery via FR.

Superparamagnetic poly(methyl methacrylate) nanoparticles surface modified with folic acid presenting cell uptake mediated by endocytosis

Science.gov (United States)

Feuser, Paulo Emilio; Jacques, Amanda Virtuoso; Arévalo, Juan Marcelo Carpio; Rocha, Maria Eliane Merlin; dos Santos-Silva, Maria Claudia; Sayer, Claudia; de Araújo, Pedro H. Hermes

2016-04-01

The encapsulation of superparamagnetic nanoparticles (MNPs) in polymeric nanoparticles (NPs) with modified surfaces can improve targeted delivery and induce cell death by hyperthermia. The goals of this study were to synthesize and characterize surface modified superparamagnetic poly(methyl methacrylate) with folic acid (FA) prepared by miniemulsion polymerization (MNPsPMMA-FA) and to evaluate their in vitro cytotoxicity and cellular uptake in non-tumor cells, murine fibroblast (L929) cells and tumor cells that overexpressed folate receptor (FR) β, and chronic myeloid leukemia cells in blast crisis (K562). Lastly, hemolysis assays were performed on human red blood cells. MNPsPMMA-FA presented an average mean diameter of 135 nm and a saturation magnetization (Ms) value of 37 emu/g of iron oxide, as well as superparamagnetic behavior. The MNPsPMMA-FA did not present cytotoxicity in L929 and K562 cells. Cellular uptake assays showed a higher uptake of MNPsPMMA-FA than MNPsPMMA in K562 cells when incubated at 37 °C. On the other hand, MNPsPMMA-FA showed a low uptake when endocytosis mechanisms were blocked at low temperature (4 °C), suggesting that the MNPsPMMA-FA uptake was mediated by endocytosis. High concentrations of MNPsPMMA-FA showed hemocompatibility when incubated for 24 h in human red blood cells. Therefore, our results suggest that these carrier systems can be an excellent alternative in targeted drug delivery via FR.

Determination of trace elements in poly(methyl methacrylate) by neutron activation analysis

International Nuclear Information System (INIS)

Kobayashi, M.

1979-01-01

The results are reported of the neutron activation analysis of poly(methyl methacrylate) polymerized with a redox system of chromium (II) acetate and p-chlorobenzyl peroxide in dimethylformamide at 30 0 C. Since the polymer was originally synthesized in experiments for kinetic studies, the results indicate an arbitrary background of purity of polymers obtained in a laboratory. Samples were irradiated for 28m and gamma spectra detected trace amounts of chlorine, aluminum, vanadium, magnesium, manganese, potassium, copper, zinc, sodium, bromine, lanthanum, gold, and chromium. 2 figures, 1 table

Fracture resistance of Kevlar-reinforced poly(methyl methacrylate) resin: a preliminary study.

Science.gov (United States)

Berrong, J M; Weed, R M; Young, J M

1990-01-01

The reinforcing effect of Kevlar fibers incorporated in processed poly(methyl methacrylate) resin samples was studied using 0% (controls), 0.5%, 1%, and 2% by weight of the added fibers. The samples were subjected to impact testing to determine fracture resistance, and sample groups were statistically compared using an ANOVA. Each reinforced sample had significantly greater fracture resistance (P less than 0.05) than the control, and no difference was found either within or between control groups. The use of reinforcing Kevlar fibers appears to enhance the fracture resistance of acrylic resin denture base materials.

Morphology and performance of poly(2-methoxy-5-(20-ethyl-hexyloxy)-p-phenylenevinylene) (MEH-PPV) : (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) based polymer solar cells

NARCIS (Netherlands)

Liu, L.J.; Bavel, van S.S.; Wen, S.P.; Yang, X.N.; Loos, J.

2013-01-01

Polymer solar cells were fabricated based on composite films of poly(2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylenevinylene) (MEH-PPV):fullerene derivative (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) with weight blend ratio of 1:3, 1:4 and 1:5, spin-coated from chloroform (CF), chlorobenzene

High molecular weight poly(L-lactide) and poly(ethylene oxide) blends : Thermal characterization and physical properties

NARCIS (Netherlands)

Nijenhuis, AJ; Colstee, E; Grijpma, DW; Pennings, AJ

1996-01-01

The miscibility of high molecular weight poly(L-lactide) (PLLA) with high molecular weight poly(ethylene oxide) (PEG) was studied by differential scanning calorimetry. Ail blends containing up to 50 weight% PEO showed single glass transition temperatures. The PLLA and PEO melting temperatures were

Poly(methyl methacrylate) films for organic vapour sensing

CERN Document Server

Capan, R; Hassan, A K; Tanrisever, T

2003-01-01

Optical constants and fabrication parameters are investigated using surface plasmon resonance (SPR) studies on spun films of poly(methyl methacrylate) (PMMA) derivatives in contact with two different dielectric media. A value of 1.503 for the refractive index of PMMA films produced from a solution having concentration of 1 mg ml sup - sup 1 at the speed of 3000 rpm is in close agreement with the data obtained from ellipsometric measurements. The film thickness shows a power-law dependence on the spin speed but the thickness increases almost linearly with the concentration of the spreading solution. These results are in good agreement with the hydrodynamic theory for a low-viscosity and highly volatile liquid. On the basis of SPR measurements under dynamic conditions, room temperature response of PMMA films to benzene vapours is found to be fast, highly sensitive and reversible. The sensitivity of detection of toluene, ethyl benzene and m-xylene is much smaller than that of benzene.

One-pot synthesis of biocompatible boronic acid-functionalized poly(methyl methacrylate) nanoparticles at sub-100 nm scale for glucose sensing

Energy Technology Data Exchange (ETDEWEB)

Sakalak, Huseyin [Selcuk University, Metallurgy and Materials Engineering (Turkey); Ulasan, Mehmet; Yavuz, Emine [Selcuk University, Advanced Technology Research and Application Center (Turkey); Camli, Sevket Tolga, E-mail: tolgacamli@gmail.com [Biyotez Machinery Chemistry R& D Co. Ltd. (Turkey); Yavuz, Mustafa Selman, E-mail: selmanyavuz@selcuk.edu.tr [Selcuk University, Metallurgy and Materials Engineering (Turkey)

2014-12-15

Poly(methyl methacrylate) nanoparticles containing 4-vinylphenyl boronic acid were synthesized in one pot by surfactant-free emulsion polymerization. The nanoparticles were characterized by scanning electron microscopy and dynamic light scattering. Boron content in the nanoparticles was confirmed by electron-dispersive X-ray spectroscopy. In polymerization process, several co-monomer ratios were studied in order to obtain optimum nanoparticle size. Average hydrodynamic diameter and polydispersity index of nanoparticles versus variation of acetone percentage in the solvent mixture and total monomer concentration were investigated. The effect of boronic acid concentration in the monomer mixture on nanoparticle size and size distribution was also reported. Without further functionalization to the nanoparticles, the catechol dye, alizarin red S, was bound to boronic acid-containing nanoparticles. These nanoparticles behave as a nanosensor by which glucose or fructose can be easily detected. Dye-containing nanoparticles were undertaken displacement reaction by glucose or fructose. The glucose or fructose content was also monitored by UV–Visible spectrophotometer. Furthermore, cytotoxicity studies of boronic acid-carrying poly(methyl methacrylate) nanoparticles were carried out in 3T3 cells, which showed no toxicity effect on the cells.

One-pot synthesis of biocompatible boronic acid-functionalized poly(methyl methacrylate) nanoparticles at sub-100 nm scale for glucose sensing

International Nuclear Information System (INIS)

Sakalak, Huseyin; Ulasan, Mehmet; Yavuz, Emine; Camli, Sevket Tolga; Yavuz, Mustafa Selman

2014-01-01

Poly(methyl methacrylate) nanoparticles containing 4-vinylphenyl boronic acid were synthesized in one pot by surfactant-free emulsion polymerization. The nanoparticles were characterized by scanning electron microscopy and dynamic light scattering. Boron content in the nanoparticles was confirmed by electron-dispersive X-ray spectroscopy. In polymerization process, several co-monomer ratios were studied in order to obtain optimum nanoparticle size. Average hydrodynamic diameter and polydispersity index of nanoparticles versus variation of acetone percentage in the solvent mixture and total monomer concentration were investigated. The effect of boronic acid concentration in the monomer mixture on nanoparticle size and size distribution was also reported. Without further functionalization to the nanoparticles, the catechol dye, alizarin red S, was bound to boronic acid-containing nanoparticles. These nanoparticles behave as a nanosensor by which glucose or fructose can be easily detected. Dye-containing nanoparticles were undertaken displacement reaction by glucose or fructose. The glucose or fructose content was also monitored by UV–Visible spectrophotometer. Furthermore, cytotoxicity studies of boronic acid-carrying poly(methyl methacrylate) nanoparticles were carried out in 3T3 cells, which showed no toxicity effect on the cells

Effect of nanosized silica in poly(methyl methacrylate)-lithium bis(trifluoromethanesulfonyl)imide based polymer electrolytes

Energy Technology Data Exchange (ETDEWEB)

Ramesh, S.; Lu, Soon-Chien [Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Setapak, 53300 Kuala Lumpur (Malaysia)

2008-12-01

The effect of nanosized silica when incorporated in polymer electrolytes is analyzed by means of Fourier transform infrared (FTIR) spectroscopy, conductivity and thermal properties. Nanocomposite polymer electrolytes are synthesized by the dispersion of nanosized silica (SiO{sub 2}), up to 10 wt.% maximum, into a matrix formed by poly(methyl methacrylate) (PMMA) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The highest conductivity is 2.44 x 10{sup -6} S cm{sup -1} at room temperature, with 4 wt.% of silica added. The FTIR spectra show evidence of complexation between PMMA, LiTFSI and SiO{sub 2}. The addition of silica to the polymer electrolytes also improves the thermal stability and the ability to retain conductivity over time. (author)

The formation of hollow poly(methyl methacrylate)/multiwalled carbon nanotube nanocomposite cylinders by microwave irradiation

International Nuclear Information System (INIS)

Wang Huan; Hu Xijun; Ka Ming Ng; Feng Jiyun

2009-01-01

Poly(methyl methacrylate) (PMMA)/multiwalled carbon nanotube (MWCNT) nanocomposite particles with 1, 2 and 4 wt% of MWCNTs were prepared by mechanical grinding of PMMA and MWCNT powders in a mortar at room temperature. Both scanning electron microscopy and Raman scattering characterizations revealed that these nanocomposite particles consist of a PMMA core and a MWCNT shell. The PMMA/MWCNT nanocomposite particles were used to fabricate the corresponding nanocomposites in the form of a hollow cylinder with various diameters and heights under 700 W microwave irradiation within 1 min. A mechanism for the fast microwave assisted forming process is proposed. These experimental results may lead to a new technology for forming hollow polymeric articles that is different from the conventional injection and blowing process.

Characterization of polar organosulfates in secondary organic aerosol from the unsaturated aldehydes 2-E-pentenal, 2-E-hexenal, and 3-Z-hexenal

Data.gov (United States)

U.S. Environmental Protection Agency — We show in the present study that the unsaturated aldehydes, 2-E-pentenal, 2-E-hexenal and 3-Z-hexenal, are biogenic volatile organic compound (BVOC) precursors for...

Detection of DNA and poly-l-lysine using CVD graphene-channel FET biosensors

International Nuclear Information System (INIS)

Kakatkar, Aniket; Craighead, H G; Abhilash, T S; Alba, R De; Parpia, J M

2015-01-01

A graphene channel field-effect biosensor is demonstrated for detecting the binding of double-stranded DNA and poly-l-lysine. Sensors consist of chemical vapor deposition graphene transferred using a clean, etchant-free transfer method. The presence of DNA and poly-l-lysine are detected by the conductance change of the graphene transistor. A readily measured shift in the Dirac voltage (the voltage at which the graphene’s resistance peaks) is observed after the graphene channel is exposed to solutions containing DNA or poly-l-lysine. The ‘Dirac voltage shift’ is attributed to the binding/unbinding of charged molecules on the graphene surface. The polarity of the response changes to positive direction with poly-l-lysine and negative direction with DNA. This response results in detection limits of 8 pM for 48.5 kbp DNA and 11 pM for poly-l-lysine. The biosensors are easy to fabricate, reusable and are promising as sensors of a wide variety of charged biomolecules. (paper)

(E)-4-Methyl-N-((quinolin-2-yl)ethylidene)aniline as ligand for IIB supramolecular complexes: synthesis, structure, aggregation-induced emission enhancement and application in PMMA-doped hybrid material.

Science.gov (United States)

Wang, Ani; Fan, Ruiqing; Dong, Yuwei; Chen, Wei; Song, Yang; Wang, Ping; Hao, Sue; Liu, Zhigang; Yang, Yulin

2016-12-20

Judicious structural design employing 2-quinolinecarboxaldehyde and 4-methylaniline was used to generate the Schiff base ligand (E)-4-methyl-N-((quinolin-2-yl)ethylidene)aniline (L). Five IIB complexes, namely, [ZnLCl 2 ] (1), [ZnL(NO 3 ) 2 ] (2), [ZnL(OAc) 2 ] 3 (3), [CdL(OAc) 2 ] 3 (4), and [HgLCl 2 ] (5) have been synthesized based on L. Single-crystal X-ray diffraction analysis indicates that complexes 1, 3 and 4 exhibit 3D networks, whereas 2 and 5 form 2D layers and 1D chains, respectively. TD-DFT calculations show a good correlation with the UV-vis absorption assigned to π → π* intraligand transitions. Furthermore, complexes 1-5 displayed strong greenish luminescent emissions (518-524 nm) in the aggregate state but weak emissions in solution (aggregation-induced emission enhancement), which may be due to the existence of C-HCl/O hydrogen bonding and ππ stacking interactions, resulting in restriction of intramolecular rotation (RIR). Variable-concentration 1 H NMR studies suggested that the aggregates undergo intramolecular changes in conformation due to intermolecular interactions. Moreover, the emission intensity and lifetime exhibited obvious increases induced by mechanical grinding and temperature reduction, which were also attributed to AIEE properties. Subsequently, complex 1 was incorporated into poly(methyl methacrylate) (PMMA), whereby 1-PMMA exhibited enhanced emission intensity (20-fold increase in comparison with that of 1), which offers opportunities for use in plastic greenhouses to increase leaf photosynthesis.

DPPC/poly(2-methyl-2-oxazoline)-grad-poly(2-phenyl-2-oxazoline) chimeric nanostructures as potential drug nanocarriers

Energy Technology Data Exchange (ETDEWEB)

Pippa, Natassa [Faculty of Pharmacy, National and Kapodistrian University of Athens, Department of Pharmaceutical Technology (Greece); Kaditi, Eleni; Pispas, Stergios [Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation (Greece); Demetzos, Costas, E-mail: demetzos@pharm.uoa.gr [Faculty of Pharmacy, National and Kapodistrian University of Athens, Department of Pharmaceutical Technology (Greece)

2013-06-15

In this study, we report on the self assembly behavior and on stability studies of mixed (chimeric) nanosystems consisting of dipalmitoylphosphatidylcholine (DPPC) and poly(2-methyl-2-oxazoline)-grad-poly(2-phenyl-2-oxazoline) (MPOx) gradient copolymer in aqueous media and in fetal bovine serum (FBS). A gamut of light scattering techniques and fluorescence spectroscopy were used in order to extract information on the size and morphological characteristics of the nanoassemblies formed, as a function of gradient block copolymer content, as well as temperature. The hydrodynamic radii (R{sub h}) of nanoassemblies decreased in the process of heating up to 50 Degree-Sign C, while the fractal dimension (d{sub f}) values, also increased. Indomethacin was successfully incorporated into these chimeric nanocarriers. Drug release was depended on the components ratio. The present studies show that there are a number of parameters that can be used in order to alter the properties of chimeric nanosystems, and this is advantageous to the development of 'smart' nanocarriers for drug delivery.

Preparation of PLLA/PMMA and PLLA/PS binary blend nanoparticles by incorporation of PLLA in methyl methacrylate or styrene miniemulsion homopolymerization

Directory of Open Access Journals (Sweden)

Luana Becker Peres

2015-02-01

Full Text Available Miniemulsion homopolymerization reactions of methyl methacrylate (MMA and styrene (STY using poly(L-lactide as co-stabilizer were carried out in order to prepare poly(L-lactide/poly(methyl methacrylate (PLLA/PMMA and poly(L-lactide/polystyrene (PLLA/PS binary blend nanoparticles. The effect of PLLA concentration on methyl methacrylate (MMA and styrene (STY homopolymerization reactions was evaluated. It was found that the incorporation of PLLA resulted on acceleration of MMA and STY homopolymerization reactions and led to a molar mass increase of up to 70% for PS in PLLA/PS blend nanoparticles in relation to those prepared without PLLA, which can be attributed to an increase of reaction loci viscosity (gel effect. PLLA also acted as an efficient co-stabilizer, since it was able to retard diffusional degradation of droplets when no other kind of co-stabilizer was used. Two isolated Tgs were found in both PLLA/PMMA and PLLA/PS blend nanoparticles which can be associated to blend immiscibility. TEM images corroborate these results, suggesting that immiscible PLLA/PMMA and PLLA/PS blend nanoparticles could be formed with two segregated phases and core-shell morphology.

Measuring urinary N-acetyl-S-(4-hydroxy-2-methyl-2-buten-1-yl)-L-cysteine (IPMA3) as a potential biomarker of isoprene exposure.

Science.gov (United States)

Alwis, K Udeni; Bailey, T Liz; Patel, Dhrusti; Wang, Liqun; Blount, Benjamin C

2016-10-19

Isoprene, the 2-methyl analog of 1,3-butadiene, is identified as a possible human carcinogen by the International Agency for Research on Cancer (IARC). Isoprene is ubiquitous in the environment with numerous natural and anthropogenic sources. Tobacco smoke is the main exogenous source of isoprene exposure in indoor environments. Among smoke constituents, isoprene is thought to contribute significantly to cancer risk; however, no selective urinary biomarkers of isoprene exposure have been identified for humans. In this manuscript, we measured the minor isoprene metabolite IPMA1 (mixture of N-acetyl-S-(1-[hydroxymethyl]-2-methyl-2-propen-1-yl)-L-cysteine and N-acetyl-S-(2-hydroxy-3-methyl-3-buten-1-yl)-L-cysteine), and we identified IPMA3 (N-acetyl-S-(4-hydroxy-2-methyl-2-buten-1-yl)-L-cysteine) as a major isoprene metabolite and novel isoprene exposure biomarker for humans. Urinary isoprene metabolites were measured using ultra high performance liquid chromatography coupled with electrospray ionization triple quad tandem mass spectrometry (UPLC/ESI-MSMS). The detection rates of IPMA1 and IPMA3 are <20% and 82%, respectively. The selectivity and abundance of IPMA3 make it a useful urinary biomarker of isoprene exposure. The limit of detection of IPMA3 in urine was 0.5 ng mL -1 . IPMA3 was stable under different storage temperatures and following ten freeze-thaw cycles. The average recovery of urine spiked with IPMA3 at three different levels was 99%. IPMA3 was measured in urine samples received from 75 anonymous subjects; the median (25th percentile, 75th percentile) IPMA3 level in smokers was 36.2 (18.2, 56.8) ng mL -1 and non-smokers 2.31 (2.31, 4.38) ng mL -1 . Application of this method to large population studies will help to characterize isoprene exposure and assess potential health impact. Published by Elsevier B.V.

Electro-oxidation of chlorophenols on poly(3,4-ethylenedioxythiophene)-poly(styrene sulphonate) composite electrode

International Nuclear Information System (INIS)

Pigani, L.; Musiani, M.; Pirvu, C.; Terzi, F.; Zanardi, C.; Seeber, R.

2007-01-01

The electrochemical behaviour of chlorinated phenols on Pt/poly(3,4-ethylenedioxy)thiophene,LiClO 4 and on Pt/poly(3,4-ethylenedioxy)thiophene,poly(sodium-4-styrenesulphonate) electrodes has been investigated in phosphate buffer solution. Poly(sodium-4-styrenesulphonate) exerts remarkable effect against the electrode fouling induced by oxidation of chlorophenols, allowing us to record the relevant anodic response even after repeated potential cycles. Hypotheses about the role exerted by poly(sodium 4-styrenesulphonate) are made, on the basis of evidences provided by several techniques, such as cyclic voltammetry, electrochemical impedance spectroscopy, electrochemical microgravimetry and atomic force microscopy. Thanks to the fact that different chlorophenols show differences in the voltammetric responses, depending on number and position of the chloro substituents on the aromatic ring, applications of the modified electrode in the analysis of mixtures of chlorinated phenols are possible

Gas-Foamed Scaffold Gradients for Combinatorial Screening in 3D

Directory of Open Access Journals (Sweden)

Joachim Kohn

2012-03-01

Full Text Available Current methods for screening cell-material interactions typically utilize a two-dimensional (2D culture format where cells are cultured on flat surfaces. However, there is a need for combinatorial and high-throughput screening methods to systematically screen cell-biomaterial interactions in three-dimensional (3D tissue scaffolds for tissue engineering. Previously, we developed a two-syringe pump approach for making 3D scaffold gradients for use in combinatorial screening of salt-leached scaffolds. Herein, we demonstrate that the two-syringe pump approach can also be used to create scaffold gradients using a gas-foaming approach. Macroporous foams prepared by a gas-foaming technique are commonly used for fabrication of tissue engineering scaffolds due to their high interconnectivity and good mechanical properties. Gas-foamed scaffold gradient libraries were fabricated from two biodegradable tyrosine-derived polycarbonates: poly(desaminotyrosyl-tyrosine ethyl ester carbonate (pDTEc and poly(desaminotyrosyl-tyrosine octyl ester carbonate (pDTOc. The composition of the libraries was assessed with Fourier transform infrared spectroscopy (FTIR and showed that pDTEc/pDTOc gas-foamed scaffold gradients could be repeatably fabricated. Scanning electron microscopy showed that scaffold morphology was similar between the pDTEc-rich ends and the pDTOc-rich ends of the gradient. These results introduce a method for fabricating gas-foamed polymer scaffold gradients that can be used for combinatorial screening of cell-material interactions in 3D.

Cellulose nanocrystals as a reinforcing material for electrospun poly(methyl methacrylate) fibers: formation, properties and nanomechanical characterization

Science.gov (United States)

Hong Dong; Kenneth E. Strawhecker; James A. Snyder; Joshua A. Orlicki; Richard S. Reiner; Alan W. Rudie

2012-01-01

Uniform fibers composed of poly(methyl methacrylate) (PMMA) reinforced with progressively increasing contents of cellulose nanocrystals (CNCs), up to 41 wt% CNCs, have been successfully produced by electrospinning. The morphological, thermal and nanomechanical properties of the composite sub-micron fibers were investigated. The CNCs derived from wood pulp by sulfuric...

Lactic acid production by irradiated Bacillus NF17 and poly-L-lactate biopolymer formation

International Nuclear Information System (INIS)

Tongpim, Saowanit; Poonsawat, Choosak; Khansawai, Paveena; Piadaeng, Nattaya

2006-09-01

This study was conducted to manipulate the thermo tolerant, lactic acid-producing bacteria, Bacillus coagulans strain NF 1 7, in the production of L-lactic acid and a bio polymer: poly-L-lactate. The bacterial isolate NF 1 7 kept in the culture collection of Khon Kaen University and could tolerate high temperature and produce lactic acid, was employed in this research work. Cell suspension of isolate NF 1 7 was exposed to gamma irradiation at various doses (1-5 KGy). The irradiated survivors were screened on the basis of forming larger colonies and clear zones than the parent strain NF 1 7 when grown on Glucose-Yeast extract-Peptone (GYP) containing CaCO 3 . We obtained 55 effective isolates which the isolate L5I2-14(5), designated as K 1 4, was chosen together with the parent strain NF 1 7 for fermentation experiments. Each bacterial strain was inoculated into GYP broth and incubated statically at 50 o C with daily pH neutralization. After 5 days of incubation, the isolate K 1 4 and NF 1 7 produced 9.71 g/l and 7.42 g/l of L-lactic acid, respectively with a small amount of D-lactic acid. Lactic acid production from sugar cane molasses by batch fermentation of Bacillus Sp. K 1 4 was carried out in a 7 l jar fermentor containing 5 l of fermentation medium. It was found that 20% molasses with the agitation speed of 100 rpm gave the highest yield of lactic acid. Poly-L-lactic acid was chemically polymerized by bulk polymerization process at 140 o C under 40 mmHg conditions. We could obtain the off-white polymer in a small amount of powder form. Improvement the yield of poly-L-lactic acid would be achieved by using polyisoprene-g-polyvinyl monomer to separate lactic acid from the fermenting liquid prior to polymerization processes

Fabrication and characterization of novel multilayered structures by stereocomplexion of poly(D-lactic acid)/poly(L-lactic acid) and self-assembly of polyelectrolytes

OpenAIRE

Elena Dellacasa; Li Zhao; Gesheng Yang; Laura Pastorino; Gleb B. Sukhorukov

2016-01-01

The enantiomers poly(D-lactic acid) (PDLA) and poly(L-lactic acid) (PLLA) were alternately adsorbed directly on calcium carbonate (CaCO3) templates and on poly(styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) multilayer precursors in order to fabricate a novel layer-by-layer (LBL) assembly. A single layer of poly(L-lysine) (PLL) was used as a linker between the (PDLA/PLLA)n stereocomplex and the cores with and without the polymeric (PSS/PAH)n/PLL multilayer precursor (PEM). N...

Morphological comparison of PVA scaffolds obtained by gas foaming and microfluidic foaming techniques.

Science.gov (United States)

Colosi, Cristina; Costantini, Marco; Barbetta, Andrea; Pecci, Raffaella; Bedini, Rossella; Dentini, Mariella

2013-01-08

In this article, we have exploited a microfluidic foaming technique for the generation of highly monodisperse gas-in-liquid bubbles as a templating system for scaffolds characterized by an ordered and homogeneous porous texture. An aqueous poly(vinyl alcohol) (PVA) solution (containing a surfactant) and a gas (argon) are injected simultaneously at constant flow rates in a flow-focusing device (FFD), in which the gas thread breaks up to form monodisperse bubbles. Immediately after its formation, the foam is collected and frozen in liquid nitrogen, freeze-dried, and cross-linked with glutaraldehyde. In order to highlight the superior morphological quality of the obtained porous material, a comparison between this scaffold and another one, also constituted of PVA but obtained with a traditional gas foaming technique, was carried out. Such a comparison has been conducted by analyzing electron microscopy and X-ray microtomographic images of the two samples. It turned out that the microfluidic produced scaffold was characterized by much more uniform porous texture than the gas-foaming one as witnessed by narrower pore size, interconnection, and wall thickness distributions. On the other side, scarce pore interconnectivity, relatively low pore volume, and limited production rate represent, by now, the principal disadvantages of microfluidic foaming as scaffold fabrication method, emphasizing the kind of improvement that this technique needs to undergo.

Preparation of poly (methyl methacrylate)/nanometer calcium carbonate composite by in-situ emulsion polymerization

Institute of Scientific and Technical Information of China (English)

史建明; 包永忠; 黄志明; 翁志学

2004-01-01

Methyl methacrylate (MMA) emulsion polymerization in the presence of nanometer calcium carbonate (nano-CaCO3) surface modified with (-methacryloxypropyltrimethoxysilane (MPTMS) was carried out to prepare poly (methyl methacrylate) (PMMA)/nano-CaCO3 composite. The reaction between nano-CaCO3 and MPTMS, and the grafting of PMMA onto nano-CaCO3 were confirmed by infrared spectrum. The grafting ratio and grafting efficiency of PMMA on nano-CaCO3 modified with MPTMS were much higher than that on nano-CaCO3 modified with stearic acid. The grafting ratio of PMMA increased as the weight ratio between MMA and nano-CaCO3 increased, while the grafting efficiency of PMMA decreased. Transmission electron micrograph showed that nano-CaCO3 covered with PMMA was formed by in-situ emulsion polymerization.

Foam for combating mine fires

Energy Technology Data Exchange (ETDEWEB)

1989-09-01

The application of foam in dealing with underground fire is well known due to its smothering action by cutting off air feed to burning fuel as well as acting as coolant. Besides plugging air feed to fire, water could be virtually reached to the fire affected areas much beyond the jet range as underground galleries with low roof restrict jet range of water. This method also enables a closer approach of a fire fighting team by isolating the toxic gases and smoke with a foam plug. The paper describes the development of high expansion foam composition and its application technology in order that foam plug method can be suitably utilized for combating mine fires in India. Three compositions were recommended for generation of high expansion foam: (a) 0.5% sodium/ammonium lauryl sulphate, 0.15 to 0.2% sodium carboxy methyl cellulose, 0.1% booster; (b) 0.5% sodium/ammonium lauryl sulfate, 0.12 to 0.15% alkaline solution of gum arabic, 0.1 to 0.2% ferrous gluconate; and (c) 0.35% sodium/ammonium lauryl sulfate, 0.20% booster, 0.2% xylene sulfonate.

Self-degradation of tissue adhesive based on oxidized dextran and poly-L-lysine.

Science.gov (United States)

Matsumura, Kazuaki; Nakajima, Naoki; Sugai, Hajime; Hyon, Suong-Hyu

2014-11-26

We have developed a low-toxicity bioadhesive based on oxidized dextran and poly-L-lysine. Here, we report that the mechanical properties and degradation of this novel hydrogel bioadhesive can be controlled by changing the extent of oxidation of the dextran and the type or concentration of the anhydride species in the acylated poly-L-lysine. The dynamic moduli of the hydrogels can be controlled from 120 Pa to 20 kPa, suggesting that they would have mechanical compatibility with various tissues, and could have applications as tissue adhesives. Development of the hydrogel color from clear to brown indicates that the reaction between the dextran aldehyde groups and the poly-L-lysine amino groups may be induced by a Maillard reaction via Schiff base formation. Degradation of the aldehyde dextran may begin by reaction of the amino groups in the poly-L-lysine. The gel degradation can be ascribed to degradation of the aldehyde dextran in the hydrogel, although the aldehyde dextran itself is relatively stable in water. The oxidized dextran and poly-L-lysine, and the degraded hydrogel showed low cytotoxicities. These findings indicate that a hydrogel consisting of oxidized dextran and poly-L-lysine has low toxicity and a well-controlled degradation rate, and has potential clinical applications as a bioadhesive. Copyright © 2014 Elsevier Ltd. All rights reserved.

Generation of Microcellular Biodegradable Polycaprolactone Foams in Supercritical Carbon Dioxide

Institute of Scientific and Technical Information of China (English)

Xu Qun; Ren Xian-wen; Chang Yu-ning; Yu Long; Wang Jing-wu

2004-01-01

Present now the application of microcellular polymeric materials in biomedical field is growing rapidly, as that of guided tissue regeneration and cell transplantation. As far as guided tissue regeneration is concerned, porous implants are used as size selective membrane to promote the growth of a special tissue in a healing site. Ideally, the implant should be inherently biocompatible,have well-defined cell size and be resorbable with appropriate biodegradation rates.Poly(a-caprolactone) (PCL) is a kind of materials suit for the demands above. PCL is biocompatible and biodegradable aliphatic polyester which is nontoxic for living organisms and bioresorbable after a period of implantation. Because of its unique combination of biocompatibility, permeability and biodegradability, PCL and some of its copolymer with lactides and glycolide have been widely applied in medicine as artificial skin, artificial bone and containers for sustained drug release.Goel and Beckman have reported a new method to generate microcellular poly(methy l methacrylate) foams in which the samples are saturated with CO2 under a series of supercritical (SC)conditions, and then the system is rapidly depressurized to atmospheric pressure at constant temperature. Unlike traditional methods, it reduces glass-transition temperature (Tg) of the mixture to below the experimental temperature rather than directly heat the system above Tg. In this process of nucleation, no phase separation occurs as well as no phase boundary meets, so the cellular structure of the foam can be retained better.In this work, we have generated PCL foams by using supercritical CO2. Because of the low glass transition temperature (Tg = -60 ℃) of PCL far below the ice point, the experimental temperature in our study is much higher than Tg, which is different from the studies by others before. A series of variable factors on the foam structure as saturation temperature, saturation pressure, saturation time and depressurization

Generation of sclerosant foams by mechanical methods increases the foam temperature.

Science.gov (United States)

Tan, Lulu; Wong, Kaichung; Connor, David; Fakhim, Babak; Behnia, Masud; Parsi, Kurosh

2017-08-01

Objective To investigate the effect of agitation on foam temperature. Methods Sodium tetradecyl sulphate and polidocanol were used. Prior to foam generation, the sclerosant and all constituent equipment were cooled to 4-25℃ and compared with cooling the sclerosant only. Foam was generated using a modified Tessari method. During foam agitation, the temperature change was measured using a thermocouple for 120 s. Results Pre-cooling all the constituent equipment resulted in a cooler foam in comparison with only cooling the sclerosant. A starting temperature of 4℃ produced average foam temperatures of 12.5 and 13.2℃ for sodium tetradecyl sulphate and polidocanol, respectively. It was also found that only cooling the liquid sclerosant provided minimal cooling to the final foam temperature, with the temperature 20 and 20.5℃ for sodium tetradecyl sulphate and polidocanol, respectively. Conclusion The foam generation process has a noticeable impact on final foam temperature and needs to be taken into consideration when creating foam.

40 CFR 721.7780 - Poly[oxy(methyl-1,2-ethane-diyl)], α,α′-(2,2-dimethyl-1,3-pro-pan-ediyl)bis[ω-(oxi-rany-me-thoxy)-.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Poly[oxy(methyl-1,2-ethane-diyl)], α,αâ²-(2,2-dimethyl-1,3-pro-pan-ediyl)bis[Ï-(oxi-rany-me-thoxy)-. 721.7780 Section 721.7780... Poly[oxy(methyl-1,2-ethane-diyl)], α,α′-(2,2-dimethyl-1,3-pro-pan-ediyl)bis[ω-(oxi-rany-me-thoxy)-. (a...

A Low Protein Binding Cationic Poly(2-oxazoline) as Non-Viral Vector

KAUST Repository

He, Zhijian

2015-04-02

© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Developing safe and efficient non-viral gene delivery systems remains a major challenge. We present a new cationic poly(2-oxazoline) (CPOx) block copolymer for gene therapy that was synthesized by sequential polymerization of non-ionic 2-methyl-2-oxazoline and a new 2-oxazoline monomer, 2-(N-methyl, N-Boc-amino)-methyl-2-oxazoline, followed by deprotection of the pendant secondary amine groups. Upon mixing with plasmid DNA (pDNA), CPOx forms small (diameter ≈80 nm) and narrowly dispersed polyplexes (PDI <0.2), which are stable upon dilution in saline and against thermal challenge. These polyplexes exhibited low plasma protein binding and very low cytotoxicity in vitro compared to the polyplexes of pDNA and poly(ethylene glycol)-b-poly(L-lysine) (PEG-b-PLL). CPOx/pDNA polyplexes at N/P = 5 bound considerably less plasma protein compared to polyplexes of PEG-b-PLL at the same N/P ratio. This is a unique aspect of the developed polyplexes emphasizing their potential for systemic delivery in vivo. The transfection efficiency of the polyplexes in B16 murine melanoma cells was low after 4 h, but increased significantly for 10 h exposure time, indicative of slow internalization of polyplexes. Addition of Pluronic P85 boosted the transfection using CPOx/pDNA polyplexes considerably. The low protein binding of CPOx/pDNA polyplexes is particularly interesting for the future development of targeted gene delivery.

Antiresonant guiding in a poly(methyl-methacrylate) hollow-core optical fiber

DEFF Research Database (Denmark)

Markos, Christos; Nielsen, Kristian; Bang, Ole

2015-01-01

Strong antiresonant reflecting optical waveguiding is demonstrated in a novel poly (methyl-methacrylate) (PMMA) hollow-core fiber. The transmission spectrum of the fiber was characterized using a supercontinuum source and it revealed distinct resonances with resonant dips as strong as ~20 d......B in the wavelength range 480-900 nm, where PMMA has low absorption. The total propagation loss of the fiber was measured to have a minimum of ~45 dB m-1 at around 500 nm. The thermal sensitivity of the fiber is 256 ± 16 pm °C-1, defined as the red-shift of the resonances per °C, which is three times higher than...... the sensitivity of polymer fiber Bragg gratings....

Multifunctional foaming agent to prepare aluminum foam with enhanced mechanical properties

Science.gov (United States)

Li, Xun; Liu, Ying; Ye, Jinwen; An, Xuguang; Ran, Huaying

2018-03-01

In this paper, CuSO4 was used as foaming agent to prepare close cell Aluminum foam(Al foam) at the temperature range of 680 °C ∼ 758 °C for the first time. The results show that CuSO4 has multifunctional such as, foaming, viscosity increasing, reinforcement in Al matrix, it has a wide decomposition temperature range of 641 °C ∼ 816 °C, its sustain-release time is 5.5 min at 758 °C. The compression stress and energy absorption of CuSO4-Al foam is 6.89 Mpa and 4.82 × 106 J m‑3(compression strain 50%), which are 77.12% and 99.17% higher than that of TiH2-Al foam at the same porosity(76% in porosity) due to the reinforcement in Al matrix and uniform pore dispersion.

Thermo-Responsive Complexes of c-Myc Antisense Oligonucleotide with Block Copolymer of Poly(OEGMA) and Quaternized Poly(4-Vinylpyridine).

Science.gov (United States)

Topuzogullari, Murat; Elalmis, Yeliz Basaran; Isoglu, Sevil Dincer

2017-04-01

Solution behavior of thermo-responsive polymers and their complexes with biological macromolecules may be affected by environmental conditions, such as the concentration of macromolecular components, pH, ion concentration, etc. Therefore, a thermo-responsive polymer and its complexes should be characterized in detail to observe their responses against possible environments under physiological conditions before biological applications. To briefly indicate this important issue, thermo-responsive block copolymer of quaternized poly(4-vinylpyridine) and poly(oligoethyleneglycol methyl ether methacrylate) as a potential nonviral vector has been synthesized. Polyelectrolyte complexes of this copolymer with the antisense oligonucleotide of c-Myc oncogene are also thermo-responsive but, have lower LCST (lower critical solution temperature) values compared to individual copolymer. LCST values of complexes decrease with molar ratio of macromolecular components and presence of salt. Dilution of solutions also affects solution behavior of complexes and causes a significant decrease in size and an increase in LCST, which indicates possible effects of severe dilutions in the blood stream. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mechanism of radiation-induced degradation of poly(methyl methacrylate)

International Nuclear Information System (INIS)

Ichikawa, Tsuneki; Oyama, Ken-ichi; Yoshida, Hiroshi

1995-01-01

ESR and gel permeation chromatographic measurements of poly(methyl methacrylate) γ-irradiated between 77 K and 300 K have been carried out to elucidate the mechanism of radiation-induced degradation of the polymer. It is revealed that the scission of the main chain is not taken place immediately after the absorption of radiation energy but is induced by the intramolecular radical conversion of the side-chain -COOCH 2 radical to the tertiary -CH 2 -C(CH 3 )- radical followed by the main-chain β-scission of the latter radical. The degradation is not taken place below 190 K, because the side-chain radical starts to convert only above 190 K. The residual monomer in the polymer reacts with the side-chain radical below 190 K to generate the stable propagating-type radical, so that the degradation is suppressed even after warming the polymer to the ambient temperature. (author)

Complete dechlorination of 2,4-dichlorophenol in aqueous solution on palladium/polymeric pyrrole-cetyl trimethyl ammonium bromide/foam-nickel composite electrode

Energy Technology Data Exchange (ETDEWEB)

Sun, Zhirong, E-mail: zrsun@bjut.edu.cn [College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124 (China); Wei, Xuefeng; Han, Yanbo; Tong, Shan [College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124 (China); Hu, Xiang, E-mail: huxiang99@163.com [College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

2013-01-15

Highlights: ► Pd/PPy-CTAB/foam-Ni electrode with high surface area and low Pd content was prepared. ► The composite electrode was applied to dechlorination of 2,4-DCP in aqueous solution. ► Complete dechlorination of 2,4-DCP was achieved with higher current efficiency. ► Removal efficiency kept 100% after 10 times dechlorination on the stable electrode. ► The electrochemically reductive activation energy was 25.8 kJ mol{sup −1} in this system. -- Abstract: The electrochemically reductive dechlorination of 2,4-dichlorophenol (2,4-DCP) in aqueous solution on palladium/polymeric pyrrole-cetyl trimethyl ammonium bromide/foam-nickel electrode (Pd/PPy-CTAB/foam-Ni electrode) was investigated in this paper. Pd/PPy-CTAB/foam-Ni electrode was prepared and characterized by cyclic voltammetry (CV), scanning electron microscope (SEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) adsorption and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The influences of some experimental factors such as the dechlorination current, dechlorination time and the initial pH on the removal efficiency and the current efficiency of 2,4-DCP dechlorination on Pd/PPy-CTAB/foam-Ni electrode were studied. Complete removal of 2,4-DCP was achieved and the current efficiency of 47.4% could be obtained under the conditions of the initial pH of 2.2, the dechlorination current of 5 mA and the dechlorination time of 50 min when the initial 2,4-DCP concentration was 100 mg L{sup −1}. The analysis of high performance liquid chromatography (HPLC) identified that the intermediate products were 2-chlorophenol (2-CP) and 4-chlorophenol (4-CP). The final products were mainly phenol. Its further reduction product cyclohexanone was also detected. The electrocatalytic dechlorination pathways of 2,4-DCP on Pd/PPy-CTAB/foam-Ni electrode were discussed. The stability of the electrode was favorable that it could keep dechlorination efficiency at 100% after having been reused

Synthesis and Properties of Shape Memory Poly(γ-Benzyl-l-Glutamate-b-Poly(Propylene Glycol-b-Poly(γ-Benzyl-l-Glutamate

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Lin Gu

2017-12-01

Full Text Available Shape memory polymers (SMPs have attracted much attention as an important class of stimuli-responsive materials for biomedical applications. For SMP-based biomaterials, in addition to suitable shape recovery performances, their mechanical properties, biodegradability, biocompatibility, and sterilizability needs to be considered. Polypeptides can satisfy the requirements outlined above. However, there are few reports on shape memory polypeptides. In this paper, shape memory poly(γ-benzyl-l-glutamate (PBLG-PPG-PBLG was synthesized by ring-opening polymerization of γ-benzyl-l-glutamate-N-carboxyanhydrides (BLG-NCA with poly(propylene glycol bis(2-aminopropyl ether as the macroinitiator. 1H Nuclear Magnetic Resonance (NMR and Fourier-Transform Infrared Spectroscopy (FTIR were used to characterize the structure of the obtained PBLG-PPG-PBLG. The FTIR analysis showed that PBLG-PPG-PBLG has α-helical and β-sheet structures. PBLG-PPG-PBLG has good shape memory properties, its shape recovery time is less than 120 s, and its shape recovery rate is 100%. In this study, we reported a simple synthetic method to obtain intelligent polypeptide materials, which will be used in many biomedical applications.

Neuropathic Pain Following Poly-L-Lactic Acid (Sculptra) Injection.

Science.gov (United States)

Vrcek, Ivan; El-Sawy, Tarek; Chou, Eva; Allen, Theresa; Nakra, Tanuj

Injectable fillers have become a prevalent means of facial rejuvenation and volume expansion. While typically well tolerated, serious complications have been reported. The authors present a case in which an otherwise healthy female with a history of multiple filler injections including poly-L-lactic acid, developed 3 weeks of neuropathic pain in the left temporal fossa following injection. To the best of the authors knowledge, neuropathic pain has not been reported as a complication following poly-L-lactic acid injection. The patient was treated with an injection of steroid and long-acting anesthetic with resolution of symptoms.

Electrodeposition of palladium and reduced graphene oxide nanocomposites on foam-nickel electrode for electrocatalytic hydrodechlorination of 4-chlorophenol

International Nuclear Information System (INIS)

Liu, Yong; Liu, Lan; Shan, Jun; Zhang, Jingdong

2015-01-01

Highlights: • Pd and reduced graphene oxide are deposited on foam-Ni via electrodeposition. • Pd particles supported on RGO possess large active surface area. • Pd/RGO/foam-Ni shows high electrocatalytic activity for dechlorination of 4-CP. • 100% 4-CP can be removed on Pd/RGO/foam-Ni under optimum ECH conditions. - Abstract: A high-performance palladium (Pd) and reduced graphene oxide (RGO) composite electrode was prepared on foam-nickel (foam-Ni) via two-step electrodeposition processes. The scanning electron microscopic (SEM) observation showed that the obtained Pd/RGO/foam-Ni composite electrode displayed a uniform and compact morphology. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopic (XPS) analysis confirmed the successful deposition of Pd and RGO on nickel substrate. The cyclic voltammetric (CV) measurements indicated that the presence of RGO greatly enhanced the active surface area of Pd particles deposited on foam-Ni. The as-deposited Pd/RGO/foam-Ni electrode was applied to electrocatalytic hydrodechlorination (ECH) of 4-chlorophenol (4-CP). Various factors influencing the dechlorination of 4-CP such as dechlorination current, initial concentration of 4-CP, Na 2 SO 4 concentration and initial pH were systematically investigated. The thermodynamic analysis showed that the dechlorination reaction of 4-CP at different temperatures followed the first-order kinetics and the activation energy for 4-CP dechlorination on Pd/RGO/foam-Ni electrode was calculated to be 51.96 kJ mol −1 . Under the optimum conditions, the dechlorination efficiency of 4-CP could reach 100% after 60-min ECH treatment. Moreover, the prepared Pd/RGO/foam-Ni composite electrode showed good stability for recycling utilization in ECH of 4-CP

Extraction behavior of uranium(VI) with polyurethane foam

International Nuclear Information System (INIS)

Tingchia Huang; Donghwang Chen; Muchang Shieh; Chingtsven Huang

1992-01-01

The extraction of uranium(VI) from aqueous solution with polyether-based polyurethane (PU) foam was studied. The effects of the kinds and concentrations of nitrate salts, uranium(VI) concentration, temperature, nitric acid concentration, pH, the content of poly(ethylene oxide) in the polyurethane foam, and the ratio of PU foam weight and solution volume on the extraction of uranium(VI) were investigated. The interferences of fluoride and carbonate ions on the extraction of uranium(VI) were also examined, and methods to overcome both interferences were suggested. It was found that no uranium was extracted in the absence of a nitrate salting-out agent, and the extraction behaviors of uranium(IV) with polyurethane foam could be explained in terms of an etherlike solvent extraction mechanism. In addition, the percentage extraction of a multiple stage was also estimated theoretically

Immobilization of Acidithiobacillus ferrooxidans on sulfonated microporous poly(styrene-divinylbenzene) copolymer with granulated activated carbon and its use in bio-oxidation of ferrous iron.

Science.gov (United States)

Koseoglu-Imer, Derya Yuksel; Keskinler, Bulent

2013-01-01

The immobilization efficiencies of Acidithiobacillus ferrooxidans cells on different immobilization matrices were investigated for biooxidation of ferrous iron (Fe(2+)) to ferric iron (Fe(3+)). Six different matrices were used such as the polyurethane foam (PUF), granular activated carbon (GAC), raw poly(styrene-divinylbenzene) copolymer (rawSDVB), raw poly(styrene-divinylbenzene) copolymer with granular activated carbon (rawSDVB-GAC), sulfonated poly(styrene-divinylbenzene) copolymer (sulfSDVB) and sulfonated poly(styrene-divinylbenzene) copolymer with granular activated carbon (sulfSDVB-GAC). The sulfSDVB-GAC polymer showed the best performance for Fe(2+) biooxidation. It was used at packed-bed bioreactor and the kinetic parameters were obtained. The highest Fe(2+) biooxidation rate (R) was found to be 4.02 g/L h at the true dilution rate (Dt) of 2.47 1/h and hydraulic retention time (τ) of 0.4 h. The sulfSDVB-GAC polymer was used for the first time as immobilization material for A. ferrooxidans for Fe(2+) biooxidation. Copyright © 2012 Elsevier B.V. All rights reserved.

Comparison of immobilized poly-L-aspartic acid and poly-L-glutamic acid for chelation of metal cations

International Nuclear Information System (INIS)

Malachowski, Lisa; Holcombe, James A.

2004-01-01

Poly-L-aspartic acid (PLAsp) and poly-L-glutamic acid (PLGlu) were individually immobilized onto controlled pore glass (CPG) and compared according to their metal-binding capabilities in a solution of pH 7.0. The metal-binding capacities were calculated through the analysis of breakthrough curves generated by monitoring the metal concentrations on a flow injection-flame atomic absorption system. Capacities for individual metals were comparable and in the order of Cu 2+ >> Pb 2+ > Ni 2+ ∼ Cd 2+ > Co 2+ > Mn 2+ >> Na + . Elemental combustion analysis yielded polymer coverage on the CPG of approximately 4 x 10 12 to 5 x 10 12 chains/cm 2 , when average chain lengths were used in the calculations. Formation constants and site capacities of both polymers for Cd 2+ were determined through equilibrium and breakthrough studies. The maximum log K values for the strong sites were determined to be ∼13 for both PLAsp and for PLGlu. Additionally, the metal selectivity of PLAsp and PLGlu was evaluated when breakthrough curves were run with several metals present in solution at one time. Both polymers showed selectivities in the order of their single metal-binding capacities, i.e., Cu 2+ > Pb 2+ > Ni 2+ ∼ Cd 2+ . Both polymers exhibited similar binding trends and binding strengths for all of the metals studied. This likely reflects the absence of a predetermined tertiary structure of the polymers on the surface and the relatively high residue-per-metal ratio (∼20:1), which places less stringent requirements on the steric hindrance between the side chains and the resultant 'wrapping' of the peptide around the metal

MgAl_2O_4 foams obtained by combustion synthesis

International Nuclear Information System (INIS)

Moraes, G.G.; Rosa, M.A.; Kronbauer, D.P.; Pozzobom, I.F.; Fernandes, C.P.; Oliveira, A.P. Novaes de

2014-01-01

This work aims to study magnesium aluminate (MgAl_2O_4) ceramic foams obtained by combustion synthesis in solution without the need of surfactants to stabilize bubbles. The precursors, Al(NO_3)_3_.9H_2O and Mg(NO_3)_2_.6H_2_O, dispersed in distilled water (20 wt%) were magnetically stirred under heating (70°C). At the beginning of the reaction, a fuel composed by a mixture of residual glycerins from the production of biodiesel was added. The foams were produced by controlling the stirring speed and temperature. The applied thermal cycle to consolidate the foams consisted of heating at 1°C/min to 600°C/120 min and subsequently raising the temperature at 10°C/min to 1600°C/120 min. The obtained materials were characterized by SEM,TEM and from tomographic images. The results showed that the obtained magnesium aluminate foams have a high porosity (97%), a high connectivity and pore sizes (diameters) between 30 and 1200 μm. (author)

Study of the nitration of poly(4,4'-diphenylether-1,3,4-oxadiazole) to gas permeation

International Nuclear Information System (INIS)

Carneiro, Candida da C.; Sena, Maria Eugenia R. de; Borges, Cristiano P.

2001-01-01

This work is a systematic modification of the poly(4,4'-diphenylether-1,3,4-oxadiazole), POD-DPE, through of the substitution of atoms of hydrogen for NO 2 groups, in aromatic rings. The presence of these groups increases the spacing among the polymer chains and decreases the packing, that promotes a larger free volume for diffusion of the permeable molecules. The nitration of POD-DPE was accomplished using N-methyl-pyrrolidine as solvent, ammonium nitrate and trifluor acetic anhydride as nitrating agent and triethylamine to finish the reaction. The influence of reaction conditions was investigated by characterization of the modified polymer. The characterization was carried out by thermal analysis (TMA and TGA), viscosity, conductivity, NMR and permeability. The viscosity analysis showed that the chemical stability of the nitrate material decreased. The results also indicated that the nitration of the aromatic rings takes to a significant reduction in Tg and little affects the polymer degradation temperature. The characterization by gas permeation also presented an increase in the permeability and selectivity of the polymer. (author)

Structural characterization of a poly(methacrylic acid)-poly(methyl methacrylate) copolymer by nuclear magnetic resonance and mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Giordanengo, Remi [Universites Aix-Marseille I, II et III - CNRS, UMR 6264: Laboratoire Chimie Provence, Spectrometries Appliquees a la Chimie Structurale, F-13397 Marseille (France); Viel, Stephane [Aix-Marseille Universite - CNRS, UMR 6263: Institut des Sciences Moleculaires de Marseille, Chimiometrie et Spectrometries, F-13397 Marseille (France); Hidalgo, Manuel; Allard-Breton, Beatrice [ARKEMA, Centre de Recherche Rhone Alpes, Rue Henri Moissan, F-69493 Pierre-Benite (France); Thevand, Andre [Universites Aix-Marseille I, II et III - CNRS, UMR 6264: Laboratoire Chimie Provence, Spectrometries Appliquees a la Chimie Structurale, F-13397 Marseille (France); Charles, Laurence, E-mail: laurence.charles@univ-provence.fr [Universites Aix-Marseille I, II et III - CNRS, UMR 6264: Laboratoire Chimie Provence, Spectrometries Appliquees a la Chimie Structurale, F-13397 Marseille (France)

2009-11-03

Mass spectrometry (MS) and nuclear magnetic resonance (NMR) have been combined to achieve the complete microstructural characterization of a poly(methacrylic acid)-poly(methyl methacrylate) (PMAA-PMMA) copolymer synthesized by nitroxide-mediated polymerization. Various PMAA-PMMA species could be identified which mainly differ in terms of terminaisons. {sup 1}H and {sup 13}C NMR experiments revealed the structure of the end-groups as well as the proportion of each co-monomer in the copolymers. These end-group masses were further confirmed from m/z values of doubly charged copolymer anions detected in the single stage mass spectrum. In contrast, copolymer composition derived from MS data was not consistent with NMR results, obviously due to strong mass bias well known to occur during electrospray ionization of these polymeric species. Tandem mass spectrometry could reveal the random nature of the copolymer based on typical dissociation reactions, i.e., water elimination occurred from any two contiguous MAA units while MAA-MMA pairs gave rise to the loss of a methanol molecule. Polymer backbone cleavages were also observed to occur and gave low abundance fragment ions which allowed the structure of the initiating end-group to be confirmed.

Histone H4 Lysine 20 methylation

DEFF Research Database (Denmark)

Jørgensen, Stine; Schotta, Gunnar; Sørensen, Claus Storgaard

2013-01-01

of histones have emerged as key regulators of genomic integrity. Intense research during the past few years has revealed histone H4 lysine 20 methylation (H4K20me) as critically important for the biological processes that ensure genome integrity, such as DNA damage repair, DNA replication and chromatin...... compaction. The distinct H4K20 methylation states are mediated by SET8/PR-Set7 that catalyses monomethylation of H4K20, whereas SUV4-20H1 and SUV4-20H2 enzymes mediate further H4K20 methylation to H4K20me2 and H4K20me3. Disruption of these H4K20-specific histone methyltransferases leads to genomic...

Preconcentration system for cadmium and lead determination in environmental samples using polyurethane foam/Me-BTANC

International Nuclear Information System (INIS)

Moreira Gama, Ednilton; Silva Lima, Adriana da; Azevedo Lemos, Valfredo

2006-01-01

In this work, polyurethane foam (PUF) loaded with 2-(6'-methyl-2'-benzothiazolylazo)chromotropic acid (Me-BTANC) was packed in a minicolumn and it was used in an on-line preconcentration system for cadmium and lead determination. Optimum hydrodynamic and chemical conditions for metal sorption were investigated. The effects of several foreign substances on the adsorption of cadmium and lead were also reported. The enrichment factor obtained was 37 (Cd and Pb) for 180 s preconcentration time. The proposed procedures allowed the determination of metals with detection limits (3σ) of 0.80 and 3.75 μg L -1 (0.10 and 0.47 μg g -1 of solid sample) for cadmium and lead, respectively. The precision of the procedures was also calculated: 3.1 (Cd 10 μg L -1 ) and 4.4% (Pb 100 μg L -1 ). The accuracy of the procedure was checked by analysis of the certified reference materials Spinach Leaves and Fish Tissue. Cadmium and lead contents in environmental samples (black tea, spinach leaves, natural and tap water) were determined by applying the proposed procedure

Water-Blown Polyurethane Foams Showing a Reversible Shape-Memory Effect

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Elena Zharinova

2016-11-01

Full Text Available Water-blown polyurethane (PU foams are of enormous technological interest as they are widely applied in various fields, i.e., consumer goods, medicine, automotive or aerospace industries. The discovery of the one-way shape-memory effect in PU foams provided a fresh impetus for extensive investigations on porous polymeric actuators over the past decades. High expansion ratios during the shape-recovery are of special interest when big volume changes are required, for example to fill an aneurysm during micro-invasive surgery or save space during transportation. However, the need to program the foams before each operation cycle could be a drawback impeding the entry of shape-memory polymeric (SMP foams to our daily life. Here, we showed that a reversible shape-memory effect (rSME is achievable for polyurethane water-blown semicrystalline foams. We selected commercially available crystallizable poly(ε-caprolactone-diols of different molecular weight for foams synthesis, followed by investigations of morphology, thermal, thermomechanical and shape-memory properties of obtained compositions. Densities of synthesized foams varied from 110 to 180 kg∙m−3, while peak melting temperatures were composition-dependent and changed from 36 to 47 °C, while the melting temperature interval was around 15 K. All semicrystalline foams exhibited excellent one-way SME with shape-fixity ratios slightly above 100% and shape-recovery ratios from the second cycle of 99%. The composition with broad distribution of molecular weights of poly(ε-caprolactone-diols exhibited an rSME of about 12% upon cyclic heating and cooling from Tlow = 10 °C and Thigh = 47 °C. We anticipate that our experimental study opens a field of systematic investigation of rSMEs in porous polymeric materials on macro and micro scale and extend the application of water-blown polyurethane foams to, e.g., protective covers with zero thermal expansion or even cushions adjustable to a certain body

HS-SPME-GC-MS Analysis of onion (Allium cepa L. and shallot (Allium ascalonicum L.

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D’Auria, M.

2017-06-01

Full Text Available The volatile organic compounds of onion and shallot were determined via HS-SPME-GC-MS. The main components were dipropyldisulphide and allylpropyldisulphide. Thiopropanal S-oxide were detected only in onion volatiles. In shallot is interesting the presence of 2-methyl-2-pentenal, a compound with an intense fruity aroma, that can characterize the different aroma between onion and shallot. The SPME-GC-MS analysis of shallot after absorption on the SPME fiber at 50°C showed the presence of new compounds, whose structures have been discussed.

Radioisotope investigations on the stratigraphic distribution of poly/methyl methacrylate/grafted onto leather

International Nuclear Information System (INIS)

Pietrucha, K.; Kroh, J.

1984-01-01

Investigations on the stratigraphic distribution of poly/methyl methacrylate/ in leather follow our earlier experiments on radiation grafting of vinyl monomers in situ. Polymer distribution was determined for pigskins and cattlehides tanned with basic sulphates of chromium/III/. 14 C-labelled methyl methacrylate was used in present experiments. Precision slicing technique was employed to cut consecutive slices parallel to the grain surface of the radiation modified leather. Quantative analysis of polymer distribution in leather was based on radioactivity measurements. Each layer was burned in Oxymat apparatus and resulting 14 CO 2 was analysed by liquid scintillation method. On the basis of radioactivity measurements and visual observations with light microscope conclusion on desirable distribution of polymer was reached. In the midcorium part of leather polymer is evenly distributed and its content is much higher than for outer layers next to surface and flesh. Mechanism of relevant processes as well as formation and role played by peroxide compounds is discussed

Radioisotope investigations on the stratigraphic distribution of poly(methyl methacrylate) grafted onto leather

International Nuclear Information System (INIS)

Pietrucha, K.; Kroh, J.

1985-01-01

Investigations on the stratigraphic distribution of poly(methyl methacrylate) in leather follow our earlier experiments on radiation grafting of vinyl monomers in situ. Polymer distribution was determined for pigskins and cattlehides tanned with basic sulphates of chromium (III). 14 C-labelled methyl methacrylate was used in present experiments. Precision slicing technique was employed to cut consecutive slices parallel to the grain surface of the radiation modified leather. Quantitative analysis of polymer distribution in leather was based on radioactivity measurements. Each layer was burned in Oxymat apparatus and resulting 14 CO 2 was analysed by liquid scintillation method. On the basis of radioactivity measurements and visual observations with light microscope conclusion on desirable distribution of polymer was reached. In the midcorium part of leather polymer is evenly distributed and its content is much higher than for outer layers next to surface and flesh. Mechanism of relevant processes as well as formation and role played by peroxide compounds are discussed. (author)

A novel poly(3,4-ethylenedioxythiophene)-ionic liquid composite coating for the headspace solid-phase microextraction and gas chromatography determination of several alcohols in soft drinks.

Science.gov (United States)

Wu, Mian; Zhang, Haibo; Zhao, Faqiong; Zeng, Baizhao

2014-11-19

A novel poly(3,4-ethylenedioxythiophene)-ionic liquid (i.e., 1-hydroxyethyl-3-methyl imidazolium-bis[(trifluoromethyl)sulfonyl]imide) composite film was electrodeposited on a Pt wire for headspace solid-phase microextraction. The film showed nodular structure and had large specific surface. In addition, it displayed high thermal stability (up to 300°C) and durable property (could be used for more than 200 times). Coupled with gas chromatography-flame ionization detection, the resulting fiber was applied to the headspace solid-phase microextraction and determination of several alcohols (i.e., linalool, nonanol, terpineol, geraniol, decanol and dodecanol). It presented higher extraction capability in comparison with the poly(3,4-ethylenedioxythiophene) and commercial polydimethylsiloxane/divinylbenzene fiber. Under the optimized conditions, the linear ranges exceeded three magnitudes with correlation coefficients above 0.9952 and the low limits of detection were 34.2-81.3ng L(-1). For different alcohols the repeatabilities (defined as RSD) were alcohols in real samples with acceptable recoveries from 81.1% to 106.6%. Copyright © 2014 Elsevier B.V. All rights reserved.

Thermally reversible cross-linked poly(ether-urethanes

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V. Gaina

2013-07-01

Full Text Available Cross-linked poly(ether-urethanes were prepared by Diels-Alder (DA reaction of the furan-containing poly(ether-urethane to bismaleimides and showed thermal reversibility evidenced by differential scanning calorimetry and attenuated total reflectance in conjunction with Fourier transform infrared spectroscopy (ATR-FTIR. The furan-containing poly(ether-urethanes were synthesized by the polyaddition reaction of 1,6-hexamethylene diisocyanate (HMDI or 4,4'- dibenzyl diisocyanate (DBDI to poly(tetramethylene ether glycol (PTMEG having Mn = 250, 650, 1000, 1500 and 2000 and 2-[N,N-bis(2-methyl-2-hydroxyethylamino]furfuryl as chain extender by the solution prepolymer method. The molar ratio of isocyanate: PTMEG:chain extender varied from 2:1:1 to 4:1:3, which produces a molar concentration of furyl group ranging between 3.65•10–4 and 1.25•10–3 mol/g.

New Synthesis and Antiparasitic Activity of Model 5-Aryl-1-methyl-4-nitroimidazoles

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Mustafa M. El-Abadelah

2009-07-01

Full Text Available A number of 5-aryl-1-methyl-4-nitroimidazoles 5a-f have been synthesized in good yields by the Suzuki coupling reaction between 5-chloro-1-methyl-4-nitroimidazole (3 and arylboronic acids 4a-f, aided by dichlorobis-(triphenylphosphinepalladium(II, K2CO3, and tetrabutylammonium bromide in water at 70-80 °C. Compounds 5a-f were characterized by elemental analysis, NMR and MS spectral data. On the basis of in vitro screening data, 5-(3-chlorophenyl-1-methyl-4-nitro-1H-imidazole (5fexhibited potent lethal activity against Entamoeba histolytica and Giardia intestinalis with IC50 = 1.47 µM/mL, a value lower by a factor of two than that of the standard drug, metronidazole. The boosted activity of 5f was not accompanied by any increased cytotoxicity.The rest of the series also exhibited potent antiparasitic activity with IC50 valuesin the 1.72-4.43 µM/mL range. The cytotoxicity of the derivatives 5c and 5e was increased compared to the precursor compound, metronidazole, although they remain non-cytotoxic at concentrations much higher than the antiparasitic concentration of the two derivatives.

New synthesis and antiparasitic activity of model 5-aryl-1-methyl-4-nitroimidazoles.

Science.gov (United States)

Saadeh, Haythem A; Mosleh, Ibrahim M; El-Abadelah, Mustafa M

2009-07-27

A number of 5-aryl-1-methyl-4-nitroimidazoles 5a-f have been synthesized in good yields by the Suzuki coupling reaction between 5-chloro-1-methyl-4-nitroimidazole (3) and arylboronic acids 4a-f, aided by dichlorobis-(triphenylphosphine)palladium(II), K(2)CO(3, )and tetrabutylammonium bromide in water at 70-80 degrees C. Compounds 5a-f were characterized by elemental analysis, NMR and MS spectral data. On the basis of in vitro screening data, 5-(3-chlorophenyl)-1-methyl-4-nitro-1H-imidazole (5f) exhibited potent lethal activity against Entamoeba histolytica and Giardia intestinalis with IC(50) = 1.47 microM/mL, a value lower by a factor of two than that of the standard drug, metronidazole. The boosted activity of 5f was not accompanied by any increased cytotoxicity.The rest of the series also exhibited potent antiparasitic activity with IC(50 ) values in the 1.72-4.43 microM/mL range. The cytotoxicity of the derivatives 5c and 5e was increased compared to the precursor compound, metronidazole, although they remain non-cytotoxic at concentrations much higher than the antiparasitic concentration of the two derivatives.

Design, synthesis and pharmacological evaluation of some novel derivatives of 1-{[3-(furan-2-yl-5-phenyl-4,5-dihydro-1,2-oxazol-4-yl]methyl}-4-methyl piperazine

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Jagdish Kumar

2017-01-01

Full Text Available A novel series of 1-{[3-(furan-2-yl-5-substituted phenyl-4,5-dihydro-1,2-oxazol-4-yl]methyl}-4-methyl piperazine, compounds 3a–l have been synthesized. The synthetic work was carried out beginning from 2-acetylfuran through Claisen Schmidt condensation with different types of aromatic aldehyde, affording 1-(furan-2-yl-3-substitutedphenylprop-2-en-1-ones which on cyclization with hydroxylamine hydrochloride resulted in 3-(furan-2-yl-5-substitutedphenyl-4,5-dihydro-1,2-oxazole formation. The isoxazolines were subjected to Mannich’s reaction in the presence of N-methyl piperazine to produce the desired product. The chemical structures of the compounds were proved by IR, 1H NMR, 13C-NMR and Mass spectrometric data. The antidepressant activities of the compounds were investigated by Porsolt’s behavioral despair (forced swimming test on albino mice. Moreover, the antianxiety activity of the newly synthesized compounds was investigated by the plus maze method. Compounds 3a and 3k reduced the duration of immobility times of 152.00–152.33% at 10 mg/kg dose level and compounds 3a and 3k have also shown significant antianxiety activity.

Numerical simulation of anisotropic polymeric foams

Directory of Open Access Journals (Sweden)

Volnei Tita

Full Text Available This paper shows in detail the modelling of anisotropic polymeric foam under compression and tension loadings, including discussions on isotropic material models and the entire procedure to calibrate the parameters involved. First, specimens of poly(vinyl chloride (PVC foam were investigated through experimental analyses in order to understand the mechanical behavior of this anisotropic material. Then, isotropic material models available in the commercial software AbaqusTM were investigated in order to verify their ability to model anisotropic foams and how the parameters involved can influence the results. Due to anisotropy, it is possible to obtain different values for the same parameter in the calibration process. The obtained set of parameters are used to calibrate the model according to the application of the structure. The models investigated showed minor and major limitations to simulate the mechanical behavior of anisotropic PVC foams under compression, tension and multi-axial loadings. Results show that the calibration process and the choice of the material model applied to the polymeric foam can provide good quantitative results and save project time. Results also indicate what kind and order of error one will get if certain choices are made throughout the modelling process. Finally, even though the developed calibration procedure is applied to specific PVC foam, it still outlines a very broad drill to analyze other anisotropic cellular materials.

Antiresonant guiding in a poly(methyl-methacrylate) hollow-core optical fiber

International Nuclear Information System (INIS)

Markos, Christos; Nielsen, Kristian; Bang, Ole

2015-01-01

Strong antiresonant reflecting optical waveguiding is demonstrated in a novel poly (methyl-methacrylate) (PMMA) hollow-core fiber. The transmission spectrum of the fiber was characterized using a supercontinuum source and it revealed distinct resonances with resonant dips as strong as ∼20 dB in the wavelength range 480–900 nm, where PMMA has low absorption. The total propagation loss of the fiber was measured to have a minimum of ∼45 dB m −1 at around 500 nm. The thermal sensitivity of the fiber is 256 ± 16 pm °C −1 , defined as the red-shift of the resonances per °C, which is three times higher than the sensitivity of polymer fiber Bragg gratings. (paper)

Synthesis and properties of the metallo-supramolecular polymer hydrogel poly[methyl vinyl ether-alt-mono-sodium maleate]·AgNO3: Ag+/Cu2+ ion exchange and effective antibacterial activity

KAUST Repository

Xu, Feng

2014-01-01

The commercial polymeric anhydride poly(methyl vinyl ether-alt-maleic anhydride) (PVM/MA) is converted by reaction with NaOH to give poly(methyl vinyl ether-alt-mono-sodium maleate) (PVM/Na-MA). By addition of AgNO 3-solution, the formation of the silver(i) supramolecular polymer hydrogel poly[methyl vinyl ether-alt-mono-sodium maleate]·AgNO 3 is reported. Freeze-dried samples of the hydrogel show a mesoporous network of polycarboxylate ligands that are crosslinked by silver(i) cations. In the intact hydrogel, ion-exchange studies are reported and it is shown that Ag+ ions can be exchanged by copper(ii) cations without disintegration of the hydrogel. The silver(i) hydrogel shows effective antibacterial activity and potential application as burn wound dressing. © the Partner Organisations 2014.

Characterization Of Biaxial Strain Of Poly(L-Lactide) Tubes

DEFF Research Database (Denmark)

Løvdal, Alexandra Liv Vest; Andreasen, Jens Wenzel; Mikkelsen, Lars Pilgaard

2016-01-01

Poly(L-lactide) (PLLA) in its L-form has promising mechanical properties. Being a semi-crystalline polymer, it can be subjected to strain-induced crystallization at temperatures above Tg and can thereby become oriented. Following a simultaneous (SIM) biaxial strain process or a sequential (SEQ...

The polymerisation of oligo(ethylene glycol methyl ether) methacrylate from a multifunctional poly(ethylene imine) derived amide : a stabiliser for the synthesis and dispersion of magnetite nanoparticles

NARCIS (Netherlands)

Kleine, A.; Altan, C.L.; Yarar, U.E.; Sommerdijk, N.A.J.M.; Bucak, S.; Holder, S.J.

2014-01-01

A facile synthetic route to poly(ethylene imine)-graft-poly(oligo(ethylene glycol methyl ether)) (PEI-graft-POEGMA) functionalised superparamagnetic magnetite nanoparticles is described. The polymerisation of OEGMA from a model molecular amide demonstrated the feasibility of POEGMA synthesis under

The thermochemistry of 2,4-pentanedione revisited: observance of a nonzero enthalpy of mixing between tautomers and its effects on enthalpies of formation.

Science.gov (United States)

Temprado, Manuel; Roux, Maria Victoria; Umnahanant, Patamaporn; Zhao, Hui; Chickos, James S

2005-06-30

The enthalpies of formation of pure liquid and gas-phase (Z)-4-hydroxy-3-penten-2-one and 2,4-pentanedione are examined in the light of some more recent NMR studies on the enthalpy differences between gas-phase enthalpies of the two tautomers. Correlation gas chromatography experiments are used to evaluate the vaporization enthalpies of the pure tautomers. Values of (51.2 +/- 2.2) and (50.8 +/- 0.6) kJ.mol(-1) are measured for pure 2,4-pentanedione and (Z)-4-hydroxy-3-penten-2-one, respectively. The value of (50.8 +/- 0.6) kJ.mol(-1) can be contrasted to a value of (43.2 +/- 0.2) kJ.mol(-1) calculated for pure (Z)-4-hydroxy-3-penten-2-one when the vaporization enthalpy is measured in a mixture of tautomers. The difference is attributed to an endothermic enthalpy of mixing that destabilizes the mixture relative to the pure components. Calculation of new enthalpies of formation for (Z)-4-hydroxy-3-penten-2-one and 2,4-pentanedione in both the gas, Delta(f)H degrees (m)(g) = (-378.2 +/- 1.2) and (-358.9 +/- 2.5) kJ.mol(-1), respectively, and liquid phases, Delta(f)H degrees (m)(l) = (-429.0 +/- 1.0) and (-410.1 +/- 1.2) kJ.mol(-1), respectively, results in enthalpy differences between the two tautomers both in the liquid and gas phases that are identical within experimental error, and in excellent agreement with recent gas-phase NMR studies.

Adsorption of thorium from aqueous solution by poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol)

International Nuclear Information System (INIS)

Juan Tan; Yanfei Wang; Mouwu Liu; Chuhua He

2017-01-01

The specialized poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol) (PZS) microspheres were prepared via a reliable and simple precipitation polymerization method and used adsorbent for the removal of thorium (Th) from aqueous solution. The PZS microspheres were characterized by FT-IR, XPS and SEM. The variables influencing the adsorption capacity were investigated. Adsorption experimental data showed thorium adsorption was equilibrium at time 60 min, pH 3.5, adsorbent dosage 1.0 g L -1 and initial concentration 25 mg L -1 , and the adsorption capacity reached to 17.30 mg g -1 . The experimental data followed the pseudo-second-order kinetic model and equilibrium data fit the Langmuir isotherm model very well. (author)

External Electric Field Effects on Excited-State Intramolecular Proton Transfer in 4'-N,N-Dimethylamino-3-hydroxyflavone in Poly(methyl methacrylate) Films.

Science.gov (United States)

Furukawa, Kazuki; Hino, Kazuyuki; Yamamoto, Norifumi; Awasthi, Kamlesh; Nakabayashi, Takakazu; Ohta, Nobuhiro; Sekiya, Hiroshi

2015-09-17

The external electric field effects on the steady-state electronic spectra and excited-state dynamics were investigated for 4'-N,N-(dimethylamino)-3-hydroxyflavone (DMHF) in a poly(methyl methacrylate) (PMMA) film. In the steady-state spectrum, dual emission was observed from the excited states of the normal (N*) and tautomer (T*) forms. Application of an external electric field of 1.0 MV·cm(-1) enhanced the N* emission and reduced the T* emission, indicating that the external electric field suppressed the excited-state intramolecular proton transfer (ESIPT). The fluorescence decay profiles were measured for the N* and T* forms. The change in the emission intensity ratio N*/T* induced by the external electric field is dominated by ESIPT from the Franck-Condon excited state of the N* form and vibrational cooling in potential wells of the N* and T* forms occurring within tens of picoseconds. Three manifolds of fluorescent states were identified for both the N* and T* forms. The excited-state dynamics of DMHF in PMMA films has been found to be very different from that in solution due to intermolecular interactions in a rigid environment.

Synthesis of no-carrier-added alpha-[11C]methyl-L-tryptophan

International Nuclear Information System (INIS)

Chaly, T.; Diksic, M.

1988-01-01

Described here is a synthesis of no-carrier-added alpha-[ 11 C]methyl-L-tryptophan based on alkylation with 11 CH 3 I of an anion generated by reacting the Schiff base of L-tryptophan methyl ester with di-isopropylamine. The synthesis requires approximately 30 min after the end of 11 CO 2 collection and gives alpha-[ 11 C]methyl-L-tryptophan in a 20-25% radiochemical yield calculated at the end of the synthesis and without correction for radioactive decay. The specific activity of the final radiopharmaceutical, measured at the end of the synthesis, was around 2000 Ci/mmol. Data confirming the stereospecificity of the synthesis are also presented

Permeability and toxicity characteristics of L-cysteine and 2-methyl-thiazolidine-4-carboxylic acid in Caco-2 cells.

Science.gov (United States)

Kartal-Hodzic, Alma; Marvola, Tuuli; Schmitt, Mechthild; Harju, Kirsi; Peltoniemi, Marikki; Sivén, Mia

2013-01-01

Acetaldehyde is a known mutagenic substance and has been classified as a group-one carcinogen by the WHO. It is possible to bind acetaldehyde locally in the gastrointestinal (GI) tract with the semi-essential amino acid l-cysteine, which reacts covalently with acetaldehyde and forms compound 2-methyl-thiozolidine-4-carboxylic acid (MTCA). The Caco-2 cell line was used to determine the permeation of l-cysteine and MTCA, as well as the possible cell toxicity of both substances. Neither of the substances permeated through the Caco-2 cells at the concentrations used in this study, and only the highest concentration of MTCA affected the viability of the cells in the MTT (3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium bromide) test. These results showed that when l-cysteine is administered in formulations releasing it locally in the lower parts of GI tract, it is not absorbed but can react with acetaldehyde, and that neither l-cysteine nor MTCA is harmful to the cells when present locally in the upper parts of GI tract. This study also shows that MTCA is sensitive at a lower pH of 5.5. Since stable MTCA is desired in different parts of the GI tract, this observation raises concern over the influence of lower pH on l-cysteine-containing product ability to bind and eliminate carcinogenic acetaldehyde.

Synthesis and Properties of the Metallo-Supramolecular Polymer Hydrogel Poly[methyl vinyl ether-alt-mono-sodium maleate]∙AgNO3

KAUST Repository

Al-Dossary, Mona S.

2014-05-01

Gels are a special class of materials which are composed of 3D networks of crosslinked polymer chains that encapsulate liquid/air in the matrix. They can be classified into organogels or hydrogels (organic solvent for organogel and water for hydrogel). For hydrogels that contain metallic elements in the form of ions, the term of metallo-supramolecular polymer hydrogel (MSPHG) is often used. The aim of this project is to develop a kind of new MSPHG and investigate its properties and possible applications. The commercial polymeric anhydride poly(methyl vinyl ether-alt-maleic anhydride) (PVM/MA) is converted by reaction with NaOH to give poly(methyl vinyl ether-alt-monosodium maleate) (PVM/Na-MA). By addition of AgNO3-solution, the formation of the silver(I) supramolecular polymer hydrogel poly[methyl vinyl ether-alt-mono-sodium maleate]∙AgNO3 is obtained. Freeze-dried samples of the hydrogel show a mesoporous network of polycarboxylate ligands that are crosslinked by silver(I) cations. The supercritical CO2 dried silver(I) hydrogel was characterized by FT-IR, SEM-EDAX, TEM, TGA and Physical adsorption (BET) measurements. The intact silver(I) hydrogel was characterized by cryo-SEM. In the intact hydrogel, ion-exchange studies are reported and it is shown that Ag+ ions can be exchanged by copper(II) cations without disintegration of the hydrogel. The silver(I) hydrogel shows effective antibacterial activity and potential application as burn wound dressing.

High optical and switching performance electrochromic devices based on a zinc oxide nanowire with poly(methyl methacrylate) gel electrolytes

Energy Technology Data Exchange (ETDEWEB)

Chun, Young Tea; Chu, Daping, E-mail: dpc31@cam.ac.uk [Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA (United Kingdom); Neeves, Matthew; Placido, Frank [Thin Film Centre, University of the West of Scotland, Paisley PA1 2BE (United Kingdom); Smithwick, Quinn [Disney Research, 521 Circle Seven Drive, Glendale, Los Angeles, California 91201 (United States)

2014-11-10

High performance electrochromic devices have been fabricated and demonstrated utilizing a solid polymer electrolyte and zinc oxide (ZnO) nanowire (NW) array counter electrode. The poly(methyl methacrylate) based polymer electrolyte was spin coated upon hydrothermally grown ZnO NW array counter electrodes, while electron beam evaporated NiO{sub x} thin films formed the working electrodes. Excellent optical contrast and switching speeds were observed in the fabricated devices with active areas of 2 cm{sup 2}, exhibiting an optical contrast of 73.11% at the wavelength of 470 nm, combined with a fast switching time of 0.2 s and 0.4 s for bleaching and coloration, respectively.

High optical and switching performance electrochromic devices based on a zinc oxide nanowire with poly(methyl methacrylate) gel electrolytes

International Nuclear Information System (INIS)

Chun, Young Tea; Chu, Daping; Neeves, Matthew; Placido, Frank; Smithwick, Quinn

2014-01-01

High performance electrochromic devices have been fabricated and demonstrated utilizing a solid polymer electrolyte and zinc oxide (ZnO) nanowire (NW) array counter electrode. The poly(methyl methacrylate) based polymer electrolyte was spin coated upon hydrothermally grown ZnO NW array counter electrodes, while electron beam evaporated NiO x thin films formed the working electrodes. Excellent optical contrast and switching speeds were observed in the fabricated devices with active areas of 2 cm 2 , exhibiting an optical contrast of 73.11% at the wavelength of 470 nm, combined with a fast switching time of 0.2 s and 0.4 s for bleaching and coloration, respectively

Synthesis of Poly(3,4-Ethylenedioxy thiophene)-Poly(Styrene-4-Sulfonate) Composites for Support Fuel Cell Catalyst Layer

International Nuclear Information System (INIS)

Eko Sulistiyono; Murni Handayani

2009-01-01

Synthesis of poly(3,4-ethylenedioxy thiophene)-poly(styrene-4-sulfonate) composites for support fuel cell catalyst layer are synthesis composites which become fuel cell catalyst support so that catalyst has optimal performance. Main function of composites is support platinum particle for application in fuel cell. This article explains the result of composites production process from ( 3,4 Ethylenedioxy thiophene) and Sodium poly( styrene - 4-sulfonate) using two methods Jingning Shan method (method 1) and Zhigang Qi and Peter G.Pickup method (method 2). Analysis of the synthesis results used Scanning Electron Microscopic –Electron Dispersive X – Ray Spectrophotometer (SEM-EDS ). The analysis result show that both methods produce polymer agglomerate into a sponge-like morphology. Composite from method 1 has morphology, pores and proton transport better than composite produced by method 2. (author)

Ruthenium complexing during sorption by graft copolymer of polyacrylonitrile fibre with poly-2-methyl-5-vnylpyridine (PAN-MVP)

International Nuclear Information System (INIS)

Simanova, S.A.; Kolmakova, A.I.; Konovalov, L.V.; Kukushkin, Yu.N.; Lysenko, A.A.

1984-01-01

The sorption of ruthenium chlorocomplexes is studied on graft copolymer of polyacrylonitrile fibre with poly-2-methyl-5-vinylpyridine (PAN-MVP). The sorption has been performed under static conditions in the course of mixing at 20 and 98 deg from 0.1-2 OM HCl, 0.1-1 m NaCl solutions. The volume of the investigated solutions constituted 25 ml, fibre weight -0.1-0.3 g. Ruthenium concentration in solutions has been changed in the limits of 5x10 3 -2x10 -2 mol/l. The fibre has been preliminarily moistened by a solution containing no ruthenium. In all cases fresh-prepared ruthenium chlorocomplex solutions have been used. It has been found that with temperature increase the PAN-MVP sorption capacitance relative to ruthenium increases (at 20 deg-1.15 mmol/g, at 98 deg-1.70 mmol/g. The ruthenium chlorocomplex sorption by pyridine fibrous sorbent from salt-acid solutions occurs by anionoexchange mechanism and is related to the formation in the sorbent phase of onium chlorocomplexes - (RPyH) 2 [RuCl 6 ]. In the course of sorbents heating pyridine compounds are subject to Anderson regroupping with formation of compounds of diamine type-[Ru(RPy) 2 Cl 4

Preparation and Characterization of Mesoporous Zirconia Made by Using a Poly (methyl methacrylate Template

Directory of Open Access Journals (Sweden)

Zhang Chunxiang

2008-01-01

Full Text Available AbstractSuperfine powders of poly (methyl methacrylate (PMMA have been prepared by means of an emulsion polymerization method. These have been used as templates in the synthesis of tetragonal phase mesoporous zirconia by the sol–gel method, using zirconium oxychloride and oxalic acid as raw materials. The products have been characterized by infrared spectroscopy, X-ray diffraction analysis, transmission electron microscopy, N2adsorption-desorption isotherms, and pore size distribution. The results indicate that the average pore size was found to be 3.7 nm.

Synthesis and characterization of poly(methyl methacrylate)/OMMT nanocomposites by γ-ray irradiation polymerization

International Nuclear Information System (INIS)

Zhang Weian; Shen Xiaofeng; Li Yu; Fang Yuee

2003-01-01

Organophilic montmorillonite (OMMT) was synthesized by cationic exchange between Na-MMT and cetyltrimethylammonium bromide in an aqueous solution. Poly(methyl methacrylate)(PMMA)/(OMMT) nanocomposites was prepared by γ-ray irradiation polymerization. The dispersion degree and the intercalation spacing of these nanocomposites were investigated with the X-ray diffraction and high-resolution transmission electron microscopy, respectively. The thermal stabilities of the samples were studied by the thermal gravimetric analysis. The nanocomposites had higher storage modulus and higher glass transition temperature (T g ) than the pure PMMA, which were measured by dynamic mechanical analysis

Poly(methyl methacrylate) Composites with Size-selected Silver Nanoparticles Fabricated Using Cluster Beam Technique

DEFF Research Database (Denmark)

Muhammad, Hanif; Juluri, Raghavendra R.; Chirumamilla, Manohar

2016-01-01

based on cluster beam technique allowing the formation of monocrystalline size-selected silver nanoparticles with a ±5–7% precision of diameter and controllable embedment into poly (methyl methacrylate). It is shown that the soft-landed silver clusters preserve almost spherical shape with a slight...... tendency to flattening upon impact. By controlling the polymer hardness (from viscous to soft state) prior the cluster deposition and annealing conditions after the deposition the degree of immersion of the nanoparticles into polymer can be tuned, thus, making it possible to create composites with either...

Thermo-Mechanical Properties of Semi-Degradable Poly(β-amino ester)-co-Methyl Methacrylate Networks under Simulated Physiological Conditions

Science.gov (United States)

Safranski, David L.; Crabtree, Jacob C.; Huq, Yameen R.; Gall, Ken

2011-01-01

Poly(β-amino ester) networks are being explored for biomedical applications, but they may lack the mechanical properties necessary for long term implantation. The objective of this study is to evaluate the effect of adding methyl methacrylate on networks' mechanical properties under simulated physiological conditions. The networks were synthesized in two parts: (1) a biodegradable crosslinker was formed from a diacrylate and amine, (2) and then varying concentrations of methyl methacrylate were added prior to photopolymerizing the network. Degradation rate, mechanical properties, and glass transition temperature were studied as a function of methyl methacrylate composition. The crosslinking density played a limited role on mechanical properties for these networks, but increasing methyl methacrylate concentration improved the toughness by several orders of magnitude. Under simulated physiological conditions, networks showed increasing toughness or sustained toughness as degradation occurred. This work establishes a method of creating degradable networks with tailorable toughness while undergoing partial degradation. PMID:21966028

Synthesis of 14C-labelled α-methyl tyrosine

International Nuclear Information System (INIS)

Rajagopal, S.; Venkatachalam, T.K.; Conway, T.; Diksic, M.

1992-01-01

A new route for the preparation of radioactively labelled α-methyl L-tyrosine is described. The labelling at the α position has been successfully achieved with 14 C-, 11 C- (very preliminary, unpublished), and 3 H-labelled methyl iodide. A detailed report on 14 C-labelling at the α position and the hydrolysis of 4-methoxy α-methyl phenylalanine is presented. The alkylation proceeds via the methylation of the carbanion of N-benzylidene 4-methoxy phenylalanine methyl ester 2. Hydrolysis of 4-O methyl tyrosine to tyrosine by HBr and HI were analysed and used in the optimization of the hydrolysis conditions of 4. Enantiomeric purity of the isolated L-isomer has been found to be 99% as judged by HPLC. Pseudo first-order rate constant for the hydrolysis of 14 C-labelled α-methyl 4-methoxy phenyl alanine methyl ester was determined. Preliminary findings of the 3 H- and 11 C-radiolabelled α-methyl tyrosine (methyl labelled) are also mentioned. For the first time it was shown that α-methyl D,L-tyrosine can be separated into enantiomerically pure α-methyl D- and L-tyrosine using a CHIRALPAK WH column. (author)

Efficient removal of perfluorooctane sulfonate from aqueous film-forming foam solution by aeration-foam collection.

Science.gov (United States)

Meng, Pingping; Deng, Shubo; Maimaiti, Ayiguli; Wang, Bin; Huang, Jun; Wang, Yujue; Cousins, Ian T; Yu, Gang

2018-07-01

Aqueous film-forming foams (AFFFs) used in fire-fighting are one of the main contamination sources of perfluorooctane sulfonate (PFOS) to the subterranean environment, requiring high costs for remediation. In this study, a method that combined aeration and foam collection was presented to remove PFOS from a commercially available AFFF solution. The method utilized the strong surfactant properties of PFOS that cause it to be highly enriched at air-water interfaces. With an aeration flow rate of 75 mL/min, PFOS removal percent reached 96% after 2 h, and the PFOS concentration in the collected foam was up to 6.5 mmol/L, beneficial for PFOS recovery and reuse. Increasing the aeration flow rate, ionic strength and concentration of co-existing surfactant, as well as decreasing the initial PFOS concentration, increased the removal percents of PFOS by increasing the foam volume, but reduced the enrichment of PFOS in the foams. With the assistance of a co-existing hydrocarbon surfactant, PFOS removal percent was above 99.9% after aeration-foam collection for 2 h and the enrichment factor exceeded 8400. Aeration-foam collection was less effective for short-chain perfluoroalkyl substances due to their relatively lower surface activity. Aeration-foam collection was found to be effective for the removal of high concentrations of PFOS from AFFF-contaminated wastewater, and the concentrated PFOS in the collected foam can be reused. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effect of modified graphene and microwave irradiation on the mechanical and thermal properties of poly(styrene-co-methyl methacrylate)/graphene nanocomposites

KAUST Repository

Zubair, Mukarram; Jose, Jobin Vinodh; Emwas, Abdul-Hamid M.; Al-Harthi, Mamdouh Ahmed

2014-01-01

The effect of modified graphene (MG) and microwave irradiation on the interaction between graphene (G) and poly(styrene-co-methyl meth acrylate) [P(S-co-MMA)] polymer matrix has been studied in this article. Modification of graphene was performed

Raman spectra of bilayer graphene covered with Poly(methyl methacrylate) thin film

Energy Technology Data Exchange (ETDEWEB)

Xia Minggang [MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Science, Xi' an Jiaotong University, 710049 (China); Center on Experimental Physics, School of Science, Xi' an Jiaotong University, 710049 (China); Su Zhidan; Zhang Shengli [MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Science, Xi' an Jiaotong University, 710049 (China); Department of Applied Physics, School of Science, Xi' an Jiaotong University, 710049 (China)

2012-09-15

The Raman spectra of bilayer graphene covered with poly(methyl methacrylate) (PMMA) were investigated. Both the G and 2D peaks of PMMA-coated graphene were stiff and broad compared with those of uncovered graphene. This could be attributed to the residual strain induced by high-temperature baking during fabrication of the nanodevice. Furthermore, the two 2D peaks stiffened and broadened with increasing laser power, which is just the reverse to uncovered graphene. The stiffness is likely caused by graphene compression induced by the circular bubble of the thin PMMA film generated by laser irradiation. Our findings may contribute to the application of PMMA in the strain engineering of graphene nanodevices.

Raman spectra of bilayer graphene covered with Poly(methyl methacrylate thin film

Directory of Open Access Journals (Sweden)

Minggang Xia

2012-09-01

Full Text Available The Raman spectra of bilayer graphene covered with poly(methyl methacrylate (PMMA were investigated. Both the G and 2D peaks of PMMA-coated graphene were stiff and broad compared with those of uncovered graphene. This could be attributed to the residual strain induced by high-temperature baking during fabrication of the nanodevice. Furthermore, the two 2D peaks stiffened and broadened with increasing laser power, which is just the reverse to uncovered graphene. The stiffness is likely caused by graphene compression induced by the circular bubble of the thin PMMA film generated by laser irradiation. Our findings may contribute to the application of PMMA in the strain engineering of graphene nanodevices.

Study of the relationships between nuclear decontamination foams stability and their physicochemical properties

International Nuclear Information System (INIS)

Dame, C.

2006-03-01

The LPAD (French Atomic Energy Commission) develops innovative processes in the frame of the future dismantling of nuclear facilities. Formulations were developed using high viscosified foams stabilized by biodegradable nonionic surfactants: alkyl poly-glucosides and viscosifiers (xanthan gum), which allow us to increase the foam lifetime and thus contact time of chemical reactants with the facility walls. We have considered the relationships between physicochemical properties and foam stability through the exploration of the foam at three different scales: from the molecular range (micelles, surface tension and visco-elasticity), to the film and Plateau border range (XR reflectivity, surface shear viscosity) and to macroscopic range, meaning the whole foam (foaminess, liquid fraction and wall film thickness evolution). Finally, exploratory study is presented concerning simultaneous foam three scales characterisation by small angle neutron scattering. (author)

Hierarchical Cu2O foam/g-C3N4 photocathode for photoelectrochemical hydrogen production

Science.gov (United States)

Ma, Xinzhou; Zhang, Jingtao; Wang, Biao; Li, Qiuguo; Chu, Sheng

2018-01-01

Solar photoelectrochemical (PEC) hydrogen production is a promising way for solving energy and environment problems. Earth-abundant Cu2O is a potential light absorber for PEC hydrogen production. In this article, hierarchical porous Cu2O foams are prepared by thermal oxidation of the electrochemically deposited Cu foams. PEC performances of the Cu2O foams are systematically studied and discussed. Benefiting from their higher light harvesting and more efficient charge separation, the Cu2O foams demonstrate significantly enhanced photocurrents and photostability compared to their film counterparts. Moreover, by integrating g-C3N4, hierarchical Cu2O foam/g-C3N4 composites are prepared with further improved photocurrent and photostability, appearing to be potential photocathodes for solar PEC hydrogen production. This study may provide a new and useful insight for the development of Cu2O-based photocathodes for PEC hydrogen production.

Lithography exposure characteristics of poly(methyl methacrylate) (PMMA) for carbon, helium and hydrogen ions

Science.gov (United States)

Puttaraksa, Nitipon; Norarat, Rattanaporn; Laitinen, Mikko; Sajavaara, Timo; Singkarat, Somsorn; Whitlow, Harry J.

2012-02-01

Poly(methyl methacrylate) is a common polymer used as a lithographic resist for all forms of particle (photon, ion and electron) beam writing. Faithful lithographic reproduction requires that the exposure dose, Θ, lies in the window Θ0⩽ΘChiang Mai and Jyväskylä to determine the exposure characteristics in terms of fluence for 2 MeV protons, 3 MeV 4He and 6 MeV 12C ions, respectively. After exposure the samples were developed in 7:3 by volume propan-2-ol:de-ionised water mixture. At low fluences, where the fluence is below the clearing fluence, the exposed regions were characterised by rough regions, particularly for He with holes around the ion tracks. As the fluence (dose) increases so that the dose exceeds the clearing dose, the PMMA is uniformly removed with sharp vertical walls. When Θ exceeds the cross-linking onset fluence, the bottom of the exposed regions show undissolved PMMA.

Bioinspired Hydroxyapatite/Poly(methyl methacrylate) Composite with a Nacre-Mimetic Architecture by a Bidirectional Freezing Method.

Science.gov (United States)

Bai, Hao; Walsh, Flynn; Gludovatz, Bernd; Delattre, Benjamin; Huang, Caili; Chen, Yuan; Tomsia, Antoni P; Ritchie, Robert O

2016-01-06

Using a bidirectional freezing technique, combined with uniaxial pressing and in situ polymerization, "nacre-mimetic" hydroxyapatite/poly(methyl methacrylate) (PMMA) composites are developed by processing large-scale aligned lamellar ceramic scaffolds. Structural and mechanical characterization shows "brick-and-mortar" structures, akin to nacre, with interesting combinations of strength, stiffness, and work of fracture, which provide a pathway to making strong and tough lightweight materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Efficacy of Poly(D,L-Lactic Acid-co-Glycolic acid)-Poly(Ethylene Glycol)-Poly(D,L-Lactic Acid-co-Glycolic Acid) Thermogel As a Barrier to Prevent Spinal Epidural Fibrosis in a Postlaminectomy Rat Model.

Science.gov (United States)

Li, Xiangqian; Chen, Lin; Lin, Hong; Cao, Luping; Cheng, Ji'an; Dong, Jian; Yu, Lin; Ding, Jiandong

2017-04-01

Experimental animal study. The authors conducted a study to determine the efficacy and safety of the poly(D,L-lactic acid-co-glycolic acid)-poly(ethylene glycol)-poly(D,L-lactic acid-co-glycolic acid) (PLGA-PEG-PLGA) thermogel to prevent peridural fibrosis in an adult rat laminectomy model. Peridural fibrosis often occurs after spinal laminectomy. It might cause persistent back and/or leg pain postoperatively and make a reoperation more difficult and dangerous. Various materials have been used to prevent epidural fibrosis, but only limited success has been achieved. The PLGA-PEG-PLGA thermogel was synthesized by us. Total L3 laminectomies were performed on 24 rats. The PLGA-PEG-PLGA thermogel or chitosan (CHS) gel (a positive control group) was applied to the operative sites in a blinded manner. In the control group, the L3 laminectomy was performed and the defect was irrigated with the NS solution 3 times. All the rats were killed 4 weeks after the surgery. The cytotoxicity of this thermogel was evaluated in vitro and the result demonstrated that no evidence of cytotoxicity was observed. The extent of epidural fibrosis, the area of epidural fibrosis, and the density of the fibroblasts and blood vessel were evaluated histologically. There were statistical differences among the PLGA-PEG-PLGA thermogel or CHS gel group compared with the control group. Although there was no difference between the PLGA-PEG-PLGA thermogel and CHS gel, the efficiency of the PLGA-PEG-PLGA thermogel was shown to be slightly improved compared with the CHS gel. The biocompatibility of the PLGA-PEG-PLGA thermogel was proven well. The application of this thermogel effectively reduced epidural scarring and prevented the subsequent adhesion to the dura mater. No side effects were noted in the rats.

The influence of supercritical foaming conditions on properties of polymer scaffolds for tissue engineering

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Kosowska Katarzyna

2017-12-01

Full Text Available The results of experimental investigations into foaming process of poly(ε-caprolactone using supercritical CO2 are presented. The objective of the study was to explore the aspects of fabrication of biodegradable and biocompatible scaffolds that can be applied as a temporary three-dimensional extracellular matrix analog for cells to grow into a new tissue. The influence of foaming process parameters, which have been proven previously to affect significantly scaffold bioactivity, such as pressure (8-18 MPa, temperature (323-373 K and time of saturation (1-6 h on microstructure and mechanical properties of produced polymer porous structures is presented. The morphology and mechanical properties of considered materials were analyzed using a scanning electron microscope (SEM, x-ray microtomography (μ-CT and a static compression test. A precise control over porosity and morphology of obtained polymer porous structures by adjusting the foaming process parameters has been proved. The obtained poly(ε-caprolactone solid foams prepared using scCO2 have demonstrated sufficient mechanical strength to be applied as scaffolds in tissue engineering.

Regioselectivity in the Thermal Rearrangement of Unsymmetrical 4-Methyl-4H-1,2,4-triazoles to 1-Methyl-1H-1,2,4-triazoles

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Per H.J. Carlsen

2001-11-01

Full Text Available The rearrangement of 4-methyl-3,5-diaryl-4H-1,2,4-triazoles to the corresponding 1-methyl-3,5-diaryl-1H-1,2,4-triazoles showed regioselectivity comparable to that observed for the alkylation of 3,5-diaryl-1H-1,2,4-triazoles. This lends support to a proposed mechanism for the rearrangement that involves consecutive nucleophilic displacements steps.

Flexible poly(methyl methacrylate)-based neural probe: An affordable implementation

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Gasemi, Pejman; Veladi, Hadi; Shahabi, Parviz; Khalilzadeh, Emad

2018-03-01

This research presents a novel technique used to fabricate a deep brain stimulation probe based on a commercial poly(methyl methacrylate) (PMMA) polymer. This technique is developed to overcome the high cost of available probes crucial for chronic stimulation and recording in neural disorders such as Parkinson’s disease and epilepsy. The probe is made of PMMA and its mechanical properties have been customized by controlling the reaction conditions. The polymer is adjusted to be stiff enough to be easily inserted and, on the other hand, soft enough to perform required movements. As cost is one of the issues in the use of neural probes, a simple process is proposed for the production of PMMA neural probes without using expensive equipment and operations, and without compromising performance and quality. An in vivo animal test was conducted to observe the recording capability of a PMMA probe.

Preparation and characterization of poly(methyl methacrylate)-clay nanocomposites via melt intercalation: Effect of organoclay on thermal, mechanical and flammability properties

Energy Technology Data Exchange (ETDEWEB)

Unnikrishnan, Lakshmi; Mohanty, Smita [Laboratory for Advanced Research in Polymeric Materials (LARPM), Central Institute of Plastics Engineering and Technology, Bhubaneswar 751024 (India); Nayak, Sanjay K., E-mail: drsknayak@gmail.com [Laboratory for Advanced Research in Polymeric Materials (LARPM), Central Institute of Plastics Engineering and Technology, Bhubaneswar 751024 (India); Ali, Anwar [Laboratory for Advanced Research in Polymeric Materials (LARPM), Central Institute of Plastics Engineering and Technology, Bhubaneswar 751024 (India)

2011-05-15

Research highlights: {yields} The present work deals with preparation and characterization of poly(methyl methacrylate) nanocomposites via melt intercalation technique. {yields} The effect of various modified nanoclays on the properties of base matrix has been investigated. {yields} It was observed that compatibilization using maleic anhydride improved the performance characteristics of PMMA/layered silicate nanocomposites. - Abstract: The PMMA nanocomposites were prepared by melt processing method. The influence of organoclay loading on extent of intercalation, thermal, mechanical and flammability properties of poly(methyl methacrylate) (PMMA)-clay nanocomposites were studied. Three different organoclay modifiers with varying hydrophobicity (single tallow vs. ditallow) were investigated. The nanocomposites were characterized by using wide angle X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, differential scanning calorimetry (DSC), and tensile tests. The intercalation of polymer chain within the silicate galleries was confirmed by WAXD and TEM. Mechanical properties such as tensile modulus (E), tensile strength, percentage elongation at break and impact strength were determined for nanocomposites at various clay loadings. Overall thermal stability of nanocomposites increased by 16-17 deg. C. The enhancement in T{sub g} of nanocomposite is merely by 2-4 deg. C. The incorporation of maleic anhydride as compatibilizer further enhanced all the properties indicating improved interface between PMMA and clay. The flammability characteristics were studied by determining the rate of burning and LOI.

Preparation and characterization of poly(methyl methacrylate)-clay nanocomposites via melt intercalation: Effect of organoclay on thermal, mechanical and flammability properties

International Nuclear Information System (INIS)

Unnikrishnan, Lakshmi; Mohanty, Smita; Nayak, Sanjay K.; Ali, Anwar

2011-01-01

Research highlights: → The present work deals with preparation and characterization of poly(methyl methacrylate) nanocomposites via melt intercalation technique. → The effect of various modified nanoclays on the properties of base matrix has been investigated. → It was observed that compatibilization using maleic anhydride improved the performance characteristics of PMMA/layered silicate nanocomposites. - Abstract: The PMMA nanocomposites were prepared by melt processing method. The influence of organoclay loading on extent of intercalation, thermal, mechanical and flammability properties of poly(methyl methacrylate) (PMMA)-clay nanocomposites were studied. Three different organoclay modifiers with varying hydrophobicity (single tallow vs. ditallow) were investigated. The nanocomposites were characterized by using wide angle X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, differential scanning calorimetry (DSC), and tensile tests. The intercalation of polymer chain within the silicate galleries was confirmed by WAXD and TEM. Mechanical properties such as tensile modulus (E), tensile strength, percentage elongation at break and impact strength were determined for nanocomposites at various clay loadings. Overall thermal stability of nanocomposites increased by 16-17 deg. C. The enhancement in T g of nanocomposite is merely by 2-4 deg. C. The incorporation of maleic anhydride as compatibilizer further enhanced all the properties indicating improved interface between PMMA and clay. The flammability characteristics were studied by determining the rate of burning and LOI.

Biocompatible evaluation of barium titanate foamed ceramic structures for orthopedic applications.

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Ball, Jordan P; Mound, Brittnee A; Nino, Juan C; Allen, Josephine B

2014-07-01

The potential of barium titanate (BT) to be electrically active makes it a material of interest in regenerative medicine. To enhance the understanding of this material for orthopedic applications, the in vitro biocompatibility of porous BT fabricated using a direct foaming technique was investigated. Characterization of the resultant foams yielded an overall porosity between 50 and 70% with average pore size in excess of 30 µm in diameter. A mouse osteoblast (7F2) cell line was cultured with the BT to determine the extent of the foams' toxicity using a LDH assay. After 72 h, BT foams showed a comparable cytotoxicity of 6.4 ± 0.8% to the 8.4 ± 1.5% of porous 45S5 Bioglass®. The in vitro inflammatory response elicited from porous BT was measured as a function of tumor necrosis factor alpha (TNF-α) secreted from a human monocytic leukemia cell line (THP-1). Results indicate that the BT foams do not cause a significant inflammatory response, eliciting a 9.4 ± 1.3 pg of TNF-α per mL of media compared with 20.2 ± 2.3 pg/mL from untreated cells. These results indicate that porous BT does not exhibit short term cytotoxicity and has potential for orthopedic tissue engineering applications. © 2013 Wiley Periodicals, Inc.

Estudo da Degradação In Vitro de Blendas de Poli(p-dioxanona/Poli(l-Ácido Láctico (PPD/PLLA Preparadas por Evaporação de Solvente Degradation of Poly (L-Lactic Acid (PLLA and Poly-p-Dioxanone (PPD Blends Prepared by Casting: In Vitro Study

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Ana P. T. Pezzin

2002-10-01

Full Text Available Blendas de dois polímeros semi-cristalinos biorreabsorvíveis, o poli(ácido láctico (PLLA e a poli(p-dioxanona (PPD, foram preparadas por evaporação de solvente em diferentes composições. As blendas foram imersas em tubos de ensaio contendo solução tampão fosfato (pH = 7,4 em um banho termostatizado a 37 ± 1 °C e avaliadas por calorimetria diferencial de varredura (DSC, análise termogravimétrica (TGA e microscopia eletrônica de varredura (MEV. Foi observado através do estudo in vitro que o PLLA apresenta uma taxa de degradação mais lenta que a PPD e que as blendas apresentam taxa de degradação intermediária, mostrando que é possível variar a taxa de degradação das blendas alterando sua composição.Blends of two crystalline bioreabsorbable polymers, poly(L-lactic acid (PLLA and poly(p-dioxanone (PPD, have been prepared by solvent casting in different compositions. The blends were immersed in tubes containing a phosphate buffer solution (pH = 7.4 in a thermally controlled bath of 37 ± 1°C and studied by differential scanning calorimetry (DSC, thermogravimetric analysis (TGA and scanning electron microscopy (SEM. It was observed by in vitro study that PLLA has a slower degradation rate than PPD and the blends presented an intermediate degradation rate. This shows that it is possible to vary the degradation rate of the blend by changing its composition.

Production of poly(β-l-malic acid) by Aureobasidium pullulans HA-4D under solid-state fermentation.

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Xia, Jun; Li, Rongqing; He, Aiyong; Xu, Jiaxing; Liu, Xiaoyan; Li, Xiangqian; Xu, Jiming

2017-11-01

Poly(β-l-malic acid) (PMA) production by Aureobasidium pullulans HA-4D was carried out through solid-state fermentation (SSF) using agro-industrial residues. Maximum PMA production (75.4mg/g substrate) was obtained from a mixed substrate of sweet potato residue and wheat bran (1:1, w/w) supplemented with NaNO 3 (0.8%, w/w) and CaCO 3 (2%, w/w), with an initial moisture content of 70% and inoculum size of 13% (v/w) for 8days. Repeated-batch SSF was successfully conducted for 5 cycles with a high productivity. The scanning electron microscopy showed that the yeast-like cells of A. pullulans HA-4D could grow well on the solid substrate surface. Moreover, the cost analysis showed that the unit price of PMA in SSF was much lower than that of SmF. This is the first report on PMA production via SSF, and this study provided a new method to produce PMA from inexpensive agro-industrial residues. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of PVA and PDE on selected structural characteristics of extrusion-cooked starch foams

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Maciej Combrzyński

2018-03-01

Full Text Available Abstract The aim of this work was to determine selected physical properties of biodegradable thermoplastic starch (TPS filling foams manufactured by extrusion-cooking technique from different combinations of potato starch and two additives: poly(vinyl alcohol PVA and Plastronfoam PDE. Foams were processed with seven starch/additives combinations at two different extruder-cooker’s screw rotational speeds. The densities of starch foams depended significantly on the additive type and content. The linear relationship between the Young modulus and the ultimate compression force and apparent density was found. The foams processed with the addition of PVA had low density, porosity and lower values of the Young modulus than the foams prepared with PDE.

Synthesis and characterization of a thermo-sensitive poly( N-methyl acryloylglycine methyl ester) used as a drug release carrier

Science.gov (United States)

Deng, Kui-Lin; Zhong, Hai-Bin; Jiao, Yi-Suo; Fan, Ting; Qiao, Xiao; Zhang, Peng-Fei; Ren, Xiao-Bo

2010-06-01

In this article, poly( N-methyl acryloylglycine methyl ester) (PNMAME) was prepared as a novel thermosensitive material with a lower critical solution temperature (LCST) at around 49.5°C. The chemical structures of the monomer NMAME and PNMAME were characterized by 1H NMR and IR measurements. The LCST was investigated systematically as a function of PNMAME concentration, inorganic salt solution and pH value. The results indicated that LCST of PNMAME was obviously dependent on PNMAME concentration and pH. The LCST was increased with a decrease in pH value and PNMAME concentration. To obtain a thermo-sensitive hydrogel with the phase transition temperature close to human body temperature, the copolymerization was conducted between NMAME and N-acryloylglycine ethyl ester (NAGEE). The release behavior of caffeine was evaluated at different temperatures and contents of cross-linkers ( N, N-methylenebis(acrylamide) (NMBA)). The increase of cross-linker content led to a decrease in the release rate of caffeine due to higher crossing density in the hydrogel network. In addition, a faster release of caffeine from the hydrogel with 3% NMBA at 37°C was found in contrast to that at 18°C.

IFI44L promoter methylation as a blood biomarker for systemic lupus erythematosus

Science.gov (United States)

Zhao, Ming; Zhou, Yin; Zhu, Bochen; Wan, Mengjie; Jiang, Tingting; Tan, Qiqun; Liu, Yan; Jiang, Juqing; Luo, Shuaihantian; Tan, Yixin; Wu, Haijing; Renauer, Paul; Gutiérrez, Maria del Mar Ayala; Palma, Maria Jesús Castillo; Castro, Rafaela Ortega; Fernández-Roldán, Concepción; Raya, Enrique; Faria, Raquel; Carvalho, Claudia; Alarcón-Riquelme, Marta E; Xiang, Zhongyuan; Chen, Jinwei; Li, Fen; Ling, Guanghui; Zhao, Hongjun; Liao, Xiangping; Lin, Youkun; Sawalha, Amr H; Lu, Qianjin

2016-01-01

Objective Systemic lupus erythematosus (SLE) is a clinically heterogeneous disease with limited reliable diagnostic biomarkers. We investigated whether gene methylation could meet sensitivity and specificity criteria for a robust biomarker. Methods IFI44L promoter methylation was examined using DNA samples from a discovery set including 377 patients with SLE, 358 healthy controls (HCs) and 353 patients with rheumatoid arthritis (RA). Two independent sets including 1144 patients with SLE, 1350 HCs, 429 patients with RA and 199 patients with primary Sjögren’s syndrome (pSS) were used for validation. Results Significant hypomethylation of two CpG sites within IFI44L promoter, Site1 (Chr1: 79 085 222) and Site2 (Chr1: 79 085 250; cg06872964), was identified in patients with SLE compared with HCs, patients with RA and patients with pSS. In a comparison between patients with SLE and HCs included in the first validation cohort, Site1 methylation had a sensitivity of 93.6% and a specificity of 96.8% at a cut-off methylation level of 75.5% and Site2 methylation had a sensitivity of 94.1% and a specificity of 98.2% at a cut-off methylation level of 25.5%. The IFI44L promoter methylation marker was also validated in an European-derived cohort. In addition, the methylation levels of Site1 and Site2 within IFI44L promoter were significantly lower in patients with SLE with renal damage than those without renal damage. Patients with SLE showed significantly increased methylation levels of Site1 and Site2 during remission compared with active stage. Conclusions The methylation level of IFI44L promoter can distinguish patients with SLE from healthy persons and other autoimmune diseases, and is a highly sensitive and specific diagnostic marker for SLE. PMID:26787370

Bonding at Compatible and Incompatible Amorphous Interfaces of Polystyrene and Poly(Methyl Methacrylate) Below the Glass Transition Temperature

DEFF Research Database (Denmark)

Boiko, Yuri M.; Lyngaae-Jørgensen, Jørgen

2004-01-01

Films of high-molecular-weight amorphous polystyrene (PS, M-w = 225 kg/mol, M-w/M-n = 3, T-g-bulk = 97degreesC, where T-g-bulk is the glass transition temperature of the bulk sample) and poly(methyl methacrylate) (PMMA, M-w = 87 kg/mol, M-w/M-n = 2, Tg-bulk = 109degreesC) were brought into contact...

Synthesis of [methyl-14C]crotonobetaine from DL-[methyl-14C]carnitine

International Nuclear Information System (INIS)

Loester, H.; Seim, H.

1996-01-01

The causes of carnitine deficiency syndromes are not completely understood, but decomposition of L-carnitine in vivo is likely to be involved. Carnitine is metabolized to γ-butyrobetaine, and crotonobetaine is probably an intermediate in this pathway. To validate experimentally the precursor-product relationship between the three physiologically occuring γ-betaines - L-carnitine, crotonobetaine, γ-butyrobetaine - labelling with stable or radioactive isotopes became necessary. Methyl-labelled carnitine isomers (L(-)-, D(+)- or DL-) or γ-butyrobetaine can be easily synthesized by methylation of 4-amino-3-hydroxybutyric acid isomers or 4-aminobutyric acid, respectively. Because of problems with the 4-aminocrotonic acid, we synthesized labelled crotonbetaine from labelled carnitine. Thus, DL-[methyl- 14 C]carnitine was dehydrated by reaction with concentrated sulfuric acid. After removal of the latter the products were separated and purified by ion exchange chromatography on DOWEX 50 WX8 (200 - 400 mesh) and gradient elution with hydrochloric acid. In addition to the labelled main product [methyl- 14 C]crotonobetaine (yield about 50 %), [methyl- 14 C]glycine betaine and [methyl- 14 C]acetonyl-trimethylammonium (ATMA) were formed. The end products were identified by combined thin layer chromatography/autoradiography and quantified by liquid scintillation counting. (Author)

Radiolytic stabilization of industrial poly(methyl methacrylate)

International Nuclear Information System (INIS)

Aquino, Katia Aparecida da Silva

2005-03-01

Poly(methyl methacrylate), PMMA, Acrigel, a Brazilian polymer, is used in the manufacture of medical supplies sterilisable by ionizing radiation. However, when PMMA is gamma-irradiated it undergoes main chain scissions, which promote molecular degradation causing reduction in its physical properties. Therefore, radiolytic stabilization of PMMA is important for to become it commercially radio sterilisable. In this work we investigated the radiolytic stabilization of PMMA by using HALS (Hindered Amine Light Stabilizer) additive, commercially used for photo and thermo oxidative stabilization of polymers. The investigation of the radiation-induced main chain scissions was carried out by viscometric method. The additive added to the polymer system at 0.3 % w/w promotes a molecular radioprotection of 61%. That means a reduction of G value (scissions/100 eV) from 2.6 to 1.0. In addition, the glassy transition temperature (Tg) of PMMA (no additive), significantly changed by radiation, does not change when PMMA (with additive) is irradiated. TGA analysis showed that the additive promotes thermal stability to the system, increasing decomposition temperature of PMMA. Spectroscopy analysis, FT-IR and RMN ( 1 H), showed that the radioprotector additive added to the system does not change the PMMA structure. Analysis on mechanical (tensile strength and elongation at break) and optical (yellowness index and refractive index) properties showed a good influence of the additive on polymer system. (author)

Modification of physical properties of poly(L-lactic acid by addition of methyl-β-cyclodextrin

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Toshiyuki Suzuki

2014-12-01

Full Text Available Poly(L-lactic acid (PLLA is a biodegradable plastic and one of the most famous plastics made from biobased materials. However, its physical strength is insufficient compared to general-purpose plastics. In this study, the effect of methylcyclodextrin (MeCD addition on the structure and physical properties, especially the drawing behavior, of PLLA was investigated. Through thermal analysis, it was found that MeCD addition lowers the crystallinity and enhances the mobility of PLLA. The sample containing approximately 17% MeCD was drawn to more than 1000% at 60 °C, although PLLA fractured at a strain of less than 100%. Differential scanning calorimetry (DSC-Raman in situ measurements also revealed decreases in the glass transition temperature (Tg, cold crystallization temperature (Tc, and melting point (Tm, and improvement in structural distribution with temperature. DSC-Raman measurements simultaneously supplied information about crystallinity and thermal properties. Thus, it was concluded that MeCD had high affinity for PLLA, and the addition of MeCD increased the amorphous component of PLLA and enhanced the drawability.

Poly(methyl methacrylate) and thiophene-coated single-walled carbon nanotubes for volatile organic compound discrimination

Science.gov (United States)

Muangrat, Worawut; Chodjarusawad, Thanawee; Maolanon, Rungroj; Pratontep, Sirapat; Porntheeraphat, Supanit; Wongwiriyapan, Winadda

2016-02-01

Poly(methyl methacrylate) (PMMA) and thiophene-coated single-walled carbon nanotubes (SWNTs) were fabricated for use in volatile organic compound (VOC) detection. Pristine SWNTs were separately coated with PMMA (PMMA/SWNTs) and thiophene (thiophene/SWNTs) by spin-coating. Pristine SWNTs showed the highest response to methanol, while PMMA/SWNTs enabled 5.4-fold improved dichloromethane detection and thiophene/SWNTs enabled 1.4-fold improved acetone detection compared with pristine SWNTs. The sensor response of PMMA/SWNTs to dichloromethane and that of thiophene/SWNTs to acetone can be attributed to the Hildebrand solubility parameter (HSP). The more similar the HSP, the higher the sensor response. The sensor response of pristine SWNTs to methanol is related to the diffusion coefficient and molecular size. The relationships between the vapor concentration and sensor response of PMMA/SWNTs to dichloromethane and thiophene/SWNTs to acetone are based on Henry’s adsorption isotherm, while that of pristine SWNTs to methanol is based on the Henry-clustering model. Principal component analysis (PCA) results show that dichloromethane, acetone, and methanol were successfully discriminated.

Phase behavior for the poly(alkyl methacrylate)+supercritical CO2+DME mixture at high pressures

International Nuclear Information System (INIS)

Choi, Yong-Seok; Chio, Sang-Won; Byun, Hun-Soo

2016-01-01

The phase behavior curves of binary and ternary system were measured for poly(alkyl methacrylate) in supercritical CO 2 , as well as for the poly(alkyl methacrylate)+dimethyl ether (DME) (or 1-butene) in CO 2 . The solubility curves are reported for the poly(alkyl methacrylate)+DME in supercritical CO 2 at temperature from (300 to 465) K and a pressure from (3.66 to 248) MPa. Also, The high-pressure static-type apparatus of cloud-point curve was tested by comparing the measured phase behavior data of the poly(methyl methacrylate) [PMMA]+CO 2 +20.0 and 30.4 wt% methyl methacrylate (MMA) system with literature data of 10.4, 28.8 and 48.4 wt% MMA concentration. The phase behavior data for the poly(alkyl methacrylate)+CO 2 +DME mixture were measured in changes of the pressure-temperature (p, T) slope and with DME concentrations. Also, the cloud-point pressure for the poly(alkyl methacrylate)+1- butene solution containing supercritical CO 2 shows from upper critical solution temperature (UCST) region to lower critical solution temperature (LCST) region at concentration range from (0.0 to 95) wt% 1-butene at below 455 K and at below 245MPa.

Preparation of poly （methyl methacrylate）／nanometer calcium carbonate composite by in-situ emulsion polymerization

Institute of Scientific and Technical Information of China (English)

史建明; 包永忠; 黄志明; 翁志学

2004-01-01

Methyl methacrylate (MMA) emulsion polymerization in the presence of nanometer calcium carbonate(nano-CaCO3) surface modified with γ-methacryloxypropyltrimethoxysilane (MPTMS) was carried out to prepare poly (methyl methacrylate) (PMMA)/nano-CaCO3 composite. The reaction between nano-CaCO3 and MPTMS, and the grafting of PMMA onto nano-CaCO3 were confirmed by infrared spectrum. The grafting ratio and grafting efficiency of PMMA on nano-CaCO3 modified with MPTMS were much higher than that on nano-CaCO3 modified with stearic acid. The grafting ratio of PMMA increased as the weight ratio between MMA and nano-CaCO3 increased, while the grafting efficiency of PMMA decreased. Transmission electron micrograph showed that nano-CaCO3 covered with PMMA was formed by in-situ emulsion polymerization.

Dynamics of poly(ethylene oxide) in a blend with poly(methyl methacrylate): A quasielastic neutron scattering and molecular dynamics simulations study

International Nuclear Information System (INIS)

Genix, A.-C.; Arbe, A.; Alvarez, F.; Colmenero, J.; Willner, L.; Richter, D.

2005-01-01

In this paper, we have addressed the question of the dynamic miscibility in a blend characterized by very different glass-transition temperatures, T g , for the components: poly(ethylene oxide) and poly(methyl methacrylate) (PEO/PMMA). The combination of quasielastic neutron scattering with isotopic labeling and fully atomistic molecular dynamics simulations has allowed us to selectively investigate the dynamics of the two components in the picosecond--10 nanoseconds scale at temperatures close and above the T g of the blend. The main focus was on the PEO component, i.e., that of the lowest T g , but first we have characterized the dynamics of the other component in the blend and of the pure PEO homopolymer as reference. In the region investigated, the dynamics of PMMA in the blend is strongly affected by the α-methyl rotation; an additional process detected in the experimental window 65 K above the blend-T g can be identified as the merged αβ process of this component that shows strong deviations from Gaussian behavior. On the other hand, pure PEO displays entropy driven dynamics up to very large momentum transfers. Such kind of motion seems to freeze when the PEO chains are in the blend. There, we have directly observed a very heterogeneous and moreover confined dynamics for the PEO component. The presence of the hardly moving PMMA matrix leads to the creation of little pockets of mobility where PEO can move. The characteristic size of such confined islands of mobility might be estimated to be of ≅1 nm. These findings are corroborated by the simulation study, which has been an essential support and guide in our data analysis procedure

Preparation and characterization of new biologically active polyurethane foams.

Science.gov (United States)

Savelyev, Yuri; Veselov, Vitali; Markovskaya, Ludmila; Savelyeva, Olga; Akhranovich, Elena; Galatenko, Natalya; Robota, Ludmila; Travinskaya, Tamara

2014-12-01

Biologically active polyurethane foams are the fast-developed alternative to many applications of biomedical materials. Due to the polyurethane structure features and foam technology it is possible to incorporate into their structure the biologically active compounds of target purpose via structural-chemical modification of macromolecule. A series of new biologically active polyurethane foams (PUFs) was synthesized with polyethers (MM 2500-5000), polyesters MM (500-2200), 2,4(2,6) toluene diisocyanate, water as a foaming agent, catalysts, foam stabilizers and functional compounds. Different functional compounds: 1,4-di-N-oxy-2,3-bis-(oxymethyl)-quinoxaline (DOMQ), partial sodium salt of poly(acrylic acid) and 2,6-dimethyl-N,N-diethyl aminoacetatanilide hydrochloride were incorporated into the polymer structure/composition due to the chemical and/or physical bonding. Structural peculiarities of PUFs were studied by FTIR spectroscopy and X-ray scattering. Self-adhesion properties of PUFs were estimated by measuring of tensile strength at break of adhesive junction. The optical microscopy method was performed for the PUF morphology studies. Toxicological estimation of the PUFs was carried out in vitro and in vivo. The antibacterial action towards the Gram-positive and Gram-negative bacteria (Escherichia coli ATC 25922, E. coli ATC 2150, Klebsiella pneumoniae 6447, Staphylococcus aureus 180, Pseudomonas aeruginosa 8180, Proteus mirabilis F 403, P. mirabilis 6054, and Proteus vulgaris 8718) was studied by the disc method on the solid nutrient. Physic-chemical properties of the PUFs (density, tensile strength and elongation at break, water absorption and vapor permeability) showed that all studied PUFs are within the operational requirements for such materials and represent fine-cellular foams. Spectral studies confirmed the incorporation of DOMQ into the PUF's macrochain. PUFs are characterized by microheterogeneous structure. They are antibacterially active, non

Radiation-induced graft copolymerization of methyl acrylate and acrylic acid onto rubber wood fiber

International Nuclear Information System (INIS)

Saliza Jam; Mansor Ahmad; Wan Md Zin Wan Yunus; Khairul Zaman Mohd Dahlan

2001-01-01

Graft copolymerization of methyl acrylate and acrylic acid monomers onto rubber wood fiber (RWF) was carried out by simultaneous radiation-induced technique. The parameters affecting the grafting reaction were investigated and the optimum conditions for both monomers obtained are as follows: impregnation time = 16 hours, total dose = 30 kGy, methanol : water ratio, 3:1, monomers concentration = 40 v/v % and sulphuric acid concentration = 0.1 mol/L. Fourier Transform Infrared (FTIR), thermogravimetry analysis (TGA), and scanning electron microscope (SEM) analyses used to characterize graft copolymers. The structural investigation by x-ray diffraction (XRD) shows the degree of crystallinity of rubber wood fiber decreased with the incorporation of poly(methyl acrylate) and poly(acrylic acid) grafts. (Author)

Synthesis of Ophiocerins from Non-Carbohydrate Sources

International Nuclear Information System (INIS)

Hong, Hui Jeong; Lee, Dong Min; Kang, Han Young

2010-01-01

Direct and unified synthetic routes to ophiocerin A, B, C, and D have been successfully developed. These syntheses are based on ring-closing metathesis and non-carbohydrate starting materials and are simpler and more efficient than the previous syntheses, as demonstrated in the case of ophiocerin B (2) (eleven steps from methyl α-D-glucopyranoside vs. four steps from 4-penten-2-ol) and ophiocerin A (1) (twelve steps from methyl α-D-glucopyranoside vs. three steps from 4-penten-2-ol). These routes will be useful for the practical synthesis of related natural products. Ophiocerins are comprised of four compounds isolated from the aqueous fungi Ophioceras venezuelense, each bearing a tetrahydropyran ring with an interesting array of substituents (Figure 1). Since substituted tetrahydropyran rings are found in many biologically important natural products, ophiocerins have attracted the attention of synthetic chemists

Effect of Amine-Functionalized MIL-53 Metal Organic Frameworks on the Performance of Poly(4-methyl-1-pentyne Membrane in CO2/CH4 Separation Gas Mixture

Directory of Open Access Journals (Sweden)

Reza Abedini

2015-06-01

Full Text Available The effect of NH2-MIL 53 metal organic framework (MOF on gas transport properties of poly(4-methyl-1-pentyne (PMP was investigated. Various characterization methods such as FTIR, DSC, SEM and gas adsorption test as well as a series of CO2/CH4 gas separation tests (i.e., pure and mixed gas test were conducted in order to determine the effect of ligand functionalization (–NH2 on the properties of the prepared mixed matrix membranes and their gas transport characteristics. The results of DSC showed that glass transition temperature (Tg increased by increasing NH2-MIL 53 loading. The SEM images also demonstrated that the NH2-MIL 53 particles were dispersed well in the PMP matrix with no noticeable agglomeration. The gas adsorption test of NH2-MIL 53 particles revealed there was a selective adsorption behavior with respect to CO2. It was also found that, incorporation of NH2-MIL 53 into the PMP resulted in an increase in gas permeability (especially towards CO2 and a higher CO2/CH4 selectivity. Adding 30 wt% NH2-MIL 53 into the polymer matrix increased CO2 permeability and CO2/CH4 selectivity of the mixed gas from 83.35 to 210.21 barrer and 7.61 to 19.88, respectively. Rising the temperature from 30 to 60°C led to the permeability increment of both CO2 and CH4 in the mixed gas test, while the CO2/CH4 selectivity decreased. Moreover, the results showed that amino groups required no regeneration and their performance did not decline during 120 h of permeation test. A comparison between the permeation data and those calculated from permeation models revealed that the Bruggeman model could fit the CO2 permeability data better than the Maxwell and Lewis models.

Preparation of superhydrophobic poly(methyl methacrylate)-silicon dioxide nanocomposite films

International Nuclear Information System (INIS)

Wang Jinyan; Chen Xinhua; Kang Yingke; Yang Guangbin; Yu Laigui; Zhang Pingyu

2010-01-01

Superhydrophobic poly(methyl methacrylate)-SiO 2 (coded as PMMA-SiO 2 ) nanocomposite films with micro-nanohierarchical structure were prepared via a simple approach in the absence of low surface-energy compounds. By spin-coating the suspension of hydrophobic silica (SiO 2 ) nanoparticles dispersed in PMMA solution, target nanocomposite films were obtained on glass slides. The wetting behavior of PMMA-SiO 2 nanocomposite films was investigated in relation to the dosage of SiO 2 nanoparticles dispersed in PMMA solution. It was found that hydrophilic PMMA film was transferred to superhydrophobic PMMA-SiO 2 nanocomposite films when hydrophobic SiO 2 nanoparticles were introduced into the PMMA solution at a high enough dosage (0.2 g and above). Resultant PMMA-SiO 2 nanocomposite films had a static water contact angle of above 162 o , showing promising applications in selfcleaning and waterproof for outer wall of building, outer covering for automobile, sanitary wares, and so forth.

Controlled release of 9-nitro-20(S)-camptothecin from methoxy poly(ethylene glycol)-poly(D,L-lactide) micelles

Energy Technology Data Exchange (ETDEWEB)

Gao, J M [College of Material Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Ming, J [Department of Medicament, The Second People' s Hospital of Sichuan, Chengdu 610041 (China); He, B; Gu, Z W; Zhang, X D [National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064 (China)], E-mail: zwgu@scu.edu.cn

2008-03-01

9-nitro-20(S)-camptothecin (9-NC) is a potent topoisomerase-I inhibitor, and it was applied for clinical trials in cancer treatment. However, the applications of 9-NC were limited by its poor solubility and instability. In order to overcome these disadvantages, 9-NC was encapsulated in amphiphilic copolymer micelles composed of methoxy poly(ethylene glycol)-b-poly(D,L-lactide) (mPEG-PDLLA, PELA). Three diblock copolymers with different PDLLA chain lengths were synthesized. The critical micelle concentration was varied from 10{sup -4} g L{sup -1} to 10{sup -2} g L{sup -1}. The 9-NC loaded micelles were nanospheres with diameters ranging from 30 nm to 60 nm. The relationship between the composition of copolymers and the drug loading content was discussed. The encapsulation of micelles improved the solubility of 9-NC greatly. The solubility of 9-NC in micelle M1 was about 250 times higher than that of 9-NC in a phosphate buffer solution (PBS). The stability of 9-NC in micelles was also promoted. After being incubated in PBS for 160 min, 80% of 9-NC in micelles existed as an active lactone form, while 85% of 9-NC in PBS were transferred to an inactive carboxylate salt form. The release experiments were carried out in PBS and the results showed that the release processes were controllable.

Surface-Initiated Atom Transfer Radical Polymerization of Magnetite Nanoparticles with Statistical Poly(tert-butyl acrylate-poly(poly(ethylene glycol methyl ether methacrylate Copolymers

Directory of Open Access Journals (Sweden)

Patcharin Kanhakeaw

2015-01-01

Full Text Available This work presented the surface modification of magnetite nanoparticle (MNP with poly[(t-butyl acrylate-stat-(poly(ethylene glycol methyl ether methacrylate] copolymers (P[(t-BA-stat-PEGMA] via a surface-initiated “grafting from” atom transfer radical polymerization (ATRP. Loading molar ratio of t-BA to PEGMA was systematically varied (100 : 0, 75 : 25, 50 : 50, and 25 : 75, resp. such that the degree of hydrophilicity of the copolymers, affecting the particle dispersibility in water, can be fine-tuned. The reaction progress in each step of the synthesis was monitored via Fourier transform infrared spectroscopy (FTIR. The studies in the reaction kinetics indicated that PEGMA had higher reactivity than that of t-BA in the copolymerizations. Gel permeation chromatography (GPC indicated that the molecular weights of the copolymers increased with the increase of the monomer conversion. Transmission electron microscopy (TEM revealed that the particles were spherical with averaged size of 8.1 nm in diameter. Dispersibility of the particles in water was apparently improved when the copolymers were coated as compared to P(t-BA homopolymer coating. The percentages of MNP and the copolymer in the composites were determined via thermogravimetric analysis (TGA and their magnetic properties were investigated via vibrating sample magnetometry (VSM.

Poly(ADP-ribosyl)ation of Methyl CpG Binding Domain Protein 2 Regulates Chromatin Structure*

Science.gov (United States)

Becker, Annette; Zhang, Peng; Allmann, Lena; Meilinger, Daniela; Bertulat, Bianca; Eck, Daniel; Hofstaetter, Maria; Bartolomei, Giody; Hottiger, Michael O.; Schreiber, Valérie; Leonhardt, Heinrich; Cardoso, M. Cristina

2016-01-01

The epigenetic information encoded in the genomic DNA methylation pattern is translated by methylcytosine binding proteins like MeCP2 into chromatin topology and structure and gene activity states. We have shown previously that the MeCP2 level increases during differentiation and that it causes large-scale chromatin reorganization, which is disturbed by MeCP2 Rett syndrome mutations. Phosphorylation and other posttranslational modifications of MeCP2 have been described recently to modulate its function. Here we show poly(ADP-ribosyl)ation of endogenous MeCP2 in mouse brain tissue. Consequently, we found that MeCP2 induced aggregation of pericentric heterochromatin and that its chromatin accumulation was enhanced in poly(ADP-ribose) polymerase (PARP) 1−/− compared with wild-type cells. We mapped the poly(ADP-ribosyl)ation domains and engineered MeCP2 mutation constructs to further analyze potential effects on DNA binding affinity and large-scale chromatin remodeling. Single or double deletion of the poly(ADP-ribosyl)ated regions and PARP inhibition increased the heterochromatin clustering ability of MeCP2. Increased chromatin clustering may reflect increased binding affinity. In agreement with this hypothesis, we found that PARP-1 deficiency significantly increased the chromatin binding affinity of MeCP2 in vivo. These data provide novel mechanistic insights into the regulation of MeCP2-mediated, higher-order chromatin architecture and suggest therapeutic opportunities to manipulate MeCP2 function. PMID:26772194

Biodegradable block poly(ester-urethane)s based on poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymers.

Science.gov (United States)

Ou, Wenfeng; Qiu, Handi; Chen, Zhifei; Xu, Kaitian

2011-04-01

A series of block poly(ester-urethane)s (abbreviated as PU3/4HB) based on biodegradable poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) segments were synthesized by a facile way of melting polymerization using 1,6-hexamethylene diisocyanate (HDI) as the coupling agent and stannous octanoate (Sn(Oct)(2)) as catalyst, with different 4HB contents and segment lengths. The chemical structure, molecular weight and distribution were systematically characterized by (1)H nuclear magnetic resonance spectrum (NMR), Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The thermal property was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The hydrophilicity was investigated by static contact angle of deionized water and CH(2)I(2). DSC curves revealed that the PU3/4HB polyurethanes have their T(g) from -25.6 °C to -4.3 °C, and crystallinity from 2.5% to 25.3%, being almost amorphous to semi-crystalline. The obtained PU3/4HBs are hydrophobic (water contact angle 77.4°-95.9°), and their surface free energy (SFE) were studied. The morphology of platelets adhered on the polyurethane film observed by scanning electron microscope (SEM) showed that platelets were activated on the PU3/4HB films which would lead to blood coagulation. The lactate dehydrogenase (LDH) assay revealed that the PU3/4HBs displayed higher platelet adhesion property than raw materials and biodegradable polymer polylactic acid (PLA) and would be potential hemostatic materials. Crystallinity degree, hydrophobicity, surface free energy and urethane linkage content play important roles in affecting the LDH activity and hence the platelet adhesion. CCK-8 assay showed that the PU3/4HB is non-toxic and well for cell growth and proliferation of mouse fibroblast L929. It showed that the hydrophobicity is an important factor for cell growth while 3HB content of the PU3/4HB is important for the cell proliferation. Through changing the

O-Alkylated heavy atom carbohydrate probes for protein X-ray crystallography: Studies towards the synthesis of methyl 2-O-methyl-L-selenofucopyranoside

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Roman Sommer

2016-12-01

Full Text Available Selenoglycosides are used as reactive glycosyl donors in the syntheses of oligosaccharides. In addition, such heavy atom analogs of natural glycosides are useful tools for structure determination of their lectin receptors using X-ray crystallography. Some lectins, e.g., members of the tectonin family, only bind to carbohydrate epitopes with O-alkylated ring hydroxy groups. In this context, we report the first synthesis of an O-methylated selenoglycoside, specifically methyl 2-O-methyl-L-selenofucopyranoside, a ligand of the lectin tectonin-2 from the mushroom Laccaria bicolor. The synthetic route required a strategic revision and further optimization due to the intrinsic lability of alkyl selenoglycosides, in particular for the labile fucose. Here, we describe a successful synthetic access to methyl 2-O-methyl-L-selenofucopyranoside in 9 linear steps and 26% overall yield starting from allyl L-fucopyranoside.

O-Alkylated heavy atom carbohydrate probes for protein X-ray crystallography: Studies towards the synthesis of methyl 2-O-methyl-L-selenofucopyranoside.

Science.gov (United States)

Sommer, Roman; Hauck, Dirk; Varrot, Annabelle; Imberty, Anne; Künzler, Markus; Titz, Alexander

2016-01-01

Selenoglycosides are used as reactive glycosyl donors in the syntheses of oligosaccharides. In addition, such heavy atom analogs of natural glycosides are useful tools for structure determination of their lectin receptors using X-ray crystallography. Some lectins, e.g., members of the tectonin family, only bind to carbohydrate epitopes with O-alkylated ring hydroxy groups. In this context, we report the first synthesis of an O -methylated selenoglycoside, specifically methyl 2- O -methyl-L-selenofucopyranoside, a ligand of the lectin tectonin-2 from the mushroom Laccaria bicolor . The synthetic route required a strategic revision and further optimization due to the intrinsic lability of alkyl selenoglycosides, in particular for the labile fucose. Here, we describe a successful synthetic access to methyl 2- O -methyl-L-selenofucopyranoside in 9 linear steps and 26% overall yield starting from allyl L-fucopyranoside.

8-Methoxypsoralen-nucleic acid photoreaction. Effect of methyl substitution on pyrone vs. furan photoaddition

International Nuclear Information System (INIS)

Kanne, D.; Rapoport, H.; Hearst, J.E.

1984-01-01

We have synthesized a series of 8-[3H]methoxypsoralens in which methyl and hydrogen are systematically varied at the 4- and 5'-positions. Analysis of the products resulting from the photoaddition of these four psoralens with the nucleic acid poly(dA-dT) reveals that the product distribution depends on the presence or absence of a 4-methyl substituent. Compounds with the 4-methyl group show an overwhelming preference (approximately 98%) for addition to the furan double bond, while compounds without the 4-methyl show a substantial amount (approximately 18%) of addition to the pyrone double bond

Cadmium Sulfide Quantum Dot Particles (CdSQD Dispersed in Poly Methyl Methacrylate as an Effective Gamma Counter for the Scintillation Detector

Directory of Open Access Journals (Sweden)

Askari Mohammad Bagher

2017-08-01

Full Text Available The synthetic material, cadmium sulfide quantum dot particles (CdSQD, using a hydrothermal method was dispersed in poly methyl methacrylate (PMM polymer. In order to study the synthesized quantum dot particles, X-ray diffraction (XRD and Fourier transform infrared spectroscopy (FTIR techniques were applied. Transmission electron microscopy (TEM and scanning electron microscopy (SEM images were also used to study the surface morphology of synthetic quantum dot particles. Energy-dispersive X-ray spectroscopy (EDX test was done for identification of constituent percent of prepared material. Optical properties of CdSQD particles were evaluated by UV-visible and photoluminescence spectroscopy (PL. Finally the capability of CdSQD particles dispersed in poly methyl methacrylate (CdSQD@PMM as a scintillator material was investigated by photomultiplier tube (PMT test. The result of PMT test along with statistical studies showed that the CdSQD@PMM can be applied as a crystalline promising material in the field of inorganic scintillator detectors regarding to the efficiency and economic aspects.

Luminescent Properties of Surface Functionalized BaTiO₃ Embedded in Poly(methyl methacrylate).

Science.gov (United States)

Requena, Sebastian; Lacoul, Srijan; Strzhemechny, Yuri M

2014-01-16

As-received BaTiO₃ nanopowders of average grain sizes 50 nm and 100 nm were functionalized by (3-aminopropyl)triethoxysilane (APTES) and mixed with poly(methyl methacrylate)/toluene solution. The nanocomposite solution was spin coated on Si substrates to form thin films. The photoluminescence spectrum of the pure powder was composed of a bandgap emission at 3.0 eV and multiple bands centered about 2.5 eV. Surface functionalization of the BaTiO₃ powder via APTES increases overall luminescence at room temperature while only enhancing bandgap emission at low-temperature. Polymer coating of the functionalized nanoparticles significantly enhances bandgap emissions while decreasing emissions associated with near-surface lattice distortions at 2.5 eV.

Surface biomimetic modification with laminin-loaded heparin/poly-L-lysine nanoparticles for improving the biocompatibility

Energy Technology Data Exchange (ETDEWEB)

Liu, Tao, E-mail: 11140021@hyit.edu.cn [Jiangsu Provincial Key Laboratory for Interventional Medical Devices, Huaiyin Institute of Technology, Huai' an (China); Hu, Youdong [Department of Geriatrics, The Affiliated Huai' an Hospital of Xuzhou Medical College, Huai' an (China); Tan, Jianying [Key Lab. of Advanced Technology for Materials of Chinese Education Ministry, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu (China); Liu, Shihui [Jiangsu Provincial Key Laboratory for Interventional Medical Devices, Huaiyin Institute of Technology, Huai' an (China); Chen, Junying [Key Lab. of Advanced Technology for Materials of Chinese Education Ministry, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu (China); Guo, Xin; Pan, Changjiang [Jiangsu Provincial Key Laboratory for Interventional Medical Devices, Huaiyin Institute of Technology, Huai' an (China); Li, Xia, E-mail: xial_li@qq.com [Department of Geriatrics, The Affiliated Huai' an Hospital of Xuzhou Medical College, Huai' an (China)

2017-02-01

Late thrombus and restenosis caused by delayed endothelialization and insufficient biocompatibility of polymer coating continue to be the greatest limitations of drug-eluting stents. In this study, based on the specific structure of vascular basement membrane, a novel biomimetic nano-coating was constructed by incorporating laminin into electrostatic-assembled heparin/poly-L-lysine nanoparticles. Alteration of heparin and poly-L-lysine concentration ratio in a certain range has no significantly influence nanoparticle size, uniformity and stability, but may affect the chemical property and subsequently the binding efficiency to dopamine-coated titanium surface. By use of this feature, four different nanoparticles were synthesized and immobilized on titanium surface for creating gradient nanoparticle binding density. According to in vitro biocompatibility evaluation, the nanoparticle modified surfaces were found to effectively block coagulation pathway and reduce thrombosis formation. Moreover, NP10L and NP15L modified surface with relatively low heparin exposing density (4.9 to 7.1 μg/cm2) showed beneficial effect in selective promoting EPCs and ECs proliferation, as well as stimulating cell migration and NO synthesis. - Highlights: • A novel laminin-loaded anticoagulant nanoparticle was prepared and used for titanium surface modification. • The nanoparticle binding density was adjustable by alteration the concentration ratio of heparin and poly-L-lysine. • In a certain range of NPs density, the surface was found to selectively direct platelet and vascular cells behavior.

Surface biomimetic modification with laminin-loaded heparin/poly-L-lysine nanoparticles for improving the biocompatibility

International Nuclear Information System (INIS)

Liu, Tao; Hu, Youdong; Tan, Jianying; Liu, Shihui; Chen, Junying; Guo, Xin; Pan, Changjiang; Li, Xia

2017-01-01

Late thrombus and restenosis caused by delayed endothelialization and insufficient biocompatibility of polymer coating continue to be the greatest limitations of drug-eluting stents. In this study, based on the specific structure of vascular basement membrane, a novel biomimetic nano-coating was constructed by incorporating laminin into electrostatic-assembled heparin/poly-L-lysine nanoparticles. Alteration of heparin and poly-L-lysine concentration ratio in a certain range has no significantly influence nanoparticle size, uniformity and stability, but may affect the chemical property and subsequently the binding efficiency to dopamine-coated titanium surface. By use of this feature, four different nanoparticles were synthesized and immobilized on titanium surface for creating gradient nanoparticle binding density. According to in vitro biocompatibility evaluation, the nanoparticle modified surfaces were found to effectively block coagulation pathway and reduce thrombosis formation. Moreover, NP10L and NP15L modified surface with relatively low heparin exposing density (4.9 to 7.1 μg/cm2) showed beneficial effect in selective promoting EPCs and ECs proliferation, as well as stimulating cell migration and NO synthesis. - Highlights: • A novel laminin-loaded anticoagulant nanoparticle was prepared and used for titanium surface modification. • The nanoparticle binding density was adjustable by alteration the concentration ratio of heparin and poly-L-lysine. • In a certain range of NPs density, the surface was found to selectively direct platelet and vascular cells behavior.

Scintillation detectors based on poly-2,4-dimethylstyrene: Structure peculiarities and radiation damage

International Nuclear Information System (INIS)

Gunder, O.A.; Voronkina, N.I.; Kopina, I.V.

1995-01-01

Scintillation detectors based on poly-2,4-dimethyl styrene (P-2,4-DMS) are studied. Investigated is the influence of two methyl groups present in the benzene ring on the energy, spectral and structural characteristics of the polymer. The said factors are assumed to result in the detectors high light output and radiation resistance. It is shown that under radiolysis (77 K) the radiation yield of the paramagnetic centers of P-2,4-DMS exceeds that of polystyrene (PST) by ∼ 1.5. Unlike PST film, the luminescence spectra of P-2,4-DMS are characterized by the presence of both excimer (320-340 nm) and monomer (292 nm) bands. Revealed are the distinction in the nature of the optical characteristics of macroradicals and the efficiency of energy transfer in gamma-irradiated PST and P-2,4-DMS scintillators. The relation between the super-molecular structure of the polymers and the interaction of their macroradicals with molecular O 2 is stated

3D FT-IR imaging spectroscopy of phase-separation in a poly(3-hydroxybutyrate)/poly(L-lactic acid) blend

Science.gov (United States)

Miriam Unger; Julia Sedlmair; Heinz W. Siesler; Carol Hirschmugl; Barbara Illman

2014-01-01

In the present study, 3D FT-IR spectroscopic imaging measurements were applied to study the phase separation of a poly(3-hydroxybutyrate) (PHB)/poly(L-lactic acid) (PLA) (50:50 wt.%) polymer blend film. While in 2D projection imaging the z-dependent information is overlapped, thereby complicating the analysis, FT-IR spectro-micro-tomography,...

X-ray investigations of sulfur-containing fungicides. IV. 4'-[[Benzoyl(4-chlorophenylhydrazono)methyl]sulfonyl]acetanilide and 4'-[[benzoyl(4-methoxyphenylhydrazono)methyl]sulfonyl]acetanilide.

Science.gov (United States)

Wolf, W M

2001-09-01

The conformations of the two approximately isomorphous structures 4'-[[benzoyl(4-chlorophenylhydrazono)methyl]sulfonyl]acetanilide, C(22)H(18)ClN(3)O(4)S, and 4'-[[benzoyl(4-methoxyphenylhydrazono)methyl]sulfonyl]acetanilide, C(23)H(21)N(3)O(5)S, are stabilized by resonance-assisted intramolecular hydrogen bonds linking the hydrazone moieties and sulfonyl groups. The stronger bond is observed in the former compound. The difference in electronic properties between the Cl atom and the methoxy group is too small to significantly alter the non-bonding interactions of the sulfonyl and beta-carbonyl groups.

EFFECTS OF ω-ACRYLOYL POLY(ETHYLENE OXIDE) MACROMONOMER ON EMULSIFIER-FREE EMULSION COPOLYMERIZATION OF METHYL METHACRYLATE AND n-BUTYL ACRYLATE

Institute of Scientific and Technical Information of China (English)

无

1998-01-01

Well-defined nonionic hydrophilic ω-acryloyl poly(ethylene oxide) macromonomer (PEO-A) has been prepared by living anionic polymerization of ethylene oxide with diphenyl methyl potassium as the initiator and acryloyl chloride as the reaction terminating agent. The polymer was characterized by FTIR and SEC. The emulsifier-free emulsion polymerization of methyl methacrylate (MMA) and n-butyl acrylate (BA) containing various concentrations of PEO-A was studied. In all cases stable emulsion coplymerizations of MMA and BA were obtained. The stabilizing effect was found to be dependent on the molecular weight and the feed amount of the macromonomer.

Study of the chain termination in the polymerization of seven-membered carbonate cyclic; Estudo da terminacao de cadeia na polymerizacao de carbonatos ciclicos de 7 membros

Energy Technology Data Exchange (ETDEWEB)

Carpentier, Jean-Francois [Laboratoire Catalyse et Organometalliques, CNRS - Universite de Rennes 1 - Sciences Chimiques de Rennes (France); Casagrande Junior, Osvaldo de; Gil, Marcelo Priebe [Laboratorio de Catalise Molecular, Instituto de Quimica, Universidade Federal do Rio Grande do Sul (Brazil)

2011-07-01

Methyl substituted seven-membered ring carbonate (7CC), namely 4-methyl-1,3-dioxepan-2-one ({alpha}-Me7CC) have been synthesized in good yield (up to 50%) upon cyclization of the corresponding {alpha}-diols issued from green renewable acid. ('Immortal') Ring-opening polymerization (iROP) of this monomer has been carried out using various catalysts combined with an alcohol acting as a co-initiator and a chain transfer agent. The Lewis acid Al(OTf){sub 3} or the organometallic complexes [(BDI{sup iPr})Zn(N(SiMe{sub 3}){sub 2})] ((BDI{sup iPr}) = 2-((2,6-diisopropylphenyl)amido)-4-((2,6- diisopropylphenyl)-imino)-2-pentene] and [(ONOO{sup tBu})Y(N(SiHMe{sub 2}){sub 2})(THF)] (ONOO{sup tBu} = amino-alkoxy-bis(phenolate)) successfully afforded the corresponding poly({alpha}-Me7CC) with quite good control and activities. Detailed microstructural analysis of the poly(a-Me7CC) using {sup 1}H and {sup 13}C NMR and MALDI-TOF-MS techniques revealed the higher regioselectivity -with preferential ring-opening at the most hindered oxygen-acyl O-C(O)O bond, i.e. close to the {alpha}-Me substituent- of the zinc-based system followed by the yttrium as compared to the lack of selectivity of the aluminum one, in the ROP of {alpha}-Me7CC. (author)

Study of the chain termination in the polymerization of seven-membered carbonate cyclic

International Nuclear Information System (INIS)

Carpentier, Jean-Francois; Casagrande Junior, Osvaldo de; Gil, Marcelo Priebe

2011-01-01

Methyl substituted seven-membered ring carbonate (7CC), namely 4-methyl-1,3-dioxepan-2-one (α-Me7CC) have been synthesized in good yield (up to 50%) upon cyclization of the corresponding α-diols issued from green renewable acid. ( I mmortal ) Ring-opening polymerization (iROP) of this monomer has been carried out using various catalysts combined with an alcohol acting as a co-initiator and a chain transfer agent. The Lewis acid Al(OTf) 3 or the organometallic complexes [(BDI iPr )Zn(N(SiMe 3 ) 2 )] ((BDI iPr ) = 2-((2,6-diisopropylphenyl)amido)-4-((2,6- diisopropylphenyl)-imino)-2-pentene] and [(ONOO tBu )Y(N(SiHMe 2 ) 2 )(THF)] (ONOO tBu = amino-alkoxy-bis( phenolate)) successfully afforded the corresponding poly(α-Me7CC) with quite good control and activities. Detailed microstructural analysis of the poly(a-Me7CC) using 1 H and 13 C NMR and MALDI-TOF-MS techniques revealed the higher regioselectivity -with preferential ring-opening at the most hindered oxygen-acyl O-C(O)O bond, i.e. close to the α-Me substituent- of the zinc-based system followed by the yttrium as compared to the lack of selectivity of the aluminum one, in the ROP of α-Me7CC. (author)

A sol-gel-modified poly(methyl methacrylate) electrophoresis microchip with a hydrophilic channel wall.

Science.gov (United States)

Chen, Gang; Xu, Xuejiao; Lin, Yuehe; Wang, Joseph

2007-01-01

A sol-gel method was employed to fabricate a poly(methyl methacrylate) (PMMA) electrophoresis microchip that contains a hydrophilic channel wall. To fabricate such a device, tetraethoxysilane (TEOS) was injected into the PMMA channel and was allowed to diffuse into the surface layer for 24 h. After removing the excess TEOS, the channel was filled with an acidic solution for 3 h. Subsequently, the channel was flushed with water and was pretreated in an oven to obtain a sol-gel-modified PMMA microchip. The water contact angle for the sol-gel-modified PMMA was approximately 27.4 degrees compared with approximately 66.3 degrees for the pure PMMA. In addition, the electro-osmotic flow increased from 2.13x10(-4) cm2 V(-1) s(-1) for the native-PMMA channel to 4.86x10(-4) cm2 V(-1) s(-1) for the modified one. The analytical performance of the sol-gel-modified PMMA microchip was demonstrated for the electrophoretic separation of several purines, coupled with amperometric detection. The separation efficiency of uric acid increased to 74,882.3 m(-1) compared with 14,730.5 m(-1) for native-PMMA microchips. The result of this simple modification is a significant improvement in the performance of PMMA for microchip electrophoresis and microfluidic applications.

New Linear and Star-Shaped Thermogelling Poly([R]-3-hydroxybutyrate) Copolymers.

Science.gov (United States)

Barouti, Ghislaine; Liow, Sing Shy; Dou, Qingqing; Ye, Hongye; Orione, Clément; Guillaume, Sophie M; Loh, Xian Jun

2016-07-18

The synthesis of multi-arm poly([R]-3-hydroxybutyrate) (PHB)-based triblock copolymers (poly([R]-3-hydroxybutyrate)-b-poly(N-isopropylacrylamide)-b-[[poly(methyl ether methacrylate)-g-poly(ethylene glycol)]-co-[poly(methacrylate)-g-poly(propylene glycol)

Enhancement of the interface in poly(L-lactide) and poly(propylidene carbonate) blends by introducing of poly(L-lactide)-grafted graphene oxide to improve mechanical properties

Science.gov (United States)

Li, Qi; Qin, Shengxue; Tian, Xiujuan; Chen, Xueyang; Chen, Yunlei; Niu, Yanhua; Zhao, Lifen

2018-03-01

Enhancement of the interfacial structure has great significances in achieving polymer blends with high mechanical performance. To improve the mechanical properties of poly(L-lactide) (PLLA)/poly(propylidene carbonate) (PPC) blends, the covalent functionalized graphene oxide by PLLA chains (PLLA-g-GO) was synthesized by a two-step strategy. It could migrate from the thermally preferred PPC phase to the interfaces of PLLA and PPC and promote the formation of a network-like structure. As a consequence, the tensile strength and elongation at break were both improved. Furthermore, the PLLA-g-GO located at the interface could induce the crystallization at the boundary, which brought the significant improvement of the tensile strength and elongation at break. This result may be beneficial for designing high-performance PLLA materials.

Catalytic cracking of iso-hexene over sapo-34 catalyst

International Nuclear Information System (INIS)

Nawaz, Z.; Shu, Q.

2009-01-01

The catalytic cracking of model feed compound, iso-hexene (2-methyl-1-pentene) was experimentally studied over 100% pure SAPO-34 zeolite catalyst. The critical focus was given to obtain maximum propylene selectivity. The product distributions were analyzed at temperature between 450-600 degree C. time-on-stream (TOS) from 1 to 5 min. and at WHSV = 7.9 h/sub -1/ The reaction behavior was quantified on both direct and indirect carbenium ion mechanisms owing to catalyst's small pore diameter with respect to 2-methyl-l-pentene kinetic diameter. The propylene yield and selectivity obtained was 41.2% and 43.1% respectively. with higher overall olefins selectivity 90.3%. The small pore size and week surface acid sites of 1000 percent pure SAPO-34 catalyst were found to be suitable for light olefins production and eliminate chances of bimolecular reactions. It was observed that both conversion and selectivity were strongly effected by TOS, as coke precursors become dominant and deactivate catalyst at higher TOS. (author)

DNA Methylation and Methylation Polymorphism in Genetically Stable In vitro Regenerates of Jatropha curcas L. Using Methylation-Sensitive AFLP Markers.

Science.gov (United States)

Rathore, Mangal S; Jha, Bhavanath

2016-03-01

The present investigation aimed to evaluate the degree and pattern of DNA methylation using methylation-sensitive AFLP (MS-AFLP) markers in genetically stable in vitro regenerates of Jatropha curcas L.. The genetically stable in vitro regenerates were raised through direct organogenesis via enhanced axillary shoot bud proliferation (Protocol-1) and in vitro-derived leaf regeneration (Protocol-2). Ten selective combinations of MS-AFLP primers produced 462 and 477 MS-AFLP bands in Protocol-1 (P-1) and Protocol-2 (P-2) regenerates, respectively. In P-1 regenerates, 15.8-31.17 % DNA was found methylated with an average of 25.24 %. In P-2 regenerates, 15.93-32.7 % DNA was found methylated with an average of 24.11 %. Using MS-AFLP in P-1 and P-2 regenerates, 11.52-25.53 % and 13.33-25.47 % polymorphism in methylated DNA was reported, respectively. Compared to the mother plant, P-1 regenerates showed hyper-methylation while P-2 showed hypo-methylation. The results clearly indicated alternation in degree and pattern of DNA methylation; hence, epigenetic instability in the genetically stable in vitro regenerates of J. curcas, developed so far using two different regeneration systems and explants of two different origins. The homologous nucleotide fragments in genomes of P-1 and P-2 regenerates showing methylation re-patterning might be involved in immediate adaptive responses and developmental processes through differential regulation of transcriptome under in vitro conditions.

Chemical synthesis of guanosine diphosphate mannuronic acid (GDP-ManA) and its C-4-O-methyl and C-4-deoxy congeners.

Science.gov (United States)

Zhang, Qingju; Howell, P Lynne; Overkleeft, Herman S; Filippov, Dmitri V; van der Marel, Gijsbert A; Codée, Jeroen D C

2017-10-10

Described is the first synthesis of guanosine diphosphate mannuronic acid (GDP-ManA), the sugar donor used by algae and bacteria for the production of alginate, an anionic polysaccharide composed of β-d-mannuronic acid (ManA) and α-l-guluronic acid (GulA). Understanding the biosynthesis of these polyanionic polysaccharides on the molecular level, opens up avenues to use and modulate the biosynthesis machinery for biotechnological and therapeutic applications. The synthesis reported here delivers multi-milligram amounts of the GDP-ManA donor that can be used to study the polymerase (Alg8 in Pseudomonas aeruginosa) that generates the poly-ManA chain. Also reported is the assembly of two close analogues of GDP-ManA: the first bears a C-4-O-methyl group, while the second has been deoxygenated at this position. Both molecules may be used as "chain stoppers" in future enzymatic ManA polymerisation reactions. The crucial pyrophosphate linkage of the GDP-mannuronic acids has been constructed by the phosphorylation of the appropriate ManA-1-phosphates with a guanosine phosphoramidite. Copyright © 2017 Elsevier Ltd. All rights reserved.

Investigation of in-situ poly(lactic acid)/soy protein concentrate composites: Composite preparation, properties and foam application development

Science.gov (United States)

Liu, Bo

2011-12-01

In this study, soy protein (SP), the residue of oil crushing, was used for preparation of value-added thermoplastics. Novel poly(lactic acid) (PLA)/soy protein concentrate (SPC) blends were investigated and foaming of the resulting blends was developed. PLA/SPC blends were prepared by twin-screw extrusion and test specimens by injection molding. Unlike the practice elsewhere SP was used as a filler in mixing with other polymers, SPC was processed as a plastic component in blending process in this work. Processing SPC as plastic component, water played an important role in terms of the deformability and the morphology of SP thus the properties of the blends. Plasticization of SP, compatibilization of the blends and structure-property relationship of the PLA/SPC blends were studied. In the literature water and glycerol were often used together in preparing SP plastics or plastic blends, but this study found that this traditional combination did not provide the best results in terms of morphology and mechanical properties. Water is only recommended in plasticizing SP in the blends. This study showed water as a plasticizer was a domain factor on control of morphology and properties of PLA/SPC blends. The due to the evaporation of water after extrusion, SP domain lost its deformability thus resulted in in-situ composites. Interconnected SPC phase structure was achieved by control water content in the pre-formulated SPC and SPC content in the blends. A novel dual compatibilization method was developed to improve the properties of PLA/SPC blends. Poly(2-ethyl-2-oxazoline) was used to improve the dispersion of SPC in the blending stage, and polymeric methylene diphenyl diisocyanate was used to improve the interfacial adhesion between SPC and PLA in the subsequent processing. The result showed excellent mechanical properties and improved thermal properties of PLA/SPC blends. Using processing aids is an effective way to decrease processing temperature and thermal degradation

Application of extrusion-cooking technique for foamed starch-based materials

Directory of Open Access Journals (Sweden)

Combrzyński Maciej

2018-01-01

Full Text Available Foamed materials are widely used, mainly as a protection objects during transport of various products. Traditionally foams are produced from plastics so they are very difficult for waste management. It is the challenge for many scientific centres to develop a technology for the production of bio-based materials which can be rapidly decomposed. The task for the researcher is to obtain a relatively cheap, easy to use and completely biodegradable materials. The aim of this work was the selection of the main raw materials, functional additives and process parameters to obtain the most effective parameters of extrusion-cooking process for foamed starch-based materials. Properties of the products and processing costs were taken into account. During the study, the extrusion-cooking process was performed under various conditions: temperature, humidity, type of the die, screw rotational speed, various raw materials and additives blends. The best results were obtained for mixtures based on potato starch and with addition the foaming agent Plastron foam PDE and poly(vinyl alcohol PVA.

The thermal degradation of poly(iso-butyl methacrylate and poly(sec-butyl methacrylate

Directory of Open Access Journals (Sweden)

IVANKA G. POPOVIC

2000-12-01

Full Text Available The non-oxidative thermal degradation of poly(iso-butyl methacrylate and poly(sec-butyl methacrylate was investigated by studying changes in the polymer residue. Due to the different number of b-hydrogens in their ester substituents, these two polymeric isomers behave differently when subjected to elevated temperatures. Poly(iso-butyl methacrylate degrades quantitatively by depolymerisation with zip lengths of the same order of magnitude as those of poly(methyl methacrylate. Poly(sec-butyl methacrylate degrades by a combined degradation mechanism of depolymerisation and de-esterification. De-esterification becomes a significant thermolysis route at temperatures higher than 240°C.

Synthesis and characterizations of CoPt nanoparticles supported on poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) functionalized multi-walled carbon nanotubes with superior activity for NaBH{sub 4} hydrolysis

Energy Technology Data Exchange (ETDEWEB)

Wang, Xiao; Zhao, Yanchun, E-mail: yanchunzhao@aliyun.com; Peng, Xinglan; Wang, Jing; Jing, Chen; Tian, Jianniao, E-mail: birdtjn@sina.com

2015-10-15

Highlights: • Simple strategy for the synthesis of CoPt-PEDOT:PSS/MWCNTs. • PEDOT:PSS as a modifier of MWCNTs can improve the particles dispersion. • Superior catalytic activities for the NaBH{sub 4} hydrolysis reaction. - Abstract: We present here a facile strategy for synthesis of CoPt nanoparticles supported on poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) functionalized multi-walled carbon nanotubes (MWCNTs). The as-prepared CoPt-PEDOT:PSS/MWCNT catalyst was characterized with UV–vis spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron. The well-supported and low-Pt-content nanostructure catalyst exhibits superior catalytic activity for the NaBH{sub 4} hydrolysis reaction with a 47.3 kJ mol{sup −1} of activation energy. The maximum hydrogen generation rate is 6900 mL min{sup −1} g{sup −1} at 298 K.

Synthesis and characterization of thermally stable poly(amide-imide-montmorillonite nanocomposites based on bis(4-carboxyphenyl-N,N'-pyromellitimide acid

Directory of Open Access Journals (Sweden)

M. Hajibeygi

2013-04-01

Full Text Available Two new poly(amide-imide-montmorillonite reinforced nanocomposites containing bis(4-carboxyphenyl-N,N'-pyromellitimide acid moiety in the main chain were synthesized by a convenient solution intercalation technique. Poly(amide-imide (PAI as a source of polymer matrix was synthesized by the direct polycondensation reaction of bis(4-carboxyphenyl-N,N'-pyromellitimide acid with 4,4'-diamino diphenyl sulfone in the presence of triphenyl phosphite (TPP, CaCl2, pyridine and N-methyl-2-pyrrolidone (NMP. Morphology and structure of the resulting PAI-nanocomposite films with 10 and 20% silicate particles were characterized by FT-IR spectroscopy, X-ray diffraction (XRD and scanning electron microscopy (SEM. The effect of clay dispersion and the interaction between clay and polymeric chains on the properties of nanocomposites films were investigated by using UV-Vis spectroscopy, thermal gravimetry analysis (TGA and water uptake measurements.DOI: http://dx.doi.org/10.4314/bcse.v27i1.10

The polymer gel electrolyte based on poly(methyl methacrylate) and its application in quasi-solid-state dye-sensitized solar cells

International Nuclear Information System (INIS)

Yang Hongxun; Huang Miaoliang; Wu Jihuai; Lan Zhang; Hao Sancun; Lin Jianming

2008-01-01

Using poly(methyl methacrylate) as polymer host, ethylene carbonate, 1,2-propanediol carbonate and dimethyl carbonate as organic mixture solvents, sodium iodide and iodine as source of I - /I 3 - , a polymer gel electrolyte PMMA-EC/PC/DMC-NaI/I 2 with ionic conductivity of 6.89 mS cm -1 was prepared. Based on the polymer gel electrolyte, a quasi-solid-state dye-sensitized solar cell (DSSC) was fabricated. The quasi-solid-state DSSC possessed a good long-term stability and a light-to-electrical energy conversion efficiency of 4.78% under irradiation of 100 mW cm -2 simulated sunlight, which is almost equal to that of DSSC with a liquid electrolyte

L-leucine methyl ester stimulates insulin secretion and islet glutamate dehydrogenase

DEFF Research Database (Denmark)

Knudsen, P; Kofod, Hans; Lernmark, A

1983-01-01

Column perifusion of collagenase-isolated mouse pancreatic islets was used to study the dynamics of insulin release in experiments lasting for several hours. The methyl esters of L-leucine and L-arginine were synthesized. Whereas L-arginine methyl ester (L-arginine OMe) had no effect, L-leucine OMe...... stimulated the release of insulin. The effect of L-leucine OMe was maximal at 5 mmol/liter. Whereas the Km for glucose-stimulated insulin release was unaffected by 1 mmol/liter L-leucine OMe, the maximal release of D-glucose was increased by the amino acid derivative that appeared more effective than L......-leucine. L-Leucine OMe was also a potent stimulus of insulin release from the perfused mouse pancreas. In the presence of 10 mmol/liter L-glutamine, 1 mmol/liter L-leucine OMe induced a 50- to 75-fold increase in insulin release. A similar stimulatory effect was also observed in column-perifused RIN 5F cells...

Metallocene-catalyzed ethylene−α-olefin isomeric copolymerization: A perspective from hydrodynamic boundary layer mass transfer and design of MAO anion

KAUST Repository

Adamu, Sagir; Atiqullah, Muhammad; Malaibari, Zuhair O.; Al-Harthi, Mamdouh A.; Emwas, Abdul-Hamid M.; Ul-Hamid, Anwar

2015-01-01

-catalyzed ethylene polymerization. This approach was illustrated by conducting homo- and isomeric copolymerization of ethylene with 1-hexene and 4-methyl-1-pentene in the presence of bis(n-butylcyclopentadienyl) zirconium dichloride (nBuCp)2ZrCl2, using (i) MAO anion

Comparative assessment of poly (D,L-lactide-co-glycolide ...

African Journals Online (AJOL)

... are modified by CTAB and chitosan. Modification with chitosan yields PLGA nanoparticles with higher DNA adsorption and transfection with lower cytotoxicity. Keywords: Chitosan, cetyltrimethyl ammonium bromide (CTAB), Nanoparticle, Poly (D,L-lactide-coglycolide) PLGA, Plasmid DNA adsorption, Gene therapy ...

A Polymer Electrolyte for Dye-Sensitized Solar Cells Based on a Poly(Polyvinylidenefluoride-Co-Hexafluoropropylene)/Hydroxypropyl Methyl Cellulose Blend

Science.gov (United States)

Won, Lee Ji; Kim, Jae Hong; Thogiti, Suresh

2018-03-01

A novel polymer blend electrolyte for dye-sensitized solar cells (DSSCs) was synthesized by quasi-solidifying a liquid-based electrolyte containing an iodide/triiodide redox couple and supporting salts with a mixture of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and indigenous hydroxypropyl methyl cellulose (HPMC). A high ionic conductivity of 8.8 × 10-4 S cm-1 was achieved after introducing 5 wt% of HPMC with respect to the weight of PVDH-HFP. DSSCs were fabricated using gel polymer blend electrolytes, and the J-V characteristics of the fabricated devices were analyzed. Under optimal conditions, the photovoltaic conversion efficiency of cells with the novel HPMC-blended gel electrolyte (5.34%) was significantly greater than that of cells without HPMC (3.97%).

Microporous poly(acrylonitrile-methyl methacrylate) membrane as a separator of rechargeable lithium battery

International Nuclear Information System (INIS)

Zhang, S.S.; Ervin, M.H.; Xu, K.; Jow, T.R.

2004-01-01

We studied microporous poly(acrylonitrile-methyl methacrylate), AMMA, membrane as the separator of Li/LiMn 2 O 4 cell. The porous AMMA membrane was prepared by the phase inversion method with N,N-dimethylformamide (DMF) as the solvent and water as the non-solvent. We observed that morphology of the resulting membrane was strongly affected by the concentration of polymer solution: low concentration produced finger-like pores with dense skin on two surfaces of the membrane, while high concentration yielded open voids with dense layer on the other surface of the membrane. Regardless of their morphology, both membranes could be rapidly wetted by the liquid electrolyte (1.0 m LiBF 4 dissolved in 1:3 wt.% mixture of ethylene carbonate (EC) and γ-butyrolactone (GBL)), and could be swollen at elevated temperatures, which resulted in the formation of a microporous gel electrolyte (MGE). It was shown that the resulting MGE not only had high ionic conductivity and but also had good compatibility with metal lithium even at 60 deg. C. Cyclic voltammetric test showed that the MGE had an electrochemical window of 4.9 V versus Li + /Li. At room temperature, the Li/MGE/LiMn 2 O 4 cell showed excellent cycliability with a specific capacity of 121-125 mA h g -1 LiMn 2 O 4 . It was shown that even at 60 deg. C good mechanical strength of the MGE remained. Therefore, the MGE is suitable for the application of battery separator at elevated temperatures

Genipin-cross-linked poly(L-lysine)-based hydrogels: synthesis, characterization, and drug encapsulation.

Science.gov (United States)

Wang, Steven S S; Hsieh, Ping-Lun; Chen, Pei-Shan; Chen, Yu-Tien; Jan, Jeng-Shiung

2013-11-01

Genipin-cross-linked hydrogels composed of biodegradable and pH-sensitive cationic poly(L-lysine) (PLL), poly(L-lysine)-block-poly(L-alanine) (PLL-b-PLAla), and poly(L-lysine)-block-polyglycine (PLL-b-PGly) polypeptides were synthesized, characterized, and used as carriers for drug delivery. These polypeptide hydrogels can respond to pH-stimulus and their gelling and mechanical properties, degradation rate, and drug release behavior can be tuned by varying polypeptide composition and cross-linking degree. Comparing with natural polymers, the synthetic polypeptides with well-defined chain length and composition can warrant the preparation of the hydrogels with tunable properties to meet the criteria for specific biomedical applications. These hydrogels composed of natural building blocks exhibited good cell compatibility and enzyme degradability and can support cell attachment/proliferation. The evaluation of these hydrogels for in vitro drug release revealed that the controlled release profile was a biphasic pattern with a mild burst release and a moderate release rate thereafter, suggesting the drug molecules were encapsulated inside the gel matrix. With the versatility of polymer chemistry and conjugation of functional moieties, it is expected these hydrogels can be useful for biomedical applications such as polymer therapeutics and tissue engineering. Copyright © 2013 Elsevier B.V. All rights reserved.

Strengthening of Poly Methyl Methacrylate (PMMA) through Electron Irradiation

Energy Technology Data Exchange (ETDEWEB)

Yoo, Sung Ho; Lim, Hyung San; Ha, Jun Mok; Cho, Sung Oh [KAIST, Daejeon (Korea, Republic of)

2015-05-15

Poly Methyl Methacrylate (PMMA) was previously known to show the deteriorating mechanical properties when irradiated with electrons. This is true for low electron irradiation does, but it was found, through experimentation, that at high irradiation dose, PMMA demonstrates improved mechanical properties. With enough electron irradiation dose, the scissions can form new links amongst one another to achieve stability that surpasses that of the PMMA in pre-irradiation treatment state. With higher irradiation dosage and beam strength, hardness of irradiated PMMA could be increased to a much greater extent. Electrons with 50keV of energy can only penetrate around 30 μm of PMMA, thus increasing the beam energy could potentially allow for hardening of not just the surface of the PMMA samples, but the whole samples themselves. Furthermore, Pencil Hardness Test is a method to roughly analyze a material's hardness and does not provide an accurate feedback on the mechanical properties of the material of interest. Hence, a more thorough and effective method of measuring data from the use of equipment such as IZOD Impact Tester, Strain-Stress Tester and Haze Meter will be utilized in the future.

Radiolytic stabilization of poly(methyl methacrylate) using commercial additives

International Nuclear Information System (INIS)

Aquino, Katia Aparecida da Silva

2000-04-01

Poly(methyl methacrylate), PMMA, Acrigel, a Brazilian polymer, is used in the manufacture of medical supplies sterelizable by ionizing radiation. However, when PMMA is gamma-irradiated it undergoes main chain scissions, which promote molecular degradation causing reduction in its mechanical properties. Therefore, radiolytic of PMMA is important for it to become commercially radiosterizable. In this work some commercial additives, originally used in photo-and thermo-oxidate stabilization of polymers, were tested. Only two additives, type HALS (Hindered Amine Light Stabilizer), denoted Scavenger, showed a good protective quality. The investigation of radiation-induced main scissions was carried out by viscosimetric method. The most effective additive, added to the polymer system at 0.3 w/w%, promotes a great molecular radioprotection of 93%. That means a reduction of G-value (scissions/100 eV) from 0.611 to 0.053. In addition, the glassy transition temperature (T g ) of PMMA (no additive) significantly changed by radiation does not change when PMMA (with additive) is irradiated. The spectroscopy analysis, FT-IR and NMR ( 1 H), showed that the radioprotector added to the system does not change the PMMA structure. (author)

Water-enhanced adhesion at interface in immiscible bilayer film of polystyrene and poly(methyl methacrylate)

International Nuclear Information System (INIS)

Harada, M; Koga, T; Fukumori, K; Sugiyama, J; Geue, T

2014-01-01

From nano-scratch tests, strong interfacial adhesion has been found for polystyrene (PS) and poly(methyl methacrylate) (PMMA) bilayer films prepared by a water floating (WF) method, while a PS layer on a PMMA film produced by a spin coating (SC) method peels off easily at the interface. Neutron reflectivity measurements demonstrated a clear difference in the interfacial width (σ) between the two bilayers; σ = 9 nm for the film obtained by the WF method, whereas σ = 5 nm for that by the SC method. Plasticization of the films by water would be responsible for broadening of the interface to enhance adhesion strength.

Quaternized poly(methyl methacrylate-co-butyl acrylate-co-vinylbenzyl chloride) membrane for alkaline fuel cells

Energy Technology Data Exchange (ETDEWEB)

Luo, Yanting; Guo, Juchen; Wang, Chunsheng [Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD 20742 (United States); Chu, Deryn [Sensors and Electron Device Directorate, U.S. Army Research Laboratory, Adelphi, MD 20783 (United States)

2010-06-15

Instead of modification of pre-existing polymers, a new route of preparation of polyelectrolyte OH{sup -} conductive membranes via copolymerization of selected functional monomers was reported in this study. A random copolymer of poly(methyl methacrylate-co-butyl acrylate-co-vinylbenzyl chloride) was synthesized via copolymerization, which was followed by quaternization and membrane casting. The intrinsic OH{sup -} conductivity of the free-standing polyelectrolyte membranes can reach 8.2 x 10{sup -3} S cm{sup -1} at 80 C. The alkaline fuel cells using copolymer polyelectrolytes demonstrated the feasibility of the preparation concept of these membranes. (author)

3D scaffolds from vertically aligned carbon nanotubes/poly(methyl methacrylate) composites via atom transfer radical polymerization

Energy Technology Data Exchange (ETDEWEB)

Tebikachew, Behabtu; Magina, Sandra [CICECO, Department of Chemistry, University of Aveiro (Portugal); Mata, Diogo; Oliveira, Filipe J.; Silva, Rui F. [CICECO, Department of Materials and Ceramic Engineering, University of Aveiro (Portugal); Barros-Timmons, Ana, E-mail: anabarros@ua.pt [CICECO, Department of Chemistry, University of Aveiro (Portugal)

2015-01-15

Vertically aligned carbon nanotubes (VACNTs) synthesized by Thermal Chemical Vapour Deposition (TCVD) were modified using an Ar:O{sub 2} (97:3) plasma to generate oxygen-containing functional groups on the surface for subsequent modification. X-ray photo-emission spectroscopy (XPS) and micro-Raman analyses confirmed the grafting of those functional groups onto the surface of the nanotubes as well as the removal of amorphous carbon produced and deposited on the VACNT forests during the CVD process. The plasma treated VACNT forests were further modified with 2-bromo-2-methylpropionyl bromide, an atom transfer radical polymerization (ATRP) initiator, to grow poly(methyl methacrylate) (PMMA) chains from the forests via ATRP. Scanning transmission electron microscopy (STEM) of the ensuing VACNT/PMMA composites confirmed the coating of the nanotube forests with the PMMA polymer. 3D scaffolds of polymeric composites with honeycomb like structure were then obtained. Compressive tests have shown that the VACNT/PMMA composite has higher compressive strength than the pristine forest. - Highlights: • Vertically aligned carbon nanotubes (VACNTs) were synthesized and plasma modified. • X-ray photo-emission and Raman spectroscopies confirmed the VACNTs modification. • Poly(methyl methacrylate) chains were grown via ATRP from the VACNTs. • STEM of the VACNT/PMMA composites confirmed that PMMA surrounds the nanotubes. • VACNT/PMMA composite has higher compressive strength compared to the pristine forest.

3D scaffolds from vertically aligned carbon nanotubes/poly(methyl methacrylate) composites via atom transfer radical polymerization

International Nuclear Information System (INIS)

Tebikachew, Behabtu; Magina, Sandra; Mata, Diogo; Oliveira, Filipe J.; Silva, Rui F.; Barros-Timmons, Ana

2015-01-01

Vertically aligned carbon nanotubes (VACNTs) synthesized by Thermal Chemical Vapour Deposition (TCVD) were modified using an Ar:O 2 (97:3) plasma to generate oxygen-containing functional groups on the surface for subsequent modification. X-ray photo-emission spectroscopy (XPS) and micro-Raman analyses confirmed the grafting of those functional groups onto the surface of the nanotubes as well as the removal of amorphous carbon produced and deposited on the VACNT forests during the CVD process. The plasma treated VACNT forests were further modified with 2-bromo-2-methylpropionyl bromide, an atom transfer radical polymerization (ATRP) initiator, to grow poly(methyl methacrylate) (PMMA) chains from the forests via ATRP. Scanning transmission electron microscopy (STEM) of the ensuing VACNT/PMMA composites confirmed the coating of the nanotube forests with the PMMA polymer. 3D scaffolds of polymeric composites with honeycomb like structure were then obtained. Compressive tests have shown that the VACNT/PMMA composite has higher compressive strength than the pristine forest. - Highlights: • Vertically aligned carbon nanotubes (VACNTs) were synthesized and plasma modified. • X-ray photo-emission and Raman spectroscopies confirmed the VACNTs modification. • Poly(methyl methacrylate) chains were grown via ATRP from the VACNTs. • STEM of the VACNT/PMMA composites confirmed that PMMA surrounds the nanotubes. • VACNT/PMMA composite has higher compressive strength compared to the pristine forest

Nanostructured Double Hydrophobic Poly(Styrene-b-Methyl Methacrylate) Block Copolymer Membrane Manufactured Via Phase Inversion Technique

KAUST Repository

Karunakaran, Madhavan; Shevate, Rahul; Peinemann, Klaus-Viktor

2016-01-01

In this paper, we demonstrate the formation of nanostructured double hydrophobic poly(styrene-b-methyl methacrylate) (PS-b-PMMA) block copolymer membranes via state-of-the-art phase inversion technique. The nanostructured membrane morphologies are tuned by different solvent and block copolymer compositions. The membrane morphology has been investigated using FESEM, AFM and TEM. Morphological investigation shows the formation of both cylindrical and lamellar structures on the top surface of the block copolymer membranes. The PS-b-PMMA having an equal block length (PS160K-b-PMMA160K) exhibits both cylindrical and lamellar structures on the top layer of the asymmetric membrane. All membranes fabricated from PS160K-b-PMMA160K shows an incomplete pore formation in both cylindrical and lamellar morphologies during the phase inversion process. However, PS-b-PMMA (PS135K-b-PMMA19.5K) block copolymer having a short PMMA block allowed us to produce open pore structures with ordered hexagonal cylindrical pores during the phase inversion process. The resulting PS-b-PMMA nanostructured block copolymer membranes have pure water flux from 105-820 l/m2.h.bar and 95% retention of PEG50K

Nanostructured Double Hydrophobic Poly(Styrene-b-Methyl Methacrylate) Block Copolymer Membrane Manufactured Via Phase Inversion Technique

KAUST Repository

Karunakaran, Madhavan

2016-03-11

In this paper, we demonstrate the formation of nanostructured double hydrophobic poly(styrene-b-methyl methacrylate) (PS-b-PMMA) block copolymer membranes via state-of-the-art phase inversion technique. The nanostructured membrane morphologies are tuned by different solvent and block copolymer compositions. The membrane morphology has been investigated using FESEM, AFM and TEM. Morphological investigation shows the formation of both cylindrical and lamellar structures on the top surface of the block copolymer membranes. The PS-b-PMMA having an equal block length (PS160K-b-PMMA160K) exhibits both cylindrical and lamellar structures on the top layer of the asymmetric membrane. All membranes fabricated from PS160K-b-PMMA160K shows an incomplete pore formation in both cylindrical and lamellar morphologies during the phase inversion process. However, PS-b-PMMA (PS135K-b-PMMA19.5K) block copolymer having a short PMMA block allowed us to produce open pore structures with ordered hexagonal cylindrical pores during the phase inversion process. The resulting PS-b-PMMA nanostructured block copolymer membranes have pure water flux from 105-820 l/m2.h.bar and 95% retention of PEG50K

TRPV4 calcium-permeable channel is a novel regulator of oxidized LDL-induced macrophage foam cell formation.

Science.gov (United States)

Goswami, Rishov; Merth, Michael; Sharma, Shweta; Alharbi, Mazen O; Aranda-Espinoza, Helim; Zhu, Xiaoping; Rahaman, Shaik O

2017-09-01

Cardiovascular disease is the number one cause of death in United States, and atherosclerosis, a chronic inflammatory arterial disease, is the most dominant underlying pathology. Macrophages are thought to orchestrate atherosclerosis by generating lipid-laden foam cells and by secreting inflammatory mediators. Emerging data support a role for a mechanical factor, e.g., matrix stiffness, in regulation of macrophage function, vascular elasticity, and atherogenesis. However, the identity of the plasma membrane mechanosensor and the mechanisms by which pro-atherogenic signals are transduced/maintained are unknown. We have obtained evidence that TRPV4, an ion channel in the transient receptor potential vanilloid family and a known mechanosensor, is the likely mediator of oxidized low-density lipoprotein (oxLDL)-dependent macrophage foam cell formation, a critical process in atherogenesis. Specifically, we found that: i) genetic ablation of TRPV4 or pharmacologic inhibition of TRPV4 activity by a specific antagonist blocked oxLDL-induced macrophage foam cell formation, and ii) TRPV4 deficiency prevented pathophysiological range matrix stiffness or scratch-induced exacerbation of oxLDL-induced foam cell formation. Mechanistically, we found that: i) plasma membrane localization of TRPV4 was sensitized to the increasing level of matrix stiffness, ii) lack of foam cell formation in TRPV4 null cells was not due to lack of expression of CD36, a major receptor for oxLDL, and iii) TRPV4 channel activity regulated oxLDL uptake but not its binding on macrophages. Altogether, these findings identify a novel role for TRPV4 in regulating macrophage foam cell formation by modulating uptake of oxLDL. These findings suggest that therapeutic targeting of TRPV4 may provide a selective approach to the treatment of atherosclerosis. Copyright © 2017. Published by Elsevier Inc.

Operator spin foam models

International Nuclear Information System (INIS)

Bahr, Benjamin; Hellmann, Frank; Kaminski, Wojciech; Kisielowski, Marcin; Lewandowski, Jerzy

2011-01-01

The goal of this paper is to introduce a systematic approach to spin foams. We define operator spin foams, that is foams labelled by group representations and operators, as our main tool. A set of moves we define in the set of the operator spin foams (among other operations) allows us to split the faces and the edges of the foams. We assign to each operator spin foam a contracted operator, by using the contractions at the vertices and suitably adjusted face amplitudes. The emergence of the face amplitudes is the consequence of assuming the invariance of the contracted operator with respect to the moves. Next, we define spin foam models and consider the class of models assumed to be symmetric with respect to the moves we have introduced, and assuming their partition functions (state sums) are defined by the contracted operators. Briefly speaking, those operator spin foam models are invariant with respect to the cellular decomposition, and are sensitive only to the topology and colouring of the foam. Imposing an extra symmetry leads to a family we call natural operator spin foam models. This symmetry, combined with assumed invariance with respect to the edge splitting move, determines a complete characterization of a general natural model. It can be obtained by applying arbitrary (quantum) constraints on an arbitrary BF spin foam model. In particular, imposing suitable constraints on a spin(4) BF spin foam model is exactly the way we tend to view 4D quantum gravity, starting with the BC model and continuing with the Engle-Pereira-Rovelli-Livine (EPRL) or Freidel-Krasnov (FK) models. That makes our framework directly applicable to those models. Specifically, our operator spin foam framework can be translated into the language of spin foams and partition functions. Among our natural spin foam models there are the BF spin foam model, the BC model, and a model corresponding to the EPRL intertwiners. Our operator spin foam framework can also be used for more general spin

Poly (acrylonitrile-co-methyl methacrylate nanoparticles: I. Preparation and characterization

Directory of Open Access Journals (Sweden)

M.S. Mohy Eldin

2017-12-01

Full Text Available This work concerns the preparation and characterization of poly (acrylonitrile-co-methyl methacrylate Copolymer, P(AN-co-MMA, nano-particles using precipitation polymerization technique. Potassium per-sulfate redox initiation system was used to perform polymerization process in an alcoholic aqueous system. The impact of different polymerization conditions such as comonomer concentration and ratio, polymerization time, polymerization temperatures, initiator concentration and co-solvent composition on the polymerization yield and particle size was studied. Maximum polymerization yield, 70%, was obtained with MMA:AN (90%:10% comonomer composition. Particle sizes ranging from 16 nm to 1483 nm were obtained and controlled by variation of polymerization conditions. The co-polymerization process was approved by FT-IR and TGA analysis. The copolymer composition was investigated by nitrogen content analysis. Copolymers with a progressive percentage of PAN show thermal stabilities close to PAN Homopolymer. SEM photographs prove spherical structure of the produced copolymers. The investigated system shows promising future in the preparation of nanoparticles from comonomers without using emulsifiers or dispersive agents.

Preparation of superhydrophobic poly(methyl methacrylate)-silicon dioxide nanocomposite films

Energy Technology Data Exchange (ETDEWEB)

Wang Jinyan [Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Jinming Road, Kaifeng, Henan Province 475004 (China); Chen Xinhua [Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Jinming Road, Kaifeng, Henan Province 475004 (China); College of Chemistry and Chemical Engineering, Xuchang University, Xuchang 461000 (China); Kang Yingke; Yang Guangbin; Yu Laigui [Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Jinming Road, Kaifeng, Henan Province 475004 (China); Zhang Pingyu, E-mail: pingyu@henu.edu.cn [Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Jinming Road, Kaifeng, Henan Province 475004 (China)

2010-12-15

Superhydrophobic poly(methyl methacrylate)-SiO{sub 2} (coded as PMMA-SiO{sub 2}) nanocomposite films with micro-nanohierarchical structure were prepared via a simple approach in the absence of low surface-energy compounds. By spin-coating the suspension of hydrophobic silica (SiO{sub 2}) nanoparticles dispersed in PMMA solution, target nanocomposite films were obtained on glass slides. The wetting behavior of PMMA-SiO{sub 2} nanocomposite films was investigated in relation to the dosage of SiO{sub 2} nanoparticles dispersed in PMMA solution. It was found that hydrophilic PMMA film was transferred to superhydrophobic PMMA-SiO{sub 2} nanocomposite films when hydrophobic SiO{sub 2} nanoparticles were introduced into the PMMA solution at a high enough dosage (0.2 g and above). Resultant PMMA-SiO{sub 2} nanocomposite films had a static water contact angle of above 162{sup o}, showing promising applications in selfcleaning and waterproof for outer wall of building, outer covering for automobile, sanitary wares, and so forth.

Phase behavior for the poly(alkyl methacrylate)+supercritical CO{sub 2}+DME mixture at high pressures

Energy Technology Data Exchange (ETDEWEB)

Choi, Yong-Seok; Chio, Sang-Won; Byun, Hun-Soo [Chonnam National University, Yeosu (Korea, Republic of)

2016-01-15

The phase behavior curves of binary and ternary system were measured for poly(alkyl methacrylate) in supercritical CO{sub 2}, as well as for the poly(alkyl methacrylate)+dimethyl ether (DME) (or 1-butene) in CO{sub 2}. The solubility curves are reported for the poly(alkyl methacrylate)+DME in supercritical CO{sub 2} at temperature from (300 to 465) K and a pressure from (3.66 to 248) MPa. Also, The high-pressure static-type apparatus of cloud-point curve was tested by comparing the measured phase behavior data of the poly(methyl methacrylate) [PMMA]+CO{sub 2}+20.0 and 30.4 wt% methyl methacrylate (MMA) system with literature data of 10.4, 28.8 and 48.4 wt% MMA concentration. The phase behavior data for the poly(alkyl methacrylate)+CO{sub 2}+DME mixture were measured in changes of the pressure-temperature (p, T) slope and with DME concentrations. Also, the cloud-point pressure for the poly(alkyl methacrylate)+1- butene solution containing supercritical CO{sub 2} shows from upper critical solution temperature (UCST) region to lower critical solution temperature (LCST) region at concentration range from (0.0 to 95) wt% 1-butene at below 455 K and at below 245MPa.

Extended Resection of Chest Wall Tumors with Reconstruction Using Poly Methyl Methacrylate-Mesh Prosthesis

International Nuclear Information System (INIS)

Abo Sedira, M.; Nassar, O.; Al-Ariny, A.

2003-01-01

This prospective study evaluates the early result of patients with massive chest wall tumors treated by extended resection and reconstruction using Prolene or Marlex mesh-enforced with Poly Methyl Methacrylate Bone Cement (PMMC) prosthesis. Material and Methods: This surgery was performed on 40 patients with a mean age of 45±18 (12-62) at the Department of Surgery, National Cancer Institute, Cairo University between 1998-2001. Primary chest wall tumors were the indications of surgery in 42.5%, while secondary involvement extending from other sites principally breast cancer were the indications for 57.5%. In 85% of patients more than 3 ribs were involved by tumors and lesions were more than 10 cm in the greatest dimension in 50% of cases. Resection involved sternum in 15 (37.5%) cases and in 45% of cases complete extensive rib resections extended between costovertebral junctions and the costochondral junctions were performed. Additional resections of nearby organs were needed in 20 (50%) of cases including partial lung resection in 14 cases, partial vertebral resection in 3 cases and diaphragm resection for 3 cases. Immediate bony reconstruction by inserting Prolene or Marlex mesh-enforced with Poly Methyl Methacrylate Bone Cement (PMMC) prosthesis to the resulting chest wall defect was performed in 36 cases, whereas, 4 cases had delayed reconstruction. Primary simple soft tissue closure was sufficient for 37.5% of patients; whereas 35% were covered by local rotational flap and 27.5% needed myocutaneous flaps. No patient with this immediate reconstruction needed ventilatory support or tracheostomy and flail chest was not noticed ICU stay was markedly reduced; whereas 85% required less than 7 days. Immediate post operative (40 days) complications were found in 14 patients (35%) and cases with additional lung resection had more complication rate than others (64% vs 19%). Infection occurred in 3 patients and conservative treatment for 3-4 weeks using frequent

Improved electrochemical performances of binder-free CoMoO4 nanoplate arrays@Ni foam electrode using redox additive electrolyte

Science.gov (United States)

Veerasubramani, Ganesh Kumar; Krishnamoorthy, Karthikeyan; Kim, Sang Jae

2016-02-01

Herein, we are successfully prepared cobalt molybdate (CoMoO4) grown on nickel foam as a binder free electrode by hydrothermal approach for supercapacitors and improved their electrochemical performances using potassium ferricyanide (K3Fe(CN)6) as redox additive. The formation of CoMoO4 on Ni foam with high crystallinity is confirmed using XRD, Raman, and XPS measurements. The nanoplate arrays (NPAs) of CoMoO4 are uniformly grown on Ni foam which is confirmed by FE-SEM analysis. The prepared binder-free CoMoO4 NPAs achieved maximum areal capacity of 227 μAh cm-2 with KOH electrolyte at 2.5 mA cm-2. This achieved areal capacity is further improved about three times using the addition of K3Fe(CN)6 as redox additive. The increased electrochemical performances of CoMoO4 NPAs on Ni foam electrode via redox additive are discussed in detail and the mechanism has been explored. Moreover, the assembled CoMoO4 NPAs on Ni foam//activated carbon asymmetric supercapacitor device with an extended operating voltage window of 1.5 V exhibits an excellent performances such as high energy density and cyclic stability. The overall performances of binder-free CoMoO4 NPAs on Ni foam with redox additives suggesting their potential use as positive electrode material for high performance supercapacitors.

Synthesis by ATRP of poly(ethylene-co-butylene)-block-polystyrene, poly(ethylene-co-butylene)-block-poly(4-acetoxystyrene) and its hydrolysis product poly(ethylene-co-butylene)-block-poly(hydroxystyrene)

DEFF Research Database (Denmark)

Jankova, Katja; Kops, Jørgen; Chen, Xianyi

1999-01-01

Diblock copolymers of poly(ethylene-co-butylene) and polystyrene or poly(4-acetoxystyrene) are synthesized by atom transfer radical polymerization (ATRP) using a 2-bromopropionic ester macroinitiator prepared from commercial monohydroxyl functional narrow dispersity hydrogenated polybutadiene...

POLY(96L/4D-LACTIDE) IMPLANTS FOR REPAIR OF ORBITAL FLOOR DEFECTS - AN IN-VITRO STUDY OF THE MATERIAL PROPERTIES IN A SIMULATION OF THE HUMAN ORBIT

NARCIS (Netherlands)

CORDEWENER, FW; ROZEMA, FR; JOZIASSE, CAP; BOS, RRM; BOERING, G; PENNINGS, AJ

1995-01-01

To test the mechanical and physical properties of two types of poly(96L/4D-lactide) (PLA96) implants and to evaluate their suitability for repair of large orbital floor defects, a study using an in vitro set-up was performed. Implants, 0.2 mm thick and 28 mm in diameter, were produced by either an

Vapour pressure and enthalpy of vaporization of aliphatic poly-amines

International Nuclear Information System (INIS)

Efimova, Anastasia A.; Emel'yanenko, Vladimir N.; Verevkin, Sergey P.; Chernyak, Yury

2010-01-01

Molar enthalpies of vaporization of aliphatic poly-amines: 1,4-dimethylpiperazine [106-58-1], 1-(2-aminoethyl)-piperazine, [140-31-8], 1-(2-aminoethyl)-4-methyl-piperazine [934-98-5], and triethylenetetramine [112-24-3] were obtained from the temperature dependence of the vapour pressure measured by the transpiration method. A large number of the primary experimental results on temperature dependences of vapour pressures of the parent compounds have been collected from the literature and have been treated uniformly in order to derive vaporization enthalpies of poly-amines at the reference temperature 298.15 K. An internal consistency check was performed on enthalpy of vaporization values for poly-amines studied in this work.

Superparamagnetic poly(methyl methacrylate) beads for nattokinase purification from fermentation broth.

Science.gov (United States)

Yang, Chengli; Xing, Jianmin; Guan, Yueping; Liu, Huizhou

2006-09-01

An effective method for purification of nattokinase from fermentation broth using magnetic poly(methyl methacrylate) (PMMA) beads immobilized with p-aminobenzamidine was proposed in this study. Firstly, magnetic PMMA beads with a narrow size distribution were prepared by spraying suspension polymerization. Then, they were highly functionalized via transesterification reaction with polyethylene glycol. The surface hydroxyl-modified magnetic beads obtained were further modified with chloroethylamine to transfer the surface amino-modified magnetic functional beads. The morphology and surface functionality of the magnetic beads were examined by scanning electron microscopy and Fourier transform infrared. An affinity ligand, p-aminobenzamidine was covalently immobilized to the amino-modified magnetic beads by the glutaraldehyde method for nattokinase purification directly from the fermentation broth. The purification factor and the recovery of the enzyme activity were found to be 8.7 and 85%, respectively. The purification of nattokinase from fermentation broth by magnetic beads only took 40 min, which shows a very fast purification of nattokinase compared to traditional purification methods.

Comparison of sound absorbing performances of copper foam and iron foam with the same parameters

Science.gov (United States)

Yang, X. C.; Shen, X. M.; Xu, P. J.; Zhang, X. N.; Bai, P. F.; Peng, K.; Yin, Q.; Wang, D.

2018-01-01

Sound absorbing performances of the copper foam and the iron foam with the same parameters were investigated by the AWA6128A detector according to standing wave method. Two modes were investigated, which included the pure metal foam mode and the combination mode with the settled thickness of metal foam. In order to legibly compare the sound absorbing coefficients of the two metal foams, the detected sound frequency points were divided into the low frequency range (100 Hz ~ 1000 Hz), the middle frequency range (1000 Hz ~ 3200 Hz), and the high frequency range (3500 Hz ~ 6000 Hz). Sound absorbing performances of the two metal foams in the two modes were discussed within the three frequency ranges in detail. It would be calculated that the average sound absorbing coefficients of copper foam in the pure metal foam mode were 12.6%, 22.7%, 34.6%, 43.6%, 51.1%, and 56.2% when the thickness was 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, and 30 mm. meanwhile, in the combination mode, the average sound absorbing coefficients of copper foam with the thickness of 10 mm were 30.6%, 34.8%, 36.3%, and 35.8% when the cavity was 5 mm, 10 mm, 15 mm, and 20 mm. In addition, those of iron foam in the pure metal foam mode were 13.4%, 20.1%, 34.4%, 43.1%, 49.6%, and 56.1%, and in the combination mode were 25.6%, 30.5%, 34.3%, and 33.4%.

A star-shaped poly(2-methyl-2-oxazoline)-based antifouling coating: Application in investigation of the interaction between acetaminophen and bovine serum albumin by frontal analysis capillary electrophoresis.

Science.gov (United States)

Du, Haiqin; Zhang, Chong; Mao, Ke; Wang, Yanmei

2017-08-01

In this work, an antifouling capillary modified with star-shaped poly(2-methyl-2-oxazoline)-based copolymer was used to study the interaction between acetaminophen (APAP) and bovine serum albumin (BSA) by frontal analysis capillary electrophoresis (FACE). The star-shaped copolymer, poly(ethylene imine)-graft-poly(2-methyl-2-oxazoline) (PEI-g-PMOXA), was immobilized onto the fused-silica capillary inner wall via dopamine-assisted co-deposition strategy, yielding a PEI-g-PMOXA/polydopamine (PDA)-coated antifouling capillary, i.e., an antifouling capillary coated with the PEI-g-PMOXA/PDA co-deposited film. Electroosmotic flow (EOF) mobility of the PEI-g-PMOXA/PDA-coated capillary was almost zero in a wide pH range (3.0-10.0), while the EOF mobility of bare capillary was much larger and increased significantly with pH increasing. When the PEI-g-PMOXA/PDA-coated capillary was exploited to separate a protein mixture including cytochrome c, lysozyme, ribonuclease A and α-chymotrypsinogen A, the theoretical plate numbers were of five orders of magnitude which were about ten-fold higher over those obtained with bare capillary; in addition, the RSD values of migration time were mostly less than 0.7% (30 consecutive runs) which were much smaller than those of bare capillary (c.a. 5.7%). The protein-resistant PEI-g-PMOXA/PDA-coated capillary was then used to investigate the interaction between APAP and BSA by FACE, the binding constant and number of binding sites at 25°C and pH 7.4 (Tris/HCl buffer of 25mM) were 1.39×10 4 M -1 and 1.08, respectively, which were comparable to the results determined by fluorescence spectroscopic measurement (3.18×10 4 M -1 and 1.19, respectively). Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis of [methyl-{sup 14}C]crotonobetaine from DL-[methyl-{sup 14}C]carnitine

Energy Technology Data Exchange (ETDEWEB)

Loester, H.; Seim, H. [Leipzig Univ. (Germany). Inst. of Clinical Chemistry and Pathobiochemistry

1996-02-01

The causes of carnitine deficiency syndromes are not completely understood, but decomposition of L-carnitine in vivo is likely to be involved. Carnitine is metabolized to {gamma}-butyrobetaine, and crotonobetaine is probably an intermediate in this pathway. To validate experimentally the precursor-product relationship between the three physiologically occuring {gamma}-betaines - L-carnitine, crotonobetaine, {gamma}-butyrobetaine - labelling with stable or radioactive isotopes became necessary. Methyl-labelled carnitine isomers (L(-)-, D(+)- or DL-) or {gamma}-butyrobetaine can be easily synthesized by methylation of 4-amino-3-hydroxybutyric acid isomers or 4-aminobutyric acid, respectively. Because of problems with the 4-aminocrotonic acid, we synthesized labelled crotonbetaine from labelled carnitine. Thus, DL-[methyl-{sup 14}C]carnitine was dehydrated by reaction with concentrated sulfuric acid. After removal of the latter the products were separated and purified by ion exchange chromatography on DOWEX 50 WX8 (200 - 400 mesh) and gradient elution with hydrochloric acid. In addition to the labelled main product [methyl-{sup 14}C]crotonobetaine (yield about 50 %), [methyl-{sup 14}C]glycine betaine and [methyl-{sup 14}C]acetonyl-trimethylammonium (ATMA) were formed. The end products were identified by combined thin layer chromatography/autoradiography and quantified by liquid scintillation counting. (Author).

The Dnmt3L ADD Domain Controls Cytosine Methylation Establishment during Spermatogenesis

Directory of Open Access Journals (Sweden)

Georgios Vlachogiannis

2015-02-01

Full Text Available A critical aspect of mammalian gametogenesis is the reprogramming of genomic DNA methylation. The catalytically inactive adaptor Dnmt3L is essential to ensuring this occurs correctly, but the mechanism by which it functions is unclear. Using gene targeting to engineer a single-amino-acid mutation, we show that the Dnmt3L histone H3 binding domain (ADD is necessary for spermatogenesis. Genome-wide single-base-resolution DNA methylome analysis of mutant germ cells revealed overall reductions in CG methylation at repetitive sequences and non-promoter CpG islands. Strikingly, we also observe an even more severe loss of non-CG methylation, suggesting an unexpected role for the ADD in this process. These epigenetic deficiencies were coupled with defects in spermatogonia, with mutant cells displaying marked changes in gene expression and reactivation of retrotransposons. Our results demonstrate that the Dnmt3L ADD is necessary for Dnmt3L function and full reproductive fitness.

Methyl 3,4-bis(cyclopropylmethoxybenzoate

Directory of Open Access Journals (Sweden)

Xian-Chao Cheng

2011-05-01

Full Text Available The title compound, C16H20O4, was obtained unintentionally as the byproduct of an attempted synthesis of methyl 3-(cyclopropylmethoxy-4-hydroxybenzoate. In the crystal, the molecules are linked by intermolecular C—H...O interactions.

Graphene and poly(methyl methacrylate) composite laminates on flexible substrates for volatile organic compound detection

Science.gov (United States)

Rattanabut, Chanoknan; Wongwiriyapan, Winadda; Muangrat, Worawut; Bunjongpru, Win; Phonyiem, Mayuree; Song, Young Jae

2018-04-01

In this paper, we present a gas sensor for volatile organic compound (VOC) detection based on graphene and poly(methyl methacrylate) (GR/PMMA) composite laminates fabricated using CVD-grown graphene. Graphene was transferred to a poly(ethylene terephthalate) (PET) substrate by PMMA-supported wet transfer process without PMMA removal in order to achieve the deposition of GR/PMMA composite laminates on PET. The GR/PMMA and graphene sensors show completely different sensitivities to VOC vapors. The GR/PMMA and graphene sensors showed the highest sensitivities to dichloromethane (DCM). The response of the GR/PMMA sensor to DCM was 3 times higher than that of the graphene sensor but the GR/PMMA sensor hardly responded to acetone, chloroform, or benzene. The sensing mechanism of the graphene sensor can be based on the dielectric constant of VOCs, the size of VOC molecule, and electron hopping effects on defect graphene, while that of the GR/PMMA sensor can be explained in terms of the polymer swelling owing to the Hansen solubility parameter.

Delayed O-methylation of l-DOPA in MB-COMT-deficient mice after oral administration of l-DOPA and carbidopa.

Science.gov (United States)

Tammimäki, Anne; Aonurm-Helm, Anu; Männistö, Pekka T

2018-04-01

1. Catechol-O-methyltransferase (COMT) is involved in the O-methylation of l-DOPA, dopamine, and other catechols. The enzyme is expressed in two isoforms: soluble (S-COMT), which resides in the cytoplasm, and membrane-bound (MB-COMT), which is anchored to intracellular membranes. 2. To obtain specific information on the functions of COMT isoforms, we studied how a complete MB-COMT deficiency affects the total COMT activity in the body, peripheral l-DOPA levels, and metabolism after l-DOPA (10 mg kg -1 ) plus carbidopa (30 mg kg -1 ) administration by gastric tube in wild-type (WT) and MB-COMT-deficient mice. l-DOPA and 3-O-methyl-l-DOPA (3-OMD) levels were assayed in plasma, duodenum, and liver. 3. We showed that the selective lack of MB-COMT did not alter the total COMT activity, COMT enzyme kinetics, l-DOPA levels, or the total O-methylation of l-DOPA but delayed production of 3-OMD in plasma and peripheral tissues.

Preparation of Au nanosheets supported on Ni foam and its electrocatalytic performance towards NaBH4 oxidation

International Nuclear Information System (INIS)

Yang, Fan; Cheng, Kui; Wang, Guiling; Cao, Dianxue

2015-01-01

Highlights: • The unique Au nanosheets are electrodeposited uniformly on Ni foam substrate. • Au NSs/Ni foam electrode shows high catalytic activity for NaBH 4 electrooxidation. • The surface of a single Au sheet is consisted of many nano-scale corrugations. - Abstract: The unique Au nanosheets (Au NSs) are electrodeposited uniformly on Ni foam substrate via a one-step potentiostatic electrodeposition technique. The electrode is characterized by scanning electron microscopy equipped with energy dispersive X-ray spectrometer and X-ray diffractometer. It shows a unique open structure allowing the full utilization of Au surface active sites. NaBH 4 electrooxidation in KOH solution on the Au NSs/Ni foam electrode are studied by linear sweep voltammetry and chronoamperometry. The electrode exhibits a high catalytic performance outperforming the Au particles made by the same method. At the oxidation potential of 0 V, the current density of 827 mA cm −2 can be achieved on Au NSs/Ni foam electrode, and only 219 mA cm −2 was obtained on Au NPs/Ni foam electrode, indicating that the catalytic activity is increased by 278%, which is attributed to the porous 3D structure, ensuring the full utilization of Au surfaces. Besides, H 2 generated by NaBH 4 hydrolysis can quickly diffuse away from the electrode, preventing surface active sites of Au from blocking by adsorbed gas bubbles

Interaction between poly(vinyl pyridine) and poly(2,6-dimethyl-1,4-phenylene oxide) : A copolymer blend miscibility study

NARCIS (Netherlands)

de Wit, Joost; van Ekenstein, Gert Alberda; ten Brinke, Gerrit

2007-01-01

The phase behavior of blends of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) with random copolymers of styrene and 2-vinyl pyridine, Poly(S-co-2VP), as well as with random copolymers of styrene and 4-vinyl pyridine, Poly(S-co-4VP), has been investigated in order to estimate the values of the

Atomic Level Cleaning of Poly Methyl Methacrylate Residues from the Graphene Surface Using Radiolized Water at High Temperatures (Postprint)

Science.gov (United States)

2017-09-05

arbitrary substrates like oxides, semiconductors , or even on other 2-D materials in order to make 2-D heterostructures.11–19 Poly-methyl...Following approaches utilized in semiconductor manufacturing, where PMMA is cleaned from the surface of semiconductors after lithographic patterning, wet...of these suggest the presence of significant amount of PMMA residue and inorganic particles made of SiOx and carbon in different places of the chip

Nucleation, Melting Behaviour and Mechanical Properties of Poly(L ...

African Journals Online (AJOL)

Anew category of nucleating agent for poly(L-lactic acid) (PLLA) was developed. An organic nucleating agent; N,N'-bis(benzoyl) suberic acid dihydrazide (NA) was synthesized from benzoyl hydrazine and suberoyl chloride which was deprived from suberic acid via acylation. The nucleation, melting behaviour and ...

Synthesis of DL-adrenaline (methyl C{sup 14}) (1961); Synthese de la DL-adrenaline (methyle {sup 14}C) (1961)

Energy Technology Data Exchange (ETDEWEB)

Pichat, L; Audinot, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1961-07-01

The sodium derivative of 5-3-4 dibenzyl oxyphenyl 2-oxazolidinone reacted with methyl iodide {sup 14}C, in stoichiometric quantity, gives rise to the corresponding N-methyl {sup 14}C derivative. The oxazolidinone ring is opened by concentrated hydrochloric acid and the benzyl groups removed by catalytic hydrogenolysis. Adrenaline methyl {sup 14}C is then purified on Dowex 50 X-12 exchange resin. Overall-yield is 45 per cent based upon methyl iodide {sup 14}C. (author) [French] Le derive sode de la (dibenzyloxy-3-4-phenyl)-5 oxazolidinone-2 traite par l'iodure de methyle {sup 14}C, en proportion stoechiometrique, fournit le derive N-methyle {sup 14}C correspondant. Apres ouverture du cycle oxazolidinone par HCL concentre et debenzylation par hydrogenation catalytique, on purifie l'adrenaline (methyle {sup 14}C) par chromatographie sur resine echangeuse Dowex 50 X-12. Le rendement est de 45 pour cent par rapport a l'iodure de methyle {sup 14}C. (auteurs)

Synthesis of DL-adrenaline (methyl C{sup 14}) (1961); Synthese de la DL-adrenaline (methyle {sup 14}C) (1961)

Energy Technology Data Exchange (ETDEWEB)

Pichat, L.; Audinot, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1961-07-01

The sodium derivative of 5-3-4 dibenzyl oxyphenyl 2-oxazolidinone reacted with methyl iodide {sup 14}C, in stoichiometric quantity, gives rise to the corresponding N-methyl {sup 14}C derivative. The oxazolidinone ring is opened by concentrated hydrochloric acid and the benzyl groups removed by catalytic hydrogenolysis. Adrenaline methyl {sup 14}C is then purified on Dowex 50 X-12 exchange resin. Overall-yield is 45 per cent based upon methyl iodide {sup 14}C. (author) [French] Le derive sode de la (dibenzyloxy-3-4-phenyl)-5 oxazolidinone-2 traite par l'iodure de methyle {sup 14}C, en proportion stoechiometrique, fournit le derive N-methyle {sup 14}C correspondant. Apres ouverture du cycle oxazolidinone par HCL concentre et debenzylation par hydrogenation catalytique, on purifie l'adrenaline (methyle {sup 14}C) par chromatographie sur resine echangeuse Dowex 50 X-12. Le rendement est de 45 pour cent par rapport a l'iodure de methyle {sup 14}C. (auteurs)

Polystyrene-poly(vinylphenol) copolymers as compatibilzers for organic-inorganic composites

International Nuclear Information System (INIS)

Landry, C.J.T.; Coltrain, B.K.; Teegarden, D.M.

1996-01-01

Random, graft, and block copolymers of polystyrene (PS) and poly(4-vinylphenol) (PVPh), and PVPh homopolymer are shown to act as compatibilizers for incompatible organic-inorganic composite materials. The VPh component reacts, or interacts strongly with the polymerizing inorganic (titanium or zirconium) alkoxide. The organic components studied were PS, poly(vinyl methyl ether), and poly(styrene-co-acrylonitrile). The use of such compatibilizers provides a means of combining in situ polymerized inorganic oxides and hydrophobic polymers. This is seen as a reduction in the size of the dispersed inorganic phase and results in improved optical and mechanical properties

Polycaprolactone foam functionalized with chitosan microparticles – a suitable scaffold for cartilage regeneration.

Czech Academy of Sciences Publication Activity Database

Filová, Eva; Jakubcová, B.; Danilová, I.; Kuželová Košťáková, E.; Jarošíková, T.; Chernyavskiy, Oleksandr; Hejda, J.; Handl, M.; Beznoska, J.; Nečas, A.; Rosina, J.; Amler, Evžen

2016-01-01

Roč. 65, č. 1 (2016), s. 121-131 ISSN 0862-8408 Institutional support: RVO:68378041 ; RVO:67985823 Keywords : poly-epsilon-caprolactone * chitosan * cartilage regeneration * foam Subject RIV: FI - Traumatology, Orthopedics Impact factor: 1.461, year: 2016

Simultaneous Determination of Hydroquinone and Catechol by Poly (L-methionine Coated Hydroxyl Multiwalled Carbon Nanotube Film

Directory of Open Access Journals (Sweden)

Ying Zhang

2014-07-01

Full Text Available A simply and high selectively electrochemical method has been developed for the simultaneous determination of hydroquinone and catechol at a glassy carbon electrode modified with the poly L-methionine/multiwall carbon nanotubes, which significantly increased the reversible electrochemical reaction. The electrochemical behavior of catechol and hydroquinone at the modified electrode was studied by cyclic voltammetry and differential pulse voltammetry. The presence of hydroxyl MWCNTs in the composite film enhances the surface coverage concentration of poly L- methionine/multiwall carbon nanotubes. The results suggest that pH=6 is the optimum acidity condition for the selective and simultaneous determination of catechol and hydroquinone. Under the optimized condition, the response peak currents of the modified electrodes were linear over ranges of 8.0´10-7~2.0´10-4 mol/L (R2=0.997 for hydroquinone and 8.0´10-7~2.0´10-4, R2=0.997 for catechol. The sensor also exhibited good sensitivity with the detection limit of 8.0´10-8 mol/L and 1.0´10- 7 mol/L for hydroquinone and catechol, respectively. This study provides a new kind of composite modified electrode for electrochemical sensors with good selectivity and strong anti- interference. It has been applied to simultaneous determination of hydroquinone and catechol in water sample with simplicity and high selectivity.

Anion exchange membranes based on terminally crosslinked methyl morpholinium-functionalized poly(arylene ether sulfone)s

Science.gov (United States)

Kwon, Sohyun; Rao, Anil H. N.; Kim, Tae-Hyun

2018-01-01

Azide-assisted terminal crosslinking of methyl morpholinium-functionalized poly(arylene ether sulfone) block copolymers yields products (xMM-PESs) suitable for use as anion exchange membranes. By combining the advantages of bulky morpholinium conductors and our unique polymer network crosslinked only at the termini of the polymer chains, we can produce AEMs that after the crosslinking show minimal loss in conductivity, yet with dramatically reduced water uptake. Terminal crosslinking also significantly increases the thermal, mechanical and chemical stability levels of the membranes. A high ion conductivity of 73.4 mS cm-1 and low water uptake of 26.1% at 80 °C are obtained for the crosslinked membrane with higher amount of hydrophilic composition, denoted as xMM-PES-1.5-1. In addition, the conductivity of the crosslinked xMM-PES-1.5-1 membrane exceeds that of its non-crosslinked counterpart (denoted as MM-PES-1.5-1) above 60 °C at 95% relative humidity because of its enhanced water retention capacity caused by the terminally-crosslinked structure.

Surface Modification of Multiwall Carbon Nanotubes with Cationic Conjugated Polyelectrolytes: Fundamental Interactions and Intercalation into Conductive Poly(methyl-methacrylate) Composites

KAUST Repository

Ezzeddine, Alaa

2015-05-22

This research investigates the modification and dispersion and of pristine multiwalled carbon nanotubes (MWCNTs) through a simple solution mixing technique based on noncovalent interactions between poly(phenylene ethynylene) based conjugated polyelectrolytes functionalized with cationic imidazolium solubilizing groups (PIM-2 and PIM-4) and MWCNTs. Spectroscopic studies demonstrated the ability of PIMs to strongly interact with and efficiently disperse MWCNTs in different solvents mainly due to π-interactions between the PIMs and MWCNTs. Transmission electron microscopy and atomic force microscopy revealed the coating of the polyelectrolytes on the walls of the nanotubes. Scanning electron microscopy (SEM) studies confirm the homogenous dispersion of PIM modified MWCNTs in poly(methyl methacrylate) (PMMA) matrix. The addition of 1 wt% PIM modified MWCNTs to the matrix has led to a significant decrease in DC resistivity of the composite (13 orders of magnitude). The increase in electrical conductivity and the improvement in thermal and mechanical properties of the membranes containing the PIM modified MWCNTs is ascribed to the formation of MWCNTs networks and cross-linking sites that provided channels for the electrons to move in throughout the matrix and reinforced the interface between MWCNTs and PMMA.

Poly(alkyl acrylate) nonparticles

International Nuclear Information System (INIS)

Kreuter, J.

1985-01-01

This study deals with the preparation of poly(alkyl acrylic) and poly(alkyl cyanocrylic) nanoparticles. Nonoparticles are solid colloidal particles, consisting of macromolecular materials in which drugs or biologically active materials are dissolved, entrapped, and encapsulated, and/or to which the active substance is adsorbed or attached. Poly(alkyl acrylic) nanoparticles are much more slowly biodegradable than poly(alkyl cyanoacrylate) nanoparticles, and are thus more suitable for drug delivery purposes. Poly(methyl methacrylate) is the material of choice for the use of nanoparticles as an adjuvant for vaccines and are produced by emulsifier-free polymerization in aqueous media. The polymerization, which can be initiated with gamma rays or with potassium peroxodisulfate, is described

Electrogenerated networks from poly[4-(diphenylaminobenzyl methacrylate] and their electrochromic properties

Directory of Open Access Journals (Sweden)

O. I. Negru

2014-09-01

Full Text Available Poly[4-(diphenylaminobenzyl methacrylate] with well-defined molecular weight and low polydispersity was prepared by atom transfer radical polymerization (ATRP using 4-(diphenylamino benzyl 2-bromo-2-methyl-propanoate as initiator and CuBr/2,2'-bipyridine as catalytic complex. Electrochemical behavior and optical properties of the polymers were investigated by cyclic voltammetry and UV-Vis and fluorescence spectroscopy. Cyclic votammetric studies revealed that the redox processes were accompanied by dimerization of triphenylamine pendant groups. The initial polymer was postmodified, in solution or bulk, by electrochemical oxidation leading to a crosslinked and insoluble network with electro -chromic properties, accompanied by strong color changes with high coloration efficiency. The crosslinking reaction took place between triphenylamine groups through para free positions leading to tetraphenylbenzidine bridges. The structure of polymers was confirmed by Fourier transform infrared (FT-IR spectroscopy and 1H and 13C-nuclear magnetic resonance spectroscopy. Morphology studies of the cross-linked film have evidenced a smooth and continuous aspect without any pinholes or defects.

Foam pad of appropriate thickness can improve diagnostic value of foam posturography in detecting postural instability.

Science.gov (United States)

Liu, Bo; Leng, Yangming; Zhou, Renhong; Liu, Jingjing; Liu, Dongdong; Liu, Jia; Zhang, Su-Lin; Kong, Wei-Jia

2018-04-01

The present study investigated the effect of foam thickness on postural stability in patients with unilateral vestibular hypofunction (UVH) during foam posturography. Static and foam posturography were performed in 33 patients (UVH group) and 30 healthy subjects (control group) with eyes open (EO) and closed (EC) on firm surface and on 1-5 foam pad(s). Sway velocity (SV) of center of pressure, standing time before falling (STBF) and falls reaction were recorded and analyzed. (1) SVs had an increasing tendency in both groups as the foam pads were added under EO and EC conditions. (2) STBFs, only in UVH group with EC, decreased with foam thickness increasing. (3) Significant differences in SV were found between the control and UVH group with EO (except for standing on firm surface, on 1 and 2 foam pad(s)) and with EC (all surface conditions). (4) Receiver operating characteristic curve analysis showed that the SV could better reflect the difference in postural stability between the two groups while standing on the 4 foam pads with EC. Our study showed that diagnostic value of foam posturography in detecting postural instability might be enhanced by using foam pad of right thickness.

Zinc oxide nanowire-poly(methyl methacrylate) dielectric layers for polymer capacitive pressure sensors.

Science.gov (United States)

Chen, Yan-Sheng; Hsieh, Gen-Wen; Chen, Shih-Ping; Tseng, Pin-Yen; Wang, Cheng-Wei

2015-01-14

Polymer capacitive pressure sensors based on a dielectric composite layer of zinc oxide nanowire and poly(methyl methacrylate) show pressure sensitivity in the range of 2.63 × 10(-3) to 9.95 × 10(-3) cm(2) gf(-1). This represents an increase of capacitance change by as much as a factor of 23 over pristine polymer devices. An ultralight load of only 10 mg (corresponding to an applied pressure of ∼0.01 gf cm(-2)) can be clearly recognized, demonstrating remarkable characteristics of these nanowire-polymer capacitive pressure sensors. In addition, optical transmittance of the dielectric composite layer is approximately 90% in the visible wavelength region. Their low processing temperature, transparency, and flexible dielectric film makes them a highly promising means for flexible touching and pressure-sensing applications.

Polymer microcapsules with "foamed" membranes.

Science.gov (United States)

Lavergne, Fleur-Marie; Cot, Didier; Ganachaud, François

2007-06-05

This article describes the preparation of capsules displaying craters at their surfaces and independent holes inside their membranes. These poly(methylmethacrylate) capsules of 20 to 200 microm diameter are prepared by a solvent evaporation process and typically contain a dispersant, polyvinyl alcohol, and an excipient, namely, a fatty acid triglyceride (miglyol 812). Spectroscopic methods showed that, depending on the miglyol content, the craters at the surface exhibited sizes of about 1 to 2 microm, whereas the core structure of the membrane changed significantly, typically from "soft-part-of-bread" up to "foamed"-like aspects. Among several spectroscopy techniques, confocal fluorescence microscopy confirmed that the capsules retained the miglyol in their core and not in the craters or holes, even after centrifugation and handling. This technique also showed that holes in the membrane are filled with water. A possible analysis of the "foaming" phenomenon based on the surface tensions of different oils, as well as their optimal hydrophile-lipophile balance (HLBO), is added to generalize the concept.

The Effect of Different Foam Concentrations on Sperm Motility in Japanese Quail

Directory of Open Access Journals (Sweden)

Avishek Biswas

2010-01-01

Full Text Available A study was conducted to determine the effect of foam extract on sperm motility in the male Japanese quail (Coturnix coturnix japonica. Adult male quails (<12 weeks of heavy body weight strain were housed in individual cages and divided into 5 groups according to the size of their cloacal glands. The data indicated that the size of the cloacal gland was positively correlated with the frequency of foam secretion and total foam production. One gram of freshly collected clean foam was mixed with 1.0 mL of normal saline and homogenized for 10 minutes. After centrifugation at 35 000 rpm, the supernatant was used as 100% foam extract. The extract was diluted to 1:40, 1:20, 1:10, and 1:4 with normal saline to produce 2.5, 5.0, 10, and 25% foam extracts, respectively. 5% foam extract enhanced sperm survival at room temperature (30°–35°C for 2 to 3 hrs, whereas higher concentrations (10% and above suppressed sperm motility. From this study, it may be concluded that foam secretion and quantity of foam are directly proportional to the size of the cloacal gland and that the foam enhances and prolongs sperm motility, in vitro at an optimum concentration of 5%.

A novel magnetic poly(aniline-naphthylamine)-based nanocomposite for micro solid phase extraction of rhodamine B

International Nuclear Information System (INIS)

Bagheri, Habib; Daliri, Rasoul; Roostaie, Ali

2013-01-01

Graphical abstract: -- Highlights: •A Fe 3 O 4 –aniline-naphthylamine nanocomposite was prepared via a simple route. •The magnetic nanocomposite was applied for isolation of RhB from water. •The nanocomposite applicability was compared with other pristine polymers. •The method was applied for the determination of RhB in different samples. -- Abstract: A novel Fe 3 O 4 –poly(aniline-naphthylamine)-based nanocomposite was synthesized by chemical oxidative polymerization process as a magnetic sorbent for micro solid phase extraction. The scanning electron microscopy images of the synthesized nanocomposite revealed that the copolymer posses a porous structure with diameters less than 50 nm. The extraction efficiency of this sorbent was examined by isolation of rhodamine B, a mutagenic and carcinogenic dye, from aquatic media in dispersion mode. Among different synthesized polymers, Fe 3 O 4 /poly(aniline-naphthylamine) nanocomposite showed a prominent efficiency. Parameters including the desorption solvent, amount of sorbent, desorption time, sample pH, ionic strength, extraction time and stirring rate were optimized. Under the optimum condition, a linear spiked calibration curve in the range of 0.35–5.00 μg L −1 with R 2 = 0.9991 was obtained. The limits of detection (3S b ) and limits of quantification (10S b ) of the method were 0.10 μg L −1 and 0.35 μg L −1 (n = 3), respectively. The relative standard deviation for water sample with 0.5 μg L −1 of RhB was 4.2% (n = 5) and the absolute recovery was 92%. The method was applied for the determination of rhodamine B in dishwashing foam, dishwashing liquid, shampoo, pencil, matches tips and eye shadows samples and the relative recovery percentage were in the range of 94–99%

Synthesis of polystyrene, poly(styrene/4-vinylpyridine), poly(p-nitrostyrene) and poly(p-aminostyrene)-coated silica and their extraction capabilities for amphetamine

International Nuclear Information System (INIS)

Sun Changmei; Zhang Shuanhong; Qu Rongjun; Sun Tao; Zhang Ying; Zhang Xiang; Song Jingyang

2010-01-01

Several novel organic-inorganic hybrid materials, including polystyrene-coated silica (SG-PS), poly(styrene/4-vinylpyridine)-coated silica (SG-PVP), poly(p-nitrostyrene)-coated silica (SG-PS-NO 2 ) and poly(p-aminostyrene)-coated silica (SG-PS-NH 2 ), were synthesized in order to improve the extraction methods of harmful stimulants via solid phase extraction. The materials were characterized using infrared spectra (IR), scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET) surface area measurement and thermogravimetric analysis (TG). The application of the new materials in solid phase extraction columns to extract methamphetamine revealed that the extraction capability of poly(styrene/4-vinylpyridine)-coated silica is the best among the four materials, which provides novel supporter materials for extracting amphetamine-derived drugs.

Synthesis of polystyrene, poly(styrene/4-vinylpyridine), poly(p-nitrostyrene) and poly(p-aminostyrene)-coated silica and their extraction capabilities for amphetamine

Energy Technology Data Exchange (ETDEWEB)

Sun Changmei; Zhang Shuanhong [School of Chemistry and Materials Science, Ludong University, Yantai, Shandong 264025 (China); Qu Rongjun, E-mail: qurongjun@eyou.com [School of Chemistry and Materials Science, Ludong University, Yantai, Shandong 264025 (China); Sun Tao; Zhang Ying; Zhang Xiang; Song Jingyang [School of Chemistry and Materials Science, Ludong University, Yantai, Shandong 264025 (China)

2010-11-01

Several novel organic-inorganic hybrid materials, including polystyrene-coated silica (SG-PS), poly(styrene/4-vinylpyridine)-coated silica (SG-PVP), poly(p-nitrostyrene)-coated silica (SG-PS-NO{sub 2}) and poly(p-aminostyrene)-coated silica (SG-PS-NH{sub 2}), were synthesized in order to improve the extraction methods of harmful stimulants via solid phase extraction. The materials were characterized using infrared spectra (IR), scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET) surface area measurement and thermogravimetric analysis (TG). The application of the new materials in solid phase extraction columns to extract methamphetamine revealed that the extraction capability of poly(styrene/4-vinylpyridine)-coated silica is the best among the four materials, which provides novel supporter materials for extracting amphetamine-derived drugs.

Atividade antibacteriana in vitro da própolis marrom

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Maria F.F. Gomes

2016-04-01

Full Text Available Resumo Objetivou-se avaliar a atividade antibacteriana in vitro da própolis marrom, por meio da determinação da Concentração Inibitória Mínima (CIM. O extrato alcoólico de própolis foi obtido de 35 g de própolis bruta macerada em 65 mL de álcool de cereais. As concentrações do extrato de própolis usadas foram: 75mg/mL; 56,4mg/mL; 37,5mg/mL; 18,9mg/mL; 9,3mg/mL; 4,5mg/mL e 2,25mg/mL. Foram utilizados 32 isolados de bactérias Gram-positivas: Rhodococcus equi, Staphylococcus aureus, Staphylococcus hyicus, Staphylococcus spp. e Streptococcus spp., e 32 isolados de bactérias Gram-negativas: Enterobacter agglomerans, Escherichia coli, Klebsiella pneumoniae, Klebsiella sp., Pseudomonas aeruginosa, Pseudomonas spp., Salmonella spp. e Serratia rubidaea, provenientes de processos clínicos infecciosos de animais domésticos, obtidas e armazenadas no Laboratório de Bacteriologia da FAMEZ/UFMS. O extrato de própolis marrom apresentou atividade antimicrobiana com CIM variando de 2,25 a 18,9mg/mL para as bactérias Gram-positivas e 4,5 a 18,9mg/mL para as bactérias Gram-negativas, sendo as bactérias provenientes de bovinos e caninos as mais resistentes. Conclui-se que a própolis marrom tem ação bactericida, em função da espécie da bactéria e da procedência animal.

Effect of barium-coated halloysite nanotube addition on the cytocompatibility, mechanical and contrast properties of poly(methyl methacrylate) cement

OpenAIRE

Jammalamadaka U; Tappa K; Weisman JA; Nicholson JC; Mills DK

2017-01-01

Uday Jammalamadaka,1 Karthik Tappa,1 Jeffery A Weisman,1 James Connor Nicholson,2 David K Mills1,3 1Center for Biomedical Engineering and Rehabilitation Science, 2Nanosystems Engineering, 3The School of Biological Sciences, Louisiana Tech University, Ruston, LA, USA Abstract: Halloysite nanotubes (HNTs) were investigated as a platform for tunable nanoparticle composition and enhanced opacity in poly(methyl methacrylate) (PMMA) bone cement. Halloysite has been widely used to increase ...

Nanoindentation and surface roughness profilometry of poly methyl methacrylate denture base materials.

Science.gov (United States)

Zafar, Muhammad Sohail; Ahmed, Naseer

2014-01-01

Polymers have a wide range of applications in dentistry. Poly methyl methacrylate (PMMA) is the most popular for making orthodontic retainers, dentures as well as synthetic teeth. Prior to clinical applications, the appliances are polished in the dental laboratory to achieve smooth, polished and comfortable surfaces. The objective of this study was to analyze the surface roughness profiles of PMMA dentures polished using two different approaches. In addition, the effects of ultrasonication and sandblasting were also evaluated on the fitting surface of PMMA dentures. This was an in vitro study using non-contact mode surface roughness profilometer and nano-indenter. Samples were polished using two different techniques (Standard and modified). Both cold cure and heat cure PMMA denture surfaces were evaluated for roughness, nanohardness and elastic modulus. The absolute hardness was recorded 297.72±19.04 MPa and 229.93±18.53 MPa for heat cured PMMA and cold cured PMMA. Manufactured acrylic teeth were harder (319.20±12.58 MPa) with an elastic modulus of (4.34±1.86 GPa). Modified polishing techniques (group 3) produced smoother surface. It was concluded that elastic moduli of acrylic tooth and heat cure PMMA is not very different. Surface treatments such as ultrasonication or sandblasting do not affect the roughness profiles of denture fitting surfaces.

Compliant gel polymer electrolyte based on poly(methyl acrylate-co-acrylonitrile)/poly(vinyl alcohol) for flexible lithium-ion batteries

International Nuclear Information System (INIS)

Ma, Xianguo; Huang, Xinglan; Gao, Jiandong; Zhang, Shu; Deng, Zhenghua; Suo, Jishuan

2014-01-01

Highlights: •Compliant gel polymer electrolyte based on P(MA-co-AN)/PVA is facilely prepared for flexible lithium-ion batteries. •The compliant gel polymer electrolyte displays high ionic conductivity, self-standing and mechanical flexible. •The compliant gel polymer electrolyte exhibits excellent chemical and electrochemical performances. -- Abstract: In this report, mechanically compliant gel polymer electrolyte (GPE) for flexible lithium-ion batteries is facilely fabricated. The GPE that based on the poly(methyl acrylate-co-acrylonitrile)/poly(vinyl alcohol) (P(MA-co-AN)/PVA) was prepared via emulsion polymerization. Herein, the P(MA-co-AN) copolymer is anticipated to exert beneficial for the bendability of the GPE, as well as swollen with the liquid electrolyte to provide a facile pathway for ion movement. The PVA serves as a stabilizer during the emulsion polymerization and a mechanical framework for the compliant polymer membrane. Performance benefits of the mechanically compliant membrane are elucidated in terms of mechanical behavior, thermostability and ionic conductivity. The GPE is still self-standing and mechanical flexible after swollen with liquid electrolyte. The GPE displays a conductivity of 0.98 mS cm −1 with the uptake electrolyte up to 150% of its own weight at 30 °C, excellent electrochemical stability window (5.2 V vs. Li/Li + ) and favorable interfacial characteristics. When used in flexible lithium-ion batteries, such a GPE demonstrates satisfactory compatibility with LiCoO 2 and graphite electrodes

Thermodynamic and kinetic analysis of phase separation of temperature-sensitive poly(vinyl methyl ether) in the presence of hydrophobic tert-butyl alcohol

Czech Academy of Sciences Publication Activity Database

Velychkivska, Nadiia; Bogomolova, Anna; Filippov, Sergey K.; Starovoytova, Larisa; Labuta, J.

2017-01-01

Roč. 295, č. 8 (2017), s. 1419-1428 ISSN 0303-402X R&D Projects: GA ČR(CZ) GC15-10527J Institutional support: RVO:61389013 Keywords : phase separation * coil-globule transition * poly(vinyl methyl ether) Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.723, year: 2016

Elution behavior of poly(ethylene glycol) through poly(vinyl alcohol) gel column using several solvents as eluents

International Nuclear Information System (INIS)

Hirayama, Chuichi; Motozato, Yoshiaki; Matsumoto, Kazuaki.

1983-01-01

γ-Irradiated poly(vinyl alcohol) beads, which were sufficiently allowed to swell in water, were washed with methanol, and then were packed into column. Gel chromatography was performed using methanol, benzene, esters and ketones as eluents and poly(ethylene glycol) as a sample. When the elution was carried out using methanol and benzene as eluents, elution behavior of samples was ordinary. When ethyl formate, methyl acetate and ethyl propionate were used as eluents, samples were slightly adsorbed and the elution was delayed. In the case the elution was carried out using ethyl acetate, propyl acetate, butyl acetate and ethyl methyl ketone as eluents, samples were adsorbed strongly on the bed material, and the adsorption curve was analogous to the calibration curve using methanol as an eluent. Dried poly(vinyl alcohol) gel as a packing material, showed ordinary elution behaviors for the samples. The adsorption of poly(ethylene glycol) on the present bed material was attributed to the existence of hydrated water on poly(vinyl alcohol) gel matrix. (author)

Characterization of Ti-6Al-4V open cellular foams fabricated by additive manufacturing using electron beam melting

International Nuclear Information System (INIS)

Murr, L.E.; Gaytan, S.M.; Medina, F.; Martinez, E.; Martinez, J.L.; Hernandez, D.H.; Machado, B.I.; Ramirez, D.A.; Wicker, R.B.

2010-01-01

Ti-6Al-4V open cellular foams were fabricated by additive manufacturing using electron beam melting (EBM). Foam models were developed from CT-scans of aluminum open cellular foams and embedded in CAD for EBM. These foams were fabricated with solid cell structures as well as hollow cell structures and exhibit tailorable stiffness and strength. The strength in proportion to the measured microindentation hardness is as much as 40% higher for hollow cell (wall) structures in contrast to solid, fully dense EBM fabricated components. Plots of relative stiffness versus relative density were in good agreement with the Gibson-Ashby model for open cellular foam materials. Stiffness or Young's modulus values measured using a resonant frequency-damping analysis technique were found to vary inversely with porosity especially for solid cell wall, open cellular structure foams. These foams exhibit the potential for novel biomedical, aeronautics, and automotive applications.

Photosensitivity mechanism of undoped poly(methyl methacrylate) under UV radiation at 325 nm and its spatial resolution limit

DEFF Research Database (Denmark)

Sáez-Rodríguez, D.; Nielsen, Kristian; Bang, Ole

2014-01-01

that increasing strain during photo-inscription leads to an increased photosensitivity, which is evidence of photodegradation. Likewise, refractive index change in the fiber was measured to be positive, which provides evidence for further polymerization of the material. Finally, we relate the data obtained......In this Letter, we provide evidence suggesting that the main photosensitive mechanism of an undoped poly(methyl methacrylate)-based microstructured optical fiber under UV radiation at 325 nm is a competitive process of both photodegradation and polymerization. We found experimentally...

C-11 production with MC-50 cyclotron and synthesis of L-[11C-methyl] methionine

International Nuclear Information System (INIS)

Kim, Sang Wook; Hur, Min Goo; Yang, Seung Dae; Ahn, Soon Hyuk; Chun, Kweon Soo

2003-01-01

L-[ 11 C-methyl] methionine was prepared via no-carrier-added(nca) fast S-alkylation of L-homocysteine with [ 11 C]CH 3 I using solid support (Al 2 O 3 /KF)at room temperature in ethanol. The radiochemical yield of methylation was 90.2%. After reaction, no radiochemical impurity was detected but traces of L-homocysteine precursor were monitored by UV detector. The purification was archived by passing successively through a C 18 and alumina sep-pak. the radiochemical purity of L-[ 11 C-methyl] methionine was over 98% after purification and total elapsed time to prepare was 10min from [ 11 C]CH 3 I delivery

Modification of Carboxymethyl Chitosan Film by Blending with Poly(benzyl L-glutamate)-block-poly(ethylene glycol) Copolymer

International Nuclear Information System (INIS)

Zhu, G.Z.; Gao, Q.C.; Liu, Y.Y.

2013-01-01

A series of water-soluble carboxymethyl chitosan (CMCS)/poly(benzyl L-glutamate)-block-poly(ethylene glycol) (PBLG-b-PEG) blend films with various CMCS/PBLG-b-PEG mol ratios were prepared by pervaporation method. Morphologies of CMCS/PBLG-b-PEG blend films were researched by scanning electron microscopy (SEM). Thermal, mechanical, and chemical properties of CMCS/PBLG-b-PEG blend films were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile tests, and contact angle tests. It was revealed that the introduction of PBLG-b-PEG segments could greatly affect the morphology and the properties of CMCS films. (author)

Foam stabilization by solid particle aggregates

Energy Technology Data Exchange (ETDEWEB)

Guignot, S.; Faure, S. [CEA Marcoule, Lab. des Procedes Avances de Decontamination, 30 (France); Pitois, O. [UniversiteParis-Est Marne-La-Valle, Lab. Physique des Materiaux Divises et des Interfaces (LPMDI), 77 - Marne la Vallee (France)

2008-07-01

During the dismantling of nuclear facilities, radioactive deposits on exposed areas are removed and solubilized by successive rinses of reactive liquid. Using this liquid in a foam state reduces the amount of resulting wastes. During the required decontamination time (1 to 5 hours) the foam has to be sufficiently wet (1). In the Laboratory of Advanced Processes for Decontamination, new formulations are currently studied to slow down the drainage kinetics of these foams, by adding colloidal particles of hydrophilic fumed silica into the classical mixtures of well-defined non ionic foaming surfactants previously used (2). The objective of our study is to shed light on the foam surprising stability induced by these particles. The study focuses on drainage of foams generated by air sparging through a suspension lying on a porous glass. The foaming suspensions contain between 0 and 70 g.L-1 of a fumed silica (Aerosil 380) which is well-known to form gels for concentrations above 200 g.L{sup -1}. In the studied solutions this silica builds up into aggregates of dozens of microns, whose volume-averaged mean diameter after sonication is centred around 300 nm. Under gentle stirring, they display no sign of re-aggregation during 24 h. On a free drainage configuration, a foam that contains particles keeps a significant amount of its initial liquid: up to 60 % during up to 5 hours, in contrast to classical foams that drain out all of their liquid in about 20 minutes. From a rheological point of view, the most concentrated suspensions display a yield stress behaviour. This evidences the structuring of the aggregates into a coherent network that might explain the incomplete drainage of the solutions. For the lowest concentrated solutions, such rheological properties have not been observed although the corresponding foams can retain large amount of solution. This suggests that local concentrations of aggregates can rise owing to their retention by foam channels, until they form

2-[(4-Bromophenylimino)methyl]-5-pentadecylphenol

OpenAIRE

Basavaraj Padmashali; Patchanita Thamyongkit; Amorn Petsom; Gadada Naganagowda

2012-01-01

2-[(4-Bromophenylimino)methyl]-5-pentadecylphenol has been synthesized by reaction of 2-hydroxy-4-pentadecylbenzaldehyde with 4-bromoaniline in 1,4-dioxane and its IR, ¹H-NMR, ¹³C-NMR and MS spectroscopic data are presented.

Radiolytic stabilization of poly(methyl methacrylate) in blends with polystyrene

International Nuclear Information System (INIS)

Lima, Ivania Soares de

2002-04-01

In this work the radiolytic stabilization of poly(methyl methacrylate) was analyzed by three radioprotective agents: polystyrene (PS) and hindered amine light stabilizers (HEALS), respectively, PMMA/PS systems, so a called polymeric blends were prepared with different compositions, where the miscibility of these blends were studied using viscometric, microscopy (SEM) and spectroscopy (FT-IR) techniques. The results show that PMMA/PS blends in the compositions below 10 wt% of PS are miscible, on films casting from solution of toluene and methyl-ethyl-ketone (1;1) mixture. On the other hand, in the composition above 10 wt% of PS, PMMA/PS blends show imminiscibility behavior. These polymer solutions were irradiated with gamma rays ( 60 Co) and viscometric, microscopic and spectroscopic experiments show gamma radiation-induced compatibilization on PMMA/PS blends on proportion 50/50 and 30/70 take place. Viscometric interaction parameters of miscible and compatibilized PMMA/PS bends were calculated in the range of - 50 kGy, with the goal to find out the polymeric interactions after irradiation of the films. G values of PMMA, PMMA/PS and PMMA+St systems were calculated in order to analyze the radioprotection of PS and St into PMMA matrix. The results show that (90/10) PMMA/PS and PMMA+1,5%St systems promote protection against the gamma the radiation-induced scissions, effect that leads to polymer degradation. Moreover, a small amount of crosslinking observed in irradiated blends has contributed to stabilize mechanical properties of PMMA films. PMMA+0,3% HALS system irradiated in doses above 60 kGy showed little stabilization of the mechanical properties of PMMA, since it was observed mechanical degradation this system. Based on these results, PS and St showed to be the best radioprotective agents to PMMA. (author)

Diversity of foam producing nocardioform actinomycetes isolated from biological foam from activated sludge plants in Comunidad Valenciana; Diversidad de actinomicetos nocardioformes productores de espumas biologicas aislados de plantas depuradoras de aguas residuales de la Comunidad Valenciana

Energy Technology Data Exchange (ETDEWEB)

Soler, A.; Alonso, J.L.; Cuesta, G.

2009-07-01

The formation of biological foams in activated sludge systems is one of the most important problems of solid separation in wastewater treatment plants. Nocardioform actinomycetes are the most important filamentous bacteria responsible of foam formation. This group of microorganisms has hydrophobic cellular surfaces due to the mycolic acids. These foams interfere in wastewater treatment process because retain many suspended solids, block conductions and produce overflowing in the digesters and corridors. To identify correctly the nocardioform actinomycetes we have to do poli phasic taxonomy that includes 16S rDNA sequences analysis, determinate several chemo taxonomic markers and some phenotypic tests. (Author) 18 refs.

Synthesis, characterization, and biological evaluation of poly(L-γ-glutamyl-glutamine-paclitaxel nanoconjugate

Directory of Open Access Journals (Sweden)

Sang Van

2010-10-01

Full Text Available Sang Van1, Sanjib K Das1, Xinghe Wang1, Zhongling Feng1, Yi Jin1, Zheng Hou1, Fu Chen1, Annie Pham1, Nan Jiang1, Stephen B Howell2, Lei Yu11Nitto Denko Technical Corporation, Oceanside, CA, USA; 2Moores Cancer Center, University of California, La Jolla, San Diego, CA, USAAbstract: The purpose of this study was to develop a novel, highly water-soluble poly(L-γ-glutamyl-glutamine-paclitaxel nanoconjugate (PGG-PTX that would improve the therapeutic index of paclitaxel (PTX. PGG-PTX is a modification of poly(L-glutamic acid-paclitaxel conjugate (PGA-PTX in which an additional glutamic acid has been added to each glutamic side chain in the polymer. PGG-PTX has higher water-solubility and faster dissolution than PGA-PTX. Unlike PGA-PTX, PGG-PTX self-assembles into nanoparticles, whose size remains in the range of 12–15 nm over the concentration range from 25 to 2,000 µg/mL in saline. Its critical micellar concentration in saline was found to be ~25 µg/mL. The potency of PGG-PTX when tested in vitro against the human lung cancer H460 cell line was comparable to other known polymer-PTX conjugates. However, PGG-PTX possesses lower toxicity compared with PGA-PTX in mice. The maximum tolerated dose of PGG-PTX was found to be 350 mg PTX/kg, which is 2.2-fold higher than the maximum tolerated dose of 160 mg PTX/kg reported for the PGA-PTX. This result indicates that PGG-PTX was substantially less toxic in vivo than PGA-PTX.Keywords: nanoconjugates, poly(L-glutamic acid, poly(L-γ-glutamyl-glutamine-paclitaxel, nanoparticles, anticancer

Protective effect of poly ({alpha}-L-glutamate) against UV and {gamma}-irradiation

Energy Technology Data Exchange (ETDEWEB)

Furuta, Masakazu E-mail: mfuruta@riast.osakafu-u.ac.jp; Huy, Nguyen Quang; Tsuchiya, Akihito; Nakatsuka, Hiroshige; Hayashi, Toshio

2004-10-01

We occasionally found that poly ({alpha}-L-glutamate) showed a superior protective effect on enzymes against UV and {sup 60}Co-{gamma} irradiation. We selected papain and {alpha}-amylase as a model enzyme and irradiated the aqueous solution (10 mg/ml) of each enzyme with UV and {sup 60}Co-{gamma} rays in the presence of poly ({alpha}-L-glutamate) ({alpha}-PGA), poly (glucosyl oxyethyl methacrylate (GEMA)), and glucose (1.25% w/v each). The mixture of the three compounds has a significant protective effect on the activity of papain solution showing 40% of remaining activity twice as much as the control containing no additive at the dose of 15 kGy. Among them, {alpha}-PGA showed the highest protecting effect on the both papain and {alpha}-amylase even after 10-kGy irradiation at which 50% of the activity was retained. {alpha}-PGA also showed significant protective activity on {alpha}-amylase against UV both in solution and under dried state.

Protective effect of poly (α-L-glutamate) against UV and γ-irradiation

International Nuclear Information System (INIS)

Furuta, Masakazu; Huy, Nguyen Quang; Tsuchiya, Akihito; Nakatsuka, Hiroshige; Hayashi, Toshio

2004-01-01

We occasionally found that poly (α-L-glutamate) showed a superior protective effect on enzymes against UV and 60 Co-γ irradiation. We selected papain and α-amylase as a model enzyme and irradiated the aqueous solution (10 mg/ml) of each enzyme with UV and 60 Co-γ rays in the presence of poly (α-L-glutamate) (α-PGA), poly (glucosyl oxyethyl methacrylate (GEMA)), and glucose (1.25% w/v each). The mixture of the three compounds has a significant protective effect on the activity of papain solution showing 40% of remaining activity twice as much as the control containing no additive at the dose of 15 kGy. Among them, α-PGA showed the highest protecting effect on the both papain and α-amylase even after 10-kGy irradiation at which 50% of the activity was retained. α-PGA also showed significant protective activity on α-amylase against UV both in solution and under dried state

Synthesis of 3-Methyl-1-morpholin-4-ylmethyl-2,6-diphenylpiperidin-4-one

Directory of Open Access Journals (Sweden)

Bathey R. Venkatraman

2009-09-01

Full Text Available This paper describes the synthesis of 3-methyl-1-morpholin-4-ylmethyl-2,6-diphenylpiperidin-4-one from 3-methyl-2,6-diphenylpiperidin-4-one. The synthesized compound was characterized by FT-IR, 1H NMR, EI-MS and elemental analysis.

Si+ and N+ ion implantation for improving blood compatibility of medical poly(methyl methacrylate)

International Nuclear Information System (INIS)

Li, D.J.; Cui, F.Z; Cui, F.Z.

1998-01-01

Si + and N + ion implantation into medical poly(methyl methacrylate) (PMMA) were performed at an energy of 80 keV with fluences ranging from 5x10 12 to 5x10 15 ions/cm 2 at room temperature to improve blood compatibility. The results of the blood contacting measurements in vitro showed that the anticoagulability and anticalcific behaviour on the surface morphology were enhanced after ion implantation. No appreciable change in the surface morphology was detected by scanning electron microscopy (SEM). X-ray photoelectron spectroscopy (XPS) analysis indicated that ion implantation broke some original chemical bonds on the surface to form some new Si- and N-containing groups. These results were considered responsible for the enhancement in the blood compatibility of PMMA. (author)

Luminescent Properties of Surface Functionalized BaTiO3 Embedded in Poly(methyl methacrylate)

Science.gov (United States)

Requena, Sebastian; Lacoul, Srijan; Strzhemechny, Yuri M.

2014-01-01

As-received BaTiO3 nanopowders of average grain sizes 50 nm and 100 nm were functionalized by (3-aminopropyl)triethoxysilane (APTES) and mixed with poly(methyl methacrylate)/toluene solution. The nanocomposite solution was spin coated on Si substrates to form thin films. The photoluminescence spectrum of the pure powder was composed of a bandgap emission at 3.0 eV and multiple bands centered about 2.5 eV. Surface functionalization of the BaTiO3 powder via APTES increases overall luminescence at room temperature while only enhancing bandgap emission at low-temperature. Polymer coating of the functionalized nanoparticles significantly enhances bandgap emissions while decreasing emissions associated with near-surface lattice distortions at 2.5 eV. PMID:28788468

Luminescent Properties of Surface Functionalized BaTiO3 Embedded in Poly(methyl methacrylate

Directory of Open Access Journals (Sweden)

Sebastian Requena

2014-01-01

Full Text Available As-received BaTiO3 nanopowders of average grain sizes 50 nm and 100 nm were functionalized by (3-aminopropyltriethoxysilane (APTES and mixed with poly(methyl methacrylate/toluene solution. The nanocomposite solution was spin coated on Si substrates to form thin films. The photoluminescence spectrum of the pure powder was composed of a bandgap emission at 3.0 eV and multiple bands centered about 2.5 eV. Surface functionalization of the BaTiO3 powder via APTES increases overall luminescence at room temperature while only enhancing bandgap emission at low-temperature. Polymer coating of the functionalized nanoparticles significantly enhances bandgap emissions while decreasing emissions associated with near-surface lattice distortions at 2.5 eV.

Electrochemical Behavior of Catechol and Hydroquinone at Copper Doped Poly (Methyl Red Coated Hydroxyl Multiwalled Carbon Nanotube Film and Their Simultaneous Determination in Water Samples

Directory of Open Access Journals (Sweden)

Ying Zhang

2014-09-01

Full Text Available A glassy carbon electrode modified with copper doped poly (methyl red coated hydroxyl multiwalled carbon nanotube film (Cu-PMR/MWCNTs, was developed to serve as a sensor for simultaneous determination of Hydroquinone (HQ and catechol (CC in this paper. The fabricated electrode showed excellent electrocatalytic behaviors towards the oxidation of HQ and CC with the enhancement of the redox peak current and the decrease of the peak-to-peak separation. Under the optimized condition, the individual determination of HQ or CT in their mixtures was performed, the response peak currents of the modified electrodes were linear over ranges of 8.0´10-7~4.0´10-4 M (R2=0.999 for CT and 5.0´10-7~2.0´10-4 M (R2=0.993 for HQ. The sensor also exhibited good sensitivity with the detection limit of 1.0´10-8 mol/L and 5.0´10-8 mol/L for HQ and CT, respectively. The simultaneous determination of HQ and CC was demonstrated by simultaneously changing their concentrations. The reduction peak currents of HQ and CC increased linearly with the concentration of their own in the range of 8´10-7 and 2.0´10-4 M for HQ and CC, with correlation coefficients of 0.994 and 0.995 (S/N=3, respectively. This study provides a new kind of composite modified electrode for electrochemical sensors with good selectivity and strong anti-interference. It has been applied to simultaneous determination of HQ and CT in water sample with high selectivity.

Preclinical and clinical evaluation of O-[11C]methyl-L-tyrosine for tumor imaging by positron emission tomography

International Nuclear Information System (INIS)

Ishiwata, Kiichi; Tsukada, Hideo; Kubota, Kazuo; Nariai, Tadashi; Harada, Norihiro; Kawamura, Kazunori; Kimura, Yuichi; Oda, Keiichi; Iwata, Ren; Ishii, Kenji

2005-01-01

We performed preclinical and clinical studies of O-[ 11 C]methyl-L-tyrosine, a potential tracer for imaging amino acid transport of tumors by positron emission tomography (PET). Examinations of the radiation-absorbed dose by O-[ 11 C]methyl-L-tyrosine and the acute toxicity and mutagenicity of O-methyl-L-tyrosine showed suitability of the tracer for clinical use. The whole-body imaging of monkeys and healthy humans by PET showed low uptake of O-[ 11 C]methyl-L-tyrosine in all normal organs except for the urinary track and bladder, suggesting that the O-[ 11 C]methyl-L-tyrosine PET has the potential for tumor imaging in the whole-body. Finally, the brain tumor imaging was preliminarily demonstrated

Thermal studies of poly(esters) containing silicon or germanium in the main chain

International Nuclear Information System (INIS)

Tagle, L.H.; Terraza, C.; Valenzuela, P.; Leiva, A.; Urzua, M.

2005-01-01

The thermal properties of poly(esters) containing Si and/or Ge in the main chain derived from the acid dichlorides bis(4-chloroformyl-phenyl)-dimethyl-silane, bis(4-chloroformyl-phenyl)-dimethyl-germane, bis(4-chloroformyl-phenyl)-diphenyl-silane and bis(4-chloroformyl-phenyl)-diphenyl-silane, and the diphenols bis(4-hydroxyphenyl)-dimethyl-silane, bis(4-hydroxyphenyl)-dimethyl-germane, bis(4-hydroxyphenyl)-diphenyl-silane and bis(4-hydroxyphenyl)-diphenyl-germane were studied by differential scanning calorimetry and dynamic thermogravimetry. Poly(esters) with two Si atoms in the main chain showed higher values of T g than those with two Ge atoms, and the same was observed for poly(esters) with phenyl groups bonded to the heteroatoms, instead of those with methyl groups. Thermal decomposition temperatures were also higher for those poly(esters) with two Si atoms in the main chain and those in which the heteroatom is bonded to phenyl groups, due to the higher polarity of the Si-C bond in front of the Ge-C

A new perspective on beta-sheet structures using vibrational Raman optical activity: From poly(L-lysine) to the prion protein

DEFF Research Database (Denmark)

McColl, L.H.; Blanch, E.W.; Gill, A.C.

2003-01-01

-sheet poly(L-lysine) contains up-and-down antiparallel beta-sheets based on the hairpin motif. The ROA spectrum of beta-sheet poly(L-lysine) was compared with ROA data on a number of native proteins containing different types of beta-sheet. Amide I and amide II ROA band patterns observed in beta-sheet poly(L-ly...

Environmental Fate and Transport of Poly- and Perfluoroalkyl Substances at Aqueous Film-Forming Foam Impacted Sites

Science.gov (United States)

Higgins, C.

2017-12-01

Poly and perfluoroalkyl substances (PFASs) are constituents in aqueous film-forming foam (AFFF) used to extinguish fuel fires. Substantially elevated PFAS groundwater concentrations have been observed at firefighter protection training areas, where co-contaminants such as chlorinated solvents and fuel hydrocarbons are also commonly present. Research into the fate and transport potential of PFASs at AFFF-impacted sites will be presented, with a particular focus on how co-contaminants and co-contaminant remediation technologies may alter the composition and transport behavior of PFASs at these sites. A detailed analysis of data collected from a U.S. Air Force site (Ellsworth Air Force Base, South Dakota) indicates that that conversion of polyfluoroalkyl chemicals to perfluoroalkyl acids (PFAAs) in situ due to natural and enhanced remediation of petroleum hydrocarbons. In addition, bench-scale studies examining the effects of various chemical oxidants, typically employed via in situ chemical oxidation (ISCO), indicates that oxidation-based remediation technologies have the potential to alter the release and composition of PFASs in AFFF-impacted source zones. Future challenges in addressing PFAS contamination will be discussed, particularly with respect to closing the mass balance on PFAAs and their precursors at AFFF-impacted sites.

Unfavourable short-term outcomes of a poly-L/D-lactide scaffold for thumb trapeziometacarpal arthroplasty.

Science.gov (United States)

Mattila, S; Waris, E

2016-03-01

The bioabsorbable poly-L-D-lactide joint scaffold arthroplasty is a recent attempt in the reconstruction of small joints in rheumatoid patients. In this study, we analysed the 1-year clinical, functional and radiologic results of partial trapeziectomy with the poly-L-D-lactide (96/4) joint scaffold in 23 patients with isolated trapeziometacarpal osteoarthritis. The results showed that the procedure provided pain relief and improvement in overall function according to the Quick Disabilities of the Arm, Shoulder and Hand score in most patients. However, radiographs demonstrated a high frequency of osteolysis around the implant. Seven patients developed clinically manifested foreign-body reactions 6 months to 1 year after surgery. The reason for the unexpected tissue reactions may relate to excessive mechanical cyclic loading of the implant. The outcomes of this implant in our patients have not been sufficiently beneficial and we have discontinued use of this implant in isolated trapeziometacarpal osteoarthritis. © The Author(s) 2015.

Surface modification of hydroxyapatite nanoparticles by poly(L-phenylalanine) via ROP of L-phenylalanine N-carboxyanhydride (Pha-NCA)

International Nuclear Information System (INIS)

Dai Yanfeng; Xu Min; Wei Junchao; Zhang Haobin; Chen Yiwang

2012-01-01

The surface of hydroxyapatite nanoparticles was modified by poly(L-phenylalanine) via the ring opening polymerization (ROP) of L-phenylalanine N-carboxyanhydride. The preparation procedure was monitored by Fourier transform infrared spectroscopy (FTIR), and the modified hydroxyapatite was characterized by thermal gravimetric analysis (TGA) and X-ray diffraction (XRD). The results showed that the surface grafting amounts of poly(L-phenylalanine) on HA ranging from 20.26% to 38.92% can be achieved by tuning the reaction condition. The XRD patterns demonstrated that the crystalline structure of the modified hydroxyapatite was nearly the same with that of HA, implying that the ROP was an efficient surface modification method. The MTT assay proved that the biocompatibility of modified HA was very good, which showed the potential application of modified HA in bone tissue engineering.

α-TCP cements prepared by syringe-foaming: Influence of Na2HPO4 and surfactant concentration.

Science.gov (United States)

Vásquez, A F; Domínguez, S; Loureiro Dos Santos, L A

2017-12-01

The lack of intrinsic open porosity in calcium phosphate cements slows down the resorption rate and bone ingrowth when implanted In Vivo. In this study, macroporous structures were obtained by mixing α-TCP cement with a foamed liquid phase containing different concentrations of sodium hydrogen phosphate and a nonionic surfactant. The cement paste was prepared by hand mixing in a novel system of two syringes connected by a tube. Two different liquid to powder (L/P) ratios were used to prepare the cement paste. The cement samples showed open macropores with diameters>100μm. The specimens prepared with lower L/P ratio showed smaller porosity, macroporosity and pore size distribution. The cohesion of the cement paste in liquid solutions was assessed by adding 2wt% sodium alginate to the liquid phase. This study suggests that the final macrostructure of the foamed cements can be controlled by varying the phosphate and surfactant concentrations in the liquid phase and the L/P ratio. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis of Nanometer-Sized Poly (methyl methacrylate) Polymer Network by Gold Nanoparticle Template

Science.gov (United States)

Liu, Fu-Ken; Hsieh, Shang-Yu; Ko, Fu-Hsiang; Chu, Tieh-Chi; Dai, Bau-Tong

2003-06-01

Gold nanoparticle/polymer composites have been produced using a one-system polymer synthesis. The linear polymer, poly (methyl methacrylate) (PMMA, MW = 15,000 g/mol) is applied for the stabilization of gold nanoparticles. The Fourier transfer infrared (FT-IR) analysis data and transition electron microscopy (TEM) image reveal that the core shell structure of gold/PMMA nanocomposite has been synthesized. The ratio of the concentration of the capping polymer material to the concentration of the gold precursor could control the sizes of gold nanoparticles. With specific concentration of the reductant, the core-shell nanostructure could be fluctuated in order. After heating treatment, the network structure of PMMA capped gold nanoparticles could be synthesized as confirmed by the TEM image. The result indicates that PMMA not only acts as the stabilizer, but also as the bridge of the neighboring gold nanoparticles.

Biodegradable Poly(D,L-lactic-co-glycolic acid)-Based Micro ...

African Journals Online (AJOL)

... drug encapsulation efficiency and release profile of PLGA mico/nanoparticles. The current knowledge of protein instability during preparation, storage and release from PLGA micro/nanoparticles and protein stabilization approaches has also been discussed in this review. Keywords: Poly(D, L-lactic-co-glycolic acid), ...

Interaction of poly-L-lysine coating and heparan sulfate proteoglycan on magnetic nanoparticle uptake by tumor cells

Czech Academy of Sciences Publication Activity Database

Siow, W. X.; Chang, Y.-T.; Babič, Michal; Lu, Y.-C.; Horák, Daniel; Ma, Y.-H.

2018-01-01

Roč. 13, 20 March (2018), s. 1693-1706 E-ISSN 1178-2013 R&D Projects: GA ČR(CZ) GC16-01128J Institutional support: RVO:61389013 Keywords : magnetic nanoparticles * poly-L-lysine * tea catechin Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 4.300, year: 2016

Poly(lactic acid)-Based in Situ Microfibrillar Composites with Enhanced Crystallization Kinetics, Mechanical Properties, Rheological Behavior, and Foaming Ability.

Science.gov (United States)

Kakroodi, Adel Ramezani; Kazemi, Yasamin; Ding, WeiDan; Ameli, Aboutaleb; Park, Chul B

2015-12-14

Melt blending is one of the most promising techniques for eliminating poly(lactic acid)'s (PLA) numerous drawbacks. However, success in a typical melt blending process is usually achieved through the inclusion of high concentrations of a second polymeric phase which can compromise PLA's green nature. In a pioneering study, we introduce the production of in situ microfibrillar PLA/polyamide-6 (PA6) blends as a cost-effective and efficient technique for improving PLA's properties while minimizing the required PA6 content. Predominantly biobased products, with only 3 wt % of in situ generated PA6 microfibrils (diameter ≈200 nm), were shown to have dramatically improved crystallization kinetics, mechanical properties, melt elasticity and strength, and foaming-ability compared with PLA. Crucially, the microfibrillar blends were produced using an environmentally friendly and cost-effective process. Both of these qualities are essential in guarantying the viability of the proposed technique for overcoming the obstacles associated with the vast commercialization of PLA.

Electrospinning of functional poly(methyl methacrylate) nanofibers containing cyclodextrin-menthol inclusion complexes

International Nuclear Information System (INIS)

Uyar, Tamer; Besenbacher, Flemming; Nur, Yusuf; Hacaloglu, Jale

2009-01-01

Electrospinning of nanofibers with cyclodextrin inclusion complexes (CD-ICs) is particularly attractive since distinct properties can be obtained by combining the nanofibers with specific functions of the CD-ICs. Here we report on the electrospinning of poly(methyl methacrylate) (PMMA) nanofibers containing cyclodextrin-menthol inclusion complexes (CD-menthol-ICs). These CD-menthol-IC functionalized nanofibers were developed with the purpose of producing functional nanofibers that contain fragrances/flavors with high temperature stability, and menthol was used as a model fragrance/flavor material. The PMMA nanofibers were electrospun with CD-menthol-ICs using three type of CD: α-CD, β-CD, and γ-CD. Direct pyrolysis mass spectrometry (DP-MS) studies showed that the thermal evaporation of menthol occurred over a very high and a broad temperature range (100-355 deg. C) for PMMA/CDmenthol-IC nanowebs, demonstrating the complexation of menthol with the CD cavity and its high temperature stability. Furthermore, as the size of CD cavity increased in the order α-CD β-CD>α-CD.

Large electrically induced height and volume changes in poly(3,4- ethylenedioxythiophene) /poly(styrenesulfonate) thin films

NARCIS (Netherlands)

Charrier, D.S.H.; Janssen, R.A.J.; Kemerink, M.

2010-01-01

We demonstrate large, partly reversible height and volume changes of thin films of poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) on the anode of interdigitating gold electrodes under ambient conditions by applying an electrical bias. The height and volume changes were monitored

Essential Oil Composition and Antimicrobial Activity of Methyl cinnamate-Linalool Chemovariant of Ocimum basilicum L. from India

Directory of Open Access Journals (Sweden)

Rajendra Chandra Padalia

2017-03-01

Full Text Available The essential oils obtained from hydrodistillation of Ocimum basilicum L. harvested at four different growth stages during spring-summer and rain-autumn cropping seasons , were characterized using GC and GC-MS. The e ssential oil yield was found to vary from 0.28–0.32% and 0.40–0.52% during spring-summer and rain-autumn cropping season, respectively with its maximal at full bloom stage. Altogether , forty constituents, comprising 94.9–98.3% were identified represented by ( E -methyl cinnamate (36.6 – 66.4%, linalool (11.2 – 43.8%, and (Z -methyl cinnamate (5.4-7.6% as main constituents. Results showed that growth stages strongly influenced the chemical composition of the essential oil in two cropping seasons, particularly concerning to the content of ( E -methyl cinnamate and linalool. Seed setting stage was optimized for harvesting ( E -methyl cinnamate rich oil (66.4% in rain-winter cropping season. The antimicrobial potential of the essential oil was tested againist eight pathogenic bacteria and three fungal strains. Antimicrobial assay showed that the essential oil possessed good antibacterial activity against Streptococcus mutans, Staphylococcus epidermidis, Escherichia coli , and antifungal activity against Candida kefyr and Candida albicans. Ocimum basilicum , essential oil, ( E - methyl cinnamate, linalool, antibacterial activity, antifungal activity

In Vitro Degradation of Borosilicate Bioactive Glass and Poly(l-lactide-co-ε-caprolactone Composite Scaffolds

Directory of Open Access Journals (Sweden)

Jenna Tainio

2017-11-01

Full Text Available Composite scaffolds were obtained by mixing various amounts (10, 30 and 50 weight % [wt %] of borosilicate bioactive glass and poly(l-lactide-co-ε-caprolactone (PLCL copolymer. The composites were foamed using supercritical CO2. An increase in the glass content led to a decrease in the pore size and density. In vitro dissolution/reaction test was performed in simulated body fluid. As a function of immersion time, the solution pH increased due to the glass dissolution. This was further supported by the increasing amount of Ca in the immersing solution with increasing immersion time and glass content. Furthermore, the change in scaffold mass was significantly greater with increasing the glass content in the scaffold. However, only the scaffolds containing 30 and 50 wt % of glasses exhibited significant hydroxyapatite (HA formation at 72 h of immersion. The compression strength of the samples was also measured. The Young’s modulus was similar for the 10 and 30 wt % glass-containing scaffolds whereas it increased to 90 MPa for the 50 wt % glass containing scaffold. Upon immersion up to 72 h, the Young’s modulus increased and then remained constant for longer immersion times. The scaffold prepared could have great potential for bone and cartilage regeneration.

Preparation of 14C-labelled poly(l-menthyl isopropenyl carbonates)

International Nuclear Information System (INIS)

Comes, R.A.; Grubbs, H.J.

1981-01-01

The synthesis of 14 C-labelled poly(l-menthyl isopropenyl carbonate) is described. Experimental conditions are included for incorporation of 14 C into each of the carbon atoms in the molecule. High pressure liquid chromatography conditions are given for separation and purification of the labelled intermediates. (author)

46 CFR 108.463 - Foam rate: Protein.

Science.gov (United States)

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Foam rate: Protein. 108.463 Section 108.463 Shipping... EQUIPMENT Fire Extinguishing Systems Foam Extinguishing Systems § 108.463 Foam rate: Protein. (a) If the outlets of a protein foam extinguishing system are in a space, the foam rate at each outlet must be at...