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Sample records for ethylene oxide matrices

  1. Infrared spectroscopy and photochemistry of iron-ethylene oxide in cryogenic matrices. The FTIR spectrum of vinyl iron hydroxide

    SciTech Connect

    Kafafi, Z.H.; Hauge, R.H.; Billups, W.E.; Margrave, J.L.

    1987-08-05

    The mechanism of the cryogenic reaction between an iron atom and an ethylene oxide molecule has been delineated. Iron spontaneously inserted into the carbon-oxygen bond of the cyclic molecule and formed the first unligated metallaoxetane. Upon visible photolysis of ferraoxetane, a metathesis reaction was observed where cleavage occurred through the iron-carbon and the carbon-oxygen bonds of the metallacycle. UV photolysis of the reaction intermediate, an iron oxide ..pi..-complexed to ethylene, led to the activation of one of the C-H bonds of ethylene and the formation of the final product, vinyl iron hydroxide. Similar reaction pathways were observed for the diiron molecule reaction with ethylene oxide. Evidence for the double insertion of two iron atoms into the C-O bonds of ethylene oxide and the subsequent formation of a five-membered oxametallacycle ring has been seen through the detection of frequencies characteristic of an Fe-O-Fe stretching mode and a carbon-carbon stretching mode in the case of the perdeuterio product.

  2. Chemical Stability and Bioadhesive Properties of an Ester Prodrug of Δ9-Tetrahydrocannabinol in Poly (Ethylene Oxide) Matrices: Effect of Formulation Additives

    PubMed Central

    Thumma, Sridhar; Majumdar, Soumyajit; ElSohly, Mahmoud A.; Gul, Waseem; Repka, Michael A.

    2008-01-01

    The objective of the present research was to stabilize a novel hemiglutarate ester prodrug of Δ9-tetrahydrocannabinol (THC), in polyethylene oxide (PEO) polymeric matrices produced by hot-melt fabrication, for systemic delivery of THC through the oral transmucosal route. For this purpose, the influence of pH modifiers and antioxidants employed as stabilizing agents in these matrices was investigated. Based on the stability studies, two final formulations were made, and the stability of the active was assessed in these systems. In addition, the bioadhesive properties of PEO matrices were studied as a function of bioadhesive polymer type and concentration, contact time, drug loading and wetting time. Of all of the polymers investigated, bioadhesion was highest with Carbopol® 971p. Bioadhesion increased with bioadhesive polymer concentration and wetting time to a certain level beyond which there was no further contribution. Both the contact time and drug loading influenced the bioadhesion. Severe degradation of the prodrug was observed during storage, even at room temperature (75% at the end of 3 months). Incorporation of the stabilizing agents in the PEO matrices reduced the degradation of the prodrug considerably. Citric acid was the most effective of all of the pH modifiers studied. Among the various antioxidants utilized, degradation was observed least in presence of BHT and ascorbic acid. Only 7.6% and 8.2% of prodrug degraded in these matrices, respectively, as compared to the PEO only matrices (59.4%) at the end of 3 months at 25 °C/60% RH. The prodrug was very stable in both of the final formulations at the end of the 3 months at 40 °C/75% RH. PMID:18652884

  3. Influence of Plasticizers on the Stability and Release of a Prodrug of Δ9-Tetrahydrocannabinol Incorporated in Poly (Ethylene Oxide) Matrices

    PubMed Central

    Thumma, Sridhar; ElSohly, Mahmoud A.; Zhang, Shuang-Qing; Gul, Waseem; Repka, Michael A.

    2008-01-01

    The objective of the present research was to stabilize a heat-labile novel prodrug of Δ9-tetrahydrocannabinol (THC), THC-hemiglutarate (THC-HG), in polyethylene oxide (PEO) [PolyOx® WSR N-80 (PEO N-80), MW 200,000 Daltons] polymeric matrix systems produced by hot-melt fabrication for systemic delivery of THC through the oral transmucosal route. For this purpose, the effects of processing conditions (processing temperature and heating duration), plasticizer type and concentration and storage conditions on the stability of the prodrug were investigated. The selected plasticizers studied included vitamin E succinate (VES), acetyltributyl citrate (ATBC), triethyl citrate (TEC), triacetin and polyethylene glycol 8000 (PEG 8000). Furthermore, the influence of plasticizer concentration on drug release was also studied. The stability of THC-HG in PEO matrices was influenced by all of the aforementioned variables. Films processed at 110 °C for 7 min were found to be favorable for hot-melt processing with a post- processing drug content of 95%, while significant degradation of THC-HG (~42%) was observed in those processed at 200 °C for 15 min. The degradation of the prodrug during hot-melt fabrication and also upon storage was considerably reduced in the presence of the plasticizers investigated, VES being the most effective. Modulation of the microenvironmental pH to an acidic range via incorporation of citric acid in PEO-plasticizer matrices significantly improved the stability of the prodrug, with almost 90% of the theoretical drug remaining as opposed to only 15% remaining in PEO-only matrices when stored at 40 °C for up to 3 months. The release of drug from PEO matrices was influenced both by the plasticizer type and concentration. A faster release resulted from water-soluble plasticizers, PEG 8000 and triacetin, and with increasing concentration. However, a slower release was observed with an increase in concentration of water-insoluble plasticizers, VES and ATBC

  4. Portable Ethylene Oxide Sterilization Chamber

    PubMed Central

    Songer, J. R.; Mathis, R. G.

    1969-01-01

    A portable ethylene oxide sterilization chamber was designed, constructed, and tested for use in the sterilization of embolectomy catheters. The unit can accommodate catheters up to 40 inches (101.6 cm) in length and can be operated for less than 4 cents per cycle. A constant concentration of 500 mg of ethylene oxide per liter of space and holding periods of 4 and 6 hr at 43 and 22 C, respectively, were adequate when tested with B. subtilis spores. The estimated cost of construction was $165.00. If temperature control is unnecessary, the cost is approximately $80.00. Images PMID:4977644

  5. Ethylene oxide sterilisation--is it safe?

    PubMed Central

    Gillespie, E H; Jackson, J M; Owen, G R

    1979-01-01

    Tests show that ethylene oxide penetrates and can sterilise long narrow tubes in a hospital ethylene oxide steriliser. Residual ethylene oxide levels in plastic tubing after sterilisation have been estimated. Although initially the levels were very high, storage for four days at room temperature reduced them to a safe level. If adequate controls of the sterilising process and storage are carried out, sterilisation by ethylene oxide is considered to be safe for new plastics and clean equipment. Images Figure PMID:512032

  6. 49 CFR 173.323 - Ethylene oxide.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Ethylene oxide. 173.323 Section 173.323... SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging § 173.323 Ethylene oxide. (a) For packaging ethylene oxide in non-bulk packagings, silver mercury or any of its alloys or copper may not be used in...

  7. Ethylene oxide and acetaldehyde in hot cores

    NASA Astrophysics Data System (ADS)

    Occhiogrosso, A.; Vasyunin, A.; Herbst, E.; Viti, S.; Ward, M. D.; Price, S. D.; Brown, W. A.

    2014-04-01

    Context. Ethylene oxide (c-C2H4O), and its isomer acetaldehyde (CH3CHO), are important complex organic molecules because of their potential role in the formation of amino acids. The discovery of ethylene oxide in hot cores suggests the presence of ring-shaped molecules with more than 3 carbon atoms such as furan (c-C4H4O), to which ribose, the sugar found in DNA, is closely related. Aims: Despite the fact that acetaldehyde is ubiquitous in the interstellar medium, ethylene oxide has not yet been detected in cold sources. We aim to understand the chemistry of the formation and loss of ethylene oxide in hot and cold interstellar objects (i) by including in a revised gas-grain network some recent experimental results on grain surfaces and (ii) by comparison with the chemical behaviour of its isomer, acetaldehyde. Methods: We introduce a complete chemical network for ethylene oxide using a revised gas-grain chemical model. We test the code for the case of a hot core. The model allows us to predict the gaseous and solid ethylene oxide abundances during a cooling-down phase prior to star formation and during the subsequent warm-up phase. We can therefore predict at what temperatures ethylene oxide forms on grain surfaces and at what temperature it starts to desorb into the gas phase. Results: The model reproduces the observed gaseous abundances of ethylene oxide and acetaldehyde towards high-mass star-forming regions. In addition, our results show that ethylene oxide may be present in outer and cooler regions of hot cores where its isomer has already been detected. Our new results are compared with previous results, which focused on the formation of ethylene oxide only. Conclusions: Despite their different chemical structures, the chemistry of ethylene oxide is coupled to that of acetaldehyde, suggesting that acetaldehyde may be used as a tracer for ethylene oxide towards cold cores.

  8. Poly(ethylene oxide) functionalization

    DOEpatents

    Pratt, Russell Clayton

    2014-04-08

    A simple procedure is provided by which the hydroxyl termini of poly(ethylene oxide) can be appended with functional groups to a useful extent by reaction and precipitation. The polymer is dissolved in warmed toluene, treated with an excess of organic base and somewhat less of an excess of a reactive acylating reagent, reacted for several hours, then precipitated in isopropanol so that the product can be isolated as a solid, and salt byproducts are washed away. This procedure enables functionalization of the polymer while not requiring laborious purification steps such as solvent-solvent extraction or dialysis to remove undesirable side products.

  9. 29 CFR 1910.1047 - Ethylene oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 6 2014-07-01 2013-07-01 true Ethylene oxide. 1910.1047 Section 1910.1047 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS (CONTINUED) Toxic and Hazardous Substances § 1910.1047 Ethylene oxide. (a) Scope and...

  10. Health Assessment Document for Ethylene Oxide

    EPA Science Inventory

    The largest single use of ethylene oxide is as an intermediate in the synthesis of ethylene glycol. However, small amounts of this epoxide are used as a sterilant or pesticide in commodities, pharmaceuticals, medical devices, tobacco, and other items, representing a considerable ...

  11. 49 CFR 173.323 - Ethylene oxide.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... and gaskets must be constructed of materials which are compatible with ethylene oxide and do not lower... the lading. (h) Neoprene, natural rubber and asbestos gaskets are prohibited. All packing and...

  12. 49 CFR 173.323 - Ethylene oxide.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... and gaskets must be constructed of materials which are compatible with ethylene oxide and do not lower... the lading. (h) Neoprene, natural rubber and asbestos gaskets are prohibited. All packing and...

  13. 21 CFR 172.770 - Ethylene oxide polymer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene oxide polymer. 172.770 Section 172.770... CONSUMPTION Other Specific Usage Additives § 172.770 Ethylene oxide polymer. The polymer of ethylene oxide may... conditions. (a) It is the polymer of ethylene oxide having a minimum viscosity of 1,500 centipoises in a...

  14. 21 CFR 172.770 - Ethylene oxide polymer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ethylene oxide polymer. 172.770 Section 172.770... CONSUMPTION Other Specific Usage Additives § 172.770 Ethylene oxide polymer. The polymer of ethylene oxide may... conditions. (a) It is the polymer of ethylene oxide having a minimum viscosity of 1,500 centipoises in a...

  15. Biocatalytic conversion of ethylene to ethylene oxide using an engineered toluene monooxygenase

    SciTech Connect

    Carlin, DA; Bertolani, SJ; Siegel, JB

    2015-01-01

    Mutants of toluene o-xylene monooxygenase are demonstrated to oxidize ethylene to ethylene oxide in vivo at yields of >99%. The best mutant increases ethylene oxidation activity by >5500-fold relative to the native enzyme. This is the first report of a recombinant enzyme capable of carrying out this industrially significant chemical conversion.

  16. 29 CFR 1915.1047 - Ethylene oxide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Ethylene oxide. 1915.1047 Section 1915.1047 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR SHIPYARD EMPLOYMENT Toxic and Hazardous...

  17. 21 CFR 880.6860 - Ethylene oxide gas sterilizer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ethylene oxide gas sterilizer. 880.6860 Section 880.6860 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Miscellaneous Devices § 880.6860 Ethylene oxide gas sterilizer. (a) Identification. An ethylene gas...

  18. 21 CFR 880.6860 - Ethylene oxide gas sterilizer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ethylene oxide gas sterilizer. 880.6860 Section 880.6860 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Miscellaneous Devices § 880.6860 Ethylene oxide gas sterilizer. (a) Identification. An ethylene gas...

  19. 21 CFR 880.6860 - Ethylene oxide gas sterilizer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ethylene oxide gas sterilizer. 880.6860 Section 880.6860 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Miscellaneous Devices § 880.6860 Ethylene oxide gas sterilizer. (a) Identification. An ethylene gas...

  20. Gas dynamics of ethylene oxide during sterilization

    NASA Astrophysics Data System (ADS)

    Zhu, Z.; Matthews, I. P.; Wang, C.

    1999-07-01

    This article reports a case study of the dynamics of ethylene oxide gas during sterilization using a microwave spectrometer. A diffusion equation is used to describe the processes of gas penetration, gas sorption, and chemical reactions. The three processes, although mathematically related, may be solved separately under simplified assumptions. This permits the prediction of gas penetration and sorption as well as the effect of chemical reactions upon the gas concentration for loads of differing dimensions and densities.

  1. Microbiological aspects of ethylene oxide sterilization. II. Microbial resistance to ethylene oxide.

    PubMed

    Kereluk, K; Gammon, R A; Lloyd, R S

    1970-01-01

    The death rate kinetics of several sporeforming and nonsporeforming microorganisms, including radiation-resistant cocci, were determined by exposing them to a mixture of ethylene oxide and dichlorodifluoromethane (500 mg of ethylene oxide per liter, 30 to 50% relative humidity, and 54.4 C). Spore survivor curves obtained from tests of inoculated and exposed hygroscopic and nonhygroscopic carriers showed that the spores of Bacillus subtilis var. niger are more resistant to ethylene oxide than are spores of Clostridium sporogenes, B. stearothermophilus, and B. pumilus. The decimal reduction times (expressed as D values at 54.4 C-500 mg of ethylene oxide per liter) obtained under the test conditions for B. subtilis var. niger spores on hygroscopic and nonhygroscopic carriers exceeded the values obtained for the other organisms considered, both sporeformers and nonsporeformers. The decimal reduction times for the vegetative cells of the radiation-resistant organisms (Micrococcus radiodurans and two strains of Streptococcus faecalis) and the ATCC strain of S. faecalis demonstrated comparable resistance to ethylene oxide with the spores of C. sporogenes, B. stearothermophilus, and B. pumilus, but not those of B. subtilis var. niger. PMID:5415211

  2. Effect of poly(ethylene oxide) homopolymer and two different poly(ethylene oxide-b-poly(propylene oxide)-b-poly(ethylene oxide) triblock copolymers on morphological, optical, and mechanical properties of nanostructured unsaturated polyester.

    PubMed

    Builes, Daniel H; Hernández-Ortiz, Juan P; Corcuera, Ma Angeles; Mondragon, Iñaki; Tercjak, Agnieszka

    2014-01-22

    Novel nanostructured unsaturated polyester resin-based thermosets, modified with poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO), and two poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) block copolymers (BCP), were developed and analyzed. The effects of molecular weights, blocks ratio, and curing temperatures on the final morphological, optical, and mechanical properties were reported. The block influence on the BCP miscibility was studied through uncured and cured mixtures of unsaturated polyester (UP) resins with PEO and PPO homopolymers having molecular weights similar to molecular weights of the blocks of BCP. The final morphology of the nanostructured thermosetting systems, containing BCP or homopolymers, was investigated, and multiple mechanisms of nanostructuration were listed and explained. By considering the miscibility of each block before and after curing, it was determined that the formation of the nanostructured matrices followed a self-assembly mechanism or a polymerization-induced phase separation mechanism. The miscibility between PEO or PPO blocks with one of two phases of UP matrix was highlighted due to its importance in the final thermoset properties. Relationships between the final morphology and thermoset optical and mechanical properties were examined. The mechanisms and physics behind the morphologies lead toward the design of highly transparent, nanostructured, and toughened thermosetting UP systems. PMID:24354274

  3. Decontamination of matrices containing actinide oxides

    SciTech Connect

    Villarreal, Robert

    1997-12-01

    There is provided a method for removing actinides and actinide oxides, particularly fired actinides, from soil and other contaminated matrices, comprising: (a) contacting a contaminated material with a solution of at least one inhibited fluoride and an acid to form a mixture; (b) heating the mixture of contaminated material and solution to a temperature in the range from about 30 C to about 90 C while stirring; (c) separating the solution from any undissolved matrix material in the mixture; (d) washing the undissolved matrix material to remove any residual materials; and (e) drying and returning the treated matrix material to the environment.

  4. 21 CFR 880.6100 - Ethylene oxide gas aerator cabinet.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ethylene oxide gas aerator cabinet. 880.6100... Miscellaneous Devices § 880.6100 Ethylene oxide gas aerator cabinet. (a) Identification. An ethyene oxide gas... with a ventilation system designed to circulate and exchange the air in the cabinet to shorten the...

  5. 21 CFR 880.6100 - Ethylene oxide gas aerator cabinet.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ethylene oxide gas aerator cabinet. 880.6100... Miscellaneous Devices § 880.6100 Ethylene oxide gas aerator cabinet. (a) Identification. An ethyene oxide gas... with a ventilation system designed to circulate and exchange the air in the cabinet to shorten the...

  6. 21 CFR 880.6100 - Ethylene oxide gas aerator cabinet.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ethylene oxide gas aerator cabinet. 880.6100... Miscellaneous Devices § 880.6100 Ethylene oxide gas aerator cabinet. (a) Identification. An ethyene oxide gas... with a ventilation system designed to circulate and exchange the air in the cabinet to shorten the...

  7. 21 CFR 880.6100 - Ethylene oxide gas aerator cabinet.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ethylene oxide gas aerator cabinet. 880.6100... Miscellaneous Devices § 880.6100 Ethylene oxide gas aerator cabinet. (a) Identification. An ethyene oxide gas... with a ventilation system designed to circulate and exchange the air in the cabinet to shorten the...

  8. 21 CFR 880.6100 - Ethylene oxide gas aerator cabinet.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ethylene oxide gas aerator cabinet. 880.6100... Miscellaneous Devices § 880.6100 Ethylene oxide gas aerator cabinet. (a) Identification. An ethyene oxide gas... with a ventilation system designed to circulate and exchange the air in the cabinet to shorten the...

  9. Kinetics of ethylene oxide desorption from sterilized materials.

    PubMed

    Mendes, Gisela C; Brandão, Teresa R S; Silva, Cristina L M

    2013-01-01

    Ethylene oxide gas is commonly used to sterilize medical devices, and concerns about using this agent on biological systems are well-established. Medical devices sterilized by ethylene oxide must be properly aerated to remove residual gas and by-products. In this work, kinetics of ethylene oxide desorption from different sterilized materials were studied in a range of aeration temperatures. The experimental data were well-described by a Fickian diffusion mass transfer behavior, and diffusivities were estimated for two textile and two polymeric materials within the temperature range of 1.5 to 59.0 degrees C. The results will allow predictions of ethylene oxide desorption, which is a key step for the design of sterilization/aeration processes, contributing to an efficient removal of residual ethylene oxide content. PMID:23513954

  10. A New Interstellar Cyclic Molecule, Ethylene Oxide

    NASA Astrophysics Data System (ADS)

    Dickens, J. E.; Irvine, W. M.; Ohishi, M.; Ikeda, M.; Ishikawa, S.; Nummelin, A.; Hjalmarson, A.

    1997-12-01

    Ethylene oxide (c-C2H4O) is only the fourth known ring molecule identified in the interstellar medium, detected in the Galactic Center cloud SgrB2(N) by Dickens et al. (1997). It is the higher energy isomer of both the more familiar interstellar species acetaldehyde (CH3CHO) and the as yet undetected molecule vinyl alcohol (CH2CHOH). Dickens et al. (1997) reported a c-C2H4O molecular column density about an order of magnitude less than that reported for CH3CHO in SgrB2(N). This is a factor of 200 larger than the predictions of the new standard gas phase chemistry model of Lee, Bettens, and Herbst (1996), suggesting that the formation of c-C2H4O may be related to molecular formation on interstellar grains. We present observations of the c-C2H4O to CH3CHO abundance ratio in 5 additional molecular clouds. The data were taken in October 1997 with the Swedish-European Submillimeter Telescope in Chile. The confirmation of ethylene oxide in molecular clouds provides an appealing scenario for the first link in the chain of reactions leading to the origin of life, since it has been suggested as a possible pathway to the formation of the related cyclic molecule oxiranecarbonitrile (c-C3H3NO; cf., Dickens et al. 1996), a precursor to the synthesis of sugar phosphates which comprise the backbone of our molecular genetic structure. References: Dickens, J.E., Irvine, W.M., Ohishi, M., Ikeda, M., Ishikawa, S., Nummelin, A., and Hjalmarson, A. 1997, Astrophys. J., 489 (in press). Dickens, J.E. et al. 1996, Orig. Life Evol. Biosphere, 26, 97. Lee, H.-H., Bettens, R.P.A., and Herbst, E. 1996, Astron. Astrophys. Supp., 119, 111.

  11. Two episodes of ethylene oxide poisoning--a case report.

    PubMed

    Lin, T J; Ho, C K; Chen, C Y; Tsai, J L; Tsai, M S

    2001-06-01

    Ethylene oxide is used as a sterilizer, a solvent, a plasticizer and in the manufacture of special solvents, antifreeze, polyester resins and non-ionic surfactants. Its toxicity is caused by an alkylating reaction with most organic substances in the body. Four workers, without any protection, managed the leakage of ethylene oxide from the collecting tank improperly on July 29, 2000. In the same factory, the overflow of ethylene oxide in process resulted in leakage of ethylene oxide again on Aug. 7, 2000. Two workers were poisoned despite wearing full-face respirators with ethylene oxide approved canisters. In these two events, the workers all smelled an ether-like odor. Six workers experienced nausea, vomiting, chest tightness, shortness of breath, dizziness, cough and ocular irritation. One worker had transient loss of consciousness. Oxygen therapy and supportive care were used. Patients were discharged in stable condition. The permissible exposure limit of ethylene oxide in air is 1 ppm as an eight hour TWA. Above 50 ppm, the odor threshold, a positive-pressure supplied air respirator is needed to protect the worker. Full-face respirators with ethylene oxide approved canisters could not protect our cases who smelled the odor and were exposed to an unknown concentration. It is important to wear positive-pressure self-contained breathing apparatuses equipped with full facepieces to clean up the contamination area and rescue the patients. PMID:11593964

  12. New sterilization technologies alternative to ethylene oxide

    NASA Astrophysics Data System (ADS)

    Tabrizian, Maryam; Lerouge, Sophie; Debrie, Anne; Yahia, L'Hocine

    1997-06-01

    Sterilization of biomedical devices may induce bulk and surface modification, responsible for the decrease or loss of their biofunctionality. Pure ethylene oxide (EO) at low temperature and new alternative techniques such as cold gas plasma sterilization have been developed for heat-sensitive polymers. There is a lack of the knowledge concerning their safety in terms of materials damage and consequences on the biofunctionality of sterilized devices. The objective of our work consists in studying bulk and surface changes in biomedical devices induced by these two sterilization techniques. Samples from PVC, Polyurethane, Polyacrylate and Polyethylene-based medical devices are subjected to 1, 5, and 10 sterilization cycles by Steri-Vac-3M (pure EO), Sterrad-100$TM, J&J (gas plasma + H2O2), and studied by X-rays photoelectron spectroscopy. Preliminary results show an increasing in Oxygen/Carbon ratio by a factor of 1.3 to 4.4 between the first and tenth cycle indicating the surface oxidation by gas plasma sterilization processes. Some changes in C-C chemical bounding are associated with EO sterilization.

  13. Health Assessment Document for Ethylene Oxide (External Review Draft)

    EPA Science Inventory

    The largest single use of ethylene oxide is an intermediate in the synthesis of ethylene glycol. However, small amounts of this epoxide are used as a sterilant or pesticide in commodities, pharmaceuticals, medical devices, tobacco, and other items, representing a considerable pot...

  14. 46 CFR 151.50-12 - Ethylene oxide.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-12 Ethylene oxide. (a)(1) Ethylene... liquid or vapor phase, including the vent risers, shall be insulated. Flanges need not be covered, but if... installed to maintain the temperature of the liquid below 90 °F, at least two complete cooling...

  15. 46 CFR 151.50-12 - Ethylene oxide.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-12 Ethylene oxide. (a)(1) Ethylene... liquid or vapor phase, including the vent risers, shall be insulated. Flanges need not be covered, but if... installed to maintain the temperature of the liquid below 90 °F, at least two complete cooling...

  16. 46 CFR 151.50-12 - Ethylene oxide.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-12 Ethylene oxide. (a)(1) Ethylene... liquid or vapor phase, including the vent risers, shall be insulated. Flanges need not be covered, but if... installed to maintain the temperature of the liquid below 90 °F, at least two complete cooling...

  17. Evaluation of the Carcinogenicity of Ethylene Oxide (External Review Draft)

    EPA Science Inventory

    EPA conducted a peer review and public comment of the scientific basis supporting the human health hazard and dose-response assessment of ethylene oxide (cancer) that when finalized will appear on the Integrated Risk Information System (IRIS) database.

  18. Storage stability of Bacillus subtilis ethylene oxide biological indicators.

    PubMed Central

    Reich, R R

    1980-01-01

    Bacillus subtilis biological indicators, stored at ambient and freezer conditions for 24 months, demonstrated no statistical difference in ethylene oxide resistance and spore viability from initial production levels. PMID:6766701

  19. Tracing Poly(ethylene-oxide) Crystallization using Atomic Force Microscopy

    NASA Astrophysics Data System (ADS)

    Capaldi, Xavier; Amanuel, Samuel

    The early stages of nucleation and crystallization of Poly(ethylene-oxide) have been studied using Atomic Force Microscopy equipped with a heating and cooling stage. Effects of molecular weight and sample preparation techniques were studied using amplitude and frequency modulation. Mapping the viscoelastic behavior at different temperatures and has enabled the development of a relatively new technique for following the evolution of crystallization and melting of a semi-crystalline polymer. Tracing Poly(ethylene-oxide) Crystallization using Atomic Force Microscopy.

  20. Ammonia and ethylene oxide permeation through selected protective clothing.

    PubMed

    Berardinelli, S P; Moyer, E S; Hall, R C

    1990-11-01

    An automated permeation test system was developed to collect permeation data. Three test specimens were evaluated simultaneously versus a challenge gas. The study evaluated chemical protective clothing garment materials for use by emergency response personnel confronted by ammonia or ethylene oxide in the gas phase. A total of 13 encapsulating suit materials and 2 glove materials were tested. Surgical latex material is not recommended for use in handling ammonia or ethylene oxide; other materials offer much greater protection. PMID:2085165

  1. Evaluating OSHA's ethylene oxide standard: exposure determinants in Massachusetts hospitals.

    PubMed Central

    LaMontagne, A D; Kelsey, K T

    2001-01-01

    OBJECTIVES: This study sought to identify determinants of workplace exposures to ethylene oxide to assess the effect of the Occupational Safety and Health Administration's (OSHA's) 1984 ethylene oxide standard. METHODS: An in-depth survey of all hospitals in Massachusetts that used ethylene oxide from 1990 through 1992 (96% participation, N = 90) was conducted. Three types of exposure events were modeled with logistic regression: exceeding the 8-hour action level, exceeding the 15-minute excursion limit, and worker exposures during unmeasured accidental releases. Covariates were drawn from data representing an ecologic framework including direct and indirect potential exposure determinants. RESULTS: After adjustment for frequencies of ethylene oxide use and exposure monitoring, a significant inverse relation was observed between exceeding the action level and the use of combined sterilizer-aerators, an engineering control technology developed after the passage of the OSHA standard. Conversely, the use of positive-pressure sterilizers that employ ethylene oxide gas mixtures was strongly related to both exceeding the excursion limit and the occurrence of accidental releases. CONCLUSIONS: These findings provide evidence of a positive effect of OSHA's ethylene oxide standard and specific targets for future prevention and control efforts. PMID:11236406

  2. Ethylene vinyl acetate based radiation grafted hydrophilic matrices: Process parameter standardization, grafting kinetics and characterization

    NASA Astrophysics Data System (ADS)

    Chaudhari, C. V.; Mondal, R. K.; Dubey, K. A.; Grover, V.; Panicker, L.; Bhardwaj, Y. K.; Varshney, L.

    2016-08-01

    A transparent, elastomeric, grafted matrix for several potential applications was synthesized by single-step simultaneous radiation grafting of methacrylic acid onto ethylene vinyl acetate (EVA). CuSO4 was found to be the most suitable homo-polymerization inhibitor among different inhibitors tried. The grafting kinetics was found to be a strong function of dose rate (D) and monomer content (M) and an equation relating grafting rate Rg=Kg [M]1.13D0.23 was deduced. Crystallinity of the grafted matrices as assessed from XRD and DSC measurements indicated decrease in crystalline content with increase in grafting yield, suggesting crystalline domain of EVA get disrupted on grafting. Elastic modulus increased linearly with the increase in grafting yield, though elongation at break decreased precipitously from 900% to 30% at even ~9% grafting. Thermo-gravimetric analysis showed three step weight loss of the grafted EVA matrix. The grafting of MAA resulted in increase in surface energy mainly due to enhanced polar component.

  3. High ethylene to ethane processes for oxidative coupling

    DOEpatents

    Chafin, Richard B.; Warren, Barbara K.

    1991-01-01

    Oxidative coupling of lower alkane to higher hydrocarbon is conducted using catalyst comprising barium and/or strontium component and a metal oxide combustion promoter in the presence of vapor phase halogen component. High ethylene to ethane mole ratios in the product can be obtained over extended operating periods.

  4. High ethylene to ethane processes for oxidative coupling

    DOEpatents

    Chafin, R.B.; Warren, B.K.

    1991-12-17

    Oxidative coupling of lower alkane to higher hydrocarbon is conducted using a catalyst comprising barium and/or strontium component and a metal oxide combustion promoter in the presence of vapor phase halogen component. High ethylene to ethane mole ratios in the product can be obtained over extended operating periods.

  5. The oxidation of copper catalysts during ethylene epoxidation.

    PubMed

    Greiner, M T; Jones, T E; Johnson, B E; Rocha, T C R; Wang, Z J; Armbrüster, M; Willinger, M; Knop-Gericke, A; Schlögl, R

    2015-10-14

    The oxidation of copper catalysts during ethylene epoxidation was characterized using in situ photoemission spectroscopy and electron microscopy. Gas chromatography, proton-transfer reaction mass spectrometry and electron-ionization mass spectrometry were used to characterize the catalytic properties of the oxidized copper. We find that copper corrodes during epoxidation in a 1 : 1 mixture of oxygen and ethylene. The catalyst corrosion passes through several stages, beginning with the formation of an O-terminated surface, followed by the formation of Cu2O scale and eventually a CuO scale. The oxidized catalyst exhibits measurable activity for ethylene epoxidation, but with a low selectivity of <3%. Tests on pure Cu2O and CuO powders confirm that the oxides intrinsically exhibit partial-oxidation activity. Cu2O was found to form acetaldehyde and ethylene epoxide in roughly equal amounts (1.0% and 1.2% respectively), while CuO was found to form much less ethyl aldehyde than ethylene epoxide (0.1% and 1.0%, respectively). Metallic copper catalysts were examined in extreme dilute-O2 epoxidation conditions to try and keep the catalyst from oxidizing during the reaction. It was found that in feed of 1 part O2 to 2500 parts C2H4 (PO2 = 1.2 × 10(-4) mbar) the copper surface becomes O-terminated. The O-terminated surface was found to exhibit partial-oxidation selectivity similar to that of Cu2O. With increasing O2 concentration (>8/2500) Cu2O forms and eventually covers the surface. PMID:26345450

  6. 40 CFR 180.151 - Ethylene oxide; tolerances for residues.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., except basil 7 Licorice, roots 7 Peppermint, tops, dried 7 Sesame, seed 7 Spearmint, tops, dried 7 Vegetable, dried 7 Walnut 50 (2) Tolerances are established for residues of the ethylene oxide reaction... 19, dried, except basil 940 Licorice, roots 940 Peppermint, tops, dried 940 Sesame, seed...

  7. 40 CFR 180.151 - Ethylene oxide; tolerances for residues.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., except basil 7 Licorice, roots 7 Peppermint, tops, dried 7 Sesame, seed 7 Spearmint, tops, dried 7 Vegetable, dried 7 Walnut 50 (2) Tolerances are established for residues of the ethylene oxide reaction... 19, dried, except basil 940 Licorice, roots 940 Peppermint, tops, dried 940 Sesame, seed...

  8. 40 CFR 180.151 - Ethylene oxide; tolerances for residues.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., except basil 7 Licorice, roots 7 Peppermint, tops, dried 7 Sesame, seed 7 Spearmint, tops, dried 7 Vegetable, dried 7 Walnut 50 (2) Tolerances are established for residues of the ethylene oxide reaction... 19, dried, except basil 940 Licorice, roots 940 Peppermint, tops, dried 940 Sesame, seed...

  9. 40 CFR 180.151 - Ethylene oxide; tolerances for residues.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., except basil 7 Licorice, roots 7 Peppermint, tops, dried 7 Sesame, seed 7 Spearmint, tops, dried 7 Vegetable, dried 7 Walnut 50 (2) Tolerances are established for residues of the ethylene oxide reaction... 19, dried, except basil 940 Licorice, roots 940 Peppermint, tops, dried 940 Sesame, seed...

  10. 40 CFR 180.151 - Ethylene oxide; tolerances for residues.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., except basil 7 Licorice, roots 7 Peppermint, tops, dried 7 Sesame, seed 7 Spearmint, tops, dried 7 Vegetable, dried 7 Walnut 50 (2) Tolerances are established for residues of the ethylene oxide reaction... 19, dried, except basil 940 Licorice, roots 940 Peppermint, tops, dried 940 Sesame, seed...

  11. 21 CFR 172.770 - Ethylene oxide polymer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ethylene oxide polymer. 172.770 Section 172.770 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR...

  12. 21 CFR 172.770 - Ethylene oxide polymer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Ethylene oxide polymer. 172.770 Section 172.770 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Other Specific Usage Additives §...

  13. 21 CFR 172.770 - Ethylene oxide polymer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ethylene oxide polymer. 172.770 Section 172.770 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR...

  14. ETHYLENE OXIDE CONTROL TECHNOLOGY DEVELOPMENT FOR HOSPITAL STERILIZERS

    EPA Science Inventory

    The report discusses the development of ethylene oxide (EO) control technology for hospital sterilizers. Hospitals sterilize heat-sensitive items in gas sterilizers that use a mixture of EO (12 wt %) and a chlorofluorocarbon (CFC) (88 wt %). The active sterilizing agent is EO. Th...

  15. Surface activity of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) copolymers

    SciTech Connect

    Alexandridis, P.; Athanassiou, V.; Fukuda, Shinya; Hatton, T.A. )

    1994-08-01

    The surface tension of aqueous solutions of seven poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (PEO-PPO-PEO) Pluronic copolymers, covering a wide range of molecular weights (3400-14600) and PPO/PEO ratios (0.19-1.79), was determined over the 10[sup [minus]5]-10% w/v concentration range, at two temperatures (25 and 35[degree]C). Two breaks (changes in slope) were observed in the surface tension vs log concentration curve for most of the copolymers. The low-concentration break, occurring at bulk copolymer concentrations of approximately 10[sup [minus]3]%, is believed to originate from rearrangement of the copolymer molecules on the surface at complete coverage of the air/water interface. The breaks at the high-concentration part of the surface tension curve occurred at concentrations that correspond to the critical micellization concentration values as determined by a dye solubilization technique. The surface area per copolymer molecule, A, increased as a function of the number of EO segments, N[sub EO], obeying a scaling law (A [approx] N[sub EO][sup 1/2]) similar to that of lower molecular weight C[sub i]E[sub j] nonionic surfactants. 56 refs., 6 figs., 2 tabs.

  16. Ethylene oxidation chemistry in a well-stirred reactor

    SciTech Connect

    Marinov, N.; Malte, P.

    1994-09-01

    Ethylene is an important intermediate in the combustion of methane, larger aliphatic hydrocarbons, and aromatics. Detailed fuel-lean C{sub 2}H{sub 4}H{sub 2}O/air well-stirred reactor data by Thornton were used to analyze reported combustion chemistry mechanisms and the development of this study`s ethylene oxidation mechanism. The data set had been obtained for the temperature range 1,003 to 1,253 K and ethylene-oxygen equivalence ratio range 0.086 to 0.103, at atmospheric pressure. Mechanisms were derived from reaction sets of Westbrook and Pitz, and Dagaut, Cathonnet and Boettner. Examination of each reported mechanism indicated unusually large kinetic rates for the vinyl decomposition reaction were used in order to obtain agreement with the Thornton data set. An ethylene oxidation model was developed in order to address the mechanistic problems of the previous models. This study`s mechanism well simulated the overall rate of ethylene oxidation and concentration profiles of CO, CO{sub 2}, H{sub 2}, CH{sub 2}O, C{sub 2}H{sub 2}, CH{sub 3}OH, CH{sub 4}, and C{sub 2}H{sub 6}. Successful predictions by the model were dependent on a new high temperature vinyl oxidation reaction route, C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}CHO + O with a branching ratio of 1.19--1.21 at 1,053 K to 1.63--2.47 at 1,253 K. The branching ratio values were dependent upon the extent of fall-off for the C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}O + HCO reaction. 132 refs.

  17. Alternative control technology document: Ethylene oxide sterilization/fumigation operations

    SciTech Connect

    Not Available

    1989-03-01

    This report presents technical information that State and local agencies can use to develop strategies for reducing VOC (i.e., EO) emissions for sterilization/fumigation facilities. The information in the document will allow planners to identify available control alternatives and evaluate the VOC reduction and cost of implementing controls. The document provides information on sterilization/fumigation processes, EO (ethylene oxide) emissions, and emission reductions, and cost associated with the application of control units. Section 2.0 presents a summary of the findings of the study. Section 3.0 provides a description of sterilization/fumigation facility operations and emission sources. Section 4.0 provides a description of alternative control techniques for the reduction of ethylene oxide emissions. Section 5.0 presents a cost analysis that includes a methodology for computing annualized equipment and operating costs. A list of contacts at various Federal agencies who are knowledgeable about sterilization/fumigation processes is presented in Appendix A.

  18. Ethylene oxidation in a well-stirred reactor

    SciTech Connect

    Marinov, N.M.; Malte, P.C.

    1994-10-01

    The detailed ethylene oxidation data set of Thornton, obtained for a well-stirred reactor operated fuel-lean at atmospheric pressure and for temperatures of 1003K to 1253K, is used as a basis for the comparison of chemical kinetic mechanisms reported in the literature and for the development of a new ethylene oxidation mechanism. The mechanisms examined are those of Westbrook and Pitz and Dagaut et al. These mechanisms indicated that unusually large rates for the vinyl decomposition reaction are required to obtain agreement with the Thornton data set. A new ethylene oxidation mechanism is developed in order to overcome some of the drawbacks of the previous mechanisms. The new mechanism closely simulates the overall rate of loss of ethylene, and the concentation of CO, CO{sub 2}, H{sub 2}, CH{sub 2}O, C{sub 2}H{sub 2}, CH{sub 3}OH, CH{sub 4}, and C{sub 2}H{sub 6} measured for the stirred reactor. Predictions by this mechanism are dependent on a new high temperature vinyl oxidation route, C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}CHO + O with a k{sub C2H3+O2=CH2CHO+O}/k{sub C2H3+O2=CH2O+HCO} branching ratio of 1.20 at 1053K to 2.05 at 1253K. The branching ratio values were dependent upon the extent of fall-off for the C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}O + HCO reaction.

  19. Intermolecular potential energy surface and thermophysical properties of ethylene oxide

    SciTech Connect

    Crusius, Johann-Philipp Hassel, Egon; Hellmann, Robert; Bich, Eckard

    2014-10-28

    A six-dimensional potential energy hypersurface (PES) for two interacting rigid ethylene oxide (C{sub 2}H{sub 4}O) molecules was determined from high-level quantum-chemical ab initio calculations. The counterpoise-corrected supermolecular approach at the MP2 and CCSD(T) levels of theory was utilized to determine interaction energies for 10178 configurations of two molecules. An analytical site-site potential function with 19 sites per ethylene oxide molecule was fitted to the interaction energies and fine tuned to agree with data for the second acoustic virial coefficient from accurate speed of sound measurements. The PES was validated by computing the second virial coefficient, shear viscosity, and thermal conductivity. The values of these properties are substantiated by the best experimental data as they tend to fall within the uncertainty intervals and also obey the experimental temperature functions, except for viscosity, where experimental data are insufficient. Due to the lack of reliable data, especially for the transport properties, our calculated values are currently the most accurate estimates for these properties of ethylene oxide.

  20. Intermolecular potential energy surface and thermophysical properties of ethylene oxide.

    PubMed

    Crusius, Johann-Philipp; Hellmann, Robert; Hassel, Egon; Bich, Eckard

    2014-10-28

    A six-dimensional potential energy hypersurface (PES) for two interacting rigid ethylene oxide (C2H4O) molecules was determined from high-level quantum-chemical ab initio calculations. The counterpoise-corrected supermolecular approach at the MP2 and CCSD(T) levels of theory was utilized to determine interaction energies for 10178 configurations of two molecules. An analytical site-site potential function with 19 sites per ethylene oxide molecule was fitted to the interaction energies and fine tuned to agree with data for the second acoustic virial coefficient from accurate speed of sound measurements. The PES was validated by computing the second virial coefficient, shear viscosity, and thermal conductivity. The values of these properties are substantiated by the best experimental data as they tend to fall within the uncertainty intervals and also obey the experimental temperature functions, except for viscosity, where experimental data are insufficient. Due to the lack of reliable data, especially for the transport properties, our calculated values are currently the most accurate estimates for these properties of ethylene oxide. PMID:25362314

  1. Microwave cavity spectrometer for process monitoring of ethylene oxide sterilization

    NASA Astrophysics Data System (ADS)

    Zhu, Z.; Gibson, C.; Samuel, A. H.; Matthews, I. P.

    1993-01-01

    This article reports a novel and simple cavity spectrometer for process monitoring of ethylene oxide sterilization, in which the source frequency, cavity resonant frequency, and gas absorption center frequency are asynchronous with respect to each other, thus, enabling sophisticated signal enhancement techniques to be employed without the need to engage the Stark effect. The operation of the device is such that the source frequency sweeps across a given range (F1 to F2) which contains one of the absorption peaks of the analyte gas (gases) of interest while the cavity resonant frequency Fr is oscillated within the profile of the absorption peak. Signal enhancement is achieved by adding a relatively small magnitude/high-frequency ``dither'' signal to the source frequency sweep pattern. The salient information of the gas absorption due to the oscillation of the resonant frequency of the cavity is carried by the ``dither'' signal and amplified and extracted by a series of tuned amplifiers and demodulators. Although the device is still at the initial design stage, a working prototype has been constructed in order to test the feasibility of the novel asynchronous modulation technique. This was achieved by successfully demonstrating that the device operates in an expected manner to within a standard error of 8.3%. It is believed that this error largely results from mechanical components. The significance of this error is greatly reduced when the spectrometer is operated in a large signal scanning mode as is the case when we apply the ``power saturation'' technique to measure the concentration of ethylene oxide in the resonant cavity. This measurement showed that there is a good linear correlation between the output signal and the concentration of ethylene oxide gas (to within a standard error of 4%).

  2. Health-hazard evaluation report HETA 83-335-1618, Kendall Company, Augusta, Georgia. [Ethylene oxide

    SciTech Connect

    Seligman, P.; Gorman, R.

    1985-08-01

    Environmental and breathing-zone samples were analyzed for ethylene oxide at the Kendall Company, Augusta, Georgia in August, 1983 and July and August, 1984. The evaluation was requested confidentially to investigate employee complaints of eye irritation and neurologic symptoms and concern over an excessive number of miscarriages. Physicians at the Medical College of Georgia had reported cases of peripheral neuropathy and cataracts related to ethylene-oxide exposure. Twenty-one employees were interviewed. Company medical records were reviewed. Ethylene-oxide concentrations ranged from nondetectable to 0.83 part per million (ppm). The OSHA standard for ethylene oxide is 1.00 ppm. Grab samples taken during sterilizer down/loading contained 0.3 to 25.0ppm ethylene oxide. Medical records confirmed three cases of neuropathy and four of cataracts. Headache, eye irritation, and fatigue were the most prominent symptoms reported. Many of these symptoms were resolved when ethylene oxide was removed from the alcohol wipes. Five of six miscarriages were not occupationally related. The authors conclude that cases of peripheral neuropathy and cataracts among ethylene-oxide sterilizer operators can be related to past exposures, which were higher. Recommendations include using engineering controls to reduce ethylene-oxide exposure further and complying with OSHA recommendations in monitoring employees exposed to action-level concentrations of 0.5ppm ethylene oxide.

  3. Oxidative degradation and kinetics of chlorinated ethylenes by potassium permanganate

    NASA Astrophysics Data System (ADS)

    Yan, Y. Eugene; Schwartz, Frank W.

    1999-04-01

    The oxidative treatment of chlorinated ethylenes in ground water using permanganate was investigated in a series of batch kinetic tests. Five chlorinated ethylenes including tetrachloroethylene (PCE), trichloroethylene (TCE), and three isomers of dichloroethylenes (DCEs) were examined. The degradation process was rapid with pseudo-first-order rate constants ranging from 4.5×10 -5 to 0.03 s -1 at MnO 4-=1 mM. The rate increased with a decreasing number of chlorine substituents on the ethylene. The higher reactivity of trans-DCE ( kobs=30×10 -3 s -1 at MnO 4-=1 mM) as compared to cis-DCE ( kobs=0.9×10 -3 s -1 at MnO 4-=1 mM) is thought to be caused by a significant steric effect due to the formation of a large cyclic activated complex. TCE oxidation as a second-order reaction was confirmed and the rate constant, k=0.67±0.03 M -1 s -1, is independent of pH over the range of 4-8. The activity of both Cl - and hydrogen ions was monitored over time and suggests essentially complete dechlorination, making the degradation products less harmful than the parent compounds. Competition for MnO 4- from other organic compounds in ground water or highly contaminated ground water was also evaluated in experiments. A simple and quick approach was demonstrated to estimate permanganate consumption by other organic compounds for field applications and to predict the TCE degradation rate in a system involving multiple contaminants. The modeling results suggest that the effect of autocatalysis by MnO 2 on TCE degradation is significant when the system contains high concentration levels of MnO 4- and TOC.

  4. Reduced Water Density in a Poly(ethylene oxide) Brush

    SciTech Connect

    Lee, Hoyoung; Kim, Dae Hwan; Park, Hae-Woong; Mahynski, Nathan A.; Kim, Kyungil; Meron, Mati; Lin, Binhua; Won, You-Yeon

    2012-09-05

    A model poly(ethylene oxide) (PEO) brush system, prepared by spreading a poly(ethylene oxide)-poly(n-butyl acrylate) (PEO-PnBA) amphiphilic diblock copolymer onto an air-water interface, was investigated under various grafting density conditions by using the X-ray reflectivity (XR) technique. The overall electron density profiles of the PEO-PnBA monolayer in the direction normal to the air-water interface were determined from the XR data. From this analysis, it was found that inside of the PEO brush, the water density is significantly lower than that of bulk water, in particular, in the region close to the PnBA-water interface. Separate XR measurements with a PnBA homopolymer monolayer confirm that the reduced water density within the PEO-PnBA monolayer is not due to unfavorable contacts between the PnBA surface and water. The above result, therefore, lends support to the notion that PEO chains provide a hydrophobic environment for the surrounding water molecules when they exist as polymer brush chains.

  5. Solubilisation of drugs in micellar solutions of diblock copolymers of ethylene oxide and styrene oxide.

    PubMed

    Crothers, Michael; Ricardo, Nagíla M P S; Heatley, Frank; Nixon, S Keith; Attwood, David; Booth, Colin

    2008-06-24

    The solubilisation of two poorly soluble drugs, furosemide and nabumetone, in micellar solutions of diblock copolymers of ethylene oxide and styrene oxide has been studied at 25 and 37 degrees C and solubilisation capacities compared with published values for griseofulvin and docetaxel. Solubilisation in the micelle core, corrected for the different proportions of poly(styrene oxide) in the copolymers, was similar for all four drugs. The highest solubilisation capacities were found for a copolymer with worm-like micelles. PMID:18417305

  6. An EPR study of the reaction of {sup 69}Ga atoms with ethylene in hydrocarbon matrices

    SciTech Connect

    Howard, J.A.; Joly, H.A.; Mile, B.

    1992-02-06

    The reaction of {sup 69}Ga atoms with ethylene in adamantane on a rotating cryostat at 77 K has been studied by EPR spectroscopy. The major paramagnetic product is the Ga atom-ethylene {pi} complex {sup 69}Ga[C{sub 2}H{sub 4}] that has the magnetic parameters {vert_bar}a{sub xx}(69){vert_bar} = 242 MHz, {vert_bar}a{sub zz}(69){vert_bar} = 82 MHz, {vert_bar}a{sub yy}(69){vert_bar} = 100 MHz, g{sub xx} = 2.0031, g{sub zz} = 1.9807, and g{sub yy} = 2.0107 and has an unpaired spin population of {approximately}0.56 in the Ga 4p{sub x} orbital. These parameters are almost identical to those of {sup 69}Ga[C{sub 2}H{sub 4}] in argon at 4 K and confirm that this complex has a {sup 2}B{sub 1} electronic ground state in the point group C{sub 2v}. There is also a quartet of almost isotropic transitions in the spectrum with the parameters {vert_bar}a{sub {parallel}}(69){vert_bar} = 1669 MHz, {vert_bar}a{sub {perpendicular}}(69){vert_bar} = 1698 MHz, g{sub {parallel}} = 1.9955, and g{perpendicular} = 1.9839 that have been tentatively assigned to the cyclic {sigma}-bonded complex gallacyclopentane, GaCH{sub 2}CH{sub 2}CH{sub 2}CH{sub 2}. 22 refs., 2 figs., 1 tab.

  7. 21 CFR 872.3410 - Ethylene oxide homopolymer and/or carboxymethylcellulose sodium denture adhesive.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... carboxymethylcellulose sodium denture adhesive. 872.3410 Section 872.3410 Food and Drugs FOOD AND DRUG ADMINISTRATION....3410 Ethylene oxide homopolymer and/or carboxymethylcellulose sodium denture adhesive. (a) Identification. An ethylene oxide homopolymer and/or carboxymethylcellulose sodium denture adhesive is a...

  8. 21 CFR 872.3410 - Ethylene oxide homopolymer and/or carboxymethylcellulose sodium denture adhesive.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... carboxymethylcellulose sodium denture adhesive. 872.3410 Section 872.3410 Food and Drugs FOOD AND DRUG ADMINISTRATION....3410 Ethylene oxide homopolymer and/or carboxymethylcellulose sodium denture adhesive. (a) Identification. An ethylene oxide homopolymer and/or carboxymethylcellulose sodium denture adhesive is a...

  9. 21 CFR 872.3450 - Ethylene oxide homopolymer and/or karaya denture adhesive.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... adhesive. 872.3450 Section 872.3450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... homopolymer and/or karaya denture adhesive. (a) Identification. Ethylene oxide homopolymer and/or karaya denture adhesive is a device composed of ethylene oxide homopolymer and/or karaya intended to be...

  10. 21 CFR 872.3410 - Ethylene oxide homopolymer and/or carboxymethylcellulose sodium denture adhesive.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... carboxymethylcellulose sodium denture adhesive. 872.3410 Section 872.3410 Food and Drugs FOOD AND DRUG ADMINISTRATION....3410 Ethylene oxide homopolymer and/or carboxymethylcellulose sodium denture adhesive. (a) Identification. An ethylene oxide homopolymer and/or carboxymethylcellulose sodium denture adhesive is a...

  11. 21 CFR 872.3450 - Ethylene oxide homopolymer and/or karaya denture adhesive.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... adhesive. 872.3450 Section 872.3450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... homopolymer and/or karaya denture adhesive. (a) Identification. Ethylene oxide homopolymer and/or karaya denture adhesive is a device composed of ethylene oxide homopolymer and/or karaya intended to be...

  12. CHROMATOGRAPHIC METHODS FOR ANALYSIS OF ETHYLENE OXIDE IN EMISSIONS FROM STATIONARY SOURCES

    EPA Science Inventory

    Chromatographic methods of analysis with FID detection were investigated for quantitation of ethylene oxide in emissions from production-plants and commercial sterilizers. olumn with a stationary phase of 3% Carbowax 20M on 80/lOO Chromsorb 101 was used to separate ethylene oxide...

  13. 21 CFR 872.3410 - Ethylene oxide homopolymer and/or carboxymethylcellulose sodium denture adhesive.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... carboxymethylcellulose sodium denture adhesive. 872.3410 Section 872.3410 Food and Drugs FOOD AND DRUG ADMINISTRATION....3410 Ethylene oxide homopolymer and/or carboxymethylcellulose sodium denture adhesive. (a) Identification. An ethylene oxide homopolymer and/or carboxymethylcellulose sodium denture adhesive is a...

  14. 21 CFR 872.3450 - Ethylene oxide homopolymer and/or karaya denture adhesive.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... adhesive. 872.3450 Section 872.3450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... homopolymer and/or karaya denture adhesive. (a) Identification. Ethylene oxide homopolymer and/or karaya denture adhesive is a device composed of ethylene oxide homopolymer and/or karaya intended to be...

  15. 21 CFR 872.3450 - Ethylene oxide homopolymer and/or karaya denture adhesive.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... adhesive. 872.3450 Section 872.3450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... homopolymer and/or karaya denture adhesive. (a) Identification. Ethylene oxide homopolymer and/or karaya denture adhesive is a device composed of ethylene oxide homopolymer and/or karaya intended to be...

  16. 21 CFR 872.3410 - Ethylene oxide homopolymer and/or carboxymethylcellulose sodium denture adhesive.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... carboxymethylcellulose sodium denture adhesive. 872.3410 Section 872.3410 Food and Drugs FOOD AND DRUG ADMINISTRATION....3410 Ethylene oxide homopolymer and/or carboxymethylcellulose sodium denture adhesive. (a) Identification. An ethylene oxide homopolymer and/or carboxymethylcellulose sodium denture adhesive is a...

  17. 40 CFR 721.3680 - Ethylene oxide adduct of fatty acid ester with pentaerythritol.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... ester with pentaerythritol. 721.3680 Section 721.3680 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.3680 Ethylene oxide adduct of fatty acid ester with... identified generically as ethylene oxide adduct of fatty acid ester with pentaerythritol (PMN P-91-442)...

  18. 40 CFR 721.3680 - Ethylene oxide adduct of fatty acid ester with pentaerythritol.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... ester with pentaerythritol. 721.3680 Section 721.3680 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.3680 Ethylene oxide adduct of fatty acid ester with... identified generically as ethylene oxide adduct of fatty acid ester with pentaerythritol (PMN P-91-442)...

  19. Decomposition of ethylene oxide in the RF plasma environment.

    PubMed

    Liao, W T; Lee, W J; Chen, C Y; Shih, M

    2001-02-01

    A radio frequency (RF) plasma system was used to decompose the ethylene oxide (EO) contained gas in the EO/Ar, and EO/O2/Ar system, respectively. The reactants and final products were analyzed by using FTIR (Fourier transform infrared spectroscopy). The effects of plasma operational parameters, including input power wattage (W), total gas flow rate (Q), feeding concentration (C) of EO and operational pressure for EO decomposition were evaluated. Due to the importance of the high-energy electrons in the RF plasma system, the EO decomposition fraction in plasma reaction increased with decreasing operational pressure, while that of thermal reaction, reported by previous investigations, increased with increasing operational pressure. However, owing to the electrophilic characteristic of oxygen atoms in the EO molecule causing the effect of electron attachment, in conditions of higher EO feeding concentration, the pressure dependence became the same for both plasma- and thermal-reaction. The EO oxidation reaction has also been investigated, the result shows that EO almost completely oxidized at 600-692 K gas temperature. The main products for the EO/Ar system are CO, CH4, C2H6, C2H4, and C2H2, and those for the EO/O2/Ar system are CO2 and H2O. PMID:11349375

  20. Polymerization of Ethylene Oxide, Propylene Oxide, and Other Alkylene Oxides: Synthesis, Novel Polymer Architectures, and Bioconjugation.

    PubMed

    Herzberger, Jana; Niederer, Kerstin; Pohlit, Hannah; Seiwert, Jan; Worm, Matthias; Wurm, Frederik R; Frey, Holger

    2016-02-24

    The review summarizes current trends and developments in the polymerization of alkylene oxides in the last two decades since 1995, with a particular focus on the most important epoxide monomers ethylene oxide (EO), propylene oxide (PO), and butylene oxide (BO). Classical synthetic pathways, i.e., anionic polymerization, coordination polymerization, and cationic polymerization of epoxides (oxiranes), are briefly reviewed. The main focus of the review lies on more recent and in some cases metal-free methods for epoxide polymerization, i.e., the activated monomer strategy, the use of organocatalysts, such as N-heterocyclic carbenes (NHCs) and N-heterocyclic olefins (NHOs) as well as phosphazene bases. In addition, the commercially relevant double-metal cyanide (DMC) catalyst systems are discussed. Besides the synthetic progress, new types of multifunctional linear PEG (mf-PEG) and PPO structures accessible by copolymerization of EO or PO with functional epoxide comonomers are presented as well as complex branched, hyperbranched, and dendrimer like polyethers. Amphiphilic block copolymers based on PEO and PPO (Poloxamers and Pluronics) and advances in the area of PEGylation as the most important bioconjugation strategy are also summarized. With the ever growing toolbox for epoxide polymerization, a "polyether universe" may be envisaged that in its structural diversity parallels the immense variety of structural options available for polymers based on vinyl monomers with a purely carbon-based backbone. PMID:26713458

  1. 40 CFR 721.3700 - Fatty acid, ester with styrenated phenol, ethylene oxide adduct.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... phenol, ethylene oxide adduct. 721.3700 Section 721.3700 Protection of Environment ENVIRONMENTAL... Significant New Uses for Specific Chemical Substances § 721.3700 Fatty acid, ester with styrenated phenol... chemical substance identified generically as fatty acid, ester with styrenated phenol, ethylene...

  2. 40 CFR 721.3700 - Fatty acid, ester with styrenated phenol, ethylene oxide adduct.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... phenol, ethylene oxide adduct. 721.3700 Section 721.3700 Protection of Environment ENVIRONMENTAL... Significant New Uses for Specific Chemical Substances § 721.3700 Fatty acid, ester with styrenated phenol... chemical substance identified generically as fatty acid, ester with styrenated phenol, ethylene...

  3. 40 CFR 721.3700 - Fatty acid, ester with styrenated phenol, ethylene oxide adduct.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... phenol, ethylene oxide adduct. 721.3700 Section 721.3700 Protection of Environment ENVIRONMENTAL... Significant New Uses for Specific Chemical Substances § 721.3700 Fatty acid, ester with styrenated phenol... chemical substance identified generically as fatty acid, ester with styrenated phenol, ethylene...

  4. 40 CFR 721.3700 - Fatty acid, ester with styrenated phenol, ethylene oxide adduct.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... phenol, ethylene oxide adduct. 721.3700 Section 721.3700 Protection of Environment ENVIRONMENTAL... Significant New Uses for Specific Chemical Substances § 721.3700 Fatty acid, ester with styrenated phenol... chemical substance identified generically as fatty acid, ester with styrenated phenol, ethylene...

  5. 40 CFR 721.3700 - Fatty acid, ester with styrenated phenol, ethylene oxide adduct.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... phenol, ethylene oxide adduct. 721.3700 Section 721.3700 Protection of Environment ENVIRONMENTAL... Significant New Uses for Specific Chemical Substances § 721.3700 Fatty acid, ester with styrenated phenol... chemical substance identified generically as fatty acid, ester with styrenated phenol, ethylene...

  6. Ethylene signalling is mediating the early cadmium-induced oxidative challenge in Arabidopsis thaliana.

    PubMed

    Schellingen, Kerim; Van Der Straeten, Dominique; Remans, Tony; Vangronsveld, Jaco; Keunen, Els; Cuypers, Ann

    2015-10-01

    Cadmium (Cd) induces the generation of reactive oxygen species (ROS) and stimulates ethylene biosynthesis. The phytohormone ethylene is a regulator of many developmental and physiological plant processes as well as stress responses. Previous research indicated various links between ethylene signalling and oxidative stress. Our results support a correlation between the Cd-induced oxidative challenge and ethylene signalling in Arabidopsis thaliana leaves. The effects of 24 or 72 h exposure to 5 μM Cd on plant growth and several oxidative stress-related parameters were compared between wild-type (WT) and ethylene insensitive mutants (etr1-1, ein2-1, ein3-1). Cadmium-induced responses observed in WT plants were mainly affected in etr1-1 and ein2-1 mutants, of which the growth was less inhibited by Cd exposure as compared to WT and ein3-1 mutants. Both etr1-1 and ein2-1 showed a delayed response in the glutathione (GSH) metabolism, including GSH levels and transcript levels of GSH synthesising and recycling enzymes. Furthermore, the expression of different oxidative stress marker genes was significantly lower in Cd-exposed ein2-1 mutants, evidencing that ethylene signalling is involved in early responses to Cd stress. A model for the cross-talk between ethylene signalling and oxidative stress is proposed. PMID:26398798

  7. Chemical modifications of therapeutic proteins induced by residual ethylene oxide.

    PubMed

    Chen, Louise; Sloey, Christopher; Zhang, Zhongqi; Bondarenko, Pavel V; Kim, Hyojin; Ren, Da; Kanapuram, Sekhar

    2015-02-01

    Ethylene oxide (EtO) is widely used in sterilization of drug product primary containers and medical devices. The impact of residual EtO on protein therapeutics is of significant interest in the biopharmaceutical industry. The potential for EtO to modify individual amino acids in proteins has been previously reported. However, specific identification of EtO adducts in proteins and the effect of residual EtO on the stability of therapeutic proteins has not been reported to date. This paper describes studies of residual EtO with two therapeutic proteins, a PEGylated form of the recombinant human granulocyte colony-stimulating factor (Peg-GCSF) and recombinant human erythropoietin (EPO) formulated with human serum albumin (HSA). Peg-GCSF was filled in an EtO sterilized delivery device and incubated at accelerated stress conditions. Glu-C peptide mapping and LC-MS analyses revealed residual EtO reacted with Peg-GCSF and resulted in EtO modifications at two methionine residues (Met-127 and Met-138). In addition, tryptic peptide mapping and LC-MS analyses revealed residual EtO in plastic vials reacted with HSA in EPO formulation at Met-328 and Cys-34. This paper details the work conducted to understand the effects of residual EtO on the chemical stability of protein therapeutics. PMID:25407640

  8. Gas Permeation through Polystyrene-Poly(ethylene oxide) Block Copolymers

    NASA Astrophysics Data System (ADS)

    Hallinan, Daniel, Jr.; Minelli, Matteo; Giacinti-Baschetti, Marco; Balsara, Nitash

    2013-03-01

    Lithium air batteries are a potential technology for affordable energy storage. They consist of a lithium metal anode and a porous air cathode separated by a solid polymer electrolyte membrane, such as PEO/LiTFSI (PEO = poly(ethylene oxide), LiTFSI = lithium bis-trifluoromethane sulfonimide). For extended operation of such a battery, the polymer electrolyte must conduct lithium ions while blocking electrons and gases present in air. In order to maintain a pressure difference the membrane must be mechanically robust, which can be achieved by incorporating the PEO into a block copolymer with a glassy block such as PS (PS = polystyrene). To protect the lithium electrode, the membrane must have low permeability to gases in air such as CO2, N2, and O2. We have therefore studied the permeation of pure gases through a PS-PEO block copolymer. A high molecular weight, symmetric block copolymer with a lamellar morphology was used to cast free-standing membranes. Gas permeability was measured through these membranes with a standard, pressure-based technique. A model was developed to account for transport through the polymer membrane consisting of semi-crystalline PEO lamellae and amorphous PS lamellae. PEO crystallinity was extracted from the permeation model and compares well with values from differential scanning calorimetry measurements.

  9. SAMPLING/ANALYTICAL METHOD EVALUATION FOR ETHYLENE OXIDE EMISSION AND CONTROL UNIT EFFICIENCY DETERMINATIONS

    EPA Science Inventory

    Radian Corporation, assisting the Environmental Monitoring Systems Laboratory, Environmental Protection Agency, Research Triangle Park, North Carolina, performed a field evaluation of a method for sampling and analyzing ethylene oxide (EO) in the vent stream from a sterilization ...

  10. Preliminary survey report: control technology for ethylene oxide sterilization at Selby General Hospital, Marietta, Ohio

    SciTech Connect

    Kercher, S.L.; Mortimer, V.D.; Todd, W.F.

    1985-08-01

    A survey of control technology for reducing exposure during ethylene oxide sterilization was conducted at Selby General Hospital, Marietta, Ohio on August 30, 1984. The Central Services Department performed ethylene oxide sterilization for obstetrics, neonatal care, respiratory therapy, cytology, isolation cases, and surgery. Engineering controls consisted of isolation of the sterilizer and aerators, local exhaust ventilation, a continuous fresh air purge on the sterilization cycle, in chamber aeration of the sterilizers, and general exhaust ventilation of the Central Services Department and the sterilizer room. The author concludes that the Central Services Department has instituted control technology that minimizes employee exposure to ethylene-oxide. The hospital should be considered a candidate for an in-depth survey in a NIOSH study of control technology for ethylene oxide sterilization in hospitals.

  11. Ethylene oxide emissions from commercial sterilization/fumigation operations: Background information for proposed standards. Final report

    SciTech Connect

    Not Available

    1993-03-01

    Table of Contents: Ethylene Oxide Sterilization/Fumigation Processes and Emissions; Emission Control Techniques; Regulatory Alternatives; Environmental Impacts; Emission Control Costs, and The Economic Impacts of the Candidate Neshap Controls.

  12. Evaluation of the Inhalation Carcinogenicity of Ethylene Oxide (Revised Aug 2014 External Review Draft)

    EPA Science Inventory

    EPA is seeking peer review of the scientific basis supporting the human health hazard and dose-response assessment of ethylene oxide (cancer) that will appear in the Integrated Risk Information System (IRIS) database.

  13. Evaluation of the Inhalation Carcinogenicity of Ethylene Oxide (Revised July 2013 External Review Draft)

    EPA Science Inventory

    EPA is initiating a public comment period prior to peer review of the scientific basis supporting the human health hazard and dose-response assessment of ethylene oxide (cancer) that will appear in the Integrated Risk Information System (IRIS) database.

  14. Fourier Transform Microwave Spectra of CO{2}-ETHYLENE Sulfide, CO{2}-ETHYLENE Oxide and CO{2}-PROPYLENE Oxide Complexes

    NASA Astrophysics Data System (ADS)

    Orita, Yukari; Kawashima, Yoshiyuki; Hirota, Eizi

    2010-06-01

    We have previously examined the difference in roles of O and S in structure and dynamics of the CO-ethylene oxide (EO) and CO-ethylene sulfide (ES) complexes. We have extended the investigation to CO{2}-EO and CO{2}-ES for comparison. We have also observed the CO{2}-propylene oxide (PO) complex, which is an important intermediate in the reaction of PO with CO{2} leading to polycarbonate. Both a-type and b-type transitions were observed for the CO{2}-EO and CO{2}-ES, but no c-type transitions were observed at all. We also detected the {34}S and {13}C isotopic species in natural abundance and the species containing {18}OCO and C{18}O% {2}, which were synthesized by burning paper in an {18}O{2} and{% 16}O{2} mixture. By analyzing the observed spectra we concluded the CO{2} moiety of CO{2}-EO and CO{2}-ES located in a plane % prependicular to the three-membered ring and bisecting the COC or CSC angle of EO or ES, respectively, as in the case of CO-EO and CO-ES complexes. An % ab initio MO calculation at the level of MP2/6-311G(d, p) yielded an optimized structure in good agreement with the experimental result. We have derived from the observed spectra the distance, the stretching force constant, and the binding energy of the bonds between the constituents of the CO{2}-EO and CO{2}-ES complexes and have found that the distances of the two complexes were shorter by 0.2Å than those in CO-EO and CO-ES, respectively, and that the intermolecular bonds were two times stronger in the CO{2} complexes than in the corresponding CO complexes. We have concluded from the observed spectra that the CO{2} moiety in CO{2}-PO is located on the PO three-membered ring plane opposite to the methyl group. The constituents in CO{2}-PO were more weakly bound than those in CO{2}-EO and CO{2}-ES. S. Sato, Y. Kawashima, Y. Tatamitani, and E. Hirota, 63rd International Symposium on Molecular Spectroscopy, WF05 (2008).

  15. Novel adhesive properties of poly(ethylene-oxide) adsorbed nanolayers

    NASA Astrophysics Data System (ADS)

    Zeng, Wenduo

    Solid-polymer interfaces play crucial roles in the multidisciplinary field of nanotechnology and are the confluence of physics, chemistry, biology, and engineering. There is now growing evidence that polymer chains irreversibly adsorb even onto weakly attractive solid surfaces, forming a nanometer-thick adsorbed polymer layer ("adsorbed polymer nanolayers"). It has also been reported that the adsorbed layers greatly impact on local structures and properties of supported polymer thin films. In this thesis, I aim to clarify adhesive and tribological properties of adsorbed poly(ethylene-oxide) (PEO) nanolayers onto silicon (Si) substrates, which remain unsolved so far. The adsorbed nanolayers were prepared by the established protocol: one has to equilibrate the melt or dense solution against a solid surface; the unadsorbed chains can be then removed by a good solvent, while the adsorbed chains are assumed to maintain the same conformation due to the irreversible freezing through many physical solid-segment contacts. I firstly characterized the formation process and the surface/film structures of the adsorbed nanolayers by using X-ray reflectivity, grazing incidence X-ray diffraction, and atomic force microscopy. Secondly, to compare the surface energy of the adsorbed layers with the bulk, static contact angle measurements with two liquids (water and glycerol) were carried out using a optical contact angle meter equipped with a video camera. Thirdly, I designed and constructed a custom-built adhesion-testing device to quantify the adhesive property. The experimental results provide new insight into the microscopic structure - macroscopic property relationship at the solid-polymer interface.

  16. Interaction of poly(ethylene oxide) with fumed silica.

    PubMed

    Voronin, E F; Gun'ko, V M; Guzenko, N V; Pakhlov, E M; Nosach, L V; Leboda, R; Skubiszewska-Zieba, J; Malysheva, M L; Borysenko, M V; Chuiko, A A

    2004-11-15

    Interaction of poly(ethylene oxide) (PEO, 600 kDa) with fumed silica A-300 (SBET = 316 m2/g) was investigated under different conditions using adsorption, infrared (IR), thermal analysis (TG-DTA), AFM, and quantum chemical methods. The studied dried silica/PEO samples were also carbonized in a flow reactor at 773 K. The structural characteristics of fumed silica, PEO/silica, and pyrocarbon/fumed silica were investigated using nitrogen adsorption-desorption at 77.4 K. PEO adsorption isotherm depicts a high affinity of PEO to the fumed silica surface in aqueous medium. PEO adsorbed in the amount of 50 mg per gram of silica (PEO monolayer corresponds to CPEO approximately 190 mg/g) can disturb approximately 70% of isolated surface silanols. However, at the monolayer coverage, only 20% of oxygen atoms of PEO molecules take part in the hydrogen bonding with the surface silanols. An increase in the PEO amount adsorbed on fumed silica leads to a diminution of the specific surface area and contributions of micro- (pore radius R < 1 nm) and mesopores (1 < R < 25 nm) to the pore volume but contribution of macropores (R > 25 nm) increases with CPEO. Quantum chemical calculations of a complex of a PEO fragment with a tripple bond SiOH group of a silica cluster in the gas phase and with consideration for the solvent (water) effect show a reduction of interaction energy in the aqueous medium. However, the complex remains strong enough to provide durability of the PEO adsorption complexes on fumed silica; i.e., PEO/fumed silica nanocomposites could be stable in both gaseous and liquid media. PMID:15464796

  17. Oxidation induced decomposition of ethylene carbonate from DFT calculations--importance of explicitly treating surrounding solvent.

    PubMed

    Xing, Lidan; Borodin, Oleg

    2012-10-01

    The oxidation induced reactions of the common lithium battery electrolyte solvent ethylene carbonate (EC) have been investigated for EC(2) using density functional theory and for selected reaction paths using Møller-Plesset perturbation theory (MP4). The importance of explicitly treating at least one solvent molecule interacting with EC during oxidation (removal of an electron) on the EC oxidation potential and decomposition reactions was shown by comparing oxidation of EC and EC(2). Accuracy of DFT results was evaluated by comparing with MP4 and G4 values for oxidation of EC. The polarized continuum model (PCM) was used to implicitly include the rest of the surrounding solvent. The oxidation potentials of EC(2) and EC(4) were found to be significantly lower than the intrinsic oxidation potential of an isolated EC and also lower than the oxidation potential of EC-BF(4)(-). The exothermic proton abstraction from the ethylene group of EC by the carbonyl group of another EC was responsible for the decreased oxidative stability of EC(2) and EC(4) compared to EC. The most exothermic path with the smallest barrier for EC(2) oxidation yielded CO(2) and an ethanol radical cation. The reaction paths with the higher barrier yielded oligo(ethylene carbonate) suggesting a pathway for the experimentally observed poly(ethylene carbonate) formation of EC-based electrolytes at cathode surfaces. PMID:22885926

  18. Micellization of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymers in aqueous solutions: Thermodynamics of copolymer association

    SciTech Connect

    Alexandridis, P.; Hatton, T.A. . Dept. of Chemical Engineering); Holzwarth, J.F. )

    1994-04-25

    The critical micellization temperature (cmt) and critical micellization concentration (cmc) values of 12 Pluronic poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers, covering a wide range of molecular weights (2,900--14,600) and PPO/PEO ratios (0.19--1.79), were determined employing a dye solubilization method. A closed association model was found to describe adequately the copolymer micellization process for the majority of the Pluronics and used to obtain the standard free energies ([Delta]G[degree]), enthalpies ([Delta]H[degree]), and entropies ([Delta]S[degree]) of micellization. It was determined that the micellization process is entropy-driven and has an endothermic micellization enthalpy. The hydrophobic part of the Pluronics, PPO, was responsible for the micellization, apparently due to diminishing hydrogen bonding between water and PPO with increasing temperature. The cmc dependence on temperature and size of headgroup (PEO) of Pluronics follows a similar trend with lower molecular weight C[sub i]E[sub j] nonionic surfactants, the effect of temperature being more pronounced with the Pluronics. The PEO-PPO-PEO block copolymers were compared to PPO-PEO-PPO block and PEO-PPO random copolymers, in an attempt to probe the effect of molecular architecture in the formation of micelles. No micelles were observed in aqueous PPO-PEO-PPO block copolymer solutions with increasing temperature, up to the cloud point.

  19. Crystallization behaviour of poly(ethylene oxide) under confinement in the electrospun nanofibers of polystyrene/poly(ethylene oxide) blends.

    PubMed

    Samanta, Pratick; V, Thangapandian; Singh, Sajan; Srivastava, Rajiv; Nandan, Bhanu; Liu, Chien-Liang; Chen, Hsin-Lung

    2016-06-21

    We have studied the confined crystallization behaviour of poly(ethylene oxide) (PEO) in the electrospun nanofibers of the phase-separated blends of polystyrene (PS) and PEO, where PS was present as the major component. The size and shape of PEO domains in the nanofibers were considerably different from those in the cast films, presumably because of the nano-dimensions of the nanofibers and the extensional forces experienced by the polymer solution during electrospinning. The phase-separated morphology in turn influenced the crystallization behaviour of PEO in the blend nanofibers. At a PEO weight fraction of ≥0.3, crystallization occurred through a heterogeneous nucleation mechanism similar to that in cast blend films. However, as the PEO weight fraction in the blend nanofibers was reduced from 0.3 to 0.2, an abrupt transformation of the nucleation mechanism from the heterogeneous to predominantly homogenous type was observed. The change in the nucleation mechanism implied a drastic reduction of the spatial continuity of PEO domains in the nanofibers, which was not encountered in the cast film. The melting temperature and crystallinity of the PEO crystallites developed in the nanofibers were also significantly lower than those in the corresponding cast films. The phenomena observed were reconciled by the morphological observation, which revealed that the phase separation under the radial constraint of the nanofibers led to the formation of small-sized fibrillar PEO domains with limited spatial connectivity. The thermal treatment of the PS/PEO blend nanofibers above the glass transition temperature of PS induced an even stronger confinement effect on PEO crystallization. PMID:27184694

  20. Features of anodic niobium oxide formation in aqueous-organic electrolyte solutions (influence of ethylene glycol)

    SciTech Connect

    Bairachnyi, B.I.; Gomozov, V.P.; Lyashok, L.V.; Glagolev, S.E.

    1992-02-10

    The formation of anodic oxide films (AOFs) on valve metals in electrolytes with different compositions has received little attention. Earlier investigations dealt mainly with AOF growth and properties in aqueous solutions of mineral and organic acids and salts. Less research was done on electrolytes containing aqueous-organic solvents. An empirically formulated electrolyte with a water/ethylene glycol mixture as the solvent is widely employed in forming the dielectric for semiconductor oxide capacitors (SOCs). The mechanism by which ethylene glycol acts on AOF properties is still not wholly clear. It has been found that AOFs produced in an ethylene glycol electrolyte are bilaminar, with the outer layer being less corrosion-resistant. The degradation resistance and crystalline phase content of AOFs have also been studied. The objective of the present study was to examine the effect of ethylene glycol as solvent on AOF formation on niobium.

  1. Poly(cyclohexylethylene)-block-poly(ethylene oxide) block polymers for metal oxide templating

    SciTech Connect

    Schulze, Morgan W.; Sinturel, Christophe

    2015-09-01

    A series of poly(cyclohexylethylene)-block-poly(ethylene oxide) (CEO) diblock copolymers were synthesized through tandem anionic polymerizations and heterogeneous catalytic hydrogenation. Solvent-annealed CEO diblock films were used to template dense arrays of inorganic oxide nanodots via simple spin coating of an inorganic precursor solution atop the ordered film. The substantial chemical dissimilarity of the two blocks enables (i) selective inclusion of the inorganic precursor within the PEO domain and (ii) the formation of exceptionally small feature sizes due to a relatively large interaction parameter estimated from mean-field analysis of the order–disorder transition temperatures of compositionally symmetric samples. UV/ozone treatment following incorporation produces an ordered arrangement of oxide nanodots and simultaneously removes the block polymer template. However, we report the smallest particles (6 ± 1 nm) templated from a selective precursor insertion method to date using a block polymer scaffold.

  2. Synthesis of ethylene and ethane by partial oxidation of methane over lithium-doped magnesium oxide

    NASA Astrophysics Data System (ADS)

    Ito, Tomoyasu; Lunsford, Jack H.

    1985-04-01

    The partial oxidation of methane into more useful chemicals such as methanol, ethylene and benzene has been investigated extensively, although yields for these products have been poor1-4. Moreover, in several of these processes the required oxidant is N2O rather than O2. Recent work5 in our laboratory has demonstrated that lithium-doped magnesium oxide (Li/MgO) in the presence of O2 has high activity for abstracting H from CH4 to form .CH3 radicals. This suggests that C2H6 and C2H4 (C2 compounds) are produced by a coupling between two gaseous .CH3 radicals formed on this catalyst. We report here our success in converting CH4 to C2 compounds in high yields in conventional catalytic conditions.

  3. Poly(cyclohexylethylene)-block-poly(ethylene oxide) block polymers for metal oxide templating

    DOE PAGESBeta

    Schulze, Morgan W.; Sinturel, Christophe; Hillmyer, Marc A.

    2015-09-01

    A series of poly(cyclohexylethylene)-block-poly(ethylene oxide) (CEO) diblock copolymers were synthesized through tandem anionic polymerizations and heterogeneous catalytic hydrogenation. Solvent-annealed CEO diblock films were used to template dense arrays of inorganic oxide nanodots via simple spin coating of an inorganic precursor solution atop the ordered film. The substantial chemical dissimilarity of the two blocks enables (i) selective inclusion of the inorganic precursor within the PEO domain and (ii) the formation of exceptionally small feature sizes due to a relatively large interaction parameter estimated from mean-field analysis of the order–disorder transition temperatures of compositionally symmetric samples. UV/ozone treatment following incorporation produces anmore » ordered arrangement of oxide nanodots and simultaneously removes the block polymer template. However, we report the smallest particles (6 ± 1 nm) templated from a selective precursor insertion method to date using a block polymer scaffold.« less

  4. Study of core-shell platinum-based catalyst for methanol and ethylene glycol oxidation

    NASA Astrophysics Data System (ADS)

    Kaplan, D.; Alon, M.; Burstein, L.; Rosenberg, Yu.; Peled, E.

    A Ru core-Pt shell, XC72-supported catalyst was synthesized in a two-step process: first, by deposition of Ru on XC72 by the polyol process and then by deposition of Pt on the XC72-supported Ru, with NaBH 4 as reducing agent. The structure and composition of this core-shell catalyst were determined by EDS, XPS, TEM and XRD. Electrochemical characterization was determined with the use of cyclic voltammetry and chronoamperometry. The methanol and ethylene glycol oxidation activities of the core-shell catalyst were studied at 80 °C and compared to those of a commercial catalyst. It was found to be significantly better (in terms of A g -1 of Pt) in the case of methanol oxidation and worse in the case of ethylene glycol oxidation. Possible reasons for the lower ethylene glycol oxidation activity of the core-shell catalyst are discussed.

  5. Determination of ethylene oxide in ethoxylated surfactants and demulsifiers by headspace gas chromatography.

    PubMed

    Dahlgran, J R; Shingleton, C R

    1987-01-01

    A headspace gas chromatographic method for the determination of traces of ethylene oxide in ethoxylated surfactants and demulsifiers was developed. Samples are analyzed directly by the technique to a 1.0 ppm (w/w) quantitation limit. The procedure also performs well for propylene oxide, acetaldehyde, and 1,4-dioxane. It is simple, sensitive, and linear. The percent relative standard deviations for 0.5 and 30 ppm ethylene oxide in the surfactant were 2.8 and 8.3%, respectively. PMID:3680111

  6. Miscibility and degradability of poly(lactic acid)poly(ethylene oxide)/poly(ethylene glycol) blends

    SciTech Connect

    Yue, C.L.; Dave, V.; Gross, R.A.; McCarthy, S.P.

    1995-12-01

    Poly(lactic acid) [PLA] was melt blended with polyethylene(oxide) [PEG] and poly(ethylene glycol) [PEG] in different compositions to form blown films. It was determined that PLA was miscible with PEO in all compositions. Based on Gordon-Taylor equation, it was determined that the interactions between PLA and PEO is stronger than PEG. The addition of low molecular weight PEG improved the elongation and tear strength of the blends. Enzymatic degradation results shows that the weight loss of all the samples was more than 80% of the initial weight in 48 hours.

  7. Permeability and partitioning of ferrocene ethylene oxide and propylene oxide oligomers into electropolymerized films from acetonitrile and polyether solutions

    SciTech Connect

    Pyati, R.; Murray, R.W. )

    1994-10-27

    We report the first electrochemically-based measurements of the rates of small polymer permeation into another polymer. The small polymer permeants are ferrocene ethylene oxide oligomers containing 2, 7, and 16 units and a propylene oxide oligomer containing 3 units. Their permeation into ultrathin microelectrode-supported films of the metal complex polymer poly[Ru(vbpy)[sub 3

  8. Temperature-Dependent Deicing Properties of Electrostatically Anchored Branched Brush Layers of Poly(ethylene oxide).

    PubMed

    Heydari, Golrokh; Tyrode, Eric; Visnevskij, Ceslav; Makuska, Ricardas; Claesson, Per M

    2016-05-01

    The hydration water of hydrophilic polymers freezes at subzero temperatures. The adsorption of such polymers will result in a hydrophilic surface layer that strongly binds water. Provided this interfacial hydration water remains liquidlike at subzero temperatures, its presence could possibly reduce ice adhesion, in particular, if the liquidlike layer is thicker than or comparable to the surface roughness. To explore this idea, a diblock copolymer, having one branched bottle-brush block of poly(ethylene oxide) and one linear cationic block, was electrostatically anchored on flat silica surfaces. The shear ice adhesion strength on such polymer-coated surfaces was investigated down to -25 °C using a homebuilt device. In addition, the temperature dependence of the ice adhesion on surfaces coated with only the cationic block, only the branched bottle-brush block, and with linear poly(ethylene oxide) was investigated. Significant ice adhesion reduction, in particular, at temperatures above -15 °C, was observed on silica surfaces coated with the electrostatically anchored diblock copolymer. Differential scanning calorimetry measurements on bulk polymer solutions demonstrate different thermal transitions of water interacting with branched and linear poly(ethylene oxide) (with hydration water melting points of about -18 and -10 °C, respectively). This difference is consistent with the low shear ice adhesion strength measured on surfaces carrying branched bottle-brush structured poly(ethylene oxide) at -10 °C, whereas no significant adhesion reduction was obtained with linear poly(ethylene oxide) at this temperature. We propose a lubrication effect of the hydration water bound to the branched bottle-brush structured poly(ethylene oxide), which, in the bulk, does not freeze until -18 °C. PMID:27064661

  9. Self-Assembly in a Mixture of Two Poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) Copolymers in Water

    PubMed

    Zhou; Alexandridis; Khan

    1996-11-10

    The self-assembly behavior in water of a mixture of two poly (ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) copolymers, (EO)13(PO)30(EO)13 (L64) and (EO)37(PO)58(EO)37 (P105), was explored at 25°C. The phase boundaries were established using 2H-NMR and inspection under polarized light; the structure of the various lyotropic liquid crystalline (LLC) phases was determined with small-angle X-ray scattering, while viscosity and differential scanning calorimetry measurements were used to probe the isotropic water-rich solution region. Isotropic regions, similar to the neat polymers, are stable at high polymer content. The addition of water induces structure in the amphiphilic block copolymer system. An extended lamellar (D) LLC phase is formed at 20-25% water content; a hexagonal (E) and a cubic (I) LLC phases supersede D at higher water contents. In addition to the above, a narrow isotropic region (L') is observed on the L64-water binary axis, in equilibrium with the E and the D phases. The hexagonal and lamellar LLC phases extended all the way from the L64-rich to the P105-rich side of the ternary L64-P105-water phase diagram; the characteristic hexagonal and lamellar structural dimensions varied linearly with P105 content in the L64-P105 mixture at a constant water concentration. An isotropic (micellar) solution phase (L1) dominates the high-water content corner of the ternary phase diagram. Viscosity measurements in this region provided evidence for increased interactions between the micelles as the boundary to the LLC phases was approached. PMID:8954676

  10. A Nanoarchitecture Based on Silver and Copper Oxide with an Exceptional Response in the Chlorine-Promoted Epoxidation of Ethylene.

    PubMed

    Ramirez, Adrian; Hueso, Jose L; Suarez, Hugo; Mallada, Reyes; Ibarra, Alfonso; Irusta, Silvia; Santamaria, Jesus

    2016-09-01

    The selective oxidation of ethylene to ethylene epoxide is highly challenging as a result of competing reaction pathways leading to the deep oxidation of both ethylene and ethylene oxide. Herein we present a novel catalyst based on silver and copper oxide with an excellent response in the selective oxidation pathway towards ethylene epoxide. The catalyst is composed of different silver nanostructures dispersed on a tubular copper oxide matrix. This type of hybrid nanoarchitecture seems to facilitate the accommodation of chlorine promoters, leading to high yields at low reaction temperatures. The stability after the addition of chlorine promoters implies a substantial improvement over the industrial practice: a single pretreatment step at ambient pressure suffices in contrast with the common practice of continuously feeding organochlorinated precursors during the reaction. PMID:27404950

  11. MUTATION AND ENHANCED VIRUS TRANSFORMATION OF CULTURED HAMSTER CELLS BY EXPOSURE TO GASEOUS ETHYLENE OXIDE

    EPA Science Inventory

    Ethylene oxide is a classical mutagen and a carcinogen based on evidence from studies in experimental animals. It is widely distributed in industrial, research, hospital, and food environments. In an effort to explore the use of newly developed methods for exposing mammalian cell...

  12. Synthesis of Monodispersed Tantalum(V) oxide Nanospheres by an Ethylene Glycol Mediated Route

    EPA Science Inventory

    Tantalum(V) oxide (Ta2O5) nanospheres have been synthesized by a very simple ethylene glycol mediated route. The two-step process involves the formation of glycolate nanoparticles and their subsequent hydrolysis and calcination to generate the final Ta2O5 nanospheres. The synthes...

  13. NITRIC OXIDE AND NITRITE TREATMENTS REDUCE ETHYLENE EVOLUTION FROM APPLE FRUIT DISKS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    ‘Golden Delicious’ apple [Malus sylvestris var. domestica (Borkh.)] cortex disks suspended in solutions containing a nitric oxide ('NO) donor [S-nitrosoglutathione (GSNO) or sodium nitroprusside (SNP)], 'NO gas, or nitrite (KNO2) were utilized to identify impacts of 'NO on ethylene production and NO...

  14. Evaluation of the Inhalation Carcinogenicity of Ethylene Oxide (Interagency Science Discussion Draft)

    EPA Science Inventory

    On September 22, 2006, the draft Evaluation of the Carinogenicity of Ethylene Oxide (EPA/635/R-06/003) and the draft charge to external peer reviewers were released for external peer review and public comment. This draft was reviewed by EPA’s Science Advisory Board (SAB)...

  15. 40 CFR 721.7000 - Polymer of disodium maleate, allyl ether, and ethylene oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Polymer of disodium maleate, allyl... New Uses for Specific Chemical Substances § 721.7000 Polymer of disodium maleate, allyl ether, and... substance identified generically as a polymer of disodium maleate, allyl ether, and ethylene oxide...

  16. 40 CFR 721.7000 - Polymer of disodium maleate, allyl ether, and ethylene oxide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Polymer of disodium maleate, allyl... New Uses for Specific Chemical Substances § 721.7000 Polymer of disodium maleate, allyl ether, and... substance identified generically as a polymer of disodium maleate, allyl ether, and ethylene oxide...

  17. 40 CFR 721.7000 - Polymer of disodium maleate, allyl ether, and ethylene oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Polymer of disodium maleate, allyl... New Uses for Specific Chemical Substances § 721.7000 Polymer of disodium maleate, allyl ether, and... substance identified generically as a polymer of disodium maleate, allyl ether, and ethylene oxide...

  18. 78 FR 46260 - Sorbitan Monooleate Ethylene Oxide Adduct; Exemption From the Requirement of a Tolerance

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-31

    ... monooleate ethylene oxide adduct is low; the LD 50 was >25,000 mg/kg in the rat and mouse. Also, no systemic... considered nonmutagenic. Evidence of carcinogenicity was not observed in mice. In rats, the incidence of... studies in rats and mice. Also, toxicity was only observed at doses (>10,000 mg/kg/day) well above...

  19. 40 CFR 721.7000 - Polymer of disodium maleate, allyl ether, and ethylene oxide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polymer of disodium maleate, allyl... New Uses for Specific Chemical Substances § 721.7000 Polymer of disodium maleate, allyl ether, and... substance identified generically as a polymer of disodium maleate, allyl ether, and ethylene oxide...

  20. SIMULATING THE IN-SITU OXIDATIVE TREATMENT OF CHLORINATED ETHYLENES BY POTASSIUM PERMANGANATE

    EPA Science Inventory

    In recent years, MnO{sub}4 oxidation of chlorinated ethylenes (PCE, TCE, and DCE) has emerged as a potentially useful approach for destroying these componds in water. Recently, more applied studies have looked at whether KMnO{sub}4 could be used in remediating sites contaminated ...

  1. 40 CFR 721.7000 - Polymer of disodium maleate, allyl ether, and ethylene oxide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Polymer of disodium maleate, allyl... New Uses for Specific Chemical Substances § 721.7000 Polymer of disodium maleate, allyl ether, and... substance identified generically as a polymer of disodium maleate, allyl ether, and ethylene oxide...

  2. Microviscosity in Pluronic and Tetronic poly(ethylene oxide)-poly(propylene oxide) block copolymer micelles

    SciTech Connect

    Nivaggioli, T.; Tsao, B.; Alexandridis, P.; Hatton, T.A. )

    1995-01-01

    The micellar microviscosity afforded by Pluronic and Tetronic poly(ethylene oxide)-poly(propylene oxide) block copolymer aqueous solutions has been investigated by fluorescence and NMR spectroscopy. Comparison is made with bulk poly(propylene oxide) (PPO) samples of different molecular weights. The microviscosity in Pluronic PEO-PPO-PEO copolymer micelles is much larger than that observed in conventional surfactant micelles and depends strongly on the size of the hydrophobic PPO block: the larger this block, the higher the viscosity. Above the critical micellar temperature (CMT), as temperature increases, the microviscosity decreases. However, this decrease is not as important as that observed in bulk PPO. Hence, the relative microviscosity, defined as the ratio of the two observed phenomena, increases. This suggests structural transformation of the micelles resulting in a core becoming more and more compact as temperature increases. Such results have been confirmed by NMR studies that showed broadening of the PPO peak and relatively constant spin-lattice relaxation time, T[sub i], with increasing temperature while the PEO signal remained relatively sharp with an exponential increase in T[sub 1]. 30 refs., 9 figs., 1 tab.

  3. Solubilization of docetaxel in poly(ethylene oxide)-block-poly(butylene/styrene oxide) micelles.

    PubMed

    Elsabahy, Mahmoud; Perron, Marie-Eve; Bertrand, Nicolas; Yu, Ga-Er; Leroux, Jean-Christophe

    2007-07-01

    Poly(ethylene oxide)-block-poly(styrene oxide) (PEO-b-PSO) and PEO-b-poly(butylene oxide) (PEO-b-PBO) of different chain lengths were synthesized and characterized for their self-assembling properties in water by dynamic/static light scattering, spectrofluorimetry, and transmission electron microscopy. The resulting polymeric micelles were evaluated for their ability to solubilize and protect the anticancer drug docetaxel (DCTX) from degradation. The drug release kinetics as well as the cytotoxicity of the loaded micelles were assessed in vitro. All polymers formed micelles with a highly viscous core at low critical association concentrations (<10 mg/L). Micelle morphology depended on the nature of the hydrophobic block, with PBO- and PSO-based micelles yielding monodisperse spherical and cylindrical nanosized aggregates, respectively. The maximum solubilization capacity for DCTX ranged from 0.7 to 4.2% and was the highest for PSO micelles exhibiting the longest hydrophobic segment. Despite their high affinity for DCTX, PEO-b-PSO micelles were not able to efficiently protect DCTX against hydrolysis under accelerated stability testing conditions. Only PEO-b-PBO bearing 24 BO units afforded significant protection against degradation. In vitro, DCTX was released slower from the latter micelles, but all formulations possessed a similar cytotoxic effect against PC-3 prostate cancer cells. These data suggest that PEO-b-P(SO/BO) micelles could be used as alternatives to conventional surfactants for the solubilization of taxanes. PMID:17579476

  4. Thermo-oxidative stability of electron beam irradiated ethylene norbornene copolymer

    NASA Astrophysics Data System (ADS)

    Aymes-Chodur, Caroline; Sghaïer, M.; Yagoubi, N.

    2016-01-01

    The effect of ionizing radiation on the thermal stability of ethylene norbornene copolymer (ENC) to which a phenolic antioxidant (AO), Irganox 1010®, had been added, was investigated. To this end, a series of appropriate thermal analyzes methods (TGA, DSC, OIT measurements), were used for testing the polymer matrix oxidation level. We were able to correlate the diminution of AO concentration with the oxidation induction time and calculate the activation energy, thereby demonstrating the efficiency of the AO and the effect of radiation.

  5. Abundances of ethylene oxide and acetaldehyde in hot molecular cloud cores

    NASA Technical Reports Server (NTRS)

    Nummelin, A.; Dickens, J. E.; Bergman, P.; Hjalmarson, A.; Irvine, W. M.; Ikeda, M.; Ohishi, M.

    1998-01-01

    We have searched for millimetre-wave line emission from ethylene oxide (c-C2H4O) and its structural isomer acetaldehyde (CH3CHO) in 11 molecular clouds using SEST. Ethylene oxide and acetaldehyde were detected through multiple lines in the hot cores NGC 6334F, G327.3-0.6, G31.41+0.31, and G34.3+0.2. Acetaldehyde was also detected towards G10.47+0.03, G322.2+0.6, and Orion 3'N, and one ethylene oxide line was tentatively detected in G10.47+0.03. Column densities and rotational excitation temperatures were derived using a procedure which fits the observed line intensifies by finding the minimum chi 2-value. The resulting rotational excitation temperatures of ethylene oxide and acetaldehyde are in the range 16-38 K, indicating that these species are excited in the outer, cooler parts of the hot cores or that the excitation is significantly subthermal. For an assumed source size of 20", the deduced column densities are (0.6-1)x10(14) cm-2 for ethylene oxide and (2-5)x10(14) cm-2 for acetaldehyde. The fractional abundances with respect to H2 are X[c-C2H4O]=(2-6)xl0(-10), and X[CH3CHO]=(0.8-3)x10(-9). The ratio X[CH3CHO]/X[c-C2H4O] varies between 2.6 (NGC 6334F) and 8.5 (G327.3-0.6). We also detected and analysed multiple transitions of CH3OH, CH3OCH3, C2H5OH, and HCOOH. The chemical, and possibly evolutionary, states of NGC 6334F, G327.3-0.6, G31.41+0.31, and G34.3+0.2 seem to be very similar.

  6. Janus-Type Dendrimer-like Poly(ethylene oxide)s

    PubMed Central

    Feng, Xiaoshuang; Taton, Daniel; Ibarboure, Emmanuel; Chaikof, Elliot L.; Gnanou, Yves

    2009-01-01

    A straightforward and original methodology allowing the synthesis of Janus-type dendrimer-like poly(ethylene oxide)s (PEOs) carrying orthogonal functional groups on their surface is described. The use of 3-allyloxy-1,2-propanediol (1) as a latent AB2-type heterofunctional initiator of anionic ring-opening polymerization (AROP) of ethylene oxide (EO) and of selective branching agents of PEO chain ends served to construct the two dendrons of these dendrimer-like PEOs, following a divergent pathway. Thus, the first PEO generation of the first dendron was grown by AROP from 1 followed by the reaction of the corresponding α-allyl,ω,ω′-bishydroxy- heterofunctional PEO derivative with 2-(3′-chloromethybenzyloxymethyl)-2-methyl-5,5-dimethyl-1,3-dioxane (2) used as a branching agent. This afforded the dendron A with four latent peripheral hydroxyls protected in the form of two ketal rings. The remaining α-allylic double bond of the PEO thus prepared was transformed into two hydroxyl groups using OsO4 in order to create the first PEO generation of the dendron B by AROP of EO. Allyl chloride (3) was then used as another (latent) branching agent to react with the terminal hydroxyl of the corresponding PEO chains. Deprotection under acidic conditions of the ketal groups of dendron A, followed by AROP of EO, afforded the second PEO generation on this face. This alternate and divergent procedure, combining AROP of EO and selective branching of PEO branches, could be readily iterated, one dendron after the other up to the generation six, leading to a Janus-type dendrimer-like PEO exhibiting a total mass of around 300 kg/mol and possessing 64 peripheral groups on each face. The possibility of orthogonal functionalization of the surfaces of such Janus-type dendritic PEOs was exploited. Indeed, a dendron of generation 4 was functionalized with hydroxyl functions at its periphery, whereas the other was end-capped with either tertiary amino or disulfide groups. In a variant of

  7. In-depth survey report: control technology for ethylene oxide sterilization at Euclid General Hospital, Euclid, Ohio

    SciTech Connect

    O'Brien, D.

    1985-06-01

    An indepth survey of control technology for ethylene oxide sterilization was conducted. Industrial hygiene sampling for ethylene-oxide was conducted. Engineering controls consisted of local exhaust ventilation above the sterilizers, at the drain, at the safety relief valve, and around the ethylene-oxide cylinders, general ventilation, and use of a pulse/purge phase at the end of the sterilization cycle. A three-component ethylene-oxide monitoring program was in place, consisting of continuous monitoring with an alarm system, environmental area monitoring performed by an outside contractor, and exposures were below 0.2 part per million. The OSHA time weighted average (TWA) standard for ethylene oxide is 1 ppm. Proper work practices for employees were outlined in a procedure and policy manual. The Central Services Director provided education and training on proper work practices and the hazards of ethylene-oxide exposure. The author concludes that the engineering controls at the facility successfully minimize employee exposure to ethylene oxide.

  8. Ethylene Oxide in Blood of Ethylene-Exposed B6C3F1 Mice, Fischer 344 Rats, and Humans

    PubMed Central

    Filser, Johannes Georg; Erbach, Eva; Faller, Thomas; Kreuzer, Paul Erich; Li, Qiang

    2013-01-01

    The gaseous olefin ethylene (ET) is metabolized in mammals to the carcinogenic epoxide ethylene oxide (EO). Although ET is the largest volume organic chemical worldwide, the EO burden in ET-exposed humans is still uncertain, and only limited data are available on the EO burden in ET-exposed rodents. Therefore, EO was quantified in blood of mice, rats, or 4 volunteers that were exposed once to constant atmospheric ET concentrations of between 1 and 10 000 ppm (rodents) or 5 and 50 ppm (humans). Both the compounds were determined by gas chromatography. At ET concentrations of between 1 and 10 000 ppm, areas under the concentration-time curves of EO in blood (µmol × h/l) ranged from 0.039 to 3.62 in mice and from 0.086 to 11.6 in rats. At ET concentrations ≤ 30 ppm, EO concentrations in blood were 8.7-fold higher in rats and 3.9-fold higher in mice than that in the volunteer with the highest EO burdens. Based on measured EO concentrations, levels of EO adducts to hemoglobin and lymphocyte DNA were calculated for diverse ET concentrations and compared with published adduct levels. For given ET exposure concentrations, there were good agreements between calculated and measured levels of adducts to hemoglobin in rats and humans and to DNA in rats and mice. Reported hemoglobin adduct levels in mice were higher than calculated ones. Furthermore, information is given on species-specific background adduct levels. In summary, the study provides most relevant data for an improved assessment of the human health risk from exposure to ET. PMID:24068676

  9. Ethylene oxide-block-butylene oxide copolymer uptake by silicone hydrogel contact lens materials

    NASA Astrophysics Data System (ADS)

    Huo, Yuchen; Ketelson, Howard; Perry, Scott S.

    2013-05-01

    Four major types of silicone hydrogel contact lens material have been investigated following treatments in aqueous solutions containing poly(ethylene oxide) and poly(butylenes oxide) block copolymer (EO-BO). The extent of lens surface modification by EO-BO and the degree of bulk uptake were studied using X-ray photoelectron spectroscopy (XPS) and ultra-performance liquid chromatography (UPLC), respectively. The experimental results suggest that different interaction models exist for the lenses, highlighting the influence of both surface and bulk composition, which greatly differs between the lenses examined. Specifically, lenses with hydrophilic surface treatments, i.e., PureVision® (balafilcon A) and O2OPTIX (lotrafilcon B), demonstrated strong evidence of preferential surface adsorption within the near-surface region. In comparison, surface adsorption on ACUVUE® Oasys® (senofilcon A) and Biofinity® (comfilcon A) was limited. As for bulk absorption, the amount of EO-BO uptake was the greatest for balafilcon A and comfilcon A, and least for lotrafilcon B. These findings confirm the presence of molecular concentration gradients within the silicone hydrogel lenses following exposure to EO-BO solutions, with the nature of such concentration gradients found to be lens-specific. Together, the results suggest opportunities for compositional modifications of lenses for improved performance via solution treatments containing surface-active agents.

  10. Effect of nitric oxide on ethylene synthesis and softening of banana fruit slice during ripening.

    PubMed

    Cheng, Guiping; Yang, En; Lu, Wangjin; Jia, Yongxia; Jiang, Yueming; Duan, Xuewu

    2009-07-01

    The effects of nitric oxide (NO) on ethylene synthesis and softening of ripening-initiated banana slice were investigated. Fruit firmness, color, and contents of starch and acid-soluble pectin (ASP) were measured. In addition, ethylene production, 1-aminocyclopropane-1-carboxylic acid (ACC) content, expression and activities of ACC synthase (ACS) and ACC oxidase (ACO), and activities of cell-wall-modifying enzymes, polygalacturonase (PG), pectin methylesterase (PME), and endo-beta-1,4-glucanase, were analyzed. Application of NO reduced ethylene production, inhibited degreening of the peel and delayed softening of the pulp. The decrease of ethylene production was associated with the reduction in the activity of ACO and the expression of the MA-ACO1 gene. Moreover, the NO-treated fruit showed a lower expression of the MA-ACS1 gene but higher ACS activity and ACC content. In addition, NO treatment decreased the activities of PG, PME, and endo-beta-1,4-glucanase and maintained higher contents of ASP and starch, which may account for the delay of softening. We proposed that the inhibition of ACO activity and transcription of gene MA-ACO1 by NO resulted in decreased ethylene synthesis and the delay of ripening of banana slice. PMID:19534461

  11. Simulating the in situ oxidative treatment of chlorinated ethylenes by potassium permanganate

    NASA Astrophysics Data System (ADS)

    Zhang, Hubao; Schwartz, Franklin W.

    2000-10-01

    Several laboratory and field studies have demonstrated the potential viability of oxidation schemes using MnO4- for the in situ treatment of source areas, which are contaminated by chlorinated ethylenes (PCE, TCE, and DCE). Chemically, the chlorinated ethylenes are oxidized to CO2, Cl-, and MnO2. The goal of this study was to develop a theoretical framework for the chemical and physical processes involved. To this end, a computer model was created to simulate the coupled processes of nonaqueous phase liquid (NAPL) dissolution, chemical reactions, and solute mass transport in the in situ chemical oxidization scheme. The model incorporates a kinetic description of reactions between the MnO4- and the chlorinated ethylenes and the rate of dissolution of the NAPL. A Strang operator-splitting method, which coupled the different physical and chemical processes and an exponentially expressed solution of the kinetic equations, led to a significant speed up in the solution process. The products were calculated based on the stoichiometry of the reaction. We demonstrated the capabilities of this code using already published results of column, test cell, and field experiments. Generally, the simulated results matched well with experimental measurements. The computer model provides a useful tool for assisting in the design and the prediction of the oxidization processes under field conditions.

  12. Toxicology and carcinogenesis studies of ethylene oxide (CAS No. 75-21-8) in B6C3F1 mice (inhalation studies). Technical report series (Final). [Ethylene oxide

    SciTech Connect

    Not Available

    1987-11-01

    Two-year toxicology and carcinogenesis studies of ethylene oxide were conducted by exposing groups of 50 B6C3F(1) mice of each sex to air containing 0, 50, or 100 ppm ethylene oxide 6 hours per day, 5 days per week for 102 weeks. Under the conditions of these 2-year inhalation studies, there was clear evidence of carcinogenic activity for B6C3F(1) mice as indicated by dose-related increased incidences of benign or malignant neoplasms of the lung and benign neoplasms of the harderian gland in both male and female B6C3F(1) mice following exposure to ethylene oxide vapors at 50 and 100 ppm. In female mice, ethylene oxide caused additional malignant neoplasms of the uterus, mammary gland, and hematopoietic system (lymphoma).

  13. Poly(ethylene glycol) enclatherated pectin-mucin submicron matrices for intravaginal anti-HIV-1 drug delivery.

    PubMed

    Mashingaidze, Felix; Choonara, Yahya E; Kumar, Pradeep; du Toit, Lisa C; Maharaj, Vinesh; Buchmann, Eckhart; Pillay, Viness

    2016-04-30

    This paper explores the potential of polyethylene glycol enclatherated pectin-mucin (PEG-encl-PEC:MUC) submicron matrices (SMMs) as an intravaginal drug delivery system capable of delivering an anti-HIV-1 agent (zidovudine; AZT) over a prolonged duration. A three factor and three level (3(3)) Box-Behnken statistical design was employed to optimize the SMMs. Optimized PEG-encl-PEC:MUC SMMs prepared as a stable W/O emulsion (determined by the degree of reversible colloidal phenomena) were spherical with a mean particle size of 270.6±5.533nm and mean zeta potential of -34.4±0.539mV. The microencapsulation of AZT and the hydrogen bonding mediated shielding of AZT by SMMs was confirmed by Fourier Transform Infrared (FTIR) analysis. The thermochemical (differential scanning calorimetry and thermogravimetric analysis) data proposed that Ca(2+)-based macromolecular ionic crosslinking as well as the intermolecular interactions may be responsible for the thermal stability of the delivery system. The partially amorphous nature of drug-loaded SMMs, as confirmed by X-ray diffraction patterns, further strengthened the matricization of AZT into the pectin-mucin matrix. In vitro drug release studies from the SMMs showed approximately 91% zidovudine release in simulated vaginal fluid (SVF) and 94% in phosphate buffered saline (PBS) in 24h. The mean dissolution time (MDT) of zidovudine from the SMMs was 5.974h. The attainment of required dimensional structure and drug release profiles from SMMs highlights the potential of their inclusion into a secondary carrier system for extended and controlled intravaginal stay. PMID:26943973

  14. Health Hazard Evaluation Report HETA 85-065-1578, United Hospital, Grand Forks, North Dakota. [Ethylene oxide

    SciTech Connect

    Gunter, B.J.

    1985-04-01

    Environmental and breathing zone samples were analyzed for ethylene-oxide at United Hospital, Grand Forks, North Dakota in January, 1985. The survey was requested by the management to determine if using ethylene-oxide for sterilization purposes posed a health risk. All employees (number not specified) in the central supply department were interviewed. These concentrations originated from an old sterilizer. The sterilizer was not normally used, but was operated on the day of the survey to stimulate a worst-case situation. None of the workers had any medical complaints. The author concludes that a health hazard due to ethylene-oxide does not exist at the facility. He recommends not using the old sterilizer until it has been refurbished and conducting periodic monitoring for ethylene/oxide with an infrared analyzer.

  15. Study of the desorption of ethylene oxide fixed on various materials during sterilization by a new procedure

    NASA Technical Reports Server (NTRS)

    Lacomme, M.; Chaigneau, M.; Lemoan, G.

    1977-01-01

    A continuous sterilization process using ethylene oxide was studied in comparison with a classical method in order to evaluate gas retention as a function of time and temperature on polyethylene, PVC, and rubber materials.

  16. Nano-structured Platinum-based Catalysts for the Complete Oxidation of Ethylene Glycol and Glycerol

    NASA Astrophysics Data System (ADS)

    Falase, Akinbayowa

    Direct alcohol fuel cells are a viable alternative to the traditional hydrogen PEM fuel cell. Fuel versatility, integration with existing distribution networks, and increased safety when handling these fuels increases their appeal for portable power applications. In order to maximize their utility, the liquid fuel must be fully oxidized to CO2 so as to harvest the full amount of energy. Methanol and ethanol are widely researched as potential fuels to power these devices, but methanol is a toxic substance, and ethanol has a much lower energy density than other liquids such as gasoline or glucose. Oxidation of complex fuels is difficult to realize, due to difficulty in breaking carbon-carbon bonding and poisoning of the catalysts by oxidative byproducts. In order to achieve the highest efficiency, an anode needs to be engineered in such a way as to maximize activity while minimizing poisoning effects of reaction byproducts. We have engineered an anode that uses platinum-based catalysts that is capable of completely oxidizing ethylene glycol and glycerol in neutral and alkaline media with little evidence of CO poisoning. We have constructed a hybrid anode consisting of a nano-structured PtRu electrocatayst with an NAD-dependent alcohol dehydrogenase for improved oxidation of complex molecules. A nano-structured PtRu catalyst was used to oxidize ethylene glycol and glycerol in neutral media. In situ infrared spectroscopy was used to verify complete oxidation via CO2 generation. There was no evidence of poisoning by CO species. A pH study was performed to determine the effect of pH on oxidative current. The peak currents did not trend at 60 mV/pH unit as would be expected from the Nernst equation, suggesting that adsorption of fuel to the surface of the electrode is not an electron-transfer step. We synthesized nano-structured PtRu, PtSn, and PtRuSn catalysts for oxidation of ethylene glycol and glycerol in alkaline media. The PtRu electrocatalyst the highest oxidative

  17. Linear poly(ethylene oxide)-based polyurethane hydrogels: polyurethane-ureas and polyurethane-amides.

    PubMed

    Petrini, P; Tanzi, M C; Moran, C R; Graham, N B

    1999-01-01

    Over the last 30 years, water-swellable and water-insoluble hydrogels have been extensively investigated and developed, leading to a large family of materials which have found uses in a wide range of biomedical applications. While hydrogels usually present a crosslinked structure, linear polyurethane-ureas (PUUs) based on poly(ethylene oxide) have been shown to be able to absorb and swell with aqueous media without dissolving. This behavior is due to the phase separated domain morphology, where hydrogen bonded urethane/urea hard segment domains are dispersed in a PEO soft segment domain. This work investigates the possibility of obtaining linear poly(ethylene oxide)-based polyurethane-amide (PUA) hydrogels using two amide diols as chain extenders, a mono amide diol (AD) and a diamide diol (DD), and a dicarboxylic acid (maleic acid, MA). Poly(ethylene oxide) based PUAs were obtained using a "one-shot" bulk polymerization technique. The chemicophysical characterization and water-solubility tests showed that these materials, while having molecular weights similar to the PUUs, do not possess sufficient phase separation, hydrogen bonding and hydrophobicity of the hard segment domains to exhibit hydrogel behavior. Crosslinked PUAs using maleic acid as chain extender show interesting hydrogel properties. PMID:15347978

  18. Iron oxide/cassava starch-supported Ziegler-Natta catalysts for in situ ethylene polymerization.

    PubMed

    Chancharoenrith, Sittikorn; Kamonsatikul, Choavarit; Namkajorn, Montree; Kiatisevi, Supavadee; Somsook, Ekasith

    2015-03-01

    Iron oxide nanoparticles were used as supporters for in situ polymerization to produce polymer nanocomposites with well-dispersed fillers in polymer matrix. Iron oxide could be sustained as colloidal solutions by cassava starch to produce a good dispersion of iron oxide in the matrix. New supports based on iron oxide/cassava starch or cassava starch for Ziegler-Natta catalysts were utilized as heterogeneous supporters for partially hydrolyzed triethylaluminum. Then, TiCl4 was immobilized on the supports as catalysts for polymerization of ethylene. High-density polyethylene (HDPE) composites were obtained by the synthesized catalysts. A good dispersion of iron oxide/cassava starch particles was observed in the synthesized polymer matrix promoting to good mechanical properties of HDPE. PMID:25498641

  19. Mechanical Characterization of Hybrid Vesicles Based on Linear Poly(Dimethylsiloxane-b-Ethylene Oxide) and Poly(Butadiene-b-Ethylene Oxide) Block Copolymers.

    PubMed

    Gaspard, Jeffery; Casey, Liam M; Rozin, Matt; Munoz-Pinto, Dany J; Silas, James A; Hahn, Mariah S

    2016-01-01

    Poly(dimethylsiloxane-ethylene oxide) (PDMS-PEO) and poly(butadiene-b-ethylene oxide) (PBd-PEO) are two block copolymers which separately form vesicles with disparate membrane permeabilities and fluidities. Thus, hybrid vesicles formed from both PDMS-PEO and PBd-PEO may ultimately allow for systematic, application-specific tuning of vesicle membrane fluidity and permeability. However, given the relatively low strength previously noted for comb-type PDMS-PEO vesicles, the mechanical robustness of the resulting hybrid vesicles must first be confirmed. Toward this end, we have characterized the mechanical behavior of vesicles formed from mixtures of linear PDMS-PEO and linear PBd-PEO using micropipette aspiration. Tension versus strain plots of pure PDMS12-PEO46 vesicles revealed a non-linear response in the high tension regime, in contrast to the approximately linear response of pure PBd33-PEO20 vesicles. Remarkably, the area expansion modulus, critical tension, and cohesive energy density of PDMS12-PEO46 vesicles were each significantly greater than for PBd33-PEO20 vesicles, although critical strain was not significantly different between these vesicle types. PDMS12-PEO46/PBd33-PEO20 hybrid vesicles generally displayed graded responses in between that of the pure component vesicles. Thus, the PDMS12-PEO46/PBd33-PEO20 hybrid vesicles retained or exceeded the strength and toughness characteristic of pure PBd-PEO vesicles, indicating that future assessment of the membrane permeability and fluidity of these hybrid vesicles may be warranted. PMID:26999148

  20. Mechanical Characterization of Hybrid Vesicles Based on Linear Poly(Dimethylsiloxane-b-Ethylene Oxide) and Poly(Butadiene-b-Ethylene Oxide) Block Copolymers

    PubMed Central

    Gaspard, Jeffery; Casey, Liam M.; Rozin, Matt; Munoz-Pinto, Dany J.; Silas, James A.; Hahn, Mariah S.

    2016-01-01

    Poly(dimethylsiloxane-ethylene oxide) (PDMS-PEO) and poly(butadiene-b-ethylene oxide) (PBd-PEO) are two block copolymers which separately form vesicles with disparate membrane permeabilities and fluidities. Thus, hybrid vesicles formed from both PDMS-PEO and PBd-PEO may ultimately allow for systematic, application-specific tuning of vesicle membrane fluidity and permeability. However, given the relatively low strength previously noted for comb-type PDMS-PEO vesicles, the mechanical robustness of the resulting hybrid vesicles must first be confirmed. Toward this end, we have characterized the mechanical behavior of vesicles formed from mixtures of linear PDMS-PEO and linear PBd-PEO using micropipette aspiration. Tension versus strain plots of pure PDMS12-PEO46 vesicles revealed a non-linear response in the high tension regime, in contrast to the approximately linear response of pure PBd33-PEO20 vesicles. Remarkably, the area expansion modulus, critical tension, and cohesive energy density of PDMS12-PEO46 vesicles were each significantly greater than for PBd33-PEO20 vesicles, although critical strain was not significantly different between these vesicle types. PDMS12-PEO46/PBd33-PEO20 hybrid vesicles generally displayed graded responses in between that of the pure component vesicles. Thus, the PDMS12-PEO46/PBd33-PEO20 hybrid vesicles retained or exceeded the strength and toughness characteristic of pure PBd-PEO vesicles, indicating that future assessment of the membrane permeability and fluidity of these hybrid vesicles may be warranted. PMID:26999148

  1. Self-Organization and Vesicle Formation of Amphiphilic Fulleromonodendrons Bearing Oligo(poly(ethylene oxide)) Chains.

    PubMed

    Chen, Mengjun; Zhu, Hongxia; Zhou, Shengju; Xu, Wenlong; Dong, Shuli; Li, Hongguang; Hao, Jingcheng

    2016-03-15

    A new series of N-methylfulleropyrrolidines bearing oligo(poly(ethylene oxide))-appended Percec monodendrons (fulleromonodendrons, 4a-f) have been synthesized. The substituted position of the oligo(poly(ethylene oxide)) chain(s) on the phenyl group of the Percec monodendron for 4a-f was varied, which is at the 4-, 2,4-, 3,5-, 3,4,5-, 2,3,4- and 2,4,6- position, respectively. 4a-e are obtained as solids at 25 °C and can self-organize into lamellar phases as revealed by X-ray diffraction (XRD) and small-angle X-ray scattering (SAXS) measurements, while 4f appears as a viscous liquid. The substitution patterns of the oligo(poly(ethylene oxide)) chain(s) also significantly influence the solubility of 4a-f, especially in ethanol and water. Formation of self-organized supramolecular structures of 4d and 4e in water as well as 4d in ethanol is evidenced from UV-vis and dynamic light scattering (DLS) measurements. Further studies in water using various imaging techniques including transmission electron microscopy (TEM), freeze-fracture TEM (FF-TEM), cryo-TEM and atomic force microscopy (AFM) observations revealed the formation of well-defined vesicles for 4d and plate-like aggregates for 4e, indicating that the aggregation behavior of the fulleromonodendrons is highly dependent on their molecular structures. For 4d in ethanol, only irregular aggregates were noticed, indicating the solvent also plays a role on regulating the aggregation behavior. After functionalization with the Percec monodendrons, 4a-f can preserve the intriguing electrochemical properties of pristine C60 as revealed by cyclic voltammetries. The thermotropic properties of 4a-f have also been investigated. It was found that all of them show good thermal stability, but no mesophases were detected within the investigated temperature ranges. PMID:26898216

  2. Comparison of methanol and ethylene glycol oxidation by alloy and Core-Shell platinum based catalysts

    NASA Astrophysics Data System (ADS)

    Kaplan, D.; Burstein, L.; Rosenberg, Yu.; Peled, E.

    2011-10-01

    Two Core-Shell, RuCore-PtShell and IrNiCore-PtRuShell, XC72-supported catalyst were synthesized in a two-step deposition process with NaBH4 as reducing agent. The structure and composition of the Core-Shell catalysts were determined by EDS, XPS and XRD. Electrochemical characterization was performed with the use of cyclic voltammetry. Methanol and ethylene glycol oxidation activities of the Core-Shell catalysts (in terms of surface and mass activities) were studied at 80 °C and compared to those of a commercial Pt-Ru alloy catalyst. The surface activity of the alloy based catalyst, in the case of methanol oxidation, was found to be superior as a result of optimized surface Pt:Ru composition. However, the mass activity of the PtRu/IrNi/XC72 was higher than that of the alloy based catalyst by ∼50%. Regarding ethylene glycol oxidation, while the surface activity of the alloy based catalyst was slightly higher than that of the Pt/Ru/XC72 catalyst, the latter showed ∼66% higher activities in terms of A g-1 of Pt. These results show the potential of Core-Shell catalysts for reducing the cost of catalysts for DMFC and DEGFC.

  3. Poly(isophthalic acid)(ethylene oxide) as a Macromolecular Modulator for Metal-Organic Polyhedra.

    PubMed

    Chen, Teng-Hao; Wang, Le; Trueblood, Jonathan V; Grassian, Vicki H; Cohen, Seth M

    2016-08-01

    A new strategy was developed by using a polymer ligand, poly(isophthalic acid)(ethylene oxide), to modulate the growth of metal-organic polyhedra (MOP) crystals. This macromolecular modulator can effectively control the crystal habit of several different Cu24L24 (L = isophthalic acid derivatives) MOPs. The polymer also directed the formation of MOP structures under reaction conditions that only produce metal-organic frameworks in the absence of modulator. Moreover, the polymer also enabled the deposition of MOP crystals on glass surfaces. This macromolecular modulator strategy provides an innovative approach to control the morphology and assembly of MOP particles. PMID:27400759

  4. Synthesis and Properties of Highly Dispersed Ionic Silica–Poly(ethylene oxide) Nanohybrids

    PubMed Central

    2013-01-01

    We report an ionic hybrid based on silica nanoparticles as the anion and amine-terminated poly(ethylene oxide) (PEO) as a cation. The charge on the nanoparticle anion is carried by the surface hydroxyls. SAXS and TEM reveal an exceptional degree of dispersion of the silica in the polymer and high degree of order in both thin film and bulk forms. In addition to better dispersion, the ionic hybrid shows improved flow characteristics compared to silica/PEO mixtures in which the ionic interactions are absent. PMID:23351113

  5. Extrusion of polysaccharide nanocrystal reinforced polymer nanocomposites through compatibilization with poly(ethylene oxide).

    PubMed

    Pereda, Mariana; El Kissi, Nadia; Dufresne, Alain

    2014-06-25

    Polysaccharide nanocrystals with a rodlike shape but with different dimensions and specific surface area were prepared from cotton and capim dourado cellulose, and with a plateletlike morphology from waxy maize starch granules. The rheological behavior of aqueous solutions of poly(ethylene oxide) (PEO) with different molecular weights when adding these nanoparticles was investigated evidencing specific interactions between PEO chains and nanocrystals. Because PEO also bears hydrophobic moieties, it was employed as a compatibilizing agent for the melt processing of polymer nanocomposites. The freeze-dried mixtures were used to prepare nanocomposite materials with a low density polyethylene matrix by extrusion. The thermal and mechanical behavior of ensuing nanocomposites was studied. PMID:24840363

  6. Morphological, rheological and electrochemical studies ofpoly(ethylene oxide) electrolytes containing fumed silicananoparticles

    SciTech Connect

    Xie, Jiangbing; Kerr, John B.; Duan, Robert G.; Han, Yongbong

    2003-06-01

    In this paper, the rheology and crystallization of composite Poly(Ethylene Oxide) (PEO) electrolytes were studied by dynamic mechanical analysis, DSC and polarized light microscopy. The effects of fumed silica nanoparticles on the conductivities of the polymer electrolytes at temperatures above and below their melting point were measured and related to their rheology and crystallization behavior, respectively. The electrolyte/electrode interfacial properties and cycling performances of the composite polymer electrolytes in Li/Li cells are also discussed. The measured electrochemical properties were found to depend heavily on the operational environments and sample processing history.

  7. Mutagenicity and cytotoxicity of ethylene oxide in the CHO/HGPRT system

    SciTech Connect

    Tan, E.L.; Cumming, R.B.; Hsie, A.W.

    1981-01-01

    Ethylene oxide (EO) is made on an industrial scale (2.5 billion pounds per year) and is used not only to prepare a number of commercially important compounds but also as a widely used fumigant to sterilize foodstuffs, textiles, and medical instruments. EO is an alkylating agent that has been shown to interact with proteins and nucleic acids and is mutagenic in a number of test systems, eg, rodents, bacteria, rice, and Drosophila. Reported is the cytotoxicity and mutagenicity of EO in a mammalian cel culture system, the Chinese hamster ovary cell/hypoxanthine-guanine phosphoribosyl transferase (CHO/HGPRT) system.

  8. Viscosity of copper oxide nanoparticles dispersed in ethylene glycol and water mixture

    SciTech Connect

    Namburu, Praveen K.; Kulkarni, Devdatta P.; Das, Debendra K.; Misra, Debasmita

    2007-11-15

    Nanofluids are new kinds of fluids engineered by dispersing nanoparticles in base fluids. This paper presents an experimental investigation of rheological properties of copper oxide nanoparticles suspended in 60:40 (by weight) ethylene glycol and water mixture. Nanofluids of particle volume percentage ranging from 0% to 6.12% were tested. The experiments were carried over temperatures ranging from -35 C to 50 C to demonstrate their applicability in cold regions. For the particle volume concentrations tested, nanofluids exhibited Newtonian behavior. An experimental correlation was developed based on the data, which relates viscosity with particle volume percent and the nanofluid temperature. (author)

  9. Nitric Oxide, Ethylene, and Auxin Cross Talk Mediates Greening and Plastid Development in Deetiolating Tomato Seedlings.

    PubMed

    Melo, Nielda K G; Bianchetti, Ricardo E; Lira, Bruno S; Oliveira, Paulo M R; Zuccarelli, Rafael; Dias, Devisson L O; Demarco, Diego; Peres, Lazaro E P; Rossi, Magdalena; Freschi, Luciano

    2016-04-01

    The transition from etiolated to green seedlings involves the conversion of etioplasts into mature chloroplasts via a multifaceted, light-driven process comprising multiple, tightly coordinated signaling networks. Here, we demonstrate that light-induced greening and chloroplast differentiation in tomato (Solanum lycopersicum) seedlings are mediated by an intricate cross talk among phytochromes, nitric oxide (NO), ethylene, and auxins. Genetic and pharmacological evidence indicated that either endogenously produced or exogenously applied NO promotes seedling greening by repressing ethylene biosynthesis and inducing auxin accumulation in tomato cotyledons. Analysis performed in hormonal tomato mutants also demonstrated that NO production itself is negatively and positively regulated by ethylene and auxins, respectively. Representing a major biosynthetic source of NO in tomato cotyledons, nitrate reductase was shown to be under strict control of both phytochrome and hormonal signals. A close NO-phytochrome interaction was revealed by the almost complete recovery of the etiolated phenotype of red light-grown seedlings of the tomato phytochrome-deficient aurea mutant upon NO fumigation. In this mutant, NO supplementation induced cotyledon greening, chloroplast differentiation, and hormonal and gene expression alterations similar to those detected in light-exposed wild-type seedlings. NO negatively impacted the transcript accumulation of genes encoding phytochromes, photomorphogenesis-repressor factors, and plastid division proteins, revealing that this free radical can mimic transcriptional changes typically triggered by phytochrome-dependent light perception. Therefore, our data indicate that negative and positive regulatory feedback loops orchestrate ethylene-NO and auxin-NO interactions, respectively, during the conversion of colorless etiolated seedlings into green, photosynthetically competent young plants. PMID:26829981

  10. [Discussion about the sampling positions of the bag-type infusion sets for single use in the ethylene oxide residues detection].

    PubMed

    Liu, Xing; Zheng, Dixin; Geng, Yuanyuan; Chen, Zheng

    2014-01-01

    This paper selects the bag-type infusion sets for single use as samples, which are produced by different manufacturers and based on the ethylene oxide sterilization. The ethylene oxide sterilization residues in different parts of samples are detected by colorimetric analysis. Combined the comparison of the ethylene oxide residues testing results in the different parts of the same sample with the actual situation in clinical use, more reasonable sampling positions are found to detect the ethylene oxide sterilization residues. The result of this experiment will play a guiding role in the detection of the actual samples. PMID:24839856

  11. Health-hazard evaluation report HETA 85-292-1811, Clark County Hospital, Jeffersonville, Indiana. [Ethylene oxide

    SciTech Connect

    Zey, J.N.; Elliott, L.; Mortimer, V.

    1987-07-01

    A request was received from Clark County Hospital located in Jeffersonville, Indiana to evaluate possible employee exposures to hazardous substances while working in the central-supply (CS) area. Symptoms expressed by workers included headaches, dizziness, mucous membrane irritation, vomiting, diarrhea, nose bleeds, fatigue, nervous problems, and respiratory difficulties. Workers had reported smelling a sweet odor at times. Air sampling yielded time-weighted average personal-exposure concentrations of 0.23 to 0.56 parts per million (ppm) for ethylene oxide with short-term exposures of 77 ppm in the cart-storage area. The OSHA standard was 1 ppm, and the NIOSH recommended criterion was 0.1 ppm of ethylene oxide. Hydrochloric acid concentrations in area air samples were less than 1.0 ppm; for chlorine gas, less than 0.2 ppm; for carbon monoxide, less than 5.0 ppm; and up to 700 ppm for carbon dioxide. The lack of a dedicated ethylene oxide exhaust and the existence of an overloaded exhaust system were noted. The authors conclude that a health hazard to workers from exposure to ethylene oxide existed. They recommend specific measures to reduce exposures to ethylene oxide, including design and installation of a proper ventilation system.

  12. Investigation of the micropolarity in reverse micelles of nonionic poly(ethylene oxide) surfactants using 4-nitropyridine-N-oxide as absorption probe.

    PubMed

    Bandula, Rodica; Vasilescu, Marilena; Lemmetyinen, Helge

    2005-07-15

    The micropolarities of the reverse micelle (RM) interior of nonionic poly(ethylene oxide) surfactants of the alkyl ether type (poly(ethylene oxide)[4] lauryl ether (C12E4, Brij 30)), alkyl-aryl ethers (poly(ethylene oxide)[4] nonylphenyl ether (C9PhiE4), poly(ethylene oxide)[5] nonylphenyl ether (C9PhiE5), and poly(ethylene oxide)[5] octylphenyl ether (C8PhiE5)), and poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymers (Pluronics P123, F127) were investigated as a function of the water content by applying the absorption probe technique, using 4-nitropyridine-N-oxide (NP) as a probe. The change in the micellar aggregate micropolarity in different solvents (cyclohexane, decane, n-butanol, and n-butyl acetate) at various water contents has been investigated. The research was focused on the determination of the effects of surfactant structure and solvent type on the hydration degrees of the PEO chains in the region at the core limit, where the NP probe was located. All results regarding the polarities in RM and PEO/water calibration mixtures have been expressed in terms of Kosower's Z values, using the linear dependence of E(NP) on Kosower's Z. The PPO/butanol mixtures have also been used for RM in butanol as a reference system. The data revealed that local polarity in RM is dependent on the surfactant type, block copolymer composition, solvent nature, and water content. At the same water content, the results clearly indicate a lower hydration degree of triblock copolymers, as compared to the surfactants of the alkyl ether and alkyl-aryl ether type, but for P123 and F127 Pluronics in n-butanol the hydration is higher owing to the behavior of butanol as cosurfactant and to its hydration. PMID:15925636

  13. Solubility of nano-zinc oxide in environmentally and biologically important matrices

    PubMed Central

    Reed, Robert B.; Ladner, David A.; Higgins, Christopher P.; Westerhoff, Paul; Ranville, James F.

    2011-01-01

    Increasing manufacture and use of engineered nanoparticles (NPs) is leading to a greater probability for release of ENPs into the environment and exposure to organisms. In particular, zinc oxide (ZnO) is toxic, although it is unclear whether this toxicity is due to the zinc oxide nanoparticles (ZnO), dissolution to Zn2+, or some combination thereof. The goal of this study was to determine the relative solubilites of both commercially available and in-house synthesized ZnO in matrices used for environmental fate and transport or biological toxicity studies. Dissolution of ZnO was observed in nanopure water (7.18– 7.40 mg/L dissolved Zn, as measured by filtration) and Roswell Park Memorial Institute medium (RPMI-1640) (~5 mg/L), but much more dissolution was observed in Dulbecco’s Modified Eagle’s Medium (DMEM), where the dissolved Zn concentration exceeded 34 mg/L. Moderately hard water exhibited low zinc solubility, likely due to precipitation of a zinc carbonate solid phase. Precipitation of a zinc-containing solid phase in RPMI also appeared to limit zinc solubility. Equilibrium conditions with respect to ZnO solubility were not apparent in these matrices, even after more than 1,000 h of dissolution. These results suggest that solution chemistry exerts a strong influence on ZnO dissolution and can result in limits on zinc solubility due to precipitation of less soluble solid phases. PMID:21994124

  14. Transient kinetic modeling of the ethylene and carbon monoxide oxidation over a commercial automotive exhaust gas catalyst

    SciTech Connect

    Harmsen, J.M.A.; Hoebink, J.H.B.J.; Schouten, J.C.

    2000-03-01

    The transient kinetics of ethylene oxidation by oxygen over a commercial Pt/Rh/CeO{sub 2}/{gamma}-Al{sub 2}O{sub 3} three-way catalyst were modeled. Experiments were carried out in a fixed-bed microreactor with two separate inlets, enabling alternate feeding of ethylene and oxygen with frequencies up to {1/4} Hz. The experimental conditions resemble the cold-start period of an Otto engine in a car. Two types of adsorbed ethylene species seem to exist. A selective catalyst deactivation for oxygen adsorption, due to deposition of carbonaceous species, was found. A kinetic model was developed, based on elementary reaction steps, that allows one to describe the experiments quantitatively. Furthermore, this model was combined with the published model for transient carbon monoxide oxidation over the same catalyst, which enables one to predict the results of simultaneous ethylene and carbon monoxide oxidation. Both components react in rather distinct zones, with ethylene being converted only when carbon monoxide oxidation is almost complete.

  15. Atomistic simulation of CO2 solubility in poly(ethylene oxide) oligomers

    NASA Astrophysics Data System (ADS)

    Hong, Bingbing; Panagiotopoulos, Athanassios Z.

    2014-06-01

    We have performed atomistic molecular dynamics simulations coupled with thermodynamic integration to obtain the excess chemical potential and pressure-composition phase diagrams for CO2 in poly(ethylene oxide) oligomers. Poly(ethylene oxide) dimethyl ether, CH3O(CH2CH2O)nCH3 (PEO for short) is a widely applied physical solvent that forms the major organic constituent of a class of novel nanoparticle-based absorbents. Good predictions were obtained for pressure-composition-density relations for CO2 + PEO oligomers (2 ≤ n ≤ 12), using the Potoff force field for PEO [J. Chem. Phys. 136, 044514 (2012)] together with the TraPPE model for CO2 [AIChE J. 47, 1676 (2001)]. Water effects on Henry's constant of CO2 in PEO have also been investigated. Addition of modest amounts of water in PEO produces a relatively small increase in Henry's constant. Dependence of the calculated Henry's constant on the weight percentage of water falls on a temperature-dependent master curve, irrespective of PEO chain length.

  16. Molecular dynamics simulations of silica nanoparticles grafted with poly(ethylene oxide) oligomer chains.

    PubMed

    Hong, Bingbing; Panagiotopoulos, Athanassios Z

    2012-03-01

    A molecular model of silica nanoparticles grafted with poly(ethylene oxide) oligomers has been developed for predicting the transport properties of nanoparticle organic-hybrid materials (NOHMs). Ungrafted silica nanoparticles in a medium of poly(ethylene oxide) oligomers were also simulated to clarify the effect of grafting on the dynamics of nanoparticles and chains. The model approximates nanoparticles as solid spheres and uses a united-atom representation for chains, including torsional and bond-bending interactions. The calculated viscosities from Green-Kubo relationships and temperature extrapolation are of the same order of magnitude as experimental data but show a smaller activation energy relative to real NOHMs systems. Grafted systems have higher viscosities, smaller diffusion coefficients, and slower chain dynamics than the ungrafted ones at high temperatures. At lower temperatures, grafted systems exhibit faster dynamics for both nanoparticles and chains relative to ungrafted systems, because of lower aggregation of particles and enhanced correlations between nanoparticles and chains. This agrees with the experimental observation that NOHMs have liquidlike behavior in the absence of a solvent. For both grafted and ungrafted systems at low temperatures, increasing chain length reduces the volume fraction of nanoparticles and accelerates the dynamics. However, at high temperatures, longer chains slow down nanoparticle diffusion. From the Stokes-Einstein relationship, it was determined that the coarse-grained treatment of nanoparticles leads to slip on the nanoparticle surfaces. Grafted systems obey the Stokes-Einstein relationship over the temperature range simulated, but ungrafted systems display deviations from it. PMID:22243140

  17. Specificity, accuracy, and interpretation of measurements of ethylene oxide gas concentrations during sterilization using a microwave spectrometer

    NASA Astrophysics Data System (ADS)

    Zhu, Z.; Matthews, I. P.; Dickinson, W.

    1997-07-01

    This article reports the update in the design of a microwave spectrometer for measuring concentrations of ethylene oxide gas during sterilization. The specificity of the measurement (absorption line at 23.134 GHz) using the spectrometer has been found to be virtually 100%. A great number of calibrations have been conducted in the range of concentrations 100% to 40% of ethylene oxide gas at intervals of -10% in order to determine the accuracy of the spectrometer. It was found that the maximum standard deviation from the regression curve was 1.2% full scale (0%-100%). A mathematical model based on a diffusion equation has been developed and was used to interpret the real time measurement data during sterilization. Numerical simulation using this model has demonstrated that it is possible to predict the dynamic distributions of ethylene oxide concentration within the load being sterilized.

  18. On the elastic properties of single-walled carbon nanotubes/poly(ethylene oxide) nanocomposites using molecular dynamics simulations.

    PubMed

    Rouhi, S; Alizadeh, Y; Ansari, R

    2016-01-01

    Molecular dynamics simulations are used to study the physical and mechanical properties of single-walled carbon nanotubes/poly(ethylene oxide) nanocomposites. The effects of nanotube atomic structure, diameter, and volume fraction on the polymer density distribution, polymer atom distribution, stress-strain curves of nanocomposites and Young's, and shear moduli of single-walled carbon nanotubes/poly(ethylene oxide) nanocomposites are explored. It is shown that the density of polymer, surrounding the nanotube surface, has a peak near the nanotube surface. However, increasing distance leads to dropping it to the value near the density of pure polymer. It is seen that for armchair nanotubes, the average polymer atoms distances from the single-walled carbon nanotubes are larger than the polymer atom distance from zigzag nanotubes. It further is shown that zigzag nanotubes are better candidates to reinforce poly (ethylene oxide) than their armchair counterparts. PMID:26791535

  19. Poly(ethylene oxide)-sodium polyiodide conductors: characterization, electrical conductivity, and photoresponse

    SciTech Connect

    Hardy, L.C.; Shriver, D.F.

    1986-05-28

    The complexes of poly(ethylene oxide) with sodium polyiodide are electronic conductors. The level of conductivity at room temperature is 2 to 3 orders of magnitude greater than that of simple quaternary ammonium polyiodide salts. Raman spectroscopy indicates that the polyiodide species formed in the polymeric material depends upon the salt concentration in the polymer as well as the iodine to sodium ion ratio. High conductivity is associated with the appearance of a polyiodide species having a resonance-enhanced Raman feature at ca. 171 cm/sup -1/. A photovoltaic effect is observed when the polyiodide-containing polymer is sandwiched between indium-tin oxide glass and platinum electrodes and then illuminated through the ITO. The sign of the photoinduced potential indicates that the photovoltaic effect arises from a recombination of electrons from ITO with holes in the polyiodide valance bond.

  20. Protein nanorings organized by poly(styrene-block-ethylene oxide) self-assembled thin films

    NASA Astrophysics Data System (ADS)

    Malmström, Jenny; Wason, Akshita; Roache, Fergus; Yewdall, N. Amy; Radjainia, Mazdak; Wei, Shanghai; Higgins, Michael J.; Williams, David E.; Gerrard, Juliet A.; Travas-Sejdic, Jadranka

    2015-11-01

    This study explores the use of block copolymer self-assembly to organize Lsmα, a protein which forms stable doughnut-shaped heptameric structures. Here, we have explored the idea that 2-D crystalline arrays of protein filaments can be prepared by stacking doughnut shaped Lsmα protein into the poly(ethylene oxide) blocks of a hexagonal microphase-separated polystyrene-b-polyethylene oxide (PS-b-PEO) block copolymer. We were able to demonstrate the coordinated assembly of such a complex hierarchical nanostructure. The key to success was the choice of solvent systems and protein functionalization that achieved sufficient compatibility whilst still promoting assembly. Unambiguous characterisation of these structures is difficult; however AFM and TEM measurements confirmed that the protein was sequestered into the PEO blocks. The use of a protein that assembles into stackable doughnuts offers the possibility of assembling nanoscale optical, magnetic and electronic structures.This study explores the use of block copolymer self-assembly to organize Lsmα, a protein which forms stable doughnut-shaped heptameric structures. Here, we have explored the idea that 2-D crystalline arrays of protein filaments can be prepared by stacking doughnut shaped Lsmα protein into the poly(ethylene oxide) blocks of a hexagonal microphase-separated polystyrene-b-polyethylene oxide (PS-b-PEO) block copolymer. We were able to demonstrate the coordinated assembly of such a complex hierarchical nanostructure. The key to success was the choice of solvent systems and protein functionalization that achieved sufficient compatibility whilst still promoting assembly. Unambiguous characterisation of these structures is difficult; however AFM and TEM measurements confirmed that the protein was sequestered into the PEO blocks. The use of a protein that assembles into stackable doughnuts offers the possibility of assembling nanoscale optical, magnetic and electronic structures. Electronic supplementary

  1. Type I allergic hypersensitivity reactions due to ethylene oxide sterilised leucocyte filters in patients with thalassaemia: report of four cases.

    PubMed

    Belen, Burcu; Polat, Meltem

    2015-01-01

    Ethylene oxide (EO) is a highly reactive gas used in sterilisation of heat sensitive medical devices, such as infusion sets, cannulae, intubation materials, ventriculoperitoneal shunts, dialysis catheters and stents. Allergic reactions due to EO have been reported in haemodialysis patients, patients undergoing extracorporeal photopheresis and donors of plasmapheresis. Clinical manifestations vary considerably and generally do not allow differentiation between IgE-mediated anaphylaxis and anaphylactoid reactions. We report four patients with thalassaemia who experienced anaphylaxis during transfusion due to ethylene oxide sterilised leucocyte filters. The aim of this report is to highlight the fact that frequently transfused patients can have allergic reactions due to EO particles left in leucocyte filters. PMID:25725028

  2. New Aptes Cross-linked Polymers from Poly(ethylene oxide)s and Cyanuric Chloride for Lithium Batteries

    NASA Technical Reports Server (NTRS)

    Tigelaar, Dean M.; Meador, Mary Ann B.; Kinder, James D.; Bennett, William R.

    2005-01-01

    A new series of polymer electrolytes for use as membranes for lithium batteries are described. Electrolytes were made by polymerization between cyanuric chloride and diamino-terminated poly(ethylene oxide)s, followed by cross-linking via a sol-gel process. Thermal analysis and lithium conductivity of freestanding polymer films were studied. The effects of several variables on conductivity were investigated, such as length of backbone PEO chain, length of branching PEO chain, extent of branching, extent of cross-linking, salt content, and salt counterion. Polymer films with the highest percentage of PEO were found to be the most conductive, with a maximum lithium conductivity of 3.9 x 10(exp -5) S/cm at 25 C. Addition of plasticizer to the dry polymers increased conductivity by an order of magnitude.

  3. Poly(ethylene glycol) dicarboxylate/poly(ethylene oxide) hydrogel film co-crosslinked by electron beam irradiation as an anti-adhesion barrier.

    PubMed

    Haryanto; Singh, Deepti; Han, Sung Soo; Son, Jun Hyuk; Kim, Seong Cheol

    2015-01-01

    The cross-linked poly(ethylene glycol) dicarboxylate (PEGDC)/poly(ethylene oxide) (PEO) and poly(ethylene glycol) dimethacrylate (PEGDMA)/(PEO) hydrogels were developed for possible biomedical applications such as an anti-adhesion barrier. Various contents of PEGDC/PEO film were irradiated using an electron beam with various beam intensities in order to obtain various degrees of crosslinked hydrogels. The optimum dose (300 kGy) and total crosslinker content of 10% were used to prepare crosslinked hydrogel films with three different compositions (10% PEGDC, 10% PEGDMA, 5% PEGDC-5% PEGDMA). Among them, 10% PEGDC hydrogel film exhibited the highest elongation at break (69.33±6.87%) with high mechanical strength. 10% PEGDC hydrogel film showed the lowest hemolysis activity (6.03±0.01%) and the highest tissue adherence (75.67±1.15 cN). The result also indicated that the carboxyl groups in PEGDC affect the tissue adherence of hydrogel films via H-bonding interactions. In animal studies, 10% PEGDC anti-adhesion hydrogel film degraded within 3 weeks and demonstrated better anti-adhesive effect compared to Guardix-SG®. PMID:25491977

  4. 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.

  5. Ethylene oxide's role as a reactive agent during sterilization: effects of polymer composition and device architecture.

    PubMed

    Phillip, Edward; Murthy, N Sanjeeva; Bolikal, Durgadas; Narayanan, Pallassana; Kohn, Joachim; Lavelle, Linda; Bodnar, Stanko; Pricer, Kurt

    2013-05-01

    Sterilization conditions need to be optimized to effectively neutralize the bioburden while using short exposure times for minimizing the changes in chemical composition, material properties and device architecture. Towards this goal, effects of ethylene oxide (EtO) exposure parameters such as time, temperature, humidity, and EtO concentration on the polymer properties were investigated by monitoring the changes in composition, and the morphology of different types of structures in a family of poly(ethylene glycol) (PEG)-containing tyrosine-derived polycarbonates. EtO was found to esterify the carboxyl groups present in the desaminotyrosyl-tyrosine groups. Sterilization under conditions more severe than those normally used reduced the glass transition temperature (Tg) and the molecular weight of the polymers, and the presence of PEG in the polymer enhanced this effect. Furthermore, electron micrographs showed that EtO sterilization cycle conditions, even those considered "mild," were found to damage the fragile structures such as those found in electrospun mats and porous scaffolds. Our study shows that the presence of EtO-susceptible groups, fusible architecture, and surface morphology should be taken into account in choosing the appropriate EtO sterilization conditions. PMID:23296710

  6. Health-hazard evaluation report HETA-87-207-1845, University of Colorado, Health Science Center, Denver, Colorado. [Ethylene oxide exposure

    SciTech Connect

    Nichting, A.T.; Hales, T.R.; Gunter, B.J.

    1987-10-01

    A study of possible hospital employee exposure to ethylene oxide was undertaken. Employees had complained of headaches and possible neurological problems. A personal breathing-zone sample collected from the sterilizer operator showed levels of ethylene oxide at the limit of quantitation, 0.02mg/cu m. In sterilizer and mechanical-access-room samples, ethylene oxide was detected ranging up to 0.2mg/cu m levels. The authors conclude that a potential for exposure to ethylene oxide exists for workers in the sterilizer room. The authors recommend that efforts be continued to keep ethylene oxide levels as low as possible and to check for possible leaks in the system. Effective ventilation controls should be established, and a warning system should be installed in the mechanical access room. Respirators, protective clothing, training for employees, safety meetings, and medical evaluations for personnel were all included in the recommendations following the investigation.

  7. EFFECTS OF CHEMICAL PROCESSING AND OXIDE ETHYLENE STERILIZATION ON CORTICAL AND CANCELLOUS RAT BONE: A LIGHT AND ELECTRON SCANNING MICROSCOPY STUDY

    PubMed Central

    Castiglia, Marcello Teixeira; da Silva, Juliano Voltarelli F.; Frezarim Thomazini, José Armendir; Volpon, José Batista

    2015-01-01

    To evaluate, under microscopic examination, the structural changes displayed by the trabecular and cortical bones after being processed chemically and sterilized by ethylene oxide. Methods: Samples of cancellous and cortical bones obtained from young female albinus rats (Wistar) were assigned to four groups according to the type of treatment: Group I- drying; Group II- drying and ethylene oxide sterilization; III- chemical treatment; IV- chemical treatment and ethylene oxide sterilization. Half of this material was analyzed under ordinary light microscope and the other half using scanning electron microscopy. Results: In all the samples, regardless the group, there was good preservation of the general morphology. For samples submitted to the chemical processing there was better preservation of the cellular content, whereas there was amalgamation of the fibres when ethylene oxide was used. Conclusion: Treatment with ethylene oxide caused amalgamation of the fibers, possibly because of heating and the chemical treatment contributed to a better cellular preservation of the osseous structure. PMID:26998450

  8. Stability and aggregation of metal oxide nanoparticles in natural aqueous matrices.

    PubMed

    Keller, Arturo A; Wang, Hongtao; Zhou, Dongxu; Lenihan, Hunter S; Cherr, Gary; Cardinale, Bradley J; Miller, Robert; Ji, Zhaoxia

    2010-03-15

    There is a pressing need for information on the mobility of nanoparticles in the complex aqueous matrices found in realistic environmental conditions. We dispersed three different metal oxide nanoparticles (TiO(2), ZnO and CeO(2)) in samples taken from eight different aqueous media associated with seawater, lagoon, river, and groundwater, and measured their electrophoretic mobility, state of aggregation, and rate of sedimentation. The electrophoretic mobility of the particles in a given aqueous media was dominated by the presence of natural organic matter (NOM) and ionic strength, and independent of pH. NOM adsorbed onto these nanoparticles significantly reduces their aggregation, stabilizing them under many conditions. The transition from reaction to diffusion limited aggregation occurs at an electrophoretic mobility from around -2 to -0.8 microm s(-1) V(-1) cm. These results are key for designing and interpreting nanoparticle ecotoxicity studies in various environmental conditions. PMID:20151631

  9. Effects of Silica Nanostructures in Poly(ethylene oxide)-Based Composite Polymer Electrolytes.

    PubMed

    Mohanta, Jagdeep; Anwar, Shahid; Si, Satyabrata

    2016-06-01

    The present work describes the synthesis of some poly(ethylene oxide)-based nanocomposite polymer electrolyte films using various silica nanostructures as the inorganic filler by simple solution mixing technique, in which the nature of the silica nanostructures play a vital role in modulating their electrochemical performances at room temperature. The silica nanostructures are prepared by ammonical hydrolysis of tetraethyl orthosilicate following the modified St6ber method. The resulting films are characterized by X-ray diffraction and differential scanning calorimeter to study their crystallinity. Room temperature AC impedance spectroscopy is utilized to determine the Li+ ion conductivity of the resulting films. The observed conductivity values of various NCPE films depend on the nature of silica filling as well as on their surface characteristics and also on the varying PEO-Li+ ratio, which is observed to be in the order of 10(-7)-10(-6) S cm(-1). PMID:27427686

  10. Effect of molecular weight on ion diffusion and transference number in poly(ethylene oxide)

    NASA Astrophysics Data System (ADS)

    Timachova, Ksenia; Balsara, Nitash

    2015-03-01

    Solid polymer electrolytes are of great interest for their potential use in high specific energy, solid-state batteries, however, salt transport properties in polymer electrolytes have not been comprehensively addressed over a wide range of molecular weights. Poly(ethylene oxide) (PEO) has been the most widely studied polymer electrolyte due to its high solvation of lithium salts and low glass transition temperature. This study presents measurements of the transport properties of lithium bis(trifluoromethanesulfone)imide (LiTFSI) in PEO at both the high concentration present in functional electrolytes and in the dilute limit for a large range of PEO molecular weights. Individual diffusion coefficients of the Li + and TFSI- ions were measured using pulsed-field gradient nuclear magnetic resonance and the cation transference number was calculated. The diffusion coefficients, transference number, and conductivity as a function of molecular weight and salt concentration provide a complete set of transport properties for PEO.

  11. SHI induced modification in structural, optical, dielectric and thermal properties of poly ethylene oxide films

    NASA Astrophysics Data System (ADS)

    Patel, Gnansagar B.; Bhavsar, Shilpa; Singh, N. L.; Singh, F.; Kulriya, P. K.

    2016-07-01

    Poly ethylene oxide (PEO) films were synthesized by solution cast method. These self-standing films were exposed with 60 MeV C+5 ion and 100 MeV Ni+7 ion at different fluences. SHI induced effect was investigated by employing various techniques. The crystalline size decreased upon irradiation as observed from XRD analysis. FTIR analysis reveals the decrement in the peak intensity upon irradiation. Tauc's method was used to determine the optical band gap (Eg), which shows decreasing trends with increase of fluence. The dielectric properties were investigated in the frequency range 10 Hz to 10 MHz for unirradiated and irradiated films. The dielectric constant remains same for the broad-spectrum of frequency and increases at lower frequency. The dielectric loss also moderately influence as a function of frequency due to irradiation. DSC analysis validated the results of XRD. Scanning electron microscopy (SEM) reveals that there is significant change in the surface morphology due to irradiation.

  12. Antibacterial effects of electrospun chitosan/poly(ethylene oxide) nanofibrous membranes loaded with chlorhexidine and silver.

    PubMed

    Song, Jiankang; Remmers, Stefan J A; Shao, Jinlong; Kolwijck, Eva; Walboomers, X Frank; Jansen, John A; Leeuwenburgh, Sander C G; Yang, Fang

    2016-07-01

    To prevent percutaneous device associated infections (PDAIs), we prepared electrospun chitosan/poly(ethylene oxide) (PEO) nanofibrous membrane containing silver nanoparticles as an implantable delivery vehicle for the dual release of chlorhexidine and silver ions. We observed that the silver nanoparticles were distributed homogeneously throughout the fibers, and a fast release of chlorhexidine in 2days and a sustained release of silver ions for up to 28days. The antibacterial efficacy of the membranes against Staphylococcus aureus showed that the membranes exhibited an obvious inhibition zone upon loading with either chlorhexidine (20μg or more per membrane) or AgNO3 (1 and 5wt% to polymer). Furthermore, long-term antibacterial effect up to 4days was verified using membranes containing 5wt% AgNO3. The results suggest that the membranes have strong potential to act as an active antibacterial dressing for local delivery of antibacterial agents to prevent PDAIs. PMID:26970025

  13. Study on thermodynamics and oxidation mechanism of ethylene glycol in the preparation of nanometer nickel powders

    SciTech Connect

    Jin Shengming . E-mail: shmjin@mail.csu.edu.cn; Yuan Liangsheng; Zhou Ying; Qiu Guanzhou; Wan Cuifeng

    2006-11-09

    Nanometer nickel powders have been prepared using the polyol method with NaOH, Ni(NO{sub 3}){sub 2}.6H{sub 2}O, ethylene glycol (EG), and polyvinylpyrrolidone (PVP) as raw materials. The thermodynamics of the reaction system was studied, and the E-pH diagram of Ni-EG-H{sub 2}O was plotted. The oxidation products of EG were predicted from the E-pH diagram, and CO{sub 3} {sup 2-} in alkaline solutions was identified as the product through the IR spectrum and CaCO{sub 3} sediment. Field-emission scanning electron micrograph (FE-SEM) showed that spherical nanometer nickel powders were obtained.

  14. Phase Behavior of a Poly(ethylene oxide)-Poly(ethylethylene)/Water/Dodecane System

    NASA Astrophysics Data System (ADS)

    Kossuth, M. B.; Bates, F. S.

    1998-03-01

    Recently, we investigated the phase behavior of a series of low molecular weight poly(ethylene oxide)-poly(ethylethylene) (PEO-PEE) block copolymers in the presence of water (D.A. Hajduk, M.B. Kossuth, M.A. Hillmyer, and F.S. Bates, submitted to J. Phys. Chem. B). These molecules are chemically similar to the C_nEOm surfactants but have molecular weights roughly an order of magnitude greater. PEO is hydrophilic, while PEE is strongly hydrophobic. Current work involves the addition of a third component, dodecane, to create a ternary surfactant/water/oil system. The phase behavior of this system will be discussed and compared to that of chemically similar small molecule surfactants. Noteworthy results include the appearance of a bicontinuous cubic phase, which was not seen in the aqueous solutions, and the relative sizes of the phase windows.

  15. [Recommendation for validation and routine monitoring of sterilization processes with ethylene oxide for medical devices].

    PubMed

    Jakimiak, B; Röhm-Rodowald, E

    1999-01-01

    The European Medical Device Directives specifically address sterilization issues in a number of instances. The European Standards for sterilization of medical devices, especially EN 550, EN 554, EN 556 regulate the manufacture, installation and operation of sterilizers as well as the validation of sterilization processes, on using ethylene oxide (EN 550) or moist heat (EN 554) for sterilization. This recommendation is intended as a source of information for conducting validation according to EN 550 and concomitantly for ensuring that the medical devices reprocessed (cleaned, disinfected, packed, sterilized, stored) in the hospital setting or in other healthcare establishments are endowed with the same level of safety with respect to sterility as that of industrially produced and marketed sterile medical devices. PMID:10474298

  16. [Cytotoxicity of PVC tubes sterilized in ethylene oxide after gamma radiation exposure].

    PubMed

    de Souza, Rafael Queiroz; Graziano, Kazuko Uchikawa; Ikeda, Tamiko Ichikawa; Gonçalves, Cláudia Regina; Cruz, Aurea Silveira

    2013-04-01

    Do materials sterilized using gamma rays become toxic when re-sterilized in ethylene oxide? This question guided the objective of this study, which was to investigate the potential cytotoxic effect of PVC sterilized by gamma radiation and re-sterilized with EO by the agar diffusion method in cell cultures. Nine PVC tubes were subjected to gamma radiation sterilization and were re-sterilized in EO. The tubes were divided into a total of 81 units of analysis that were tested so as to represent the internal and external surfaces and mass of each tube. It was concluded that the PVC materials sterilized in gamma radiation and re-sterilized in EO are not cytotoxic. PMID:23743920

  17. CO2 permeation through poly(amide-6-b-ethylene oxide)-nanosilica membranes

    NASA Astrophysics Data System (ADS)

    Lovineh, Shirin Gh.; Asghari, Morteza; Khanbabaei, Ghader

    2014-11-01

    The organic-inorganic hybrids of poly(amide-6-b-ethylene oxide) (PEBA) and silica utilizing aminopropyltriethoxysilane (APTES) as precursor was prepared via sol-gel process and was compared with neat PEBA. The nanodispersed inorganic network produced in the organic matrix was structurally characterized using Fourier transform infrared (FT-IR) that revealed the existence of different chemical groups corresponding to the silica precursors. The single gas permeability was carried out for neat PEBA and PEBA-nano silica (10 wt.% precursor) membranes. CO2 permeability for the neat polymer membrane was higher than the nano-composite membrane and increased with pressure. Adding 10 wt.% of nanosilica filler into the polymeric matrix caused CO2 permeability to decrease.

  18. Poly(ethylene oxide)/clay nanaocomposites: Thermal and mechanical properties

    NASA Astrophysics Data System (ADS)

    Ejder-Korucu, Mehtap; Gürses, Ahmet; Karaca, Semra

    2016-08-01

    Poly(ethylene oxide) (PEO)/clay nanocomposites were prepared by a solution intercalation method using chloroform as a solvent. The nanocomposites were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR) and also investigation of some mechanical properties of the composites. Formation of nanocomposite was confirmed by XRD analysis. The increasing tendency of exfoliation degree with an increase in clay content may be attributed to easier diffusion of PEO chains to interlayer regions. An increase in PEO crystallinity in case of nanocomposite, was confirmed by an increase in the heat of melting as indicated by DSC. Improvement in tensile properties in all respect was observed for nanocomposites with clay content.

  19. Effects of temperature and relative humidity on biological indicators used for ethylene oxide sterilization.

    PubMed Central

    Oxborrow, G S; Placencia, A M; Danielson, J W

    1983-01-01

    A study was made to determine the effects of temperature and moisture on the D-value of a common biological indicator. Relative humidity (RH) was varied between 10 and 70% in increments of 10%, and temperature was varied between 30 and 70 degrees C in increments of 10 degrees C. Temperature was found to have a pronounced effect on the D-value. At 60% RH, the D-value varied from 15.0 min at 30 degrees C to 1.1 min at 70 degrees C. When RH was plotted against the average D-value at the various temperatures, the temperature curves at or above 50 degrees C were more erratic and the RH had a significant effect. The study showed that temperature and RH must be controlled if biological indicators are to be properly calibrated for use in ethylene oxide sterilization. PMID:6402979

  20. Structural conformation in a poly (ethylene oxide) film obta inedfrom X-ray emission spectroscopy (XES)

    SciTech Connect

    Kashtanov, S.; Zhuang, G.V.; Augustsson, A.; Guo, J.-H.; Nordgren, J.; Luo, Y.; Ross, P.N.

    2007-03-16

    The electronic structure of poly(ethylene oxide) (PEO) in a thin (< 1 {micro}) film sample was experimentally probed by X-ray emission spectroscopy. The emission spectra from this film were much sharper with more resolved fine structure than the spectra from the bulk polymer from which it was cast. Both non-resonant and resonant X-ray emission spectra were simulated using density functional theory (DFT) applied to four different models representing different conformations in the polymer. Calculated spectra were compared with experimental results for the PEO film. It was found that the best fit was obtained with the polymer conformation in PEO electrolytes from which the salt (LiMF6, M=P, As, or Sb) had been removed. This conformation is different from that in the crystalline bulk polymer and implies that film casting, commonly used to form electrolytes for Li polymer batteries, induces the same conformation in the polymer with or without the salt present.

  1. Facile synthesis of porous worm-like Pd nanotubes with high electrocatalytic activity and stability towards ethylene glycol oxidation.

    PubMed

    Feng, Jiu-Ju; Zhou, Dan-Ling; Xi, Huan-Xiang; Chen, Jian-Rong; Wang, Ai-Jun

    2013-08-01

    A facile method was developed for large-scale preparation of porous worm-like Pd nanotubes based on the reduction of PdO nanotubes, which were obtained by calcining the complex precipitate of [Pd(dimethylglyoxime)2]n. The Pd catalyst showed excellent electrocatalytic activity and stability towards ethylene glycol oxidation. PMID:23817778

  2. 78 FR 44117 - Notice of a Public Comment Period on the Draft IRIS Carcinogenicity Assessment for Ethylene Oxide

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-23

    ... Carcinogenicity of Ethylene Oxide'' (EPA/635/R-13/128a) and on the draft peer review charge questions. The draft assessment and draft peer review charge questions were prepared by the National Center for Environmental... review charge questions begins on the day EPA posts the draft assessment and the draft peer review...

  3. Photolysis of CpRe(CO){sub 3} and CpM(CO){sub 4}, where M = Nb and Ta, in nujol matrices and supercritical ethylene. An unexpected ethylene polymerization catalyst

    SciTech Connect

    Bitterwolf, T.E.; Bays, J.T.; Gallagher, S.; Linehan, J.C.; Yonker, C.R.

    1997-12-31

    Nujol matrix photochemical studies of CpRe(CO){sub 3} establish the primary photochemical event to be loss of carbon monoxide to form an electron deficient species. CpM(CO){sub 4}, where M = Nb or Ta, give both CpM(CO){sub 3} and CpM(CO){sub 2} species upon photolysis in the Nujol matrix. Upon photolysis of these compounds in supercritical ethylene, IR bands associated with CpM(CO){sub n-1}(ethylene) are observed as well as bands associated with CpM(CO){sub n-2}(ethylene){sub 2}. White precipitate, formed under photochemical conditions, has been shown to be polyethylene.

  4. Durability of amide N-chloramine biocides to ethylene oxide sterilization.

    PubMed

    Zhao, Nan; Logsetty, Sarvesh; Liu, Song

    2012-01-01

    The objective of this work is to study the stability of three novel topical antimicrobial dressings consisting of amide N-chloramine structures against ethylene oxide sterilization. Cotton gauze samples bonded with one of three amide N-chloramine structures were subjected to standard ethylene oxide (EtO) sterilization. The amounts of amide N-chloramine structures before and after the sterilization were quantified to indicate the stabilities of these amide N-chloramine structures to the sterilization. The samples after sterilization were challenged with a clinical isolate of healthcare-associated multidrug-resistant Escherichia coli. N-Chloramine structure converted from polymethacrylamide (dressing 2) had the highest durability (89.7% retained active chlorine) toward EtO sterilization; that from hydantoin (dressing 3; 86.3% retained active chlorine) followed; and poly(N-chloroacrylamide) (dressing 1) had the lowest (64.0% retained active chlorine). After EtO sterilization, all the samples still reduced E. coli presence at 5 minutes of contact, with dressing 2 retaining a log 6 reduction. The three tested amide N-chloramine structures could all survive EtO sterilization while retaining percentages of active chlorine ranging from 64.0 to 89.7%. Dressing 2 showed the best durability, whereas dressing 1 had the poorest durability. With the remaining amounts of amide N-chloramine structures after EtO sterilization, all the dressings could still reduce E. coli numbers within 5 minutes of contact, and dressing 2 resulted in a log 6 reduction in colony count. PMID:22157019

  5. Atmospheric chemistry of toxic contaminants 2. Saturated aliphatics: Acetaldehyde, dioxane, ethylene glycol ethers, propylene oxide

    SciTech Connect

    Grosjean, D. )

    1990-11-01

    Detailed mechanisms are outlined for the chemical reactions that contribute to in-situ formation and atmospheric removal of the saturated aliphatic contaminants acetaldehyde, dioxane, ethylene glycol ethers (methyl, ethyl, n-butyl) and propylene oxide. In-situ formation is of major importance for acetaldehyde. In-situ removal involves reaction with OH (all compounds) and, for acetaldehyde, photolysis and reaction with NO{sub 3}. Acetaldehyde, dioxane, and the ethers are rapidly removed (half-lives of less than one day), leading to PAN (acetaldehyde) and to 2-oxodioxane and formaldehyde (dioxane). Reaction products of the glycol ethers include a large number of hydroxyesters, hydroxyacids, and hydroxycarbonyls. Propylene oxide reacts only slowly with OH, with an atmospheric half-life of 3 - 10 days, to yeild formaldehyde, acetaldehyde, and PAN. Uncertainties in the reaction mechanisms for dioxane, the glycol ethers, and propylene oxide are discussed and include C-C vs C-O bond scission in alkoxy radicals as well as alkoxy radical unimolecular decomposition vs reaction with oxygen.

  6. Single-Layer Light-Emitting Diodes Using Organometal Halide Perovskite/Poly(ethylene oxide) Composite Thin Films.

    PubMed

    Li, Junqiang; Bade, Sri Ganesh R; Shan, Xin; Yu, Zhibin

    2015-09-16

    Organometal halide perovskite and poly(ethylene oxide) composite thin films are studied. Single-layer light-emitting diodes using the composite thin film sandwiched between indium tin oxide and indium-gallium eutectic alloy exhibit a low turn-on voltage and high brightness because of the ionic conductivity of the composite film and the formation of a p-i-n homojunction. PMID:26247326

  7. Removal of ethylene from air stream by adsorption and plasma-catalytic oxidation using silver-based bimetallic catalysts supported on zeolite.

    PubMed

    Trinh, Quang Hung; Lee, Sang Baek; Mok, Young Sun

    2015-03-21

    Dynamic adsorption of ethylene on 13X zeolite-supported Ag and Ag-M(x)O(y) (M: Co, Cu, Mn, and Fe), and plasma-catalytic oxidation of the adsorbed ethylene were investigated. The experimental results showed that the incorporation of Ag into zeolite afforded a marked enhancement in the adsorptivity for ethylene. The addition of transition metal oxides was found to have a positive influence on the ethylene adsorption, except Fe(x)O(y). The presence of the additional metal oxides, however, appeared to somewhat interrupt the diffusion of ozone into the zeolite micro-pores, leading to a decrease in the plasma-catalytic oxidation efficiency of the ethylene adsorbed there. Among the second additional metal oxides, Fe(x)O(y) was able to reduce the emission of ozone during the plasma-catalytic oxidation stage while keeping a high effectiveness for the oxidative removal of the adsorbed ethylene. The periodical treatment consisting of adsorption followed by plasma-catalytic oxidation may be a promising energy-efficient ethylene abatement method. PMID:25576654

  8. Drying of films formed by ordered poly(ethylene oxide)-poly(propylene oxide) block copolymer gels.

    PubMed

    Gu, Zhiyong; Alexandridis, Paschalis

    2005-03-01

    The drying of hydrogel films formed by poly(ethylene oxide)-poly(propylene oxide) (PEO-PPO) block copolymers (Pluronic P105 and Pluronic L64) is investigated at various air relative humidity (RH) conditions in the range 11-94%. These amphiphilic block copolymers self-assemble to form a variety of ordered (lyotropic liquid crystalline) structures as the water content decreases. The amount of water lost increases linearly with the drying time initially (constant rate region, stage I). After this linear region, a falling rate is observed (stage II). The drying rate increases with decreasing RH, thus greatly shortening the drying time. A decrease of the initial film thickness or a decrease in the initial water content shortens the drying time; however, the drying mechanism remains the same. Analysis of the experimental data shows that the hydration level in the Pluronic hydrogel mainly determines the drying rate, rather than the type of ordered structure formed. Two distinct regions (liquid/gel and solid/crystalline) are observed in the drying isotherm for PEO-PPO block copolymers and homopolymer poly(ethylene glycol)s. A model for one-dimensional water diffusion is used to fit the experimental drying results at different RH, initial film thickness, and initial water content conditions. The model accounts for the shrinkage of the film during drying and for a water diffusion coefficient that is a function of the water concentration in the film. For the experimental conditions considered here, the Biot number (Bi) is less than unity and the drying is mainly limited by evaporation at the film surface. The diffusion model is used to obtain information for cases where Bi > 1. PMID:15723476

  9. Preparation of bank bone using defatting, freeze-drying and sterilisation with ethylene oxide gas. Part 1. Experimental evaluation of its efficacy and safety.

    PubMed

    Kakiuchi, M; Ono, K; Nishimura, A; Shiokawa, H

    1996-01-01

    We devised a method of sterilising bone allografts which consists of defatting in chloroform and methanol, freeze-drying and sterilisation with ethylene oxide gas. The purpose of defatting and freeze-drying was to facilitate subsequent sterilisation by eliminating the barrier to diffusion of the gas into bone, to lower residual levels of ethylene oxide and its toxic by-products, to eliminate alloantigens and to make storage possible at room temperature. The efficacy and safety of the method were evaluated by testing the sterilisation of infected bone from 6 patients with active chronic osteomyelitis, the penetration of ethylene oxide into human femoral heads treated by this or by freeze-drying or freeze-thawing, and the desorption of ethylene oxide and its toxic by-products from pieces of bone treated by these methods. All the samples of infected bone tested negative for bacteria after treatment. The gas penetrated into the central area of the femoral heads in a few hours. Residual levels of ethylene oxide and its toxic by-products were much lower in the treated bone than in freeze-dried or freeze-thawed bone, and decreased quickly in flowing air. Prior defatting and freeze-drying facilitated penetration of ethylene oxide into bone during sterilisation and the desorption of ethylene oxide and its toxic by-products after sterilisation. Preparation under clean, but not sterile, conditions and storage at room temperature make bone banking more practical and efficient. PMID:8832315

  10. Insertion Mechanism of a Poly(ethylene oxide)-poly(butylene oxide) Block Copolymer into a DPPC Monolayer

    SciTech Connect

    Leiske, Danielle L.; Meckes, Brian; Miller, Chad E.; Wu, Cynthia; Walker, Travis W.; Lin, Binhua; Meron, Mati; Ketelson, Howard A.; Toney, Michael F.; Fuller, Gerald G.

    2012-02-06

    Interactions between amphiphilic block copolymers and lipids are of medical interest for applications such as drug delivery and the restoration of damaged cell membranes. A series of monodisperse poly(ethylene oxide)-poly(butylene oxide) (EOBO) block copolymers were obtained with two ratios of hydrophilic/hydrophobic block lengths. We have explored the surface activity of EOBO at a clean interface and under 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monolayers as a simple cell membrane model. At the same subphase concentration, EOBO achieved higher equilibrium surface pressures under DPPC compared to a bare interface, and the surface activity was improved with longer poly(butylene oxide) blocks. Further investigation of the DPPC/EOBO monolayers showed that combined films exhibited similar surface rheology compared to pure DPPC at the same surface pressures. DPPC/EOBO phase separation was observed in fluorescently doped monolayers, and within the liquid-expanded liquid-condensed coexistence region for DPPC, EOBO did not drastically alter the liquid-condensed domain shapes. Grazing incidence X-ray diffraction (GIXD) and X-ray reflectivity (XRR) quantitatively confirmed that the lattice spacings and tilt of DPPC in lipid-rich regions of the monolayer were nearly equivalent to those of a pure DPPC monolayer at the same surface pressures.

  11. Citric Acid-Modified Fenton's Reaction for the Oxidation of Chlorinated Ethylenes in Soil Solution Systems

    SciTech Connect

    Seol, Yongkoo; Javandel, Iraj

    2008-03-15

    Fenton's reagent, a solution of hydrogen peroxide and ferrous iron catalyst, is used for an in-situ chemical oxidation of organic contaminants. Sulfuric acid is commonly used to create an acidic condition needed for catalytic oxidation. Fenton's reaction often involves pressure buildup and precipitation of reaction products, which can cause safety hazards and diminish efficiency. We selected citric acid, a food-grade substance, as an acidifying agent to evaluate its efficiencies for organic contaminant removal in Fenton's reaction, and examined the impacts of using citric acid on the unwanted reaction products. A series of batch and column experiments were performed with varying H{sub 2}O{sub 2} concentrations to decompose selected chlorinated ethylenes. Either dissolved iron from soil or iron sulfate salt was added to provide the iron catalyst in the batch tests. Batch experiments revealed that both citric and sulfuric acid systems achieved over 90% contaminant removal rates, and the presence of iron catalyst was essential for effective decontamination. Batch tests with citric acid showed no signs of pressure accumulation and solid precipitations, however the results suggested that an excessive usage of H{sub 2}O{sub 2} relative to iron catalysts (Fe{sup 2+}/H{sub 2}O{sub 2} < 1/330) would result in lowering the efficiency of contaminant removal by iron chelations in the citric acid system. Column tests confirmed that citric acid could provide suitable acidic conditions to achieve higher than 55% contaminant removal rates.

  12. Graphene oxide-stimulated myogenic differentiation of C2C12 cells on PLGA/RGD peptide nanofiber matrices

    NASA Astrophysics Data System (ADS)

    Shin, Y. C.; Lee, J. H.; Kim, M. J.; Hong, S. W.; Oh, J.-W.; Kim, C.-S.; Kim, B.; Hyun, J. K.; Kim, Y.-J.; Han, D.-W.

    2015-07-01

    During the last decade, much attention has been paid to graphene-based nanomaterials because they are considered as potential candidates for biomedical applications such as scaffolds for tissue engineering and substrates for the differentiation of stem cells. Until now, electrospun matrices composed of various biodegradable copolymers have been extensively developed for tissue engineering and regeneration; however, their use in combination with graphene oxide (GO) is novel and challenging. In this study, nanofiber matrices composed of poly(lactic-co-glycolic acid, PLGA) and M13 phage with RGD peptide displayed on its surface (RGD peptide-M13 phage) were prepared as extracellular matrix (ECM)-mimicking substrates. RGD peptide is a tripeptide (Arg-Gly-Asp) found on ECM proteins that promotes various cellular behaviors. The physicochemical properties of PLGA and RGD peptide-M13 phage (PLGA/RGD peptide) nanofiber matrices were characterized by atomic force microscopy, Fourier-transform infrared spectroscopy and thermogravimetric analysis. In addition, the growth of C2C12 mouse myoblasts on the PLGA/RGD peptide matrices was examined by measuring the metabolic activity. Moreover, the differentiation of C2C12 mouse myoblasts on the matrices when treated with GO was evaluated. The cellular behaviors, including growth and differentiation of C2C12 mouse myoblasts, were substantially enhanced on the PLGA/RGD peptide nanofiber matrices when treated with GO. Overall, these findings suggest that the PLGA/RGD peptide nanofiber matrices can be used in combination with GO as a novel strategy for skeletal tissue regeneration.

  13. Health Hazard Evaluation Report HETA 83-166-1594, Witco Chemical Corporation, Perth Amboy, New Jersey. [Ethylene oxide, glycols, and adipic acid

    SciTech Connect

    Cummings, C.E.; Roseman, J.

    1985-05-01

    Area and personel air samples were analyzed for ethylene oxide, glycols, and adipic-acid at the Witco Chemical Corporation, Perth Amboy, New Jersey from November to December, 1983 and May, 1984. The evaluation was requested by the union to investigate possible health effects due to polychlorinated biphenyls (PCBs), glycols, and ethylene oxide. The evaluation was assigned to the New Jersey State Department of Health. The authors conclude that health hazards due to ethylene oxide and airborne fatty acid exposures exist. Recommendations include improving ventilation and work practices and implementing an OSHA approved respirator program.

  14. Final Technical Report - High-Performance, Oxide-Dispersion-Strengthened Tubes for Production of Ethylene adn Other Industrial Chemicals

    SciTech Connect

    McKimpson, Marvin G.

    2006-04-06

    This project was undertaken by Michigan Technological University and Special Metals Corporation to develop creep-resistant, coking-resistant oxide-dispersion-strengthened (ODS) tubes for use in industrial-scale ethylene pyrolysis and steam methane reforming operations. Ethylene pyrolysis tubes are exposed to some of the most severe service conditions for metallic materials found anywhere in the chemical process industries, including elevated temperatures, oxidizing atmospheres and high carbon potentials. During service, hard deposits of carbon (coke) build up on the inner wall of the tube, reducing heat transfer and restricting the flow of the hydrocarbon feedstocks. About every 20 to 60 days, the reactor must be taken off-line and decoked by burning out the accumulated carbon. This decoking costs on the order of $9 million per year per ethylene plant, accelerates tube degradation, and requires that tubes be replaced about every 5 years. The technology developed under this program seeks to reduce the energy and economic cost of coking by creating novel bimetallic tubes offering a combination of improved coking resistance, creep resistance and fabricability not available in current single-alloy tubes. The inner core of this tube consists of Incoloy(R) MA956, a commercial ferritic Fe-Cr-Al alloy offering a 50% reduction in coke buildup combined with improved carburization resistance. The outer sheath consists of a new material - oxide dispersion strengthened (ODS) Alloy 803(R) developed under the program. This new alloy retains the good fireside environmental resistance of Alloy 803, a commercial wrought alloy currently used for ethylene production, and provides an austenitic casing to alleviate the inherently-limited fabricability of the ferritic Incoloy(R) MA956 core. To provide mechanical compatibility between the two alloys and maximize creep resistance of the bimetallic tube, both the inner Incoloy(R) MA956 and the outer ODS Alloy 803 are oxide dispersion

  15. Effect of Organic Capping Layers over Monodisperse Platinum Nanoparticles upon Activity for Ethylene Hydrogenation and Carbon Monoxide Oxidation

    SciTech Connect

    Kuhn, John N.; Tsung, Chia-Kuang; Huang, Wenyu; Somorjai, Gabor A.

    2009-03-24

    The influence of oleylamine (OA), trimethyl tetradecyl ammonium bromide (TTAB), and polyvinlypyrrolidone (PVP) capping agents upon the catalytic properties of Pt/silica catalysts was evaluated. Pt nanoparticles that were 1.5 nm in size were synthesized by the same procedure (ethylene glycol reduction under basic conditions) with the various capping agents added afterward for stabilization. Before examining catalytic properties for ethylene hydrogenation and CO oxidation, the Pt NPs were deposited onto mesoporous silica (SBA-15) supports and characterized by transmission electron microscopy (TEM), H{sub 2} chemisorption, and elemental analysis (ICP-MS). PVP- and TTAB-capped Pt yielded mass-normalized reaction rates that decreased with increasing pretreatment temperature, and this trend was attributed to the partial coverage of the Pt surface with decomposition products from the organic capping agent. Once normalized to the Pt surface area, similar intrinsic activities were obtained regardless of the pretreatment temperature, which indicated no influence on the nature of the active sites. Consequently, a chemical probe technique using intrinsic activity for ethylene hydrogenation was demonstrated as an acceptable method for estimating the metallic surface areas of Pt. Amine (OA) capping exhibited a detrimental influence on the catalytic properties as severe deactivation and low activity were observed for ethylene hydrogenation and CO oxidation, respectively. These results were consistent with amine groups being strong poisons for Pt surfaces, and revealed the need to consider the effects of capping agents on the catalytic properties.

  16. Platinum Metal-Free Catalysts for Selective Soft Oxidative Methane → Ethylene Coupling. Scope and Mechanistic Observations.

    PubMed

    Peter, Matthias; Marks, Tobin J

    2015-12-01

    Using abundant soft oxidants, a high methane-to-ethylene conversion might be achievable due to the low thermodynamic driving force for over-oxidation. Here we report on the oxidative coupling of methane by gaseous S2 (SOCM). The catalytic properties of Pd/Fe3O4 are compared with those of Fe3O4, and it is found that high ethylene selectivities can be achieved without noble metals; conversion and selectivity on Fe3O4 are stable for at least 48 h at SOCM conditions. SOCM data for 10 oxides are compared, and ethylene selectivities as high as 33% are found; the C2H4/C2H6 ratios of 9-12 observed at the highest S2 conversions are significantly higher than the C2H4/C2H6 ratios usually found in the CH4 coupling with O2. Complementary in-detail analytical studies show that, on Mg, Zr, Sm, W, and La catalysts, which strongly coke during the reaction, lower ethylene selectivities are observed than on Fe, Ti, and Cr catalysts, which only coke to a minor extent. Further catalyst-dependent changes during SOCM in surface area, surface composition, and partial conversion to oxysulfides and sulfides are discussed. Evidence concerning the reaction mechanism is obtained taking into account the selectivity for the different reaction products versus the contact time. CH4 coupling proceeds non-oxidatively with the evolution of H2 on some catalysts, and evidence is presented that C2H4 and C2H2 formation occur via C2H6 and C2H4 dehydrogenation, respectively. PMID:26551955

  17. Synthesis of terephthalic acid via Diels-Alder reactions with ethylene and oxidized variants of 5-hydroxymethylfurfural

    PubMed Central

    Pacheco, Joshua J.; Davis, Mark E.

    2014-01-01

    Terephthalic acid (PTA), a monomer in the synthesis of polyethylene terephthalate (PET), is obtained by the oxidation of petroleum-derived p-xylene. There is significant interest in the synthesis of renewable, biomass-derived PTA. Here, routes to PTA starting from oxidized products of 5-hydroxymethylfurfural (HMF) that can be produced from biomass are reported. These routes involve Diels-Alder reactions with ethylene and avoid the hydrogenation of HMF to 2,5-dimethylfuran. Oxidized derivatives of HMF are reacted with ethylene over solid Lewis acid catalysts that do not contain strong Brønsted acids to synthesize intermediates of PTA and its equally important diester, dimethyl terephthalate (DMT). The partially oxidized HMF, 5-(hydroxymethyl)furoic acid (HMFA), is reacted with high pressure ethylene over a pure-silica molecular sieve containing framework tin (Sn-Beta) to produce the Diels-Alder dehydration product, 4-(hydroxymethyl)benzoic acid (HMBA), with 31% selectivity at 61% HMFA conversion after 6 h at 190 °C. If HMFA is protected with methanol to form methyl 5-(methoxymethyl)furan-2-carboxylate (MMFC), MMFC can react with ethylene in the presence of Sn-Beta for 2 h to produce methyl 4-(methoxymethyl)benzenecarboxylate (MMBC) with 46% selectivity at 28% MMFC conversion or in the presence of a pure-silica molecular sieve containing framework zirconium (Zr-Beta) for 6 h to produce MMBC with 81% selectivity at 26% MMFC conversion. HMBA and MMBC can then be oxidized to produce PTA and DMT, respectively. When Lewis acid containing mesoporous silica (MCM-41) and amorphous silica, or Brønsted acid containing zeolites (Al-Beta), are used as catalysts, a significant decrease in selectivity/yield of the Diels-Alder dehydration product is observed. PMID:24912153

  18. Synthesis of terephthalic acid via Diels-Alder reactions with ethylene and oxidized variants of 5-hydroxymethylfurfural.

    PubMed

    Pacheco, Joshua J; Davis, Mark E

    2014-06-10

    Terephthalic acid (PTA), a monomer in the synthesis of polyethylene terephthalate (PET), is obtained by the oxidation of petroleum-derived p-xylene. There is significant interest in the synthesis of renewable, biomass-derived PTA. Here, routes to PTA starting from oxidized products of 5-hydroxymethylfurfural (HMF) that can be produced from biomass are reported. These routes involve Diels-Alder reactions with ethylene and avoid the hydrogenation of HMF to 2,5-dimethylfuran. Oxidized derivatives of HMF are reacted with ethylene over solid Lewis acid catalysts that do not contain strong Brønsted acids to synthesize intermediates of PTA and its equally important diester, dimethyl terephthalate (DMT). The partially oxidized HMF, 5-(hydroxymethyl)furoic acid (HMFA), is reacted with high pressure ethylene over a pure-silica molecular sieve containing framework tin (Sn-Beta) to produce the Diels-Alder dehydration product, 4-(hydroxymethyl)benzoic acid (HMBA), with 31% selectivity at 61% HMFA conversion after 6 h at 190 °C. If HMFA is protected with methanol to form methyl 5-(methoxymethyl)furan-2-carboxylate (MMFC), MMFC can react with ethylene in the presence of Sn-Beta for 2 h to produce methyl 4-(methoxymethyl)benzenecarboxylate (MMBC) with 46% selectivity at 28% MMFC conversion or in the presence of a pure-silica molecular sieve containing framework zirconium (Zr-Beta) for 6 h to produce MMBC with 81% selectivity at 26% MMFC conversion. HMBA and MMBC can then be oxidized to produce PTA and DMT, respectively. When Lewis acid containing mesoporous silica (MCM-41) and amorphous silica, or Brønsted acid containing zeolites (Al-Beta), are used as catalysts, a significant decrease in selectivity/yield of the Diels-Alder dehydration product is observed. PMID:24912153

  19. Facile synthesis of porous worm-like Pd nanotubes with high electrocatalytic activity and stability towards ethylene glycol oxidation

    NASA Astrophysics Data System (ADS)

    Feng, Jiu-Ju; Zhou, Dan-Ling; Xi, Huan-Xiang; Chen, Jian-Rong; Wang, Ai-Jun

    2013-07-01

    A facile method was developed for large-scale preparation of porous worm-like Pd nanotubes based on the reduction of PdO nanotubes, which were obtained by calcining the complex precipitate of [Pd(dimethylglyoxime)2]n. The Pd catalyst showed excellent electrocatalytic activity and stability towards ethylene glycol oxidation.A facile method was developed for large-scale preparation of porous worm-like Pd nanotubes based on the reduction of PdO nanotubes, which were obtained by calcining the complex precipitate of [Pd(dimethylglyoxime)2]n. The Pd catalyst showed excellent electrocatalytic activity and stability towards ethylene glycol oxidation. Electronic supplementary information (ESI) available: Experimental section and Fig. S1-S7. See DOI: 10.1039/c3nr01578e

  20. Poly(ethylene oxide) Functionalized Graphene Nanoribbons with Excellent Solution Processability.

    PubMed

    Huang, Yinjuan; Mai, Yiyong; Beser, Uliana; Teyssandier, Joan; Velpula, Gangamallaiah; van Gorp, Hans; Straasø, Lasse Arnt; Hansen, Michael Ryan; Rizzo, Daniele; Casiraghi, Cinzia; Yang, Rong; Zhang, Guangyu; Wu, Dongqing; Zhang, Fan; Yan, Deyue; De Feyter, Steven; Müllen, Klaus; Feng, Xinliang

    2016-08-17

    Structurally well-defined graphene nanoribbons (GNRs) have attracted great interest as next-generation semiconductor materials. The functionalization of GNRs with polymeric side chains, which can widely broaden GNR-related studies on physiochemical properties and potential applications, has remained unexplored. Here, we demonstrate the bottom-up solution synthesis of defect-free GNRs grafted with flexible poly(ethylene oxide) (PEO) chains. The GNR backbones possess an armchair edge structure with a width of 1.0-1.7 nm and mean lengths of 15-60 nm, enabling near-infrared absorption and a low bandgap of 1.3 eV. Remarkably, the PEO grafting renders the GNRs superb dispersibility in common organic solvents, with a record concentration of ∼1 mg mL(-1) (for GNR backbone) that is much higher than that (<0.01 mg mL(-1)) of reported GNRs. Moreover, the PEO-functionalized GNRs can be readily dispersed in water, accompanying with supramolecular helical nanowire formation. Scanning probe microscopy reveals raft-like self-assembled monolayers of uniform GNRs on graphite substrates. Thin-film-based field-effect transistors (FETs) of the GNRs exhibit a high carrier mobility of ∼0.3 cm(2) V(-1) s(-1), manifesting promising application of the polymer-functionalized GNRs in electronic devices. PMID:27463961

  1. Rheology and pressurised gyration of starch and starch-loaded poly(ethylene oxide).

    PubMed

    Mahalingam, S; Ren, G G; Edirisinghe, M J

    2014-12-19

    This work investigates the rheology and spinning of starch and starch-loaded poly(ethylene oxide) (PEO) by pressurised gyration in order to prepare nanofibres. The spinning dope's rheological properties played a crucial role in fibre formation. Newtonian behaviour is observed in 1-20 wt% starch suspensions and non-Newtonian behaviour is found in all the PEO-starch mixtures. Pressurised gyration of the starch suspensions produced beads only but PEO-starch mixtures generated fibres. The fibre diameter of the PEO-starch samples is shown to be a function of polymer concentration and rotating speed of the gyration system. Fibre formation can only be facilitated below a certain working pressure. The concentration of starch in the PEO-starch mixtures is crucial in defining whether beaded or continuous fibres were generated and this is related to the composition of the spinning dope. FT-IR, XRD and microscopy studies indicated very good miscibility of starch and PEO in the nanofibres. The storage modulus of the PEO-starch were also studied as a function of temperature (30-150°C) and showed interesting results but it was not possible to deduce general trends valid for the entire temperature range. PMID:25263892

  2. Preventing corona effects: multiphosphonic acid poly(ethylene glycol) copolymers for stable stealth iron oxide nanoparticles.

    PubMed

    Torrisi, V; Graillot, A; Vitorazi, L; Crouzet, Q; Marletta, G; Loubat, C; Berret, J-F

    2014-08-11

    When dispersed in biological fluids, engineered nanoparticles are selectively coated with proteins, resulting in the formation of a protein corona. It is suggested that the protein corona is critical in regulating the conditions of entry into the cytoplasm of living cells. Recent reports describe this phenomenon as ubiquitous and independent of the nature of the particle. For nanomedicine applications, however, there is a need to design advanced and cost-effective coatings that are resistant to protein adsorption and that increase the biodistribution in vivo. In this study, phosphonic acid poly(ethylene glycol) copolymers were synthesized and used to coat iron oxide particles. The copolymer composition was optimized to provide simple and scalable protocols as well as long-term stability in culture media. It is shown that polymers with multiple phosphonic acid functionalities and PEG chains outperform other types of coating, including ligands, polyelectrolytes, and carboxylic acid functionalized PEG. PEGylated particles exhibit moreover exceptional low cellular uptake, of the order of 100 femtograms of iron per cell. The present approach demonstrates that the surface chemistry of engineered particles is a key parameter in the interactions with cells. It also opens up new avenues for the efficient functionalization of inorganic surfaces. PMID:25046557

  3. Comprehensive Phase Behavior of Poly(isoprene-b-styrene-b-ethylene oxide) Triblock Copolymers

    SciTech Connect

    Chatterjee, Joon; Jain, Sumeet; Bates, Frank S.

    2010-03-05

    The phase behavior of 44 poly(isoprene-b-styrene-b-ethylene oxide) (ISO) linear triblock copolymer melts was investigated at weak to intermediate segregation strengths and spanning a comprehensive range of compositions. Phases were characterized by a combination of experimental techniques, including small-angle X-ray scattering, dynamic mechanical spectroscopy, transmission electron microscopy, and birefringence measurements. Combined with our previous results, six different stable ordered state symmetries have been identified: lamellae (LAM), Fddd orthorhombic network (O{sup 70}), double gyroid (Q{sup 230}), alternating gyroid (Q{sup 214}), hexagonal (HEX), and body-centered cubic (BCC). The phase map of ISO specimens was found to be somewhat asymmetric around the f{sub I} = f{sub O} isopleth. This work provides a guide for theoretical studies and gives insight into the intricate effects of various parameters on the self-assembly of ABC triblock copolymers. Experimental SAXS data evaluated with a simple scattering intensity model show that local mixing varies continuously across the phase map between states of two- and three-domain segregation.

  4. Platelet adhesion and cellular interaction with poly(ethylene oxide) immobilized onto silicone rubber membrane surfaces.

    PubMed

    Hsiue, G H; Lee, S D; Chang, P C

    1996-01-01

    Cellular interaction and platelet adsorption were investigated on poly(ethylene oxide) (PEO) immobilized silicone rubber membrane (SR) which has polyacrylic acid grafts on the surfaces. Polyacrylic acid (PAA) had been introduced to the SR surface after Ar plasma treatment of SR surfaces to introduce peroxide groups. Surface characterizations were made using ATR-FTIR, ESCA, SEM, and contact angle measurements. Experimental results obtained by ESCA high resolution curve fitting spectra indicated that the amount of bisamino PEO of different molecular weights immobilized onto SR surfaces were similar, which showed that the influence of the length of molecular chains (-C-C-O-) on the reactivity of terminal amino group is negligible. The wettability of modified SR surfaces increased with an increase in PEO molecular weight. Biological studies such as corneal epithelial cell culture and blood platelet adhesion were performed to understand the biocompatibility of modified SR surfaces. Biological studies using corneal epithelial cells showed that cell migration, attachment and proliferation onto PEO-20000 immobilized SR surface were suppressed, whereas these biological activities on PEO-600 were enhanced. Another study on platelet adhesion revealed that many platelets attached to PEO-600 immobilized SR, while platelet deposition was rarely observed on SR grafted with PEO-3350. The effects of different PEO molecular chains on biological response were discussed. PMID:8836831

  5. Simultaneous Surface Modification and Chemical Reduction of Graphene Oxide Using Ethylene Diamine.

    PubMed

    Pan, Hui; Zhang, Yudong; Wang, Xiaodong; Yu, Laigui; Zhang, Zhijun

    2016-03-01

    We report a simple and facile method of reducing and modifying graphene oxide (GO) simultaneously using ethylene diamine (ED). The ED-modified and reduced GO (denoted as E-rGO) as well as the GO reduced by hydrazine hydrate (denoted as H-rGO) were characterized by Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), Raman spectra, Thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), Transmission electron microscopy (TEM) and Scanning electron microscopy (SEM). It was found that as-prepared E-rGO exhibited good dispersibility in water and water-borne polyurethane (denoted as WPU) matrix and improve greatly the mechanical properties of WPU matrix. Moreover, E-rGO showed a high electric conductivity close to that of H-rGO after ultrasonic treatment for 12 h, which indicated that ED had the desired reducibility. The present approach could help to broaden the application field of graphene nanosheets and provide a new opportunity for developing high performance graphene/polymer-matrix composites. PMID:27455669

  6. Self-organization of poly(ethylene oxide) on the surface of aqueous salt solutions.

    PubMed

    Fuchs, Christian; Hussain, Hazrat; Amado, Elkin; Busse, Karsten; Kressler, Joerg

    2015-01-01

    It is demonstrated that stable Langmuir films of poly(ethylene oxide) (PEO) can be formed up to surface pressures of 30 mN m(-1) when potassium carbonate K2CO3 is added to the aqueous subphase. Generally, PEO homopolymer cannot stay on the water surface at a surface pressure ≥10 mN m(-1) due to its high water solubility. To prepare stable monolayer films, PEO can be modified with hydrophobic moieties. However, by exploiting the salting out effect by adding certain salts (K2CO3 or MgSO4) into the aqueous subphase, not only very stable films but also unusual self-organization can be achieved by the PEO homopolymer on the surface of the aqueous solution. Thus, a series of OH-terminated PEOs is found to form a stable monolayer at K2CO3 concentrations of 2 M and above in the aqueous subphase, and the stability of the film increases with an increase in K2CO3 concentration. Hysteresis experiments are also carried out. During the phase transition induced by progressive compression, self-organization into well-defined domains with sizes in the micrometer range are observed, and with further compression and holding of the film for 30 min and above the microdomains transform into a crystalline morphology as visualized by Brewster angle microscopy. PMID:25269665

  7. Photopolymerization-induced crystallization and phase separation in poly(ethylene oxide)/triacrylate blends

    SciTech Connect

    Park, Soo Jeoung; Kyu, Thein

    2008-12-28

    The present article describes experimental and theoretical investigations of miscibility and crystallization behavior of blends of poly(ethylene oxide) (PEO) and triacrylate monomer (TA) using differential scanning calorimetry and optical microscopy. The PEO/TA blends manifested a single T{sub g} varying systematically with composition suggestive of a miscible character in their amorphous states. Moreover, there occurs melting point depression of PEO crystals with increasing TA. A phase diagram was subsequently established that exhibited a solid+liquid coexistence region bound by the liquidus and solidus lines, followed by an upper critical solution temperature (UCST) at a lower temperature. The emerging phase morphology was investigated to verify the coexistence regions. Upon photopolymerization in the isotropic melt above the melting point depression curve, both the UCST and the melting temperatures move upward and eventually surpass the reaction temperature, resulting in phase separation as well as crystallization of PEO driven by the changing supercooling, i.e., the thermodynamic driving force. Of particular interest is the interplay between photopolymerization-induced phase separation and crystallization, which eventually determines the final phase morphology of the PEO/TA blend such as crystalline lamellae, sheaf, or spherulites in isotropic liquid, phase separated domains, and viscous fingering liquids.

  8. Solid dispersion of acetaminophen and poly(ethylene oxide) prepared by hot-melt mixing.

    PubMed

    Yang, Min; Wang, Peng; Huang, Chien-Yueh; Ku, M Sherry; Liu, Huiju; Gogos, Costas

    2010-08-16

    In this study, a model drug, acetaminophen (APAP), was melt mixed with poly(ethylene oxide) (PEO) using a Brabender mixer. APAP was found to recrystallize upon cooling to room temperature for all the drug loadings investigated. Higher drug loading leads to faster recrystallization rate. However, the morphology of the recrystallized drug crystals is identical in samples with different drug loadings and does not change with the storage time. To adjust the drug's dissolution rate, nanoclay Cloisite 15A and 30B were added into the binary mixture. The presence of either of the nanoclay dramatically accelerates the drug's recrystallization rate and slows down the drug's releasing rate. The drop of the releasing rate is mainly due to the decrease of wettability, as supported by the contact angle data. Data analysis of the dissolution results suggests that the addition of nanoclays changes the drug's release mechanism from erosion dominant to diffusion dominant. This study suggests that nanoclays may be utilized to tailor the drug's releasing rate and to improve the dosage form's stability by dramatically shortening the lengthy recrystallization process. PMID:20435110

  9. Mechanical strength of cortical allografts with gamma radiation versus ethylene oxide sterilization.

    PubMed

    Zhou, Zongke; Qin, Tingwu; Yang, Jing; Shen, Bin; Kang, Pengde; Peil, Fuxing

    2011-10-01

    We investigated the effects of gamma irradiation versus ethylene oxide (ETO) sterilization on the mechanical strength of cortical bone grafts. Tibias were collected from cadavers of mature goats. Sixty test specimens were randomized into four groups: fresh (no processing), frozen (freezing at -70 degrees C), gamma-irradiated, and ETO-sterilized specimens. Torsion, three-point bending, and compression testing were separately performed with a material testing machine. Parameters studied included maximum stress, strain, deflection, extension, load, shear modulus, and E-modulus. Compared with findings for the fresh specimens, findings were as follows for gamma-irradiated specimens: maximal shear modulus, reduced by 48%; shear stress, by 55%; deflection, by 71%; bending stress, by 51%; bending strain, by 74%; extension, by 60%; and compression strain, by 50%. However, there were no reductions in those parameters for the frozen specimens or the ETO-sterilized specimens. These findings confirm that shear, bending, and compression strength of cortical allografts are weakened by gamma irradiation at room temperature. To maintain optimum mechanical properties, ETO sterilization of allografts is better than gamma sterilization, especially for cortical bone, because it is usually used in load-bearing settings. PMID:22187845

  10. Encapsulation of T4 bacteriophage in electrospun poly(ethylene oxide)/cellulose diacetate fibers.

    PubMed

    Korehei, Reza; Kadla, John F

    2014-01-16

    Phage therapy is a potentially beneficial approach to food preservation and storage. Sustained delivery of bacteriophage can prevent bacterial growth on contaminated food surfaces. Using coaxial electrospinning bacteriophage can be encapsulated in electrospun fibers with high viability. The resulting bio-based electrospun fibers may have potential as a food packaging material. In the present work, T4 bacteriophage (T4 phage) was incorporated into core/shell electrospun fibers made from poly(ethylene oxide) (PEO), cellulose diacetate (CDA), and their blends. Fibers prepared using PEO as the shell polymer showed an immediate burst release of T4 phage upon submersion in buffer. The blending of CDA with PEO significantly decreased the rate of phage release, with no released T4 phage being detected from the solely CDA fibers. Increasing the PEO molecular weight increased the electrospun fiber diameter and viscosity of the releasing medium, which resulted in a relatively slower T4 phage release profile. SEM analyses of the electrospun fiber morphologies were in good agreement with the T4 phage release profiles. Depending on the PEO/CDA ratio, the post-release electrospun fiber morphologies varied from discontinuous fibers to minimally swollen fibers. From these results it is suggested that the T4 phage release mechanism is through solvent activation/polymer dissolution in the case of the PEO fibers and/or by diffusion control from the PEO/CDA blend fibers. PMID:24188849

  11. Radiation and ethylene oxide terminal sterilization experiences with drug eluting stent products.

    PubMed

    Lambert, Byron J; Mendelson, Todd A; Craven, Michael D

    2011-12-01

    Radiation and ethylene oxide terminal sterilization are the two most frequently used processes in the medical device industry to render product within the final sterile barrier package free from viable microorganisms. They are efficacious, safe, and efficient approaches to the manufacture of sterile product. Terminal sterilization is routinely applied to a wide variety of commodity healthcare products (drapes, gowns, etc.) and implantable medical devices (bare metal stents, heart valves, vessel closure devices, etc.) along with products used during implantation procedures (catheters, guidewires, etc.). Terminal sterilization is also routinely used for processing combination products where devices, drugs, and/or biologics are combined on a single product. High patient safety, robust standards, routine process controls, and low-cost manufacturing are appealing aspects of terminal sterilization. As the field of combination products continues to expand and evolve, opportunity exists to expand the application of terminal sterilization to new combination products. Material compatibility challenges must be overcome to realize these opportunities. This article introduces the reader to terminal sterilization concepts, technologies, and the related standards that span different industries (pharmaceutical, medical device, biopharmaceuticals, etc.) and provides guidance on the application of these technologies. Guidance and examples of the application of terminal sterilization are discussed using experiences with drug eluting stents and bioresorbable vascular restoration devices. The examples provide insight into selecting the sterilization method, developing the process around it, and finally qualifying/validating the product in preparation for regulatory approval and commercialization. Future activities, including new sterilization technologies, are briefly discussed. PMID:21887604

  12. Detection of interstellar ethylene oxide (c-C2H4O).

    PubMed

    Dickens, J E; Irvine, W M; Ohishi, M; Ikeda, M; Ishikawa, S; Nummelin, A; Hjalmarson, A

    1997-11-10

    We report the identification of 10 transitions that support the detection of the small cyclic molecule ethylene oxide (c-C2H4O) in Sgr B2N. Although one of these transitions is severely blended, so that an accurate intensity and line width could not be determined, and two other lines are only marginally detected, we have done Gaussian fits to the remaining seven lines and have performed a rotation diagram analysis. Our results indicate a rotation temperature T(rot) = 18 K and a molecular column density N(c-C2H4O) = 3.3 x 10(14) cm-2, corresponding to a fractional abundance relative to molecular hydrogen of order 6 x 10(-11). This is a factor of more than 200 higher than the abundance for this molecule suggested by the "new standard" chemistry model of Lee, Bettens, & Herbst. This result suggests that grain chemistry might play an effective role in the production of c-C2H4O. No transitions of this molecule were detected in either Sgr B2M or Sgr B2NW. PMID:11541726

  13. Field evaluation of direct-reading continuous ethylene oxide monitors. Final report

    SciTech Connect

    Hossain, M.A.; Carpenter, D.R.

    1989-05-01

    The Wilford Hall USAF Medical Center Central Processing Section (WHMC/SGLP) uses ethylene oxide (EtO) as a primary sterilizing agent. Because of their concern about the health effects of EtO, SGLP has searched for a continuous-monitoring EtO system. In their search, they found two units (AMSCO's Envirogard III and Baseline Industries, Inc.'s Model 5500 Gas Analyzer). The objective of this evaluation was to conduct a field study to compare the performances of the two direct-reading continuous EtO monitors against the Occupational Safety and Health Administration's (OSHA) acceptable charcoal-tube sampling method. In addition, the 3M EtO passive monitor sampling method was compared with the charcoal-tube method and direct-reading instrumental method as well. Neither the Baseline Industries, Inc. nor the AMSCO continuous monitors corresponded to OSHA acceptable charcoal tube method of air sampling. Both instruments reported EtO concentrations much higher than those detected by the charcoal tubes. There is no way of knowing which method, the direct-reading continuous monitor or the charcoal tube/passive monitor, is more correct. However, the OSHA standard for EtO is based on measuring EtO by the charcoal tube method.

  14. Lyotropic Phase Behavior of Polybutadiene-Poly(ethylene oxide) Diblock Copolymers in Ionic Liquids

    SciTech Connect

    Simone, Peter M.; Lodge, Timothy P.

    2008-08-26

    The lyotropic phase behavior of three poly(1,2-butadiene-b-ethylene oxide) diblock copolymers (PB-PEO) with different monomer volume fractions has been studied in two different ionic liquids, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMI][TFSI]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMI][PF{sub 6}]), across the complete concentration range. The ordered microstructures present in the solutions were characterized via small-angle X-ray scattering (SAXS). The phase diagrams for the PB-PEO/ionic liquid solutions include regions corresponding to the classical copolymer microstructures: body-centered-cubic lattices of spheres, hexagonally ordered cylinders, and lamellae. Additionally, the phase diagrams also include wide regions of coexisting microstructures and regions apparently corresponding to a disordered network microstructure. The phase behavior of the PB-PEO copolymers in both ionic liquids was comparable to their previously reported aqueous solution behavior. The temperature dependence of the phase diagrams was very modest, indicative of a highly segregated system. The level of solvent selectivity was also investigated via cryogenic transmission electron microscopy (cryo-TEM) on dilute solutions. On the basis of the morphology of the dilute solution copolymer aggregate structures in the ionic liquid solvents, and on the structural length scales of the concentrated solutions, it was concluded that for PB-PEO [BMI][PF{sub 6}] behaves as a more selective solvent than [EMI][TFSI].

  15. Polycation-sodium lauryl ether sulfate-type surfactant complexes: influence of ethylene oxide length.

    PubMed

    Vleugels, Leo F W; Pollet, Jennifer; Tuinier, Remco

    2015-05-21

    Polyelectrolyte-surfactant complexes (PESC) are a class of materials which form spontaneously by self-assembly driven by electrostatic and hydrophobic interactions. PESC containing sodium lauryl ether sulfates (SLES) have found wide application in hair care products like shampoo. Typically, SLES with only one or two ethylene oxide (EO) groups are used for this application. We have studied the influence of the size of the EO block (ranging from 0 to 30 EO groups) on complexation with two model polycations: linear polyDADMAC and branched PEI. PESC size and electrostatic properties were determined during stepwise titration of buffered polycation solutions. The critical aggregation concentration (CAC) of PESC was determined by surface tension measurements and fluorescence spectroscopy. For polyDADMAC, there is no influence of the size of the EO block on the complexation behavior; the stiff polycation governs the structure formation. For PEI, it was seen that the EO block size does affect the structure of the complexes. The CAC value of the investigated complexes turns out to be rather independent of the EO block size; however, the CMC/CAC ratio decreases with increasing size of the EO block. This latter observation explains why the Lochhead-Goddard effect is most effective for small EO blocks. PMID:25940957

  16. Curing kinetics and morphology of a nanovesicular epoxy/stearyl-block-poly(ethylene oxide) surfactant system.

    PubMed

    Bogaerts, K; Lavrenova, A; Spoelstra, A B; Boyard, N; Goderis, B

    2015-08-21

    Brittle epoxy based thermosets can be made tougher by introducing structural inhomogeneities at the micro- or nanoscale. In that respect, nano vesicles and worm-like micelles from self-assembling blockcopolymers have been shown to be very effective. This paper describes the curing kinetics and morphology of an epoxy composed of diglycidyl ether of bisphenol A (DGEBA) and 4,4'-methylenedianiline (MDA), modified by 20% of the surfactant stearyl-block-poly(ethylene oxide). Time resolved, synchrotron small-angle X-ray scattering demonstrates that at any time during the epoxy curing process, the surfactant predominantly adopts a bilayer vesicular nano-morphology. Transmission electron microscopy on fully cured systems reveals the coexistence of spherical and worm-like micelles. Differential scanning calorimetry experiments prove that the presence of surfactant reduces the epoxy curing rate but that ultimately full curing is accomplished. The material glass transition temperature falls below that of the pure resin due to plasticization. It is suggested that favorable secondary interactions between the PEO segments and the epoxy resin are responsible for the observed phenomena. PMID:26144526

  17. Structure and drug release in a crosslinked poly(ethylene oxide) hydrogel.

    PubMed

    Shekunov, Boris Y; Chattopadhyay, Pratibhash; Tong, Henry H Y; Chow, Albert H L; Grossmann, J Günter

    2007-05-01

    Hydrogels are a continuously expanding class of pharmaceutical polymers designed for sustained or controlled drug release. The structure and intermolecular interactions in such systems define their macroscopic properties. The aim of this study was to investigate the mechanism of swelling, drug impregnation, and drug release from poly(ethylene oxide) (PEO) gel crosslinked by urethane bonds. A combination of SAXS/WAXS/SANS techniques enabled us to determine the phase transition between lamellar and extended gel network, and to apply different descriptions of crystallinity, based on lamellar and crystal lattice structures. It is shown that even low (1-7% w/w) loading of model drugs acetaminophen and caffeine, produced significant disorder in the polymer matrix. This effect was particularly pronounced for acetaminophen due to its specific ability to form complexes with PEO. The drug-release profiles were analyzed using a general cubic equation, proposed for this work, which allowed us to determine the gel hydration velocity. The results indicate that the release profiles correlate inversely with the polymer crystallinity. PMID:17455363

  18. Detection of Interstellar Ethylene Oxide (c-C2H4O)

    NASA Astrophysics Data System (ADS)

    Dickens, J. E.; Irvine, W. M.; Ohishi, M.; Ikeda, M.; Ishikawa, S.; Nummelin, A.; Hjalmarson, A.

    1997-01-01

    We report the identification of 10 transitions which support the detection of the small cyclic molecule ethylene oxide (c-C2H40) in SgrB2(N). Although one of these transitions is severely blended, such that an accurate intensity and linewidth could not be determined, and two other lines are only marginally detected, we have done gaussian fits to the remaining 7 lines and have performed a rotation diagram analysis. Our results indicate a rotation temperature, Trot = 18 K, and a molecular column density, N(c-C2H40) = 3.3 x 1014cm-2, corresponding to a fractional abundance relative to molecular hydrogen of order 6 x 10exp -11). This is a factor of more than 200 higher than the abundance for this molecule suggested by the "new standard" chemistry model of Lee, Bettens, & Herbst (1996). This result suggests that grain chemistry might play an effective role in the production Of c-C2H40. No transitions of this molecule were detected in either SgrB2(M) or SgrB2(NW).

  19. Detection of Interstellar Ethylene Oxide (c-C2H4O)

    NASA Astrophysics Data System (ADS)

    Dickens, J. E.; Irvine, W. M.; Ohishi, M.; Ikeda, M.; Ishikawa, S.; Nummelin, A.; Hjalmarson, Å.

    1997-11-01

    We report the identification of 10 transitions that support the detection of the small cyclic molecule ethylene oxide (c-C2H4O) in Sgr B2N. Although one of these transitions is severely blended, so that an accurate intensity and line width could not be determined, and two other lines are only marginally detected, we have done Gaussian fits to the remaining seven lines and have performed a rotation diagram analysis. Our results indicate a rotation temperature Trot = 18 K and a molecular column density N(c-C2H4O) = 3.3 × 1014 cm-2, corresponding to a fractional abundance relative to molecular hydrogen of order 6 × 10-11. This is a factor of more than 200 higher than the abundance for this molecule suggested by the ``new standard'' chemistry model of Lee, Bettens, & Herbst. This result suggests that grain chemistry might play an effective role in the production of c-C2H4O. No transitions of this molecule were detected in either Sgr B2M or Sgr B2NW.

  20. Interfacial Effect on Confined Crystallization of Poly(ethylene oxide)/Silica Composites

    NASA Astrophysics Data System (ADS)

    Su, Yunlan; Zhao, Weiwei; Gao, Xia; Xu, Jianjun; Wang, Dujin

    The impact of nanoconfinement introduced by nanoparticles on polymer crystallization has attracted extensive attention because it plays the decisive role in the ultimate properties of polymer nanocomposites. In this study, interfacial and spatial confinement effects of silica (SiO2) nanoparticles on the crystallization behaviors of poly(ethylene oxide) (PEO)/SiO2 composites were systematically investigated by changing the size and concentration of SiO2 in PEO matrix. The composites with high silica loadings exhibit two crystallization peaks of PEO as determined by differential scanning calorimetry (DSC). The first peak at 7-43 °C is related to the bulk PEO, while the second peak at -20 to -30 °C is attributed to the restricted PEO segments. Three-layer (amorphous, interfacial and bulk) model is proposed to interpret the confined crystallization of PEO/SiO2 composites, which is supported by the results of thermogravimetric analysis (TGA) and solid-state 1H nuclear magnetic resonance (NMR). In amorphous layer, most PEO segments are directly adsorbed on SiO2 surface via hydrogen bonding. The interfacial PEO layer, which is nonuniform, is composed of crystallizable loops and tails extending from amorphous layer. National Natural Science Foundation of China (NSFC) under Contract 21274156.

  1. Li ion conductors based on laponite/poly(ethylene oxide) composites

    SciTech Connect

    Doeff, M.M.; Reed, J.S.

    1997-11-01

    Synthesis and characterization of single ion conducting poly(ethylene oxide) (PEO)/Li-laponite nanocomposites are reported. The amount of PEO that can be intercalated into laponite, a synthetic hectorite with high surface area, ranges from about 0.7g/g Li-laponite when the polymer average molecular weight is 1,000 or above, to about 1 g/g for oligomers of average molecular weight 500. The interlayer spacing increases from about 10 {angstrom} in the dry clay to 20--24 {angstrom} in the nanocomposites, depending upon polymer molecular weight, and the average particle size increases proportionally, but is still in the sub-micron range. AC impedance measurements on the clear, slightly brittle, self-supporting films indicate that the nanocomposite conductivity is greatly enhanced over that of the dry clay. A maximum of about 10{sup {minus}6} S/cm at 80 C is obtained for materials containing a slight excess of polymer, and conductivities of nanocomposites containing PEO were generally higher than that of those containing oxymethylene linked polyethylene glycol (amorphous PEOs). Suggestions for further improving conductivity and mechanical properties of these novel materials are presented.

  2. Industry-wide studies report of an industrial hygiene of Kettering Medical Center, Kettering, Ohio. [Ethylene oxide

    SciTech Connect

    Ringenburg, V.L.; Morelli-Schroth, P.; Elliott, L.J.

    1986-05-01

    Environmental and breathing-zone samples were analyzed for ethylene oxide in the respiratory therapy area of Kettering Medical Center, Kettering, Ohio in August, 1985. Work practices and engineering controls were observed. Engineering controls included local exhaust ventilation over sterilizer doors and the pressure relief valve and floor drain, and dedicated exhaust ventilation of the sterilizers and aerators. Effective work practices included wearing cotton gloves when unloading sterilizers and pulling instead of pushing carts containing sterilized items.

  3. Comparative sterilization effectiveness of plasma in O2-H2O2 mixtures and ethylene oxide treatment.

    PubMed

    Silva, J M F; Moreira, A J; Oliveira, D C; Bonato, C B; Mansano, R D; Pinto, T J A

    2007-01-01

    We investigated the influence of variable parameters of plasma sterilization and compared its effectiveness with that of ethylene oxide using a reactive ion etching plasma reactor at 13.56 MHz. Gases tested were pure oxygen and oxygen-hydrogen peroxide mixtures in 190/10, 180/20, and 160/40 sccm ratios with constant gas flow at 200 sccm, pressure at 0.100 torr, radio-frequency power at 25 W, 50 W, 100 W, and 150 W, and temperature below 60 degrees C. Ethylene oxide sterilization was performed using 450 mg/L at 55 degrees C, 60% humidity, and -0.65 and 0.60 kgf/cm2 pressure. The biological indicator was Bacillus atrophaeus ATCC 9372, with exposure times of 3 to 120 min. Observed D values were 215.91, 55.55, 9.19, and 2.98 min for pure oxygen plasma at 25 W, 50 W, 100 W, and 150 W, respectively. Oxygen-hydrogen peroxide plasma produced D values of 6.41 min (190/10), 6.47 min (180/20), and 4.02 min (160/40) at 100 W and 1.47 min (190/10), 3.11 min (180/20), and 1.94 min (160/40) at 150 W. Ethylene oxide processes resulted in a D value of 2.86 min. Scanning electron microscopy analyses showed damage to the spore cortex. PMID:17722487

  4. Optical properties of Eu3+-doped antimony-oxide-based low phonon disordered matrices

    NASA Astrophysics Data System (ADS)

    Som, Tirtha; Karmakar, Basudeb

    2010-01-01

    A new series of monolithic Eu2O3-doped high antimony oxide (40-80 mol%) content disordered matrices (glasses) of low phonon energy (about 600 cm-1) in the K2O-B2O3-Sb2O3 (KBS) system was prepared by the melt-quench technique. Infrared reflection spectroscopy was used to establish the low phonon energy of the glasses. Amorphicity and devitrification of the glasses were confirmed by x-ray diffraction analysis. UV-vis absorption spectra of Eu3+ have been measured and the band positions have been justified with quantitative calculation of the nephelauxetic parameter and covalent bonding characteristics of the host. These Eu2O3-doped glasses upon excitation at 393 nm radiation exhibit six emission bands in the range 500-750 nm due to their low phonon energy. Of these, the magnetic dipole ^{5}\\mathrm {D}_{0} \\to {}^{7} \\mathrm {F_{1}} transition shows small Stark splitting while the electric dipole ^{5}\\mathrm {D}_{0} \\to {}^{7}\\mathrm {F}_{2} transition undergoes remarkable Stark splitting into two components. They have been explained by the crystal field effect. The Judd-Ofelt parameters, Ωt = 2,4,6, were also evaluated and the change of Ωt with the glass composition was correlated with the asymmetric effect at Eu3+ ion sites and the fundamental properties like covalent character and optical basicity. We are the first to report the spectroscopic properties of the Eu3+ ion in KBS low phonon antimony glasses.

  5. Dimethyl Sulfide-Dimethyl Ether and Ethylene Oxide-Ethylene Sulfide Complexes Investigated by Fourier Transform Microwave Spectroscopy and AB Initio Calculation

    NASA Astrophysics Data System (ADS)

    Kawashima, Yoshiyuki; Tatamitani, Yoshio; Mase, Takayuki; Hirota, Eizi

    2015-06-01

    The ground-state rotational spectra of the dimethyl sulfide-dimethyl ether (DMS-DME) and the ethylene oxide and ethylene sulfide (EO-ES) complexes were observed by Fourier transform microwave spectroscopy, and a-type and c-type transitions were assigned for the normal, 34S, and three 13C species of the DMS-DME and a-type and b-type rotational transitions for the normal, 34S, and two 13C species of the EO-ES. The observed transitions were analyzed by using an S-reduced asymmetric-top rotational Hamiltonian. The rotational parameters thus derived for the DMS-DME were found consistent with a structure of Cs symmetry with the DMS bound to the DME by two C-H(DMS)---O and one S---H-C(DME) hydrogen bonds. The barrier height V3 to internal rotation of the "free" methyl group in the DME was determined to be 915.4 (23) wn, which is smaller than that of the DME monomer, 951.72 (70) wn, and larger than that of the DME dimer, 785.4 (52) wn. For the EO-ES complex the observed data were interpreted in the terms of an antiparallel Cs geometry with the EO bound to the ES by two C-H(ES)---O and two S---H-C(EO) hydrogen bonds. We have applied a natural bond orbital (NBO) analysis to the DMS-DME and EO-ES to calculate the stabilization energy CT (= ΔEσσ*), which were closely correlated with the binding energy EB, as found for other related complexes. Y. Niide and M. Hayashi, J. Mol. Spectrosc. 220, 65-79 (2003). Y. Tatamitani, B. Liu, J. Shimada, T. Ogata, P. Ottaviani, A. Maris, W. Caminati, and J. L. Alonso, J. Am. Chem. Soc. 124, 2739-2743 (2002).

  6. Comprehensive study on effects of water matrices on removal of pharmaceuticals by three different kinds of advanced oxidation processes.

    PubMed

    Tokumura, Masahiro; Sugawara, Asato; Raknuzzaman, Mohammad; Habibullah-Al-Mamun, Md; Masunaga, Shigeki

    2016-09-01

    Simple semi-theoretical models were developed to estimate the performance of three different kinds of advanced oxidation processes (AOPs) in the degradation of pharmaceuticals. The AOPs included the photo-Fenton process as an example of a liquid-liquid reaction, the TiO2 photocatalytic oxidation process as a solid-liquid reaction, and the combined ozone and hydrogen peroxide oxidation process as a gas-liquid reaction; the effects of the aqueous matrices (CESs: co-existing substances) of actual wastewater on the removal of pharmaceuticals (carbamazepine and diclofenac) was taken into account. By comparing the characteristic parameters of the models, obtained from the experiments using pure water and actual wastewater, the effects of CESs on the respective removal mechanisms could be separately and quantitatively evaluated. As a general tendency, the AOPs proceeded less effectively (were inhibited) in the matrices containing CESs, as observed with the use of a lower initial concentration of pharmaceuticals. The inhibition mechanisms differed for the three types of AOPs. In the photo-Fenton process, the Fenton reaction was improved by the incorporation of CESs, while the photo-reduction reaction was significantly inhibited. In the TiO2 photocatalytic oxidation process, competition between the pharmaceuticals and CESs for adsorption on the catalyst surface was a less significant inhibitory factor than the scavenger effects of the CESs. The combined ozone and hydrogen peroxide oxidation process was most strongly inhibited by CESs among the AOPs investigated in this study. PMID:27317938

  7. Ethylene Oxide and Hydrogen Peroxide Gas Plasma Sterilization: Precautionary Practices in U.S. Hospitals

    PubMed Central

    Boiano, James M.; Steege, Andrea L.

    2015-01-01

    Objective Evaluate precautionary practices and extent of use of ethylene oxide (EtO) and hydrogen peroxide gas plasma (HPGP) sterilization systems, including use of single chamber EtO units. Design Modular, web-based survey. Participants Members of professional practice organizations who reported using EtO or HPGP in the past week to sterilize medical instruments and supplies. Participating organizations invited members via email which included a hyperlink to the survey. Methods Descriptive analyses were conducted including simple frequencies and prevalences. Results A total of 428 respondents completed the module on chemical sterilants. Because most respondents worked in hospitals (87%, n=373) analysis focused on these workers. Most used HPGP sterilizers (84%, n=373), 38% used EtO sterilizers, with 22% using both. Nearly all respondents using EtO operated single chamber units (94%, n=120); most of them reported that the units employed single use cartridges (83%, n=115). Examples of where engineering and administrative controls were lacking for EtO include: operational local exhaust ventilation (7%; n=114); continuous air monitoring (6%; n=113); safe handling training (6%; n=142); and standard operating procedures (4%; n=142). Examples of practices which may increase HPGP exposure risk included lack of standard operating procedures (9%; n=311) and safe handling training (8%; n=312). Conclusions Use of precautionary practices was good but not universal. EtO use appears to have diminished in favor of HPGP which affords higher throughput and minimal regulatory constraints. Separate EtO sterilization and aeration units were still being used nearly one year after U.S. EPA prohibited their use. PMID:26594097

  8. Polymer chain organization in tensile-stretched poly(ethylene oxide)-based polymer electrolytes.

    PubMed

    Burba, Christopher M; Woods, Lauren; Millar, Sarah Y; Pallie, Jonathan

    2011-12-15

    Polymer chain orientation in tensile-stretched poly(ethylene oxide)-lithium trifluoromethanesulfonate polymer electrolytes are investigated with polarized infrared spectroscopy as a function of the degree of strain and salt composition (ether oxygen atom to lithium ion ratios of 20:1, 15:1, and 10:1). The 1359 and 1352 cm(-1) bands are used to probe the crystalline PEO and P(EO)(3)LiCF(3)SO(3) domains, respectively, allowing a direct comparison of chain orientation for the two phases. Two-dimensional correlation FT-IR spectroscopy indicates that the two crystalline domains align at the same rate as the polymer electrolytes are stretched. Quantitative measurements of polymer chain orientation obtained through dichroic infrared spectroscopy show that chain orientation predominantly occurs between strain values of 150% and 250%, regardless of salt composition investigated. There are few changes in chain orientation for either phase when the films are further elongated to a strain of 300%; however, the PEO domains are slightly more oriented at the high strain values. The spectroscopic data are consistent with stretching-induced melt-recrystallization of the unoriented crystalline domains in the solution-cast polymer films. Stretching the films pulls polymer chains from the crystalline domains, which subsequently recrystallize with the polymer helices parallel to the stretch direction. If lithium ion conduction in crystalline polymer electrolytes is viewed as consisting of two major components (facile intra-chain lithium ion conduction and slow helix-to-helix inter-grain hopping), then alignment of the polymer helices will affect the ion conduction pathways for these materials by reducing the number of inter-grain hops required to migrate through the polymer electrolyte. PMID:22184475

  9. Complement activation on poly(ethylene oxide)-like RFGD-deposited surfaces

    PubMed Central

    Szott, Luisa Mayorga; Stein, M. Jeanette; Ratner, Buddy D.; Horbett, Thomas A.

    2010-01-01

    Non-specific protein adsorption, particularly fibrinogen (Fg), is thought to be an initiating step in the foreign body response (FBR) to biomaterials by promoting phagocyte attachment. In previous studies, we therefore prepared radio frequency glow discharge (RFGD) polyethylene oxide (PEO)-like tetraglyme coatings (CH3O(CH2CH2O)4CH3) adsorbing less than 10 ng/cm2 Fg and showed that they had the expected low monocyte adhesion in vitro. However, when these were implanted in vivo, many adherent inflammatory cells and a fibrous capsule were found, suggesting the role of alternative proteins, such as activated complement proteins, in the FBR to these materials. We therefore investigated complement interactions with the tetraglyme surfaces. First, because of its well known role in complement C3 activation, we measured the hydroxyl group (-OH) content of tetraglyme, but found it to be very low. Second, we measured C3 adsorption to tetraglyme from plasma. Low amounts of C3 adsorbed on tetraglyme, though it displayed higher binding strength than the control surfaces. Finally, complement activation was determined by measuring C3a and SC5b-9 levels in serum after incubating with tetraglyme, as well as other surfaces that served as positive and negative controls, namely poly(vinyl alcohol) hydrogels, Silastic sheeting, and poly(ethylene glycol) self-assembled monolayers with different end groups. Despite displaying low hydroxyl group concentration, relatively high C3a and SC5b-9 levels were found in serum exposed to tetraglyme, similar to the values due to our positive control, PVA. Our results support the conclusion that complement activation by tetraglyme is a possible mechanism involved in the FBR to these biomaterials. PMID:21105163

  10. Pharmacokinetics of Polymersomes Composed of Poly(Butadiene-Ethylene Oxide); Healthy versus Tumor-Bearing Mice.

    PubMed

    Wang, G; de Kruijff, R M; Abou, D; Ramos, N; Mendes, E; Franken, L E; Wolterbeek, H T; Denkova, A G

    2016-02-01

    Vesicles composed of block copolymers (i.e., polymersomes) are one of the most versatile nano-carriers for medical purposes due to their tuneable physicochemical properties and the possibility to encapsulate simultaneously hydrophobic and hydrophilic substances, allowing, for instance, the combination of therapy and imaging. In cancer treatment, these vesicles need to remain long enough in the blood stream to be sufficiently taken up by tumors. Here, we have investigated the biodistribution and the pharmacokinetics of polymersomes, composed of poly(butadiene-b-ethylene oxide) having dimensions around 80 nm. The polymersomes have been radiolabeled with ¹¹¹In via the so-called active loading method achieving a loading efficiency of 92.9 ± 0.9% with radionuclide retention in mouse serum of more than 95% at 24 h. The optimized ¹¹¹In containing polymersomes have been intravenously administered in healthy and tumor bearing mice for pharmacokinetic determination using microSPECT (Single Photon Emission Computed Tomography). In healthy mice these polymersomes have been found to exhibit relatively long blood circulation (> 6 h), low liver uptake (6 ± 1.5%ID/g, 48 h p.i.) and elevated spleen uptake (188 ± 30%ID/g). The blood circulation in tumor bearing mice is dramatically reduced (< 1.5 h) most likely due to elevated splenic filtration, clearly indicating the importance of in vivo studies in diseased mice. Finally, the polymersomes have been injected subcutaneously in tumor bearing mice revealing retention of 77% in the mice, primarily accumulated at the site of injection, up to 48 hours after administration. PMID:27305765

  11. Use of multiparameter analysis to quantitate hematological damage from exposure to a chemical (ethylene oxide)

    SciTech Connect

    Popp, D.M.; Popp, R.A.; Lock, S.; Mann, R.C.; Hand, R.E. Jr.

    1986-01-01

    Mice exposed to 255 ppm ethylene oxide (EtO) for 6 h/d were removed for analysis after 1,2,4,8 and 14 d (sequential exposure) and 4,6,8 and 10 wk (5 d/wk). Prior to sacrifice, blood was removed from the orbital sinus for blood cell counts, hemoglobin determination, and hematocrit. A blood film was made for differential leukocyte counts. Bone marrow was flushed from femurs and tibias and counted, and aliquots were used for stem-cell assay (CFU-S) or flow cytometry (FCM) analysis. One aliquot of marrow was stained with propidium iodide for cell-cycle analysis and another was reacted with fluorescein-conjugated monoclonal antibody for B-cell analysis. The preparations were analyzed for forward and 90/sup 0/ scatter and fluorescence on an Ortho 50H cytofluorograph. Perturbations of peripheral leukocytes occurred after one exposure. After multiple exposures, hematocrit, red-cell number, and hemoglobin were generally depressed, with transient compensatory bursts, and bone marrow cellularity and CFU-S were below normal. However, white-cell numbers fluctuated dramatically during the exposure period. There was a shift in differential toward granulocytes, at times resulting in severely depressed numbers of lymphocytes in the peripheral blood. The FCM analysis showed an early depletion of granulocytes in the bone marrow followed by replacement and a relative lymphocyte deficit, especially pronounced at 10 wk. The B-cell changes reflected general lymphocyte perturbations. Shifts in numbers of cells in S and G/M were observed, consistent with a moderate bone marrow response to cell loss.

  12. Extraction of americium in different oxidation states in a two-phase aqueous system based on poly(ethylene glycol)

    SciTech Connect

    Molochnikova, N.P.; Frenkel', B.F.; Myasoedov, B.F.; Shkinev, V.M.; Spivakov, B.Ya.; Zolotov, Yu.A.

    1987-09-01

    The extraction of americium in different states of oxidation was studied in a two-phase aqueous system based on poly(ethylene glycol). Conditions were found for the quantitative extraction of americium (III) and americium (V) from solutions of ammonium sulfate in the pH range of 3-5 and in the presence of arsenazo III. The composition of the complexes of americium with the reagent was determined; americium (III) reacts with arsenazo III in solutions of ammonium sulfate to form complexes with the composition of MeR and Me/sub 2/R. Characteristics of the absorption spectra of complexes of americium (III) and (V) with arsenazo III in ammonium sulfate solutions and in extracts based on aqueous solutions of poly(ethylene glycol) were found. The molar extinction coefficients of complexes of americium with arsenazo III were determined in these solutions.

  13. Oxidation-Responsive and "Clickable" Poly(ethylene glycol) via Copolymerization of 2-(Methylthio)ethyl Glycidyl Ether.

    PubMed

    Herzberger, Jana; Fischer, Karl; Leibig, Daniel; Bros, Matthias; Thiermann, Raphael; Frey, Holger

    2016-07-27

    Poly(ethylene glycol) (PEG) is a widely used biocompatible polymer. We describe a novel epoxide monomer with methyl-thioether moiety, 2-(methylthio)ethyl glycidyl ether (MTEGE), which enables the synthesis of well-defined thioether-functional poly(ethylene glycol). Random and block mPEG-b-PMTEGE copolymers (Mw/Mn = 1.05-1.17) were obtained via anionic ring opening polymerization (AROP) with molecular weights ranging from 5 600 to 12 000 g·mol(-1). The statistical copolymerization of MTEGE with ethylene oxide results in a random microstructure (rEO = 0.92 ± 0.02 and rMTEG E = 1.06 ± 0.02), which was confirmed by in situ (1)H NMR kinetic studies. The random copolymers are thermoresponsive in aqueous solution, with a wide range of tunable transition temperatures of 88 to 28 °C. In contrast, mPEG-b-PMTEGE block copolymers formed well-defined micelles (Rh ≈ 9-15 nm) in water, studied by detailed light scattering (DLS and SLS). Intriguingly, the thioether moieties of MTEGE can be selectively oxidized into sulfoxide units, leading to full disassembly of the micelles, as confirmed by detection of pure unimers (DLS and SLS). Oxidation-responsive release of encapsulated Nile Red demonstrates the potential of these micelles as redox-responsive nanocarriers. MTT assays showed only minor effects of the thioethers and their oxidized derivatives on the cellular metabolism of WEHI-164 and HEK-293T cell lines (1-1000 μg·mL(-1)). Further, sulfonium PEG polyelectrolytes can be obtained via alkylation or alkoxylation of MTEGE, providing access to a large variety of functional groups at the charged sulfur atom. PMID:27375132

  14. Molecular and structural characterization of hybrid poly(ethylene oxide)-polyhedral oligomeric silesquioxanes star-shaped macromolecules.

    PubMed

    Pozza, Gladys M-E; Crotty, Sarah; Rawiso, Michel; Schubert, Ulrich S; Lutz, Pierre J

    2015-01-29

    Octafunctionalized spherosilsesquioxanes (Q8M8(H)), decorated with Si-H functions, could be used to design, by coupling via hydrosilylation with α-methoxy-ω-undecenyl poly(ethylene oxide)s (PEOs), organic-inorganic nanocomposite structures. (1)H, (13)C, and (29)Si NMR; size exclusion chromatography; and Fourier transfrom infrared spectroscopy were used to follow the grafting reaction and determine the molar mass and the functionality of the different species. Hybrid star-shaped poly(ethylene oxide)s of precise molar mass and functionality could be isolated by fractional precipitation of the raw reaction product. Absolute molar masses of the purified star-shaped PEOs, calculated with the assumption of a functionality of 8, were comparable when measured by light scattering in methanol and by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Small-angle X-ray scattering was employed to determine their molecular and structural characteristics, representing the versatility and innovative aspect to this study. Both differential scanning calorimetry and optical microscopy were utilized to elaborate and analyze the thermal properties and crystallization, respectively, of the hybrid stars. Further ongoing work is being carried out currently to investigate and foresee the use of longer PEO branches onto the core. PMID:25531696

  15. Evaluating the formulae for integrated lethality in ethylene oxide sterilization using six different endospore forming strains of bacteria, and comparisons of integrated lethality for ethylene oxide and steam systems.

    PubMed

    Mosley, Gregg A; Gillis, John R; Krushefski, Garrett

    2005-01-01

    Bacterial endospores from six different species of bacteria were exposed to a spectrum of ethylene oxide (EtO) sterilizing conditions. Temperature was varied from 40 to 60 degrees C and the ethylene oxide concentration was varied from 300 to 750 mg/L. Relative humidity was maintained at 60+/-10% RH. The fraction negative procedure was used to determine the D value for each of the test conditions. Bacterial species tested included Bacillus atrophaeus ATCC # 9372, Bacillus smithii ATCC # 51232, Bacillus subtilis "5230" ATCC # 35021, Bacillus subtilis, DSM # 4181, Bacillus pumilus ATCC # 27142, and Geobacillus stearothermophilus ATCC # 7953. All spore preparations were inoculated on filter paper strips packaged in blue, sterilizable glassine pouches. G. stearothermophilus was the least resistant organism tested. The most resistant organisms tested were B. atrophaeus and B. subtilis "5230". The B. subtilis "5230" strain was slightly more resistant than B. atrophaeus at conditions of 54C and EtO concentrations of 400, 600, and 750 mg/L, as well as at 60C/750mg/L EtO. The other species were between these extremes. This empirical data allowed the application of the recently published formula for converting D values from one set of conditions to another and evaluations of accuracy. The measured D values also allowed the determination of Z values based on temperature variations. These formulae, when applied to process temperatures independent of gas concentration, result in a Z value of approximately 32 degrees C that appears to be similar for all species tested. These data support the application of the previously published formulae 1-6 and allow the same approach to integrated lethality for ethylene oxide processes as is commonly applied to steam sterilization. A review of steam sterilization and related principles was conducted for comparison of integrated lethality for these two methods of sterilization. Errors associated with D values, Z values, extrapolation, and

  16. Ethylene promotes germination of Arabidopsis seed under salinity by decreasing reactive oxygen species: evidence for the involvement of nitric oxide simulated by sodium nitroprusside.

    PubMed

    Lin, Yingchao; Yang, Lei; Paul, Matthew; Zu, Yuangang; Tang, Zhonghua

    2013-12-01

    Both ethylene and nitric oxide (NO) are involved in modulating seed germination in adverse environments. However, the mechanisms by which they interact and affect germination have not been explained. In this study, the relationship between ethylene and NO during germination of Arabidopsis seed under salinity was analysed. Application of exogenous 1-aminocyclopropane-1-carboxylate (ACC, a precursor of ethylene biosynthesis) or sodium nitroprusside (SNP, an NO donor) largely overcame the inhibition of germination induced by salinity. The effects of ACC and SNP were decreased by 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (cPTIO), a specific NO scavenger, or by aminoisobutyric acid (AIB), an inhibitor of ethylene biosynthesis, indicating that ethylene and NO interact during germination under salinity. Further, we demonstrated that ACC increased NO production and that SNP greatly induced the expression of the ACS2 gene involved in ethylene synthesis in Arabidopsis seeds germinating under salinity stress, suggesting that each substance influences the production of the other. Application of exogenous ACC increased germination under oxidative stress induced by hydrogen peroxide (H2O2) while SNP had a much smaller effect on wild-type Arabidopsis (Col-0) and no effect on the ethylene insensitive mutant (ein3-1) seeds, respectively. This shows that NO increased germination under salinity indirectly through H2O2 acting via the ethylene pathway. The endogenous concentration of H2O2 was increased by salinity in germinating seeds but was decreased by exogenous ACC, which stimulated germination ultimately. To explain all these results and the regulation of germination of Arabidopsis seed under salinity we propose a model involving ethylene, NO and H2O2 interaction. PMID:24148906

  17. Ethylene and oxygen species adsorbed on a defect oxidized surface Ag(1 1 1) . Theoretical analysis by DFT method

    NASA Astrophysics Data System (ADS)

    Avdeev, Vasilii I.; Zhidomirov, Georgii M.

    2001-10-01

    We suggest a cluster model AS v→Ag12-3O of the oxidized surface Ag(1 1 1) with a defect. The defect is simulated by cationic vacancy V. Density functional theory (B3LYP/LANL1MB approximation) is used to calculate ethylene and oxygen adsorption on the regular (AS r) and defect (AS d) sites on the Ag(1 1 1). Oxygen interaction with site AS r produces atomic oxygen species (AS r-O). Oxygen adsorption on site AS d is accompanied by its association with subsurface oxygen atoms to form a quasimolecular structure of metal ozonide type -Ag-O-O ep-O-Ag-, containing electrophilic oxygen O ep. Energies of atomic oxygen binding to the regular and defect surfaces are found to be approximately equal. On the regular surface, ethylene forms a π-complex with binding energy Eπ(Ag-C 2H 4)=14.2 kcal/mol. On the defect surface, ethylene produces a metal-ethylene-peroxide cycle such as Ag-O-O-C 2H 4-Ag. Determined are the frequencies of normal vibration for ethylene and oxygen species, adsorbed on the regular and defect surfaces. In the case of associative oxygen species and complete isotope replacement 16O→ 18O, the main frequency at 1000 cm -1 shifts by Δν=57-61 cm -1, but this shift decreases to Δν=25-30 cm -1 for isotope mixtures 16O/ 18O. For the adsorbed species of ethylene-oxygen mixtures, IR spectra show the frequencies within which 170-180 cm -1 are associated with stretching of bond Ag-C. Frequencies at 300-490 cm -1 are assigned to mode ν(Ag-O) of the functional group Ag-O-O ep-O-Ag. The most intensive modes at 950 and 600 cm -1 are likely to stretching and bending of the functional groups containing the O-O-O and O-O-C bonds.

  18. An Investigation on the Effect of Polyethylene Oxide Concentration and Particle Size in Modulating Theophylline Release from Tablet Matrices.

    PubMed

    Shojaee, Saeed; Emami, Parastou; Mahmood, Ahmad; Rowaiye, Yemisi; Dukulay, Alusine; Kaialy, Waseem; Cumming, Iain; Nokhodchi, Ali

    2015-12-01

    Polyethylene oxide has been researched extensively as an alternative polymer to hydroxypropyl methylcellulose (HPMC) in controlled drug delivery due to its desirable swelling properties and its availability in a number of different viscosity grades. Previous studies on HPMC have pointed out the importance of particle size on drug release, but as of yet, no studies have investigated the effect of particle size of polyethylene oxide (polyox) on drug release. The present study explored the relationship between polymer level and particle size to sustain the drug release. Tablets produced contained theophylline as their active ingredient and consisted of different polyethylene oxide particle size fractions (20-45, 45-90, 90-180 and 180-425 μm). It was shown that matrices containing smaller particle sizes of polyox produced harder tablets than when larger polyox particles were used. The release studies showed that matrices consisting of large polyox particles showed a faster release rate than matrices made from smaller particles. Molecular weight (MW) of the polymer was a key determining step in attaining sustained release, with the high MW of polyox resulting in a delayed release profile. The results showed that the effect of particle size on drug release was more detrimental when a low concentration of polyox was used. This indicates that care must be taken when low levels of polyox with different particle size fractions are used. More robust formulations could be obtained when the concentration of polyox is high. Differential scanning calorimetry (DSC) traces showed that particle size had no major effect on the thermal behaviour of polyox particles. PMID:25771738

  19. Comparative evaluation of drug release from aged prolonged polyethylene oxide tablet matrices: effect of excipient and drug type.

    PubMed

    Shojaee, Saeed; Kaialy, Waseem; Cumming, Kenneth Iain; Nokhodchi, Ali

    2016-03-01

    Polyethylene oxide (PEO) undergoes structural adjustments caused by elevated temperatures, which results in loss of its stability within direct compression tablets. The aim of this study was to evaluate the influence of filler solubility on the drug delivery process of matrix tablets containing drugs with different water-solubility properties and stored at elevated temperature. The results demonstrated that in the case of propranolol HCl (highly water-soluble) tablet matrices, soluble lactose promoted drug release, whereas, a stable release of drug was observed with insoluble DCP. A drug release pattern similar to the propranolol HCl formulation containing DCP was obtained for hydrophilic matrix tablets containing either lactose or DCP for the less water-soluble drug, zonisamide. In the case of the partially water-soluble drug, theophylline, formulated with lower molecular weight PEO 750, drug release increased considerably in the presence of both fillers with increasing storage time, however a stable release rate (similar to fresh samples) was observed in the case of higher molecular weight PEO 303 tablet matrices containing theophylline with either lactose or DCP. The hydration properties (e.g. solubility) of the diluents had a considerable effect on drug release behavior from various model matrices; this effect was dependent on both molecular weight of PEO and solubility of drug. PMID:25410967

  20. Fourier transform microwave spectrum of the nitrogen molecule-ethylene oxide complex: intracomplex motions.

    PubMed

    Kawashima, Yoshiyuki; Hirota, Eizi

    2013-12-19

    The rotational spectra of the N2-ethylene oxide (EO) complex were measured in the frequency region from 4 to 27 GHz by Fourier transform microwave spectroscopy, paying particular attention to intracomplex motions. The isotopologues with enriched (15)N2 or (15)NN as a moiety were also investigated. We have observed spectra of a strong/weak pair for each of the ortho and para states of the (14)N2-EO and (15)N2-EO species, which indicated that the complex existed in four distinct states. We interpreted, on the basis of the observed relative intensities, that these states were generated primarily by the exchange of the nitrogen atoms of the N2 moiety, followed by that of the two CH2 groups in the EO molecule. The (15)NN-EO species was found to consist of two isomers, one with the (15)N in the inner expressed as N(15)N-EO and the other in the outer position designated as (15)NN-EO, and the spectra of both isomers were accompanied by one weak set of satellites. The observed spectra were rotationally assigned by using sum rules and were analyzed by the asymmetric-rotor program of S-reduction, with the standard deviation of less than 10 kHz. We have found some of the molecular parameters like A, D(JK), and D(K) to be correlated between the two pairs of the spectra, and also, to much less extent, between the strong and weak members. The differences in these molecular parameters between the four sets were explained by the first-order Coriolis interaction between the "ground" and "excited" states generated by a combination of the two internal motions corresponding to the exchanges of the equivalent atoms and/or groups in the N2 and EO constituents of the complex. These internal motions were simulated by the 2-fold internal rotations of the two moieties. We have carried out ab initio molecular orbital calculations at the level of MP2 with basis sets 6-311++G(d,p), aug-cc-pVDZ, and aug-cc-pVTZ, to complement the information on the intracomplex motions obtained from the observed

  1. Membrane protein resistance of oligo(ethylene oxide) self-assembled monolayers.

    PubMed

    Vaish, Amit; Vanderah, David J; Vierling, Ryan; Crawshaw, Fay; Gallagher, D Travis; Walker, Marlon L

    2014-10-01

    As part of an effort to develop biointerfaces for structure-function studies of integral membrane proteins (IMPs) a series of oligo(ethylene oxide) self-assembled monolayers (OEO-SAMs) were evaluated for their resistance to protein adsorption (RPA) of IMPs on Au and Pt. Spectroscopic ellipsometry (SE) was used to determine SAM thicknesses and compare the RPA of HS(CH2)3O(CH2CH2O)6CH3 (1), HS(CH2)3O(CH2CH2O)6H (2), [HS(CH2)3]2CHO(CH2CH2O)6CH3 (3) and [HS(CH2)3]2CHO(CH2CH2O)6H (4), assembled from water. For both substrates, SAM thicknesses for 1 to 4 were found to be comparable indicating SAMs with similar surface coverages and OEO chain order and packing densities. Fibrinogen (Fb), a soluble plasma protein, and rhodopsin (Rd), an integral membrane G-protein coupled receptor, adsorbed to the SAMs of 1, as expected from previous reports, but not to the hydroxy-terminated SAMs of 2 and 4. The methoxy-terminated SAMs of 3 were resistant to Fb but, surprisingly, not to Rd. The stark difference between the adsorption of Rd to the SAMs of 3 and 4 clearly indicate that a hydroxy-terminus of the OEO chain is essential for high RPA of IMPs. The similar thicknesses and high RPA of the SAMs of 2 and 4 show the conditions of protein resistance (screening the underlying substrate, packing densities, SAM order, and conformational mobility of the OEO chains) defined from previous studies on Au are applicable to Pt. In addition, the SAMs of 4, exhibiting the highest resistance to Fb and Rd, were placed in contact with undiluted fetal bovine serum for 2h. Low protein adsorption (≈12.4ng/cm(2)), obtained under these more challenging conditions, denote a high potential of the SAMs of 4 for various applications requiring the suppression of non-specific protein adsorption. PMID:25124834

  2. A comparison of two methods for selecting vibrational configuration interaction spaces on a heptatomic system: ethylene oxide.

    PubMed

    Bégué, Didier; Gohaud, Neil; Pouchan, Claude; Cassam-Chenaï, Patrick; Liévin, Jacques

    2007-10-28

    Two recently developed methods for solving the molecular vibrational Schrodinger equation, namely, the parallel vibrational multiple window configuration interaction and the vibrational mean field configuration interaction, are presented and compared on the same potential energy surface of ethylene oxide, c-C(2)H(4)O. It is demonstrated on this heptatomic system with strong resonances that both approaches converge towards the same fundamental frequencies. This confirms their ability to tackle the vibrational problem of large molecules for which full configuration interaction calculations are not tractable. PMID:17979327

  3. National emission standards for hazardous air pollutants for ethylene oxide commercial sterilization and fumigation operations--EPA. Interim final rule.

    PubMed

    1998-12-01

    Today's action suspends the National Emission Standards for Hazardous Air Pollutants for Ethylene Oxide Commercial Sterilization and Fumigation Operations (EO NESHAP) requirements for chamber exhaust and aeration room vents. The suspension allows affected sources subject to the EO NESHAP to defer compliance with the NESHAP requirements for chamber exhaust and aeration room vents for one year until December 6, 1999. This suspension does not affect the requirement for sources subject to the EO NESHAP to comply with provisions for sterilizer vents by December 6, 1998. This action does not change the level of the standards or the intent of the NESHAP promulgated in 1994. PMID:10338881

  4. Severe anaphylactic shock due to ethylene oxide in a patient with myelomeningocele: successful exposure prevention and pretreatment with omalizumab.

    PubMed

    Listyo, Adrian; Hofmeier, Kathrin Scherer; Bandschapp, Oliver; Erb, Thomas; Hasler, Carol-Claudius; Bircher, Andreas J

    2014-01-01

    Ethylene oxide (EO) is a highly reactive gas widely used for sterilization of medical devices, for example, plastic materials and ventriculoperitoneal shunts. Allergic reactions to EO are rare and have been observed mainly in patients during hemodialysis and myelomeningocele patients. We describe severe anaphylaxis to EO in a patient with myelomeningocele during general anesthesia. A detailed description is provided about the prevention measures aimed at reducing exposure to EO including a novel approach by resterilization with plasma. Also, pretreatment with omalizumab was implemented for the first time in such a case. With these measures, further surgeries in our patient were uneventful. PMID:25612258

  5. Nitric Oxide, Ethylene, and Auxin Cross Talk Mediates Greening and Plastid Development in Deetiolating Tomato Seedlings1[OPEN

    PubMed Central

    Melo, Nielda K.G.; Bianchetti, Ricardo E.; Oliveira, Paulo M.R.; Demarco, Diego

    2016-01-01

    The transition from etiolated to green seedlings involves the conversion of etioplasts into mature chloroplasts via a multifaceted, light-driven process comprising multiple, tightly coordinated signaling networks. Here, we demonstrate that light-induced greening and chloroplast differentiation in tomato (Solanum lycopersicum) seedlings are mediated by an intricate cross talk among phytochromes, nitric oxide (NO), ethylene, and auxins. Genetic and pharmacological evidence indicated that either endogenously produced or exogenously applied NO promotes seedling greening by repressing ethylene biosynthesis and inducing auxin accumulation in tomato cotyledons. Analysis performed in hormonal tomato mutants also demonstrated that NO production itself is negatively and positively regulated by ethylene and auxins, respectively. Representing a major biosynthetic source of NO in tomato cotyledons, nitrate reductase was shown to be under strict control of both phytochrome and hormonal signals. A close NO-phytochrome interaction was revealed by the almost complete recovery of the etiolated phenotype of red light-grown seedlings of the tomato phytochrome-deficient aurea mutant upon NO fumigation. In this mutant, NO supplementation induced cotyledon greening, chloroplast differentiation, and hormonal and gene expression alterations similar to those detected in light-exposed wild-type seedlings. NO negatively impacted the transcript accumulation of genes encoding phytochromes, photomorphogenesis-repressor factors, and plastid division proteins, revealing that this free radical can mimic transcriptional changes typically triggered by phytochrome-dependent light perception. Therefore, our data indicate that negative and positive regulatory feedback loops orchestrate ethylene-NO and auxin-NO interactions, respectively, during the conversion of colorless etiolated seedlings into green, photosynthetically competent young plants. PMID:26829981

  6. Influence of Different Shellfish Matrices on the Separation of PSP Toxins Using a Postcolumn Oxidation Liquid Chromatography Method

    PubMed Central

    Rey, Verónica; Alfonso, Amparo; Botana, Luis M.; Botana, Ana M.

    2015-01-01

    The separation of PSP toxins using liquid chromatography with a post-column oxidation fluorescence detection method was performed with different matrices. The separation of PSP toxins depends on several factors, and it is crucial to take into account the presence of interfering matrix peaks to produce a good separation. The matrix peaks are not always the same, which is a significant issue when it comes to producing good, reliable results regarding resolution and toxicity information. Different real shellfish matrices (mussel, scallop, clam and oyster) were studied, and it was seen that the interference is not the same for each individual matrix. It also depends on the species, sampling location and the date of collection. It was proposed that separation should be accomplished taking into account the type of matrix, as well as the concentration of heptane sulfonate in both solvents, since the mobile phase varies regarding the matrix. Scallop and oyster matrices needed a decrease in the concentration of heptane sulfonate to separate GTX4 from matrix peaks, as well as dcGTX3 for oysters, with a concentration of 6.5 mM for solvent A and 6.25 mM for solvent B. For mussel and clam matrices, interfering peaks are not as large as they are in the other group, and the heptane sulfonate concentration was 8.25 mM for both solvents. Also, for scallops and oysters, matrix interferences depend not only on the sampling site but also on the date of collection as well as the species; for mussels and clams, differences are noted only when the sampling site varies. PMID:25884908

  7. Monitoring human exposure to ethylene oxide by the determination of hemoglobin adducts using gas chromatography-mass spectrometry

    SciTech Connect

    Farmer, P.B.; Bailey, E.; Gorf, S.M.; Toernqvist, M.O.; Osterman-Golkar, S.; Kautiainen, A.; Lewis-Enright, D.P.

    1986-04-01

    Globin samples from ethylene oxide-exposed workers and non-exposed referrents were analyzed by two methods: (i) gas chromatography-mass spectrometry determination of Nt-(2-hydroxyethyl)histidine as its methyl ester heptafluorobutyryl derivative, after hydrolysis of the protein and isolation of the alkylated amino acid by ion exchange chromatography. The internal standard, Nt-(2-hydroxy-d4-ethyl)histidine, was added to the protein before hydrolysis. (ii) Determination of N-(2-hydroxyethyl)valine after derivatization of the protein by a modified Edman procedure, extraction and g.c.-m.s. determination of alkylated N-terminal valine in the form of its pentafluorophenylthiohydantoin derivative. The internal standard used was in this case a globin with a known content of hydroxy-d4-ethylated amino acids. The two methods gave consistent results, especially at high levels of alkylated products. The average content of hydroxyethylhistidine was 0.6 nmol/g higher than the content of hydroxyethylvaline. Higher levels of background alkylation (of unknown origin) were recorded with the histidine method as compared with the valine method, suggesting that the latter assay should show greater sensitivity for low level ethylene oxide exposure monitoring.

  8. Modeling and experimental investigation of rheological properties of injectable poly(lactide ethylene oxide fumarate)/hydroxyapatite nanocomposites.

    PubMed

    Sarvestani, Alireza S; Jabbari, Esmaiel

    2006-05-01

    Injectable multiphasic polymer/ceramic composites are attractive as bioresorbable scaffolds for bone regeneration because they can be cross-linked in situ and are osteoconductive. The injectability of the composite depends on the nanoparticle content and the energetic interactions at the polymer/particle interface. The objective of this research was to determine experimentally the rheological properties of the PLEOF/apatite composite as an injectable biomaterial and to compare the viscoelastic response with the predictions of a linear elastic dumbbell model. A degradable in situ cross-linkable terpolymer based on low molecular weight poly(L-lactide) and poly(ethylene oxide) linked by unsaturated fumarate groups is synthesized. The poly(L-lactide-co-ethylene oxide-co-fumarate) (PLEOF) terpolymer interacts with the surface of the apatite nanoparticles by polar interactions and hydrogen bonding. A kinetic model is developed that takes into account the adsorption/desorption of polymer chains to/from the nanoparticle surface. Rheological properties of the aqueous dispersion of PLEOF terpolymer reinforced with nanosized hydroxyapatite (HA) particles are investigated using mechanical rheometry. To this end, we performed a series of rheological experiments on un-cross-linked PLEOF reinforced with different volume fractions of HA nanoparticles. The results demonstrate that the observed nonlinear viscoelasticity at higher shear rates is controlled by the energetic interactions between the polymer chains and dispersed particle aggregates and by the rate of the adsorption/desorption of the chains to/from the surface of the nanoparticles. PMID:16677041

  9. Laboratory validation and field verification of a new passive air monitoring badge for sampling ethylene oxide in air.

    PubMed

    Kring, E V; Damrell, D J; Basilio, A N; McGibney, P D; Douglas, J J; Henry, T J; Ansul, G R

    1984-10-01

    A new diffusion colorimetric air monitoring badge for sampling ethylene oxide is described. The Du Pont Pro-Tek C-70 badge has been laboratory validated over the range of 4-375 ppm-hours (0.5-47 ppm on an 8-hour TWA) using standard spectrophotometer readout in 1 centimeter (10 mm) cells. The lower range can be extended to 2 ppm-hours (0.25 ppm) by using 4 cm (40 mm) cells. The badge has an overall sampling and analytical method accuracy of +/- 13.5%. It meets NIOSH accuracy criteria and has a mean coefficient of variation CVT = 0.059. The badge has no temperature, pressure, relative humidity or face velocity effects over practical ranges. The response time is adequate to sample peak concentrations over short time periods. The badge may be used to determine ambient formaldehyde levels if suspected to be present along with ethylene oxide. Badges are shown to agree very well with the industry accepted and proposed ASTM pump/charcoal tube method in three extensive plant field tests. Badges were more precise than the charcoal tube/pump method in all field tests conducted. PMID:6496316

  10. A comparative study of the treatment of ethylene plant spent caustic by neutralization and classical and advanced oxidation.

    PubMed

    Hawari, Alaa; Ramadan, Hasanat; Abu-Reesh, Ibrahim; Ouederni, Mabrouk

    2015-03-15

    The treatment of spent caustic produced from an ethylene plant was investigated. In the case of neutralization alone it was found that the maximum removal of sulfide was at pH values below 5.5. The higher percentage removal of sulfides (99% at pH = 1.5) was accompanied with the highest COD removal (88%). For classical oxidation using H2O2 the maximum COD removal percentage reached 89% at pH = 2.5 and at a hydrogen peroxide concentration of 19 mM/L. For the advanced oxidation using Fenton's process it was found that the maximum COD removal of 96.5% was achieved at a hydrogen peroxide/ferrous sulfate ratio of (7:1). PMID:25546845

  11. Oxidation of methanol, ethylene glycol, and isopropanol with human alcohol dehydrogenases and the inhibition by ethanol and 4-methylpyrazole.

    PubMed

    Lee, Shou-Lun; Shih, Hsuan-Ting; Chi, Yu-Chou; Li, Yeung-Pin; Yin, Shih-Jiun

    2011-05-30

    Human alcohol dehydrogenases (ADHs) include multiple isozymes with broad substrate specificity and ethnic distinct allozymes. ADH catalyzes the rate-limiting step in metabolism of various primary and secondary aliphatic alcohols. The oxidation of common toxic alcohols, that is, methanol, ethylene glycol, and isopropanol by the human ADHs remains poorly understood. Kinetic studies were performed in 0.1M sodium phosphate buffer, at pH 7.5 and 25°C, containing 0.5 mM NAD(+) and varied concentrations of substrate. K(M) values for ethanol with recombinant human class I ADH1A, ADH1B1, ADH1B2, ADH1B3, ADH1C1, and ADH1C2, and class II ADH2 and class IV ADH4 were determined to be in the range of 0.12-57 mM, for methanol to be 2.0-3500 mM, for ethylene glycol to be 4.3-2600mM, and for isopropanol to be 0.73-3400 mM. ADH1B3 appeared to be inactive toward ethylene glycol, and ADH2 and ADH4, inactive with methanol. The variations for V(max) for the toxic alcohols were much less than that of the K(M) across the ADH family. 4-Methylpyrazole (4MP) was a competitive inhibitor with respect to ethanol for ADH1A, ADH1B1, ADH1B2, ADH1C1 and ADH1C2, and a noncompetitive inhibitor for ADH1B3, ADH2 and ADH4, with the slope inhibition constants (K(is)) for the whole family being 0.062-960 μM and the intercept inhibition constants (K(ii)), 33-3000 μM. Computer simulation studies using inhibition equations in the presence of alternate substrate ethanol and of dead-end inhibitor 4MP with the determined corresponding kinetic parameters for ADH family, indicate that the oxidation of the toxic alcohols up to 50mM are largely inhibited by 20 mM ethanol or by 50 μM 4MP with some exceptions. The above findings provide an enzymological basis for clinical treatment of methanol and ethylene glycol poisoning by 4MP or ethanol with pharmacogenetic perspectives. PMID:21167143

  12. Ethylene update

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The gaseous plant hormone ethylene is required for many aspects of plant growth, development and responses to the environment. Potato tubers produce low amounts of ethylene and are highly sensitive to ethylene in the atmosphere. Several responses of potato tubers to endogenous and exogenous ethylene...

  13. Effect of modifier oxides on absorption and emission properties of Eu3+ doped different lithium fluoroborate glass matrices

    NASA Astrophysics Data System (ADS)

    Ratnakaram, Y. C.; Balakrishna, A.; Rajesh, D.

    2012-11-01

    Eu3+ doped lithium fluoroborate glass with different modifier oxides (Li2B4O7-BaF2-NaF-MO where M=Mg, Ca, Cd and Pb) and combinations of modifier oxides (Li2B4O7-BaF2-NaF-MgO+CaO, Li2B4O7-BaF2-NaF-CdO+PbO) were prepared by means of melt quenching method. These glass samples were analyzed by absorption, photoluminescence and decay curve measurements. The relative merits of thermal correction to the spectral intensities originating from the ground state (7F0) of different absorption bands of Eu3+ are calculated. From the optical absorption measurements and using the Judd-Ofelt (J-O) theory, J-O parameters (Ωλλ=2, 4 and 6) have been obtained which are used to predict the radiative properties such as radiative transition probabilities (A), radiative life-times (τR), and branching ratios (βr) for certain transitions in all the glass matrices. From the emission spectra, peak stimulated emission cross-sections (σP) are obtained for the emission transitions, 5D0→7F1, 5D0→7F2, 5D0→7F3 and 5D0→7F4 of Eu3+ in lithium fluoroborate glass matrix with different modifier oxides. The fluorescence decay curves of the 5D0→7F2 transition have been measured and analyzed for all the glass matrices.

  14. Lenghty reverse poly(butylene oxide)-poly(ethylene oxide)-poly(butylene oxide) polymeric micelles and gels for sustained release of antifungal drugs.

    PubMed

    Figueroa-Ochoa, Edgar B; Villar-Alvarez, Eva M; Cambón, Adriana; Mistry, Dharmista; Llovo, José; Attwood, David; Barbosa, Silvia; Soltero, J F Armando; Taboada, Pablo

    2016-08-20

    In this work, we present a detailed study of the potential application of polymeric micelles and gels of four different reverse triblock poly(butylene oxide)-poly(ethylene oxide)-poly(butylene oxide) copolymers (BOnEOmBOn, where n denotes the respective block lengths), specifically BO8EO90BO8, BO14EO378BO14, BO20EO411BO20 and BO21EO385BO21, as effective drug transport nanocarriers. In particular, we tested the use of this kind of polymeric nanostructures as reservoirs for the sustained delivery of the antifungals griseofulvin and fluconazole for oral and topical administration. Polymeric micelles and gels formed by these copolymers were shown to solubilize important amounts of these two drugs and to have a good stability in physiologically relevant conditions for oral or topical administration. These polymeric micellar nanocarriers were able to release drugs in a sustained manner, being the release rate slower as the copolymer chain hydrophobicity increased. Different sustained drug release profiles were observed depending on the medium conditions. Gel nanocarriers were shown to display longer sustained release rates than micellar formulations, with the existence of a pulsatile-like release mode under certain solution conditions as a result of their inner network structure. Certain bioadhesive properties were observed for the polymeric physical gels, being moderately tuned by the length and hydrophobicity of the polymeric chains. Furthermore, polymeric gels and micelles showed activity against the yeast Candida albicans and the mould demartophytes (Trichophyton rubrum and Microsporum canis) and, thus, may be useful for the treatment of different cutaneous fungal infections. PMID:27289012

  15. Non-invasive topical drug delivery to spinal cord with carboxyl-modified trifunctional copolymer of ethylene oxide and propylene oxide.

    PubMed

    Kamalov, Marat I; Lavrov, Igor A; Yergeshov, Abdulla A; Siraeva, Zulfira Y; Baltin, Maxim E; Rizvanov, Albert A; Kuznetcova, Svetlana V; Petrova, Natalia V; Savina, Irina N; Abdullin, Timur I

    2016-04-01

    In this study the effect of oxidative modification on micellar and drug delivery properties of copolymers of ethylene oxide (EO) and propylene oxide (PO) was investigated. Carboxylated trifunctional copolymers were synthesized in the reaction with chromium(VI) oxide. We found that carboxylation significantly improved the uniformity and stability of polymeric micelles by inhibiting the microphase transition. The cytotoxicity of copolymers was studied in relation to their aggregative state on two cell types (cancer line vs. primary fibroblasts). The accumulation of rhodamine 123 in neuroblastoma SH-SY5Y cells was dramatically increased in the presence of the oxidized block copolymer with the number of PO and EO units of 83.5 and 24.2, respectively. The copolymer was also tested as an enhancer for topical drug delivery to the spinal cord when applied subdurally. The oxidized copolymer facilitated the penetration of rhodamine 123 across spinal cord tissues and increased its intraspinal accumulation. These results show the potential of using oxidized EO/PO based polymers for non-invasive delivery of protective drugs after spinal cord injury. PMID:26764102

  16. Development and assessment of two-phase porous matrices for use in all-oxide ceramic composites

    NASA Astrophysics Data System (ADS)

    Fujita, Hiroki

    The study focuses on a class of all-oxide continuous-fiber ceramic composite (CFCC) in which damage tolerance is derived from a highly-porous matrix, without an interphase at the fiber-matrix boundary. It includes experiments and analyses on both a representative oxide CFCC (developed earlier at UCSB) and a series of alumina-mullite matrices. The first part of the thesis addresses the stability of the porosity against densification and the associated implications for long-term durability at elevated temperatures. For this purpose, changes in the mechanical properties of the CFCC following 1000 hour exposure at 1000--1200°C were examined. Despite evidence of some strengthening of the matrix, the tensile properties in the 0°/90° orientation, including strength and failure strain, are unchanged. This strengthening is manifested to a more significant extent in the composite properties in the +/-45° orientation. The remainder of the thesis focuses on the assessment of weakly bonded mixtures of mullite and alumina as candidate matrices. Stability against densification is accomplished by using mullite particles as the major phase. This stability arises from the sluggish sintering kinetics of mullite. The matrix is strengthened by adding alumina, either as small particulates in the starting slurry or by subsequent impregnation and pyrolysis of a precursor solution. The modulus and the toughness of both types of mixtures as well as the changes in these properties following aging at 1200°C are examined. Models based on bonded particle aggregates are presented, assessed and calibrated. When coupled with a crack deflection parameter, the models are useful in determining the conditions under which damage tolerance is lost, because of excessive strengthening of the matrix. The implications of these results in matrix design are discussed.

  17. Density-functional investigation of the geometric and electronic structure of ethylene oxide adsorbed on Si(100)

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Li, Qing-Fang; Yang, Cui-Hong; Wei, Yue-Ling; Zhu, Xing-Feng; Rao, Wei-Feng

    2016-05-01

    The geometric and electronic structures of the ethylene oxide (EO) molecule adsorbed on Si(100)-(2 × 1) surface were investigated by using the density-functional theory calculations. All possible adsorbed structures were considered and it was found that only four adsorption structures are stable. The calculations of the formation energy revealed the most stable conformation and demonstrated that the nature of Si-O bond significantly affects the stability of adsorption systems. The analysis of corresponding electronic structures showed that two adsorbed structures are still semiconductor compounds but the other two are not. In particular, the EO after adsorbing was found to be connected via a ring-opening reaction where the molecule forms a five-membered ring together with the surface of dimer silicon atoms, and the produced five-membered ring is almost perpendicular to the silicon surface.

  18. The structure of poly(ethylene oxide) liquids : comparison of integral equation theory with molecular dynamics simulations and neutron scaling.

    SciTech Connect

    Curro, John G.; Frischknecht, Amalie Lucile

    2005-01-01

    Polymer reference interaction site model (PRISM) calculations and molecular dynamics (MD) simulations were carried out on poly(ethylene oxide) liquids using a force field of Smith, Jaffe, and Yoon. The intermolecular pair correlation functions and radius of gyration from theory were in very good agreement with MD simulations when the partial charges were turned off. When the charges were turned on, considerably more structure was seen in the intermolecular correlations obtained from MD simulation. Moreover, the radius of gyration increased by 38% due to electrostatic repulsions along the chain backbone. Because the partial charges greatly affect the structure, significant differences were seen between the PRISM calculations (without charges) and the wide angle neutron scattering measurements of Annis and coworkers for the total structure factor, and the hydrogen/hydrogen intermolecular correlation function. This is in contrast to previous PRISM calculations on poly (dimethyl siloxane).

  19. Second-generation locking mechanisms and ethylene oxide sterilization reduce tibial insert backside damage in total knee arthroplasty.

    PubMed

    Azzam, Michael G; Roy, Marcel E; Whiteside, Leo A

    2011-06-01

    This study evaluated the effects of polyethylene quality and locking mechanism on damage to the nonarticulating (backside) surface of retrieved tibial inserts in total knee arthroplasty. Inserts with peripheral capture (PC) locking mechanisms and ethylene oxide (EtO)-sterilized polyethylene were hypothesized to prevent major backside damage. A total of 156 inserts were sorted by locking mechanism and sterilization method and analyzed by damage scoring methods. Ninety-seven specimens exhibited burnishing. Significant positive linear correlations were observed between damage score and age in vivo for all combinations, but damage occurred at a significantly lower rate for second-generation PC implants with EtO sterilization. Most specimens in this group were undamaged (46/72), with others exhibiting only burnishing. Sex, body mass index, and weight did not influence backside damage. PMID:20541356

  20. Structure and dynamics of water near the interface with oligo(ethylene oxide) self-assembled monolayers.

    PubMed

    Ismail, Ahmed E; Grest, Gary S; Stevens, Mark J

    2007-07-31

    We performed molecular dynamics simulations of the oligo(ethylene oxide) (OEO) self-assembled monolayers in water to determine the nature of the systems' interfacial structure and dynamics. The density profiles, hydrogen bonding, and water dynamics are calculated as a function of the area per molecule A of OEO. At the highest coverages, the interface is hydrophobic, and a density drop is found at the interface. The interfacial region becomes more like bulk water as A increases. The OEO and water become progressively more mixed, and hydrogen bonding increases within the interfacial region. Water mobility is slower within the interfacial region, but not substantially. The implications of our results on the resistance of OEO SAMs to protein adsorption are discussed. Our principal result is that as A increases the increasingly waterlike interfacial region provides a more protein-resistant surface. This finding supports recent experimental measurements that protein resistance is maximal for less than full coverage on Au. PMID:17622160

  1. Efficient Crystalline Si/Poly(ethylene dioxythiophene):Poly(styrene sulfonate):Graphene Oxide Composite Heterojunction Solar Cells

    NASA Astrophysics Data System (ADS)

    Ono, Masahiro; Tang, Zeguo; Ishikawa, Ryo; Gotou, Takuya; Ueno, Keiji; Shirai, Hajime

    2012-03-01

    Efficient crystalline silicon (c-Si) heterojunction solar cells with conductive poly(ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and graphene oxide (GO) composite are demonstrated using a structure of Ag/PEDOT:PSS/PEDOT:PSS:GO composite/c-Si (100)(ρ: 3-5 Ω.cm)/Al. The power-conversion efficiency η increased to 10.7% under illumination of AM1.5 100 mW/cm2 simulated solar light by adjusting the PEDOT:PSS and GO mixing concentration ratio. The GO addition to conductive PEDOT:PSS suppressed electron recombination and/or promoted the hole current at the anode. The soluble PEDOT:PSS:GO composite is promising as a hole-transporting transparent conducting layer for c-Si photovoltaic applications.

  2. Morphological Control of Poly(ethylene oxide)/Polystyrene Blend Thin Films by Using Supercritical Carbon Dioxide

    NASA Astrophysics Data System (ADS)

    Chen, Xiameng

    Polymer blend thin films have been paid great attention to technological applications including adhesion, coatings, liquid crystal alignment, electronics, optics, biotechnology, and sensors. In this thesis, I investigated the effect of supercritical CO2 (scCO2) as a green solvent for poly(ethylene oxide)/polystyrene (PEO/PS) blend thin films. We prepared a series of PEO/PS blend thin films with different PEO compositions thickness ranging from 20 nm to 50 nm. As a control experiment, we also processed the same PEO/PS films at high temperature (150 °C) under vacuum. Comparison of these experimental results by using atomic force microscopy and optical microscopy clarified the significant plasticization effect of scCO2 on the phase separation, crystallization of PEO, and the swelling behavior of PS.

  3. The effect of ethylene oxide sterilization on the surface chemistry and in vitro cytotoxicity of several kinds of chitosan.

    PubMed

    França, Rodrigo; Mbeh, Doris A; Samani, Taraneh Djavanbakht; Le Tien, Canh; Mateescu, Mircea A; Yahia, L'hocine; Sacher, Edward

    2013-06-01

    The surfaces of three chitosan samples, differing only in their degrees of deacetylation and of carboxyethyl chitosan were chemically characterized by X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectroscopy, X-ray diffraction, and Fourier transform infrared, both before and after sterilization with ethylene oxide. Unexpected elemental ratios suggest that surface chemical modification occurred during the processing of the original chitin, with further surface modification on subsequent sterilization, despite previous reports to the contrary. Cell viability was evaluated by direct contact methyl thiazole tetrazolium and lactate dehydrogenase assays between the chitosan particles and A549 human epithelial cells, which demonstrated that the modifications incurred on sterilization are reflected in biocompatibility changes. All the samples were found to be biocompatible and nontoxic before sterilization and remained so subsequently. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013. PMID:23744606

  4. The effect of ethylene oxide sterilization on the surface chemistry and in vitro cytotoxicity of several kinds of chitosan.

    PubMed

    França, Rodrigo; Mbeh, Doris A; Samani, Taraneh Djavanbakht; Le Tien, Canh; Mateescu, Mircea A; Yahia, L'Hocine; Sacher, Edward

    2013-11-01

    The surfaces of three chitosan samples, differing only in their degrees of deacetylation and of carboxyethyl chitosan were chemically characterized by X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectroscopy, X-ray diffraction, and Fourier transform infrared, both before and after sterilization with ethylene oxide. Unexpected elemental ratios suggest that surface chemical modification occurred during the processing of the original chitin, with further surface modification on subsequent sterilization, despite previous reports to the contrary. Cell viability was evaluated by direct contact methyl thiazole tetrazolium and lactate dehydrogenase assays between the chitosan particles and A549 human epithelial cells, which demonstrated that the modifications incurred on sterilization are reflected in biocompatibility changes. All the samples were found to be biocompatible and nontoxic before sterilization and remained so subsequently. PMID:24591223

  5. Organosilicon compounds containing nitrile and oligo(ethylene oxide) substituents as safe electrolytes for high-voltage lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Yong, Tianqiao; Wang, Jinglun; Mai, Yongjin; Zhao, Xinyue; Luo, Hao; Zhang, Lingzhi

    2014-05-01

    Organosilicon compounds containing nitrile and oligo(ethylene oxide) substituents are synthesized as safe electrolytes for high-voltage lithium-ion batteries. We firstly report that these organosilicon electrolytes could be stably cycled at an upper cutoff voltage of 4.4 V in LiCoO2/graphite full cells.

  6. Miscibility of poly(lactic acid) and poly(ethylene oxide) solvent polymer blends and nanofibers made by solution blow spinning

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The miscibility of blends of poly(lactic acid) (PLA) and poly(ethylene oxide) (PEO) was studied in polymer solutions by dilute solution viscometry and in solution blow spun nanofibers by microscopy (SEM, TEM) and by thermal and spectral analysis. Three blends of PLA and PEO were solution blended in...

  7. Characterization and assessment of a novel poly(ethylene oxide)/polyurethane composite hydrogel (Aquavene) as a ureteral stent biomaterial.

    PubMed

    Gorman, S P; Tunney, M M; Keane, P F; Van Bladel, K; Bley, B

    1998-03-15

    The effective long-term use of indwelling ureteral stents is often hindered by the formation of encrusting deposits which may cause obstruction and blockage of the stent. Development of improved ureteral stent biomaterials capable of preventing or reducing encrustation is therefore particularly desirable. In this study, the suitability as a ureteral stent biomaterial of Aquavene, a novel poly(ethylene oxide)/polyurethane composite hydrogel was compared with that of silicone and polyurethane, two materials widely employed in ureteral stent manufacture. Examination of Aquavene in dry and hydrated states by confocal laser scanning microscopy, scanning electron microscopy, and atomic force microscopy showed the presence of numerous channels within a cellular matrix structure. The channel size increased considerably to as much as 10 microm in diameter in the hydrated state. Aquavene provided superior resistance to encrustation and intraluminal blockage over a 24-week period in a simulated urine flow model. Unobstructed urine flow continued with Aquavene at 24 weeks, whereas silicone and polyurethane stents became blocked with encrustation at 8 and 10 weeks, respectively. Weight loss within Aquavene on the order of 9% (w/w) over the 24-week flow period indicates that extraction of the noncrosslinked poly(ethylene oxide) hydrogel may be responsible for the prevention of encrustation blockage of this biomaterial. In the dry state, Aquavene was significantly harder than either silicone or polyurethane, as shown by Young's modulus, and rapidly became soft on hydration. These additional properties of Aquavene would facilitate ease of stent insertion in the dry state past obstructions in the ureter and provide improved patient comfort on subsequent biomaterial hydration in situ. Aquavene is a promising candidate for use in the urinary tract, as it is probable that effective long-term urine drainage would be maintained in vivo. Further evaluation of this novel biomaterial is

  8. Individual Shrink Wrapping of Zucchini Fruit Improves Postharvest Chilling Tolerance Associated with a Reduction in Ethylene Production and Oxidative Stress Metabolites

    PubMed Central

    Megías, Zoraida; Martínez, Cecilia; Manzano, Susana; García, Alicia; Rebolloso-Fuentes, María del Mar; Garrido, Dolores; Valenzuela, Juan Luis; Jamilena, Manuel

    2015-01-01

    We have studied the effect of individual shrink wrapping (ISW) on the postharvest performance of refrigerated fruit from two zucchini cultivars that differ in their sensitivity to cold storage: Sinatra (more sensitive) and Natura (more tolerant). The fruit was individually shrink wrapped before storing at 4°C for 0, 7 and 14 days. Quality parameters, ethylene and CO2 productions, ethylene gene expression, and oxidative stress metabolites were assessed in shrink wrapped and non-wrapped fruit after conditioning the fruit for 6 hours at 20°C. ISW decreased significantly the postharvest deterioration of chilled zucchini in both cultivars. Weight loss was reduced to less than 1%, pitting symptoms were completely absent in ISW fruit at 7 days, and were less than 25% those of control fruits at 14 days of cold storage, and firmness loss was significantly reduced in the cultivar Sinatra. These enhancements in quality of ISW fruit were associated with a significant reduction in cold-induced ethylene production, in the respiration rate, and in the level of oxidative stress metabolites such as hydrogen peroxide and malonyldialdehyde (MDA). A detailed expression analysis of ethylene biosynthesis, perception and signaling genes demonstrated a downregulation of CpACS1 and CpACO1 genes in response to ISW, two genes that are upregulated by cold storage. However, the expression patterns of six other ethylene biosynthesis genes (CpACS2 to CpACS7) and five ethylene signal transduction pathway genes (CpCTR1, CpETR1, CpERS1, CpEIN3.1 and CpEN3.2), suggest that they do not play a major role in response to cold storage and ISW packaging. In conclusion, ISW zucchini packaging resulted in improved tolerance to chilling concomitantly with a reduction in oxidative stress, respiration rate and ethylene production, as well as in the expression of ethylene biosynthesis genes, but not of those involved in ethylene perception and sensitivity. PMID:26177024

  9. Individual Shrink Wrapping of Zucchini Fruit Improves Postharvest Chilling Tolerance Associated with a Reduction in Ethylene Production and Oxidative Stress Metabolites.

    PubMed

    Megías, Zoraida; Martínez, Cecilia; Manzano, Susana; García, Alicia; Rebolloso-Fuentes, María Del Mar; Garrido, Dolores; Valenzuela, Juan Luis; Jamilena, Manuel

    2015-01-01

    We have studied the effect of individual shrink wrapping (ISW) on the postharvest performance of refrigerated fruit from two zucchini cultivars that differ in their sensitivity to cold storage: Sinatra (more sensitive) and Natura (more tolerant). The fruit was individually shrink wrapped before storing at 4°C for 0, 7 and 14 days. Quality parameters, ethylene and CO2 productions, ethylene gene expression, and oxidative stress metabolites were assessed in shrink wrapped and non-wrapped fruit after conditioning the fruit for 6 hours at 20°C. ISW decreased significantly the postharvest deterioration of chilled zucchini in both cultivars. Weight loss was reduced to less than 1%, pitting symptoms were completely absent in ISW fruit at 7 days, and were less than 25% those of control fruits at 14 days of cold storage, and firmness loss was significantly reduced in the cultivar Sinatra. These enhancements in quality of ISW fruit were associated with a significant reduction in cold-induced ethylene production, in the respiration rate, and in the level of oxidative stress metabolites such as hydrogen peroxide and malonyldialdehyde (MDA). A detailed expression analysis of ethylene biosynthesis, perception and signaling genes demonstrated a downregulation of CpACS1 and CpACO1 genes in response to ISW, two genes that are upregulated by cold storage. However, the expression patterns of six other ethylene biosynthesis genes (CpACS2 to CpACS7) and five ethylene signal transduction pathway genes (CpCTR1, CpETR1, CpERS1, CpEIN3.1 and CpEN3.2), suggest that they do not play a major role in response to cold storage and ISW packaging. In conclusion, ISW zucchini packaging resulted in improved tolerance to chilling concomitantly with a reduction in oxidative stress, respiration rate and ethylene production, as well as in the expression of ethylene biosynthesis genes, but not of those involved in ethylene perception and sensitivity. PMID:26177024

  10. [A chromatographic and surface-activity analysis of the fractions of Rokopols, block copolymers of propylene oxide and ethylene oxide separated from the technical product].

    PubMed

    Zgoda, Marian Mikołaj; Nachajski, Michał Jakub

    2008-01-01

    A metod of refininig technical Rokopols, products of copolymerization of ethylene oxide and propylene oxide of 30p160, 30p27 and 30p10 type was developed. The course of the relation between R(f)(R(m)) and the number of oxyethylene segments n(TE) in the molecule of the homological series ofpolyethyleneglycols (PEG) was used to examine the content of n(TE) in the refined fractions of Rokopols. For the aqueous solutions of Rokopols weight-average molecular mass M(w) was calculated and the surface tension coefficient gamma25 was determined on the basis of the stalgmometric method. The value of the critical micellar concentration (cmc) and the thermodynamic potential for micelle formation (DeltaG(m)(0)), which facilitates the assessment of the solubilizing abilities of the investigated class of copolymers, were estimated. PMID:19137973

  11. Destructive Clustering of Metal Nanoparticles in Chalcogenide and Oxide Glassy Matrices

    NASA Astrophysics Data System (ADS)

    Shpotyuk, M. V.; Shpotyuk, O. I.; Cebulski, J.; Kozyukhin, S.

    2016-01-01

    The energetic χ-criterion is developed to parameterize difference in the origin of high-order optical non-linearity associated with metallic atoms (Cu, Ag, Au) embedded destructively in oxide- and chalcogenide glasses. Within this approach, it is unambiguously proved that covalent-bonded networks of soft semiconductor chalcogenides exemplified by binary As(Ge)-S(Se) glasses differ essentially from those typical for hard dielectric oxides like vitreous silica by impossibility to accommodate pure agglomerates of metallic nanoparticles. In an excellence according to known experimental data, it is suggested that destructive clustering of nanoparticles is possible in Cu-, Ag-, and Au-ion-implanted dielectric oxide glass media, possessing a strongly negative χ-criterion. Some recent speculations trying to ascribe equally this ability to soft chalcogenide glasses despite an obvious difference in the corresponding bond dissociation energies have been disclosed and criticized as inconclusive.

  12. Destructive Clustering of Metal Nanoparticles in Chalcogenide and Oxide Glassy Matrices.

    PubMed

    Shpotyuk, M V; Shpotyuk, O I; Cebulski, J; Kozyukhin, S

    2016-12-01

    The energetic χ-criterion is developed to parameterize difference in the origin of high-order optical non-linearity associated with metallic atoms (Cu, Ag, Au) embedded destructively in oxide- and chalcogenide glasses. Within this approach, it is unambiguously proved that covalent-bonded networks of soft semiconductor chalcogenides exemplified by binary As(Ge)-S(Se) glasses differ essentially from those typical for hard dielectric oxides like vitreous silica by impossibility to accommodate pure agglomerates of metallic nanoparticles. In an excellence according to known experimental data, it is suggested that destructive clustering of nanoparticles is possible in Cu-, Ag-, and Au-ion-implanted dielectric oxide glass media, possessing a strongly negative χ-criterion. Some recent speculations trying to ascribe equally this ability to soft chalcogenide glasses despite an obvious difference in the corresponding bond dissociation energies have been disclosed and criticized as inconclusive. PMID:26787053

  13. Induction of glutathione-S-transferase and heat-shock proteins in rat liver after ethylene oxide exposure.

    PubMed

    Katoh, T; Ohmori, H; Murakami, T; Karasaki, Y; Higashi, K; Muramatsu, M

    1991-08-22

    Defense mechanisms in rat liver against depletion of glutathione (GSH) and cellular injuries induced by ethylene oxide (EO) were studied. Rats were exposed to EO under either high dose (1300 ppm for 4 hr, once) or low dose (500 ppm for 6 hr, three times a week for 6 weeks) conditions. The hepatic content of GSH decreased dramatically after EO treatment, probably due to detoxication of EO. After the high dose treatment the hepatic GSH content fell by 90% of the control values but recovered within 10 to 15 hr. EO reacts directly with a variety of cellular macromolecules but all rats survived the exposure. Since the metabolites of EO are ethylene glycol and GSH-conjugates, the enzymatic activities of epoxide hydrolase and glutathione-S-transferase (GST) were determined. Only GST activity was found to occur after low dose chronic exposure. The defense mechanism at mRNA level was investigated using probes for GST and several heat-shock proteins (hsps). Enhanced accumulation of GST mRNA was detectable during the recovery period of rats after both high and low dose exposure to EO. Interestingly, both hsp32 (less than 40-fold) and hsp90 (less than 3-fold) mRNA increased after high dose exposure but the mRNA level of one of the major heat-shock proteins, hsp70, did not change under these conditions. Diethylmaleate, which is known to be a GSH depleter in liver, induced hsp32 mRNA only in rat liver, while hsp70 and hsp90 mRNA levels did not change when GSH was depleted. These results suggest that individual heat-shock proteins are induced in different ways under unphysiological conditions such as EO exposure. PMID:1888334

  14. One-step sonochemical synthesis of a graphene oxide-manganese oxide nanocomposite for catalytic glycolysis of poly(ethylene terephthalate)

    NASA Astrophysics Data System (ADS)

    Park, Gle; Bartolome, Leian; Lee, Kyoung G.; Lee, Seok Jae; Kim, Do Hyun; Park, Tae Jung

    2012-06-01

    Ultrasound-assisted synthesis of a graphene oxide (GO)-manganese oxide nanocomposite (GO-Mn3O4) was conducted without further modification of GO or employing secondary materials. With the GO nanoplate as a support, potassium permanganate oxidizes the carbon atoms in the GO support and gets reduced to Mn3O4. An intensive ultrasound method could reduce the number of reaction steps and temperature, enhance the reaction rate and furthermore achieve a Mn3O4 phase. The composite was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The coverage and crystallinity of Mn3O4 were controlled by changing the ratio of permanganate to GO dispersion. The synthesized nanocomposite was used as a catalyst for poly(ethylene terephthalate) (PET) depolymerization into its monomer, bis(2-hydroxylethyl) terephthalate (BHET). The highest monomer yield of 96.4% was obtained with the nanocomposite containing the lowest amount of Mn3O4, while PET glycolysis with the Mn3O4 without GO yielded 82.7% BHET.Ultrasound-assisted synthesis of a graphene oxide (GO)-manganese oxide nanocomposite (GO-Mn3O4) was conducted without further modification of GO or employing secondary materials. With the GO nanoplate as a support, potassium permanganate oxidizes the carbon atoms in the GO support and gets reduced to Mn3O4. An intensive ultrasound method could reduce the number of reaction steps and temperature, enhance the reaction rate and furthermore achieve a Mn3O4 phase. The composite was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The coverage and crystallinity of Mn3O4 were controlled by changing the ratio of permanganate to GO dispersion. The synthesized nanocomposite was used as a catalyst for poly(ethylene

  15. Ethylene production from methionine

    PubMed Central

    Lieberman, M.; Kunishi, A. T.; Mapson, L. W.; Wardale, D. A.

    1965-01-01

    1. A new reaction is described in which ethylene is formed from the Cu+-catalysed breakdown of methionine in phosphate buffer at 30° in air. Some of the other products of the reaction are methionine sulphone, methionine sulphoxide, homocysteic acid, homocystine, acrolein, dimethyl disulphide, methanethiol, ethyl methyl sulphide, methane and ethane. These are considered to be produced in different reaction pathways. 2. Hydrogen peroxide is an intermediate in this reaction and can support ethylene production in the model system in anaerobic atmospheres. Cuprous copper is the active form that catalyses the formation of ethylene from an oxidized intermediate. The initial reaction is probably a Strecker degradation, but the aldehyde product is further degraded to ethylene and other products. 3. Methional (CH3·S·CH2·CH2·CHO) is the most effective producer of ethylene in the model system and appears to be an intermediate in the reaction. 4. The evidence, from both tracer studies and from other precursors of ethylene in the reaction, indicates that ethylene is derived from the −CH2·CH2− group of methionine. PMID:16749150

  16. One step growth of protein antifouling surfaces: monolayers of poly(ethylene oxide) (PEO) derivatives on oxidized and hydrogen-passivated silicon surfaces.

    PubMed

    Cecchet, Francesca; De Meersman, Benoît; Demoustier-Champagne, Sophie; Nysten, Bernard; Jonas, Alain M

    2006-01-31

    We compare two routes for creating protein adsorption-resistant self-assembled monolayers (SAMs) by chemical modification of silicon surfaces with poly(ethylene oxide) (PEO) oligomeric derivatives. The first route involves the assembly of 2-methyl[(polyethyleneoxy)propyl]trichlorosilane (Cl3SiMPEO) films onto oxidized silicon surfaces (OH-SiO(x)) either by a liquid-phase process at room temperature or by a gas-phase process at 423 K, producing Si-O-Si bonds between the substrate and the organic layer. The second pathway makes use of the assembly of poly(ethylene glycol methyl ether) (MPEG) films onto hydrogen-passivated silicon surfaces (H-Si) using a liquid-phase process at 353 or 423 K, leading to the formation of Si-O-C bonds between the substrate and the organic layer. Structural investigation by X-ray reflectometry (XRR) reveals that the thickness and surface densities of the grafted PEO monolayers strongly depend on experimental conditions such as temperature and grafting time. Atomic force microscopy (AFM) shows that very smooth and homogeneous monolayers can be obtained with average roughnesses close to those measured on the corresponding bare substrates. Finally, the antifouling properties of the modified silicon surfaces were evaluated by X-ray photoelectron spectroscopy (XPS), using a membrane protein (P.69 antigen) as model protein. Both types of PEO monolayers exhibit excellent protein repellency, as soon as the grafting density is equal to or higher than 1.7 chains/nm2. PMID:16430281

  17. Development of Iron-Chelating Poly(ethylene terephthalate) Packaging for Inhibiting Lipid Oxidation in Oil-in-Water Emulsions.

    PubMed

    Johnson, David R; Tian, Fang; Roman, Maxine J; Decker, Eric A; Goddard, Julie M

    2015-05-27

    Foods such as bulk oils, salad dressings, and nutritionally fortified beverages that are susceptible to oxidative degradation are often packaged in poly(ethylene terephthalate) (PET) bottles with metal chelators added to the food to maintain product quality. In the present work, a metal-chelating active packaging material is designed and characterized, in which poly(hydroxamic acid) (PHA) metal-chelating moieties were grafted from the surface of PET. Biomimetic PHA groups were grafted in a two-step UV-initiated process without the use of a photoinitiator. Surface characterization of the films by attenuated total reflective Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM) suggested successful grafting and conversion of poly(hydroxyethyl acrylate) (PHEA) to PHA chelating moieties from the surface of PET. Colorimetric (ferrozine) and inductively coupled plasma mass spectroscopy (ICP-MS) assays demonstrated the ability of PET-g-PHA to chelate iron in a low-pH (3.0) environment containing a competitive metal chelator (citric acid). Lipid oxidation studies demonstrated the antioxidant activity of PET-g-PHA films in inhibiting iron-promoted oxidation in an acidified oil-in-water (O/W) emulsion model system (pH 3.0). Particle size and ζ-potential analysis indicated that the addition of PET-g-PHA films did not affect the physical stability of the emulsion system. This work suggests that biomimetic chelating moieties can be grafted from PET and effectively inhibit iron-promoted degradation reactions, enabling removal of metal-chelating additives from product formulations. PMID:25985711

  18. One-step sonochemical synthesis of a graphene oxide-manganese oxide nanocomposite for catalytic glycolysis of poly(ethylene terephthalate).

    PubMed

    Park, Gle; Bartolome, Leian; Lee, Kyoung G; Lee, Seok Jae; Kim, Do Hyun; Park, Tae Jung

    2012-07-01

    Ultrasound-assisted synthesis of a graphene oxide (GO)-manganese oxide nanocomposite (GO-Mn(3)O(4)) was conducted without further modification of GO or employing secondary materials. With the GO nanoplate as a support, potassium permanganate oxidizes the carbon atoms in the GO support and gets reduced to Mn(3)O(4). An intensive ultrasound method could reduce the number of reaction steps and temperature, enhance the reaction rate and furthermore achieve a Mn(3)O(4) phase. The composite was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The coverage and crystallinity of Mn(3)O(4) were controlled by changing the ratio of permanganate to GO dispersion. The synthesized nanocomposite was used as a catalyst for poly(ethylene terephthalate) (PET) depolymerization into its monomer, bis(2-hydroxylethyl) terephthalate (BHET). The highest monomer yield of 96.4% was obtained with the nanocomposite containing the lowest amount of Mn(3)O(4), while PET glycolysis with the Mn(3)O(4) without GO yielded 82.7% BHET. PMID:22592889

  19. Novel composite materials synthesized by the high-temperature interaction of pyrrole with layered oxide matrices

    NASA Astrophysics Data System (ADS)

    Pavel, Alexandru Cezar

    The initial goal of the research presented herein was to develop the very first synthetic metal---high-temperature superconductor ceramic composite material, in the specific form of a polypyrrole---Bi2Sr2CaCu 2O8+delta nanocomposite. In the course of scientific investigation, this scope was broadened to encompass structurally and compositionally similar layered bismuthates and simpler layered oxides. The latter substrates were prepared through novel experimental procedures that enhanced the chance of yielding nanostructured morphologies. The designed novel synthesis approaches yielded a harvest of interesting results that may be further developed upon their dissemination in the scientific community. High-temperature interaction of pyrrole with molybdenum trioxide substrates with different crystalline phases and morphologies led to the formation of the first members of a new class of heterogeneous microcomposites characterized by incomplete occupancy by the metal oxide core of the volume encapsulated by the rigid, amorphous permeable polymeric membrane that reproduces the volume of the initial grain of precursor substrate. The method may be applied for various heterogeneous catalyst substrates for the precise determination of the catalytically active crystallographic planes. In a different project, room-temperature, templateless impregnation of molybdenum trioxide substrates with different crystalline phases and morphologies by a large excess of silver (I) cations led to the formation of 1-D nanostructured novel Ag-Mo-O ternary phase in what may be the simplest experimental procedure available to date that has yielded a 1-D nanostructure, regardless the nature of the constituent material. Interaction of this novel ternary phase with pyrrole vapors at high reaction temperatures led to heterogeneous nanostructured composites that exhibited a silver nanorod core. Nanoscrolls of vanadium pentoxide xerogel were synthesized through a novel, facile reflux-based method that

  20. Synthesis of polymer electrolyte membranes from cellulose acetate/poly(ethylene oxide)/LiClO4 for lithium ion battery application

    NASA Astrophysics Data System (ADS)

    Nurhadini, Arcana, I. Made

    2015-09-01

    This study was conducted to determine the effect of cellulose acetate on poly(ethylene oxide)-LiClO4 membranes as the polymer electrolyte. Cellulose acetate is used as an additive to increase ionic conductivity and mechanical property of polymer electrolyte membranes. The increase the percentage of cellulose acetate in membranes do not directly effect on the ionic conductivity, and the highest ionic conductivity of membranes about 5,7 × 10-4 S/cm was observed in SA/PEO/LiClO4 membrane with cellulose ratio of 10-25% (w/w). Cellulose acetate in membranes increases mechanical strength of polymer electrolyte membranes. Based on TGA analysis, this polymer electrolyte thermally is stable until 270 °C. The polymer electrolyte membrane prepared by blending the cellulose acetate, poly(ethylene oxide), and lithium chlorate could be potentially used as a polymer electrolyte for lithium ion battery application.

  1. Synthesis of polymer electrolyte membranes from cellulose acetate/poly(ethylene oxide)/LiClO{sub 4} for lithium ion battery application

    SciTech Connect

    Nurhadini, Arcana, I Made

    2015-09-30

    This study was conducted to determine the effect of cellulose acetate on poly(ethylene oxide)-LiClO{sub 4} membranes as the polymer electrolyte. Cellulose acetate is used as an additive to increase ionic conductivity and mechanical property of polymer electrolyte membranes. The increase the percentage of cellulose acetate in membranes do not directly effect on the ionic conductivity, and the highest ionic conductivity of membranes about 5,7 × 10{sup −4} S/cm was observed in SA/PEO/LiClO{sub 4} membrane with cellulose ratio of 10-25% (w/w). Cellulose acetate in membranes increases mechanical strength of polymer electrolyte membranes. Based on TGA analysis, this polymer electrolyte thermally is stable until 270 °C. The polymer electrolyte membrane prepared by blending the cellulose acetate, poly(ethylene oxide), and lithium chlorate could be potentially used as a polymer electrolyte for lithium ion battery application.

  2. Interaction of poly(ethylene oxide) with the sodium dodecyl sulfate micelle interface studied with nitroxide spin probes

    SciTech Connect

    Kang, Y.S.; Kevan, L. )

    1994-08-04

    Electron spin resonance (ESR) line widths of 5-, 7-, 12-, and 16-doxylstearic acid (x-DSA) and tempo nitroxides versus the concentration of poly(ethylene oxide) (PEO) in sodium dodecyl sulfate (SDS) micelles show different trends. The ESR line widths of 5-, 7-, and 16-DSA increase with increasing concentration of PEO, which is interpreted as due to increasing viscosity in the environment of the nitroxide spin probe. The tempo and 12-DSA line widths were independent of the concentration of PEO. The line width showed the highest value for 5-DSA and the lowest value of tempo. The line width of x-DSA decreases from 5-DSA to a minimum value for 12-DSA and then increases somewhat for 16-DSA. This is interpreted as bending of the alkyl chain to provide different locations for the nitroxide moiety relative to the micelle interface. The relative distances of the nitroxide moiety of [chi]-DSA from deuterated water at the SDS micelle interface was measured by deuterium electron spin echo modulation. The distances increased from 5-DSA to 12-DSA and then decreased for 16-DSA. The interpretation of the DSR line width trend is supported by the deuterium modulation depth trend. 28 refs., 5 figs., 2 tabs.

  3. Characterization of predominantly hydrophobic poly(styrene)-poly(ethylene oxide) copolymers at air/water and cyclohexane/water interfaces

    SciTech Connect

    Gragson, D.E.; Jensen, J.M.; Baker, S.M.

    1999-09-14

    Interfacial tension measurements are employed to explore the spreading behavior of predominantly hydrophobic poly(styrene)--poly(ethylene oxide), PS-PEO, diblock copolymers at air/water and cyclohexane/water interfaces. Two copolymers with 7%- and 15.5%-PEO are examined in this study. The former is expected to have a PS block limiting area in air roughly equal to the limiting PEO pancake area, whereas the latter is expected to have a limiting PS block area in air approximately 3 times smaller than the limiting PEO pancake area. At the air/water interface, the 7%-PEO copolymer does not spread well, which is attributed to interference from the hydrophobic PS block. In contrast, the 7%-PEO copolymer spreads well at the cyclohexane/water interface, producing an isotherm with a terminating mean molecular area 3 times smaller than that obtained at the air/water interface. The 15.5%-PEO copolymer spreads well at both the air/water ad cyclohexane/water interfaces due to less interference from the smaller hydrophobic PS block. These observations are compared to compression isotherms, and the results are discussed in terms of the solvating nature of the adjacent cyclohexane phase for the PS block.

  4. Phase Behavior and Ionic Conductivity of Concentrated Solutions of Polystyrene-Poly(ethylene oxide) Diblock Copolymers in an Ionic Liquid

    SciTech Connect

    Simone, Peter M.; Lodge, Timothy P.

    2010-03-16

    Concentrated solutions of poly(styrene-b-ethylene oxide) (PS-PEO) diblock copolymers were prepared using the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [EMI][TFSI] as the solvent. The self-assembled microstructures adopted by the copolymer solutions have been characterized using small-angle X-ray scattering. Lyotropic mesophase transitions were observed, with a progression from hexagonally packed cylinders of PEO, to lamellae, to hexagonally packed cylinders of PS upon increasing [EMI][TFSI] content. The change in lamellar domain spacing with ionic liquid concentration was found to be comparable to that reported for other block copolymers in strongly selective solvents. The ionic conductivity of the concentrated PS-PEO/[EMI][TFSI] solutions was measured via impedance spectroscopy, and ranged from 1 x 10{sup -7} to 1 x 10{sup -3} S/cm at temperatures from 25-100 C. Additionally, the ionic conductivity of the solutions was found to increase with both ionic liquid concentration and molecular weight of the PEO blocks. The ionic conductivity of PEO homopolymer/[EMI][TFSI] solutions was also measured in order to compare the conductivity of the PS-PEO solutions to the expected limit for a lamellar sample with randomly oriented microstructure grains.

  5. Lyotropic Phase Behavior of Poly(ethylene oxide)-Poly(butadiene) Diblock Copolymers: Evolution of the Random Network Morphology

    SciTech Connect

    Jain, Sumeet; Dyrdahl, Mitchell H.E.; Gong, Xiaobo; Scriven, L.E.; Bates, Frank S.

    2008-10-24

    The phase behavior of poly(ethylene oxide)-poly(butadiene) (PEO-PB) diblock copolymers mixed with water was studied using small-angle X-ray scattering (SAXS), cryogenic scanning electron microscopy (cryo-SEM), cryogenic transmission electron microscopy (cryo-TEM), and dynamic mechanical spectroscopy. Two sets of diblocks were synthesized by adding different lengths of PEO to hydroxy terminated PB with degrees of polymerization N{sub PB} = 46 and 170. Two-component mixtures were investigated as a function of block composition and copolymer molecular weight, between 1 and 100 wt % polymer content. Melt phase behavior is consistent with established theory and known experimental behavior for diblock copolymers. Various lyotropic liquid crystalline structures, notably lamellae (L), hexagonally packed cylinders (H), and spheres (S) arranged on cubic (body-centered cubic, face-centered cubic) lattices, were documented as a function of water content. At the higher molecular weights (N{sub PB} = 170), a random network phase (N) was identified over a sizable portion of the phase portrait, located between hexagonally ordered cylinders and ordered lamellae. This new structure, along with branching of cylindrical micelles in the dilute limit, bear a striking similarity to experimentally observed and theoretically predicted phase behavior in certain ternary water/oil/surfactant systems. These findings demonstrate that block copolymer surfactants are characterized by at least four structural building blocks -- spheres, cylinders, bilayers, and branched cylinders -- above a threshold molecular weight.

  6. Poly(ethylene oxide)-Assisted Macromolecular Self-Assembly of Lignin in ABS Matrix for Sustainable Composite Applications

    DOE PAGESBeta

    Akato, Kokouvi M.; Tran, Chau D.; Chen, Jihua; Naskar, Amit K.

    2015-11-05

    Here we report the compatibilization of biomass-derived lignin polymer in acrylonitrile butadiene styrene (ABS) thermoplastic matrix without loss of mechanical properties via poly(ethylene oxide) (PEO)-mediated macromolecular self-assembly. ABS was blended with lignin in different concentrations, and blends with 10 wt % PEO (relative to lignin) were prepared. The relative tensile strength improved slightly at low lignin content but diminished rapidly as the lignin content was increased. However, the inclusion of PEO as an interfacial adhesion promoter helped avoid deleterious effects. Dynamic mechanical analysis showed that PEO plasticized the hard phase and thus lowered the activation energy (Ea) for its relaxationmore » but caused stiffening of the soft phase and increased its Ea. Microscopy revealed that incorporating lignin in ABS led to the statistical dispersion of discrete lignin domains (300–1000 nm) which, after PEO addition, were reduced to smaller interconnected particles (200–500 nm). The lignin-extended partially renewable ABS resins showed shear-thinning behavior and reduced viscosity compared to neat ABS. The preferred lignin-loaded compositions reinforced with 20 vol % chopped carbon fibers exhibited mechanical performances (77–80 MPa) equivalent to those of reinforced ABS materials reportedly used in 3D printing applications. In conclusion, this approach could lower the cost of ABS while reducing its carbon footprint.« less

  7. Polymer-Ion Interaction Weakens the Strain-Rate Dependence of Extension-Induced Crystallization for Poly(ethylene oxide).

    PubMed

    Hu, Tingting; Tian, Nan; Ali, Sarmad; Wang, Zhen; Chang, Jiarui; Huang, Ningdong; Li, Liangbin

    2016-03-01

    The crystallization of poly(ethylene oxide) (PEO)-sodium iodine (NaI) composites is investigated by differential scanning calorimetry (DSC), extensional rheology, and in situ small-angle X-ray scattering (SAXS) with the aim of demonstrating versatile roles played by polymer-ion interactions. In the isothermal quiescent crystallization process, a decrease in the crystal growth rate is observed for PEO-NaI and is attributed to slow chain movement caused by the coordination between cations and polymer. In situ SAXS on extensional flow-induced crystallization (FIC) exhibits enhanced kinetics and orientation for both PEO and PEO-NaI with increasing strain rate. However, an overall weaker strain-rate dependence of FIC is observed for PEO-NaI, which can be interpreted as a synergistic consequence of promoted nucleation under flow and impeded crystal growth by polymer-ion interaction. A possible microscopic mechanism is proposed to account for the experimental observation based on the formation of transient cross-linking points in PEO-NaI and their influence on the entanglement network of polymer under various flow fields. The disclosed strain-rate dependence and various ion effects on the behavior of PEO-salt composites contribute to a comprehensive understanding of polymer-ion solid polyelectrolytes. PMID:26822166

  8. Enhanced luminescence properties of highly threaded conjugated polyelectrolytes with potassium counter-ions upon blending with poly(ethylene oxide)

    NASA Astrophysics Data System (ADS)

    Latini, Gianluca; Winroth, Gustaf; Brovelli, Sergio; McDonnell, Shane O.; Anderson, Harry L.; Mativetsky, Jeffrey M.; Samorı, Paolo; Cacialli, Franco

    2010-06-01

    The photophysics and electroluminescence (EL) of thin films of unthreaded and cyclodextrin-encapsulated poly(4,4'-diphenylenevinylene) (PDV) with potassium countercations, blended with poly(ethylene oxide) (PEO) are investigated as a function of the PEO concentration. We show that three main factors contribute to increasing the photoluminescence (PL) quantum efficiency as a result of suppressed intermolecular interactions, namely: the high degree of encapsulation of the polyrotaxanes, the relatively large countercation (e.g., compared to lithium), and the complexation of the rotaxanes with PEO. By facilitating cationic transport to the negative electrodes, PEO also leads to devices with enhanced electron injection and improved charge balance, whose operation therefore resembles that of "virtually unipolar" light-emitting electrochemical cells. This effect, together with the enhanced PL efficiency, leads to higher EL efficiency for both polyrotaxanes and unthreaded polymers, upon addition of the PEO. We show that the concurrent exploitation of the various strategies above lead to an overall EL efficiency that is approximately twice the value previously reported for Li-based PDV. A blueshift of the EL spectrum during the devices turn-on is also reported and analyzed in terms of interference and doping effects.

  9. SPECT/CT Imaging of Pluronic Nanocarriers with Varying Poly(ethylene oxide) Block Length and Aggregation State.

    PubMed

    Arranja, Alexandra; Ivashchenko, Oleksandra; Denkova, Antonia G; Morawska, Karolina; van Vlierberghe, Sandra; Dubruel, Peter; Waton, Gilles; Beekman, Freek J; Schosseler, François; Mendes, Eduardo

    2016-03-01

    Optimal biodistribution and prolonged circulation of nanocarriers improve diagnostic and therapeutic effects of enhanced permeability and retention-based nanomedicines. Despite extensive use of Pluronics in polymer-based pharmaceuticals, the influence of different poly(ethylene oxide) (PEO) block length and aggregation state on the biodistribution of the carriers is rather unexplored. In this work, we studied these effects by evaluating the biodistribution of Pluronic unimers and cross-linked micelles with different PEO block size. In vivo biodistribution of (111)In-radiolabeled Pluronic nanocarriers was investigated in healthy mice using single photon emission computed tomography. All carriers show fast uptake in the organs from the reticuloendothelial system followed by a steady elimination through the hepatobiliary tract and renal filtration. The PEO block length affects the initial renal clearance of the compounds and the overall liver uptake. The aggregation state influences the long-term accumulation of the nanocarriers in the liver. We showed that the circulation time and elimination pathways can be tuned by varying the physicochemical properties of Pluronic copolymers. Our results can be beneficial for the design of future Pluronic-based nanomedicines. PMID:26883169

  10. Enhanced Catalytic Activities of NiPt Truncated Octahedral Nanoparticles toward Ethylene Glycol Oxidation and Oxygen Reduction in Alkaline Electrolyte.

    PubMed

    Xia, Tianyu; Liu, Jialong; Wang, Shouguo; Wang, Chao; Sun, Young; Gu, Lin; Wang, Rongming

    2016-05-01

    The high cost and poor durability of Pt nanoparticles (NPs) are great limits for the proton exchange membrane fuel cells (PEMFCs) from being scaled-up for commercial applications. Pt-based bimetallic NPs together with a uniform distribution can effectively reduce the usage of expensive Pt while increasing poison resistance of intermediates. In this work, a simple one-pot method was used to successfully synthesize ultrafine (about 7.5 nm) uniform NiPt truncated octahedral nanoparticles (TONPs) in dimethylformamid (DMF) without any seeds or templates. The as-prepared NiPt TONPs with Pt-rich surfaces exhibit greatly improved catalytic activities together with good tolerance and better stability for ethylene glycol oxidation reaction (EGOR) and oxygen reduction reaction (ORR) in comparison with NiPt NPs and commercial Pt/C catalysts in alkaline electrolyte. For example, the value of mass and specific activities for EGOR are 23.2 and 17.6 times higher comparing with those of commercial Pt/C, respectively. Our results demonstrate that the dramatic enhancement is mainly attributed to Pt-rich surface, larger specific surface area, together with coupling between Ni and Pt atoms. This developed method provides a promising pathway for simple preparation of highly efficient electrocatalysts for PEMFCs in the near future. PMID:27093304

  11. Mixed micellar nanoparticle of amphotericin B and poly styrene-block-poly ethylene oxide reduces nephrotoxicity but retains antifungal activity.

    PubMed

    Han, Kun; Miah, M A Jalil; Shanmugam, Srinivasan; Yong, Chul Soon; Choi, Han-Gon; Kim, Jung Ae; Yoo, Bong Kyu

    2007-10-01

    Mixed micellar nanoparticle consisting of amphotericin B (AmB) and poly styrene-block-poly ethylene oxide (PS-block-PEO) was prepared by high pressure homogenizer. Nephrotoxicity of the nanoparticle was investigated along with antifungal activity and self-aggregation status of the drug in the nanoparticle. Nephrotoxicity was markedly reduced when AmB was intravenously administered to rats as mixed micellar nanoparticle with PS-block-PEO in terms of transmission electron microscopy of tubular cells and creatinine clearance. Antifungal activity of AmB was not altered when the drug was in the form of mixed micellar nanoparticle compared to both conventional formulation and AmB micelle treated by same procedure without PS-block-PEO. Self-aggregation status of AmB molecules revealed monomeric in the mixed micellar nanoparticle with PS-block-PEO up to the therapeutic level of the drug (1-3 mM). The reduced nephrotoxicity of AmB in mixed micellar nanoparticle may be associated with the existence of the drug as monomeric form in the nanoparticle. Based on our result, formulation of AmB as mixed micellar nanoparticle with PS-block-PEO may be a promising alternative for the treatment of fungal diseases in patients who are at risk of renal dysfunction. PMID:18038914

  12. A bifunctional poly(ethylene glycol) silane immobilized on metallic oxide-based nanoparticles for conjugation with cell targeting agents

    SciTech Connect

    Kohler, Nathan J.; Fryxell, Glen E.; Zhang, Miqin

    2004-06-16

    A trifluoroethylester-terminal poly (ethylene glycol) (PEG) silane was synthesized and self-assembled on iron oxide nanoparticles. The nanoparticle system thus prepared has the flexibility to conjugate with cell targeting agents having either carboxylic and amine terminal groups for a number of biomedical applications, including magnetic resonance imaging (MRI) and controlled drug delivery. The trifluoroethylester silane was synthesized by modifying a PEG diacid to form the corresponding bistrifluoroethylester (TFEE), followed by a reaction with 3-aminopropyltriethoxysilane (APS). The APS coupled with PEG chains confers the stability of PEG self-assembled monolayers (SAMs) and increases the PEG packing density on nanoparticles by establishing hydrogen bonding between the carbonyl and amine groups present within the monolayer structure. The success of the synthesis of the PEG TEFE silane was confirmed with 1H NMR and Fourier transform infrared spectroscopy (FTIR). The conjugating flexibility of the PEG TEFE was demonstrated with folic acid having carboxylic acid groups and amine terminal groups respectively and confirmed by FTIR. TEM analysis showed the dispersion of nanoparticles before and after they were coated with PEG and folic acid.

  13. Polystyrene-poly(ethylene oxide) diblock copolymer: the effect of polystyrene and spreading concentration at the air/water interface.

    PubMed

    Glagola, Cameron P; Miceli, Lia M; Milchak, Marissa A; Halle, Emily H; Logan, Jennifer L

    2012-03-20

    Polystyrene-block-poly(ethylene oxide) (PS-PEO) is an amphiphilic diblock copolymer that undergoes microphase separation when spread at the air/water interface, forming nanosized domains. In this study, we investigate the impact of PS by examining a series of PS-PEO samples containing constant PEO (~17,000 g·mol(-1)) and variable PS (from 3600 to 200,000 g·mol(-1)) through isothermal characterization and atomic force microscopy (AFM). The polymers separated into two categories: predominantly hydrophobic and predominantly hydrophilic with a weight percent of PEO of ~20% providing the boundary between the two. AFM results indicated that predominantly hydrophilic PS-PEO forms dots while more hydrophobic samples yield a mixture of dots and spaghetti with continent-like structures appearing at ~7% PEO or less. These structures reflect a blend of polymer spreading, entanglement, and vitrification as the solvent evaporates. Changing the spreading concentration provides insight into this process with higher concentrations representing earlier kinetic stages and lower concentrations demonstrating later ones. Comparison of isothermal results and AFM analysis shows how polymer behavior at the air/water interface correlates with the observed nanostructures. Understanding the impact of polymer composition and spreading concentration is significant in leading to greater control over the nanostructures obtained through PS-PEO self-assembly and their eventual application as polymer templates. PMID:22339480

  14. Surfactant-assisted intercalation of high molecular weight poly(ethylene oxide) into vanadyl phosphate di-hydrate

    SciTech Connect

    Ferreira, Joao Paulo L.; Oliveira, Herenilton P.

    2012-03-15

    Graphical abstract: CuK{sub {alpha}} X-ray diffraction patterns of the VOPO{sub 4}/PEO (A) e VOPO{sub 4}/CTA (B) and VOPO{sub 4}/CTA/PEO (C). Highlights: Black-Right-Pointing-Pointer VOPO{sub 4}/PEO has been synthesized by using CTAB, thereby improving PEO intercalation. Black-Right-Pointing-Pointer The d-spacing increase from 1.30 nm (VOPO{sub 4}/PEO) to 2.94 nm (VOPO{sub 4}/CTA/PEO). Black-Right-Pointing-Pointer This strategy was viable for intercalation of PEO with high molecular weight. -- Abstract: A high molecular weight poly(ethylene oxide)/layered vanadyl phosphate di-hydrate intercalation compound was synthesized via the surfactant-assisted approach. Results confirmed that surfactant molecules were replaced with the polymer, while the lamellar structure of the matrix was retained, and that the material presents high specific surface area. In addition, intercalation produced a more thermally stable polymer as evidenced by thermal analysis.

  15. Adsorption energies of poly(ethylene oxide)-based surfactants and nanoparticles on an air-water surface.

    PubMed

    Zell, Zachary A; Isa, Lucio; Ilg, Patrick; Leal, L Gary; Squires, Todd M

    2014-01-14

    The self-assembly of polymer-based surfactants and nanoparticles on fluid-fluid interfaces is central to many applications, including dispersion stabilization, creation of novel 2D materials, and surface patterning. Very often these processes involve compressing interfacial monolayers of particles or polymers to obtain a desired material microstructure. At high surface pressures, however, even highly interfacially active objects can desorb from the interface. Methods of directly measuring the energy which keeps the polymer or particles bound to the interface (adsorption/desorption energies) are therefore of high interest for these processes. Moreover, though a geometric description linking adsorption energy and wetting properties through the definition of a contact angle can be established for rigid nano- or microparticles, such a description breaks down for deformable or aggregating objects. Here, we demonstrate a technique to quantify desorption energies directly, by comparing surface pressure-density compression measurements using a Wilhelmy plate and a custom-microfabricated deflection tensiometer. We focus on poly(ethylene oxide)-based polymers and nanoparticles. For PEO-based homo- and copolymers, the adsorption energy of PEO chains scales linearly with molecular weight and can be tuned by changing the subphase composition. Moreover, the desorption surface pressure of PEO-stabilized nanoparticles corresponds to the saturation surface pressure for spontaneously adsorbed monolayers, yielding trapping energies of ∼10(3) k(B)T. PMID:24328531

  16. Molecular dynamics simulation of polymer electrolytes based on poly(ethylene oxide) and ionic liquids. II. Dynamical properties

    NASA Astrophysics Data System (ADS)

    Costa, Luciano T.; Ribeiro, Mauro C. C.

    2007-10-01

    Dynamical properties of polymer electrolytes based on poly(ethylene oxide) (PEO) and ionic liquids of 1-alkyl-3-methylimidazolium cations were calculated by molecular dynamics simulations with previously proposed models [L. T. Costa and M. C. Ribeiro, J. Chem. Phys. 124, 184902 (2006)]. The effect of changing the ionic liquid concentration, temperature, and the 1-alkyl-chain lengths, [1,3-dimethylimidazolium]PF6 and [1-butyl-3-methylimidazolium]PF6 ([dmim]PF6 and [bmim]PF6), was investigated. Cation diffusion coefficient is higher than those of anion and oxygen atoms of PEO chains. Ionic mobility in PEO /[bmim]PF6 is higher than in PEO /[dmim]PF6, so that the ionic conductivity κ of the former is approximately ten times larger than the latter. The ratio between κ and its estimate from the Nernst-Einstein equation κ /κNE, which is inversely proportional to the strength of ion pairs, is higher in ionic liquid polymer electrolytes than in polymer electrolytes based on inorganic salts with Li+ cations. Calculated time correlation functions corroborate previous evidence from the analysis of equilibrium structure that the ion pairs in ionic liquid polymer electrolytes are relatively weak. Structural relaxation at distinct spatial scales is revealed by the calculation of the intermediate scattering function at different wavevectors. These data are reproduced with stretched exponential functions, so that temperature and wavevector dependences of best fit parameters can be compared with corresponding results for polymer electrolytes containing simpler ions.

  17. Nuclear magnetic resonance investigation of dynamics in poly(ethylene oxide)-based lithium polyether-ester-sulfonate ionomers

    DOE PAGESBeta

    Roach, David J.; Dou, Shichen; Colby, Ralph H.; Mueller, Karl T.

    2012-01-06

    Nuclear magnetic resonance (NMR) spectroscopy has been utilized to investigate the dynamics of poly(ethylene oxide)-based lithium sulfonate ionomer samples that have low glass transition temperatures. 1H and 7Li spin-lattice relaxation times (T1) of the bulk polymer and lithium ions, respectively, were measured and analyzed in samples with a range of ion contents. The temperature dependence of T1 values along with the presence of minima in T1 as a function of temperature enabled correlation times and activation energies to be obtained for both the segmental motion of the polymer backbone and the hopping motion of lithium cations. Similar activation energies formore » motion of both the polymer and lithium ions in the samples with lower ion content indicate that the polymer segmental motion and lithium ion hopping motion are correlated in these samples, even though their respective correlation times differ significantly. A divergent trend is observed for correlation times and activation energies of the highest ion content sample with 100% lithium sulfonation due to the presence of ionic aggregation. Details of the polymer and cation dynamics on the nanosecond timescale are discussed and complement the findings of X-ray scattering and Quasi Elastic Neutron Scattering experiments.« less

  18. Preparation and interfacial properties of a novel biodegradable polymer surfactant: poly(ethylene oxide monooleate-block-DL-lactide).

    PubMed

    Nishino, Satoru; Kitamura, Yoshiro; Kishida, Akio; Yoshizawa, Hidekazu

    2005-11-01

    In this paper, we report a novel synthesis of poly(ethylene oxide monooleate-block-DL-lactide) (MOPEO-PLA) in the presence of stannous 2-ethylhexanoate catalyst. By utilizing the surfactant property and the reactive double bond of the amphiphilic MOPEO-PLA, various characteristics of PLA microspheres, such as surface and internal structure, surface morphology, release property, and so on, may potentially be controlled. MOPEO-PLA was found to be hydrophobic enough to prevent loss by dissolution into aqueous solution, which is often a problem for MOPEO. Furthermore, the interfacial tension measurements of a MOPEO-PLA/toluene/water system revealed that MOPEO-PLA had a good surface activity almost equal to that of MOPEO. The MOPEO-PLA/PLA blend films were prepared by solvent casting on a water layer. Contact-angle measurements of MOPEO-PLA/PLA blend films confirmed that the hydrophilic PEO segments were selectivity accumulated at the oil/water interface. Moreover, the surface free energy on the 'water side' of the MOPEO-PLA/PLA blend films was increased because of the increase in polar components as a result of the ether bonds of the PEO segments. Schematic illustration of the adsorption property of a) MOPEO-PLA with a high-molecular-weight PLA segment and b) MOPEO-PLA with a low-molecular-weight PLA segment at an ethyl acetate/water interface. PMID:16245272

  19. Poly(ethylene oxide)-Assisted Macromolecular Self-Assembly of Lignin in ABS Matrix for Sustainable Composite Applications

    SciTech Connect

    Akato, Kokouvi M.; Tran, Chau D.; Chen, Jihua; Naskar, Amit K.

    2015-11-05

    Here we report the compatibilization of biomass-derived lignin polymer in acrylonitrile butadiene styrene (ABS) thermoplastic matrix without loss of mechanical properties via poly(ethylene oxide) (PEO)-mediated macromolecular self-assembly. ABS was blended with lignin in different concentrations, and blends with 10 wt % PEO (relative to lignin) were prepared. The relative tensile strength improved slightly at low lignin content but diminished rapidly as the lignin content was increased. However, the inclusion of PEO as an interfacial adhesion promoter helped avoid deleterious effects. Dynamic mechanical analysis showed that PEO plasticized the hard phase and thus lowered the activation energy (Ea) for its relaxation but caused stiffening of the soft phase and increased its Ea. Microscopy revealed that incorporating lignin in ABS led to the statistical dispersion of discrete lignin domains (300–1000 nm) which, after PEO addition, were reduced to smaller interconnected particles (200–500 nm). The lignin-extended partially renewable ABS resins showed shear-thinning behavior and reduced viscosity compared to neat ABS. The preferred lignin-loaded compositions reinforced with 20 vol % chopped carbon fibers exhibited mechanical performances (77–80 MPa) equivalent to those of reinforced ABS materials reportedly used in 3D printing applications. In conclusion, this approach could lower the cost of ABS while reducing its carbon footprint.

  20. Nuclear magnetic resonance investigation of dynamics in poly(ethylene oxide)-based lithium polyether-ester-sulfonate ionomers

    NASA Astrophysics Data System (ADS)

    Roach, David J.; Dou, Shichen; Colby, Ralph H.; Mueller, Karl T.

    2012-01-01

    Nuclear magnetic resonance spectroscopy has been utilized to investigate the dynamics of poly(ethylene oxide)-based lithium sulfonate ionomer samples that have low glass transition temperatures. 1H and 7Li spin-lattice relaxation times (T1) of the bulk polymer and lithium ions, respectively, were measured and analyzed in samples with a range of ion contents. The temperature dependence of T1 values along with the presence of minima in T1 as a function of temperature enabled correlation times and activation energies to be obtained for both the segmental motion of the polymer backbone and the hopping motion of lithium cations. Similar activation energies for motion of both the polymer and lithium ions in the samples with lower ion content indicate that the polymer segmental motion and lithium ion hopping motion are correlated in these samples, even though lithium hopping is about ten times slower than the segmental motion. A divergent trend is observed for correlation times and activation energies of the highest ion content sample with 100% lithium sulfonation due to the presence of ionic aggregation. Details of the polymer and cation dynamics on the nanosecond timescale are discussed and complement the findings of X-ray scattering and quasi-elastic neutron scattering experiments.

  1. Charge transport and glassy dynamics of poly(ethylene oxide)-based single-ion conductors under geometrical confinement

    NASA Astrophysics Data System (ADS)

    Runt, James; Iacob, Ciprian

    2015-03-01

    Segmental and local dynamics as well as charge transport are investigated in a series of poly(ethylene oxide)-based single-ion conductors (ionomers) with varying counterions (Li +, Na +) confined in uni-directional nanoporous silica membranes. The dynamics are explored over a wide frequency and temperature range by broadband dielectric relaxation spectroscopy. Slowing of segmental dynamics and a decrease in dc conductivity (strongly coupled with segmental relaxation) of the confined ionomers are associated with surface effects - resulting from interfacial hydrogen bonding between the host nanoporous silica membrane and the guest ionomers. These effects are significantly reduced or eliminated upon pore surface modification through silanization. The primary transport properties for the confined ionomers decrease by about one decade compared to the bulk ionomer. A model assuming reduced mobility of an adsorbed layer at the pore wall/ionomer interface is shown to provide a quantitative explanation for the decrease in effective transport quantities in non-silanized porous silica membranes. Additionally, the effect of confinement on ion aggregation in ionomers by using X-ray scattering will also be discussed. Supported by the National Science Foundation, Polymers Program.

  2. Nuclear Magnetic Resonance Investigation of Dynamics in Poly(Ethylene Oxide) Based Lithium Polyether-ester-sulfonate Ionomers

    SciTech Connect

    Roach, David J.; Dou, Shichen; Colby, Ralph H.; Mueller, Karl T.

    2012-01-07

    Nuclear magnetic resonance (NMR) spectroscopy has been utilized to investigate the dynamics of poly(ethylene oxide)-based lithium sulfonate ionomer samples that have low glass transition temperatures. 1H and 7Li spin-lattice relaxation times (T1) of the bulk polymer and lithium ions, respectively, were analyzed in samples with a range of ion contents. The temperature dependence of T1 values along with the presence of minima in T1 enabled correlation times and activation energies to be obtained for both the segmental motion of the polymer backbone and the hopping motion of lithium cations. Similar activation energies of both the polymer and lithium ions in the lower ion content samples indicate that the polymer segmental motion and lithium ion hopping motion are correlated even though their respective correlation times differ significantly. A divergent trend is observed for correlation times and activation energies of the highest ion content sample due to the presence of ionic aggregation. Details about the polymer and cation dynamics on the nanosecond timescale are discussed and complement the findings of X-ray scattering and Quasi Elastic Neutron Scattering experiments.

  3. Understanding the Impact of Poly(ethylene oxide) on the Assembly of Lignin in Solution toward Improved Carbon Fiber Production.

    PubMed

    Imel, Adam E; Naskar, Amit K; Dadmun, Mark D

    2016-02-10

    Carbon fiber produced from lignin has recently become an industrial scalable product with applications ranging from thermal insulation to reinforcing automobile bodies. Previous research has shown that mixing 1-2 wt %, of poly(ethylene oxide) (PEO) with the lignin before fiber formation can enhance the properties of the final carbon fibers. The research reported here determines the impact of adding PEO to a lignin solution on its assembly, focusing on the role of the lignin structure on this assembly process. Results indicate the addition of PEO anisotropically directs the self-assembly of the hardwood and softwood lignin by lengthening the cylindrical building blocks that make up the larger global aggregates. On the other hand, results from an annual lignin exhibit a shapeless, more complex structure with a unique dependence on the PEO loading. These results are consistent with improved carbon fibers from solutions of lignin that include PEO, as the local ordering and directed assembly will inhibit the formation of defects during the carbon fiber fabrication process. PMID:26756927

  4. Nuclear magnetic resonance investigation of dynamics in poly(ethylene oxide)-based lithium polyether-ester-sulfonate ionomers

    SciTech Connect

    Roach, David J.; Dou, Shichen; Colby, Ralph H.; Mueller, Karl T.

    2012-01-06

    Nuclear magnetic resonance (NMR) spectroscopy has been utilized to investigate the dynamics of poly(ethylene oxide)-based lithium sulfonate ionomer samples that have low glass transition temperatures. 1H and 7Li spin-lattice relaxation times (T1) of the bulk polymer and lithium ions, respectively, were measured and analyzed in samples with a range of ion contents. The temperature dependence of T1 values along with the presence of minima in T1 as a function of temperature enabled correlation times and activation energies to be obtained for both the segmental motion of the polymer backbone and the hopping motion of lithium cations. Similar activation energies for motion of both the polymer and lithium ions in the samples with lower ion content indicate that the polymer segmental motion and lithium ion hopping motion are correlated in these samples, even though their respective correlation times differ significantly. A divergent trend is observed for correlation times and activation energies of the highest ion content sample with 100% lithium sulfonation due to the presence of ionic aggregation. Details of the polymer and cation dynamics on the nanosecond timescale are discussed and complement the findings of X-ray scattering and Quasi Elastic Neutron Scattering experiments.

  5. Dodecagonal Quasicrystalline Morphology in a Poly(styrene-b-isoprene-b-styrene-b-ethylene oxide) Tetrablock Terpolymer

    SciTech Connect

    Zhang, Jingwen; Bates, Frank S.

    2012-10-26

    A dodecagonal quasicrystalline (QC) morphology is identified in a poly(styrene-b-isoprene-b-styrene-b-ethylene oxide) (SISO) tetrablock terpolymer based on evidence provided by transmission electron microscopy (TEM), small-angle X-ray scattering, and dynamic mechanical spectroscopy measurements. The QC state occurs at temperatures between those associated with simple hexagonal order (HEX) and the {sigma}-phase (P4{sub 2}/mnm), T{sub HEX} < T{sub QC} < T{sub {sigma}} < T{sub ODT}, where T{sub ODT} is the order-disorder transition temperature. All three morphologies are formed from spherical domains containing an O core surrounded by a shell of S that screens unfavorable segment-segment interactions with an I-rich matrix. TEM analysis reveals a QC morphology with 12-fold rotational symmetry but devoid of long-range translational order, along with locally coordinated structures consistent with dodecagonal quasicrystalline approximants. The SISO molecular architecture decouples control over the domain shape and interdomain interactions, leading to a multiplicity of packing symmetries.

  6. Synthesis and Gelation Characteristics of Photo-Crosslinkable Star Poly(ethylene oxide-co-lactide-glycolide acrylate) Macromonomers

    PubMed Central

    Moeinzadeh, Seyedsina; Khorasani, Saied Nouri; Ma, Junyu; He, Xuezhong; Jabbari, Esmaiel

    2011-01-01

    Viability of encapsulated cells in situ crosslinkable macromonomers depends strongly on the minimum concentration of polymerization initiators and monomers required for gelation. Novel 4-arm poly(ethylene oxide-co-lactide-glycolide acrylate) (SPELGA) macromonomers were synthesized and characterized with respect to gelation, sol fraction, degradation, and swelling in aqueous solution. SPELGA macromonomers were crosslinked in the absence of N-vinyl-2-pyrrolidone (NVP) monomer to produce a hydrogel network with a shear modulus of 27±4 kPa. The shear modulus of the gels increased by 170-fold as the macromonomer concentration was increased from 10 to 25 wt%. Sol fraction ranged between 8–18%. Addition of only 0.4 mol% NVP to the polymerization mixture increased modulus by 2.2-fold from 27±4 (no NVP) to 60±10 kPa. The higher modulus was attributed to the dilution effect of polymer chains in the sol, by delaying the onset of diffusion-controlled reaction, and cross-propagation of the growing chains with network-bound SPELGA acrylates. Degradation of SPELGA gels depended on water content and density of hydrolytically degradable ester groups. PMID:21927508

  7. Effect of low-temperature ethylene oxide and electron beam sterilization on the in vitro and in vivo function of reconstituted extracellular matrix-derived scaffolds.

    PubMed

    Proffen, Benedikt L; Perrone, Gabriel S; Fleming, Braden C; Sieker, Jakob T; Kramer, Joshua; Hawes, Michael L; Murray, Martha M

    2015-10-01

    Reconstituted extracellular matrix (ECM)-derived scaffolds are commonly utilized in preclinical tissue engineering studies as delivery vehicles for cells and growth factors. Translation into clinical use requires identifying a sterilization method that effectively removes bacteria but does not harm scaffold function. To determine effectiveness of sterilization and impact on ECM scaffold integrity and function, low-temperature ethylene oxide and 15 kGy electron beam irradiation techniques were evaluated. Scaffold sterility was assessed in accordance to United States Pharmacopeia Chapter 71. Scaffold matrix degradation was determined in vitro using enzymatic resistance tests and gel electrophoresis. Scaffold mechanics including elastic modulus, yield stress and collapse modulus were tested. Lastly, 14 Yorkshire pigs underwent ACL transection and bio-enhanced ACL repair using sterilized scaffolds. Histologic response of ligament, synovium, and lymph nodes was compared at 4, 6, and 8 weeks. Ethylene oxide as well as electron beam irradiation yielded sterile scaffolds. Scaffold resistance to enzymatic digestion and protein integrity slightly decreased after electron beam irradiation while ethylene oxide altered scaffold matrix. Scaffold elastic modulus and yield stress were increased after electron beam treatment, while collapse modulus was increased after ethylene oxide treatment. No significant changes in ACL dimensions, in vivo scaffold resorption rate, or histologic response of synovium, ligament, and lymph nodes with either terminal sterilization technique were detectable. In conclusion, this study identifies two methods to terminally sterilize an ECM scaffold. In vitro scaffold properties were slightly changed without significantly influencing the biologic responses of the surrounding tissues in vivo. This is a critical step toward translating new tissue engineering strategies to clinical trials. PMID:26088294

  8. The use of poly(ethylene oxide) for the efficient stabilization of entrapped alpha-chymotrypsin in silicone elastomers: a chemometric study.

    PubMed

    Ragheb, Amro M; Hileman, Oliver E; Brook, Michael

    2005-12-01

    The enzyme alpha-chymotrypsin, a model for catalytic proteins, was entrapped in different silicone elastomers that were formed via the condensation-cure room temperature vulcanization (CC-RTV) of silanol terminated poly(dimethylsiloxane) with tetraethyl orthosilicate as a crosslinker, in the presence of different poly(ethylene oxide) oligomers that were functionalized with triethoxysilyl groups. The effects of various chemical factors on both the activity and entrapping efficiency of proteins (leaching) were studied using a 2-level fractional factorial design--a chemometrics approach. The factors studied include the concentration and chain length of poly(ethylene oxide), enzyme content, and crosslinker (TEOS) concentration. The study indicated that poly(ethylene oxide) can stabilize the entrapped alpha-chymotrypsin in silicone rubber: the specific activity can be maximized by incorporating a relatively high content of short chain, functional PEO. Increased enzyme concentration was found to adversely affect the specific activity. The effect of TEOS was found to be insignificant when PEO was present in the elastomer, however, it does affect the activity positively in the case of simple elastomers. PMID:15992922

  9. Complex Formation Between Lysozyme and Stabilized Micelles with a Mixed Poly(ethylene oxide)/Poly(acrylic acid) Shell.

    PubMed

    Karayianni, Maria; Gancheva, Valeria; Pispas, Stergios; Petrov, Petar

    2016-03-10

    The electrostatic complexation between lysozyme and stabilized polymeric micelles (SPMs) with a poly(acrylic acid) (PAA) or a mixed poly(ethylene oxide)/poly(acrylic acid) (PEO/PAA) shell (SPMs with a mixed shell, SPMMS) and a temperature-responsive poly(propylene oxide) (PPO) core was investigated by means of dynamic, static, and electrophoretic light scattering. The SPMs and different types of SPMMS used resulted from the self-assembly of PAA-PPO-PAA triblock copolymer chains, or PAA-PPO-PAA and PEO-PPO-PEO triblock copolymer chain mixtures (with varying chain lengths and molar ratios) in aqueous solutions at pH 10 and the subsequent cross-linking of their PPO cores via loading and photo-cross-linking of pentaerythritol tetraacrylate (PETA). The solution behavior, structure and properties of the formed complexes at pH 7 and 0.01 M ionic strength, were studied as a function of the protein concentration in the solution (the concentration of the stabilized micelles was kept constant) or equivalently the ratio of the two components. The complexation process and properties of the complexes proved to be dependent on the protein concentration, while of particular interest was the effect of the structure of the shell of the SPMs on the stability/solubility of the complexes. Finally, the fluorescence and mid infrared spectroscopic investigation of the structure of the complexed protein showed that, although a small stretching of the protein molecules occurred in some cases, no protein denaturation takes place upon complexation. PMID:26881445

  10. High-temperature catalytic oxidative conversion of propane to propylene and ethylene involving coupling of exothermic and endothermic reactions

    SciTech Connect

    Choudhary, V.R.; Rane, V.H.; Rajput, A.M.

    2000-04-01

    Coupling of the exothermic catalytic oxidative conversion and endothermic thermal cracking (noncatalytic) reactions of propane to propylene and ethylene over the SrO/La{sub 2}O{sub 3}/SA5205 catalyst in the presence of steam and limited oxygen was investigated at different process conditions (temperature, 700--850 C; C{sub 3}H{sub 8}/O{sub 2} ratio in feed, 2.0--8.0; H{sub 2}O/C{sub 3}H{sub 8} ratio, 0.5--2.5; space velocity, 2,000--15,000 cm{sup 3}/g h). In the presence of steam and limited O{sub 2}, the endothermic thermal cracking and exothermic oxidative conversion reactions occur simultaneously and there is no coke formation on the catalyst. Because of the direct coupling of exothermic and endothermic reactions, this process occurs in a most energy efficient and safe manner. The propane conversion, selectivity for propylene, and net heat of reaction ({Delta}H{sub r}) in the process are strongly influenced by the temperature and concentration of O{sub 2} relative to the propane in the feed. The C{sub 3}H{sub 6}/C{sub 2}H{sub 4} product ratio is also strongly influenced by the temperature, C{sub 3}H{sub 8}/O{sub 2} feed ratio, and space velocity. The net heat of reaction can be controlled by manipulating the reaction temperature and C{sub 3}H{sub 8}/O{sub 2} ratio in the feed; the process exothermicity is reduced drastically with increasing the temperature and/or C{sub 3}H{sub 8}/O{sub 2} feed ratio.

  11. Indium tin oxide with zwitterionic interfacial design for biosensing applications in complex matrices

    NASA Astrophysics Data System (ADS)

    Darwish, Nadia T.; Alias, Yatimah; Khor, Sook Mei

    2015-01-01

    Biosensing interfaces consisting of linker molecules (COOH or NH2) and charged, antifouling moieties ((sbnd SO3- and N+(Me)3) for biosensing applications were prepared for the first time by the in situ deposition of mixtures of aryl diazonium cations on indium tin oxide (ITO) electrodes. A linker molecule is required for the attachment of biorecognition molecules (e.g., antibodies, enzymes, DNA chains, and aptamers) close to the transducer surface. The attached molecules improve the biosensing sensitivity and also provide a short response time for analyte detection. Thus, the incorporation of a linker and antifouling molecules is an important interfacial design for both affinity and enzymatic biosensors. The reductive adsorption behavior and electrochemical measurement were studied for (1) an individual compound and (2) a mixture of antifouling zwitterionic molecules together with linker molecules [combination 1: 4-sulfophenyl (SP), 4-trimethylammoniophenyl (TMAP), and 1,4-phenylenediamine (PPD); combination 2: 4-sulfophenyl (SP), 4-trimethylammoniophenyl (TMAP), and 4-aminobenzoic acid (PABA)] of aryl diazonium cations grafted onto an ITO electrode. The mixture ratios of SP:TMAP:PPD and SP:TMAP:PABA that provided the greatest resistance to non-specific protein adsorptions of bovine serum albumin labeled with fluorescein isothiocyanate (BSA-FITC) and cytochrome c labeled with rhodamine B isothiocyanate (RBITC-Cyt c) were determined by confocal laser scanning microscopy (CLSM). For the surface antifouling study, we used 2-[2-(2-methoxyethoxy) ethoxy]acetic acid (OEG) as a standard control because of its prominent antifouling properties. Surface compositions of combinations 1 and 2 were characterized using X-ray photoelectron spectroscopy (XPS). Field-emission scanning electron microscopy (FE-SEM) was used to characterize the morphology of the grafted films to confirm the even distribution between linker and antifouling molecules grafted onto the ITO surfaces

  12. The polymerization and electrochemical characterization of polypyrrole and polypyrrole/poly(ethylene oxide)pyrrole copolymers

    NASA Astrophysics Data System (ADS)

    Huntoon, Trey William Stevens

    1998-11-01

    The work contained within this document discusses the polymerization and subsequent characterization of Polypyrrole based electrodes for lithium batteries. Polypyrrole and Polypyrrole/polyethyloxy copolymers were compared and contrasted in an attempt to show the superior kinetics of the copolymer electrode. It was found that the diffusion of dopant ions across the electrode and electrolyte interface was increased by on order of magnitude in the copolymer sample. It was also found that the reversibility of the Polypyrrole electrode was greater than that of the copolymer electrode. While the diffusion coefficient of the copolymer electrode was altered to be comparable to that of the transition metal oxide cathodes in production today, the capacity of the copolymer material is still too low to be considered as an alternative cathode material in the lithium battery industry.

  13. Molecular dynamics simulations of poly (ethylene oxide) hydration and conformation in solutions

    NASA Astrophysics Data System (ADS)

    Dahal, Udaya; Dormidontova, Elena

    Polyethylene oxide (PEO) is one of the most actively used polymers, especially in biomedical applications due to its high hydrophilicity, biocompatibility and potency to inhibit protein adsorption. PEO solubility and conformation in water depends on its capability to form hydrogen bonds. Using atomistic molecular dynamics simulations we investigated the details of water packing around PEO chain and characterized the type and lifetime of hydrogen bonds in aqueous and mixed solvent solutions. The observed polymer chain conformation varies from an extended coil in pure water to collapsed globule in hexane and a helical-like conformation in pure isobutyric acid or isobutyric acid -water mixture in agreement with experimental observations. We'll discuss the implications of protic solvent arrangement and stability of hydrogen bonds on PEO chain conformation and mobility. This research is supported by NSF (DMR-1410928).

  14. Super Soft All-Ethylene Oxide Polymer Electrolyte for Safe All-Solid Lithium Batteries

    NASA Astrophysics Data System (ADS)

    Porcarelli, Luca; Gerbaldi, Claudio; Bella, Federico; Nair, Jijeesh Ravi

    2016-01-01

    Here we demonstrate that by regulating the mobility of classic -EO- based backbones, an innovative polymer electrolyte system can be architectured. This polymer electrolyte allows the construction of all solid lithium-based polymer cells having outstanding cycling behaviour in terms of rate capability and stability over a wide range of operating temperatures. Polymer electrolytes are obtained by UV-induced (co)polymerization, which promotes an effective interlinking between the polyethylene oxide (PEO) chains plasticized by tetraglyme at various lithium salt concentrations. The polymer networks exhibit sterling mechanical robustness, high flexibility, homogeneous and highly amorphous characteristics. Ambient temperature ionic conductivity values exceeding 0.1 mS cm-1 are obtained, along with a wide electrochemical stability window (>5 V vs. Li/Li+), excellent lithium ion transference number (>0.6) as well as interfacial stability. Moreover, the efficacious resistance to lithium dendrite nucleation and growth postulates the implementation of these polymer electrolytes in next generation of all-solid Li-metal batteries working at ambient conditions.

  15. Titanate nanotubes for reinforcement of a poly(ethylene oxide)/chitosan polymer matrix.

    PubMed

    Porras, R; Bavykin, D V; Zekonyte, J; Walsh, F C; Wood, R J

    2016-05-13

    Soft polyethylene oxide (PEO)/chitosan mixtures, reinforced with hard titanate nanotubes (TiNTs) by co-precipitation from aqueous solution, have been used to produce compact coatings by the 'drop-cast' method, using water soluble PEO polymer and stable, aqueous colloidal solutions of TiNTs. The effects of the nanotube concentration and their length on the hardness and modulus of the prepared composite have been studied using nanoindentation and nanoscratch techniques. The uniformity of TiNT dispersion within the polymer matrix has been studied using transmission electron microscopy (TEM). A remarkable increase in hardness and reduced Young's modulus of the composites, compared to pure polymer blends, has been observed at a TiNT concentration of 25 wt %. The short (up to 30 min) ultrasound treatment of aqueous solutions containing polymers and a colloidal TiNT mixture prior to drop casting has resulted in some improvements in both hardness and reduced Young's modulus of dry composite films, probably due to a better dispersion of ceramic nanotubes within the matrix. However, further (more than 1 h) treatment of the mixture with ultrasound resulted in a deterioration of the mechanical properties of the composite accompanied by a shortening of the nanotubes, as observed by the TEM. PMID:27039947

  16. Titanate nanotubes for reinforcement of a poly(ethylene oxide)/chitosan polymer matrix

    NASA Astrophysics Data System (ADS)

    Porras, R.; Bavykin, D. V.; Zekonyte, J.; Walsh, F. C.; Wood, R. J.

    2016-05-01

    Soft polyethylene oxide (PEO)/chitosan mixtures, reinforced with hard titanate nanotubes (TiNTs) by co-precipitation from aqueous solution, have been used to produce compact coatings by the ‘drop-cast’ method, using water soluble PEO polymer and stable, aqueous colloidal solutions of TiNTs. The effects of the nanotube concentration and their length on the hardness and modulus of the prepared composite have been studied using nanoindentation and nanoscratch techniques. The uniformity of TiNT dispersion within the polymer matrix has been studied using transmission electron microscopy (TEM). A remarkable increase in hardness and reduced Young’s modulus of the composites, compared to pure polymer blends, has been observed at a TiNT concentration of 25 wt %. The short (up to 30 min) ultrasound treatment of aqueous solutions containing polymers and a colloidal TiNT mixture prior to drop casting has resulted in some improvements in both hardness and reduced Young’s modulus of dry composite films, probably due to a better dispersion of ceramic nanotubes within the matrix. However, further (more than 1 h) treatment of the mixture with ultrasound resulted in a deterioration of the mechanical properties of the composite accompanied by a shortening of the nanotubes, as observed by the TEM.

  17. Super Soft All-Ethylene Oxide Polymer Electrolyte for Safe All-Solid Lithium Batteries

    PubMed Central

    Porcarelli, Luca; Gerbaldi, Claudio; Bella, Federico; Nair, Jijeesh Ravi

    2016-01-01

    Here we demonstrate that by regulating the mobility of classic −EO− based backbones, an innovative polymer electrolyte system can be architectured. This polymer electrolyte allows the construction of all solid lithium-based polymer cells having outstanding cycling behaviour in terms of rate capability and stability over a wide range of operating temperatures. Polymer electrolytes are obtained by UV-induced (co)polymerization, which promotes an effective interlinking between the polyethylene oxide (PEO) chains plasticized by tetraglyme at various lithium salt concentrations. The polymer networks exhibit sterling mechanical robustness, high flexibility, homogeneous and highly amorphous characteristics. Ambient temperature ionic conductivity values exceeding 0.1 mS cm−1 are obtained, along with a wide electrochemical stability window (>5 V vs. Li/Li+), excellent lithium ion transference number (>0.6) as well as interfacial stability. Moreover, the efficacious resistance to lithium dendrite nucleation and growth postulates the implementation of these polymer electrolytes in next generation of all-solid Li-metal batteries working at ambient conditions. PMID:26791572

  18. Compound matrices

    NASA Astrophysics Data System (ADS)

    Kravvaritis, Christos; Mitrouli, Marilena

    2009-02-01

    This paper studies the possibility to calculate efficiently compounds of real matrices which have a special form or structure. The usefulness of such an effort lies in the fact that the computation of compound matrices, which is generally noneffective due to its high complexity, is encountered in several applications. A new approach for computing the Singular Value Decompositions (SVD's) of the compounds of a matrix is proposed by establishing the equality (up to a permutation) between the compounds of the SVD of a matrix and the SVD's of the compounds of the matrix. The superiority of the new idea over the standard method is demonstrated. Similar approaches with some limitations can be adopted for other matrix factorizations, too. Furthermore, formulas for the n - 1 compounds of Hadamard matrices are derived, which dodge the strenuous computations of the respective numerous large determinants. Finally, a combinatorial counting technique for finding the compounds of diagonal matrices is illustrated.

  19. Crystallization of poly(ethylene oxide) with acetaminophen--a study on solubility, spherulitic growth, and morphology.

    PubMed

    Yang, Min; Gogos, Costas

    2013-11-01

    A simple, sensitive, efficient, and novel method analyzing the number of spherulitic nuclei was proposed to estimate the solubility of a model drug acetaminophen (APAP) in poly(ethylene oxide) (PEO). At high crystallization temperature (323 K), 10% APAP-PEO had the same low number of spherulitic nuclei as pure PEO, indicating that APAP and PEO were fully miscible. At low crystallization temperature (303 K), the number of nuclei for 10% APAP-PEO was significantly higher, suggesting that APAP was oversaturated and therefore recrystallized and acted as a nucleating agent. Based on the results obtained, the solubility of APAP in PEO is possibly between the concentration of 0.1% and 1% at 303 K. The spherulitic growth rate G of PEO was found to decrease with increasing APAP concentration, suggesting that APAP is most likely functioning as a chemical defect and is either rejected from or included in the PEO crystals during chain folding. APAP could possibly locate in the inter-spherulitic, inter-fibrillar, inter-lamellar, or intra-lamellar regions of PEO. At 323 K, the morphology of 10% APAP-PEO is more dendritic than spherulitic with large unfilled space in between dendrites and spherulites, which is a sign of one or the combination of the four modes of segregation. An extensive spherulitic nucleation and growth kinetics study using the classical theoretical relationships, for example, the Hoffman-Lauritzen (HL) and Avrami theories, was conducted. Both microscopic and differential scanning calorimetric (DSC) analysis yielded similar values for the nucleation constant Kg as well as the fold surface free energy σe and work of chain folding q. The values of σe and q increased with APAP concentration, indicating that the chain folding of PEO was hindered by APAP. PMID:23562611

  20. A scanning electron microscopic study of in vitro toxicity of ethylene-oxide-sterilized bone repair materials.

    PubMed

    Zislis, T; Martin, S A; Cerbas, E; Heath, J R; Mansfield, J L; Hollinger, J O

    1989-01-01

    Polylactic acid (PLA) and polyglycolic acid (PGA) have been under investigation for use in the management of hard- and soft-tissue wounds. Current research has included the incorporation of osteo-inductive substances into a PLA-PGA copolymer alloplastic implant material for enhancement of the healing of osseous defects. Conventional methods of sterilization--such as dry heat, steam heat, or 60Co--tend either to destroy or attenuate osteo-inductive activity and alter polymer biodegradation. Ethylene oxide (EO) gas sterilization is currently being tested as an alternate method. This study examined the relationship of EO-induced cytotoxicity to the length of time of polymer aeration following EO sterilization. Three groups of copolymer implant discs were studied: (1) 50:50 PLA-PGA copolymer, (2) PLA-PGA polymer with hydroxyapatite (HA), and (3) PLA-PGA with autolyzed, antigen-extracted (AA) bone particles. Polymer discs, as well as particulate HA and AA bone controls, were sterilized with EO for 12 hours. Following periods of two weeks, one week, one day, or no subsequent vacuum aeration, samples were placed into 24-well culture plates. A suspension of human fibroblasts was added to each well. Cell growth and attachment were permitted for 24 hours. Medium was then removed, and solutions for cell fixation, buffer washing, and dehydration were added to each well. SEM examination revealed changes in cell growth with increasing periods of aeration suggestive of increasing cell vitality. Cells growing on discs having no aeration were small, round, and lobulated, whereas those of seven to 14 days' aeration were more numerous, and flattened with many microvilli, pseudopodia, and dendritic processes, features consistent with normal cell morphology. These results suggest that EO-sterilized polymer implants should be aerated for least seven to 14 days prior to surgical use. PMID:2561372

  1. Prediction of acetaminophen's solubility in poly(ethylene oxide) at room temperature using the Flory-Huggins theory.

    PubMed

    Yang, Min; Wang, Peng; Gogos, Costas

    2013-01-01

    Solid dispersion technologies such as hot-melt extrusion and spray drying are often used to enhance the solubility of poorly soluble drugs. The biggest challenge associated with solid dispersion systems is that amorphous drugs may phase-separate from the polymeric matrix and recrystallize during storage. A more fundamental understanding of drug-polymer mixtures is needed for the industry to embrace the solid dispersion technologies. In this study, a theoretical model based on Flory-Huggins lattice theory was utilized to predict the solubility of a model drug acetaminophen (APAP) in a semi-crystalline polymer poly(ethylene oxide) (PEO) at 300 K. The interaction parameter χ was calculated to be -1.65 from the depression of drug's melting temperature determined from rheological and differential scanning calorimetry analysis. The equilibrium solubility in amorphous PEO was estimated to be 11.7% at 300 K. Assuming no APAP molecules dissolve in the crystalline part of PEO, the adjusted theoretical solubility is around 2.3% considering PEO being 80% crystalline. The solubility of APAP in PEG 400 was calculated to be 14.6% by using the same χ value, close to the experimental measurement 17.1%. The drug's solubility could be altered noticeably by the change of both χ and polymer molecular weight. The study also suggests that the depression of drug's melting point is a good indicator for preliminary polymer screening. The polymer that reduces the melting point the most is likely to be most miscible with the drug. PMID:22356356

  2. Bioengineering Functional Copolymers. IX. Poly[(maleic anhydride-co-hexene-1)-g-poly(ethylene oxide)].

    PubMed

    Mazi, Hidayet; Kibarer, Günay; Emregül, Emel; Rzaev, Zakir M O

    2006-04-12

    Amphiphilic bioengineering copolymers having a combination of hydrophilic/hydrophobic linkages and polyelectrolyte behavior, along with an ability to interact with biomacromolecules, in particular with the invertase enzyme, have been synthesized by (a) complex-radical copolymerization of maleic anhydride (MA, the acceptor) and hexene-1 (H-1, the donor) monomers with benzoyl peroxide as the initiator in 1,4-dioxane at 65 degrees C under high-conversion conditions and (b) subsequent grafting (polyesterification) of synthesized poly(MA-alt-H-1) with alpha-methoxy-omega-hydroxy-poly(ethylene oxide) (PEO). Copolymerizations were also carried out in the steady state, in order to essentially reduce the effect of copolymer composition drift. The values of the monomer reactivity ratios (r(1) and r(2)) determined by using the known terminal models of Fineman-Ross (FR) and Kelen-Tüdös (KT), as well as by nonlinear regression (NLR) analysis, are: r(1) = 0.16 and r(2) = 0.30 (FR), r(1) = 0.14 and r(2) = 0.27 (KT), and r(1) = 0.15 and r(2) = 0.29 (NLR), respectively. All the copolymers and graft copolymers were characterized by FTIR spectroscopy, (1)H{(13)C} NMR spectroscopy, viscometric measurements, and chemical (acid number), thermal (DSC and TGA), and X-ray diffraction analyses. Unlike poly(MA-alt-H-1)s, PEO macrobranched graft copolymers exhibit expressed polyelectrolyte and swelling behavior in diluted and concentrated dioxane solutions, respectively. The copolymer and its PEO hyperbranched derivatives can be used as carriers for enzyme immobilization. PMID:16572476

  3. Cell adhesion and growth enabled by biomimetic oligopeptide modification of a polydopamine-poly(ethylene oxide) protein repulsive surface.

    PubMed

    Musilkova, Jana; Kotelnikov, Ilya; Novotna, Katarina; Pop-Georgievski, Ognen; Rypacek, Frantisek; Bacakova, Lucie; Proks, Vladimir

    2015-11-01

    Protein-repulsive surfaces modified with ligands for cell adhesion receptors have been widely developed for controlling the cell adhesion and growth in tissue engineering. However, the question of matrix production and deposition by cells on these surfaces has rarely been addressed. In this study, protein-repulsive polydopamine-poly(ethylene oxide) (PDA-PEO) surfaces were functionalized with an RGD-containing peptide (RGD), with a collagen-derived peptide binding fibronectin (Col), or by a combination of these peptides (RGD + Col, ratio 1:1) in concentrations of 90 fmol/cm(2) and 700 fmol/cm(2) for each peptide type. When seeded with vascular endothelial CPAE cells, the PDA-PEO surfaces proved to be completely non-adhesive for cells. On surfaces with lower peptide concentrations and from days 1 to 3 after seeding, cell adhesion and growth was restored practically only on the RGD-modified surface. However, from days 3 to 7, cell adhesion and growth was improved on surfaces modified with Col and with RGD + Col. At higher peptide concentrations, the cell adhesion and growth was markedly improved on all peptide-modified surfaces in both culture intervals. However, the collagen-derived peptide did not increase the expression of fibronectin in the cells. The deposition of fibronectin on the material surface was generally very low and similar on all peptide-modified surfaces. Nevertheless, the RGD + Col surfaces exhibited the highest cell adhesion stability under a dynamic load, which correlated with the highest expression of talin and vinculin in the cells on these surfaces. A combination of RGD + Col therefore seems to be the most promising for surface modification of biomaterials, e.g. vascular prostheses. PMID:26449443

  4. A study of release mechanisms of different ophthalmic drugs from erodible ocular inserts based on poly(ethylene oxide).

    PubMed

    Di Colo, G; Zambito, Y

    2002-09-01

    When topical controlled delivery of ophthalmic drugs is realised via erodible inserts, drug bioavailability is maximised, if release is controlled exclusively by insert erosion, since parallel mechanisms which increase the release rate, also increases the dose fraction cleared from the precorneal area by tear fluid draining. The respective contributions of diffusion and erosion to the release mechanism of different drugs, namely, prednisolone (PDS), oxytetracycline hydrochloride (OTH) and gentamicin sulfate (GTS), from erodible ocular inserts based on poly(ethylene oxide) (PEO) of molecular weight 400 or 900kDa was determined by an in vitro technique adequate to predict the release mechanism in vivo. PDS and OTH were released with erosion-controlled kinetics. With therapeutic doses of these drugs in the inserts (0.3mg, 1.5%), the possibility of a purely erosive mechanism was shown to rely upon drug-PEO molecular interactions, which limit drug diffusion in the swollen matrix. This was the case with OTH, for which strong interactions with PEO were measured, whereas some contribution from the parallel diffusive mechanism was evidenced for PDS, which showed weaker interactions with polymer. Such a contribution disappeared when the PDS concentration in the insert was increased to 6%, which suggested that the erosive mechanism is favoured by a drug concentration in the hydrated insert substantially higher than solubility. On the other hand, the release of about 50% GTS dose was controlled by diffusion, due to the high water solubility of this drug, accompanied by weak drug-PEO interactions. In this case the residence time of drug in the precorneal area is expected to be significantly shorter than that of the PEO carrier. PMID:12191691

  5. Nitric oxide mediates strigolactone signaling in auxin and ethylene-sensitive lateral root formation in sunflower seedlings

    PubMed Central

    Bharti, Niharika; Bhatla, Satish C

    2015-01-01

    Strigolactones (SLs) play significant role in shaping root architecture whereby auxin-SL crosstalk has been observed in SL-mediated responses of primary root elongation, lateral root formation and adventitious root (AR) initiation. Whereas GR24 (a synthetic strigolactone) inhibits LR and AR formation, the effect of SL biosynthesis inhibitor (fluridone) is just the opposite (root proliferation). Naphthylphthalamic acid (NPA) leads to LR proliferation but completely inhibits AR development. The diffusive distribution of PIN1 in the provascular cells in the differentiating zone of the roots in response to GR24, fluridone or NPA treatments further indicates the involvement of localized auxin accumulation in LR development responses. Inhibition of LR formation by GR24 treatment coincides with inhibition of ACC synthase activity. Profuse LR development by fluridone and NPA treatments correlates with enhanced [Ca2+]cyt in the apical region and differentiating zones of LR, indicating a critical role of [Ca2+] in LR development in response to the coordinated action of auxins, ethylene and SLs. Significant enhancement of carotenoid cleavage dioxygenase (CCD) activity (enzyme responsible for SL biosynthesis) in tissue homogenates in presence of cPTIO (NO scavenger) indicates the role of endogenous NO as a negative modulator of CCD activity. Differences in the spatial distribution of NO in the primary and lateral roots further highlight the involvement of NO in SL-modulated root morphogenesis in sunflower seedlings. Present work provides new report on the negative modulation of SL biosynthesis through modulation of CCD activity by endogenous nitric oxide during SL-modulated LR development. PMID:26076049

  6. Performance of polymer electrolyte based on chitosan blended with poly(ethylene oxide) for plasmonic dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Buraidah, M. H.; Teo, L. P.; Au Yong, C. M.; Shah, Shahan; Arof, A. K.

    2016-07-01

    Chitosan and poly(ethylene oxide) powders have been mixed in different weight ratios. To each mixture, a fixed amount of ammonium iodide has been added. All mixtures have been dissolved in 1% acetic acid solution to form polymer blend electrolyte films by the solution cast technique. X-ray diffraction indicates that the polymer blend electrolytes are amorphous. Fourier transform infrared spectroscopy shows shifting of the amine, carboxamide and Csbnd Osbnd C bands to lower wavenumbers indicating the occurrence of complexation. Electrochemical impedance spectroscopy has been used to study the electrical properties of the samples. The ionic conductivity for 55 wt.% chitosan-45 wt.% NH4I electrolyte system is 3.73 × 10-7 S cm-1 at room temperature and is increased to 3.66 × 10-6 S cm-1 for the blended film (16.5 wt.% chitosan-38.5 wt.% PEO)-45 wt.% NH4I film. Dye-sensitized solar cells (DSSCs) have been fabricated by sandwiching the polymer electrolyte between the TiO2/dye photoelectrode and Pt counter electrode. DSSCs fabricated exhibits short-circuit current density (Jsc) of 2.71 mA cm-2, open circuit voltage (Voc) of 0.58 V and efficiency of 0.78% with configuration ITO/TiO2/N3 dye/(16.5 wt.% chitosan-38.5 wt.% PEO)-45 wt.% NH4I(+I2)/Pt/ITO and Jsc of 2.84 mA cm-2, Voc of 0.58 V and efficiency of 1.13% with configuration ITO/TiO2 + Ag nanoparticles/N3 dye/(16.5 wt.% chitosan-38.5 wt.% PEO)-45 wt.% NH4I(+I2)/Pt/ITO.

  7. Effect of poly(ethylene oxide)-silane graft molecular weight on the colloidal properties of iron oxide nanoparticles for biomedical applications.

    PubMed

    Barrera, Carola; Herrera, Adriana P; Bezares, Nayla; Fachini, Estevão; Olayo-Valles, Roberto; Hinestroza, Juan P; Rinaldi, Carlos

    2012-07-01

    The size, charge, and stability of colloidal suspensions of magnetic nanoparticles with narrow size distribution and grafted with poly(ethylene glycol)-silane of different molecular weights were studied in water, biological buffers, and cell culture media. X-ray photoelectron spectroscopy provided information on the chemical nature of the nanoparticle surface, indicating the particle surfaces consisted of a mixture of amine groups and grafted polymer. The results indicate that the exposure of the amine groups on the surface decreased as the molecular weight of the polymer increased. The hydrodynamic diameters correlated with PEG graft molecular weight and were in agreement with a distributed density model for the thickness of a polymer shell end-grafted to a particle core. This indicates that the particles obtained consist of single iron oxide cores coated with a polymer brush. Particle surface charge and hydrodynamic diameter were measured as a function of pH, ionic strength, and in biological buffers and cell culture media. DLVO theory was used to analyze the particle stability considering electrostatic, magnetic, steric, and van der Waals interactions. Experimental results and colloidal stability theory indicated that stability changes from electrostatically mediated for a graft molecular weight of 750 g/mol to sterically mediated at molecular weights of 1000 g/mol and above. These results indicate that a graft molecular weight above 1000 g/mol is needed to produce particles that are stable in a wide range of pH and ionic strength, and in cell culture media. PMID:22513169

  8. Magnetic and dielectric properties of sulfonated (S) poly[(styrene)-(ethylene-co-butylene)]-styrene (SEBS) block copolymer/magnetic metal oxide nanocomposites synthesized via an in-situ precipitation method

    NASA Astrophysics Data System (ADS)

    Peddini, Sateesh Kumar

    Block copolymer/magnetic metal oxide nanocomposites were synthesized by growing metal oxide nanoparticles (cobalt ferrite, CoFe2O 4 and iron oxide, alpha-Fe2O3) in sulfonated (s) poly (styrene) (PS) block domains of sulfonated poly [(styrene)-(ethylene-co-butylene)-(styrene)] (SEBS) BCP preformed films via an in-situ precipitation method by dissolving the salts of respective metal chloride (s) in a suitable solvent that selectively swells the sPS regions. Inorganic uptake was determined using thermogravimetric analysis (TGA), and it was observed that none of the samples incorporated more than 5 wt % of the inorganic component. Dynamical mechanical analysis was used to observe the changes in the glass transition temperatures (T g) in both blocks of the BCP by plotting tan delta vs. temperature responses in tensile mode on all samples. The results showed that the T g of the sPS block domains increased with sulfonation level and further increased with the incorporation of both nanoparticles in the same blocks, indicating that growth of nanoparticles takes place only in sPS blocks. The crystalline structure of the nanoparticles was observed using wide angle X-ray diffractometry (WAXD), and it was determined that cobalt iron oxide nanoparticles in 20 mole % sulfonated SEBS exhibited an inverse spinel structure confirming the structure to be CoFe2O4. And with iron oxide nanoparticles in 10 mole % sulfonated SEBS exhibiting a hematite (alpha-Fe2O 3) phase. Transmission electron microscopy (TEM) was used to investigate the particle size and distribution of nanoparticles in sBCP matrices at all sulfonation levels. Select area electron diffraction in TEM was used to determine crystalline structures of individual nanoparticles to compare with the structure observed from WAXD. The changes in thickness of interfaces between the individual PS and EB block domains with increase in sulfonation of PS blocks were investigated semi-quantitatively using tapping mode atomic force

  9. Functionalized poly(ethylene glycol)-stabilized water-soluble palladium nanoparticles: property/activity relationship for the aerobic alcohol oxidation in water.

    PubMed

    Feng, Bo; Hou, Zhenshan; Yang, Hanmin; Wang, Xiangrui; Hu, Yu; Li, Huan; Qiao, Yunxiang; Zhao, Xiuge; Huang, Qingfa

    2010-02-16

    The preparation, characterization, and catalytic properties of water-soluble palladium nanoparticles stabilized by the functionalized-poly(ethylene glycol) as a protective ligand were demonstrated for aerobic oxidation of alcohols in aqueous phase. UV/vis spectra and X-ray photoelectron spectroscopy (XPS) proved that there was an electronic interaction between the bidentate nitrogen ligand and palladium atoms. Transmission electron microscopy and XPS analysis showed that the particle size and surface properties of the generated palladium nanoparticles can be controlled by varying the amount of protective ligand and the kinds of reducing agents. It was found that both the size and surface properties of palladium nanoparticles played very important roles in affecting catalytic performance. The stabilized metallic palladium nanoparticles were proven to be the active centers for benzyl alcohol oxidation in the present system, and the water-soluble Pd nanocatalysts can also be extended to the selective oxidation of various alcohols. PMID:20039597

  10. Custom-made morphologies of ZnO nanostructured films templated by a poly(styrene-block-ethylene oxide) diblock copolymer obtained by a sol-gel technique.

    PubMed

    Sarkar, Kuhu; Rawolle, Monika; Herzig, Eva M; Wang, Weijia; Buffet, Adeline; Roth, Stephan V; Müller-Buschbaum, Peter

    2013-08-01

    Zinc oxide (ZnO) nanostructured films are synthesized on silicon substrates to form different morphologies that consist of foamlike structures, wormlike aggregates, circular vesicles, and spherical granules. The synthesis involves a sol-gel mechanism coupled with an amphiphilic diblock copolymer poly(styrene-block-ethylene oxide), P(S-b-EO), which acts as a structure-directing template. The ZnO precursor zinc acetate dihydrate (ZAD) is incorporated into the poly(ethylene oxide) block. Different morphologies are obtained by adjusting the weight fractions of the solvents and ZAD. The sizes of the structure in solution for different sol-gels are probed by means of dynamic light scattering. Thin-film samples with ZnO nanostructures are prepared by spin coating and solution casting followed by a calcination step. On the basis of various selected combinations of weight fractions of the ingredients used, a ternary phase diagram is constructed to show the compositional boundaries of the investigated morphologies. The evolution and formation mechanisms of the morphologies are addressed in brief. The surface morphologies of the ZnO nanostructures are studied with SEM. The inner structures of the samples are probed by means of grazing incidence small-angle X-ray scattering to complement the SEM investigations. XRD measurements confirm the crystallization of the ZnO in the wurtzite phase upon calcination of the nanocomposite film in air. The optical properties of ZnO are analyzed by FTIR and UV/Vis spectroscopy. PMID:23881752

  11. Effects of temperature and dissolved lithium perchlorate on the viscoelastic and dynamic properties of poly(ethylene oxide), (PEO) melts

    NASA Astrophysics Data System (ADS)

    Bogoslovov, Radoslav B.

    Poly(ethylene oxide)/lithium perchlorate (PEO/LiClO4) complexes are widely studied as a prototype solid polymer electrolyte in rechargeable lithium-polymer batteries. Characterizing the structure and dynamics of the system in its molten state is important for understanding the role of the polymer environment in lithium ion transport and conductivity. A fiber-optic coupled Fabry-Perot interferometer is employed in the investigation of the electrolyte viscoelastic and dynamic properties, which are both related to the intrachain local mobility and therefore to ion diffusion. The properties of the system are studied as a function of composition, temperature, and frequency. Structural relaxation processes are observed both in the neat polymer melt and in the salt containing electrolytes. For the neat PEO-1K melt the relaxation is identified as Maxwell-Debye single-exponential relaxation (beta = 1). The relaxation time follows Arrhenius temperature dependence with activation energy of the order of 10-11 kJ/mol. Upon addition of salt, the character of the relaxation persists with beta = 1, while the characteristic relaxation time slows down and the activation energy increases slightly. The slowdown of the dynamics is more pronounced at lower temperatures. In addition, with increasing salt concentration the elastic modulus increases significantly making the system stiffer at all temperatures, while the maximum of the storage modulus is shifted to higher temperatures. These effects result in a decrease in polymer segmental mobility and consequently in reduction of lithium ion diffusivity, with increased salt concentration. A unique q-dependent measurement is performed, allowing the investigation of the Brillouin frequency and linewidth as a function of frequency. It revealed a double-step relaxation in the electrolyte. The two relaxations are identified as secondary relaxations with Maxwell-Debye character (beta=1). The lower-frequency relaxation is stronger and has

  12. [Production of soy bean inoculants. Behavior of supports based on peat from Tierra del Fuego sterilized by vapor and ethylene oxide].

    PubMed

    Balatti, A P; Mazza, L A

    1979-01-01

    The survival of Rhizobium japonicum was studied in neutralized and sterilized peats from Ushuaia and Rio Grande. The carriers were sterilized by ethylene oxide and by autoclaving. Similar counts for Rhizobium (5 x 10(8) cel/g) were obtained in peat-cultures sterilized by both methods, after eight months. A good nodulation and nitrogen fixation capacity was observed with inoculated soybean plants. Using the strain Rhizobium japonicum E-45, no appreciable difference in symbiotic effectiveness was found between the inoculants prepared with the two peats. PMID:263653

  13. Release of Bacteriocins from Nanofibers Prepared with Combinations of Poly(d,l-lactide) (PDLLA) and Poly(Ethylene Oxide) (PEO)

    PubMed Central

    Heunis, Tiaan; Bshena, Osama; Klumperman, Bert; Dicks, Leon

    2011-01-01

    Plantaricin 423, produced by Lactobacillus plantarum, and bacteriocin ST4SA produced by Enterococcus mundtii, were electrospun into nanofibers prepared from different combinations of poly(d,l-lactide) (PDLLA) and poly(ethylene oxide) (PEO) dissolved in N,N-dimethylformamide (DMF). Both peptides were released from the nanofibers with a high initial burst and retained 88% of their original antimicrobial activity at 37 °C. Nanofibers have the potential to serve as carrier matrix for bacteriocins and open a new field in developing controlled antimicrobial delivery systems for various applications. PMID:21731433

  14. Nuclear magnetic resonance investigation of dynamics in poly(ethylene oxide) based polyether-ester-sulfonate ionomers

    NASA Astrophysics Data System (ADS)

    Roach, David J.

    Nuclear magnetic resonance (NMR) spectroscopy has been utilized to investigate the dynamics of poly(ethylene oxide)-based lithium sulfonate ionomer samples that have low glass transition temperatures. 1H and 7Li spin-lattice relaxation times (T1) of the bulk polymer and lithium ions, respectively, were measured and analyzed in samples with a range of ion contents. The temperature dependence of T1 values along with the presence of minima in T1 as a function of temperature enabled correlation times and activation energies to be obtained for both the segmental motion of the polymer backbone and the hopping motion of lithium cations. Similar activation energies for motion of both the polymer and lithium ions in the samples with lower ion content indicate that the polymer segmental motion and lithium ion hopping motion are correlated in these samples, even though lithium hopping is about ten times slower than the segmental motion. A divergent trend is observed for correlation times and activation energies of the highest ion content sample with 100% lithium sulfonation due to the presence of ionic aggregation. Details of the polymer and cation dynamics on the nanosecond timescale are discussed and complement the findings of X-ray scattering and Quasi Elastic Neutron Scattering experiments. Polymer backbone dynamics of single ion conducting poly(ethylene oxide) (PEO)-based ionomer samples with low glass transition temperatures (T g) have been investigated using solid-state nuclear magnetic resonance (NMR). Experiments detecting 13C with 1H decoupling under magic angle spinning (MAS) conditions identified the different components and relative mobilities of the polymer backbone of a suite of. lithium- and sodium-containing ionomer samples with varying cation contents. Variable temperature (203-373 K) 1H-13C cross-polarization MAS (CP-MAS) experiments also provided qualitative assessment of the differences in the motions of the polymer backbone components as a function of

  15. Kinetics of Ethylene and Ethylene Oxide in Subcellular Fractions of Lungs and Livers of Male B6C3F1 Mice and Male Fischer 344 Rats and of Human Livers

    PubMed Central

    Csanády, György András; Kessler, Winfried; Klein, Dominik; Pankratz, Helmut; Pütz, Christian; Richter, Nadine; Filser, Johannes Georg

    2011-01-01

    Ethylene (ET) is metabolized in mammals to the carcinogenic ethylene oxide (EO). Although both gases are of high industrial relevance, only limited data exist on the toxicokinetics of ET in mice and of EO in humans. Metabolism of ET is related to cytochrome P450-dependent mono-oxygenase (CYP) and of EO to epoxide hydrolase (EH) and glutathione S-transferase (GST). Kinetics of ET metabolism to EO and of elimination of EO were investigated in headspace vessels containing incubations of subcellular fractions of mouse, rat, or human liver or of mouse or rat lung. CYP-associated metabolism of ET and GST-related metabolism of EO were found in microsomes and cytosol, respectively, of each species. EH-related metabolism of EO was not detectable in hepatic microsomes of rats and mice but obeyed saturation kinetics in hepatic microsomes of humans. In ET-exposed liver microsomes, metabolism of ET to EO followed Michaelis-Menten-like kinetics. Mean values of Vmax [nmol/(min·mg protein)] and of the apparent Michaelis constant (Km [mmol/l ET in microsomal suspension]) were 0.567 and 0.0093 (mouse), 0.401 and 0.031 (rat), and 0.219 and 0.013 (human). In lung microsomes, Vmax values were 0.073 (mouse) and 0.055 (rat). During ET exposure, the rate of EO production decreased rapidly. By modeling a suicide inhibition mechanism, rate constants for CYP-mediated catalysis and CYP inactivation were estimated. In liver cytosol, mean GST activities to EO expressed as Vmax/Km [μl/(min·mg protein)] were 27.90 (mouse), 5.30 (rat), and 1.14 (human). The parameters are most relevant for reducing uncertainties in the risk assessment of ET and EO. PMID:21785163

  16. Novel mechanism for the radiation-induced bystander effect: nitric oxide and ethylene determine the response in sponge cells.

    PubMed

    Müller, Werner E G; Ushijima, Hiroshi; Batel, Renato; Krasko, Anatoli; Borejko, Alexandra; Müller, Isabel M; Schröder, Heinz-C

    2006-05-11

    Until now the bystander effect had only been described in vertebrates. In the present study the existence of this effect has been demonstrated for the phylogenetically oldest metazoan phylum, the Porifera. We used the demosponge Suberites domuncula for the experiments in the two-chamber-system. The lower dish contained irradiated "donor" cells (single cells) and the upper dish the primmorphs ("recipient" primmorphs). The "donor" cells were treated with UV-B light (40 mJ/cm2) and 100 microM hydrogen peroxide (H2O2), factors that exist also in the natural marine aquatic environment of sponges; these factors caused a high level of DNA strand breaks followed by a reduced viability of the cells. If these cells were added to the "recipient" primmorphs these 3D-cell cultures started to undergo apoptosis. This effect could be abolished by the NO-specific scavenger PTIO and ethylene. The conclusion that NO is synthesized by the UV-B/H2O2-treated cells was supported analytically. The cDNA encoding the enzyme dimethylarginine dimethylaminohydrolase (DDAH) was isolated from the "donor" cells. High levels of DDAH transcripts were measured in UV-B/H2O2-treated "donor" cells while after ethylene treatment the steady-state level of expression drops drastically. We conclude that in the absence of ethylene the concentration of the physiological inhibitor for the NO synthase ADMA is low, due to the high level of DDAH. In consequence, high amounts of NO are released from "donor" cells which cause apoptosis in "recipient" primmorphs. In contrast, ethylene reduces the DDAH expression with the consequence of higher levels of ADMA which prevent the formation of larger amounts of NO. This study describes the radiation-induced bystander effect also for the most basal metazoans and demonstrates that this effect is controlled by the two gases NO and ethylene. PMID:16427660

  17. Ethylene effects in pea stem tissue

    SciTech Connect

    Steen, D.A.; Chadwick, A.V.

    1981-01-01

    The marked effects of ethylene on pea stem growth have been investigated. Low temperatures and colchicine, both known microtubule depolymerization agents, reverse the effects of ethylene in straight growth tests. Low temperature (6 C) also profoundly reduces the effects of gas in terms of swelling, hook curvature, and horizontal mutation. Deuterium oxide, an agent capable of rigidifying microtubular structure, mimics the effects of ethylene. Electron microscopy shows that microtubule orientation is strikingly altered by ethylene. These findings indicate that some of the ethylene responses may be due to a stabilizing effect on microtubules in plant cells.

  18. Poly(ethylene oxide)-silica hybrids entrapping sensitive dyes for biomedical optical pH sensors: Molecular dynamics and optical response

    NASA Astrophysics Data System (ADS)

    Fabbri, Paola; Pilati, Francesco; Rovati, Luigi; McKenzie, Ruel; Mijovic, Jovan

    2011-06-01

    Polymer-silica hybrid nanocomposites prepared by sol-gel process based on triethoxisilane-terminated poly(ethylene oxide) chains and tetraethoxysilane as silica precursor, doped with organic pH sensitive dyes, have been prepared and their suitability for use as sensors coupled with plastic optic fibers has been evaluated. Sensors were prepared by immobilizing a drop of the hybrid materials onto the tip of a multi-mode poly(methyl methacrylate) optical fiber. The performance of the optical sensor in terms of sensitivity and response time was tested in different experimental conditions, and was found to be markedly higher than analogous sensors present on the market. The very fast kinetic of the hybrid's optical response was supported by studies performed at the molecular level by broadband dielectric relaxation spectroscopy (DRS), investigated over a wide range of frequency and temperature, showing that poly(ethylene oxide) chains maintain their dynamics even when covalently bonded to silica domains, which decrease the self-association interactions and promote motions of polymer chain segments. Due to the fast response kinetic observed, these pH optical sensors result suitable for the fast-detection of biomedical parameters, i.e. fast esophageous pH-metry.

  19. Recyclable magnetic nanocluster crosslinked with poly(ethylene oxide)-block-poly(2-vinyl-4,4-dimethylazlactone) copolymer for adsorption with antibody.

    PubMed

    Prai-In, Yingrak; Boonthip, Chatchai; Rutnakornpituk, Boonjira; Wichai, Uthai; Montembault, Véronique; Pascual, Sagrario; Fontaine, Laurent; Rutnakornpituk, Metha

    2016-10-01

    Surface modification of magnetic nanoparticle (MNP) with poly(ethylene oxide)-block-poly(2-vinyl-4,4-dimethylazlactone) (PEO-b-PVDM) diblock copolymers and its application as recyclable magnetic nano-support for adsorption with antibody were reported herein. PEO-b-PVDM copolymers were first synthesized via a reversible addition-fragmentation chain-transfer (RAFT) polymerization using poly(ethylene oxide) chain-transfer agent as a macromolecular chain transfer agent to mediate the RAFT polymerization of VDM. They were then grafted on amino-functionalized MNP by coupling with some azlactone rings of the PVDM block to form magnetic nanoclusters with tunable cluster size. The nanocluster size could be tuned by adjusting the chain length of the PVDM block. The nanoclusters were successfully used as efficient and recyclable nano-supports for adsorption with anti-rabbit IgG antibody. They retained higher than 95% adsorption of the antibody during eight adsorption-separation-desorption cycles, indicating the potential feasibility in using this novel hybrid nanocluster as recyclable support in cell separation applications. PMID:27287124

  20. Ethylene glycol

    Integrated Risk Information System (IRIS)

    Ethylene glycol ; CASRN 107 - 21 - 1 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic E

  1. Ethylene diamine

    Integrated Risk Information System (IRIS)

    Ethylene diamine ; CASRN 107 - 15 - 3 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  2. Novel bifunctional catalysts based on crystalline multi-oxide matrices containing iron ions for CO2 hydrogenation to liquid fuels and chemicals.

    PubMed

    Utsis, N; Vidruk-Nehemya, R; Landau, M V; Herskowitz, M

    2016-07-01

    Seven solid mono-, bi- and tri-metallic oxide matrices where Fe(2+,3+) ions are distributed in different chemical/spatial environments were synthesized and characterized by XRD, N2-adsorption and EDAX methods. After basification with potassium, all matrices were activated by carburization or reduction-carburization under conditions selected based on the TPC/TPR spectra, tailoring the carburization extent of iron. The performances of the activated Fe-based catalysts with respect to CO2 conversion and C5+ selectivity were measured in a fixed-bed reactor under standard conditions in transient and continuous operation modes in units containing one or three reactors in series with water separations between the reactors. The catalysts were characterized by XRD, N2-adsorption, HRTEM-EELS and XPS before and after steady-state operation in the reactors. It was found that the rate of CO2 conversion is not limited by thermodynamic equilibrium but is strongly restricted by water inhibition and it depends on the nature of the Fe-oxide precursor. The ratio between the FTS and RWGS rates, which determines the C5+ hydrocarbons productivity, is strongly affected by the nature of the Fe-oxide matrix. The catalysts derived from the Fe-Al-O spinel and Fe-Ba-hexaaluminate precursors displayed the best balance of the two functions RFTS/RRWGS = 0.77-0.78. They were followed by magnetite, CuFe-delafossite, K-ferrite, Fe-La-hexaaluminate and LaFe-perovskite with a gradual lowering of RFTS/RRWGS from 0.60 to 0.15 and a gradual decrease in the C5+ productivity. The active sites that enhance the RWGS reaction are located on the surface of the Fe-oxide phases, while the FTS and methanation reactions occur on the surface of the Fe-carbide phases. PMID:27075823

  3. Magnetic solid phase extraction based on magnetite/reduced graphene oxide nanoparticles for determination of trace isocarbophos residues in different matrices.

    PubMed

    Yan, Shan; Qi, Ting-Ting; Chen, De-Wen; Li, Zhao; Li, Xiu-Juan; Pan, Si-Yi

    2014-06-20

    A simple one-step solvothermal method was applied for the preparation of magnetite/reduced graphene oxide (MRGO), and the synthetic nanocomposites with a magnetic particle size of ∼8nm were used as an adsorbent for magnetic solid phase extraction of isocarbophos (ICP) in different sample matrices prior to gas chromatography (GC) detection. The identity of the nanomaterial was confirmed using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. It was shown that Fe3O4 nanoparticles with a uniform size were homogeneously anchored on RGO nanosheets. Increased oxidation degrees of graphite oxide, big particle sizes and large loading amounts of Fe3O4 on the surface of RGO led to a decrease of adsorption capacity of MRGO to ICP. The adsorption behavior of this adsorbent was better fitted by the pseudo-second-order kinetic model. Several parameters affecting the extraction efficiency were investigated and optimized, including adsorbent dosage, extraction time, ionic strength and desorption conditions. And then, a rapid and effective method based on MRGO combined with GC was developed for the determination of ICP in aqueous samples. A linear range from 0.05 to 50ngmL(-1) was obtained with a high correlation coefficient (R(2)) of 0.9995, and the limit of detection was found to be 0.0044ngmL(-1). This method was successfully applied to the analysis of ICP in five kinds of samples, including apple, rice, lake water, cowpea and cabbage. The recoveries in different sample matrices were in the range from 81.00% to 108.51% with relative standard deviations less than 9.72%. It can be concluded that the proposed analytical method is highly-efficient, sensitive, precise, accurate and practicable. PMID:24800969

  4. Study on ion conductivity and crystallinity of composite polymer electrolytes based on poly(ethylene oxide)/poly(acrylonitrile) containing nano-sized Al2O3 fillers.

    PubMed

    Kim, Mingyeong; Lee, Lyungyu; Jung, Yongju; Kim, Seok

    2013-12-01

    In this paper, composite polymer electrolytes were prepared by a blend of poly(ethylene oxide) (PEO) and poly(acrylonitrile) (PAN) as a polymer matrix, ethylene carbonate as a plasticizer, LiClO4 as a salt, and by containing a different content of nano-sized Al2O3. The composite films were prepared by using the solution casting method. The crystallinity and ionic conductivity of the polymer electrolytes was investigated using X-ray diffraction (XRD) and AC impedance method, respectively. The morphology of composite polymer electrolyte film was analyzed by SEM method. From the experimental results, by increasing the Al2O3 content, the crystallinity of PEO was reduced, and the ionic conductivity was increased. In particular, by a doping of 15 wt.% Al2O3 in PEO/PAN polymer blend, the CPEs showed the superior ionic conductivity. However, when Al2O3 content exceeds 15 wt.%, the ionic conductivity was decreased. From the surface morphology, it was concluded that the ionic conductivity was decreased because the CPEs showed a heterogenous morphology due to immiscibility or aggregation of the ceramic filler within the polymer matrix. PMID:24266154

  5. Immobilization of poly(ɛ-caprolactone)-poly(ethylene oxide)-poly(ɛ-caprolactone) triblock copolymer on poly(lactide- co-glycolide) surface and dual biofunctional effects

    NASA Astrophysics Data System (ADS)

    Zhu, Aiping; Lu, Ping; Wu, Hao

    2007-01-01

    Poly(ɛ-caprolactone)-poly(ethylene oxide)-poly(ɛ-caprolactone) (PCL-PEG-PCL) triblock copolymer was covalently immobilized onto poly(lactide- co-glycolide) (PLGA) surface with the precursor of photopolymerizable and biodegradable PCL-PEG-PCL diacrylates. Argon plasma technique was exploited to obtain hydrophilic PLGA surface (HPLGA). The surface properties were characterized by Water contact angle and X-ray photoelectron spectroscopy (XPS) techniques. PCL-PEG-PCL surface modified hydrophobic PLGA and hydrophilic PLGA results in different surface physicochemical properties. PCL-PEG-PCL modified hydrophobic PLGA surface (PLGA-PCL-PEG-PCL) demonstrates excellent inhibition of platelet adhesion and activation; while PCL-PEG-PCL modified hydrophilic PLGA surface (HPLGA-PCL-PEG-PCL) results in good cytocompatibility. The possible mechanism was discussed and the driven force was ascribed to the different assembly behavior of PCL-PEG-PCL on PLGA surface dependant on the hydrophilic/hydrophobic property of PLGA. This simple and effective surface engineering method is also suitable for the other biomaterials such as polyurethane (PU), silicon rubber and poly(ethylene terephthalate) (PET) to obtain the enhanced biocompatibility.

  6. Determination of Gonyautoxin-4 in Echinoderms and Gastropod Matrices by Conversion to Neosaxitoxin Using 2-Mercaptoethanol and Post-Column Oxidation Liquid Chromatography with Fluorescence Detection

    PubMed Central

    Silva, Marisa; Rey, Verónica; Botana, Ana; Vasconcelos, Vitor; Botana, Luis

    2015-01-01

    Paralytic Shellfish Toxin blooms are common worldwide, which makes their monitoring crucial in the prevention of poisoning incidents. These toxins can be monitored by a variety of techniques, including mouse bioassay, receptor binding assay, and liquid chromatography with either mass spectrometric or pre- or post-column fluorescence detection. The post-column oxidation liquid chromatography with fluorescence detection method, used routinely in our laboratory, has been shown to be a reliable method for monitoring paralytic shellfish toxins in mussel, scallop, oyster and clam species. However, due to its high sensitivity to naturally fluorescent matrix interferences, when working with unconventional matrices, there may be problems in identifying toxins because of naturally fluorescent interferences that co-elute with the toxin peaks. This can lead to erroneous identification. In this study, in order to overcome this challenge in echinoderm and gastropod matrices, we optimized the conversion of Gonyautoxins 1 and 4 to Neosaxitoxin with 2-mercaptoethanol. We present a new and less time-consuming method with a good recovery (82.2%, RSD 1.1%, n = 3), requiring only a single reaction step. PMID:26729166

  7. Effect of Solution Conditions on the Nanoscale Intermolecular Interactions Between Human Serum Albumin and Low Grafting Density Surfaces of Poly(ethylene oxide)

    NASA Astrophysics Data System (ADS)

    Rixman, Monica; Macias, Celia; Dean, Delphine; Ortiz, Christine

    2003-03-01

    The first step in the biological rejection response to an implanted blood-contacting biomaterial is the non-covalent adsorption of proteins onto the surface, which triggers a cascade reaction ultimately resulting in thrombus formation. Using the technique of high resolution force spectroscopy, we have quantified the nonspecific intermolecular forces between fatty acid-complexed human serum albumin (HSA) covalently attached to a cantilever probe tip and individual end-grafted poly(ethylene oxide) mushrooms. In order to help elucidate the molecular origins of the constituent forces (e.g. steric, electrostatic, van der Waals), experiments were performed varying both the solution environmental conditions (e.g. ionic strength, removal of the bound fatty acids, and the addition of the antihydrophobic agent isopropanol), and the probe deflection rate.

  8. Rheological kinetics of thermo-sensitive supramolecular assemblies from poly( N-isopropyl acrylamide) and adenine-functionalized poly(ethylene oxide) stabilized by complementary multiple hydrogen bonds

    NASA Astrophysics Data System (ADS)

    Cui, Hui-Wang; Kuo, Shiao-Wei

    2014-05-01

    In this study, we synthesized a poly( N-isopropylacrylamide) (PNIPAm) through the polymerization of N-isopropylacrylamide in distilled water with azodiisobutyronitrile as the initiator and a bisadenine-functionalized poly(ethylene oxide) (A-PEO-A) from the reaction of adenine with a difunctionalized toluenesulfonyl-PEO. When blended together in distilled water, PNIPAm and A-PEO-A formed supramolecular aggregates stabilized through complementary multiple hydrogen bonds between the amide groups of PNIPAm and the adenine units of A-PEO-A. Agrawal integral equation and rheometry revealed the rheological kinetics of supramolecular assemblies, which were influenced significantly by the spherical micelles, large associated aggregates of spherical micelles, network structures, and toroid structures formed in aqueous solutions.

  9. Isothermal growth, thickening and melting of poly(ethylene-oxide) single crystals in the bulk. III. Bilayer crystals and the effect of chain ends

    NASA Astrophysics Data System (ADS)

    Kovacs, A. J.; Straupe, C.

    1980-02-01

    Growth, thickening and melting of poly(ethylene-oxide) single crystals, grown from the melt, have been investigated using three fractions of nearly the same chain length. The data are compared to and complement previous work, which is briefly recalled. The new results mainly concern the behavior of siamese twin-lamellae simultaneously grown from the same seed, modelling shish kebabs. On the other hand, the impact of a diphenyl group at one chain end is investigated in a systematic manner. The results show that these small modifications in the constitution of the crystals and in one of the chain ends give rise to rather large and often spectacular effects. The implications of these are discussed in terms of the detailed molecular conformations and mobility in the crystal lattice, in connection with current understanding of chain folding in lamellar polymer crystals.

  10. Enhanced retention of polymer physical characteristics and mechanical strength of 70:30 poly(L-lactide-co-D,L-lactide) after ethylene oxide sterilization.

    PubMed

    McManus, Anastasia J; Moser, Rodney C; Dabkowski, Rhiannon B; Thomas, Kevin A

    2007-08-01

    This study examined the effect of ethylene oxide (EtO) and electron beam (e-beam) irradiation on the properties of 70:30 poly(L-lactide-co-D,L-lactide). The effects of sterilization upon the polymer physical characteristics and strength retention of the material were examined, both initially and after being subjected to real time ageing. Commercially available 70:30 poly(L-lactide-co-D,L-lactide) material was fabricated into rectangular, cylindrical, screw, and sheet designs, and tested in compression, shear, or tension. Sterilization of 70:30 poly(L-lactide-co-D,L-lactide) by ethylene oxide had a nearly negligible effect on the physical properties of the polymer, regardless of specimen size or manufacturing technique. The molecular weight and inherent viscosity of the specimens decreased by approximately 3% after sterilization by EtO. However, sterilization of 70:30 poly(L-lactide-co-D,L-lactide) by e-beam irradiation resulted in immediate changes to some of the physical properties of the polymer. Specimens sterilized by e-beam irradiation displayed an immediate decrease in inherent viscosity of approximately 67% as compared to the respective nonsterile samples. The immediate decrease in inherent viscosity and molecular weight with e-beam irradiation required approximately 39 weeks of real time ageing of the EtO sterilized parts. At all time points investigated in the present study, the strength retention of the EtO sterilized devices equaled or exceeded that of the e-beam irradiated samples. PMID:17238162

  11. Highly mobile segments in crystalline poly(ethylene oxide)8:NaPF6 electrolytes studied by solid-state NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Luo, Huan; Liang, Xinmiao; Wang, Liying; Zheng, Anmin; Liu, Chaoyang; Feng, Jiwen

    2014-02-01

    Two types of high-crystallinity poly(ethylene oxide)/NaPF6 electrolytes with ethylene oxide (EO)/Na molar ratios of 8:1 and 6:1, termed as PEO8:NaPF6 and PEO6:NaPF6 with Mw = 6000 g mol-1 were prepared, and their ionic conductivity, structure, and segmental motions were investigated and compared. PEO8:NaPF6 polymer electrolyte exhibits the room-temperature ionic conductivity 7.7 × 10-7 S cm-1 which is about five times higher than the PEO6:NaPF6. By variable-temperature measurements of static powder spectra and 1H spin-lattice relaxation time in rotation frame (1H T1ρ), we demonstrate that crystalline segments are more highly mobile in the crystalline PEO8:NaPF6 with higher ionic conductivity than in the PEO6:NaPF6 with lower ionic conductivity. The large-angle reorientation motion of polymer segments in the PEO8:NaPF6 onsets at lower temperature (˜233 K) with a low activation energy 0.31 eV that is comparable with that of the pure PEO crystal. Whereas, the large-angle reorientation motion of polymer segments in the PEO6:NaPF6 starts around 313 K with a high activation energy of 0.91 eV. As a result of the temperature-enhanced large-angle reorientations, the 13C static powder lineshape changes markedly from a low-temperature wide pattern with apparent principal values of chemical shift δ33 < δ22 < δ11 to a high-temperature narrow pattern of uniaxial chemical shift anisotropy δ33 > δ22 (δ11). It is suggested that the segmental motion in crystalline PEO-salt complex promotes ionic conductivity.

  12. Hemoglobin adducts from acrylonitrile and ethylene oxide in cigarette smokers: effects of glutathione S-transferase T1-null and M1-null genotypes.

    PubMed

    Fennell, T R; MacNeela, J P; Morris, R W; Watson, M; Thompson, C L; Bell, D A

    2000-07-01

    Acrylonitrile (ACN) is used to manufacture plastics and fibers. It is carcinogenic in rats and is found in cigarette smoke. Ethylene oxide (EO) is a metabolite of ethylene, also found in cigarette smoke, and is carcinogenic in rodents. Both ACN and EO undergo conjugation with glutathione. The objectives of this study were to examine the relationship between cigarette smoking and hemoglobin adducts derived from ACN and EO and to investigate whether null genotypes for glutathione transferase (GSTM1 and GSTT1) alter the internal dose of these agents. The hemoglobin adducts N-(2-cyanoethyl)valine (CEVal), which is formed from ACN, and N-(2-hydroxyethyl)valine (HEVal), which is formed from EO, and GST genotypes were determined in blood samples obtained from 16 nonsmokers and 32 smokers (one to two packs/day). Smoking information was obtained by questionnaire, and plasma cotinine levels were determined by immunoassay. Glutathione transferase null genotypes (GSTM1 and GSTT1) were determined by PCR. Both CEVal and HEVal levels increased with increased cigarette smoking dose (both self-reported and cotinine-based). CEVal and HEVal levels were also correlated. GSTM1 and GSTT1 genotypes had little effect on CEVal concentrations. GSTM1 null genotypes had no significant impact on HEVal. However, HEVal levels were significantly elevated in GSTT1-null individuals when normalized to smoking status or cotinine levels. The ratio of HEVal:CEVal was also elevated in GSTT1-null smokers (1.50 +/- 0.57 versus 0.88 +/- 0.24; P = 0.0002). The lack of a functional GSTT1 is estimated to increase the internal dose of EO derived from cigarette smoke by 50-70%. PMID:10919741

  13. Effect of SiO2-acryl nanohybrid coating layers on transparent conducting oxide-poly(ethylene terephthalate) superstrate.

    PubMed

    Kang, Y T; Kang, D P; Kang, D J; Chung, I D

    2013-05-01

    SiO2-acryl nanohybrid coating layers were produced by hybridizing acrylic resin and surface-modified colloidal silica (CS) nanoparticles. First, CS nanoparticles were modified with methyltrimethoxysilane (MTMS) and vinyltrimethoxysilane (VTMS) by a sol-gel process. The surface-modified CS nanoparticles were then solvent-exchanged to be homogeneous in acrylic resin. The Hybrid materials were mixed in variation with the amount of surface-modified CS nanoparticles, coated with poly(ethylene terephthalate) (PET), then finally cured by UV light to obtain a hybrid coating layer. Field emission scanning electron microscopy (FE-SEM), particle size analysis (using a Zetasizer), and atomic force microscopy (AFM) were performed to determine the morphology of the hybrid thin-films. Thermogravimetric analysis (TGA) was used to investigate the thermal properties. Fourier-transform infrared (FTIR), ultraviolet-visible (UVNis) spectroscopies, and pencil hardness were used to obtain the details of chemical structures, optical properties, and hardness, respectively. The hybrid thin films had shown to be enhanced properties compared to their urethane acrylate prepolymer (UAP) coating film. PMID:23858925

  14. Ethylene Gas in Storage

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ethylene is a small volatile organic molecule that is produced by plants and many microbes. Potato tubers sense ethylene at concentrations of less than 1 ppm and respond to ethylene in ways that may be beneficial or detrimental for potato tuber storage. High concentrations of ethylene suppress sprou...

  15. The efficacy of antioxidant therapy against oxidative stress and androgen rise in ethylene glycol induced nephrolithiasis in Wistar rats.

    PubMed

    Naghii, M R; Jafari, M; Mofid, M; Eskandari, E; Hedayati, M; Khalagie, K

    2015-07-01

    Administration of natural antioxidants has been used to protect against nephrolithiasis. Urolithiasis was induced by ethylene glycol (EG) in Wistar rats. For 4 weeks, group 1 (control) was fed with a standard commercial diet. Group 2 received the same diet with 0.75% of EG. Group 3 received EG plus the diet and water added with antioxidant nutrients and lime juice as the dietary source of citrate (EG + AX). Group 4 same as group 3 with no EG in water. For 8 weeks, group 5 was fed the standard diet with EG in water for the first 28 days, followed by no EG. Group 6 received the diet with EG for the first 28 days, followed by discontinuation of EG and addition of antioxidant nutrients. Group 7 were provided the diet with antioxidant nutrients for 8 weeks. Group 8 received the diet with antioxidant nutrients for 4 weeks, followed by antioxidant nutrients with EG for the next 4 weeks. Blood samples were collected and kidneys were removed. The size and the mean number of crystal deposits in EG-treated groups was significantly higher than the EG-treated groups, added with antioxidant nutrients and lime juice. After 4 weeks, the mean concentration of malondialdehyde in group 2 was higher than the group 3, and significantly lower in group 4; and in groups 7 after 8 weeks, as well. After 8 weeks, supplementation developed less mean number of deposits in group 6 as compared to group 5; and in group 8, the crystal deposits was substantially less than either group 2 or group 5 (EG-treated rats). Elevated concentration of androgens (as promoters of the formation of renal calculi) as a result of EG consumption decreased following antioxidant supplementations. Results showed a beneficial effect of antioxidant and provided superior renal protection on treating and preventing stone deposition in the rat kidney. PMID:25392345

  16. Viscoelastic Properties, Ionic Conductivity, and Materials Design Considerations for Poly(styrene-b-ethylene oxide-b-styrene)-Based Ion Gel Electrolytes

    SciTech Connect

    Zhang, Sipei; Lee, Keun Hyung; Sun, Jingru; Frisbie, C. Daniel; Lodge, Timothy P.

    2013-03-07

    The viscoelastic properties and ionic conductivity of ion gels based on the self-assembly of a poly(styrene-b-ethylene oxide-b-styrene) (SOS) triblock copolymer (M{sub n,S} = 3 kDa, M{sub n,O} = 35 kDa) in the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMI][TFSA]) were investigated over the composition range of 10-50 wt % SOS and the temperature range of 25-160 C. The poly(styrene) (PS) end-blocks associate into micelles, whereas the poly(ethylene oxide) (PEO) midblocks are well-solvated by this ionic liquid. The ion gel with 10 wt % SOS melts at 54 C, with the longest relaxation time exhibiting a similar temperature dependence to that of the viscosity of bulk PS. However, the actual values of the gel relaxation time are more than 4 orders of magnitude larger than the relaxation time of bulk PS. This is attributed to the thermodynamic penalty of pulling PS end-blocks through the PEO/[EMI][TFSA] matrix. Ion gels with 20-50 wt % SOS do not melt and show two plateaus in the storage modulus over the temperature and frequency ranges measured. The one at higher frequencies is that of an entangled network of PEO strands with PS cross-links; the modulus displays a quadratic dependence on polymer weight fraction and agrees with the prediction of linear viscoelastic theory assuming half of the PEO chains are elastically effective. The frequency that separates the two plateaus, {omega}{sub c}, reflects the time scale of PS end-block pull-out. The other plateau at lower frequencies is that of a congested micelle solution with PS cores and PEO coronas, which has a power law dependence on domain spacing similar to diblock melts. The ionic conductivity of the ion gels is compared to PEO homopolymer solutions at similar polymer concentrations; the conductivity is reduced by a factor of 2.1 or less, decreases with increasing PS volume fraction, and follows predictions based on a simple obstruction model. Our collective results allow the formulation

  17. The influence of Ir and Pt1Ir1 structure in metallic multilayers nanoarchitectured electrodes towards ethylene glycol electro-oxidation

    NASA Astrophysics Data System (ADS)

    Freitas, R. G.; Antunes, E. P.; Christensen, P. A.; Pereira, E. C.

    2012-09-01

    This paper presents a study of the electro-oxidation of ethylene glycol (EG) at metallic multilayer electrodes: Ptpc/Irx/Pty (Ptpc = polycrystalline Pt, x and y denote the number of monolayers of Ir intralayer and Pt outer layer, respectively) and Ptpc/(Pt1Ir1)x/Pty (ie a 1:1 alloy of Pt and Ir was employed as intralayer). For comparison, data are also presented for Ptpc. Although Pt and Ir have similar crystallographic structures, the work reported shows for the first time that the electrocatalytic properties of the Pt outer layer are affected significantly by the composition of the intralayer. The voltammetry data show that the Ptpc/Ir3.0/Pt3.0 metallic multilayer electrode exhibits a peak current density 78% higher than that observed using Ptpc, in agreement with activation energy measurements on the electro-oxidation of EG which showed: Ptpc/Ir3.0/Pt3.0 (26 kJ mol-1) < Ptpc (44 kJ mol-1) < Ptpc/(Pt1Ir1)3.0/Pt3.0 (46 kJ mol-1). The FTIR experiments showed that the main products for the oxidation of the diol at the electrodes are similar: COL, CO2 and glycolic and/or oxalic acid over Ptpc and Ptpc/Ir3.0/Pt3.0 metallic multilayer electrodes. However, significantly more CO2 and COL were observed at Ptpc/Ir3.0/Pt3.0 compared to Ptpc electrodes.

  18. Effect of 1-Butyl-3-methylimidazolium Halide on the Relative Stability between Sodium Dodecyl Sulfate Micelles and Sodium Dodecyl Sulfate-Poly(ethylene oxide) Nanoaggregates.

    PubMed

    Ferreira, Gabriel M Dias; Ferreira, Guilherme M Dias; Agudelo, Álvaro J Patiño; Hespanhol da Silva, Maria C; Rezende, Jaqueline de Paula; Pires, Ana Clarissa Dos Santos; da Silva, Luis Henrique Mendes

    2015-12-24

    It is well-known that ionic liquids (ILs) alter the properties of aqueous systems containing only surfactants. However, the effect of ILs on polymer-surfactant systems is still unknown. Here, the effect of 1-butyl-3-methylimidazolium bromide (bmimBr) and chloride (bmimCl) on the micellization of sodium dodecyl sulfate (SDS) and its interaction with poly(ethylene oxide) (PEO) was evaluated using conductimetry, fluorimetry, and isothermal titration calorimetry. The ILs decreased the critical micellar concentration (cmc) of the surfactant, stabilizing the SDS micelles. A second critical concentration (c2thc) was verified at high SDS concentrations, due to the micelle size decrease. The stability of PEO/SDS aggregates was also affected by ILs, and the critical aggregation concentration (cac) of SDS increased. Integral aggregation enthalpy changed from -0.72 in water to 2.16 kJ mol(-1) in 4.00 mM bmimBr. IL anions did not affect the SDS micellization or the beginning of PEO/SDS aggregation. Nevertheless, when chloride was replaced with bromide, the amount of SDS bound to the polymer increased. At 100.0 mM IL, the PEO-SDS interaction vanished. We suggest that the effect of ILs comes from participating in the structure of the formed aggregates, interacting with the SDS monomers at the core/interface of the micelles, and promoting preferential solvation of the polymer. PMID:26595360

  19. Structural tailoring of hydrogen-bonded poly(acrylic acid)/poly(ethylene oxide) multilayer thin films for reduced gas permeability.

    PubMed

    Xiang, Fangming; Ward, Sarah M; Givens, Tara M; Grunlan, Jaime C

    2015-02-01

    Hydrogen bonded poly(acrylic acid) (PAA)/poly(ethylene oxide) (PEO) layer-by-layer assemblies are highly elastomeric, but more permeable than ionically bonded thin films. In order to expand the use of hydrogen-bonded assemblies to applications that require a better gas barrier, the effect of assembling pH on the oxygen permeability of PAA/PEO multilayer thin films was investigated. Altering the assembling pH leads to significant changes in phase morphology and bonding. The amount of intermolecular hydrogen bonding between PAA and PEO is found to increase with increasing pH due to reduction of COOH dimers between PAA chains. This improved bonding leads to smaller PEO domains and lower gas permeability. Further increasing the pH beyond 2.75 results in higher oxygen permeability due to partial deprotonation of PAA. By setting the assembling pH at 2.75, the negative impacts of COOH dimer formation and PAA ionization on intermolecular hydrogen bonding can be minimized, leading to a 50% reduction in the oxygen permeability of the PAA/PEO thin film. A 20 bilayer coating reduces the oxygen transmission rate of a 1.58 mm natural rubber substrate by 20 ×. These unique nanocoatings provide the opportunity to impart a gas barrier to elastomeric substrates without altering their mechanical behavior. PMID:25519816

  20. An in vitro study of bare and poly(ethylene glycol)-co-fumarate-coated superparamagnetic iron oxide nanoparticles: a new toxicity identification procedure

    NASA Astrophysics Data System (ADS)

    Mahmoudi, Morteza; Simchi, Abdolreza; Imani, Mohammad; Milani, Abbas S.; Stroeve, Pieter

    2009-06-01

    As the use of superparamagnetic iron oxide nanoparticles (SPION) in biomedical applications increases (e.g. for targeting drug delivery and imaging), patients are likely to be exposed to products containing SPION. Despite their high biomedical importance, toxicity data for SPION are limited to date. The aim of this study is to investigate the cytotoxicity of SPION and its ability to change cell medium components. Bare and poly(ethylene glycol)-co-fumarate (PEGF)-coated SPION with narrow size distributions were synthesized. The particles were prepared by co-precipitation using ferric and ferrous salts with a molar Fe3+/Fe2+ ratio of 2. Dulbecco's modified Eagle's medium (DMEM) and primary mouse fibroblast (L929) cell lines were exposed to the SPION. Variation of cell medium components and cytotoxicity due to the interactions with nanoparticles were analyzed using ultraviolet and visible spectroscopy (UV/vis) and the 3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium bromide (MTT) assay methods, respectively. The toxicity amount has been traditionally identified by changes in pH and composition in cells and DMEM due to the tendency of SPION to adsorb proteins, vitamins, amino acids and ions. For in vitro toxicity assessments, a new surface passivation procedure is proposed which can yield more reliable quantitative results. It is shown that a more reliable way of identifying cytotoxicity for in vitro assessments is to use particles with saturated surfaces via interactions with DMEM before usage.

  1. On-line sample preconcentration by sweeping and poly(ethylene oxide)-mediated stacking for simultaneous analysis of nine pairs of amino acid enantiomers in capillary electrophoresis.

    PubMed

    Lin, En-Ping; Lin, Kai-Cheng; Chang, Chia-Wei; Hsieh, Ming-Mu

    2013-09-30

    This study proposes a sensitive method for the simultaneous separation and concentration of 9 pairs of amino acid enantiomers by combining poly(ethylene oxide) (PEO)-based stacking, β-cyclodextrin (β-CD)-mediated micellar electrokinetic chromatography (MEKC), and 9-fluoroenylmethyl chloroformate (FMOC) derivatization. The 9 pairs of FMOC-derivatized amino acid enantiomers were baseline separated using a discontinuous system, and the buffer vials contained a solution of 150 mM Tris-borate (TB), 12.5% (v/v) isopropanol (IPA), 0.5% (w/v) PEO, 35 mM sodium taurodeoxycholate (STDC), and 35 mM β-CD, and the capillary was filled with a solution of 1.5 M TB, 12.5% (v/v) IPA, 35 mM STDC, and 35 mM β-CD. Based on the difference in viscosity between the sample zone and PEO solution and because of the STDC sweeping, the discontinuous system effectively stacked 670 nL of the 9 pairs of FMOC-derivatized amino acid enantiomers without losing chiral resolution. Consequently, the limits of detection for the 9 pairs of FMOC-derivatized amino acid enantiomers were reduced to 40-60 nM. This method was successfully used to determine d-Tryptophan (Trp), l-Trp, d-Phenylalanine (Phe), l-Phe, d-Glutamic acid (Glu), and l-Glu in various types of beers. PMID:23953474

  2. Polyelectrolyte-surfactant complexes formed by poly[3,5-bis(trimethylammoniummethyl)4-hydroxystyrene iodide]-block-poly(ethylene oxide) and sodium dodecyl sulfate in aqueous solutions.

    PubMed

    Štěpánek, Miroslav; Matějíček, Pavel; Procházka, Karel; Filippov, Sergey K; Angelov, Borislav; Šlouf, Miroslav; Mountrichas, Grigoris; Pispas, Stergios

    2011-05-01

    Formation of polyelectrolyte-surfactant (PE-S) complexes of poly[3,5-bis(trimethylammoniummethyl)-4-hydroxystyrene iodide]-block-poly(ethylene oxide) (QNPHOS-PEO) and sodium dodecyl sulfate (SDS) in aqueous solution was studied by dynamic and electrophoretic light scattering, small-angle X-ray scattering (SAXS), atomic force microscopy, and fluorometry, using pyrene as a fluorescent probe. SAXS data from the QNPHOS-PEO/SDS solutions were fitted assuming contributions from free copolymer, PE-S aggregates described by a mass fractal model, and densely packed surfactant micelles inside the aggregates. It was found that, unlike other systems of a double hydrophilic block polyelectrolyte and an oppositely charged surfactant, PE-S aggregates of the QNPHOS-PEO/SDS system do not form core-shell particles and the PE-S complex precipitates before reaching the charge equivalence between dodecyl sulfate anions and QNPHOS polycationic blocks, most likely because of conformational rigidity of the QNPHOS blocks, which prevents the system from the corresponding rearrangement. PMID:21446735

  3. Preparation of magnetic core-shell iron oxide@silica@nickel-ethylene glycol microspheres for highly efficient sorption of uranium(VI).

    PubMed

    Tan, Lichao; Zhang, Xiaofei; Liu, Qi; Wang, Jun; Sun, Yanbo; Jing, Xiaoyan; Liu, Jingyuan; Song, Dalei; Liu, Lianhe

    2015-04-21

    We report a facile approach for the formation of magnetic core-shell iron oxide@silica@nickel-ethylene glycol (Fe3O4@SiO2@Ni-L) microspheres. The structure and morphology of Fe3O4@SiO2@Ni-L are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen sorption isotherm. The composite possesses a high specific surface area of 382 m(2) g(-1). The obtained core/shell structure is composed of a superparamagnetic core with a strong response to external fields, which are recovered readily from aqueous solutions by magnetic separation. When used as the adsorbent for uranium(vi) in water, the as-prepared Fe3O4@SiO2@Ni-L multi-structural microspheres exhibit a high adsorption capacity, which is mainly attributed to the large specific surface area and typical mesoporous characteristics of Fe3O4@SiO2@Ni-L microspheres. This work provides a promising approach for the design and synthesis of multifunctional microspheres, which can be used for water treatment, as well as having other potential applications in a variety of biomedical fields including drug delivery and biosensors. PMID:25773512

  4. Conformational and Dynamic Properties of Poly(ethylene oxide) in an Ionic Liquid: Development and Implementation of a First-Principles Force Field.

    PubMed

    McDaniel, Jesse G; Choi, Eunsong; Son, Chang-Yun; Schmidt, J R; Yethiraj, Arun

    2016-01-14

    The conformational properties of polymers in ionic liquids are of fundamental interest but not well understood. Atomistic and coarse-grained molecular models predict qualitatively different results for the scaling of chain size with molecular weight, and experiments on dilute solutions are not available. In this work, we develop a first-principles force field for poly(ethylene oxide) (PEO) in the ionic liquid 1-butyl 3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) using symmetry adapted perturbation theory (SAPT). At temperatures above 400 K, simulations employing both the SAPT and OPLS-AA force fields predict that PEO displays ideal chain behavior, in contrast to previous simulations at lower temperature. We therefore argue that the system shows a transition from extended to more compact configurations as the temperature is increased from room temperature to the experimental lower critical solution temperature. Although polarization is shown to be important, its implicit inclusion in the OPLS-AA force is sufficient to describe the structure and energetics of the mixture. The simulations emphasize the difference between ionic liquids from typical solvents for polymers. PMID:26690901

  5. Biological and Tribological Assessment of Poly(Ethylene Oxide Terephthalate)/Poly(Butylene Terephthalate), Polycaprolactone, and Poly (L\\DL) Lactic Acid Plotted Scaffolds for Skeletal Tissue Regeneration.

    PubMed

    Hendrikson, Wilhelmus J; Zeng, Xiangqiong; Rouwkema, Jeroen; van Blitterswijk, Clemens A; van der Heide, Emile; Moroni, Lorenzo

    2016-01-21

    Additive manufactured scaffolds are fabricated from three commonly used biomaterials, polycaprolactone (PCL), poly (L\\DL) lactic acid (P(L\\DL)LA), and poly(ethylene oxide terephthalate)/poly(butylene terephthalate) (PEOT/PBT). Scaffolds are compared biologically and tribologically. Cell-seeded PEOT/PBT scaffolds cultured in osteogenic and chondrogenic differentiation media show statistical significantly higher alkaline phosphatase (ALP) activity/DNA and glycosaminoglycans (GAG)/DNA ratios, followed by PCL and P(L\\DL)LA scaffolds, respectively. The tribological performance is assessed by determining the friction coefficients of the scaffolds at different loads and sliding velocities. With increasing load or decreasing sliding velocity, the friction coefficient value decreases. PEOT/PBT show to have the lowest friction coefficient value, followed by PCL and P(L\\DL)LA. The influence of the scaffold architecture is further determined with PEOT/PBT. Reducing of the fiber spacing results in a lower friction coefficient value. The best and the worst performing scaffold architecture are chosen to investigate the effect of cell culture on the friction coefficient. Matrix deposition is low in the cell-seeded scaffolds and the effect is, therefore, undetermined. Taken together, our studies show that PEOT/PBT scaffolds support better skeletal differentiation of seeded stromal cells and lower friction coefficient compared to PCL and P(L/DL)A scaffolds. PMID:26775915

  6. The preparation and characterization of highly aligned poly(epsilon-caprolactone)/poly ethylene oxide/chitosan ultrafine fiber for the application to tissue scaffold.

    PubMed

    Nien, Yu-Hsun; Wang, Jia-Yi; Tsai, Yan-Sheng

    2013-07-01

    The purpose of this study was to fabricate poly(epsilon-caprolactone) (PCL)/poly ethylene oxid (PEO)/chitosan (CS) ultrafine fiber in both aligned and random structures using electrospinning technique and their process parameters were optimized. The aligned and random PCL/PEO/chitosan ultrafine fibers were also used as scaffold for tissue engineering and their cell affinity was investigated. In the first part, we inspected the effect of environment conditions, solution properties, process parameters on PCL/PEO/chitosan ultrafine fiber. In the second part, the apparatus of electrospinning to manufacture highly aligned PCL/PEO/chitosan ultrafine fiber was developed. The effects of process parameters such as flow rate, design of collector and rotation speed of collecting drum on the morphology of ultrafine fiber were discussed. In addition, the cross link of PCL/PEO/chitosan ultrafine fiber by cross-linking agent was examined, too. The physical properties, chemical properties, and cell affinities of the aligned PCL/PEO/chitosan ultrafine fiber with or without cross link were measured. The chemical analysis and tensile strength of the ultrafine fiber were characterized using Fourier Transfer Infared Spectrophotometer and Universal Tensile Machine, respectively. The results show that the aligned PCL/PEO/chitosan ultrafine fibrous mat had the capacity to induce cellular alignment and enhance cellular elongation. PMID:23901493

  7. Organic-inorganic random copolymers from methacrylate-terminated poly(ethylene oxide) with 3-methacryloxypropylheptaphenyl polyhedral oligomeric silsesquioxane: synthesis via RAFT polymerization and self-assembly behavior.

    PubMed

    Wei, Kun; Li, Lei; Zheng, Sixun; Wang, Ge; Liang, Qi

    2014-01-14

    In this contribution, we report the synthesis of organic-inorganic random polymers from methacrylate-terminated poly(ethylene oxide) (MAPEO) (Mn = 950) and 3-methacryloxypropylheptaphenyl polyhedral oligomeric silsesquioxane (MAPOSS) macromers via reversible addition-fragmentation chain transfer (RAFT) polymerization with 4-cyano-4-(thiobenzoylthio) valeric acid (CTBTVA) as the chain transfer agent. The organic-inorganic random copolymers were characterized by means of (1)H NMR spectroscopy, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The results of GPC indicate that the polymerizations were carried out in a controlled fashion. Transmission electron microscopy (TEM) showed that the organic-inorganic random copolymers in bulk were microphase-separated and the POSS microdomains were formed via POSS-POSS interactions. In aqueous solutions the organic-inorganic random copolymers were capable of self-assembling into spherical nanoobjects as evidenced by transmission electron microscopy (TEM) and dynamic laser scattering (DLS). The self-assembly behavior of the organic-inorganic random copolymers was also found to occur in the mixtures with the precursors of epoxy. The nanostructures were further fixed via subsequent curing reaction and thus the organic-inorganic nanocomposites were obtained. The formation of nanophases in epoxy thermosets was confirmed by transmission electron microscopy (TEM) and dynamic mechanical thermal analysis (DMTA). The organic-inorganic nanocomposites displayed the enhanced surface hydrophobicity as evidenced by surface contact angle measurements. PMID:24651714

  8. Quantitative control of poly(ethylene oxide) surface antifouling and biodetection through azimuthally enhanced grating coupled-surface plasmon resonance sensing

    NASA Astrophysics Data System (ADS)

    Sonato, Agnese; Silvestri, Davide; Ruffato, Gianluca; Zacco, Gabriele; Romanato, Filippo; Morpurgo, Margherita

    2013-12-01

    Grating Coupled-Surface Plasmon reflectivity measurements carried out under azimuth and polarization control (GC-SPR φ ≠ 0°) were used to optimize the process of gold surface dressing with poly(ethylene oxide) (PEO) derivatives of different molecular weight, with the final goal to maximize the discrimination between specific and non-specific binding events occurring at the surface. The kinetics of surface deposition of thiol-ending PEOs (0.3, 2 and 5 kDa), introduced as antifouling layers, was monitored. Non-specific binding events upon immersion of the surfaces into buffers containing either 0.1% bovine serum albumin or 1% Goat Serum, were evaluated as a function of polymer size and density. A biorecognition event between avidin and biotin was then monitored in both buffers at selected low and high polymer surface densities and the contribution of analyte and fouling elements to the signal was precisely quantified. The 0.3 kDa PEO film was unable to protect the surface from non-specific interactions at any tested density. On the other hand, the 2 and 5 kDa polymers at their highest surface densities guaranteed full protection from non-specific interactions from both buffers. These densities were reached upon a long deposition time (24-30 h). The results pave the way toward the application of this platform for the detection of low concentration and small dimension analytes, for which both non-fouling and high instrumental sensitivity are fundamental requirements.

  9. Core–Shell Structure of Monodisperse Poly(ethylene glycol)-Grafted Iron Oxide Nanoparticles Studied by Small-Angle X-ray Scattering

    PubMed Central

    2015-01-01

    The promising applications of core–shell nanoparticles in the biological and medical field have been well investigated in recent years. One remaining challenge is the characterization of the structure of the hydrated polymer shell. Here we use small-angle X-ray scattering (SAXS) to investigate iron oxide core–poly(ethylene glycol) brush shell nanoparticles with extremely high polymer grafting density. It is shown that the shell density profile can be described by a scaling model that takes into account the locally very high grafting density near the core. A good fit to a constant density region followed by a star-polymer-like, monotonously decaying density profile is shown, which could help explain the unique colloidal properties of such densely grafted core–shell nanoparticles. SAXS experiments probing the thermally induced dehydration of the shell and the response to dilution confirmed that the observed features are associated with the brush and not attributed to structure factors from particle aggregates. We thereby demonstrate that the structure of monodisperse core–shell nanoparticles with dense solvated shells can be well studied with SAXS and that different density models can be distinguished from each other. PMID:26321792

  10. CO2-Free Power Generation on an Iron Group Nanoalloy Catalyst via Selective Oxidation of Ethylene Glycol to Oxalic Acid in Alkaline Media

    PubMed Central

    Matsumoto, Takeshi; Sadakiyo, Masaaki; Ooi, Mei Lee; Kitano, Sho; Yamamoto, Tomokazu; Matsumura, Syo; Kato, Kenichi; Takeguchi, Tatsuya; Yamauchi, Miho

    2014-01-01

    An Fe group ternary nanoalloy (NA) catalyst enabled selective electrocatalysis towards CO2-free power generation from highly deliverable ethylene glycol (EG). A solid-solution-type FeCoNi NA catalyst supported on carbon was prepared by a two-step reduction method. High-resolution electron microscopy techniques identified atomic-level mixing of constituent elements in the nanoalloy. We examined the distribution of oxidised species, including CO2, produced on the FeCoNi nanoalloy catalyst in the EG electrooxidation under alkaline conditions. The FeCoNi nanoalloy catalyst exhibited the highest selectivities toward the formation of C2 products and to oxalic acid, i.e., 99 and 60%, respectively, at 0.4 V vs. the reversible hydrogen electrode (RHE), without CO2 generation. We successfully generated power by a direct EG alkaline fuel cell employing the FeCoNi nanoalloy catalyst and a solid-oxide electrolyte with oxygen reduction ability, i.e., a completely precious-metal-free system. PMID:25004118

  11. Nanoporous nonwoven fibril-like morphology by cooperative self-assembly of poly(ethylene oxide)-block-poly(ethyl acrylate)-block-polystyrene and phenolic resin.

    PubMed

    Deng, Guodong; Qiang, Zhe; Lecorchick, Willis; Cavicchi, Kevin A; Vogt, Bryan D

    2014-03-11

    Cooperative self-assembly of block copolymers with (in)organic precursors effectively generates ordered nanoporous films, but the porosity is typically limited by the need for a continuous (in)organic phase. Here, a network of homogeneous fibrous nanostructures (≈20 nm diameter cylinders) having high porosity (≈ 60%) is fabricated by cooperative self-assembly of a phenolic resin oligomer (resol) with a novel, nonfrustrated, ABC amphiphilic triblock copolymer template, poly(ethylene oxide)-block-poly(ethyl acrylate)-block-polystyrene (PEO-b-PEA-b-PS), via a thermally induced self-assembly process. Due to the high glass transition temperature (Tg) of the PS segments, the self-assembly behavior is kinetically hindered as a result of competing effects associated with the ordering of the self-assembled system and the cross-linking of resol that suppresses segmental mobility. The balance in these competing processes reproducibly yields a disordered fibril network with a uniform fibril diameter. This nonequilibrium morphology is dependent on the PEO-b-PEA-b-PS to resol ratio with an evolution from a relatively open fibrous structure to an apparent poorly ordered mixed lamellae-cylinder morphology. Pyrolysis of these former films at elevated temperatures yields a highly porous carbon film with the fibril morphology preserved through the carbonization process. These results illustrate a simple method to fabricate thin films and coatings with a well-defined fiber network that could be promising materials for energy and separation applications. PMID:24548298

  12. A Mode-Locked Soliton Erbium-Doped Fiber Laser with a Single-Walled Carbon Nanotube Poly-Ethylene Oxide Film Saturable Absorber

    NASA Astrophysics Data System (ADS)

    Z. R. R. Rosdin, R.; F., Ahmad; M. Ali, N.; M. Nor, R.; R. Zulkepely, N.; W. Harun, S.; Arof, H.

    2014-09-01

    We present a simple, compact and low-cost mode-locked erbium-doped fiber laser (EDFL) using single-walled carbon nanotubes (SWCNTs) embedded in a poly-ethylene oxide (PEO) thin film as a passive saturable absorber. The film is fabricated by using a prepared homogeneous SWCNT solution, which is mixed with a diluted PEO solution and cast onto a glass Petri dish to form, by evaporation, a thin film. The 50 μm-thick film is sandwiched between two fiber connectors to construct a saturable absorber, which is then integrated in an EDFL cavity to generate self-started stable soliton pulses operating at 1560.8 nm. The soliton pulse starts to lase at a pump power threshold of 12.3 mW with a repetition rate of 11.21 MHz, a pulse width of 1.02 ps, an average output power of 0.65 mW and a pulse energy of 57.98 pJ.

  13. Stability of Water/Poly(ethylene oxide)43-b-poly(ε-caprolactone)14/Cyclohexanone Emulsions Involves Water Exchange between the Core and the Bulk.

    PubMed

    Flores, Mario E; Martínez, Francisco; Olea, Andrés F; Shibue, Toshimichi; Sugimura, Natsuhiko; Nishide, Hiroyuki; Moreno-Villoslada, Ignacio

    2015-12-31

    The formation of emulsions upon reverse self-association of the monodisperse amphiphilic block copolymer poly(ethylene oxide)43-b-poly(ε-caprolactone)14 in cyclohexanone is reported. Such emulsions are not formed in toluene, chloroform, or dichloromethane. We demonstrate by magnetic resonance spectroscopy the active role of the solvent on the stabilization of the emulsions. Cyclohexanone shows high affinity for both blocks, as predicted by the Hansen solubility parameters, so that the copolymer chains are fully dissolved as monomeric chains. In addition, the solvent is able to produce hydrogen bonding with water molecules. Water undergoes molecular exchange between water molecules associated with the polymer and water molecules associated with the solvent, dynamics of major importance for the stabilization of the emulsions. Association of polymeric chains forming reverse aggregates is induced by water over a concentration threshold of 5 wt %. Reverse copolymer aggregates show submicron average hydrodynamic diameters, as seen by dynamic light scattering, depending on the polymer and water concentration. PMID:26637018

  14. Synthesis and characterizations of palladium catalysts with high activity and stability for formic acid oxidation by hydrogen reduction in ethylene glycol at room temperature

    NASA Astrophysics Data System (ADS)

    Wu, Meixia; Li, Muwu; Wu, Xin; Li, Yuexia; Zeng, Jianhuang; Liao, Shijun

    2015-10-01

    In this work, a Pd/C catalyst with high activity as well as excellent stability has been prepared by hydrogen gas reduction of Pd(II) precursor in ethylene glycol solution with the assistance of appropriate amount of sodium citrate. Pd nanoparticles with an average particle size of 3.8 nm and excellent uniformity are obtained. The Pd/C catalyst synthesized in this work shows an electrochemical surface area of 68.6 m2 g-1 and displays activities of 819 A g-1. Strikingly, the Pd/C catalyst also exhibits excellent stability, which has been confirmed by its slow activity decay under repeated potential cycles as well as chronoamperometric test. The activity for Pd/C at the 300th and 500th cycle remains at 5.5 and 2.4 mA cm-2, respectively, which is 25% and 11% of its initial value, respectively. The oxidation currents at the Pd/C and Pd/C-Citrate (control) at 0 V decrease to 44% and 25% of their initial values. Transmission electron microscopy observations on the Pd/C catalyst after 1000 potential cycles reveal that, in addition to carbon support corrosion, Pd agglomeration together with more serious Pd dissolution occur at the same time, leading to a decrease of the electrocatalytic performance.

  15. Reversible de-intercalation and intercalation induced by polymer crystallization and melting in a poly(ethylene oxide)/organoclay nanocomposite.

    PubMed

    Sun, Lu; Ertel, Ethan A; Zhu, Lei; Hsiao, Benjamin S; Avila-Orta, Carlos A; Sics, Igors

    2005-06-21

    Semicrystalline polymer/layered silicate nanocomposites were prepared by solution blending of a low molecular weight poly(ethylene oxide) (PEO) with an organically modified montmorillonite, Cloisite 10A (C10A). The intercalation morphology was studied by temperature-dependent synchrotron wide-angle X-ray diffraction (WAXD). Unlike PEO homopolymers, significant secondary crystallization was observed in the PEO/C10A nanocomposites. Reversible de-intercalation and intercalation processes were detected during secondary crystallization and subsequent melting of secondary crystals. On the basis of two-dimensional WAXD results on oriented samples, an interphase layer between the silicate primary particles and PEO lamellar crystals was proposed. Secondary PEO crystallization in the interphase regions was inferred to be the primary driving force for polymer chains to diffuse out of the silicate gallery. This study provided a useful method to investigate polymer diffusion in nanoconfined spaces, which can be controlled by PEO secondary crystallization and melting outside the silicate gallery. PMID:15952806

  16. Mesoscale simulation of the formation and dynamics of lipid-structured poly(ethylene oxide)-block-poly(methyl methacrylate) diblock copolymers.

    PubMed

    Mu, Dan; Li, Jian-Quan; Feng, Sheng-Yu

    2015-05-21

    Twelve poly(ethylene oxide)-block-poly(methyl methacrylate) (PEO-b-PMMA) copolymers with lipid-like structures were designed and investigated by MesoDyn simulation. Spherical and worm-like micelles as well as bicontinuous, lamellar and defected lamellar phases were obtained. A special structure, designated B2412, with two lipid structures connected by their heads, was found to undergo four stages prior to forming a spherical micelle phase. Two possible assembly mechanisms were found via thermodynamic and dynamic process analyses; namely, the fusion and fission of micelles in dynamic equilibrium during the adjustment stage. Water can be encapsulated into these micelles, which can affect their size, particularly in low concentration aqueous solutions. The assignment of weak negative charges to the hydrophilic EO blocks resulted in a clear effect on micelle size. Surprisingly, the largest effect was observed with EO blocks with -0.5 e, wherein an ordered perfect hexagonal phase was formed. The obtained results can be applied in numerous fields of study, including adsorption, catalysis, controlled release and drug delivery. PMID:25898853

  17. Fluorescence spectroscopy of individual semiconductor nanoparticles in different ethylene glycols.

    PubMed

    Flessau, Sandra; Wolter, Christopher; Pöselt, Elmar; Kröger, Elvira; Mews, Alf; Kipp, Tobias

    2014-06-14

    The optical properties of single colloidal semiconductor nanoparticles (NPs) are considerably influenced by the direct environment of the NPs. Here, the influence of different liquid and solid glycol matrices on CdSe-based NPs is investigated. Since the fluorescence of individual NPs varies from one NP to another, it is highly desirable to study the very same individual NPs in different matrices. This was accomplished by immobilizing NPs in a liquid cell sample holder or in microfluidic devices. The samples have been investigated by space-resolved wide-field fluorescence microscopy and energy- and time-resolved confocal scanning fluorescence microscopy with respect to fluorescence intensities, emission energies, blinking behavior, and fluorescence decay dynamics of individual NPs. During the measurements the NPs were exposed to air, to liquid ethylene glycols H(OCH2CH2)nOH (also called EGn) with different chain lengths (1 ≤ n ≤ 7), to liquid 2-methylpentane-2,3-diol, or to solid polyethylene oxide. It was found that EG6-7 (also known as PEG 300) is very well suited as a liquid matrix or solvent for experiments that correlate chemical and physical modifications of the surface and of the immediate environment of individual NPs to their fluorescence properties since it leads to intense and stable fluorescence emission of the NPs. PMID:24788878

  18. Change in the Affinity of Ethylene Glycol Methacrylate Phosphate Monomer and Its Polymer Anchored on a Graphene Oxide Platform toward Uranium(VI) and Plutonium(IV) Ions.

    PubMed

    Chappa, Sankararao; Singha Deb, Ashish K; Ali, Sk Musharaf; Debnath, A K; Aswal, D K; Pandey, Ashok K

    2016-03-24

    The complexation behavior of the carbonyl and phosphoryl ligating groups bearing ethylene glycol methacrylate phosphate (EGMP) monomer and its polymer fixed on a graphene oxide (GO) platform was studied to understand the coordination ability of segregated EGMP units and polymer chains toward UO2(2+) and Pu(4+) ions. The cross-linked poly(EGMP) gel and EGMP dissolved in solution have a similar affinity toward these ions. UV-initiator induced polymerization was used to graft poly(EGMP) on the GO platform utilizing a double bond of EGMP covalently fixed on it. X-ray photoelectron spectroscopy (XPS) of the GO and GO-EGMP was done to confirm covalent attachment of the EGMP via a -C-O-P- link between GO and EGMP. The extent of poly(EGMP) grafting on GO by thermal analyses was found to be 5.88 wt %. The EGMP units fixed on the graphene oxide platform exhibited a remarkable selectivity toward Pu(4+) ions at high HNO3 conc. where coordination is a dominant mode involved in the sorption of ions. The ratio of distribution coefficients of Pu(IV) to U(VI) (DPu(IV)/DU(VI)) followed a trend as cross-linked poly(EGMP) (0.95) < EGMP in solvent methyl isobutyl ketone (1.3) < GO-poly(EGMP) (25) < GO-EGMP (181); the DPu(IV)/DU(VI) values are given in parentheses. The density functional theory computations have been performed for the complexation of UO2(2+) and Pu(4+) ions with the EGMP molecule anchored on GO in the presence of nitrate ions. This computational modeling suggested that Pu(4+) ion formed a strong coordination complex with phosphoryl and carbonyl ligating groups of the GO-EGMP as compared to UO2(2+) ions. Thus, the nonselective EGMP becomes highly selective to Pu(IV) ions when it interacts as a single unit fixed on a GO platform. PMID:26926256

  19. Effects of Salts and Ionic Liquids on the Thermodynamics of Poly(ethylene oxide)-Containing Block Copolymers

    NASA Astrophysics Data System (ADS)

    Wanakule, Nisita; Virgili, Justin; Teran, Alexander; Balsara, Nitash

    2010-03-01

    We explore the thermodynamics of block copolymers doped with the salt, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and the ionic liquid, imidazolium bis(trifluoromethanesulfonyl) imide ([Im][TFSI]). The block copolymers comprise of polyethylene oxide (PEO), a polymer with a higher dielectric constant, and polystyrene (PS), a polymer with a lower dielectric constant. A combination of small-angle x-ray scattering (SAXS) and birefringence was used to determine morphology and order-to-disorder transition temperatures (ODT). Leibler's theory for microphase separation was employed to determine the effective Flory-Huggins interaction parameter. These values are compared to theoretically-determined values of the effective interaction parameter which were calculated with no adjustable parameters using a theory developed by Zhen-Gang Wang.

  20. Ethylene process design optimization

    SciTech Connect

    2001-09-01

    Integration of Advanced Technologies will Update Ethylene Plants. Nearly 93 million tons of ethylene are produced annually in chemical plants worldwide, using an energy intensive process that consumes 2.5 quadrillion Btu per year.

  1. 7Li NMR spectroscopy and ion conduction mechanism in mesoporous silica (SBA-15) composite poly(ethylene oxide) electrolyte

    NASA Astrophysics Data System (ADS)

    Reddy, M. Jaipal; Chu, Peter P.

    A composite of mesoporous silica (SBA-15) with a polyethylene oxide (PEO) polymer electrolyte is examined for use in various electrochemical devices. Incorporation of SBA-15 in a PEO:LiClO 4 polymer electrolyte facilitates salt dissociation, enhances ion conductivity, and improves miscibility between organic and inorganic moieties. Optimized conductivity is found at 10 wt.% SBA-15 composition, above this concentration the conductivity is reduced due to aggregation of a SBA-15:Li rich phase. Heating above melt temperature of PEO allows more of the polymer segments to interact with SBA-15. This results in a greater degree of disorder upon cooling, and the ion conductivity is enhanced. A 7Li MAS NMR study reveals three types of lithium-ion coordination. Two major types of conduction mechanism can be identified: one through conventional amorphous PEO; a second via hopping in a sequential manner by replacing the nearby vacancies ('holes') on the surface (both interior and exterior) of the SBA-15 channels.

  2. Structural effect of glyme-Li(+) salt solvate ionic liquids on the conformation of poly(ethylene oxide).

    PubMed

    Chen, Zhengfei; McDonald, Samila; Fitzgerald, Paul A; Warr, Gregory G; Atkin, Rob

    2016-06-01

    The conformation of 36 kDa polyethylene oxide (PEO) dissolved in three glyme-Li(+) solvate ionic liquids (SILs) has been investigated by small angle neutron scattering (SANS) and rheology as a function of concentration and compared to a previously studied SIL. The solvent quality of a SIL for PEO can be tuned by changing the glyme length and anion type. Thermogravimetric analysis (TGA) reveals that PEO is dissolved in the SILs through Li(+)-PEO coordinate bonds. All SILs (lithium triglyme bis(trifluoromethanesulfonyl)imide ([Li(G3)]TFSI), lithium tetraglyme bis(pentafluoroethanesulfonyl)imide ([Li(G4)]BETI), lithium tetraglyme perchlorate ([Li(G4)]ClO4) and the recently published [Li(G4)]TFSI) are found to be moderately good solvents for PEO but solvent quality decreases in the order [Li(G4)]TFSI ∼ [Li(G4)]BETI > [Li(G4)]ClO4 > [Li(G3)]TFSI due to decreased availability of Li(+) for PEO coordination. For the same glyme length, the solvent qualities of SILs with TFSI(-) and BETI(-) anions ([Li(G4)]TFSI and [Li(G4)]BETI) are very similar because they weakly coordinate with Li(+), which facilitates Li(+)-PEO interactions. [Li(G4)]ClO4 presents a poorer solvent environment for PEO than [Li(G4)]BETI because ClO4(-) binds more strongly to Li(+) and thereby hinders interactions with PEO. [Li(G3)]TFSI is the poorest PEO solvent of these SILs because G3 binds more strongly to Li(+) than G4. Rheological and radius of gyration (Rg) data as a function of PEO concentration show that the PEO overlap concentrations, c* and c**, are similar in the three SILs. PMID:27189677

  3. In situ immobilization of proteins and RGD peptide on polyurethane surfaces via poly(ethylene oxide) coupling polymers for human endothelial cell growth.

    PubMed

    Wang, Dong-an; Ji, Jian; Sun, Yong-hong; Shen, Jia-cong; Feng, Lin-xian; Elisseeff, Jennifer H

    2002-01-01

    A "CBABC"-type pentablock coupling polymer, mesylMPEO, was designed and synthesized to promote human endothelial cell growth on the surfaces of polyurethane biomaterials. The polymer was composed of a central 4,4'-methylenediphenyl diisocyanate (MDI) coupling unit and poly(ethylene oxide) (PEO) spacer arms with methanesulfonyl (mesyl) end groups pendent on both ends. As the presurface modifying additive (pre-SMA), the mesylMPEO was noncovalently introduced onto the poly(ether urethane) (PEU) surfaces by dip coating, upon which the protein/peptide factors (gelatin, albumin, and arginine-glycine-aspartic acid tripeptide [RGD]) were covalently immobilized in situ by cleavage of the original mesyl end groups. The pre-SMA synthesis and PEU surface modification were characterized using nuclear magnetic resonance spectroscopy ((1)H NMR), attenuated total reflection infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). Human umbilical vein endothelial cells (HUVEC) were harvested manually by collagenase digestion and seeded on the modified PEU surfaces. Cell adhesion ratios (CAR) and cell proliferation ratios (CPR) were measured using flow cytometry, and the individual cell viability (ICV) was determined by MTT assay. The cell morphologies were investigated by optical inverted microscopy (OIM) and scanning electrical microscopy (SEM). The gelatin- and RGD-modified surfaces were HUVEC-compatible and promoted HUVEC growth. The albumin-modified surfaces were compatible but inhibited cell adhesion. The results also indicated that, for HUVEC in vitro cultivation, the cell adhesion stage was of particular importance and had a significant impact on the cell responses to the modified surfaces. PMID:12425667

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

    PubMed

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

    2005-09-01

    In this paper, we have addressed the question of the dynamic miscibility in a blend characterized by very different glass-transition temperatures, Tg, for the components: poly(ethylene oxide) and poly(methyl methacrylate) (PEO/PMMA). The combination of quasielastic neutron scattering with isotopic labeling and fully atomistic molecular dynamics simulations has allowed us to selectively investigate the dynamics of the two components in the picosecond-10 nanoseconds scale at temperatures close and above the Tg of the blend. The main focus was on the PEO component, i.e., that of the lowest Tg, but first we have characterized the dynamics of the other component in the blend and of the pure PEO homopolymer as reference. In the region investigated, the dynamics of PMMA in the blend is strongly affected by the alpha-methyl rotation; an additional process detected in the experimental window 65 K above the blend-Tg can be identified as the merged alphabeta process of this component that shows strong deviations from Gaussian behavior. On the other hand, pure PEO displays entropy driven dynamics up to very large momentum transfers. Such kind of motion seems to freeze when the PEO chains are in the blend. There, we have directly observed a very heterogeneous and moreover confined dynamics for the PEO component. The presence of the hardly moving PMMA matrix leads to the creation of little pockets of mobility where PEO can move. The characteristic size of such confined islands of mobility might be estimated to be of approximately 1 nm. These findings are corroborated by the simulation study, which has been an essential support and guide in our data analysis procedure. PMID:16241474

  5. Bioaffinity sensor based on nanoarchitectonic films: control of the specific adsorption of proteins through the dual role of an ethylene oxide spacer.

    PubMed

    Davila, Johanna; Toulemon, Delphine; Garnier, Tony; Garnier, Aurélie; Senger, Bernard; Voegel, Jean-Claude; Mésini, Philippe J; Schaaf, Pierre; Boulmedais, Fouzia; Jierry, Loïc

    2013-06-18

    The identification and quantification of biomarkers or proteins is a real challenge in allowing the early detection of diseases. The functionalization of the biosensor surface has to be properly designed to prevent nonspecific interactions and to detect the biomolecule of interest specifically. A multilayered nanoarchitecture, based on polyelectrolyte multilayers (PEM) and the sequential immobilization of streptavidin and a biotinylated antibody, was elaborated as a promising platform for the label-free sensing of targeted proteins. We choose ovalbumin as an example. Thanks to the versatility of PEM films, the platform was built on two types of sensor surface and was evaluated using both optical- and viscoelastic-based techniques, namely, optical waveguide lightmode spectroscopy and the quartz crystal microbalance, respectively. A library of biotinylated poly(acrylic acids) (PAAs) was synthesized by grafting biotin moieties at different grafting ratios (GR). The biotin moieties were linked to the PAA chains through ethylene oxide (EO) spacers of different lengths. The adsorption of the PAA-EOn-biotin (GR) layer on a PEM precursor film allows tuning the surface density in biotin and thus the streptavidin adsorption mainly through the grafting ratio. The nonspecific adsorption of serum was reduced and even suppressed depending on the length of the EO arms. We showed that to obtain an antifouling polyelectrolyte the grafting of EO9 or EO19 chains at 25% in GR is sufficient. Thus, the spacer has a dual role: ensuring the antifouling property and allowing the accessibility of biotin moieties. Finally, an optimized platform based on the PAA-EO9-biotin (25%)/streptavidin/biotinylated-antibody architecture was built and demonstrated promising performance as interface architecture for bioaffinity sensing of a targeted protein, in our case, ovalbumin. PMID:23346932

  6. Dynamics of a poly(ethylene oxide) tracer in a poly(methyl methacrylate) matrix: Remarkable decoupling of local and global motions

    NASA Astrophysics Data System (ADS)

    Haley, Jeffrey C.; Lodge, Timothy P.

    2005-06-01

    The tracer diffusion coefficient of unentangled poly(ethylene oxide) (PEO, M =1000g/mol) in a matrix of poly(methyl methacrylate) (PMMA, M =10000g/mol) has been measured over a temperature range from 125to220°C with forced Rayleigh scattering. The dynamic viscosities of blends of two different high molecular weight PEO tracers (M =440000 and 900000g/mol) in the same PMMA matrix were also measured at temperatures ranging from 160to220°C; failure of time-temperature superposition was observed for these systems. The monomeric friction factors for the PEO tracers were extracted from the diffusion coefficients and the rheological relaxation times using the Rouse model. The friction factors determined by diffusion and rheology were in good agreement, even though the molecular weights of the tracers differed by about three orders of magnitude. The PEO monomeric friction factors were compared with literature data for PEO segmental relaxation times measured directly with NMR. The monomeric friction factors of the PEO tracer in the PMMA matrix were found to be from two to six orders of magnitude greater than anticipated based on direct measurements of segmental dynamics. Additionally, the PEO tracer terminal dynamics are a much stronger function of temperature than the corresponding PEO segmental dynamics. These results indicate that the fastest PEO Rouse mode, inferred from diffusion and rheology, is completely separated from the bond reorientation of PEO detected by NMR. This result is unlike other blend systems in which global and local motions have been compared.

  7. Investigation of the aqueous dissolution of semicrystalline poly(ethylene oxide) using infrared chemical imaging: the effects of molecular weight and crystallinity.

    PubMed

    Coutts-Lendon, Carrie; Koenig, Jack L

    2005-08-01

    Fourier transform infrared (FT-IR) imaging was used to successfully explore several factors influencing the dissolution of poly(ethylene oxide). The effect of the degree of crystallinity on the rate of dissolution of mid-range molecular weight PEO was negligible over the temperature ranges studied. The influence of molecular weight on polymer dissolution was found to be much greater than the changes in morphology. An examination of the polymer and solvent images and absorbance profiles, compared with the results of the bulk polymer/solvent boundary movement, confirmed this relationship. An investigation of the bulk polymer/solvent boundary using a crystalline-sensitive polymer band showed the crystalline to amorphous phase change occurred over a short distance. Moreover, solvent diffusion ahead of the bulk polymer/solvent front was minimal, most likely a result of the required phase change, which in turn regulated the degree of solvent ingress. Modeling of the dissolution was performed using the Peppas (power law) model. Physical parameters of the dissolution process were obtained from fitting the release profiles to the power law (fraction released = k x t(n), where k is the dissolution rate constant and n is the release exponent). Results indicated the model worked well to describe dissolution at all molecular weights. By varying the number of data points input to the model and then comparing the generated graphs, it becomes clear that not only does the dissolution slow down over the course of the experiment, but an increase in molecular weight enhances this effect. The effect of different types of drug on the rate of polymer dissolution was also studied. The dissolution of neat polymer was compared to the dissolution of polymer containing 10% (by weight) of theophylline, etophylline, or testosterone. The general trend of all the dissolution curves was the same, with the addition of etophylline and testosterone tracing almost the same route in terms of movement

  8. The surface grafting of graphene oxide with poly(ethylene glycol) as a reinforcement for poly(lactic acid) nanocomposite scaffolds for potential tissue engineering applications.

    PubMed

    Zhang, Chunmei; Wang, Liwei; Zhai, Tianliang; Wang, Xinchao; Dan, Yi; Turng, Lih-Sheng

    2016-01-01

    Graphene oxide (GO) was incorporated into poly(lactic acid) (PLA) as a reinforcing nanofiller to produce composite nanofibrous scaffolds using the electrospinning technique. To improve the dispersion of GO in PLA and the interfacial adhesion between the filler and matrix, GO was surface-grafted with poly(ethylene glycol) (PEG). Morphological, thermal, mechanical, and wettability properties, as well as preliminary cytocompatibility with Swiss mouse NIH 3T3 cells of PLA, PLA/GO, and PLA/GO-g-PEG electrospun nanofibers, were characterized. Results showed that the average diameter of PLA/GO-g-PEG electrospun nanofibers decreased with filler content. Both GO and GO-g-PEG improved the thermal stability of PLA, but GO-g-PEG was more effective. The water contact angle test of the nanofiber mats showed that the addition of GO in PLA did not change the surface wettability of the materials, but PLA/GO-g-PEG samples exhibited improved wettability with lower water contact angles. The tensile strength of the composite nanofiber mats was improved with the addition of GO, and it was further enhanced when GO was surface grafted with PEG. This suggested that improved interfacial adhesion between GO and PLA was achieved by grafting PEG onto the GO. The cell viability and proliferation results showed that the cytocompatibility of PLA was not compromised with the addition of GO and GO-g-PEG. With enhanced mechanical properties as well as good wettability and cytocompatibility, PLA/GO-g-PEG composite nanofibers have the potential to be used as scaffolds in tissue engineering. PMID:26409231

  9. Fundamental and harmonic soliton mode-locked erbium-doped fiber laser using single-walled carbon nanotubes embedded in poly (ethylene oxide) film saturable absorber

    NASA Astrophysics Data System (ADS)

    Rosdin, R. Z. R. R.; Zarei, A.; Ali, N. M.; Arof, H.; Ahmad, H.; Harun, S. W.

    2015-01-01

    This paper presents a simple, compact and low cost mode-locked Erbium-doped fiber laser (EDFL) using a single-walled carbon nanotubes (SWCNTs) embedded in poly(ethylene oxide) (PEO) film as a passive saturable absorber. The film was fabricated using a prepared homogeneous SWCNT solution, which was mixed with a diluted PEO solution and casted onto a glass petri dish to form a thin film by evaporation technique. The film, with a thickness of 50 μm, is sandwiched between two fiber connectors to construct a saturable absorber, which is then integrated in an EDFL cavity to generate a self-started stable soliton pulses operating at 1560.8 nm. The soliton pulse starts to lase at 1480 nm pup power threshold of 12.3 mW to produce pulse train with repetition rate of 11.21 MHz, pulse width of 1.02 ps, average output power of 0.65 mW and pulse energy of 57.98 pJ. Then, we observed the 4th, 7th and 15th harmonic of fundamental cavity frequency start to occur when the pump powers are further increased to 14.9, 17.5 and 20.1 mW, respectively. The 4th harmonic pulses are characterized in detail with a repetition rate of 44.84 MHz, a transform-limited pulse width of 1.19 ps, side-mode suppression ratio of larger than 20 dB and pulse energy of 9.14 pJ.

  10. Properties controlling the diffusion and release of water-soluble solutes from poly(ethylene oxide) hydrogels. 2. Dispersion in an initially dry slab.

    PubMed

    McNeill, M E; Graham, N B

    1993-01-01

    The mechanisms which control the release of dispersed water-soluble drugs from an initially dry hydrogel are complex. The release profile derives from a combination of several contributing factors which may change with time at different rates. It has been possible to isolate controlling factors and investigate their individual contributions to the release kinetics. The hydrogels presented in this paper owe their hydrophilicity to their poly(ethylene oxide) content. They swell and can absorb up to three times their dry weight in water. Having a glass transition temperature (Tg) below body temperature they are essentially different to those studied theoretically or experimentally, by other groups, which have Tg values above body temperature and are initially glassy. A range of diffusates was studied ranging from low water-soluble prostaglandin E2 to highly water-soluble lithium chloride. Device geometry was restricted to approximations to infinite slabs with more than 85% total surface area over the top and bottom surfaces so that release was predominantly one-dimensional and the controlling variable was thickness. The increase in surface area with time, drug-solubility in the water-swelling matrix and the presence of crystallinity were shown to be important factors governing the profile and level of release rate with time. It was observed that the release profile could be separated into three parts, the most important being the middle section from early in the release until at least the half-life time. This period could be characterized by the exponential time function, tn. The diffusional exponent, n, is an important indicator of the release mechanism and ranged from 0.79 to 1, i.e. good anomalous to zero order. This is a highly desirable range of values for controlled release devices. The value of n decreases at late-time. The very early-time release can also show a burst or lag effect depending on the diffusate solubility and its loading in the xerogel. PMID

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

    SciTech Connect

    Genix, A.-C.; Arbe, A.

    2005-09-01

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

  12. Microfluidic synthesis of dye-loaded polycaprolactone-block-poly(ethylene oxide) nanoparticles: Insights into flow-directed loading and in vitro release for drug delivery.

    PubMed

    Bains, Aman; Wulff, Jeremy E; Moffitt, Matthew G

    2016-08-01

    Using the fluorescent probe dye 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) as a surrogate for hydrophobic drugs, we investigate the effects of water content and on-chip flow rate on the multiscale structure, loading and release properties of DiI-loaded poly(ε-caprolactone)-block-poly(ethylene oxide) (PCL-b-PEO) nanoparticles produced in a gas-liquid segmented microfluidic device. We find a linear increase in PCL crystallinity within the nanoparticle cores with increasing flow rate, while mean nanoparticle sizes first decrease and then increase with flow rate coincident with the disappearance and reappearance of long filament nanoparticles. Loading efficiencies at the lower water content (cwc+10wt%) are generally higher (up to 94%) compared to loading efficiencies (up to 53%) at the higher water content (cwc+75wt%). In vitro release times range between ∼2 and 4days for nanoparticles produced at cwc+10wt% and >15days for nanoparticles produced at cwc+75wt%. At the lower water content, slower release of DiI is found for nanoparticles produced at higher flow rate, while at high water content, release times first decrease and then increase with flow rate. Finally, we investigate the effects of the chemical and physical characteristics of the release medium on the kinetics of in vitro DiI release and nanoparticle degradation. This work demonstrates the general utility of dye-loaded nanoparticles as model systems for screening chemical and flow conditions for producing drug delivery formulations within microfluidic devices. PMID:27163840

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

    PubMed

    Ved, Parag M; Kim, Kwonho

    2011-06-15

    The purpose of this study was to investigate the olfactory transfer of zidovudine (ZDV) after intranasal (IN) administration and to assess the effect of thermoreversible gelling system on its absorption and brain uptake. The nasal formulation was prepared by dissolving ZDV in pH 5.5 phosphate buffer solution comprising of 20% polyethylene oxide/propylene oxide (Poloxamer 407, PLX) as thermoreversible gelling agent and 0.1% n-tridecyl-β-D-maltoside (TDM) as permeation enhancer. This formulation exhibited a sufficient stability and an optimum gelation profile at 27-30 °C. The in vitro permeation studies across the freshly excised rabbit nasal mucosa showed a 53% increase in the permeability of ZDV from the formulation. For in vivo evaluation, the drug concentrations in the plasma, cerebrospinal fluid (CSF) and six different regions of the brain tissues, i.e. olfactory bulb (OB), olfactory tract (OT), anterior, middle and posterior segments of cerebrum (CB), and cerebellum (CL) were determined by LC/MS method following IV and IN administration in rabbits at a dose of 1mg/kg. The IN administration of Poloxamer 407 and TDM based formulation showed a systemic bioavailability of 29.4% while exhibiting a 4 times slower absorption process (t(max) = 20 min) than control solution (t(max) = 5 min). The CSF and brain ZDV levels achieved after IN administration of the gelling formulation were approximately 4.7-56 times greater than those attained after IV injection. The pharmacokinetic and brain distribution studies revealed that a polar antiviral compound, ZDV could preferentially transfer into the CSF and brain tissue via an alternative pathway, possibly olfactory route after intranasal administration. PMID:21356294

  14. Self-Assembly and Chain-Folding in Hybrid Coil-Coil-Cube Triblock Oligomers of Polyethylene-b-Poly(ethylene Oxide)-b-Polyhedral Oligomeric Silsesquioxane

    SciTech Connect

    Miao,J.; Cui, L.; Lau, H.; Mather, P.; Zhu, L.

    2007-01-01

    Self-assembly and chain-folding in well-defined oligomeric polyethylene-block-poly(ethylene oxide)-block-polyhedral oligomeric silsesquioxane (PE-b-PEO-b-POSS) triblock molecules were studied by small-angle X-ray scattering (SAXS), wide-angle X-ray diffraction (WAXD), and transmission electron microscopy (TEM). The triblock oligomers were synthesized by attaching two kinds of functional POSS molecules, namely, isocyanatopropyldimethylsilylisobutyl-POSS (Ib-POSS) and isocyanatopropyldimethylsilylcyclopentyl-POSS (Cp-POSS), to a hydroxyl-terminated PE-b-PEO-OH diblock oligomer (denoted as E{sub 39}EO{sub 23}) via urethane reactions. In these triblock oligomers, both PE and POSS were crystalline, whereas PEO became amorphous due to tethering of its both ends to other two blocks. In the crystalline state, PE chains tilted 32{sup o} from the lamellar normal, and both Ib-POSS and Cp-POSS molecules stacked into four-layer (ABCA) lamellar crystals, having the same trigonal (R{bar 3}m) symmetry as in pure POSS crystals. Because the cross-sectional area for a PE chain in the PE crystals (0.216 nm{sup 2}/chain) at the interface was much smaller than that for a POSS molecule in POSS crystals (1.136 nm{sup 2}/molecule), the self-assembly and PE chain-folding were substantially affected by the sequence of PE and POSS crystallization when crystallizing from the melt. For example, PE crystallization induced the POSS crystallization in the bulk E{sub 39}EO{sub 23}-Ib-POSS, and thus extended-chain PE crystals were observed. The grains of crystalline lamellae again were small with often highly curved lamellar crystals. This could also be attributed to the unbalanced interfacial areas for POSS and PE blocks (the interfacial area ratio being 2.6 for interdigitated PE crystals, i.e., two PE chains per POSS molecule). For the E{sub 39}EO{sub 23}-Cp-POSS triblock oligomer, POSS molecules crystallized before PE crystallization, forming a well-defined lamellar structure. The preexisting

  15. Properties and mechanisms of drug release from matrix tablets containing poly(ethylene oxide) and poly(acrylic acid) as release retardants.

    PubMed

    Zhang, Feng; Meng, Fan; Lubach, Joseph; Koleng, Joseph; Watson, N A

    2016-08-01

    The interactions between poly(ethylene oxide) (PEO) and poly(acrylic acid) (PAA) in aqueous medium at pH 6.8 were investigated in the current study. We have also studied the effect of interpolymer interactions and various formulation variables, including the molecular weight of PEO, the ratio between PEO and PAA, the crystallinity of PEO, and the presence of an acidifying agent, on the release of theophylline from matrix tablets containing both PEO and PAA as release retardants. At pH 6.8, the synergy in solution viscosity between PEO and PAA as the result of ion-dipole interaction was observed in this study. The release of theophylline from the matrix tablets containing physical mixtures of PEO and PAA was found to be a function of dissolution medium pH because of the pH-dependent interactions between these two polymers. Because of the formation of water insoluble interpolymer complex between PEO and PAA in aqueous medium at pH below 4.0, the release of theophylline was independent of PEO molecular weight and was controlled by Fickian diffusion mechanism in 0.01N hydrochloric acid solution. In comparison, the drug release was a function of PEO molecular weight and followed the anomalous transport mechanism in phosphate buffer pH 6.8. The presence of PAA exerted opposite effects on the release of theophylline in phosphate buffer pH 6.8. In one aspect, theophylline release was accelerated because the erosion of PAA was much faster than that of PEO at pH6.8. On the opposite aspect, theophylline release was slowed down because of the formation of insoluble complex inside the gel layer as the result of the acidic microenvironment induced by PAA, and the increase in the viscosity of the gel layer as the result of the synergy between PEO and PAA. These two opposite effects offset each other. As a result, the release of theophylline remained statistically the same even when 75% PEO in the formulation was replaced with PAA. In phosphate buffer pH 6.8, the release of

  16. Self-associating poly(ethylene oxide)-b-poly(alpha-cholesteryl carboxylate-epsilon-caprolactone) block copolymer for the solubilization of STAT-3 inhibitor cucurbitacin I.

    PubMed

    Mahmud, Abdullah; Patel, Sarthak; Molavi, Ommoleila; Choi, Phillip; Samuel, John; Lavasanifar, Afsaneh

    2009-03-01

    An increase in the degree of chemical compatibility between drug and polymeric structure in the core has been shown to raise the encapsulation efficiency and lower the rate of drug release from polymeric micelles. In this study, to achieve an optimized polymeric micellar delivery system for the solubilization and controlled delivery of cucurbitacin I (CuI), the Flory-Huggins interaction parameter (chi(sc)) between CuI and poly(epsilon-caprolactone) (PCL), poly(alpha-benzylcarboxylate-epsilon-caprolactone) (PBCL) and poly(alpha-cholesteryl carboxylate-epsilon-caprolactone) (PChCL) structures was calculated by group contribution method (GCM) as an indication for the degree of chemical compatibility between different micellar core structures and CuI. The results pointed to a better compatibility between CuI and PChCL core rationalizing the synthesis of self-associating methoxy poly(ethylene oxide)-b-poly(alpha-cholesteryl carboxylate-epsilon-caprolactone) block copolymer (MePEO-b-PChCL). Novel block copolymer of MePEO-b-PChCL was synthesized through, first, preparation of substituted monomer, that is, alpha-cholesteryl carboxylate-epsilon-caprolactone, and further ring opening polymerization of this monomer by methoxy PEO (5000 g mol(-1)) using stannous octoate as catalyst. Synthesized block copolymers were characterized for their molecular weight and polydispersity by (1)H NMR and gel permeation chromatography. Self-assembled MePEO-b-PChCL micelles were characterized for their size, morphology, critical micellar concentration (CMC), capacity for the physical encapsulation of CuI, and mode of CuI release in comparison to MePEO-b-PCL and MePEO-b-PBCL micelles. Overall, the experimental order for the level of CuI encapsulation in different polymeric micellar formulations was consistent with what was predicted by the Flory-Huggins interaction parameter. Although MePEO-b-PChCL micelles exhibited the highest level of CuI loading, this structure did not show any significant

  17. Solid State Nuclear Magnetic Resonance Investigation of Polymer Backbone Dynamics in Poly(Ethylene Oxide) Based Lithium and Sodium Polyether-ester-sulfonate Ionomers

    SciTech Connect

    Roach, David J.; Dou, Shichen; Colby, Ralph H.; Mueller, Karl T.

    2013-01-01

    Polymer backbone dynamics of single ion conducting poly(ethylene oxide) (PEO)-based ionomer samples with low glass transition temperatures (Tg) have been investigated using solid-state nuclear magnetic resonance (NMR). Experiments detecting 13C with 1H decoupling under magic angle spinning (MAS) conditions identified the different components of the polymer backbone (PEO spacer and isophthalate groups) and their relative mobilities for a suite of lithium- and sodium-containing ionomer samples with varying cation contents. Variable temperature (203-373 K) 1H-13C cross-polarization MAS (CP-MAS) experiments also provided qualitative assessment of the differences in the motions of the polymer backbone components as a function of cation content and identity. Each of the main backbone components exhibit distinct motions, following the trends expected for motional characteristics based on earlier Quasi Elastic Neutron Scattering and 1H spin-lattice relaxation rate measurements. Previous 1H and 7Li spin-lattice relaxation measurements focused on both the polymer backbone and cation motion on the nanosecond timescale. The studies presented here assess the slower timescale motion of the polymer backbone allowing for a more comprehensive understanding of the polymer dynamics. The temperature dependences of 13C linewidths were used to both qualitatively and quantitatively examine the effects of cation content and identity on PEO spacer mobility. Variable contact time 1H-13C CP-MAS experiments were used to further assess the motions of the polymer backbone on the microsecond timescale. The motion of the PEO spacer, reported via the rate of magnetization transfer from 1H to 13C nuclei, becomes similar for T ≳ 1.1 Tg in all ionic samples, indicating that at similar elevated reduced temperatures the motions of the polymer backbones on the microsecond timescale become insensitive to ion interactions. These results present an improved picture, beyond those of previous findings, for

  18. Solid state nuclear magnetic resonance investigation of polymer backbone dynamics in poly(ethylene oxide) based lithium and sodium polyether-ester-sulfonate ionomers

    NASA Astrophysics Data System (ADS)

    Roach, David J.; Dou, Shichen; Colby, Ralph H.; Mueller, Karl T.

    2013-05-01

    Polymer backbone dynamics of single ion conducting poly(ethylene oxide) (PEO)-based ionomer samples with low glass transition temperatures (Tg) have been investigated using solid-state nuclear magnetic resonance. Experiments detecting 13C with 1H decoupling under magic angle spinning (MAS) conditions identified the different components of the polymer backbone (PEO spacer and isophthalate groups) and their relative mobilities for a suite of lithium- and sodium-containing ionomer samples with varying cation contents. Variable temperature (203-373 K) 1H-13C cross-polarization MAS (CP-MAS) experiments also provided qualitative assessment of the differences in the motions of the polymer backbone components as a function of cation content and identity. Each of the main backbone components exhibit distinct motions, following the trends expected for motional characteristics based on earlier Quasi Elastic Neutron Scattering and 1H spin-lattice relaxation rate measurements. Previous 1H and 7Li spin-lattice relaxation measurements focused on both the polymer backbone and cation motion on the nanosecond timescale. The studies presented here assess the slower timescale motion of the polymer backbone allowing for a more comprehensive understanding of the polymer dynamics. The temperature dependences of 13C linewidths were used to both qualitatively and quantitatively examine the effects of cation content and identity on PEO spacer mobility. Variable contact time 1H-13C CP-MAS experiments were used to further assess the motions of the polymer backbone on the microsecond timescale. The motion of the PEO spacer, reported via the rate of magnetization transfer from 1H to 13C nuclei, becomes similar for T ˜x 1{.1} Tg in all ionic samples, indicating that at similar elevated reduced temperatures the motions of the polymer backbones on the microsecond timescale become insensitive to ion interactions. These results present an improved picture, beyond those of previous findings, for the

  19. Polyplex formation between four-arm poly(ethylene oxide)-b-poly(2-(diethylamino)ethyl methacrylate) and plasmid DNA in gene delivery.

    PubMed

    He, E; Yue, C Y; Simeon, F; Zhou, L H; Too, H P; Tam, K C

    2009-12-01

    Amphiphilic polyelectrolytes comprising cationic and uncharged hydrophilic segments condensed negatively charged DNA to form a core-shell structure stabilized by a layer of hydrophilic corona chains. At physiological pH, four-arm star-shaped poly(ethylene oxide)-b-poly(2-(diethylamino)ethyl methacrylate) (four-arm PEO-b-PDEAEMA) block copolymer possessed positively charged amine groups that interacted with negatively charged plasmid DNA to form polymer/DNA complexes. The mechanism and physicochemical properties of the complex formation were investigated at varying molar ratio of amine groups on polymer chains and phosphate group on plasmid DNA segments (N/P ratio). The capability of the star block copolymer to condense DNA was demonstrated through gel electrophoresis and ethidium bromide exclusion assay. In the absence of salt, the hydrodynamic radius of polyplexes was about 94 nm at low polymer/DNA ratio, and it decreased to about 34 nm at large N/P ratios, forming a compact spherical structure with a weighted average molecular weight of 4.39 +/- 0.22 x 10(6) g/mol. Approximately 15 polymeric chains were required to condense a plasmid DNA. The addition of monovalent salt to the polyplexes significantly altered the size of the complexes, which would have an impact on cell transfection. Because of the electrostatic interaction induced by the diffusion of small ions, the polyplex increased in size to about 53 nm with a less compact structure. In vitro cytotoxicty of polymer and polymer/pDNA complexes were evaluated, and the polyplexes exhibited low toxicity at low N/P ratios. At N/P ratio of 4.5, the four-arm PEO-b-PDEAEMA showed the highest level of transfection in Neuro-2A cells. These observations showed that the star-shaped multi-arm polymers offers interesting properties in self-association and condensation ability for plasmid DNA and can serve as a nonviral DNA delivery system. PMID:19048636

  20. Higher dimensional Hadamard matrices

    NASA Technical Reports Server (NTRS)

    Schlichta, P. J.

    1979-01-01

    The paper defines higher dimensional Hadamard matrices and enumerates on some of the simplest three-, four-, and five-dimensional cases and procedures for generating them. Special emphasis is given to proper matrices that have a dimensional hierarchy of orthogonalities. It is determined that this property lends itself primarily to the application of higher dimensional Hadamard matrices to error-correcting codes. A list of derived statements for n-dimensional Hadamard matrices are given, as well as a definition of Hadamard matrix families, such as minimal, Petrie polygon, antipodal (n-2)-dimensional sections, and double proximity shells.

  1. Poly(ethylene oxide)-block-polyphosphoester-graft-paclitaxel Conjugates with Acid-labile Linkages as a pH-Sensitive and Functional Nanoscopic Platform for Paclitaxel Delivery

    PubMed Central

    Zou, Jiong; Zhang, Fuwu; Zhang, Shiyi; Pollack, Stephanie F.; Elsabahy, Mahmoud; Fan, Jingwei; Wooley, Karen L.

    2013-01-01

    There has been an increasing interest to develop new types of stimuli-responsive drug delivery vehicles with high drug loading and controlled release properties for chemotherapeutics. An acid-labile, polyphosphoester-based degradable, polymeric paclitaxel (PTX) conjugate containing ultra-high levels of PTX loading has been improved significantly, in this second generation development, which involves connection of each PTX molecule to the polymer backbone via a pH-sensitive β-thiopropionate linkage. The results for this system indicate that it has great potential as an effective anti-cancer agent. Poly(ethylene oxide)-block-polyphosphoester-graft-PTX drug conjugate (PEO-b-PPE-g-PTX G2) was synthesized by organocatalyst-promoted ring-opening polymerization of 2-(but-3-en-1-yloxy)-1,3,2-dioxaphospholane-2-oxide from a PEO macroinitiator, followed by thermo-promoted thiolene click conjugation of a thiol-functionalized PTX prodrug to the pendant alkene groups of the block copolymer. The PEO-b-PPE-g-PTX G2 formed well-defined nanoparticles in aqueous solution, by direct dissolution into water, with a number-averaged hydrodynamic diameter of 114 ± 31 nm. The conjugate had PTX loading capacity as high as 53 wt%, and a maximum PTX concentration of 0.68 mg/mL in water (vs. 1.7 μg/mL for free PTX). Although the PTX concentration is ca. 10× less than for our first generation material, its accelerated release allowed for similar free PTX concentrations vs. time. The PEO-b-PPE-g-PTX G2 exhibited accelerated drug release under acidic conditions (~50 wt% PTX released in 8 d) compared to neutral conditions (~20 wt% PTX released in 8 d) and compared to the first generation analog that contained ester linkages between PTX and the polymer backbone (<5 wt% PTX released in 4 d), due to their acid-sensitive hydrolytically-labile β-thiopropionate linkages between PTX molecules and the polymer backbone. The positive cell-killing activity of PEO-b-PPE-g-PTX G2 against two cancer cell

  2. Cytokinin-Induced Ethylene Biosynthesis in Nonsenescing Cotton Leaves

    PubMed Central

    Suttle, Jeffrey C.

    1986-01-01

    The influence of cytokinins on ethylene production was examined using cotton leaf tissues. Treatment of intact cotton (Gossypium hirsutum L. cv LG 102) seedlings with both natural and synthetic cytokinins resulted in an increase in ethylene production by excised leaves. The effectiveness of the cytokinins tested was as follows: thidiazuron ≫ BA ≫ isopentyladenine ≥ zeatin ≫ kinetin. Using 100 micromolar thidiazuron (TDZ), an initial increase in ethylene production was observed 7 to 8 hours post-treatment, reached a maximum by 24 hours and then declined. Inhibitors of 1-aminocyclopropane-1-carboxylic acid (ACC) synthesis and its oxidation to ethylene reduced ethylene production 24 hours post-treatment; however, by 48 hours only inhibitors of ACC oxidation were effective. The increase in ethylene production was accompanied by a massive accumulation of ACC and its acid-labile conjugate. TDZ treatment resulted in a significant increase in the capacity of tissues to oxidize ACC to ethylene. Endogenous levels of methionine remained constant following TDZ treatment. It was concluded that the stimulation of ethylene production in cotton leaves following cytokinin treatment was the result of an increase in both the formation and oxidation of ACC. Images Fig. 4 PMID:16665168

  3. AUTOMOTIVE EMISSIONS OF ETHYLENE DIBROMIDE

    EPA Science Inventory

    Ethylene dibromide, a suspected carcinogen, and ethylene dichloride are commonly used in leaded gasoline as scavengers. Ethylene dibromide emission rates were determined from seven automobiles which had a wide range of control devices, ranging from totally uncontrolled to evapora...

  4. Ethylene insensitive plants

    DOEpatents

    Ecker, Joseph R.; Nehring, Ramlah; McGrath, Robert B.

    2007-05-22

    Nucleic acid and polypeptide sequences are described which relate to an EIN6 gene, a gene involved in the plant ethylene response. Plant transformation vectors and transgenic plants are described which display an altered ethylene-dependent phenotype due to altered expression of EIN6 in transformed plants.

  5. Interaction of Light and Ethylene on Stem Gravitropism

    NASA Technical Reports Server (NTRS)

    Harrison, Marcia A.

    1996-01-01

    The major objective of this study was to evaluate light-regulated ethylene production during gravitropic bending in etiolated pea stems. Previous investigations indicated that ethylene production increases after gravistimulation and is associated with the later (counter-reactive) phase of bending. Additionally, changes in the counter-reaction and locus of curvature during gravitropism are greatly influenced by red light and ethylene production. Ethylene production may be regulated by the levels of available precursor (1-aminocyclopropane-l-carboxylic acid, ACC) via its synthesis, conjugation to malonyl-ACC or glutamyl-ACC, or oxidation to ethylene. The regulation of ethylene production by quantifying ACC and conjugated ACC levels in gravistimulated pea stemswas examined. Also measured was the changes in protein and enzyme activity associated with gravitropic curvature by electrophoretic and spectrophotometric techniques. An image analysis system was used to visualize and quantify enzymatic activity and transcriptional products in gravistimulated and red-light treated etiolated pea stem tissues.

  6. ACR process for ethylene

    SciTech Connect

    Baldwin, R.L.; Kamm, G.R.

    1983-01-01

    Describes how the advanced cracking reactor process, which is ready for a logical commercial application, offers total liquids feedstock flexibility from light naphthenes through vacuum gas oils in the same production unit. Several processes are presently being developed which are aimed at maintaining olefin selectivity when cracking the heaviest feeds. Addresses the problems posed by such heavy feedstocks. The following trends favor the ACR process in the 1980s: natural gas price decontrol; limited natural gas reserves; few new domestic LPG-based ethylene plants will be built; an economic recovery will create the need for more ethylene capacity; modest increases in ''real'' crude oil prices; plentiful supplies of vacuum gas oil at prices making it an attractive ethylene feedstock; and increasing supplies of light naphtha at prices making it an attractive ethylene feedstock as well. Predicts that these factors will swing the preferred feedstocks for ethylene manufacture back to crude oil distillates before the end of the decade. Argues that in this environment, the ACR process can deliver the lowest cost ethylene in the industry. ACR has full-range feedstock flexibility, high selectivity to ethylene, and less sensitivity to feedstock costs and co-product credits.

  7. Ethylene glycol poisoning

    MedlinePlus

    ... attempt or as a substitute for drinking alcohol (ethanol). This article is for information only. Do NOT ... attempt or as a substitute for drinking alcohol (ethanol). Ethylene glycol is found in many household products, ...

  8. Ethylene by Naphta Cracking

    ERIC Educational Resources Information Center

    Wiseman, Peter

    1977-01-01

    Presents a discussion of the manufacture of ethylene by thermal cracking of hydrocarbon feedstocks that is useful for introducing the subject of industrial chemistry into a chemistry curriculum. (MLH)

  9. Ethylene-Vapor Optrodes

    NASA Technical Reports Server (NTRS)

    Tabacco, Mary Beth; Zhou, Quan

    1993-01-01

    Porous optical fibers include sensing regions filled with reagents. Optical-fiber chemical sensors (optrodes) developed to measure concentrations of ethylene in air in enclosed artificial plant-growth environments. Such measurements needed because ethylene acts as plant-growth hormone affecting growth at concentrations less than or equal to 20 parts per billion. Optrodes small, but exhibit sensitivities comparable to those of larger instruments. Operated safely in potentially explosive atmospheres and neither cause, nor susceptible to, electrical interference at suboptical frequencies.

  10. Separation of parent homopolymers from polystyrene and poly(ethylene oxide) based block copolymers by liquid chromatography under limiting conditions of desorption-3. Study of barrier efficiency according to block copolymers' chemical composition.

    PubMed

    Rollet, Marion; Pelletier, Bérengère; Berek, Dušan; Maria, Sébastien; Phan, Trang N T; Gigmes, Didier

    2016-09-01

    Liquid Chromatography under Limiting Conditions of Desorption (LC LCD) is a powerful separation tool for multicomponent polymer systems. This technique is based on a barrier effect of an appropriate solvent, which is injected in front of the sample, and which decelerates the elution of selected macromolecules. In this study, the barrier effects have been evaluated for triblock copolymers polystyrene-b-poly(ethylene oxide)-b-polystyrene (PS-b-PEO-b-PS) according to the content of polystyrene (wt% PS) and PEO-block molar mass. PS-b-PEO-b-PS samples were prepared by Atom Transfer Radical Polymerization (ATRP). The presence of respective parent homopolymers was investigated by applying optimized LC LCD conditions. It was found that the barrier composition largely affects the efficiency of separation and it ought to be adjusted for particular composition range of block copolymers. PMID:27495367

  11. Novel membrane technology for green ethylene production.

    SciTech Connect

    Balachandran, U.; Lee, T. H.; Dorris, S. E.; Udovich, C. A.; Scouten, C. G.; Marshall, C. L.

    2008-01-01

    reactions and prolong membrane life. With the Argonne approach, oxygen does not contact the ethane/ethylene stream, so oxidation products are not formed. Consequently, higher selectivity to ethylene and fewer by-products can be achieved. Some benefits are: (1) Simplifies overall product purification and processing schemes; (2) Results in greater energy efficiency; (3) Completely eliminates greenhouse gases from the reactor section; and (4) Lowers the cost of the 'back end' purification train, which accounts for about 70% of the capital cost of a conventional ethylene production unit.

  12. Portable Apparatus for Electrochemical Sensing of Ethylene

    NASA Technical Reports Server (NTRS)

    Manoukian, Mourad; Tempelman, Linda A.; Forchione, John; Krebs, W. Michael; Schmitt, Edwin W.

    2007-01-01

    A small, lightweight, portable apparatus based on an electrochemical sensing principle has been developed for monitoring low concentrations of ethylene in air. Ethylene has long been known to be produced by plants and to stimulate the growth and other aspects of the development of plants (including, notably, ripening of fruits and vegetables), even at concentrations as low as tens of parts per billion (ppb). The effects are magnified in plant-growth and -storage chambers wherein ethylene can accumulate. There is increasing recognition in agriculture and related industries that it is desirable to monitor and control ethylene concentrations in order to optimize the growth, storage, and ripening of plant products. Hence, there are numerous potential uses for the present apparatus in conjunction with equipment for controlling ethylene concentrations. The ethylene sensor is of a thick-film type with a design optimized for a low detection limit. The sensor includes a noble metal sensing electrode on a chip and a hydrated solid-electrolyte membrane that is held in contact with the chip. Also located on the sensor chip are a counter electrode and a reference electrode. The sensing electrode is held at a fixed potential versus the reference electrode. Detection takes place at active-triple-point areas where the sensing electrode, electrolyte, and sample gas meet. These areas are formed by cutting openings in the electrolyte membrane. The electrode current generated from electrochemical oxidation of ethylene at the active triple points is proportional to the concentration of ethylene. An additional film of the solid-electrolyte membrane material is deposited on the sensing electrode to increase the effective triple-point areas and thereby enhance the detection signal. The sensor chip is placed in a holder that is part of a polycarbonate housing. When fully assembled, the housing holds the solid-electrolyte membrane in contact with the chip (see figure). The housing includes

  13. 40 CFR 721.3800 - Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. 721.3800 Section 721.3800... Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. (a... generically as formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol,...

  14. 40 CFR 721.3800 - Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. 721.3800 Section 721.3800... Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. (a... generically as formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol,...

  15. 40 CFR 721.3800 - Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. 721.3800 Section 721.3800... Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. (a... generically as formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol,...

  16. 40 CFR 721.3800 - Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. 721.3800 Section 721.3800... Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. (a... generically as formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol,...

  17. 40 CFR 721.3800 - Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. 721.3800 Section 721.3800... Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. (a... generically as formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol,...

  18. Anomalously increased effective thermal conductivities of ethylene glycol-based nanofluids containing copper nanoparticles

    SciTech Connect

    Eastman, J. A.; Choi, S. U. S.; Li, S.; Yu, W.; Thompson, L. J.

    2001-02-05

    It is shown that a ''nanofluid'' consisting of copper nanometer-sized particles dispersed in ethylene glycol has a much higher effective thermal conductivity than either pure ethylene glycol or ethylene glycol containing the same volume fraction of dispersed oxide nanoparticles. The effective thermal conductivity of ethylene glycol is shown to be increased by up to 40% for a nanofluid consisting of ethylene glycol containing approximately 0.3 vol% Cu nanoparticles of mean diameter <10 nm. The results are anomalous based on previous theoretical calculations that had predicted a strong effect of particle shape on effective nanofluid thermal conductivity, but no effect of either particle size or particle thermal conductivity.

  19. Recovery and purification of ethylene

    DOEpatents

    Reyneke, Rian; Foral, Michael J.; Lee, Guang-Chung; Eng, Wayne W. Y.; Sinclair, Iain; Lodgson, Jeffery S.

    2008-10-21

    A process for the recovery and purification of ethylene and optionally propylene from a stream containing lighter and heavier components that employs an ethylene distributor column and a partially thermally coupled distributed distillation system.

  20. Boronyl as a terminal ligand in boron oxide clusters: hexagonal ring C(2v) B6O4 and ethylene-like D(2h) B6O4(-/2-).

    PubMed

    Wang, Wei; Chen, Qiang; Wang, Ying-Jin; Bai, Hui; Gao, Ting-Ting; Li, Hai-Ru; Zhai, Hua-Jin; Li, Si-Dian

    2015-08-14

    Considerable recent research effort has been devoted to the development of boronyl (BO) chemistry. Here we predict three perfectly planar boron boronyl clusters: C2v B6O4 (1, (1)A1), D2h B6O4(−) (2, (2)B3u), and D2h B6O4(2−) (3, (1)Ag). These are established as the global-minimum structures on the basis of the coalescence kick and basin hopping structural searches and electronic structure calculations at the B3LYP/aug-cc-pVTZ level, with complementary CCSD/6-311+G* and single-point CCSD(T)/6-311+G*//B3LYP/aug-cc-pVTZ calculations for 2. The C2v B6O4 neutral cluster features a hexagonal B4O2 ring with two terminal BO groups. The D2h B6O4(−/2−) clusters have ethylene-like structures and are readily formulated as B2(BO)4(−/2−), in which a B2 core with double bond character is bonded to four terminal BO groups. Chemical bonding analyses show that B6O4 (1) possesses an aromatic π bonding system with three delocalized, six-centered π bonds over the hexagonal ring, rendering it an inorganic analogue of benzene, whereas the B6O4(−/2−) (2 and 3) species closely resemble ethylene in terms of structures and bonding. This work provides new examples for the analogy between boron oxides and hydrocarbons. PMID:26166194

  1. Ethylene and Fruit Ripening

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Experiments designed to down-regulate specific tomato ethylene receptor isoforms using antisense suppression have been reported for LeETR1, NR and LeETR4. Down-regulation of LeETR1 expression in transgenic plants did not alter fruit ripening but resulted in plants with shorter internodes and reduce...

  2. Ethylene thiourea (ETU)

    Integrated Risk Information System (IRIS)

    Ethylene thiourea ( ETU ) ; CASRN 96 - 45 - 7 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarci

  3. ETHYLENE AND POSTHARVEST COMMODITIES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper is a review of the plant hormone ethylene, a simple two carbon molecule. This hormone is biologically active at low concentrations (part per billion to part per million range). Since it is a gas, it is easily transported long distances via diffusion from site of synthesis within the pla...

  4. Excimer-laser-induced oxidation of diborane: Formation and isolation of HBO, HB 18O AND H 3B 3O 3 in argon matrices

    NASA Astrophysics Data System (ADS)

    Ault, Bruce S.

    1989-05-01

    An excimer laser operating at 193 nm has been employed in conjunction with the matrix isolation technique to study the reaction of B 2H 6 with oxygen atoms. N 2O and O 2 were used as photolytic oxygen atom sources, and a number of oxidation products were detected. Absorptions near 750 and 1813 cm -1 were assigned to H 11BO; experiments with 18O led to production of HB 18O for the first time, and the identification of two of the fundamentals of this species. Also, H 3B 3O 3 was detected near 910, 1380 and 2610 cm -1. In addition, the most intense fundamental of BH 3 was tentatively identified at 1138 cm -1. These observations support the most recently postulated mechanism for the oxidation of diborane, and the suggested intermediacy of HBO in the process.

  5. Singular Mueller matrices

    NASA Astrophysics Data System (ADS)

    Gil, José J.; Ossikovski, Razvigor; José, Ignacio San

    2016-04-01

    Singular Mueller matrices play an important role in polarization algebra and have peculiar properties that stem from the fact that either the medium exhibits maximum diattenuation and/or polarizance, or because its associated canonical depolarizer has the property of fully randomizing, the circular component (at least) of the states of polarization of light incident on it. The formal reasons for which the Mueller matrix M of a given medium is singular are systematically investigated, analyzed and interpreted in the framework of the serial decompositions and the characteristic ellipsoids of M. The analysis allows for a general classification and geometric representation of singular Mueller matrices, of potential usefulness to experimentalists dealing with such media.

  6. Singular Mueller matrices.

    PubMed

    Gil, José J; Ossikovski, Razvigor; José, Ignacio San

    2016-04-01

    Singular Mueller matrices play an important role in polarization algebra and have peculiar properties that stem from the fact that either the medium exhibits maximum diattenuation and/or polarizance or because its associated canonical depolarizer has the property of fully randomizing the circular component (at least) of the states of polarization of light incident on it. The formal reasons for which the Mueller matrix M of a given medium is singular are systematically investigated, analyzed, and interpreted in the framework of the serial decompositions and the characteristic ellipsoids of M. The analysis allows for a general classification and geometric representation of singular Mueller matrices, which are of potential usefulness to experimentalists dealing with such media. PMID:27140769

  7. The level of ethylene biomarker in the renal failure of elderly patients analyzed by photoacoustic spectroscopy

    NASA Astrophysics Data System (ADS)

    Popa, C.; Patachia, M.; Banita, S.; Matei, C.; Bratu, A. M.; Dumitras, D. C.

    2013-12-01

    In recent years there has been a large increase in the areas related to developments in the prevention of diseases, especially in explaining the role of oxidative stress. Lipid peroxidation and oxidative stress contributes to morbidity in hemodialysis (HD) patients. It is therefore relevant to analyze the impact of oxidative stress and its related species (ethylene) immediately after dialysis treatment in order to prevent trauma in the renal failure of elderly patients. In this paper we describe recent progress in laser photoacoustic spectroscopy detection of ethylene in renal failure patients. We have found that HD treatment increases ethylene concentration in the exhaled breath of elderly patients and may intensify oxidative stress.

  8. Electrocatalytic oxidation of ethanol in acid medium: Enhancement of activity of vulcan-supported Platinum-based nanoparticles upon immobilization within nanostructured zirconia matrices

    NASA Astrophysics Data System (ADS)

    Rutkowska, Iwona A.; Kulesza, Pawel J.

    2014-09-01

    Composite electrocatalytic materials that utilize carbon (Vulcan) supported Pt or PtRu nanoparticles dispersed within thin films of zirconia (ZrO2) are considered here for oxidation of such a biofuel as ethanol in acid medium. The systems were characterized using electrochemical techniques as well as transmission electron microscopy. The enhancement of activity was clearly evident upon comparison of the respective voltammetric and chronoamperometric current densities recorded (at room temperature in 0.5 mol dm-3H2SO4 containing 0.5 mol dm-3 ethanol) using the Vulcan supported Pt and PtRu catalysts in the presence and absence of zirconia. In all cases, the noble metal loading was the same, 100 μg cm-2. Apparently, the existence of large population of hydroxyl groups (originating from zirconia) in the vicinity of Pt-based catalyst, in addition to possible specific interactions between zirconia and the ruthenium component of PtRu, facilitated the oxidative removal (from Pt) of the passivating (e.g., CO) reaction intermediates (adsorbates). By utilizing carbon supported, rather than bare or unsupported, Pt or PtRu nanoparticles (dispersed within the semiconducting zirconia), the overall charge distribution at the electrocatalytic interface was improved.

  9. [Chronic ethylene glycol poisoning].

    PubMed

    Kaiser, W; Steinmauer, H G; Biesenbach, G; Janko, O; Zazgornik, J

    1993-04-30

    Over a six-week period a 60-year-old patient had several unexplained intoxication-like episodes. He finally had severe abdominal cramps with changes in the level of consciousness and oligoanuric renal failure (creatinine 4.7 mg/dl). The history, marked metabolic acidosis (pH 7.15, HCO3- 2.2 mmol/l, pCO2 6.6 mmHg) as well as raised anion residue (43 mmol/l) and the presence of oxalates in urine suggested poisoning by ethylene glycol contained in antifreeze liquid. Intensive haemodialysis adequately eliminated ethylene glycol and its toxic metabolites (glycol aldehyde, glycolic acid). Renal function returned within 10 days, although the concentrating power of the kidney remained impaired for several weeks because of interstitial nephritis. The intoxication had been caused by a defective heating-pipe system from which the antifreeze had leaked into the hot-water boiler (the patient had habitually prepared hot drinks by using water from the hot-water tap). Gas chromatography demonstrated an ethylene glycol concentration of 21 g per litre of water. PMID:8482240

  10. Degradation of ethylene glycol using Fenton's reagent and UV.

    PubMed

    McGinnis, B D; Adams, V D; Middlebrooks, E J

    2001-10-01

    Oxidation of ethylene glycol in aqueous solutions was found to occur with the addition of Fenton's reagent with further conversion observed upon UV irradiation. The pH range studied was 2.5-9.0 with initial H2O2 concentrations ranging from 100 to 1000 mg/l. Application of this method to airport storm-water could potentially result in reduction of chemical oxygen demand by conversion of ethylene glycol to oxalic and formic acids. Although the amount of H2O2 added follows the amount of ethylene glycol degraded, smaller H2O2 doses were associated with increases in the ratio of ethylene glycol removed per unit H2O2 added indicating the potential of pulsed doses or constant H2O2 feed systems. Ethylene glycol removal was enhanced by exposure to UV light after treatment with Fenton's reagent, with rates dependent on initial H2O2 concentration. In addition to ethylene glycol, the principle products of this reaction, oxalic and formic acids, have been shown to be mineralized in other HO generating systems presenting the potential for ethylene glycol mineralization in this system with increased HO* production. PMID:11572583

  11. Intermittency and random matrices

    NASA Astrophysics Data System (ADS)

    Sokoloff, Dmitry; Illarionov, E. A.

    2015-08-01

    A spectacular phenomenon of intermittency, i.e. a progressive growth of higher statistical moments of a physical field excited by an instability in a random medium, attracted the attention of Zeldovich in the last years of his life. At that time, the mathematical aspects underlying the physical description of this phenomenon were still under development and relations between various findings in the field remained obscure. Contemporary results from the theory of the product of independent random matrices (the Furstenberg theory) allowed the elaboration of the phenomenon of intermittency in a systematic way. We consider applications of the Furstenberg theory to some problems in cosmology and dynamo theory.

  12. Formation of TiO2 nanotube arrays by anodic oxidation in LiOH added ethylene glycol electrolyte and the effect of thermal annealing on the photoelectrochemical properties

    NASA Astrophysics Data System (ADS)

    Taib, Mustaffa Ali Azhar; Tan, Wai Kian; Okuno, Teruhisa; Kawamura, Go; Jaafar, Mariatti; Razak, Khairunisak Abdul; Matsuda, Atsunori; Lockman, Zainovia

    2016-07-01

    The present study employs LiOH as an additive in fluoride ethylene glycol (EG) electrolyte (LiOH/EG) for anodic oxidation of Ti in fabricating anodic TiO2 nanotubes (TNTs). TNTs formed in LiOH/EG electrolyte were found to be longer (6.23 ± 0.2 µm) compared to when only water was used in EG electrolyte: 4.54 ± 0.2 µm for the same anodisation time of 30 min and voltage of 60 V. The as-anodised TNTs were however amorphous. Hence, the samples were annealed at high temperatures for crystallization preferably as anatase oxide. Anatase phase is needed as the anodised Ti is used as a photoanode in a photoelectrochemical (PEC) cell. The effect of annealing temperatures on the TNTs to the photocurrent measurement was investigated in a standard KOH PEC cell under visible light illumination. Anodised Ti annealed at 200 °C has the lowest photocurrent of 0.002 mA cm-2. Sample annealed at 400 °C has the highest photocurrent of 0.955 mA cm-2 (0.5 V) since it is comprised of mostly anatase with crystallite size of 31.80 nm, whereas sample annealed at 600 °C seems to be a mixture of anatase and rutile, displays lower photocurrent of 0.823 mA cm-2. It was also observed that the as-anodised sample has slightly higher photocurrent than the 200 °C annealed sample perhaps due to the adsorbed OH species from the electrolyte acting as holes trapping sites.

  13. Links Between Ethylene and Sulfur Nutrition—A Regulatory Interplay or Just Metabolite Association?

    PubMed Central

    Wawrzynska, Anna; Moniuszko, Grzegorz; Sirko, Agnieszka

    2015-01-01

    Multiple reports demonstrate associations between ethylene and sulfur metabolisms, however the details of these links have not yet been fully characterized; the links might be at the metabolic and the regulatory levels. First, sulfur-containing metabolite, methionine, is a precursor of ethylene and is a rate limiting metabolite for ethylene synthesis; the methionine cycle contributes to both sulfur and ethylene metabolism. On the other hand, ethylene is involved in the complex response networks to various stresses and it is known that S deficiency leads to photosynthesis and C metabolism disturbances that might be responsible for oxidative stress. In several plant species, ethylene increases during sulfur starvation and might serve signaling purposes to initiate the process of metabolism reprogramming during adjustment to sulfur deficit. An elevated level of ethylene might result from increased activity of enzymes involved in its synthesis. It has been demonstrated that the alleviation of cadmium stress in plants by application of S seems to be mediated by ethylene formation. On the other hand, the ethylene-insensitive Nicotiana attenuata plants are impaired in sulfur uptake, reduction and metabolism, and they invest their already limited S into methionine needed for synthesis of ethylene constitutively emitted in large amounts to the atmosphere. Regulatory links of EIN3 and SLIM1 (both from the same family of transcriptional factors) involved in the regulation of ethylene and sulfur pathway, respectively, is also quite probable as well as the reciprocal modulation of both pathways on the enzyme activity levels. PMID:26648954

  14. Links Between Ethylene and Sulfur Nutrition-A Regulatory Interplay or Just Metabolite Association?

    PubMed

    Wawrzynska, Anna; Moniuszko, Grzegorz; Sirko, Agnieszka

    2015-01-01

    Multiple reports demonstrate associations between ethylene and sulfur metabolisms, however the details of these links have not yet been fully characterized; the links might be at the metabolic and the regulatory levels. First, sulfur-containing metabolite, methionine, is a precursor of ethylene and is a rate limiting metabolite for ethylene synthesis; the methionine cycle contributes to both sulfur and ethylene metabolism. On the other hand, ethylene is involved in the complex response networks to various stresses and it is known that S deficiency leads to photosynthesis and C metabolism disturbances that might be responsible for oxidative stress. In several plant species, ethylene increases during sulfur starvation and might serve signaling purposes to initiate the process of metabolism reprogramming during adjustment to sulfur deficit. An elevated level of ethylene might result from increased activity of enzymes involved in its synthesis. It has been demonstrated that the alleviation of cadmium stress in plants by application of S seems to be mediated by ethylene formation. On the other hand, the ethylene-insensitive Nicotiana attenuata plants are impaired in sulfur uptake, reduction and metabolism, and they invest their already limited S into methionine needed for synthesis of ethylene constitutively emitted in large amounts to the atmosphere. Regulatory links of EIN3 and SLIM1 (both from the same family of transcriptional factors) involved in the regulation of ethylene and sulfur pathway, respectively, is also quite probable as well as the reciprocal modulation of both pathways on the enzyme activity levels. PMID:26648954

  15. Modelling the behaviour of oxide fuels containing minor actinides with urania, thoria and zirconia matrices in an accelerator-driven system

    NASA Astrophysics Data System (ADS)

    Sobolev, V.; Lemehov, S.; Messaoudi, N.; Van Uffelen, P.; Aı̈t Abderrahim, H.

    2003-06-01

    The Belgian Nuclear Research Centre, SCK • CEN, is currently working on the pre-design of the multipurpose accelerator-driven system (ADS) MYRRHA. A demonstration of the possibility of transmutation of minor actinides and long-lived fission products with a realistic design of experimental fuel targets and prognosis of their behaviour under typical ADS conditions is an important task in the MYRRHA project. In the present article, the irradiation behaviour of three different oxide fuel mixtures, containing americium and plutonium - (Am,Pu,U)O 2- x with urania matrix, (Am,Pu,Th)O 2- x with thoria matrix and (Am,Y,Pu,Zr)O 2- x with inert zirconia matrix stabilised by yttria - were simulated with the new fuel performance code MACROS, which is under development and testing at the SCK • CEN. All the fuel rods were considered to be of the same design and sizes: annular fuel pellets, helium bounded with the stainless steel cladding, and a large gas plenum. The liquid lead-bismuth eutectic was used as coolant. Typical irradiation conditions of the hottest fuel assembly of the MYRRHA subcritical core were pre-calculated with the MCNPX code and used in the following calculations as the input data. The results of prediction of the thermo-mechanical behaviour of the designed rods with the considered fuels during three irradiation cycles of 90 EFPD are presented and discussed.

  16. Glucose-sensitive polymeric matrices for controlled drug delivery.

    PubMed

    Goldraich, M; Kost, J

    1993-01-01

    Hydrogel matrices were prepared by chemical polymerization of solutions containing 2-hydroxyethyl methacrylate, N,N-dimethyl-aminoethyl methacrylate, tetraethylene glycol dimethacrylate, ethylene glycol and water solutions containing glucose oxidase, bacitracin or insulin. The hydrogels displayed faster and higher swelling and release rates at lower pH or at higher glucose concentrations. Swelling and release kinetics were also responsive to step changes in glucose concentration in the physiological range. The kinetics of the soluble and immobilized enzyme followed Michaelis Menten's kinetics. In the soluble state the enzyme was more active than the immobilized one due to mass transfer limitations, which may be overcome by preparation of microbead configuration. PMID:10146247

  17. Ethylene in mutualistic symbioses

    PubMed Central

    Khatabi, Behnam; Schäfer, Patrick

    2012-01-01

    Ethylene (ET) is a gaseous phytohormone that participates in various plant physiological processes and essentially contributes to plant immunity. ET conducts its functions by regulating the expression of ET-responsive genes or in crosstalk with other hormones. Several recent studies have shown the significance of ET in the establishment and development of plant-microbe interactions. Therefore, it is not surprising that pathogens and mutualistic symbionts target ET synthesis or signaling to colonize plants. This review introduces the significance of ET metabolism in plant-microbe interactions, with an emphasis on its role in mutualistic symbioses. PMID:23072986

  18. Inhibition of the Conversion of 1-Aminocyclopropane-1-carboxylic Acid to Ethylene by Structural Analogs, Inhibitors of Electron Transfer, Uncouplers of Oxidative Phosphorylation, and Free Radical Scavengers 1

    PubMed Central

    Apelbaum, Akiva; Wang, Shiow Y.; Burgoon, Alan C.; Baker, James E.; Lieberman, Morris

    1981-01-01

    Cyclopropane carboxylic acid (CCA) at 1 to 5 millimolar, unlike related cyclopropane ring analogs of 1-aminocyclopropane-1-carboxylic acid (ACC) which were virtually ineffective, inhibited C2H4 production, and this inhibition was nullified by ACC. Inhibition by CCA is not competitive with ACC since there is a decline, rather than an increase, in native endogenous ACC in the presence of CCA. Similarly, short-chain organic acids from acetic to butyric acid and α-aminoisobutyric acid inhibited C2H4 production at 1 to 5 millimolar and lowered endogenous ACC levels. These inhibitions, like that of CCA, were overcome with ACC. Inhibitors of electron transfer and oxidative phosphorylation effectively inhibited ACC conversion to C2H4 in pea and apple tissues. The most potent inhibitors were 2,4-dinitrophenol (DNP) and carbonyl cyanide m-chlorophenylhydrazone (CCCP) which virtually eliminated ACC-stimulated C2H4 production in both tissues. Still other inhibitors of the conversion of ACC to C2H4 were putative free radical scavengers which reduced chemiluminescence in the free radical-activated luminol reaction. These inhibitor studies suggest the involvement of a free radical in the reaction sequence which converts ACC to C2H4. Additionally, the potent inhibition of this reaction by uncouplers of oxidative phosphorylation (DNP and CCCP) suggest the involvement of ATP or the necessity for an intact membrane for C2H4 production from ACC. In the latter case, CCCP may be acting as a proton ionophore to destroy the membrane integrity necessary for C2H4 production. PMID:16661637

  19. On the origin of reactivity of steam reforming of ethylene glycol on supported Ni catalysts.

    PubMed

    Li, Shuirong; Zhang, Chengxi; Zhang, Peng; Wu, Gaowei; Ma, Xinbin; Gong, Jinlong

    2012-03-28

    This paper describes a strategy for producing hydrogen via steam reforming of ethylene glycol over supported nickel catalysts. Nickel plays a crucial role in conversion of ethylene glycol and production of hydrogen, while oxide supports affect product distribution of carbonaceous species. A plausible reaction pathway is proposed based on our results and the literature. PMID:22246195

  20. Interstellar Antifreeze: Ethylene Glycol

    NASA Astrophysics Data System (ADS)

    Hollis, J. M.; Lovas, F. J.; Jewell, P. R.; Coudert, L. H.

    2002-05-01

    Interstellar ethylene glycol (HOCH2CH2OH) has been detected in emission toward the Galactic center source Sagittarius B2(N-LMH) by means of several millimeter-wave rotational torsional transitions of its lowest energy conformer. The types and kinds of molecules found to date in interstellar clouds suggest a chemistry that favors aldehydes and their corresponding reduced alcohols-e.g., formaldehyde (H2CO)/methanol (CH3OH), acetaldehyde (CH3CHO)/ethanol (CH3CH2OH). Similarly, ethylene glycol is the reduced alcohol of glycolaldehyde (CH2OHCHO), which has also been detected toward Sgr B2(N-LMH). While there is no consensus as to how any such large complex molecules are formed in the interstellar clouds, atomic hydrogen (H) and carbon monoxide (CO) could form formaldehyde on grain surfaces, but such surface chemistry beyond that point is uncertain. However, laboratory experiments have shown that the gas-phase reaction of atomic hydrogen (H) and solid-phase CO at 10-20 K can produce formaldehyde and methanol and that alcohols and other complex molecules can be synthesized from cometary ice analogs when subject to ionizing radiation at 15 K. Thus, the presence of aldehyde/reduced alcohol pairs in interstellar clouds implies that such molecules are a product of a low-temperature chemistry on grain surfaces or in grain ice mantles. This work suggests that aldehydes and their corresponding reduced alcohols provide unique observational constraints on the formation of complex interstellar molecules.

  1. Interstellar Antifreeze: Ethylene Glycol

    NASA Technical Reports Server (NTRS)

    Hollis, J. M.; Lovas, F. J.; Jewell, P. R.; Coudert, L. H.

    2002-01-01

    Interstellar ethylene glycol (HOCH2CH2,OH) has been detected in emission toward the Galactic center source Sagittarius B2(N-LMH) by means of several millimeter-wave rotational torsional transitions of its lowest energy conformer. The types and kinds of molecules found to date in interstellar clouds suggest a chemistry that favors aldehydes and their corresponding reduced alcohols-e.g., formaldehyde (H2CO)/methanol (CH3OH), acetaldehyde (CH3CHO)/ethanol (CH3CH2OH). Similarly, ethylene glycol is the reduced alcohol of glycolaldehyde (CH2OHCHO), which has also been detected toward Sgr B2(N-LMH). While there is no consensus as to how any such large complex molecules are formed in the interstellar clouds, atomic hydrogen (H) and carbon monoxide (CO) could form formaldehyde on grain surfaces, but such surface chemistry beyond that point is uncertain. However, laboratory experiments have shown that the gas-phase reaction of atomic hydrogen (H) and solid-phase CO at 10-20 K can produce formaldehyde and methanol and that alcohols and other complex molecules can be synthesized from cometary ice analogs when subject to ionizing radiation at 15 K. Thus, the presence of aldehyde/ reduced alcohol pairs in interstellar clouds implies that such molecules are a product of a low-temperature chemistry on grain surfaces or in grain ice mantles. This work suggests that aldehydes and their corresponding reduced alcohols provide unique observational constraints on the formation of complex interstellar molecules.

  2. Enhancing Understanding of Transformation Matrices

    ERIC Educational Resources Information Center

    Dick, Jonathan; Childrey, Maria

    2012-01-01

    With the Common Core State Standards' emphasis on transformations, teachers need a variety of approaches to increase student understanding. Teaching matrix transformations by focusing on row vectors gives students tools to create matrices to perform transformations. This empowerment opens many doors: Students are able to create the matrices for…

  3. Online Aerosol Mass Spectrometry of Single Micrometer-Sized Particles Containing Poly(ethylene glycol)

    SciTech Connect

    Bogan, M J; Patton, E; Srivastava, A; Martin, S; Fergenson, D; Steele, P; Tobias, H; Gard, E; Frank, M

    2006-10-25

    Analysis of poly(ethylene glycol)(PEG)-containing particles by online single particle aerosol mass spectrometers equipped with laser desorption ionization (LDI) is reported. We demonstrate that PEG-containing particles are useful in the development of aerosol mass spectrometers because of their ease of preparation, low cost, and inherently recognizable mass spectra. Solutions containing millimolar quantities of PEGs were nebulized and, after drying, the resultant micrometer-sized PEG containing particles were sampled. LDI (266 nm) of particles containing NaCl and PEG molecules of average molecular weight <500 generated mass spectra reminiscent of mass spectra of PEG collected by other MS schemes including the characteristic distribution of positive ions (Na{sup +} adducts) separated by the 44 Da of the ethylene oxide units separating each degree of polymerization. PEGs of average molecular weight >500 were detected from particles that also contained t the tripeptide tyrosine-tyrosine-tyrosine or 2,5-dihydroxybenzoic acid, which were added to nebulized solutions to act as matrices to assist LDI using pulsed 266 nm and 355 nm lasers, respectively. Experiments were performed on two aerosol mass spectrometers, one reflectron and one linear, that each utilize two time-of-flight mass analyzers to detect positive and negative ions created from a single particle. PEG-containing particles are currently being employed in the optimization of our bioaerosol mass spectrometers for the application of measurements of complex biological samples, including human effluents, and we recommend that the same strategies will be of great utility to the development of any online aerosol LDI mass spectrometer platform.

  4. Prediction of the solubility of cucurbitacin drugs in self-associating poly(ethylene oxide)-b-poly(alpha-benzyl carboxylate epsilon-caprolactone) block copolymer with different tacticities using molecular dynamics simulation.

    PubMed

    Patel, Sarthak K; Lavasanifar, Afsaneh; Choi, Phillip

    2010-01-01

    Molecular dynamics (MD) simulation was used to investigate the solubility of two hydrophobic drugs Cucurbitacin B (CuB) and Cucurbitacin I (CuI) in poly(ethylene oxide)-b-poly(alpha-benzyl carboxylate epsilon-caprolactone) (PEO-b-PBCL) block copolymers with different tacticities. In particular, di-block copolymer with three different tacticities viz. PEO-b-iPBCL, PEO-b-sPBCL, and PEO-b-aPBCL were used. The solubility was quantified by calculating the corresponding Flory-Huggins interaction parameters (chi) using random binary mixture models with 10wt% of drug. The tacticity of the di-block copolymer was found to influence significantly the solubility of two drugs in it. In particular, based on MD simulation results, only PEO-b-sPBCL exhibited solubility while the other two did not. Given the fact that the drugs were shown to be soluble in PEO-b-PBCL experimentally, it is predicted that the tacticity of the di-block copolymer synthesized in experiment is syndiotactic. This predication matches well with the dominant ring opening polymerization of cyclic lactones to syndiotactic polymers by stannous octoate as catalyst used to prepare PEO-b-PBCL block copolymers in our previous experiments. The simulation results showed that the solubility of the drugs in PEO-b-sPBCL is attributed to the favorable intra-molecular interaction of the di-block copolymer and favorable intermolecular interaction between the di-block copolymer and the drugs. Radial distribution function analysis provides useful insights into the nature and type of the intermolecular interactions. PMID:19796808

  5. pH-dependent immobilization of proteins on surfaces functionalized by plasma-enhanced chemical vapor deposition of poly(acrylic acid)- and poly(ethylene oxide)-like films.

    PubMed

    Belegrinou, Serena; Mannelli, Ilaria; Lisboa, Patricia; Bretagnol, Frederic; Valsesia, Andrea; Ceccone, Giacomo; Colpo, Pascal; Rauscher, Hubert; Rossi, François

    2008-07-15

    The interaction of the proteins bovine serum albumin (BSA), lysozyme (Lys), lactoferrin (Lf), and fibronectin (Fn) with surfaces of protein-resistant poly(ethylene oxide) (PEO) and protein-adsorbing poly(acrylic acid) (PAA) fabricated by plasma-enhanced chemical vapor deposition has been studied with quartz crystal microbalance with dissipation monitoring (QCM-D). We focus on several parameters which are crucial for protein adsorption, i.e., the isoelectric point (pI) of the proteins, the pH of the solution, and the charge density of the sorbent surfaces, with the zeta-potential as a measure for the latter. The measurements reveal adsorption stages characterized by different segments in the plots of the dissipation vs frequency change. PEO remains protein-repellent for BSA, Lys, and Lf at pH 4-8.5, while weak adsorption of Fn was observed. On PAA, different stages of protein adsorption processes could be distinguished under most experimental conditions. BSA, Lys, Lf, and Fn generally exhibit a rapid initial adsorption phase on PAA, often followed by slower processes. The evaluation of the adsorption kinetics also reveals different adsorption stages, whereas the number of these stages does not always correspond to the structurally different phases as revealed by the D- f plots. The results presented here, together with information obtained in previous studies by other groups on the properties of these proteins and their interaction with surfaces, allow us to develop an adsorption scenario for each of these proteins, which takes into account electrostatic protein-surface and protein-protein interaction, but also the pH-dependent properties of the proteins, such as shape and exposure of specific domains. PMID:18549295

  6. Estimating sparse precision matrices

    NASA Astrophysics Data System (ADS)

    Padmanabhan, Nikhil; White, Martin; Zhou, Harrison H.; O'Connell, Ross

    2016-08-01

    We apply a method recently introduced to the statistical literature to directly estimate the precision matrix from an ensemble of samples drawn from a corresponding Gaussian distribution. Motivated by the observation that cosmological precision matrices are often approximately sparse, the method allows one to exploit this sparsity of the precision matrix to more quickly converge to an asymptotic 1/sqrt{N_sim} rate while simultaneously providing an error model for all of the terms. Such an estimate can be used as the starting point for further regularization efforts which can improve upon the 1/sqrt{N_sim} limit above, and incorporating such additional steps is straightforward within this framework. We demonstrate the technique with toy models and with an example motivated by large-scale structure two-point analysis, showing significant improvements in the rate of convergence. For the large-scale structure example, we find errors on the precision matrix which are factors of 5 smaller than for the sample precision matrix for thousands of simulations or, alternatively, convergence to the same error level with more than an order of magnitude fewer simulations.

  7. Estimating sparse precision matrices

    NASA Astrophysics Data System (ADS)

    Padmanabhan, Nikhil; White, Martin; Zhou, Harrison H.; O'Connell, Ross

    2016-05-01

    We apply a method recently introduced to the statistical literature to directly estimate the precision matrix from an ensemble of samples drawn from a corresponding Gaussian distribution. Motivated by the observation that cosmological precision matrices are often approximately sparse, the method allows one to exploit this sparsity of the precision matrix to more quickly converge to an asymptotic 1/√{N_sim} rate while simultaneously providing an error model for all of the terms. Such an estimate can be used as the starting point for further regularization efforts which can improve upon the 1/√{N_sim} limit above, and incorporating such additional steps is straightforward within this framework. We demonstrate the technique with toy models and with an example motivated by large-scale structure two-point analysis, showing significant improvements in the rate of convergence. For the large-scale structure example we find errors on the precision matrix which are factors of 5 smaller than for the sample precision matrix for thousands of simulations or, alternatively, convergence to the same error level with more than an order of magnitude fewer simulations.

  8. Estimating sparse precision matrices

    NASA Astrophysics Data System (ADS)

    Padmanabhan, Nikhil; White, Martin; Zhou, Harrison H.; O'Connell, Ross

    2016-08-01

    We apply a method recently introduced to the statistical literature to directly estimate the precision matrix from an ensemble of samples drawn from a corresponding Gaussian distribution. Motivated by the observation that cosmological precision matrices are often approximately sparse, the method allows one to exploit this sparsity of the precision matrix to more quickly converge to an asymptotic 1/√{N_sim} rate while simultaneously providing an error model for all of the terms. Such an estimate can be used as the starting point for further regularization efforts which can improve upon the 1/√{N_sim} limit above, and incorporating such additional steps is straightforward within this framework. We demonstrate the technique with toy models and with an example motivated by large-scale structure two-point analysis, showing significant improvements in the rate of convergence. For the large-scale structure example, we find errors on the precision matrix which are factors of 5 smaller than for the sample precision matrix for thousands of simulations or, alternatively, convergence to the same error level with more than an order of magnitude fewer simulations.

  9. Numerical inversion of finite Toeplitz matrices and vector Toeplitz matrices

    NASA Technical Reports Server (NTRS)

    Bareiss, E. H.

    1969-01-01

    Numerical technique increases the efficiencies of the numerical methods involving Toeplitz matrices by reducing the number of multiplications required by an N-order Toeplitz matrix from N-cubed to N-squared multiplications. Some efficient algorithms are given.

  10. What's wrong with risk matrices?

    PubMed

    Cox, Louis Anthony

    2008-04-01

    Risk matrices-tables mapping "frequency" and "severity" ratings to corresponding risk priority levels-are popular in applications as diverse as terrorism risk analysis, highway construction project management, office building risk analysis, climate change risk management, and enterprise risk management (ERM). National and international standards (e.g., Military Standard 882C and AS/NZS 4360:1999) have stimulated adoption of risk matrices by many organizations and risk consultants. However, little research rigorously validates their performance in actually improving risk management decisions. This article examines some mathematical properties of risk matrices and shows that they have the following limitations. (a) Poor Resolution. Typical risk matrices can correctly and unambiguously compare only a small fraction (e.g., less than 10%) of randomly selected pairs of hazards. They can assign identical ratings to quantitatively very different risks ("range compression"). (b) Errors. Risk matrices can mistakenly assign higher qualitative ratings to quantitatively smaller risks. For risks with negatively correlated frequencies and severities, they can be "worse than useless," leading to worse-than-random decisions. (c) Suboptimal Resource Allocation. Effective allocation of resources to risk-reducing countermeasures cannot be based on the categories provided by risk matrices. (d) Ambiguous Inputs and Outputs. Categorizations of severity cannot be made objectively for uncertain consequences. Inputs to risk matrices (e.g., frequency and severity categorizations) and resulting outputs (i.e., risk ratings) require subjective interpretation, and different users may obtain opposite ratings of the same quantitative risks. These limitations suggest that risk matrices should be used with caution, and only with careful explanations of embedded judgments. PMID:18419665

  11. Computer-Access-Code Matrices

    NASA Technical Reports Server (NTRS)

    Collins, Earl R., Jr.

    1990-01-01

    Authorized users respond to changing challenges with changing passwords. Scheme for controlling access to computers defeats eavesdroppers and "hackers". Based on password system of challenge and password or sign, challenge, and countersign correlated with random alphanumeric codes in matrices of two or more dimensions. Codes stored on floppy disk or plug-in card and changed frequently. For even higher security, matrices of four or more dimensions used, just as cubes compounded into hypercubes in concurrent processing.

  12. Participation of ethylene in gravitropism

    NASA Technical Reports Server (NTRS)

    Harrison, M.; Pickard, B. G.

    1984-01-01

    In shoots of many plants, of which tomato (Lycopersicon esculentum Mill.) is an example, ethylene production is substantially increased during gravitropism. As a first step toward elucidating the role of ethylene in gravitropism, detailed time courses of ethylene production in isolated hypocotyl segments and whole plants were measured for gravistimulated and upright tomato seedlings. In the first experiment, seedlings were set upright or laid horizontal and then, at 15 min intervals, sets of hypocotyls were excised and sealed into gas tight vials. A steady long term rise in ethylene production begins after 15 min gravistimulation. It is possible that this increase is a consequence of the accumulation of indoleacetic acid (IAA) in the lower tissue of the hypocotyle. In a second kind of experiment, whole seedlings were enclosed in sealed chambers and air samples were withdrawn at 5 min intervals. Stimulated seedlings produced more ethylene than controls during the first 5 min interval, but not appreciably more during the second. This suggests the possibility that the ethylene production induced during the first 5 min occurs immediately rather than after a lag, and thus much too soon to be controlled by redistribution of IAA.

  13. 29 CFR 1910.1047 - Ethylene oxide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., the appropriate respirators specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134; however, employers... no cost to the employee, appropriate protective clothing or other equipment in accordance with 29 CFR... elements prescribed in 29 CFR 1910.38 and 29 CFR 1910.39, “Emergency action plans” and “Fire...

  14. 46 CFR 154.1725 - Ethylene oxide.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... accessory equipment made of steel, stainless steel, except types 416 and 442, or other material specially... stainless steel containing not less than 11% chromium; (4) Have gaskets constructed of spirally wound stainless steel with teflon or other material specially approved by the Commandant (CG-522); (5) Not...

  15. 46 CFR 154.1725 - Ethylene oxide.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... accessory equipment made of steel, stainless steel, except types 416 and 442, or other material specially... stainless steel containing not less than 11% chromium; (4) Have gaskets constructed of spirally wound stainless steel with Teflon or other material specially approved by the Commandant (CG-OES); (5) Not...

  16. 46 CFR 154.1725 - Ethylene oxide.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... accessory equipment made of steel, stainless steel, except types 416 and 442, or other material specially... stainless steel containing not less than 11% chromium; (4) Have gaskets constructed of spirally wound stainless steel with teflon or other material specially approved by the Commandant (CG-OES); (5) Not...

  17. 46 CFR 154.1725 - Ethylene oxide.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... accessory equipment made of steel, stainless steel, except types 416 and 442, or other material specially... stainless steel containing not less than 11% chromium; (4) Have gaskets constructed of spirally wound stainless steel with teflon or other material specially approved by the Commandant (CG-522); (5) Not...

  18. 46 CFR 154.1725 - Ethylene oxide.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... accessory equipment made of steel, stainless steel, except types 416 and 442, or other material specially... stainless steel containing not less than 11% chromium; (4) Have gaskets constructed of spirally wound stainless steel with teflon or other material specially approved by the Commandant (CG-OES); (5) Not...

  19. 49 CFR 173.323 - Ethylene oxide.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... addition, each cylinder must be equipped with a fusible type relief device with yield temperature of 69 °C... polymerize, decompose or undergo other violent chemical reaction. (g) Copper, silver, mercury, magnesium...

  20. 49 CFR 173.323 - Ethylene oxide.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... bath at a temperature, and for a period of time, sufficient to ensure that an internal pressure equal... polymerize, decompose or undergo other violent chemical reaction. (g) Copper, silver, mercury, magnesium...

  1. 29 CFR 1910.1047 - Ethylene oxide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., the appropriate respirators specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134; however, employers... no cost to the employee, appropriate protective clothing or other equipment in accordance with 29 CFR... elements prescribed in 29 CFR 1910.38 and 29 CFR 1910.39, “Emergency action plans” and “Fire...

  2. 29 CFR 1910.1047 - Ethylene oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., the appropriate respirators specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134; however, employers... no cost to the employee, appropriate protective clothing or other equipment in accordance with 29 CFR... elements prescribed in 29 CFR 1910.38 and 29 CFR 1910.39, “Emergency action plans” and “Fire...

  3. 29 CFR 1910.1047 - Ethylene oxide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., the appropriate respirators specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134; however, employers... no cost to the employee, appropriate protective clothing or other equipment in accordance with 29 CFR... elements prescribed in 29 CFR 1910.38 and 29 CFR 1910.39, “Emergency action plans” and “Fire...

  4. Molecular-Level Control of Ciclopirox Olamine Release from Poly(ethylene oxide)-Based Mucoadhesive Buccal Films: Exploration of Structure-Property Relationships with Solid-State NMR.

    PubMed

    Urbanova, Martina; Gajdosova, Marketa; Steinhart, Miloš; Vetchy, David; Brus, Jiri

    2016-05-01

    Mucoadhesive buccal films (MBFs) provide an innovative way to facilitate the efficient site-specific delivery of active compounds while simultaneously separating the lesions from the environment of the oral cavity. The structural diversity of these complex multicomponent and mostly multiphase systems as well as an experimental strategy for their structural characterization at molecular scale with atomic resolution were demonstrated using MBFs of ciclopirox olamine (CPX) in a poly(ethylene oxide) (PEO) matrix as a case study. A detailed description of each component of the CPX/PEO films was followed by an analysis of the relationships between each component and the physicochemical properties of the MBFs. Two distinct MBFs were identified by solid-state NMR spectroscopy: (i) at low API (active pharmaceutical ingredient) loading, a nanoheterogeneous solid solution of CPX molecularly dispersed in an amorphous PEO matrix was created; and (ii) at high API loading, a pseudoco-crystalline system containing CPX-2-aminoethanol nanocrystals incorporated into the interlamellar space of a crystalline PEO matrix was revealed. These structural differences were found to be closely related to the mechanical and physicochemical properties of the prepared MBFs. At low API loading, the polymer chains of PEO provided sufficient quantities of binding sites to stabilize the CPX that was molecularly dispersed in the highly amorphous semiflexible polymer matrix. Consequently, the resulting MBFs were soft, with low tensile strength, plasticity, and swelling index, supporting rapid drug release. At high CPX content, however, the active compounds and the polymer chains simultaneously cocrystallized, leaving the CPX to form nanocrystals grown directly inside the spherulites of PEO. Interfacial polymer-drug interactions were thus responsible not only for the considerably enhanced plasticity of the system but also for the exclusive crystallization of CPX in the thermodynamically most stable

  5. Constructions of Factorizable Multilevel Hadamard Matrices

    NASA Astrophysics Data System (ADS)

    Matsufuji, Shinya; Fan, Pingzhi

    Factorization of Hadamard matrices can provide fast algorithm and facilitate efficient hardware realization. In this letter, constructions of factorizable multilevel Hadamard matrices, which can be considered as special case of unitary matrices, are inverstigated. In particular, a class of ternary Hadamard matrices, together with its application, is presented.

  6. An analysis of alternative technologies for the removal of ethylene from the CELSS biomass production chamber

    NASA Technical Reports Server (NTRS)

    Rakow, Allen L.

    1995-01-01

    A variety of technologies were analyzed for their potential to remove ethylene from the CELSS Biomass Production Chamber (BPC). During crop production (e.g., lettuce, wheat, soybean, potato) in the BPC ethylene can accumulate in the airspace and subsequently affect plant viability. The chief source of ethylene is the plants themselves which reside in plastic trays containing nutrient solution. The main sink for ethylene is chamber leakage. The removal technology can be employed when deleterious levels (e.g., 50 ppb for potato) of ethylene are exceeded in the BPC and perhaps to optimize the plant growth process once a better understanding is developed of the relationship between exogenous ethylene concentration and plant growth. The technologies examined were catalytic oxidation, molecular sieve, cryotrapping, permanganate absorption, and UV degradation. Upon analysis, permanganate was chosen as the most suitable method. Experimental data for ethylene removal by permanganate during potato production was analyzed in order to design a system for installation in the BPC air duct. In addition, an analysis of the impact on ethylene concentration in the BPC of integrating the Breadboard Scale Aerobic Bioreactor (BSAB) with the BPC was performed. The result indicates that this unit has no significant effect on the ethylene material balance as a source or sink.

  7. Ethylene Response Factor TERF1, Regulated by ETHYLENE-INSENSITIVE3-like Factors, Functions in Reactive Oxygen Species (ROS) Scavenging in Tobacco (Nicotiana tabacum L.).

    PubMed

    Zhang, Hongbo; Li, Ang; Zhang, Zhijin; Huang, Zejun; Lu, Pingli; Zhang, Dingyu; Liu, Xinmin; Zhang, Zhong-Feng; Huang, Rongfeng

    2016-01-01

    The phytohormone ethylene plays a crucial role in the production and accumulation of reactive oxygen species (ROS) in plants under stress conditions. Ethylene response factors (ERFs) are important ethylene-signaling regulators functioning in plant defense responses against biotic and abiotic stresses. However, the roles of ERFs during plant adapting to ROS stress have not yet been well documented. Our studies previously reported that a tomato ERF transcription factor TERF1 functions in the regulation of plant ethylene responses and stress tolerance. Here, we report our findings regarding the roles of TERF1 in ROS scavenging. In this study, we revealed that the transcription of TERF1 is regulated by upstream EIN3-like (EIN3, ethylene-insensitive 3) regulators LeEIL3 and LeEIL4 in tomato (Solanum lycopersicum), and is also inducible by exogenous applied ROS-generating reagents. Ectopic expression of TERF1 in tobacco promoted the expression of genes involved in oxidative stress responses, including carbonic anhydrase functioning in hypersensitive defense, catalase and glutathione peroxidase catalyzing oxidative reactions, and GDP-D-mannose pyrophosphorylase functioning in ascorbic acid biosynthesis, reduced the ROS content induced by ethylene treatment, and enhanced stress tolerance of tobacco seedlings to hydrogen peroxide (H2O2). Cumulatively, these findings suggest that TERF1 is an ethylene inducible factor regulating ROS scavenging during stress responses. PMID:27435661

  8. Ethylene Response Factor TERF1, Regulated by ETHYLENE-INSENSITIVE3-like Factors, Functions in Reactive Oxygen Species (ROS) Scavenging in Tobacco (Nicotiana tabacum L.)

    PubMed Central

    Zhang, Hongbo; Li, Ang; Zhang, Zhijin; Huang, Zejun; Lu, Pingli; Zhang, Dingyu; Liu, Xinmin; Zhang, Zhong-Feng; Huang, Rongfeng

    2016-01-01

    The phytohormone ethylene plays a crucial role in the production and accumulation of reactive oxygen species (ROS) in plants under stress conditions. Ethylene response factors (ERFs) are important ethylene-signaling regulators functioning in plant defense responses against biotic and abiotic stresses. However, the roles of ERFs during plant adapting to ROS stress have not yet been well documented. Our studies previously reported that a tomato ERF transcription factor TERF1 functions in the regulation of plant ethylene responses and stress tolerance. Here, we report our findings regarding the roles of TERF1 in ROS scavenging. In this study, we revealed that the transcription of TERF1 is regulated by upstream EIN3-like (EIN3, ethylene-insensitive 3) regulators LeEIL3 and LeEIL4 in tomato (Solanum lycopersicum), and is also inducible by exogenous applied ROS-generating reagents. Ectopic expression of TERF1 in tobacco promoted the expression of genes involved in oxidative stress responses, including carbonic anhydrase functioning in hypersensitive defense, catalase and glutathione peroxidase catalyzing oxidative reactions, and GDP-D-mannose pyrophosphorylase functioning in ascorbic acid biosynthesis, reduced the ROS content induced by ethylene treatment, and enhanced stress tolerance of tobacco seedlings to hydrogen peroxide (H2O2). Cumulatively, these findings suggest that TERF1 is an ethylene inducible factor regulating ROS scavenging during stress responses. PMID:27435661

  9. BIOSYNTHESIS OF STRESS ETHYLENE IN SOYBEAN SEEDLINGS: SIMILARITIES TO ENDOGENOUS ETHYLENE BIOSYNTHESIS

    EPA Science Inventory

    The similarity of stress ethylene biosynthesis in whole plants to endogenous ethylene biosynthesis was investigated using two inhibitors of ethylene biosynthesis, amino-ethoxyvinylglycine (AVG) and cobalt chloride (Co2+); and the intermediates, methionine, S-adenosylmethionine (S...

  10. Synthesis of silica coated zinc oxide–poly(ethylene-co-acrylic acid) matrix and its UV shielding evaluation

    SciTech Connect

    Ramasamy, Mohankandhasamy; Kim, Yu Jun; Gao, Haiyan; Yi, Dong Kee; An, Jeong Ho

    2014-03-01

    Graphical abstract: - Highlights: • Well layer thickness controlled silica shell was made on ZnO nanoparticles. • PEAA, an interfacial agent is used to make nanocomposite–polymer matrix by twin-screw extruder. • Si-ZnO/PEAA matrix is highly stable and UV protective as compared to ZnO/PEAA matrix. • Nanoparticle embedded polymer matrix is suggested to make UV shielding fabrics with Nylon4. - Abstract: Silica coated zinc oxide nanoparticles (Si-ZnO NPs) (7 nm thick) were synthesized successfully and melt blended with poly(ethylene-co-acrylic acid) (PEAA resin) to improving ultraviolet (UV) shielding of zinc oxide nanoparticles (ZnO NPs). The photostability of both the ZnO NPs and Si-ZnO NPs were analyzed by the difference in photoluminescence (PL) and by methylene blue (MB) degradation. Photo-degradation studies confirmed that Si-ZnO NPs are highly photostable compared to ZnO NPs. The melt blended matrices were characterized by field emission scanning electron microscopy interfaced with energy dispersive X-ray spectroscopy (FE-SEM-EDX). The UV shielding property was analyzed from the transmittance spectra of UV–visible (UV–vis) spectroscopy. The results confirmed fine dispersion of thick Si-ZnO NPs in the entire resin matrix. Moreover, the Si-ZnO/PEAA showed about 97% UV shielding properties than the ZnO/PEAA.

  11. [Secondary hyperoxaluria and nephrocalcinosis due to ethylene glycol poisoning].

    PubMed

    Monet, C; Richard, E; Missonnier, S; Rebouissoux, L; Llanas, B; Harambat, J

    2013-08-01

    We report the case of a 3-year-old boy admitted to the pediatric emergency department for ethylene glycol poisoning. During hospitalization, he presented dysuria associated with crystalluria. Blood tests showed metabolic acidosis with an elevated anion gap. A renal ultrasound performed a few weeks later revealed bilateral medullary hyperechogenicity. Urine microscopic analysis showed the presence of weddellite crystals. Secondary nephrocalcinosis due to ethylene glycol intoxication was diagnosed. Hyperhydration and crystallization inhibition by magnesium citrate were initiated. Despite this treatment, persistent weddellite crystals and nephrocalcinosis were seen more than 2years after the intoxication. Ethylene glycol is metabolized in the liver by successive oxidations leading to its final metabolite, oxalic acid. Therefore, metabolic acidosis with an elevated anion gap is usually found following ethylene glycol intoxication. Calcium oxalate crystal deposition may occur in several organs, including the kidneys. The precipitation of calcium oxalate in renal tubules can lead to nephrocalcinosis and acute kidney injury. The long-term renal prognosis is related to chronic tubulointerstitial injury caused by nephrocalcinosis. Treatment of ethylene glycol intoxication is based on specific inhibitors of alcohol dehydrogenase and hemodialysis in the most severe forms, and should be started promptly. PMID:23827374

  12. Ethylene monitoring and control system

    NASA Technical Reports Server (NTRS)

    Nelson, Bruce N. (Inventor); Richard, II, Roy V. (Inventor); Kane, James A. (Inventor)

    2001-01-01

    A system that can accurately monitor and control low concentrations of ethylene gas includes a test chamber configured to receive sample gas potentially containing an ethylene concentration and ozone, a detector configured to receive light produced during a reaction between the ethylene and ozone and to produce signals related thereto, and a computer connected to the detector to process the signals to determine therefrom a value of the concentration of ethylene in the sample gas. The supply for the system can include a four way valve configured to receive pressurized gas at one input and a test chamber. A piston is journaled in the test chamber with a drive end disposed in a drive chamber and a reaction end defining with walls of the test chamber a variable volume reaction chamber. The drive end of the piston is pneumatically connected to two ports of the four way valve to provide motive force to the piston. A manifold is connected to the variable volume reaction chamber, and is configured to receive sample gasses from at least one of a plurality of ports connectable to degreening rooms and to supply the sample gas to the reactive chamber for reaction with ozone. The apparatus can be used to monitor and control the ethylene concentration in multiple degreening rooms.

  13. Ethylene monitoring and control system

    NASA Technical Reports Server (NTRS)

    Nelson, Bruce N. (Inventor); Richard, II, Roy V. (Inventor); Kanc, James A. (Inventor)

    2000-01-01

    A system that can accurately monitor and control low concentrations of ethylene gas includes a test chamber configured to receive sample gas potentially containing an ethylene concentration and ozone, a detector configured to receive light produced during a reaction between the ethylene and ozone and to produce signals related thereto, and a computer connected to the detector to process the signals to determine therefrom a value of the concentration of ethylene in the sample gas. The supply for the system can include a four way valve configured to receive pressurized gas at one input and a test chamber. A piston is journaled in the test chamber with a drive end disposed in a drive chamber and a reaction end defining with walls of the test chamber a variable volume reaction chamber. The drive end of the piston is pneumatically connected to two ports of the four way valve to provide motive force to the piston. A manifold is connected to the variable volume reaction chamber, and is configured to receive sample gasses from at least one of a plurality of ports connectable to degreening rooms and to supply the sample gas to the reactive chamber for reaction with ozone. The apparatus can be used to monitor and control the ethylene concentration in multiple degreening rooms.

  14. Synthesis of amphiphilic diblock copolymer for surface modification of Ethylene-Norbornene Copolymers

    NASA Astrophysics Data System (ADS)

    Levinsen, Simon; Svendsen, Winnie Edith; Horsewell, Andy; Almdal, Kristoffer

    2014-03-01

    The aim of this work is to produce polymer modifiers in order to develop hydrophilic polymeric surfaces for use in microfluidics. The use of hydrophilic polymers in microfluidics will have many advantages e.g. preventing protein absorbance. Here we present an amphiphilic diblock copolymer consisting of a bulk material compatible block and a hydrophilic block. To utilize the possibility of incorporating diblock copolymers into ethylene-norbornene copolymers, we have in this work developed a model poly(ethylene-1-butene) polymer compatible with the commercial available ethylene-norbornene copolymer TOPAS. Through matching of the radius of gyration for the model polymer and TOPAS the miscibility was achieved. The poly(ethylene-1-butene) polymer was synthesized from a hydrogenated anionic polymerized polybutadiene polymer. As hydrophilic block poly(ethylene oxide) was subsequently added also with anionic polymerization. Recent miscibility results between the model polymer and TOPAS will be presented, as well ongoing efforts to study the hydrophilic surface.

  15. Ethylene-producing bacteria that ripen fruit.

    PubMed

    Digiacomo, Fabio; Girelli, Gabriele; Aor, Bruno; Marchioretti, Caterina; Pedrotti, Michele; Perli, Thomas; Tonon, Emil; Valentini, Viola; Avi, Damiano; Ferrentino, Giovanna; Dorigato, Andrea; Torre, Paola; Jousson, Olivier; Mansy, Sheref S; Del Bianco, Cristina

    2014-12-19

    Ethylene is a plant hormone widely used to ripen fruit. However, the synthesis, handling, and storage of ethylene are environmentally harmful and dangerous. We engineered E. coli to produce ethylene through the activity of the ethylene-forming enzyme (EFE) from Pseudomonas syringae. EFE converts a citric acid cycle intermediate, 2-oxoglutarate, to ethylene in a single step. The production of ethylene was placed under the control of arabinose and blue light responsive regulatory systems. The resulting bacteria were capable of accelerating the ripening of tomatoes, kiwifruit, and apples. PMID:25393892

  16. Iterative methods for Toeplitz-like matrices

    SciTech Connect

    Huckle, T.

    1994-12-31

    In this paper the author will give a survey on iterative methods for solving linear equations with Toeplitz matrices, Block Toeplitz matrices, Toeplitz plus Hankel matrices, and matrices with low displacement rank. He will treat the following subjects: (1) optimal (w)-circulant preconditioners is a generalization of circulant preconditioners; (2) Optimal implementation of circulant-like preconditioners in the complex and real case; (3) preconditioning of near-singular matrices; what kind of preconditioners can be used in this case; (4) circulant preconditioning for more general classes of Toeplitz matrices; what can be said about matrices with coefficients that are not l{sub 1}-sequences; (5) preconditioners for Toeplitz least squares problems, for block Toeplitz matrices, and for Toeplitz plus Hankel matrices.

  17. Bromination of selected pharmaceuticals in water matrices.

    PubMed

    Benitez, F Javier; Acero, Juan L; Real, Francisco J; Roldan, Gloria; Casas, Francisco

    2011-11-01

    The bromination of five selected pharmaceuticals (metoprolol, naproxen, amoxicillin, phenacetin, and hydrochlorothiazide) was studied with these compounds individually dissolved in ultra-pure water. The apparent rate constants for the bromination reaction were determined as a function of the pH, obtaining the sequence amoxicillin>naproxen>hydrochlorothiazide≈phenacetin≈metoprolol. A kinetic mechanism specifying the dissociation reactions and the species formed for each compound according to its pK(a) value and the pH allowed the intrinsic rate constants to be determined for each elementary reaction. There was fairly good agreement between the experimental and calculated values of the apparent rate constants, confirming the goodness of the proposed reaction mechanism. In a second stage, the bromination of the selected pharmaceuticals simultaneously dissolved in three water matrices (a groundwater, a surface water from a public reservoir, and a secondary effluent from a WWTP) was investigated. The pharmaceutical elimination trend agreed with the previously determined rate constants. The influence of the main operating conditions (pH, initial bromine dose, and characteristics of the water matrix) on the degradation of the pharmaceuticals was established. An elimination concentration profile for each pharmaceutical in the water matrices was proposed based on the use of the previously evaluated apparent rate constants, and the theoretical results agreed satisfactorily with experiment. Finally, chlorination experiments performed in the presence of bromide showed that low bromide concentrations slightly accelerate the oxidation of the selected pharmaceuticals during chlorine disinfection. PMID:21906777

  18. Inhibition of platelet spreading from plasma onto glass by an adsorbed layer of a novel fluorescent-labeled poly(ethylene oxide)/poly(butylene oxide) block copolymer: characteristics of the exclusion zone probed by means of polystyrene beads and macromolecules.

    PubMed

    Gingell, D; Owens, N

    1994-04-01

    We have investigated the anti-adhesive properties of a newly synthesized fluorescent triblock copolymer containing poly(ethylene oxide). This adsorbs from aqueous solution onto glass that has been rendered hydrophobic. When the polymer-treated surface was exposed to human platelet-rich plasma (PRP) or whole blood at 37 degrees C, platelet adhesion and spreading were prevented. Avid adhesion and rapid platelet spreading occurred along tracks scraped in the adsorbed polymer coating, as seen by video-enhanced interference reflection microscopy. Leukocytes from whole blood are eventually able to adhere to the polymer-treated surface and were seen to remove labeled polymer from their vicinity and accumulate it at the cell body. Interferometry using polystyrene spheres showed that they do not adhere to polymer-coated glass and are unable to approach closer than 70-95 nm. On scraped tracks, beads make molecular contacts with the glass. Because the fully extended solvated (EO)400 arms may extend up to 100 nm from the glass, this suggests that the polymer forms a monolayer with the hydrophilic arms projecting into the water, whereas the hydrophobic (BO)55 segment binds the molecule to the hydrophobic surface. Another tri-bloc copolymer with shorter hydrophilic arms allows particles to approach more closely. PMID:7516339

  19. Real-time monitoring of endogenous lipid peroxidation by exhaled ethylene in patients undergoing cardiac surgery.

    PubMed

    Cristescu, Simona M; Kiss, Rudolf; Hekkert, Sacco te Lintel; Dalby, Miles; Harren, Frans J M; Risby, Terence H; Marczin, Nandor

    2014-10-01

    Pulmonary and systemic organ injury produced by oxidative stress including lipid peroxidation is a fundamental tenet of ischemia-reperfusion injury, inflammatory response to cardiac surgery, and cardiopulmonary bypass (CPB) but is not routinely measured in a surgically relevant time frame. To initiate a paradigm shift toward noninvasive and real-time monitoring of endogenous lipid peroxidation, we have explored pulmonary excretion and dynamism of exhaled breath ethylene during cardiac surgery to test the hypothesis that surgical technique and ischemia-reperfusion triggers lipid peroxidation. We have employed laser photoacoustic spectroscopy to measure real-time trace concentrations of ethylene from the patient breath and from the CPB machine. Patients undergoing aortic or mitral valve surgery-requiring CPB (n = 15) or off-pump coronary artery bypass surgery (OPCAB) (n = 7) were studied. Skin and tissue incision by diathermy caused striking (> 30-fold) increases in exhaled ethylene resulting in elevated levels until CPB. Gaseous ethylene in the CPB circuit was raised upon the establishment of CPB (> 10-fold) and decreased over time. Reperfusion of myocardium and lungs did not appear to enhance ethylene levels significantly. During OPCAB surgery, we have observed increased ethylene in 16 of 30 documented reperfusion events associated with coronary and aortic anastomoses. Therefore, novel real-time monitoring of endogenous lipid peroxidation in the intraoperative setting provides unparalleled detail of endogenous and surgery-triggered production of ethylene. Diathermy and unprotected regional myocardial ischemia and reperfusion are the most significant contributors to increased ethylene. PMID:25128523

  20. Real-time monitoring of endogenous lipid peroxidation by exhaled ethylene in patients undergoing cardiac surgery

    PubMed Central

    Cristescu, Simona M.; Kiss, Rudolf; te Lintel Hekkert, Sacco; Dalby, Miles; Harren, Frans J. M.; Risby, Terence H.

    2014-01-01

    Pulmonary and systemic organ injury produced by oxidative stress including lipid peroxidation is a fundamental tenet of ischemia-reperfusion injury, inflammatory response to cardiac surgery, and cardiopulmonary bypass (CPB) but is not routinely measured in a surgically relevant time frame. To initiate a paradigm shift toward noninvasive and real-time monitoring of endogenous lipid peroxidation, we have explored pulmonary excretion and dynamism of exhaled breath ethylene during cardiac surgery to test the hypothesis that surgical technique and ischemia-reperfusion triggers lipid peroxidation. We have employed laser photoacoustic spectroscopy to measure real-time trace concentrations of ethylene from the patient breath and from the CPB machine. Patients undergoing aortic or mitral valve surgery-requiring CPB (n = 15) or off-pump coronary artery bypass surgery (OPCAB) (n = 7) were studied. Skin and tissue incision by diathermy caused striking (>30-fold) increases in exhaled ethylene resulting in elevated levels until CPB. Gaseous ethylene in the CPB circuit was raised upon the establishment of CPB (>10-fold) and decreased over time. Reperfusion of myocardium and lungs did not appear to enhance ethylene levels significantly. During OPCAB surgery, we have observed increased ethylene in 16 of 30 documented reperfusion events associated with coronary and aortic anastomoses. Therefore, novel real-time monitoring of endogenous lipid peroxidation in the intraoperative setting provides unparalleled detail of endogenous and surgery-triggered production of ethylene. Diathermy and unprotected regional myocardial ischemia and reperfusion are the most significant contributors to increased ethylene. PMID:25128523

  1. Outstanding properties of bistochastic matrices

    NASA Astrophysics Data System (ADS)

    Brugia, O.; Wolfowicz, W.

    1981-10-01

    The statistical properties of many devices used in communication systems, such as scramblers and line coding and decoding devices, are described by mathematical models in which the transition probability matrix is bistochastic. To facilitate the analysis of systems response, the specific properties of the bistochastic matrices are described in six theorems which are demonstrated.

  2. Fibonacci Identities, Matrices, and Graphs

    ERIC Educational Resources Information Center

    Huang, Danrun

    2005-01-01

    General strategies used to help discover, prove, and generalize identities for Fibonacci numbers are described along with some properties about the determinants of square matrices. A matrix proof for identity (2) that has received immense attention from many branches of mathematics, like linear algebra, dynamical systems, graph theory and others…

  3. Making almost commuting matrices commute

    SciTech Connect

    Hastings, Matthew B

    2008-01-01

    Suppose two Hermitian matrices A, B almost commute ({parallel}[A,B]{parallel} {<=} {delta}). Are they close to a commuting pair of Hermitian matrices, A', B', with {parallel}A-A'{parallel},{parallel}B-B'{parallel} {<=} {epsilon}? A theorem of H. Lin shows that this is uniformly true, in that for every {epsilon} > 0 there exists a {delta} > 0, independent of the size N of the matrices, for which almost commuting implies being close to a commuting pair. However, this theorem does not specifiy how {delta} depends on {epsilon}. We give uniform bounds relating {delta} and {epsilon}. The proof is constructive, giving an explicit algorithm to construct A' and B'. We provide tighter bounds in the case of block tridiagonal and tridiagnonal matrices. Within the context of quantum measurement, this implies an algorithm to construct a basis in which we can make a projective measurement that approximately measures two approximately commuting operators simultaneously. Finally, we comment briefly on the case of approximately measuring three or more approximately commuting operators using POVMs (positive operator-valued measures) instead of projective measurements.

  4. Nonphysiological binding of ethylene by plants.

    PubMed

    Abeles, F B

    1984-03-01

    Ethylene binding to seedling tissue of Vicia faba, Phaseolus vulgaris, Glycine max, and Triticum aestivum was demonstrated by determining transit time required for ethylene to move through a glass tube filled with seedling tissue. Transit time for ethylene was greater than that for methane indicating that these tissues had an affinity for ethylene. However, the following observations suggest that the binding was not physiological. Inhibitors of ethylene action such as Ag(+) ions and CO(2) did not decrease binding. Mushrooms which have no known sites of ethylene action also demonstrated ethylene binding. The binding of acetylene, propylene, ethylene, propane, and ethane more closely followed their solubility in water than any known physiological activity. PMID:16663455

  5. Nonphysiological Binding of Ethylene by Plants

    PubMed Central

    Abeles, Fred B.

    1984-01-01

    Ethylene binding to seedling tissue of Vicia faba, Phaseolus vulgaris, Glycine max, and Triticum aestivum was demonstrated by determining transit time required for ethylene to move through a glass tube filled with seedling tissue. Transit time for ethylene was greater than that for methane indicating that these tissues had an affinity for ethylene. However, the following observations suggest that the binding was not physiological. Inhibitors of ethylene action such as Ag+ ions and CO2 did not decrease binding. Mushrooms which have no known sites of ethylene action also demonstrated ethylene binding. The binding of acetylene, propylene, ethylene, propane, and ethane more closely followed their solubility in water than any known physiological activity. PMID:16663455

  6. Colorometric detection of ethylene glycol vapor

    NASA Technical Reports Server (NTRS)

    Helm, C.; Mosier, B.; Verostko, C. E.

    1970-01-01

    Very low concentrations of ethylene glycol in air or other gases are detected by passing a sample through a glass tube with three partitioned compartments containing reagents which successively convert the ethylene glycol vapor into a colored compound.

  7. Ethylene binding site affinity in ripening apples

    SciTech Connect

    Blankenship, S.M. . Dept. of Horticultural Science); Sisler, E.C. )

    1993-09-01

    Scatchard plots for ethylene binding in apples (Malus domestica Borkh.), which were harvested weekly for 5 weeks to include the ethylene climacteric rise, showed C[sub 50] values (concentration of ethylene needed to occupy 50% of the ethylene binding sites) of 0.10, 0.11, 0.34, 0.40, and 0.57 [mu]l ethylene/liter[sup [minus]1], respectively, for each of the 5 weeks. Higher ethylene concentrations were required to saturate the binding sites during the climacteric rise than at other times. Diffusion of [sup 14]C-ethylene from the binding sites was curvilinear and did not show any indication of multiple binding sites. Ethylene was not metabolized by apple tissue.

  8. Carbon nanomaterials in silica aerogel matrices

    SciTech Connect

    Hamilton, Christopher E; Chavez, Manuel E; Duque, Juan G; Gupta, Gautam; Doorn, Stephen K; Dattelbaum, Andrew M; Obrey, Kimberly A D

    2010-01-01

    Silica aerogels are ultra low-density, high surface area materials that are extremely good thermal insulators and have numerous technical applications. However, their mechanical properties are not ideal, as they are brittle and prone to shattering. Conversely, single-walled carbon nanotubes (SWCNTs) and graphene-based materials, such as graphene oxide, have extremely high tensile strength and possess novel electronic properties. By introducing SWCNTs or graphene-based materials into aerogel matrices, it is possible to produce composites with the desirable properties of both constituents. We have successfully dispersed SWCNTs and graphene-based materials into silica gels. Subsequent supercritical drying results in monolithic low-density composites having improved mechanical properties. These nanocomposite aerogels have great potential for use in a wide range of applications.

  9. Ethylene and 1-MCP regulate major volatile biosynthetic pathways in apple fruit.

    PubMed

    Yang, Xiaotang; Song, Jun; Du, Lina; Forney, Charles; Campbell-Palmer, Leslie; Fillmore, Sherry; Wismer, Paul; Zhang, Zhaoqi

    2016-03-01

    The effects of ethylene and 1-methylcyclopropene (1-MCP) on apple fruit volatile biosynthesis and gene expression were investigated. Statistical analysis identified 17 genes that changed significantly in response to ethylene and 1-MCP treatments. Genes encoding branched-chain amino acid aminotransferase (BCAT), aromatic amino acid aminotransferase (ArAT) and amino acid decarboxylases (AADC) were up-regulated during ripening and further enhanced by ethylene treatment. Genes related to fatty acid synthesis and metabolism, including acyl-carrier-proteins (ACPs), malonyl-CoA:ACP transacylase (MCAT), acyl-ACP-desaturase (ACPD), lipoxygenase (LOX), hydroperoxide lyase (HPL), alcohol dehydrogenase (ADH), pyruvate decarboxylase (PDC2), β-oxidation, acyl-CoA synthetase (ACS), enoyl-CoA hydratase (ECHD), acyl-CoA dehydrogenase (ACAD), and alcohol acyltransferases (AATs) also increased during ripening and in response to ethylene treatment. Allene oxide synthase (AOS), alcohol dehydrogenase 1 (ADH1), 3-ketoacyl-CoA thiolase and branched-chain amino acid aminotransferase 2 (BCAT2) decreased in ethylene-treated fruit. Treatment with 1-MCP and ethylene generally produced opposite effects on related genes, which provides evidence that regulation of these genes is ethylene dependent. PMID:26471562

  10. Involvement of ethylene in gibberellic acid-induced sulfur assimilation, photosynthetic responses, and alleviation of cadmium stress in mustard.

    PubMed

    Masood, Asim; Khan, M Iqbal R; Fatma, Mehar; Asgher, Mohd; Per, Tasir S; Khan, Nafees A

    2016-07-01

    The role of gibberellic acid (GA) or sulfur (S) in stimulation of photosynthesis is known. However, information on the involvement of ethylene in GA-induced photosynthetic responses and cadmium (Cd) tolerance is lacking. This work shows that ethylene is involved in S-assimilation, photosynthetic responses and alleviation of Cd stress by GA in mustard (Brassica juncea L.). Plants grown with 200 mg Cd kg(-1) soil were less responsive to ethylene despite high ethylene evolution and showed photosynthetic inhibition. Plants receiving 10 μM GA spraying plus 100 mg S kg(-1) soil supplementation exhibited increased S-assimilation and photosynthetic responses under Cd stress. Application of GA plus S decreased oxidative stress of plants grown with Cd and limited stress ethylene formation to the range suitable for promoting sulfur use efficiency (SUE), glutathione (GSH) production and photosynthesis. The role of ethylene in GA-induced S-assimilation and reversal of photosynthetic inhibition by Cd was substantiated by inhibiting ethylene biosynthesis with the use of aminoethoxyvinylglycine (AVG). The suppression of S-assimilation and photosynthetic responses by inhibiting ethylene in GA plus S treated plants under Cd stress indicated the involvement of ethylene in GA-induced S-assimilation and Cd stress alleviation. The outcome of the study is important to unravel the interaction between GA and ethylene and their role in Cd tolerance in plants. PMID:26998941

  11. Evolution of soot size distribution in premixed ethylene/air and ethylene/benzene/air flames: Experimental and modeling study

    SciTech Connect

    Echavarria, Carlos A.; Sarofim, Adel F.; Lighty, JoAnn S.; D'Anna, Andrea

    2011-01-15

    The effect of benzene concentration in the initial fuel on the evolution of soot size distribution in ethylene/air and ethylene/benzene/air flat flames was characterized by experimental measurements and model predictions of size and number concentration within the flames. Experimentally, a scanning mobility particle sizer was used to allow spatially resolved and online measurements of particle concentration and sizes in the nanometer-size range. The model couples a detailed kinetic scheme with a discrete-sectional approach to follow the transition from gas-phase to nascent particles and their coagulation to larger soot particles. The evolution of soot size distribution (experimental and modeled) in pure ethylene and ethylene flames doped with benzene showed a typical nucleation-sized (since particles do not actually nucleate in the classical sense particle inception is often used in place of nucleation) mode close to the burner surface, and a bimodal behavior at greater height above burner (HAB). However, major features were distinguished between the data sets. The growth of nucleation and agglomeration-sized particles was faster for ethylene/benzene/air flames, evidenced by the earlier presence of bimodality in these flames. The most significant changes in size distribution were attributed to an increase in benzene concentration in the initial fuel. However, these changes were more evident for high temperature flames. In agreement with the experimental data, the model also predicted the decrease of nucleation-sized particles in the postflame region for ethylene flames doped with benzene. This behavior was associated with the decrease of soot precursors after the main oxidation zone of the flames. (author)

  12. Dispersion of PMMA-grafted, mesoscopic iron-oxide rods in polymer films.

    PubMed

    Ferrier, Robert C; Huang, Yun; Ohno, Kohji; Composto, Russell J

    2016-03-01

    This study investigates the parameters that affect the dispersion of polymer grafted mesoscopic iron-oxide rods (FeMRs) in polymer matrices. FeMRs (212 nm long by 36 nm in diameter) are grafted with poly(methyl methacrylate) (PMMA) at three different brush molecular weights: 3.7 kg mol(-1), 32 kg mol(-1), and 160 kg mol(-1). Each FeMR sample was cast in a polymer thin film consisting of either PMMA or poly(ethylene oxide) (PEO) each at a molecular weight much higher or much lower than the brush molecular weight. We find that the FeMRs with 160 kg mol(-1) brush disperse in all matrices while the FeMRs with 32 kg mol(-1) and 3.7 kg mol(-1) brushes aggregate in all matrices. We perform simple free energy calculations, taking into account steric repulsion from the brush and van der Waals attraction between FeMRs. We find that there is a barrier for aggregation for the FeMRs with the largest brush, while there is no barrier for the other FeMRs. Therefore, for these mesoscopic particles, the brush size is the main factor that determines the dispersion state of FeMRs in polymer matrices with athermal or weakly attractive brush-matrix interactions. These studies provide new insight into the mechanisms that affect dispersion in polymer matrices of mesoscopic particles and therefore guide the design of composite films with well-dispersed mesoscopic particles. PMID:26908174

  13. Ethylene and senescence in petals of tradescantia.

    PubMed

    Suttle, J C; Kende, H

    1978-08-01

    Flowers of Tradescantia (clone O2) which are ephemeral, produce ethylene during senescence with the maximum rates occurring during the initial period of fading. Senescing isolated petals produce ethylene in a similar manner, exhibit a loss of membrane semipermeability, and exogenous ethylene hastens the onset as well as the subsequent rate of this loss. The aminoethoxy analog of 0.1 millimolar rhizobitoxine completely inhibits ethylene production by isolated petals but only partially the loss of membrane semipermeability. Isolated petals acquire a sensitivity to ethylene as they mature, becoming fully sensitive on the day of anthesis. PMID:16660498

  14. Optical properties of graphene simulated in MATLAB using scattering matrices

    NASA Astrophysics Data System (ADS)

    Cariappa K., S.; Kumar, Anil

    2016-04-01

    Transmittance and absorbance spectrum of monolayer and bilayer graphene are simulated, in wavelength range 400-900nm, using scattering matrices of graphene and air. MATLAB is used for simulations studies and the results are in good agreement with the experimental values reported in the literature. The high transmittance values exhibited by graphene along with its electrical properties make it a potential alternative to conventional transparent conducting oxides.

  15. S-matrices and integrability

    NASA Astrophysics Data System (ADS)

    Bombardelli, Diego

    2016-08-01

    In these notes we review the S-matrix theory in (1+1)-dimensional integrable models, focusing mainly on the relativistic case. Once the main definitions and physical properties are introduced, we discuss the factorization of scattering processes due to integrability. We then focus on the analytic properties of the two-particle scattering amplitude and illustrate the derivation of the S-matrices for all the possible bound states using the so-called bootstrap principle. General algebraic structures underlying the S-matrix theory and its relation with the form factors axioms are briefly mentioned. Finally, we discuss the S-matrices of sine-Gordon and SU(2), SU(3) chiral Gross–Neveu models. In loving memory of Lilia Grandi.

  16. Acute hepatotoxicity of ethylene and halogenated ethylenes after PCB pretreatment.

    PubMed

    Conolly, R B; Jaeger, R J

    1977-12-01

    Previous studies from our laboratory have shown that ethylene, vinyl fluoride monomer (VFM), vinyl chloride monomer (VCM), and vinyl bromide monomer (VBM) are all acutely hepatotoxic in rats pretreated with polychlorinated biphenyl (PCB). The time course of hepatic injury development after exposure and several parameters, environmental and chemical, affecting this toxicity were evaluated in the work reported here. Liver injury, as measured by serum alanine-alpha-ketoglutarate transaminase (SAKT) or sorbitol dehydrogenase (SDH), develops progressively over a 24-hr period following a 4-hr inhalation exposure of PCB-pretreated rats to ethylene or VCM. Environmental temperature during exposure to VCM does not affect hepatotoxicity or mortality below 30.3 degrees C. At 33.8 degrees C, however, mortality and SAKT are dramatically increased. Overnight fasting, which depletes hepatic glutathione (GSH) of PCB-pretreated rats before exposure to ethylene or VCM, significantly increases the hepatotoxicity of these compounds as measured by SDH. The combined effects of fasting and of trichloropropane epoxide (TCPE), an inhibitor of epoxide hydrase (EH), were also examined. TCPE treatment of fasted PCB-pretreated rats immediately before exposure was synergistic in increasing the acute toxicity of ethylene and VCM. TCPE increased mortality in fed or fasted rats exposed to VFM, but there was no effect of fasting alone. Both fasting and TCPE increased the sensitivity of PCB-pretreated rats to VBM, but there was not a clearly synergistic effect of fasting plus TCPE. These data suggest that the acute toxicity of these compounds is mediated through epoxide intermediates. PMID:417916

  17. Householder factorizations of unitary matrices

    NASA Astrophysics Data System (ADS)

    Urías, Jesús

    2010-07-01

    A method to construct all representations of finite dimensional unitary matrices as the product of Householder reflections is given. By arbitrarily severing the state space into orthogonal subspaces, the method may, e.g., identify the entangling and single-component quantum operations that are required in the engineering of quantum states of composite (multipartite) systems. Earlier constructions are shown to be extreme cases of the unifying scheme that is presented here.

  18. Threaded Operations on Sparse Matrices

    SciTech Connect

    Sneed, Brett

    2015-09-01

    We investigate the use of sparse matrices and OpenMP multi-threading on linear algebra operations involving them. Several sparse matrix data structures are presented. Implementation of the multi- threading primarily occurs in the level one and two BLAS functions used within the four algorithms investigated{the Power Method, Conjugate Gradient, Biconjugate Gradient, and Jacobi's Method. The bene ts of launching threads once per high level algorithm are explored.

  19. Compliance matrices for cracked bodies

    NASA Technical Reports Server (NTRS)

    Ballarini, R.

    1986-01-01

    An algorithm is presented which can be used to develop compliance matrices for cracked bodies. The method relies on the numerical solution of singular integral equations with Cauchy-type kernels and provides an efficient and accurate procedure for relating applied loadings to crack opening displacements. The algorithm should be of interest to those performing repetitive calculations in the analysis of experimental results obtained from fracture specimens.

  20. Rotationally invariant ensembles of integrable matrices

    NASA Astrophysics Data System (ADS)

    Yuzbashyan, Emil A.; Shastry, B. Sriram; Scaramazza, Jasen A.

    2016-05-01

    We construct ensembles of random integrable matrices with any prescribed number of nontrivial integrals and formulate integrable matrix theory (IMT)—a counterpart of random matrix theory (RMT) for quantum integrable models. A type-M family of integrable matrices consists of exactly N -M independent commuting N ×N matrices linear in a real parameter. We first develop a rotationally invariant parametrization of such matrices, previously only constructed in a preferred basis. For example, an arbitrary choice of a vector and two commuting Hermitian matrices defines a type-1 family and vice versa. Higher types similarly involve a random vector and two matrices. The basis-independent formulation allows us to derive the joint probability density for integrable matrices, similar to the construction of Gaussian ensembles in the RMT.