Schistosomicidal Activity of Dihydrobenzofuran Neolignans.

PubMed

Dias, Herbert J; Patrocínio, Andressa B; Pagotti, Mariana C; Fukui, Murilo J; Rodrigues, Vanderlei; Magalhães, Lizandra G; Crotti, Antônio E M

2018-05-13

We have evaluated the antischistosomal activity of synthetic dihydrobenzofuran neolignans (DBNs) derived from (±)-trans-dehydrodicoumarate dimethyl ester (1) and (±)-trans-dehydrodiferulate dimethyl ester (2) against adult Schistosoma mansoni worms in vitro. Compound 4 ((±)-4-O-acetyl-trans-dehydrodiferulate dimethyl ester) displays the most promising activity; at 200 μM, it kills 100±0% of worms after 24 h, which resembles the result achieved with praziquantel (positive control) at 1.56 μM. Hydrogenation of the double bond between C7' and C8', introduction of an additional methyl group at C3', and a double bond between C7 and C8 decreases the schistosomicidal activity of DBNs. On the other hand, the presence of the acetoxy group at C4 plays an interesting role in this activity. These results demonstrate the interesting schistosomicidal potential of DBNs, which could be further exploited. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Collection and analysis of organic gases from natural ecosystems - Application to poultry manure

NASA Technical Reports Server (NTRS)

Smith, M. S.; Francis, A. J.; Duxbury, J. M.

1977-01-01

Combined gas chromatography-mass spectrometry was used to identify volatile compounds generated from chicken manure and collected in Poropak QS-Carbosieve B traps. Various alcohols, ketones, esters, and carboxylic acids together with dimethyl sulfide and dimethyl disulfide were detected when the wastes were incubated in an argon atmosphere. Significant amounts of dimethyl sulfide and dimethyl disulfide but few other compounds were found when the manure was incubated in air

40 CFR 721.10223 - Styrenyl surface treated manganese ferrite with acrylic ester polymer (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... ferrite with acrylic ester polymer (generic). 721.10223 Section 721.10223 Protection of Environment... manganese ferrite with acrylic ester polymer (generic). (a) Chemical substance and significant new uses... manganese ferrite with acrylic ester polymer (PMN P-09-582) is subject to reporting under this section for...

40 CFR 721.10223 - Styrenyl surface treated manganese ferrite with acrylic ester polymer (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... ferrite with acrylic ester polymer (generic). 721.10223 Section 721.10223 Protection of Environment... manganese ferrite with acrylic ester polymer (generic). (a) Chemical substance and significant new uses... manganese ferrite with acrylic ester polymer (PMN P-09-582) is subject to reporting under this section for...

40 CFR 721.10223 - Styrenyl surface treated manganese ferrite with acrylic ester polymer (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... ferrite with acrylic ester polymer (generic). 721.10223 Section 721.10223 Protection of Environment... manganese ferrite with acrylic ester polymer (generic). (a) Chemical substance and significant new uses... manganese ferrite with acrylic ester polymer (PMN P-09-582) is subject to reporting under this section for...

40 CFR 721.10223 - Styrenyl surface treated manganese ferrite with acrylic ester polymer (generic).

Code of Federal Regulations, 2012 CFR

2012-07-01

... ferrite with acrylic ester polymer (generic). 721.10223 Section 721.10223 Protection of Environment... manganese ferrite with acrylic ester polymer (generic). (a) Chemical substance and significant new uses... manganese ferrite with acrylic ester polymer (PMN P-09-582) is subject to reporting under this section for...

40 CFR 721.10369 - Carbonic acid, diphenyl ester, polymer with diphenyl P-methylphosphonate and 4,4′-(1...

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Carbonic acid, diphenyl ester, polymer... Carbonic acid, diphenyl ester, polymer with diphenyl P-methylphosphonate and 4,4′-(1-methylethylidene) bis... identified as carbonic acid, diphenyl ester, polymer with diphenyl P-methylphosphonate and 4,4′-(1...

Fatty acid alkyl esters as solvents: An evaluation of the kauri-butanol value. Comparison to hydrocarbons, dimethyl diesters and other oxygenates

USDA-ARS?s Scientific Manuscript database

Esters, most commonly methyl esters, of vegetable oils or animal fats or other lipid feedstocks have found increasing use as an alternative diesel fuel known as biodiesel. However, biodiesel also has good solvent properties, a feature rendered additionally attractive by its biodegradability, low tox...

AN ASSESSMENT OF THE TOXICITY OF PHTHALATE ESTERS TO FRESHWATER BENTHOS. 1. AQUEOUS EXPOSURES

EPA Science Inventory

Tests were performed with the freshwater invertebrates, Hyalella azteca, Chironomus tentans, and Lumbriculus variegatus to determine the acute toxicity of six phthalate esters, including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), butylbenzyl ph...

40 CFR 721.10289 - Hexanedioic acid polymer with aliphatic polyol dihydrogen phosphate aromatic ester (generic).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Hexanedioic acid polymer with... polymer with aliphatic polyol dihydrogen phosphate aromatic ester (generic). (a) Chemical substance and... acid polymer with aliphatic polyol dihydrogen phosphate aromatic ester (PMN P-11-333) is subject to...

New High Temperature Cross Linking Monomers

NASA Technical Reports Server (NTRS)

Scola, Daniel A.

1978-01-01

This report describes the results of a one-year program designed to synthesize new, nonvolatile crosslinking monomers and to prove their feasibility in the development of lower temperature curing PMR-polyimide resins with high temperature capability. The objective of this program is to develop PMR-polyimide resins capable of being processed at a maximum temperature of 232C to 288C (450F to 500F) without sacrifice of the high temperature 316C (600F) capability of the state-of-the-art PMR-15 polyimide resin. Four monomethyl esters were synthesized and characterized for use in the crosslinking studies. It was found that all four crosslinkers were capable of entering into a crosslinking reaction to produce polymer specimens which were strong, dense and free of voids. The infrared and DSC studies of each crosslinker with monomers 4,4'-methylenedianiline (MDA) and the dimethyl ester of 3,3',4,4'-benzophenonetetracarboxylic acid (BTDE) comprising the resin systems, crosslinker/MDA/BTDE suggested that curing could be accomplished at 288C (550F). However, fabrication of dense, void free polymer specimens required a temperature of 316C (600F) and a pressure of 0.69 MPa (100 psi). The crosslinkers, monomethyl ester of 2,5-bicyclo[2.2.1]heptadiene-2,3-dicarboxylic acid (NDE) and monomethyl ester of maleic acid (MAE) were selected for evaluation in Celion 6000/PMR polyimide composites. These composites were characterized at RT, 288C (550F) and 316C (600F) initially and after isothermal aging at 288C (550F) and 316C (600F) for several hundred hours. The results of the isothermal aging studies suggested that both PMR systems NDE-MDA-BTDE and MAE-MDA-BTDE are promising candidates as matrices for addition type polyimide composites. These studies demonstrated that alternate crosslinkers to NE/MDA/BTDE are feasible, but mechanisms to lower the crosslinking temperature must be developed to provide lower temperature processing PMR-type polyimides.

New bis(alkythio) fatty acid methyl esters

USDA-ARS?s Scientific Manuscript database

The addition reaction of dimethyl disulfide (DMDS) to mono-unsaturated fatty acid methyl esters is well-known for analytical purposes to determine the position of double bonds by mass spectrometry. In this work, the classical iodine-catalyzed reaction is expanded to other dialkyl disulfides (RSSR), ...

FDEMS Sensing for Automated Intelligent Processing of PMR-15

NASA Technical Reports Server (NTRS)

Kranbuehl, David E.; Hood, D. K.; Rogozinski, J.; Barksdale, R.; Loos, Alfred C.; McRae, Doug

1993-01-01

The purpose of this grant was to develop frequency dependent dielectric measurements, often called FDEMS (frequency dependent electromagnetic sensing), to monitor and intelligently control the cure process in PMR-15, a stoichiometric mixture of a nadic ester, dimethyl ester, and methylendianiline in a monomor ratio.

Side Chain Degradable Cationic-Amphiphilic Polymers with Tunable Hydrophobicity Show in Vivo Activity.

PubMed

Uppu, Divakara S S M; Samaddar, Sandip; Hoque, Jiaul; Konai, Mohini M; Krishnamoorthy, Paramanandham; Shome, Bibek R; Haldar, Jayanta

2016-09-12

Cationic-amphiphilic antibacterial polymers with optimal amphiphilicity generally target the bacterial membranes instead of mammalian membranes. To date, this balance has been achieved by varying the cationic charge or side chain hydrophobicity in a variety of cationic-amphiphilic polymers. Optimal hydrophobicity of cationic-amphiphilic polymers has been considered as the governing factor for potent antibacterial activity yet minimal mammalian cell toxicity. However, the concomitant role of hydrogen bonding and hydrophobicity with constant cationic charge in the interactions of antibacterial polymers with bacterial membranes is not understood. Also, degradable polymers that result in nontoxic degradation byproducts offer promise as safe antibacterial agents. Here we show that amide- and ester (degradable)-bearing cationic-amphiphilic polymers with tunable side chain hydrophobicity can modulate antibacterial activity and cytotoxicity. Our results suggest that an amide polymer can be a potent antibacterial agent with lower hydrophobicity whereas the corresponding ester polymer needs a relatively higher hydrophobicity to be as effective as its amide counterpart. Our studies reveal that at higher hydrophobicities both amide and ester polymers have similar profiles of membrane-active antibacterial activity and mammalian cell toxicity. On the contrary, at lower hydrophobicities, amide and ester polymers are less cytotoxic, but the former have potent antibacterial and membrane activity compared to the latter. Incorporation of amide and ester moieties made these polymers side chain degradable, with amide polymers being more stable than the ester polymers. Further, the polymers are less toxic, and their degradation byproducts are nontoxic to mice. More importantly, the optimized amide polymer reduces the bacterial burden of burn wound infections in mice models. Our design introduces a new strategy of interplay between the hydrophobic and hydrogen bonding interactions keeping constant cationic charge density for developing potent membrane-active antibacterial polymers with minimal toxicity to mammalian cells.

21 CFR 175.260 - Partial phosphoric acid esters of polyester resins.

Code of Federal Regulations, 2014 CFR

2014-04-01

... section, partial phosphoric acid esters of polyester resins are prepared by the reaction of trimellitic anhydride with 2,2-dimethyl-1,3-propanediol followed by reaction of the resin thus produced with phosphoric... characterizing the type of food and under the conditions of time and temperature characterizing the conditions of...

Fatty acid methyl esters with two vicinal alkylthio side chains and their NMR characterization

USDA-ARS?s Scientific Manuscript database

The addition reaction of dimethyl disulfide (DMDS) to double bonds in alkenes and monounsaturated fatty acid esters in the presence of iodine or other catalysts to give bis(methylthio) derivatives has largely served analytical purposes in mass spectrometry with scattered reports on the addition of o...

40 CFR 721.10369 - Carbonic acid, diphenyl ester, polymer with diphenyl P-methylphosphonate and 4,4′-(1...

Code of Federal Regulations, 2014 CFR

2014-07-01

... with diphenyl P-methylphosphonate and 4,4â²-(1-methylethylidene) bis[phenol]. 721.10369 Section 721... Carbonic acid, diphenyl ester, polymer with diphenyl P-methylphosphonate and 4,4′-(1-methylethylidene) bis... identified as carbonic acid, diphenyl ester, polymer with diphenyl P-methylphosphonate and 4,4′-(1...

USE OF LINEAR FREE ENERGY RELATIONSHIPS AND AN EVALUATIVE MODEL TO ASSESS THE FATE AND TRANSPORT OF PHTHALATE ESTERS IN THE AQUATIC ENVIRONMENT

EPA Science Inventory

Linear free energy relationships for selected phthalate esters were used to estimate the rate constants for hydrolysis, biolysis, sediment-water partition coefficients, and biosorption required for modeling. The fate and transport behavior of dimethyl, diethyl, di-n-butyl, di-n-o...

40 CFR 721.10072 - Benzene, 1,1′-methylenebis[4-isocyanato-, polymer with benzenedicarboxylic acid, butyl dialkyl...

Code of Federal Regulations, 2010 CFR

2010-07-01

...-isocyanato-, polymer with benzenedicarboxylic acid, butyl dialkyl ester, poly[oxy(methyl-1,2-ethanediyl)], .alpha.-hydro-.omega.-hydroxy-, oxirane, alkyl-, polymer with oxirane, ether with propanepolyol and...-isocyanato-, polymer with benzenedicarboxylic acid, butyl dialkyl ester, poly[oxy(methyl-1,2-ethanediyl...

Activities of native and tyrosine-69 mutant phospholipases A2 on phospholipid analogues. A reevaluation of the minimal substrate requirements.

PubMed

Kuipers, O P; Dekker, N; Verheij, H M; de Haas, G H

1990-06-26

The role of Tyr-69 of porcine pancreatic phospholipase A2 in substrate binding was studied with the help of proteins modified by site-directed mutagenesis and phospholipid analogues with a changed head-group geometry. Two mutants were used containing Phe and Lys, respectively, at position 69. Modifications in the phospholipids included introduction of a sulfur at the phosphorus (thionophospholipids), removal of the negative charge at phosphorus (phosphatidic acid dimethyl ester), and reduction (phosphonolipids) or extension (diacylbutanetriol choline phosphate) of the distance between the phosphorus and the acyl ester bond. Replacement of Tyr-69 by Lys reduces enzymatic activity, but the mutant enzyme retains both the stereospecificity and positional specificity of native phospholipase A2. The Phe-69 mutant not only hydrolyzes the Rp isomer of thionophospholipids more efficiently than the wild-type enzyme, but the Sp thiono isomer is hydrolyzed too, although at a low (approximately 4%) rate. Phosphonolipids are hydrolyzed by native phospholipase A2 about 7 times more slowly than natural phospholipids, with retention of positional specificity and a (partial) loss of stereospecificity. The dimethyl ester of phosphatidic acid is degraded efficiently in a calcium-dependent and positional-specific way by native phospholipase A2 and by the mutants, indicating that a negative charge at phosphorus is not an absolute substrate requirement. The activities on the phosphatidic acid dimethyl ester of native enzyme and the Lys-69 mutant are lower than those on the corresponding lecithin, in contrast to the Phe-69 mutant, which has equal activities on both substrates.(ABSTRACT TRUNCATED AT 250 WORDS)

Degradable poly(anhydride ester) implants: effects of localized salicylic acid release on bone.

PubMed

Erdmann, L; Macedo, B; Uhrich, K E

2000-12-01

Degradable poly(anhydride ester) implants in which the polymer backbone breaks down into salicylic acid (SA) were investigated. In this preliminary work, local release of SA from the poly(anhydride esters), thus classified as 'active polymers', on healthy bone and tissue was evaluated in vivo using a mouse model. Degradable polyanhydrides that break down into inactive by-products were used as control membranes because of their chemical similarity to the active polymers. Small polymer squares were inserted over the exposed palatal bone adjacent to the maxillary first molars. Active polymer membranes were placed on one side of the mouth, control polymers placed on the contra lateral side. Intraoral clinical examination showed that active polymer sites were less swollen and inflamed than control polymer sites. Histopathological examination at day 1 showed essentially no difference between control and active polymers. After 4 days, active polymer sites showed epithelial proliferation to a greater extent than the polyanhydride controls. After 20 days, active polymer sites showed greater thickness of new palatal bone and no resorptive areas, while control polymer sites showed less bone thickness as well as resorption including lacunae involving cementum and dentine. From these preliminary studies, we conclude that active polymers, namely poly(anhydride esters), stimulated new bone formation.

Synthesis and characterization of poly (benzyl trimethyl ammonium chloride) ionic polymer

NASA Astrophysics Data System (ADS)

Mathew, Manjusha Elizabeth; Ahmad, Ishak; Thomas, Sabu; Daik, Rusli; Kassim, Muhammad

2018-04-01

Poly vinyl benzyl chloride (PVBC) was synthesized by free radical polymerization of 4-vinyl benzyl chloride (VBC) using benzoyl peroxide initiator at 80°C. Amine functionalised polymer prepared by treatment of PVBC with trimethyl amine in different solvents such as water, ethanol, tetra hydro furan(THF) and dimethyl formamide(DMF). The polymers characterized structurally by nuclear magnetic resonance and infrared spectroscopic techniques. The thermal decomposition of the polymer is studied by Thermo Gravimetric Analysis(TGA) and found that the polymer has stability up to 230°C. The nitrogen content of the aminated polymer determined by elemental analysis. The nitrogen content obtained from tetra hydro furan and dimethyl formamide solvents are 20.1% and 19.9% respectively.

A novel gene delivery composite system based on biodegradable folate-poly (ester amine) polymer and thermosensitive hydrogel for sustained gene release

PubMed Central

Yang, Yi; Zhao, Hang; Jia, YanPeng; Guo, QingFa; Qu, Ying; Su, Jing; Lu, XiaoLing; Zhao, YongXiang; Qian, ZhiYong

2016-01-01

Local anti-oncogene delivery providing high local concentration of gene, increasing antitumor effect and decreasing systemic side effects is currently attracting interest in cancer therapy. In this paper, a novel local sustained anti-oncogene delivery system, PECE thermoresponsive hydrogel containing folate-poly (ester amine) (FA-PEA) polymer/DNA (tumor suppressor) complexes, is demonstrated. First, a tumor-targeted biodegradable folate-poly (ester amine) (FA-PEA) polymer based on low-molecular-weight polyethyleneimine (PEI) was synthesized and characterized, and the application for targeted gene delivery was investigated. The polymer had slight cytotoxicity and high transfection efficiency in vitro compared with PEI 25k, which indicated that FA-PEA was a potential vector for targeted gene delivery. Meanwhile, we successfully prepared a thermoresponsive PECE hydrogel composite containing FA-PEA/DNA complexes which could contain the genes and slowly release the genes into cells. We concluded the folate-poly (ester amine) (FA-PEA) polymer would be useful for targeted gene delivery, and the novel gene delivery composite based on biodegradable folate-poly (ester amine) polymer and thermosensitive PECE hydrogel showed potential for sustained gene release. PMID:26883682

Synthesis of thermally stable polymers

NASA Technical Reports Server (NTRS)

Butler, G. B.

1978-01-01

The reaction of bis triazo linediones with divinyl esters and substituted styrenes was investigated. Twenty new polymers were derived via reaction of two previously synthesized bis triazol linediones and four new bis atriazol linediones with eight styrenes. The structure and polymer properties of these thermally stable polymers was examined. The reaction of triazo linediones with enol esters was also considered.

Additive manufacturing of short and mixed fibre-reinforced polymer

DOEpatents

Lewicki, James; Duoss, Eric B.; Rodriguez, Jennifer Nicole; Worsley, Marcus A.; King, Michael J.

2018-01-09

Additive manufacturing of a fiber-reinforced polymer (FRP) product using an additive manufacturing print head; a reservoir in the additive manufacturing print head; short carbon fibers in the reservoir, wherein the short carbon fibers are randomly aligned in the reservoir; an acrylate, methacrylate, epoxy, cyanate ester or isocyanate resin in the reservoir, wherein the short carbon fibers are dispersed in the acrylate, methacrylate, epoxy, cyanate ester or isocyanate resin; a tapered nozzle in the additive manufacturing print head operatively connected to the reservoir, the tapered nozzle produces an extruded material that forms the fiber-reinforced polymer product; baffles in the tapered nozzle that receive the acrylate, methacrylate, epoxy, cyanate ester or isocyanate resin with the short carbon fibers dispersed in the acrylate, methacrylate, epoxy, cyanate ester or isocyanate resin; and a system for driving the acrylate, methacrylate, epoxy, cyanate ester or isocyanate resin with the short carbon fibers dispersed in the acrylate, methacrylate, epoxy, cyanate ester or isocyanate resin from the reservoir through the tapered nozzle wherein the randomly aligned short carbon fibers in the acrylate, methacrylate, epoxy, cyanate ester or isocyanate resin are aligned by the baffles and wherein the extruded material has the short carbon fibers aligned in the acrylate, methacrylate, epoxy, cyanate ester or isocyanate resin that forms the fiber-reinforced polymer product.

A Single Chiroptical Spectroscopic Method May Not Be Able To Establish the Absolute Configurations of Diastereomers: Dimethylesters of Hibiscus and Garcinia Acids

PubMed Central

Polavarapu, Prasad L.; Donahue, Emily A.; Shanmugam, Ganesh; Scalmani, Giovanni; Hawkins, Edward K.; Rizzo, Carmelo; Ibnusaud, Ibrahim; Thomas, Grace; Habel, Deenamma; Sebastian, Dellamol

2013-01-01

Electronic circular dichroism (ECD), optical rotatory dispersion (ORD), and vibrational circular dichroism (VCD) spectra of hibiscus acid dimethyl ester have been measured and analyzed in combination with quantum chemical calculations of corresponding spectra. These results, along with those reported previously for garcinia acid dimethyl ester, reveal that none of these three (ECD, ORD, or VCD) spectroscopic methods, in isolation, can unequivocally establish the absolute configurations of diastereomers. This deficiency is eliminated when a combined spectral analysis of either ECD and VCD or ORD and VCD methods is used. It is also found that the ambiguities in the assignment of absolute configurations of diastereomers may also be overcome when unpolarized vibrational absorption is included in the spectral analysis. PMID:21568330

Gas chromatographic--mass spectrometric quantitation of 16, 16-dimethyl-trans-delta 2-PGE1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dimov, V.; Green, K.; Bygdeman, M.

1983-02-01

Di-deuterated and di-tritiated 16,16-dimethyl-trans-delta 2-PGE1 has been synthesized and used for development of a GC-MS method for quantitation of corresponding unlabelled drug in patient plasma. Although these carrier/internal standard molecules only contain 2 deuterium atoms the lower limit of detection at each injection is as low as about 40 pg. The maximum plasma levels of this drug following administration of vaginal suppositories used in clinical studies (1 mg 16,16-dimethyl-trans-delta 2-PGE1 methyl ester in 0.8 g Witepsol S-52) were 100-350 pg/ml i.e. in the same order of magnitude as earlier seen for 16,16-dimethyl-PGE2.

Asphaltenes-based polymer nano-composites

DOEpatents

Bowen, III, Daniel E

2013-12-17

Inventive composite materials are provided. The composite is preferably a nano-composite, and comprises an asphaltene, or a mixture of asphaltenes, blended with a polymer. The polymer can be any polymer in need of altered properties, including those selected from the group consisting of epoxies, acrylics, urethanes, silicones, cyanoacrylates, vulcanized rubber, phenol-formaldehyde, melamine-formaldehyde, urea-formaldehyde, imides, esters, cyanate esters, allyl resins.

Oxyphosphorus-containing polymers as binders for battery cathodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pratt, Russell Clayton; Mullin, Scott Allen; Eitouni, Hany Basam

A class of polymeric phosphorous esters can be used as binders for battery cathodes. Metal salts can be added to the polymers to provide ionic conductivity. The polymeric phosphorous esters can be formulated with other polymers either as mixtures or as copolymers to provide additional desirable properties. Examples of such properties include even higher ionic conductivity and improved mechanical properties. Furthermore, cathodes that include the polymeric phosphorous esters can be assembled with a polymeric electrolyte separator and an anode to form a complete battery.

Absolute configuration of a tetrahydrophenanthrene from Heliotropium ovalifolium by LC-NMR of its Mosher esters.

PubMed

Guilet, David; Guntern, Alain; Ioset, Jean-Robert; Queiroz, Emerson F; Ndjoko, Karine; Foggin, Chris M; Hostettmann, Kurt

2003-01-01

A new tetrahydrophenanthrene (1, (1R,2R)-1-hydroxy-2-methoxy-6,9-dimethyl-2,3-dihydrophenanthren-4(1H)-one (heliophenanthrone)) has been isolated from the aerial parts of Heliotropium ovalifolium. Its structure was elucidated on the basis of spectroscopic data, and the absolute configuration of the asymmetric centers was determined from LC-NMR data of the Mosher ester derivatives.

The influence of oscillations on product selectivity during the palladium-catalysed phenylacetylene oxidative carbonylation reaction.

PubMed

Novakovic, Katarina; Grosjean, Christophe; Scott, Stephen K; Whiting, Andrew; Willis, Mark J; Wright, Allen R

2008-02-07

This paper reports on the influence of oscillations on product selectivity as well as the dynamics of product formation during the palladium-catalysed phenylacetylene oxidative carbonylation reaction in a catalytic system (PdI2, KI, Air, NaOAc in methanol). The occurrence of the pH oscillations is related to PdI2 granularity and the initial pH drop after phenylacetylene addition. To achieve pH and reaction exotherm oscillations regulation of the amount of PdI2 is required, ensuring that the initial pH does not fall significantly below 1 after phenylacetylene addition. Experiments in both oscillatory and non-oscillatory pH regimes were performed in an HEL SIMULAR reaction calorimeter with the concentration-time profiles measured using a GC-MS. It is demonstrated that when operating in an oscillatory pH regime product formation may be suppressed until oscillations occur after which there is a steep increase in the formation of Z-2-phenyl-but-2-enedioic acid dimethyl ester. When operating in non-oscillatory pH mode the products are formed steadily over time with the main products being Z-2-phenyl-but-2-enedioic acid dimethyl ester, 2-phenyl-acrylic acid methyl ester and E-3-phenyl-acrylic acid methyl ester.

Preparation, characterization, and application of poly(vinyl alcohol)-graft-poly(ethylene glycol) resins: novel polymer matrices for solid-phase synthesis.

PubMed

Luo, Juntao; Pardin, Christophe; Zhu, X X; Lubell, William D

2007-01-01

Spherical crosslinked poly(vinyl alcohol) (PVA) beads with good mechanical stability were prepared by reverse-suspension polymerization, using dimethyl sulfoxide (DMSO) as a cosolvent in an aqueous phase. Poly(ethylene glycol)s with varying chain lengths were grafted onto the PVA beads by anionic polymerization of ethylene oxide. The thermal behavior, morphology, and swelling were evaluated for each of the new polymer matrices. High loading and good swelling in water and organic solvents were characteristic of the PEG-grafted PVA beads. The polymer beads also exhibited good mechanical and chemical stability and were unaffected by treatment with 6 N HCl and with 6 N NaOH. The hydroxyl groups of the PVA-PEG beads were converted into aldehyde, carboxylic acid, and isocyanate functions to provide scavenger resins and were extended by way of a benzyl alcohol in a Wang linker. The transglutaminase substrates dipeptides (Z-Gln-Gly) and heptapeptides (Pro-Asn-Pro-Gln-Leu-Pro-Phe) were synthesized on PVA-PEG_5, PVA-PEG_20, and the Wang linker-derivatized PVA-PEG resins. The cleavage of the peptides from the resins using MeOH/NH3 mixture at different temperatures (0 degrees C and room temp) and 50% TFA/DCM provided, respectively, peptide methyl esters, amides, and acids in good yields and purity as assessed by LC-MS analysis.

40 CFR 721.8160 - Propanoic acid, 2,2-dimethyl-, ethenyl ester.

Code of Federal Regulations, 2012 CFR

2012-07-01

... activities, full body chemical protective clothing is required for any worker activity in which the substance... applicable to the other substances weighted by the proportion of each substance present in the total daily...

40 CFR 721.8160 - Propanoic acid, 2,2-dimethyl-, ethenyl ester.

Code of Federal Regulations, 2014 CFR

2014-07-01

... activities, full body chemical protective clothing is required for any worker activity in which the substance... applicable to the other substances weighted by the proportion of each substance present in the total daily...

40 CFR 721.8160 - Propanoic acid, 2,2-dimethyl-, ethenyl ester.

Code of Federal Regulations, 2013 CFR

2013-07-01

... activities, full body chemical protective clothing is required for any worker activity in which the substance... applicable to the other substances weighted by the proportion of each substance present in the total daily...

21 CFR 175.260 - Partial phosphoric acid esters of polyester resins.

Code of Federal Regulations, 2010 CFR

2010-04-01

... resins are prepared by the reaction of trimellitic anhydride with 2,2-dimethyl-1,3-propanediol followed by reaction of the resin thus produced with phosphoric acid anhydride to produce a resin having an...

Androstanes and pregnanes from Trichilia emetica ssp. suberosa J.J. de Wilde.

PubMed

Malafronte, Nicola; Sanogo, Rokia; Vassallo, Antonio; De Tommasi, Nunziatina; Bifulco, Giuseppe; Dal Piaz, Fabrizio

2013-12-01

Four pregnanes: 1-methoxy-pregnan-17(R)-1,4-dien-3,16-dione (1), 1-methoxy-pregnan-17(S)-1,4-dien-3,16-dione (2), 2,3-seco-pregnan-17(S)-2,3-dioic acid-16-oxo-dimethyl ester (4), 2α,3α,16α-trihydroxy-5α-pregnan-17(R)-20-yl acetate (7), three androstanes: 1-methoxy-androstan-1,4-dien-3,16-dione (3), 2,3-seco-androstan-2,3-dioic acid-16-oxo-dimethyl ester (5), 3-methoxycarbonyl-2,3-seco-androstan-3-oic acid-16-oxo-2,19-lactone (6), together with three known pregnane derivatives, were isolated from the roots of Trichilia emetica ssp. suberosa. Their structures were determined by means of 1D and 2D NMR spectroscopy, mass spectrometry analysis, as well as by quantum chemical calculations. Copyright © 2013 Elsevier Ltd. All rights reserved.

Isohexide and Sorbitol-Derived, Enzymatically Synthesized Renewable Polyesters with Enhanced Tg.

PubMed

Gustini, Liliana; Lavilla, Cristina; de Ilarduya, Antxon Martínez; Muñoz-Guerra, Sebastián; Koning, Cor E

2016-10-10

Sugar-based polyesters derived from sorbitol and isohexides were obtained via solvent-free enzymatic catalysis. Pendant hydroxyl groups, coming from the sorbitol units, were present along the polyester backbone, whereas the two isohexides, namely, isomannide and isoidide dimethyl ester monomers, were selected to introduce rigidity into the polyester chains. The feasibility of incorporating isomannide as a diol compared to the isoidide dimethyl ester as acyl-donor via lipase-catalyzed polycondensation was investigated. The presence of bicyclic units resulted in enhanced T g with respect to the parent sorbitol-containing polyester lacking isohexides. The different capability of the two isohexides to boost the thermal properties confirmed the more flexible character provided by the isoidide diester derivative. Solvent-borne coatings were prepared by cross-linking the sugar-based polyester polyols with polyisocyanates. The increased rigidity of the obtained sugar-based polyester polyols led to an enhancement in hardness of the resulting coatings.

Receptor model for the molecular basis of tissue selectivity of 1,4-dihydropyridine calcium channel drugs

NASA Astrophysics Data System (ADS)

Langs, David A.; Strong, Phyllis D.; Triggle, David J.

1990-09-01

Our analysis of the solid state conformations of nifedipine [dimethyl 1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)-3,5-pyridinecarboxylate] and its 1,4-dihydropyridine (1,4-DHP) analogues produced a cartoon description of the important interactions between these drugs and their voltage-dependent calcium channel receptor. In the present study a molecular-level detailed model of the 1,4-DHP receptor binding site has been built from the published amino acid sequence of the 215-1 subunit of the voltage-dependent calcium channel isolated from rabbit skeletal muscle transverse tubule membranes. The voltage-sensing component of the channel described in this work differs from others reported for the homologous sodium channel in that it incorporates a water structure and a staggered, rather than eclipsed, hydrogen bonded S4 helix conformation. The major recognition surfaces of the receptor lie in helical grooves on the S4 or voltagesensing α-helix that is positioned in the center of the bundle of transmembrane helices that define each of the four calcium channel domains. Multiple binding clefts defined by Arg-X-X-Arg-P-X-X-S `reading frames' exist on the S4 strand. The tissue selectivity of nifedipine and its analogues may arise, in part, from conservative changes in the amino acid residues at the P and S positions of the reading frame that define the ester-binding regions of receptors from different tissues. The crystal structures of two tissue-selective nifedipine analogues, nimodipine [isopropyl (2-methoxyethyl) 1,4-dihydro-2,6- dimethyl-4-(3-nitrophenyl)-3,5-pyridinecarboxylate] and nitrendipine [ethyl methyl 1,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)-3,5-pyridinecarboxylate] are reported. Nimodipine was observed to have an unusual ester side chain conformation that enhances the fit to the proposed ester-sensing region of the receptor.

Hybrid nanocomposites of CdSe nanocrystals distributed in complexing thiophene-based copolymers.

PubMed

Aldakov, Dmitry; Jiu, Tonggang; Zagorska, Malgorzata; de Bettignies, Rémi; Jouneau, Pierre-Henri; Pron, Adam; Chandezon, Frédéric

2010-07-21

Two types of conjugated polymers were prepared with the goal to blend them with rod-like CdSe nanocrystals. The polymers of the first type were synthesized through copolymerization of 3-octylthiophene and 3-methylene-ethylcarboxylate-thiophene to give polythiophene with solubilizing alkyl groups and methylene ester functional groups (PE series). Post-polymerization hydrolysis of the ester type polymers yielded acid-type ones (PA series). Photoluminescence (PL) quenching in these polymers induced by their titration with nanocrystals solution was chosen as a measure of the polymer-nanocrystal interactions. PL of polyacids turned out to be more efficiently quenched as compared to the case of polymers with ester groups which was interpreted as an indication of better electronic communication between the hybrid components. Infrared (IR) spectroscopy confirmed efficient coordination of the carboxylic groups to CdSe. Voltammetric studies combined with UV-vis spectroelectrochemistry enabled the determination of energy levels alignment of the molecular composite components which turned out to be of staggered type-appropriate for photovoltaic applications. The obtained blends of polyacids with CdSe nanocrystals, when studied by transmission electron microscopy (TEM), revealed the presence of an interpenetrating network in which nanorods were homogeneously distributed within the polymer matrix without any indication of agglomerates formation both on the film surface and in the cross-section. Blends with polymers containing ester groups were less homogeneous which could be explained by weaker polymer-nanocrystals interactions. Photovoltaic cells based on these hybrid materials are also discussed.

The oxidation products of crude mesobilirubinogen

PubMed Central

Stoll, M. S.; Gray, C. H.

1970-01-01

Bile pigment esters were separated by ascending t.l.c. Apparently pure pigments, obtained by ferric chloride oxidation of crude mesobilirubinogen, derived from commercial bilirubin by reduction with sodium amalgam, were shown to be complex mixtures. Successive chromatography of their dimethyl esters on silica gel in methyl acetate–methyl propionate–dichloromethane–carbon tetrachloride (1:1:1:1, by vol.), ethyl methyl ketone–1,2-dichloroethane (1:2, v/v) and benzene–ethanol (100:3, v/v) revealed two major blue pigments (verdins), six major violet pigments (violins) and a red pigment (rhodin) together with numerous minor components. i-Urobilin dimethyl ester, prepared from mesobilirubinogen by dehydrogenation with aqueous iodine, was resolved into three major and at least four minor components on silica gel–kieselguhr (3:1, w/w) in benzene–ethanol (25:2, v/v). The chemical nature of these pigments was investigated by oxidation, by visible and u.v. spectroscopy, by mass spectrometry and by n.m.r. spectrometry. The evidence suggests unusual rearrangement of bilirubin during reduction leading to the formation of IIIα and XIIIα isomers. Isomeric forms of mesobiliviolin IXα and of i-urobilin IXα may also be formed. PMID:5420035

Volatile organic chemicals of a shore-dwelling cyanobacterial mat community.

PubMed

Evans, W G

1994-02-01

The main components of a cyanobacterial mat community of a hypersaline lake shore consist of edaphic, mat-forming strains (ecophenes), and littoral strains ofOscillatoria animalis Agardh andO. subbrevis Schmidle, other microorganisms associated with these cyanobacteria, several species ofBembidion (Carabidae: Coleoptera), and two halophytic flowering plants:Puccinellia nuttalliana (salt meadow grass) andSalicornia europaea rubra (samphire). The volatile organic compounds of this community are a blend of those emitted by each of these components such as the C17 alka(e)nes, geosmin, 2-methylisoborneol,β-cyclocitral,β-ionone, dimethyl sulfide, and dimethyl trisulfide of cyanobacteria and associated microorganisms; alcohols, esters, and aldehydes usually associated with flowering plants; and possibly some insect-derived esters, particularly isopropyl tetradecanoate. The dominant compounds were: C11, C13, C15, and C17 alka(e)nes, methyl esters of C16 and C18:2 acids, isopropyl tetradecanoate, heptanal, 3-octanone and 2-nonanone, the acyclic terpene linalool, and the alcohols 1-heptanol, 1-hexanol, 1-octanol, 3-hexen-1-ol, and 2-octen-1-ol. It is concluded that this community may be distinguished from related communities by its repertoire of volatile organic compounds.

40 CFR 721.8160 - Propanoic acid, 2,2-dimethyl-, ethenyl ester.

Code of Federal Regulations, 2011 CFR

2011-07-01

.../min · cm2 after 8 hours of testing in accordance with the most current version of the American Society... will be released will be calculated before the substance enters control technology does not apply...

40 CFR 721.8160 - Propanoic acid, 2,2-dimethyl-, ethenyl ester.

Code of Federal Regulations, 2010 CFR

2010-07-01

.../min · cm2 after 8 hours of testing in accordance with the most current version of the American Society... will be released will be calculated before the substance enters control technology does not apply...

Building ultramicropores within organic polymers based on a thermosetting cyanate ester resin.

PubMed

Zhang, Bufeng; Wang, Zhonggang

2009-09-07

Ultramicropores with high surface areas (>530 m(2) g(-1)) and narrow micropore size distribution (4-6 A) were engineered within a new cyanate ester resin, extending the microporous concept (<20 A) to general thermosetting resins in the area of polymer chemistry.

Tailor making high performance graphite fiber reinforced PMR polyimides

NASA Technical Reports Server (NTRS)

Serafini, T. T.; Vannucci, R. D.

1974-01-01

Studies performed to demonstrate the feasibility of using the polymerization of monomer reactants (PMR) approach to tailor make processable polyimide matrix resins are described. Monomeric reactant solutions containing the dimethyl ester of 3,3',4,4' -benzophenonetetracarboxylic acid, 4, 4' -methylenedianiline and the monomethyl ester of 5-norbornene-2, 3-dicarboxylic acid were used to impregnate Hercules HTS graphite fiber. Six different monomeric reactant stoichiometries were studied. The processing characteristics and elevated temperature mechanical properties of the PMR polyimide/HTS graphite fiber composites are described.

Semi-aromatic polyesters based on a carbohydrate-derived rigid diol for engineering plastics.

PubMed

Wu, Jing; Eduard, Pieter; Thiyagarajan, Shanmugam; Noordover, Bart A J; van Es, Daan S; Koning, Cor E

2015-01-01

New carbohydrate-based polyesters were prepared from isoidide-2,5-dimethanol (extended isoidide, XII) through melt polymerization with dimethyl esters of terephthalic acid (TA) and furan-2,5-dicarboxylic acid (FDCA), yielding semi-crystalline prepolymers. Subsequent solid-state post-condensation (SSPC) gave high molecular weight (Mn =30 kg mol(-1) for FDCA) materials, the first examples of high Mn , semi-aromatic homopolyesters containing isohexide derivatives obtained via industrially relevant procedures. NMR spectroscopy showed that the stereo-configuration of XII was preserved under the applied conditions. The polyesters are thermally stable up to 380 °C. The TA- and FDCA-based polyesters have high Tg (105 °C and 94 °C, resp.) and Tm (284 °C and 250 °C, resp.) values. Its reactivity, stability, and ability to afford high Tg and Tm polyesters make XII a promising diol for the synthesis of engineering polymers. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multistimuli-Responsive Amphiphilic Poly(ester-urethane) Nanoassemblies Based on l-Tyrosine for Intracellular Drug Delivery to Cancer Cells.

PubMed

Aluri, Rajendra; Saxena, Sonashree; Joshi, Dheeraj Chandra; Jayakannan, Manickam

2018-06-11

Multistimuli-responsive l-tyrosine-based amphiphilic poly(ester-urethane) nanocarriers were designed and developed for the first time to administer anticancer drugs in cancer tissue environments via thermoresponsiveness and lysosomal enzymatic biodegradation from a single polymer platform. For this purpose, multifunctional l-tyrosine monomer was tailor-made with a PEGylated side chain at the phenolic position along with urethane and carboxylic ester functionalities. Under melt dual ester-urethane polycondensation, the tyrosine monomer reacted with diols to produce high molecular weight amphiphilic poly(ester-urethane)s. The polymers produced 100 ± 10 nm spherical nanoparticles in aqueous medium, and they exhibited thermoresponsiveness followed by phase transition from clear solution into a turbid solution in heating/cooling cycles. Variable temperature transmittance, dynamic light scattering, and 1 H NMR studies revealed that the polymer chains underwent reversible phase transition from coil-to-expanded chain conformation for exhibiting the thermoresponsive behavior. The lower critical solution temperature of the nanocarriers was found to correspond to cancer tissue temperature (at 42-44 °C), which was explored as an extracellular trigger (stimuli-1) for drug delivery through the disassembly process. The ester bond in the poly(ester-urethane) backbones readily underwent enzymatic biodegradation in the lysosomal compartments that served as intracellular stimuli (stimuli-2) to deliver drugs. Doxorubicin (DOX) and camptothecin (CPT) drug-loaded polymer nanocarriers were tested for cellular uptake and cytotoxicity studies in the normal WT-MEF cell line and cervical (HeLa) and breast (MCF7) cancer cell lines. In vitro drug release studies revealed that the polymer nanoparticles were stable under physiological conditions (37 °C, pH 7.4) and they exclusively underwent disassembly at cancer tissue temperature (at 42 °C) and biodegradation by lysosomal-esterase enzyme to deliver 90% of DOX and CPT. Drug-loaded polymer nanoparticles exhibited better cytotoxic effects than their corresponding free drugs. Live cell confocal microscopy imaging experiments with lysosomal tracker confirmed the endocytosis of the polymer nanoparticles and their biodegradation in the lysosomal compartments in cancer cells. The increment in the drug content in the cells incubated at 42 °C compared to 37 °C supported the enhanced drug uptake by the cancer cells under thermoresponsive stimuli. The present work creates a new platform for the l-amino acid multiple-responsive polymer nanocarrier platform for drug delivery, and the proof-of-concept was successfully demonstrated for l-tyrosine polymers in cervical and breast cancer cells.

Transition state analogue imprinted polymers as artificial amidases for amino acid p-nitroanilides: morphological effects of polymer network on catalytic efficiency.

PubMed

Mathew, Divya; Thomas, Benny; Devaky, K S

2017-11-13

The morphology of the polymer network - porous/less porous - plays predominant role in the amidase activities of the polymer catalysts in the hydrolytic reactions of amino acid p-nitroanilides. Polymers with the imprints of stable phosphonate analogue of the intermediate of hydrolytic reactions were synthesized as enzyme mimics. Molecular imprinting was carried out in thermodynamically stable porogen dimethyl sulphoxide and unstable porogen chloroform, to investigate the morphological effects of polymers on catalytic amidolysis. It was found that the medium of polymerization has vital influence in the amidase activities of the enzyme mimics. The morphological studies of the polymer catalysts were carried out by scanning electron microscopy and Bruner-Emmett-Teller analysis. The morphology of the polymer catalysts and their amidase activities are found to be dependent on the composition of reaction medium. The polymer catalyst prepared in dimethyl sulphoxide is observed to be efficient in 1:9 acetonitrile (ACN)-Tris HCl buffer and that prepared in chloroform is noticed to be stereo specifically and shape-selectively effective in 9:1 ACN-Tris HCl buffer. The solvent memory effect in catalytic amidolysis was investigated using the polymer prepared in acetonitrile.

The sonochemical arylation of malonic esters mediated by manganese triacetate.

PubMed

Meciarova, M; Toma, S; Luche, J L

2001-04-01

The intermolecular arylation of malonate esters in acetic acid solution in the presence of manganese(III) triacetate is known to proceed via an Electron Transfer mechanism. Under sonication, this reaction undergoes only minor changes. In contrast, the intramolecular reaction of dimethyl alpha-(3-phenylpropyl)malonate provides a new case of sonochemical switching, with the formation of compounds 7-9, while conventional thermal conditions generate only the bicyclic compound 6. Reactions using the more powerful oxidant, cerium ammonium nitrate are governed by the formation of the nitrate ester 11. Compounds 7-9 are isolated in yields lower than with MnTA, and in proportions depending on the conditions, thermal or sonochemical.

Bio-Based Nanocomposites: An Alternative to Traditional Composites

ERIC Educational Resources Information Center

Tate, Jitendra S.; Akinola, Adekunle T.; Kabakov, Dmitri

2009-01-01

Polymer matrix composites (PMC), often referred to as fiber reinforced plastics (FRP), consist of fiber reinforcement (E-glass, S2-glass, aramid, carbon, or natural fibers) and polymer matrix/resin (polyester, vinyl ester, polyurethane, phenolic, and epoxies). Eglass/ polyester and E-glass/vinyl ester composites are extensively used in the marine,…

Controlled release from aspirin based linear biodegradable poly(anhydride esters) for anti-inflammatory activity.

PubMed

Dasgupta, Queeny; Movva, Sahitya; Chatterjee, Kaushik; Madras, Giridhar

2017-08-07

This work reports the synthesis of a novel, aspirin-loaded, linear poly (anhydride ester) and provides mechanistic insights into the release of aspirin from this polymer for anti-inflammatory activity. As compared to conventional drug delivery systems that rely on diffusion based release, incorporation of bioactives in the polymer backbone is challenging and high loading is difficult to achieve. In the present study, we exploit the pentafunctional sugar alcohol (xylitol) to provide sites for drug (aspirin) attachment at its non-terminal OH groups. The terminal OH groups are polymerized with a diacid anhydride. The hydrolysis of the anhydride and ester bonds under physiological conditions release aspirin from the matrix. The resulting poly(anhydride ester) has high drug loading (53%) and displays controlled release kinetics of aspirin. The polymer releases 8.5 % and 20%, of the loaded drug in one and four weeks, respectively and has a release rate constant of 0.0035h -0.61 . The release rate is suitable for its use as an anti-inflammatory agent without being cytotoxic. The polymer exhibits good cytocompatibility and anti-inflammatory properties and may find applications as injectable or as an implantable bioactive material. The physical insights into the release mechanism can provide development of other drug loaded polymers. Copyright © 2017 Elsevier B.V. All rights reserved.

Water-soluble polymers and compositions thereof

DOEpatents

Smith, B.F.; Robison, T.W.; Gohdes, J.W.

1999-04-06

Water-soluble polymers including functionalization from the group of amino groups, carboxylic acid groups, phosphonic acid groups, phosphonic ester groups, acylpyrazolone groups, hydroxamic acid groups, aza crown ether groups, oxy crown ethers groups, guanidinium groups, amide groups, ester groups, aminodicarboxylic groups, permethylated polyvinylpyridine groups, permethylated amine groups, mercaptosuccinic acid groups, alkyl thiol groups, and N-alkylthiourea groups are disclosed.

Water-soluble polymers and compositions thereof

DOEpatents

Smith, Barbara F.; Robison, Thomas W.; Gohdes, Joel W.

2002-01-01

Water-soluble polymers including functionalization from the group of amino groups, carboxylic acid groups, phosphonic acid groups, phosphonic ester groups, acylpyrazolone groups, hydroxamic acid groups, aza crown ether groups, oxy crown ethers groups, guanidinium groups, amide groups, ester groups, aminodicarboxylic groups, permethylated polvinylpyridine groups, permethylated amine groups, mercaptosuccinic acid groups, alkyl thiol groups, and N-alkylthiourea groups are disclosed.

Water-soluble polymers and compositions thereof

DOEpatents

Smith, Barbara F.; Robison, Thomas W.; Gohdes, Joel W.

1999-01-01

Water-soluble polymers including functionalization from the group of amino groups, carboxylic acid groups, phosphonic acid groups, phosphonic ester groups, acylpyrazolone groups, hydroxamic acid groups, aza crown ether groups, oxy crown ethers groups, guanidinium groups, amide groups, ester groups, aminodicarboxylic groups, permethylated polyvinylpyridine groups, permethylated amine groups, mercaptosuccinic acid groups, alkyl thiol groups, and N-alkylthiourea groups are disclosed.

Green polymer chemistry: The role of Candida antarctica lipase B in polymer functionalization

NASA Astrophysics Data System (ADS)

Castano Gil, Yenni Marcela

The synthesis of functional polymers with well-defined structure, end-group fidelity and physico-chemical properties useful for biomedical applications has proven challenging. Chemo-enzymatic methods are an alternative strategy to increase the diversity of functional groups in polymeric materials. Specifically, enzyme-catalyzed polymer functionalization carried out under solventless conditions is a great advancement in the design of green processes for biomedical applications, where the toxicity of solvents and catalyst residues need to be considered. Enzymes offer several distinct advantages, including high efficiency, catalyst recyclability, and mild reaction conditions. This reseach aimed to precisely functionalized polymers using two methods: enzyme-catalyzed functionalization via polymerization and chemo-enzymatic functionalization of pre-made polymers for drug delivery. In the first method, well-defined poly(caprolactone)s were generated using alkyne-based initiating systems catalyzed by CALB. Propargyl alcohol and 4-dibenzocyclooctynol (DIBO) were shown to efficiently initiate the ring opening polymerization of epsilon-caprolactone under metal free conditions and yielded polymers with Mn ~4 to 24 KDa and relatively narrow molecular mass distribution. In the second methodology, we present quantitative enzyme-catalyzed transesterification of vinyl esters and ethyl esters with poly(ethylene glycol)s (PEG)s that will serve as building blocks for dendrimer synthesis, followed by introducing a new process for the exclusive gamma-conjugation of folic acid. Specifically, fluorescein-acrylate was enzymatically conjugated with PEG. Additionally, halo-ester functionalized PEGs were successfully prepared by the transesterification of alkyl halo-esters with PEGs. 1H and 13C NMR spectroscopy, SEC and MALDI-ToF mass spectrometry confirmed the structure and purity of the products.

Phenolic components of the primary cell wall. Feruloylated disaccharides of D-galactose and L-arabinose from spinach polysaccharide.

PubMed Central

Fry, S C

1982-01-01

1. Cell walls from rapidly growing cell suspension cultures of Spinacia oleracea L. contained ferulic acid and p-coumaric acid esterified with a water-insoluble polymer. 2. Prolonged treatment with trypsin did not release may feruloyl esters from dearabinofuranosylated cell walls, and the polymer was also insoluble in phenol/acetic acid/water (2:1:1, w/v/v). 3. Treatment of the cell walls with the fungal hydrolase preparation "Driselase' did liberate low-Mr feruloyl esters. The major esters were 4-O-(6-O-feruloyl-beta-D-galactopyranosyl)-D-galactose and 3?-O-feruloyl-alpha-L-arabinopyranosyl)-L-arabinose. These two esters accounted for about 60% of the cell-wall ferulate. 4. It is concluded that the feruloylation of cell-wall polymers is not a random process, but occurs at very specific sites, probably on the arabinogalactan component of pectin. 5. The possible role of such phenolic substituents in cell-wall architecture and growth is discussed. PMID:7115300

A New Epoxy Bis-Phosphonate Crosslinker for Durable Fire Retardancy on Cotton

USDA-ARS?s Scientific Manuscript database

A new epoxy bis-phosphonate crosslinker for cotton [2-(dimethoxy-phosphorylmethyl)-oxiranylmethyl]-phosphonic acid dimethyl ester was prepared in two steps from 3-chloro-2-chloromethylpropene in 55% yield. The new monomer was characterized by proton and carbon NMR and GC-mass spectrometry. This cro...

40 CFR Appendix I to Part 192 - Listed Constituents

Code of Federal Regulations, 2012 CFR

2012-07-01

... (Propanedinitrile) Melphalan (L-Phenylalanine, 4-[bis(2-chloroethyl)aminol]-) Mercury and compounds, N.O.S. Mercury...) Amitrole (lH-1,2,4-Triazol-3-amine) Ammonium vanadate (Vanadic acid, ammonium salt) Aniline (Benzenamine...[N,N-dimethyl-]) Azaserine (L-Serine, diazoacetate (ester)) Barium and compounds, N.O.S. Barium...

40 CFR Appendix I to Part 192 - Listed Constituents

Code of Federal Regulations, 2014 CFR

2014-07-01

... (Propanedinitrile) Melphalan (L-Phenylalanine, 4-[bis(2-chloroethyl)aminol]-) Mercury and compounds, N.O.S. Mercury...) Amitrole (lH-1,2,4-Triazol-3-amine) Ammonium vanadate (Vanadic acid, ammonium salt) Aniline (Benzenamine...[N,N-dimethyl-]) Azaserine (L-Serine, diazoacetate (ester)) Barium and compounds, N.O.S. Barium...

40 CFR Appendix I to Part 192 - Listed Constituents

Code of Federal Regulations, 2013 CFR

2013-07-01

... (Propanedinitrile) Melphalan (L-Phenylalanine, 4-[bis(2-chloroethyl)aminol]-) Mercury and compounds, N.O.S. Mercury...) Amitrole (lH-1,2,4-Triazol-3-amine) Ammonium vanadate (Vanadic acid, ammonium salt) Aniline (Benzenamine...[N,N-dimethyl-]) Azaserine (L-Serine, diazoacetate (ester)) Barium and compounds, N.O.S. Barium...

Rapid characterization of lithium ion battery electrolytes and thermal aging products by low-temperature plasma ambient ionization high-resolution mass spectrometry.

PubMed

Vortmann, Britta; Nowak, Sascha; Engelhard, Carsten

2013-03-19

Lithium ion batteries (LIBs) are key components for portable electronic devices that are used around the world. However, thermal decomposition products in the battery reduce its lifetime, and decomposition processes are still not understood. In this study, a rapid method for in situ analysis and reaction monitoring in LIB electrolytes is presented based on high-resolution mass spectrometry (HR-MS) with low-temperature plasma probe (LTP) ambient desorption/ionization for the first time. This proof-of-principle study demonstrates the capabilities of ambient mass spectrometry in battery research. LTP-HR-MS is ideally suited for qualitative analysis in the ambient environment because it allows direct sample analysis independent of the sample size, geometry, and structure. Further, it is environmental friendly because it eliminates the need of organic solvents that are typically used in separation techniques coupled to mass spectrometry. Accurate mass measurements were used to identify the time-/condition-dependent formation of electrolyte decomposition compounds. A LIB model electrolyte containing ethylene carbonate and dimethyl carbonate was analyzed before and after controlled thermal stress and over the course of several weeks. Major decomposition products identified include difluorophosphoric acid, monofluorophosphoric acid methyl ester, monofluorophosphoric acid dimethyl ester, and hexafluorophosphate. Solvents (i.e., dimethyl carbonate) were partly consumed via an esterification pathway. LTP-HR-MS is considered to be an attractive method for fundamental LIB studies.

Gd(OTf)3-catalyzed synthesis of geranyl esters for the intramolecular radical cyclization of their epoxides mediated by titanocene(III).

PubMed

García Santos, William H; Puerto Galvis, Carlos E; Kouznetsov, Vladimir V

2015-02-07

A selective and mild method for the esterification of a variety of carboxylic acids with geraniol is developed. We demonstrated that the use of triphenylphosphine, I2, 2-methylimidazole or imidazole and a catalytic amount of Gd(OTf)3 resulted to be more active than the previous protocols, providing a 16-membered library of geranyl esters in higher yields and in shorter reaction times. The use of essential oil of palmarosa (Cymbopogon martinii), enriched with geraniol, as a raw material for the synthesis of the target compounds complemented and proved how sustainable and eco-friendly this protocol is. Finally, the selective 6,7-epoxidation of the obtained geranyl esters led us to study their regio-controlled radical cyclization mediated by titanocene(III) for the synthesis of novel (8-hydroxy-9,9-dimethyl-5-methylene cyclohexyl)methyl esters in moderate yields and with excellent stereoselectivities.

Production, purification, and properties of a lipase from a bacterium (Pseudomonas aeruginosa YS-7) capable of growing in water-restricted environments.

PubMed Central

Shabtai, Y; Daya-Mishne, N

1992-01-01

An extracellular lipase from the low-water-tolerant bacterium P. aeruginosa YS-7 was produced, purified, and characterized with respect to its functional properties in aqueous solutions and organic solvents. The enzyme was partially released from the cells during fermentation in defined medium with 5% (wt/vol) soybean oil. Approximately one-half of the total culture activity remained in solution after removal of cells. More than 95% of the activity was found in culture supernatant after mild detergent treatment (10 mM sodium deoxycholate) or after shifting the carbon source during the fermentation from triglyceride to a free fatty acid. The enzyme was recovered from an acetone precipitate of the whole culture and purified by hydrophobic interaction chromatography, yielding a preparation having a specific activity of about 1,300 mumol of fatty acid mg-1 h-1. The lipase (molecular size, approximately 40 kDa) hydrolyzes a variety of fatty acid esters and has an optimum pH of about 7. The enzyme retained its full activity at 20 to 55 degrees C, even after prolonged exposure (more than 30 days) to different concentrations of water-miscible organic solvents such as alcohols, glycols, pyridine, acetonitrile, dimethyl formamide, and dimethyl sulfoxide. The hydrolysis of 4-nitrophenyl laurate ester and of triglyceride emulsified in water was slightly accelerated with increasing concentrations of alcohols and glycols up to about 20% but was abolished with a further increase in alcohol concentration or in the presence of acetonitrile. In contrast, the rate of hydrolysis of these substrates in concentrated solutions of dimethyl formamide or dimethyl sulfoxide was markedly increased, by more than twofold and more than fivefold, respectively.(ABSTRACT TRUNCATED AT 250 WORDS) Images PMID:1539972

Purification and Characterization of a New Antifungal Compound 10-(2,2-dimethyl-cyclohexyl)-6,9-dihydroxy-4,9-dimethyl-dec-2-enoic Acid Methyl Ester from Streptomyces hydrogenans Strain DH16

PubMed Central

Kaur, Talwinder; Kaur, Amarjeet; Sharma, Vishal; Manhas, Rajesh K.

2016-01-01

In agriculture, biocontrol agents have been emerged as safe alternative to chemical pesticides where Streptomyces spp. and their metabolites constitute a great potential for their exploration as potent agents for controlling various fungal phytopathogens. The present study reports an antifungal compound purified from Streptomyces hydrogenans strain DH16, a soil isolate, using silica gel chromatography and semi preparative HPLC. The compound was characterized using various spectroscopic techniques (IR, 1H and 13C NMR) and named 10-(2,2-dimethyl-cyclohexyl)-6,9-dihydroxy-4,9-dimethyl-dec-2-enoic acid methyl ester (SH2). Compound (SH2) showed significant inhibitory activity against fungal phytopathogens and resulted in severe morphological aberrations in their structure. Minimal inhibitory and minimal fungicidal concentrations of the compound ranged from 6.25 to 25 μg/ml and 25 to 50 μg/ml, respectively. In vivo evaluation of the compound showed strong control efficacy against Alternaria brassicicola, a seed borne pathogen, on radish seeds. In comparison to mancozeb and carbendazim, the compound was more effective in controlling damping off disease. Additionally, it promoted plant growth with increased rate of seed germination, and displayed no phytotoxicity. The compound retained its antifungal activity after its exposure to temperature of 100°C and sunlight for 1 h. Furthermore, the compound (SH2) when tested for its biosafety was found to be non-cytotoxic, and non-mutagenic against Salmonella typhimurium TA98 and TA100 strains. This compound from S. hydrogenans strain DH16 has not been reported earlier, so this new compound can be developed as an ideal safe and superior biofungicide for the control of various fungal plant diseases. PMID:27446043

Thermosetting Phthalocyanine Polymers

NASA Technical Reports Server (NTRS)

Fohlen, G.; Parker, J.; Achar, B.

1985-01-01

Group of phthalocyanine polymers resist thermal degradation. Polymers expected semiconducting. Principal applications probably in molded or laminated parts that have to withstand high temperatures. Polymers made from either of two classes of monomer: Bisphthalonitriles with imide linkages or Bisphthalonitriles with ester-imide linkages.

Counterbalancing of morphology and conductivity of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate based flexible devices.

PubMed

Jang, Woongsik; Ahn, Sunyong; Park, Soyun; Park, Jong Hyeok; Wang, Dong Hwan

2016-12-01

The importance of conductive polymer electrodes with a balance between the morphology and electrical conductivity for flexible organic photovoltaic properties has been demonstrated. Highly transparent PEDOT:PSS anodes with controlled conductivity and surface properties were realized by insertion of dimethyl sulfoxide (DMSO) and a fluorosurfactant (Zonyl) as efficient additives and used for flexible organic photovoltaic cells (OPVs) which are based on a bulk-heterojunction of polythieno[3,4-b]-thiophene-co-benzodithiophene (PTB7):[6,6]phenyl-C 71 -butyric acid methyl ester (PC 71 BM). We investigated the correlation between the electrical properties of PEDOT:PSS electrodes and their influences on the surface morphology of the active materials (PTB7:PC 71 BM). When the device was prepared from the PEDOT:PSS layer functioning as an anode of OPV through an optimized ratio of 5 vol% of DMSO and 0.1 wt% of fluorosurfactant, the devices exhibited improved fill factor (FF) due to the enhanced coverage of PEDOT:PSS films. These results correlate with reduced photoluminescence and increased charge extraction as seen through Raman spectroscopy and electrical analysis, respectively. The conductive polymer electrode with the balance between the morphology and electrical conductivity can be a useful replacement for brittle electrodes such as those made of indium tin oxide (ITO) as they are more resistant to cracking and bending conditions, which will contribute to the long-term operation of flexible devices.

Diels-Alder Trapping of Photochemically Generated o-Quinodimethane Intermediates: An Alternative Route to Photocured Polymer Film Development

NASA Technical Reports Server (NTRS)

Tyson, Daniel S.; Ilhan, Faysal; Meador, Mary Ann B.; Smith, Dee Dee; Scheiman, Daniel A.; Meador, Michael A.

2004-01-01

Photolysis of o-methylphenyl ketones generates bis-o-quinodimethane intermediates that can be trapped in situ by dienophiles through Diels-Alder cycloadditions. This well-known photochemical process is applied to a series of six new photoreactive monomers containing bis-(o-methylphenyl ketone) functionalities combined with diacrylate and triacrylate ester monomers for the development of acrylic ester copolymer blends. Irradiation of cyclohexanone solutions of the bis-(o-methylphenyl ketone)s and acrylate esters produce thin polymer films. Solid state 13C NMR data indicated 47- 100% reaction of the bis-(o-methylphenyl ketone)s, depending on experimental conditions, to yield the desired products. DSC and TGA analyses were performed to determine the glass transition temperature, T,, and onset of decomposition, Td, of the resulting polymer films. A statistical Design of Experiments approach was used to obtain a systematic understanding of the effects of experimental variables on the extent of polymerization and the final polymer properties.

Poly(ortho esters)--from concept to reality.

PubMed

Heller, Jorge; Barr, John

2004-01-01

The development of poly(ortho esters) dates back to the early 1970s, and during that time, four distinct families were developed. These polymers can be prepared by a transesterification reaction or by the addition of polyols to diketene acetals, and it is the latter method that has proven to be preferred one. The latest polymer, now under intense development, incorporates a latent acid segment in the polymer backbone that takes advantage of the acid-labile nature of the ortho ester linkages and allows control over erosion rates. By use of diols having selected chain flexibility, polymers that range from hard, brittle materials to materials that have a gel-like consistency at room temperature can be obtained. Drug release from solid materials will be illustrated with 5-fluorouacil and bovine serum albumin, and drug release from gel-like materials will be illustrated with mepivacaine, now in Phase II clinical trials as a delivery system to treat post-operative pain. A brief summary of preclinical toxicology studies is also presented.

Physical and mechanical testing of essential oil-embedded cellulose ester films

USDA-ARS?s Scientific Manuscript database

Polymer films made from cellulose esters are useful for embedding plant essential oils, either for food packaging or air freshener applications. Studies and testing were done on the physical and mechanical properties of cellulose ester-based films incorporating essential oils (EO) from lemongrass (C...

Potential Pharmacologic Treatments for Cystinuria and for Calcium Stones Associated with Hyperuricosuria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldfarb, David S.

Two new potential pharmacologic therapies for recurrent stone disease are described. The role of hyperuricosuria in promoting calcium stones is controversial with only some but not all epidemiologic studies demonstrating associations between increasing urinary uric acid excretion and calcium stone disease. The relationship is supported by the ability of uric acid to 'salt out' (or reduce the solubility of) calcium oxalate in vitro. A randomized, controlled trial of allopurinol in patients with hyperuricosuria and normocalciuria was also effective in preventing recurrent stones. Febuxostat, a nonpurine inhibitor of xanthine oxidase (also known as xanthine dehydrogenase or xanthine oxidoreductase) may have advantagesmore » over allopurinol and is being tested in a similar protocol, with the eventual goal of determining whether urate-lowering therapy prevents recurrent calcium stones. Treatments for cystinuria have advanced little in the past 30 years. Atomic force microscopy has been used recently to demonstrate that effective inhibition of cystine crystal growth is accomplished at low concentrations of L-cystine methyl ester and L-cystine dimethyl ester, structural analogs of cystine that provide steric inhibition of crystal growth. In vitro, L-cystine dimethyl ester had a significant inhibitory effect on crystal growth. The drug's safety and effectiveness will be tested in an Slc3a1 knockout mouse that serves as an animal model of cystinuria.« less

Addition-type polyimides from solutions of monomeric reactants

NASA Technical Reports Server (NTRS)

Delvigs, P.; Serafini, T. T.; Lightsey, G. R.

1972-01-01

The monomeric reactants approach was used to fabricate addition-type polyimide/graphite fiber composites with improved mechanical properties and thermal stability characteristics over those of composites derived from addition-type amide acid prepolymers. A screening study of 24 different monomer combinations was performed. The results of a more extensive investigation of a selected number of monomer combinations showed that the combination providing the best thermomechanical properties was 5-norbornene-2,3-dicarboxylic acid monomethyl ester/4,4'-methylenedianiline/3,3'4,4'-benzophenone tetracarboxylic acid dimethyl ester at a molar ratio of 2/3.09/2.09.

Physical Properties of Substituted Imidazolium Based Ionic Liquids Gel Electrolytes

NASA Astrophysics Data System (ADS)

Sutto, Thomas E.; De Long, Hugh C.; Trulove, Paul C.

2002-11-01

The physical properties of solid gel electrolytes of either polyvinylidene diflurohexafluoropropylene or a combination of polyvinylidene hexafluoropropylene and polyacrylic acid, and the molten salts 1-ethyl-3-methylimidazolium tetrafluoroborate, 1,2-dimethyl-3-n-propylimidazolium tetrafluoroborate, and the new molten salts 1,2-dimethyl-3-n-butylimidazolium tetrafluoroborate, and 1,2-dimethyl-3-n-butylimidazolium hexafluorophosphate were characterized by temperature dependent ionic conductivity measurements for both the pure molten salt and of the molten salt with 0.5 M Li+ present. Ionic conductivity data indicate that for each of the molten salts, the highest concentration of molten salt allowable in a single component polymer gel was 85%, while gels composed of 90%molten salt were possible when using both polyvinylidene hexafluorophosphate and polyacrylic acid. For polymer gel composites prepared using lithium containing ionic liquids, the optimum polymer gel composite consisted of 85% of the 0.5 M Li+/ionic liquid, 12.75% polyvinylidene hexafluoropropylene, and 2.25% poly (1-carboxyethylene). The highest ionic conductivity observed was for the gel containing 90%1-ethyl-3-methyl-imidazolium tetrafluoroborate, 9.08 mS/cm. For the lithium containing ionic liquid gels, their ionic conductivity ranged from 1.45 to 0.05 mS/cm, which is comparable to the value of 0.91 mS/cm, observed for polymer composite gels containing 0.5 M LiBF4 in propylene carbonate.

Influence of polymer:sensitizer ratio on photoelectric properties of organic composite photoconductor

NASA Astrophysics Data System (ADS)

Aleman, K.; Sanchez Juarez, A.; Kosarev, A.; Mansurova, S.; Koeber, S.; Meerholz, K.

2010-06-01

The results on characterization of the main photoelectric properties of the polymer:fulleren based composite material by using the non-steady-state photo-electromotive force (p-EMF) and modulated photocurrent technique are presented. By measuring this current under different experimental conditions, important material photoelectric parameters such as drift L0 and diffusion length LD, photocarrier's lifetime τ ; quantum efficiency of charge generation φ can be determined. The 50% of the composite weight consists of a mixture of the hole-conducting polymer PF6:TPD (poly-hexyle-triophene:N,N'-bis(4-methylphenyl)-N,N'-bis-(phenyl)-benzidine) sensitized with the highly soluble C60 derivative PCBM (phenyl-C61-butyric acid methyl ester) . Seven samples with varied polymer:sensitizer weight ratio (49:1wt.-%, 45:5wt.-%, 40:10wt.-%, 15:35wt.-%, 25:25wt.-%, 10:40wt.-%, 5:45wt.-%) where prepared. The remaining 50% were two azo-dyes 2,5-dimethyl-(4-p-nitrophenylazo)-anisole (DMNPAA) and 3- methoxy-(4-p-nitrophenylazo)-anisole (MNPAA) (25wt.-% each). Photoconductive composite film was sandwiched between two glass plates covered by transparent ITO electrodes. Two counter-propagating beams derived from a cw HeNe laser (λ = 633nm) intersected inside the detector creating an interference pattern. The output photo-EMF current (SEE MANUSCRIPT FOR EQUATION) was detected as a voltage drop by a lock-in amplifier. At polymer sensitizer ratio 25:25wt.-% the signal sign changes to the opposite revealing that the majority carriers at this and higher concentration of sensitizer are electrons. Our results show that the majority carrier's lifetime τ is only slightly affected by the variations of sensitizer concentration. Mobility-lifetime product μhτh of holes, on its turn decreases at the increasing sensitizer concentration, while μeτe of electrons keeps increasing. All this indicates that the carrier's mobility is strongly influenced by the changes on sensitizer concentrations.

21 CFR 175.260 - Partial phosphoric acid esters of polyester resins.

Code of Federal Regulations, 2012 CFR

2012-04-01

... resins are prepared by the reaction of trimellitic anhydride with 2,2-dimethyl-1,3-propanediol followed by reaction of the resin thus produced with phosphoric acid anhydride to produce a resin having an... conditions of time and temperature characterizing the conditions of its intended use, as determined from...

21 CFR 175.260 - Partial phosphoric acid esters of polyester resins.

Code of Federal Regulations, 2013 CFR

2013-04-01

... resins are prepared by the reaction of trimellitic anhydride with 2,2-dimethyl-1,3-propanediol followed by reaction of the resin thus produced with phosphoric acid anhydride to produce a resin having an... conditions of time and temperature characterizing the conditions of its intended use, as determined from...

Dimethyl carbonate-mediated lipid extraction and lipase-catalyzed in situ transesterification for simultaneous preparation of fatty acid methyl esters and glycerol carbonate from Chlorella sp. KR-1 biomass.

PubMed

Jo, Yoon Ju; Lee, Ok Kyung; Lee, Eun Yeol

2014-04-01

Fatty acid methyl esters (FAMEs) and glycerol carbonate were simultaneously prepared from Chlorella sp. KR-1 containing 40.9% (w/w) lipid using a reactive extraction method with dimethyl carbonate (DMC). DMC was used as lipid extraction agent, acyl acceptor for transesterification of the extracted triglycerides, substrate for glycerol carbonate synthesis from glycerol, and reaction medium for the solvent-free reaction system. For 1g of biomass, 367.31 mg of FAMEs and 16.73 mg of glycerol carbonate were obtained under the optimized conditions: DMC to biomass ratio of 10:1 (v/w), water content of 0.5% (v/v), and Novozyme 435 to biomass ratio of 20% (w/w) at 70°C for 24h. The amount of residual glycerol was only in the range of 1-2.5mg. Compared to conventional method, the cost of FAME production with the proposed technique could be reduced by combining lipid extraction with transesterification and omitting the extraction solvent recovery process. Copyright © 2014 Elsevier Ltd. All rights reserved.

The transition from linear to highly branched poly(β-amino ester)s: Branching matters for gene delivery

PubMed Central

Zhou, Dezhong; Cutlar, Lara; Gao, Yongsheng; Wang, Wei; O’Keeffe-Ahern, Jonathan; McMahon, Sean; Duarte, Blanca; Larcher, Fernando; Rodriguez, Brian J.; Greiser, Udo; Wang, Wenxin

2016-01-01

Nonviral gene therapy holds great promise but has not delivered treatments for clinical application to date. Lack of safe and efficient gene delivery vectors is the major hurdle. Among nonviral gene delivery vectors, poly(β-amino ester)s are one of the most versatile candidates because of their wide monomer availability, high polymer flexibility, and superior gene transfection performance both in vitro and in vivo. However, to date, all research has been focused on vectors with a linear structure. A well-accepted view is that dendritic or branched polymers have greater potential as gene delivery vectors because of their three-dimensional structure and multiple terminal groups. Nevertheless, to date, the synthesis of dendritic or branched polymers has been proven to be a well-known challenge. We report the design and synthesis of highly branched poly(β-amino ester)s (HPAEs) via a one-pot “A2 + B3 + C2”–type Michael addition approach and evaluate their potential as gene delivery vectors. We find that the branched structure can significantly enhance the transfection efficiency of poly(β-amino ester)s: Up to an 8521-fold enhancement in transfection efficiency was observed across 12 cell types ranging from cell lines, primary cells, to stem cells, over their corresponding linear poly(β-amino ester)s (LPAEs) and the commercial transfection reagents polyethyleneimine, SuperFect, and Lipofectamine 2000. Moreover, we further demonstrate that HPAEs can correct genetic defects in vivo using a recessive dystrophic epidermolysis bullosa graft mouse model. Our findings prove that the A2 + B3 + C2 approach is highly generalizable and flexible for the design and synthesis of HPAEs, which cannot be achieved by the conventional polymerization approach; HPAEs are more efficient vectors in gene transfection than the corresponding LPAEs. This provides valuable insight into the development and applications of nonviral gene delivery and demonstrates great prospect for their translation to a clinical environment. PMID:27386572

RECOVERY OF LACTIC ACID FROM AMERICAN CRYSTAL SUGAR COMPANY WASTEWATER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daniel J. Stepan; Edwin S. Olson; Richard E. Shockey

2001-04-30

This project has shown that the recovery of several valuable lactic acid products is both technically feasible and economically viable. One of the original objectives of this project was to recover lactic acid. However, the presence of a variety of indigenous bacteria in the wastewater stream and technical issues related to recovery and purification have resulted in the production of lactic acid esters. These esters could by hydrolyzed to lactic acid, but only with unacceptable product losses that would be economically prohibitive. The developed process is projected to produce approximately 200,000 lb per day of lactate esters from wastewater atmore » a single factory at costs that compete with conventional solvents. The lactate esters are good solvents for polymers and resins and could replace acetone, methyl ethyl ketone, MIBK, and other polar solvents used in the polymer industry. Because of their low volatility and viscosity-lowering properties, they will be especially useful for inks for jet printers, alkyl resins, and high-solid paints. Owing to their efficiency in dissolving salts and flux as well as oils and sealants, lactate esters can be used in cleaning circuit boards and machine and engine parts. Unlike conventional solvents, lactate esters exhibit low toxicity, are biodegradable, and are not hazardous air pollutants. Another application for lactate esters is in the production of plasticizers. Severe health problems have been attributed to widely used phthalate ester plasticizers. The U.S. Department of Agriculture showed that replacement of these with inexpensive lactate esters is feasible, owing to their superior polymer compatibility properties. A very large market is projected for polymers prepared from lactic acid. These are called polylactides and are a type of polyester. Thermoplastics of this type have a variety of uses, including moldings, fibers, films, and packaging of both manufactured goods and food products. Polylactides form tough, orientable, self-supporting thin films and have, therefore, been used for adhesives, safety glass, and finishes. If the bacterial culture produces the L-lactic acid enanatiomer form exclusively, the L-lactide prepared from this form can be used for making polymers with good fiber-forming properties. We have not currently achieved the exclusive production of L-lactate in our efforts. However, markets in films and structural shapes are available for polymers and copolymers prepared from the mixed D,L-lactide forms that result from processing the D,L-lactic acid obtained from fermentation such as that occurring naturally in sugar beet wastewater. These materials are slowly biodegraded to harmless compounds in the environment, and they burn with a clean blue flame when incinerated. These materials represent excellent opportunities for utilization of the D,L-lactic mixture produced from natural fermentation of the ACS flume water. Esters can be converted into a lactide, and the alcohol released from the ester can be recycled with no net consumption of the alcohol. Lactide intermediates could be produced locally and shipped to polymer producers elsewhere. The polymer and copolymer markets are extremely large, and the role of lactides in these markets is continuously expanding. The overall process can be readily integrated into existing factory wastewater operations. There are several environmental benefits that would be realized at the factories with incorporation of the lactate recovery process. The process reduces the organic loading to the existing wastewater treatment system that should result in enhanced operability with respect to both solids handling and treated-water quality. A higher-quality treated water will also help reduce odor levels from holding ponds. Several water reuse opportunities are probable, depending on the quality of treated water from the FT process.« less

40 CFR 721.10326 - 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate...

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2-propenoate (1:2), 2,2'-(1,2-diazenediyl)bis[2-methylbutanenitrile]- and 2,2'-(1,2-diazenediyl)bis[2-methylpropanenitrile]-initiated. 721.10326...

Synthesis of molecularly imprinted polymers by atom transfer radical polymerization for the solid-phase extraction of phthalate esters in edible oil.

PubMed

Chen, Ningning; He, Juan; Wu, Chaojun; Li, Yuanyuan; Suo, An; Wei, Hongliang; He, Lijun; Zhang, Shusheng

2017-03-01

Novel molecularly imprinted polymers of phthalate esters were prepared by atom transfer radical polymerization using methyl methacrylate as functional monomer, cyclohexanone as solvent, cuprous chloride as catalyst, 1-chlorine-1-ethyl benzene as initiator and 2,2-bipyridyl as cross-linker in the mixture of methanol and water (1:1, v/v). The effect of reaction conditions such as monomer ratio and template on the adsorption properties was investigated. The optimum condition was obtained by an orthogonal experiment. The obtained polymers were characterized using scanning electron microscopy. The binding property was studied with both static and dynamic methods. Results showed that the polymers exhibited excellent recognition capacity and outstanding selectivity for ten phthalate esters. Factors affecting the extraction efficiency of the molecularly imprinted solid-phase extraction were systematically investigated. An analytical method based on the molecularly imprinted coupled with gas chromatography and flame ionization detection was successfully developed for the simultaneous determination of ten phthalate esters from edible oil. The method detection limits were 0.10-0.25 μg/mL, and the recoveries of spiked samples were 82.5-101.4% with relative standard deviations of 1.24-5.37% (n = 6). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Miscibility of choline-substituted polyphosphazenes with PLGA and osteoblast activity on resulting blends.

PubMed

Weikel, Arlin L; Owens, Steven G; Morozowich, Nicole L; Deng, Meng; Nair, Lakshmi S; Laurencin, Cato T; Allcock, Harry R

2010-11-01

The preparation of phosphazene tissue engineering scaffolds with bioactive side groups has been accomplished using the biological buffer, choline chloride. Mixed-substituent phosphazene cyclic trimers (as model systems) and polymers with choline chloride and glycine ethyl ester, alanine ethyl ester, valine ethyl ester, or phenylalanine ethyl ester were synthesized. Two different synthetic protocols were examined. A sodium hydride mediated route resulted in polyphosphazenes with a low choline content, while a cesium carbonate mediated process produced polyphosphazenes with higher choline content. The phosphazene structures and physical properties were studied using multinuclear NMR, differential scanning calorimetry (DSC), and gel permeation chromatography (GPC) techniques. The resultant polymers were then blended with PLGA (50:50) or PLGA (85:15) and characterized by DSC analysis and scanning electron microscopy (SEM). Polymer products obtained via the sodium hydride route produced miscible blends with both ratios of PLGA, while the cesium carbonate route yielded products with reduced blend miscibility. Heterophase hydrolysis experiments in aqueous media revealed that the polymer blends hydrolyzed to near-neutral pH media (∼5.8 to 6.8). The effect of different molecular structures on cellular adhesion showed osteoblast proliferation with an elevated osteoblast phenotype expression compared to PLGA over a 21-day culture period. Copyright © 2010 Elsevier Ltd. All rights reserved.

High-Temperature and High-Energy-Density Dipolar Glass Polymers Based on Sulfonylated Poly(2,6-dimethyl-1,4-phenylene oxide).

PubMed

Zhang, Zhongbo; Wang, David H; Litt, Morton H; Tan, Loon-Seng; Zhu, Lei

2018-02-05

A new class of high-temperature dipolar polymers based on sulfonylated poly(2,6-dimethyl-1,4-phenylene oxide) (SO 2 -PPO) was synthesized by post-polymer functionalization. Owing to the efficient rotation of highly polar methylsulfonyl side groups below the glass transition temperature (T g ≈220 °C), the dipolar polarization of these SO 2 -PPOs was enhanced, and thus the dielectric constant was high. Consequently, the discharge energy density reached up to 22 J cm -3 . Owing to its high T g  , the SO 2 -PPO 25 sample also exhibited a low dielectric loss. For example, the dissipation factor (tan δ) was 0.003, and the discharge efficiency at 800 MV m -1 was 92 %. Therefore, these dipolar glass polymers are promising for high-temperature, high-energy-density, and low-loss electrical energy storage applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reaction pathway in vapour phase hydrogenation of maleic anhydride and its esters to {gamma}-butyrolactone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Messori, M.; Vaccari, A.

1994-11-01

The catalytic reactivity of maleic anhydride (MA), succinic anhydride (SA) and their dimethyl esters (dimethyl maleate and dimethyl succinate) in the vapour phase hydrogenation to {gamma}-butyrolacetone (GBL) was investigated. In order to obtain general data, both a multicomponent catalyst (CAT 1: Cu/Zn/Mg/Cr = 40:5:5:50, atomic ratio %), obtained by reduction of a nonstoichiometric spinel-type precursor, and a commercial catalyst (CAT 2: Cu/Mn/Ba/Cr = 44:8:1:47, atomic ratio %) were used. The MA/GBL solution exhibited the highest GBL production, while the SA/GBL solution was converted only partially due to a competitive adsorption of GBL on the active sites, as evidenced by themore » similar reactivities observed with pure anhydrides. The best carbon balances were observed with the esters, probably the result of lowest light hydrocarbon synthesis and tar formation. With all the feedstocks, the activity of CAT 2 is higher than that of CAT 1, which, however, gives the best yield in GBL due its lower activity in the overhydrogenation and hydrogenolysis reaction. It was found that n-butanol (BuOH) and butyric acid (BuA) derived mainly from GBL. On this basis, the reactivities of the main products observed were investigated separately, confirming the stability of tetrahydrofuran (THF), which reacted only at high temperature with low conversions to ethanol. On the other hand, GBL gave rise to overhydrogenation and/or hydrogenolysis, with high conversion (mainly with CAT 2), confirming its key role in both reactions. Furthermore, the formation in the catalytic tests with BuA and BuOH of n-butanal, notwithstanding the high H{sub 2}/organic ratio, implies that it is the main intermediate in the hydrogenolysis reactions. A new reaction scheme is proposed, pointing out the key role of GBL as the {open_quotes}intersection{close_quotes} of two possible reaction pathways, giving rise to THF or overhydrogenation and hydrogenolysis products, respectively. 44 refs., 4 figs., 6 tabs.« less

Synthetic approaches to peptides containing the L-Gln-L-Val-D(S)-Dmt motif.

PubMed

Suaifan, Ghadeer A R Y; Arafat, Tawfiq; Threadgill, Michael D

2007-05-15

The pseudoprolines S-Dmo (5,5-dimethyl-4-oxaproline) and R-Dmt (5,5-dimethyl-4-thiaproline) have been used to study the effects of forcing a fully cis conformation in peptides. Synthesis of peptides containing these (which have the same configuration as L-Pro) is straightforward. However, synthesis of peptides containing S-Dmt is difficult, owing to the rapid cyclisation of L-Aaa-S-Dmt amides and esters to form the corresponding diketopiperazines (DKP); thus the intermediacy of L-Aaa-S-Dmt amides and esters must be avoided in the synthetic sequence. Peptides containing the L-Gln-L-Val-D(S)-Dmt motif are particularly difficult, owing to the insolubility of coupling partners containing Gln. Introduction of Gln as N-Boc-pyroglutamate overcame the latter difficulty and the dipeptide active ester BocPygValOC(6)F(5) coupled in good yield with S-DmtOH. BocPygVal-S- DmtNH(CH(2))(2)C(6)H(4)NO(2) was converted quantitatively to BocGlnVal-S-DmtNH(CH(2))(2)C(6)H(4)NO(2) with ammonia, demonstrating the utility of this approach. Two peptide derivatives (CbzSerLysLeuGlnVal-S-DmtNH(CH(2))(2)C(6)H(4)NO(2) and CbzSerSerLysLeuGlnVal-S- DmtNH(CH(2))(2)C(6)H(4)NO(2)) were assembled, using these new methods of coupling a dipeptide acid active ester with S-DmtOH and introduction of Gln as Pyg, followed by conventional peptide couplings. The presence of the Val caused these peptides to be cleaved very slowly by prostate-specific antigen (PSA) at Leu Gln, rather than the expected Gln Val.

40 CFR 721.10326 - 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate...

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2-propenoate (1:2), 2,2â²-(1,2-diazenediyl)bis[2-methylbutanenitrile]- and 2,2â²-(1,2-diazenediyl)bis[2-methylpropanenitrile]-initiated. 721.10326...

40 CFR 721.10326 - 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate...

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2-propenoate (1:2), 2,2â²-(1,2-diazenediyl)bis[2-methylbutanenitrile]- and 2,2â²-(1,2-diazenediyl)bis[2-methylpropanenitrile]-initiated. 721.10326...

Cyanate Ester Resin Modified with Nano-particles for Inclusion in Continuous Fiber Reinforced Composites

DTIC Science & Technology

2011-02-25

thermogravimetric analyzer (TGA) from TA Instruments upon heating at 20 oC/min under air purge. The structural features of the nanoparticles were...low viscosity bisphenol E cyanate ester resin (BECy) resin reinforced with macro scale carbon fibers and negative CTE nanoparticles . Polymer...developed to improve the compatibility of the ZrW2O8 nanoparticles with the polymer matrix. The hybrid composites were prepared with 30 wt

Determination of phthalate esters from environmental water samples by micro-solid-phase extraction using TiO2 nanotube arrays before high-performance liquid chromatography.

PubMed

Zhou, Qingxiang; Fang, Zhi; Liao, Xiangkun

2015-07-01

We describe a highly sensitive micro-solid-phase extraction method for the pre-concentration of six phthalate esters utilizing a TiO2 nanotube array coupled to high-performance liquid chromatography with a variable-wavelength ultraviolet visible detector. The selected phthalate esters included dimethyl phthalate, diethyl phthalate, dibutyl phthalate, butyl benzyl phthalate, bis(2-ethylhexyl)phthalate and dioctyl phthalate. The factors that would affect the enrichment, such as desorption solvent, sample pH, salting-out effect, extraction time and desorption time, were optimized. Under the optimum conditions, the linear range of the proposed method was 0.3-200 μg/L. The limits of detection were 0.04-0.2 μg/L (S/N = 3). The proposed method was successfully applied to the determination of six phthalate esters in water samples and satisfied spiked recoveries were achieved. These results indicated that the proposed method was appropriate for the determination of trace phthalate esters in environmental water samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The possible participation of esters as well as amides in prebiotic polymers.

NASA Technical Reports Server (NTRS)

Rich, A.

1971-01-01

Demonstration that alpha-hydroxy acids may have participated in the formation of prebiological polymers in a manner similar to the participation of alpha-amino acids. Ex periments are described which indicate that the system for forming peptide bonds in present-day biological organisms is equally competent in forming ester and polyester bonds. In particular, the experiments described are directed toward answering questions regarding the action of peptidyl transferase in ester formation. Also, an attempt is made to determine whether a complete protein synthetic system can operate with transfer RNA molecules which have alpha-hydroxyl acids attached to them instead of alpha-amino acids, using both synthetic and natural mRNA. The ability of ribosomal peptidyl transferase to catalyze the formation of an ester bond as well as its normal product, the peptide bond, is demonstrated.

Post surgical pain management with poly(ortho esters).

PubMed

Barr, John; Woodburn, Kathryn W; Ng, Steven Y; Shen, Hui-Rong; Heller, Jorge

2002-10-16

Poly(ortho esters), POE, are synthetic bioerodible polymers that can be prepared as solid materials, or as viscous, injectable polymers. These materials have evolved through a number of families, and the latest member of this family, POE IV, is particularly well suited to drug delivery since latent acid is integrated into the polymer backbone, thereby, modulating surface erosion. POE IV predominantly undergoes surface erosion and is able to moderate drug release over periods from days to many months. One indication in which the POE IV polymer is currently being investigated is in sustained post-surgical pain management. The local anesthetic agent, mepivacaine, has been incorporated into a viscous, injectable POE IV and its potential to provide longer-acting anesthesia has been explored in non-clinical models.

Labelling Polymers and Micellar Nanoparticles via Initiation, Propagation and Termination with ROMP

PubMed Central

Thompson, Matthew P.; Randolph, Lyndsay M.; James, Carrie R.; Davalos, Ashley N.; Hahn, Michael E.

2014-01-01

In this paper we compare and contrast three approaches for labelling polymers with functional groups via ring-opening metathesis polymerization (ROMP). We explored the incorporation of functionality via initiation, termination and propagation employing an array of novel initiators, termination agents and monomers. The goal was to allow the generation of selectively labelled and well-defined polymers that would in turn lead to the formation of labelled nanomaterials. Norbornene analogues, prepared as functionalized monomers for ROMP, included fluorescent dyes (rhodamine, fluorescein, EDANS, and coumarin), quenchers (DABCYL), conjugatable moieties (NHS esters, pentafluorophenyl esters), and protected amines. In addition, a set of symmetrical olefins for terminally labelling polymers, and for the generation of initiators in situ is described. PMID:24855496

Developments in the use of rare earth metal complexes as efficient catalysts for ring-opening polymerization of cyclic esters used in biomedical applications

NASA Astrophysics Data System (ADS)

Cota, Iuliana

2017-04-01

Biodegradable polymers represent a class of particularly useful materials for many biomedical and pharmaceutical applications. Among these types of polyesters, poly(ɛ-caprolactone) and polylactides are considered very promising for controlled drug delivery devices. These polymers are mainly produced by ring-opening polymerization of their respective cyclic esters, since this method allows a strict control of the molecular parameters (molecular weight and distribution) of the obtained polymers. The most widely used catalysts for ring-opening polymerization of cyclic esters are tin- and aluminium-based organometallic complexes; however since the contamination of the aliphatic polyesters by potentially toxic metallic residues is particularly of concern for biomedical applications, the possibility of replacing organometallic initiators by novel less toxic or more efficient organometallic complexes has been intensively studied. Thus, in the recent years, the use of highly reactive rare earth initiators/catalysts leading to lower polymer contamination has been developed. The use of rare earth complexes is considered a valuable strategy to decrease the polyester contamination by metallic residues and represents an attractive alternative to traditional organometallic complexes.

The main chemical composition and in vitro antifungal activity of the essential oils of Ocimum basilicum Linn. var. pilosum (Willd.) Benth.

PubMed

Zhang, Ji-Wen; Li, Sheng-Kun; Wu, Wen-Jun

2009-01-08

The essential oils of the aerial parts of Ocimum basilicum Linn.var. pilosum (Willd.) Benth., an endemic medicinal plant growing in China, was obtained by hydrodistillation and analysed by GC-MS. Fifteen compounds, representing 74.19% of the total oil were identified. The main components were as follows: linalool (29.68%), (Z)-cinnamic acid methyl ester (21.49%), cyclohexene (4.41%), alpha- cadinol (3.99%), 2,4-diisopropenyl-1-methyl-1-vinylcyclohexane (2.27%), 3,5-pyridine-dicarboxylic acid, 2,6-dimethyl-diethyl ester (2.01%), beta-cubebene (1.97%), guaia-1(10),11-diene (1.58%), cadinene (1.41%) (E)-cinnamic acid methyl ester (1.36%) and beta-guaiene (1.30%). The essential oils showed significant antifungal activity against some plant pathogenic fungi.

Lignans and secoiridoid glycosides from the stem barks of Jasminum tortuosum.

PubMed

Tomassini, Lamberto; Ventrone, Antonio; Frezza, Claudio; Serafini, Ilaria; Bianco, Armandodoriano; Cometa, Maria Francesca

2018-08-01

This paper reports on the first phytochemical analysis ever performed on Jasminum tortuosum Willd. This analysis, mainly carried out by means of column chromatography separation, NMR spectroscopy and mass spectrometry, led to the isolation and the identification of four compounds, namely the lignans ginkgool (1) and olivil-4'-O-β-glucopyranoside (2) and the secoiridoids oleoside dimethyl ester (3) and oleoside 11-methyl ester (4). The presence of these compounds is significant from a chemotaxonomic point of view, confirming the correct botanical classification of the species and, from a phytochemical standpoint, may suggest its possible use in the ethno-medicinal field.

Development of l-Tyrosine-Based Enzyme-Responsive Amphiphilic Poly(ester-urethane) Nanocarriers for Multiple Drug Delivery to Cancer Cells.

PubMed

Aluri, Rajendra; Jayakannan, Manickam

2017-01-09

New classes of enzymatic-biodegradable amphiphilic poly(ester-urethane)s were designed and developed from l-tyrosine amino acid resources and their self-assembled nanoparticles were employed as multiple drug delivery vehicles in cancer therapy. The amine and carboxylic acid functional groups in l-tyrosine were converted into dual functional ester-urethane monomers and they were subjected to solvent free melt polycondensation with hydrophilic polyethylene glycols to produce comb-type poly(ester-urethane)s. The phenolic unit in the l-tyrosine was anchored with hydrophobic alkyl side chain to bring appropriate amphiphilicity in the polymer geometry to self-assemble them as stable nanoscaffolds in aqueous medium. The topology of the polymer was found to play a major role on the glass transition, crystallinity, and viscoelastic rheological properties of l-tyrosine poly(ester-urethane)s. The amphiphilic polymers were self-assembled as 200 ± 10 nm nanoparticles and they exhibited excellent encapsulation capabilities for anticancer drugs such as doxorubicin (DOX) and camptothecin (CPT). In vitro drug release studies revealed that the drug-loaded l-tyrosine nanoparticles were stable at extracellular conditions and they underwent enzymatic-biodegradation exclusively at the intracellular level to release the drugs. Cytotoxicity studies in the cervical cancer (HeLa) and normal WT-MEFs cell lines revealed that the nascent l-tyrosine nanoparticles were nontoxic, whereas the CPT and DOX drug-loaded polymer nanoparticles exhibited excellent cell killing in cancer cells. Confocal microscopic imaging confirmed the cellular internalization of drug-loaded nanoparticles. The drugs were taken up by the cells much higher quantity while delivering them from l-tyrosine nanoparticle platform compared to their free state. Flow cytometry analysis showed that the DOX-loaded polymer nanoscaffolds internalized the drugs 8-10× higher compared to free DOX. Both the synthesis of new classes of poly(ester-urethane)s via melt polycondensation approach and the enzyme-responsive drug delivery concept were accomplished for the first time. Thus, the present investigation is expected to open up new opportunities for l-tyrosine polymeric materials in biomaterial and thermoplastic applications.

pH- and ion-sensitive polymers for drug delivery

PubMed Central

Yoshida, Takayuki; Lai, Tsz Chung; Kwon, Glen S; Sako, Kazuhiro

2013-01-01

Introduction Drug delivery systems (DDSs) are important for effective, safe, and convenient administration of drugs. pH- and ion-responsive polymers have been widely employed in DDS for site-specific drug release due to their abilities to exploit specific pH- or ion-gradients in the human body. Areas covered Having pH-sensitivity, cationic polymers can mask the taste of drugs and release drugs in the stomach by responding to gastric low pH. Anionic polymers responsive to intestinal high pH are used for preventing gastric degradation of drug, colon drug delivery and achieving high bioavailability of weak basic drugs. Tumor-targeted DDSs have been developed based on polymers with imidazole groups or poly(β-amino ester) responsive to tumoral low pH. Polymers with pH-sensitive chemical linkages, such as hydrazone, acetal, ortho ester and vinyl ester, pH-sensitive cell-penetrating peptides and cationic polymers undergoing pH-dependent protonation have been studied to utilize the pH gradient along the endocytic pathway for intracellular drug delivery. As ion-sensitive polymers, ion-exchange resins are frequently used for taste-masking, counterion-responsive drug release and sustained drug release. Polymers responding to ions in the saliva and gastrointestinal fluids are also used for controlled drug release in oral drug formulations. Expert opinion Stimuli-responsive DDSs are important for achieving site-specific and controlled drug release; however, intraindividual, interindividual and intercellular variations of pH should be considered when designing DDSs or drug products. Combination of polymers and other components, and deeper understanding of human physiology are important for development of pH- and ion-sensitive polymeric DDS products for patients. PMID:23930949

New Insights into Structure-Property Relationships in Thermosetting Polymers from Studies of Co-Cured Polycyanurate Networks (Preprint)

DTIC Science & Technology

2011-12-19

have shown through positron annihilation studies that a substantial amount of free volume develops during the final stages of cyanate ester cure...Polymers from 5b. GRANT NUMBER Studies of Co-Cured Polycyanurate Networks (preprint) 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Andrew J. Guenthner...Macromolecules. 14. ABSTRACT Studies of the physical properties of the co-cured networks formed from three similar dicyanate ester monomers revealed a

Effect of Silicon Substitution on the Crystal Properties of Cyanate Ester Monomers (Briefing Charts)

DTIC Science & Technology

2015-08-17

unlimited.   Outline • Background / Motivation – Cyanate esters – Reasons for incorporating silicon into thermosetting resins • Cyanate esters with...Approved for public release; distribution is unlimited.   The Use of Si in Thermosetting Polymers • In addition to the expected increase in short

76 FR 32196 - Certain New Chemicals; Receipt and Status Information; Correction

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-03

... use (S) 2-propenoic Inc. of this polymer is acid, 2-methyl-, 2- for refinishing hydroxyethyl ester, vehicles. through polymer with rel- the hydroxyl groups (1r,2r,4r)-1,7,7- on the polymer, the...)-, (t-4)-, polymers; polymer with 3- surfactant, flow, methyl-3-[(2,2,2- leveling, and trifluoroethoxy...

The reduction of CrVI to CrIII by the alpha and beta anomers of D-glucose in dimethyl sulfoxide. A comparative kinetic and mechanistic study.

PubMed

Signorella, S; Lafarga, R; Daier, V; Sala, L F

2000-02-11

The reduction of CrVI by alpha-D-glucose and beta-D-glucose was studied in dimethyl sulfoxide in the presence of pyridinium p-toluensulfonate, a medium where mutarotation is slower than the redox reaction. The two anomers reduce CrVI by formation of an intermediate CrVI ester precursor of the slow redox step. The equilibrium constant for the formation of the intermediate chromic ester and the rate of the redox steps are different for each anomer. alpha-D-Glucose forms the CrVI-Glc ester with a higher equilibrium constant than beta-D-glucose, but the electron transfer within this complex is slower than for the beta anomer. The difference is attributed to the better chelating ability of the 1,2-cis-diolate moiety of the alpha anomer. The CrV species, generated in the reaction mixture, reacts with the two anomers at a rate comparable with that of CrVI. The EPR spectra show that the alpha anomer forms several linkage isomers of the five-coordinate CrV bis-chelate, while beta-D-glucose affords a mixture of six-coordinate CrV monochelate and five-coordinate CrV bis-chelate. The conversion of the CrV mono- to bis-chelate is discussed in terms of the ability of the 1,2-cis- versus 1,2-trans-diolate moieties of the glucose anomers to bind CrV.

Pinosylvin-Based Polymers: Biodegradable Poly(Anhydride-Esters) for Extended Release of Antibacterial Pinosylvin.

PubMed

Bien-Aime, Stephan; Yu, Weiling; Uhrich, Kathryn E

2016-07-01

Pinosylvin is a natural stilbenoid known to exhibit antibacterial bioactivity against foodborne bacteria. In this work, pinosylvin is chemically incorporated into a poly(anhydride-ester) (PAE) backbone via melt-condensation polymerization, and characterized with respect to its physicochemical and thermal properties. In vitro release studies demonstrate that pinosylvin-based PAEs hydrolytically degrade over 40 d to release pinosylvin. Pseudo-first order kinetic experiments on model compounds, butyric anhydride and 3-butylstilbene ester, indicate that the anhydride linkages hydrolyze first, followed by the ester bonds to ultimately release pinosylvin. An antibacterial assay shows that the released pinosylvin exhibit bioactivity, while in vitro cytocompatibility studies demonstrate that the polymer is noncytotoxic toward fibroblasts. These preliminary findings suggest that the pinosylvin-based PAEs can serve as food preservatives in food packaging materials by safely providing antibacterial bioactivity over extended time periods. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Organic Inorganic Hybrid Solar Cell Efficiency Improvement By Employing Au Nanocluster

DTIC Science & Technology

2015-06-14

ABSTRACT 16. SECURITY CLASSIFICATION OF: Poly( 3,4-ethyllenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS), a P-type organic polymer is frequently...Addition of small volume percentage of organic additives such as dimethyl sulfoxide (DMSO) has a positive effect on the conductivity of this polymer . In...Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 hybrid solar cell, tunable conductivity, organic polymer , heterojunction, nanocluster

Polymer compositions based on PXE

DOEpatents

Yang, Jin; Eitouni, Hany Basam; Singh, Mohit

2015-09-15

New polymer compositions based on poly(2,6-dimethyl-1,4-phenylene oxide) and other high-softening-temperature polymers are disclosed. These materials have a microphase domain structure that has an ionically-conductive phase and a phase with good mechanical strength and a high softening temperature. In one arrangement, the structural block has a softening temperature of about 210.degree. C. These materials can be made with either homopolymers or with block copolymers.

Facile synthesis of fluorescent polymer nanoparticles by covalent modification-nanoprecipitation of amine-reactive ester polymers.

PubMed

Lee, Yeonju; Hanif, Sadaf; Theato, Patrick; Zentel, Rudolf; Lim, Jeewoo; Char, Kookheon

2015-06-01

Emission wavelength control in fluorescent nanoparticles (NPs) is crucial for their applications. In the case of inorganic quantum dots or dye-impregnated silica NPs, such a control is readily achieved by changing the size of the particles or choosing appropriate fluorescent dyes, respectively. A similar modular approach for controlling the emission wavelength of fluo-rescent polymer NPs, however, is difficult. This article reports on fluorescent polymer NPs, the synthesis of which provides a platform for a modular approach towards the preparation of fluorescent NPs of desired emission wavelength. Atom-transfer radical polymerization (ATRP) is employed to synthesize reactive ester polymers, which are then easily modified with a commercially available dye and subsequently subjected to nanoprecipitation. The resulting NPs, with low size polydispersity, show an enhanced emission quantum yield when compared with the same dye molecules in solution. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface modification of medical implant materials with hydrophilic polymers for enhanced biocompatibility and delivery of therapeutic agents

NASA Astrophysics Data System (ADS)

Urbaniak, Daniel J.

2004-11-01

In the research reported here, the surface modification of medical grade poly(dimethyl siloxane), polyetherurethane, and stainless steel through gamma-radiation grafting of hydrophilic polymers was investigated. Emphasis was placed on developing improved and simplified surface modification methods that produce more stable and more bioacceptible hydrophilic graft surfaces. As a result of this research, new surface modification techniques were developed that yield significantly improved surface stability unachievable using previous surface modification techniques. The surface modification of poly(dimethyl siloxane) with hydrophilic polymers was carried out using gamma radiation initiated graft polymerization. The addition of alkali metal hydroxides afforded a unique way to enhance the grafting of N-vinyl-2 pyrrolidone, dimethylacryamide, 2-methacryloyloxyethyl phosphoryl choline, N,N-dimethyl-N-(methacryloyloxyethyl)-N-(3-sulfopropyl)-ammonium-betaine, N,N-dimethyl-N-(methacrylamidopropyl)-N-(3-sulfopropyl)-ammonium-betaine, and copolymers thereof to silicones. Ethanolamine was found to further enhance the grafting of some hydrophilic polymers to silicone. The resulting hydrophilic surface grafts were resistant to hydrophobic surface rearrangement. This process overcomes previous problems inherent in silicone surface modification. The technique was also found to moderately enhance the grafting of hydrophilic monomers to polyetherurethane and to 316-L stainless steel. The surface modification of 316-L stainless steel was further enhanced by treating the substrates with a chromium III methacrylate bonding agent prior to irradiation. The coatings were evaluated for their potential use as depots for delivering therapeutic agents. The release of ofloxacin from surface-modified poly(dimethyl siloxane) and dexamethasone from surface-modified 316-L stainless steel was evaluated by in-vitro experiments. Therapeutic levels of drugs were released from surface-modified specimens via a burst effect. Improved surface characterization methods were another aspect of this research. New nanomechanical testing techniques were developed and used to evaluate the viscoelastic surface mechanical properties of low modulus surface-modified specimens. Dynamic nanoindentation characterization techniques were designed to measure the storage modulus and loss modulus of compliant viscoelastic substrate surfaces. The results of these experiments were compared with modulus data obtained by conventional dynamic mechanical spectroscopy. Nanoscratch testing methods were also developed that qualitatively compared the abrasion resistance of surface-modified substrates. (Abstract shortened by UMI.)

Performance Loss of Lithium Ion Polymer Batteries Subjected to Overcharge and Overdischarge Abuse

DTIC Science & Technology

2012-11-16

hexafluorophosphate EC: ethylene carbonate DEC: diethyl carbonate DMC: dimethyl carbonate PC: propylene carbonate     2    2. Introduction  Lithium -ion...Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6110--12-9455 Performance Loss of Lithium Ion Polymer Batteries Subjected to Overcharge...ABSTRACT c. THIS PAGE 18. NUMBER OF PAGES 17. LIMITATION OF ABSTRACT Performance Loss of Lithium Ion Polymer Batteries Subjected to Overcharge and

Polymer-Oxide Nanolayer/Al Composite Cathode for Efficient Polymer Light-Emitting Diodes

DTIC Science & Technology

2007-06-30

4. Influence of polymer gate dielectrics on n-channel conduction of pentacene -based organic field-effect transistors J. Appl. Phys. 101, 124505...molecular materials, including rubrene, 1,3,5-tris(2-N-phenyl-benzimidzolyl)benzene (TPBI), pentacene , and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline...BCP, and pentacene . The inset in Fig. 3 presents the molecular structures. TPBI is often utilized as an effective electron injection and hole-blocking

Transition-Metal-Free Synthesis of 1,3-Butadiene-Containing π-Conjugated Polymers.

PubMed

Cai, Xuediao; Liu, Yating; Lu, Tian; Yang, Rui; Luo, Chuxin; Zhang, Qi; Chai, Yonghai

2016-12-01

This work describes the synthesis of π-conjugated polymers possessing arylene and 1,3-butadiene alternating units in the main chain by the reaction of α,β-unsaturated ester/nitrile containing γ-H with aromatic/heteroaromatic aldehyde compound. By using 4-(4-formylphenyl)-2-butylene acid ethyl ester as a model monomer, the different polymerization conditions, including catalyst, catalyst amount, and solvent, are optimized. The polymerization of 4-(4-formylphenyl)-2-butylene acid ethyl ester is carried out by refluxing in ethanol for 72 h with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as a catalyst to give a 1,3-butadiene-containing π-conjugated polymer, poly(phenylene-1,3-butadiene), in 84.3% yield with M¯n and M¯w/M¯n (PDI) estimated as 6172 and 1.65, respectively. Based on this new methodology, a series of π-conjugated polymers containing 1,3-butadiene units with different substituents are obtained in high yields. A possible mechanism is proposed for the polymerization through a six-membered ring transition state and then a 1,5-H shift intermediate. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Syntheses and properties of elastic copoly(ester-urethane)s containing a phospholipid moiety and the fabrication of nanosheets.

PubMed

Sirithep, Wariya; Morita, Kohei; Iwano, Atsushi; Komachi, Takuya; Okamura, Yosuke; Nagase, Yu

2014-01-01

In these years, we have investigated the syntheses of novel diamine and diol monomers containing phosphorylcholine (PC) group to obtain biocompatible polymers, the backbone components of which were thermally stable and mechanically strong. In this study, the preparations of elastic copoly(ester-urethane)s containing PC group and polycarbonate segment were carried out by polycondensation and polyaddition using a diol monomer containing PC group and polycarbonate diol. It was found that the obtained polymers exhibited the high-thermal stability up to 200 °C and the elasticity derived from the soft segment. The introduction of PC group was effective to improve the resistance to the adhesions of proteins and platelets on the polymer films, which was the result of surface properties derived from the PC moiety. In addition, we tried to prepare ultra-thin polymer films composed of copoly(ester-urethane)s, so-called nanosheets. As a result, the desired nanosheets were successfully fabricated and the obtained nanosheets exhibited the high adhesive strength, indicating that the nanosheets could conform closely to the desired surfaces due to their exquisite flexibility and low roughness.

Production of biodiesel from Coelastrella sp. microalgae

NASA Astrophysics Data System (ADS)

Mansur, Dieni; Fitriady, Muhammad Arifuddin; Susilaningsih, Dwi; Simanungkalit, Sabar Pangihutan

2017-11-01

Microalgae have a wide area of usage and one of them it can be used for biodiesel production. In biodiesel production, lipids containing triglyceride or free fatty acid are converted into methyl ester through trans/esterification reactions. Lipids from microalgae can be extracted by acetone and dimethyl carbonate using homogenizer. Esterification of the lipids was investigated using various catalysts and source of methyl group. Activity of homogeneous catalyst such as HCl and H2SO4 and heterogeneous catalysts such as montmorillonit K-10 and ledgestone was investigated. Moreover, methanol and dimethyl carbonate as source of methyl group were also studied. Among of catalysts with methanol as source of methyl group, it was found that yield of crude biodiesel derived from Choelestrella Sp. microalgae was high over H2SO4 catalyst. On the other hand, over H2SO4 catalyst using dimethyl carbonate as source of methyl group, yield of crude biodiesel significant increase. However, FAME composition of crude biodiesel was high over HCl catalyst.

Phthalate esters in the environment: A critical review of their occurrence, biodegradation, and removal during wastewater treatment processes.

PubMed

Gao, Da-Wen; Wen, Zhi-Dan

2016-01-15

Phthalate esters are one of the most frequently detected persistent organic pollutants in the environment. A better understanding of their occurrence and degradation in the environment and during wastewater treatment processes will facilitate the development of strategies to reduce these pollutants and to bioremediate contaminated freshwater and soil. Phthalate esters occur at measurable levels in different environments worldwide. For example, the concentrations of dimethyl phthalate (DMP) in atmospheric particulate matter, fresh water and sediments, soil, and landfills are N.D.-10.4 ng/m(3), N.D.-31.7 μg/L, N.D.-316 μg/kg dry weight, and N.D.-200 μg/kg dry weight, N.D.-43.27 μg/L, respectively. Bis(2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DBP) are primary phthalate ester pollutants. Urbanization has increased the discharge of phthalate esters to atmospheric and aquatic environments, and the use of agricultural plastics has exacerbated soil contamination by phthalate esters in rural areas. Aerobic biodegradation is the primary manner of phthalate ester mineralization in the environment, and this process has been widely studied. Phthalate esters can be removed during wastewater treatment processes. The combination of different wastewater treatment technologies showed greater efficiency in the removal of phthalate esters than individual treatment steps, such as the combination of anaerobic wastewater treatment with a membrane bioreactor would increase the efficiency of phthalate ester removal from 65%-71% to 95%-97%. This review provides a useful framework to identify future research objectives to achieve the mineralization and elimination of phthalate esters in the environment. Copyright © 2015 Elsevier B.V. All rights reserved.

Phthalate esters in main source water and drinking water of Zhejiang Province (China): Distribution and health risks.

PubMed

Wang, Xiaofeng; Lou, Xiaoming; Zhang, Nianhua; Ding, Gangqiang; Chen, Zhijian; Xu, Peiwei; Wu, Lizhi; Cai, Jianmin; Han, Jianlong; Qiu, Xueting

2015-10-01

To evaluate the distributions and health risks of phthalate esters in the main source water and corresponding drinking water of Zhejiang Province, the concentrations of 16 phthalate esters in water samples from 19 sites were measured from samples taken in the dry season and wet season. The concentration of the total phthalate ester congeners in source water ranged from 1.07 μg/L to 7.12 μg/L in the wet season, from 0.01 μg/L to 1.58 μg/L in the dry season, from 1.18 μg/L to 15.28 μg/L from drinking water in the wet season, and from 0.16 μg/L to 1.86 μg/L from drinking water in the dry season. Of the 16 phthalate esters, dimethyl phthalate, dibutyl phthalate, di-(2-ethyl-hexyl) phthalate, di-iso-butyl phthalate, bis-2-n-butoxyethyl phthalate, and dicyclohexyl phthalate were present in the samples analyzed, dominated by di-iso-butyl phthalate and di-(2-ethyl-hexyl) phthalate. The concentrations of phthalate esters in the wet season were all relatively higher than those in the dry season, and the drinking water had higher concentrations of phthalate esters than source water. The phthalate ester congeners studied pose little health risk to nearby citizens. Environ Toxicol Chem 2015;34:2205-2212. © 2015 SETAC. © 2015 SETAC.

Synthesis of perfluoroalkylene aromatic diamines

NASA Technical Reports Server (NTRS)

Paciorek, K. L.; Ito, T. I.; Nakahara, J. H.; Kratzer, R. H.

1978-01-01

Analogues of methylene dianilines were synthesized, in which the methylene group between the two aromatic nuclei was replaced by various perfluoroalkylene linkage. The hydrolytic thermal, and thermal oxidative stabilities of PMR Polyimides derived from these diamines were determined. Three types of PMR Polyimide discs were fabricated from the dimethyl ester of 3,3', 4,4'-benzophenonetetracarboxylic acid, the methyl ester of 5-norbornene-2,3-dicarboxylic acid, and one of the following three diamines: methyl dianiline, 1,3-bis(4-aminophenyl)hexafluoropropane, and 2,2-bis(4-aminophenyl)hexafluoropropane. The polyimide based on 2,2-bis(4-aminophenyl)hexafluoropropane exhibited the best hydrolytic, thermal, and thermal oxidative stability as determined by moisture uptake and thermogravimetric analysis.

Concurrent release of admixed antimicrobials and salicylic acid from salicylate-based poly(anhydride-esters)

PubMed Central

Johnson, Michelle L.; Uhrich, Kathryn E.

2008-01-01

A polymer blend consisting of antimicrobials (chlorhexidine, clindamycin, and minocycline) physically admixed at 10% by weight into a salicylic acid-based poly (anhydride-ester) (SA-based PAE) was developed as an adjunct treatment for periodontal disease. The SA-based PAE/antimicrobial blends were characterized by multiple methods, including contact angle measurements and differential scanning calorimetry. Static contact angle measurements showed no significant differences in hydrophobicity between the polymer and antimicrobial matrix surfaces. Notable decreases in the polymer glass transition temperature (Tg) and the antimicrobials' melting points (Tm) were observed indicating that the antimicrobials act as plasticizers within the polymer matrix. In vitro drug release of salicylic acid from the polymer matrix and for each physically admixed antimicrobial was concurrently monitored by high pressure liquid chromatography during the course of polymer degradation and erosion. Although the polymer/antimicrobial blends were immiscible, the initial 24 h of drug release correlated to the erosion profiles. The SA-based PAE/antimicrobial blends are being investigated as an improvement on current localized drug therapies used to treat periodontal disease. PMID:19180627

Stabilization of Resveratrol in Blood Circulation by Conjugation to mPEG and mPEG-PLA Polymers: Investigation of Conjugate Linker and Polymer Composition on Stability, Metabolism, Antioxidant Activity and Pharmacokinetic Profile

PubMed Central

Siddalingappa, Basavaraj; Benson, Heather A. E.; Brown, David H.; Batty, Kevin T.; Chen, Yan

2015-01-01

Resveratrol is naturally occurring phytochemical with diverse biological activities such as chemoprevention, anti-inflammatory, anti-cancer, anti-oxidant. But undergoes rapid metabolism in the body (half life 0.13h). Hence Polymer conjugation utilizing different chemical linkers and polymer compositions was investigated for enhanced pharmacokinetic profile of resveratrol. Ester conjugates such as α-methoxy-ω-carboxylic acid poly(ethylene glycol) succinylamide resveratrol (MeO-PEGN-Succ-RSV) (2 and 20 kDa); MeO-PEG succinyl ester resveratrol (MeO-PEGO-Succ-RSV) (2 kDa); α-methoxy poly(ethylene glycol)-co-polylactide succinyl ester resveratrol (MeO-PEG-PLAO-Succ-RSV) (2 and 6.6kDa) were prepared by carbodiimide coupling reactions. Resveratrol-PEG ethers (2 and 5 kDa) were synthesized by alkali-mediated etherification. All polymer conjugates were fully characterized in vitro and the pharmacokinetic profile of selected conjugates was characterized in rats. Buffer and plasma stability of conjugates was dependent on polymer hydrophobicity, aggregation behavior and PEG corona, with MeO-PEG-PLAO-Succ-RSV (2 kDa) showing a 3h half-life in rat plasma in vitro. Polymer conjugates irrespective of linker chemistry protected resveratrol against metabolism in vitro. MeO-PEG-PLAO-Succ-RSV (2 kDa), Resveratrol-PEG ether (2 and 5 kDa) displayed improved pharmacokinetic profiles with significantly higher plasma area under curve (AUC), slower clearance and smaller volume of distribution, compared to resveratrol. PMID:25799413

Fabrication of mesoporous polymer monolith: a template-free approach.

PubMed

Okada, Keisuke; Nandi, Mahasweta; Maruyama, Jun; Oka, Tatsuya; Tsujimoto, Takashi; Kondoh, Katsuyoshi; Uyama, Hiroshi

2011-07-14

Mesoporous polyacrylonitrile (PAN) monolith has been fabricated by a template-free approach using the unique affinity of PAN towards a water/dimethyl sulfoxide (DMSO) mixture. A newly developed Thermally Induced Phase Separation Technique (TIPS) has been used to obtain the polymer monoliths and their microstructures have been controlled by optimizing the concentration and cooling temperature.

75 FR 4288 - Oxirane, 2-Methyl-, Polymer with Oxirane, Dimethyl Ether; Tolerance Exemption

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-27

... a finite tolerance is not necessary to ensure that there is a reasonable certainty that no harm will... composition the atomic elements carbon, hydrogen, and oxygen. 3. The polymer does not contain as an integral part of its composition, except as impurities, any element other than those listed in 40 CFR 723.250(d...

40 CFR 721.10020 - Benzoic acid, 5-amino-2-chloro-, 1,1-dimethyl-2-oxo-2-(2-propenyloxy) ethyl ester.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Benzoic acid, 5-amino-2-chloro-, 1,1... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10020 Benzoic acid, 5-amino-2-chloro... subject to reporting. (1) The chemical substance identified as benzoic acid, 5-amino-2-chloro-, 1,1...

40 CFR 721.10020 - Benzoic acid, 5-amino-2-chloro-, 1,1-dimethyl-2-oxo-2-(2-propenyloxy) ethyl ester.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzoic acid, 5-amino-2-chloro-, 1,1... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10020 Benzoic acid, 5-amino-2-chloro... subject to reporting. (1) The chemical substance identified as benzoic acid, 5-amino-2-chloro-, 1,1...

Development of controlled release formulations of azadirachtin-A employing poly(ethylene glycol) based amphiphilic copolymers.

PubMed

Kumar, Jitendra; Shakil, Najam A; Singh, Manish K; Singh, Mukesh K; Pandey, Alka; Pandey, Ravi P

2010-05-01

Controlled release (CR) formulations of azadirachtin-A, a bioactive constituent derived from the seed of Azadirachta indica A. Juss (Meliaceae), have been prepared using commercially available polyvinyl chloride, polyethylene glycol (PEG) and laboratory synthesized poly ethylene glycol-based amphiphilic copolymers. Copolymers of polyethylene glycol and various dimethyl esters, which self assemble into nano micellar aggregates in aqueous media, have been synthesized. The kinetics of azadirachtin-A, release in water from the different formulations was studied. Release from the commercial polyethylene glycol (PEG) formulation was faster than the other CR formulations. The rate of release of encapsulated azadirachtin-A from nano micellar aggregates is reduced by increasing the molecular weight of PEG. The diffusion exponent (n value) of azadirachtin-A, in water ranged from 0.47 to 1.18 in the tested formulations. The release was diffusion controlled with a half release time (t(1/2)) of 3.05 to 42.80 days in water from different matrices. The results suggest that depending upon the polymer matrix used, the application rate of azadirachtin-A can be optimized to achieve insect control at the desired level and period.

Impact of lignin polymer backbone esters on ionic liquid pretreatment of poplar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Kwang Ho; Dutta, Tanmoy; Ralph, John

Biomass pretreatment remains an essential step in lignocellulosic biofuel production, largely to facilitate the efficient removal of lignin and increase enzyme accessibility to the polysaccharides. In recent years, there have been significant efforts in planta to reduce lignin content or modify its composition to overcome the inherent recalcitrance that it imposes on lignocellulosic biomass during processing. Here, transgenic poplar lines in which monolignol ferulate conjugates were synthesized during cell wall development to introduce, during lignification, readily cleavable ester linkages into the lignin polymer backbone (i.e., "zip lignin"), along with wild-type (WT) controls, were pretreated with different ionic liquids (ILs). Themore » strategic introduction of ester bonds into the lignin backbone resulted in increased pretreatment efficiency and released more carbohydrates with lower energy input. After pretreatment with any of three different ILs, and after limited saccharification, the transgenic poplars, especially those with relatively higher amounts of incorporated monolignol ferulate conjugates, yielded up to 23% higher sugar levels compared to WT plants. Our findings clearly demonstrate that the introduction of ester linkages into the lignin polymer backbone decreases biomass recalcitrance in poplar has the potential to reduce the energy and/or amount of IL required for effective pretreatment, and could enable the development of an economically viable and sustainable biorefinery process.« less

Impact of lignin polymer backbone esters on ionic liquid pretreatment of poplar

DOE PAGES

Kim, Kwang Ho; Dutta, Tanmoy; Ralph, John; ...

2017-04-20

Biomass pretreatment remains an essential step in lignocellulosic biofuel production, largely to facilitate the efficient removal of lignin and increase enzyme accessibility to the polysaccharides. In recent years, there have been significant efforts in planta to reduce lignin content or modify its composition to overcome the inherent recalcitrance that it imposes on lignocellulosic biomass during processing. Here, transgenic poplar lines in which monolignol ferulate conjugates were synthesized during cell wall development to introduce, during lignification, readily cleavable ester linkages into the lignin polymer backbone (i.e., "zip lignin"), along with wild-type (WT) controls, were pretreated with different ionic liquids (ILs). Themore » strategic introduction of ester bonds into the lignin backbone resulted in increased pretreatment efficiency and released more carbohydrates with lower energy input. After pretreatment with any of three different ILs, and after limited saccharification, the transgenic poplars, especially those with relatively higher amounts of incorporated monolignol ferulate conjugates, yielded up to 23% higher sugar levels compared to WT plants. Our findings clearly demonstrate that the introduction of ester linkages into the lignin polymer backbone decreases biomass recalcitrance in poplar has the potential to reduce the energy and/or amount of IL required for effective pretreatment, and could enable the development of an economically viable and sustainable biorefinery process.« less

A highly conductive poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) film with the solvent bath treatment by dimethyl sulfoxide as cathode for polymer tantalum capacitor

NASA Astrophysics Data System (ADS)

Ma, Xiaopin; Wang, Xiuyu; Li, Mingxiu; Chen, Tongning; Zhang, Hao; Chen, Qiang; Ding, Bonan; Liu, Yanpeng

2016-06-01

The highly conductive poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films were prepared on porous tantalum pentoxide surface as cathode for polymer tantalum capacitors (PTC). The electrical performances of PTC with PEDOT:PSS films as cathode were optimized by dimethyl sulfoxide (DMSO) bath treatment. With the DMSO-bath treatment of PTC, the equivalent series resistance (ESR) of PTC decreased from 25 mΩ to 9 mΩ. The ultralow ESR led to better capacitance-frequency performance. The device reliability investigation revealed the enhanced environmental stability of PTC. The enhanced performances were attributed to the conductivity improvement of PEDOT:PSS cathode films and the removal of excess PSS from PEDOT:PSS films.

Evaluation of bisphenol E cyanate ester for the resin-injection repair of advanced composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lio, Wilber Yaote

2009-12-01

This thesis is a compilation of a general introduction and literature review that ties together the subsequent chapters which consist of two journal articles that have yet to be submitted for publication. The overall topic relates to the evaluation and application of a new class of cyanate ester resin with unique properties that lend it applicable to use as a resin for injection repair of high glass transition temperature polymer matrix composites. The first article (Chapter 2) details the evaluation and optimization of adhesive properties of this cyanate ester and alumina nanocomposites under different conditions. The second article (Chapter 3)more » describes the development and evaluation of an injection repair system for repairing delaminations in polymer matrix composites.« less

Soluble, High Molecular Weight Polysilsesquioxanes with Carboxylate Functionalities

DOE Office of Scientific and Technical Information (OSTI.GOV)

RAHIMIAN,KAMYAR; LOY,DOUGLAS A.; WHEELER,DAVID R.

2000-07-14

Trialkoxysilyl-containing monomers of the type (RO){sub 3}Si(CH{sub 2}){sub 3}C(O)OtBu (R = Me, Et) were prepared by hydrosilation of the corresponding vinylic tert-butyl esters CH{sub 3}CHCH{sub 2}C(O)OtBu. Acid- or base-catalyzed polymerization of the monomers leads to very high molecular weight polymers with relatively narrow polydispersities. The polymerization results in complete condensation of the alkoxy groups while the tert-butyl ester functionality remains fully intact. Partial or full deprotection of the tert-butyl group can easily be achieved to yield the corresponding carboxylic acid polymers. The ester and carboxylic acid functionalities of these new materials allow for their potential use in a variety ofmore » applications such as scavenging of heavy metals.« less

Amino acid-functionalized multi-walled carbon nanotubes for improving compatibility with chiral poly(amide-ester-imide) containing L-phenylalanine and L-tyrosine linkages

NASA Astrophysics Data System (ADS)

Abdolmaleki, Amir; Mallakpour, Shadpour; Borandeh, Sedigheh

2013-12-01

Amino acid functionalized multi-walled carbon nanotubes (f-MWCNTs)/poly(amide-ester-imide) (PAEI) composites were fabricated by solution mixing method. Proper functionalization and mixing strategy of MWCNTs provides the best opportunity for better distribution and bonding of nanoparticles to the polymer matrix. MWCNTs have been chemically modified with L-phenylalanine to improve their compatibility with L-phenylalanine based PAEI. Field emission scanning electron microscopy micrographs of composite revealed that f-MWCNTs made a good interaction with polymer chains by wrapping the polymer around them, and transmission electron microscopy results confirmed well dispersion with nano size of f-MWCNTs in the polymer matrix. In addition, thermal analysis showed good enhancement in thermal properties of composites compared to pure polymer. Thermal stability of the composites containing f-MWCNTs was enhanced due to their good dispersion and improved interfacial interaction between the amino acid based PAEI matrix and f-MWCNTs.

Refractive Index Determination of Transparent Polymers: Experimental Setup for Multi-Wavelength Determination and Calculation at Specific Frequencies Using Group Contribution Theory

ERIC Educational Resources Information Center

Dlutowski, Jay; Cardenas-Valencia, Andres M.; Fries, David; Langebrake, Larry

2006-01-01

An experiment which enables students to determine the index of refraction at various wavelengths is demonstrated by using two polymers examples, poly(dimethyl siloxane) (PDMS) and poly(methyl methacrylate) (PMMA). This experiment would be suitable for a course in organic chemistry or any course discussing the optical properties of polymeric…

Synthesis, Properties and Applications of Biodegradable Polymers Derived from Diols and Dicarboxylic Acids: From Polyesters to Poly(ester amide)s

PubMed Central

Díaz, Angélica; Katsarava, Ramaz; Puiggalí, Jordi

2014-01-01

Poly(alkylene dicarboxylate)s constitute a family of biodegradable polymers with increasing interest for both commodity and speciality applications. Most of these polymers can be prepared from biobased diols and dicarboxylic acids such as 1,4-butanediol, succinic acid and carbohydrates. This review provides a current status report concerning synthesis, biodegradation and applications of a series of polymers that cover a wide range of properties, namely, materials from elastomeric to rigid characteristics that are suitable for applications such as hydrogels, soft tissue engineering, drug delivery systems and liquid crystals. Finally, the incorporation of aromatic units and α-amino acids is considered since stiffness of molecular chains and intermolecular interactions can be drastically changed. In fact, poly(ester amide)s derived from naturally occurring amino acids offer great possibilities as biodegradable materials for biomedical applications which are also extensively discussed. PMID:24776758

Dicarboxylic esters: Useful tools for the biocatalyzed synthesis of hybrid compounds and polymers

PubMed Central

Bassanini, Ivan; Hult, Karl

2015-01-01

Summary Dicarboxylic acids and their derivatives (esters and anhydrides) have been used as acylating agents in lipase-catalyzed reactions in organic solvents. The synthetic outcomes have been dimeric or hybrid derivatives of bioactive natural compounds as well as functionalized polyesters. PMID:26664578

40 CFR 721.10185 - 1,2-Propanediol, 3-(diethylamino)-, polymers with 5-isocyanato-1- (isocyanatomethyl)-1,3,3...

Code of Federal Regulations, 2011 CFR

2011-07-01

...)-, polymers with 5-isocyanato-1- (isocyanatomethyl)-1,3,3-trimethylcyclohexane, propylene glycol and reduced...- (isocyanatomethyl)-1,3,3-trimethylcyclohexane, propylene glycol and reduced Me esters of reduced polymd. oxidized...)-, polymers with 5-isocyanato-1- (isocyanatomethyl)-1,3,3-trimethylcyclohexane, propylene glycol and reduced...

40 CFR 721.10185 - 1,2-Propanediol, 3-(diethylamino)-, polymers with 5-isocyanato-1- (isocyanatomethyl)-1,3,3...

Code of Federal Regulations, 2012 CFR

2012-07-01

...)-, polymers with 5-isocyanato-1- (isocyanatomethyl)-1,3,3-trimethylcyclohexane, propylene glycol and reduced...- (isocyanatomethyl)-1,3,3-trimethylcyclohexane, propylene glycol and reduced Me esters of reduced polymd. oxidized...)-, polymers with 5-isocyanato-1- (isocyanatomethyl)-1,3,3-trimethylcyclohexane, propylene glycol and reduced...

40 CFR 721.10185 - 1,2-Propanediol, 3-(diethylamino)-, polymers with 5-isocyanato-1- (isocyanatomethyl)-1,3,3...

Code of Federal Regulations, 2014 CFR

2014-07-01

...)-, polymers with 5-isocyanato-1- (isocyanatomethyl)-1,3,3-trimethylcyclohexane, propylene glycol and reduced...- (isocyanatomethyl)-1,3,3-trimethylcyclohexane, propylene glycol and reduced Me esters of reduced polymd. oxidized...)-, polymers with 5-isocyanato-1- (isocyanatomethyl)-1,3,3-trimethylcyclohexane, propylene glycol and reduced...

40 CFR 721.10185 - 1,2-Propanediol, 3-(diethylamino)-, polymers with 5-isocyanato-1- (isocyanatomethyl)-1,3,3...

Code of Federal Regulations, 2013 CFR

2013-07-01

...)-, polymers with 5-isocyanato-1- (isocyanatomethyl)-1,3,3-trimethylcyclohexane, propylene glycol and reduced...- (isocyanatomethyl)-1,3,3-trimethylcyclohexane, propylene glycol and reduced Me esters of reduced polymd. oxidized...)-, polymers with 5-isocyanato-1- (isocyanatomethyl)-1,3,3-trimethylcyclohexane, propylene glycol and reduced...

21 CFR 175.320 - Resinous and polymeric coatings for polyolefin films.

Code of Federal Regulations, 2014 CFR

2014-04-01

... film over one or both sides of a base film produced from one or more of the basic olefin polymers complying with § 177.1520 of this chapter. The base polyolefin film may contain optional adjuvant substances... Limitations (i) Resins and polymers: Acrylic acid polymer and its ethyl or methyl esters Acrylamide...

21 CFR 177.2440 - Polyethersulfone resins.

Code of Federal Regulations, 2014 CFR

2014-04-01

... determined by reduced viscosity in dimethyl formamide in accordance with ASTM method D2857-70 (Reapproved 1977), “Standard Test Method for Dilute Solution Viscosity of Polymers,” which is incorporated by...

Differential polymer structure tunes mechanism of cellular uptake and transfection routes of poly(β-amino ester) polyplexes in human breast cancer cells.

PubMed

Kim, Jayoung; Sunshine, Joel C; Green, Jordan J

2014-01-15

Successful gene delivery with nonviral particles has several barriers, including cellular uptake, endosomal escape, and nuclear transport. Understanding the mechanisms behind these steps is critical to enhancing the effectiveness of gene delivery. Polyplexes formed with poly(β-amino ester)s (PBAEs) have been shown to effectively transfer DNA to various cell types, but the mechanism of their cellular uptake has not been identified. This is the first study to evaluate the uptake mechanism of PBAE polyplexes and the dependence of cellular uptake on the end group and molecular weight of the polymer. We synthesized three different analogues of PBAEs with the same base polymer poly(1,4-butanediol diacrylate-co-4-amino-1-butanol) (B4S4) but with small changes in the end group or molecular weight. We quantified the uptake and transfection efficiencies of the pDNA polyplexes formulated from these polymers in hard-to-transfect triple negative human breast cancer cells (MDA-MB 231). All polymers formed positively charged (10-17 mV) nanoparticles of ∼200 nm in size. Cellular internalization of all three formulations was inhibited the most (60-90% decrease in cellular uptake) by blocking caveolae-mediated endocytosis. Greater inhibition was shown with polymers that had a 1-(3-aminopropyl)-4-methylpiperazine end group (E7) than the others with a 2-(3-aminopropylamino)-ethanol end group (E6) or higher molecular weight. However, caveolae-mediated endocytosis was generally not as efficient as clathrin-mediated endocytosis in leading to transfection. These findings indicate that PBAE polyplexes can be used to transfect triple negative human breast cancer cells and that small changes to the same base polymer can modulate their cellular uptake and transfection routes.

Protection of 2-(3-Thienyl)ethanol with 3-Thienylacetic Acid and Hard Cross- Linked Conducting Films by Electropolymerization of the Ester

NASA Technical Reports Server (NTRS)

Leventis, Nicholas; Dass, Amala; Mulik, Sudir; Sotiriou-Leventis, Chariklia

2005-01-01

The ester (compound 1) of 2-(3-thienyl)ethanol (T-etOH) with 3-thienylacetic acid was synthesized as a monomer whose two thiophene groups could be electropolymerized independently, becoming members of different polymer chains in a highly-crosslinked highly-insoluble polymer. Indeed, 1 was electropolymerized successfully alone and together with 3-methylthiophene (3MeT). Films of poly(1) are hard (3H, as opposed to less than 6B for poly(3MeT)), and the close proximity of the polymeric strands creates pi-stacking interactions. The behavior of 1 suggests that by: (a) limiting the potential used for the oxidation of monomeric esters of T-etOH at the foot of their oxidation waves (less than 1.8 V vs. Ag/AgCl); and, (b) compensating for the decrease in the electrogenerated radical concentration by increasing the monomer concentration, practically all esters of T-etOH should be electropolymerizable. This was confirmed by durable film formation from the archetypical ester of T-etOH, the 2-(3-thienyl)ethyl acetate (T-etOAc), whose homo-electropolymerization is reported for the first time.

3- and 4-pyridylalkyl adamantanecarboxylates: inhibitors of human cytochrome P450(17 alpha) (17 alpha-hydroxylase/C17,20-lyase). Potential nonsteroidal agents for the treatment of prostatic cancer.

PubMed

Chan, F C; Potter, G A; Barrie, S E; Haynes, B P; Rowlands, M G; Houghton, J; Jarman, M

1996-08-16

Various 3- and 4-pyridylalkyl 1-adamantanecarboxylates have been synthesized and tested for inhibitory activity toward the 17 alpha-hydroxylase and C17,20-lyase activities of human testicular cytochrome P450(17 alpha). The 4-pyridylalkyl esters were much more inhibitory than their 3-pyridylalkyl counterparts. The most potent was (S)-1-(4-pyridyl)ethyl 1-adamantanecarboxylate (3b; IC50 for lyase, 1.8 nM), whereas the (R)-enantiomer 3a was much less inhibitory (IC50 74 nM). Nearly as potent as 3b was the dimethylated counterpart, the 2-(4-pyridylpropan-2-yl) ester 5 (IC50 2.7 nM), which was also more resistant to degradation by esterases. In contrast to their 4-pyridyl analogs, the enantiomers of the 1-(3-pyridyl)ethyl ester were similarly inhibitory (IC50 for lyase; (R)-isomer 8a 150 nM, (S)-isomer 8b 230 nM). Amides corresponding to the 4-pyridylmethyl ester 1 and the (S)-1-(4-pyridyl)ethyl ester 3b, respectively 11 and 15b, were much less inhibitory than their ester counterparts. On the basis of a combination of inhibitory potency and resistance to esterases, the ester 5 was the best candidate for further development as a potential nonsteroidal inhibitor of cytochrome P450(17 alpha) for the treatment of prostate cancer.

21 CFR 177.2440 - Polyethersulfone resins.

Code of Federal Regulations, 2013 CFR

2013-04-01

... molecular weight is determined by reduced viscosity in dimethyl formamide in accordance with ASTM method D2857-70 (Reapproved 1977), “Standard Test Method for Dilute Solution Viscosity of Polymers,” which is...

21 CFR 177.2440 - Polyethersulfone resins.

Code of Federal Regulations, 2012 CFR

2012-04-01

... molecular weight is determined by reduced viscosity in dimethyl formamide in accordance with ASTM method D2857-70 (Reapproved 1977), “Standard Test Method for Dilute Solution Viscosity of Polymers,” which is...

21 CFR 177.2440 - Polyethersulfone resins.

Code of Federal Regulations, 2011 CFR

2011-04-01

... molecular weight is determined by reduced viscosity in dimethyl formamide in accordance with ASTM method D2857-70 (Reapproved 1977), “Standard Test Method for Dilute Solution Viscosity of Polymers,” which is...

Studies of Plasticized-Polymer Electrolytes Containing Mixed Zn(II) and Li(I)

DTIC Science & Technology

1992-06-12

iIIIII1iIIII!I 14. SUBJECT TERMS 15. tdUMnnrri . 9 poly(ethylene glycol) ( PEG ), poly(ethylene glycol dimethyl ether) (PEGDME), 16. PRICE CODE...glycol) ( PEG ) and poly(ethylene glycol dimethyl ether) (PEGDME). The addition of salts to either PEO or plasticized-PEO strongly influences the...were found to depend on salt concentration. Td varied from 385 to 3350 C as the zinc content was increased from 0 to 100%. Thus the overall thermal

Shoe contact dermatitis from dimethyl fumarate: clinical manifestations, patch test results, chemical analysis, and source of exposure.

PubMed

Giménez-Arnau, Ana; Silvestre, Juan Francisco; Mercader, Pedro; De la Cuadra, Jesus; Ballester, Isabel; Gallardo, Fernando; Pujol, Ramón M; Zimerson, Erik; Bruze, Magnus

2009-11-01

The methyl ester form of fumaric acid named dimethyl fumarate (DMF) is an effective mould-growth inhibitor. Its irritating and sensitizing properties were demonstrated in animal models. Recently, DMF has been identified as responsible for furniture contact dermatitis in Europe. To describe the clinical manifestations, patch test results, shoe chemical analysis, and source of exposure to DMF-induced shoe contact dermatitis. Patients with suspected shoe contact dermatitis were studied in compliance with the Declaration of Helsinki. Patch test results obtained with their own shoe and the European baseline series, acrylates and fumaric acid esters (FAE), were recorded according to international guidelines. The content of DMF in shoes was analysed with gas chromatography and mass spectrometry. Acute, immediate irritant contact dermatitis and non-immunological contact urticaria were observed in eight adults and two children, respectively. All the adult patients studied developed a delayed sensitization demonstrated by a positive patch testing to DMF < or = 0.1% in pet. Cross-reactivity with other FAEs and acrylates was observed. At least 12 different shoe brands were investigated. The chemical analysis from the available shoes showed the presence of DMF. DMF in shoes was responsible for severe contact dermatitis. Global preventive measures for avoiding contact with DMF are necessary.

A High T(sub g) PMR Polyimide Composites (DMBZ-15)

NASA Technical Reports Server (NTRS)

Chuang, Kathy C.; Bowles, Kenneth J.; Papadopoulos, Demitrios S.; Hardy-Green, DeNise; Mccorkle, Linda

2000-01-01

A high T(sub g) thermosetting PMR-type polyimide, designated as DMBZ-15, was developed by replacing methylene dianline (MDA) in PMR-15 with 2,2'-dimethylbenzidine. Polyimide/carbon fiber (T650-35) composites were fabricated from a formulation of 3,3', 4,4'-benzophenonetetracarboxylic acid dimethyl ester (BTDE) and 2,2'-dimethylbenzidine (DMBZ), along with nadic ester (NE) as the endcap. DMBZ-15 displays a higher glass transition temperature (T(sub g) = 414 C) than PMR-15 (T(sub g) = 345 C), and thus retains better mechanical properties for brief exposure above 400 C. The physical properties and longterm thermo-oxidative stability of the DMBZ-15 polyimide/carbon fiber composites are also compared to that of PMR-15.

In vitro assessment of phthalate acid esters-trypsin complex formation.

PubMed

Chi, Zhenxing; Zhao, Jing; Li, Weiguo; Araghi, Arash; Tan, Songwen

2017-10-01

In this work, interactions of three phthalate acid esters (PAEs), including dimethyl phthalate (DMP), diethyl phthalate (DEP) and dibutyl phthalate (DBP), with trypsin have been studied in vitro, under simulated physiological conditions using multi-spectroscopic techniques and molecular modeling. The results show that these PAEs can bind to the trypsin, forming trypsin-PAEs complexes, mainly via hydrophobic interactions, with the affinity order of DMP > DEP > DBP. Binding to the PAEs is found to result in molecular deformation of trypsin. The modeling results suggest that only DBP can bind with the amino acid residues of the catalytic triad and S1 binding pocket of trypsin, leading to potential competitive enzyme inhibition. Copyright © 2017 Elsevier Ltd. All rights reserved.

SEPARATION OF T-MAZ ETHOXYLATED SORBITAN FATTY ACID ESTERS BY REVERSE PHASE CHROMATOGRAPHY

EPA Science Inventory

The method for determination of T-MAZ ethoxylated sorbitan fatty acid esters is described. This work demonstrates that with a less retentive C8 alkyl bonded phase packing, reverse phase chromatography can be used to analyze nonionic polymer mixtures with a molecular weight range ...

Formation of furan fatty alkyl esters from their bis-epoxide fatty esters

USDA-ARS?s Scientific Manuscript database

Epoxidation of vegetable oils and consecutive epoxide ring-opening reaction is a widely investigated path for producing biobased lubricants and polymers. The reaction mechanism and products are considered well-studied and known. In the current study, the reactions of epoxidized alkyl soyate with fou...

Low-temperature phase behavior of fatty acid methyl esters by differential scanning calorimetry (DSC)

USDA-ARS?s Scientific Manuscript database

Fatty acid methyl ester (FAME) mixtures have many uses including biodiesel, lubricants, metal-working fluids, surfactants, polymers, coatings, green solvents and phase-change materials. The physical properties of a FAME mixture depends on the fatty acid concentration (FAC) profile. Some products hav...

Lipase-catalyzed simultaneous biosynthesis of biodiesel and glycerol carbonate from corn oil in dimethyl carbonate.

PubMed

Min, Ji Young; Lee, Eun Yeol

2011-09-01

Biodiesel [fatty acid methyl esters (FAMEs)] and glycerol carbonate were synthesized from corn oil and dimethyl carbonate (DMC) via transesterification using lipase (Novozyme 435) in solvent-free reaction in which excess DMC was used as the substrate and reaction medium. Glycerol carbonate was also simultaneously formed from DMC and glycerol. Conversions of FAMEs and glycerol carbonate were examined in batch reactions. The FAMEs and glycerol carbonate reached 94 and 62.5% from oil and DMC (molar ratio of 1:10) with 0.2% (v/v) water and 10% (w/w) Novozyme 435 (based on oil weight) at 60 °C. When Novozyme 435 was washed with acetone after each reaction, more than 80% activity still remained after seven recycling. © Springer Science+Business Media B.V. 2011

Iron-based magnetic molecular imprinted polymers and their application in removal and determination of di-n-pentyl phthalate in aqueous media

PubMed Central

Zhou, Qingxiang; Yuan, Yongyong; Wu, Yalin

2017-01-01

Iron-based magnetic molecular imprinted polymers (Fe@SiO2@MIP) were synthesized for highly selective removal and recognition of di-n-pentyl phthalate (DnPP) from water. Well-defined core-shell Fe@SiO2 nanoparticles (less than 70 nm) were decorated on MIPs reticular layers to endow DnPP-MIPs with magnetic property for the first time. Five other phthalic acid esters including dimethyl phthalate, diethyl phthalate, dipropyl phthalate, di-n-butyl phthalate and di-iso-octyl phthalate were used to investigate the adsorptive selectivity to DnPP. The designed experiments were carried out to explore the adsorption kinetics, isotherms and thermodynamics and the results demonstrated that the adsorption was a spontaneous, exothermal and physical adsorption process. The materials were proved to be excellent adsorbents in removal of DnPP with an adsorption capacity as high as 194.15 mg g−1 in optimal condition. Furthermore, a magnetic solid phase extraction with Fe@SiO2@MIP coupled to high-performance liquid chromatography method was successfully developed for the determination of DnPP, and the proposed method achieved a good linear range of 0.5–250 µg l−1 with a correlation coefficient (R2) of 0.999 and low limit of detection (LOD) of 0.31 µg l−1. These materials exhibited excellent capacity in removal and highly sensitive identification of DnPP from aqueous environment samples, and opened a valuable direction for developing new adsorbents for the removal and enrichment of important pollutants. PMID:28879009

Iron-based magnetic molecular imprinted polymers and their application in removal and determination of di-n-pentyl phthalate in aqueous media.

PubMed

Li, Jing; Zhou, Qingxiang; Yuan, Yongyong; Wu, Yalin

2017-08-01

Iron-based magnetic molecular imprinted polymers (Fe@SiO 2 @MIP) were synthesized for highly selective removal and recognition of di- n -pentyl phthalate (DnPP) from water. Well-defined core-shell Fe@SiO 2 nanoparticles (less than 70 nm) were decorated on MIPs reticular layers to endow DnPP-MIPs with magnetic property for the first time. Five other phthalic acid esters including dimethyl phthalate, diethyl phthalate, dipropyl phthalate, di- n -butyl phthalate and di-iso-octyl phthalate were used to investigate the adsorptive selectivity to DnPP. The designed experiments were carried out to explore the adsorption kinetics, isotherms and thermodynamics and the results demonstrated that the adsorption was a spontaneous, exothermal and physical adsorption process. The materials were proved to be excellent adsorbents in removal of DnPP with an adsorption capacity as high as 194.15 mg g -1 in optimal condition. Furthermore, a magnetic solid phase extraction with Fe@SiO 2 @MIP coupled to high-performance liquid chromatography method was successfully developed for the determination of DnPP, and the proposed method achieved a good linear range of 0.5-250 µg l -1 with a correlation coefficient ( R 2 ) of 0.999 and low limit of detection (LOD) of 0.31 µg l -1 . These materials exhibited excellent capacity in removal and highly sensitive identification of DnPP from aqueous environment samples, and opened a valuable direction for developing new adsorbents for the removal and enrichment of important pollutants.

Synthesis of ethylene maleic anhydride copolymer containing fungicides and evaluation of their effect for wood decay resistance

Treesearch

George C. Chen

2008-01-01

The aim of the present study was to combat wood decay based on the approach controlled-release biocides from polymers. The possibility of introducing polymer-bonded fungicides into the cell lumens was investigated. The synthesis of ethylene maleic anhydride copolymer containing pentachlorophenol (penta) and 8-hydroxy quinoline (8HQ) in N, N dimethyl formamide is...

Silicon-Containing Tri- and Tetra-Functional Cyanate Esters: Synthesis, Cure Kinetics, and Network Properties

DTIC Science & Technology

2014-01-01

24. Pollack, S. K.; Fu, Z. Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem.) 1998, 39, 452-453. 25. Devaraju, S.; Vengatesan, M. R.; Selvi , M...Ganguli, S.; Dean, D.; Jordan, K.; Price, G.; Vaia, R. Polymer 2003, 44, 1315-1319. 54. Devaraju, S.; Vengatesan, M. R.; Selvi , M.; Kumar, A. A

Formation of 4-Hydroxy-2,5-Dimethyl-3[2H]-Furanone by Zygosaccharomyces rouxii: Identification of an Intermediate

PubMed Central

Hauck, Tobias; Brühlmann, Fredi; Schwab, Wilfried

2003-01-01

The formation of the important flavor compound 4-hydroxy-2,5-dimethyl-3[2H]-furanone (HDMF; Furaneol) from d-fructose-1,6-bisphosphate by the yeast Zygosaccharomyces rouxii was studied with regard to the identification of intermediates present in the culture medium. Addition of o-phenylenediamine, a trapping reagent for α-dicarbonyls, to the culture medium and subsequent analysis by high-pressure liquid chromatography with diode array detection revealed the formation of three quinoxaline derivatives derived from d-fructose-1,6-bisphosphate under the applied growth conditions (30°C; pH 4 to 5). Isolation and characterization of these compounds by tandem mass spectrometry and nuclear magnetic resonance spectroscopy led to the identification of phosphoric acid mono-(2,3,4-trihydroxy-4-quinoxaline-2-yl-butyl) ester (Q1), phosphoric acid mono-[2,3-dihydroxy-3-(3-methyl-quinoxaline-2-yl)-propyl] ester (Q2), and phosphoric acid mono-[2-hydroxy-3-(3-methyl-quinoxaline-2-yl)-propyl] ester (Q3). Q1 and Q2 were formed independently of Z. rouxii cells, whereas Q3 was detected only in incubation systems containing the yeast. Identification of Q2 demonstrated for the first time the chemical formation of 1-deoxy-2,3-hexodiulose-6-phosphate in the culture medium, a generally expected but never identified intermediate in the formation pathway of HDMF. Since HDMF was detected only in the presence of Z. rouxii cells, additional enzymatic steps were presumed. Incubation of periplasmic and cytosolic protein extracts obtained from yeast cells with d-fructose-1,6-bisphosphate led to the formation of HDMF, implying the presence of the required enzymes in both extracts. PMID:12839760

Response surface method (RSM) for optimization of ionic conductivity of membranes polymer electrolyte poly (vinylidene fluoride) (PVDF) with polyvinyl pyrrolidone (PVP) as pore forming agent

NASA Astrophysics Data System (ADS)

Dyartanti, E. R.; Susanto, H.; Widiasa, I. N.; Purwanto, A.

2017-06-01

The Membranes Polymer Gel Electrolyte (MPGEs) based poly (vinylidene fluoride) (PVDF) was prepared by a phase inversion method using polyvinyl pyrrolidone (PVP) as a pore-forming agent and N, N-dimethyl acetamide (DMAc) as a solvent and water as non solvet. The membranes were then soaked in 1 M lithium hexafluorophosphate (LiPF6) in ethylene carbonate (EC) / dimethyl carbonate (DMC) / Diethyl carbonate (DEC) (4:2:4 %vol) solution in order to prepare polymer electrolyte membranes. The MPEGs PVDF/PVP/Nanoclay was applied using central composite design (CCD) experimental design to obtain a quantitative relationship between selected membranes prepared parameters namely (PVDF, PVP as pore forming agent and nanoclay filler concentration) and Ionic conductivity MPEGs. The model was used to find the optimum ionic conductivity from polymer electrolyte membranes. The polymer electrolyte membranes show good ionic conductivity on the order of 6.3 - 8.7 x 10-3 S cm-1 at the ambient temperatures. The ionic conductivity tended to increase with PVP and nanoclay concentration and decrease with PVDF composition. The model predicted the maximum ionic conductivity of 8.47 x 10-3 S cm-1 when the PVDF, PVP and nanoclay concentration were set at 8.01 %, 8.04 % and 10.12%, respectively. The first section in your paper.

Update on the Us Army’s Fuel Contamination Detection Efforts

DTIC Science & Technology

2011-04-04

Dual Eng flameout Contaminated with water and particulate 14 2009 C-130 USAF Jet Fuel Contamination with Fatty Acid Methyl Ester ( FAME ) BioFuel 15 20...DRNEN. WARRGHTER FOCUSED. Summary of Incidents • US Air Force – 2 - T-37 Super Absorbent Polymer 1 C 130 FAME Fatty Methyl Ester

Thermally crosslinked polymeric compositions and methods of making the same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koros, William John; Kratochvil, Adam Michal

2014-03-04

The various embodiments of the present disclosure relate generally to thermally crosslinked polymeric compositions and methods of making thermally crosslinked polymeric compositions. An embodiment of the present invention comprises a composition comprising: a first polymer comprising a first repeat unit, the first repeat unit comprising a carboxyl group, wherein the first polymer crosslinks to a second polymer formed from a second repeat unit, and wherein the first polymer crosslinks to the second polymer without formation of an ester group.

End-functionalized ROMP polymers for Biomedical Applications

PubMed Central

Madkour, Ahmad E.; Koch, Amelie H. R.; Lienkamp, Karen; Tew, Gregory N.

2010-01-01

We present two novel allyl-based terminating agents that can be used to end-functionalize living polymer chains obtained by ring-opening metathesis polymerization (ROMP) using Grubbs’ third generation catalyst. Both terminating agents can be easily synthesized and yield ROMP polymers with stable, storable activated ester groups at the chain-end. These end-functionalized ROMP polymers are attractive building blocks for advanced polymeric materials, especially in the biomedical field. Dye-labeling and surface-coupling of antimicrobially active polymers using these end-groups were demonstrated. PMID:21499549

New Methods for the Site-Selective Placement of Peptides on a Microelectrode Array: Probing VEGF-v107 Binding as Proof of Concept.

PubMed

Graaf, Matthew D; Marquez, Bernadette V; Yeh, Nai-Hua; Lapi, Suzanne E; Moeller, Kevin D

2016-10-21

Cu(I)-catalyzed "click" reactions cannot be performed on a borate ester derived polymer coating on a microelectrode array because the Cu(II) precursor for the catalyst triggers background reactions between both acetylene and azide groups with the polymer surface. Fortunately, the Cu(II)-background reaction can itself be used to site-selectively add the acetylene and azide nucleophiles to the surface of the array. In this way, molecules previously functionalized for use in "click" reactions can be added directly to the array. In a similar fashion, activated esters can be added site-selectively to a borate ester coated array. The new chemistry can be used to explore new biological interactions on the arrays. Specifically, the binding of a v107 derived peptide with both human and murine VEGF was probed using a functionalized microelectrode array.

JPRS Report, Science & Technology, Japan, Selections from Future Industrial Technology Symposium.

DTIC Science & Technology

1988-08-01

pyrolyzed graphite ( HOPG ). X-ray diffraction photos of the biaxially stretched PPV films indicate that the films have been plane-oriented. It is...CRYSTALS OF TWO-DIMENSIONALLY CROSS-LINKED POLYMERS PRODUCED 8 ION-CROSSLINKING POLYMER COMPACTS EVALUATED 12 RECENT PROGRESS IN SYNTHETIC METALS...derived from 2,5-thienylene bis(methylene dimethyl sulfonium bromide). Highly conducting graphite films also have been obtained by pyrolysis of PPV and

Simple and Rapid Immobilization of Coating Polymers on Poly(dimethyl siloxane)-glass Hybrid Microchips by a Vacuum-drying Method.

PubMed

Kitagawa, Fumihiko; Nakagawara, Syo; Nukatsuka, Isoshi; Hori, Yusuke; Sueyoshi, Kenji; Otsuka, Koji

2015-01-01

A simple and rapid vacuum-drying modification method was applied to several neutral and charged polymers to obtain coating layers for controlling electroosmotic flow (EOF) and suppressing sample adsorption on poly(dimethyl siloxane) (PDMS)-glass hybrid microchips. In the vacuum-dried poly(vinylpyrrolidone) coating, the electroosmotic mobility (μeo) was suppressed from +2.1 to +0.88 × 10(-4) cm(2)/V·s, and the relative standard deviation (RSD) of μeo was improved from 10.2 to 2.5% relative to the bare microchannel. Among several neutral polymers, poly(vinylalcohol) (PVA) and poly(dimethylacrylamide) coatings gave more suppressed and repeatable EOF with RSDs of less than 2.3%. The vacuum-drying method was also applicable to polyanions and polycations to provide accelerated and inversed EOF, respectively, with acceptable RSDs of less than 4.9%. In the microchip electrophoresis (MCE) analysis of bovine serum albumin (BSA) in the vacuum-dried and thermally-treated PVA coating channel, an almost symmetric peak of BSA was obtained, while in the native microchannel a significantly skewed peak was observed. The results demonstrated that the vacuum-dried polymer coatings were effective to control the EOF, and reduced the surface adsorption of proteins in MCE.

New polymers for composites: A summary of research on polystyrylpyridines

NASA Technical Reports Server (NTRS)

Pearce, E. M.

1983-01-01

Styrylpyridine and its derivatives are studied. The synthesis, characterization, and thermal stability of styrylpyridine based polymers are discussed, as well as the preparation of a diglycidyl ester of styrylpridine. Also discussed are the preparation of polyarylates, and styrylpyridine based polytriazines and prepolymers.

Photo-enhanced performance and photo-tunable degradation in LC ecopolymers

NASA Astrophysics Data System (ADS)

Kaneko, Tatsuo

2007-05-01

Photosensitive, liquid crystalline (LC) polymers were prepared by in-bulk polymerization of phytomonomers such as cinnamic acid derivatives. The p-coumaric acid (4HCA) homopolymer showed a thermotropic LC phase where a photoreaction of [2+2] cycloaddition occurred by ultraviolet irradiation. LC phase was exhibited only in a low molecular weight state but the polymer was too brittle to materialize. Then we copolymerized 4HCA with multifunctional cinnamate, 3,4 dihydroxycinnamic acid (caffeic acid; DHCA), to prepare the hyperbranching architecture. Many branches increased the apparent size of the polymer chain but kept the low number-average molecular weight. P(4HCA-co-DHCA)s showed high performances which may be attained through the entanglement by in-bulk formation of hyperbranching, rigid structures. P(4HCA-co-DHCA)s showed a smooth hydrolysis, an in-soil degradation and a photoreaction cross-linking from conjugated cinnamate esters to aliphatic esters. The change in photoconversion degree tuned the polymer performance and chain hydrolysis.

Addition Polyimides from Non-Mutagenic Diamines

NASA Technical Reports Server (NTRS)

Delvigs, Peter; Klopotek, David L.; Hardy-Green, DeNise; Meador, Michael A. (Technical Monitor)

2001-01-01

Studies were conducted to find an acceptable non-mutagenic diamine to replace 4,4'-methylenedianiline (MDA), a suspect carcinogen, which is currently being used in PMR-15 polyimide applications. Several diamines containing fluorine and trifluoromethyl substituent groups were synthesized. The diamines were polymerized with the dimethyl ester of 3,3',4,4'-benzophenone tetracarboxylic acid (BTDE), using the monomethyl ester of nadic acid (NE) as an endcap. The effect of diamine structure on rheological properties, glass transition temperature, and thermo-oxidative stability was investigated. Unidirectional laminates were fabricated from selected resins, using carbon fiber as the reinforcement. The results indicate that some of the diamines containing trifluoromethyl groups are non-mutagenic, and have potential to replace MDA in PMR polyimides for long-term applications at temperatures up to 300 C.

Development and applications of injectable poly(ortho esters) for pain control and periodontal treatment.

PubMed

Helle, J; Barr, J; Ng, S Y; Shen, H R; Schwach-Abdellaoui, K; Gurny, R; Vivien-Castioni, N; Loup, P J; Baehni, P; Mombelli, A

2002-11-01

Poly(ortho esters) with a low glass transition temperature are semi-solid materials so that therapeutic agents can be incorporated at room temperature, without the use of solvents, by a simple mixing procedure. When molecular weights are limited to < 5 kDa, such materials are directly injectable using a needle size no larger than 22 gauge. Somewhat hydrophilic polymers can be produced by using the diketene acetal 3,9-diethylidene-2,4,8,10-tetraoxaspiro[5.5]undecane and triethylene glycol (TEG), while hydrophobic materials can be produced by using the diketene acetal and 1,10-decanediol. Molecular weight can be reproducibly controlled by using an excess of the diol, or by use of an alcohol that acts as a chain-stopper. Erosion rates can be controlled by varying the amount of latent acid incorporated into the polymer backbone. Toxicology studies using the TEG polymer have been completed and have shown that the polymer is non-toxic. Toxicology studies using the decanediol polymer are underway. Development studies using the TEG polymer aimed at providing a sustained delivery of an analgesic agent to control post-surgical pain are under development and human clinical trials using the decanediol polymer for the treatment of periodontitis are also underway.

Tailoring Pore Size and Chemical Interior of near 1 nm Sized Pores in a Nanoporous Polymer Based on a Discotic Liquid Crystal

PubMed Central

2017-01-01

A triazine based disc shaped molecule with two hydrolyzable units, imine and ester groups, was polymerized via acyclic diene metathesis in the columnar hexagonal (Colhex) LC phase. Fabrication of a cationic nanoporous polymer (pore diameter ∼1.3 nm) lined with ammonium groups at the pore surface was achieved by hydrolysis of the imine linkage. Size selective aldehyde uptake by the cationic porous polymer was demonstrated. The anilinium groups in the pores were converted to azide as well as phenyl groups by further chemical treatment, leading to porous polymers with neutral functional groups in the pores. The pores were enlarged by further hydrolysis of the ester groups to create ∼2.6 nm pores lined with −COONa surface groups. The same pores could be obtained in a single step without first hydrolyzing the imine linkage. XRD studies demonstrated that the Colhex order of the monomer was preserved after polymerization as well as in both the nanoporous polymers. The porous anionic polymer lined with −COOH groups was further converted to the −COOLi, −COONa, −COOK, −COOCs, and −COONH4 salts. The porous polymer lined with −COONa groups selectively adsorbs a cationic dye, methylene blue, over an anionic dye. PMID:28416888

Chemical Modification of Cellulose Esters for Oral Drug Delivery

NASA Astrophysics Data System (ADS)

Meng, Xiangtao

Polymer functional groups have critical impacts upon physical, chemical and mechanical properties, and thus affect the specific applications of the polymer. Functionalization of cellulose esters and ethers has been under extensive investigation for applications including drug delivery, cosmetics, food ingredients, and automobile coating. In oral delivery of poorly water-soluble drugs, amorphous solid dispersion (ASD) formulations have been used, prepared by forming miscible blends of polymers and drugs to inhibit crystallization and enhance bioavailability of the drug. The Edgar and Taylor groups have revealed that some cellulose o-carboxyalkanoates were highly effective as ASD polymers, with the pendant carboxylic acid groups providing both specific polymer-drug interactions and pHtriggered release through swelling of the ionized polymer matrix. While a variety of functional groups such as hydroxyl and amide groups are also of interest, cellulose functionalization has relied heavily on classical methods such as esterification and etherification for appending functional groups. These methods, although they have been very useful, are limited in two respects. First, they typically employ harsh reaction conditions. Secondly, each synthetic pathway is only applicable for one or a narrow group of functionalities due to restrictions imposed by the required reaction conditions. To this end, there is a great impetus to identify novel reactions in cellulose modification that are mild, efficient and ideally modular. In the initial effort to design and synthesize cellulose esters for oral drug delivery, we developed several new methods in cellulose functionalization, which can overcome drawbacks of conventional synthetic pathways, provide novel cellulose derivatives that are otherwise inaccessible, and present a platform for structure-property relationship study. Cellulose o-hydroxyalkanoates were previously difficult to access as the hydroxyl groups, if not protected, react with carboxylic acid/carbonyl during a typical esterification reaction or ring opening of lactones, producing cellulose-g-polyester and homopolyester. We demonstrated the viability of chemoselective olefin hydroboration-oxidation in the synthesis of cellulose o-hydroxyesters in the presence of ester groups. Cellulose esters with terminally olefinic side chains were transformed to the target products by two-step, one-pot hydroborationoxidation reactions, using 9-borabicyclo[3.3.1]nonane (9-BBN) as hydroboration agent, followed by oxidizing the organoborane intermediate to a primary alcohol using mildly alkaline H2O2. The use of 9-BBN as hydroboration agent and sodium acetate as base catalyst in oxidation successfully avoided cleavage of ester linkages by borane reduction and base catalyzed hydrolysis. With the impetus of modular and efficient synthesis, we introduced olefin crossmetathesis (CM) in polysaccharide functionalization. Using Grubbs type catalyst, cellulose esters with terminally olefinic side chains were reacted with various CM partners including acrylic acid, acrylates and acrylamides to afford families of functionalized cellulose esters. Molar excesses of CM partners were used in order to suppress potential crosslinking caused by self-metathesis between terminally olefinic side chains. Amide CM partners can chelate with the ruthenium catalyst and cause low conversions in conventional solvents such as THF. While the inherent reactivity toward CM and tendency of acrylamides to chelate Ru is influenced by the acrylamide N-substituents, employing acetic acid as a solvent significantly improved the conversion of certain acrylamides. We observed that the CM products are prone to crosslinking during storage, and found that the crosslinking is likely caused by free radical abstraction of gamma-hydrogen of the alpha,beta-unsaturation and subsequent recombination. We further demonstrated successful hydrogenation of these alpha,beta-unsaturated acids, esters, and amides, thereby eliminating the potential for radical-induced crosslinking during storage. The alpha,beta-unsaturation on CM products can cause crosslinking due to gamma-H abstraction and recombination if not reduced immediately after reaction. Instead of eliminating the double bond by hydrogenation, we described a method to make use of these reactive conjugated olefins by post-CM thiol-Michael addition. Under amine catalysis, different CM products and thiols were combined and reacted. Using proper thiols and catalyst, complete conversion can be achieved under mild reaction conditions. The combination of the two modular reactions creates versatile access to multi-functionalized cellulose derivatives. Compared with conventional reactions, these reactions enable click or click-like conjugation of functional groups onto cellulose backbone. The modular profile of the reactions enables clean and informative structure-property relationship studies for ASD. These approaches also provide opportunities for the synthesis of chemically and architecturally diverse cellulosic polymers that are otherwise difficult to access, opening doors for many other applications such as antimicrobial, antifouling, in vivo drug delivery, and bioconjugation. We believe that the cellulose functionalization approaches we pioneered can be expanded to the modification of other polysaccharides and polymers, and that these reactions will become useful tools in the toolbox of polymer/polysaccharide chemists.

Surface functionalization of quantum dots with fine-structured pH-sensitive phospholipid polymer chains.

PubMed

Liu, Yihua; Inoue, Yuuki; Ishihara, Kazuhiko

2015-11-01

To add novel functionality to quantum dots (QDs), we synthesized water-soluble and pH-responsive block-type polymers by reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymers were composed of cytocompatible 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer segments, which contain a small fraction of active ester groups and can be used to conjugate biologically active compounds to the polymer, and pH-responsive poly(2-(N,N-diethylamino) ethyl methacrylate (DEAEMA)) segments. One terminal of the polymer chain had a hydrophobic alkyl group that originated from the RAFT initiator. This hydrophobic group can bind to the hydrophobic layer on the QD surface. A fluorescent dye was conjugated to the polymer chains via the active ester group. The block-type polymers have an amphiphilic nature in aqueous medium. The polymers were thus easily bound to the QD surface upon evaporation of the solvent from a solution containing the block-type polymer and QDs, yielding QD/fluorescence dye-conjugated polymer hybrid nanoparticles. Fluorescence resonance energy transfer (FRET) between the QDs (donors) and the fluorescent dye molecules (acceptors) was used to obtain information on the conformational dynamics of the immobilized polymers. Higher FRET efficiency of the QD/fluorescent dye-conjugated polymer hybrid nanoparticles was observed at pH 7.4 as compared to pH 5.0 due to a stretching-shrinking conformational motion of the poly(DEAEMA) segments in response to changes in pH. We concluded that the block-type MPC polymer-modified nanoparticles could be used to evaluate the pH of cells via FRET fluorescence based on the cytocompatibility of the MPC polymer. Copyright © 2015 Elsevier B.V. All rights reserved.

21 CFR 189.300 - Hydrogenated 4,4′-isopropyl-idene-diphenol-phosphite ester resins.

Code of Federal Regulations, 2014 CFR

2014-04-01

... manufacture of rigid vinyl chloride polymer bottles. (b) Food containing any added or detectable levels of... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Hydrogenated 4,4â²-isopropyl-idene-diphenol-phosphite ester resins. 189.300 Section 189.300 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF...

Evaluating dispensers loaded with codlemone and pear ester for disruption of codling moth (Lepidoptera: Tortricidae)

USDA-ARS?s Scientific Manuscript database

Polyvinyl chloride polymer (pvc) dispensers loaded with ethyl (E,Z)-2,4-decadienoate (pear ester) plus the sex pheromone, (E,E)-8,10-dodecadien-1-ol (codlemone) of codling moth, Cydia pomonella (L.), were compared with similar dispensers and a commercial dispenser (Isomate®-C Plus) loaded with codle...

Tung oil-based unsaturated co-ester macromonomer for thermosetting polymers: Synergetic synthesis and copolymerization with styrene

USDA-ARS?s Scientific Manuscript database

A novel unsaturated co-ester (co-UE) macromonomer containing both maleates and acrylates was synthesized from tung oil (TO) and its chemical structure was characterized by FT-IR, 1H-NMR, 13C-NMR, and gel permeation chromatography (GPC). The monomer was synthesized via a new synergetic modification o...

Gold-nanoparticle-based catalysts for the oxidative esterification of 1,4-butanediol into dimethyl succinate.

PubMed

Brett, Gemma L; Miedziak, Peter J; He, Qian; Knight, David W; Edwards, Jennifer K; Taylor, Stuart H; Kiely, Christopher J; Hutchings, Graham J

2013-10-01

The oxidation of 1,4-butanediol and butyrolactone have been investigated by using supported gold, palladium and gold-palladium nanoparticles. The products of such reactions are valuable chemical intermediates and, for example, can present a viable pathway for the sustainable production of polymers. If both gold and palladium were present, a significant synergistic effect on the selective formation of dimethyl succinate was observed. The support played a significant role in the reaction, with magnesium hydroxide leading to the highest yield of dimethyl succinate. Based on structural characterisation of the fresh and used catalysts, it was determined that small gold-palladium nanoalloys supported on a basic Mg(OH)2 support provided the best catalysts for this reaction. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ethynyl-terminated ester oligomers and polymers therefrom

NASA Technical Reports Server (NTRS)

Hergenrother, Paul M. (Inventor); Havens, Stephen J. (Inventor)

1986-01-01

A class of ethynyl terminated oligomers and the process for preparing the same are disclosed. Upon the application of heat, with or without a catalyst, the ethynyl groups react to provide crosslinking and chain extension to increase the polymer use temperature and improve the polymer solvent resistance. These polyesters are potentially useful in packaging, magnetic tapes, capacitors, industrial belting, protective coatings, structural adhesives and composite matrices.

Ethynyl terminated ester oligomers and polymers therefrom

NASA Technical Reports Server (NTRS)

Hergenrother, Paul M. (Inventor); hesives and composite matrices. (Inventor)

1987-01-01

A new class of ethynyl-terminated oligomers and the process for preparing same are disclosed. Upon the application of heat, with or without a catalyst, the ethynyl groups react to provide crosslinking and chain extension to increase the polymer use temperature and improve the polymer solvent resistance. These improved polyesters are potentially useful in packaging, magnetic tapes, capacitors, industrial belting, protective coatings, structural adhesives and composite matrices.

Bioinspired Surface Treatments for Improved Decontamination: Silicon and Latex Polymer SLIPS Treatments

DTIC Science & Technology

2017-06-27

of the simulants paraoxon, methyl salicylate, dimethyl methylphosphate, and diisopropyl fluorophosphates following treatment of contaminated surfaces...Biological Defense Program (CBDP) seeks to provide protection of forces in a contaminated environment including contamination avoidance, individual

Flavonoids and terpenoids from Luma gayana (Barn.) Burret.

PubMed

Wächter, G A; Wangmaneerat, A; Caple, K M; Montenegro, G; Timmermann, B N

1999-12-01

The flavonoids 5-hydroxy-7-methoxyflavanone, 6,8-dimethyl-5,7-dihydroxyflavanone and 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone, a mixture of alkyl esters of p-coumaric acid, the triterpenoids oleanolic acid and maslinic acid, the monoterpenoid 1 alpha,2 beta,4 beta-trihydroxy-p-menthane, the sesquiterpenoid clovandiol and beta-sitosterol were isolated from the aerial parts of Luma gayana (Barn.) Burret. This is the first report on the chemistry of this species.

Utilization of Herbicide Concentration/Exposure Time Relationships for Controlling Submersed Invasive Plants on Lake Gaston, Virginia/North Carolina

DTIC Science & Technology

2011-06-01

of efficacy in controlling invasive plant species, and are verified in aquatic and wetland field sites throughout the US. This multi-tiered...localized treatment sites, moving or still water. Chlorosis of stems and leaves with plant death in 7-10 days. 2,4-D 3 DMA liquid, BEE salt...with Eurasian watermilfoil. Formulations include a liquid dimethyl amine (DMA) and a granular clay butoxyethanol ester ( BEE ). Current Evaluations

Direct sample introduction gas chromatography and mass spectrometry for the determination of phthalate esters in cleaning products.

PubMed

Cacho, J I; Campillo, N; Viñas, P; Hernández-Córdoba, M

2015-02-06

A method using direct sample introduction (DSI) coupled to gas chromatography-mass spectrometry (GC-MS) is developed for the determination of six phthalate esters (dimethyl, diethyl, dibutyl, butylbenzyl, diethylhexyl and dioctyl phthalate) in cleaning products. The different variables involved in the DSI step, including venting time and temperature, vaporisation time and temperature, injector heating temperature and gas flow rate and pressure, were evaluated and optimised using Taguchi orthogonal arrays. The proposed method, using calibration against methanolic standards, showed good linearity in the 0.05-15 μg g(-1) range and good repeatability, with RSD values ranging from 3.5% to 5.7%. Quantification limits between 0.010 and 0.041 μg g(-1), depending on the compound, were attained, while recovery assays provided values from 83% to 115%. Twenty-seven cleaning products were analysed using the DSI-GC-MS method, being four phthalates (dimethyl, diethyl, dibutyl and diethylhexyl phthalate) found in fourteen of them at concentration levels in the 0.1-21 μg g(-1) range. Compared with the most common GC injection technique, which uses the split/splitless injector, the proposed DSI procedure provided larger peak areas and lower detection limits, as result of the greater injected volume and reduction in noise. Copyright © 2014 Elsevier B.V. All rights reserved.

Optical isomer separation of potential analgesic drug candidates by using capillary electrophoresis.

PubMed

Ferrara, G; Santagati, N A; Aturki, Z; Fanali, S

1999-09-01

Using cyclodextrin capillary zone electrophoresis (CD-CZE), baseline separation of synthetic potential analgesic drug diastereoisomer candidates 6,11-dimethyl-1,2,3,4,5,6-hexahydro-3-[(2'-methoxycarbonyl-2'-phenylc yclopropyl)methyl]-2,6-methano-3-benzazocin-8-ol (MPCB) and 6,11-dimethyl-1,2,3,4,5,6-hexahydro-3-[[2'-methoxycarbonyl-2'(4-chloroph enyl)cyclopropyl]methyl]-2,6-methano-3-benzazocin-8-ol (CCB) was achieved. Among the cyclodextrins tested (hydroxypropyl-, carboxymethyl- and sulfobutyl-beta-cyclodextrin (HP-beta-CD, CM-beta-CD and SBE-beta-CD)) SBE-beta-CD was found to be the most effective complexing agent, allowing good optical isomer separation. Resolution was also influenced by the CD concentration, pH of the buffer and presence of organic modifier in the background electrolyte. The optimum experimental conditions for the separation of studied analgesic drugs were found using 25 mM borate buffer at pH 9 containing 40 mM of SBE-beta-CD and 20% v/v of methanol. Using the above-mentioned background electrolyte, it was also possible to separate, in the same run, the enantiomers of normetazocine (NMZ) as well as the optical isomers of (+/-)-cis-2-chloromethyl-1-phenyl cyclopropancarboxylic acid methyl ester (PCE) or (+/-)-cis-2-chloromethyl-1-(4-chlorophenyl)cyclopropancarboxylic acid methyl ester (CPCE) reagents used in the synthesis of the studied analgesic drugs).

Orthene? toxicity to little brown bats (Myotis lucifugus): Acetylcholinesterase inhibition, coordination loss, and mortality

USGS Publications Warehouse

Clark, D.R.; Rattner, B.A.

1987-01-01

The 24-h LD50 of Orhene (active ingredient acephate, acetylphosphoramidothioic acid o,s-dimethyl ester, CAS 30560-19-1) to little brown bats (Myotis lucifugus) was high (> 1,500 mg acephate/kg) and at least several times greater than the LD50 for mice (Mus musculus) (720 mg/kg). Twenty-four hours after dosing, all surviving mice appeared behaviorally normal, but 9 of 30 surviving bats could not right themselves when placed on their backs. When dead and incapacitated bats were combined to calculate an ED50 (median effective dose), the resultant estimate (687 mg/kg) did not differ (p > 0.05) from the LD50 for mice. Serum cholinesterase (ChE) activity in control bats was 3.2 times greater than in mice. The relationship between the naturally high level of ChE and the relative tolerance of bats to organophosphorus insecticides is unexplained. Toxicity of Orthene was clearly less than that reported elsewhere for methyl parathion (phosphorothioic acid o,o-dimethyl o-[4-nitrophenyl] ester, CAS 298-00-0). This finding may be useful in selection of a chemical for agricultural use, but conclusions about the safety of Orthene to this bat species, or to others, must remain tentative until confirmed by studies under field conditions. Because bats are long-lived with low reproductive rates and slow recruitment, any additional mortality in the wild could be critical to population survival.

Preparation, Characterization and Utilization of Electrodes Coated with Polymeric Networks Formed by Gamma Radiation Crosslinking.

DTIC Science & Technology

1987-04-01

polymers such as poly[ diallyl dimethyl ammonium chloride] , poly [vinylbenzyl trimethyl ammonium chloride], poly[styrene sulfonic acid , sodium salt] and...poly[acrylic acid ], which would ordinarily dissolve from the electrode surface in aqueous solution unless crosslinked into a network, and several...Irradiation on a Water-Soluble Polymer: DDAC 8 E. Electrochemistry of DDAC Networks on Platinum and Graphite 10 F. Poly [acrylic acid ] Films on Graphite

Photosensitized oxidation of unsaturated polymers

NASA Technical Reports Server (NTRS)

Golub, M. A.

1979-01-01

The photosensitized oxidation or singlet oxygenation of unsaturated hydrocarbon polymers and of their model compounds was reviewed. Emphasis was on cis and trans forms of 1,4-polyisoprene, 1,4-polybutadiene and 1,2-poly(1,4-hexadiene), and on 1,4-poly(2,3-dimethyl-1,3-butadiene). The microstructural changes which occur in these polymers on reaction with O2-1 in solution were investigated by infrared H-1 and C-13 NMR spectroscopy. The polymers were shown to yield allylic hydroperoxides with shifted double bonds according to the ene mechanism established for simple olefins. The photosensitized oxidation of the above unsaturated polymer exhibited zero order kinetics, the relative rates paralleling the reactivities of the corresponding simple olefins towards O2-1.

40 CFR 180.960 - Polymers; exemptions from the requirement of a tolerance.

Code of Federal Regulations, 2014 CFR

2014-07-01

...-hydroxypoly (oxypropylene) and/or poly (oxyethylene) polymers where the alkyl chain contains a minimum of six...-hydroxypoly(oxyethylene)poly (oxypropylene) poly(oxyethylene) block copolymer; the minimum poly(oxypropylene... weight (in amu), 900,000 62386-95-2 Monophosphate ester of the block copolymer α-hydro-ω-hydroxypoly...

Release of DNA from polyelectrolyte multilayers fabricated using 'charge-shifting' cationic polymers: tunable temporal control and sequential, multi-agent release.

PubMed

Sun, Bin; Lynn, David M

2010-11-20

We report an approach to the design of multilayered polyelectrolyte thin films (or 'polyelectrolyte multilayers', PEMs) that can be used to provide tunable control over the release of plasmid DNA (or multiple different DNA constructs) from film-coated surfaces. Our approach is based upon methods for the layer-by-layer assembly of DNA-containing thin films, and exploits the properties of a new class of cationic 'charge-shifting' polymers (amine functionalized polymers that undergo gradual changes in net charge upon side chain ester hydrolysis) to provide control over the rates at which these films erode and release DNA. We synthesized two 'charge-shifting' polymers (polymers 1 and 2) containing different side chain structures by ring-opening reactions of poly(2-alkenyl azlactone)s with two different tertiary amine functionalized alcohols (3-dimethylamino-1-propanol and 2-dimethylaminoethanol, respectively). Subsequent characterization revealed large changes in the rates of side chain ester hydrolysis for these two polymers; whereas the half-life for the hydrolysis of the esters in polymer 1 was ~200 days, the half-life for polymer 2 was ~6 days. We demonstrate that these large differences in side chain hydrolysis make possible the design of PEMs that erode and promote the surface-mediated release of DNA either rapidly (e.g., over ~3 days for films fabricated using polymer 2) or slowly (e.g., over ~1 month for films fabricated using polymer 1). We demonstrate further that it is possible to design films with release profiles that are intermediate to these two extremes by fabricating films using solutions containing different mixtures of these two polymers. This approach can thus expand the usefulness of these two polymers and achieve a broader range of DNA release profiles without the need to synthesize polymers with new structures or properties. Finally, we demonstrate that polymers 1 and 2 can be used to fabricate multilayered films with hierarchical structures that promote the sequential release of two different DNA constructs with separate and distinct release profiles (e.g., the release of a first construct over a period of ~3 days, followed by the sustained release of a second for a period of ~70 days). With further development, this approach could contribute to the design of functional thin films and surface coatings that provide sophisticated control over the timing and the order of the release of two or more DNA constructs (or other agents) of interest in a range of biomedical contexts. Copyright © 2010 Elsevier B.V. All rights reserved.

Optimization of structural and dielectric properties of CdSe loaded poly(diallyl dimethyl ammonium chloride) polymer in a desired frequency and temperature window

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tyagi, Chetna, E-mail: ctyagi05@gmail.com; Sharma, Ambika, E-mail: ambikasharma2004@yahoo.com

2016-01-07

In the present paper, investigations of CdSe loaded poly(diallyl dimethyl ammonium chloride) (PDADMAC) nanocomposites and pure PDADMAC synthesized by wet chemical technique have been carried out. Fourier transform infrared and X-ray diffraction analysis have been performed to reveal the structural details of pure polymer and polymer nanocomposite (PNC). The dielectric behavior of pure polymer and PNC has been recorded, which results in higher value of the real and imaginary part of dielectric constant for PNC, as compared with pure PDADMAC. The increase is attributed to the addition of CdSe quantum dots to the pure polymer. The contribution of ionic andmore » electronic polarization has been observed at higher frequency. The theoretical fitting of Cole-Cole function to the experimental data of dielectric constant of PNC and pure PDADMAC results in the determination of relaxation time and conductivity of space charge carriers. The CdSe loaded polymer nanocomposite has been used as an electrolyte in the battery fabrication with configuration Al/PNC/Ag{sub 2}O. The ac conductivity measurements have been carried out for both samples in a frequency window of 1 kHz–5 MHz and at different temperatures varying from 298 K to 523 K. Activation energy (E{sub a}) has been determined for pure polymer as well as PNC and is found to be less for PNC, as compared with pure polymer. Further, impedance measurement at different temperatures results in two frequency ranges corresponding to ionic conduction and blocking electrode effect. The value of bulk resistance for pure polymer and PNC has been found to be 3660 Ω and 442 Ω, respectively, at 298 K temperature. Electric modulus has been determined and is observed to support the dielectric constant data; it further reveals the deviation from Debye behavior at a higher frequency.« less

21 CFR 189.300 - Hydrogenated 4,4′-isopropyl-idene-diphenol-phosphite ester resins.

Code of Federal Regulations, 2012 CFR

2012-04-01

... resins are used in the manufacture of rigid vinyl chloride polymer bottles. (b) Food containing any added... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Hydrogenated 4,4â²-isopropyl-idene-diphenol-phosphite ester resins. 189.300 Section 189.300 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF...

21 CFR 189.300 - Hydrogenated 4,4′-isopropyl-idene-diphenol-phosphite ester resins.

Code of Federal Regulations, 2013 CFR

2013-04-01

... resins are used in the manufacture of rigid vinyl chloride polymer bottles. (b) Food containing any added... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Hydrogenated 4,4â²-isopropyl-idene-diphenol-phosphite ester resins. 189.300 Section 189.300 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF...

A bioreducible linear poly(β-amino ester) for siRNA delivery

PubMed Central

Kozielski, Kristen L.; Tzeng, Stephany Y.; Green, Jordan J.

2014-01-01

Described here is the synthesis and characterization of a novel, bioreducible linear poly(β-amino ester) designed to condense siRNA into nanoparticles and efficiently release it upon entering the cytoplasm. Delivery of siRNA using this polymer achieved near-complete knockdown of a fluorescent marker gene in primary human glioblastoma cells with no cytotoxicity. PMID:23646347

Glass Transition Temperature Measurement for Undercured Cyanate Ester Networks: Challenges, Tips, and Tricks (Briefing Charts)

DTIC Science & Technology

2014-01-29

DISTRIBUTION A: Approved for public release; distribution is unlimited. Thermosetting Polymers Have a TG Envelope – Not Just a TG 4 • The glass transition...glass transition temperature of a thermosetting polymer can vary over a wide range of temperatures depending on how the polymer is processed • A... thermosetting polymer with only one kind of network formation and negligible side reactions, the conversion may be determined at every point in the scan. • By

Physiological and Chemical Investigations into Microbial Degradation of Synthetic Poly(cis-1,4-isoprene)

PubMed Central

Bode, Helge B.; Zeeck, Axel; Plückhahn, Kirsten; Jendrossek, Dieter

2000-01-01

Streptomyces coelicolor 1A and Pseudomonas citronellolis were able to degrade synthetic high-molecular-weight poly(cis-1,4-isoprene) and vulcanized natural rubber. Growth on the polymers was poor but significantly greater than that of the nondegrading strain Streptomyces lividans 1326 (control). Measurement of the molecular weight distribution of the polymer before and after degradation showed a time-dependent increase in low-molecular-weight polymer molecules for S. coelicolor 1A and P. citronellolis, whereas the molecular weight distribution for the control (S. lividans 1326) remained almost constant. Three degradation products were isolated from the culture fluid of S. coelicolor 1A grown on vulcanized rubber and were identified as (6Z)-2,6-dimethyl-10-oxo-undec-6-enoic acid, (5Z)-6-methyl-undec-5-ene-2,9-dione, and (5Z,9Z)-6,10-dimethyl-pentadec-5,9-diene-2,13-dione. An oxidative pathway from poly(cis-1,4-isoprene) to methyl-branched diketones is proposed. It includes (i) oxidation of an aldehyde intermediate to a carboxylic acid, (ii) one cycle of β-oxidation, (iii) oxidation of the conjugated double bond resulting in a β-keto acid, and (iv) decarboxylation. PMID:10966376

Pressure-induced amorphization and reactivity of solid dimethyl acetylene probed by in situ FTIR and Raman spectroscopy

NASA Astrophysics Data System (ADS)

Guan, Jiwen; Daljeet, Roshan; Kieran, Arielle; Song, Yang

2018-06-01

Conjugated polymers are prominent semiconductors that have unique electric conductivity and photoluminescence. Synthesis of conjugated polymers under high pressure is extremely appealing because it does not require a catalyst or solvent used in conventional chemical methods. Transformation of acetylene and many of its derivatives to conjugated polymers using high pressure has been successfully achieved, but not with dimethyl acetylene (DMA). In this work, we present a high-pressure study on solid DMA using a diamond anvil cell up to 24.4 GPa at room temperature characterized by in situ Fourier transform infrared and Raman spectroscopy. Our results show that solid DMA exists in a phase II crystal structure and is stable up to 12 GPa. Above this pressure, amorphization was initiated and the process was completed at 24.4 GPa. The expected polymeric transformation was not evident upon compression, but only observed upon decompression from a threshold compression pressure (e.g. 14.4 GPa). In situ florescence measurements suggest excimer formation via crystal defects, which induces the chemical reactions. The vibrational spectral analysis suggests the products contain the amorphous poly(DMA) and possibly additional amorphous hydrogenated carbon material.

Pressure-induced amorphization and reactivity of solid dimethyl acetylene probed by in situ FTIR and Raman spectroscopy.

PubMed

Guan, Jiwen; Daljeet, Roshan; Kieran, Arielle; Song, Yang

2018-06-06

Conjugated polymers are prominent semiconductors that have unique electric conductivity and photoluminescence. Synthesis of conjugated polymers under high pressure is extremely appealing because it does not require a catalyst or solvent used in conventional chemical methods. Transformation of acetylene and many of its derivatives to conjugated polymers using high pressure has been successfully achieved, but not with dimethyl acetylene (DMA). In this work, we present a high-pressure study on solid DMA using a diamond anvil cell up to 24.4 GPa at room temperature characterized by in situ Fourier transform infrared and Raman spectroscopy. Our results show that solid DMA exists in a phase II crystal structure and is stable up to 12 GPa. Above this pressure, amorphization was initiated and the process was completed at 24.4 GPa. The expected polymeric transformation was not evident upon compression, but only observed upon decompression from a threshold compression pressure (e.g. 14.4 GPa). In situ florescence measurements suggest excimer formation via crystal defects, which induces the chemical reactions. The vibrational spectral analysis suggests the products contain the amorphous poly(DMA) and possibly additional amorphous hydrogenated carbon material.

Combining mass spectrometry diagnostic and density functional theory calculations for a better understanding of the plasma polymerization of ethyl lactate.

PubMed

Ligot, S; Guillaume, M; Gerbaux, P; Thiry, D; Renaux, F; Cornil, J; Dubois, P; Snyders, R

2014-04-17

The focus of this work is on the growth mechanism of ethyl lactate-based plasma polymer film (ELPPF) that could be used as barrier coatings. In such an application, the ester density of the plasma polymer has to be controlled to tune the degradation rate of the material. Our strategy consists of correlating the plasma chemistry evaluated by RGA mass spectrometry and understanding, via DFT calculations, the chemistry of the synthesized thin films. The theoretical calculations helped us to understand the plasma chemistry in plasma ON and OFF conditions. From these data it is unambiguously shown that the signal m/z 75 can directly be correlated with the precursor density in the plasma phase. The combination of XPS and chemical derivatization experiments reveal that the ester content in the ELPFF can be tailored from 2 to 18 at. % by decreasing the RF power, which is perfectly correlated with the evolution of the plasma chemistry. Our results also highlight that the ELPPF chemistry, especially the ester content, is affected by the plasma mode of operation (continuous or pulsed discharge, at similar injected mean power) for similar ester content in the plasma. This could be related to different energy conditions at the interface of the growing films that could affect the sticking coefficient of the ester-bearing fragments.

An Iterative O-Methyltransferase Catalyzes 1,11-Dimethylation of Aspergillus fumigatus Fumaric Acid Amides.

PubMed

Kalb, Daniel; Heinekamp, Thorsten; Schieferdecker, Sebastian; Nett, Markus; Brakhage, Axel A; Hoffmeister, Dirk

2016-10-04

S-adenosyl-l-methionine (SAM)-dependent methyltransfer is a common biosynthetic strategy to modify natural products. We investigated the previously uncharacterized Aspergillus fumigatus methyltransferase FtpM, which is encoded next to the bimodular fumaric acid amide synthetase FtpA. Structure elucidation of two new A. fumigatus natural products, the 1,11-dimethyl esters of fumaryl-l-tyrosine and fumaryl-l-phenylalanine, together with ftpM gene disruption suggested that FtpM catalyzes iterative methylation. Final evidence that a single enzyme repeatedly acts on fumaric acid amides came from an in vitro biochemical investigation with recombinantly produced FtpM. Size-exclusion chromatography indicated that this methyltransferase is active as a dimer. As ftpA and ftpM homologues are found clustered in other fungi, we expect our work will help to identify and annotate natural product biosynthesis genes in various species. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Highly sensitive surface enhanced Raman scattering substrates based on Ag decorated Si nanocone arrays and their application in trace dimethyl phthalate detection

NASA Astrophysics Data System (ADS)

Zuo, Zewen; Zhu, Kai; Ning, Lixin; Cui, Guanglei; Qu, Jun; Cheng, Ying; Wang, Junzhuan; Shi, Yi; Xu, Dongsheng; Xin, Yu

2015-01-01

Wafer-scale three-dimensional (3D) surface enhancement Raman scattering (SERS) substrates were prepared using the plasma etching and ion sputtering methods that are completely compatible with well-established silicon device technologies. The substrates are highly sensitive with excellent uniformity and reproducibility, exhibiting an enhancement factor up to 1012 with a very low relative standard deviation (RSD) around 5%. These are attributed mainly to the uniform-distributed, multiple-type high-density hot spots originating from the structural characteristics of Ag nanoparticles (NPs) decorated Si nanocone (NC) arrays. We demonstrate that the trace dimethyl phthalate (DMP) at a concentration of 10-7 M can be well detected using this SERS substrate, showing that the AgNPs-decorated SiNC arrays can serve as efficient SERS substrates for phthalate acid esters (PAEs) detection with high sensitivity.

Potential toxicity of phthalic acid esters plasticizer: interaction of dimethyl phthalate with trypsin in vitro.

PubMed

Wang, Yaping; Zhang, Guowen; Wang, Langhong

2015-01-14

Dimethyl phthalate (DMP) is widely used as a plasticizer in industrial processes and has been reported to possess potential toxicity to the human body. In this study, the interaction between DMP and trypsin in vitro was investigated. The results of fluorescence, UV–vis, circular dichroism, and Fourier transform infrared spectra along with cyclic voltammetric measurements indicated that the remarkable fluorescence quenching and conformational changes of trypsin resulted from the formation of a DMP–trypsin complex, which was driven mainly by hydrophobic interactions. The molecular docking and trypsin activity assay showed that DMP primarily interacted with the catalytic triad of trypsin and led to the inhibition of trypsin activity. The dimensions of the individual trypsin molecules were found to become larger after binding with DMP by atomic force microscopy imaging. This study offers a comprehensive picture of DMP–trypsin interaction, which is expected to provide insights into the toxicological effect of DMP.

The aroma volatile repertoire in strawberry fruit: a review.

PubMed

Yan, Jia-Wei; Ban, Zhao-Jun; Lu, Hong-Yan; Li, Dong; Poverenov, Elena; Li, Li; Luo, Zi-Sheng

2018-03-30

Aroma significantly contributes to flavor, which directly affects commercial quality of strawberry. Strawberry aroma is complex as many kinds of volatile compounds are found in strawberries. In this review, we describe the current knowledge of constituents and biosynthesis of strawberry volatile compounds, and the effect of postharvest treatments on aroma profiles. The characteristic strawberry volatile compounds consist of furanones, such as 2,5-dimethyl-4-hydroxy-3(2H)-furanone and 4-methoxy-2,5-dimethyl-3(2H)-furanone; esters including ethyl butanoate, ethyl hexanoate, methyl butanoate, and methyl hexanoate; sulfur compounds such as methanethiol, and terpenoids including linalool and nerolidol. As for postharvest treatment, the present review discusses the overview of aroma volatiles in response to temperature, atmosphere, and exogenous hormone as well as other treatments including ozone, edible coating and ultraviolet radiation. In addition, the future prospects for strawberry volatile biosynthesis and metabolism are presented. This article is protected by copyright. All rights reserved.

Analysis of organic volatile flavor compounds in fermented stinky tofu using SPME with different fiber coatings.

PubMed

Liu, Yuping; Miao, Zhiwei; Guan, Wei; Sun, Baoguo

2012-03-26

The organic volatile flavor compounds in fermented stinky tofu (FST) were studied using SPME-GC/MS. A total of 39 volatile compounds were identified, including nine esters, seven alcohols, five alkenes, four sulfides, three heterocycles, three carboxylic acids, three ketones, two aldehydes, one phenol, one amine and one ether. These compounds were determined by MS, and conformed by comparison of the retention times of the separated constituents with those of authentic samples and by comparison of retention indexes (RIs) of separated constituents with the RIs reported in the literature. The predominant volatile compound in FST was indole, followed by dimethyl trisulfide, phenol, dimethyl disulfide and dimethyl tetrasulfide. In order to find a better extraction time, the extraction times was optimized for each type of SPME fiber; the results show that the best extraction time for Carboxen/PDMS is 60 min, for PDMS/DVB 30 min, for DVB/CAR/PDMS 60 min and for PDMS 75 min. Of the four fibers used in this work, Carboxen/PDMS is found to be the most suitable to extract the organic volatile flavor compounds in fermented stinky tofu.

Assessment of potential false positives via orbitrap-based untargeted lipidomics from rat tissues.

PubMed

Xu, Lina; Wang, Xueying; Jiao, Yupei; Liu, Xiaohui

2018-02-01

Untargeted lipidomics is increasingly popular due to the broad coverage of lipid species. Data dependent MS/MS acquisition is commonly used in order to acquire sufficient information for confident lipid assignment. However, although lipids are identified based on MS/MS confirmation, a number of false positives are still observed. Here, we discuss several causes of introducing lipid false identifications in untargeted analysis. Phosphotidylcholines and cholesteryl esters generate in-source fragmentation to produce dimethylated phosphotidylethanolamine and free cholesterol. Dimerization of fatty acid results in false identification of fatty acid ester of hydroxyl fatty acid. Realizing these false positives is able to improve confidence of results acquired from untargeted analysis. Besides, thresholds are established for lipids identified using LipidSearch v4.1.16 software to reduce unreliable results. Copyright © 2017 Elsevier B.V. All rights reserved.

Ultrastructure Processing of Macromolecular Materials.

DTIC Science & Technology

1983-09-01

349-356 (1982) (with R. Vukovic , V. Kuresevic, and W. J . MacKnight) "The Investigation of the Compatibility and Phase Separation of Poly (2,6-Dimethyl...Sci. 28, 219-224 (1983) (with R. Vukovic , W. J . MacKnight) "Compatibility of Some Fluorosubstituted Styrene Polymers and Copolymers in Blends with Poly...Points in Blends of Polystyrene and Poly (o-chlorostyrene)". 15. Polymer 24, 529-533 (1983) (with R. Vukovic and W. J . MacKnight) "Compati--ity of Poly(p

Proceedings of the 1995 SAE alternative fuels conference. P-294

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1995-12-31

This volume contains 32 papers and five panel discussions related to the fuel substitution of trucks, automobiles, buses, cargo handling equipment, diesel passenger cars, and pickup trucks. Fuels discussed include liquefied natural gas, natural gas, ethanol fuels, methanol fuels, dimethyl ether, methyl esters from various sources (rape oil, used cooking oils, soya, and canola oils), hydrogen fuels, and biodiesel. Other topics include fuel cell powered vehicles, infrastructure requirements for fuel substitution, and economics. Papers have been processed separately for inclusion on the data base.

Preliminary Assessment/Site Investigation, Tooele Army Depot, Utah. Volume 2. South Area. Appendixes

DTIC Science & Technology

1988-12-01

METHYL BENZOATE BZOTHP BENZO [B) THIOPHENE BZOTRZ 1H-BENZOThIAZOLE / 1,* 2 , 3 -SENZOThIAZO! E BZPA BENZENEPHOSPHONIC ACID BZYLBR BENZYL BROMIDE / ALPH.A...DEFINITIONS ~ STEST-NAMLE Cil MENECANE C12 DODECANE CI2AMM 8-KETHYLDECANOIC ACID , METHYL ESTER C12DCE CIS-l , 2 -DICHLOROETHENE C13 TRIDECANE C13DCP CIS-1 , 3 ...DBTSPY 4,5-DIMETHYL-2,6-BIS(ThIMETHYLSILOXY)PYRINIDINE DSZFIJR DIBDNZOFURAN DBZTHP DIBENZOThIOPHENE DCAKIBA 2 -METHOXY- 3 ,6-DICHLOROBENZOIC ACID DCBPH

Honeycomb structural composite polymer network of gelatin and functional cellulose ester for controlled release of omeprazole.

PubMed

Zhuang, Chen; Shi, Chengmei; Tao, Furong; Cui, Yuezhi

2017-12-01

The functionalized cellulose ester MCN was firstly synthesized and used to cross-link gelatin by amidation between -NH 2 in gelatin and active ester groups in MCN to form a composite polymer network Gel-MCN, which was confirmed by Van Slyke method, FTIR, XRD and TGA-DTG spectra. The model drug omeprazole was loaded in Gel-MCN composites mainly by electrostatic interaction and hydrogen bonds, which were certified by FTIR, XRD and TGA-DSC. Thermal stability, anti-biodegradability, mechanical property and surface hydrophobicity of the composites with different cross-linking extents and drug loading were systematically investigated. SEM images demonstrated the honeycomb structural cells of cross-linked gelatin networks and this ensured drug entrapment. The drug release mechanism was dominated by a combined effect of diffusion and degradation, and the release rate decreased with cross-linking degree increased. The developed drug delivery system had profound significance in improving pesticide effect and bioavailability of drugs. Copyright © 2017. Published by Elsevier B.V.

Thermally reversible gels based on acryloyl- L-proline methyl ester as drug delivery systems

NASA Astrophysics Data System (ADS)

Martellini, Flavia; Higa, Olga Z.; Takacs, Erzsebet; Safranj, Agneza; Yoshida, Masaru; Katakai, Ryoichi; Carenza, Mario

1999-06-01

Thermally reversible hydrogels were synthesized by radiation-induced copolymerization of acryloyl- L-proline methyl ester with hydrophilic or hydrophobic monomers. The swelling behaviour was found to be affected by a proper balance of the latter. In particular, the transition temperature of the different hydrogels shifted to higher or lower values depending on the presence of hydrophilic or hydrophobic moieties in the polymer chain, respectively. Acetaminophen, an analgesic and antipyretic drug, was entrapped into some hydrogels and a wide range of release rates was obtained according to the nature of the comonomers. A novel thermoresponsive hydrogel was also prepared by radiation polymerization of acryloyl- L-proline methyl ester in the presence of 4-acryloyloxy acetanilide, an acrylic derivative of acetaminophen. Again, the swelling curves showed an inverse function of temperature. It was shown that with this hydrogel bearing the drug covalently attached to the polymer backbone, the hydrolysis process was the rate-determining process of the drug release.

Electrochemical preparation of polyaniline-polypyrrole solid-phase microextraction coating and its application in the GC determination of several esters.

PubMed

Zhao, Shasha; Wu, Mian; Zhao, Faqiong; Zeng, Baizhao

2013-12-15

A novel polyaniline-polypyrrole (PANI-PPY) composite film coated stainless steel wire was prepared by cyclic voltammetry. Firstly, PANI was electrodeposited on a stainless steel wire from a solution containing 0.1 M aniline and 1M HNO3, after the PANI coating was dried in air PPY was electrodeposited on it from a solution containing 0.1 M pyrrole and 0.1 M p-methylbenzene sulfonic acid. The resulting PANI-PPY fiber showed reticulate structure and had large specific surface area. When it was used for the headspace solid-phase microextraction of several esters (i.e. methyl anthranilate, ethyl-o-aminobenzoate, dimethyl phthalate, methyl laurate, and diethyl phthalate), followed by gas chromatographic determination, it presented higher extraction capability in comparison with PPY and PANI coatings. Under the optimized conditions, the linear ranges were 0.07-300 μg L(-1) and the detection limits were 0.05-0.38 μg L(-1) for different esters. The PANI-PPY fiber also showed high durability, after being used for about 160 times its extraction capacity only changed a little. The proposed method was successfully applied to the determination of these esters in real samples and the recoveries were 90-102%. © 2013 Elsevier B.V. All rights reserved.

40 CFR 180.960 - Polymers; exemptions from the requirement of a tolerance.

Code of Federal Regulations, 2012 CFR

2012-07-01

...-hydroxypoly (oxypropylene) and/or poly (oxyethylene) polymers where the alkyl chain contains a minimum of six...) block copolymer; the minimum poly(oxypropylene) content is 27 moles and the minimum molecular weight (in... weight (in amu), 900,000 62386-95-2 Monophosphate ester of the block copolymer α-hydro-ω-hydroxypoly...

40 CFR 180.960 - Polymers; exemptions from the requirement of a tolerance.

Code of Federal Regulations, 2013 CFR

2013-07-01

...-hydroxypoly (oxypropylene) and/or poly (oxyethylene) polymers where the alkyl chain contains a minimum of six... (oxypropylene) poly(oxyethylene) block copolymer; the minimum poly(oxypropylene) content is 27 moles and the... number average molecular weight (in amu), 900,000 62386-95-2 Monophosphate ester of the block copolymer α...

Evaluation of polymeric gene delivery nanoparticles by nanoparticle tracking analysis and high-throughput flow cytometry.

PubMed

Shmueli, Ron B; Bhise, Nupura S; Green, Jordan J

2013-03-01

Non-viral gene delivery using polymeric nanoparticles has emerged as an attractive approach for gene therapy to treat genetic diseases(1) and as a technology for regenerative medicine(2). Unlike viruses, which have significant safety issues, polymeric nanoparticles can be designed to be non-toxic, non-immunogenic, non-mutagenic, easier to synthesize, chemically versatile, capable of carrying larger nucleic acid cargo and biodegradable and/or environmentally responsive. Cationic polymers self-assemble with negatively charged DNA via electrostatic interaction to form complexes on the order of 100 nm that are commonly termed polymeric nanoparticles. Examples of biomaterials used to form nanoscale polycationic gene delivery nanoparticles include polylysine, polyphosphoesters, poly(amidoamines)s and polyethylenimine (PEI), which is a non-degradable off-the-shelf cationic polymer commonly used for nucleic acid delivery(1,3) . Poly(beta-amino ester)s (PBAEs) are a newer class of cationic polymers(4) that are hydrolytically degradable(5,6) and have been shown to be effective at gene delivery to hard-to-transfect cell types such as human retinal endothelial cells (HRECs)(7), mouse mammary epithelial cells(8), human brain cancer cells(9) and macrovascular (human umbilical vein, HUVECs) endothelial cells(10). A new protocol to characterize polymeric nanoparticles utilizing nanoparticle tracking analysis (NTA) is described. In this approach, both the particle size distribution and the distribution of the number of plasmids per particle are obtained(11). In addition, a high-throughput 96-well plate transfection assay for rapid screening of the transfection efficacy of polymeric nanoparticles is presented. In this protocol, poly(beta-amino ester)s (PBAEs) are used as model polymers and human retinal endothelial cells (HRECs) are used as model human cells. This protocol can be easily adapted to evaluate any polymeric nanoparticle and any cell type of interest in a multi-well plate format.

Synthetic Polymers as Gasoline Thickening Agents

DTIC Science & Technology

1944-10-02

Polyvinyl Ethers —---- 71 2. Vistanex and Synthetic Rubbers — 73 3. Ethyl Cellulose 7* a. Solubility Studies 75 b. Gel Preparation — 75 c...Surveillance Tests —- 77 d. Static Firing Tests 78 e. Ethyl Cellulose as a Methacrylate Extender 78 f. Modification of Ethyl Cellulose 78 4...Miscellaneous Polymers 79 5. Emulsions 81 6. Pactices 81 B. Preparation of Polymers not nov in Commercial Production— ---——--— 81 1. Cellulose Esters

Nonchemically amplified resists for deep-UV lithography

NASA Astrophysics Data System (ADS)

Ganesan, Ramakrishnan; Kim, Sumin; Youn, Seul Ki; Cho, Youngook; Yun, Jei-Moon; Kim, Jin-Baek

2007-03-01

A novel monomer containing a diazoketo functional group was designed and synthesized. Polymers were synthesized using the diazoketo-functionalized monomer and their physical properties were evaluated. The polymers were synthesized by radical copolymerization of cholic acid 3-diazo-3-ethoxycarbonyl-2-oxo-propyl ester methacrylate, methyl methacrylate, and γ-butyrolacton-2-yl methacrylate. These polymers showed 0.7 μm line and space patterns using a mercury-xenon lamp in a contact printing mode.

Highly efficient non-biofouling coating of zwitterionic polymers: poly((3-(methacryloylamino)propyl)-dimethyl(3-sulfopropyl)ammonium hydroxide).

PubMed

Cho, Woo Kyung; Kong, Bokyung; Choi, Insung S

2007-05-08

This work describes the formation of highly efficient non-biofouling polymeric thin films of poly((3-(methacryloylamino)propyl)-dimethyl(3-sulfopropyl)ammonium hydroxide), (poly(MPDSAH)). The poly(MPDSAH) films were generated from the self-assembled monolayers terminating in an initiator of atom transfer radical polymerization (ATRP) by the surface-initiated ATRP of MPDSAH. The poly(MPDSAH) films on a gold surface were characterized by ellipsometry, FT-IR spectroscopy, contact angle goniometery, and X-ray photoelectron spectroscopy. The copper complexes and unpolymerized monomers trapped inside the polymer brushes were completely washed out by soaking the poly(MPDSAH)-coated substrate in water at 40 degrees C for 4 days. The amount of proteins nonspecifically adsorbed onto the poly(MPDSAH) films was evaluated by surface plasmon resonance spectroscopy: the adsorption of proteins was <0.6 ng/cm(2) on the surfaces for all the model proteins. The ability of the poly(MPDSAH) films to resist the nonspecific adsorption of proteins was comparable to that of the best known systems.

Determination of phthalates released from paper packaging materials by solid-phase extraction-high-performance liquid chromatography.

PubMed

Gao, Xin; Yang, Bofeng; Tang, Zhixu; Luo, Xin; Wang, Fengmei; Xu, Hui; Cai, Xue

2014-01-01

A solid phase extraction (SPE) high-performance liquid chromatography (HPLC) method was developed for the simultaneous determination of 10 phthalic acid esters (dimethyl phthalate, diethyl phthalate, dipropyl phthalate, benzylbutyl phthalate, diisobutyl phthalate, dicyclohexyl phthalate, diamyl phthalate, di-n-hexyl phthalate, di-n-octyl phthalate and di-2-ethylhexyl phthalate) released from food paper packaging materials. The use of distilled water, 3% acetic acid (w/v), 10% ethanol (v/v) and 95% ethanol (v/v) instead of the different types of food simulated the migration of 10 phthalic acid esters from food paper packaging materials; the phthalic acid esters in four food simulants were enriched and purified by a C18 SPE column and nitrogen blowing, and quantified by HPLC with a diode array detector. The chromatographic conditions and extraction conditions were optimized and all 10 of the phthalate acid esters had a maximum absorbance at 224 nm. The method showed limitations of detection in the range of 6.0-23.8 ng/mL the correlation coefficients were greater than 0.9999 in all cases, recovery values ranged between 71.27 and 106.97% at spiking levels of 30, 60 and 90 ng/mL and relative standard deviation values ranged from 0.86 to 8.00%. The method was considered to be simple, fast and reliable for a study on the migration of these 10 phthalic acid esters from food paper packaging materials into food.

Analyzing the flavor compounds in Chinese traditional fermented shrimp pastes by HS-SPME-GC/MS and electronic nose

NASA Astrophysics Data System (ADS)

Fan, Yan; Yin, Li'ang; Xue, Yong; Li, Zhaojie; Hou, Hu; Xue, Changhu

2017-04-01

Shrimp paste is a type of condiments with high nutritional value. However, the flavors of shrimp paste, particularly the non-uniformity flavors, have limited its application in food processing. In order to identify the characteristic flavor compounds in Chinese traditional shrimp pastes, five kinds of typical commercial products were evaluated in this study. The differences in the volatile composition of the five products were investigated. Solid phase micro-extraction method was employed to extract the volatile compounds. GC-MS and electronic nose were applied to identify the compounds, and the data were analyzed using principal component analysis (PCA). A total of 62 volatile compounds were identified, including 8 alcohols, 7 aldehydes, 3 ketones, 7 ethers, 7 acids, 3 esters, 6 hydrocarbons, 12 pyrazines, 2 phenols, and 7 other compounds. The typical volatile compounds contributing to the flavor of shrimp paste were found as follows: dimethyl disulfide, dimethyl tetrasulfide, dimethyl trisulfide, 2, 3, 5-trimethyl-6-ethyl pyrazine, ethyl-2, 5-dimethyl-pyrazine, phenol and indole. Propanoic acid, butanoic acid, furans, and 2-hydroxy-3-pentanone caused unpleasant odors, such as pungent and rancid odors. Principal component analysis showed that the content of volatile compounds varied depending on the processing conditions and shrimp species. These results indicated that the combinations of multiple analysis and identification methods could make up the limitations of a single method, enhance the accuracy of identification, and provide useful information for sensory research and product development.

Application of AlkBGT and AlkL from Pseudomonas putida GPo1 for Selective Alkyl Ester ω-Oxyfunctionalization in Escherichia coli

PubMed Central

Eggink, Gerrit; Weusthuis, Ruud A.

2016-01-01

ABSTRACT The enzyme system AlkBGT from Pseudomonas putida GPo1 can efficiently ω-functionalize fatty acid methyl esters. Outer membrane protein AlkL boosts this ω-functionalization. In this report, it is shown that whole cells of Escherichia coli expressing the AlkBGT system can also ω-oxidize ethyl nonanoate (NAEE). Coexpression of AlkBGT and AlkL resulted in 1.7-fold-higher ω-oxidation activity on NAEE. With this strain, initial activity on NAEE was 70 U/g (dry weight) of cells (gcdw), 67% of the initial activity on methyl nonanoate. In time-lapse conversions with 5 mM NAEE the main product was 9-hydroxy NAEE (3.6 mM), but also 9-oxo NAEE (0.1 mM) and 9-carboxy NAEE (0.6 mM) were formed. AlkBGT also ω-oxidized ethyl, propyl, and butyl esters of fatty acids ranging from C6 to C10. Increasing the length of the alkyl chain improved the ω-oxidation activity of AlkBGT on esters of C6 and C7 fatty acids. From these esters, application of butyl hexanoate resulted in the highest ω-oxidation activity, 82 U/gcdw. Coexpression of AlkL only had a positive effect on ω-functionalization of substrates with a total length of C11 or longer. These findings indicate that AlkBGT(L) can be applied as a biocatalyst for ω-functionalization of ethyl, propyl, and butyl esters of medium-chain fatty acids. IMPORTANCE Fatty acid esters are promising renewable starting materials for the production of ω-hydroxy fatty acid esters (ω-HFAEs). ω-HFAEs can be used to produce sustainable polymers. Chemical conversion of the fatty acid esters to ω-HFAEs is challenging, as it generates by-products and needs harsh reaction conditions. Biocatalytic production is a promising alternative. In this study, biocatalytic conversion of fatty acid esters toward ω-HFAEs was investigated using whole cells. This was achieved with recombinant Escherichia coli cells that produce the AlkBGT enzymes. These enzymes can produce ω-HFAEs from a wide variety of fatty acid esters. Medium-chain-length acids (C6 to C10) esterified with ethanol, propanol, or butanol were applied. This is a promising production platform for polymer building blocks that uses renewable substrates and mild reaction conditions. PMID:27084021

Dimethyl ester of bilirubin exhibits anti-inflammatory activity through inhibition of secretory phospholipase A2, lipoxygenase and cyclooxygenase.

PubMed

Joshi, Vikram; Umashankara, M; Ramakrishnan, Chandrasekaran; Nanjaraj Urs, Ankanahalli N; Suvilesh, Kanve Nagaraj; Velmurugan, Devadasan; Rangappa, Kanchugarakoppal S; Vishwanath, Bannikuppe Sannanaik

2016-05-15

Overproduction of arachidonic acid (AA) mediated by secretory phospholipase A2 group IIA (sPLA2IIA) is a hallmark of many inflammatory disorders. AA is subsequently converted into pro-inflammatory eicosanoids through 5-lipoxygenase (5-LOX) and cyclooxygenase-1/2 (COX-1/2) activities. Hence, inhibition of sPLA2IIA, 5-LOX and COX-1/2 activities is critical in regulating inflammation. We have previously reported unconjugated bilirubin (UCB), an endogenous antioxidant, as sPLA2IIA inhibitor. However, lipophilic UCB gets conjugated in liver with glucuronic acid into hydrophilic conjugated bilirubin (CB). Since hydrophobicity is pre-requisite for sPLA2IIA inhibition, conjugation reduces the efficacy of UCB. In this regard, UCB was chemically modified and derivatives were evaluated for sPLA2IIA, 5-LOX and COX-1/2 inhibition. Among the derivatives, BD1 (dimethyl ester of bilirubin) exhibited ∼ 3 fold greater inhibitory potency towards sPLA2IIA compared to UCB. Both UCB and BD1 inhibited human 5-LOX and COX-2 activities; however only BD1 inhibited AA induced platelet aggregation. Molecular docking studies demonstrated BD1 as better inhibitor of aforesaid enzymes than UCB and other endogenous antioxidants. These data suggest that BD1 exhibits strong anti-inflammatory activity through inhibition of AA cascade enzymes which is of great therapeutic importance. Copyright © 2016 Elsevier Inc. All rights reserved.

High temperature lithium cells with solid polymer electrolytes

DOEpatents

Yang, Jin; Eitouni, Hany Basam; Singh, Mohit

2017-03-07

Electrochemical cells that use electrolytes made from new polymer compositions based on poly(2,6-dimethyl-1,4-phenylene oxide) and other high-softening-temperature polymers are disclosed. These materials have a microphase domain structure that has an ionically-conductive phase and a phase with good mechanical strength and a high softening temperature. In one arrangement, the structural block has a softening temperature of about 210.degree. C. These materials can be made with either homopolymers or with block copolymers. Such electrochemical cells can operate safely at higher temperatures than have been possible before, especially in lithium cells. The ionic conductivity of the electrolytes increases with increasing temperature.

Membrane separation of ionic liquid solutions

DOEpatents

Campos, Daniel; Feiring, Andrew Edward; Majumdar, Sudipto; Nemser, Stuart

2015-09-01

A membrane separation process using a highly fluorinated polymer membrane that selectively permeates water of an aqueous ionic liquid solution to provide dry ionic liquid. Preferably the polymer is a polymer that includes polymerized perfluoro-2,2-dimethyl-1,3-dioxole (PDD). The process is also capable of removing small molecular compounds such as organic solvents that can be present in the solution. This membrane separation process is suitable for drying the aqueous ionic liquid byproduct from precipitating solutions of biomass dissolved in ionic liquid, and is thus instrumental to providing usable lignocellulosic products for energy consumption and other industrial uses in an environmentally benign manner.

78 FR 70878 - Octadecanoic Acid, 12-Hydroxy-, Homopolymer, Ester With 2-Methyloxirane Polymer With Oxirane...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-27

... a finite tolerance is not necessary to ensure that there is a reasonable certainty that no harm will... of its composition the atomic elements carbon, hydrogen, and oxygen. 3. The polymer does not contain as an integral part of its composition, except as impurities, any element other than those listed in...

75 FR 71556 - Polyoxyalkylated Glycerol Fatty Acid Esters; Tolerance Exemption

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-24

... a finite tolerance is not necessary to ensure that there is a reasonable certainty that no harm will... polymer does contain as an integral part of its composition the atomic elements carbon, hydrogen, and... element other than those listed in 40 CFR 723.250(d)(2)(ii). 4. The polymer is neither designed nor can it...

75 FR 52269 - Acetic Acid Ethenyl Ester, Polymer With Oxirane; Tolerance Exemption

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-25

... result of pesticide use in residential settings. If EPA is able to determine that a finite tolerance is... contain as an integral part of its composition the atomic elements carbon, hydrogen, and oxygen. 3. The polymer does not contain as an integral part of its composition, except as impurities, any element other...

Cyanate Ester Resin Modified with Nano-particles for Inclusion in Continuous Fiber Reinforced Composites

DTIC Science & Technology

2011-02-25

custom built rotating oven, to prevent settling during cure. The filler content in the test specimen are verified by thermogravimetric analysis (TGA...using a Shimadzu SA-CP3 centrifugal particle size analyzer. The moisture absorption of the nanoparticles was studied using a Q50 thermogravimetric ...low viscosity bisphenol E cyanate ester resin (BECy) resin reinforced with macro scale carbon fibers and negative CTE nanoparticles . Polymer

Nanoporous Cyanate Ester Resins: Structure-Gas Transport Property Relationships

NASA Astrophysics Data System (ADS)

Gusakova, Kristina; Fainleib, Alexander; Espuche, Eliane; Grigoryeva, Olga; Starostenko, Olga; Gouanve, Fabrice; Boiteux, Gisèle; Saiter, Jean-Marc; Grande, Daniel

2017-04-01

This contribution addresses the relationships between the structure and gas transport properties of nanoporous thermostable cyanate ester resins (CERs) derived from polycyclotrimerization of 1,1'-bis(4-cyanatophenyl)ethane in the presence of 30 or 50 wt% of inert high-boiling temperature porogens (i.e., dimethyl- or dibutyl phthalates), followed by their quantitative removal. The nanopores in the films obtained were generated via a chemically induced phase separation route with further porogen extraction from the densely crosslinked CERs. To ensure a total desorption of the porogen moieties from the networks, an additional short-term thermal annealing at 250 °C was performed. The structure and morphology of such nanoporous CER-based films were investigated by FTIR and SEM techniques, respectively. Further, the gas transport properties of CER films were analyzed after the different processing steps, and relationships between the material structure and the main gas transport parameters were established.

Development of a drug delivery system for the treatment of periodontal disease based on bioerodible poly(ortho esters).

PubMed

Roskos, K V; Fritzinger, B K; Rao, S S; Armitage, G C; Heller, J

1995-03-01

Poly(ortho esters) prepared by the condensation of 1,2,6-hexanetriol and an alkyl orthoacetate are viscous, semisolid materials at room temperature that can be injected using a blunt needle. When tetracycline was incorporated into these materials, complete release occurred within about 24 hours, but when small amounts of Mg(OH)2 were incorporated into the polymer release could be extended to many weeks, and a loading of 0.5 wt% resulted in sustained release of about 10 days. When adhesion was tested using bovine teeth, cohesive failure of the pure polymer occurred at a force of about 392 mN cm-2 and cohesive failure of a polymer incorporating 10 wt% tetracycline and 1 wt% (Mg(OH)2 occurred at about 118 mN cm-2. The combination of injectability, dentoadhesiveness and ability to control accurately the release of incorporated antibiotics makes these materials promising candidates for bioerodible delivery systems useful in the treatment of periodontitis. Toxicological studies are currently in progress.

Chemical aspects of silicon-containing bilayer resists

NASA Astrophysics Data System (ADS)

Boardman, Larry D.; Kessel, Carl R.; Rhyner, Steven J.

1999-06-01

We have prepare several novel silicon-containing polymers containing both low Ea and high Ea protecting groups, and we have evaluated these materials at both 193 nm. Low Ea acetal-containing polymers were prepared by reacting poly(4-vinylphenol) with novel silyl enol ethers. The ease of protecting group cleavage in these materials is manifested in the immediate formation of a strong latent image after exposure. High Ea polymers were prepared by introducing tertiary esters which contain the tris(trimethylsilyl)silyl group, and both methacrylate copolymers and norbornene-maleic anhydride copolymers containing this group have been synthesized. Both of these materials show good oxygen plasma etch resistance, with the latter demonstrating superior adhesion to poly(4- vinylphenol) planarizing layers. The tris(trimethylsilyl)silyl group imparts a high degree of hydrophobicity to coatings of many of these materials. Acid- catalyzed deprotection of these tertiary esters affords the corresponding carboxylic acids and 1-silyl-3-methylbutenes, and the liberation of these olefins is significantly faster than the loss of isobutylene from the tert-butyl analogs.

Chemoenzymatic Synthesis and Chemical Recycling of Poly(ester-urethane)s

PubMed Central

Hayashi, Hiroto; Yanagishita, Yoshio; Matsumura, Shuichi

2011-01-01

Novel poly(ester-urethane)s were prepared by a synthetic route using a lipase that avoids the use of hazardous diisocyanate. The urethane linkage was formed by the reaction of phenyl carbonate with amino acids and amino alcohols that produced urethane-containing diacids and hydroxy acids, respectively. The urethane diacid underwent polymerization with polyethylene glycol and α,ω-alkanediols and also the urethane-containing hydroxy acid monomer was polymerized by the lipase to produce high-molecular-weight poly(ester-urethane)s. The periodic introduction of ester linkages into the polyurethane chain by the lipase-catalyzed polymerization afforded chemically recyclable points. They were readily depolymerized in the presence of lipase into cyclic oligomers, which were readily repolymerized in the presence of the same enzyme. Due to the symmetrical structure of the polymers, poly(ester-urethane)s synthesized in this study showed higher Tm, Young’s modulus and tensile strength values. PMID:22016604

Method Of Signal Amplification In Multi-Chromophore Luminescence Sensors

DOEpatents

Levitsky, Igor A.; Krivoshlykov, Sergei G.

2004-02-03

A fluorescence-based method for highly sensitive and selective detection of analyte molecules is proposed. The method employs the energy transfer between two or more fluorescent chromophores in a carefully selected polymer matrix. In one preferred embodiment, signal amplification has been achieved in the fluorescent sensing of dimethyl methylphosphonate (DMMP) using two dyes, 3-aminofluoranthene (AM) and Nile Red (NR), in a hydrogen bond acidic polymer matrix. The selected polymer matrix quenches the fluorescence of both dyes and shifts dye emission and absorption spectra relative to more inert matrices. Upon DMMP sorption, the AM fluorescence shifts to the red at the same time the NR absorption shifts to the blue, resulting in better band overlap and increased energy transfer between chromophores. In another preferred embodiment, the sensitive material is incorporated into an optical fiber system enabling efficient excitation of the dye and collecting the fluorescent signal form the sensitive material on the remote end of the system. The proposed method can be applied to multichromophore luminescence sensor systems incorporating N-chromophores leading to N-fold signal amplification and improved selectivity. The method can be used in all applications where highly sensitive detection of basic gases, such as dimethyl methylphosphonate (DMMP), Sarin, Soman and other chemical warfare agents having basic properties, is required, including environmental monitoring, chemical industry and medicine.

Wide bandgap OPV polymers based on pyridinonedithiophene unit with efficiency >5%

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schneider, Alexander M.; Lu, Luyao; Manley, Eric F.

2015-06-04

We report the properties of a new series of wide band gap photovoltaic polymers based on the N-alkyl 2-pyridone dithiophene (PDT) unit. These polymers are effective bulk heterojunction solar cell materials when blended with phenyl-C 71-butyric acid methyl ester (PC 71BM). They achieve power conversion efficiencies (up to 5.33%) high for polymers having such large bandgaps, ca. 2.0 eV (optical) and 2.5 eV (electrochemical). As a result, grazing incidence wide-angle X-ray scattering (GIWAXS) reveals strong correlations between π–π stacking distance and regularity, polymer backbone planarity, optical absorption maximum energy, and photovoltaic efficiency.

An Examination of the Feasibility of Administering Prophylactic Pyridostigmine by the Percutaneous Route.

DTIC Science & Technology

1981-01-01

skin; possibly the compound is bound to anionic polymers. These results do not allow appendageal diffusion (through hair follicles) to be...R.M. "Carbamylation and Decarbamylation of Acetylcholinesterase: Effect of Choline , 3,3-dimethyl-l-butanol and some Allosteric Effectors". J. Neurocnem

Controlled delivery of metoclopramide using an injectable semi-solid poly(ortho ester) for veterinary application.

PubMed

Schwach-Abdellaoui, Khadija; Moreau, Marinette; Schneider, Marc; Boisramć, Bernard; Gurny, Robert

2002-11-06

In animal health care, current therapeutic regimens for gastrointestinal disorders require repeated oral or parenteral dosage forms of anti-emetic agents. However, fluctuations of plasma concentrations produce severe side effects. The aim of this work is to develop a subcutaneous and biodegradable controlled release system containing metoclopramide (MTC). Semi-solid poly(ortho ester)s (POE) prepared by a transesterification reaction between trimethyl orthoacetate and 1,2,6,-hexanetriol were investigated as injectable bioerodible polymers for the controlled release of MTC. MTC is present in the polymeric matrix as a solubilised form and it is released rapidly from the POE by erosion and diffusion because of its acidic character and its high hydrosolubility. If a manual injection is desired, only low molecular weight can be used. However, low molecular weight POEs release the drug rapidly. In order to extend polymer lifetime and decrease drug release rate, a sparingly water-soluble base Mg(OH)(2) was incorporated to the formulation. It was possible to produce low molecular weight POE that can be manually injected and releasing MTC over a period of several days.

In Vitro and Ex Vivo Evaluation of Novel Curcumin-Loaded Excipient for Buccal Delivery.

PubMed

Laffleur, Flavia; Schmelzle, Franziska; Ganner, Ariane; Vanicek, Stefan

2017-08-01

This study aimed to develop a mucoadhesive polymeric excipient comprising curcumin for buccal delivery. Curcumin encompasses broad range of benefits such as antioxidant, anti-inflammatory, and chemotherapeutic activity. Hyaluronic acid (HA) as polymeric excipient was modified by immobilization of thiol bearing ligands. L-Cysteine (SH) ethyl ester was covalently attached via amide bond formation between cysteine and the carboxylic moiety of hyaluronic acid. Succeeded synthesis was proved by H-NMR and IR spectra. The obtained thiolated polymer hyaluronic acid ethyl ester (HA-SH) was evaluated in terms of stability, safety, mucoadhesiveness, drug release, and permeation-enhancing properties. HA-SH showed 2.75-fold higher swelling capacity over time in comparison to unmodified polymer. Furthermore, mucoadhesion increased 3.4-fold in case of HA-SH and drug release was increased 1.6-fold versus HA control, respectively. Curcumin-loaded HA-SH exhibits a 4.4-fold higher permeation compared with respective HA. Taking these outcomes in consideration, novel curcumin-loaded excipient, namely thiolated hyaluronic acid ethyl ester appears as promising tool for pharyngeal diseases.

One-pot synthesis of polyunsaturated fatty acid amides with anti-proliferative properties.

PubMed

Tremblay, Hugo; St-Georges, Catherine; Legault, Marc-André; Morin, Caroline; Fortin, Samuel; Marsault, Eric

2014-12-15

A one-pot environmentally friendly transamidation of ω-3 fatty acid ethyl esters to amides and mono- or diacylglycerols was investigated via the use of a polymer-supported lipase. The method was used to synthesize a library of fatty acid monoglyceryl esters and amides. These new derivatives were found to have potent growth inhibition effects against A549 lung cancer cells. Copyright © 2014 Elsevier Ltd. All rights reserved.

Methods of making alkyl esters

DOEpatents

Elliott, Brian

2010-08-03

A method comprising contacting an alcohol, a feed comprising one or more glycerides and equal to or greater than 2 wt % of one or more free fatty acids, and a solid acid catalyst, a nanostructured polymer catalyst, or a sulfated zirconia catalyst in one or more reactors, and recovering from the one or more reactors an effluent comprising equal to or greater than about 75 wt % alkyl ester and equal to or less than about 5 wt % glyceride.

Water Uptake Vs. Density and Conversion in Silicon Containing Cyanate Esters (Briefing Charts)

DTIC Science & Technology

2014-12-17

known that cyanate ester networks decrease in density as conversion increases, and that moisture uptake increases as conversion increases at...Charts 3. DATES COVERED (From - To) Dec 2014- Dec 2014 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER In-House Water Uptake Vs. Density and...Polymers and Composites, San Diego, CA, 15 December, 2014. PA#14581 14. ABSTRACT A study was conducted which explored the density, percent water uptake by

76 FR 41135 - 2-Propenoic acid, 2-methyl-, phenylmethyl ester, polymer with 2-propenoic acid and sodium 2...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-13

... a finite tolerance is not necessary to ensure that there is a reasonable certainty that no harm will... integral part of its composition the atomic elements carbon, hydrogen, and oxygen. 3. The polymer does not contain as an integral part of its composition, except as impurities, any element other than those listed...

Identification of Osteoconductive and Biodegradable Polymers from a Combinatorial Polymer Library

PubMed Central

Brey, Darren M.; Chung, Cindy; Hankenson, Kurt D.; Garino, Jonathon P.; Burdick, Jason A.

2012-01-01

Combinatorial polymer syntheses are now being utilized to create libraries of materials with potential utility for a wide variety of biomedical applications. We recently developed a library of photopolymerizable and biodegradable poly(β-amino ester)s (PBAEs) that possessed a range of tunable properties. In this work, the PBAE library was assessed for candidate materials that met design criteria (e.g., physical properties such as degradation and mechanical strength and in vitro cell viability and osteoconductive behavior) for scaffolding in mineralized tissue repair. The most promising candidate, A6, was then processed into 3-dimensional porous scaffolds and implanted subcutaneously and only presented a mild inflammatory response. The scaffolds were then implanted intramuscularly and into a critically-sized cranial defect either alone or loaded with bone morphogenetic protein-2 (BMP-2). The samples in both locations displayed mineralized tissue formation in the presence of BMP-2, as evident through radiographs, micro-computed tomography, and histology, while samples without BMP-2 showed minimal or no mineralized tissue. These results illustrate a process to identify a candidate scaffolding material from a combinatorial polymer library, and specifically for the identification of an osteoconductive scaffold with osteoinductive properties via the inclusion of a growth factor. PMID:20198696

Next Generation Hemostatic Materials Based on NHS-Ester Functionalized Poly(2-oxazoline)s.

PubMed

Boerman, Marcel A; Roozen, Edwin; Sánchez-Fernández, María José; Keereweer, Abraham R; Félix Lanao, Rosa P; Bender, Johan C M E; Hoogenboom, Richard; Leeuwenburgh, Sander C; Jansen, John A; Van Goor, Harry; Van Hest, Jan C M

2017-08-14

In order to prevent hemorrhage during surgical procedures, a wide range of hemostatic agents have been developed. However, their efficacy is variable; hemostatic devices that use bioactive components to accelerate coagulation are dependent on natural sources, which limits reproducibility. Hybrid devices in which chain-end reactive poly(ethylene glycol) is employed as active component sometimes suffer from irregular cross-linking and dissolution of the polar PEG when blood flow is substantial. Herein, we describe a synthetic, nonbioactive hemostatic product by coating N-hydroxysuccinimide ester (NHS)-functional poly(2-oxazoline)s (POx-NHS) onto gelatin patches, which acts by formation of covalent cross-links between polymer, host blood proteins, gelatin and tissue to seal the wound site and prevent hemorrhage during surgery. We studied different process parameters (including polymer, carrier, and coating technique) in direct comparison with clinical products (Hemopatch and Tachosil) to obtain deeper understanding of this class of hemostatic products. In this work, we successfully prove the hemostatic efficacy of POx-NHS as polymer powders and coated patches both in vitro and in vivo against Hemopatch and Tachosil, demonstrating that POx-NHS are excellent candidate polymers for the development of next generation hemostatic patches.

Targeted cell adhesion on selectively micropatterned polymer arrays on a poly(dimethylsiloxane) surface.

PubMed

Tang, Linzhi; Min, Junhong; Lee, Eun-Cheol; Kim, Jong Sung; Lee, Nae Yoon

2010-02-01

Herein, we introduce the fabrication of polymer micropattern arrays on a chemically inert poly(dimethylsiloxane) (PDMS) surface and employ them for the selective adhesion of cells. To fabricate the micropattern arrays, a mercapto-ester-based photocurable adhesive was coated onto a mercaptosilane-coated PDMS surface and photopolymerized using a photomask to obtain patterned arrays at the microscale level. Robust polymer patterns, 380 microm in diameter, were successfully fabricated onto a PDMS surface, and cells were selectively targeted toward the patterned regions. Next, the performance of the cell adhesion was observed by anchoring cell adhesive linker, an RGD oligopeptide, on the surface of the mercapto-ester-based adhesive-cured layer. The successful anchoring of the RGD linker was confirmed through various surface characterizations such as water contact angle measurement, XPS analysis, FT-IR analysis, and AFM measurement. The micropatterning of a photocurable adhesive onto a PDMS surface can provide high structural rigidity, a highly-adhesive surface, and a physical pathway for selective cell adhesion, while the incorporated polymer micropattern arrays inside a PDMS microfluidic device can serve as a microfluidic platform for disease diagnoses and high-throughput drug screening.

Structure elucidation of nigricanoside A through enantioselective total synthesis† †Electronic supplementary information (ESI) available: Complete experimental details and characterization data. See DOI: 10.1039/c5sc00281h Click here for additional data file.

PubMed Central

Chen, Jie; Koswatta, Panduka; DeBergh, J. Robb; Fu, Peng; Pan, Ende

2015-01-01

Nigricanoside A was isolated from green alga, and its dimethyl ester was found to display potent cytotoxicity. Its scarcity prevented a full structure elucidation, leaving total synthesis as the only means to determine its relative and absolute stereochemistry and to explore its biological activity. Here we assign the stereochemistry of the natural product through enantioselective total synthesis and provide initial studies of its cytotoxicity. PMID:26877863

Cholinesterase inhibition in meadow voles Microtus pennsylvanicus following field applications of Orthene

USGS Publications Warehouse

Jett, David A.

1986-01-01

Brain acetylcholinesterase activity in field-caught meadow voles (Microtus pennsylvanicus) was depressed after a field-spray of Orthene (acephate: acetylphosphoramidothioic acid O,S-dimethyl ester) by as much as 32% in 1982 and 38% in 1983. Short-term recovery was demonstrated and occurred in a time-dependent fashion in 1982. Plasma cholinesterase levels were move variable but also were depressed. Residues were detected in vegetation samples and in the gastrointestinal tracts of exposed voles. Residues in vegetation were diluted or absent 7 to 8 d following the treatment.

Preparation and electrochemical characterization of polymer electrolytes based on electrospun poly(vinylidene fluoride- co-hexafluoropropylene)/polyacrylonitrile blend/composite membranes for lithium batteries

NASA Astrophysics Data System (ADS)

Raghavan, Prasanth; Zhao, Xiaohui; Shin, Chorong; Baek, Dong-Ho; Choi, Jae-Won; Manuel, James; Heo, Min-Yeong; Ahn, Jou-Hyeon; Nah, Changwoon

Apart from PEO based solid polymer electrolytes, tailor-made gel polymer electrolytes based on blend/composite membranes of poly(vinylidene fluoride- co-hexafluoropropylene) and polyacrylonitrile are prepared by electrospinning using 14 wt% polymer solution in dimethylformamide. The membranes show uniform morphology with an average fiber diameter of 320-490 nm, high porosity and electrolyte uptake. Polymer electrolytes are prepared by soaking the electrospun membranes in 1 M lithium hexafluorophosphate in ethylene carbonate/dimethyl carbonate. Temperature dependent ionic conductivity and their electrochemical performance are studied. The blend/composite polymer electrolytes show good ionic conductivity in the range of 10 -3 S cm -1 at ambient temperature and good electrochemical performance. All the Polymer electrolytes show an anodic stability >4.6 V with stable interfacial resistance with storage time. The prototype cell shows good charge-discharge properties and stable cycle performance with comparable capacity fade compared to liquid electrolyte under the test conditions.

Optoelectronic and Photovoltaic Performances of Pyridine Based Monomer and Polymer Capped ZnO Dye-Sensitized Solar Cells.

PubMed

Singh, Satbir; Raj, Tilak; Singh, Amarpal; Kaur, Navneet

2016-06-01

The present research work describes the comparative analysis and performance characteristics of 4-pyridine based monomer and polymer capped ZnO dye-sensitized solar cells. The N, N-dimethyl-N4-((pyridine-4yl)methylene) propaneamine (4,monomer) and polyamine-4-pyridyl Schiff base (5, polymer) dyes were synthesized through one step condensation reaction between 4-pyridinecarboxaldehyde 1 and N, N-dimethylpropylamine 2/polyamine 3. Products obtained N, N-dimethyl-N4-((pyridine-4yl)methylene)propaneamine (4) and polyamine-4-pyridyl Schiff base (5) were purified and characterized using 1H, 13C NMR, mass, IR and CHN spectroscopy. Both the dyes 4 and 5 were further coated over ZnO nanoparticles and characterized using SEM, DLS and XRD analysis. Absorption profile and emission profile was monitored using fluorescence and UV-Vis absorption spectroscopy. A thick layer of these inbuilt dye linked ZnO nanoparticles of dyes (4) and (5) was pasted on one of the conductive side of ITO glass followed with a liquid electrolyte and counter electrode of the same conductive glass. Polyamine-4-pyridyl Schiff base polymer (5) decorated dye sensitized solar cell has shown better exciting photovoltaic properties in the form of short circuit current density (J(sc) = 6.3 mA/cm2), open circuit photo voltage (V(oc) = 0.7 V), fill factor (FF = 0.736) than monomer decorated dye sensitized solar cell. Polymer dye (5) based ZnO solar cell has shown a maximum solar power to electrical conversion efficiency of 3.25%, which is enhanced by 2.16% in case of monomer dye based ZnO solar cell under AM 1.5 sun illuminations.

Study on characteristics of PVDF/nano-clay composite polymer electrolyte using PVP as pore-forming agent

NASA Astrophysics Data System (ADS)

Dyartanti, Endah R.; Purwanto, Agus; Widiasa, I. Nyoman; Susanto, Heru

2016-02-01

Polyvinylidene fluoride (PVDF) based polymer electrolytes have a high dielectric constant, which can assist in greater ionization of lithium salts. The main advantages of PVDF are its durability in long battery operation and its ability to be a good ion conductor. However, the limitation of this polymer is its crystalline molecular structure. Dispersing nano-particles in the polymer matrix may improve the characteristics of the PVDF polymer. This paper aims to investigate the impact of nano-clay addition on the characteristics of PVDF polymer to be used as a polymer electrolyte membrane. In addition, the effect of poly(vinyl pyrrolidone) (PVP) is also investigated. The membrane was prepared by phase separation method whereas the polymer electrolyte membranes was prepared by immersing into 1 M lithium hexafluorophosphate (LiPF6) in ethylene carbonate/dimethyl carbonate (EC/DMC) electrolytes for 1 h. The membranes were characterized by scanning electron microscope (SEM), porosity and electrolyte uptake and performance in battery cell. The results showed that both nano-clay and PVP have significant impacts on the improvement of PVDF membranes to be used as polymer electrolyte.

Simultaneous determination of 22 phthalate esters in polystyrene food-contact materials by ultra performance convergence chromatography with tandem mass spectrometry.

PubMed

Fan, Ying-Li; Ma, Ming; Cui, He-Zhen; Liu, Shu; Yang, Min-Li; Hou, Xiu-Feng

2018-05-29

A method for the determination of 22 phthalate esters in polystyrene food-contact materials has been established using ultra performance convergence chromatography with tandem mass spectrometry. In this method, 22 phthalate esters were analyzed in less than 3.5 min on an ACQUITY Tours 1-AA column by gradient elution. The mobile phase, the compensation solvent, the flow rate of mobile phase, column temperature and automatic back pressure regulator pressure were optimized, respectively. There was a good linearity of 20 phthalate esters with a range of 0.05-10 mg/L, diisodecyl phthalate and diisononyl phthalate were 0.25-10 mg/L, and the correlation coefficients of all phthalates were higher than 0.99 and those of 16 phthalates were higher than 0.999. The limits of detection and the limits of quantification of 15 phthalates were 0.02 and 0.05 mg/kg, meanwhile diallyl phthalate, diisobutyl phthalate, dimethyl phthalate, di-n-butyl phthalate and di(2-ethylhexyl) phthalate were 0.05 and 0.10 mg/kg, diisodecyl phthalate and diisononyl phthalate were 0.10 and 0.25 mg/kg. The spiked recoveries were 76.26-107.76%, and the relative standard deviations were 1.78-12.10%. Results support this method as an efficient alternative to apply for the simultaneous determination of 22 phthalate esters in common polystyrene food-contact materials. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Femtosecond laser microfabrication in polymers towards memory devices and microfluidic applications

NASA Astrophysics Data System (ADS)

Deepak, K. L. N.; Venugopal Rao, S.; Narayana Rao, D.

2011-12-01

We have investigated femtosecond laser induced microstructures, gratings, and craters in four different polymers: poly methyl methacrylate (PMMA), poly dimethyl siloxane (PDMS), polystyrene (PS) and poly vinyl alcohol (PVA) using Ti:sapphire laser delivering 800 nm, 100 femtosecond (fs) pulses at 1 kHz repetition rate with a maximum pulse energy of 1 mJ. Local chemical modifications leading to the formation of optical centers and peroxide radicals which were studied using UV-Visible absorption and emission, confocal micro-Raman and Electron Spin Resonance (ESR) spectroscopic techniques.

Polymer-based adsorption medium prepared using a fragment imprinting technique for homologues of chlorinated bisphenol A produced in the environment.

PubMed

Kubo, Takuya; Hosoya, Ken; Watabe, Yoshiyuki; Ikegami, Tohru; Tanaka, Nobuo; Sano, Tomoharu; Kaya, Kunimitsu

2004-03-12

A polymer-based adsorption medium having molecular recognition ability for homologues of chlorinated bisphenol A produced in environment was prepared using a fragment imprinting technique. 2,6-Dimethyl phenol was utilized as a pseudo-template molecule and the adsorption media prepared was evaluated by high performance liquid chromatography (HPLC) and solid-phase extraction (SPE). As results, the adsorption medium showed preferable chromatographic retention and specific adsorption ability for the chlorinated bisphenol As having chlorine substituents at 3,5-positions through fragment imprinting effect.

Synthesis and characterization of new poly(ortho ester amidine) copolymers for nonviral gene delivery

PubMed Central

Tang, Rupei; Ji, Weihang; Wang, Chun

2011-01-01

A new type of pH-labile cationic polymers, poly(ortho ester amidine) (POEAmd) copolymers, has been synthesized and characterized with potential future application as gene delivery carriers. The acid-labile POEAmd copolymer was synthesized by polycondensation of a new ortho ester diamine monomer with dimethylaliphatimidates, and a non-acid-labile polyamidine (PAmd) copolymer was also synthesized for comparison using a triethylene glycol diamine monomer. Both copolymers were easily dissolved in water, and can efficiently bind and condense plasmid DNA at neutral pH, forming nano-scale polyplexes. The physico-chemical properties of the polyplexes have been studied using dynamic light scattering, gel electrophoresis, ethidium bromide exclusion, and heparin competition. The average size of the polyplexes was dependent on the amidine: phosphate (N:P) ratio of the polymers to DNA. Polyplexes containing the acid-labile POEAmd or the non-acid-labile PAmd showed similar average particle size, comparable strength of condensing DNA, and resistance to electrostatic destabilization. They also share similar metabolic toxicity to cells as measured by MTT assay. Importantly, the acid-labile polyplexes undergo accelerated polymer degradation at mildly-acid-pHs, resulting in increasing particle size and the release of intact DNA plasmid. Polyplexes from both types of polyamidines caused distinct changes in the scattering properties of Baby Hamster Kidney (BHK-21) cells, showing swelling and increasing intracellular granularity. These cellular responses are uniquely different from other cationic polymers such as polyethylenimine and point to stress-related mechanisms specific to the polyamidines. Gene transfection of BHK-21 cells was evaluated by flow cytometry. The positive yet modest transfection efficiency by the polyamidines (acid-labile and non-acid-labile alike) underscores the importance of balancing polymer degradation and DNA release with endosomal escape. Insights gained from studying such acid-labile polyamidine-based DNA carriers and their interaction with cells may contribute to improved design of practically useful gene delivery systems. PMID:21479119

The Effect of Hydrogen Bonding in Enhancing the Ionic Affinities of Immobilized Monoprotic Phosphate Ligands

DOE PAGES

Alexandratos, Spiro D.; Zhu, Xiaoping

2017-08-18

Environmental remediation requires ion-selective polymers that operate under a wide range of solution conditions. In one example, removal of trivalent and divalent metal ions from waste streams resulting from mining operations before they enter the environment requires treatment at acidic pH. The monoethyl ester phosphate ligands developed in this report operate from acidic solutions. They have been prepared on polystyrene-bound ethylene glycol, glycerol, and pentaerythritol, and it is found that intra-ligand hydrogen bonding affects their metal ion affinities. The affinity for a set of trivalent (Fe(III), Al(III), La(III), and Lu(III)) and divalent (Pb(II), Cd(II), Cu(II), and Zn(II)) ions is greatermore » than that of corresponding neutral diethyl esters and phosphonic acid. In an earlier study, hydrogen bonding was found important in determining the metal ion affinities of immobilized phosphorylated polyol diethyl ester coordinating ligands; their Fourier transform infrared (FTIR) band shifts indicated that the basicity of the phosphoryl oxygen increased by hydrogen bonding to auxiliary –OH groups on the neighboring polyol. The same mechanism is operative with the monoprotic resins along with hydrogen bonding to the P–OH acid site. This is reflected in the FTIR spectra: the neutral phosphate diethyl ester resins have the P=O band at 1265 cm -1 while the monoethyl ester resins have the band shifted to 1230 cm -1; hydrogen bonding is further indicated by the broadness of this region down to 900 cm -1. Of the polymers studied, monoprotic pentaerythritol has the highest metal ion affinities.« less

The Effect of Hydrogen Bonding in Enhancing the Ionic Affinities of Immobilized Monoprotic Phosphate Ligands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alexandratos, Spiro D.; Zhu, Xiaoping

Environmental remediation requires ion-selective polymers that operate under a wide range of solution conditions. In one example, removal of trivalent and divalent metal ions from waste streams resulting from mining operations before they enter the environment requires treatment at acidic pH. The monoethyl ester phosphate ligands developed in this report operate from acidic solutions. They have been prepared on polystyrene-bound ethylene glycol, glycerol, and pentaerythritol, and it is found that intra-ligand hydrogen bonding affects their metal ion affinities. The affinity for a set of trivalent (Fe(III), Al(III), La(III), and Lu(III)) and divalent (Pb(II), Cd(II), Cu(II), and Zn(II)) ions is greatermore » than that of corresponding neutral diethyl esters and phosphonic acid. In an earlier study, hydrogen bonding was found important in determining the metal ion affinities of immobilized phosphorylated polyol diethyl ester coordinating ligands; their Fourier transform infrared (FTIR) band shifts indicated that the basicity of the phosphoryl oxygen increased by hydrogen bonding to auxiliary –OH groups on the neighboring polyol. The same mechanism is operative with the monoprotic resins along with hydrogen bonding to the P–OH acid site. This is reflected in the FTIR spectra: the neutral phosphate diethyl ester resins have the P=O band at 1265 cm -1 while the monoethyl ester resins have the band shifted to 1230 cm -1; hydrogen bonding is further indicated by the broadness of this region down to 900 cm -1. Of the polymers studied, monoprotic pentaerythritol has the highest metal ion affinities.« less

A study of perfluorocarboxylate ester solvents for lithium ion battery electrolytes

DOE PAGES

Fears, Tyler M.; Sacci, Robert L.; Winiarz, Jeffrey G.; ...

2015-09-18

We prepared several high-purity methyl perfluorocarboxylates (>99.5% purity by mole) and investigated as potential fluorine-rich electrolyte solvents in Li-ion batteries. The most conductive electrolyte, 0.1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in dimethyl perfluoroglutarate (PF5M 2) (ionic conductivity 1.87 10 -2 mS cm -1), is investigated in Si thin-film half-cells. The solid-electrolyteinterphase (SEI) formed by the PF5M2 electrolyte is composed of similar organic and inorganic moieties and at comparable concentrations as those formed by ethylene carbonate/dimethyl carbonate electrolytes containing LiPF 6 and LiTFSI salts. But, the SEI formed by the PF5M 2 electrolyte undergoes reversible electrochemical defluorination, contributing to the reversible capacitymore » of the cell and compensating in part for capacity fade in the Si electrode. These electrolytes, though far from ideal, provide an opportunity to further develop predictions of suitable fluorinated molecules for use in battery solvents.« less

Treatment of phthalic acid esters by electrocoagulation with stainless steel electrodes using dimethyl phthalate as a model compound.

PubMed

Kabdaşli, Işik; Keleş, Asuman; Olmez-Hanci, Tuğba; Tünay, Olcay; Arslan-Alaton, Idil

2009-11-15

In this study, treatment of phthalates by electrocoagulation employing stainless steel electrodes was investigated using dimethyl phthalate (DMP) as a model compound. DMP was completely destructed within 30 min up to the high initial concentration of 100mg/L while total mineralization was also obtained within a couple of hours. The applied current density of 22.5 mA/cm(2) and electrolyte (NaCl) concentrations varying between 1000 and 1500 mg/L as chloride resulted in the highest treatment performance. The initial solution pH (2-6) had practically no effect on the process efficiency. Desorption experiments and the reaction rates obtained for DMP, COD and TOC abatements appeared to be a strong evidence of an oxidative removal mechanism. DMP removal fitted first order kinetics. COD and TOC removals began after the total DMP removal and also fitted first order kinetics. Activated sludge inhibition experiments revealed that toxicity could be significantly reduced by electrocoagulation application.

Thermoplastic polymers for improved fire safety

NASA Technical Reports Server (NTRS)

Kourtides, D. A.; Parker, J. A.; Hilado, C. J.

1976-01-01

The thermochemical and flammability characteristics of some typical thermoplastic materials currently in use and others being considered for use in aircraft interiors are described. The properties studied included (1) thermomechanical properties such as glass transition and melt temperature, (2) changes in polymer enthalpy by differential scanning calorimetry, (3) thermogravimetric analysis in anaerobic and oxidative environments, (4) oxygen index, (5) smoke evolution, (6) relative toxicity of the volatile products of pyrolysis, and (7) selected physical properties. The generic polymers that were evaluated included: acrylonitrile butadiene styrene, bisphenol A polycarbonate, 9,9 bis (4-hydroxyphenyl) fluorene polycarbonatepoly (dimethyl siloxane) block polymer, phenolphthalein bisphenol A polycarbonate, phenolphthalein polycarbonate, polyether sulfone, polyphenylene oxide, polyphenylene sulfide, polyaryl sulfone, chlorinated polyvinyl chloride homopolymer, polyvinyl fluoride, and polyvinylidene fluoride. Processing parameters, including molding characteristics of some of the advanced polymers, are described. Test results and relative ranking of some of the flammability, smoke, and toxicity properties are presented.

A High-Performance Nanocomposite Material Based on Functionalized Carbon Nanotube and Polymer for Gas Sensing Applications

NASA Astrophysics Data System (ADS)

Wang, L. C.; Tang, K. T.; Kuo, C. T.; Yang, S. R.; Sung, Yuh; Hsu, H. L.; Jehng, J. M.

2009-05-01

The aim of this study is to develop a novel chemical gas sensing nanocomposite material. The traditional use for carbon nanotube in gas sensing polymer is to increase the composite's conductivity. However, we added functionalized carbon nanotube to fill the free volume of the sensing polymer films and enhance the gas absorption/desorption response time of these nanocomposites. These sensing materials were prepared by mixing functionalized multiwalled carbon nanotubes (MWNTs) and Poly (n, n dimethylamino propylsilsequioxane) SXNR polymer. These new materials were coated on the Surface Acoustic Wave (SAW) device, which is expected to increase its sensitivity in analyzing specific classes of vapors. The proposed materials showed an enhanced sensitivity upon exposure to ethanol and dimethyl methylphosphonate (Dmmp) vapors. Additionally, the performances of our nanocomposite film are much higher than those polymers without functionalized carbon nanotubes.

Biodegradable Poly(ester urethane)urea Elastomers with Variable Amino Content for Subsequent Functionalization with Phosphorylcholine

PubMed Central

Fang, Jun; Ye, Sang-Ho; Shankarraman, Venkat; Huang, Yixian; Mo, Xiumei; Wagner, William R.

2015-01-01

While surface modification is well suited for imparting biomaterials with specific functionality for favorable cell interactions, the modification of degradable polymers would be expected to provide only temporary benefit. Bulk modification by incorporating pendant reactive groups for subsequent functionalization of biodegradable polymers would provide a more enduring approach. Towards this end, a series of biodegradable poly(ester urethane)urea elastomers with variable amino content (PEUU-NH2 polymers) were developed. Carboxylated phosphorycholine was synthesized and conjugated to the PEUU-NH2 polymers for subsequent bulk functionalization to generate PEUU-PC polymers. Synthesis was verified by 1H NMR, X-ray photoelectron spectroscopy and ATR-FTIR. The impact of amine incorporation and phosphorylcholine conjugation was shown on mechanical, thermal and degradation properties. Water absorption increased with increasing amine content, and further with PC conjugation. In wet conditions, tensile strength and initial modulus generally decreased with increasing hydrophilicity, but remained in the range of 5–30 MPa and 10–20 MPa respectively. PC conjugation was associated with significantly reduced platelet adhesion in blood contact testing and the inhibition of rat vascular smooth muscle cell proliferation. These biodegradable PEUU-PC elastomers offer attractive properties for applications as non-thrombogenic, biodegradable coatings and for blood-contacting scaffold applications. Further, the PEUU-NH2 base polymers offer the potential to have multiple types of biofunctional groups conjugated onto the backbone to address a variety of design objectives. PMID:25132273

The development and characterization of degradable poly(vinyl ester) and poly(vinyl ester)/PEO block copolymers

NASA Astrophysics Data System (ADS)

Lipscomb, Corinne Elizabeth

The development of biodegradable materials is a challenging and important problem in polymer science. A review of the state of the art in degradable materials is presented, which reveals that current biodegradable materials do not exhibit the thermal or mechanical properties necessary for widespread applications. One strategy for toughening polymeric materials, which has previously been applied to non-degradable thermoplastics and thermoplastic elastomers, is the formation of block copolymers. Poly(vinyl esters) (PVE) homopolymers are known to have a wide range of properties, but PVE block copolymers comprise a class of inexpensive and (bio)degradable materials that were previously unknown. Therefore, the synthesis and properties of these block copolymers were explored in an effort to develop robust degradable materials. This thesis research probes the reaction conditions necessary for the reversible-addition fragmentation chain transfer (RAFT) polymerization and chain extension reactions of vinyl ester monomers. PVE di- and triblock copolymers are synthesized and studied, and the triblock copolymers display extremely poor toughness due to their relatively low molecular weights in light of the high entanglement molecular weight of the poly(vinyl acetate) center block. Attempts to improve the mechanical properties of these materials focus on the incorporation of poly(ethylene oxide) (PEO) as a low entanglement molecular weight and biocompatible center block in PVE-containing triblock copolymers. Depending on the choice of PVE endblocks and the overall polymer composition, crystallization of the PEO block can be controlled, confined, or inhibited. Polymers in which PEO crystallization is completely inhibited exhibit enhanced mechanical properties and behave as weak thermoplastics. In order to understand the relationship between the inhibition of PEO crystallization and the mechanical properties of PVE/PEO materials, these polymers were studied using dynamic mechanical spectroscopy, wide angle X-ray scattering, small angle X-ray scattering, differential scanning calorimetry, and uniaxial tensile tests. By combining insights gained from these techniques, a complex picture emerges that explains the enhanced mechanical properties of these materials based on the type and location of thermal transitions, amorphous PEO entanglements, and the strain-induced crystallization of PEO. This work represents an important step toward developing robust materials with tunable properties containing (bio)degradable components.

New Polymeric Materials Expected to Have Superior Properties for Space-Based Use.

DTIC Science & Technology

1985-07-01

Polymethacrylic esters Polvacrylic esters GB3 +CH 2-CH1 +CH 2-C4 COOR COOR Pa lyacrylamide Polymethacrylamide +CH -CH+ CH CONH 2 JCH 2-C4 Polyvinyl chloride...fl.. tetracarboxylic acid dianhydride or with pyromellitic dianhydride. These polymers have shown excellent thermal and radiolytic stability...than the crosslinked phthalocyanines. They can be dissolved in sulfuric acid and sublimed into thin films. 2 2 ,2 3 No mechanical properties have been

75 FR 4292 - 2-Propenoic acid, 2-ethylhexyl ester, polymer with ethenylbenzene and 2-methylpropyl 2-methyl-2...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-27

... of pesticide use in residential settings. If EPA is able to determine that a finite tolerance is not... elements carbon, hydrogen, and oxygen. 3. The polymer does not contain as an integral part of its composition, except as impurities, any element other than those listed in 40 CFR 723.250(d)(2)(ii). 4. The...

Fine-tuning of electronic properties in donor-acceptor conjugated polymers based on oligothiophenes

NASA Astrophysics Data System (ADS)

Imae, Ichiro; Sagawa, Hitoshi; Harima, Yutaka

2018-03-01

A novel series of donor-acceptor conjugated polymers having oligothiophenes with well-defined structures were synthesized and their optical, electrochemical, and photovoltaic properties were investigated. It was found that the absorption bands of polymers were red-shifted with increasing number of ethylenedioxy groups added to each oligothiophene unit and that their band edges reached over 1000 nm. The systematical fine-tuning of the electronic properties was achieved using the chemical structures of oligothiophene units. Photovoltaic cells based on polymer/(6,6)-phenyl C61 butyric acid methyl ester (PC61BM) exhibited power conversion efficiencies in the range from 0.004 to 1.10%, reflecting the electronic properties of the polymers.

HYDROPHOBIC ZEOLITE-SILICONE RUBBER MIXED MATRIX MEMBRANES FOR ETHANOL-WATER SEPARATION: EFFECT OF ZEOLITE AND SILICONE COMPONENT SELECTION ON PERVAPORATION PERFORMANCE

EPA Science Inventory

High-silica ZSM 5 zeolites were incorporated into poly(dimethyl siloxane) (PDMS) polymers to form mixed matrix membranes for ethanol removal from water via pervaporation. Membrane formulation and preparation parameters were varied to determine the effect on pervaporation perform...

77 FR 41692 - Significant New Use Rule for Phenol, 2,4- dimethyl-6-(1-methylpentadecyl)-

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-16

... visitors are required to show photographic identification, pass through a metal detector, and sign the EPA... often used as an additive in thermoplastic polymer matrices and in mixtures at concentrations less than... matrices. 5. Revises the recordkeeping requirements under Sec. 721.125 to reflect the modified significant...

21 CFR 177.2460 - Poly(2,6-dimethyl-1,4-phenylene) oxide resins.

Code of Federal Regulations, 2014 CFR

2014-04-01

...-phenylene) oxide basic resins meet the following: (1) Specifications. Intrinsic viscosity is not less than 0... Solution Viscosity of Vinyl Chloride Polymers,” which is incorporated by reference, modified as follows... reference in paragraph (c)(1) of this section) with the reduced viscosity determined for three concentration...

21 CFR 175.320 - Resinous and polymeric coatings for polyolefin films.

Code of Federal Regulations, 2010 CFR

2010-04-01

...-formaldehyde as the basic polymer or chemically modified with methyl alcohol Methacrylic acid and its ethyl or... 68083-18-1), with methyl hydrogen polysiloxane (CAS Reg. No. 63148-57-2). Dimethyl maleate (CAS Reg. No... product of vinyl-containing dimethylpolysiloxane (CAS Reg. Nos. 68083-19-2 and 68083-18-1), with methyl...

21 CFR 175.320 - Resinous and polymeric coatings for polyolefin films.

Code of Federal Regulations, 2011 CFR

2011-04-01

...-formaldehyde as the basic polymer or chemically modified with methyl alcohol Methacrylic acid and its ethyl or... 68083-18-1), with methyl hydrogen polysiloxane (CAS Reg. No. 63148-57-2). Dimethyl maleate (CAS Reg. No... product of vinyl-containing dimethylpolysiloxane (CAS Reg. Nos. 68083-19-2 and 68083-18-1), with methyl...

catena-Poly[[bis­[4-(dimethyl­amino)­pyridine-κN 1]cobalt(II)]-di-μ-azido-κ4 N 1:N 3

PubMed Central

Guenifa, Fatiha; Zeghouan, Ouahida; Hadjadj, Nasreddine; Bendjeddou, Lamia; Merazig, Hocine

2013-01-01

The title layered polymer, [Co(N3)2(C7H10N2)2]n, contains CoII, azide and 4-(dimethyl­amino)­pyridine (4-DMAP) species with site symmetries m2m, 2 and m, respectively. The Co2+ ion adopts an octa­hedral coordination geometry in which four N atoms from azide ligands lie in the equatorial plane and two 4-DMAP N atoms occupy the axial positions. The CoII atoms are connected by two bridging azide ligands, resulting in a chain parallel to the c axis. PMID:23476514

Application of a constant hole volume Sanchez-Lacombe equation of state to mixtures relevant to polymeric foaming.

PubMed

von Konigslow, Kier; Park, Chul B; Thompson, Russell B

2018-06-06

A variant of the Sanchez-Lacombe equation of state is applied to several polymers, blowing agents, and saturated mixtures of interest to the polymer foaming industry. These are low-density polyethylene-carbon dioxide and polylactide-carbon dioxide saturated mixtures as well as polystyrene-carbon dioxide-dimethyl ether and polystyrene-carbon dioxide-nitrogen ternary saturated mixtures. Good agreement is achieved between theoretically predicted and experimentally determined solubilities, both for binary and ternary mixtures. Acceptable agreement with swelling ratios is found with no free parameters. Up-to-date pure component Sanchez-Lacombe characteristic parameters are provided for carbon dioxide, dimethyl ether, low-density polyethylene, nitrogen, polylactide, linear and branched polypropylene, and polystyrene. Pure fluid low-density polyethylene and nitrogen parameters exhibit more moderate success while still providing acceptable quantitative estimations. Mixture estimations are found to have more moderate success where pure components are not as well represented. The Sanchez-Lacombe equation of state is found to correctly predict the anomalous reversal of solubility temperature dependence for low critical point fluids through the observation of this behaviour in polystyrene nitrogen mixtures.

Polyacrylonitrile nanofiber as polar solvent N,N-dimethyl formamide sensor based on quartz crystal microbalance technique

NASA Astrophysics Data System (ADS)

Rianjanu, A.; Julian, T.; Hidayat, S. N.; Suyono, E. A.; Kusumaatmaja, A.; Triyana, K.

2018-04-01

Here, we describe an N,N-dimethyl formamide (DMF) vapour sensor fabricated by coating polyacrylonitrile (PAN) nanofiber structured on quartz crystal microbalance (QCM). The PAN nanofiber sensors with an average diameter of 225 nm to 310 nm were fabricated via electrospinning process with different mass deposition on QCM substrate. The nanostructured of PAN nanofiber offers a high specific surface area that improved the sensing performance of nanofiber sensors. Benefiting from that fine structure, and high polymer-solvent affinity between PAN and DMF, the development of DMF sensors presented good response at ambient temperature. Since there is no chemical reaction between PAN nanofiber and DMF vapour, weak physical interaction such absorption and swelling were responsible for the sensing behavior. The results are indicating that the response of PAN nanofiber sensors has more dependency on the nanofiber structure (specific surface area) rather than its mass deposition. The sensor also showed good stability after a few days sensing. These findings have significant implications for developing DMF vapour sensor based on QCM coated polymer nanofibers.

Solvent stimulated actuation of polyurethane-based shape memory polymer foams using dimethyl sulfoxide and ethanol

NASA Astrophysics Data System (ADS)

Boyle, A. J.; Weems, A. C.; Hasan, S. M.; Nash, L. D.; Monroe, M. B. B.; Maitland, D. J.

2016-07-01

Solvent exposure has been investigated to trigger actuation of shape memory polymers (SMPs) as an alternative to direct heating. This study aimed to investigate the feasibility of using dimethyl sulfoxide (DMSO) and ethanol (EtOH) to stimulate polyurethane-based SMP foam actuation and the required solvent concentrations in water for rapid actuation of hydrophobic SMP foams. SMP foams exhibited decreased T g when submerged in DMSO and EtOH when compared to water submersion. Kinetic DMA experiments showed minimal or no relaxation for all SMP foams in water within 30 min, while SMP foams submerged in EtOH exhibited rapid relaxation within 1 min of submersion. SMP foams expanded rapidly in high concentrations of DMSO and EtOH solutions, where complete recovery over 30 min was observed in DMSO concentrations greater than 90% and in EtOH concentrations greater than 20%. This study demonstrates that both DMSO and EtOH are effective at triggering volume recovery of polyurethane-based SMP foams, including in aqueous environments, and provides promise for use of this actuation technique in various applications.

Supercritical antisolvent co-precipitation of rifampicin and ethyl cellulose.

PubMed

Djerafi, Rania; Swanepoel, Andri; Crampon, Christelle; Kalombo, Lonji; Labuschagne, Philip; Badens, Elisabeth; Masmoudi, Yasmine

2017-05-01

Rifampicin-loaded submicron-sized particles were prepared through supercritical anti-solvent process using ethyl cellulose as polymeric encapsulating excipient. Ethyl acetate and a mixture of ethyl acetate/dimethyl sulfoxide (70/30 and 85/15) were used as solvents for both drug and polymeric excipient. When ethyl acetate was used, rifampicin was crystallized separately without being embedded within the ethyl cellulose matrix while by using the ethyl acetate/dimethyl sulfoxide mixture, reduced crystallinity of the active ingredient was observed and a simultaneous precipitation of ethyl cellulose and drug was achieved. The effect of solvent/CO 2 molar ratio and polymer/drug mass ratio on the co-precipitates morphology and drug loading was investigated. Using the solvent mixture, co-precipitates with particle sizes ranging between 190 and 230nm were obtained with drug loading and drug precipitation yield from respectively 8.5 to 38.5 and 42.4 to 77.2% when decreasing the ethyl cellulose/rifampicin ratio. Results show that the solvent nature and the initial drug concentrations affect morphology and drug precipitation yield of the formulations. In vitro dissolution studies revealed that the release profile of rifampicin was sustained when co-precipitation was carried out with the solvent mixture. It was demonstrated that the drug to polymer ratio influenced amorphous content of the SAS co-precipitates. Differential scanning calorimetry thermograms and infrared spectra revealed that there is neither interaction between rifampicin and the polymer nor degradation of rifampicin during co-precipitation. In addition, stability stress tests on SAS co-precipitates were carried out at 75% relative humidity and room temperature in order to evaluate their physical stability. SAS co-precipitates were X-ray amorphous and remained stable after 6months of storage. The SAS co-precipitation process using a mixture of ethyl acetate/dimethyl sulfoxide demonstrates that this strategy can be successful for controlling rifampicin delivery. Copyright © 2017 Elsevier B.V. All rights reserved.

Formulation and evaluation of biodegradable nanoparticles for the oral delivery of fenretinide.

PubMed

Graves, Richard A; Ledet, Grace A; Glotser, Elena Y; Mitchner, Demaurian M; Bostanian, Levon A; Mandal, Tarun K

2015-08-30

Fenretinide is an anticancer drug with low water solubility and poor bioavailability. The goal of this study was to develop biodegradable polymeric nanoparticles of fenretinide with the intent of increasing its apparent aqueous solubility and intestinal permeability. Three biodegradable polymers were investigated for this purpose: two different poly lactide-co-glycolide (PLGA) polymers, one acid terminated and one ester terminated, and one poly lactide-co-glycolide/polyethylene glycol (PLGA/PEG) diblock copolymer. Nanoparticles were obtained by using an emulsification solvent evaporation technique. The formulations were characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and particle size analysis. Dissolution studies and Caco-2 cell permeation studies were also carried out for all formulations. Ultra high performance liquid chromatography coupled with mass spectrometry (UPLC/MS) and ultraviolet detection was used for the quantitative determination of fenretinide. Drug loading and the type of polymer affected the nanoparticles' physical properties, drug release rate, and cell permeability. While the acid terminated PLGA nanoparticles performed the best in drug release, the ester terminated PLGA nanoparticles performed the best in the Caco-2 cell permeability assays. The PLGA/PEG copolymer nanoparticles performed better than the formulations with ester terminated PLGA in terms of drug release but had the poorest performance in terms of cell permeation. All three categories of formulations performed better than the drug alone in both drug release and cell permeation studies. Copyright © 2015 Elsevier B.V. All rights reserved.

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

NASA Technical Reports Server (NTRS)

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

1977-01-01

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

Round-patterned ZnO nanostructure coated with siloxane-based polymer for nerve agent detection

NASA Astrophysics Data System (ADS)

Choi, Hyun Ji; Lee, Ji Won; Jeong, Dong-Cheol; Ha, Seonggyun; Song, Changsik; Boo, Jin-Hyo

2018-01-01

The alignment of zinc oxide (ZnO) nanostructures is expected to improve device sensitivities due to large surface areas which can be utilized to capture significant quantities of gas particles. In this study, we investigated patterned ZnO nanorods modified with polystyrene monolayers synthesized directly onto a quartz crystal microbalance (QCM) cell to increase the coating surface area of the sensing material. Also, we designed and synthesized a siloxane-based polymer (S1 polymer) as a sensing material. The patterned ZnO nanorods coated with S1 polymers were fabricated and used for the detection of dimethyl methylphosphonate (DMMP). The resonance frequency of QCM was shifted due to the adsorption and desorption of a compound at the surface of the modified electrodes. We have synthesized an S1 polymer that exhibited high sensitivity to DMMP. The patterned ZnO nanorods coated with the polymer also exhibited improved sensitivity due to an enhanced surface area capable of adsorbing more DMMP vapor.

PPV-Based Conjugated Polymer Nanoparticles as a Versatile Bioimaging Probe: A Closer Look at the Inherent Optical Properties and Nanoparticle-Cell Interactions.

PubMed

Peters, Martijn; Zaquen, Neomy; D'Olieslaeger, Lien; Bové, Hannelore; Vanderzande, Dirk; Hellings, Niels; Junkers, Thomas; Ethirajan, Anitha

2016-08-08

Conjugated polymers have attracted significant interest in the bioimaging field due to their excellent optical properties and biocompatibility. Tailor-made poly(p-phenylenevinylene) (PPV) conjugated polymer nanoparticles (NPs) are in here described. Two different nanoparticle systems using poly[2-methoxy-5-(3',7'-dimethoxyoctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and a functional statistical copolymer 2-(5'-methoxycarbonylpentyloxy)-5-methoxy-1,4-phenylenevinylene (CPM-MDMO-PPV), containing ester groups on the alkoxy side chains, were synthesized by combining miniemulsion and solvent evaporation processes. The hydrolysis of ester groups into carboxylic acid groups on the CPM-MDMO-PPV NPs surface allows for biomolecule conjugation. The NPs exhibited excellent optical properties with a high fluorescent brightness and photostability. The NPs were in vitro tested as potential fluorescent nanoprobes for studying cell populations within the central nervous system. The cell studies demonstrated biocompatibility and surface charge dependent cellular uptake of the NPs. This study highlights that PPV-derivative based particles are a promising bioimaging probe and can cater potential applications in the field of nanomedicine.

Toward lanthanide containing coordination polymers and nanomaterials

NASA Astrophysics Data System (ADS)

Greig, Natalie E.

The focus of this thesis is to develop lanthanide (Ln) luminescent materials through the exploration of coordination polymers and nanomaterials. Herein, dimethyl-3,4-furanedicarboxylate acid undergoes hydrolysis under hydrothermal conditions to form coordination polymers with lanthanide ions. The resulting coordination polymers exhibited luminescent properties, with quantum yields and lifetimes for the Eu- and Tb-CP of 1.14±0.31% and 0.387±0.0001 ms, and 3.33±0.82% and 0.769±0.006 ms, respectively. While the incorporation of lanthanides was not achieved in this work, progress toward the production of pure phase InP in the nanoregime has been made, using a low-cost, hydrothermal method. Though SEM and PXRD conflict, it is believed that pure InP particles with a size range of 58-81 nm were successfully synthesized.

Preparations and properties of anti-corrosion additives of water-soluble metal working fluids for aluminum alloy materials.

PubMed

Watanabe, Shoji

2008-01-01

This short review describes various types of anti-corrosion additives of water-soluble metal working fluids for aluminum alloy materials. It is concerned with synthetic additives classified according to their functional groups; silicone compounds, carboxylic acids and dibasic acids, esters, Diels-Alder adducts, various polymers, nitrogen compounds, phosphoric esters, phosphonic acids, and others. Testing methods for water-soluble metal working fluids for aluminum alloy materials are described for a practical application in a laboratory.

The 5-(4-Ethynylophenoxy) isophthalic chloride

NASA Technical Reports Server (NTRS)

Hergenrother, P. M.; Jensen, B. J. (Inventor)

1986-01-01

Sulfone-ester polymers containing pendent ethynyl groups and a direct and multistep process for preparing them are disclosed. The multistep process involves the conversion of a pendent bromo group to the ethynyl group while the direct route involves reating hydroxy-terminated sulfone oligomer or polymers with a stoichiometric amount of 5-(4-ethynylphenoxy) isophthaloyl chloride. The 5-(4-ethynylphenoxy) isophthaloyl chloride and the process for preparing it are also disclosed.

Flexible, highly efficient all-polymer solar cells

PubMed Central

Kim, Taesu; Kim, Jae-Han; Kang, Tae Eui; Lee, Changyeon; Kang, Hyunbum; Shin, Minkwan; Wang, Cheng; Ma, Biwu; Jeong, Unyong; Kim, Taek-Soo; Kim, Bumjoon J.

2015-01-01

All-polymer solar cells have shown great potential as flexible and portable power generators. These devices should offer good mechanical endurance with high power-conversion efficiency for viability in commercial applications. In this work, we develop highly efficient and mechanically robust all-polymer solar cells that are based on the PBDTTTPD polymer donor and the P(NDI2HD-T) polymer acceptor. These systems exhibit high power-conversion efficiency of 6.64%. Also, the proposed all-polymer solar cells have even better performance than the control polymer-fullerene devices with phenyl-C61-butyric acid methyl ester (PCBM) as the electron acceptor (6.12%). More importantly, our all-polymer solar cells exhibit dramatically enhanced strength and flexibility compared with polymer/PCBM devices, with 60- and 470-fold improvements in elongation at break and toughness, respectively. The superior mechanical properties of all-polymer solar cells afford greater tolerance to severe deformations than conventional polymer-fullerene solar cells, making them much better candidates for applications in flexible and portable devices. PMID:26449658

Cyclic Tetrapyrrolic Photosensitisers from the leaves of Phaeanthus ophthalmicus

PubMed Central

2011-01-01

Background Twenty-seven extracts from 26 plants were identified as photo-cytotoxic in the course of our bioassay guided screening program for photosensitisers from 128 extracts prepared from 64 terrestrial plants in two different collection sites in Malaysia - Royal Belum Forest Reserve in the State of Perak and Gunung Nuang in the State of Selangor. One of the photo-cytotoxic extracts from the leaves of Phaeanthus ophtalmicus was further investigated. Results The ethanolic extract of the leaves from Phaeanthus ophtalmicus was able to reduce the in vitro viability of leukaemic HL60 cells to < 50% when exposed to 9.6 J/cm2 of a broad spectrum light at a concentration of 20 μg/mL. Dereplication of the photo-cytotoxic fractions from P. ophthalmicus extracts based on TLC Rf values and HPLC co-injection of reference tetrapyrrolic compounds enabled quick identification of known photosensitisers, pheophorbide-a, pheophorbide-a methyl ester, 132-hydroxypheophorbide-a methyl ester, pheophytin-a and 151-hydroxypurpurin 7-lactone dimethyl ester. In addition, compound 1 which was not previously isolated as a natural product was also identified as 7-formyl-151-hydroxypurpurin-7-lactone methyl ester using standard spectroscopic techniques. Conclusions Our results suggest that the main photosensitisers in plants are based on the cyclic tetrapyrrole structure and photosensitisers with other structures, if present, are present in very minor amounts or are not as active as those with the cyclic tetrapyrrole structure. PMID:21682931

The design, synthesis, and characterization of poly(carbonate-ester)s based on dihydroxyacetone for use as potential biomaterials

NASA Astrophysics Data System (ADS)

Weiser, Jennifer Rose

The creation of new devices and materials with desirable biomedical characteristics, such as biocompatibility and easily tunable physico-chemical parameters, has played a key role in the advancement of the biomedical industry. In recent years, the combination of classical engineering principles with polymer chemistry has led to a wide range of materials that influence the manner in which drugs are delivered, tissues are engineered, and surgery is performed. The work presented in this thesis is focused on the design, synthesis, and characterization of a poly(carbonate-ester) biomaterial based on lactic acid (LA) and a carbonate form of dihydroxyacetone (DHAC) as vehicles for controlled release. The goal of this work was to synthesize a variety of pLAx- co-DHACy copolymers and characterize their behavior to better understand their structure/function relationships. The results show that random copolymers based on dihydroxyacetone and lactic acid are easily and reliably producible, with unique characteristics. In vitro degradation studies showed that the poly(carbonate-ester)s had an unexpected degradation pattern, in that the carbonate bond was more labile to hydrolysis than that of the ester bond. The resulting degradation pattern made from these biomaterials did not appear to have an acidic interior environment, due to a lack of visible viscous core commonly seen with bulk degrading lactic acid based polymers. Due to the insolubility of the poly(carbonate-ester)s, exploration of copolymer degradation was determined by the development of a newly discovered technique to quantify dihydroxyacetone release from the matrix using the bicinchoninic acid assay. Finally, the release kinetics and mechanism from these poly(carbonate-ester)s was studied following the incorporation of two different model proteins, bovine serum albumin and lysozyme. Their release behaviors and activities were analyzed to explore the controlled release capabilities of these materials and to identify their potential for the effective release of proteins.

Solution blow spinning: parameters optimization and effects on the properties of nanofibers from poly(lactic) acid/dimethyl carbonate solutions

USDA-ARS?s Scientific Manuscript database

Solution blow spinning (SBS) is a process to produce non-woven fiber sheets with high porosity and an extremely large amount of surface area. In this study, a Box-Behnken experimental design (BBD) was used to optimize the processing parameters for the production of nanofibers from polymer solutions ...

[A new secoiridoid from the flowers of Jasminum officinale L. var. grandiflorum].

PubMed

Zhao, Gui-Qin; Yin, Zhi-Feng; Dong, Jun-Xing

2008-05-01

To study the chemical constituents of the flowers of Jasminum officinale L. var. grandiflorum, the compounds were isolated and purified by HPLC, recrystallization and chromatography on silica gel and Sephadex LH-20 column. Their structures were elucidated on the basis of physicochemical properties and spectral analysis. Six secoiridoids were identified as jasgranoside (I), jaspolyoside (II), 8-epi-kingiside (III), 10-hydroxy-oleuropein (IV), 10-hydroxy-ligstroside (V), oleoside-7, 11-dimethyl ester (VI). Compound I is a new compound. Compounds II, III, IV, V and VI were isolated from Jasminum officinale L. var. grandiflorum for the first time.

Fluorescence method for enzyme analysis which couples aromatic amines with aromatic aldehydes

DOEpatents

Smith, R.E.; Dolbeare, F.A.

1980-10-21

Analysis of proteinases is accomplished using conventional amino acid containing aromatic amine substrates. Aromatic amines such as 4-methoxy-2-naphthylamine (4M2NA), 2-naphthylamine, aminoisophthalic acid dimethyl ester, p-nitroaniline, 4-methoxy-1-aminofluorene and coumarin derivatives resulting from enzymatic hydrolysis of the substrate couples with aromatic aldehydes such as 5-nitrosalicylaldehyde (5-NSA), benzaldehyde and p-nitrobenzaldehyde to produce Schiff-base complexes which are water insoluble. Certain Schiff-base complexes produce a shift from blue to orange-red (visible) fluorescence. Such complexes are useful in the assay of enzymes. No Drawings

Fluorescence method for enzyme analysis which couples aromatic amines with aromatic aldehydes

DOEpatents

Smith, Robert E. [557 Escondido Cir., Livermore, CA 94550; Dolbeare, Frank A. [5178 Diane La., Livermore, CA 94550

1980-10-21

Analysis of proteinases is accomplished using conventional amino acid containing aromatic amine substrates. Aromatic amines such as 4-methoxy-2-naphthylamine (4M2NA), 2-naphthylamine, aminoisophthalic acid dimethyl ester, p-nitroaniline, 4-methoxy-1-aminofluorene and coumarin derivatives resulting from enzymatic hydrolysis of the substrate couples with aromatic aldehydes such as 5-nitrosalicylaldehyde (5-NSA), benzaldehyde and p-nitrobenzaldehyde to produce Schiff-base complexes which are water insoluble. Certain Schiff-base complexes produce a shift from blue to orange-red (visible) fluorescence. Such complexes are useful in the assay of enzymes.

Fluorescence method for enzyme analysis which couples aromatic amines with aromatic aldehydes

DOEpatents

Smith, Robert E.; Dolbeare, Frank A.

1979-01-01

Analysis of proteinases is accomplished using conventional amino acid containing aromatic amine substrates. Aromatic amines such as 4-methoxy-2-naphthylamine (4M2NA), 2-naphthylamine, aminoisophthalic acid dimethyl ester, p-nitroaniline, 5-methoxy-1-aminofluorene and coumarin derivatives resulting from enzymatic hydrolysis of the substrate couples with aromatic aldehydes such as 5-nitrosalicylaldehyde (5-NSA), benzaldehyde and p-nitrobenzaldehyde to produce Schiff-base complexes which are water insoluble. Certain Schiff-base complexes produce a shift from blue to orange-red (visible) fluorescence. Such complexes are useful in the assay of enzymes.

Structural Peculiarities of Ion-Conductive Organic-Inorganic Polymer Composites Based on Aliphatic Epoxy Resin and Salt of Lithium Perchlorate.

PubMed

Matkovska, Liubov; Iurzhenko, Maksym; Mamunya, Yevgen; Tkachenko, Igor; Demchenko, Valeriy; Synyuk, Volodymyr; Shadrin, Andriy; Boiteux, Gisele

2017-12-01

The article is concerned with hybrid amorphous polymers synthesized basing on epoxy oligomer of diglycide aliphatic ester of polyethylene glycol that was cured by polyethylene polyamine and lithium perchlorate salt. Structural peculiarities of organic-inorganic polymer composites were studied by differential scanning calorimetry, wide-angle X-ray spectra, infrared spectroscopic, scanning electron microscopy, elemental analysis, and transmission and reflective optical microscopy. On the one hand, the results showed that the introduction of LiClO 4 salt into epoxy polymer leads to formation of the coordinative metal-polymer complexes of donor-acceptor type between central Li + ion and ligand. On the other hand, the appearance of amorphous microinclusions, probably of inorganic nature, was also found.

Functional Polymers and Sequential Copolymers by Phase Transfer Catalysis. Synthesis of Thermotropic Side-Chain Liquid Crystalline Polymers Containing a Poly(2,6-Dimethyl-1,4-Phenylene Oxide) Main Chain.

DTIC Science & Technology

1986-10-01

bromovalerate (Aldrich, 99%), 5-bromovaleronitrile (Aldrich, 95%), and 11-bromoundecanoic acid (Aldrich, 99%) were used without further purification. 4...atic proton’s). 71 Cm, 4 aromatic X~tons). C. Synthesis of 4- 4-oxybipheny1 butyrnc acid , 4-(4-inethoxy 4’-oxy- I hen 1 butyrnc acid , 5-(4-oxybipheny1...valeric acid , 5-(4-inethoxy-4-oxy- bi heny1 valeric acid . 11- 4-ox bipheny1 undecanoic acid and 11- 4-inethox -4 -ox biphenylundecanoic acid . The

Investigation of polymer membranes modified by fullerenol for dehydration of organic mixtures

NASA Astrophysics Data System (ADS)

Dmitrenko, Mariia E.; Penkova, Anastasia V.; Kuzminova, Anna I.; Ermakov, Sergey S.; Roizard, Denis

2017-07-01

This study focuses on the development of novel dense and supported mixed-matrix membranes based on chitosan and poly(2,6-dimethyl-1,4-phenylenoxide) (PPO) with low-hydroxylated fullerenol C60(OH)12. These novel membranes containing nano-carbon particles were prepared to reach high membrane performances for further integration in a dehydration process like distillation coupled with pervaporation. SEM microscopy was used to visualize the internal morphology of the membrane. It was found that all membranes were well stable and highly water-selective in spite of the different nature of polymers.

Solid-phase microextraction of phthalate esters in water sample using different activated carbon-polymer monoliths as adsorbents.

PubMed

Lirio, Stephen; Fu, Chung-Wei; Lin, Jhih-Yun; Hsu, Meng-Ju; Huang, Hsi-Ya

2016-07-13

In this study, the application of different activated carbon-polymer (AC-polymer) monoliths as adsorbents for the solid-phase microextraction (SPME) of phthalate esters (PAEs) in water sample were investigated. The activated carbon (AC) was embedded in organic polymers, poly(butyl methacrylate-co-ethylene dimethacrylate) (poly(BMA-EDMA)) or poly(styrene-co-divinylbenzene) (poly(STY-DVB)), via a 5-min microwave-assisted or a 15-min water bath heating polymerization. Preliminary investigation on the performance of the native poly(BMA-EDMA) and poly(STY-DVB) demonstrated remarkable adsorption efficiencies for PAEs. However, due to the strong hydrophobic, π-π, and hydrogen bonding interactions between the analytes and polymers, low extraction recoveries were achieved. In contrast, the presence of AC in native polymers not only enhanced the adsorption efficiencies but also assisted the PAE desorption, especially for AC-poly(STY-DVB) with extraction recovery ranged of 76.2-99.3%. Under the optimized conditions, the extraction recoveries for intra-, inter-day and column-to-column were in the range of 76.5-100.8% (<3.7% RSDs), 77.2-97.6% (<5.6% RSDs) and 75.5-99.7% (<6.2% RSDs), respectively. The developed AC-poly(STY-DVB) monolithic column showed good mechanical stability, which can be reused for more than 30 extraction times without any significant loss in the extraction recoveries of PAEs. The AC-poly(STY-DVB) monolithic column was successfully applied in SPME of PAEs in water sample with extraction recovery ranged of 78.8%-104.6% (<5.5% RSDs). Copyright © 2016 Elsevier B.V. All rights reserved.

Study on characteristics of PVDF/nano-clay composite polymer electrolyte using PVP as pore-forming agent

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dyartanti, Endah R., E-mail: heru.susanto@undip.ac.id, E-mail: endah-rd@uns.ac.id; Department of Chemical Engineering, Diponegoro University, Semarang; Purwanto, Agus

2016-02-08

Polyvinylidene fluoride (PVDF) based polymer electrolytes have a high dielectric constant, which can assist in greater ionization of lithium salts. The main advantages of PVDF are its durability in long battery operation and its ability to be a good ion conductor. However, the limitation of this polymer is its crystalline molecular structure. Dispersing nano-particles in the polymer matrix may improve the characteristics of the PVDF polymer. This paper aims to investigate the impact of nano-clay addition on the characteristics of PVDF polymer to be used as a polymer electrolyte membrane. In addition, the effect of poly(vinyl pyrrolidone) (PVP) is alsomore » investigated. The membrane was prepared by phase separation method whereas the polymer electrolyte membranes was prepared by immersing into 1 M lithium hexafluorophosphate (LiPF{sub 6}) in ethylene carbonate/dimethyl carbonate (EC/DMC) electrolytes for 1 h. The membranes were characterized by scanning electron microscope (SEM), porosity and electrolyte uptake and performance in battery cell. The results showed that both nano-clay and PVP have significant impacts on the improvement of PVDF membranes to be used as polymer electrolyte.« less

Dextran hydrogels by crosslinking with amino acid diamines and their viscoelastic properties.

PubMed

O'Connor, Naphtali A; Jitianu, Mihaela; Nunez, Greisly; Picard, Quentin; Wong, Madeline; Akpatsu, David; Negrin, Adam; Gharbaran, Rajendra; Lugo, Daniel; Shaker, Sundus; Jitianu, Andrei; Redenti, Stephen

2018-05-01

Amine functionalized polysaccharide hydrogels such as those based on chitosan are widely examined as biomaterials. Here we set out to develop a facile procedure for developing such hydrogels by crosslinking dextran with amino acid diamines. The dextran-amino acid gels were formed by the addition of the amino acid diamines to a dextran and epichlorohydrin solution once it became homogeneous. This was demonstrated with three amino acid diamines, lysine, lysine methyl ester, and cystine dimethyl ester. Hydrogel networks with albumin entrapped were also demonstrated. These hydrogels were characterized by FTIR, SEM, rotational rheometry, swelling studies and cell biocompatibility analysis. These hydrogels showed the unexpected pH-responsive behavior of greater swelling at more basic pH, similar to that of an anionic hydrogel. This is uncharacteristic for amine functionalized gels as they typically exhibit cationic hydrogel behavior. All hydrogels showed similar biocompatibility to that of dextran crosslinked without amino acids. Copyright © 2018 Elsevier B.V. All rights reserved.

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.

PubMed Central

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

Process for the production of ethylidene diacetate from dimethyl ether using a heterogeneous catalyst

DOEpatents

Ramprasad, D.; Waller, F.J.

1998-04-28

This invention relates to a process for producing ethylidene diacetate by the reaction of dimethyl ether, acetic acid, hydrogen and carbon monoxide at elevated temperatures and pressures in the presence of an alkyl halide and a heterogeneous, bifunctional catalyst that is stable to hydrogenation and comprises an insoluble polymer having pendant quaternized heteroatoms, some of which heteroatoms are ionically bonded to anionic Group VIII metal complexes, the remainder of the heteroatoms being bonded to iodide. In contrast to prior art processes, no accelerator (promoter) is necessary to achieve the catalytic reaction and the products are easily separated from the catalyst by filtration. The catalyst can be recycled for 3 consecutive runs without loss in activity.

Process for the production of ethylidene diacetate from dimethyl ether using a heterogeneous catalyst

DOEpatents

Ramprasad, Dorai; Waller, Francis Joseph

1998-01-01

This invention relates to a process for producing ethylidene diacetate by the reaction of dimethyl ether, acetic acid, hydrogen and carbon monoxide at elevated temperatures and pressures in the presence of an alkyl halide and a heterogeneous, bifunctional catalyst that is stable to hydrogenation and comprises an insoluble polymer having pendant quaternized heteroatoms, some of which heteroatoms are ionically bonded to anionic Group VIII metal complexes, the remainder of the heteroatoms being bonded to iodide. In contrast to prior art processes, no accelerator (promoter) is necessary to achieve the catalytic reaction and the products are easily separated from the catalyst by filtration. The catalyst can be recycled for 3 consecutive runs without loss in activity.

Presidential Green Chemistry Challenge: 2009 Designing Greener Chemicals Award

EPA Pesticide Factsheets

Presidential Green Chemistry Challenge 2009 award winners, Procter & Gamble Co. (P&G) and Cook Composites and Polymers Co. (CCP), developed Chempol MPS resins and Sefose sucrose esters to enable high-performance low-VOC alkyd paints.

Achieving significantly enhanced visible-light photocatalytic efficiency using a polyelectrolyte: the composites of exfoliated titania nanosheets, graphene, and poly(diallyl-dimethyl-ammonium chloride)

NASA Astrophysics Data System (ADS)

Zhang, Qian; An, Qi; Luan, Xinglong; Huang, Hongwei; Li, Xiaowei; Meng, Zilin; Tong, Wangshu; Chen, Xiaodong; Chu, Paul K.; Zhang, Yihe

2015-08-01

A high-performance visible-light-active photocatalyst is prepared using the polyelectrolyte/exfoliated titania nanosheet/graphene oxide (GO) precursor by flocculation followed by calcination. The polyelectrolyte poly(diallyl-dimethyl-ammonium chloride) serves not only as an effective binder to precipitate GO and titania nanosheets, but also boosts the overall performance of the catalyst significantly. Unlike most titania nanosheet-based catalysts reported in the literature, the composite absorbs light in the UV-Vis-NIR range. Its decomposition rate of methylene blue is 98% under visible light. This novel strategy of using a polymer to enhance the catalytic performance of titania nanosheet-based catalysts affords immense potential in designing and fabricating next-generation photocatalysts with high efficiency.A high-performance visible-light-active photocatalyst is prepared using the polyelectrolyte/exfoliated titania nanosheet/graphene oxide (GO) precursor by flocculation followed by calcination. The polyelectrolyte poly(diallyl-dimethyl-ammonium chloride) serves not only as an effective binder to precipitate GO and titania nanosheets, but also boosts the overall performance of the catalyst significantly. Unlike most titania nanosheet-based catalysts reported in the literature, the composite absorbs light in the UV-Vis-NIR range. Its decomposition rate of methylene blue is 98% under visible light. This novel strategy of using a polymer to enhance the catalytic performance of titania nanosheet-based catalysts affords immense potential in designing and fabricating next-generation photocatalysts with high efficiency. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03256c

Comparative antimicrobial activity, in vitro and in vivo, of soft N-chloramine systems and chlorhexidine.

PubMed Central

Selk, S H; Pogány, S A; Higuchi, T

1982-01-01

Antimicrobial activity of the following four new N-chloramine compounds was evaluated: two chlorinated simple amino acids, a chlorinated half-ester of succinic acid, and a chlorinated half-ester of glutaric acid. For comparison, the known bactericidal agents 3-chloro-4,4-dimethyl-2-oxazolidinone and chlorhexidine were evaluated by the same procedure. The contact germicidal efficiency screen was used to examine the in vitro bactericidal activity of all six compounds in the absence and presence of 5% horse serum or 5% Triton X-100. The four new compounds were found to have greater germicidal activity than the other compounds tested and to exhibit low toxicity and skin irritation values. The in vivo bactericidal activity was evaluated in two studies. In the occlusion test, three of the four new compounds plus chlorhexidine diacetate were tested. The N-chloramines were significantly superior to chlorhexidine in preventing the expansion of the normal flora under occlusion. In the scrub test, a gloved-hand wash method was used to compare the antimicrobial effect of a 1% solution of the chlorinated half-ester of succinic acid in triacetin with that of a commercial germicidal hand wash containing 4% chlorhexidine gluconate. The two preparations exhibited essentially the same hand-degerming activity. PMID:6805433

β-Keto esters from ketones and ethyl chloroformate: a rapid, general, efficient synthesis of pyrazolones and their antimicrobial, in silico and in vitro cytotoxicity studies

PubMed Central

2013-01-01

Background Pyrazolones are traditionally synthesized by the reaction of β-keto esters with hydrazine and its derivatives. There are methods to synthesize β-keto esters from esters and aldehydes, but these methods have main limitation in varying the substituents. Often, there are a number of methods such as acylation of enolates in which a chelating effect has been employed to lock the enolate anion using lithium and magnesium salts; however, these methods suffer from inconsistent yields in the case of aliphatic acylation. There are methods to synthesize β-keto esters from ketones like caboxylation of ketone enolates using carbon dioxide and carbon monoxide sources in the presence of palladium or transition metal catalysts. Currently, the most general and simple method to synthesize β-keto ester is the reaction of dimethyl or ethyl carbonate with ketone in the presence of strong bases which also requires long reaction time, use of excessive amount of reagent and inconsistent yield. These factors lead us to develop a simple method to synthesize β-keto esters by changing the base and reagent. Results A series of β-keto esters were synthesized from ketones and ethyl chloroformate in the presence of base which in turn are converted to pyrazolones and then subjected to cytotoxicity studies towards various cancer cell lines and antimicrobial activity studies towards various bacterial and fungal strains. Conclusion The β-keto esters from ethyl chloroformate was successfully attempted, and the developed method is simple, fast and applicable to the ketones having the alkyl halogens, protecting groups like Boc and Cbz that were tolerated and proved to be useful in the synthesis of fused bicyclic and tricyclic pyrazolones efficiently using cyclic ketones. Since this method is successful for different ketones, it can be useful for the synthesis of pharmaceutically important pyrazolones also. The synthesized pyrazolones were subjected to antimicrobial, docking and cytotoxicity assay against ACHN (human renal cell carcinoma), Panc-1 (human pancreatic adenocarcinoma) and HCT-116 (human colon cancer) cell line, and lead molecules have been identified. Some of the compounds are found to have promising activity against different bacterial and fungal strains tested. PMID:23870758

Electrically conductive polymer concrete coatings

DOEpatents

Fontana, J.J.; Elling, D.; Reams, W.

1990-03-13

A sprayable electrically conductive polymer concrete coating for vertical d overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt % calcined coke breeze, 40 wt % vinyl ester with 3.5 wt % modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag.

Electrically conductive polymer concrete coatings

DOEpatents

Fontana, Jack J.; Elling, David; Reams, Walter

1990-01-01

A sprayable electrically conductive polymer concrete coating for vertical d overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt % calcined coke breeze, 40 wt % vinyl ester with 3.5 wt % modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag.

Very High Performance High Nitrogen Energetic Ingredients and Energetic Polymers for Structural Components

DTIC Science & Technology

2011-12-31

have developed a vastly improved procedure for synthesis of the n- propyl ester that gives essentially quantitative yield and uses concentrated... Synthesis of n- propyl 4-aminofurazan-3-carboxylate. We next turned our attention to the synthesis of the amide. Again, the literature procedure is... synthesis and chemistry of 3-hydroxymethyl-4-amino[1,2,5]oxadiazole and 5) work on energetic polymers for structural components. 15. SUBJECT TERMS

Submicroporous/microporous and compatible/incompatible multi-functional dual-layer polymer electrolytes and their interfacial characteristics with lithium metal anode

NASA Astrophysics Data System (ADS)

Lee, Young-Gi; Kyhm, Kwangseuk; Choi, Nam-Soon; Ryu, Kwang Sun

A novel multi-functional dual-layer polymer electrolyte was prepared by impregnating the interconnected pores with an ethylene carbonate (EC)/dimethyl carbonate (DMC)/lithium hexafluorophosphate (LiPF 6) solution. An incompatible layer is based on a microporous polyethylene (PE) and a compatible layer, based on a poly(vinylidenefluoride-co-hexafluoropropylene) (P(VdF-co-HFP)) is sub-microporous and compatible with an electrolyte solution. The Li electrode/the dual-layer polymer electrolyte/Li[Ni 0.15Li 0.23M n0.62]O 2 cell showed stable cycle performance under prolonged cycle number. This behavior is due to the enhanced compatibility between the matrix polymer and the liquid electrolytes within the submicroporous compatible layer, which could lead to a controlled Li + deposition on the Li anode surface by forming homegeneous electrolyte zone near the anode.

A study on optical properties of poly (ethylene oxide) based polymer electrolyte with different alkali metal iodides

NASA Astrophysics Data System (ADS)

Rao, B. Narasimha; Suvarna, R. Padma

2016-05-01

Polymer electrolytes were prepared by adding poly (ethylene glycol) dimethyl ether (PEGDME), TiO2 (nano filler), different alkali metal iodide salts RI (R+=Li+, Na+, K+, Rb+, Cs+) and I2 into Acetonitrile gelated with Poly (ethylene oxide) (PEO). Optical properties of poly (ethylene oxide) based polymer electrolytes were studied by FTIR, UV-Vis spectroscopic techniques. FTIR spectrum reveals that the alkali metal cations were coordinated to ether oxygen of PEO. The optical absorption studies were made in the wavelength range 200-800 nm. It is observed that the optical absorption increases with increase in the radius of alkali metal cation. The optical band gap for allowed direct transitions was evaluated using Urbach-edges method. The optical properties such as optical band gap, refractive index and extinction coefficient were determined. The studied polymer materials are useful for solar cells, super capacitors, fuel cells, gas sensors etc.

Facile surface modification of glass with zwitterionic polymers for improving the blood compatibility

NASA Astrophysics Data System (ADS)

Zhang, Lingling; Chen, Xiaojuan; Liu, Pingsheng; Wang, Jing; Zhu, Haomiao; Li, Li

2018-06-01

A facile procedure to modify glass film with zwitterionic polymers for improving the blood compatibility was introduced. The glass slides were first silanized with 3-methacryloxypropyltrimethoxysilane (MPT) to generate methacrylate groups on the surface. Then, N, N’-dimethyl-N-methacryloxyethyl-N-(3-sulfopropyl) ammonium (DMMSA), a sulfobetaine zwitterionic monomer, was polymerized on the silanized glass substrates by free-radical polymerization in order to graft the zwitterionic polymers onto the substrates. X-ray Photoelectron Spectroscopy (XPS), water contact angle, scanning electron microscope (SEM) and atomic force microscopy (AFM) were utilized to analyze the surface properties of the grafted glass. The blood compatibility of the grafted glass was verified by whole blood contacting and platelet adhesion experiments in vitro. The results showed that the zwitterionic polymers were successfully grafted on the glass surface, and consequently significantly inhibited the platelet adhesion and whole blood cell attachment.

Process for crosslinking and extending conjugated diene-containing polymers

NASA Technical Reports Server (NTRS)

Bell, Vernon L. (Inventor); Havens, Stephen J. (Inventor)

1977-01-01

A process using a Diels-Alder reaction which increases the molecular weight and/or crosslinks polymers by reacting the polymers with bisunsaturated dienophiles is developed. The polymer comprises at least 75% by weight based on the reaction product, has a molecular weight of at least 5000 and a plurality of conjugated 1,3-diene systems incorporated into the molecular structure. A dienophile reaction with the conjugated 1,3-diene of the polymer is at least 1% by weight based on the reaction product. Examples of the polymer include polyesters, polyamides, polyethers, polysulfones and copolymers. The bisunsaturated dienophiles may include bis-maleimides, bis maleic and bis tumaric esters and amides. This method for expanding the molecular weight chains of the polymers, preferable thermoplastics, is advantageous for processing or fabricating thermoplastics. A low molecular weight thermoplastic is converted to a high molecular weight plastic having improved strength and toughness for use in the completed end use article.

Selenium-substituted polymers for improved photovoltaic performance.

PubMed

Yu, Jiangsheng; Ding, Guanqun; Hai, Jiefeng; Zhu, Enwei; Yin, Xinxing; Xu, Zhongsheng; Zhou, Baojing; Zhang, Fujun; Ma, Wanli; Tang, Weihua

2016-03-21

Four isostructural donor-acceptor alternating polymers of benzodithiophene (BDT)/naphthodifuran (NDF) and benzoselenadiazole (BSe)/benzothiadiazole (BT) have been developed and evaluated for organic photovoltaics. The substitution of one-atom (Se for S) in the accepting units exerts remarkable impact on the optoelectronic properties of polymers. Extended absorption, narrowed bandgap and higher HOMO energy levels were observed for Se-containing polymers in comparison to their S-containing counterparts. Theoretical calculations confirmed the measurable effect on energy levels as found in experimental studies. Bulk-heterojuction solar cells based on the BDT-BSe copolymer and [6,6]-phenyl-C71-butyric acid methyl ester (1 : 2, w/w) blend films deliver the best PCE of 5.40%. BSe-based polymers showed enhanced photovoltaic performances than BT-based polymers. The device performance is found to be strongly dependent on the processing conditions and morphology of the active layers.

The sorption properties of polymers with molecular imprints of chlorine-containing pesticides

NASA Astrophysics Data System (ADS)

Popov, S. A.; Dmitrienko, S. G.; Chumichkina, Yu. A.; Zolotov, Yu. A.

2009-04-01

Polymers with molecular imprints of 2,4-dichlorophenoxyacetic acid (2,4-D), 3,6-dichloro-2-methoxybenzoic acid (dicamba), and (RS)-1- p-chlorophenyl-4,4-dimethyl-3-(1H-1,2,4-triazol-1-ylmethyl) pentan-3-ol and the corresponding blank polymers were synthesized using acrylamide as a functional monomer. The specific surface area of the resulting materials was estimated and their sorption properties were studied. It was found that the sorption characteristics of the polymers with molecular imprints of chlorine-containing pesticides depended on the nature of template molecules, functional monomer: template ratio in the polymerization mixture, and nature and content of solvents varied at the synthesis stage. According to the sorption isotherms, the difference in the sorption behavior of molecularly imprinted and blank polymers was observed over a wide range of chlorine-containing pesticide concentrations. The selectivity of the adsorbent with 2,4-D imprints was estimated for the example of structurally related compounds.

Development of a New Monomer for the Synthesis of Intrinsic Antimicrobial Polymers with Enhanced Material Properties.

PubMed

Brodkorb, Florian; Fischer, Björn; Kalbfleisch, Katrin; Robers, Oliver; Braun, Carina; Dohlen, Sophia; Kreyenschmidt, Judith; Lorenz, Reinhard; Kreyenschmidt, Martin

2015-08-24

The use of biocidal compounds in polymers is steadily increasing because it is one solution to the need for safety and hygiene. It is possible to incorporate an antimicrobial moiety to a polymer. These polymers are referred to as intrinsic antimicrobial. The biocidal action results from contact of the polymer to the microorganisms, with no release of active molecules. This is particularly important in critical fields like food technology, medicine and ventilation technology, where migration or leaching is crucial and undesirable. The isomers N-(1,1-dimethylethyl)-4-ethenyl-benzenamine and N-(1,1-dimethyl-ethyl)-3-ethenyl-benzenamine (TBAMS) are novel (Co-)Monomers for intrinsic anti-microbial polymers. The secondary amines were prepared and polymerized to the corresponding water insoluble polymer. The antimicrobial activity was analyzed by the test method JIS Z 2801:2000. Investigations revealed a high antimicrobial activity against Staphylococcus aureus and Escherichia coli with a reduction level of >4.5 log10 units. Furthermore, scanning electron microscopy (SEM) of E. coli. in contact with the polymer indicates a bactericidal action which is caused by disruption of the bacteria cell membranes, leading to lysis of the cells.

Photo-triggered solvent-free metamorphosis of polymeric materials.

PubMed

Honda, Satoshi; Toyota, Taro

2017-09-11

Liquefaction and solidification of materials are the most fundamental changes observed during thermal phase transitions, yet the design of organic and polymeric soft materials showing isothermal reversible liquid-nonliquid conversion remains challenging. Here, we demonstrate that solvent-free repeatable molecular architectural transformation between liquid-star and nonliquid-network polymers that relies on cleavage and reformation of a covalent bond in hexaarylbiimidazole. Liquid four-armed star-shaped poly(n-butyl acrylate) and poly(dimethyl siloxane) with 2,4,5-triphenylimidazole end groups were first synthesized. Subsequent oxidation of the 2,4,5-triphenylimidazoles into 2,4,5-triphenylimidazoryl radicals and their coupling with these liquid star polymers to form hexaarylbiimidazoles afforded the corresponding nonliquid network polymers. The resulting nonliquid network polymers liquefied upon UV irradiation and produced liquid star-shaped polymers with 2,4,5-triphenylimidazoryl radical end groups that reverted to nonliquid network polymers again by recoupling of the generated 2,4,5-triphenylimidazoryl radicals immediately after terminating UV irradiation.The design of organic and polymeric soft materials showing isothermal reversible liquid-nonliquid conversion is challenging. Here, the authors show solvent-free repeatable molecular architectural transformation between liquid-star and non-liquid-network polymers by the cleavage and reformation of covalent bonds in the polymer chain.

A novel (S)-(+)-decursin derivative, (S)-(+)-3-(3,4-dihydroxy-phenyl)-acrylic acid 2,2-dimethyl-8-oxo-3,4-dihydro-2H,8H-pyrano[3,2-g]chromen-3-yl-ester, inhibits ovalbumin-induced lung inflammation in a mouse model of asthma.

PubMed

Yang, Eun Ju; Song, Gyu-Yong; Lee, Ji-Sook; Yun, Chi-Young; Kim, In Sik

2009-03-01

(S)-(+)-Decursin is a coumarin compound present in herbal extracts that has various biological activities. (S)-(+)-Decursin attenuates pathophysiologic progression in cancer, bacterial infection and neuropathy. Asthma is an inflammatory disease associated with increased infiltration of leukocytes, especially eosinophils, and secretion of mucus into the airways. Although (S)-(+)-decursin, as well as (S)-(+)-decursin analogues, have various pharmacological properties, the effect of these compounds on asthma is not known. In the present study, we synthesized (S)-(+)-3-(3,4-dihydroxy-phenyl)-acrylic acid 2,2-dimethyl-8-oxo-3,4-dihydro-2H,8H-pyrano[3,2-g]chromen-3-yl-ester (compound 6, C6) from (S)-(+)-decursin and examined if C6 had any inhibitory effects on lung inflammation in a mouse model of ovalbumin-induced asthma. C6 significantly inhibited the leukocytosis (p < 0.01) and eosinophilia (p < 0.05) in bronchoalveolar lavage (BAL) fluid. Examination of lung tissues stained with hematoxylin and eosin and periodic acid Schiff reagents showed that C6 suppressed the increased infiltration of inflammatory cells and elevated mucus hypersecretion. Protein levels of interleukin (IL)-5 (p < 0.05) and eotaxin (p < 0.01) were significantly reduced in BAL fluid by C6. C6 also significantly reduced total and ovalbumin-specific immunoglobulin E (IgE) levels in BAL fluid (p < 0.01) as well as that in serum (p < 0.05). C6 may have pharmacological effects for asthma and may be a potent therapeutic agent for the treatment of allergic airway diseases.

40 CFR 721.10594 - Hexanedioic acid, polymer with 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol, hydrazine, 3-hydroxy...

Code of Federal Regulations, 2013 CFR

2013-07-01

... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10594...) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as...-173; CAS No. 1138156-39-4) is subject to reporting under this section for the significant new uses...

40 CFR 721.10594 - Hexanedioic acid, polymer with 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol, hydrazine, 3-hydroxy...

Code of Federal Regulations, 2014 CFR

2014-07-01

... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10594...) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as...-173; CAS No. 1138156-39-4) is subject to reporting under this section for the significant new uses...

Superstretchable, Self-Healing Polymeric Elastomers with Tunable Properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, Peng-Fei; Li, Bingrui; Hong, Tao

Utilization of self-healing chemistry to develop synthetic polymer materials that can heal themselves with restored mechanical performance and functionality is of great interest. Self-healable polymer elastomers with tunable mechanical properties are especially attractive for a variety of applications. In this paper, a series of urea functionalized poly(dimethyl siloxane)-based elastomers (U-PDMS-Es) are reported with extremely high stretchability, self-healing mechanical properties, and recoverable gas-separation performance. Tailoring the molecular weights of poly(dimethyl siloxane) or weight ratio of elastic cross-linker offers tunable mechanical properties of the obtained U-PDMS-Es, such as ultimate elongation (from 984% to 5600%), Young's modulus, ultimate tensile strength, toughness, and elasticmore » recovery. The U-PDMS-Es can serve as excellent acoustic and vibration damping materials over a broad range of temperature (over 100 °C). The strain-dependent elastic recovery behavior of U-PDMS-Es is also studied. After mechanical damage, the U-PDMS-Es can be healed in 120 min at ambient temperature or in 20 min at 40 °C with completely restored mechanical performance. Lastly, the U-PDMS-Es are also demonstrated to exhibit recoverable gas-separation functionality with retained permeability/selectivity after being damaged.« less

Superstretchable, Self-Healing Polymeric Elastomers with Tunable Properties

DOE PAGES

Cao, Peng-Fei; Li, Bingrui; Hong, Tao; ...

2018-04-16

Utilization of self-healing chemistry to develop synthetic polymer materials that can heal themselves with restored mechanical performance and functionality is of great interest. Self-healable polymer elastomers with tunable mechanical properties are especially attractive for a variety of applications. In this paper, a series of urea functionalized poly(dimethyl siloxane)-based elastomers (U-PDMS-Es) are reported with extremely high stretchability, self-healing mechanical properties, and recoverable gas-separation performance. Tailoring the molecular weights of poly(dimethyl siloxane) or weight ratio of elastic cross-linker offers tunable mechanical properties of the obtained U-PDMS-Es, such as ultimate elongation (from 984% to 5600%), Young's modulus, ultimate tensile strength, toughness, and elasticmore » recovery. The U-PDMS-Es can serve as excellent acoustic and vibration damping materials over a broad range of temperature (over 100 °C). The strain-dependent elastic recovery behavior of U-PDMS-Es is also studied. After mechanical damage, the U-PDMS-Es can be healed in 120 min at ambient temperature or in 20 min at 40 °C with completely restored mechanical performance. Lastly, the U-PDMS-Es are also demonstrated to exhibit recoverable gas-separation functionality with retained permeability/selectivity after being damaged.« less

Nanoimprinting-induced nanomorphological transition in polymer solar cells: enhanced electrical and optical performance.

PubMed

Jeong, Seonju; Cho, Changsoon; Kang, Hyunbum; Kim, Ki-Hyun; Yuk, Youngji; Park, Jeong Young; Kim, Bumjoon J; Lee, Jung-Yong

2015-03-24

We have investigated the effects of a directly nanopatterned active layer on the electrical and optical properties of inverted polymer solar cells (i-PSCs). The capillary force in confined molds plays a critical role in polymer crystallization and phase separation of the film. The nanoimprinting process induced improved crystallization and multidimensional chain alignment of polymers for more effective charge transfer and a fine phase-separation between polymers and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) to favor exciton dissociation and increase the generation rate of charge transfer excitons. Consequently, the power conversion efficiency with a periodic nanostructure was enhanced from 7.40% to 8.50% and 7.17% to 9.15% in PTB7 and PTB7-Th based i-PSCs, respectively.

Lipase catalyzed epoxidation of fatty acid methyl esters derived from unsaturated vegetable oils in absence of carboxylic acid.

PubMed

Sustaita-Rodríguez, Alejandro; Ramos-Sánchez, Víctor H; Camacho-Dávila, Alejandro A; Zaragoza-Galán, Gerardo; Espinoza-Hicks, José C; Chávez-Flores, David

2018-04-11

Nowadays the industrial chemistry reactions rely on green technologies. Enzymes as lipases are increasing its use in diverse chemical processes. Epoxidized fatty acid methyl esters obtained from transesterification of vegetable oils have recently found applications as polymer plasticizer, agrochemical, cosmetics, pharmaceuticals and food additives. In this research article, grapeseed, avocado and olive oils naturally containing high percents of mono and poly unsaturations were used as starting materials for the production of unsaturated fatty acid methyl esters. The effect of lauric acid as an active oxygen carrier was studied on epoxidation reactions where unsaturated fatty acid methyl esters were converted to epoxy fatty acid methyl esters using immobilized Candida antarctica Lipase type B as catalyst and hydrogen peroxide as oxygen donor at mild temperature and pressure conditions. After this study it was confirmed by 1 H NMR, 13 C NMR and GC-MS that the addition of lauric acid to the enzymatic reaction is unnecessary to transform the alkenes in to epoxides. It was found that quantitative conversions were possible in despite of a carboxylic acid absence.

Photorefractive performance of polymer composite sensitized by CdSe nanoparticles passivated by 1-hexadecylamine

NASA Astrophysics Data System (ADS)

Aslam, Farzana; Binks, David J.; Rahn, Mark D.; West, David P.; O'Brien, Paul; Pickett, Nigel

2005-07-01

The performance of a photorefractive polymer composite sensitized by 1-hexadecylamine capped CdSe nanoparticles is reported. The polymer composite also comprises the charge transporting matrix poly(N-vinylcarbazole) and the electro-optic chromophore 1-(2-ethylhexyloxy)-2,5-dimethyl-4-(4-nitrophenylazo) benzene. At an applied field of 70?V?µ m-1 two beam coupling gain of 13.2?cm-1 was observed, confirming the photorefractive nature of the induced grating. At the same field, a holographic contrast of 9.12×10-4±6×10-6, a photorefractive sensitivity of 5.1×10-4 ±0.2×10-4?cm3?J-1 and a space-charge field rise time of 13±1?s were obtained.

Kinetic evaluation and process performance of a fixed film bioreactor removing phthalic acid and dimethyl phthalate.

PubMed

Pirsaheb, Meghdad; Mesdaghinia, Ali-Reza; Shahtaheri, Seyed Jamaleddin; Zinatizadeh, Ali Akbar

2009-08-15

Phthalate esters are toxic organic contaminants which can enter into the environment through various industrial processes. In this study, a 6-liter fixed film bioreactor was used to examine biodegradation of phthalic acid (PA) and dimethyl phthalate (DMP) in synthetic wastewater. Effect on the process of two operating factors, namely hydraulic retention time (HRT) (at four levels ranging between 6 and 48 h) and initial phthalate concentrations (at six levels ranging from 10mg to 500 mg/l), was investigated. The process was stable at all operating conditions, except for the condition with influent PA and DMP of 500 mg/l and HRT of 6h. More than 95% removal efficiency was achieved for the conditions with HRT longer than 10h. Remarkable amount of DMP (398 mg/kg of sludge) was adsorbed on the biomass due to its higher hydrophobicity compared to PA (171 mg/kg). The kinetic parameters (mu(m,)K(s), Y and K(d)) were determined and compared for both substrates, PA and DMP.

Design, synthesis and evaluation of dialkyl 4-(benzo[d][1,3]dioxol-6-yl)-1,4-dihydro-2,6-dimethyl-1-substituted pyridine-3,5-dicarboxylates as potential anticonvulsants and their molecular properties prediction.

PubMed

Prasanthi, G; Prasad, K V S R G; Bharathi, K

2013-08-01

The present study is on the development of dialkyl 4-(benzo[d][1,3]dioxol-6-yl)-1,4-dihydro-2,6-dimethyl-1-substituted pyridine-3,5-dicarboxylate derivatives as isosteric analogues of isradipine and nifedipine, by the replacement of benzofurazanyl and 2-nitrophenyl groups respectively with benzo[d][1,3]dioxo-6-yl group, as potential anticonvulsants. Fivfteen new derivatives (8a-8o) were synthesized and tested for anticonvulsant activity using maximal electroshock and subcutaneous pentylenetetrazole induced seizure methods. Compound 8f possessing free NH group in 1,4-dihydropyridine ring, diethyl ester functionality at the positions 3 and 5 showed significant anticonvulsant and antioxidant activities. This was also supported by molecular properties prediction data. Selected compounds were evaluated for antinociceptive activity in capsaicin induced nociception assay at 10 mg/kg body weight, but displayed no significant activity at the tested dose. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

On the hydrophilicity of polyzwitterion poly (N,N-dimethyl-N-(3-(methacrylamido)propyl)ammoniopropane sulfonate) in water, deuterated water, and aqueous salt solutions.

PubMed

Hildebrand, Viet; Laschewsky, André; Zehm, Daniel

2014-01-01

A series of zwitterionic model polymers with defined molar masses up to 150,000 Da and defined end groups are prepared from sulfobetaine monomer N,N-dimethyl-N-(3-(methacrylamido)propyl)ammoniopropanesulfonate (SPP). Polymers are synthesized by reversible addition-fragmentation chain transfer polymerization (RAFT) using a functional chain transfer agent labeled with a fluorescent probe. Their upper critical solution temperature-type coil-to-globule phase transition in water, deuterated water, and various salt solutions is studied by turbidimetry. Cloud points increase with polyzwitterion concentration and molar mass, being considerably higher in D2O than in H2O. Moreover, cloud points are strongly affected by the amount and nature of added salts. Typically, they increase with increasing salt concentration up to a maximum value, whereas further addition of salt lowers the cloud points again, mostly down to below freezing point. The different salting-in and salting-out effects of the studied anions can be correlated with the Hofmeister series. In physiological sodium chloride solution and in phosphate buffered saline (PBS), the cloud point is suppressed even for high molar mass samples. Accordingly, SPP-polymers behave strongly hydrophilic under most conditions encountered in biomedical applications. However, the direct transfer of results from model studies in D2O, using, e.g. (1)H NMR or neutron scattering techniques, to 'normal' systems in H2O is not obvious.

Electrically conductive polymer concrete coatings

DOEpatents

Fontana, J.J.; Elling, D.; Reams, W.

1988-05-26

A sprayable electrically conductive polymer concrete coating for vertical and overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt% calcined coke breeze, 40 wt% vinyl ester resin with 3.5 wt% modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag. 4 tabs.

Functionalised graphene sheets as effective high dielectric constant fillers

PubMed Central

2011-01-01

A new functionalised graphene sheet (FGS) filled poly(dimethyl)siloxane insulator nanocomposite has been developed with high dielectric constant, making it well suited for applications in flexible electronics. The dielectric permittivity increased tenfold at 10 Hz and 2 wt.% FGS, while preserving low dielectric losses and good mechanical properties. The presence of functional groups on the graphene sheet surface improved the compatibility nanofiller/polymer at the interface, reducing the polarisation process. This study demonstrates that functionalised graphene sheets are ideal nanofillers for the development of new polymer composites with high dielectric constant values. PACS: 78.20.Ci, 72.80.Tm, 62.23.Kn PMID:21867505

Functionalised graphene sheets as effective high dielectric constant fillers

NASA Astrophysics Data System (ADS)

Romasanta, Laura J.; Hernández, Marianella; López-Manchado, Miguel A.; Verdejo, Raquel

2011-08-01

A new functionalised graphene sheet (FGS) filled poly(dimethyl)siloxane insulator nanocomposite has been developed with high dielectric constant, making it well suited for applications in flexible electronics. The dielectric permittivity increased tenfold at 10 Hz and 2 wt.% FGS, while preserving low dielectric losses and good mechanical properties. The presence of functional groups on the graphene sheet surface improved the compatibility nanofiller/polymer at the interface, reducing the polarisation process. This study demonstrates that functionalised graphene sheets are ideal nanofillers for the development of new polymer composites with high dielectric constant values. PACS: 78.20.Ci, 72.80.Tm, 62.23.Kn

Michael Addition Polymerization of Trifunctional Amine and Acrylic Monomer: A Versatile Platform for Development of Biomaterials.

PubMed

Cheng, Weiren; Wu, Decheng; Liu, Ye

2016-10-10

Michael addition polymerizations of amines and acrylic monomers are versatile approaches to biomaterials for various applications. A combinatorial library of poly(β-amino ester)s and diverse poly(amido amine)s from diamines and diacrylates or bis(acrylamide)s have been reported, respectively. Furthermore, novel linear and hyperbranched polymers from Michael addition polymerizations of trifunctional amines and acrylic monomers significantly enrich this category of biomaterials. In this Review, we focus on the biomaterials from Michael addition polymerizations of trifunctional amines and acrylic monomers. First we discuss how the polymerization mechanisms, which are determined by the reactivity sequence of the three types of amines of trifunctional amines, i.e., secondary (2°) amines (original), primary (1°) amines, and 2° amines (formed), are affected by the chemistry of monomers, reaction temperature, and solvent. Then we update how to design and synthesize linear and hyperbranched polymers based on the understanding of polymerization mechanisms. Linear polymers containing 2° amines in the backbones can be obtained from polymerizations of diacrylates or bis(acrylamide)s with equimolar trifunctional amine, and several approaches, e.g., 2A 2 +BB'B″, A 3 +2BB'B', A 2 +BB'B″, to hyperbranched polymers are developed. Further through molecular design of monomers, conjugation of functional species to 2° amines in the backbones of linear polymers and the abundant terminal groups of hyperbranched polymers, the amphiphilicity of polymers can be adjusted, and additional stimuli, e.g., thermal, redox, reactive oxidation species (ROS), and light, responses can be integrated with the intrinsic pH response. Finally we discuss the applications of the polymers for gene/drug delivery and bioimaging through exploring their self-assemblies in various motifs, e.g., micelles, polyplexes particles/nanorings and hydrogels. Redox-responsive hyperbranched polymers can display 300 times higher in vitro gene transfection efficiency and provide a higher in vivo siRNA efficacy than PEI. Also redox-responsive micelle carriers can improve the efficacy of anticancer drug and the bioimaging contrast. Further molecular design and optimization of this category of polymers together with in vivo studies should provide safe and efficient biomaterials for clinical applications.

Structural characterization of saturated branched chain fatty acid methyl esters by collisional dissociation of molecular ions generated by electron ionization.

PubMed

Ran-Ressler, Rinat R; Lawrence, Peter; Brenna, J Thomas

2012-01-01

Saturated branched chain fatty acids (BCFA) are present as complex mixtures in numerous biological samples. The traditional method for structure elucidation, electron ionization (EI) mass spectrometry, sometimes does not unambiguously enable assignment of branching in isomeric BCFA. Zirrolli and Murphy (Zirrolli , J. A. , and R. A. Murphy. 1993. Low-energy tandem mass spectrometry of the molecular ion derived from fatty acid methyl esters: a novel method for analysis of branched-chain fatty acids. J. Am. Soc. Mass Spectrom. 4: 223-229.) showed that the molecular ions of four BCFA methyl ester (BCFAME) yield highly characteristic fragments upon collisional dissociation using a triple quadrupole instrument. Here, we confirm and extend these results by analysis using a tabletop 3-D ion trap for activated molecular ion EI-MS/MS to 30 BCFAME. iso-BCFAME produces a prominent ion (30-100% of base peak) for [M-43] (M-C₃H₇), corresponding to the terminal isopropyl moiety in the original iso-BCFAME. Anteiso-FAME yield prominent ions (20-100% of base peak) corresponding to losses on both side of the methyl branch, [M-29] and [M-57], and tend to produce more prominent m/z 115 peaks corresponding to a cyclization product around the ester. Dimethyl and tetramethyl FAME, with branches separated by at least one methylene group, yield fragment on both sides of the sites of methyl branches that are more than 6 C away from the carboxyl carbon. EI-MS/MS yields uniquely specific ions that enable highly confident structural identification and quantification of BCFAME.

Structural characterization of saturated branched chain fatty acid methyl esters by collisional dissociation of molecular ions generated by electron ionization[S

PubMed Central

Ran-Ressler, Rinat R.; Lawrence, Peter; Brenna, J. Thomas

2012-01-01

Saturated branched chain fatty acids (BCFA) are present as complex mixtures in numerous biological samples. The traditional method for structure elucidation, electron ionization (EI) mass spectrometry, sometimes does not unambiguously enable assignment of branching in isomeric BCFA. Zirrolli and Murphy (Zirrolli , J. A. , and R. A. Murphy. 1993. Low-energy tandem mass spectrometry of the molecular ion derived from fatty acid methyl esters: a novel method for analysis of branched-chain fatty acids. J. Am. Soc. Mass Spectrom. 4: 223–229.) showed that the molecular ions of four BCFA methyl ester (BCFAME) yield highly characteristic fragments upon collisional dissociation using a triple quadrupole instrument. Here, we confirm and extend these results by analysis using a tabletop 3-D ion trap for activated molecular ion EI-MS/MS to 30 BCFAME. iso-BCFAME produces a prominent ion (30-100% of base peak) for [M-43] (M-C3H7), corresponding to the terminal isopropyl moiety in the original iso-BCFAME. Anteiso-FAME yield prominent ions (20-100% of base peak) corresponding to losses on both side of the methyl branch, [M-29] and [M-57], and tend to produce more prominent m/z 115 peaks corresponding to a cyclization product around the ester. Dimethyl and tetramethyl FAME, with branches separated by at least one methylene group, yield fragment on both sides of the sites of methyl branches that are more than 6 C away from the carboxyl carbon. EI-MS/MS yields uniquely specific ions that enable highly confident structural identification and quantification of BCFAME. PMID:22021637

Poly(organo phosphazene) nanoparticles surface modified with poly(ethylene oxide).

PubMed

Vandorpe, J; Schacht, E; Stolnik, S; Garnett, M C; Davies, M C; Illum, L; Davis, S S

1996-10-05

The use of biodegradable derivatives of poly(organo phosphazenes) for the preparation of nanoparticles and their surface modification with the novel poly(ethylene oxide) derivative of poly(organo phosphazene) has been assessed using a range of in vitro characterization methods. The nanoparticles were produced by the precipitation solvent evaporation method from the derivative co-substituted with phenylalanine and glycine ethyl ester side groups. A reduction in particle size to less than 200 nm was achieved by an increase in pH of the preparation medium. The formation (and colloidal stability) of these nanoparticles seems to be controlled by two opposite effects: attractive hydrophobic interactions between phenylalanine ester groups and electrostatic repulsions arising from the carboxyl groups formed due to (partial) hydrolysis of the ester bond(s) at the high pH of the preparation medium. The poly[(glycine ethyl ester)phosphazene] derivative containing 5000-Da poly(ethylene oxide) as 5% of the side groups was used for the surface modification of nanoparticles. Adsorbed onto the particles, the polymer produced a thick coating layer of approximately 35 nm. The coated nanoparticles exhibited reduced surface negative potential and improved colloidal stability toward electrolyte-induced flocculation, relative to the uncoated system. However, the steric stabilization provided was less effective than that of a Poloxamine 908 coating. This difference in effectiveness of the steric stabilization might indicate that, although both the stabilizing polymers possess a 5000-Da poly(ethylene oxide) moiety, there is a difference in the arrangements of these poly(ethylene oxide) chains at the particle surface. (c) 1996 John Wiley & Sons, Inc.

Catalytic asymmetric ring-opening of meso-aziridines with malonates under heterodinuclear rare earth metal Schiff base catalysis.

PubMed

Xu, Yingjie; Lin, Luqing; Kanai, Motomu; Matsunaga, Shigeki; Shibasaki, Masakatsu

2011-04-20

Catalytic asymmetric ring-opening of meso-aziridines with malonates is described. The combined use of two rare earth metal sources with different properties promoted the desired ring-opening reaction. A 1:1:1 mixture of a heterobimetallic La(O-iPr)(3)/Yb(OTf)(3)/Schiff base 1a (0.25-10 mol %) efficiently promoted the reaction of five-, six-, and seven-membered ring cyclic meso-aziridines as well as acyclic meso-aziridines with dimethyl, diethyl, and dibenzyl malonates, giving chiral cyclic and acyclic γ-amino esters in 99-63% yield and >99.5-97% ee.

Preparation and electrochemical characterization of gel polymer electrolyte based on electrospun polyacrylonitrile nonwoven membranes for lithium batteries

NASA Astrophysics Data System (ADS)

Raghavan, Prasanth; Manuel, James; Zhao, Xiaohui; Kim, Dul-Sun; Ahn, Jou-Hyeon; Nah, Changwoon

Electrospun membranes of polyacrylonitrile are prepared, and the electrospinning parameters are optimized to get fibrous membranes with uniform bead-free morphology. The polymer solution of 16 wt.% in N, N-dimethylformamide at an applied voltage of 20 kV results in the nanofibrous membrane with average fiber diameter of 350 nm and narrow fiber diameter distribution. Gel polymer electrolytes are prepared by activating the nonwoven membranes with different liquid electrolytes. The nanometer level fiber diameter and fully interconnected pore structure of the host polymer membranes facilitate easy penetration of the liquid electrolyte. The gel polymer electrolytes show high electrolyte uptake (>390%) and high ionic conductivity (>2 × 10 -3 S cm -1). The cell fabricated with the gel polymer electrolytes shows good interfacial stability and oxidation stability >4.7 V. Prototype coin cells with gel polymer electrolytes based on a membrane activated with 1 M LiPF 6 in ethylene carbonate/dimethyl carbonate or propylene carbonate are evaluated for discharge capacity and cycle property in Li/LiFePO 4 cells at room temperature. The cells show remarkably good cycle performance with high initial discharge properties and low capacity fade under continuous cycling.

Weak-link capacitor

DOEpatents

Dirk, Shawn M [Albuquerque, NM; Johnson, Ross S [Albuquerque, NM; Wheeler, David R [Albuquerque, NM; Bogart, Gregory R [Corrales, NM

2011-06-07

A process for making a dielectric material where a precursor polymer selected from poly(phenylene vinylene) polyacetylene, poly(p-phenylene), poly(thienylene vinylene), poly(1,4-naphthylene vinylene), and poly(p-pyridine vinylene) is energized said by exposure by radiation or increase in temperature to a level sufficient to eliminate said leaving groups contained within the precursor polymer, thereby transforming the dielectric material into a conductive polymer. The leaving group in the precursor polymer can be a chloride, a bromide, an iodide, a fluoride, an ester, an xanthate, a nitrile, an amine, a nitro group, a carbonate, a dithiocarbamate, a sulfonium group, an oxonium group, an iodonium group, a pyridinium group, an ammonium group, a borate group, a borane group, a sulphinyl group, or a sulfonyl group.

Weak-link capacitor

DOEpatents

Dirk, Shawn M.; Johnson, Ross S.; Wheeler, David R.; Bogart, Gregory R.

2013-04-23

A process for making a dielectric material where a precursor polymer selected from poly(phenylene vinylene)polyacetylene, poly(p-phenylene), poly(thienylene vinylene), poly(1,4-naphthylene vinylene), and poly(p-pyridine vinylene) is energized said by exposure by radiation or increase in temperature to a level sufficient to eliminate said leaving groups contained within the precursor polymer, thereby transforming the dielectric material into a conductive polymer. The leaving group in the precursor polymer can be a chloride, a bromide, an iodide, a fluoride, an ester, an xanthate, a nitrile, an amine, a nitro group, a carbonate, a dithiocarbamate, a sulfonium group, an oxonium group, an iodonium group, a pyridinium group, an ammonium group, a borate group, a borane group, a sulphinyl group, or a sulfonyl group.

Alternative Thieno[3,2-b][1]benzothiophene Isoindigo Polymers for Solar Cell Applications.

PubMed

Neophytou, Marios; Bryant, Daniel; Lopatin, Sergei; Chen, Hu; Hallani, Rawad K; Cater, Lewis; McCulloch, Iain; Yue, Wan

2018-03-05

This work reports the synthesis, characterization, photophysical, and photovoltaic properties of five new thieno[3,2-b][1]benzothiophene isoindigo (TBTI)-containing low bandgap donor-acceptor conjugated polymers with a series of comonomers and different side chains. When TBTI is combined with different electron-rich moieties, even small structural variations can have significant impact on thin film morphology of the polymer:phenyl C70 butyric acid methyl ester (PCBM) blends. More importantly, high-resolution electron energy loss spectroscopy is used to investigate the phase-separated bulk heterojunction domains, which can be accurately and precisely resolved, enabling an enhanced correlation between polymer chemical structure, photovoltaic device performance, and morphology. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface charge tunability as a powerful strategy to control electrostatic interaction for high efficiency silencing, using tailored oligopeptide-modified poly(beta-amino ester)s (PBAEs).

PubMed

Dosta, Pere; Segovia, Nathaly; Cascante, Anna; Ramos, Victor; Borrós, Salvador

2015-07-01

Here we present an extended family of pBAEs that incorporate terminal oligopeptide moieties synthesized from both positive and negative amino acids. Polymer formulations of mixtures of negative and positive oligopeptide-modified pBAEs are capable of condensing siRNA into discrete nanoparticles. We have demonstrated that efficient delivery of nucleic acids in a cell-type dependent manner can be achieved by careful control of the pBAE formulation. In addition, our approach of adding differently charged oligopeptides to the termini of poly(β-amino ester)s is of great interest for the design of tailored complexes having specific features, such as tuneable zeta potential. We anticipate that this surface charge tunability may be a powerful strategy to control unwanted electrostatic interactions, while preserving high silencing efficiency and reduced toxicity. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Waterborne Polymeric Films.

DTIC Science & Technology

1981-02-01

polymer of neopentyl glycol (NPC) and isophoronediisocyanate (IPDI) as an example: CH 3 0 CH3 0 CH- HO !Ch,,C h OCNH CH.NHCO, HCCH.OH CIF CH- Groun...copolymer of isophoronediisocyanate with neopentyl glycol and dimethylolpropionic acid. And the solibilitv parameter calculations must include this...copolymer of isophoronediiisocyanate with a diol mixture of 85 inol percent neopentyl glycol and 15 inol percent dimethyl- olpropionic acid. 0 0 0 it 0

Bio-based production of methacrylic acid

USDA-ARS?s Scientific Manuscript database

Methacrylic acid (MAA) is an important industrial chemical commodity, with annual production exceeding 3 million metric tons and a market value surpassing $9 billion. The primary use of MAA is the conversion to ester derivatives, which are further converted into numerous useful polymers. Despite the...

Evaluation of weed control efficacy and crop safety of the new HPPD-inhibiting herbicide-QYR301.

PubMed

Wang, Hengzhi; Liu, Weitang; Zhao, Kongping; Yu, Hui; Zhang, Jia; Wang, Jinxin

2018-05-21

QYR301, 1,3-Dimethyl-1H-pyrazole-4-carboxylic acid 4-[2-chloro-3-(3,5-dimethyl-pyrazol-1-ylmethyl)-4-methanesulfonyl-benzoyl]-2,5-dimethyl-2H-pyrazol-3-yl ester, is a novel HPPD-inhibiting herbicide and was evaluated to provide a reference for post-emergence (POST) application under greenhouse and field conditions. The crop safety (180 and 360 g active ingredient (a.i.) ha -1 treatments) experiment revealed that wheat, paddy, garlic and corn were the only four crops without injury at both examined herbicide rates. The weed control efficacy (60 and 120 g a.i. ha -1 ) experiment showed that QYR301 exhibited high efficacy against many weeds, especially weeds infesting paddy fields. Furthermore, it is interesting that both susceptible and multiple herbicide resistant Echinochloa crus-galli (L.) Beauv. and Echinochloa phyllopogon (Stapf) Koss, two notorious weed species in paddy field, remained susceptible to QYR301. Further crop tolerance results indicated that 20 tested paddy hybrids displayed different levels of tolerance to QYR301, with the japonica paddy hybrids having more tolerance than indica paddy hybrids under greenhouse conditions. Results obtained from field experiments showed that QYR301 POST at 135 to 180 g a.i. ha -1 was recommended to provide satisfactory full-season control of E. crus-galli and Leptochloa chinensis (L.) Nees and to maximize rice yields. These findings indicate that QYR301 possesses great potential for the management of weeds in paddy fields.

Ingasaponin, a complex triterpenoid saponin with immunological adjuvant activity from Inga laurina.

PubMed

Cruz, Maria de Fátima Simão Jucá; Pereira, Gabriela Moysés; Ribeiro, Marcela Gonçalves; da Silva, Ari Miranda; Tinoco, Luzineide Wanderley; da Silva, Bernadete Pereira; Parente, José Paz

2016-02-01

As part of our search of bioactive saponins from Brazilian plants, phytochemical study of the seeds of Inga laurina led to the isolation of a new complex triterpenoid saponin, named ingasaponin. It is the first saponin isolated from a species of Inga genus. It was isolated by using chromatographic methods and its structural elucidation was performed using detailed analyses of (1)H and (13)C NMR spectra including 2D-NMR spectroscopic techniques and chemical conversions. Its structure was established as 21-[[(2E,6S)-6-[[6-deoxy-4-O-[(2E,6S)-6-[(β-D-glucopyranosyl)oxy]-2,6-dimethyl-1-oxo-2,7-octadienyl]-[(β-D-glucopyranosyl)oxy]-2,6-dimethyl-1-oxo-2,7-octadienyl]-[(β-D-glucopyranosyl)oxy]-2,6-dimethyl-1-oxo-2,7-octadienyl]-[(β-D-glucopyranosyl)oxy]-2-(hydroxymethyl)-6-methyl-1-oxo-2,7-octadienyl]oxy]-16-hydroxy-3-[[O-β-D-xylopyranosyl-(1 → 2)-O-α-L-arabinopyranosyl-(1 → 6)-2-(acetylamino)-2-deoxy-β-D-glucopyranosyl]oxy]-(3β,16α,21β)-olean-12-en-28-oic acid O-α-L-arabinofuranosyl-(1 → 4)-O-[β-D-glucopyranosyl-(1 → 3)]-O-6-deoxy-α-L-mannopyranosyl-(1 → 2)-β-D-glucopyranosyl ester (1). The hemolytic potential of 1 was evaluated using in vitro assays, and its adjuvant activity on the cellular immune response against ovalbumin antigen was investigated using in vivo models. Copyright © 2015 Elsevier Ltd. All rights reserved.

Cannabidiol-2',6'-dimethyl ether, a cannabidiol derivative, is a highly potent and selective 15-lipoxygenase inhibitor.

PubMed

Takeda, Shuso; Usami, Noriyuki; Yamamoto, Ikuo; Watanabe, Kazuhito

2009-08-01

The inhibitory effect of nordihydroguaiaretic acid (NDGA) (a nonselective lipoxygenase (LOX) inhibitor)-mediated 15-LOX inhibition has been reported to be affected by modification of its catechol ring, such as methylation of the hydroxyl group. Cannabidiol (CBD), one of the major components of marijuana, is known to inhibit LOX activity. Based on the phenomenon observed in NDGA, we investigated whether or not methylation of CBD affects its inhibitory potential against 15-LOX, because CBD contains a resorcinol ring, which is an isomer of catechol. Although CBD inhibited 15-LOX activity with an IC(50) value (50% inhibition concentration) of 2.56 microM, its monomethylated and dimethylated derivatives, CBD-2'-monomethyl ether and CBD-2',6'-dimethyl ether (CBDD), inhibited 15-LOX activity more strongly than CBD. The number of methyl groups in the resorcinol moiety of CBD (as a prototype) appears to be a key determinant for potency and selectivity in inhibition of 15-LOX. The IC(50) value of 15-LOX inhibition by CBDD is 0.28 microM, and the inhibition selectivity for 15-LOX (i.e., the 5-LOX/15-LOX ratio of IC(50) values) is more than 700. Among LOX isoforms, 15-LOX is known to be able to oxygenate cholesterol esters in the low-density lipoprotein (LDL) particle (i.e., the formation of oxidized LDL). Thus, 15-LOX is suggested to be involved in development of atherosclerosis, and CBDD may be a useful prototype for producing medicines for atherosclerosis.

Alternative High Performance Polymers for Ablative Thermal Protection Systems

NASA Technical Reports Server (NTRS)

Boghozian, Tane; Stackpoole, Mairead; Gonzales, Greg

2015-01-01

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

Synthesis of High Molecular Weight Para-Phenylene PBI

DTIC Science & Technology

1974-11-01

acid , and the viscous material stirred at 1500 under nitrogen for 3 hours. The flask was then cooled in ice, opened, and 2 g (6.56 mole) of 2 -[p...11 1. Monomers 11 2 . Polymers 18 0 V REFERENCES 23 ILLUSTRATIONS FIGURE PAGE 1. X-RAY DIFFRACTION PATTERN OF ACID INSOLUBLE POLYMER 24 2 . X-RAY...solvents. Other acid derivatives such as esters, amides, and nitriles were also employed as monomers with the same results. NH 2 ,NH 2 - 4HCI + 1- I NH2

A new hypercrosslinked supermicroporous polymer, with scope for sulfonation, and its catalytic potential for the efficient synthesis of biodiesel at room temperature.

PubMed

Bhunia, Subhajit; Banerjee, Biplab; Bhaumik, Asim

2015-03-25

We have designed a new hypercrosslinked supermicroporous polymer (HMP-1) with a BET surface area of 913 m(2) g(-1) by FeCl3 via a catalyzed Friedel-Crafts alkylation reaction between carbazole and α,α'-dibromo-p-xylene. Upon sulfonation HMP-1 yielded a very efficient solid acid catalyst for the production of biodiesels via esterification/transesterification of free fatty acids (FFA)/esters at room temperature.

A Wide Band Gap Polymer with a Deep Highest Occupied Molecular Orbital Level Enables 14.2% Efficiency in Polymer Solar Cells.

PubMed

Li, Sunsun; Ye, Long; Zhao, Wenchao; Yan, Hongping; Yang, Bei; Liu, Delong; Li, Wanning; Ade, Harald; Hou, Jianhui

2018-05-21

To simultaneously achieve low photon energy loss ( E loss ) and broad spectral response, the molecular design of the wide band gap (WBG) donor polymer with a deep HOMO level is of critical importance in fullerene-free polymer solar cells (PSCs). Herein, we developed a new benzodithiophene unit, i.e., DTBDT-EF, and conducted systematic investigations on a WBG DTBDT-EF-based donor polymer, namely, PDTB-EF-T. Due to the synergistic electron-withdrawing effect of the fluorine atom and ester group, PDTB-EF-T exhibits a higher oxidation potential, i.e., a deeper HOMO level (ca. -5.5 eV) than most well-known donor polymers. Hence, a high open-circuit voltage of 0.90 V was obtained when paired with a fluorinated small molecule acceptor (IT-4F), corresponding to a low E loss of 0.62 eV. Furthermore, side-chain engineering demonstrated that subtle side-chain modulation of the ester greatly influences the aggregation effects and molecular packing of polymer PDTB-EF-T. With the benefits of the stronger interchain π-π interaction, the improved ordering structure, and thus the highest hole mobility, the most symmetric charge transport and reduced recombination are achieved for the linear decyl-substituted PDTB-EF-T (P2)-based PSCs, leading to the highest short-circuit current density and fill factor (FF). Due to the high Flory-Huggins interaction parameter (χ), surface-directed phase separation occurs in the P2:IT-4F blend, which is supported by X-ray photoemission spectroscopy results and cross-sectional transmission electron microscope images. By taking advantage of the vertical phase distribution of the P2:IT-4F blend, a high power conversion efficiency (PCE) of 14.2% with an outstanding FF of 0.76 was recorded for inverted devices. These results demonstrate the great potential of the DTBDT-EF unit for future organic photovoltaic applications.

Fumaric Acid Esters Do Not Reduce Inflammatory NF-κB/p65 Nuclear Translocation, ICAM-1 Expression and T-Cell Adhesiveness of Human Brain Microvascular Endothelial Cells.

PubMed

Haarmann, Axel; Nehen, Mathias; Deiß, Annika; Buttmann, Mathias

2015-08-13

Dimethyl fumarate (DMF) is approved for disease-modifying treatment of patients with relapsing-remitting multiple sclerosis. Animal experiments suggested that part of its therapeutic effect is due to a reduction of T-cell infiltration of the central nervous system (CNS) by uncertain mechanisms. Here we evaluated whether DMF and its primary metabolite monomethyl fumarate (MMF) modulate pro-inflammatory intracellular signaling and T-cell adhesiveness of nonimmortalized single donor human brain microvascular endothelial cells at low passages. Neither DMF nor MMF at concentrations of 10 or 50 µM blocked the IL-1β-induced nuclear translocation of NF-κB/p65, whereas the higher concentration of DMF inhibited the nuclear entry of p65 in human umbilical vein endothelium cultured in parallel. DMF and MMF also did not alter the IL-1β-stimulated activation of p38 MAPK in brain endothelium. Furthermore, neither DMF nor MMF reduced the basal or IL-1β-inducible expression of ICAM-1. In accordance, both fumaric acid esters did not reduce the adhesion of activated Jurkat T cells to brain endothelium under basal or inflammatory conditions. Therefore, brain endothelial cells probably do not directly mediate a potential blocking effect of fumaric acid esters on the inflammatory infiltration of the CNS by T cells.

Slow-injection ultrasound-assisted emulsification-microextraction for determination of phthalate esters in water.

PubMed

Li, Songqing; Li, Tong; Gao, Peng; Lu, Runhua; Zhou, Wenfeng; Gao, Haixiang

2014-10-01

A type of ultrasound-assisted emulsification-microextraction (USAEME) was applied for the extraction and determination of four phthalate esters (e.g., dimethyl phthalate, diethyl phthalate, dibutyl phthalate and benzyl butyl phthalate) in aqueous samples prior to quantification using HPLC-UV. The simultaneous injection of the extraction solvent and ultrasonication of the mixture results in an efficient extraction with the extractant well-dispersed in the sample. The parameters affecting the experimental results were analyzed and optimized through the design of the experiment. Using a central composite face-centered design, the results of 28 experimental data points were analyzed and validated. An optimal set of operating conditions was obtained using 40 μL of 1,1,2,2-tetrachloroethane and 1% NaCl subjected to 2.0 min of ultrasonication under natural pH. Under optimized conditions, the extractions resulted in analyte recoveries of 75-87% and high enrichment factors of 356-415. The calibration curves were linear, and the correlation coefficients ranged from 0.9992 to 0.9997 at concentrations of 5 to 300 μg L(-1). The RSDs (n = 5) were 5.6-7.9%. The limits of detection for the four phthalate esters ranged from 0.26 to 1.46 μg L(-1). © The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

21 CFR 175.210 - Acrylate ester copolymer coating.

Code of Federal Regulations, 2014 CFR

2014-04-01

... polymerized copolymer of ethyl acrylate, methyl methacrylate, and methacrylic acid applied in emulsion form to... of the polymer and in the preparation and application of the emulsion may include substances named in... amount required as a preservative in emulsion defoamer. Disodium hydrogen phosphate Do. Formaldehyde...

Diketopyrrolopyrrole-based polymer:fullerene nanoparticle films with thermally stable morphology for organic photovoltaic applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holmes, Natalie P.; Vaughan, Ben; Williams, Evan L.

Polymer:fullerene nanoparticles (NPs) offer two key advantages over bulk heterojunction (BHJ) films for organic photovoltaics (OPVs), water-processability and potentially superior morphological control. Once an optimal active layer morphology is reached, maintaining this morphology at OPV operating temperatures is key to the lifetime of a device. Here in this paper we study the morphology of the PDPP-TNT (poly{3,6-dithiophene-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-naphthalene}):PC 71BM ([6,6]-phenyl C 71 butyric acid methyl ester) NP system and then compare the thermal stability of NP and BHJ films to the common poly(3-hexylthiophene) (P3HT): phenyl C 61 butyric acid methyl ester (PC 61BM) system. We find that material T g playsmore » a key role in the superior thermal stability of the PDPP-TNT:PC 71BM system; whereas for the P3HT:PC 61BM system, domain structure is critical.« less

Mussel-inspired hyperbranched poly(amino ester) polymer as strong wet tissue adhesive.

PubMed

Zhang, Hong; Bré, Lígia P; Zhao, Tianyu; Zheng, Yu; Newland, Ben; Wang, Wenxin

2014-01-01

Current medical adhesives based on cyanoacrylates typically exhibit cellular toxicity. In contrast, fibrin adhesives are non-toxic but have poor adhesive properties. To overcome these drawbacks we designed a simple and scalable adhesive precursor inspired by marine mussel adhesion that functioned with strong adhesion in wet conditions and with low cytotoxicity. Dopamine, an-amine derivative of an amino acid abundantly present in mussel adhesive proteins, was co-polymerised with a tri-functional vinyl monomer, to form a hyperbranched poly(β-amino ester) polymer termed poly(dopamine-co-acrylate) (PDA). A variety of molecular weights and crosslinking methods were analysed using an ex vivo porcine skin model and an almost 4 fold increase in wet adhesion strength was observed compared to TISSEEL(®) fibrin sealant. With a fast curing time, degradable properties and low cytotoxicity, PDA is highly attractive for medical purposes and could have a broad impact on surgeries where surgical tissue adhesives, sealants, and haemostatic agents are used. Copyright © 2013 Elsevier Ltd. All rights reserved.

Photophysics and morphology of poly (3-dodecylthienylenevinylene)-[6,6]-phenyl-C{sub 61}-butyric acid methyl ester composite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lafalce, E.; Toglia, P.; Jiang, X.

2012-05-21

A series of low band gap poly(3-dodecylthienylenevinylene) (PTV) with controlled morphological order have been synthesized and blended with the electron acceptor [6,6]-phenyl-C{sub 61}-butyric acid methyl ester (PCBM) for organic photovoltaic devices. Two polymers with the most and least side chain regioregularity were chosen in this work, namely the PTV010 and PTV55, respectively. Using photoluminescence, photo-induced absorption spectroscopy, and atomic force microscopy, we find no direct evidence of photoinduced charge transfer between the two constituents, independent of the bulk-heterojunction morphology of the film, although the possibility of formation of P{sup +}/C{sub 60}{sup -} charge transfer complex was not completely ruled out.more » The large exciton binding energy (E{sub b} = 0.6 eV) in PTV inhibits the photoinduced electron transfer from PTV to PCBM. In addition, excitons formed on polymer chains suffer ultrafast (« less

Poly(ester urea)-Based Adhesives: Improved Deployment and Adhesion by Incorporation of Poly(propylene glycol) Segments.

PubMed

Zhou, Jinjun; Bhagat, Vrushali; Becker, Matthew L

2016-12-14

The adhesive nature of mussels arises from the catechol moiety in the 3,4-dihydroxyphenylalanine (DOPA) amino acid, one of the many proteins that contribute to the unique adhesion properties of mussels. Inspired by these properties, many biomimetic adhesives have been developed over the past few years in an attempt to replace adhesives such as fibrin, cyanoacrylate, and epoxy glues. In the present work, we synthesized ethanol soluble but water insoluble catechol functionalized poly(ester urea) random copolymers that help facilitate delivery and adhesion in wet environments. Poly(propylene glycol) units incorporated into the polymer backbone impart ethanol solubility to these polymers, making them clinically relevant. A catechol to cross-linker ratio of 10:1 with a curing time of 4 h exceeded the performance of commercial fibrin glue (4.8 ± 1.4 kPa) with adhesion strength of 10.6 ± 2.1 kPa. These adhesion strengths are significant with the consideration that the adhesion studies were performed under wet conditions.

Structure Property Relationships of Biobased Epoxy Resins

NASA Astrophysics Data System (ADS)

Maiorana, Anthony Surraht

The thesis is about the synthesis, characterization, development, and application of epoxy resins derived from sustainable feedstocks such as lingo-cellulose, plant oils, and other non-food feedstocks. The thesis can be divided into two main topics 1) the synthesis and structure property relationship investigation of new biobased epoxy resin families and 2) mixing epoxy resins with reactive diluents, nanoparticles, toughening agents, and understanding co-curing reactions, filler/matrix interactions, and cured epoxy resin thermomechanical, viscoelastic, and dielectric properties. The thesis seeks to bridge the gap between new epoxy resin development, application for composites and advanced materials, processing and manufacturing, and end of life of thermoset polymers. The structures of uncured epoxy resins are characterized through traditional small molecule techniques such as nuclear magnetic resonance, high resolution mass spectrometry, and infrared spectroscopy. The structure of epoxy resin monomers are further understood through the process of curing the resins and cured resins' properties through rheology, chemorheology, dynamic mechanical analysis, tensile testing, fracture toughness, differential scanning calorimetry, scanning electron microscopy, thermogravimetric analysis, and notched izod impact testing. It was found that diphenolate esters are viable alternatives to bisphenol A and that the structure of the ester side chain can have signifi-cant effects on monomer viscosity. The structure of the cured diphenolate based epoxy resins also influence glass transition temperature and dielectric properties. Incorporation of reactive diluents and flexible resins can lower viscosity, extend gel time, and enable processing of high filler content composites and increase fracture toughness. Incorpora-tion of high elastic modulus nanoparticles such as graphene can provide increases in physical properties such as elastic modulus and fracture toughness. The synthesis of epoxy resins with aliphatic esters in the main chain of the polymer allow for chemical recycling under alkaline conditions and changing the hydrophobicity and access of main chain esters influences the rate of polymer degradation. The thesis further provides strategies and concepts that will allow for future researchers to rapidly understand how to manipulate epoxy resins for specific end uses and supplements current understanding of epoxy curing agents, accelerators, and interactions with fillers.

Bismaleimide and cyanate ester based sequential interpenetrating polymer networks for high temperature application

NASA Astrophysics Data System (ADS)

Geng, Xing

2005-07-01

A research area of high activity in connection with aerospace engineering has been the development of polymer thermosetting resins that can withstand temperature as high as 300°C while maintaining adequate toughness and providing ease of processing to enable low temperature and low cost composite fabrication methods. In order to meet such requirements, sequential interpenetrating polymer networks (IPNs) based on bismaleimide (BMI) and cyanate ester (CE) monomers were investigated. In these systems, a polycyanurate network is first formed in the presence of BMI and appropriate reactive diluent monomers and, in a second step, a network based on the BMI is created in the presence of a fully formed polycyanurate network. The materials developed can be processed at relatively low temperature (<150°C) and with the aid of electron beam (EB) curing. Of major importance to the success of this work was the identification of a reactive diluent that improves ease of processing and has tailored reactivity to allow for the controlled synthesis of CE-BMI sequential IPNs. Based on solubility and reactivity of a number of reactive diluents, N-acryloylmorpholine (AMP) was selected as a co-monomer for BMI copolymerization. A donor-acceptor reaction mechanism was suggested to explain the relative reactivity of a variety of reactive diluents towards maleimide functionality. The optimum processing parameters for the formation of the first network were determined through the study of metal catalyzed cure and hydrolysis of cyanate esters, whereas the reaction behavior for second network formation in terms of the influence of EB dose rate and temperature was elucidated through an in-situ kinetics study of maleimide and AMP copolymerization. Structure-property relationships were developed which allowed for the design of improved resin systems. In particular, an appropriate network coupler possessing cyanate ester and maleimide functionality was synthesized to link the polycyanurate first network to the BMI/AMP second network and thus form linked sequential IPNs (LIPNs). Consequently, Tg as high as 370°C was achieved and a fracture toughness of 120 J/m2 was obtained for resin systems that possess adequately low viscosity for processing using liquid molding techniques at low temperature.

Cellulose esters synthesized using a tetrabutylammonium acetate and dimethylsulfoxide solvent system

NASA Astrophysics Data System (ADS)

Yu, Yongqi; Miao, Jiaojiao; Jiang, Zeming; Sun, Haibo; Zhang, Liping

2016-07-01

Cellulose acetate (CA) and cellulose acetate propionate (CAP) were homogeneously synthesized in a novel tetrabutylammonium acetate/dimethyl sulfoxide (DMSO) solvent system, without any catalyst, at temperatures below 70 °C. The molecular structures of the cellulose esters (CEs) and distributions of the substituents in the anhydroglucose repeating units were determined using 13C cross-polarization magic angle spinning nuclear magnetic resonance spectroscopy, and the degree of substitution (DS) values were determined using 1H nuclear magnetic resonance spectroscopy. The structures of the CEs, regenerated cellulose (RC), and pulp were determined using Fourier transform infrared spectroscopy. The thermal properties of the products were determined using thermogravimetric analysis. The temperatures of initial decomposition of the CEs were up to 40 °C higher than those of the RC and pulp. All the CEs were highly soluble in DMSO, but were insoluble in acetone. CAs with DS values less than 2.6 swelled or were poorly dissolved in CHCl3, but those with DS values above 2.9 dissolved rapidly. CAPs with DS values above 2.6 had good solubilities in ethyl acetate.

Performance, kinetic, and biodegradation pathway evaluation of anaerobic fixed film fixed bed reactor in removing phthalic acid esters from wastewater

NASA Astrophysics Data System (ADS)

Ahmadi, Ehsan; Yousefzadeh, Samira; Ansari, Mohsen; Ghaffari, Hamid Reza; Azari, Ali; Miri, Mohammad; Mesdaghinia, Alireza; Nabizadeh, Ramin; Kakavandi, Babak; Ahmadi, Peyman; Badi, Mojtaba Yegane; Gholami, Mitra; Sharafi, Kiomars; Karimaei, Mostafa; Ghoochani, Mahboobeh; Brahmand, Masoud Binesh; Mohseni, Seyed Mohsen; Sarkhosh, Maryam; Rezaei, Soheila; Asgharnia, Hosseinali; Dehghanifard, Emad; Jafari, Behdad; Mortezapour, Alireza; Moghaddam, Vahid Kazemi; Mahmoudi, Mohammad Molla; Taghipour, Nader

2017-02-01

Emerging and hazardous environmental pollutants like phthalic acid esters (PAEs) are one of the recent concerns worldwide. PAEs are considered to have diverse endocrine disrupting effects on human health. Industrial wastewater has been reported as an important environment with high concentrations of PAEs. In the present study, four short-chain PAEs including diallyl phthalate (DAP), diethyl phthalate (DEP), dimethyl phthalate (DMP), and phthalic acid (PA) were selected as a substrate for anaerobic fixed film fixed bed reactor (AnFFFBR). The process performances of AnFFFBR, and also its kinetic behavior, were evaluated to find the best eco-friendly phthalate from the biodegradability point of view. According to the results and kinetic coefficients, removing and mineralizing of DMP occurred at a higher rate than other phthalates. In optimum conditions 92.5, 84.41, and 80.39% of DMP, COD, and TOC were removed. DAP was found as the most bio-refractory phthalate. The second-order (Grau) model was selected as the best model for describing phthalates removal.

Occurrence of phthalic acid esters in source waters: a nationwide survey in China during the period of 2009-2012.

PubMed

Liu, Xiaowei; Shi, Jianghong; Bo, Ting; Zhang, Hui; Wu, Wei; Chen, Qingcai; Zhan, Xinmin

2014-01-01

The first nationwide survey of six phthalic acid esters (PAEs) (diethyl phthalate (DEP); dimethyl phthalate (DMP); di-n-butyl phthalate (DBP); butyl benzyl phthalate (BBP); bis(2-ethylhexyl) phthalate (DEHP); di-n-octyl phthalate (DnOP)) in source waters was conducted in China. The results showed these PAEs were ubiquitous in source waters. DBP and DEHP were the most frequently detected with high concentrations ranging nd-1.52 μg/L and nd-6.35 μg/L, respectively. These PAEs concentrations (except DBP) in surface water (rivers, lakes and reservoirs) were generally higher than those in groundwater; DBP had high concentrations in groundwater in Northeast China (Liao River Basin) and North China (Hai River Basin). Their concentrations in the northern regions were generally higher than those in the southern and eastern regions; particularly, in North China. Three short-chain PAEs (DMP, DEP and DBP) were detected with high concentrations in Hai River Basin, Pearl River Basin and Yellow River Basin. Copyright © 2013 Elsevier Ltd. All rights reserved.

Performance, kinetic, and biodegradation pathway evaluation of anaerobic fixed film fixed bed reactor in removing phthalic acid esters from wastewater.

PubMed

Ahmadi, Ehsan; Yousefzadeh, Samira; Ansari, Mohsen; Ghaffari, Hamid Reza; Azari, Ali; Miri, Mohammad; Mesdaghinia, Alireza; Nabizadeh, Ramin; Kakavandi, Babak; Ahmadi, Peyman; Badi, Mojtaba Yegane; Gholami, Mitra; Sharafi, Kiomars; Karimaei, Mostafa; Ghoochani, Mahboobeh; Brahmand, Masoud Binesh; Mohseni, Seyed Mohsen; Sarkhosh, Maryam; Rezaei, Soheila; Asgharnia, Hosseinali; Dehghanifard, Emad; Jafari, Behdad; Mortezapour, Alireza; Moghaddam, Vahid Kazemi; Mahmoudi, Mohammad Molla; Taghipour, Nader

2017-02-20

Emerging and hazardous environmental pollutants like phthalic acid esters (PAEs) are one of the recent concerns worldwide. PAEs are considered to have diverse endocrine disrupting effects on human health. Industrial wastewater has been reported as an important environment with high concentrations of PAEs. In the present study, four short-chain PAEs including diallyl phthalate (DAP), diethyl phthalate (DEP), dimethyl phthalate (DMP), and phthalic acid (PA) were selected as a substrate for anaerobic fixed film fixed bed reactor (AnFFFBR). The process performances of AnFFFBR, and also its kinetic behavior, were evaluated to find the best eco-friendly phthalate from the biodegradability point of view. According to the results and kinetic coefficients, removing and mineralizing of DMP occurred at a higher rate than other phthalates. In optimum conditions 92.5, 84.41, and 80.39% of DMP, COD, and TOC were removed. DAP was found as the most bio-refractory phthalate. The second-order (Grau) model was selected as the best model for describing phthalates removal.

Performance, kinetic, and biodegradation pathway evaluation of anaerobic fixed film fixed bed reactor in removing phthalic acid esters from wastewater

PubMed Central

Ahmadi, Ehsan; Yousefzadeh, Samira; Ansari, Mohsen; Ghaffari, Hamid Reza; Azari, Ali; Miri, Mohammad; Mesdaghinia, Alireza; Nabizadeh, Ramin; Kakavandi, Babak; Ahmadi, Peyman; Badi, Mojtaba Yegane; Gholami, Mitra; Sharafi, Kiomars; Karimaei, Mostafa; Ghoochani, Mahboobeh; Brahmand, Masoud Binesh; Mohseni, Seyed Mohsen; Sarkhosh, Maryam; Rezaei, Soheila; Asgharnia, Hosseinali; Dehghanifard, Emad; Jafari, Behdad; Mortezapour, Alireza; Moghaddam, Vahid Kazemi; Mahmoudi, Mohammad Molla; Taghipour, Nader

2017-01-01

Emerging and hazardous environmental pollutants like phthalic acid esters (PAEs) are one of the recent concerns worldwide. PAEs are considered to have diverse endocrine disrupting effects on human health. Industrial wastewater has been reported as an important environment with high concentrations of PAEs. In the present study, four short-chain PAEs including diallyl phthalate (DAP), diethyl phthalate (DEP), dimethyl phthalate (DMP), and phthalic acid (PA) were selected as a substrate for anaerobic fixed film fixed bed reactor (AnFFFBR). The process performances of AnFFFBR, and also its kinetic behavior, were evaluated to find the best eco-friendly phthalate from the biodegradability point of view. According to the results and kinetic coefficients, removing and mineralizing of DMP occurred at a higher rate than other phthalates. In optimum conditions 92.5, 84.41, and 80.39% of DMP, COD, and TOC were removed. DAP was found as the most bio-refractory phthalate. The second-order (Grau) model was selected as the best model for describing phthalates removal. PMID:28216654

Wiring microbial biofilms to the electrode by osmium redox polymer for the performance enhancement of microbial fuel cells.

PubMed

Yuan, Yong; Shin, Hyosul; Kang, Chan; Kim, Sunghyun

2016-04-01

An osmium redox polymer, PAA-PVI-[Os(4,4'-dimethyl-2,2'-bipyridine)2Cl]+/2+ that has been used in enzymatic fuel cells and microbial sensors, was applied for the first time to the anode of single-chamber microbial fuel cells with the mixed culture inoculum aiming at enhancing performance. Functioning as a molecular wire connecting the biofilm to the anode, power density increased from 1479 mW m(-2) without modification to 2355 mW m(-2) after modification of the anode. Evidence from cyclic voltammetry showed that the catalytic activity of an anodic biofilm was greatly enhanced in the presence of an osmium redox polymer, indicating that electrons were more efficiently transferred to the anode via co-immobilized osmium complex tethered to wiring polymer chains at the potential range of -0.3 V-+0.1 V (vs. SCE). The optimum amount of the redox polymer was determined to be 0.163 mg cm(-2). Copyright © 2015 Elsevier B.V. All rights reserved.

Smoothing Polymer Surfaces by Solvent-Vapor Exposure

NASA Astrophysics Data System (ADS)

Anthamatten, Mitchell

2003-03-01

Ultra-smooth polymer surfaces are of great importance in a large body of technical applications such as optical coatings, supermirrors, waveguides, paints, and fusion targets. We are investigating a simple approach to controlling surface roughness: by temporarily swelling the polymer with solvent molecules. As the solvent penetrates into the polymer, its viscosity is lowered, and surface tension forces drive surface flattening. To investigate sorption kinetics and surface-smoothing phenomena, a series of vapor-deposited poly(amic acid) films were exposed to dimethyl sulfoxide vapors. During solvent exposure, the surface topology was continuously monitored using light interference microscopy. The resulting power spectra indicate that high-frequency defects smooth faster than low-frequency defects. This frequency dependence was studied by depositing polymer films onto a series of 2D sinusoidal surfaces and performing smoothing experiments. Results show that the amplitudes of the sinusoidal surfaces decay exponentially with solvent exposure time, and the exponential decay constants are proportional to surface frequency. This work was performed under the auspices of the U.S. Department of Energy by the University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

Photoresponsive liquid crystalline epoxy networks with shape memory behavior and dynamic ester bonds

DOE PAGES

Rios, Orlando; Chen, Jihua; Li, Yuzhan; ...

2016-06-01

Functional polymers are intelligent materials that can respond to a variety of external stimuli. However, these materials have not yet found widespread real world applications because of the difficulties in fabrication and the limited number of functional building blocks that can be incorporated into a material. Here, we demonstrate a simple route to incorporate three functional building blocks (azobenzene chromophores, liquid crystals, and dynamic covalent bonds) into an epoxy-based liquid crystalline network (LCN), in which an azobenzene-based epoxy monomer is polymerized with an aliphatic dicarboxylic acid to create exchangeable ester bonds that can be thermally activated. Lastly, all three functionalmore » building blocks exhibited good compatibility, and the resulting materials exhibits various photomechanical, shape memory, and self-healing properties because of the azobenzene molecules, liquid crystals, and dynamic ester bonds, respectively.« less

Degradation Mechanisms of Poly(ester urethane) Elastomer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edgar, Alexander S.

This report describes literature regarding the degradation mechanisms associated with a poly(ester urethane) block copolymer, Estane® 5703 (Estane), used in conjunction with Nitroplasticizer (NP), and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane, also known as high molecular weight explosive (HMX) to produce polymer bonded explosive PBX 9501. Two principal degradation mechanisms are reported: NO2 oxidative reaction with the urethane linkage resulting in crosslinking and chain scission events, and acid catalyzed hydrolysis of the ester linkage. This report details future work regarding this PBX support system, to be conducted in late 2017 and 2018 at Engineered Materials Group (MST-7), Materials Science and Technology Division, Los Alamos Nationalmore » Laboratory. This is the first of a series of three reports on the degradation processes and trends of the support materials of PBX 9501.« less

Complexes of polyadenylic acid and the methyl esters of amino acids

NASA Technical Reports Server (NTRS)

Khaled, M. A.; Mulins, D. W., Jr.; Swindle, M.; Lacey, J. C., Jr.

1983-01-01

A study of amino acid methyl esters binding to polyadenylic acid supports the theory that the genetic code originated through weak but selective affinities between amino acids and nucleotides. NMR, insoluble complex analysis, and ultraviolet spectroscopy are used to illustrate a correlation between the hydrophybicities of A amino acids and their binding constants, which, beginning with the largest, are in the order of Phe (having nominally a hydrophobic AAA anticodon), Ile, Leu, Val and Gly (having a hydrophilic anticodon with no A). In general, the binding constants are twice the values by Reuben and Polk (1980) for monomeric AMP, which suggests that polymer amino acids are interacting with only one base. No real differences are found betwen poly A binding for free Phe, Phe methyl ester or Phe amide, except that the amide value is slightly lower.

Generation of live offspring from vitrified embryos with synthetic polymers SuperCool X-1000 and SuperCool Z-1000.

PubMed

Marco-Jimenez, F; Jimenez-Trigos, E; Lavara, R; Vicente, J S

2014-01-01

Ice growth and recrystallisation are considered important factors in determining vitrification outcomes. Synthetic polymers inhibit ice formation during cooling or warming of the vitrification process. The aim of this study was to assess the effect of adding commercially available synthetic polymers SuperCool X-1000 and SuperCool Z-1000 to vitrification media on in vivo development competence of rabbit embryos. Four hundred and thirty morphologically normal embryos recovered at 72 h of gestation were used. The vitrification media contained 20% dimethyl sulphoxide and 20% ethylene glycol, either alone or in combination with 1% of SuperCool X-1000 and 1% SuperCool. Our results show that embryos can be successfully vitrified using SuperCool X-1000 and SuperCool Z-1000 and when embryos are transferred, live offspring can be successfully produced. In conclusion, our results demonstrated that we succeeded for the first time in obtaining live offspring after vitrification of embryos using SuperCool X-1000 and SuperCool Z-1000 polymers.

Synthesis and development of low cost, high temperature N-arylene polybenzimidazole foam material

NASA Technical Reports Server (NTRS)

Harrison, E. S.

1975-01-01

Polymer (and foam) studies followed two basic routes: (1) formation of high molecular weight uncyclized polyamide followed by subsequent fusion and cyclodehydration to yield NABI (foam) and (2) polymer and foam formation by reaction of diphenyl esters (or anhydrides) with the tetramine. The latter route was found much more attractive since considerable versatility in both basic polymer structure and crosslinkability is achievable. Preliminary studies on BAB, phthalic anhydride (PA), and 3, 3 (prime), 4, 4(prime) benzo pheno netetracarboxylic acid dianhydride (BTDA) as crosslinked polymer precursors were conducted. Nonmelting rigid char forming foams with densities as low as 2.7 lb/cubic ft. were achieved. The program was successful in the preparation of a potentially low cost, low density, high char yield, high temperature foam material.

Efficient Quenching of Oligomeric Fluorophores on a DNA Backbone

PubMed Central

Wilson, James N.; Teo, Yin Nah; Kool, Eric T.

2008-01-01

The quenching properties of a series of oligodeoxyribosides bearing fluorophore ‘bases’ is described. Sequences of adjacent, π-stacked pyrenes exhibit stronger electronic interactions visible in both absorbance and emission spectra than pyrenes that are insulated by intervening adenines. Quenching by N, N′-dimethyl-4,4′-bipyridinium dichloride is efficient for excimer-and exciplex-forming oligomers, with Stern-Volmer constants comparable to conjugated polymer “superquenching” schemes. PMID:18027944

An aqueous all-organic redox-flow battery employing a (2,2,6,6-tetramethylpiperidin-1-yl)oxyl-containing polymer as catholyte and dimethyl viologen dichloride as anolyte

NASA Astrophysics Data System (ADS)

Hagemann, Tino; Winsberg, Jan; Grube, Mandy; Nischang, Ivo; Janoschka, Tobias; Martin, Norbert; Hager, Martin D.; Schubert, Ulrich S.

2018-02-01

Herein we present a new redox-flow battery (RFB) that employs a (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) containing copolymer (P1) as catholyte and the viologen derivative N,N‧-dimethyl-4,4‧-bipyridinium dichloride (MV) as anolyte in an aqueous sodium chloride solution. This is the first time that a combination of an organic polymer and a low-molar-mass organic redox-active material is presented. The electrochemical behavior of the utilized charge-storage materials were investigated by cyclic voltammetry (CV) and feature reversible redox-reactions at E½ = 0.7 V (TEMPO/TEMPO+) and E½ = -0.6 V vs. AgCl/Ag (MV++/MV+•), which lead to a promising cell voltage of 1.3 V in the subsequent battery application. Studies were performed to determine the most suitable anion-exchange membrane (AEM), the ideal conducting salt concentration and the optimal flow rate. The resulting battery reveals a stable charge/discharge performance over 100 consecutive cycles with coulombic efficiencies of up to 95%, a high energy efficiency of 85% and an overall energy density of the electrolyte system of 3.8 W h L-1.

Dimethyl diallyl ammonium chloride and diallylamin Co-polymer modified bio-film derived from palm dates for the adsorption of dyes.

PubMed

Jabli, Mahjoub; Saleh, Tawfik A; Sebeia, Nouha; Tka, Najeh; Khiari, Ramzi

2017-10-31

For the first time, co-polymer of dimethyl diallyl ammonium chloride and diallylamin (PDDACD) was used to modify the films derived from the waste of palm date fruits, which were then investigated by the purification of colored aqueous solutions. The physico-chemical characteristics were identified using data color, FT-IR spectroscopy, and SEM features. The modified films were evaluated as adsorbents of Methylene Blue (MB), Direct Yellow 50 (DY50), Reactive Blue 198 (RB198) and Naphtol Blue Black (NBB). High retention capacities were achieved in the following order: The equilibrium da DY50 (14 mg g -1 ) < RB198 (16 mg g -1 ) < NBB (63.9 mg g -1 ) < MB (150 mg g -1 ). The kinetic modeling of the data revealed that the adsorption data follows the pseudo second order model. It was fitted to the Langmuir, Freundlich, Temkin, and Dubinin-Redushkevich equations, and the data best fit the Freundlich model indicating that the adsorption might occur in the heterogeneous adsorption sites. These results reveal that PDDACD modified films are valuable materials for the treatment of industrial wastewater. Moreover, the as-prepared adsorbent is economically viable and easily controllable for pollutant adsorption.

Azo polymeric micelles designed for colon-targeted dimethyl fumarate delivery for colon cancer therapy.

PubMed

Ma, Zhen-Gang; Ma, Rui; Xiao, Xiao-Lin; Zhang, Yong-Hui; Zhang, Xin-Zi; Hu, Nan; Gao, Jin-Lai; Zheng, Yu-Feng; Dong, De-Li; Sun, Zhi-Jie

2016-10-15

Colon-targeted drug delivery and circumventing drug resistance are extremely important for colon cancer chemotherapy. Our previous work found that dimethyl fumarate (DMF), the approved drug by the FDA for the treatment of multiple sclerosis, exhibited anti-tumor activity on colon cancer cells. Based on the pharmacological properties of DMF and azo bond in olsalazine chemical structure, we designed azo polymeric micelles for colon-targeted dimethyl fumarate delivery for colon cancer therapy. We synthesized the star-shape amphiphilic polymer with azo bond and fabricated the DMF-loaded azo polymeric micelles. The four-arm polymer star-PCL-azo-mPEG (sPCEG-azo) (constituted by star-shape PCL (polycaprolactone) and mPEG (methoxypolyethylene glycols)-olsalazine) showed self-assembly ability. The average diameter and polydispersity index of the DMF-loaded sPCEG-azo polymeric micelles were 153.6nm and 0.195, respectively. In vitro drug release study showed that the cumulative release of DMF from the DMF-loaded sPCEG-azo polymeric micelles was no more than 20% in rat gastric fluid within 10h, whereas in the rat colonic fluids, the cumulative release of DMF reached 60% in the initial 2h and 100% within 10h, indicating that the DMF-loaded sPCEG-azo polymeric micelles had excellent colon-targeted property. The DMF-loaded sPCEG-azo polymeric micelles had no significant cytotoxicity on colon cancer cells in phosphate buffered solution (PBS) and rat gastric fluid. In rat colonic fluid, the micelles showed significant cytotoxic effect on colon cancer cells. The blank sPCEG-azo polymeric micelles (without DMF) showed no cytotoxic effect on colon cancer cells in rat colonic fluids. In conclusion, the DMF-loaded sPCEG-azo polymeric micelles show colon-targeted DMF release and anti-tumor activity, providing a novel approach potential for colon cancer therapy. Colon-targeted drug delivery and circumventing drug resistance are extremely important for colon cancer chemotherapy. Our previous work found that dimethyl fumarate (DMF), the approved drug by the FDA for the treatment of multiple sclerosis, exhibited anti-tumor activities on colon cancer cells (Br J Pharmacol. 2015 172(15):3929-43.). Based on the pharmacological properties of DMF and azo bond in olsalazine chemical structure, we designed azo polymeric micelles for colon-targeted dimethyl fumarate delivery for colon cancer therapy. We found that the DMF-loaded sPCEG-azo polymeric micelles showed colon-targeted DMF release and anti-tumor activities, providing a novel approach potential for colon cancer therapy. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

COMBINATION DOSE OF TWO PHTHALATES ADDITIVELY DEPRESSES TESTOSTERONE PRODUCTION AND INSL3 GENE EXPRESSION IN MALE RAT FETUSES

EPA Science Inventory

Diethylhexyl phthalate (DEHP) and di(n-butyl) phthalate (DBP) are phthalate esters used to modify plastic and polymer textures. Individually,DEHP and DBP reduce testosterone production, inhibit reproductive tract development, andinduce reproductive organ malformationsin male rats...

Effect of ethylene glycol doping on performance of PEDOT:PSS/µT-n-Si heterojunction solar cell

NASA Astrophysics Data System (ADS)

Singh, Prashant; Nakra, Rohan; Sivaiah, B.; Sardana, Sanjay K.; Prathap, P.; Rauthan, C. M. S.; Srivastava, Sanjay K.

2018-05-01

This study reports effect of co-solvent doping in poly (3, 4-ethyelenedioxythiophene):poly(dimethyl sulfoxide) (PEDOT:PSS) over the performance of Ag/PEDOT:PSS/µT-n-Si/In:Ga architecture based solar cell. PEDOT:PSS polymer is doped with varying concentration of ethylene glycol (EG). At 10% (volume) concentration performance of the device is highest with 4.69% power conversion efficiency. At higher or lower concentrations of ethylene glycol device performance deteriorates with sharp decline in short-circuit current density. Improvement in conductivity of the PEDOT:PSS polymer due to addition of co-solvent is the reason behind improvement in the performance of the device efficiency.

Spectroscopic studies of nanoparticle-sensitised photorefractive polymers

NASA Astrophysics Data System (ADS)

Aslam, Farzana; Binks, David J.; Daniels, Steve; Pickett, Nigel; O'Brien, Paul

2005-09-01

We report on the absorbance and photoluminescence spectra of photorefractive polymer composites sensitized by three different types of nanoparticles. Each nanoparticle is passivated by 1-hexadecylamine (HDA) and the composites also consist of the charge transporting matrix poly( N-vinylcarbazole) and the dye 1-(2'-ethylhexyloxy)-2,5-dimethyl-4-(4-nitrophenylazo) benzene. A strong spectral feature is observed that is attributed to a complex formed between the dye and HDA; elemental analysis indicates that the formation of this complex is determined by the metal content of the nanoparticle surface. The photoluminescence quantum yield for the complex is greatly reduced when the HDA is attached to the nanoparticle, indicating that a charge transfer occurs.

Method development for determination of migrated phthalate acid esters from polyethylene terephthalate (PET) packaging into traditional Iranian drinking beverage (Doogh) samples: a novel approach of MSPE-GC/MS technique.

PubMed

Kiani, Amin; Ahmadloo, Mahsa; Shariatifar, Nabi; Moazzen, Mojtaba; Baghani, Abbas Norouzian; Khaniki, GholamReza Jahed; Taghinezhad, Ali; Kouhpayeh, Amin; Mousavi Khaneghah, Amin; Ghajarbeygi, Peyman

2018-05-01

In the current study, a novel magnetic solid phase extraction (MSPE) technique combined with a gas chromatography/mass spectroscopy (GC/MS) was developed to determine the phthalate ester content of bottled Doogh samples. Doogh is a yogurt-based drinking beverage, which is frequently consumed in Middle East and Balkans. It is produced by stirring yogurt in Chern separation machine and consists of substances such as water, yogurt, and salt in addition to aqueous extracts of native herbs. The magnetic multi-walled carbon nanotubes (MWCNT-Fe 3 O 4 ) were used as adsorbents of phthalate acid esters (PAEs) due to a superior adsorption capability of hydrophobic compounds. In this context, the quantity of the extractable migrated phthalate esters (dibutyl phthalate (DBP), dimethyl phthalate (DMP), butyl benzyl phthalate (BBP), diethyl phthalate (DEP), di-N-octyl phthalate (DNOP), and bis (2-ethylhexyl) phthalate (DEHP)) from polyethylene terephthalate (PET) bottles into Doogh samples was measured. The correlation between the concentration of migrated PAEs and some factors such as the type of Doogh (gaseous and without gas), difference in brand (five brands), volume (1500 and 300 mL), and the storage time also was investigated. The migration level into Doogh samples was increased by incorporating of gas as well as increasing the volume of PET bottles. Also, with elaborating of storage time, the migration of some phthalates such as DEHP (the mean from 2419.85 ng L -1 in the first week to 2716.15 ng L -1 in the second month), DEP, and total phthalate was increased. However, no significant difference in concentrations of migrated phthalate esters among different examined brands was noted. Finally, the concentration of migrated PAEs from bottle into all the examined Doogh samples was below the defined standards by EPA; 6 μg/L for DEHP in drinking water. Graphical abstract ᅟ.

Controlled drug release by polymer dissolution. II: Enzyme-mediated delivery device.

PubMed

Heller, J; Trescony, P V

1979-07-01

A novel, closed-loop drug delivery system was developed where the presence or absence of an external compound controls drug delivery from a bioerodible polymer. In the described delivery system, hydrocortisone was incorporated into a n-hexyl half-ester of a methyl vinyl ehter-maleic anhydride copolymer, and the polymer-drug mixture was fabricated into disks. These disks were then coated with a hydrogel containing immobilized urease. In a medium of constant pH and in the absence of external urea, the hydrocortisone release was that normally expected for that polymer at the given pH. With external urea, ammonium bicarbonate and ammonium hydroxide were generated within the hydrogel, which accelerated polymer erosion and drug release. The drug delivery rate increase was proportional to the amount of external urea and was reversible; that is, when external urea was removed, the drug release rate gradually returned to its original value.

Tuning Fullerene Intercalation in a Poly (thiophene) derivative by Controlling the Polymer Degree of Self-Organisation

NASA Astrophysics Data System (ADS)

Paternò, G. M.; Skoda, M. W. A.; Dalgliesh, Robert; Cacialli, F.; Sakai, V. García

2016-10-01

Controlling the nanoscale arrangement in polymer-fullerene organic solar cells is of paramount importance to boost the performance of such promising class of photovoltaic diodes. In this work, we use a pseudo-bilayer system made of poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene (PBTTT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), to acquire a more complete understanding of the diffusion and intercalation of the fullerene-derivative within the polymer layer. By exploiting morphological and structural characterisation techniques, we observe that if we increase the film solidification time the polymer develops a higher crystalline order, and, as a result, it does not allow fullerene molecules to intercalate between the polymer side-chains. Gaining insight into the detailed fullerene intercalation mechanism is important for the development of organic photovoltaic diodes (PVDs).

A redox beginning: Which came first phosphoryl, acyl, or electron transfer ?. [Abstract only

NASA Technical Reports Server (NTRS)

Weber, Arthur L.

1994-01-01

Thermodynamic and kinetic information available on the synthesis of prebiotic monomers and polymers will be examined in order to illuminate the prebiotic plausibility of polymer syntheses based on (a) phosphoryl transfer that yields phosphodiester polymers, (b) acyl transfer that gives polyamides, and (c) electron transfer that produces polydisulfide or poly(thio)ester polymers. New experimental results on the oxidative polymerization of 2,3-dimercaptopropanol by ferric ions on the surface of ferric hydroxide oxide will be discussed as a chemical model of polymerization by electron transfer. This redox polymerization that yields polymers with a polydisulfide backbone was found to give oligomers up to the 15-mer from 1 mM of 2,3-dimercaptopropanol after one day at 25 C. High pressure liquid chromatography (HPLC) analysis of the oligomers was carried out on an Alltech OH-100 column eluted with acetonitrile-water.

Tuning Fullerene Intercalation in a Poly (thiophene) derivative by Controlling the Polymer Degree of Self-Organisation.

PubMed

Paternò, G M; Skoda, M W A; Dalgliesh, Robert; Cacialli, F; Sakai, V García

2016-10-04

Controlling the nanoscale arrangement in polymer-fullerene organic solar cells is of paramount importance to boost the performance of such promising class of photovoltaic diodes. In this work, we use a pseudo-bilayer system made of poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene (PBTTT) and [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM), to acquire a more complete understanding of the diffusion and intercalation of the fullerene-derivative within the polymer layer. By exploiting morphological and structural characterisation techniques, we observe that if we increase the film solidification time the polymer develops a higher crystalline order, and, as a result, it does not allow fullerene molecules to intercalate between the polymer side-chains. Gaining insight into the detailed fullerene intercalation mechanism is important for the development of organic photovoltaic diodes (PVDs).

Tuning Fullerene Intercalation in a Poly (thiophene) derivative by Controlling the Polymer Degree of Self-Organisation

PubMed Central

Paternò, G. M.; Skoda, M. W. A.; Dalgliesh, Robert; Cacialli, F.; Sakai, V. García

2016-01-01

Controlling the nanoscale arrangement in polymer-fullerene organic solar cells is of paramount importance to boost the performance of such promising class of photovoltaic diodes. In this work, we use a pseudo-bilayer system made of poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene (PBTTT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), to acquire a more complete understanding of the diffusion and intercalation of the fullerene-derivative within the polymer layer. By exploiting morphological and structural characterisation techniques, we observe that if we increase the film solidification time the polymer develops a higher crystalline order, and, as a result, it does not allow fullerene molecules to intercalate between the polymer side-chains. Gaining insight into the detailed fullerene intercalation mechanism is important for the development of organic photovoltaic diodes (PVDs). PMID:27698410

Athero-inflammatory nanotherapeutics: Ferulic acid-based poly(anhydride-ester) nanoparticles attenuate foam cell formation by regulating macrophage lipogenesis and reactive oxygen species generation.

PubMed

Chmielowski, Rebecca A; Abdelhamid, Dalia S; Faig, Jonathan J; Petersen, Latrisha K; Gardner, Carol R; Uhrich, Kathryn E; Joseph, Laurie B; Moghe, Prabhas V

2017-07-15

Enhanced bioactive anti-oxidant formulations are critical for treatment of inflammatory diseases, such as atherosclerosis. A hallmark of early atherosclerosis is the uptake of oxidized low density lipoprotein (oxLDL) by macrophages, which results in foam cell and plaque formation in the arterial wall. The hypolipidemic, anti-inflammatory, and antioxidative properties of polyphenol compounds make them attractive targets for treatment of atherosclerosis. However, high concentrations of antioxidants can reverse their anti-atheroprotective properties and cause oxidative stress within the artery. Here, we designed a new class of nanoparticles with anti-oxidant polymer cores and shells comprised of scavenger receptor targeting amphiphilic macromolecules (AMs). Specifically, we designed ferulic acid-based poly(anhydride-ester) nanoparticles to counteract the uptake of high levels of oxLDL and regulate reactive oxygen species generation (ROS) in human monocyte derived macrophages (HMDMs). Compared to all compositions examined, nanoparticles with core ferulic acid-based polymers linked by diglycolic acid (PFAG) showed the greatest inhibition of oxLDL uptake. At high oxLDL concentrations, the ferulic acid diacids and polymer nanoparticles displayed similar oxLDL uptake. Treatment with the PFAG nanoparticles downregulated the expression of macrophage scavenger receptors, CD-36, MSR-1, and LOX-1 by about 20-50%, one of the causal factors for the decrease in oxLDL uptake. The PFAG nanoparticle lowered ROS production by HMDMs, which is important for maintaining macrophage growth and prevention of apoptosis. Based on these results, we propose that ferulic acid-based poly(anhydride ester) nanoparticles may offer an integrative strategy for the localized passivation of the early stages of the atheroinflammatory cascade in cardiovascular disease. Future development of anti-oxidant formulations for atherosclerosis applications is essential to deliver an efficacious dose while limiting localized concentrations of pro-oxidants. In this study, we illustrate the potential of degradable ferulic acid-based polymer nanoparticles to control macrophage foam cell formation by significantly reducing oxLDL uptake through downregulation of scavenger receptors, CD-36, MSR-1, and LOX-1. Another critical finding is the ability of the degradable ferulate-based polymer nanoparticles to lower macrophage reactive oxygen species (ROS) levels, a precursor to apoptosis and plaque escalation. The degradable ferulic acid-based polymer nanoparticles hold significant promise as a means to alter the treatment and progression of atherosclerosis. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Microbial Lipid and C Isotopic Biosignatures of a Unique Community at Grand Prismatic Spring, Yellowstone National Park

NASA Technical Reports Server (NTRS)

Jahnke, Linda; Parenteau, Mary; Farmer, Jack

2012-01-01

The microbial communities found in modern hot springs are considered analogs to ones that may have existed in hydrothermal systems on the early Earth and possibly Mars. Our goal was to characterize the microbial biosignatures and to assess the preservation of organic matter in the silica-depositing Grand Prismatic Spring in Yellowstone National Park. This study combines 16S rRNA surveys, lipid biomarkers, and C isotopes to query, "Who's there and what are they doing?" On the edge of the approximately 90 m diameter blue vent pool (56.1 C, pH 8.5), a floating green streamer community grew over a benthic pink community. The membrane lipids in the green streamers and pink mat were composed of unusual ester-linked fatty acids, indicating the presence of novel bacterial groups. In particular, we discovered a series of 2-methyl and 2,X-dimethyl phospholipid fatty acids (C18-22). We are attempting to use the 16S rRNA surveys to link these compounds to source organisms. Wax esters, biomarkers for Chloroflexi, were present in both communities, but displayed different profiles. A higher proportion of branched wax esters were found in the green streamers, and were associated with a relatively high concentration of long-chain di- and trienes (C29-31). This suggests that Chloroflexus primarily grew in the green streamers, while a pink mat of Roseiflexus grew on the sinter substrate underneath. Cyanobacterial alkanes were found in the green streamers (n-C17, 7-, 6- and 5-monomethyl-C17, 7,11-dimethyl-C17, n-C19, n-C19:1). We also detected a series of monoalkylglycerylethers and geologically relevant hopanoids in both communities. Carbon isotope analyses indicated that Chloroflexus was growing photoheterotrophically using cyanobacterial photosynthate. Roseiflexus also traditionally grows photoheterotrophically, but the C isotopic signatures of the lipids in the pink mat were approximately 10 %0 lighter than the cyanobacterial and Chloroflexus lipids, indicating a potentially novel metabolic mechanism or prior secondary reworking of substrates before reaching Roseiflexus. This arrangement of Synechococcus-Chloroflexus green streamers floating over a benthic pink community of Roseiflexus is different from the classical laminated Synechococcus-Chloroflexi mats at Octopus Hot Spring.

Influence of macromer molecular weight and chemistry on poly(beta-amino ester) network properties and initial cell interactions.

PubMed

Brey, Darren M; Erickson, Isaac; Burdick, Jason A

2008-06-01

A library of photocrosslinkable poly(beta-amino ester)s (PBAEs) was recently synthesized to expand the number of degradable polymers that can be screened and developed for a variety of biological applications. In this work, the influence of variations in macromer chemistry and macromer molecular weight (MMW) on network reaction behavior, overall bulk properties, and cell interactions were investigated. The MMW was controlled through alterations in the initial diacrylate to amine ratio (> or =1) during synthesis and decreased with an increase in this ratio. Lower MMWs reacted more quickly and to higher double bond conversions than higher MMWs, potentially due to the higher concentration of reactive groups. Additionally, the lower MMWs led to networks with higher compressive and tensile moduli that degraded slower than networks formed from higher MMWs because of an increase in the crosslinking density and decrease in the number of degradable units per crosslink. The adhesion and spreading of osteoblast-like cells on polymer films was found to be dependent on both the macromer chemistry and the MMW. In general, the number of cells was similar on networks formed from a range of MMWs, but the spreading was dramatically influenced by MMW (higher spreading with lower MMWs). These results illustrate further diversity in photocrosslinkable PBAE properties and that the chemistry and macromer structure must be carefully selected for the desired application. Copyright 2007 Wiley Periodicals, Inc.

Hydrophobically-associating cationic polymers as micro-bubble surface modifiers in dissolved air flotation for cyanobacteria cell separation.

PubMed

Yap, R K L; Whittaker, M; Diao, M; Stuetz, R M; Jefferson, B; Bulmus, V; Peirson, W L; Nguyen, A V; Henderson, R K

2014-09-15

Dissolved air flotation (DAF), an effective treatment method for clarifying algae/cyanobacteria-laden water, is highly dependent on coagulation-flocculation. Treatment of algae can be problematic due to unpredictable coagulant demand during blooms. To eliminate the need for coagulation-flocculation, the use of commercial polymers or surfactants to alter bubble charge in DAF has shown potential, termed the PosiDAF process. When using surfactants, poor removal was obtained but good bubble adherence was observed. Conversely, when using polymers, effective cell removal was obtained, attributed to polymer bridging, but polymers did not adhere well to the bubble surface, resulting in a cationic clarified effluent that was indicative of high polymer concentrations. In order to combine the attributes of both polymers (bridging ability) and surfactants (hydrophobicity), in this study, a commercially-available cationic polymer, poly(dimethylaminoethyl methacrylate) (polyDMAEMA), was functionalised with hydrophobic pendant groups of various carbon chain lengths to improve adherence of polymer to a bubble surface. Its performance in PosiDAF was contrasted against commercially-available poly(diallyl dimethyl ammonium chloride) (polyDADMAC). All synthesised polymers used for bubble surface modification were found to produce positively charged bubbles. When applying these cationic micro-bubbles in PosiDAF, in the absence of coagulation-flocculation, cell removals in excess of 90% were obtained, reaching a maximum of 99% cell removal and thus demonstrating process viability. Of the synthesised polymers, the polymer containing the largest hydrophobic functionality resulted in highly anionic treated effluent, suggesting stronger adherence of polymers to bubble surfaces and reduced residual polymer concentrations. Copyright © 2014 Elsevier Ltd. All rights reserved.

Durability of polymer matrix composites for infrastructure: The role of the interphase

NASA Astrophysics Data System (ADS)

Verghese, Kandathil Nikhil Eapen

1999-12-01

As fiber reinforced polymer matrix composites find greater use in markets such as civil infrastructure and ground transportation, the expectations placed on these materials are ever increasing. The overall cost and reliability have become the drivers of these high performance materials and have led to the disappearance of resins such as bismaleimides (BMI). cyanate esters and other high performance polyimides and epoxys. In their place polymers, such polyester and vinylester have arisen. The reinforcing fiber scenario has also undergone changes from the high quality and performance assured IM7 and AS4 to cheaper and hybrid systems consisting of both glass and low cost carbon. Manufacturing processes have had their share of changes too with processes such as pultrusion and other mass production techniques replacing hand lay-up and resin transfer molding. All of this has however come with little or no concession on material performance. The motivation of the present research has therefore been to try to improve the properties of these low cost composites by better understanding the constituent materials (fiber and matrix) and the region that lies in-between them namely the interphase. In order to achieve this. working with controls is necessary and the present discourse therefore deals with the AS4 fiber system from Hexcel Corporation and the vinyl ester resin, Derakane 441-400 from The Dow Chemical Company. The following eight chapters sum up the work done thus far on composites made with sized fibers and the above mentioned resin and fiber systems. They are in the form of publications that have either been accepted. submitted or going to be submitted to various peer reviewed journals. The sizings used have been poly(vinylpyrrolidone) PVP and Polyhydroxyether (Phenoxy) thermoplastic polymers and G' an industrial sizing material supplied by Hexcel. A number of issues have been addressed ranging from viscoelastic relaxation to enviro-mechanical durability. Chapter 1 deals with the influence of the sizing material on the fatigue response of cross ply composites made with the help of resin infusion molding. Chapter 2 describes the effects of a controlled set of interphase polymers that have the saine chemical structure but differ from each other in polarity. The importance of the atomic force microscope (AFM) to view and perform nano-indentations on the interphase regions has been demonstrated. Finally, it attempts to tie everything together with the help of the fatigue response of the different composites. Chapter 3 deals only with the vinyl ester resin and examines the influence of network structure on the molecular relaxation behavior (cooperativity) of the glassy polymer. It also tries to make connections between structural features of the glass and fracture toughness as measured in it's glassy state. Chapter 4 extends the results obtained in chapter 3 to examine the cooperativity of pultruded composites made with the different sizings. A correlation between strength and cooperativity is found to exist, with systems having greater cooperativity being stronger. Chapter 5 moves into the area of hygrothermal aging of Derakane 441-400 resin. It looks specifically at identifying a mechanism for the unusual moisture uptake behavior of the polymer subjected to a thermal-spiking environment. This it does by identifying the presence of hydrogen bonding in the resin. Finally, chapters 6 to 8 present experimental and analytical results obtained on PVP K90, Phenoxy and G' sized, AS4/Derakane 411-350 LI vinyl ester composites that were pultruded at Strongwell Inc., on their lab-scale pultruder in Bristol, Virginia.

The use of novel biodegradable, optically active and nanostructured poly(amide-ester-imide) as a polymer matrix for preparation of modified ZnO based bionanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdolmaleki, Amir, E-mail: abdolmaleki@cc.iut.ac.ir; Nanotechnology and Advanced Materials Institute, Isfahan University of Technology, Isfahan 84156-83111, Islamic Republic of Iran; Mallakpour, Shadpour, E-mail: mallak@cc.iut.ac.ir

Highlights: Black-Right-Pointing-Pointer A novel biodegradable and nanostructured PAEI based on two amino acids, was synthesized. Black-Right-Pointing-Pointer ZnO nanoparticles were modified via two different silane coupling agents. Black-Right-Pointing-Pointer PAEI/modified ZnO BNCs were synthesized through ultrasound irradiation. Black-Right-Pointing-Pointer ZnO particles were dispersed homogeneously in PAEI matrix on nanoscale. Black-Right-Pointing-Pointer The effect of ZnO nanoparticles on the properties of synthesized polymer was examined. -- Abstract: A novel biodegradable and nanostructured poly(amide-ester-imide) (PAEI) based on two different amino acids, was synthesized via direct polycondensation of biodegradable N,N Prime -bis[2-(methyl-3-(4-hydroxyphenyl)propanoate)]isophthaldiamide and N,N Prime -(pyromellitoyl)-bis-L-phenylalanine diacid. The resulting polymer was characterized by FT-IR, {sup 1}H NMR,more » specific rotation, elemental analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) analysis. The synthesized polymer showed good thermal stability with nano and sphere structure. Then PAEI/ZnO bionanocomposites (BNCs) were fabricated via interaction of pure PAEI and ZnO nanoparticles. The surface of ZnO was modified with two different silane coupling agents. PAEI/ZnO BNCs were studied and characterized by FT-IR, XRD, UV/vis, FE-SEM and TEM. The TEM and FE-SEM results indicated that the nanoparticles were dispersed homogeneously in PAEI matrix on nanoscale. Furthermore the effect of ZnO nanoparticle on the thermal stability of the polymer was investigated with TGA and DSC technique.« less

Poly(ferulic acid-co-tyrosine): Effect of the Regiochemistry on the Photophysical and Physical Properties en Route to Biomedical Applications

PubMed Central

2015-01-01

The photophysical and mechanical properties of novel poly(carbonate-amide)s derived from two biorenewable resources, ferulic acid (FA) and l-tyrosine ethyl ester, were evaluated in detail. From these two bio-based precursors, a series of four monomers were generated (having amide and/or carbonate coupling units with remaining functionalities to allow for carbonate formation) and transformed to a series of four poly(carbonate-amide)s. The simplest monomer, which was biphenolic and was obtained in a single amidation synthetic step, displayed bright, visible fluorescence that was twice brighter than FA. Multidimensional fluorescence spectroscopy of the polymers in solution highlighted the strong influence that regioselectivity and the degree of polymerization have on their photophysical properties. The regiochemistry of the system had little effect on the wettability, surface free energy, and Young’s modulus (ca. 2.5 GPa) in the solid state. Confocal imaging of solvent-cast films of each polymer revealed microscopically flat surfaces with fluorescent emission deep into the visible region. Fortuitously, one of the two regiorandom polymers (obtainable from the biphenolic monomer in only an overall two synthetic steps from FA and l-tyrosine ethyl ester) displayed the most promising fluorescent properties both in the solid state and in solution, allowing for the possibility of translating this system as a self-reporting or imaging agent in future applications. To further evaluate the potential of this polymer as a biodegradable material, hydrolytic degradation studies at different pH values and temperatures were investigated. Additionally, the antioxidant properties of the degradation products of this polymer were compared with its biphenolic monomer and FA. PMID:25364040

Thermoplastic composite matrices with improved solvent resistance

NASA Technical Reports Server (NTRS)

Hergenrother, P. M.; Jensen, B. J.; Havens, S. J.

1984-01-01

In order to improve solvent resistance of aromatic thermoplastic polymers, ethynyl-terminated aromatic sulfone polymers (ETS), sulfone/ester polymers (SEPE) containing pendent ethynyl groups, and phenoxy resin containing pendent ethynyl groups are synthesized. Cured polysulfones and phenoxy resins containing ethynyl groups on the ends or pendent on the molecules exhibited systematic behavior in solvent resistance, film flexibility, and toughness as a function of crosslink density. The film and composite properties of a cured solvent-resistant ETS were better than those of a commercially available solvent sensitive polysulfone. The study was part of a NASA program to better understand the trade-offs between solvent resistance, processability and mechanical properties which may be useful in designing composite structures for aerospace vehicles.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Boxin; Schneiderman, Deborah K.; Zare Bidoky, Fazel

We have designed printable, biocompatible, and degradable ion gels by combining a novel ABA triblock aliphatic polyester, poly(ε-decalactone)-b-poly(dl-lactide)-b-poly(ε-decalactone), and a low toxicity ionic liquid, 1-butyl-1-methylpyrrolidinium bistrifluoromethanesulfonylimide ([P14][TFSI]). Due to the favorable compatibility between amorphous poly(dl-lactide) and [P14][TFSI] and the insolubility of the poly(ε-decalactone), the triblock polymer forms self-assembled micellar cross-links similar to thermoplastic elastomers, which ensures similar processing conditions and mechanical robustness during the fabrication of printed electrolyte-gated organic transistor devices. Additionally, the ester backbone in the polymer structure enables efficient hydrolytic degradation of these ion gels compared to those made previously using carbon-backbone polymers.

Vibrational spectroscopy, intramolecular CH⋯O interaction and conformational analysis of 2,5-dimethyl-benzyl benzoate

NASA Astrophysics Data System (ADS)

Viana, Rommel B.; Ribeiro, Gabriela L. O.; Valencia, Leidy J.; Varela, Jaldyr J. G.; Viana, Anderson B.; da Silva, Albérico B. F.; Moreno-Fuquen, Rodolfo

2016-12-01

The aim of this study was to report the spectroscopic and electronic properties of 2,5-dimethyl-benzyl benzoate. FT-IR and Raman vibrational spectral analyses were performed, while a computational approach was used to elucidate the vibrational frequency couplings. The electronic properties were predicted using the Density Functional Theory, while the G3MP2 method was employed in the thermochemical calculation. A conformational analysis, frontier orbitals, partial atomic charge distribution and the molecular electrostatic potential were also estimated. Concerning to the dihedral angles in the ester group, a conformational analysis showed a barrier energy of 10 kcal mol-1, while other small barriers (below 0.6 kcal mol-1) were predicted within the potential surface energy investigation. Insights into the relative stability among the different positions of methyl groups in the phenyl ring demonstrated that the energy gaps were lower than 1 kcal mol-1 among the regioisomers. In addition, the Quantum Theory of Atoms in Molecules (QTAIM) was used to understand the intramolecular CH⋯O interaction in the title compound, while various methodologies were applied in the atomic charge distribution to evaluate the susceptibility to the population method.

Occurrence and abatement of volatile sulfur compounds during biogas production.

PubMed

Andersson, Fräs Annika T; Karlsson, Anna; Svensson, Bo H; Ejlertsson, Jörgen

2004-07-01

Volatile sulfur compounds (VSCs) in biogas originating from a biogas production plant and from a municipal sewage water treatment plant were identified. Samples were taken at various stages of the biogas-producing process, including upgrading the gas to vehicle-fuel quality. Solid-phase microextraction was used for preconcentration of the VSCs, which were subsequently analyzed using gas chromatography in combination with mass spectrometry. Other volatile organic compounds present also were identified. The most commonly occurring VSCs in the biogas were hydrogen sulfide, carbonyl sulfide, methanethiol, dimethyl sulfide, and dimethyl disulfide, and hydrogen sulfide was not always the most abundant sulfur (S) compound. Besides VSCs, oxygenated organic compounds were commonly present (e.g., ketones, alcohols, and esters). The effect of adding iron chloride to the biogas reactor on the occurrence of VSCs also was investigated. It was found that additions of 500-g/m3 substrate gave an optimal removal of VSCs. Also, the use of a prefermentation step could reduce the amount of VSCs formed in the biogas process. Moreover, in the carbon dioxide scrubber used for upgrading the gas, VSCs were removed efficiently, leaving traces (ppbv levels). The scrubber also removed other organic compounds.

Research on the degradation mechanism of dimethyl phthalate in drinking water by strong ionization discharge

NASA Astrophysics Data System (ADS)

Hong, ZHAO; Chengwu, YI; Rongjie, YI; Huijuan, WANG; Lanlan, YIN; I, N. MUHAMMAD; Zhongfei, MA

2018-03-01

The degradation mechanism of dimethyl phthalate (DMP) in the drinking water was investigated using strong ionization discharge technology in this study. Under the optimized condition, the degradation efficiency of DMP in drinking water was up to 93% in 60 min. A series of analytical techniques including high-performance liquid chromatography, liquid chromatography mass spectrometry, total organic carbon analyzer and ultraviolet-visible spectroscopy were used in the study. It was found that a high concentration of ozone (O3) produced by dielectric barrier discharge reactor was up to 74.4 mg l-1 within 60 min. Tert-butanol, isopropyl alcohol, carbonate ions ({{{{CO}}}3}2-) and bicarbonate ions ({{{{HCO}}}3}-) was added to the sample solution to indirectly prove the presence and effect of hydroxyl radicals (·OH). These analytical findings indicate that mono-methyl phthalate, phthalic acid (PA) and methyl ester PA were detected as the major intermediates in the process of DMP degradation. Finally, DMP and all products were mineralized into carbon dioxide (CO2) and water (H2O) ultimately. Based on these analysis results, the degradation pathway of DMP by strong ionization discharge technology were proposed.

Impacts of dimethyl phthalate on the bacterial community and functions in black soils

PubMed Central

Wang, Zhi-Gang; Hu, Yun-Long; Xu, Wei-Hui; Liu, Shuai; Hu, Ying; Zhang, Ying

2015-01-01

Dimethyl phthalate (DMP), a known endocrine disruptor and one of the phthalate esters (PAEs), is a ubiquitous pollutant. Its impacts on living organisms have aroused great concern. In this study, the impacts of DMP contamination on bacterial communities and functions were tested by using microcosm model in black soils. The results showed that the operational taxonomic unit (OTUs) richness and bacterial diversity were reduced by DMP contamination. The relative percentages of some genera associated with nitrogen metabolism were increased by DMP contamination, while the relative percentages of some other genera that were extremely beneficial to soil health were decreased by DMP contamination. Further, the relative percentages of some genera that possessed the capability to degrade DMP were increased by the DMP treatment at low concentrations (5, 10, and 20 mg/kg), but were decreased by the high concentration DMP treatment (40 mg/kg). Clearly, DMP contamination changed the bacterial community structure and disturbed the metabolic activity and functional diversity of the microbes in black soils. Our results suggest that DMP pollution can alter the metabolism and biodiversity of black soil microorganisms, thereby directly impact fertility and ecosystem functions. PMID:25999932

Tough soluble aromatic thermoplastic copolyimides

NASA Technical Reports Server (NTRS)

Bryant, Robert G. (Inventor)

2000-01-01

Tough, soluble, aromatic, thermoplastic copolyimides were prepared by reacting 4,4'-oxydiphthalic anhydride, 3,4,3',4'-biphenyltetracarboxylic dianhydride and 3,4'-oxydianiline. Alternatively, these copolyimides may be prepared by reacting 4,4'-oxydiphthalic anhydride with 3,4,3',4'-biphenyltetracarboxylic dianhydride and 3,4'-oxydiisocyanate. Also, the copolyimide may be prepared by reacting the corresponding tetra acid and ester precursors of 4,4'-oxydiphthalic anhydride and 3,4,3',4'-biphenyltetracarboxylic dianhydride with 3,4'-oxydianiline. These copolyimides were found to be soluble in common amide solvents such as N,N'-dimethyl acetamide, N-methylpyrrolidinone, and dimethylformamide allowing them to be applied as the fully imidized copolymer and to be used to prepare a wide range of articles.

Secondary metabolites from Penicillium pinophilum SD-272, a marine sediment-derived fungus.

PubMed

Wang, Ming-Hui; Li, Xiao-Ming; Li, Chun-Shun; Ji, Nai-Yun; Wang, Bin-Gui

2013-06-21

Two new secondary metabolites, namely, pinodiketopiperazine A (1) and 6,7-dihydroxy-3-methoxy-3-methylphthalide (2), along with alternariol 2,4-dimethyl ether (3) and L-5-oxoproline methyl ester (4), which were isolated from a natural source for the first time but have been previously synthesized, were characterized from the marine sediment-derived fungus Penicillium pinophilum SD-272. In addition, six known metabolites (5-10) were also identified. Their structures were elucidated by analysis of the NMR and mass spectroscopic data. The absolute configuration of compound 1 was determined by experimental and calculated ECD spectra. Compound 2 displayed potent brine shrimp (Artemia salina) lethality with LD₅₀ 11.2 μM.

Rotational Investigation of the Adducts of Formic Acid with Alcohols, Ethers and Esters

NASA Astrophysics Data System (ADS)

Evangelisti, Luca; Spada, Lorenzo; Li, Weixing; Caminati, Walther

2016-06-01

Mixtures of formic acid with methyl alcohol, with isopropyl alcohol, with tert-butyl alcohol, with dimethylether and with isopropylformiate have been supersonically expanded as pulsed jets. The obtained cool plumes have been analyzed by Fourier transform microwave spectroscopy. It has been possible to assign the rotational spectra of the 1:1 adducts of formic acid with tert-butyl alcohol, with dimethyl ether and with isopropylformiate. The conformational shapes and geometries of these adducts, as well as the topologies of their itermolecular hydrogen bonds will be presented. An explanation is given of the failure of the assignments of the rotational spectra of the adducts of formic acid with methyl alcohol and isopropyl alcohol.

COMBINATION DOSE OF TWO PHTHALATES ADDITIVELY DEPRESSES TESTOSTERONE PRODUCTION AND INSL3 GENE EXPRESSION IN MALE RAT FETUSES

EPA Science Inventory

Diethylhexyl phthalate (DEHP) and di(n-butyl) phthalate (DBP) are phthalate esters used to modify plastic and polymer textures. Individually,in uteroexposure to DEHP and DBP inhibit reproductive tract development,induce reproductive organ malformations, and reduce testosterone (T...

ACADEMY OF SCIENCES AZERBAYDZHAN. INSTITUTE OF ADDITIVE CHEMISTRY. ADDITIVES AND LUBRICANTS, QUESTIONS OF SYNTHESIS, RESEARCH ON THE APPLICATION OF ADDITIVES AND LUBRICANTS, FUELS, AND POLYMER MATERIALS (SELECTED ARTICLES),

DTIC Science & Technology

an alkylphenol ); Synthesis and investigation of the new antioxidative INKhP-40 Additive; Synthesis and investigation of N-butylurethane-based antioxidative additive; and Synthesis of mixed esters of dithiophosphoric acid.

Synthetic polymers enable non-vitreous cellular cryopreservation by reducing ice crystal growth during thawing.

PubMed

Deller, Robert C; Vatish, Manu; Mitchell, Daniel A; Gibson, Matthew I

2014-01-01

The cryopreservation of cells, tissue and organs is fundamental to modern biotechnology, transplantation medicine and chemical biology. The current state-of-the-art method of cryopreservation is the addition of large amounts of organic solvents such as glycerol or dimethyl sulfoxide, to promote vitrification and prevent ice formation. Here we employ a synthetic, biomimetic, polymer, which is capable of slowing the growth of ice crystals in a manner similar to antifreeze (glyco)proteins to enhance the cryopreservation of sheep and human red blood cells. We find that only 0.1 wt% of the polymer is required to attain significant cell recovery post freezing, compared with over 20 wt% required for solvent-based strategies. These results demonstrate that synthetic antifreeze (glyco)protein mimics could have a crucial role in modern regenerative medicine to improve the storage and distribution of biological material for transplantation.

Solvent-modified ultrafast decay dynamics in conjugated polymer/dye labeled single stranded DNA

NASA Astrophysics Data System (ADS)

Kim, Inhong; Kang, Mijeong; Woo, Han Young; Oh, Jin-Woo; Kyhm, Kwangseuk

2015-07-01

We have investigated that organic solvent (DMSO, dimethyl sulfoxide) modifies energy transfer efficiency between conjugated polymers (donors) and fluorescein-labeled single stranded DNAs (acceptors). In a mixture of buffer and organic solvent, fluorescence of the acceptors is significantly enhanced compared to that of pure water solution. This result can be attributed to change of the donor-acceptor environment such as decreased hydrophobicity of polymers, screening effect of organic solvent molecules, resulting in an enhanced energy transfer efficiency. Time-resolved fluorescence decay of the donors and the acceptors was modelled by considering the competition between the energy harvesting Foerster resonance energy transfer and the energy-wasting quenching. This enables to quantity that the Foerster distance (R0 = 43.3 Å) and resonance energy transfer efficiency (EFRET = 58.7 %) of pure buffer solution become R0 = 38.6 Å and EFRET = 48.0 % when 80% DMSO/buffer mixture is added.

Redox-active charge carriers of conducting polymers as a tuner of conductivity and its potential window

PubMed Central

Park, Han-Saem; Ko, Seo-Jin; Park, Jeong-Seok; Kim, Jin Young; Song, Hyun-Kon

2013-01-01

Electric conductivity of conducting polymers has been steadily enhanced towards a level worthy of being called its alias, “synthetic metal”. PEDOT:PSS (poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate)), as a representative conducting polymer, recently reached around 3,000 S cm−1, the value to open the possibility to replace transparent conductive oxides. The leading strategy to drive the conductivity increase is solvent annealing in which aqueous solution of PEDOT:PSS is treated with an assistant solvent such as DMSO (dimethyl sulfoxide). In addition to the conductivity enhancement, we found that the potential range in which PEDOT:PSS is conductive is tuned wider into a negative potential direction by the DMSO-annealing. Also, the increase in a redox-active fraction of charge carriers is proposed to be responsible for the enhancement of conductivity in the solvent annealing process. PMID:23949091

Antimicrobial activity of chemically modified dextran derivatives.

PubMed

Tuchilus, Cristina G; Nichifor, Marieta; Mocanu, Georgeta; Stanciu, Magdalena C

2017-04-01

Cationic amphiphilic dextran derivatives with a long alkyl group attached to the reductive end of the polysaccharide chain and quaternary ammonium groups attached as pendent groups to the main dextran backbone were synthesized and tested for their antimicrobial properties against several bacteria and fungi strains. Dependence of antimicrobial activity on both polymer chemical composition (dextran molar mass, length of end alkyl group and chemical structure of ammonium groups) and type of microbes was highlighted by disc-diffusion method (diameter of inhibition zone) and broth microdilution method (minimum inhibitory concentrations). Polymers had antimicrobial activity for all strains studied, except for Pseudomonas aeruginosa ATCC 27853. The best activity against Staphylococcus aureus (Minimun Inhibitory Concentration 60μg/mL) was provided by polymers obtained from dextran with lower molecular mass (Mn=4500), C 12 H 25 or C 18 H 37 end groups, and N,N-dimethyl-N-benzylammonium pendent groups. Copyright © 2017 Elsevier Ltd. All rights reserved.

Molecularly imprinted polymers for separation of various sugars from human urine.

PubMed

Okutucu, Burcu; Onal, Seçil

2011-12-15

Molecularly imprinted polymers were the new, simple and unexpensive materials that can be used in several clinical applications. Phenylboronic acid has been frequently used as functional monomer for the covalent imprinting of diols. In this study, the phenylboronic acid esters of fructose, galactose, glucose and raffinose were synthesized and then used as template analytes. The adsorption capacities of fructose, galactose and glucose-phenylboronic acid imprinted polymers were 75, 10 and 30%, respectively. The batch rebinding studies and Scatchard analysis were done for all sugar imprinted polymer. Glucose is one of the mostly found sugar in the urine. The glucose:phenylboronic acid imprinted polymer was used for the analysis of glucose, fructose, galactose, sucrose, maltose, lactose and raffinose in spiked urine. The selectivity of glucose:phenylboronic acid imprinted polymer to urine monosaccharides was found as nearly 45-55% and to di- and polysaccharides was found as 30-35%, respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

Effects of Terminal Sterilization on PEG-Based Bioresorbable Polymers Used in Biomedical Applications.

PubMed

Bhatnagar, Divya; Dube, Koustubh; Damodaran, Vinod B; Subramanian, Ganesan; Aston, Kenneth; Halperin, Frederick; Mao, Meiyu; Pricer, Kurt; Murthy, N Sanjeeva; Kohn, Joachim

2016-10-01

The effects of ethylene oxide (EO), vaporized hydrogen peroxide (VHP), gamma (γ) radiation, and electron-beam (E-beam) on the physiochemical and morphological properties of medical device polymers are investigated. Polymers with ether, carbonate, carboxylic acid, amide and ester functionalities are selected from a family of poly(ethylene glycol) (PEG) containing tyrosine-derived polycarbonates (TyrPCs) to include slow, medium, fast, and ultrafast degrading polymers. Poly(lactic acid) (PLA) is used for comparison. Molecular weight ( M w ) of all tested polymers decreases upon gamma and E-beam, and this effect becomes more pronounced at higher PEG content. Gamma sterilization increases the glass transition temperature of polymers with high PEG content. EO esterifies the carboxylic acid groups in desaminotyrosol-tyrosine (DT) and causes significant degradation. VHP causes hydroxylation of the phenyl ring, and hydrolytic degradation. This study signifies the importance of the chemical composition when selecting a sterilization method, and provides suggested conditions for each of the sterilization methods.

Biodegradable Shape Memory Polymers in Medicine.

PubMed

Peterson, Gregory I; Dobrynin, Andrey V; Becker, Matthew L

2017-11-01

Shape memory materials have emerged as an important class of materials in medicine due to their ability to change shape in response to a specific stimulus, enabling the simplification of medical procedures, use of minimally invasive techniques, and access to new treatment modalities. Shape memory polymers, in particular, are well suited for such applications given their excellent shape memory performance, tunable materials properties, minimal toxicity, and potential for biodegradation and resorption. This review provides an overview of biodegradable shape memory polymers that have been used in medical applications. The majority of biodegradable shape memory polymers are based on thermally responsive polyesters or polymers that contain hydrolyzable ester linkages. These materials have been targeted for use in applications pertaining to embolization, drug delivery, stents, tissue engineering, and wound closure. The development of biodegradable shape memory polymers with unique properties or responsiveness to novel stimuli has the potential to facilitate the optimization and development of new medical applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Resist Rolymers. 8. Thermolysis of Bromine Containing Acrylate Polymers.

DTIC Science & Technology

1987-06-01

bromine containing polymers is particularly interesting because of their role as proven flame retardants . The bromine ...BrI IC COOH I -co2 (1 CH MeI I Br --- CH 2 ---- The presence of bromine on ester units apparently alters the principal mode of degradation of the...CH2---C C--- I I I I C-O C-O C C=O 0’ OCH2CH2Br 0 0 + ’OCH2CH 2Br (6) As described earlier6 bromoethoxy radical loose bromine atom at

Polyphosphazene/Nano-Hydroxyapatite Composite Microsphere Scaffolds for Bone Tissue Engineering

PubMed Central

Nukavarapu, Syam P.; Kumbar, Sangamesh G.; Brown, Justin L.; Krogman, Nicholas R.; Weikel, Arlin L.; Hindenlang, Mark D.; Nair, Lakshmi S.; Allcock, Harry R; Laurencin, Cato T.

2009-01-01

The non-toxic, neutral degradation products of amino acid ester polyphosphazenes make them ideal candidates for in vivo orthopaedic applications. The quest for new osteocompatible materials for load bearing tissue engineering applications has led us to investigate mechanically competent amino acid ester substituted polyphosphazenes. In this study, we have synthesized three biodegradable polyphosphazenes substituted with side groups namely leucine, valine and phenylalanine ethyl esters. Of these polymers, the phenylalanine ethyl ester substituted polyphosphazene showed the highest glass transition temperature (41.6 °C) and hence was chosen as a candidate material for forming composite microspheres with 100 nm sized hydroxyapatite (nHAp). The fabricated composite microspheres were sintered into a three-dimensional (3-D) porous scaffold by adopting a dynamic solvent sintering approach. The composite microsphere scaffolds showed compressive moduli of 46–81 MPa with mean pore diameters in the range of 86–145 µm. The three-dimensional polyphosphazene-nHAp composite microsphere scaffolds showed good osteoblast cell adhesion, proliferation and alkaline phosphatase expression, and are potential suitors for bone tissue engineering applications. PMID:18517248

Vinyl Sulfonate Esters: Efficient Chain Transfer Agents for the 3D-Printing of Tough Photopolymers without Retardation.

PubMed

Seidler, Konstanze; Griesser, Markus; Kury, Markus; Reghunathan, Harikrishna; Dorfinger, Peter; Koch, Thomas; Svirkova, Anastasiya; Marchetti-Deschmann, Martina; Stampfl, Jürgen; Moszner, Norbert; Gorsche, Christian; Liska, Robert

2018-05-04

Photoinitiated radical polymer network formation is lacking freedom for tailored network design. Resulting inhomogeneous network architectures and brittle material behavior of such glassy-type networks limit the commercial application of photopolymers in 3D printing, biomedicine or microelectronics. An ester-activated vinyl sulfonate ester (EVS) is presented for the rapid formation of tailored methacrylate-based networks with nearly no retardation, reduced shrinkage stress, high monomer conversion and improved material toughness. Laser flash photolysis followed by theoretical calculations and photoreactor studies elucidate the fast chain transfer reaction and exceptional regulating ability of EVS. Final photopolymer networks exhibit high tensile strength, improved elongation at break and high impact resistance, while maintaining high modulus and hardness at ambient conditions. These findings make EVS an exceptional candidate for the 3D printing of tough photopolymers. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanoporous Polymer Films of Cyanate Ester Resins Designed by Using Ionic Liquids as Porogens.

PubMed

Fainleib, Alexander; Vashchuk, Alina; Starostenko, Olga; Grigoryeva, Olga; Rogalsky, Sergiy; Nguyen, Thi-Thanh-Tam; Grande, Daniel

2017-12-01

Novel nanoporous film materials of thermostable cyanate ester resins (CERs) were generated by polycyclotrimerization of dicyanate ester of bisphenol E in the presence of varying amounts (from 20 to 40 wt%) of an ionic liquid (IL), i.e., 1-heptylpyridinium tetrafluoroborate, followed by its quantitative extraction after complete CER network formation. The completion of CER formation and IL extraction was assessed using gel fraction content determination, FTIR, 1 H NMR, and energy-dispersive X-ray spectroscopy (EDX). SEM and DSC-based thermoporometry analyses demonstrated the formation of nanoporous structures after IL removal from CER networks, thus showing the effective role of IL as a porogen. Pore sizes varied from ~20 to ~180 nm with an average pore diameter of around 45-60 nm depending on the initial IL content. The thermal stability of nanoporous CER-based films was investigated by thermogravimetric analysis.

Nanoporous Polymer Films of Cyanate Ester Resins Designed by Using Ionic Liquids as Porogens

NASA Astrophysics Data System (ADS)

Fainleib, Alexander; Vashchuk, Alina; Starostenko, Olga; Grigoryeva, Olga; Rogalsky, Sergiy; Nguyen, Thi-Thanh-Tam; Grande, Daniel

2017-02-01

Novel nanoporous film materials of thermostable cyanate ester resins (CERs) were generated by polycyclotrimerization of dicyanate ester of bisphenol E in the presence of varying amounts (from 20 to 40 wt%) of an ionic liquid (IL), i.e., 1-heptylpyridinium tetrafluoroborate, followed by its quantitative extraction after complete CER network formation. The completion of CER formation and IL extraction was assessed using gel fraction content determination, FTIR, 1H NMR, and energy-dispersive X-ray spectroscopy (EDX). SEM and DSC-based thermoporometry analyses demonstrated the formation of nanoporous structures after IL removal from CER networks, thus showing the effective role of IL as a porogen. Pore sizes varied from 20 to 180 nm with an average pore diameter of around 45-60 nm depending on the initial IL content. The thermal stability of nanoporous CER-based films was investigated by thermogravimetric analysis.

Polymer-Based Protein Engineering: Synthesis and Characterization of Armored, High Graft Density Polymer-Protein Conjugates.

PubMed

Carmali, Sheiliza; Murata, Hironobu; Cummings, Chad; Matyjaszewski, Krzysztof; Russell, Alan J

2017-01-01

Atom transfer radical polymerization (ATRP) from the surface of a protein can generate remarkably dense polymer shells that serve as armor and rationally tune protein function. Using straightforward chemistry, it is possible to covalently couple or display multiple small molecule initiators onto a protein surface. The chemistry is fine-tuned to be sequence specific (if one desires a single targeted site) at controlled density. Once the initiator is anchored on the protein surface, ATRP is used to grow polymers on protein surface, in situ. The technique is so powerful that a single-protein polymer conjugate molecule can contain more than 90% polymer coating by weight. If desired, stimuli-responsive polymers can be "grown" from the initiated sites to prepare enzyme conjugates that respond to external triggers such as temperature or pH, while still maintaining enzyme activity and stability. Herein, we focus mainly on the synthesis of chymotrypsin-polymer conjugates. Control of the number of covalently coupled initiator sites by changing the stoichiometric ratio between enzyme and the initiator during the synthesis of protein-initiator complexes allowed fine-tuning of the grafting density. For example, very high grafting density chymotrypsin conjugates were prepared from protein-initiator complexes to grow the temperature-responsive polymers, poly(N-isopropylacrylamide), and poly[N,N'-dimethyl(methacryloyloxyethyl) ammonium propane sulfonate]. Controlled growth of polymers from protein surfaces enables one to predictably manipulate enzyme kinetics and stability without the need for molecular biology-dependent mutagenesis. © 2017 Elsevier Inc. All rights reserved.

Magnetic Field Effect in Conjugated Molecules-Based Devices

DTIC Science & Technology

2017-10-23

triplet annihilation process (TTA) process in charge- balanced polymer light emitting diode (PLED) containing a super yellow poly-(phenylene vinylene...current density. Our results demonstrate a clear correlation between TTA process and current density as well as temperature in charge- balanced SY-PPV...dimethyl sulfoxide (DMSO) (7:3, v/v) at 60 °C for 12 h inside the nitrogen -filled glove box. The perovskite films were spin-cast by a consecutive two-step

Structure Formation in Solutions of Rigid Polymers Undergoing a Phase Transition

DTIC Science & Technology

1987-04-01

cyclohexene dioxide (ERL-4206) - 10 g. nonenyl succinic anhydride (NSA) - 26 g. dimethyl amino ethanol ( DMAE ) - 0.4 g. After infiltration, short segments...existence of a significant number of defects within the individual microfibril. The presence of defects in the lateral packing of PBT chains is also suggested...of the D- and L- enantiomers yields a nematic phase. The ordered phases exhi- bit complex textures due to defects (disclinations) which depend on

Synthesis and Characterization of Bioactive Tamoxifen-conjugated Polymers

PubMed Central

Rickert, Emily L.; Trebley, Joseph P.; Peterson, Anton C.; Morrell, Melinda M.; Weatherman, Ross V.

2008-01-01

Macromolecular conjugates of tamoxifen could perhaps be used to circumvent some of the limitations of the extensively used breast cancer drug. To test the feasibility of these conjugates, a 4-hydroxytamoxifen analog was conjugated to a diaminoalkyl linker and then conjugated to activated esters of a poly(methacrylic acid) polymer synthesized by atom transfer radical polymerization. A polymer conjugated to the 4-hydroxytamoxifen analog with a six carbon linker showed high affinity for both estrogen receptor alpha and estrogen receptor beta and potent antagonism of the estrogen receptor in cell-based transcriptional reporter assays. These results suggest that the conjugation of 4-hydroxytamoxifen to a polymer results in a macromolecular conjugate that can display ligand in a manner that can be recognized by estrogen receptor and still act as a potent antiestrogen in cells. PMID:17929966

End Functionalized Nonionic Water-Dispersible Conjugated Polymers.

PubMed

Zhan, Ruoyu; Liu, Bin

2017-09-01

2,7-Dibromofluorene monomers carrying two or four oligo(ethylene glycol) (OEG) side chains are synthesized. Heck coupling between the monomers and 1,4-divinylbenzene followed by end capping with [4-(4-bromophenoxy)butyl]carbamic acid tert-butyl ester leads to two nonionic water-dispersible poly(fluorene-alt-1,4-divinylenephenylene)s end-functionalized with amine groups after hydrolysis. In water, the polymer with a lower OEG density (P1) has poor water dispersibility with a quantum yield of 0.24, while the polymer with a higher OEG density (P2) possesses excellent water-dispersibility with a high quantum yield of 0.45. Both polymers show fluorescence enhancement and blue-shifted absorption and emission maxima in the presence of surfactant sodium dodecyl sulfate and dodecyltrimethylammonium bromide. The polymers are also resistant to ionic strength with minimal nonspecific interactions to bovine serum albumin. When biotin is incorporated into the end of the polymer backbones through N-hydroxysuccinimide/amine coupling reaction, the biotinylated polymers interact specifically with streptavidin on solid surface. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Biocompatibility of Synthetic Poly(ester urethane)/Polyhedral Oligomeric Silsesquioxane Matrices with Embryonic Stem Cell Proliferation and Differentiation

PubMed Central

Guo, Yan-Lin; Wang, Wenshou; Otaigbe, Joshua U.

2010-01-01

Incorporation of polyhedral oligomeric silsesquioxanes (POSS) into poly (ester urethane)s (PEU) as a building block results in a PEU/POSS hybrid polymer with increased mechanical strength and thermostability. An attractive feature of the new polymer is that it forms a porous matrix when cast in the form of a thin film, making it potentially useful in tissue engineering. In this study, we present detailed microscopic analysis of the PEU/POSS matrix and demonstrate its biocompatibility with cell culture. The PEU/POSS polymer forms a continuous porous matrix with open pores and interconnected grooves. From SEM image analysis, it is calculated that there are about 950 pores per mm2 of the matrix area with pore size ranging from 1 to 15 μm in diameter. The area occupied by the pores represents approximately 7.6 % of matrix area. Using mouse embryonic stem cells (ESCs), we demonstrate that the PEU/POSS matrix provides excellent support for cell proliferation and differentiation. Under the cell culture condition optimized to maintain self-renewal, ESCs grown on a PEU/POSS matrix exhibit undifferentiated morphology, express pluripotency markers, and have similar growth rate to cells grown on gelatin. When induced for differentiation, ESCs underwent dramatic morphological change, characterized by the loss of clonogenecity and increased cell size with well-expanded cytoskeleton networks. Differentiated cells are able to form a continuous monolayer that is closely embedded on the matrix. The excellent compatibility between the PEU/POSS matrix and ESC proliferation/differentiation demonstrates the potential of using PEU/POSS polymers in future ESC-based tissue engineering. PMID:20213627

An artificial molecular machine that builds an asymmetric catalyst

NASA Astrophysics Data System (ADS)

De Bo, Guillaume; Gall, Malcolm A. Y.; Kuschel, Sonja; De Winter, Julien; Gerbaux, Pascal; Leigh, David A.

2018-05-01

Biomolecular machines perform types of complex molecular-level tasks that artificial molecular machines can aspire to. The ribosome, for example, translates information from the polymer track it traverses (messenger RNA) to the new polymer it constructs (a polypeptide)1. The sequence and number of codons read determines the sequence and number of building blocks incorporated into the biomachine-synthesized polymer. However, neither control of sequence2,3 nor the transfer of length information from one polymer to another (which to date has only been accomplished in man-made systems through template synthesis)4 is easily achieved in the synthesis of artificial macromolecules. Rotaxane-based molecular machines5-7 have been developed that successively add amino acids8-10 (including β-amino acids10) to a growing peptide chain by the action of a macrocycle moving along a mono-dispersed oligomeric track derivatized with amino-acid phenol esters. The threaded macrocycle picks up groups that block its path and links them through successive native chemical ligation reactions11 to form a peptide sequence corresponding to the order of the building blocks on the track. Here, we show that as an alternative to translating sequence information, a rotaxane molecular machine can transfer the narrow polydispersity of a leucine-ester-derivatized polystyrene chain synthesized by atom transfer radical polymerization12 to a molecular-machine-made homo-leucine oligomer. The resulting narrow-molecular-weight oligomer folds to an α-helical secondary structure13 that acts as an asymmetric catalyst for the Juliá-Colonna epoxidation14,15 of chalcones.

Novel fatty acid methyl esters from the actinomycete Micromonospora aurantiaca

PubMed Central

Bruns, Hilke; Riclea, Ramona

2011-01-01

Summary The volatiles released by Micromonospora aurantiaca were collected by means of a closed-loop stripping apparatus (CLSA) and analysed by GC–MS. The headspace extracts contained more than 90 compounds from different classes. Fatty acid methyl esters (FAMEs) comprised the major compound class including saturated unbranched, monomethyl and dimethyl branched FAMEs in diverse structural variants: Unbranched, α-branched, γ-branched, (ω−1)-branched, (ω−2)-branched, α- and (ω−1)-branched, γ- and (ω−1)-branched, γ- and (ω−2)-branched, and γ- and (ω−3)-branched FAMEs. FAMEs of the last three types have not been described from natural sources before. The structures for all FAMEs have been suggested based on their mass spectra and on a retention index increment system and verified by the synthesis of key reference compounds. In addition, the structures of two FAMEs, methyl 4,8-dimethyldodecanoate and the ethyl-branched compound methyl 8-ethyl-4-methyldodecanoate were deduced from their mass spectra. Feeding experiments with isotopically labelled [2H10]leucine, [2H10]isoleucine, [2H8]valine, [2H5]sodium propionate, and [methyl-2H3]methionine demonstrated that the responsible fatty acid synthase (FAS) can use different branched and unbranched starter units and is able to incorporate methylmalonyl-CoA elongation units for internal methyl branches in various chain positions, while the methyl ester function is derived from S-adenosyl methionine (SAM). PMID:22238549

Effects of six priority controlled phthalate esters with long-term low-dose integrated exposure on male reproductive toxicity in rats.

PubMed

Gao, Hai-Tao; Xu, Run; Cao, Wei-Xin; Qian, Liang-Liang; Wang, Min; Lu, Lingeng; Xu, Qian; Yu, Shu-Qin

2017-03-01

Human beings are inevitably exposed to ubiquitous phthalate esters (PEs) surroundings. The purposes of this study were to investigate the effects of long-term low-dose exposure to the mixture of six priority controlled phthalate esters (MIXPs): dimethyl phthalate (DMP), diethyl phthalate (DEP), di(n-butyl) phthalate (DBP), butyl benzyl phthalate (BBP), di(2-ethyhexyl) phthalate (DEHP) and di-n-octyl phthalate (DNOP), on male rat reproductive system and further to explore the underlying mechanisms of the reproductive toxicity. The male rats were orally exposed to either sodium carboxymethyl cellulose as controls or MIXPs at three different low-doses by gavage for 15 weeks. Testosterone and luteinizing hormone (LH) in serum were analyzed, and pathological examinations were performed for toxicity evaluation. Steroidogenic proteins (StAR, P450scc, CYP17A1 and 17β-HSD), cell cycle and apoptosis-related proteins (p53, Chk1, Cdc2, CDK6, Bcl-2 and Bax) were measured for mechanisms exploration. MIXPs with long-term low-dose exposure could cause male reproductive toxicity to the rats, including the decrease of both serum and testicular testosterone, and the constructional damage of testis. These effects were related to down-regulated steroidogenic proteins, arresting cell cycle progression and promoting apoptosis in rat testicular cells. The results indicate that MIXPs with long-term low-dose exposure may pose male reproductive toxicity in human. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dummy molecularly imprinted microbeads as solid-phase extraction material for selective determination of phthalate esters in water.

PubMed

Özer, Elif Tümay; Osman, Bilgen; Yazıcı, Tuğçe

2017-06-02

The aim of this study was to investigate the usability of newly synthesized dummy molecularly imprinted microbeads (DMIMs) as a solid phase extraction (SPE) material to determine six phthalate esters (PEs) in water by GC-MS analysis. Diethyl phthalate (DEP) was used as a dummy template to prepare poly(ethylene glycol dimethacrylate N-methacryloyl-l-tryptophan methyl ester) [PEMATrp)] DMIMs by using suspension polymerization. The PEMATrp DMIMs were characterized by using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Firstly, the adsorption capacities of the DMIMs prepared in different template molecule (DEP) to functional monomer (MATrp) ratios were investigated by using DEP solutions in the concentration range of 1-500mg/L at pH 3.0. Styrene and vanillic acid were used to evaluate the selectivity of the prepared DMIMs towards the template molecule (DEP). Then, the best analytical conditions were investigated for the simultaneous determination of dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), benzylbutyl phthalate (BBP), di-(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DnOP) in aqueous media by using the PEMATrp DMIMs as SPE material. Validation experiments showed that the PEMATrp DMIMs-SPE method had good linearity at 12.5-250.0μg/L (0.988-0.999), good precision (1.2-5.9%), and limits of detection in a range of 0.31-0.41μg/L. Copyright © 2017 Elsevier B.V. All rights reserved.

Binding specificity of the juvenile hormone carrier protein from the hemolymph of the tobacco hornworm Manduca sexta Johannson (Lepidoptera: Sphingidae).

PubMed

Peterson, R C; Reich, M F; Dunn, P E; Law, J H; Katzenellnbogen, J A

1977-05-17

A series of analogues of insect juvenile hormone (four geometric isomers of methyl epoxyfarnesenate, several para-substituted epoxygeranyl phenyl ethers, and epoxyfarnesol and its acetate and haloacetate derivatives) was prepared to investigate the binding specificity of the hemolymph juvenile hormone binding protein from the tobacco hornworm Manduct sexta. The relative binding affinities were determined by a competition assay against radiolabeled methyl (E,E)-3,11-dimethyl-7-ethyl-cis-10,11-epoxytrideca-2,6-dienoate (JH I). The ratio of dissociation constants was estimated by plotting competitor data according to a linear transformation of the dissociation equations describing competition of two ligands for a binding protein. The importance of the geometry of the sesquiterpene hydrocarbon chain is indicated by the fact that the binding affinity is decreased as Z (cis) double bonds are substituted for E (trans) double bonds in the methyl epoxyfarnesenate series; the unepoxidized analogues do not bind. A carboxylic ester function is important although its orientation can be reversed, as indicated by the good binding of epoxyfarnesyl acetate. In the monoterpene series, methyl epoxygeranoate shows no affinity for the binding protein, but substitution of a phenyl or p-carbomethoxyphenyl ether for the ester function imparts a low, but significant affinity. These data taken together with earlier results indicate that the binding site for juvenile hormone in the hemolymph binding protein is characterized by a sterically defined hydrophobic region with polar sites that recognize the epoxide and the ester functions.

Value-added processing of crude glycerol into chemicals and polymers.

PubMed

Luo, Xiaolan; Ge, Xumeng; Cui, Shaoqing; Li, Yebo

2016-09-01

Crude glycerol is a low-value byproduct which is primarily obtained from the biodiesel production process. Its composition is significantly different from that of pure glycerol. Crude glycerol usually contains various impurities, such as water, methanol, soap, fatty acids, and fatty acid methyl esters. Considerable efforts have been devoted to finding applications for converting crude glycerol into high-value products, such as biofuels, chemicals, polymers, and animal feed, to improve the economic viability of the biodiesel industry and overcome environmental challenges associated with crude glycerol disposal. This article reviews recent advances of biological and chemical technologies for value-added processing of crude glycerol into chemicals and polymers, and provides strategies for addressing production challenges. Copyright © 2016 Elsevier Ltd. All rights reserved.

Crosslinking hydroxylated reduced graphene oxide with RAFT-CTA: A nano-initiator for preparation of well-defined amino acid-based polymer nanohybrids.

PubMed

Namvari, Mina; Biswas, Chandra S; Wang, Qiao; Liang, Wenlang; Stadler, Florian J

2017-10-15

Here, we demonstrate a novel reversible addition-fragmentation chain transfer agent (RAFT-CTA)-modified reduced graphene oxide nanosheets (CTA-rGONSs) by crosslinking rGONSs with a RAFT-CTA via esterification reaction. These nano CTA-rGONSs were used to polymerize a hydrophobic amino acid-based methacrylamide (N-acryloyl-l-phenylalanine methyl ester) monomer with different monomer/initiator ratios. Thermogravimetric analysis showed that the polymer-graphene composites were thermally more stable than GO itself. M n of the polymers increased with increasing monomer/initiator ratio, while the polydispersity index decreased, indicating controlled polymerization. The composites were stable in DMF even after two months. Copyright © 2017 Elsevier Inc. All rights reserved.

ACCUMULATION OF POLY-B-HYDROXYBUTYRATE IN A METHANE- ENRICHED, HALOGENATED, HYDROCARBON-DEGRADING SOIL COLUMN: IMPLICATIONS FOR MICROBIAL COMMUNITY STRUCTURE AND NUTRITIONAL STATUS

EPA Science Inventory

The prokarotic, endogenous storage polymer poly--hydroxybutyrate (PHB) accumulated in soil from a methane-enriched, halogenated hydrocarbon-degrading soil column. Based on phospholipid ester-linked fatty acid (PLFA) profiles, this mocrocosm has been previously reported to be sign...

Preparation and characterization of the nanocomposites from chemically modified nanocellulose and poly(lactic acid)

Treesearch

Liqing Wei; Shupin Luo; Armando G. McDonald; Umesh P. Agarwal; Kolby C. Hirth; Laurent M. Matuana; Ronald C. Sabo; Nicole M. Stark

2017-01-01

Cellulose nanocrystals (CNCs) are renewable and sustainable filler for polymeric nanocomposites. However, their high hydrophilicity limits their use with hydrophobic polymer for composite materials. In this study, freeze-dried CNCs were modified by transesterification with canola oil fatty acid methyl ester to reduce the hydrophilicity. The transesterified CNCs (CNCFE...

Phenolics and compartmentalization in the sapwood of broad-leaved trees

Treesearch

Kevin T. Smith

1997-01-01

Tree survival depends on the chemistry of phenolic compounds, a broad class of chemicals characterized by a hydroxylated benzene ring. In trees, phenolics occur frequently as polymers, acids, or glycosylated esters and perform diverse functions. For example, lignin, a phenylpropane heteropolymer, provides structural strength to wood. The induced production of phenols...

40 CFR 180.930 - Inert ingredients applied to animals; exemptions from the requirement of a tolerance.

Code of Federal Regulations, 2013 CFR

2013-07-01

...-hydroxypolyoxyethylene polymer with or without polyoxypropylene, mixture of di- and monohydrogen phosphate esters and the corresponding ammonium, calcium, magnesium, monoethanolamine, potassium, sodium and zinc salts of the phosphate... Reg. No. 7727-43-7) Carrier, density control agent Benzoic acid Preservative for formulations 2-Bromo...

40 CFR 180.930 - Inert ingredients applied to animals; exemptions from the requirement of a tolerance.

Code of Federal Regulations, 2012 CFR

2012-07-01

...-hydroxypolyoxyethylene polymer with or without polyoxypropylene, mixture of di- and monohydrogen phosphate esters and the corresponding ammonium, calcium, magnesium, monoethanolamine, potassium, sodium and zinc salts of the phosphate..., density control agent Benzoic acid Preservative for formulations 2-Bromo-2-nitro-1,3-propanediol (CAS Reg...

Long-Life and High-Power Binder-Free Cathode Based on One-Step Synthesis of Radical Polymers with Multi-Pendant Groups.

PubMed

Chen, Yaoguang; Zhang, Yangfan; Liu, Xiu; Fan, Xuliang; Bai, Bing; Yang, Kang; Liang, Zhongxin; Zhang, Zishou; Mai, Kancheng

2018-05-16

The main bottlenecks for the widespread application of radical polymers in organic radical batteries are poor cycling stability, due to the dissolution of radical polymers into the electrolyte, and the low efficiency of multi-step synthesis strategies. Herein, a kind of electrolyte-resistant radical polymer bearing multi-pendant groups (poly(ethylene-alt-TEMPO maleate) (PETM)) is designed and synthesized through a one-step esterification reaction to graft 4-hydroxy-2,2,6,6-teramethylpiperidinyl-1-oxy into the commercially available poly(ethylene-alt-maleic anhydride). Interestingly, PETM is hardly soluble in the ethylene carbonate/dimethyl carbonate/ethyl methyl carbonate-based electrolyte, showing an extremely low solubility of 0.59 mg mL -1 , but is easily soluble in tetrahydrofuran and N-Methyl pyrrolidone. The derived binder-free PETM cathode exhibits nearly 100% utilization of the grafted nitroxide radicals (88 mA h g -1 ) and excellent rate capability with almost invariant capacitance from 10 C to 40 C. Significantly, the PETM cathodes retain 94% of the initial capacity after 1000 cycles, outperforming most reported radical polymer-based cathodes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of norbornene copolymers with diazo groups and their application as DUV resists

NASA Astrophysics Data System (ADS)

Kim, Jin-Baek; Kim, Kyoung Seon

2003-06-01

We synthesized a new type of norbornene-maleic anhydride copolymer which as diazoketo groups instead of acid labile protecting groups. The matrix polymer does not need a photoacid generator for the lithographic evaluation. And there is no necessity for the post-exposure bake step that is the cause of PED effects. Methyl 5-norbornenyl-3-oxopropionate was prepared by the reaction of acetyl norbornene with dimethyl carbonate in the presence of sodium hydride. And methyl 5-norbornenyl-2-diazo-3-oxopropionate was synthesized from the reaction between methyl 5-norbornenyl-3-oxopropionate and p-carboxybenzenesulfonyl azide. The polymer was prepared by free radical polymerization. Upon exposure to DUV light, diazoketo groups undergo a series of reactions that culminate in the formation of a carboxylic acid. The matrix polymer in the exposed region becomes soluble in the aqueous base developer. The polymer showed bleaching effect after exposure. Thermal stability of the polymer is measured by TGA and DSC. Characterization of the polymer is achieved using other techniques such as FT-IR, NMR, GPC, and UV. The resist patterns of 0.6 μm feature size were resolved using a KrF exposure tool and with a conventional developer, 2.38 wt% TMAH aqueous solution.

Molecularly imprinted polymer cartridges coupled to high performance liquid chromatography (HPLC-UV) for simple and rapid analysis of fenthion in olive oil.

PubMed

Bakas, Idriss; Ben Oujji, Najwa; Istamboulié, Georges; Piletsky, Sergey; Piletska, Elena; Ait-Addi, Elhabib; Ait-Ichou, Ihya; Noguer, Thierry; Rouillon, Régis

2014-07-01

A combination of molecular modelling and a screening of the library of non-imprinted polymers (NIPs) was used to identify acrylamide as a functional monomer with high affinity towards fenthion, organophosphate insecticide, which is frequently used in the treatment of olives. A good correlation was found between the screening tests and modelling of monomer-template interactions performed using a computational approach. Acrylamide-based molecularly imprinted polymer (MIP) and non-imprinted polymer (NIP) were thermally synthesised in dimethyl formamide (porogen) using ethylene glycol dimethacrylate as a cross-linker and 1,1-azo-bis (isobutyronitrile) as an initiator. The chemical and physical properties of the prepared polymers were characterised. The binding of fenthion by the polymers was studied using solvents with different polarities. The developed MIP showed a high selectivity towards fenthion, compared to other organophosphates (dimethoate, methidathion malalthion), and allowed extraction of fenthion from olive oil samples with a recovery rate of about 96%. The extraction of fenthion using MIPs was much more effective than traditional C18 reverse-phase solid phase extraction and allowed to achieve a low detection limit (LOD) (5 µg L(-1)). Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis of poly(N-isopropylacrylamide)-co-poly(phenylboronate ester) acrylate and study on their glucose-responsive behavior.

PubMed

Yao, Yuan; Shen, Heyun; Zhang, Guanghui; Yang, Jing; Jin, Xu

2014-10-01

We introduced thermo-sensitive poly(N-isopropylacrylamide) (PNIPAM) into the polymer structure of poly(ethylene glycol)-block-poly(phenylboronate ester) acrylate (MPEG-block-PPBDEMA) by block and random polymerization pathways in order to investigate the effect of polymer architecture on the glucose-responsiveness and enhance their insulin release controllability. By following the structure, the continuous PNIPAM shell of the triblock polymer MPEG-block-PNIPAM-block-PPBDEMA collapsing on the glucose-responsive PPBDEMA core formed the polymeric micelles with a core-shell-corona structure, and MPEG-block-(PNIPAM-rand-PPBDEMA) exhibited core-corona micelles in which the hydrophobic core consisted of PNIPAM and PPBDEMA segments when the environmental temperature was increased above low critical solution temperature (LCST) of PNIPAM. The micellar morphologies can be precisely controlled by temperature change between 15 and 37°C. As a result, the introduction of PNIPAM greatly enhanced the overall stability of insulin encapsulated in the polymeric micelles in the absence of glucose over incubation 80 h at 37°C. Comparing to MPEG-block-PNIPAM-block-PPBDEMA, the nanocarriers from MPEG-block-(PNIPAM-rand-PPBDEMA) showed great insulin release behavior which is zero insulin release without glucose, low release at normal blood glucose concentration (1.0 mg/mL). Therefore, these nanocarriers may be served as promising self-regulated insulin delivery system for diabetes treatment. Copyright © 2014 Elsevier Inc. All rights reserved.

Vegetable Oil Derived Solvent, and Catalyst Free “Click Chemistry” Thermoplastic Polytriazoles

PubMed Central

Floros, Michael C.; Leão, Alcides Lopes; Narine, Suresh S.

2014-01-01

Azide-alkyne Huisgen “click” chemistry provides new synthetic routes for making thermoplastic polytriazole polymers—without solvent or catalyst. This method was used to polymerize three diester dialkyne monomers with a lipid derived 18 carbon diazide to produce a series of polymers (labelled C18C18, C18C9, and C18C4 based on monomer chain lengths) free of residual solvent and catalyst. Three diester dialkyne monomers were synthesized with ester chain lengths of 4, 9, and 18 carbons from renewable sources. Significant differences in thermal and mechanical properties were observed between C18C9 and the two other polymers. C18C9 presented a lower melting temperature, higher elongation at break, and reduced Young's modulus compared to C18C4 and C18C18. This was due to the “odd-even” effect induced by the number of carbon atoms in the monomers which resulted in orientation of the ester linkages of C18C9 in the same direction, thereby reducing hydrogen bonding. The thermoplastic polytriazoles presented are novel polymers derived from vegetable oil with favourable mechanical and thermal properties suitable for a large range of applications where no residual solvent or catalyst can be tolerated. Their added potential biocompatibility and biodegradability make them ideal for applications in the medical and pharmaceutical industries. PMID:25032224

Microencapsulation of superoxide dismutase into biodegradable microparticles by spray-drying.

PubMed

Youan, Bi-Botti Célestin

2004-01-01

The aim of this work was to encapsulate superoxide dismutase (SOD) into biodegradable microparticles by spray-drying technique. The nature of the organic solvent to dissolve the polymer, the method of incorporation of the drug in the organic phase (with or without a surfactant, namely sucrose ester of HLB = 6), the surfactant/polymer ratio, and the nature of the biodegradable polyesters were investigated as formulation variables. The polyesters investigated as matrix were poly(epsilon-caprolactone) (PCL), poly(d, l, lactide-co-glycolide) (PLG-RG756), and poly(d, l-lactide) (PLA-R207) of respective molecular weight 78.2 kDa, 84.8 kDa, and 199.8 kDa. At surfactant/polymer ratio of 1/10, the SOD-retained enzymatic activities were higher (> 95%) for PLG-RG756 and PLA-R207 but relatively lower for the PCL (approximately 85%) probably due to the PCL relatively higher hydrophobicity. The obtained microparticles exhibited average volume mean diameter of 4-10 microm, the smaller for PCL and the larger for PLG-RG756 polymeric matrix. The in vitro release profile showed that SOD was completely (100%) released from PLA-R207 in 48 hr and from PLG-RG756 and PCL within 72 hr. These results showed that spray-drying with incorporation of surfactant such as sucrose ester may efficiently encapsulate SOD into biodegradable microparticles. Such formulations may improve the bioavailability of SOD and similar biopharmaceuticals.

pH-sensitive micelles self-assembled from polymer brush (PAE-g-cholesterol)-b-PEG-b-(PAE-g-cholesterol) for anticancer drug delivery and controlled release

PubMed Central

Huang, Xiangxuan; Liao, Wenbo; Zhang, Gang; Kang, Shimin; Zhang, Can Yang

2017-01-01

A novel amphiphilic pH-sensitive triblock polymer brush (poly(β-amino esters)-g-cholesterol)-b-poly(ethylene glycol)-b-(poly(β-amino esters)-g-cholesterol) ((PAE-g-Chol)-b-PEG-b-(PAE-g-Chol)) was designed and synthesized successfully through a three-step reaction, and their self-assembled polymeric micelles were used as hydrophobic anticancer drug delivery carriers to realize effectively controlled release. The critical micelle concentrations were 6.8 μg/mL, 12.6 μg/mL, 17.4 μg/mL, and 26.6 μg/mL at pH values of 7.4, 6.5, 6.0, and 5.0, respectively. The trend of critical micelle concentrations indicated that the polymer had high stability that could prolong the circulation time in the body. The hydrodynamic diameter and zeta potential of the polymeric micelles were influenced significantly by the pH values. As pH decreased from 7.4 to 5.0, the particle size and zeta potential increased from 205.4 nm to 285.7 nm and from +12.7 mV to +47.0 mV, respectively. The pKb of the polymer was confirmed to be approximately 6.5 by the acid–base titration method. The results showed that the polymer had sharp pH-sensitivity because of the protonation of the amino groups, resulting in transformation of the PAE segment from hydrophobic to hydrophilic. Doxorubicin-loaded polymeric micelles were prepared with a high loading content (20%) and entrapment efficiency (60%) using the dialysis method. The in vitro results demonstrated that drug release rate and cumulative release were obviously dependent on pH values. Furthermore, the drug release mechanism was also controlled by the pH values. The polymer had barely any cytotoxicity, whereas the doxorubicin-loaded system showed high toxicity for HepG2 cells as free drugs. All the results proved that the pH-sensitive triblock polymer brush and its self-assembled micelle might be a potential delivery carrier for anticancer drugs with sustained release. PMID:28356738

pH-sensitive micelles self-assembled from polymer brush (PAE-g-cholesterol)-b-PEG-b-(PAE-g-cholesterol) for anticancer drug delivery and controlled release.

PubMed

Huang, Xiangxuan; Liao, Wenbo; Zhang, Gang; Kang, Shimin; Zhang, Can Yang

2017-01-01

A novel amphiphilic pH-sensitive triblock polymer brush (poly(β-amino esters)- g -cholesterol)- b -poly(ethylene glycol)- b -(poly(β-amino esters)- g -cholesterol) ((PAE- g -Chol)- b -PEG- b -(PAE- g -Chol)) was designed and synthesized successfully through a three-step reaction, and their self-assembled polymeric micelles were used as hydrophobic anticancer drug delivery carriers to realize effectively controlled release. The critical micelle concentrations were 6.8 μg/mL, 12.6 μg/mL, 17.4 μg/mL, and 26.6 μg/mL at pH values of 7.4, 6.5, 6.0, and 5.0, respectively. The trend of critical micelle concentrations indicated that the polymer had high stability that could prolong the circulation time in the body. The hydrodynamic diameter and zeta potential of the polymeric micelles were influenced significantly by the pH values. As pH decreased from 7.4 to 5.0, the particle size and zeta potential increased from 205.4 nm to 285.7 nm and from +12.7 mV to +47.0 mV, respectively. The p K b of the polymer was confirmed to be approximately 6.5 by the acid-base titration method. The results showed that the polymer had sharp pH-sensitivity because of the protonation of the amino groups, resulting in transformation of the PAE segment from hydrophobic to hydrophilic. Doxorubicin-loaded polymeric micelles were prepared with a high loading content (20%) and entrapment efficiency (60%) using the dialysis method. The in vitro results demonstrated that drug release rate and cumulative release were obviously dependent on pH values. Furthermore, the drug release mechanism was also controlled by the pH values. The polymer had barely any cytotoxicity, whereas the doxorubicin-loaded system showed high toxicity for HepG2 cells as free drugs. All the results proved that the pH-sensitive triblock polymer brush and its self-assembled micelle might be a potential delivery carrier for anticancer drugs with sustained release.

Mechanistic Design of Chemically Diverse Polymers with Applications in Oral Drug Delivery.

PubMed

Mosquera-Giraldo, Laura I; Borca, Carlos H; Meng, Xiangtao; Edgar, Kevin J; Slipchenko, Lyudmila V; Taylor, Lynne S

2016-11-14

Polymers play a key role in stabilizing amorphous drug formulations, a recent strategy employed to improve solubility and bioavailability of drugs delivered orally. However, the molecular mechanism of stabilization is unclear, therefore, the rational design of new crystallization-inhibiting excipients remains a substantial challenge. This article presents a combined experimental and computational approach to elucidate the molecular features that improve the effectiveness of cellulose polymers as solution crystallization inhibitors, a crucial first step toward their rational design. Polymers with chemically diverse substituents including carboxylic acids, esters, ethers, alcohols, amides, amines, and sulfides were synthesized. Measurements of nucleation induction times of the model drug, telaprevir, show that the only effective polymers contained carboxylate groups in combination with an optimal hydrocarbon chain length. Computational results indicate that polymer conformation as well as solvation free energy are important determinants of effectiveness at inhibiting crystallization and show that simulations are a promising predictive tool in the screening of polymers. This study suggests that polymers need to have an adequate hydrophilicity to promote solvation in an aqueous environment, and sufficient hydrophobic regions to drive interactions with the drug. Particularly, the right balance between key substituent groups and lengths of hydrocarbon side chains is needed to create effective materials.

Tailor-Made Electrospun Multilayer Composite Polymer Electrolytes for High-Performance Lithium Polymer Batteries.

PubMed

Lim, Du-Hyun; Haridas, Anupriya K; Figerez, Stelbin Peter; Raghavan, Prasanth; Matic, Aleksandar; Ahn, Jou-Hyeon

2018-09-01

A novel tailor-made multilayer composite polymer electrolyte, consisting of two outer layers of electrospun polyacrylonitrile (PAN) and one inner layer of poly(vinyl acetate) (PVAc)/poly(methyl methacrylate) (PMMA)/poly(ethylene oxide) (PEO) fibrous membrane, was prepared using continuous electrospinning. These membranes, which are made up of fibers with diameters in the nanometer range, were stacked in layers to produce interconnected pores that result in a high porosity. Gel polymer electrolytes (GPEs) were prepared by entrapping a liquid electrolyte (1 M LiPF6 in ethylene carbonate/dimethyl carbonate) in the membranes. The composite membranes exhibited a high electrolyte uptake of 450-510%, coupled with an improved room temperature ionic conductivity of up to 4.72 mS cm-1 and a high electrochemical stability of 4.6 V versus Li/Li+. Electrochemical investigations of a composite membrane of PAN-PVAc-PAN, with a LiFePO4 cathode synthesized in-house, showed a high initial discharge capacity of 145 mAh g-1, which corresponds to 85% utilization of the active material, and displayed stable cycle performance.

Effect of solvents on the enzyme mediated degradation of copolymers

NASA Astrophysics Data System (ADS)

Banerjee, Aditi; Chatterjee, Kaushik; Madras, Giridhar

2015-09-01

The biodegradation of polycaprolactone (PCL), polylactic acid (PLA), polyglycolide (PGA) and their copolymers, poly (lactide-co-glycolide) and poly (D, L-lactide-co-caprolactone) (PLCL) was investigated. The influence of different solvents on the degradation of these polymers at 37 °C in the presence of two different lipases namely Novozym 435 and the free lipase of porcine pancreas was investigated. The rate coefficients for the polymer degradation and enzyme deactivation were determined using continuous distribution kinetics. Among the homopolymers, the degradation of PGA was nearly an order of magnitude lower than that for PCL and PLA. The overall rate coefficients of the copolymers were higher than their respective homopolymers. Thus, PLCL degraded faster than either PCL or PLA. The degradation was highly dependent on the viscosity of the solvent used with the highest degradation observed in acetone. The degradation of the polymers in acetone was nearly twice that observed in dimethyl sulfoxide indicating that the degradation decreases with increase in the solvent viscosity. The degradation of the polymers in water-solvent mixtures indicated an optimal water content of 2.5 wt% of water.

Effect of Osmolytes on the Conformational Behavior of a Macromolecule in a Cytoplasm-like Crowded Environment: A Femtosecond Mid-IR Pump-Probe Spectroscopy Study.

PubMed

Kundu, Achintya; Verma, Pramod Kumar; Cho, Minhaeng

2018-02-15

Osmolytes found endogenously in almost all living beings play an important role in regulating cell volume under harsh environment. Here, to address the longstanding questions about the underlying mechanism of osmolyte effects, we use femtosecond mid-IR pump-probe spectroscopy with two different IR probes that are the OD stretching mode of HDO and the azido stretching mode of azido-derivatized poly(ethylene glycol) dimethyl ether (PEGDME). Our experimental results show that protecting osmolytes bind strongly with water molecules and dehydrate polymer surface, which results in promoting intramolecular interactions of the polymer. By contrast, urea behaves like water molecules without significantly disrupting water H-bonding network and favors extended and random-coil segments of the polymer chain by directly participating in solvation of the polymer. Our findings highlight the importance of direct interaction between urea and macromolecule, while protecting osmolytes indirectly affect the macromolecule through enhancing the water-osmolyte interaction in a crowded environment, which is the case that is often encountered in real biological systems.

Homogeneous graft copolymerization of styrene onto cellulose in a sulfur dioxide-diethylamine-dimethyl sulfoxide cellulose solvent

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsuzuki, M.; Hagiwara, I.; Shiraishi, N.

1980-12-01

Graft copolymerization of styrene onto cellulose was studied in a homogeneous system (SO/sub 2/(liquid)- diethylamine (DEA)-dimethyl sulfoxide (DMSO) medium)) by ..gamma..-ray mutual irradiation technique. At the same time, homopolymerization of styrene was also examined separately in DMSO, SO/sub 2/-DMSO, DEA-DMSO, and SO/sub 2/-DEA-DMSO media by the same technique. Polymerization of styrene hardly occurs on concentrations above 10 mole SO/sub 2/-DEA complex per mole glucose unit. Maximum percent grafting was obtained in concentrations of 4 mole, after which it decreased rapidly. Total conversion and percent grafting increased with the irradiation time. The value (=0.55) of the slope of the total conversionmore » rate plotted against the dose was only a little higher than the 1/2 which was expected from normal kinetics. No retardation in homopolymerization of styrene in DMSO, SO/sub 2/-DMSO, and DEA-DMSO was evident, while the retardation of homopolymerization in the SO/sub 2/-DEA-DMSO medium was measurable. Sulfur atoms were detected in the polymers obtained in both of SO/sub 2/-DMSO and SO/sub 2/-DEA-DMSO solutions. All of the molecular weights of polymers obtained in the present experiment were very low (3.9 x 10/sup 3/-1.75 x 10/sup 4/).« less

Preparation and characterization of nanocomposite polymer electrolytes poly(vinylidone fluoride)/nanoclay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rahmawati, Suci A.; Sulistyaningsih,; Putro, Alviansyah Z. A.

2016-02-08

Polymer electrolytes are defined as semi solid electrolytes used as separator in lithium ion battery. Separator used as medium for transfer ions and to prevent electrical short circuits in battery cells. To obtain the optimal battery performance, separator with high porosity and electrolyte uptake is required. This can reduce the resistance in the transfer of ions between cathode and anode. The main objective of this work is to investigate the impact of different solvent (Dimethyl acetamide (DMAc), N-methyl-2-pyrrolidone (NMP) and dimethyl formamide (DMF)), pore forming agent poly(vinylpyrolidone) (PVP) and nanoclay as filler in addition of membrane using phase inversion methodmore » on the morphology, porosity, electrolyte uptake and degree of crystallinity. The membrane was prepared by the phase inversion method by adding PVP and Nanoclay using different solvents. The phase inversion method was prepared by dissolving Nanoclay and PVP in solvent for 1-2 hours, and then add the PVDF with stirring for 4 hours at 60°C. The membranes were characterized by porosity test, electrolyte uptake test, scanning electron microscope (SEM), and X-ray diffraction (XRD). The results showed that DMAc as solvent gives the highest value of porosity and electrolyte uptake. The addition of nanoclay and PVP enlarge the size of the pores and reduce the degree of crystallinity. So, the usage of DMAc as solvent is better than NMP or DMF.« less

Bis(thienothiophenyl) diketopyrrolopyrrole-based conjugated polymers with various branched alkyl side chains and their applications in thin-film transistors and polymer solar cells.

PubMed

Shin, Jicheol; Park, Gi Eun; Lee, Dae Hee; Um, Hyun Ah; Lee, Tae Wan; Cho, Min Ju; Choi, Dong Hoon

2015-02-11

New thienothiophene-flanked diketopyrrolopyrrole and thiophene-containing π-extended conjugated polymers with various branched alkyl side-chains were successfully synthesized. 2-Octyldodecyl, 2-decyltetradecyl, 2-tetradecylhexadecyl, 2-hexadecyloctadecyl, and 2-octadecyldocosyl groups were selected as the side-chain moieties and were anchored to the N-positions of the thienothiophene-flanked diketopyrrolopyrrole unit. All five polymers were found to be soluble owing to the bulkiness of the side chains. The thin-film transistor based on the 2-tetradecylhexadecyl-substituted polymer showed the highest hole mobility of 1.92 cm2 V(-1) s(-1) due to it having the smallest π-π stacking distance between the polymer chains, which was determined by grazing incidence X-ray diffraction. Bulk heterojunction polymer solar cells incorporating [6,6]-phenyl-C71-butyric acid methyl ester as the n-type molecule and the additive 1,8-diiodooctane (1 vol %) were also constructed from the synthesized polymers without thermal annealing; the device containing the 2-octyldodecyl-substituted polymer exhibited the highest power conversion efficiency of 5.8%. Although all the polymers showed similar physical properties, their device performance was clearly influenced by the sizes of the branched alkyl side-chain groups.

Evaluating the potential of poly(beta-amino ester) nanoparticles for reprogramming human fibroblasts to become induced pluripotent stem cells.

PubMed

Bhise, Nupura S; Wahlin, Karl J; Zack, Donald J; Green, Jordan J

2013-01-01

Gene delivery can potentially be used as a therapeutic for treating genetic diseases, including neurodegenerative diseases, as well as an enabling technology for regenerative medicine. A central challenge in many gene delivery applications is having a safe and effective delivery method. We evaluated the use of a biodegradable poly(beta-amino ester) nanoparticle-based nonviral protocol and compared this with an electroporation-based approach to deliver episomal plasmids encoding reprogramming factors for generation of human induced pluripotent stem cells (hiPSCs) from human fibroblasts. A polymer library was screened to identify the polymers most promising for gene delivery to human fibroblasts. Feeder-independent culturing protocols were developed for nanoparticle-based and electroporation-based reprogramming. The cells reprogrammed by both polymeric nanoparticle-based and electroporation-based nonviral methods were characterized by analysis of pluripotency markers and karyotypic stability. The hiPSC-like cells were further differentiated toward the neural lineage to test their potential for neurodegenerative retinal disease modeling. 1-(3-aminopropyl)-4-methylpiperazine end-terminated poly(1,4-butanediol diacry-late-co-4-amino-1-butanol) polymer (B4S4E7) self-assembled with plasmid DNA to form nanoparticles that were more effective than leading commercially available reagents, including Lipofectamine® 2000, FuGENE® HD, and 25 kDa branched polyethylenimine, for nonviral gene transfer. B4S4E7 nanoparticles showed effective gene delivery to IMR-90 human primary fibroblasts and to dermal fibroblasts derived from a patient with retinitis pigmentosa, and enabled coexpression of exogenously delivered genes, as is needed for reprogramming. The karyotypically normal hiPSC-like cells generated by conventional electroporation, but not by poly(beta-amino ester) reprogramming, could be differentiated toward the neuronal lineage, specifically pseudostratified optic cups. This study shows that certain nonviral reprogramming methods may not necessarily be safer than viral approaches and that maximizing exogenous gene expression of reprogramming factors is not sufficient to ensure successful reprogramming.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Penning, T.D.

The enone, 2,2-diemthyl-3a..beta.., 6a..beta..-dihydro-4H-cyclopenta-1,3-dioxol-4-one, has been synthesized in six steps from cyclopentadiene, resolved using sulfoximine chemistry, and converted into (-)-prostaglandin E/sub 2/ methyl ester in three steps. Introduction of the optically pure omega side-chain using a conjugate addition of a stabilized organocopper reagent, followed by direct alkylation of the enolate with the ..cap alpha.. side-chain allylic iodide in the presence of hexamethylphosphoramide, afforded a trans, vicinally disubstituted cyclopentanone. Deprotection of the C-15 alcohol, followed by aluminum amalgam reduction of the C-10/oxygen bond, provided (-)-PGE/sub 2/ methyl ester in 47% overall yield from the enone. In an extension of previously describedmore » work, 2-chloro-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholidine 2-sulfide, prepared from l-ephedrine and thiophosphoryl chloride, was used to determine the enantiomeric excess of chiral alcohols in conjunction with /sup 31/P NMR. Chiral primary and secondary alcohols added quantitatively to the phospholidine to give diastereomers which could be analyzed by /sup 31/P NMR and HPLC. A number of other phosphorus heterocycles were also explored as potential chiral derivatizing reagents.« less

Study on the Mechanism of Interaction between Phthalate Acid Esters and Bovine Hemoglobin.

PubMed

Chi, Zhenxing; Zhao, Jing; You, Hong; Wang, Mingjing

2016-08-03

Phthalate acid esters (PAEs) are widely used in plastic products as a series of chemical softeners. However, PAEs, which now exist in many environmental media such as the atmosphere, water, and soil, have been shown to be environmental endocrine disruptors. Hemoglobin is a functional protein that carries oxygen in the red blood cells of animals. This study aims at revealing the interactions between bovine hemoglobin (BHb) and PAEs using spectroscopic and molecular modeling methods. The results indicate that the selected representative PAEs-dimethyl phthalate (DMP), diethyl phthalate (DEP), and dibutyl phthalate (DBP)-can interact with BHb to form BHb-PAE complexes with one binding site, mainly relying on hydrophobic forces, with the affinity order DMP > DEP > DBP, opposite to the order of side-chain length. The binding of PAEs can cause conformational and micro-environmental changes in BHb, which may affect the physiological functions of Hb. Furthermore, molecular docking was applied to define the specific binding sites, the results of which show that all the three PAEs can bind into the central cavity of BHb. The study contributes to expound the toxic mechanism of PAEs in vivo from the point of hematological toxicology.

Fabrication and characterization of nanoclay modified PMR type polyimide composites reinforced with 3D woven basalt fabric

NASA Astrophysics Data System (ADS)

Xie, Jianfei; Qiu, Yiping

2009-07-01

Nanoclay modified PMR type polyimide composites were prepared from 3D orthogonal woven basalt fiber performs and nanoclay modified polyimide matrix resin, which derived from methylene dianiline (MDA), dimethyl ester of 3,3',4,4'- oxydiphthalic acid (ODPE), monomethyl ester of cis-5-norbornene-endo-2,3-dicarboxylic acid (NE) and nanoclay. The Na+-montmorillonite was organically treated using a 1:1 molar ratio mixture of dodecylamine (C12) and MDA. The rheological properties of neat B-stage PMR polyimide and 2% clay modified B-stage PMR polyimide were investigated. Based on the results obtained from the rheological tests, a two step compression molding process can be established for the composites. In the first step, the 3D fabric preforms were impregnated with polyimide resin in a vacuum oven and heated up for degassing the volatiles and by-products. In the second step, composites were compressed. The internal structure of the composites was observed by a microscope. Incorporation of 2% clay showed an improvement in the Tg and stiffness of the PMR polyimide. The resulting composites exhibited high thermal stability and good mechanical properties.

Role of HCA₂ (GPR109A) in nicotinic acid and fumaric acid ester-induced effects on the skin.

PubMed

Hanson, Julien; Gille, Andreas; Offermanns, Stefan

2012-10-01

Nicotinic acid (NA) and fumaric acid esters (FAE) such as monomethyl fumarate or dimethyl fumarate are drugs that elicit a cutaneous reaction called flushing as a side effect. NA is used to reduce progression of atherosclerosis through its anti-dyslipidemic activity and lipid-independent mechanisms involving immune cells, whereas FAE are used to treat psoriasis via largely unknown mechanisms. Both, NA and FAE, induce flushing by the activation of the G-protein-coupled receptor (GPCR) Hydroxy-carboxylic acid receptor 2 (HCA₂, GPR109A) in cells of the epidermis. While the wanted effects of NA are at least in part also mediated by HCA₂, it is currently not clear whether this receptor is also involved in the anti-psoriatic effects of FAE. The HCA₂-mediated flushing response to these drugs involves the formation of prostaglandins D₂ and E₂ by Langerhans cells and keratinocytes via COX-1 in Langerhans cells and COX-2 in keratinocytes. This review summarizes recent progress in the understanding of the mechanisms underlying HCA₂-mediated flushing, describes strategies to mitigate it and discusses the potential link between flushing, HCA₂ and the anti-psoriatic effects of FAE. Copyright © 2012 Elsevier Inc. All rights reserved.

Full kinetics investigation of the formation reaction of phosphonate esters in the gas-phase: a theoretical study.

PubMed

Kazemian, Mohammad Amin; Habibi-Khorassani, Sayyed Mostafa; Maghsoodlu, Malek Taher; Ebrahimi, Ali

2014-04-01

In the present work, the proposed multiple-mechanisms have been investigated theoretically for the reaction between triphenyl phosphite and dimethyl acetylenedicarboxylate in the presence of N-H acid such as aniline for generation of phosphonate esters using ab initio molecular orbital theory in gas phase. The profile of the potential energy surface was constructed at the HF/6-311G(d,p) level of theory. The kinetics of the gas phase reaction was studied by evaluating the reaction path of various mechanisms. Between 12 speculative proposed mechanisms {step₁, step₂ (with four possibilities), step₃ (with three possibilities), and step₄} only the third speculative mechanism was recognized as a desirable mechanism. Theoretical kinetics data involving k and E(a), activation (ΔG(‡), ΔS(‡) and ΔH(‡)), and thermodynamic parameters (ΔG°, ΔS° and ΔH°) were calculated for each step of the various mechanisms. Step₁ of the desirable mechanism was identified as the rate determining step. Comparison of the theoretical desirable mechanism with the rate law that has been previously obtained by UV spectrophotometry experiments indicated that the results are in good agreement.

High-Efficiency Polymer Solar Cells by Using Co-solvents 1-Chloronaphthalene and 1,8-Octanedithiol as Processing Additives

NASA Astrophysics Data System (ADS)

Gao, Bowen; Meng, Jing

2018-07-01

The copolymer poly-BDT-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (PC20BDTDPP) with the bulkier alkoxy on BDT and alkyl on DPP is widely used in organic photovoltaic cells as a potential donor material. Power conversion efficiency (PCE) of polymer solar cells fabricated withPC20BDTDPP as the electron donor blended with [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the electron acceptor was improved from 4.90% to 9.10% by adding 1-5% of the co-solvents (1-chloronaphthalene and 1,8-octanedithiol) as processing additives. The enhanced PCE was attributed to optimized surface morphology and packed polymer chains leading to better phase separation morphology by the solvent additive. Furthermore, owing to its very narrow band gap, the synthesized polymer demonstrates a great potential for tandem or parallel-like solar cells.

High-Efficiency Polymer Solar Cells by Using Co-solvents 1-Chloronaphthalene and 1,8-Octanedithiol as Processing Additives

NASA Astrophysics Data System (ADS)

Gao, Bowen; Meng, Jing

2018-04-01

The copolymer poly-BDT-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (PC20BDTDPP) with the bulkier alkoxy on BDT and alkyl on DPP is widely used in organic photovoltaic cells as a potential donor material. Power conversion efficiency (PCE) of polymer solar cells fabricated withPC20BDTDPP as the electron donor blended with [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the electron acceptor was improved from 4.90% to 9.10% by adding 1-5% of the co-solvents (1-chloronaphthalene and 1,8-octanedithiol) as processing additives. The enhanced PCE was attributed to optimized surface morphology and packed polymer chains leading to better phase separation morphology by the solvent additive. Furthermore, owing to its very narrow band gap, the synthesized polymer demonstrates a great potential for tandem or parallel-like solar cells.

Antimocrobial Polymer

DOEpatents

McDonald, William F.; Huang, Zhi-Heng; Wright, Stacy C.

2005-09-06

A polymeric composition having antimicrobial properties and a process for rendering the surface of a substrate antimicrobial are disclosed. The composition comprises a crosslinked chemical combination of (i) a polymer having amino group-containing side chains along a backbone forming the polymer, (ii) an antimicrobial agent selected from quaternary ammonium compounds, gentian violet compounds, substituted or unsubstituted phenols, biguanide compounds, iodine compounds, and mixtures thereof, and (iii) a crosslinking agent containing functional groups capable of reacting with the amino groups. In one embodiment, the polymer is a polyamide formed from a maleic anhydride or maleic acid ester monomer and alkylamines thereby producing a polyamide having amino substituted alkyl chains on one side of the polyamide backbone; the crosslinking agent is a phosphine having the general formula (A)3P wherein A is hydroxyalkyl; and the antimicrobial agent is chlorhexidine, dimethylchlorophenol, cetyl pyridinium chloride, gentian violet, triclosan, thymol, iodine, and mixtures thereof.

Antimicrobial Polymer

DOEpatents

McDonald, William F.; Wright, Stacy C.; Taylor, Andrew C.

2004-09-28

A polymeric composition having antimicrobial properties and a process for rendering the surface of a substrate antimicrobial are disclosed. The polymeric composition comprises a crosslinked chemical combination of (i) a polymer having amino group-containing side chains along a backbone forming the polymer, (ii) an antimicrobial agent selected from metals, metal alloys, metal salts, metal complexes and mixtures thereof, and (iii) a crosslinking agent containing functional groups capable of reacting with the amino groups. In one example embodiment, the polymer is a polyamide formed from a maleic anhydride or maleic acid ester monomer and alkylamines thereby producing a polyamide having amino substituted alkyl chains on one side of the polyamide backbone; the crosslinking agent is a phosphine having the general formula (A).sub.3 P wherein A is hydroxyalkyl; and the metallic antimicrobial agent is selected from chelated silver ions, silver metal, chelated copper ions, copper metal, chelated zinc ions, zinc metal and mixtures thereof.

Achieving high efficiency laminated polymer solar cell with interfacial modified metallic electrode and pressure induced crystallization

NASA Astrophysics Data System (ADS)

Yuan, Yongbo; Bi, Yu; Huang, Jinsong

2011-02-01

We report efficient laminated organic photovoltaic device with efficiency approach the optimized device by regular method based on Poly(3-hexylthiophene-2,5-diyl) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). The high efficiency is mainly attributed to the formation of a concrete polymer/metal interface mechanically and electrically by the use of electronic-glue, and using the highly conductive and flexible silver film as anode to reduce photovoltage loss and modifying its work function for efficiency hole extraction by ultraviolet/ozone treatment, and the pressure induced crystallization of PCBM.

Surface and interface analysis of poly-hydroxyethylmethacrylate-coated anodic aluminium oxide membranes

NASA Astrophysics Data System (ADS)

Ali, Nurshahidah; Duan, Xiaofei; Jiang, Zhong-Tao; Goh, Bee Min; Lamb, Robert; Tadich, Anton; Poinern, Gérrard Eddy Jai; Fawcett, Derek; Chapman, Peter; Singh, Pritam

2014-01-01

The surface and interface of poly (2-hydroxyethylmethacrylate) (PHEMA) and anodic aluminium oxide (AAO) membranes were comprehensively investigated using Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. It was found that 1s→π* (Cdbnd O) and 1s→σ* (Csbnd O) transitions were dominant on the surface of both bulk PHEMA polymer and PHEMA-surface coated AAO (AAO-PHEMA) composite. Findings from NEXAFS, Fourier-Transform Infrared (FTIR) and X-ray Photoelectron Spectroscopy (XPS) analyses suggest the possibility of chemical interaction between carbon from the ester group of polymer and AAO membrane.

Molecular design of photovoltaic materials for polymer solar cells: toward suitable electronic energy levels and broad absorption.

PubMed

Li, Yongfang

2012-05-15

Bulk heterojunction (BHJ) polymer solar cells (PSCs) sandwich a blend layer of conjugated polymer donor and fullerene derivative acceptor between a transparent ITO positive electrode and a low work function metal negative electrode. In comparison with traditional inorganic semiconductor solar cells, PSCs offer a simpler device structure, easier fabrication, lower cost, and lighter weight, and these structures can be fabricated into flexible devices. But currently the power conversion efficiency (PCE) of the PSCs is not sufficient for future commercialization. The polymer donors and fullerene derivative acceptors are the key photovoltaic materials that will need to be optimized for high-performance PSCs. In this Account, I discuss the basic requirements and scientific issues in the molecular design of high efficiency photovoltaic molecules. I also summarize recent progress in electronic energy level engineering and absorption spectral broadening of the donor and acceptor photovoltaic materials by my research group and others. For high-efficiency conjugated polymer donors, key requirements are a narrower energy bandgap (E(g)) and broad absorption, relatively lower-lying HOMO (the highest occupied molecular orbital) level, and higher hole mobility. There are three strategies to meet these requirements: D-A copolymerization for narrower E(g) and lower-lying HOMO, substitution with electron-withdrawing groups for lower-lying HOMO, and two-dimensional conjugation for broad absorption and higher hole mobility. Moreover, better main chain planarity and less side chain steric hindrance could strengthen π-π stacking and increase hole mobility. Furthermore, the molecular weight of the polymers also influences their photovoltaic performance. To produce high efficiency photovoltaic polymers, researchers should attempt to increase molecular weight while maintaining solubility. High-efficiency D-A copolymers have been obtained by using benzodithiophene (BDT), dithienosilole (DTS), or indacenodithiophene (IDT) donor unit and benzothiadiazole (BT), thienopyrrole-dione (TPD), or thiazolothiazole (TTz) acceptor units. The BDT unit with two thienyl conjugated side chains is a highly promising unit in constructing high-efficiency copolymer donor materials. The electron-withdrawing groups of ester, ketone, fluorine, or sulfonyl can effectively tune the HOMO energy levels downward. To improve the performance of fullerene derivative acceptors, researchers will need to strengthen absorption in the visible spectrum, upshift the LUMO (the lowest unoccupied molecular orbital) energy level, and increase the electron mobility. [6,6]-Phenyl-C(71)-butyric acid methyl ester (PC(70)BM) is superior to [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM) because C(70) absorbs visible light more efficiently. Indene-C(60) bisadduct (ICBA) and Indene-C(70) bisadduct (IC(70)BA) show 0.17 and 0.19 eV higher LUMO energy levels, respectively, than PCBM, due to the electron-rich character of indene and the effect of bisadduct. ICBA and IC(70)BA are excellent acceptors for the P3HT-based PSCs.

[Chemical Constituents from Ethyl Acetate Extract of Psidium guajava Leaves (II)].

PubMed

Ouyang, Wen; Zhu, Xiao-ai; He, Cui-xia; Chen, Xue-xiang; Ye, Shu-min; Peng, Shan; Cao, Yong

2015-08-01

To study the chemical constituents from ethyl acetate extract of Psidium guajava leaves. The constituents were separated and purified by silica gel and Sephadex LH-20 column chromatography and their structures were identified on the basis of physicochemical properties and spectral data. Eleven compounds were isolated and identified as 6,10,14-trimethyl-2-pentadecanone (1), phytyl-acetate (2), cubenol (3), eucalyptin (4), n-docosanoic acid-p-hydroxy-phenethylol ester (5),8-methyl-5,7- dihydroxy-flavonone (6), 6-methyl-5,7-dihydroxy-flavonone (7), betulinic acid (8), carnosol (9), quercetin (10), and 2,4,6-tirhydroxy- 3,5-dimethyl-diphenylketone-4-O-(6'"-O-galloyl)-β-D-glucoside (11). Compounds 1-9 are isolated from this plant for the first time.

Aldehyde-containing urea-absorbing polysaccharides

NASA Technical Reports Server (NTRS)

Mueller, W. A.; Hsu, G. C.; Marsh, H. E., Jr. (Inventor)

1977-01-01

A novel aldehyde containing polymer (ACP) is prepared by reaction of a polysaccharide with periodate to introduce aldehyde groups onto the C2 - C3 carbon atoms. By introduction of ether and ester groups onto the pendant primary hydroxyl solubility characteristics are modified. The ACP is utilized to absorb nitrogen bases such as urea in vitro or in vivo.

Dimethyl Fumarate Protects Neural Stem/Progenitor Cells and Neurons from Oxidative Damage through Nrf2-ERK1/2 MAPK Pathway.

PubMed

Wang, Qin; Chuikov, Sergei; Taitano, Sophina; Wu, Qi; Rastogi, Arjun; Tuck, Samuel J; Corey, Joseph M; Lundy, Steven K; Mao-Draayer, Yang

2015-06-17

Multiple sclerosis (MS) is the most common multifocal inflammatory demyelinating disease of the central nervous system (CNS). Due to the progressive neurodegenerative nature of MS, developing treatments that exhibit direct neuroprotective effects are needed. Tecfidera™ (BG-12) is an oral formulation of the fumaric acid esters (FAE), containing the active metabolite dimethyl fumarate (DMF). Although BG-12 showed remarkable efficacy in lowering relapse rates in clinical trials, its mechanism of action in MS is not yet well understood. In this study, we reported the potential neuroprotective effects of dimethyl fumarate (DMF) on mouse and rat neural stem/progenitor cells (NPCs) and neurons. We found that DMF increased the frequency of the multipotent neurospheres and the survival of NPCs following oxidative stress with hydrogen peroxide (H2O2) treatment. In addition, utilizing the reactive oxygen species (ROS) assay, we showed that DMF reduced ROS production induced by H2O2. DMF also decreased oxidative stress-induced apoptosis. Using motor neuron survival assay, DMF significantly promoted survival of motor neurons under oxidative stress. We further analyzed the expression of oxidative stress-induced genes in the NPC cultures and showed that DMF increased the expression of transcription factor nuclear factor-erythroid 2-related factor 2 (Nrf2) at both levels of RNA and protein. Furthermore, we demonstrated the involvement of Nrf2-ERK1/2 MAPK pathway in DMF-mediated neuroprotection. Finally, we utilized SuperArray gene screen technology to identify additional anti-oxidative stress genes (Gstp1, Sod2, Nqo1, Srxn1, Fth1). Our data suggests that analysis of anti-oxidative stress mechanisms may yield further insights into new targets for treatment of multiple sclerosis (MS).

Dimethyl Fumarate Protects Neural Stem/Progenitor Cells and Neurons from Oxidative Damage through Nrf2-ERK1/2 MAPK Pathway

PubMed Central

Wang, Qin; Chuikov, Sergei; Taitano, Sophina; Wu, Qi; Rastogi, Arjun; Tuck, Samuel J.; Corey, Joseph M.; Lundy, Steven K.; Mao-Draayer, Yang

2015-01-01

Multiple sclerosis (MS) is the most common multifocal inflammatory demyelinating disease of the central nervous system (CNS). Due to the progressive neurodegenerative nature of MS, developing treatments that exhibit direct neuroprotective effects are needed. Tecfidera™ (BG-12) is an oral formulation of the fumaric acid esters (FAE), containing the active metabolite dimethyl fumarate (DMF). Although BG-12 showed remarkable efficacy in lowering relapse rates in clinical trials, its mechanism of action in MS is not yet well understood. In this study, we reported the potential neuroprotective effects of dimethyl fumarate (DMF) on mouse and rat neural stem/progenitor cells (NPCs) and neurons. We found that DMF increased the frequency of the multipotent neurospheres and the survival of NPCs following oxidative stress with hydrogen peroxide (H2O2) treatment. In addition, utilizing the reactive oxygen species (ROS) assay, we showed that DMF reduced ROS production induced by H2O2. DMF also decreased oxidative stress-induced apoptosis. Using motor neuron survival assay, DMF significantly promoted survival of motor neurons under oxidative stress. We further analyzed the expression of oxidative stress-induced genes in the NPC cultures and showed that DMF increased the expression of transcription factor nuclear factor-erythroid 2-related factor 2 (Nrf2) at both levels of RNA and protein. Furthermore, we demonstrated the involvement of Nrf2-ERK1/2 MAPK pathway in DMF-mediated neuroprotection. Finally, we utilized SuperArray gene screen technology to identify additional anti-oxidative stress genes (Gstp1, Sod2, Nqo1, Srxn1, Fth1). Our data suggests that analysis of anti-oxidative stress mechanisms may yield further insights into new targets for treatment of multiple sclerosis (MS). PMID:26090715

Heterogeneous Photochemistry of Agrochemicals at the Leaf Surface: A Case Study of Plant Activator Acibenzolar-S-methyl.

PubMed

Sleiman, M; de Sainte Claire, P; Richard, C

2017-09-06

The photoreactivity of plant activator benzo(1,2,3)thiadiazole-7-carbothioic acid S-methyl ester (BTH), commonly named acibenzolar-S-methyl, was studied on the surfaces of glass, paraffinic wax films, and apple leaves. Experiments were carried out in a solar simulator using pure and formulated BTH (BION). Surface photoproducts were identified using liquid chromatography coupled with electrospray ionization and high-resolution Orbitrap mass spectrometry, while volatile photoproducts were characterized using an online thermal desorption system coupled to a gas chromatography-mass spectrometry (GC-MS) system. Pure BTH degraded quickly on wax surfaces with a half-life of 5.0 ± 0.5 h, whereas photolysis of formulated BTH was 7 times slower (t 1/2 = 36 ± 14 h). On the other hand, formulated BTH was found to photolyze quickly on detached apple leaves with a half-life of 2.8 h ± 0.4 h. This drastic difference in photoreactivity was attributed to the nature and spreading of the BTH deposit, as influenced by the surfactant and surface characteristics. Abiotic stress of irradiated apple leaf was also shown to produce OH radicals which might contribute to the enhanced photodegradability. Eight surface photoproducts were identified, whereas GC-MS analyses revealed the formation of gaseous dimethyl disulfide and methanethiol. The yield of dimethyl disulfide ranged between 1.5% and 12%, and a significant fraction of dimethyl disulfide produced was found to be absorbed by the leaf. This is the first study to report on the formation of volatile chemicals and OH radicals during agrochemical photolysis on plant surfaces. The developed experimental approach can provide valuable insights into the heterogeneous photoreactivity of sprayed agrochemicals and could help improve dissipation models.

Mechanism of papain-catalyzed synthesis of oligo-tyrosine peptides.

PubMed

Mitsuhashi, Jun; Nakayama, Tsutomu; Narai-Kanayama, Asako

2015-01-01

Di-, tri-, and tetra-tyrosine peptides with angiotensin I-converting enzyme inhibitory activity were synthesized by papain-catalyzed polymerization of L-tyrosine ethyl ester in aqueous media at 30 °C. Varying the reaction pH from 6.0 to 7.5 and the initial concentration of the ester substrate from 25 to 100 mM, the highest yield of oligo-tyrosine peptides (79% on a substrate basis) was produced at pH 6.5 and 75 mM, respectively. In the reaction initiated with 100 mM of the substrate, approx. 50% yield of insoluble, highly polymerized peptides accumulated. At less than 15 mM, the reaction proceeded poorly; however, from 30 mM to 120 mM a dose-dependent increase in the consumption rate of the substrate was observed with a sigmoidal curve. Meanwhile, each of the tri- and tetra-tyrosine peptides, even at approx. 5mM, was consumed effectively by papain but was not elongated to insoluble polymers. For deacylation of the acyl-papain intermediate through which a new peptide bond is made, L-tyrosine ethyl ester, even at 5mM, showed higher nucleophilic activity than di- and tri-tyrosine. These results indicate that the mechanism through which papain polymerizes L-tyrosine ethyl ester is as follows: the first interaction between papain and the ester substrate is a rate-limiting step; oligo-tyrosine peptides produced early in the reaction period are preferentially used as acyl donors, while the initial ester substrate strongly contributes as a nucleophile to the elongation of the peptide product; and the balance between hydrolytic fragmentation and further elongation of oligo-tyrosine peptides is dependent on the surrounding concentration of the ester substrate. Copyright © 2015 Elsevier Inc. All rights reserved.

Lebbeckoside C, a new triterpenoid saponin from the stem barks of Albizia lebbeck inhibits the growth of human glioblastoma cells.

PubMed

Noté, Olivier Placide; Ngo Mbing, Joséphine; Kilhoffer, Marie-Claude; Pegnyemb, Dieudonné Emmanuel; Lobstein, Annelise

2018-02-19

One new acacic acid-type saponin, named lebbeckoside C (1), was isolated from the stem barks of Albizia lebbeck. Its structure was established on the basis of extensive analysis of 1D and 2D NMR ( 1 H, 13 C NMR, DEPT, COSY, TOCSY, ROESY, HSQC and HMBC) experiments, HRESIMS studies, and by chemical evidence as 3-O-[β-d-xylopyranosyl-(l→2)-β-d-fucopyranosyl-(1→6)-[β-d-glucopyranosyl(1→2)]-β-d-glucopyranosyl]-21-O-{(2E,6S)-6-O-{4-O-[(2E,6S)-2,6-dimethyl-6-O-(β-d-quinovopyranosyl)octa-2,7-dienoyl]-4-O-[(2E,6S)-2,6-dimethyl-6-O-(β-d-quinovopyranosyl)octa-2,7-dienoyl]-β-d-quinovopyranosyl}-2,6-dimethylocta-2,7-dienoyl}acacic acid 28 O-[β-d-quinovopyranosyl-(l→3)-[α-l-arabinofuranosyl-(l→4)]-α-l-rhamnopyranosyl-(l→2)-β-d-glucopyranosyl] ester. The isolated saponin (1) displayed significant cytotoxic activity against the human glioblastoma cell line U-87 MG and TG1 stem-like glioma cells isolated from a patient tumor with IC 50 values of 1.69 and 1.44 μM, respectively.

Endothelium-Dependent and -Independent Vasodilator Effects of Dimethyl Sulfoxide in Rat Aorta.

PubMed

Kaneda, Takeharu; Sasaki, Noriyasu; Urakawa, Norimoto; Shimizu, Kazumasa

2016-01-01

This study examined the mechanism of vasorelaxation induced by dimethyl sulfoxide (DMSO) in endothelium-intact and -denuded rat aorta. DMSO (0.1-3%) inhibited phenylephrine (PE, 1 μmol/l)-induced contraction in a dose-dependent manner. However, this relaxation was lower in the absence of the endothelium. Increase in DMSO-induced relaxation in the presence of the endothelium was attenuated by preincubation in L-NG-nitroarginine methyl ester (L-NAME, 100 μmol/l) and by the removal of the endothelium. In the aorta with endothelium, DMSO (3%) and CCh (3 μmol/l) increased cGMP contents, significantly and L-NAME (100 μmol/l) inhibited the DMSO-induced increases of cGMP. In fura 2-loaded endothelium-denuded aorta, cumulative application of DMSO (1-3%) inhibited PE-induced muscle tension; however, this application did not affect the [Ca2+]i level. In PE-precontracted endothelium-denuded aorta, relaxation responses to fasudil were significantly less in the presence of DMSO compared to the control. These results suggest that DMSO causes relaxation by increasing the cGMP content in correlation with the release of NO from endothelial cells and by decreasing the Ca2+ sensitivity of contractile elements partly via inhibiting Rho-kinase in rat aorta. © 2016 S. Karger AG, Basel.

Sol-gel-based SPME fiber as a reliable sampling technique for studying biogenic volatile organic compounds released from Clostridium tetani.

PubMed

Ghader, Masoud; Shokoufi, Nader; Es-Haghi, Ali; Kargosha, Kazem

2017-11-01

A novel and efficient headspace solid-phase microextraction (HS-SPME) method, followed by gas chromatography mass spectrometry (GC-MS), was developed to study volatile organic compounds (VOCs) emerging from microorganisms. Two homemade SPME fibers, a semi-polar poly (dimethylsiloxane) (PDMS) fiber, and a polar polyethylene glycol (PEG) fiber, along with two commercial fibers (PDMS and PDMS/DVB) were used to collect VOCs emerging from Clostridium tetani which was cultured in different media. The adsorbed VOCs were desorbed and identified, in vitro, using GC-MS. The adsorption efficiency was improved by optimizing the time duration of adsorption and desorption. About 50 components were identified by the proposed method. The main detected compounds appeared to be sulfur containing compounds such as butanethioic acid S-methyl ester, dimethyl trisulfide, and dimethyl tetrasulfide. These volatile sulfur containing compounds are derived from amino acids containing the sulfur element, which probably coexist in the mentioned bacterium or are added to the culture media. The developed HS-SPME-GC-MS method allowed the determination of the chemical fingerprint of Clostridium tetani volatile constituents, and thus provides a new, simple, and reliable tool for studying the growth of microorganisms. Graphical abstract Investigation of biogenic VOCs released from Clostridium tetani using SPME-GC-MS.

Synthesis and characteristics of polyarylene ether sulfones

NASA Technical Reports Server (NTRS)

Viswanathan, R.; Johnson, B. C.; Ward, T. C.; Mcgrath, J. E.

1981-01-01

A method utilizing potassium carbonate/dimethyl acetamide, as base and solvent respectively, was used for the synthesis of several homopolymers and copolymers derived from various bisphenols. It is demonstrated that this method deviates from simple second order kinetics; this deviation being due to the heterogeneous nature of the reaction. Also, it is shown that a liquid induced crystallization process can improve the solvent resistance of these polymers. Finally, a Monte Carlo simulation of the triad distribution of monomers in nonequilibrium copolycondensation is discussed.

Predictive Model for the Design of Zwitterionic Polymer Brushes: A Statistical Design of Experiments Approach.

PubMed

Kumar, Ramya; Lahann, Joerg

2016-07-06

The performance of polymer interfaces in biology is governed by a wide spectrum of interfacial properties. With the ultimate goal of identifying design parameters for stem cell culture coatings, we developed a statistical model that describes the dependence of brush properties on surface-initiated polymerization (SIP) parameters. Employing a design of experiments (DOE) approach, we identified operating boundaries within which four gel architecture regimes can be realized, including a new regime of associated brushes in thin films. Our statistical model can accurately predict the brush thickness and the degree of intermolecular association of poly[{2-(methacryloyloxy) ethyl} dimethyl-(3-sulfopropyl) ammonium hydroxide] (PMEDSAH), a previously reported synthetic substrate for feeder-free and xeno-free culture of human embryonic stem cells. DOE-based multifunctional predictions offer a powerful quantitative framework for designing polymer interfaces. For example, model predictions can be used to decrease the critical thickness at which the wettability transition occurs by simply increasing the catalyst quantity from 1 to 3 mol %.

Functional interface of polymer modified graphite anode

NASA Astrophysics Data System (ADS)

Komaba, S.; Ozeki, T.; Okushi, K.

Graphite electrodes were modified by polyacrylic acid (PAA), polymethacrylic acid (PMA), and polyvinyl alcohol (PVA). Their electrochemical properties were examined in 1 mol dm -3 LiClO 4 ethylene carbonate:dimethyl carbonate (EC:DMC) and propylene carbonate (PC) solutions as an anode of lithium ion batteries. Generally, lithium ions hardly intercalate into graphite in the PC electrolyte due to a decomposition of the PC electrolyte at ca. 0.8 V vs. Li/Li +, and it results in the exfoliation of the graphene layers. However, the modified graphite electrodes with PAA, PMA, and PVA demonstrated the stable charge-discharge performance due to the reversible lithium intercalation not only in the EC:DMC but also in the PC electrolytes since the electrolyte decomposition and co-intercalation of solvent were successfully suppressed by the polymer modification. It is thought that these improvements were attributed to the interfacial function of the polymer layer on the graphite which interacted with the solvated lithium ions at the electrode interface.

An ecotoxicological study on tin- and bismuth-catalysed PDMS based coatings containing a surface-active polymer.

PubMed

Pretti, Carlo; Oliva, Matteo; Mennillo, Elvira; Barbaglia, Martina; Funel, Marco; Reddy Yasani, Bhaskar; Martinelli, Elisa; Galli, Giancarlo

2013-12-01

Novel films were prepared by condensation curing reaction of a poly(dimethyl siloxane) (PDMS) matrix with bismuth neodecanoate and dibutyltin diacetate catalysts. An ecotoxicological study was performed on the leachates of the coatings using the bacterium Vibrio fischeri, the unicellular alga Dunaliella tertiolecta, the crustacean Artemia salina and the fish Sparus aurata (larvae) as testing organisms. A copper-based self-polishing commercial paint was also tested as reference. The results showed that the tin-catalysed coatings and the copper paint were highly toxic against at least two of the four test organisms, whereas bismuth-catalysed coatings did not show any toxic effect. Moreover, the same biological assessment was also carried out on PDMS coatings containing a surface-active fluorinated polymer. The toxicity of the entire polymeric system resulted only from the tin catalyst used for the condensation curing reaction, as the bismuth catalysed coatings incorporating the surface-active polymer remained atoxic toward all the tested organisms. © 2013 Elsevier Inc. All rights reserved.

Dedicated Industrial Oilseed Crops as Metabolic Engineering Platforms for Sustainable Industrial Feedstock Production

PubMed Central

Zhu, Li-Hua; Krens, Frans; Smith, Mark A.; Li, Xueyuan; Qi, Weicong; van Loo, Eibertus N.; Iven, Tim; Feussner, Ivo; Nazarenus, Tara J.; Huai, Dongxin; Taylor, David C.; Zhou, Xue-Rong; Green, Allan G.; Shockey, Jay; Klasson, K. Thomas; Mullen, Robert T.; Huang, Bangquan; Dyer, John M.; Cahoon, Edgar B.

2016-01-01

Feedstocks for industrial applications ranging from polymers to lubricants are largely derived from petroleum, a non-renewable resource. Vegetable oils with fatty acid structures and storage forms tailored for specific industrial uses offer renewable and potentially sustainable sources of petrochemical-type functionalities. A wide array of industrial vegetable oils can be generated through biotechnology, but will likely require non-commodity oilseed platforms dedicated to specialty oil production for commercial acceptance. Here we show the feasibility of three Brassicaceae oilseeds crambe, camelina, and carinata, none of which are widely cultivated for food use, as hosts for complex metabolic engineering of wax esters for lubricant applications. Lines producing wax esters >20% of total seed oil were generated for each crop and further improved for high temperature oxidative stability by down-regulation of fatty acid polyunsaturation. Field cultivation of optimized wax ester-producing crambe demonstrated commercial utility of these engineered crops and a path for sustainable production of other industrial oils in dedicated specialty oilseeds. PMID:26916792

Dedicated Industrial Oilseed Crops as Metabolic Engineering Platforms for Sustainable Industrial Feedstock Production.

PubMed

Zhu, Li-Hua; Krens, Frans; Smith, Mark A; Li, Xueyuan; Qi, Weicong; van Loo, Eibertus N; Iven, Tim; Feussner, Ivo; Nazarenus, Tara J; Huai, Dongxin; Taylor, David C; Zhou, Xue-Rong; Green, Allan G; Shockey, Jay; Klasson, K Thomas; Mullen, Robert T; Huang, Bangquan; Dyer, John M; Cahoon, Edgar B

2016-02-26

Feedstocks for industrial applications ranging from polymers to lubricants are largely derived from petroleum, a non-renewable resource. Vegetable oils with fatty acid structures and storage forms tailored for specific industrial uses offer renewable and potentially sustainable sources of petrochemical-type functionalities. A wide array of industrial vegetable oils can be generated through biotechnology, but will likely require non-commodity oilseed platforms dedicated to specialty oil production for commercial acceptance. Here we show the feasibility of three Brassicaceae oilseeds crambe, camelina, and carinata, none of which are widely cultivated for food use, as hosts for complex metabolic engineering of wax esters for lubricant applications. Lines producing wax esters >20% of total seed oil were generated for each crop and further improved for high temperature oxidative stability by down-regulation of fatty acid polyunsaturation. Field cultivation of optimized wax ester-producing crambe demonstrated commercial utility of these engineered crops and a path for sustainable production of other industrial oils in dedicated specialty oilseeds.

Acid-catalyzed conversion of mono- and poly-sugars into platform chemicals: effects of molecular structure of sugar substrate.

PubMed

Hu, Xun; Wu, Liping; Wang, Yi; Song, Yao; Mourant, Daniel; Gunawan, Richard; Gholizadeh, Mortaza; Li, Chun-Zhu

2013-04-01

Hydrolysis/pyrolysis of lignocellulosic biomass always produces a mixture of sugars with distinct structures as intermediates or products. This study tried to elucidate the effects of molecular structure of sugars on their acid-catalyzed conversions in ethanol/water. Location of carbonyl group in sugars (fructose versus glucose) and steric configuration of hydroxyl groups (glucose versus galactose) significantly affected yields of levulinic acid/ester (fructose>glucose>galactose). The dehydration of fructose to 5-(hydroxymethyl)furfural produces much less soluble polymer than that from glucose and galactose, which results in high yields of levulinic acid/ester from fructose. Anhydrate sugar such as levoglucosan tends to undergo the undesirable decomposition to form less levulinic acid/ester. Catalytic behaviors of the poly-sugars (sucrose, maltose, raffinose, β-cyclodextrins) were determined much by their basic units. However, their big molecular sizes create the steric hindrance that significantly affects their followed conversion over solid acid catalyst. Copyright © 2013 Elsevier Ltd. All rights reserved.

Synthesis of Degradable Poly(vinyl alcohol) by Radical Ring-Opening Copolymerization and Ice Recrystallization Inhibition Activity.

PubMed

Hedir, Guillaume; Stubbs, Christopher; Aston, Phillip; Dove, Andrew P; Gibson, Matthew I

2017-12-19

Poly(vinyl alcohol) (PVA) is the most active synthetic mimic of antifreeze proteins and has extremely high ice recrystallization inhibition (IRI) activity. Addition of PVA to cellular cryopreservation solutions increases the number of recovered viable cells due to its potent IRI, but it is intrinsically nondegradable in vivo . Here we report the synthesis, characterization, and IRI activity of PVA containing degradable ester linkages. Vinyl chloroacetate (VClAc) was copolymerized with 2-methylene-1,3-dioxepane (MDO) which undergoes radical ring-opening polymerization to install main-chain ester units. The use of the chloroacetate monomer enabled selective deacetylation with retention of esters within the polymer backbone. Quantitative IRI assays revealed that the MDO content had to be finely tuned to retain IRI activity, with higher loadings (24 mol %) resulting in complete loss of IRI activity. These degradable materials will help translate PVA, which is nontoxic and biocompatible, into a range of biomedical applications.

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.

PubMed

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.

Experimental investigation of engine emissions with marine gas oil-oxygenate blends.

PubMed

Nabi, Md Nurun; Hustad, Johan Einar

2010-07-15

This paper investigates the diesel engine performance and exhaust emissions with marine gas oil-alternative fuel additive. Marine gas oil (MGO) was selected as base fuel for the engine experiments. An oxygenate, diethylene glycol dimethyl ether (DGM), and a biodiesel (BD) jatropha oil methyl ester (JOME) with a volume of 10% were blended with the MGO fuel. JOME was derived from inedible jatropha oil. Lower emissions with diesel-BD blends (soybean methyl ester, rapeseed methyl ester etc.) have been established so far, but the effect of MGO-BD (JOME) blends on engine performance and emissions has been a growing interest as JOME (BD) is derived from inedible oil and MGO is frequently used in maritime transports. No phase separation between MGO-DGM and MGO-JOME blends was found. The neat MGO, MGO-DGM and MGO-JOME blends are termed as MGO, Ox10 and B10 respectively. The experiments were conducted with a six-cylinder, four-stroke, turbocharged, direct-injection Scania DC 1102 (DI) diesel engine. The experimental results showed significant reductions in fine particle number and mass emissions, PM and smoke emissions with Ox10 and B10 fuels compared to the MGO fuel. Other emissions including total unburned hydrocarbon (THC), carbon monoxide (CO) and engine noise were also reduced with the Ox10 and B10 fuels, while maintaining similar brake specific fuel consumption (BSFC) and thermal efficiency with MGO fuel. Oxides of nitrogen (NOx) emissions, on the other hand, were slightly higher with the Ox10 and B10 fuels at high engine load conditions. Copyright 2010 Elsevier B.V. All rights reserved.

Temperature-Triggered Switchable Helix-Helix Inversion of Poly(phenylacetylene) Bearing l-Valine Ethyl Ester Pendants and Its Chiral Recognition Ability.

PubMed

Zhou, Yanli; Zhang, Chunhong; Qiu, Yuan; Liu, Lijia; Yang, Taotao; Dong, Hongxing; Satoh, Toshifumi; Okamoto, Yoshio

2016-11-21

A phenylacetylene containing the l-valine ethyl ester pendant (PAA-Val) was synthesized and polymerized by an organorhodium catalyst (Rh(nbd)BPh₄) to produce the corresponding one-handed helical cis -poly(phenylacetylene) (PPAA-Val). PPAA-Val showed a unique temperature-triggered switchable helix-sense in chloroform, while it was not observed in highly polar solvents, such as N , N '-dimethylformamide (DMF). By heating the solution of PPAA-Val in chloroform, the sign of the CD absorption became reversed, but recovered after cooling the solution to room temperature. Even after six cycles of the heating-cooling treatment, the helix sense of the PPAA-Val's backbone was still switchable without loss of the CD intensity. The PPAA-Val was then coated on silica gel particles to produce novel chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC). These novel PPAA-Val based CSPs showed a high chiral recognition ability for racemic mandelonitrile ( α = 2.18) and racemic trans - N , N '-diphenylcyclohexane-1,2-dicarboxamide ( α = 2.60). Additionally, the one-handed helical cis -polyene backbone of PPAA-Val was irreversibly destroyed to afford PPAA-Val-H by heating in dimethyl sulfoxide (DMSO) accompanied by the complete disappearance of the Cotton effect. Although PPAA-Val-H had the same l-valine ethyl ester pendants as its cis -isomer PPAA-Val, it showed no chiral recognition. It was concluded that the one-handed helical cis -polyene backbone of PPAA-Val plays an important role in the chiral recognition ability.

Machine learning-based screening of complex molecules for polymer solar cells

NASA Astrophysics Data System (ADS)

Jørgensen, Peter Bjørn; Mesta, Murat; Shil, Suranjan; García Lastra, Juan Maria; Jacobsen, Karsten Wedel; Thygesen, Kristian Sommer; Schmidt, Mikkel N.

2018-06-01

Polymer solar cells admit numerous potential advantages including low energy payback time and scalable high-speed manufacturing, but the power conversion efficiency is currently lower than for their inorganic counterparts. In a Phenyl-C_61-Butyric-Acid-Methyl-Ester (PCBM)-based blended polymer solar cell, the optical gap of the polymer and the energetic alignment of the lowest unoccupied molecular orbital (LUMO) of the polymer and the PCBM are crucial for the device efficiency. Searching for new and better materials for polymer solar cells is a computationally costly affair using density functional theory (DFT) calculations. In this work, we propose a screening procedure using a simple string representation for a promising class of donor-acceptor polymers in conjunction with a grammar variational autoencoder. The model is trained on a dataset of 3989 monomers obtained from DFT calculations and is able to predict LUMO and the lowest optical transition energy for unseen molecules with mean absolute errors of 43 and 74 meV, respectively, without knowledge of the atomic positions. We demonstrate the merit of the model for generating new molecules with the desired LUMO and optical gap energies which increases the chance of finding suitable polymers by more than a factor of five in comparison to the randomised search used in gathering the training set.

Synthesis and optical properties of azo -dye-attached novel second-order NLO polymers with high thermal stability

NASA Astrophysics Data System (ADS)

Ushiwata, Takami; Okamoto, Etsuya; Komatsu, Kyoji; Kaino, Toshikuni

2001-06-01

Novel second order nonlinear optical (NLO) polymethacrylate or polyacrylate polymers with high glass transition temperatures containing an azo dye attached as side-chain have been prepared using a new approach from polymethacrylic acid or polyacrylic acid as starting materials. Glass transition temperatures of 150 approximately 170 degree Celsius were obtained for Disperse red 1 dye attached polymethacrylic acid. These are attributed to the hydrogen bonding between the residual carboxyl groups in the starting polymers. Poled films by corona poling exhibited large NLO susceptibilities, (chi) (2)33 up to 53 pm/V at a wavelength of 1.3 micrometer. Due to the high glass transition temperatures of the polymers, long-term stability of the optical nonlinearity at 100 degrees Celsius was observed for 200 hrs or more. However residual carboxyl groups caused absorbance decrease mainly by hydrolysis of the ester bonds of the polymers investigated by UV-Vis absorption measurement. The stability of induced polar order of the NLO polymer was enhanced by using aminoalkyl chromophore and imidizing it thermally to introduce imide structure into the polymer main-chain. This imidized polymer exhibited (chi) (2)33 of 45 pm/V at a wavelength of 1.3 micrometer and maintained about 90% of the initial value after 230 hrs or more at 100 degrees Celsius.

Grafting of carboxyl groups using CO2/C2H4/Ar pulsed plasma: Theoretical modeling and XPS derivatization

NASA Astrophysics Data System (ADS)

Manakhov, Anton; Kiryukhantsev-Korneev, Philip; Michlíček, Miroslav; Permyakova, Elizaveta; Dvořáková, Eva; Polčák, Josef; Popov, Zakhar; Visotin, Maxim; Shtansky, Dmitry V.

2018-03-01

The grafting of carboxyl groups enhances cell adhesion and can be used for immobilization of different biomolecules onto plasma-treated materials. The process, however, was not well optimized due to lack of clear understanding of the mechanisms of carboxylic group incorporation into plasma and their grafting to polymer surface. In this work the deposition of COOH plasma polymers from CO2/C2H4/Ar pulsed discharge has been studied depending on the gas mixture and duty cycle. We have demonstrated that the CO2/C2H4/Ar plasma with adjustable thickness of COOH functionalized layer and high stability of the grafted functions in water is a better solution for the COOH surface functionalization compared to the thoroughly analyzed CO2 plasma. The concentration of different carbon environments and the density of COOH groups have been measured by using chemical derivatization combined with X-ray photoelectron spectroscopy. It has been found that the CO2/C2H4/Ar plasma mainly contains ester groups (COOC), the COOH/COOC ratio being between 0.03 and 0.08. The water stability of the COOH groups was significantly higher compared to ester environment, so immersing in water for 24 h allowed to increase the COOH/COOC ratio by a factor of 3. The mechanisms of the CO2 molecule attachment to hydrocarbon chains on the polymer surface and those located inside the plasma were modeled using ab initio calculations.

Thermometric sensing of nitrofurantoin by noncovalently imprinted polymers containing two complementary functional monomers.

PubMed

Athikomrattanakul, Umporn; Gajovic-Eichelmann, Nenad; Scheller, Frieder W

2011-10-15

Molecularly imprinted polymers (MIPs) for nitrofurantoin (NFT) recognition addressing in parallel of two complementary functional groups were created using a noncovalent imprinting approach. Specific tailor-made functional monomers were synthesized: a diaminopyridine derivative as the receptor for the imide residue and three (thio)urea derivatives for the interaction with the nitro group of NFT. A significantly improved binding of NFT to the new MIPs was revealed from the imprinting factor, efficiency of binding, affinity constants and maximum binding number as compared to previously reported MIPs, which addressed either the imide or the nitro residue. Substances possessing only one functionality (either the imide group or nitro group) showed significantly weaker binding to the new imprinted polymers than NFT. However, the compounds lacking both functionalities binds extremely weak to all imprinted polymers. The new imprinted polymers were applied in a flow-through thermistor in organic solvent for the first time. The MIP-thermistor allows the detection of NFT down to a concentration of 5 μM in acetonitrile + 0.2% dimethyl sulfoxide (DMSO). The imprinting factor of 3.91 at 0.1 mM of NFT as obtained by thermistor measurements is well comparable to the value obtained by batch binding experiments. © 2011 American Chemical Society

Correlation between ion diffusional motion and ionic conductivity for different electrolytes based on ionic liquid.

PubMed

Kaur, Dilraj Preet; Yamada, K; Park, Jin-Soo; Sekhon, S S

2009-04-23

Room temperature ionic liquid 2,3-dimethyl-1-hexylimidazolium bis(trifluoromethane sulfonyl)imide (DMHxImTFSI) has been synthesized and used in the preparation of polymer gel electrolytes containing polymethylmethacrylate and propylene carbonate (PC). The onset of ion diffusional motion has been studied by (1)H and (19)F NMR spectroscopy and the results obtained for ionic liquid, liquid electrolytes, and polymer gel electrolytes have been correlated with the ionic conductivity results for these electrolytes in the 100-400 K temperature range. The temperature at which (1)H and (19)F NMR lines show motional narrowing and hence ion diffusional motion starts has been found to be closely related to the temperature at which a large increase in ionic conductivity has been observed for these electrolytes. Polymer gel electrolytes have high ionic conductivity over a wide range of temperatures. Thermogravimetric analysis/differential scanning calorimetry studies show that the ionic liquid (DMHxImTFSI) used in the present study is thermally stable up to 400 degrees C, whereas the addition of PC lowers the thermal stability of polymer gel electrolytes containing the ionic liquid. Different electrolytes have been observed to show high ionic conductivity in different range of temperatures, which can be helpful in the design of polymer gel electrolytes for specific applications.

A direct and fast method to monitor lipid oxidation progress in model fatty acid methyl esters by high-performance size-exclusion chromatography.

PubMed

Márquez-Ruiz, G; Holgado, F; García-Martínez, M C; Dobarganes, M C

2007-09-21

A new method based on high-performance size-exclusion chromatography (HPSEC) is proposed to quantitate primary and secondary oxidation compounds in model fatty acid methyl esters (FAMEs). The method consists on simply injecting an aliquot sample in HPSEC, without preliminary isolation procedures neither addition of standard internal. Four groups of compounds can be quantified, namely, unoxidised FAME, oxidised FAME monomers including hydroperoxides, FAME dimers and FAME polymers. Results showed high repeatability and sensitivity, and substantial advantages versus determination of residual substrate by gas-liquid chromatography. Applicability of the method is shown through selected data obtained by numerous oxidation experiments on pure FAME, mainly methyl linoleate, at ambient and moderate temperatures.

75 FR 50926 - 2-propenoic acid, 2-methyl-, C12-16-alkyl esters, telomers with 1-dodecanethiol, polyethylene...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-18

... result of pesticide use in residential settings. If EPA is able to determine that a finite tolerance is... of its composition the atomic elements carbon, hydrogen, and oxygen. 3. The polymer does not contain as an integral part of its composition, except as impurities, any element other than those listed in...

77 FR 20314 - 2-Propenoic Acid, 2-Methyl-, 2-Ethylhexyl Ester, Telomer With 1-Dodecanethiol, Ethenylbenzene and...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-04

... result of pesticide use in residential settings. If EPA is able to determine that a finite tolerance is... composition the atomic elements carbon, hydrogen, and oxygen. 3. The polymer does not contain as an integral part of its composition, except as impurities, any element other than those listed in 40 CFR 723.250(d...

40 CFR 721.825 - Certain aromatic ether diamines.

Code of Federal Regulations, 2011 CFR

2011-07-01

... ester, compound with 4,4′-[[1,1′-biphenyl]-2,5-diylbis(oxy)]bis[benzenamine] (1:1), polymer with 4,4...: Manufacture, import, or processing in a quantity of 100,000 pounds per year, or greater, for any use. (3) The..., import, or processing in a quantity of 225,000 pounds per year, or greater, for any use. (b) Specific...

Adjustable release of mitomycin C for inhibition of scar tissue formation after filtration surgery.

PubMed

Merritt, Sonia R; Velasquez, Gia; von Recum, Horst A

2013-11-01

The aim of this study is to demonstrate a drug delivery system with the capacity to adjust the release of mitomycin C (MMC), based on polymer composition, and inhibit fibroblast proliferation to a better effect than is currently used in glaucoma filtration surgery. The polymer used in this work is made from the oligosaccharide cyclodextrin, from which others and we have demonstrated adjustable release of small molecule drugs due to specific molecular interactions or "affinity" between drug and the cyclodextrin polymer. To adjust release rate, cyclodextrin polymers were synthesized in either dimethylformamide (DMF) or dimethyl sulfoxide, (DMSO) at a crosslinking ratio of 1:0.16 or 1:0:32 (molecule of glucose: molecule of crosslinker). The polymers were then loaded with mitomycin C, dried, and release evaluated in a physiological environment. Drug release was determined by visible spectroscopy. Released aliquots of mitomycin C were incubated with 3T3 fibroblast cells to determine cytotoxic or inhibitory effect through a cell proliferation assay. We show that by using affinity between drug and polymer, we can adjust MMC release rates to be slower and more sustained than from conventional, diffusion-only polymers, for both the DMF polymers (p = 0.00526) and the DMSO polymers (p = 0.0113). The incorporated and released MMC maintains inhibition of fibroblast proliferation much longer than is possible with a one-time application. Affinity polymers with 1:0.16 and 1:0.32 crosslink ratio showed significant inhibition of proliferation for up to 100 h (p = 0.018 and p = 0.014 respectively). The use of our controlled drug delivery technology applied after surgery could have a greater therapeutic impact than the current one-time applications of MMC. Copyright © 2013 Elsevier Ltd. All rights reserved.