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Sample records for acid anhydride cured

  1. ULTRASONIC BEHAVIOR OF EPOXY RESINS/POLY (ETHYLENE OXIDE)BLENDS CURED WITH PHTHALIC ANHYDRIDE

    Institute of Scientific and Technical Information of China (English)

    ZHENG Sixun; WANG Haiqian; LUO Xiaolie; ZHANG Naibin; MA Dezhu; ZHU Changfei; HU Jiankai

    1995-01-01

    By means of ultrasonic attenuation apparatus, the ultrasonic velocity and attenuation of anhydride-cured epoxy resins (EP)/poly(ethylene oxide)(PEO)blends were measured on the basis of pulse-echo method. It was found that the sonic velocity of the blends decreased as the temperature increased, but attenuation coefficient increased and possessed a peak value. Larger velocity and smaller attenuation coefficient(α)can be obtained from perfect crosslinking network structures of pure DGEBA cured with phthalic anhydride (PA). As for cured DGEBA/PEO blend systems,sonic velocity decreased as a function of PEO concentration,but attenuation coefficient (α) increased.

  2. Curing behaviors and properties of an extrinsic toughened epoxy/anhydride system and an intrinsic toughened epoxy/anhydride system

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Mengjin; Liu, Jialin; Li, Xiangyuan [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Cheng, Jue, E-mail: chengjue@mail.buct.edu.cn [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Zhang, Junying, E-mail: zjybuct@gmail.com [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China)

    2013-02-20

    Highlights: ► Two curing systems (ETRS and ITRS) with similar chemical composite were prepared. ► The curing kinetics of the ETRS and the novel ITRS were comparatively studied. ► Crosslinking density can affect the kinetic schemes of the two curing systems. ► Their mechanical properties and thermal stabilities were also comparatively studied. ► Crosslinking density may play an influential role in mechanical properties. - Abstract: The curing kinetics of an extrinsic toughened epoxy (mixture of diglycidyl ether of bisphenol-A and 1,4-butanediol epoxy resin, DGEBA/DGEBD) and an intrinsic toughened epoxy (ethoxylated bisphenol-A epoxy resin with two oxyethylene units, DGEBAEO-2) using hexahydrophthalic anhydride (HHPA) as curing agent and tris-(dimethylaminomethyl) phenol (DMP-30) as accelerator were comparatively studied by non-isothermal DSC with a model-fitting Málek approach and a model-free advanced isoconversional method of Vyazovkin. The dynamic mechanical properties and thermal stabilities of the cured materials were investigated by DMTA and TGA, respectively. The results showed that Šesták–Berggren model can generally simulate well the reaction rates of these two systems. The activation energy of DGEBA/DGEBD/HHPA/DMP-30 at high fractional conversion changed much higher than that of DGEBAEO-2/HHPA/DMP-30, indicating the increased steric hindrance mainly affected the reaction kinetic scheme of DGEBA/DGEBD/HHPA/DMP-30. The T{sub g} and storage moduli of cured DGEBAEO-2/HHPA/DMP-30 were lower than those of cured DGEBA/DGEBD/HHPA/DMP-30 according to DMTA while TGA showed that the thermal stabilities of these two cured systems were similar.

  3. Effect of Hyperbranched Polyester on Modification of Epoxy Resins Cured with Anhydride

    Institute of Scientific and Technical Information of China (English)

    Xiu Xia WANG; Zhi Gang JIANG; Yi Feng ZHANG

    2006-01-01

    The synthesis and characterization of hyperbranched polyester (HBP) with different molecular weight are studied. The effect of HBP on the modification of epoxy resins cured with anhydride is mainly discussed. The characteristics of HBP and the morphologies of cured system are determined by nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC) and scanning electron microscope (SEM). The impact strength of cured system is detected and Fourier transform infrared (FTIR) measurements were used to pursue the curing process. The investigation shows that HBP can improve the toughness by forming copolymer networks between epoxy resins, HBP and anhydride. Moreover, when the molecular weight of HBP is 1342g/mol the toughening effect is the best, and the changes of toughness are small with the increase of molecular weight of HBP to 3500 g/mol.

  4. Tannic Acid as a Bio-Based Modifier of Epoxy/Anhydride Thermosets

    OpenAIRE

    Xiaoma Fei; Fangqiao Zhao; Wei Wei; Jing Luo; Mingqing Chen; Xiaoya Liu

    2016-01-01

    Toughening an epoxy resin by bio-based modifiers without trade-offs in its modulus, mechanical strength, and other properties is still a big challenge. This paper presents an approach to modify epoxy resin with tannic acid (TA) as a bio-based feedstock. Carboxylic acid-modified tannic acid (TA–COOH) was first prepared through a simple esterification between TA and methylhexahydrophthalic anhydride, and then used as a modifier for the epoxy/anhydride curing system. Owing to the chemical modifi...

  5. Effects of Amine and Anhydride Curing Agents on the VARTM Matrix Processing Properties

    Science.gov (United States)

    Grimsley, Brian W.; Hubert, Pascal; Song, Xiaolan; Cano, Roberto J.; Loos, Alfred C.; Pipes, R. Byron

    2002-01-01

    To ensure successful application of composite structure for aerospace vehicles, it is necessary to develop material systems that meet a variety of requirements. The industry has recently developed a number of low-viscosity epoxy resins to meet the processing requirements associated with vacuum assisted resin transfer molding (VARTM) of aerospace components. The curing kinetics and viscosity of two of these resins, an amine-cured epoxy system, Applied Poleramic, Inc. VR-56-4 1, and an anhydride-cured epoxy system, A.T.A.R.D. Laboratories SI-ZG-5A, have been characterized for application in the VARTM process. Simulations were carried out using the process model, COMPRO, to examine heat transfer, curing kinetics and viscosity for different panel thicknesses and cure cycles. Results of these simulations indicate that the two resins have significantly different curing behaviors and flow characteristics.

  6. A self-crosslinking thermosetting monomer with both epoxy and anhydride groups derived from Tung oil fatty acids: Synthesis and properties

    Science.gov (United States)

    A self-crosslinking compound with epoxy groups and anhydride groups (GEMA) has been successfully synthesized from Tung oil fatty acid by reacting with maleic anhydride via the Diels-Alder reaction. GEMA has very good storage stability and can be cured with trace amounts of tertiary amine. This advan...

  7. The influence of tertiary amine accelerators on the curing behaviors of epoxy/anhydride systems

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Tao; Zhang, Chongfeng; Zhang, Junying, E-mail: zjybuct@gmail.com; Cheng, Jue

    2014-02-10

    Highlights: • The influences of two types of accelerators (BDMA and DMP-30) on curing reaction of DGEBF/MeHHPA systems were studied comparatively. • The activation energy and kinetic parameters of DGEBF/MeHHPA systems with accelerator content of 0.2 phr and 0.5 phr were calculated, respectively. • The dependence of autocatalytic and non-autocatalytic curing reaction on the loading of accelerators was discussed. • The non-catalytic curing reaction dominated absolutely in the curing process of DGEBF/MeHHPA systems when the accelerator contents were 0.2 phr. - Abstract: Accelerators have significant effects on the curing behaviors of epoxy/anhydride (diglycidyl ether of bisphenol-F/methylhexahydrophthalic anhydride, DGEBF/MeHHPA) systems. Non-isothermal DSC was used to investigate the influence of dimethyl benzylamine (BDMA, 0.2 phr/0.5 phr) and Tris-(dimethyl aminomethyl) phenol (DMP-30, 0.2 phr/0.5 phr) on the curing behaviors of DGEBF/MeHHPA systems, respectively. When the amount of accelerators was kept constant, the activation energy calculated by Kissinger method changed slightly in the presence of either BDMA or DMP-30. And, with increasing the accelerator content from 0.2 phr to 0.5 phr, the value of activation energy decreased from 115 kJ/mol to 85 kJ/mol. Furthermore, the calculation results of Málek method identified that all systems in this study fitted Sesták–Berggren (SB) model and the corresponding model parameters, m and n, were obtained. It was found that the contribution of autocatalytic reaction with low accelerator content (0.2 phr) was far less than that with high accelerator content (0.5 phr)

  8. Catalytic behavior of Sn/Bi metal powder in anhydride-based epoxy curing.

    Science.gov (United States)

    Jang, Keon-Soo; Eom, Yong-Sung; Moon, Jong-Tae; Oh, Yong-Soo; Nam, Jae-Do

    2009-12-01

    In this paper, we report the catalytic activity of the Sn/Bi alloy beads and its acceleration of the exothermic epoxy curing reactions in various thermal conditions and bead compositions. As being used as low-melting solder balls in electronic interconnection processes with various epoxy systems, it was found that the Sn/Bi beads substantially lowered the exothermic peak temperature of the diglycidyl ether of bisphenol A (DGEBA)/anhydride systems in up to ca. 140 degrees C depending on different types of anhydride curing agents. The catalytic activation of Sn/Bi powder was initiated with a small amount of Sn/Bi powder, for example, lowering ca. 50 degrees C of the exothermic peak temperature by adding only 0.1 vol% of Sn/Bi powder. The catalytic capability of the powder was increased by using smaller sized beads corresponding to larger catalytic surface area at the same volume fraction. Exhibiting a latent catalytic effect, the catalytic activity of Sn/Bi powder was remained latent at temperatures lower than 100 degrees C in isothermal conditions.

  9. Tannic Acid as a Bio-Based Modifier of Epoxy/Anhydride Thermosets

    Directory of Open Access Journals (Sweden)

    Xiaoma Fei

    2016-08-01

    Full Text Available Toughening an epoxy resin by bio-based modifiers without trade-offs in its modulus, mechanical strength, and other properties is still a big challenge. This paper presents an approach to modify epoxy resin with tannic acid (TA as a bio-based feedstock. Carboxylic acid-modified tannic acid (TA–COOH was first prepared through a simple esterification between TA and methylhexahydrophthalic anhydride, and then used as a modifier for the epoxy/anhydride curing system. Owing to the chemical modification, TA–COOH could easily disperse in epoxy resin and showed adequate interface interaction between TA–COOH and epoxy matrix, in avoid of phase separation. The use of TA–COOH in different proportions as modifier of epoxy/anhydride thermosets was studied. The results showed that TA–COOH could significantly improve the toughness with a great increase in impact strength under a low loading amount. Moreover, the addition of TA–COOH also simultaneously improved the tensile strength, elongation at break and glass transition temperature. The toughening and reinforcing mechanism was studied by scanning electron microscopy (SEM, dynamic mechanical analysis (DMA and thermal mechanical analysis (TMA, which should be owned to the synergistic effect of good interface interaction, aromatic structure, decreasing of cross linking density and increasing of free volume. This approach allows us to utilize the renewable tannic acid as an effective modifier for epoxy resin with good mechanical and thermal properties.

  10. Hydration of AN Acid Anhydride: the Water Complex of Acetic Sulfuric Anhydride

    Science.gov (United States)

    Smith, CJ; Huff, Anna; Mackenzie, Becca; Leopold, Ken

    2017-06-01

    The water complex of acetic sulfuric anhydride (ASA, CH_{3}COOSO_{2}OH) has been observed by pulsed nozzle Fourier transform microwave spectroscopy. ASA is formed in situ in the supersonic jet via the reaction of SO_{3} and acetic acid and subsequently forms a complex with water during the expansion. Spectra of the parent and fully deuterated form, as well as those of the species derived from CH_{3}^{13}COOH, have been observed. The fitted internal rotation barrier of the methyl group is 219.599(21), \\wn indicating the complexation with water lowers the internal rotation barrier of the methyl group by 9% relative to that of free ASA. The observed species is one of several isomers identified theoretically in which the water inserts into the intramolecular hydrogen bond of the ASA. Aspects of the intermolecular potential energy surface are discussed.

  11. Increasing the electrical discharge endurance of acid anhydride cured DGEBA epoxy resin by dispersion of nanoparticle silica. High Perform. Polym. 11 (1999) pp 281-296 by IOP Publishing Ltd

    DEFF Research Database (Denmark)

    Henk, Peter O; Kortsen, T.W.; Kvarts, T.

    1999-01-01

    A fluid DGEBA/methyl nadicanhydride epoxy system has been filled with inorganic particles, cast as bubble-free plates and cured. The ability of both the pure network polymer and the polymer/particle composites to withstand partial electrical discharges has been investigated. Three types of particle...... the endurance by a factor of up to 20 as the Aerosil content goes from zero to 5.4 vol%. Aerosil mixed with anatase has a similar effect. The high level of endurance is maintained with an additional high-volume (35 vol.%) filling of coarse-particle dolomite to an epoxy system already containing Aerosil...

  12. Modification of wheat starch with succinic acid/acetic anhydride and azelaic acid/acetic anhydride mixtures I. Thermophysical and pasting properties.

    Science.gov (United States)

    Subarić, Drago; Ačkar, Durđica; Babić, Jurislav; Sakač, Nikola; Jozinović, Antun

    2014-10-01

    The aim of this research was to investigate the influence of modification with succinic acid/acetic anhydride and azelaic acid/acetic anhydride mixtures on thermophysical and pasting properties of wheat starch. Starch was isolated from two wheat varieties and modified with mixtures of succinic acid and acetic anhydride, and azelaic acid and acetic anhydride in 4, 6 and 8 % (w/w). Thermophysical, pasting properties, swelling power, solubility and amylose content of modified starches were determined. The results showed that modifications with mixtures of afore mentioned dicarboxylic acids with acetic anhydride decreased gelatinisation and pasting temperatures. Gelatinisation enthalpy of Golubica starch increased, while of Srpanjka starch decreased by modifications. Retrogradation after 7 and 14 day-storage at 4 °C decreased after modifications of both starches. Maximum, hot and cold paste viscosity of both starches increased, while stability during shearing at high temperatures decreased. % setback of starches modified with azelaic acid/acetic anhydride mixture decreased. Swelling power and solubility of both starches increased by both modifications.

  13. Preparation of epoxy/zirconia hybrid materials via in situ polymerization using zirconium alkoxide coordinated with acid anhydride

    Energy Technology Data Exchange (ETDEWEB)

    Ochi, Mitsukazu, E-mail: mochi@ipcku.kansai-u.ac.jp [Faculty of Chemistry, Materials and Bioengineering, Kansai University, 3-3-35 Suita-shi, Osaka 564-8680 (Japan); Nii, Daisuke; Harada, Miyuki [Faculty of Chemistry, Materials and Bioengineering, Kansai University, 3-3-35 Suita-shi, Osaka 564-8680 (Japan)

    2011-09-15

    Highlights: {yields} Novel epoxy/zirconia hybrid materials were synthesized via in situ polymerization using zirconium alkoxide coordinated with acid anhydride. {yields} The half-ester compound of acid anhydride desorbed from zirconium played as curing agent of epoxy resin. {yields} The zirconia was uniformly dispersed in the epoxy matrix on the nanometer or sub-nanometer scale by synchronizing the epoxy curing and sol-gel reactions. {yields} The refractive indices of the hybrid materials significantly improved with an increase in the zirconia content. - Abstract: Novel epoxy/zirconia hybrid materials were synthesized using a bisphenol A epoxy resin (diglycidyl ether of bisphenol A; DGEBA), zirconium(IV)-n-propoxide (ZTNP), and hexahydrophthalic anhydride (HHPA) via in situ polymerization. HHPA played two roles in this system: it acted as a modifier to control the hydrolysis and condensation reactions of zirconium alkoxide and also as a curing agent - the half-ester compound of HHPA desorbed from zirconium reacted with the epoxy resin to form the epoxy network. As a result, both the sol-gel reaction and epoxy curing occurred simultaneously in a homogeneous solution, and organic-inorganic hybrid materials were readily obtained. Further, the zirconia produced by the in situ polymerization was uniformly dispersed in the epoxy matrix on the nanometer or sub-nanometer scale; thus, hybrid materials that exhibited excellent optical transparency were obtained. Furthermore, the heat resistance of the hybrid materials could be improved by hybridization with zirconia. And, the refractive indices of the hybrid materials significantly improved with an increase in the zirconia content.

  14. Highly efficient peptide formation from N-acetylaminoacyl-AMP anhydride and free amino acid

    Science.gov (United States)

    Mullins, D. W., Jr.; Lacey, J. C., Jr.

    1983-01-01

    The kinetics of formation of the N-blocked dipeptide, N-acetylglycylglycine, from N-acetylglycyl adenylate anhydride and glycine in aqueous solution at 25 C, and at various PH's are reported. The reaction is of interest in that over a physiologically relevant pH range (6-8), peptide synthesis proceeds more rapidly than hydrolysis, even at those pH's at which this compound becomes increasingly susceptible to base-catalyzed hydrolysis. Under similar conditions, the corresponding unblocked aminoacyl adenylate anhydrides are considerably more unstable, and undergo appreciable hydrlysis in the presence of free amino acid. Because N-blocked aminoacyl adenylate anhydrides serve as model compounds of peptidyl adenylate anhydrides, these results suggest that primitive amino acid polymerization systems may have operated by cyclic reactivation of the peptidyl carboxyl group, rather than that of the incoming amino acid.

  15. Synthesis and curing of alkyd enamels based on ricinoleic acid

    Directory of Open Access Journals (Sweden)

    Jovičić Mirjana C.

    2010-01-01

    Full Text Available A combination of an alkyd resin with a melamine-formaldehyde resin gives a cured enamel film with the flexibility of the alkyd constituent and the high chemical resistance and hardness of the melamine resin at the same time. The melamine resin is a minor constituent and plays the role of a crosslinking agent. In this paper, alkyd resins of high hydroxyl numbers based on trimethylolpropane, ricinoleic acid and phthalic anhydride were synthesized. Two alkyds having 30 and 40 wt% of ricinoleic acid were formulated by calculation on alkyd constant. Alkyds were characterized by FTIR and by the determination of acid and hydroxyl numbers. Then synthesized alkyds were made into baking enamels by mixing with melamine-formaldehyde resins (weight ratio of 70:30 based on dried mass. Two types of commercial melamine resins were used: threeisobutoxymethyl melamine-formaldehyde resin (TIMMF and hexamethoxymethyl melamine resin (HMMMF. Prepared alkyd/melamine resin mixtures were cured in a differential scanning calorimeter (DSC under non-isothermal mode. Apparent degree of curing as a function of temperature was calculated from the curing enthalpies. Kinetic parameters of curing were calculated using Freeman-Carroll method. TIMMF resin is more reactive with synthesized alkyds than HMMMF resin what was expected. Alkyd resin with 30 wt% of ricinoleic acid is slightly more reactive than alkyd with 40 wt% of ricinoleic acid, probably because it has the high contents of free hydroxyl and acid groups. The gel content, Tg, thermal stability, hardness, elasticity and impact resistance of coated films cured at 150°C for 60 min were measured. Cured films show good thermal stability since the onset of films thermal degradation determined by thermogravimetric analysis (TGA is observed at the temperatures from 281 to 329°C. Films based on alkyd 30 are more thermal stable than those from alkyd 40, with the same melamine resin. The type of alkyd resin has no significant

  16. 21 CFR 872.3500 - Polyvinylmethylether maleic anhydride (PVM-MA), acid copolymer, and carboxymethylcellulose sodium...

    Science.gov (United States)

    2010-04-01

    ...), acid copolymer, and carboxymethylcellulose sodium (NACMC) denture adhesive. 872.3500 Section 872.3500...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3500 Polyvinylmethylether maleic anhydride (PVM-MA), acid copolymer, and carboxymethylcellulose sodium (NACMC) denture adhesive. (a) Identification...

  17. Thermal curing of an epoxy-anhydride system modified with hyperbranched poly(ethylene imine)s with different terminal groups

    OpenAIRE

    Morancho Llena, José María; Fernández Francos, Xavier; Acebo Gorostiza, Cristina; Ramis Juan, Xavier; Salla Tarragó, José María; Serra Albet, Àngels

    2017-01-01

    New hyperbranched polymers (HBP) have been synthesized by reaction of a poly(ethylene imine) with phenyl and t-butyl isocyanates. These HBPs have been characterized by 1H-NMR (nuclear magnetic resonance of hydrogen) and Fourier transform infrared spectroscopy. Their influence on the curing and properties of epoxy-anhydride thermosets has been studied by different techniques: differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and thermogravimetry (TG). The ...

  18. Oligoesters and polyesters produced by the curing of sunflower oil epoxidized biodiesel with cis-cyclohexane dicarboxylic anhydride: Synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Reiznautt, Quelen B. [Laboratory of Instrumentation and Molecular Dynamics, Department of Physical Chemistry, Chemistry Institute, Federal University of Rio Grande do Sul, Av. Bento Goncalves 9500, CEP: 91501-970, Porto Alegre (Brazil); Garcia, Irene T.S. [Department of Analytical and Inorganic Chemistry, Chemistry and Geosciences Institute, Federal University of Pelotas, 96010-900, Pelotas (Brazil); Samios, Dimitrios, E-mail: dsamios@iq.ufrgs.br [Laboratory of Instrumentation and Molecular Dynamics, Department of Physical Chemistry, Chemistry Institute, Federal University of Rio Grande do Sul, Av. Bento Goncalves 9500, CEP: 91501-970, Porto Alegre (Brazil)

    2009-08-31

    Oligoesters and polyesters produced from sunflower oil biodiesel were synthesized and characterized. The polymers were obtained through the reaction of fatty acid methyl epoxy esters (EE) with cis-1,2-cyclohexane dicarboxylic anhydride (CH) and triethylamine (TEA) as initiator. Some reactions were conducted by adding small amounts of 1,4-butanediol diglycidyl ether (BDGE). The intermediate products of the synthesis process, including sunflower oil, methyl ester, epoxidised methyl esters, and the oligoesters and polyesters produced, were followed by Fourier Transform Infrared Spectroscopy and {sup 1}H and {sup 13}C nuclear magnetic resonance. The products obtained from the curing of the epoxidised esters with different compositions present similar chemical structures; however, they still depend on the amount of the epoxy resin BDGE that was added in the polymerization reaction. Thermoplastic materials with molecular weights (MW) starting at 3800 g/mol and reaching very high MWs, resulted in cross linked polymers. The thermal behaviour of the different products was investigated using differential scanning calorimetry and thermogravimetric analyses. The presence of BDGE in the structure of the materials increases the bonding capacity, resulting in higher molecular weight materials, which present good thermal stability.

  19. Synthesis and Characterization of a Novel Biomaterial:Maleic Anhydride-modified Poly(dl-lactic acid)

    Institute of Scientific and Technical Information of China (English)

    Yan Feng LUO; Yuan Liang WANG; Xu Feng NIU; Jun PAN; Liang Ping SHI

    2004-01-01

    A novel modified poly(dl-lactic acid) (PDLLA) was obtained by covalently grafting of maleic anhydride onto the backbone of PDLLA, attempting to improve PDLLA's hydrophilicity and cell affinity and to provide reactive groups for further chemical modification. FTIR, 13C NMR and DSC were used to characterize the maleic anhydride-modified PDLLA.

  20. Preparation and Physical Properties of Chitosan Benzoic Acid Derivatives Using a Phosphoryl Mixed Anhydride System

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    Kyu Yun Chai

    2012-02-01

    Full Text Available Direct benzoylation of the two hydroxyl groups on chitosan was achieved using a phosphoryl mixed anhydride system, derived from trifluoroacetic anhydride (TFAA, benzoic acids (BAs, and phosphoric acid (PA. The reaction is operated as a one pot process under mild conditions that does not require neither an inert atmosphere nor dry solvents. The structures of the synthesized compounds were confirmed by NMR and IR spectroscopy. Solubility tests on the products revealed that they were soluble in organic solvents such as N,N-dimethylformamide (DMF, dimethylsulfoxide (DMSO, and acetone. In the meantime, a morphological study by scanning electron microscopy (SEM evidently indicated that the chitosan benzoates underwent significant structural changes after the benzoylation.

  1. Physical insights into salicylic acid release from poly(anhydrides).

    Science.gov (United States)

    Dasgupta, Queeny; Chatterjee, Kaushik; Madras, Giridhar

    2016-01-21

    Salicylic acid (SA) based biodegradable polyanhydrides (PAHs) are of great interest for drug delivery in a variety of diseases and disorders owing to the multi-utility of SA. There is a need for the design of SA-based PAHs for tunable drug release, optimized for the treatment of different diseases. In this study, we devised a simple strategy for tuning the release properties and erosion kinetics of a family of PAHs. PAHs incorporating SA were derived from related aliphatic diacids, varying only in the chain length, and prepared by simple melt condensation polymerization. Upon hydrolysis induced erosion, the polymer degrades into cytocompatible products, including the incorporated bioactive SA and diacid. The degradation follows first order kinetics with the rate constant varying by nearly 25 times between the PAH obtained with adipic acid and that with dodecanedioic acid. The release profiles have been tailored from 100% to 50% SA release in 7 days across the different PAHs. The release rate constants of these semi-crystalline, surface eroding PAHs decreased almost linearly with an increase in the diacid chain length, and varied by nearly 40 times between adipic acid and dodecanedioic acid PAH. The degradation products with SA concentration in the range of 30-350 ppm were used to assess cytocompatibility and showed no cytotoxicity to HeLa cells. This particular strategy is expected to (a) enable synthesis of application specific PAHs with tunable erosion and release profiles; (b) encompass a large number of drugs that may be incorporated into the PAH matrix. Such a strategy can potentially be extended to the controlled release of other drugs that may be incorporated into the PAH backbone and has important implications for the rational design of drug eluting bioactive polymers.

  2. Screening and assignment of phenylboronic acid and its anhydride formation by NMR spectroscopy

    Science.gov (United States)

    Chaudhari, Sachin R.

    2015-08-01

    The study discusses an approach that allows simultaneous determination of boronic acid and its anhydride without the need for tedious physical separation of the mixture. The assignment of the proton spectra of monomer, dimer and trimer was achieved by combining utility of 1D and 2D experimental techniques including 2D DOSY. The differential intensities of NMR peaks and supplementary resonances were detected in low polar solvents, such as, chloroform, toluene and in a non-polar solvent benzene. A fascinating phenomenon is observed at lower temperature where there is a formation of aryl boronic acid with the disappearance of boraxine formation.

  3. Study on Curing Reaction of Epoxidized Linseed Oil with Anhydrides%环氧亚麻油与酸酐固化反应研究

    Institute of Scientific and Technical Information of China (English)

    董宇; 裴帆; 石春韬; 王雪; 许艳玲; 李萍

    2015-01-01

    Epoxidized linseed oil is a type of epoxy resin synthesized by the epoxidation reaction of linsee d oil. Thermosetting epoxy resin-based polymer composites with a variety of properties can be prepared after the reaction of epoxy resin and curing agents, which can be used in many fields. In this work, the curing reaction of epoxidized linseed oil was studied and the optimized reaction conditions were also obtained by the application of orthogonal experimental method based on the best selection of curing agent and accelerator. Fourier transform infrared spectroscopy(FT-IR)and differential scanning calorimetry (DSC)techniques were applied to investigate the curing reaction process and characterization. The results show that a mixture of maleic anhydride and phthalic anhydride (molar ratio 0.83﹕0.17) was the best curing agent while N, N-dimethylbenzylamine was the best accelerator. The factors impacting curing reaction were in the order of mixed anhydride/epoxy ratio > temperature >amount of accelerator > time. Curing degree of the final product could reach 97.13% under the following optimized conditions:mixed anhydride / epoxy ratio was 1.2﹕1.0 (molar ratio), the amount of accelerator was 2.5%, the temperature and time were 120 ℃ and 4 h,respectively. IR characteristic absorption of epoxy and anhydride gradually disappeared as the proceeding of the reaction and the curing reaction tended to be complete. Curing reaction of epoxidized linseed oil with mixed anhydride is an exothermic one with peak temperature at 182.6 ℃ and reaction enthalpy is -130.2 J/g.%环氧亚麻油是亚麻油通过环氧化反应合成的环氧树脂,其可进一步与固化剂反应,制备具有多种性能的热固性环氧树脂基复合材料,在多种领域具有广泛应用。文中研究了环氧亚麻油的固化反应,在选择最佳固化剂和促进剂的基础上,用正交试验优化反应条件,红外光谱表征固化反应过程,差示扫描量热法(DSC

  4. Perfluoroalkylation of Unactivated Alkenes with Acid Anhydrides as the Perfluoroalkyl Source.

    Science.gov (United States)

    Kawamura, Shintaro; Sodeoka, Mikiko

    2016-07-18

    An efficient perfluoroalkylation of unactivated alkenes with perfluoro acid anhydrides was developed. Copper salts play a crucial role as a catalyst to achieve allylic perfluoroalkylation with the in situ generated bis(perfluoroacyl) peroxides. Furthermore, carboperfluoroalkylation of alkene bearing an aromatic ring at an appropriate position on the carbon side chain was found to proceed under metal-free conditions to afford carbocycles or heterocycles bearing a perfluoroalkyl group. This method, which makes use of readily available perfluoroalkyl sources, offers a convenient and powerful tool for introducing a perfluoroalkyl group onto an sp(3) carbon to construct synthetically useful skeletons.

  5. Grafting of poly (lactic acid) with maleic anhydride using supercritical carbon dioxide

    Science.gov (United States)

    Khankrua, R.; Pivsa-Art, S.; Hiroyuki, H.; Suttiruengwong, S.

    2015-07-01

    The aim of this work was to modify poly lactic acid (PLA) via free radical grafting with maleic anhydride (MA) by using supercritical carbon dioxide (SCCO2). Benzoyl peroxide (BPO) was used as an initiator. The solubility of MA in SCCO2 was first determined to estimate the suitable grafting conditions and equilibrium. From the solubility study of MA in SCCO2, it was found that the solubility of MA in SCCO2 increased with the increasing pressure and dissolution time. PLA films were first prepared by compression molding. The ratio of MA to BPO was 2:1. The reaction temperature and pressure were 70°C and 100 bar respectively. The grafting reaction and the degree of grafting were characterized by nuclear magnetic resonance (NMR) spectroscopy and titration, respectively. Scanning electron microscope (SEM) technique and contact angle were used to confirm the changes in physical properties of PLA film grafted MA. NMR spectrum indicated that the grafting of MA onto PLA was successively achieved. Degree of grafting by using SCCO2 was as high as 0.98%. This provided rather high grafting degree compared with other processes. SEM pictures showed the rough surface structure on modified PLA film. In addition, contact angle results showed an improvement of the hydrophilicity by maleic anhydride grafting onto polymers.

  6. One-pot odourless synthesis of thioesters via in situ generation of thiobenzoic acids using benzoic anhydrides and thiourea

    Directory of Open Access Journals (Sweden)

    Mohammad Abbasi

    2015-07-01

    Full Text Available An efficient and odourless procedure for a one-pot synthesis of thioesters by the reaction of benzoic anhydrides, thiourea and various organic halides (primary, allylic, and benzylic or structurally diverse, electron-deficient alkenes (ketones, esters, and nitriles in the presence of Et3N has been developed. In this method, thiobenzoic acids were in situ generated from the reaction of thiourea with benzoic anhydrides, which were subjected to conjugate addition with electron-deficient alkenes or a nucleophilic displacement reaction with alkyl halides.

  7. Preparation and structural characterisation of novel and versatile amphiphilic octenyl succinic anhydride-modified hyaluronic acid derivatives

    DEFF Research Database (Denmark)

    Eenschooten, Corinne Diane; Guillaumie, Fanny; Kontogeorgis, Georgios

    2010-01-01

    The purpose of the present study was to prepare amphiphilic hyaluronic acid (HA) derivatives and to study the influence of a selection of reaction parameters on the degree of substitution (DS) of the derivatives. Octenyl succinic anhydride (OSA)–modified HA (OSA–HA) derivatives were prepared...

  8. Fluorescence and Judd-Ofelt analysis of rare earth complexes with maleic anhydride and acrylic acid

    Institute of Scientific and Technical Information of China (English)

    WEN Shipeng; ZHANG Xiaoping; HU Shui; ZHANG Liqun; LIU Li

    2008-01-01

    Two kinds of Eu-complexes, Eu(TTA)2(Phen)(AA) and Eu(TTA)2(Phen)(MA) (HTFA=2-Thenoyltrifluoroacetone, Phen=1,10-phenanthroline, AA=acrylic acid, MA=Maleic anhydride), which combined the excellent fluorescence properties of Eu(TTA)2(Phen)(H2O) and the reactivity of acrylic acid and maleic anhydride with radicals, were synthesized. The two complexes were characterized by elemental analysis, infrared (IR) spectra, and X-ray photoelectron spectroscopy (XPS). Based on the data shown from the fluorescent spectra of the Eu-MA and Eu-AA complexes, the Ωλ (λ=2 and 4) experimental intensity parameters were calculated. The results demonstrated that the Ω2 intensity parameters for the two complexes were smaller than those for the Eu(TTA)2(Phen)(H2O) complex, indicating that a less symmetri-cal chemical environment existed in the complexes. It implied that the radiative efficiency of the 5D0 of these two complexes could be en-hanced by ligand of MA and AA, respectively. The luminescent lifetime of the Eu-AA (τ=7.26×10-4 s) or Eu-MA complex (τ=-8.12×10-4 s) was higher than that of the Eu(TTA)2(Phen)(H2O) complex, which was attributed to the substitution of the water molecule (H2O) in Eu(TTA)2(Phen)(H2O) by the MA or AA ligand.

  9. A NOVEL COPOLYMER-BOUND CIS- DICARBONYLRHODIUM COMPLEX FOR THE CARBONYLATION OF METHANOL TO ACETIC ACID AND ACETIC ANHYDRIDE

    Institute of Scientific and Technical Information of China (English)

    YUAN Guoqing; CHEN Yuying; CHEN Rongyao

    1989-01-01

    A series of porous microspheres of linear and ethylene diacrylate (M ') cross-linked copolymers of 2 - vinylpyridine (V) and methyl acrylate (M) reacted with tetracarbonyldichlorodirhodium to form a series of cis-dicarbonylrhodium chelate complex (MVRh and MVM 'Rh). They are thermally stable yet very reactive in the carbonylation of methanol to acetic acid, and of methanol - acetic acid mixture to acetic acid and acetic anhydride with a selectivity of 100% under relatively mild and anhydrous conditions.

  10. 40 CFR 721.3635 - Octadecanoic acid, ester with 1,2-propanediol, phosphate, anhydride with silicic acid (H4SiO4).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Octadecanoic acid, ester with 1,2..., ester with 1,2-propanediol, phosphate, anhydride with silicic acid (H4SiO4). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as octadecanoic acid,...

  11. Application of palladium-catalyzed carboxyl anhydride-boronic acid cross coupling in the synthesis of novel bile acids analogs with modified side chains.

    Science.gov (United States)

    Mayorquín-Torres, Martha C; Flores-Álamo, Marcos; Iglesias-Arteaga, Martin A

    2015-09-01

    Palladium-catalyzed cross coupling of 4-methoxycarbonyl phenyboronic acid with acetylated bile acids in which the carboxyl functions was activated by formation of a mixed anhydride with pivalic anhydride afforded the cross coupled compounds, which were converted in novel side chain modified bile acids by one pot carbonyl reduction/removal of the protecting acetyl groups by Wolff-Kishner reduction. Unambiguous assignments of the NMR signals and crystal characterization of the heretofore unknown compounds are provided. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. MECHANICAL RELAXATION AND INTERMOLECULAR INTERACTION IN EPOXY RESINS/POLY (ETHYLENE OXIDE)BLENDS CURED WITH PHTHALIC ANHYDRIDE

    Institute of Scientific and Technical Information of China (English)

    LUO Xiaolie; ZHENG Sixun; MA Dezhu; HU Keliang

    1995-01-01

    The miscibility of the blend,composed of a bisphenol A epoxy resins (Diglycidyl etherof bisphenol A) (DGEBA) and poly(ethylene oxide) (PEO) and crosslinked by phthalicanhydride (PA) was studied using dynamic mechanical method. Single glass transitiontemperatures intermediate between the two pure components were observed for all blendlevels. The secondary relaxation mechanism should relate to not only diester linkage, butalso hydroxyether structural unit in the system. Fourier transform infrared spectroscopy(FTIR) is applied to study the curing reaction and intermolecular specific interaction of thesystem. The results indicate the PEO participates the crosslinking reaction, accelerates thecuring reaction and make the reaction more perfect. The shifts of the hydroxyl band andcarbonyl band demonstrate the presence of the intermolecular interaction in the curedblend. Moreover, the molecular interaction between the side hydroxyl in the hydroxyetherunits and the ether bond in PEO macromolecules is stronger.

  13. THE THERMAL AND ABLATIVE DEGRADATION OF SOME EPOXY RESINS CURED WITH METHYL BICYCLO(2.2.1)HEPTENE-2,3-DICARBOXYLIC ANHYDRIDE (NMA).

    Science.gov (United States)

    ABLATION), (* EPOXY RESINS , (*PYROLYSIS, EPOXY RESINS ), CYCLOALKENES, ANHYDRIDES, CATALYSTS, ADDITIVES, CROSSLINKING(CHEMISTRY), REACTION KINETICS, DEGRADATION, AGING(MATERIALS), INFRARED SPECTRA, CHROMATOGRAPHIC ANALYSIS.

  14. Locally delivered salicylic acid from a poly(anhydride-ester): impact on diabetic bone regeneration.

    Science.gov (United States)

    Wada, Keisuke; Yu, Weiling; Elazizi, Mohamad; Barakat, Sandrine; Ouimet, Michelle A; Rosario-Meléndez, Roselin; Fiorellini, Joseph P; Graves, Dana T; Uhrich, Kathryn E

    2013-10-10

    Diabetes mellitus (DM) involves metabolic changes that can impair bone repair, including a prolonged inflammatory response. A salicylic acid-based poly(anhydride-ester) (SA-PAE) provides controlled and sustained release of salicylic acid (SA) that locally resolves inflammation. This study investigates the effect of polymer-controlled SA release on bone regeneration in diabetic rats where enhanced inflammation is expected. Fifty-six Sprague-Dawley rats were randomly assigned to two groups: diabetic group induced by streptozotocin (STZ) injection or normoglycemic controls injected with citrate buffer alone. Three weeks after hyperglycemia development or vehicle injection, 5mm critical sized defects were created at the rat mandibular angle and treated with SA-PAE/bone graft mixture or bone graft alone. Rats were euthanized 4 and 12weeks after surgery, then bone fill percentage in the defect region was assessed by micro-computed tomography (CT) and histomorphometry. It was observed that bone fill increased significantly at 4 and 12weeks in SA-PAE/bone graft-treated diabetic rats compared to diabetic rats receiving bone graft alone. Accelerated bone formation in normoglycemic rats caused by SA-PAE/bone graft treatment was observed at 4weeks but not at 12weeks. This study shows that treatment with SA-PAE enhances bone regeneration in diabetic rats and accelerates bone regeneration in normoglycemic animals.

  15. An atom-economic approach to carboxylic acids via Pd-catalyzed direct addition of formic acid to olefins with acetic anhydride as a co-catalyst.

    Science.gov (United States)

    Wang, Yang; Ren, Wenlong; Shi, Yian

    2015-08-21

    An effective Pd-catalyzed hydrocarboxylation of olefins using formic acid with acetic anhydride as a co-catalyst is described. A variety of carboxylic acids are obtained in good yields with high regioselectivities under mild reaction conditions without the use of toxic CO gas.

  16. EFFECT OF SUBSTITUTION POSITION OF HYDROXY GROUP AT BENZOIC ACID ON THE LUMINESCENT AND DEGRADATION PROPERTIES OF POLY[DI(CARBOXYPHENYL) SUCCINATE-co-SEBACIC ANHYDRIDE]S

    Institute of Scientific and Technical Information of China (English)

    Jun Fan; Hong-liang Jiang; Kang-jie Zhu

    2007-01-01

    In this work, two new diacids, di(m-carboxyphenyl) succinate (m-dCPS) and di(o-carboxyphenyl) succinate (o-dCPS), were synthesized by reaction of m-, o-hydroxy benzoic acid with succinic chloride, respectively. Their corresponding copolymers with sebacic acid (SA), P(m-dCPS:SA) and P(o-dCPS:SA), were prepared by melt copolycondensation and characterized by NMR, UV and DSC methods. Compared with inherently fluorescent poly[di(p-carboxyphenyl) succinateco-sebacic anhydride] (P(p-dCPS:SA)), P(m-dCPS:SA) and P(o-dCPS:SA) displayed different luminescent properties. P(m-dCPS:SA) could emit fluorescence under the excitation of both visible and UV light, while P(o-dCPS:SA) could only emit fluorescence when excited with UV light. Degradation rate of the two new copolyanhydrides increased with the increase of SA fraction in the copolymers. In addition, P(o-dCPS:SA) degraded more rapidly than P(m-dCPS:SA) with the same composition. Typical surface-degradation characteristics of these copolyanhydrides were observed.

  17. Synthesis of high molecular weight polylactic acid from aqueous lactic acid co-catalyzed by tin(II)chloride dihydrate and succinic anhydride

    Institute of Scientific and Technical Information of China (English)

    LEI Ziqiang; BAI Yanbin; WANG Shoufeng

    2005-01-01

    Polylactic acid was synthesized from commercial available cheap aqueous lactic acid (85%―90% w/w) using succinic anhydride and SnCl2·2H2O as catalyst in the absence of organic solvents. As a result, polylactic acid with a molecular weight of 60000 was prepared in 10 h. The new procedure is much simple, cheap and outstanding in that the start material is aqueous lactic acid; the catalytic system is environmentally benign.

  18. Effect of Amine Catalyst Work on Epoxy / Anhydride Curing System%胺类促进剂对环氧树脂/酸酐固化体系的影响

    Institute of Scientific and Technical Information of China (English)

    刘琳; 张晓逆

    2012-01-01

    Adopting liquid methyltetrahydro phthalic anhydride as curing agent, multiplicate amine catalyst (including aliphatic ethanol amine, cycloaliphatic amine, aliphatic amine, quaternary ammonium salt, urea) were used to study diglycidyl ether bisphnol-A epoxy resin system. The best formula was confirmed from the aspects of amine catalyst compatibility, gel time, Tg, pot life etc. The results showed that cycloaliphatic amine (N,N-dimethylcyclohexylamine), aliphatic amine (N-dimethylpropane-l, 3-diamine), quaternary ammonium salt ( 2,2-dimethyl-Propanoic acid ammonium salt) could accelerate the curing system by decreasing the curing temperature from 160? to 100-120? and satisfied the mechanical properties request of FRP wind and casting / encapsulation.%以液体四氢甲基苯酐为固化剂,选用了多种胺类促进剂(包括脂肪类乙醇胺、脂环胺、脂肪胺、季胺盐、脲类)对双酚A缩水甘油醚类环氧树脂固化体系进行研究.从固化促进剂的相容性、凝胶时间、玻璃化转化温度、可使用时间等方面确定最佳配方.研究表明,脂环胺(N,N-二甲环己胺)、脂肪胺[三(二甲胺基丙基)胺]、季胺盐(2,2-二甲基丙酸季胺盐)可以促进双酚A缩水甘油醚类环氧树脂/液体四氢甲基苯酐固化体系的固化,并能使该体系的固化温度从160℃降低到100~120℃,力学性能达到玻璃钢缠绕和灌封浇注料的要求.

  19. ACID RESISTANCE OF FLYASH BASED GEOPOLYMER MORTAR UNDER AMBIENT CURING AND HEAT CURING

    Directory of Open Access Journals (Sweden)

    V.Sreevidya

    2012-02-01

    Full Text Available An Experimental study was conducted to assess the Acid resistance of flyash based geopolymer mortar specimens of size 50x50x50mm with a ratio of flyash to sand as 1:3.The ratio between solution(Sodiumhydroxide and Sodium silicate solution to flyash were 0.376,0.386,0.396 and 0.416. After casting the specimens were subjected to both ambient curing and heat curing. In heat curing the specimens were kept continuously at 60oC for 24 hrs. Durability of specimens was assessed by immersing them in 5% of sulfuric acid and 5%hydrochloric acid for a period of 14 weeks. Evaluation of its resistance in terms of change in weight, compressive strength and visual appearance at regular intervals was carried out. After exposure in the acid solutions for 14 weeks, the samples showed very low weight loss. Results obtained from the present study indicate that Geopolymers are highly resistance to sulfuric acid and hydrochloric acid.

  20. KINETIC STUDY OF CARBONYLATION OF METHANOL TO ACETIC ACID AND ACETIC ANHYDRIDE OVER A NOVEL COPOLYMER- BOUND CIS- DICARBONYLRHODIUM COMPLEX

    Institute of Scientific and Technical Information of China (English)

    CHEN Yuying; YUAN Guoqing; CHEN Rongyao

    1989-01-01

    The kinetic study of carbonylation of methanol-acetic acid mixture to acetic acid and acetic anhydride over a cis-dicarbonylrhodium complex (MVM' Rh)coordinated with the ethylene diacrylate (M')crosslinked copolymer of methyl acrylate (M) and 2 - vinylpyridine (V) shows that the rate of reaction is zero order with respect to both reactants methanol and carbon monoxide, but first order in the concentrations of promoter methyl iodide and rhodium in the complex . Polar solvents can accelerate the reaction .Activation parameters were calculated from the experimental results, being comparable to that of the homogeneous system . A mechanism similar to that of soluble rhodium catalyst was proposed .

  1. 亚临界水介质回收酸酐固化环氧树脂/碳纤维复合材料%Recycling of Carbon Fiber Reinforced Epoxy Resin Cured with Anhydride in Subcritical Water

    Institute of Scientific and Technical Information of China (English)

    王一明; 刘杰; 吴广峰; 唐涛

    2013-01-01

    研究了不同添加剂对碳纤维增强酸酐固化环氧树脂复合材料在亚临界水中降解的影响,通过IR、GC-MS等分析,确定了环氧树脂的分解机理主要为酯键的断裂.结果表明,KOH与苯酚对酸酐固化环氧树脂的分解没有协同效应,碱性物质更有利于酯键的断裂.甲基四氢邻苯二甲酸酐固化的环氧树脂增强碳纤维复合材料在反应温度为250℃、反应时间为60 min、KOH浓度为0.2 mol/L时可完全分解,回收碳纤维的拉伸强度和表面形貌未受影响.%Effect of additives on the decomposition behavior of the carbon fiber reinforced epoxy resin cured with anhydride in subcritical water was investigated.IR and GC-MS results show that the decomposition is ascribed to cleavage of ester bond.KOH and phenol does not exhibit the synergetic effect on the decomposition of anhydride cured epoxy resin.Alkaline conditions are found to be favorable to the cleavage of ester linkages.The carbon fiber reinforced methyl-tetrabydrophalic anhydride (MeTHPA) cured epoxy resin composite was totally decomposed with the addition of 0.2 mol/L KOH at 250 ℃ for 60 min.The tensile strength and morphology of the recycled carbon fibers are not influenced.

  2. Synthesis of comb-like copolymers from renewable resources: Itaconic anhydride, stearyl methacrylate and lactic acid

    Science.gov (United States)

    Shang, Shurui

    The synthesis and properties of comb-like copolymers and ionomers derived from renewable resources: itaconic anhydride (ITA), stearyl methacrylate (SM) and lactic acid (LA) are described. The copolymers based on ITA and SM (ITA-SM) were nearly random with a slight alternating tendency. The copolymers exhibited a nanophase-separated morphology, with the stearate side-chains forming a bilayer, semi-crystalline structure. The crystalline side-chains suppressed molecular motion of the main-chain, so that a glass transition temperature (Tg) was not resolved unless the ITA concentration was sufficiently high so that Tg > the melting point (Tm). The softening point and modulus of the copolymers increased with the increasing ITA concentration, but the thermal stability decreased. The ITA moiety along the main chain of the copolymers was neutralized with metal acetates to produce Na-, Ca- and Zn- random ionomers with comb-like architectures. In general, the incorporation of the ionic groups increased the Tg and suppressed the crystallinity of the side-chain packing. Ionomers with high SM side-chain density had two competing driving forces for self-assembled nano-phase separation: ionic aggregation and side-chain crystalline packing. Upon neutralization, a morphological transition from semi-crystalline lamella to spherical ionic aggregation was observed by small angle X-ray scattering (SAXS) analysis and transmission electron microscopy (TEM). Thermomechanical analysis revealed an increasing resistance to penetration deformation with an increasing degree of neutralization and an apparent rubbery plateau was observed above Tg. A controlled transesterification of PLA in glassware was an effective way to prepare a methacrylate functionalized PLA macromonomer with controlled molecular weight, which was used to synthesize a variety of copolymers. The copolymerization of this functionalized PLA macromonomer with ITA totally suppressed the side-chain crystallinity for the PLA chain

  3. α-Costic anhydride

    Directory of Open Access Journals (Sweden)

    Moha Berraho

    2010-03-01

    Full Text Available The title compound [systematic name: 2-(4a,8-dimethyl-1,2,3,4,4a,5,6,8a-octahydronaphthalen-2-ylacrylic acid anhydride], C30H42O3, is a new isocostic anhydride which was synthesized from the aerial part of Inula Viscosa (L Aiton [or Dittrichia Viscosa (L Greuter]. The molecule adopts an essentially linear shape with two terminal fused-rings bridged by the anhydride group. The external rings have the same conformation (half-chair while each of the two inner rings has an almost ideal chair conformation. In the crystal, intermolecular C—H...O interactions link the molecules into a two-dimensional array in the bc plane.

  4. α-Costic anhydride.

    Science.gov (United States)

    Tebbaa, Mohamed; Akssira, Mohamed; Elhakmaoui, Ahmed; El Ammari, Lahcen; Benharref, Ahmed; Berraho, Moha

    2010-02-13

    THE TITLE COMPOUND [SYSTEMATIC NAME: 2-(4a,8-dimethyl-1,2,3,4,4a,5,6,8a-octa-hydro-naphthalen-2-yl)acrylic acid anhydride], C(30)H(42)O(3), is a new isocostic anhydride which was synthesized from the aerial part of Inula Viscosa- (L) Aiton [or Dittrichia Viscosa- (L) Greuter]. The mol-ecule adopts an essentially linear shape with two terminal fused-rings bridged by the anhydride group. The external rings have the same conformation (half-chair) while each of the two inner rings has an almost ideal chair conformation. In the crystal, inter-molecular C-H⋯O inter-actions link the mol-ecules into a two-dimensional array in the bc plane.

  5. Investigation of the ageing effects on phenol-urea-formaldehyde binder and alkanol amine-acid anhydride binder coated mineral fibres

    DEFF Research Database (Denmark)

    Zafar, Ashar; Schjødt-Thomsen, Jan; Sodhi, R.;

    2013-01-01

    Phenol-Urea-Formaldehyde (PUF) binder coated mineral fibres' mechanical properties have been observed to degrade during ageing at elevated temperatures and humidity, while alkanol amine-acid anhydride binder based mineral fibres exhibited better ageing properties for same duration of ageing. X......-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were employed to identify the chemical changes occurring in the PUF binder coated mineral fibres and alkanol amine-acid anhydride binder coated mineral fibres during that ageing. The samples were aged in a climate...... of amide, methylene ether and methylene linkages between urea groups present in the PUF binder. In the case of the alkanol amine-acid anhydride binder coated mineral fibres, both XPS and ToF-SIMS techniques consistently showed that the surface chemical composition of the organic components of the alkanol...

  6. Curing mechanism and kinetics of epoxy/anhydride system modified by benzoxazine%苯并嗪改性环氧酸酐体系的固化机理及动力学

    Institute of Scientific and Technical Information of China (English)

    廖进彬; 姜其斌; 曾智; 李鸿岩

    2014-01-01

    An epoxy/anhydride system was modified by aromatic diamine-based benzoxazine. The curing mechanism of the system was analyzed with Fourier transform infrared spectroscopy(FT-IR)and differential scanning calorimetry (DSC). The blend system exhibited two curing reactions in the curing process. Epoxy resin first cured with sufficient anhydride catalyzed by imidazole at 100℃, and cured completely at 150℃ for 2 h. Benzoxazine underwent ring-opening polymerization at 180℃. The curing kinetics of modified resin system was studied with non-isothermal DSC at different heating rates. The average activation energies of two reactions were calculated utilizing the Flynn-Wall-Ozawa method to be 65.27 kJ·mol-1 and 92.8 kJ·mol-1, respectively. Both curing reactions were found to be autocatalytic processes by the Friedman method, and the predicted curves from the autocatalytic model fitted well with those of experiments.%利用一种二胺型苯并嗪改性环氧酸酐体系。通过FT-IR和DSC分析了改性体系的固化机理。结果表明:共混树脂体系在固化时存在两个反应,首先是环氧树脂与足量的酸酐在咪唑作用下在100℃先开始固化,并在150℃固化2 h后固化完全,之后苯并嗪在180℃发生开环聚合。用非等温DSC法研究了该共混体系的固化动力学。采用 Flynn-Wall-Ozawa 方法求出了共混体系在固化时两个固化反应的活化能,分别为65.27 kJ·mol-1和92.8 kJ·mol-1,并利用Friedman方法判断了两个反应都是自催化反应,计算得到自催化模型曲线与实验曲线能较好地吻合。

  7. Characterization of maleic acid/anhydride copolymer films by low-rate dynamic liquid-fluid contact angle measurements using axisymmetric drop shape analysis.

    Science.gov (United States)

    Uhlmann, Petra; Skorupa, Sebastian; Werner, Carsten; Grundke, Karina

    2005-07-05

    Thin films of alternating maleic acid/anhydride copolymers (poly(octadecene-alt-maleic acid/anhydride), POMA; poly(propene-alt-maleic acid/anhydride), PPMA; poly(styrene-alt-maleic acid/anhydride), PSMA) were studied to unravel the influence of the comonomer characteristics in the backbone on the surface-energetic properties of the copolymer films in the dry state and in contact with aqueous solutions. Water contact angle measurements revealed a graduation of the wettability of the dry hydrolyzed and annealed copolymer films that was dependent on the comonomer unit. It ranged from moderately hydrophilic (PPMA, annealed gamma(sv) = 39.9 mJ/m2) to very hydrophobic (POMA, annealed, gamma(sv) = 18.4 mJ/m2) surfaces. Liquid-fluid contact angle measurements using captive air bubbles were performed in different aqueous media (pure water, phosphate-buffered saline, and 10(-)(3) M KCl of two different pH values (pH = 3 and pH = 10) to study the copolymer films in their hydrated states relevant for biointerfacial phenomena. It was found that the graduation of the wettability of the copolymer films in the dry state is overall maintained upon immersion in aqueous solutions. The dependence of the wettability on the pH value of the aqueous medium could be related to the (de)protonation of the carboxylic groups.

  8. 桐马酸酐与环氧树脂的非等温固化反应动力学%Non - isothermal curing kinetics of Tung - maleic anhydride and epoxy resin

    Institute of Scientific and Technical Information of China (English)

    黄坤; 夏建陵; 李梅; 林贵福; 连建伟

    2011-01-01

    The non- isothermal curing kinetics of Tung- maleic anhydride and epoxy resin E-51 blend with 1%DMP -30 by weight was studied by Má1ek method. The real curing process was stimulated well using mechanism equation (S)esták - Berggren. The active energy calculated by iso - conversion ratio method was 69. 78 kJ/mol. The pre -exponential factor A was 4. 567 × 108 min -1 and the values of n and m were 1. 082 and O. 456, respectively.Based on the curing kinetic equation obtained, the calculated curing time of the system with 98% conversion rate was 115 minutes at the curing temperature 137. 05 ℃.%采用Málek法对桐马酸酐与双酚A环氧树脂E-51体系(含有1%质最分数的DMP-30)的非等温固化反应动力学进行了研究.通过机理函数(S)esták-Berggren方程很好地模拟了真实的固化反应过程.等转化率法求得反应活化能为69.78 kJ/mol.指前因子A的值为4.567×108min-1,n和m的值分别为1.082和0.456.根据得到的同化动力学方程计算可知,在固化温度为137.05℃时达到98%固化度的固化时间为115 min.

  9. EFFECT OF ACIDITY ON ACID-SENSITIVE UV CURING SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Qi-dao Chen; Bing Wu; Xiao-yin Hong

    1999-01-01

    By using diphenyliodonium salts with different counterions as photo acid generators (PAGs), the effect of acidity on ring-opening polymerization of epoxy monomers and polycondensation of polyol with hexamethoxymethyl melamine (HMMM) was studied. The result shows that the rate of ring-opening polymerization is evidently dependent on the acidity of the acid and strong photo-generated acid is required.However, there is a leveling effect in the polycondensation system; if the photo-generated acid is stronger than protonated HMMM, the acidity does not obviously affect the polycondensation rate.

  10. Ferrocenecarboxylic anhydride: a redetermination

    Directory of Open Access Journals (Sweden)

    C. John McAdam

    2016-11-01

    Full Text Available The title molecule, [Fe2(C5H52(C12H8O3], briefly reported previously [Zhang (2015. Private Communication (CCDC reference 1056736. CCDC, Cambridge, England], comprises two ferrocenyl units connected by an acid anhydride bridge. Both ferrocene units have near coplanar [dihedral angles between the ring planes = 2.84 (4 and 1.74 (13°] and eclipsed [pseudo torsion angles = 6.3 (2 and 5.1 (2°] cyclopentadienyl (Cp rings. A twist through the anhydride linkage results in a dihedral angle of 73.81 (8° between the two substituted Cp rings planes. An intramolecular C—H...O hydrogen bond is also found. In the crystal, C—H...O hydrogen bonds link the molecules into a three-dimensional network.

  11. Investigation of the ageing effects on phenol-urea-formaldehyde binder and alkanol amine-acid anhydride binder coated mineral fibres

    DEFF Research Database (Denmark)

    Zafar, Ashar; Schjødt-Thomsen, Jan; Sodhi, R.

    2013-01-01

    . Principal Component Analysis (PCA) was applied on the positive and negative ToF-SIMS spectra of the PUF binder coated mineral fibres, showing a decrease in the concentration of the nitrogen containing peaks during ageing. This decrease was attributed to the depolymerisation of the binder due to hydrolysis......Phenol-Urea-Formaldehyde (PUF) binder coated mineral fibres' mechanical properties have been observed to degrade during ageing at elevated temperatures and humidity, while alkanol amine-acid anhydride binder based mineral fibres exhibited better ageing properties for same duration of ageing. X......-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were employed to identify the chemical changes occurring in the PUF binder coated mineral fibres and alkanol amine-acid anhydride binder coated mineral fibres during that ageing. The samples were aged in a climate...

  12. STUDY OF CARBONYLATION OF METHANOL TO ACETIC ACID AND ACETIC ANHYDRIDE OVER A BIDENTATE POLYMER BOUND CIS-DICARBONYLRHODIUM COMPLEX AS CATALYST

    Institute of Scientific and Technical Information of China (English)

    WANG Xiaojun; LIU Zhongyang; PAN Pinglai; YUAN Guoqing

    1996-01-01

    Copolymer of 2-vinylpyridine and vinylacetate coordinated with dicarbonylrhodium used as a catalyst for carbonylation of methanol to acetic acid and anhydride has been studied. The structural characteristics of the copolymer ligand and complex, and the influences of the reaction conditions on the carbonylation catalyzed by this polymer complex have been investigated. In comparison with small molecule catalyst of Rh complex, the bidentate copolymer coordinated complex has better thermal stability. The reaction mechanism of the carbonylation reaction is also illustrated.

  13. Development of a guided bone regeneration device using salicylic acid-poly(anhydride-ester) polymers and osteoconductive scaffolds.

    Science.gov (United States)

    Mitchell, Ashley; Kim, Brian; Cottrell, Jessica; Snyder, Sabrina; Witek, Lukasz; Ricci, John; Uhrich, Kathryn E; O'Connor, J Patrick

    2014-03-01

    Successful repair of craniofacial and periodontal tissue defects ideally involves a combined therapy that includes inflammation modulation, control of soft tissue infiltration, and bone regeneration. In this study, an anti-inflammatory polymer, salicylic acid-based poly(anhydride-ester) (SAPAE) and a three-dimensional osteoconductive ceramic scaffold were evaluated as a combined guided bone regeneration (GBR) system for concurrent control of inflammation, soft tissue ingrowth, and bone repair in a rabbit cranial defect model. At time periods of 1, 3, and 8 weeks, five groups were compared: (1) scaffolds with a solid ceramic cap (as a GBR structure); (2) scaffolds with no cap; (3) scaffolds with a poly(lactide-glycolide) cap; (4) scaffolds with a slow release SAPAE polymer cap; and (5) scaffolds with a fast release SAPAE polymer cap. Cellular infiltration and bone formation in these scaffolds were evaluated to assess inflammation and bone repair capacity of the test groups. The SAPAE polymers suppressed inflammation and displayed no deleterious effect on bone formation. Additional work is warranted to optimize the anti-inflammatory action of the SAPAE, GBR suppression of soft tissue infiltration, and stimulation of bone formation in the scaffolds and create a composite device for successful repair of craniofacial and periodontal tissue defects.

  14. In Vivo Evaluation of Nerve Guidance Conduits Comprised of a Salicylic Acid-based Poly(anhydride-ester) Blend

    Science.gov (United States)

    Lee, Yong Soo

    Unlike the central nervous system, peripheral nervous system can regenerate from injury. However, without surgical intervention, the results are often poor. Autologous nerve grafting is the golden standard for repairing peripheral nerve injury; but limited donor availability and donor site morbidity led researchers to seek alternative methods. Among the many alternative treatment options, synthetic nerve guidance conduits (NGCs) have been most actively developed. The goal of NGCs is to serve as a physical scaffold that aids the axonal regeneration process while preventing scar tissue formation that interferes with regeneration. Biocompatible and biodegradable NGCs would provide additional benefits: minimize foreign body reaction and avoid secondary surgeries to remove NGCs. We developed a unique NGC that incorporated the characteristics described above and can release an anti-inflammatory drug, salicylic acid. In this work, in vivo assays were performed to evaluate NGCs fabricated from a poly(anhydride-ester) blend. To further assist in the regeneration process, bovine native collagen type I hydrogel were inserted into the NGCs lumen which was then implanted in femoral nerve of mice for up to 16 weeks. These studies demonstrated in vivo biodegradability, biocompatibility, and axonal regeneration following an injury to the peripheral nerve. These studies provide greater insights into the importance of designing NGCs and how they aid in regeneration and functional recovery of subjects.

  15. Dimethylmaleic anhydride, a specific reagent for protein amino groups.

    Science.gov (United States)

    de la Escalera, S; Palacián, E

    1989-01-01

    The reagent dimethylmaleic anhydride does not cause a stable modification of thiol compounds under the conditions used for modification of protein amino groups, in contrast to maleic and monomethylmaleic anhydrides, which produce an irreversible modification of sulfhydryl groups. This behavior and the low reactivity toward hydroxyamino acid residues, shown in a previous work, make dimethylmaleic anhydride a specific reagent for protein amino groups.

  16. Electron beam curing of dimer acid-based urethane acrylates for pressure sensitive adhesives

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Takashi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; Takeda, Satoe; Shiraishi, Katsutoshi

    1995-03-01

    Polyester urethane diacrylate prepolymers prepared from dimer acids (DUA) were cured with low energy electron beams to investigate adhesive properties of cured films. Among various type monomers added, monofunctional methacrylates such as isobornyl methacrylate (IBXMA) were effective for higher peel strength cured films although the dose-to-cure for the mixtures increased to 100 kGy or more. The increase in the molecular weight of prepolymers resulted in lower curing rates but higher peel strength. Aging tests up to 80degC for four weeks proved good stability in peel strength of the stored products. (author).

  17. Thermosets of epoxy monomer from Tung oil fatty acids cured in two synergistic ways

    Science.gov (United States)

    A new epoxy monomer from tung oil fatty acids, glycidyl ester of eleostearic acid (GEEA), was synthesized and characterized by 1H-NMR and 13C-NMR spectroscopy. Differential scanning calorimetry analysis (DSC) and FT-IR were utilized to investigate the curing process of GEEA cured by both dienophiles...

  18. Synthetic studies of coumarin derivatives from o-hydroxybenzophenones with phenylacetic acid and acetic anhydride

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Soon Hee; Yang, Sung Yun [Ewha Womans Univ., Seoul (Korea, Republic of)

    1999-02-01

    The 8 coumarin derivatives have been synthesized from 8 starting materials(2-hydroxy-benzophenone, 2,2'-dihydroxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-5-methylbenzophenone, 5-chloro-2-hydroxy-4-methylbenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-4'-dimethoxybenzophenone) with phenylacetic acid and Ac{sub 2}O/TEA in acetone at reflux temperature. The ratio of o-hydroxybenzophenone, phenylacetic acid, Ac{sub 2}O and TEA is 1:1:8:8 in acetone. Our results showed higher products yields of coumarin derivatives than Shama and Ray's method in previous papers. A new intermediate form was proposed to our mechanism of coumarin synthetic method.

  19. Solvent effects in acid-catalyzed dehydration of the Diels-Alder cycloadduct between 2,5-dimethylfuran and maleic anhydride

    Science.gov (United States)

    Salavati-fard, Taha; Caratzoulas, Stavros; Doren, Douglas J.

    2017-03-01

    Dehydration of the cycloadduct produced from the Diels-Alder reaction between 2,5-dimethylfuran and maleic anhydride to 3,6-dimethylphthalic anhydride exemplifies an important step in producing platform chemicals from biomass. The mechanisms of dehydration and catalytic effects of Lewis and Brønsted acids are investigated with density functional theory. The uncatalyzed reaction has a very high activation barrier (68.7 kcal/mol) in the gas phase and it is not significantly affected by solvation. With a Lewis acid catalyst, modeled as an alkali ion, the activation barriers are reduced, but intermediates are also stabilized. The net effect in vacuum is that the energetic span, or apparent activation energy of the catalytic cycle, is 77.9 kcal/mol, even higher than the barrier in the uncatalyzed case. In solution, however, the energetic span is reduced by as much as 20 kcal/mol, due to differences in the solvation energy of the transition states and intermediates. In the case of a Brønsted acid catalyst, modeled as a proton, the gas phase transition state energies are reduced even more than in the Lewis acid case, and there is no strong stabilization of the intermediates. The energetic span in vacuum is only 13.8 kcal/mol and is reduced even further in solution. Brønsted acid catalysis appears to be the preferred mechanism for dehydration of this cycloadduct. Since the Diels-Alder reaction that produced the molecule has previously been shown to be catalyzed by Brønsted acids, this suggests that a single catalyst could be used to accelerate both steps.

  20. Critical behavior of anhydride cured epoxies

    Science.gov (United States)

    Trappe, V.; Richtering, W.; Burchard, W.

    1992-07-01

    Critical behavior was studied with a crosslinking system obtained by living anionic polymerization, where the primary chain length was kept constant and the crosslinking density was varied. Gelation was found at a critical ratio of crosslinker per chain X_c=0.884± 0.004. Different samples from the pre gel region were studied by dynamic and static light scattering in dilute solution and oscillatory rheology in melt. The exponents γ = 1.75± 0.38 and ν = 0.98± 0.19, determined from M_w and R_g dependence on (X_c-X), are in accordance with three dimensional percolation theory. The distribution of diffusion coefficients obtained by inverse Laplace transformation of the time correlation function shows power law behavior in a limited interval, from which an exponent tau = 2.17± 0.03 is derived. Rheological measurements show a systematic change of G^{prime}(ω) and G''(ω) from typical liquid to the critical gel behavior, where tan δ = G''(ω)/G^{prime}(ω) becomes frequency independent.

  1. Effect of curing modes of dual-curing core systems on microtensile bond strength to dentin and formation of an acid-base resistant zone.

    Science.gov (United States)

    Li, Na; Takagaki, Tomohiro; Sadr, Alireza; Waidyasekera, Kanchana; Ikeda, Masaomi; Chen, Jihua; Nikaido, Toru; Tagami, Junji

    2011-12-01

    To evaluate the microtensile bond strength (μTBS) and acid-base resistant zone (ABRZ) of two dualcuring core systems to dentin using four curing modes. Sixty-four caries-free human molars were randomly divided into two groups according to two dual-curing resin core systems: (1) Clearfil DC Core Automix; (2) Estelite Core Quick. For each core system, four different curing modes were applied to the adhesive and core resin: (1) dual-cured and dual-cured (DD); (2) chemically cured and dual-cured (CD); (3) dual-cured and chemically cured (DC); (4) chemically cured and chemically cured (CC). The specimens were sectioned into sticks (n = 20 for each group) for the microtensile bond test. μTBS data were analyzed using two-way ANOVA and the Dunnett T3 test. Failure patterns were examined with scanning electron microscopy (SEM) to determine the proportion of each mode. Dentin sandwiches were produced and subjected to an acid-base challenge. After argon-ion etching, the ultrastructure of ABRZ was observed using SEM. For Clearfil DC Core Automix, the μTBS values in MPa were as follows: DD: 29.1 ± 5.4, CD: 21.6 ± 5.6, DC: 17.9 ± 2.8, CC: 11.5 ± 3.2. For Estelite Core Quick, they were: DD: 48.9 ±5.7, CD: 20.5 ± 4.7, DC: 41.4 ± 8.3, CC: 19.1 ± 6.0. The bond strength was affected by both material and curing mode, and the interaction of the two factors was significant (p core systems affects bond strength to dentin, but has no significant effect on the formation of ABRZ.

  2. Preparation, characterization and thermal properties of styrene maleic anhydride copolymer (SMA)/fatty acid composites as form stable phase change materials

    Energy Technology Data Exchange (ETDEWEB)

    Sari, Ahmet; Alkan, Cemil; Karaipekli, Ali; Oenal, Adem [Department of Chemistry, Gaziosmanpasa University, 60240, Tokat (Turkey)

    2008-02-15

    Fatty acids such as stearic acid (SA), palmitic acid (PA), myristic acid (MA) and lauric acid (LA) are promising phase change materials (PCMs) for latent heat thermal energy storage (LHTES) applications, but high cost is the major drawback of them, limiting their utility area in thermal energy storage. The use of fatty acids as form stable PCMs will increase their feasibilities in practical applications due to the reduced cost of the LHTES system. In this regard, a series of styrene maleic anhydride copolymer (SMA)/fatty acid composites, SMA/SA, SMA/PA, SMA/MA, and SMA/LA, were prepared as form stable PCMs by encapsulation of fatty acids into the SMA, which acts as a supporting material. The encapsulation ratio of fatty acids was as much as 85 wt.% and no leakage of fatty acid was observed even when the temperature of the form stable PCM was over the melting point of the fatty acid in the composite. The prepared form stable composite PCMs were characterized using optic microscopy (OM), viscosimetry and Fourier transform infrared (FT-IR) spectroscopy methods, and the results showed that the SMA was physically and chemically compatible with the fatty acids. In addition, the thermal characteristics such as melting and freezing temperatures and latent heats of the form stable composite PCMs were measured by using the differential scanning calorimetry (DSC) technique, which indicated they had good thermal properties. On the basis of all the results, it was concluded that form stable SMA/fatty acid composite PCMs had important potential for practical LHTES applications such as under floor space heating of buildings and passive solar space heating of buildings by using wallboard, plasterboard or floors impregnated with a form stable PCM due to their satisfying thermal properties, easy preparation in desired dimensions, direct usability without needing additional encapsulation thereby eliminating the thermal resistance caused by the shell and, thus, reducing the cost of

  3. Inlfuence of Curing Accelerators on the Imidization of Polyamic Acids and Properties of Polyimide Films

    Institute of Scientific and Technical Information of China (English)

    XU Yong; ZHAO Anlu; WANG Xinlong; XUE Hui; LIU Feilong

    2016-01-01

    In order to lower the imidization temperature of polyamic acids (PAA), the catalytic activities of the curing agents p-hydroxybenzoic acid (PHA), quinoline (QL), benzimidazole (BI), benzotriazole (BTA), triethylamine (Et3N) and 1, 8-diazabicyclo [5.4.0]undec-7-ene (DBU) were investigated in the process of thermal imidization of PAA. In addition, the effect of these various curing agents on the thermal stabilities and mechanical properties of the resultant polyimide (PI) iflms was determined. Quinoline was found to be an effective curing accelerator in the use of two-step method for synthesizing PI. Due to its moderate base strength, low steric crowding effect and moderate boiling point, quinoline could not only accelerate PAA to achieve imidization completely at 180℃, but also maintain the mechanical properties and thermal stability of the ordinary PI iflm. Any residual quinoline could be removed from PI iflms by heating at 250℃ for 4 h.

  4. Effect of Solvent and Acid-Base on Palladium(ll)-catalyzed Dicarbonylation of Terminal Acetylenes: a General, Efficient andStereoselective Synthesis of Maleic Diesters and Maleic Anhydrides

    Institute of Scientific and Technical Information of China (English)

    JIANG, Huan-Feng; LI, JiN-Heng; CHEN, Ming-Cai

    2001-01-01

    The productions of maleic diesters and maleic anhydrises depend on the effect of solvint and acid-bade of solvent and acid-base in palladium-catalyzed dicarbonylation of terminal acetylenes. For primaryand secondary alcohol in benzene.only maleic diesters wereobtained stereospecifically from the sicabonylation ofacetylenes in the presence of PdCl2,and NaHCO3.For tERTIARy alcohols,maleic anhydrides were synthesized selectively.

  5. Microwave Characterization of Propiolic Sulfuric Anhydride and Two Conformers of Acrylic Sulfuric Anhydride

    Science.gov (United States)

    Smith, CJ; Huff, Anna; Mackenzie, Becca; Leopold, Ken

    2017-06-01

    Sulfur trioxide reacts with propiolic acid and acrylic acid to form propiolic sulfuric anhydride (HC\\equivC-COOSO_{2}OH) and acrylic sulfuric anhydride (H_{2}C=CH-COOSO_{2}OH), respectively. Both species have been observed by chirped-pulse and conventional cavity microwave spectroscopy. In the case of acrylic acid, two conformers derived from the cis and trans form of the acid have been observed. The reaction mechanism and energetics are investigated by density functional theory and CCSD calculations. These results add to a growing body of evidence that establishes carboxylic sulfuric anhydrides, RCOOSO_{2}OH, as a class of molecules formed readily from SO_{3} + RCOOH in the gas phase and which, therefore, may be of significance in the nucleation and growth of atmospheric aerosol particles.

  6. Method for epoxy foam production using a liquid anhydride

    Science.gov (United States)

    Celina, Mathias [Albuquerque, NM

    2012-06-05

    An epoxy resin mixture with at least one epoxy resin of between approximately 50 wt % and 100 wt %, an anhydride cure agent of between approximately 0 wt % and approximately 50 wt %, a tert-butoxycarbonyl anhydride foaming agent of between proximately 0.1-20 wt %, a surfactant and an imidazole or similar catalyst of less than approximately 2 wt %, where the resin mixture is formed from at least one epoxy resin with a 1-10 wt % tert-butoxycarbonyl anhydride compound and an imidazole catalyst at a temperature sufficient to keep the resin in a suitable viscosity range, the resin mixture reacting to form a foaming resin which in the presence of an epoxy curative can then be cured at a temperature greater than 50.degree. C. to form an epoxy foam.

  7. Effect of maleic anhydride-aniline derivative buffer layer on the properties of flexible substrate heterostructures: Indium tin oxide/nucleic acid base/metal

    Energy Technology Data Exchange (ETDEWEB)

    Stanculescu, A., E-mail: sanca@infim.ro [National Institute of Materials Physics, 105 bis Atomistilor Street, P.O. Box MG-7, 077125, Bucharest-Magurele (Romania); Socol, M. [National Institute of Materials Physics, 105 bis Atomistilor Street, P.O. Box MG-7, 077125, Bucharest-Magurele (Romania); Socol, G.; Mihailescu, I.N. [National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG-36, 077125, Bucharest-Magurele (Romania); Girtan, M. [Laboratoire de Photonique d' Angers, Universite d' Angers, 2, Bd. Lavoisier, 49045, Angers (France); Preda, N. [National Institute of Materials Physics, 105 bis Atomistilor Street, P.O. Box MG-7, 077125, Bucharest-Magurele (Romania); Albu, A.-M. [Department of Polymer Science, University ' Politehnica' of Bucharest, Bucharest (Romania); Stanculescu, F. [University of Bucharest, Faculty of Physics, Str. Atomistilor nr.405, P.O. Box MG-11, Bucharest-Magurele, 077125 (Romania)

    2011-12-01

    This paper presents some investigations on the properties of guanine (G) and cytosine (C) based heterostructures deposited on flexible substrates. The effects of two types of maleic anhydride-aniline derivatives (maleic anhydride-cyano aniline or maleic anhydride-2,4 dinitroaniline) buffer layer, deposited between indium tin oxide and (G) or (C) layer, on the optical and electrical properties of the heterostructures have been identified. The heterostructures containing a film of maleic anhydride-2,4 dinitroaniline have shown a good transparency and low photoluminescence in visible range. This buffer layer has determined an increase in the conductance only in the heterostructures based on (G) and (C) deposited on biaxially-oriented polyethylene terephthalate substrate.

  8. Blending of Low-Density Polyethylene and Poly-Lactic Acid with Maleic Anhydride as A Compatibilizer for Better Environmentally Food-Packaging Material

    Science.gov (United States)

    Setiawan, A. H.; Aulia, F.

    2017-05-01

    The common conventional food packaging materialsare using a thin layer plastic or film, which is made of a synthetic polymer, such as Low-Density Poly Ethylene (LDPE). However, the use of these polymers hasan adverse impact on the environment, because the synthetic polymersare difficult to degrade naturally. Poly-Lactic Acid (PLA) is a biodegradable polymer that can be substituted to synthetic polymers. Since LDPE and PLA have a difference in polarity, therefore the first step of research is to graft them with maleic anhydride (MAH) for increasing the properties of its miscibility. The interaction between them is confirmed by FTIR; whereas the environment issueis characterized by the water adsorption and biodegradability. The FTIR spectra indicated that there had been an interaction between LDPE and MAH and LDPE/LDPE-g-MAH/PLA blend. Increasing PLA content in the blend affected to the increasing in their water absorption and biodegradable. Poly-blend with 20% PLA content was the optimum composition for environmentally food packaging.

  9. Enhancement of mechanical properties, microstructure, and antimicrobial activities of zein films cross-linked using succinic anhydride, eugenol, and citric Acid.

    Science.gov (United States)

    Khalil, Ashraf A; Deraz, Sahar F; Elrahman, Somia Abd; El-Fawal, Gomaa

    2015-08-18

    Zein constitutes about half of the endosperm proteins in corn. Recently, attempts have been made to utilize zein for food coatings and biodegradable materials, which require better physical properties, using chemical modification of zein. In this study, zein proteins were modified using citric acid, succinic anhydride, and eugenol as natural cross-linking agents in the wet state. The cross-linkers were added either separately or combined in increment concentrations (0.1, 0.2, 0.3, and 0.4%). The effects of those agents on the mechanical properties, microstructure, optical properties, infrared (IR) spectroscopy, and antibacterial activities of zein were investigated. The addition of cross-linking agents promoted changes in the arrangement of groups in zein film-forming particles. Regarding the film properties, incorporation of cross-linking agents into zein films prepared in ethanol resulted in two- to three-fold increases in tensile strength (TS) values. According to the Fourier-transform infrared (FTIR) spectra and Hunter parameters there were no remarkable changes in the structure and color of zein films. Transparency of zein films was decreased differentially according to the type and cross-linker concentration. The mechanical and optical properties of zein films were closely related to their microstructure. All cross-linked films showed remarkable antibacterial activities against Bacillus cereus ATCC 49064 and Salmonella enterica ATCC 25566. Food spoilage and pathogenic bacteria were affected in a film-dependent manner. Our experimental results show that even with partial cross-linking the mechanical properties and antipathogen activities of zein films were significantly improved, which would be useful for various industrial applications.

  10. Salicylic acid-based poly(anhydride-ester) nerve guidance conduits: Impact of localized drug release on nerve regeneration.

    Science.gov (United States)

    Lee, Yong S; Griffin, Jeremy; Masand, Shirley N; Shreiber, David I; Uhrich, Kathryn E

    2016-04-01

    Nerve guidance conduits (NGCs) can serve as physical scaffolds aligning and supporting regenerating cells while preventing scar tissue formation that often interferes with the regeneration process. Numerous studies have focused on functionalizing NGCs with neurotrophic factors, for example, to support nerve regeneration over longer gaps, but few directly incorporate therapeutic agents. Herein, we fabricated NGCs from a polyanhydride comprised of salicylic acid (SA), a nonsteroidal anti-inflammatory drug, then performed in vitro and in vivo assays. In vitro studies included cytotoxicity, anti-inflammatory response, and NGC porosity measurements. To prepare for implantation, type I collagen hydrogels were used as NGC luminal fillers to further enhance the axonal regeneration process. For the in vivo studies, SA-NGCs were implanted in femoral nerves of mice for 16 weeks and evaluated for functional recovery. The SA-based NGCs functioned as both a drug delivery vehicle capable of reducing inflammation and scar tissue formation because of SA release as well as a tissue scaffold that promotes peripheral nerve regeneration and functional recovery.

  11. Adenoviral transduction of human acid sphingomyelinase into neo-angiogenic endothelium radiosensitizes tumor cure.

    Directory of Open Access Journals (Sweden)

    Branka Stancevic

    Full Text Available These studies define a new mechanism-based approach to radiosensitize tumor cure by single dose radiotherapy (SDRT. Published evidence indicates that SDRT induces acute microvascular endothelial apoptosis initiated via acid sphingomyelinase (ASMase translocation to the external plasma membrane. Ensuing microvascular damage regulates radiation lethality of tumor stem cell clonogens to effect tumor cure. Based on this biology, we engineered an ASMase-producing vector consisting of a modified pre-proendothelin-1 promoter, PPE1(3x, and a hypoxia-inducible dual-binding HIF-2α-Ets-1 enhancer element upstream of the asmase gene, inserted into a replication-deficient adenovirus yielding the vector Ad5H2E-PPE1(3x-ASMase. This vector confers ASMase over-expression in cycling angiogenic endothelium in vitro and within tumors in vivo, with no detectable enhancement in endothelium of normal tissues that exhibit a minute fraction of cycling cells or in non-endothelial tumor or normal tissue cells. Intravenous pretreatment with Ad5H2E-PPE1(3x-ASMase markedly increases SDRT cure of inherently radiosensitive MCA/129 fibrosarcomas, and converts radiation-incurable B16 melanomas into biopsy-proven tumor cures. In contrast, Ad5H2E-PPE1(3x-ASMase treatment did not impact radiation damage to small intestinal crypts as non-dividing small intestinal microvessels did not overexpress ASMase and were not radiosensitized. We posit that combination of genetic up-regulation of tumor microvascular ASMase and SDRT provides therapeutic options for currently radiation-incurable human tumors.

  12. 1-Butyl-3-methylimidazolium Salts as New Catalysts to Produce Epoxy-anhydride Polymers with Improved Properties

    OpenAIRE

    Mikhail S. Fedoseev; Gruzdev, Matvey S.; Lubov F. Derzhavinskaya

    2014-01-01

    We report the curing process of epoxy oligomers by using isomethyltetrahydrophthalic anhydride catalyzed with 1-butyl-3-methylimidazolium salts. Catalytic action has been ascertained to be dependent on the nature of anion. Salts with (Br-) and (PO4-) anions appeared to be most active. Formation of salt adducts with epoxy resin and anhydride is shown. Polymers having higher values of strength and glass transition temperature—as compared with similar epoxy systems cured in the presence of terti...

  13. Inhibition of Listeria monocytogenes by propionic acid-based ingredients in cured deli-style Turkey.

    Science.gov (United States)

    Glass, Kathleen A; McDonnell, Lindsey M; Von Tayson, Roxanne; Wanless, Brandon; Badvela, Mani

    2013-12-01

    Listeria monocytogenes growth can be controlled on ready-to-eat meats through the incorporation of antimicrobial ingredients into the formulation or by postlethality kill steps. However, alternate approaches are needed to provide options that reduce sodium content but maintain protection against pathogen growth in meats after slicing. The objective of this study was to determine the inhibition of L. monocytogenes by propionic acid-based ingredients in high-moisture, cured turkey stored at 4 or 7°C. Six formulations of sliced, cured (120 ppm of NaNO2 ), deli-style turkey were tested, including control without antimicrobials, 3.2% lactate-diacetate blend (LD), 0.4% of a liquid propionate-benzoate-containing ingredient, or 0.3, 0.4, and 0.5% of a liquid propionate-containing ingredient. Products were inoculated with 5 log CFU L. monocytogenes per 100-g package (3 log CFU/ml rinsate), vacuum-sealed, and stored at 4 or 7°C for up to 12 weeks; and populations were enumerated by plating on modified Oxford agar. As expected, the control without antimicrobials supported rapid growth, with >2 log average per ml rinsate increase within 4 weeks of storage at 4°C, whereas growth was observed at 6 weeks for the LD treatment. For both replicate trials, all treatments that contained liquid propionate or propionate-benzoate limited L. monocytogenes growth to an increase of 1-log increase) was observed in individual samples for all propionate-containing treatments at weeks 10, 11, and 12. As expected, L. monocytogenes grew more rapidly when products were stored at 7°C, but trends in relative inhibition were similar to those observed at 4°C. These results verify that propionate-based ingredients inhibit growth of L. monocytogenes on sliced, high-moisture, cured turkey and can be considered as an alternative to reduce sodium-based salts while maintaining food safety.

  14. Catalytic actions of alkaline salts in reactions between 1,2,3,4-butanetetracarboxylic acid and cellulose: II. Esterification.

    Science.gov (United States)

    Ji, Bolin; Tang, Peixin; Yan, Kelu; Sun, Gang

    2015-11-05

    1,2,3,4-Butanetetracarboxylic acid (BTCA) reacts with cellulose in two steps with catalysis of alkaline salts such as sodium hypophosphite: anhydride formation and esterification of anhydride with cellulose. The alkali metal ions were found effective in catalyzing formation of BTCA anhydride in a previous report. In this work, catalytic functions of the alkaline salts in the esterification reaction between BTCA anhydride and cellulose were investigated. Results revealed that acid anions play an important role in the esterification reaction by assisting removal of protons on intermediates and completion of the esterification between cellulose and BTCA. Besides, alkaline salts with lower pKa1 values of the corresponding acids are more effective ones for the reaction since addition of these salts could lead to lower pH values and higher acid anion concentrations in finishing baths. The mechanism explains the results of FTIR and wrinkle recovery angles of the fabrics cured under different temperatures and times.

  15. Eliminación del plomo por curado casero Lead elimination by traditional acidic curing

    Directory of Open Access Journals (Sweden)

    Luisa Torres-Sánchez

    1999-11-01

    Full Text Available Objetivo. Evaluar el curado ácido como medida preventiva para reducir el contenido de plomo en vasijas de barro vidriadas. Material y métodos. En 27 vasijas de barro procedentes de cuatro estados de México se determinó, mediante espectrofotometría de absorción atómica, el nivel de plomo residual, después de cuatro lavados con ácido acético al 3%. Resultados. El contenido de plomo en el ácido acético utilizado para lavar las vasijas disminuyó proporcionalmente con el número de lavados, aunque se conservó por arriba de los niveles permisibles (2.5-7.0 p.p.m.. Conclusiones. El curado ácido de piezas de barro no es una medida preventiva útil para reducir la exposición a plomo.Objective. To evaluate traditional acidic curing as a preventive method for reducing lead content of glazed ceramic ware. Material and methods. In 27 ceramic ware pieces from four states in Mexico, the level of residual lead was determined through atomic absorption spectrophotometry after four washings with acetic acid 3%. Results. The lead content of the vinegar washing diminished proportionally with the number of washings, although it remained highly above the permissible levels of this metal (2.5-7.0 p.p.m.. Conclusions. Traditional acidic curing of glazed ceramic ware is not a useful preventive measure for reducing lead exposure.

  16. 顺酐加氢产物精制丁二酸的工艺研究%Purifying Technology of Succinic Acid from Product of M aleic Anhydride Hydrogenation

    Institute of Scientific and Technical Information of China (English)

    田丹; 霍稳周; 吕清林; 乔凯; 孟宪革; 李守田

    2013-01-01

    The process of succinic acid purifying from product of maleic anhydride hydrogenation was studied .The effects of distillation pressure ,temperature and reflux ratio on the process of vacuum distillation were investigated ;it also discussed the effects of reaction time and molar ratio of water to succinic anhydride on hydrolysis ;meanwhile ,the effect of temperature on the crystallization was concerned . The pure succinic acid was acquired through vacuum distillation , hydrolyzation and crystallization .The process conditions of purifying technology of succinic acid were detemined .The results show that the yield of succinic acid is more than 70% and purity of the product can reach 99 .5% even more under the conditions of vaccum distillation temperature 75~85 ℃ ,distillation pressure 200~300 Pa ,hydrolysis temperature 100 ℃ ,molar ratio of water to succinic anhydride 4~5 ,reaction time 2 h .%对顺酐加氢产物精制丁二酸的工艺进行了研究。考察了蒸馏压力、蒸馏温度及回流比对减压蒸馏过程的影响;考察了水解时间、水与酸酐物质的量比对水解过程的影响;考察了结晶温度对结晶过程的影响。确定了顺酐加氢产物减压蒸馏后水解结晶精制丁二酸的方法及工艺条件。结果表明,在减压蒸馏温度为75~85℃,蒸馏压力为200~300 Pa ,水解温度为100℃,水与丁二酸酐物质的量比为4~5,水解时间为2 h的条件下,得到的丁二酸产品收率≥70%,纯度≥99.5%。

  17. Hydrogen bonding in cyclic imides and amide carboxylic acid derivatives from the facile reaction of cis-cyclohexane-1,2-carboxylic anhydride with o- and p-anisidine and m- and p-aminobenzoic acids.

    Science.gov (United States)

    Smith, Graham; Wermuth, Urs D

    2012-09-01

    The structures of the open-chain amide carboxylic acid rac-cis-2-[(2-methoxyphenyl)carbamoyl]cyclohexane-1-carboxylic acid, C(15)H(19)NO(4), (I), and the cyclic imides rac-cis-2-(4-methoxyphenyl)-3a,4,5,6,7,7a-hexahydroisoindole-1,3-dione, C(15)H(17)NO(3), (II), chiral cis-3-(1,3-dioxo-3a,4,5,6,7,7a-hexahydroisoindol-2-yl)benzoic acid, C(15)H(15)NO(4), (III), and rac-cis-4-(1,3-dioxo-3a,4,5,6,7,7a-hexahydroisoindol-2-yl)benzoic acid monohydrate, C(15)H(15)NO(4)·H(2)O, (IV), are reported. In the amide acid (I), the phenylcarbamoyl group is essentially planar [maximum deviation from the least-squares plane = 0.060 (1) Å for the amide O atom] and the molecules form discrete centrosymmetric dimers through intermolecular cyclic carboxy-carboxy O-H···O hydrogen-bonding interactions [graph-set notation R(2)(2)(8)]. The cyclic imides (II)-(IV) are conformationally similar, with comparable benzene ring rotations about the imide N-C(ar) bond [dihedral angles between the benzene and isoindole rings = 51.55 (7)° in (II), 59.22 (12)° in (III) and 51.99 (14)° in (IV)]. Unlike (II), in which only weak intermolecular C-H···O(imide) hydrogen bonding is present, the crystal packing of imides (III) and (IV) shows strong intermolecular carboxylic acid O-H···O hydrogen-bonding associations. With (III), these involve imide O-atom acceptors, giving one-dimensional zigzag chains [graph-set C(9)], while with the monohydrate (IV), the hydrogen bond involves the partially disordered water molecule which also bridges molecules through both imide and carboxy O-atom acceptors in a cyclic R(4)(4)(12) association, giving a two-dimensional sheet structure. The structures reported here expand the structural database for compounds of this series formed from the facile reaction of cis-cyclohexane-1,2-dicarboxylic anhydride with substituted anilines, in which there is a much larger incidence of cyclic imides compared to amide carboxylic acids.

  18. Fatty acid profile, total cholesterol, vitamin content, and TBARS value of turkey breast muscle cured with the addition of lycopene.

    Science.gov (United States)

    Skiepko, N; Chwastowska-Siwiecka, I; Kondratowicz, J; Mikulski, D

    2016-05-01

    The aim of this study was to determine the effect of lycopene addition for curing turkey meat on the profile of fatty acids, total cholesterol, vitamin content, and the TBARS of the final products. The analyzed material comprised 64 breast muscles, of which 16 (RBM) were immediately transported to a laboratory. Another 16 (UBM) were heat treated in a convection steam oven, and 32 muscles were cured for 3 days in two types of curing mixture: without (CBM) and with (CBM+Lyc) tomato peel extract standardized for 5% lycopene content. After completed curing, samples were steamed and grilled under the same conditions as raw samples. Statistical analysis demonstrated the highest (P≤0.01) mean content of vitamin A (0.07 μg/g) in chilled muscles. The content of vitamin E was lower (P≤0.01) in UBM samples than in CBM+Lyc and RBM. The TBARS value was the lowest (P≤0.01) in RBM muscles (0.35 mg MDA/kg of meat). Although there were no differences between products, but lower TBARS were found in CBM+Lyc samples. The content of cholesterol was higher (P≤0.01) in CBM+Lyc products than in the RBM and UBM. RBM samples contained (P≤0.01) the lowest amount of saturated, monounsaturated, and hypercholesterolemic fatty acids, and the highest of unsaturated, polyunsaturated, and hypocholesterolemic fatty acids. CBM+Lyc samples contained (P≤0.01) less hypercholesterolemic and more hypocholesterolemic fatty acids than CBM group. Higher (P≤0.01) unsaturated/saturated and hypocholesterolemic/hypercholesterolemic fatty acid ratios were also found in CBM+Lyc products. The study demonstrated that the used processing technology caused reduction (P≤0.01) of n-3 and n-6 PUFA content. Findings suggest that the addition of lycopene in the process of meat curing and heat treatment in meat industry do not change the content of vitamins and cholesterol or alter the TBARS value in turkey meat products. Nevertheless, lycopene can be used to increase the content of essential

  19. Physical characteristics of cold cured anthracite/coke breeze briquettes prepared from a coal tar acid resin

    Energy Technology Data Exchange (ETDEWEB)

    Thoms, L.J.; Snape, C.E.; Taylor, D. [University of Strathclyde, Glasgow (United Kingdom). Dept. of Pure and Applied Chemistry

    1999-11-01

    Phenolic resins were synthesised using the whole coal tar acid fraction of the oil from a low temperature carbonisation process. A series of briquettes were prepared using a number of coal tar acid concentrations, cured at ambient temperature with various concentrations of sulphuric acid and were subjected to a variety of physical tests. Excellent briquettes, in terms of mechanical strength, water-proofing characteristics and thermal degradation, were produced with both nominally 10 and 9% w/w resole solution and acid concentrations down to 1.8 M, corresponding to sulphur addition in the briquettes of ca. 0.2% w/w. Briquettes bound with 8% w/w resole solution, however, required stronger acid concentrations to satisfy the test conditions. When the briquettes were combusted up to 850{degree}C, they retained their core shape after 70% weight loss. 16 refs., 4 figs., 4 tabs.

  20. Application of acid-treated yeast cell wall (AYC) as a pharmaceutical additive. II: effects of curing on the medicine release from AYC-coated tablets.

    Science.gov (United States)

    Yuasa, H; Kaneshige, J; Ozeki, T; Kasai, T; Eguchi, T; Ishiwaki, N

    2000-11-19

    Acid-treated yeast cell wall (AYC) was newly prepared by acidifying brewers' yeast cell wall. Core tablets containing 3% of acetaminophen (AAP) were coated with the AYC aqueous dispersion containing 5% (w/v) of AYC and 0.35% (w/v) of glycerol. The curing of AYC-coated tablets was performed at various curing periods of time and temperatures. The effects of curing on AAP release from AYC-coated tablets, the weight and thickness of the coated layer of AYC and the water sorption into the AYC-coated tablets were studied. The tensile strength and pore size distribution of the AYC cast film were measured. In the case of 60, 80, or 100 degrees C curing, AAP release from AYC-coated tablets showed a sigmoidal release profile with an initial lag time. The duration of the lag time increased with the increasing curing time and temperature, though the release rate after the lag time hardly changed. At 120 degrees C curing, the release rate after the lag time decreased with the increasing curing time and a sustained release was observed. The weight and thickness of the AYC-coated layer and the water sorption rate into AYC-coated tablets decreased with the increasing curing time and temperature. The tensile strength of the AYC cast film increased with increasing the curing temperature, particularly at 120 degrees C curing. It is considered that the water was evaporated from the AYC-coated layer and the adhesion force between AYC particles increased during curing, making the structure of the AYC-coated layer densely firm. The changes in the duration of lag time and the release rate may be due to changes in the structure of the AYC-coated layer caused by curing. These results show that it is feasible to control the lag time and the release rate of AAP from AYC-coated tablets by varying the curing time and temperature.

  1. Investigação da cinética de cura por calorimetria diferencial exploratória (DSC de resinas epóxi preparadas a partir de óleo de soja epoxidado com diferentes anidridos e aminas terciárias Investigation of the kinetics of cure by differential scanning calorimetry (DSC of epoxy resins prepared from epoxidized soybean oil with different anhydrides and tertiary amines

    Directory of Open Access Journals (Sweden)

    Ana P. O. Costa

    2011-01-01

    Full Text Available No presente trabalho, utilizou-se a calorimetria diferencial exploratória (DSC para investigar a cinética da reação de cura de resinas epóxi produzidas a partir da reação do óleo de soja epoxidado (ESO, com os anidridos dodecenilsuccínico (DDS, maleico (MAL, ftálico (FTA, succínico (SUC e hexahidroftálico (CH, atuando como agentes de cura, e na presença de aminas terciárias como a trietilamina (TEA, a N,N'-dimetilanilina (ARO e a 1,4- diazobiciclo [2,2,2] octano (DABCO, atuando como catalisadores. A taxa de aquecimento, a natureza química e a estrutura do anidrido e das aminas influenciaram a reação de cura. Os métodos dinâmicos de Kissinger, Ozawa e de Barrett foram utilizados para calcular a energia de ativação dos sistemas onde se variou o anidrido. Observou-se que os anidridos mais reativos foram o DDS e maleico que apresentaram os menores valores de energias de ativação. No estudo da influência do catalisador, utilizou-se o método de Barrett para determinar as energias de ativação das reações com as diferentes aminas. A amina cicloaliafática (DABCO foi a mais reativa obtendo-se o menor valor de energia de ativação (Ea = 51 kJ.mol-1 e fator pré-exponencial (ln A0 = 9 s-1.In the present work, differential scanning calorimetry (DSC was used to investigate the curing reaction kinetics of epoxy resins produced from reaction of epoxidized soybean oil (ESO with cyclic anhydrides dodecenylsuccinic (DDS, maleic (MAL, phthalic (PA, succinic (SUC and hexahydrophthalic (CH, in the presence of tertiary amines such as triethylamine (TEA, N,N-dimethylaniline (ARO and 1,4-diazabicyclo [2,2,2] octane (DABCO. The heating rate, the nature and structure of anhydrides and amines were found to affect the curing reaction. The dynamic methods of Kissinger, Ozawa and Barrett were used to calculate the activation energy of the reactions where different anhydrides were used. DDS and maleic anhydrides were more reactive than the others

  2. Graft Copolymers of Maleic Anhydride and Its Isostructural Analogues: High Performance Engineering Materials

    OpenAIRE

    Rzayev, Zakir M. O.

    2011-01-01

    This review summarizes the main advances published over the last 15 years outlining the different methods of grafting, including reactive extruder systems, surface modification, grafting and graft copolymerization of synthetic and natural polymers with maleic anhydride and its isostructural analogues such as maleimides and maleates, and anhydrides, esters and imides of citraconic and itaconic acids, derivatives of fumaric acid, etc. Special attention is spared to the grafting of conventional ...

  3. COMPARISON OF THE E44 EPOXY RESINS IN DIFFERENT CONTENTS OF CURING AGENT BY MICROWAVE AND THERMAL CURING METHODS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper discusses the fundamental principle of microwave heating, and based on the advantages of microwave heating, use maleic anhydride as curing agent.The technology of microwave curing E44 epoxy resins is investigated,the mechanical properties of cured epoxy resin samples in different contents of curing agent by microwave and thermal curing methods are measured respectively, and then some experimental results for which are obtained.At last, this paper analyses why microwave curing can improve mechanical property of epoxy resin.

  4. 1-Butyl-3-methylimidazolium Salts as New Catalysts to Produce Epoxy-anhydride Polymers with Improved Properties

    Directory of Open Access Journals (Sweden)

    Mikhail S. Fedoseev

    2014-01-01

    Full Text Available We report the curing process of epoxy oligomers by using isomethyltetrahydrophthalic anhydride catalyzed with 1-butyl-3-methylimidazolium salts. Catalytic action has been ascertained to be dependent on the nature of anion. Salts with (Br- and (PO4- anions appeared to be most active. Formation of salt adducts with epoxy resin and anhydride is shown. Polymers having higher values of strength and glass transition temperature—as compared with similar epoxy systems cured in the presence of tertiary amines as catalysts—are prepared.

  5. Mechanistic Insights into an Unexpected Carbon DioxideInsertion Reaction through the Crystal Structures of CarbamicDiphenylthiophosphinic Anhydride and 1-[( 4-Nitrophenyl )-sulfonyl ]-trans-2,5-pyrrolidinedicarboxylic Acid Methyl Ester

    Institute of Scientific and Technical Information of China (English)

    SHI, Min; SHEN, Yu-Mei; JIANG, Jian-Kang

    2001-01-01

    The crystal structures of an unexpected carbon dioxide inserted carbamicdiphenylthiophosphinic anhydride and 1-[(4-nitrophenyl) sulfonyl]- trans-2, 5-pyrrolidinedicarboxylic acid methyl ester were determined by X-ray analysis. They crystallized in the space group P21(#4) with α=0.9550(2), b=0.9401(4), c= 1.2880(2) nm, β= 107.74°, V=1.1013(5) nm3, D calcd = 1.349 g/cm3, Z = 2 and P212121 ( # 19)with α= 1.4666(2), b = 0.7195(2), c = 1.6339(2) nm, V= 1.7240(7) nm3, Dcalcd= 1.434 g/cm3, Z=4, respectively.Through the investigation of these two crystal structures, the mechanistic insights into this unexpected carbon dioxide insertion in the reaction of trans-2,5-disubstituted pyrrolidine with diphenylthiophosphoryl chloride in the presence of potassium carbonate were disclosed.

  6. 乙酸酐/乙酸法制备油溶性胭脂虫红色素%Acetic anhydride/acetic acid prepared oil-soluble cochineal dye

    Institute of Scientific and Technical Information of China (English)

    刘兰香; 郑华; 钱岐雄; 张雯雯; 高山; 张弘

    2015-01-01

    胭脂虫红色素是水溶性极好的天然色素,改善其油溶性后可拓展该色素在油溶性食品、化妆品、药品、化工等行业的应用.本文以乙酸酐/乙酸为反应体系,对其有效染色成分胭脂红酸分子进行化学修饰后制得了油溶性胭脂虫红色素衍生物.通过单因素及响应曲面优化实验确定了制备油溶性胭脂虫红色素衍生物的最佳工艺参数为:胭脂虫红色素0.5g; 乙酸酐与乙酸用量均为10mL; 催化剂三乙胺用量为1.0mL; 反应温度70℃; 反应时间为8h; 此条件下油溶性胭脂虫红色素衍生物收率为65.2%.通过紫外可见光谱、红外光谱对所得到的色素产物进行了初步的结构表征,表明胭脂虫红酸分子中增加了酯基和烷基,得到的产物在油样中的溶解度为 2.41(25℃),且稳定性良好,说明胭脂虫红色素的油溶性得到有效的改善,具有开发和应用潜在价值与前景.%Cochineal is one of the most valuable water soluble natural pigments. Improving its oil soluble may contribute to the application on oil soluble food,cosmetics,medicines,etc. Herein, oil-soluble cochineal dye was obtained by molecule esterification of carminic acid with acetic anhydride/acetic acid in this paper. Based on single factor experiments,response surface methodology has been applied to further optimize pretreatment condition. Under the optimal condition,i.e. cochineal dye was 0.5g,acetic anhydride and acetic acid dosage were 10mL,catalyst dosage of triethylamine was 1.0mL,reaction temperature was 70℃,and reaction time was 8h,the yield of cochineal dye derivatives reach up to 65.2%. The target product showed good solubility in corn oil,good dyeing effect and good stability with 2.41g in oil (25℃). This suggests that cochineal dye derivatives have potential value and promising development prospects.

  7. Disproportionation of bromous acid HOBrO by direct O-transfer and via anhydrides O(BrO)2 and BrO-BrO2. An ab initio study of the mechanism of a key step of the Belousov-Zhabotinsky oscillating reaction.

    Science.gov (United States)

    Glaser, Rainer; Jost, Mary

    2012-08-16

    The results are reported of an ab initio study of the thermochemistry and of the kinetics of the HOBrO disproportionation reaction 2HOBrO (2) ⇄ HOBr (1) + HBrO(3) (3), reaction ( R4' ), in gas phase (MP2(full)/6-311G*) and aqueous solution (SMD(MP2(full)/6-311G*)). The reaction energy of bromous acid disproportionation is discussed in the context of the coupled reaction system R2-R4 of the FKN mechanism of the Belousov-Zhabotinsky reaction and considering the acidities of HBr and HOBrO(2). The structures were determined of ten dimeric aggregates 4 of bromous acid, (HOBrO)(2), of eight mixed aggregates 5 formed between the products of disproportionation, (HOBr)(HOBrO(2)), and of four transition states structures 6 for disproportionation by direct O-transfer. It was found that the condensation of two HOBrO molecules provides facile access to bromous acid anhydride 7, O(BrO)(2). A discussion of the potential energy surface of Br(2)O(3) shows that O(BrO)(2) is prone to isomerization to the mixed anhydride 8, BrO-BrO(2), and to dissociation to 9, BrO, and 10, BrO(2), and their radical pair 11. Hence, three possible paths from O(BrO)(2) to the products of disproportionation, HOBr and HOBrO(2), are discussed: (1) hydrolysis of O(BrO)(2) along a path that differs from its formation, (2) isomerization of O(BrO)(2) to BrO-BrO(2) followed by hydrolysis, and (3) O(BrO)(2) dissociation to BrO and BrO(2) and their reactions with water. The results of the potential energy surface analysis show that the rate-limiting step in the disproportionation of HOBrO consists of the formation of the hydrate 12a of bromous acid anhydride 7 via transition state structure 14a. The computed activation free enthalpy ΔG(act)(SMD) = 13.6 kcal/mol for the process 2·2a → [14a](‡) → 12a corresponds to the reaction rate constant k(4) = 667.5 M(-1) s(-1) and is in very good agreement with experimental measurements. The potential energy surface analysis further shows that anhydride 7 is

  8. Réaction du polyisobutène chloré sur l'anhydride maléique : mécanisme. Catalyse par l'anhydride dichloromaléique Reaction of Chlorinated Polyisobutene on Maleic Anhydride. Mechanism. Catalysis by Dichloromaleic Anhydride

    Directory of Open Access Journals (Sweden)

    Sillion B.

    2006-11-01

    Full Text Available Dans cet article le mécanisme de la réaction de condensation du polyisobutène chloré sur l'anhydride maléique, qui sert dans la synthèse d'additif pour lubrifiant, est étudié par une cinétique globale et par un travail sur composés modèles. Il est montré que, dans cette réaction, l'anhydride maléique joue un double rôle : de catalyseur de déshydrochloration par une réactivité de type acide de Lewis organique, de réactif comme diénophile. Grâce à ces résultats, il est proposé une catalyse par l'anhydride dichloromaléique, qui permet une amélioration sensible du procédé. This article examines the mechanism of the chlorinated-polyisobutene condensation reaction on maleic anhydride. The overall kinetics and model compounds are investigated for this reaction which is used in the synthesis of lubricant additives. Maleic anhydride is shown to play the dual role of a dehydrochlorination catalyst by having a reactivity of the organic Lewis acid type and of a reactant like dienophile. These results are used to propose a catalysis by dichloromaleic anhydride which appreciably improves the process.

  9. Wet Strength and Antibacterial Performance of Cellulosic Paper Induced by Maleic Anhydride-Acylated Chitosan

    OpenAIRE

    Zicheng Chen,; Chunting Li; Zhanqian Song,; Xueren Qian

    2014-01-01

    Paper sheets were dipped in maleic anhydride-acylated chitosan (MAAC) to enhance their wet strength and antibacterial performance. The wet strength of paper sheets treated with MAAC or chitosan solutions and cured at 90 and 170 °C was investigated. Escherichia coli was used to evaluate the antibacterial performance of the treated paper sheets. The antibacterial performance was determined by measuring the absorbance at 610 nm based on the turbidity of the bacterial suspension on the surface of...

  10. Extensive feeding versus oleic acid and tocopherol enriched mixed diets for the production of Iberian dry-cured hams: Effect on chemical composition, oxidative status and sensory traits.

    Science.gov (United States)

    Ventanas, S; Ventanas, J; Tovar, J; García, C; Estévez, M

    2007-10-01

    The present study aimed to analyse the chemical composition and oxidative status of Iberian dry-cured hams from pigs fed different finishing diets: extensive feeding on acorns and pasture in a "Montanera" traditional system (MON), fed in confinement with a mixed diet containing high-oleic sunflower oil (115g/kg of diet) and supplemented with 250mg/kg α-tocopherol (HOVE), and fed in confinement control mixed diet (CON) without added tocopherol and oleic acid fat. Muscles from MON dry-cured hams contained significantly (p<0.05) higher amounts of intramuscular fat (IMF) than those from HOVE and CON hams. The feeding background affected the tocopherol levels in dry-cured hams as those from MON and HOVE pigs had significantly higher levels of α-tocopherol than those from CON pigs whereas the extensive feeding provided muscles from MON pigs with significantly higher levels of γ-tocopherol than the experimental diets did to CON and HOVE pigs. The HOVE diet significantly increased the levels of oleic acid in Iberian dry-cured hams with these levels being similar to the oleic acid levels found in MON hams and significantly higher than those in CON hams. Compared to dry-cured hams from CON pigs, those from MON and HOVE pigs exhibited a higher oxidative stability as a likely result of a most favourable fatty acid composition and the presence of higher tocopherol levels. The principal component analysis (PCA) successfully discriminated between dry-cured hams from pigs fed different finishing diets.

  11. A facile and efficient synthetic method for 4-phenylethynylphthalic anhydride

    Institute of Scientific and Technical Information of China (English)

    Di Feng Wu; Mei Jia Yang; Yang Wang; Guo Wei Gao; Jian Men

    2011-01-01

    A novel approach to the synthesis of 4-phenylethynylphthalic anhydride has been described. The target compound was synthesized by Pd/Cu catalyzed Sonogashira coupling reaction between phenylacetylene and 4-bromophthalic acid which was for the first time employed as start material, followed by dehydration of 4-phenylethynylphthalic acid. Compared with traditional synthetic routes, this method provides several advantages such as readily available raw materials, convenient manipulation and high yield. The products were characterized by IR, 1H NMR, 13C NMR, MS and elemental analysis, respectively.

  12. A new process for the valorisation of a bio-alcohol. The oxidehydration of 1-butanol into maleic anhydride

    Energy Technology Data Exchange (ETDEWEB)

    Caldarelli, A.; Cavani, F.; Garone, O.; Pavarelli, G. [Bologna Univ. (Italy). Dipt. di Chimica Industriale e dei Materiali; Bologna Univ. (Italy). CIRCC, Research Unit; Dubois, J.L. [ARKEMA, Colombes (France); Mitsova, I.; Simeonova, L. [JSC, Russe (Bulgaria). Orgachim

    2012-07-01

    This paper deals with a study on the gas-phase transformation of 1-butanol into maleic anhydride, using different types of catalysts. Indeed, catalytic acid properties are needed to dehydrate 1-butanol into 1-butene, whereas redox-type properties are required for the oxidation of the olefin into maleic anhydride. The two types of active sites can be combined in bifunctional systems, showing both acid and redox-type properties. We found that vanadyl pyrophosphate catalyzes the one-pot reaction, giving a maximum selectivity to maleic anhydride of 28%. In fact, various side reactions contributed to the formation of by-products, eg, 1-butanol (oxidative) dehydrogenation into butyraldehyde, formation of light carboxylic acids and carbon oxides, and condensation of unsaturated C{sub 4} intermediates (butenes and butadiene) with the formed maleic anhydride to yield heavier compounds. (orig.)

  13. Acceleration of curing period of pastrami manufactured from buffalo meat: II-Fatty acids, amino acids, nutritional value and sensory evaluation

    Directory of Open Access Journals (Sweden)

    Ibrahim, Hayam M.A.

    2001-04-01

    Full Text Available Upon accelerating the curing period of pastrami (dry cured meat prepared from buffalo lean round muscles using heat treatment (~71ºC internally, the results indicated that: the peroxide and thiobarbituric acid (TBA values increased with increasing the aging period. Percentage of the released free fatty acids was 1.21 after heat treatment and increased gradually to reach 1.47 after hanging in air at room temperature for drying and complete curing up to 6 days. The major saturated and unsaturated fatty acids in all of the pastrami samples were palmitic (16:0, oleic (18:1 and linoleic (18:2 fatty acids. The main three identified polyunsaturated fatty acids (linoleic, linolenic and arachidonic were of high percentages in the accelerated cured samples than in the control one. The ratio of the unsaturated: saturated fatty acids was similar in either the heat treated (1.28:1 and the control (1.27: 1 pastrami samples. Similar findings were found for the ratio of total essential amino acids (EAAS: total amino acids (AAS. The Essential Amino Acids Index (EAAI that possesses higher percentage for the heat treated sample than that for the control one proved the higher biological acceptance of the heat accelerated cured pastrami sample. The predicted protein efficiency ratio (PER of all the investigated samples reached more than 2.42 of casein. Sensory evaluation of the pastrami sample processed to an internal temperature of ~71ºC proved by the panelists to be of attractive color, more tasty, of good characteristic odor and more tender than the control samples which were prepared and cured for 3 weeks without using heat treatment.En relación a la aceleración del período de cura del pastrami (carne curada en seco preparada a partir de carne magra de búfalo usando un tratamiento térmico (~71ºC internamente, los resultados indicaron que los valores de peróxido y ácido tiobarbitúrico (TBA aumentaron con el envejecimiento. El porcentaje de

  14. SWELLING AND WETTABILITY OF LIGHT-CURED METHACRYLATE-BASED DENTAL RESINS PREPARED FROM CHOLIC ACID

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    2 '-methacryloxy-3α, 7α 12α- trimethacryloyl cholic acid ethyl ester (CAGE4MA) has been prepared from cholic acid. Photo-polymeric resins were prepared from CAGE4MA. 2,2-bis[4-(2-hydroxy-3-methacrylyloxypropoxy)phenyl]propane (bis-GMA) was used for comparison, triethyleneglycol dimethacrylate (TEGDMA) was used as diluent. The polymerization was initiated by camphoroquinone (CQ)/N, N-dimethylaminoethyl methacrylate (DMAEMA) system. The conversion of CAGE4MA was 39% when the reaction time is 60s, which is lower than bis-GMA and TEGDMA.The swelling value of CAGE4MA resin was 0.41% in distilled water, which is much lower than those of bis-GMA resin (2.04%) and TEGDMA resin (4.77%) under the same conditions. Copolymers from CAGE4MA and TEGDMA have been prepared. With the increase of TEGDMA in mixture, the degree of conversion of CA GE4MA and swelling value increased. The swelling values of photocured resins in 0. 1mol/L HCl were also measured.

  15. Cure behavior of epoxy polymers used in microelectronics

    Science.gov (United States)

    Taweeplengsangsuke, Jantrawan

    2000-10-01

    Underfill resins are used to reduce solder fatigue in flip-chip assemblies. Both underfilling and curing processes are critical to achieve reliable finished products. This study included two main themes; the development of processing diagrams for commercial underfill resins and the fundamental understanding of cure kinetics and evolution of cure stresses in model epoxies. A variety of techniques have been used to characterize the fundamental phenomena involved in the processing of underfill resins. The flow behavior, cure kinetics, cure stresses, outgassing phenomena and void formation of underfill resins were studied. Processing diagrams for underfill resins were developed by mapping fundamental phenomena involved to provide a guideline for underfilling and curing steps. With these processing diagrams one should be able to design his underfilling and curing process with scientific approach. Two commercial underfill resins, which were evaluated as part of a SEMATECH program, where shown to possess significantly different processing characteristics. However, the appropriate explanation could not be made without knowing the proprietary chemistry of the systems. Therefore, model epoxies were formulated. Three different systems were investigated; amine, imidazole, and anhydride curing agent systems. With the known chemistry, the reaction kinetics and developed cure stress can be explained more clearly. Vitrification, which severely retards the rate of reaction, was found in amine (N-aminoethylpiperazine) and anhydride (Hexahydro-4-methylphthalic anhydride) cured systems when the cure temperatures were lower than the glass transition temperature (T g) of fully cured samples; however, imidazole(2-ethyl-4-methyl-imidazole) did not show vitrification when it was cured at 20 degrees below the T g of fully cured sample due to the large exotherms. Interestingly for imidazole system, the higher cure temperature exhibited a lower Tg. This could possibly be explained by the

  16. Dual cure photocatalyst systems

    Energy Technology Data Exchange (ETDEWEB)

    DeVoe, R.J.; Brown-Wensley, K.A.; Holmes, G.L.; Mathis, M.D.; McCormick, F.B.; Palazzotto, M.C.; Spurgeon, K.M. (Minnesota Mining and Mfg. Co., St. Paul, MN (USA). Corporate Research Labs.)

    1990-01-01

    A family of dual cure photocatalyst systems is being developed to be used in the solventless processing of organic coatings. The photocatalyst systems consist of organometallic compounds often in combination with other agents. Upon photolysis, the photocatalyst system generates a Lewis acid and a free radical. The Lewis acid can initiate the polymerization of epoxies or the addition of isocyanates and polyols to form polyurethanes while the free radical can initiate the polymerization of acrylates. The performance of the various photocatalyst systems will be compared on the basis of the physical properties of the cured compositions they produce. 17 figs.

  17. Vascular Cures

    Science.gov (United States)

    ... is Possible EVERY DOLLAR SAVES LIVES. Donate Now Vascular Cures innovates patient-centered research, catalyzes breakthrough collaborations and empowers people in their vascular health journey. what is vascular disease PATIENTS see ...

  18. [Determination of twenty free amino acids in flue-cured tobacco leaves using ultra performance liquid chromatography-single quadruple mass spectrometry and pre-column derivatization].

    Science.gov (United States)

    Li, Haoli; Zhao, Chunxia; Zhang, Junjie; Fu, Jiajun; Wang, Ying; Lu, Xin; Xu, Guowang

    2013-12-01

    Free amino acids in flue-cured tobacco leaves were investigated using the ultra performance liquid chromatography-single quadruple mass spectrometry detection and pre-column derivatization method. The validation results showed that the method could meet the analytical requirements. A total of 138 tobacco leaf samples were collected from 14 provinces in China in 2011 in which the free amino acids were determined. The relative standard deviations (RSDs) of the contents of free amino acids in different growing regions ranged from 28.50%-94.20%, and those of asparagine and glutamine were over 80%. The RSDs of the contents of free amino acids in full aroma tobacco leaves were larger than those in fresh aroma and medium aroma tobacco leaves. The principal component analysis (PCA) and non-parameter Mann-Whitney U test were used for data analysis. The free amino acids of the same aroma type grown in different regions or different aroma types in the same province showed great variation. The contents of free amino acids of full aroma tobacco grown in Southeast region were much lower than those in Huanghuai region. The contents of free amino acids in Hunan province were much lower than the average contents. The results showed that free amino acids in flue-cured tobacco leaves were affected by the growing region.

  19. Effects of dietary high-oleic acid sunflower oil, copper and vitamin E levels on the fatty acid composition and the quality of dry cured Parma ham.

    Science.gov (United States)

    Bosi, P; Cacciavillani, J A; Casini, L; Lo Fiego, D P; Marchetti, M; Mattuzzi, S

    2000-02-01

    The effects of seven isoenergetic dietary treatments: (1) no sunflower oil, 35 mg/kg Cu, without α-tocopheryl-acetate added; (2) to (7) 6% high oleic acid sunflower oil (HOSO), 35 or 175 mg/kg Cu crossed with a 0, 100 or 200 mg/kg α-tocopherol addition, were tested on quality characteristics of dry cured Parma hams from a total 84 Large White gilts. No statistically significant effect was detected on parameters of early evaluation of seasoning loss of hams. The seasoning loss and intramuscular fat content of seasoned hams averaged 28.1 and 3.3%, respectively, with no effect of the diet composition. The CIE L*a*b* colour values taken on the surface of the lean from Parma ham were not affected by dietary oil inclusion, nor by copper levels and by α-tocopherol addition in the feed mixture, except for the 'a' value that increased in HOSO groups (Poil group, the Parma hams in the HOSO groups showed a higher oleic acid content in the covering fat, but not different in neutral and polar fractions from semimenbranosus muscle. The oil inclusion reduced the saturated fatty acid content in subcutaneous fat and neutral lipids fraction from muscle to 30-34% No effect of α-tocopherol and copper levels were observed on fatty acids profiles. From the subjects fed the HOSO diet softer Parma hams were produced than those fed the control diet (χ(2)<0.05), while α-tocopherol and Cu levels did not influence the sensorial evaluation of hams. The inclusion of an oleic acid rich source in heavy pig diet brought about an improved nutritional value, but also the possible need of a prolonged ageing time to achieve an ideal firmness of Parma ham. Dietary α-tocopherol supplementation improved the red colour slightly and the lipid stability in Parma ham, while the supplementation of Cu in the diet had no influence on the tested parameters.

  20. Hydrolysis of Acetic Anhydride in a CSTR

    Directory of Open Access Journals (Sweden)

    Veronica N. Coraci

    2016-05-01

    Full Text Available To find the optimal reactor volume and temperature for the hydrolysis of acetic anhydride at the lowest possible cost with a 90% conversion of acetic anhydride, a formula for the total cost of the reaction was created. Then, the first derivative was taken to find a value for the temperature. This value was then inputted into the second derivative of the equation to find the sign of the value which would indicate whether that point was a minima or maxima value. The minima value would then be the lowest total cost for the optimum reaction to take place.

  1. Amino acid derivative-mediated detoxification and functionalization of dual cure dental restorative material for dental pulp cell mineralization.

    Science.gov (United States)

    Minamikawa, Hajime; Yamada, Masahiro; Iwasa, Fuminori; Ueno, Takeshi; Deyama, Yoshiaki; Suzuki, Kuniaki; Yawaka, Yasutaka; Ogawa, Takahiro

    2010-10-01

    Current dental restorative materials are only used to fill the defect of hard tissues, such as dentin and enamel, because of their cytotoxicity. Therefore, exposed dental pulp tissues in deep cavities must be first covered by a pulp capping material like calcium hydroxide to form a layer of mineralized tissue. However, this tissue mineralization is based on pathological reaction and triggers long-lasting inflammation, often causing clinical problems. This study tested the ability of N-acetyl cysteine (NAC), amino acid derivative, to reduce cytotoxicity and induce mineralized tissue conductivity in resin-modified glass ionomer (RMGI), a widely used dental restorative material having dual cure mechanism. Rat dental pulp cells were cultured on untreated or NAC-supplemented RMGI. NAC supplementation substantially increased the percentage of viable cells from 46.7 to 73.3% after 24-h incubation. Cell attachment, spreading, proliferative activity, and odontoblast-related gene and protein expressions increased significantly on NAC-supplemented RMGI. The mineralization capability of cells, which was nearly suppressed on untreated RMGI, was induced on NAC-supplemented RMGI. These improved behaviors and functions of dental pulp cells on NAC-supplemented RMGI were associated with a considerable reduction in the production of intracellular reactive oxygen species and with the increased level of intracellular glutathione reserves. These results demonstrated that NAC could detoxify and functionalize RMGIs via two different mechanisms involving in situ material detoxification and antioxidant cell protection. We believe that this study provides a new approach for developing dental restorative materials that enables mineralized tissue regeneration.

  2. Enhancing the functionality of biobased polyester coating resins through modification with citric acid.

    Science.gov (United States)

    Noordover, Bart A J; Duchateau, Robbert; van Benthem, Rolf A T M; Ming, Weihua; Koning, Cor E

    2007-12-01

    Citric acid (CA) was evaluated as a functionality-enhancing monomer in biobased polyesters suitable for coating applications. Model reactions of CA with several primary and secondary alcohols and diols, including the 1,4:3,6-dianhydrohexitols, revealed that titanium(IV) n-butoxide catalyzed esterification reactions involving these compounds proceed at relatively low temperatures, often via anhydride intermediates. Interestingly, the facile anhydride formation from CA at temperatures around CA's melting temperature ( T m = 153 degrees C) proved to be crucial in modifying sterically hindered secondary hydroxyl end groups. OH-functional polyesters were reacted with CA in the melt between 150 and 165 degrees C, yielding slightly branched carboxylic acid functional materials with strongly enhanced functionality. The acid/epoxy curing reaction of the acid-functional polymers was simulated with a monofunctional glycidyl ether. Finally, the CA-modified polyesters were applied as coatings, using conventional cross-linking agents. The formulations showed rapid curing, resulting in chemically and mechanically stable coatings. These results demonstrate that citric acid can be applied in a new way, making use of its anhydride formation to functionalize OH-functional polyesters, which is an important new step toward fully biobased coating systems.

  3. Effect of the amount of chestnuts in the diet of Celta pigs on the fatty acid profile of dry-cured lacon

    Energy Technology Data Exchange (ETDEWEB)

    Jesus, M.C. de; Dominguez, R.; Cantalapiedra, J.; Iglesias, A.; Lorenzo, J.M.

    2016-07-01

    The effect of including chestnuts in the formulation of the feed (0, 15 and 25% chestnut) on the fatty acids of dry-cured lacon from Celta pigs was studied. The inclusion of chestnuts decreases the saturated fatty acid content (SFA) and the monounsaturated fatty acid content (MUFA). With regards to the polyunsaturated fatty acids (PUFA), the lacon from animals fed with chestnuts presented higher values of total PUFA, n6 PUFAs and n3 PUFAs. This is related to the fact that chestnut diets had the highest amounts of essential fatty acids (C18:2n6 and C18:3n3), therefore the lacon from chestnut-fed animals also presented higher amounts of these fatty acids. According to nutritional ratios, lacon obtained from chestnut-fed pigs was healthier than the one obtained from pigs fed on commercial feed. The main conclusion is that including chestnuts in the diet allows us to obtain healthier dry-cured meat products. (Author)

  4. PHOTOCOPOLYMERIZATION OF MALEIC ANHYDRIDE AND VINYL ACETATE

    Institute of Scientific and Technical Information of China (English)

    LI Xiaofang; LI Shanjun; QIN Anwei; YU Tongyin

    1990-01-01

    The charge-transfer complex of maleic anhydride and vinyl acetate was copolymerized under UV light. The chain composition and structure of the copolymer were analyzed with conductometry and NMR, and the chain sequence was determined as alternating. The copolymerization rates at different feed ratios, temperatures and in different solvents were investigated, giving evidence to the very active involvement of the CT complexes in the copolymerization. Terpolymerization with acrylonitrile also showed that the complex mechanism was a proper one for this system.

  5. Increasing the electrical discharge endurance of acid anhydride cured DGEBA epoxy resin by dispersion of nanoparticle silica. High Perform. Polym. 11 (1999) pp 281-296 by IOP Publishing Ltd

    DEFF Research Database (Denmark)

    Henk, Peter O; Kortsen, T.W.; Kvarts, T.

    1999-01-01

    combinations were used: (a) fumed nanoparticle silicon dioxide referred to as Aerosil, (b) equal volumes of Aerosil and nanoparticle anatase, and (c) Aerosil plus anatase in combination with coarse-particle filler grade calcium-magnesium carbonate dolomite. A test for endurance using the CIGRE method II...... the endurance by a factor of up to 20 as the Aerosil content goes from zero to 5.4 vol%. Aerosil mixed with anatase has a similar effect. The high level of endurance is maintained with an additional high-volume (35 vol.%) filling of coarse-particle dolomite to an epoxy system already containing Aerosil...

  6. Properties of Esterified Wood Prepared with Maleic Anhydride / Tetrabr Omophthalic Anhydride / Glycerol Mixture

    Institute of Scientific and Technical Information of China (English)

    Li Jianzhang; Furuno Takeshi; Zhou Wenrui; Yu Zhiming; Sun Yanling; Zhang Derong

    2003-01-01

    For overcoming disadvantages of wood, an esterification process was employed and tetrabromophthalic anhydride (TBPA) was used as a reactive chemical agent to prepare an esterified wood with the high dimensional stability, flame resistance, and resistance to biodegradation from water-leaching. The experimental results indicated that esterification of wood plus maleic anhydride / tetrabromophthalic anhydride / glycerol could endow wood with dimensional stability, the antiswelling efficiency during water absorption (ASEw), reduction in water absorptivity (RWA), antiswelling efficiency during moisture absorption (ASEm), moisture excluding efficiency (MEE), and oxygen index (OI) of treated wood increased with an increase in the weight percent gain (WPG). And the treated wood showed great decay resistance and resistance to water leaching, too.

  7. 烤烟中非挥发性有机酸和高级脂肪酸研究进展%Research Progress in Nonvolatile Organic Acids and High Fatty Acids in Flue- cured Tobacco

    Institute of Scientific and Technical Information of China (English)

    张骏

    2012-01-01

    The nonvolatile organic acids and high fatty acids have significant influences on the aroma quality of smoking gas and tobacco leaf quality of flue - cured tobacco. This article systematically introduced the influences of nonvolatile organic acids and high fatty acids on flue -cured tobacco, the physiochemical properties and distributive characteristics of nonvolatile organic acids and high fatty acids in tobacco leaves, and the control factors affecting the contents of nonvolatile organic acids and high fatty acids. The author also discussed the prospects of the future researches in this field.%非挥发性有机酸和高级脂肪酸影响烟气的香气质量,对烟叶品质有着重要作用.系统地介绍了非挥发性有机酸和高级脂肪酸对烤烟的影响、理化特点、分布特点及影响其含量的控制因子.并对今后的研究方向进行了展望.

  8. Omega-3 polyunsaturated fatty acid from extruded linseed influences the fatty acid composition and sensory characteristics of dry-cured ham from heavy pigs.

    Science.gov (United States)

    Musella, M; Cannata, S; Rossi, R; Mourot, J; Baldini, P; Corino, C

    2009-11-01

    Twenty-four barrows (78.1 +/- 1.7 kg of initial BW) were fed a control diet (2.5% sunflower oil) or an experimental diet containing 5% whole extruded linseed. Both diets were supplemented with 170 mg of vitamin E/kg of feed. At slaughter (160 +/- 9.2 kg of BW), 6 hams were collected per group and delivered to Stazione Sperimentale per l'Industria delle Conserve Alimentari of Parma for seasoning. There was no effect (P > 0.05) of diet on the physicochemical characteristics of dry-cured ham. The linseed diet increased (P characteristics of dry-cured ham.

  9. Graft Copolymers of Maleic Anhydride and Its Isostructural Analogues: High Performance Engineering Materials

    CERN Document Server

    Rzayev, Zakir M O

    2011-01-01

    This review summarizes the main advances published over the last 15 years outlining the different methods of grafting, including reactive extruder systems, surface modification, grafting and graft copolymerization of synthetic and natural polymers with maleic anhydride and its isostructural analogues such as maleimides and maleates, and anhydrides, esters and imides of citraconic and itaconic acids, derivatives of fumaric acid, etc. Special attention is spared to the grafting of conventional and non-conventional synthetic and natural polymers, including biodegradable polymers, mechanism of grafting and graft copolymerization, in situ grafting reactions in melt by reactive extrusion systems, in solutions and solid state (photo- and plasma-induced graftings), and H-bonding effect in the reactive blend processing. The structural phenomena, unique properties and application areas of these copolymers and their various modifications and composites as high performance engineering materials have been also described.

  10. Characterization of the curing agents used in epoxy resins with TG/FT-IR technique

    OpenAIRE

    Benedita M. V. Romão; Diniz,Milton F.; Margarete F. P. Azevedo; Vera L. Lourenço; Luiz C. Pardini; Rita C.L. Dutra; Fabrice Burel

    2006-01-01

    Samples of epoxy resin (EP) based on the diglycidyl ether of bisphenol A (DGEBA), cured with nadic methyl anhydride (NMA) and mercaptan (CAPCURE 3-800), or amine-phenol (CAPCURE EH-30), respectively, SE 4 and SE 5, were prepared in the stoichiometric ratio determined by the supplier. The curing behaviour of the epoxy systems SE 4 and SE 5 was followed by DSC (Differential Scanning Calorimetry). These SE and their ingredients were analyzed using FTIR transmission techniques (KBr pellets, pyrol...

  11. 腊鱼加工中的乳酸菌及其特性%Lactic Acid Bacteria in Cured Fish and Its Growth Properties

    Institute of Scientific and Technical Information of China (English)

    谢静; 熊善柏; 曾令彬; 赵思明

    2009-01-01

    以白鲢为原料,对腊鱼加工过程的乳酸菌进行分离鉴定,并分析了其特性,为腊鱼加工及其品质控制提供实验数据.结果表明,腊鱼加工中存在植物乳杆菌、弯曲乳杆菌、食品乳杆菌、乳酸片球菌、戊糖片球菌,且不同加工阶段乳酸菌苗种分布不同.原料鱼、腌制结束时鱼体和成品中杆菌分别占乳酸菌的88%、56%和94%,是腊鱼加工中的优势乳酸菌.所有分离的乳酸菌都具有一定的耐盐、耐低温能力和蛋白酶活性,其中弯曲乳杆菌、乳酸片球菌的耐盐和耐低温能力较高;乳酸片球菌的蛋白酶活性最高.%With sliver carp as raw materials, Lactic acid bacteria(LAB) during processing cured fish was isola-ted and identified, whose properties were also studied ,aiming at providing experimental data for cured fish processing and quality control. The results shows that Lactobacillus plantarum, Lactobacillus curvatus,Lactobacillus alimentarius,Pediococcus pentosaceu,Pediococcus acidiactici exist in cuerd fish. And the distribution of LAB was different in different stages. Bacilli were dominant LAB during processing cured fish, ratio of bacilli to LAB from fresh fish, pickled fish and cured fish was 88%, 56% and 94%, respectively. All of isolations have the ability of salt tolerance, low-tem-perature resistance and protease activity. Lactobacillus curvatus and Pediococcus acidiactici have higher ability of salt tolerance and low-temperature resistance. Protease activity of Pediococcus acidiactici is the highest.

  12. Ambient cure polyimide foams prepared from aromatic polyisocyanates, aromatic polycarboxylic compounds, furfuryl alcohol, and a strong inorganic acid

    Science.gov (United States)

    Sawko, Paul M. (Inventor); Riccitiello, Salvatore R. (Inventor); Hamermesh, Charles L. (Inventor)

    1980-01-01

    Flame and temperature resistant polyimide foams are prepared by the reaction of an aromatic dianhydride, e.g., pyromellitic dianhydride, with an aromatic polyisocyanate, e.g., polymethylene polyphenylisocyanate (PAPI) in the presence of an inorganic acid and a lower molecular weight alcohol, e.g., dilute sulfuric acid or phosphoric acid and furfuryl alcohol. The exothermic reaction between the acid and the alcohol provides the heat necessary for the other reactants to polymerize without the application of any external heat. Such mixtures, therefore, are ideally suited for in situ foam formation, especially where the application of heat is not practical or possible.

  13. Effect of the amount of chestnuts in the diet of Celta pigs on the fatty acid profile of dry-cured lacon

    Directory of Open Access Journals (Sweden)

    de Jesús, M. C.

    2016-03-01

    Full Text Available The effect of including chestnuts in the formulation of the feed (0, 15 and 25% chestnut on the fatty acids of dry-cured lacon from Celta pigs was studied. The inclusion of chestnuts decreases the saturated fatty acid content (SFA and the monounsaturated fatty acid content (MUFA. With regards to the polyunsaturated fatty acids (PUFA, the lacon from animals fed with chestnuts presented higher values of total PUFA, n6 PUFAs and n3 PUFAs. This is related to the fact that chestnut diets had the highest amounts of essential fatty acids (C18:2n6 and C18:3n3, therefore the lacon from chestnut-fed animals also presented higher amounts of these fatty acids. According to nutritional ratios, lacon obtained from chestnut-fed pigs was healthier than the one obtained from pigs fed on commercial feed. The main conclusion is that including chestnuts in the diet allows us to obtain healthier dry-cured meat products.Se estudió el efecto de la inclusión de la castaña en la formulación del pienso (0, 15 y 25% de castaña sobre el perfil de ácidos grasos del lacón curado de cerdo Celta. La inclusión de castañas produjo una disminución del contenido de ácidos grasos saturados (SFA y monoinsaturados (MUFA. Con respecto a los ácidos grasos poliinsaturados (PUFA los lacones de animales alimentados por castaña presentaron valores más altos de PUFA totales, PUFA n6 y PUFA n3. Esto está relacionado con que las castañas tienen una mayor cantidad de ácidos grasos esenciales (C18:2n6 y C18:3n3, por tanto los lacones de cerdos alimentados con castaña también presentan mayores contenidos de estos ácidos grasos. De acuerdo con los índices nutricionales, los lacones obtenidos de cerdos alimentados con mayor proporción de castañas fueron más saludables. La inclusión de castañas en la dieta nos permite obtener productos cárnicos curados más saludables.

  14. Epoxy monomers derived from tung oil fatty acids and its regulable thermosets cured in two synergistic ways

    Science.gov (United States)

    A new bio-based epoxy monomer with conjugated double bonds, glycidyl ester of eleostearic acid (GEEA), was synthesized from tung oil fatty acids and characterized by 1H-NMR, 13C-NMR and Mass Spectrometry Analysis (MSA). Differential Scanning Calorimetry (DSC) analysis and FT-IR were utilized to inve...

  15. An epoxy monomer derived from Tung oil fatty acids and its products cured by two synergistic reactions

    Science.gov (United States)

    A new bio-based epoxy monomer containing conjugated double bonds, the glycidyl ester of eleostearic acid (GEEA), was synthesized from tung oil fatty acids. It was characterized using 1H-NMR, 13C-NMR and mass spectrometric analysis. Differential scanning calorimetry (DSC) and FT-IR spectroscopy were ...

  16. Air formaldehyde and solvent concentrations during surface coating with acid-curing lacquers and paints in the woodworking and furniture industry.

    Science.gov (United States)

    Thorud, Syvert; Gjolstad, Merete; Ellingsen, Dag G; Molander, Paal

    2005-06-01

    An investigation of contemporary exposure to formaldehyde and organic solvents has been carried out during surface coating with acid-curing lacquers and paints in the Norwegian woodworking and furniture industry over a period of 3 years. The investigation covered 27 factories of different sizes and with different types of production, and totally 557 parallel formaldehyde and solvent samples were collected. The formaldehyde concentration (geometric mean) was 0.15 ppm (range 0.01-1.48 ppm) with about 10% of the samples exceeding the Norwegian occupational exposure limit of 0.5 ppm. The solvent concentration as additive effect (geometric mean) was 0.13 (range 0.0004-5.08) and about 5% of the samples exceeded the Norwegian occupational exposure limit. The most frequently occurring solvents from acid-curing lacquers were n-butyl acetate, ethanol, ethyl acetate and 1-butanol, which were found in 88-98% of the samples. Toluene, n-butyl acetate and 1-butanol were the only solvents with maximum concentrations exceeding their respective occupational exposure limits. Curtain painting machine operators were exposed to the highest concentrations of both formaldehyde (geometric mean 0.51 ppm, range 0.08-1.48 ppm) and organic solvents (additive effect, geometric mean 1.18, range 0.02-5.08). Other painting application work tasks such as automatic and manual spray-painting, manual painting and dip painting, showed on average considerably lower concentrations of both formaldehyde (geometric means 0.07-0.16 ppm) and organic solvents (additive effect, geometric mean 0.02-0.18). Non-painting work tasks also displayed moderate concentrations of formaldehyde (geometric means 0.11-0.17 ppm) and organic solvents (additive effect, geometric mean 0.04-0.07).

  17. Exposure to cyclic anhydrides in welding: a new allergen-chlorendic anhydride.

    Science.gov (United States)

    Pfäffli, Pirkko; Hämeilä, Mervi; Keskinen, Helena; Wirmoila, Ritva

    2002-11-01

    Respiratory effects associated with welding fumes have been manifested in welders as occupational asthma. Previous studies have concerned mainly the effects of metal fume exposure, although it has also been suggested that asthma may develop as a result of exposure to contaminants generated from painted metals. To determine whether welding fumes contain irritating and sensitizing anhydrides, air samples were collected during the repair welding of forest harvesters, which were painted with chlorinated polyester paint. Samples were collected with an assembly of a spiral glass trap inserted between a filter holder with a Teflon filter and a Tenax sampling tube. Sample analyses were with GC-MS and GC-ECD. Sensitizing anhydrides released from the paint into the air were primarily chlorendic anhydride (paint films are electrical insulators, the film around the welding seam was removed before arc welding. Removal of paint with an abrasive wheel caused the least exposure to HCl (paint coating be removed from an area around the seam with an abrasive wheel, not by burning, before welding.

  18. Synthesis and Characterization of Poly(maleic Anhydride)s Cross-linked Polyimide Aerogels

    Science.gov (United States)

    Guo, Haiquan; Meador, Mary Ann B.

    2015-01-01

    With the development of technology for aerospace applications, new thermal insulation materials are required to be flexible and capable of surviving high heat flux. For instance, flexible insulation is needed for inflatable aerodynamic decelerators which are used to slow spacecraft for entry, descent and landing (EDL) operations. Polyimide aerogels have low density, high porosity, high surface area, and better mechanical properties than silica aerogels and can be made into flexible thin films, thus they are potential candidates for aerospace needs. The previously reported cross-linkers such as octa(aminophenyl)silsesquioxane (OAPS) and 1,3,5-triaminophenoxybenzene (TAB) are either expensive or not commercially available. Here, we report the synthesis of a series of polyimide aerogels cross-linked using various commercially available poly(maleic anhydride)s, as seen in Figure 1. The amine end capped polyimide oligomers were made with 3,3,4,4-biphenyltetracarboxylic dianhydride (BPDA) and diamine combinations of dimethylbenzidine (DMBZ) and 4, 4-oxydianiline (ODA). The resulting aerogels have low density (0.12 gcm3 to 0.16 gcm3), high porosity (90) and high surface area (380-554 m2g). The effect of the different poly(maleic anhydride) cross-linkers and polyimide backbone structures on density, shrinkage, porosity, surface area, mechanical properties, moisture resistance and thermal properties will be discussed.

  19. Convergence of Biological Nitration and Nitrosation via Symmetrical Nitrous Anhydride

    Science.gov (United States)

    Vitturi, Dario A.; Minarrieta, Lucia; Salvatore, Sonia R.; Postlethwait, Edward M.; Fazzari, Marco; Ferrer-Sueta, Gerardo; Lancaster, Jack R.; Freeman, Bruce A.; Schopfer, Francisco J.

    2015-01-01

    Current perspective holds that the generation of secondary signaling mediators from nitrite (NO2−) requires acidification to nitrous acid (HNO2) or metal catalysis. Herein, the use of stable isotope-labeled NO2− and LC-MS/MS analysis of products revealed that NO2− also participates in fatty acid nitration and thiol S-nitrosation at neutral pH. These reactions occur in the absence of metal centers and are stimulated by nitric oxide (•NO) autoxidation via symmetrical dinitrogen trioxide (nitrous anhydride, symN2O3) formation. While theoretical models have predicted physiological symN2O3 formation, its generation is now demonstrated in aqueous reaction systems, cell models and in viv, with the concerted reactions of •NO and NO2− shown to be critical for symN2O3 formation. These results reveal new mechanisms underlying the NO2− propagation of •NO signaling and the regulation of both biomolecule function and signaling network activity via NO2−-dependent nitrosation and nitration reactions. PMID:26006011

  20. PREPARATION OF ISOMERIZED METHYL TETRAHYDROPHTHALIC ANHYDRIDE%异构化甲基四氢苯酐的研制

    Institute of Scientific and Technical Information of China (English)

    吴光杰

    2001-01-01

    Isomerized methyl tetrahydrophthalic anhydride with low viscosity,a curing agent of epoxy resin (N-570D),was prepared in this paper.Effect of some factors,such as catalyst,temperature et al on product gield and method of inhibitting side reaction were also discussed.%制备了低粘度环氧树脂固化剂(N-570D),即:异构化甲基四氢苯酐(MeTHPA),讨论催化剂等因素对收率的影响,并论述了抑制副反应的方法。

  1. Optimal Composite Curing System

    Science.gov (United States)

    Handel, Paul; Guerin, Daniel

    The Optimal Composite Curing System (OCCS) is an intelligent control system which incorporates heat transfer and resin kinetic models coupled with expert knowledge. It controls the curing of epoxy impregnated composites, preventing part overheating while maintaining maximum cure heatup rate. This results in a significant reduction in total cure time over standard methods. The system uses a cure process model, operating in real-time, to determine optimal cure profiles for tool/part configurations of varying thermal characteristics. These profiles indicate the heating and cooling necessary to insure a complete cure of each part in the autoclave in the minimum amount of time. The system coordinates these profiles to determine an optimal cure profile for a batch of thermally variant parts. Using process specified rules for proper autoclave operation, OCCS automatically controls the cure process, implementing the prescribed cure while monitoring the operation of the autoclave equipment.

  2. Gelatin-based biomaterial engineering with anhydride-containing oligomeric cross-linkers.

    Science.gov (United States)

    Loth, Tina; Hötzel, Rudi; Kascholke, Christian; Anderegg, Ulf; Schulz-Siegmund, Michaela; Hacker, Michael C

    2014-06-01

    Chemically cross-linked gelatin hydrogels are versatile cell-adhesive hydrogel materials that have been established for a variety of biomedical applications. The most prominent cross-linker is glutaraldehyde, which, however, has been described to cause compatibility problems and loss of microscopic but relevant structural features. A recently developed oligomeric cross-linker that contains anhydride functionalities was evaluated as cross-linker for the fabrication of gelatin-based hydrogels and microparticles. In a fast curing reaction, hydrogels composed of gelatin and oligomeric cross-linker were fabricated with good conversion over a wide concentration range of constituents and with cross-linkers of different anhydride contents. Hydrogel properties, such as dry weight and mechanics, could be controlled by hydrogel composition and rheological properties correlated to elastic moduli from 1 to 10 kPa. The gels were shown to be cytocompatible and promoted cell adhesion. In soft formulations, cells migrated into the hydrogel bulk. Gelatin microparticles prepared by a standard water-in-oil emulsion technique were also treated with the novel oligomers, and cross-linking degrees matching those obtained with glutaraldehyde were obtained. At the same time, fewer interparticular cross-links were observed. Fluorescein-derivatized cross-linkers yielded labeled microparticles in a concentration-dependent manner. The oligomeric cross-linkers are presented as an efficient and possibly more functional and compatible alternative to glutaraldehyde. The engineered hydrogel materials hold potential for various biomedical applications.

  3. Impact of salt reduction on biogenic amines, fatty acids, microbiota, texture and sensory profile in traditional blood dry-cured sausages.

    Science.gov (United States)

    Laranjo, Marta; Gomes, Ana; Agulheiro-Santos, Ana Cristina; Potes, Maria Eduarda; Cabrita, Maria João; Garcia, Raquel; Rocha, João Miguel; Roseiro, Luísa Cristina; Fernandes, Maria José; Fraqueza, Maria João; Elias, Miguel

    2017-03-01

    Meat industry needs to reduce salt in their products due to health issues. The present study evaluated the effect of salt reduction from 6% to 3% in two Portuguese traditional blood dry-cured sausages. Physicochemical and microbiological parameters, biogenic amines, fatty acids and texture profiles and sensory panel evaluations were considered. Differences due to salt reduction were perceptible in a faint decline of water activity, which slightly favoured microbial growth. Total biogenic amines content ranged from 88.86 to 796.68mgkg(-1) fresh matter, with higher amounts, particularly of cadaverine, histamine and tyramine, in low-salt products. Still, histamine and other vasoactive amines remained at low levels, thus not affecting consumers' health. Regarding fatty acids, no significant differences were observed due to salt. However, texture profile analysis revealed lower resilience and cohesiveness in low-salt products, although no textural changes were observed by the sensory panel. Nevertheless, low-salt sausages were clearly preferred by panellists. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. PRELIMINARY STUDY OF EXTRACTABLE PROTEIN BINDING USING MALEIC ANHYDRIDE COPOLYMER

    Institute of Scientific and Technical Information of China (English)

    Thirawan Nipithakul; Ladawan Watthanachote; Nanticha Kalapat

    2012-01-01

    A preliminary study of using maleic anhydride copolymer for protein binding has been carried out.The polymeric films were prepared by compression of the purified resin and annealing the film to induce efficient back formation of the anhydride groups.The properties of the film surface were analyzed by attenuated total reflection Fourier transforms infrared spectroscopy and water contact angle measurements.The protein content was determined by Bradford assay.To obtain optimum conditions,immersion time for protein binding was examined.Results revealed that proteins can be successfully immobilized onto the film surface via covalent linkage.The efficiency of the covalent binding of the extractable protein to maleic anhydride-polyethylene film was estimated at 69.87 μtg/cm2,although the film had low anhydride content (3%) on the surface.

  5. 烤烟不同叶位叶片有机酸含量的差异分析%Difference Analysis of the Nonvolatile Organic Acids and Higher Organic Acids of the Different Leaf Position in Flue-cured Tobacco

    Institute of Scientific and Technical Information of China (English)

    景延秋; 张欣华; 刘剑君; 杨宇熙; 李广良; 张红立; 金磊; 李怀奇

    2011-01-01

    The pre-treatment of sulfuric acid methyl ester with gas chromatography-mass spectrometry (GC/ MS) analysis techniques was utilized to study the difference of the organic acid content in different flue-cured tobacco leaf (L8-L12: from the bottom of the eighth leave up to the twelfth leave) and its influence on fluecured tobacco'quality. The results showed that malic acid, γ-e ketone acid, citric acid, malonic acid, linolenic acid and palmitic acid had a higher content relatively in different flue-cured tobacco leaves and they were the main acidic components, what's more, the difference between organic acids, malic acid and other organic acids content in different leaf was significantly obvious. The differencce of total organic acids content from the eighth to the twelfth leave was L8 > L9 > L12 > L10 > L11; The content proportion ranges of non-volatile acid, senior saturated fatty acid and senior unsaturated fatty acid in total organic acids were 88.49% -94.38% ,3.01% -5. 10% and 2.61% -6. 40% , respectively. The difference analysis of organic acids content in different leaf position indicated that the organic acids content in the eighth and twelfth leaves was moderate and they could be considered as the superior and slap-up tobacco raw materials.%采用硫酸甲酯化前处理,结合气相色谱-质谱( GC/MS)分离分析技术,研究了烤烟不同叶位叶片(L8-L12,即从底部第8位叶向上到第12位叶)有机酸含量的差异.GC/MS定量分析结果表明:烤烟不同叶位叶片中,苹果酸、γ-戊酮酸、柠檬酸、丙二酸、乙二酸、亚麻酸和软脂酸含量相对较高,是烤烟中主要的有机酸成分;并且不同叶位叶片有机酸、苹果酸与其他有机酸含量差异明显;不同叶位叶片有机酸总量表现为:L8> L9> L12> L10> L11;L8-L12叶片中,非挥发性有机酸、高级饱和脂肪酸、高级不饱和脂肪酸总量分别在有机酸总量中所五比例范围是:88.49% ~94.38%,3.01% ~5

  6. 硫酸二乙酯酸值对123树脂固化的影响研究%Influence of Acid Value in Diethyl Sulfate on the Curing Process of 123 Resin

    Institute of Scientific and Technical Information of China (English)

    罗雪梅; 左玉芬; 黄黎明; 秦蛟

    2001-01-01

    The curing process of 123 resin was studied by means of microcalorimetry with diethyl sulfate as a curing agent. The results show that the acid value(greater than 1 percent) of diethyl sulfate has an effect on the curing rate and cured degree. When acid values of diethyl sulfates vary in a proper range(less than 1 percent),curing rate,cured degree and curing heat of 123 resin will not be affected.The curing mechanism of 123 resin was studied through FTIR technique. It shows that with the deepening of cured degree,the magnitude of characteristic peaks of CC at 1 651 cm-1 、CH2 at 3 095~3 075 cm-1 and 3 040~3 010 cm-1 attenuates sharply,indicating that the cross-link reaction takes place on the non-saturated double bond within the CC group for monomers Ⅰ and Ⅱ.%用微热量热法研究了用不同酸值的硫酸二乙酯作固化剂时123树脂的固化过程,结果表明,酸值大于1%的硫酸二乙酯对123树脂的固化速率与固化反应深度有较大影响。当酸值小于1%时,固化的速率、深度和热效应基本不变。用FTIR研究了123树脂的固化机理,发现随着固化反应的加深,1 651 cm-1处的CC特征峰、3 095~3 075 cm-1和3 040~3 010 cm-1处的CH2特征峰强度明显减弱,表明交联反应发生在单体的不饱和双键处。

  7. PDMS-modified poly(styrene-alt-maleic anhydride)s as water-borne coatings based on surfactant-free latexes

    NARCIS (Netherlands)

    Gunbas, I.D.; Wouters, M.E.L.; Benthem, R.A.T.M. van; Koning, C.E.; Noordover, B.A.J.

    2013-01-01

    In this work, two series of PDMS-modified poly(styrene-alt-maleic anhydride)s (PSMA) were prepared by the partial imidization of their anhydride groups with mono-functional, amine-terminated polydimethyl siloxanes (PDMS-NH2) with two different molecular weights. Subsequently, surfactant-free artific

  8. 3D Printing of Cytocompatible Water-Based Light-Cured Polyurethane with Hyaluronic Acid for Cartilage Tissue Engineering Applications

    Science.gov (United States)

    Shie, Ming-You; Chang, Wen-Ching; Wei, Li-Ju; Huang, Yu-Hsin; Chen, Chien-Han; Shih, Cheng-Ting; Chen, Yi-Wen; Shen, Yu-Fang

    2017-01-01

    Diseases in articular cartilages have affected millions of people globally. Although the biochemical and cellular composition of articular cartilages is relatively simple, there is a limitation in the self-repair ability of the cartilage. Therefore, developing strategies for cartilage repair is very important. Here, we report on a new liquid resin preparation process of water-based polyurethane based photosensitive materials with hyaluronic acid with application of the materials for 3D printed customized cartilage scaffolds. The scaffold has high cytocompatibility and is one that closely mimics the mechanical properties of articular cartilages. It is suitable for culturing human Wharton’s jelly mesenchymal stem cells (hWJMSCs) and the cells in this case showed an excellent chondrogenic differentiation capacity. We consider that the 3D printing hybrid scaffolds may have potential in customized tissue engineering and also facilitate the development of cartilage tissue engineering. PMID:28772498

  9. Anhydride formation is not a valid mechanism for peptide cleavage by carboxypeptidase-A: a semiempirical reaction pathway study

    Science.gov (United States)

    Vardi-Kilshtain, Alexandra; Shoham, Gil; Goldblum, Amiram

    The mechanism of action of zinc metalloproteinases has been studied by following the direct nucleophilic pathway, which has been frequently suggested but not yet examined by computational methods, and comparing it to other pathways. We computed the reaction enthalpies for the direct nucleophilic attack by Glu270 in the active site model of carboxypeptidase-A on a model substrate's peptide carbonyl and followed this pathway through mixed anhydride formation and subsequent anhydride cleavage by water. The starting molecular coordinates originate in our own high-resolution crystal structure and the computations have been conducted with the minimal neglect of differential overlap (MNDO) Hamiltonian, modified to include the d-orbitals of zinc and the effects of multiple hydrogen bonding, thus labelled MNDO/d/H. Compared to our recent results for two other candidate pathways for this mechanism, both of the General-Acid-General-Base type, we conclude that the direct nucleophilic or 'anhydride' pathway has a much higher energy barrier at the rate determining step, which is a proton transfer, than previously calculated paths. We argue that the 'anhydride' pathway is thus not a valid one for the cleavage of peptides by carboxypeptidase-A.

  10. A New Process for Maleic Anhydride Synthesis from a Renewable Building Block: The Gas-Phase Oxidehydration of Bio-1-butanol.

    Science.gov (United States)

    Pavarelli, Giulia; Velasquez Ochoa, Juliana; Caldarelli, Aurora; Puzzo, Francesco; Cavani, Fabrizio; Dubois, Jean-Luc

    2015-07-01

    We investigated the synthesis of maleic anhydride by oxidehydration of a bio-alcohol, 1-butanol, as a possible alternative to the classical process of n-butane oxidation. A vanadyl pyrophosphate catalyst was used to explore the one-pot reaction, which involved two sequential steps: 1) 1-butanol dehydration to 1-butene, catalysed by acid sites, and 2) the oxidation of butenes to maleic anhydride, catalysed by redox sites. A non-negligible amount of phthalic anhydride was also formed. The effect of different experimental parameters was investigated with chemically sourced 1-butanol, and the results were then confirmed by using genuinely bio-sourced 1-butanol. In the case of bio-1-butanol, however, the purity of the product remarkably affected the yield of maleic anhydride. It was found that the reaction mechanism includes the oxidation of butenes to crotonaldehyde and the oxidation of the latter to either furan or maleic acid, both of which are transformed to produce maleic anhydride.

  11. Preparation and Crystallization of Carbon Nanotube/maleic Anhydride-grafted Polypropylene Composites

    Institute of Scientific and Technical Information of China (English)

    Xiaohua CHEN; Jing HU; Lingping ZHOU; Wenhua LI; Zi YANG; Yanguo WANG

    2008-01-01

    Carbon nanotube (CNT)/maleic acid anhydride (MAH)-grafted polypropylene (PP) composites were prepared by in situ grafting method. Infrared spectroscopy showed that the CNTs were linked to PP by MAH grafting. The microstructures and calorimetry analysis indicated that the crystallization behaviors of the filled and unfilled PP were quite different. The addition of CNTs dramatically reduced the spherulite size, increased crystallization rate and improved the thermal stability of PP. These results confirmed the expected nucleant effect of CNT on the crystallization of PP. Scanning and transmission electron microscopy showed that the CNTs were dispersed homogeneously, indicating that the original CNT bundles were separated into individual tubes by the grafting.

  12. 丁二酸酐性能及各种生产工艺介绍%The Properties and Various Production Technology of Succinic Anhydride

    Institute of Scientific and Technical Information of China (English)

    潘玉莹; 李江; 胡利娜; 肖鹏飞

    2014-01-01

    Succinic anhydride was a kind of widely used and important fine chemical raw materials , especially its derivatives of high value -added fine chemical products , succinic anhydride production process in all the world mainly divided into succinic acid dehydration and maleic anhydride hydrogenated to succinic anhydride .The properties, the application and production technology of succinic anhydride , and comparison of production technology , maleic anhydride melting catalytic hydrogenated to succinic anhydride were mainly introduced , which was one of the most competitive and promising development method due to the cost of production and the comprehensive energy consumption was low .%丁二酸酐是一种重要的精细化工原料,用途广泛,尤其它的衍生物更是附加值高的精细化工产品,全球丁二酸酐的生产工艺主要有丁二酸脱水法、顺丁烯二酸酐催化加氢法。本文章主要介绍了丁二酸酐的性能、用途和生产工艺技术,并对生产工艺技术进行了比较,顺丁烯二酸酐熔融催化加氢法由于生产成本和综合能耗较低,是最具竞争力,发展前景看好的一种方法。

  13. One-pot synthesis of thermoplastic mixed paramylon esters using trifluoroacetic anhydride.

    Science.gov (United States)

    Shibakami, Motonari; Tsubouchi, Gen; Sohma, Mitsugu; Hayashi, Masahiro

    2015-03-30

    Mixed paramylon esters prepared from paramylon (a storage polysaccharide of Euglena), acetic acid, and a long-chain fatty acid by one-pot synthesis using trifluoroacetic anhydride as a promoter and solvent were shown to have thermoplasticity. Size exclusion chromatography indicated that the mixed paramylon esters had a weight average molecular weight of approximately 4.9-6.7×10(5). Thermal analysis showed that these esters were stable in terms of the glass transition temperature (>90°C) and 5% weight loss temperature (>320°C). The degree of substitution of the long alkyl chain group, a dominant factor determining thermoplasticity, was controlled by tuning the feed molar ratio of acetic acid and long-chain fatty acid to paramylon. These results implied that the one-pot synthesis is useful for preparing structurally-well defined thermoplastic mixed paramylon esters with high molecular weight. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Mixed Anhydride Intermediates in the Reaction of 5(4H)‐Oxazolones with Phosphate Esters and Nucleotides

    Science.gov (United States)

    Liu, Ziwei; Rigger, Lukas; Rossi, Jean‐Christophe; Sutherland, John D.

    2016-01-01

    Abstract 5(4H)‐Oxazolones can be formed through the activation of acylated α‐amino acids or of peptide C termini. They constitute potentially activated intermediates in the abiotic chemistry of peptides that preceded the origin of life or early stages of biology and are capable of yielding mixed carboxylic‐phosphoric anhydrides upon reaction with phosphate esters and nucleotides. Here, we present the results of a study aimed at investigating the chemistry that can be built through this interaction. As a matter of fact, the formation of mixed anhydrides with mononucleotides and nucleic acid models is shown to take place at positions involving a mono‐substituted phosphate group at the 3’‐ or 5’‐terminus but not at the internal phosphodiester linkages. In addition to the formation of mixed anhydrides, the subsequent intramolecular acyl or phosphoryl transfers taking place at the 3’‐terminus are considered to be particularly relevant to the common prebiotic chemistry of α‐amino acids and nucleotides. PMID:27534830

  15. Curing Behavior of Epoxy Asphalt

    Institute of Scientific and Technical Information of China (English)

    YU Jianying; CONG Peiliang; WU Shaopeng; CHENG Songbo

    2009-01-01

    The curing process of epoxy asphalt was analyzed by Fourier transform infrared (FT-IR)spectroscopy.Effect of curing temperature on viscosity of epoxy asphalt,and changes of mechanical properties with curing time were investigated.The evolution of concentration of epoxy band was followed as a function of the applied curing process.The experimental results indicate that the curing reaction rate of epoxy asphalt is invariable before 70 min at 120℃,and it decreases when curing time exceeds 70 min.The viscosity of epoxy asphalt increases slowly with curing time at initial curing stage.But it increases quickly after initial curing stage and the initial curing time decreases as the curing temperature increases.The tensile strength increases slowly at incipient curing stage and increases rapidly when curing time is form 20 min to 70 min.The elongation at break shows a decrease with curing time,but it exceeds 200%after cured.

  16. Epoxy/anhydride thermosets modified with end-capped star polymers with poly(ethyleneimine cores of different molecular weight and poly(ε–caprolactone arms

    Directory of Open Access Journals (Sweden)

    C. Acebo

    2015-09-01

    Full Text Available Multiarm star polymers, with a hyperbranched poly(ethyleneimine (PEI core and poly(ε-caprolactone (PCL arms end-capped with acetyl groups were synthesized by ring-opening polymerization of ε-caprolactone from PEI cores of different molecular weight. These star polymers were used as toughening agents for epoxy/anhydride thermosets. The curing process was studied by calorimetry, thermomechanical analysis and infrared spectroscopy. The final properties of the resulting materials were determined by thermal and mechanical tests. The addition of the star polymers led to an improvement up to 130% on impact strength and a reduction in the thermal stresses up to 55%. The structure and molecular weight of the modifier used affected the morphology of the resulting materials. Electron microscopy showed phase-separated morphologies with nano-sized fine particles well adhered to the epoxy/anhydride matrix when the higher molecular weight modifier was used.

  17. 马来酸酐改性聚乳酸对成骨细胞黏附、增殖和分化的研究%Effects of Maleic Anhydride-modified Poly(D,L-lactic acid) on the Adhesion,Proliferation and Differentiation of Osteoblasts

    Institute of Scientific and Technical Information of China (English)

    向燕; 王远亮; 罗彦凤; 张兵兵; 辛娟; 郑丹芳

    2011-01-01

    The main objective of this study was to observe the adhesion, proliferation and differentiation of mouse os-teblast-like MC3T3-E1 cells cultured on maleic anhydride-modified poly(D,L-lactic acid) (MPLA) and poly(D,L-lactic acid) (PDLLA) polymers, and to evaluate the cytocompatibility of MPLA polymer. The effects of MPLA and PDLLA polymers on the morphology, adhesion, proliferation, the content of total cellular protein, alkaline phospha-tase (ALP) activity and the content of Ca of MC3T3-E1 cells were explored. These results indicated that MC3T3-E1 cells on MPLA polymer adhered and spread more fully. On MPLA polymer, the proliferation, total protein content, ALP activity, Ca content of the cells were significantly higher than those of the cells on PDLLA polymer (P< 0. 01). It was concluded that MPLA polymer could promote the adhesion, spreading, proliferation and the synthesis of protein of osteoblasts, and also induced the differentiation and mineralization of osteoblasts, suggesting that MPLA polymer might have the better cytocompatibility than PDLLA.%通过研究马来酸酐改性聚乳酸(MPLA)和聚乳酸(PDLLA)材料表面对MC3T3-E1成骨细胞形态、黏附、增殖、细胞总蛋白含量、碱性磷酸酶活性及细胞分泌无机钙含量的影响,评价MPLA和PDLLA材料的细胞相容性.结果显示:与PDLLA相比,MPLA材料上的成骨细胞完全黏附和充分铺展;MPLA材料上细胞的增殖速率、细胞总蛋白含量、细胞碱性磷酸酶活性及细胞分泌的无机钙含量都显著高于PDLLA(P<0.01).这些结果说明,MPLA材料能促进MC3T3-E1成骨细胞的黏附、铺展、增殖及蛋白质的合成,并能促进成骨细胞的分化和矿化,与PDLLA材料相比具有更好的细胞相容性.

  18. Cure mechanisms in materials for use in esthetic dentistry.

    Science.gov (United States)

    Kwon, Tae-Yub; Bagheri, Rafat; Kim, Young K; Kim, Kyo-Han; Burrow, Michael F

    2012-02-01

    The current paper reviews the curing mechanisms found in resin-based materials used in dentistry. Historical aspects of dental products and the associated curing mechanisms are reviewed. In comparison with common industrial procedures, curing methods employed for dental materials are relatively limited because of the need to polymerize quickly in the oral cavity at an ambient temperature. Heat-cure and self-cure dental resins utilize benzoyl peroxide initiator alone with a tertiary amine co-initiator. At present, most dental restorative composites use a camphorquinone-amine complex initiation, visible light-cure, one-component systems, although alternative photoinitiators have been researched and developed. A multiple curing mode in a dual-cure material is a complex combination of various initiation systems. The use of aryl sulfinic acid sodium salt to overcome adverse chemical interactions between simplified adhesives and self- or dual-cure composites is based on another self-cure polymerization mechanism, sulfinic acid-initiated polymerization, proposed by Hagger in 1948. The sodium salt of aryl sulfinic acid reacts with an acidic monomer in simplified adhesives, and is believed to produce radicals. Clinically, it is important to try to optimize the degree of conversion of resin-based materials using proper manipulation and adequate light-curing techniques to ensure the best outcome for materials used to restore teeth.

  19. Effect of pasture on chestnut or acorn on fatty acid composition and aromatic profile of fat of Cinta Senese dry-cured ham

    Directory of Open Access Journals (Sweden)

    Franci, Oreste

    2009-07-01

    Full Text Available The objective of this study was to evaluate the effect of pasture on oak and chestnut grove on chemical and aromatic traits of Cinta Senese cured ham. Fifteen Cinta Senese barrows (124 kg of l.w. on average were allotted to three groups: one group (MI was reared outdoors in confined area and fed commercial feedstuff. The other two groups were raised under free-range conditions on acorn (AC or chestnut (CH woods. At slaughtering (148 kg of l.w. the right thighs were seasoned for 360 days, on average, to obtained cured hams. Results demonstrated that subcutaneous fat of ham of CH and AC groups, respect to CONC group, was the richest in MUFA (51.3 and 53.9 vs 49.5% respectively, because of the higher content of oleic acid (48.4 and 50.8 vs 46.2%, respectively. AC showed a lower percentage of PUFA than CH and CONC (13.8 vs 15.4 and 16.3%, respectively. As regard volatile compounds, AC, respect to CH and MI groups, showed the highest value of aldehydes (44.1 vs 30.3 and 33.5% respectively and ethers (4.04 vs 1.15 and 1.71% respectively.El objetivo de este estudio fue la evaluación de la composición de los ácidos grasos y de los compuestos volátiles del jamón curado Toscano obtenido de cerdos Cinta Senese alimentados con bellota, castaña o pienso. Quince cerdos de raza Cinta Senese fueron criados en extensivo: 5 fueron criados en bosque de bellota (AC, 5 en bosque de castaña (CH y 5 en un cercado y alimentados con pienso (MI. El día posterior al sacrificio se curaron los jamones. La composición de los ácidos grasos fue estadísticamente diferente entre los tipos de alimentación. La grasa de AC presentó el mayor porcentaje de AGMI total en comparación con CH y MI (51.3 y 53.9 vs 49.5% respectivamente gracias al mayor porcentaje de ácido oleico (48.4 y 50.8 vs 46.2%, respectivamente, y la menor de AGPI total (13.8 vs 15.4 y 16.3%, respectivamente. En relación a los compuestos volátiles, la grasa de AC, en comparación con CH y MI

  20. Study of the structure and the mechanical properties of dynamically cured PP/MAH-g-SEBS/epoxy blends

    Institute of Scientific and Technical Information of China (English)

    Xue Liang Jiang; Yin Xi Zhang

    2009-01-01

    A new method concerning with the simultaneous reinforcing and toughening of polypropylene (PP) was reported. Dynamical cure of the epoxy resin was successfully applied in the PP/maleic anhydride-grafted styrene--ethylene-butylene-styrene (SEBS) triblock copolymer, and the obtained blends named as dynamically cured PP/MAH-g-SEBS/epoxy blends. The stiffness and toughness of the blends are in a good balance, and MAH-g-SEBS was acted as not only an impact modifier but also a compatibilizer. The structure of the dynamically cured PP/MAH-g-SEBS/epoxy blends is the embedding of the epoxy particles by the MAH-gSEBS.

  1. Radiation curing of epoxies

    Science.gov (United States)

    Dickson, Lawrence W.; Singh, Ajit

    The literature on radiation polymerization of epoxy compounds has been reviewed to assess the potential use of radiation for curing these industrially important monomers. Chemical curing of epoxies may proceed by either cationic or anionic mechanisms depending on the nature of the curing agent, but most epoxies polymerize by cationic mechanisms under the influence of high-energy radiation. Radiation-induced cationic polymerization of epoxy compounds is inhibited by trace quantities of water because of proton transfer from the chain-propagating epoxy cation to water. Several different methods with potential for obtaining high molecular weight polymers by curing epoxies with high-energy radiation have been studied. Polymeric products with epoxy-like properties have been produced by radiation curing of epoxy oligomers with terminal acrylate groups and mixtures of epoxies with vinyl monomers. Both of these types of resin have good potential for industrial-scale curing by radiation treatment.

  2. Preparation, characterization and antibacterial activity of octenyl succinic anhydride modified inulin.

    Science.gov (United States)

    Zhang, Xiaoyun; Zhang, Ye-Wang; Zhang, Hongyin; Yang, Qiya; Wang, Haiying; Zhang, Guochao

    2015-01-01

    Octenyl succinic anhydride modified inulin (In-OSA) was synthesized via chemical modification of inulin with octenyl succinic anhydride (OSA). The esterification of inulin with OSA was confirmed by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and degree of substitution (DS) calculation. Antibacterial activity of In-OSA against Staphylococcus aureus and Escherichia coli was investigated by minimum inhibitory concentration (MIC) and inhibition rate determination. The results showed that inhibition rates against both E.coli and S. aureus increased with the increase of the In-OSA concentration. And the MICs against E. coli and S. aureus were 1% and 0.5% (w/v), respectively. The antibacterial mechanism was analyzed with the results of the proteins and nucleic acids leakage, SEM and negative staining transmission electron microscopy (TEM). Both the leakages of proteins and nucleic acids increased with the increase of the In-OSA concentration. The leakage occurred mainly in the early stage which indicated that cell membrane and wall were destroyed by In-OSA quickly. The images of SEM and negative staining TEM suggested that the cell membranes and cell walls of S. aureus were damaged more severely and even destroyed completely; but only pores appeared on the surface of E. coli.

  3. Design of a new, multi-purpose, light-curing adhesive comprising a silane coupling agent, acidic adhesive monomers and dithiooctanoate monomers for bonding to varied metal and dental ceramic materials.

    Science.gov (United States)

    Ikemura, Kunio; Tanaka, Hisaki; Fujii, Toshihide; Deguchi, Mikito; Negoro, Noriyuki; Endo, Takeshi; Kadoma, Yoshinori

    2011-01-01

    A newly designed, light-curing adhesive was investigated for its bonding effectiveness to porcelain, alumina, zirconia, Au, Au alloy, Ag alloy, Au-Ag-Pd alloy, and Ni-Cr alloy. Four experimental adhesives were prepared using varying contents of the following: a silane coupling agent [3-methacryloyloxypropyltriethoxysilane (3-MPTES)], acidic adhesive monomers [6-methacryloyloxyhexyl phosphonoacetate(6-MHPA),6-methacryloyloxyhexyl3-phosphonopropionate(6-MHPP)and 4-methacryloyloxyethoxycarbonylphthalic acid (4-MET)], and dithiooctanoate monomers [6-methacryloyloxyhexyl 6,8-dithiooctanoate (6-MHDT) and 10-methacryloyloxydecyl 6,8-dithiooctanoate (10-MDDT)]. After all adherend surfaces were sandblasted and applied with an experimental adhesive, shear bond strengths (SBSs) of a light-curing resin composite (Beautifil II, Shofu Inc., Kyoto, Japan) to the adherend materials after 2,000 times of thermal cycling were measured. For the experimental adhesive which contained 3-MPTES (30.0 wt%), 6-MHPA (1.0 wt%), 6-MHPP (1.0 wt%), 4-MET (1.0 wt%), 6-MHDT (0.5 wt%) and 10-MDDT (0.5 wt%), it consistently yielded the highest SBS for all adherend surfaces in the range of 20.8 (4.8)-30.3 (7.9) MPa, with no significant differences among all the adherend materials (p>0.05). Therefore, the newly designed, multi-purpose, light-curing adhesive was able to deliver high SBS to all the adherend materials tested.

  4. The Curing Meter

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    2006-01-01

    Curing technology concerns adjustment and control of temperature and moisture conditions in hardening structures and elements of concrete. The curing technology comprises e.g. measurement, adjustment and control of the moisture conditions during the early hardening phase of the concrete to achiev...... from concrete surfaces in the early hardening phase. The Concrete Curing Meter is designed for simple and reliable monitoring of water loss from a wet surface of fresh concrete. This new measuring technique has been tested with several prototypes of the Curing Meter....

  5. 聚乳酸接枝马来酸酐/丙烯酸丁酯共聚物的制备与性能∗%Preparation and properties of maleic anhydride/butyl acrylate grafted poly(lactic acid)copolymer

    Institute of Scientific and Technical Information of China (English)

    罗卫华; 袁彩霞; 王正良; 向世欢; 聂鹏; 袁光明

    2015-01-01

    Maleic anhydride (MAH)/butyl acrylate (BA)grafted poly(lactic acid)(PLA)copolymers (mPLAs) were prepared through solution grafting copolymerization using benzoyl peroxide as initiator,MAH and BA as monomers.The structure and properties of the graft copolymers were characterized by Fourier transform infra-red spectroscopy (FT-IR),wide-angle X-ray diffraction (WAXD),differential scanning calorimetry (DSC)and thermogravimetry (TG).The monomer graft degree on PLA first increases and then decreases with increasing mass ratio of BA to MAH.It reaches the highest value of 1.96% when the mass ratios of BA to MAH and MAH to PLA are 1/1 and 3/100 respectively.Compared with the pure PLA,mPLAs exhibit lower crystallinity and decreased thermal stability.A higher monomer graft degree was associated with a lower crystallinity of the samples.With the increase of mass ratio of BA to MAH,both the melting temperature and glass transition temperature of mPLAs have a trend of declining.%以马来酸酐(MAH)和丙烯酸丁酯(BA)为单体,通过溶液接枝法制备了聚乳酸(PLA )接枝MAH/BA共聚物(mPLA).使用红外光谱(FT-IR)、广角X 射线衍射(WAXD)、差示扫描量热仪(DSC)、热重分析仪(TG)研究了接枝共聚物的结构和性能.结果表明,随着单体质量比BA/MA H 的增加,单体在PLA 上的接枝率出现先增大后减小的趋势,当m(MAH)/m (BA )=1/1,m (MAH )/m (PLA )=3/100时,制备的 mPLA 接枝率最高为1.96%;与纯PLA相比,mPLA 的结晶度和热稳定性均比有所下降,且样品的接枝率越大其结晶度越低;随着单体中BA含量的增加,mPLA 的熔融温度和玻璃化转变温度有减小的趋势.

  6. The Curing Meter

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    2006-01-01

    Curing technology concerns adjustment and control of temperature and moisture conditions in hardening structures and elements of concrete. The curing technology comprises e.g. measurement, adjustment and control of the moisture conditions during the early hardening phase of the concrete to achiev...... from concrete surfaces in the early hardening phase. The Concrete Curing Meter is designed for simple and reliable monitoring of water loss from a wet surface of fresh concrete. This new measuring technique has been tested with several prototypes of the Curing Meter.......Curing technology concerns adjustment and control of temperature and moisture conditions in hardening structures and elements of concrete. The curing technology comprises e.g. measurement, adjustment and control of the moisture conditions during the early hardening phase of the concrete to achieve...... an optimal development of properties in the hardening concrete – so-called "moisture curing". Proper moisture curing is vital to concrete but laborious to accomplish and difficult to control at the construction site with present methods. This paper concerns a new method for site measurement of evaporation...

  7. Lysine adducts between methyltetrahydrophthalic anhydride and collagen in guinea pig lung.

    Science.gov (United States)

    Jönsson, B A; Wishnok, J S; Skipper, P L; Stillwell, W G; Tannenbaum, S R

    1995-11-01

    The formation of adducts between methyltetrahydrophthalic anhydride (MTHPA), an important industrial chemical and potent allergen, and collagen from guinea pig lung tissue was investigated. Collagen peptides were obtained from the lung tissue by homogenization, defatting, washing, and digestion with collagenase. In experiments in vitro, lung tissue was exposed to 8.4 mumol (50 microCi) of 14C MTHPA. The amount of adducts was 97 nmol MTHPA/g of wet tissue as determined from the bound radioactivity. In a study in vivo, four guinea pigs were injected intratracheally with 8.4 mumol of 14C MTHPA each. The amount of adducts was 0-1.2 nmol MTHPA/g of wet tissue (determined by bound radioactivity). N epsilon-methyltetrahydrophthaloyl-L-lysine (MTHPL) was synthesized and characterized by NMR, UV, and mass spectrometry (MS). A method to analyze MTHPL, after derivatization with methanol and pentafluorobenzoyl chloride, using gas chromatography-MS was developed. Analysis of Pronase-digested MTHPA-exposed lung tissue showed a concentration of 19 nmol MTHPL/g wet lung in vitro and between 0 and 0.15 nmol MTHPL/g wet lung in vivo. Thus, 20% in vitro and 12-15% in vivo of the bound radioactivity was found as adducts with lysine. These results are a first step toward studies of allergenic epitopes in proteins and methods for biological monitoring of exposure to acid anhydrides.

  8. Substituted Phthalic Anhydrides from Biobased Furanics: A New Approach to Renewable Aromatics.

    Science.gov (United States)

    Thiyagarajan, Shanmugam; Genuino, Homer C; Śliwa, Michał; van der Waal, Jan C; de Jong, Ed; van Haveren, Jacco; Weckhuysen, Bert M; Bruijnincx, Pieter C A; van Es, Daan S

    2015-09-21

    A novel route for the production of renewable aromatic chemicals, particularly substituted phthalic acid anhydrides, is presented. The classical two-step approach to furanics-derived aromatics via Diels-Alder (DA) aromatization has been modified into a three-step procedure to address the general issue of the reversible nature of the intermediate DA addition step. The new sequence involves DA addition, followed by a mild hydrogenation step to obtain a stable oxanorbornane intermediate in high yield and purity. Subsequent one-pot, liquid-phase dehydration and dehydrogenation of the hydrogenated adduct using a physical mixture of acidic zeolites or resins in combination with metal on a carbon support then allows aromatization with yields as high as 84 % of total aromatics under relatively mild conditions. The mechanism of the final aromatization reaction step unexpectedly involves a lactone as primary intermediate.

  9. Process of cleaning phthalic and maleic anhydrides from gases

    Energy Technology Data Exchange (ETDEWEB)

    Pavlovich, L.B.; Karbainov, A.D.; Morozkina, N.A.; Smokotin, N.E.; Syskin, V.A.

    1981-01-02

    A process is described for cleaning phthalic and maleic anhydrides from gases by oxidation of them at elevated temperature on a catalyst, being characterized by the fact that with the aim of simultaneously cleaning 1,4-naphthoquinone from the gases and simplifying the process, a vanadium slag of the following composition is used as the catalyst: (wt%) MnO 8-9, U/sub 2/O/sub 5/ 13-19, Tio 9-10 A1/sub 2/O/sub 3/ 1-4, Cr/sub 2/O/sub 3/ 7-9, phosphorus 0.05-0.1, SiO/sub 2/ 15-25, CaO 1.0-2.0, Mgo 0.5-1.5; FeO the remainder. The process can be used for catalytic cleaning from gases of organic substances, for example waste gases from phthalic anhydride production.

  10. Particleboard made from waste paper treated with maleic anhydride.

    Science.gov (United States)

    Nourbakhsh, Amir; Ashori, Alireza

    2010-01-01

    This study evaluates the usage of waste newspaper as a supplement raw material for laboratory-made single-layer particle-boards. The boards were made of various ratios (75/25, 50/50, 25/75 and 0/100) of waste paper flakes to wood particles mixtures (wt/wt). The effects of press temperature and maleic anhydride on the properties of the boards were determined. Evaluated properties were modulus of rupture, modulus of elasticity, internal bonding strength, and thickness swelling. Panels made from waste newspaper satisfied the modulus of rupture, modulus of elasticity and internal bonding strength requirements of European Norms standards. Performing a statistical analysis of the results, press temperature and maleic anhydride content were found to be positively effective on the mechanical properties at a 95% confidence level. The results from this study indicated that technically waste paper could be a potential substitute material for particleboard manufacture.

  11. Cationic concentration effects on electron beam cured of carbon-epoxy composites

    Science.gov (United States)

    Nishitsuji, D. A.; Marinucci, G.; Evora, M. C.; Silva, L. G. A.

    2010-03-01

    Electron beam (e-beam) curing is a technology that offers advantages over the thermal curing process, that usually requires high temperature and are time-consuming. E-beam curing is faster and occurs at low temperatures that help reduce residual mechanical stresses in a thermoset composite. The aim of the present study is to analyze the effects of cationic initiator (diaryliodonium hexafluoroantimonate) ranged from 1 to 3 wt% in DGEBA (diglycidyl ether of bisphenol A) epoxy resin when cured by a 1.5 MeV electron beam. The specimens were cured to a total dose of 200.4 kGy for 40 min. Analyses by dynamic mechanical thermal analysis (DMTA) and differential scanning calorimetry (DSC) show that the e-beam irradiated samples with 2 wt% cationic initiator were 96% cured obtained a glass transition temperature (tan δ) of 167 °C. The same epoxy resin, thermally cured for 16 h with an anhydride hardener, reached a Tg (tan δ) of 136 °C. So, the irradiated sample had its Tg increased approximately 20% and the curing process was much less time consuming.

  12. Cationic concentration effects on electron beam cured of carbon-epoxy composites

    Energy Technology Data Exchange (ETDEWEB)

    Nishitsuji, D.A., E-mail: delmo_amari@yahoo.com.b [Brazilian Navy Technological Center, Sao Paulo (Brazil); Marinucci, G. [Brazilian Navy Technological Center, Sao Paulo (Brazil); Energetic and Nuclear Research Institute-IPEN-CNEN/SP, Av. Prof. Lineu Prestes, 2242-Cidade Universitaria, 05508-000 Sao Paulo/SP (Brazil); Evora, M.C. [Institute of Advanced Studies/CTA, Sao Jose dos Campos/SP (Brazil); Silva, L.G.A. [Energetic and Nuclear Research Institute-IPEN-CNEN/SP, Av. Prof. Lineu Prestes, 2242-Cidade Universitaria, 05508-000 Sao Paulo/SP (Brazil)

    2010-03-15

    Electron beam (e-beam) curing is a technology that offers advantages over the thermal curing process, that usually requires high temperature and are time-consuming. E-beam curing is faster and occurs at low temperatures that help reduce residual mechanical stresses in a thermoset composite. The aim of the present study is to analyze the effects of cationic initiator (diaryliodonium hexafluoroantimonate) ranged from 1 to 3 wt% in DGEBA (diglycidyl ether of bisphenol A) epoxy resin when cured by a 1.5 MeV electron beam. The specimens were cured to a total dose of 200.4 kGy for 40 min. Analyses by dynamic mechanical thermal analysis (DMTA) and differential scanning calorimetry (DSC) show that the e-beam irradiated samples with 2 wt% cationic initiator were 96% cured obtained a glass transition temperature (tan delta) of 167 deg. C. The same epoxy resin, thermally cured for 16 h with an anhydride hardener, reached a T{sub g} (tan delta) of 136 deg. C. So, the irradiated sample had its T{sub g} increased approximately 20% and the curing process was much less time consuming.

  13. Microwave-assisted addition of azomethines to isatoic anhydride

    Indian Academy of Sciences (India)

    E Dominic Jacob; Lopez Mathew; Baby Thomas

    2007-01-01

    Diels-Alder addition of azomethines to isatoic anhydride in a solvent-free and eco-friendly condition is investigated using a microwave oven. The product is exclusively 2,3-diaryl-2,3-dihydroquinazolin-4(1H)-ones 4a-d. HOMO-LUMO energy of the iminoketene and the dienophiles were calculated using semi-empirical AM1 calculations.

  14. CHARACTERIZATION AND THERMAL STABILITY OF PMR POLYIMIDES USING 7-OXA-BICYCLO[2,2,1]HEPT-5-ENE-2, 3-DICARBOXYLIC ANHYDRIDE AS END CAPS

    Institute of Scientific and Technical Information of China (English)

    Chen-liang Gong; Yan-feng Li; Hai-xia Yang; Xiao-long Wang; Shu-jiang Zhang; Shi-yong Yanga

    2011-01-01

    An anhydride monomer containing ether oxide bridge,7-oxa-bicyclo[2,2,1]hept-5-ene-2,3-dicarboxylic anhydride (ONA),was successfully synthesized by Diels-Alder reaction of furan and maleic anhydride.The ONA was also studied as an end-cap for the polymerization of monomer reactant (PMR) type polyimides.Three molecular weight levels of the ONA end-capped PMR resins were evaluated.The effects of process conditions of these novel PMR resins on thermal and mechanical properties were investigated.It was demonstrated that the imidized prepolymers using the end-cap have good processability,and the cured polyimide specimens exhibited good thermal stability.The initial decomposition temperature,Td (ca.580℃) and glass transition temperature,Tg (330℃) of the novel resin (PI-20),prepared under optimum process conditions,compare favorably with the Td (ca.620℃) and Tg (ca.348℃) of the state-of-the-art resin (PI'-20),respectively.

  15. Rubber curing chemistry governing the orientation of layered silicate

    Directory of Open Access Journals (Sweden)

    2007-11-01

    Full Text Available The effect of curing systems on the orientation and the dispersion of the layered silicates in acrylonitrile butadiene rubber nanocomposite is reported. Significant differences in X-ray diffraction pattern between peroxide curing and sulfur curing was observed. Intense X-ray scattering values in the XRD experiments from peroxide cured vulcanizates indicate an orientation of the layers in a preferred direction as evinced by transmission electron micrographs. However, sulfur cured vulcanizates show no preferential orientation of the silicate particles. Nevertheless, a closer inspection of transmission electron microscopy (TEM images of peroxide and sulfur cured samples shows exfoliated silicate layers in the acrylonitrile butadiene rubber (NBR matrix. It was revealed in the prevailing study that the use of an excess amount of stearic acid in the formulation of the sulfur curing package leads to almost exfoliated type X-ray scattering pattern.

  16. C-CURE

    Data.gov (United States)

    US Agency for International Development — C-CURE system manages certain aspects of the access control system, including collecting employee and contractor names and photographs. The Office of Security uses...

  17. Curing of Concrete

    African Journals Online (AJOL)

    and pipes illustrate defects frequently caused by improper curing. Proper ... because in such pastes the layers of hydrated ... *3) When cement hydrates the solid products occupy a volume equal to the sum of volumes of anhydrous cement and.

  18. Blends of nitrile butadiene rubber/poly (vinyl chloride: The use of maleated anhydride castor oil based plasticizer

    Directory of Open Access Journals (Sweden)

    Indiah Ratna Dewi

    2016-06-01

    Full Text Available Recently, much attention has been focused on research to replace petroleum-based plasticizers, with biodegradable materials, such as biopolymer which offers competitive mechanical properties. In this study, castor oil was modified with maleic anhydride (MAH to produce bioplasticizer named maleated anhydride castor oil (MACO, and used in nitrile butadiene rubber (NBR/poly vinyl chloride (PVC blend. The effect of MACO on its cure characteristics and mechanical properties of NBR/PVC blend has been determined. The reactions were carried out at different castor oil (CO/xylene ratios, i.e. 1:0 and 1:1 by weight, and fixed CO/MAH ratio, 1:3 by mole. DOP, CO, and MACO were added into each NBR/PVC blend according to the formula. It was found that the viscosity and safe process level of NBR/PVC blend is similar from all plasticizer, however, MACO (1:0 showed the highest cure rate index (CRI. MACO-based plasticizer gave a higher value of the mechanical properties of the NBR/PVC blend as compared to DOP based plasticizer. MACO (1:1 based plasticizer showed a rather significance performance compared to another type of plasticizers both before and after aging. The value of hardness, elongation at break, tensile strength, and tear strength were 96 Shore A, 155.91 %, 19.15 MPa, and 74.47 MPa, respectively. From this result, NBR/PVC blends based on MACO plasticizer can potentially replace the DOP, and therefore, making the rubber blends eco-friendly.

  19. Effects of Amino Acid Fertilizer on Flue-cured Tobacco Fertilizer Reducing and Efficiency Increasing%氨基酸肥对烤烟减肥增效的作用

    Institute of Scientific and Technical Information of China (English)

    倪霞; 罗勇; 张燕; 金必志; 王云; 高松; 陶永萍; 查宏波; 游堂贵; 陆文林; 陈旭; 肖家繁; 陈淮

    2016-01-01

    [目的]探究氨基酸肥对烤烟生长发育和烟叶品质的影响。[方法]以云烟87为供试烤烟品种,采用同田对比的方式,设化学肥料(对照)、化学肥料+固态氨基酸肥、化学肥料+液态氨基酸肥3个处理,研究氨基酸肥对烤烟减肥增效的作用。[结果]施用固态氨基酸肥烤烟的农艺性状整体表现最好,液态氨基酸肥有利于烟株顶部叶片的开片;固态氨基酸肥处理的产量最高,而液态氨基酸肥处理的原烟外观质量最好,能提高均价和中上等烟比例,获得较好的经济效益。液态氨基酸肥处理的各部位烟叶糖碱比、双糖差均最适宜,化学成分协调性最好。与对照相比,氨基酸肥料处理的刺激性更小,余味更舒适,其中液态氨基酸肥处理的杂气较轻,感官质量整体表现最好。[结论]综合比较,施用化学肥料+液态氨基酸肥有助于促进烤烟生长发育和提高烟叶品质。%Objective] The aim was to explore effects of amino acid fertilizer on flue-cured tobacco growth, development and quality.[Meth-od] With Yunyan87 as tested flue-cured tobacco varieties, by means of the same field contrast, setting up three treatments:chemical fertilizer (control), chemical fertilizer+solid amino acid, chemical fertilizer+liquid amino acid, effects of amino acid fertilizer on flue-cured tobacco fertilizer reducing and efficiency increasing were studied.[ Result] Applying solid amino acid fertilizer, agronomic traits, yield had best per-formance; while applying liquid amino acid fertilizer, top leaf opening, raw tobacco appearance quality, mean price, proportion of middle and high quality tobacco, economic benefits, ratio of sugar and nicotine in tobacco leaves, disaccharide difference, coordination of chemical com-position had good performance.Compared with the control, tobacco treated by amino acid fertilizer had less irritating and more comfortable taste; tobacco treated

  20. Radiation curing in the eighties

    Energy Technology Data Exchange (ETDEWEB)

    Vrancken, A. (UCB, Drogenbos (Belgium). Chemical Specialities Div.)

    1984-05-01

    The subject is discussed under the headings: introduction; what is radiation curing; history; radiation curable resins (with properties of products); ultraviolet and electron beam curing; photoinitiation and the ultraviolet light curing process; electron beam curing (initiation; electron beam accelerators); end uses (graphic arts; wood finishing; paper upgrading; adhesives; metal finishing; electronic chemical; floor coatings).

  1. Enhanced Activity of Nanocrystalline Beta Zeolite for Acylation of Veratrole with Acetic Anhydride.

    Science.gov (United States)

    Aisha Mahmood Abdulkareem, Al-Turkustani; Selvin, Rosilda

    2016-04-01

    Friedel-Craft acylation of veratrole using homogeneous acid catalysts such as AlCl3, FeCl3, ZnCl2, and HF etc. produces acetoveratrone, (3',4'-dimethoxyacetophenone), which is the intermediate for synthesis of papavarine alkaloids. The problems associated with these homogeneous catalysts can be overcome by using heterogeneous solid catalysts. Since acetoveratrone is a larger molecule, large pore Beta zeolites with smaller particle sizes are beneficial for the liquid-phase acylation of veratrole, for easy diffusion of reactants and products. The present study aims in the acylation of veratrole with acetic anhydride using nanocrystalline Beta Zeolite catalyst. A systematic investigation of the effects of various reaction parameters was done. The catalysts were characterized for their structural features by using XRD, TEM and DLS analyses. The catalytic activity of nanocrystalline Beta zeolite was compared with commercial Beta zeolite for the acylation and was found that nanocrystalline Beta zeolite possessed superior activity.

  2. Poly(anhydride-esters) comprised exclusively of naturally occurring antimicrobials and EDTA: antioxidant and antibacterial activities.

    Science.gov (United States)

    Carbone-Howell, Ashley L; Stebbins, Nicholas D; Uhrich, Kathryn E

    2014-05-12

    Carvacrol, thymol, and eugenol are naturally occurring phenolic compounds known to possess antimicrobial activity against a range of bacteria, as well as antioxidant activity. Biodegradable poly(anhydride-esters) composed of an ethylenediaminetetraacetic acid (EDTA) backbone and antimicrobial pendant groups (i.e., carvacrol, thymol, or eugenol) were synthesized via solution polymerization. The resulting polymers were characterized to confirm their chemical composition and understand their thermal properties and molecular weight. In vitro release studies demonstrated that polymer hydrolytic degradation was complete after 16 days, resulting in the release of free antimicrobials and EDTA. Antioxidant and antibacterial assays determined that polymer release media exhibited bioactivity similar to that of free compound, demonstrating that polymer incorporation and subsequent release had no effect on activity. These polymers completely degrade into components that are biologically relevant and have the capability to promote preservation of consumer products in the food and personal care industries via antimicrobial and antioxidant pathways.

  3. N-甲酰-L-天冬氨酸酐的合成%Synthesis of N-Formyl-L-aspartic Anhydride

    Institute of Scientific and Technical Information of China (English)

    冷一欣; 芮新生; 马江权; 孙豪义; 周宏斌

    2001-01-01

    N-Formyl-L-aspartic anhydride was prepared by the reaction of L-aspartic acid and formic acid with magnesium oxide catalyst in acetic anhydride solvent.Effects of temperature,operation time and molar ratio of formic acid and acetic anhydride were discussed.The optimum operation conditions were temperature 50 ℃,operation time 5 h, molar ratio of formic acid to L-aspartic acid 1.6∶1.0 and molar ratio of acetic anhydride to L-aspartic acid 2.3∶1.0.The yield was 90.35%.%在乙酸酐溶剂中,以氧化镁为催化剂,L-天冬氨酸与甲酸进行甲酰化反应并脱水生成N-甲酰-L-天冬氨酸酐。考察了温度、时间、甲酸和乙酸酐用量比对反应的影响,得到了优化的反应条件为:反应温度50 ℃,反应时间5 h,甲酸与L-天冬氨酸的物质的量比为1.6∶1.0,乙酸酐与L-天冬氨酸的物质的量比为2.3∶1.0,此时产物收率达90.35%。

  4. Effect of Hops Beta Acids on the Survival of Unstressed- or Acid-Stress-Adapted-Listeria Monocytogenes and on the Quality and Sensory Attributes of Commercially Cured Ham Slices.

    Science.gov (United States)

    Wang, Li; McKeith, Amanda Gipe; Shen, Cangliang; Carter, Kelsey; Huff, Alyssa; McKeith, Russell; Zhang, Xinxia; Chen, Zhengxing

    2016-02-01

    This study evaluated the antilisterial activity of hops beta acids (HBA) and their impact on the quality and sensory attributes of ham. Commercially cured ham slices were inoculated with unstressed- and acid-stress-adapted (ASA)-L. monocytogenes (2.2 to 2.5 log CFU/cm(2) ), followed by no dipping (control), dipping in deionized (DI) water, or dipping in a 0.11% HBA solution. This was followed by vacuum or aerobic packaging and storage (7.2 °C, 35 or 20 d). Samples were taken periodically during storage to check for pH changes and analyze the microbial populations. Color measurements were obtained by dipping noninoculated ham slices in a 0.11% HBA solution, followed by vacuum packaging and storage (4.0 °C, 42 d). Sensory evaluations were performed on ham slices treated with 0.05% to 0.23% HBA solutions, followed by vacuum packaging and storage (4.0 °C, 30 d). HBA caused immediate reductions of 1.2 to 1.5 log CFU/cm(2) (P < 0.05) in unstressed- and ASA-L. monocytogenes populations on ham slices. During storage, the unstressed-L. monocytogenes populations on HBA-treated samples were 0.5 to 2.0 log CFU/cm(2) lower (P < 0.05) than control samples and those dipped in DI water. The lag-phase of the unstressed-L. monocytogenes population was extended from 3.396 to 7.125 d (control) to 7.194 to 10.920 d in the HBA-treated samples. However, the ASA-L. monocytogenes population showed resistance to HBA because they had a higher growth rate than control samples and had similar growth variables to DI water-treated samples during storage. Dipping in HBA solution did not adversely affect the color or sensory attributes of the ham slices stored in vacuum packages. These results are useful for helping ready-to-eat meat processors develop operational procedures for applying HBA on ham slices.

  5. Characterization of the curing agents used in epoxy resins with TG/FT-IR technique

    Directory of Open Access Journals (Sweden)

    Benedita M. V. Romão

    2006-06-01

    Full Text Available Samples of epoxy resin (EP based on the diglycidyl ether of bisphenol A (DGEBA, cured with nadic methyl anhydride (NMA and mercaptan (CAPCURE 3-800, or amine-phenol (CAPCURE EH-30, respectively, SE 4 and SE 5, were prepared in the stoichiometric ratio determined by the supplier. The curing behaviour of the epoxy systems SE 4 and SE 5 was followed by DSC (Differential Scanning Calorimetry. These SE and their ingredients were analyzed using FTIR transmission techniques (KBr pellets, pyrolysis without control and controlled pyrolysis-FT-IR, the CONTROLPIR/FT-IR for characterizing the curing agents (CA. The temperature range used for samples pyrolysis was found from TG (thermogravimetry. Thus, the FT-IR bands of liquid pyrolysate obtained by CONTROLPIR/FT-IR were evaluated, in comparison to the reference spectrum of CA. The characterization of CA was also possible, by the analysis of such SE with the TG/FT-IR technique.

  6. SYNTHESIS AND CHARACTERIZATION OF A NEW COMBLIKE POLYMER BASED ON POLY (VINYL METHYL ETHER-ALT-MALEIC ANHYDRIDE) BACKBONE

    Institute of Scientific and Technical Information of China (English)

    DING Liming; LIN Yunqing; ZHOU Zinan; NI Jianlong; CHEN Donglin

    1995-01-01

    A new comblike polymer host for polymer electrolyte was synthesized by reacting monomethyl ether of poly(ethylene glycol) with poly(vinyl methyl ether-alt-maleic anhydride) and endcapping the residual carboxylic acid with methanol. Butanone was selected as a solvent for the esterification in order to obtain a completely soluble product. The synthesis process was traced through by IR. Compared with the model compounds, the presumed structure of this comblike polymer has been proved to be valid by 13C NMR. The comb polymer is a white rubbery solid. It can be dissolved in butanone and THF, and manifests good film forming ability.

  7. An investigation on the effect of light cure and self cure composite resins on bonding strength of light cure glass ionomer to dentin (In-vitro

    Directory of Open Access Journals (Sweden)

    Pahlavan A

    2004-02-01

    Full Text Available Composite reins have recently become popular for posterior teeth restorations. Gap"nformation and subsequent microleakage are of the complications resulting from such restorations. One of the"ntechniques to overcome polymerization shrinkage of composite resins is sandwich technique (application of"nglass ionomer as a base beneath the composite resin. Since polymerization patterns in two types of composite"nresins (light cure and self cure differ from each other, various effects on the bond strength between glass"nionomer and dentin are expected."nPurpose: The aim of this in vitro study was to evaluate the effects of self- cure and light- cure composite"nresins in sandwich technique on the bond strength of light cure glass ionomer and dentin."nMaterials and Methods: 40 extracted human premolars were selected and divided into four groups:"nGroup 1: Light cure glass ionomer of 1mm thickness was placed on dentin."nGroup 2: 1mm thickness of light cure glass ionomer plus a mass of self cure composite resin of 2mm"nthickness were placed."nGroup 3: 1mm thickness of light cure glass ionomer plus light cure composite resin as two separate 1mm layer"nwere placed."nGroup 4: 1mm thickness of light cure glass ionomer with 37% phosphoric acid etching followed by two"nseparate layers of light cure composite resin of 1 mm thickness were placed."nSEM was used to determine gap size ai Gl- dentin and Gi- composite interlaces. The findings were analyzed"nby ANOVA and t-student tests."nResults: Groups 1 and 2 showed no gap at Gl-dentm interface and also cracks were not observed in all these"nspecimens. In group 3, there was gap between light cure GI and light cure composite resin and cracks were"nseen in GI, too. Group 4 showed gap at both interfaces and more cracks were seen in GI. Groups I and 2"nshowed the least gap formation and group 4 showed the most. Statistically significant difference was found"nbetween groups 3, 4 and group 1 (control, 2."nConclusion: Base

  8. Efficient synthesis of zinc-containing mesoporous silicas by microwave irradiation method and their high activities in acetylation of 1,2-dimethoxybenzene with acetic anhydride

    Directory of Open Access Journals (Sweden)

    K. Bachari

    2016-09-01

    Full Text Available A series of acid zinc-containing mesoporous materials have been synthesized by microwave irradiation method with different Si/Zn ratios (Si/Zn = 100, 65, 15 and characterized by several spectroscopic techniques such as: N2 physical adsorption, ICP, XRD, TEM, FT-IR and a temperature-programmed-desorption (TPD of pyridine. The liquid phase of acetylation of 1,2-dimethoxybenzene with acetic anhydride has been investigated over this series of catalysts. In fact, the catalyst Zn-JLU-15 (15 showed bigger performance in the acid-catalyzed acetylation of 1,2-dimethoxybenzene employing acetic anhydride as an acylating agent. Furthermore, the kinetics of the acetylation of 1,2-dimethoxybenzene over these catalysts have also been investigated.

  9. Mixed anhydrides (phosphoric-carboxyl) are also formed in the esterification of 5'-amp with n-acetylaminoacyl imidazolides - Implications regarding the origin of protein synthesis

    Science.gov (United States)

    Wickramasinghe, Nalinie S. M. D.; Lacey, James C., Jr.

    1992-01-01

    Procedure for the formation of aminoacyl esters of monoribonucleotides with aminoacyl imidazolides were first reported by Gottikh et al. (1970) and summarized in 1970. This reaction has been widely used by us and numbers of other workers as a convenient means of preparing aminoacyl esters of nucleotides. We have previously reported that, under conditions of excess imidazolide, large amounts of bis 2', 3' esters are formed in addition to the monoesters. However, to our knowledge, no one has reported that in addition to the esters, relatively large amounts of the mixed anhydride, with the amino acid carboxyl attached to the phosphate, are also formed at short reaction times. We report here on the relative amounts of anhydride and esters formed in this reaction of racemic mixtures of eleven N-acetyl amino acid imidazolides with 5'-AMP and discuss the relevance of the findings to the origin of protein synthesis.

  10. SYNTHESIS OF MESOPOROUS POLY(STYRENE-co-MALEIC ANHYDRIDE)/SILICA HYBRID MATERIALS VIA A NONSURFACTANT-TEMPLATED SOL-GEL PROCESS

    Institute of Scientific and Technical Information of China (English)

    Jie-bin Pang; Kun-yuan Qiu; Yen Wei

    2000-01-01

    Mesoporous poly(styrene-co-maleic anhydride)/silica hybrid materials have been prepared. The synthesis was achieved by the HCl-catalyzed sol-gel reactions of tetraethyl orthosilicate (TEOS) and styrene-maleic anhydride copolymer in the presence of 3-aminopropyl triethoxysilane (APTES) as a coupling agent and citric acid as a nonsurfactant template or pore-forming agent, followed by ethanol extraction. Characterization results from nitrogen sorption isotherms and powder Xray diffraction indicate that polymer-modified mesoporous materials with large specific surface areas (e.g. 900 m2/g) and pore volumes (e.g. 0.6 cm3/g) could be prepared. As the citric acid concentration is increased, the specific surface areas, pore volumes and pore diameters of the hybrid materials increase.

  11. Curing the queue

    NARCIS (Netherlands)

    Zonderland, Maartje Elisabeth

    2012-01-01

    In this dissertation we study several problems related to the management of healthcare and the cure of disease. In each chapter a hospital capacity distribution problem is analyzed using techniques from operations research, also known as mathematical decision theory. The problems considered are insp

  12. Light-Cured Self-Etch Adhesives Undergo Hydroxyapatite-Triggered Self-Cure.

    Science.gov (United States)

    Liu, Y; Bai, X; Liu, Y W; Wang, Y

    2016-03-01

    Light cure is a popular mode of curing for dental adhesives. However, it suffers from inadequate light delivery when the restoration site is less accessible, in which case a self-cure mechanism is desirable to salvage any compromised polymerization. We previously reported a novel self-cure system mediated by ethyl 4-(dimethylamino)-benzoate (4E) and hydroxyapatite (HAp). The present work aims to investigate if such self-cure phenomenon takes place in adhesives that underwent prior inadequate light cure and to elucidate if HAp released from the dental etching process is sufficient to trigger it. Model self-etch adhesives were formulated with various components, including bis[2-methacryloyloxy)ethyl]-phosphate (2MP) as acidic monomer and trimethylbenzoyl-diphenylphosphine oxide (TPO) as photoinitiator. In vitro evolution of degree of conversion (DC) of HAp-incorporated adhesives was monitored by infrared spectroscopy during light irradiation and dark storage. Selected adhesives were allowed to etch and extract HAp from enamel, light-cured in situ, and stored in the dark, after which Raman line mapping was used to obtain spatially resolved DC across the enamel-resin interface. Results showed that TPO+4E adhesives reached DC similar to TPO-only counterparts upon completion of light irradiation but underwent another round of initiation that boosted DC to ~100% regardless of HAp level or prior light exposure. When applied to enamel, TPO-only adhesives had ~80% DC in resin, which gradually descended to ~50% in enamel, whereas TPO+4E adhesives consistently scored ~80% DC across the enamel-resin interface. These observations suggest that polymerization of adhesives that underwent insufficient light cure is salvaged by the novel self-cure mechanism, and such salvaging effect can be triggered by HAp released from dental substrate during the etching process.

  13. MALEIC ANHYDRIDE HYDROGENATION OF PD/AL2O3 CATALYST UNDER SUPERCRITICAL CO2 MEDIUM

    Science.gov (United States)

    Hydrogenation of maleic anhydride (MA) to either y-butyrolactone of succinic anhydride over simple Pd/Al2O3 impregnated catalyst in supercritical CO2 medium has been studied at different temperatures and pressures. A comparison of the supercritical CO2 medium reaction with the c...

  14. TRIMELLITIC ANHYDRIDE-INDUCED EOSINOPHILIA IN A MURINE MODEL OF OCCUPATIONAL ASTHMA

    Science.gov (United States)

    TRIMELLITIC ANHYDRIDE-INDUCED EOSINOPHILIA IN A MURINE MODEL OF OCCUPATIONAL ASTHMA. J F Regal, ME Mohrman, E Boykin and D Sailstad. Dept. of Pharmacology, University of Minnesota, Duluth, MN, USA and NHEERL, ORD, US EPA, RTP, NC, USA.Trimellitic anhydride (TMA) is a small m...

  15. Telechelic polyisobutylene with unsaturated end groups and with anhydride end groups

    NARCIS (Netherlands)

    Walch, E.; Gaymans, R.J.

    1994-01-01

    Anhydride terminated polyisobutylene (PIB) oligomers were synthesized in a one- or two-step process from chlorine terminated oligomers. In the one-step process, chlorine functional oligomers were just heated in the presence of maleic anhydride (MA) for 12 h at 190°C without a catalyst. In the two-st

  16. Investigations on organolead compounds III. The reaction of organolead compounds with ketene. (Triphenylplumbyl)acetic anhydride

    NARCIS (Netherlands)

    Willemsens, L.C.; Kerk, G.J.M. van der

    1965-01-01

    The reaction of ketene with triphenyllead hydroxide in diethyl ether gave (triphenylplumbyl)acetic anhydride, (Ph3PbCH2CO)2O, the first anhydride-substituted organolead compound known. The reaction of ketene with triphenyllead acetate in absolute ethanol gave ethyl (triphenylplumbyl)acetate, Ph3PbCH

  17. 40 CFR 721.6183 - Amides, from ammonium hydroxide - maleic anhydride polymer and hydrogenated tallow alkyl amines...

    Science.gov (United States)

    2010-07-01

    ... - maleic anhydride polymer and hydrogenated tallow alkyl amines, sodium salts, compds. with ethanolamine... Substances § 721.6183 Amides, from ammonium hydroxide - maleic anhydride polymer and hydrogenated tallow... anhydride polymer and hydrogenated tallow alkyl amines, sodium salts, compds. with ethanolamine (PMN...

  18. Enrichment of dry-cured ham with α-linolenic acid and α-tocopherol by the use of linseed oil and α-tocopheryl acetate in pig diets.

    Science.gov (United States)

    Santos, C; Hoz, L; Cambero, M I; Cabeza, M C; Ordóñez, J A

    2008-11-01

    The use of α-linolenic acid and α-tocopherol enriched pork on the fatty acids and the sensory characteristics of Spanish dry-cured hams have been studied. Five batches of hams were manufactured using the posterior legs of pigs fed on diets with the same ingredients except for the oil source: sunflower (C), linseed (L) or linseed and olive (1/1, w/w, LO). Two different α-tocopheryl acetate concentrations [20 (C, L and LO) or 220 (LOE and LE)mg/kg diet] were used. Biceps femoris and Semitendinosus/Semimembranosus muscles from hams with low polyunsaturated fatty acid n-6/n-3 ratio (less than 3) were obtained from animals fed on linseed and linseed/olive oil enriched diets. However, hams from animals fed on diets added with linseed and α-tocopheryl acetate (20mg/kg diet) (batch L) were rejected by consumers because of less acceptable sensory characteristics and higher TBARs. The remaining hams had satisfactory sensory and nutritional characteristics.

  19. Hiccups: causes and cures.

    Science.gov (United States)

    Lewis, J H

    1985-12-01

    Hiccups result from a wide variety of conditions that act on the supraspinal hiccup center or that stimulate or disinhibit the limbs of its reflex arc. While scores of hiccup remedies have been reported over the centuries, no single "cure" stands out as being the most effective. Measures that stimulate the uvula or pharynx or disrupt diaphragmatic (respiratory) rhythm are simple to use and often help to speed the end of a bout of otherwise benign, self-limited hiccups. Such manueuvers may also terminate persistent hiccups. Drug therapy usually becomes necessary for more intractable hiccups; chlorpromazine and metoclopramide being two of the most widely employed agents for this purpose. Physical disruption of the phrenic nerve, hypnosis, and acupuncture are other modes of therapy that have been used in severe cases. Because so many reports of hiccup "cures" are based on anecdotal experience rather than controlled clinical studies, I review the available treatments to provide a rational approach for the management of hiccups.

  20. Facile Formation of Acetic Sulfuric Anhydride in a Supersonic Jet: Characterization by Microwave Spectroscopy and Computational Chemistry

    Science.gov (United States)

    Huff, Anna; Smith, CJ; Mackenzie, Becca; Leopold, Ken

    2017-06-01

    Sulfur trioxide and acetic acid are shown to react under supersonic jet conditions to form acetic sulfuric anhydride, CH_{3}COOSO_{2}OH. Rotational spectra of the parent, ^{34}S, methyl ^{13}C, and fully deuterated isotopologues have been observed by chirped-pulse and conventional cavity microwave spectroscopy. A and E internal rotation states have been observed for each isotopologue studied and the methyl group internal rotation barriers have been determined (241.043(65) \\wn for the parent species). The reaction is analogous to that of our previous report on the reaction of sulfur trioxide and formic acid. DFT and CCSD calculations are also presented which indicate that the reaction proceeds via a π_{2} + π_{2} + σ_{2} cycloaddition reaction. These results support our previous conjecture that the reaction of SO_{3} with carboxylic acids is both facile and general. Possible implications for atmospheric aerosol formation are discussed.

  1. Relationships of Non-volatile Organic Acids and Higher Fatty Acids in Flue-cured Tobacco with its Other Chemical Components and Smoking Quality%烤烟非挥发有机酸、高级脂肪酸与其他成分及其感官品质的关系

    Institute of Scientific and Technical Information of China (English)

    杜咏梅; 张怀宝; 付秋娟; 徐光军; 商耀; 林建胜

    2011-01-01

    The relationships of non-volatile organic acids and higher fatty acids with routine chemical components, calcium, neutral aroma components and sensory quality of tobacco were studied with 176 flue-cured tobacco samples. The results showed that; 1) Non-volatile organic acids and higher fatty acids closely related to major chemical indexes and aroma components, particularly malonic acid related to total nitrogen, malic acid to calcium, lactic acid to megastigmatrienone, palmitic acid to nicotine, geranylacetone, damascene and megastigmatrienone, linoleic acid + oleic acid to geranylacetone, with higher correlation coefficients and in scatter diagrams fitted to a straight line, or a quadratic, cubic or power curve. 2) The smoking quality of flue-cured tobacco was mainly influenced by malonic acid, oxalic acid, the ratio of total non-volatile organic acids to nicotine, the ratio of malic acid to citric acid, and calcium to malic acid, particularly, malonic acid and the ratio of total non-volatile organic acids to nicotine. The contents of palmiticacid and linoleic acid + oleic acid affected the flavor style and smoking quality significantly. The contents of palmitic acid and linoleic acid + oleic acid and the ratios of total non-volatile organic acids to nicotine and malic acid to citric acid in tobacco leaves of better quality were relatively higher, however, the contents of malonic acid and oxalic acid and the ratio of calcium to malic acid were relatively lower. The contents of palmitic acid and linoleic acid + oleic acid in thick flavor style tobacco were relatively lower.%研究了176份烤烟样品中的非挥发有机酸、高级脂肪酸含量与其常规化学成分、钙、中性致香成分和吸食品质的关系.结果表明:非挥发有机酸、高级脂肪酸均与烤烟主要化学指标及香气成分相关关系密切,尤其是丙二酸与总氮,苹果酸与钙、乳酸与巨豆三烯酮,棕榈酸与烟碱、香叶基丙酮、二氢大马酮、巨豆

  2. Acetylation of barnyardgrass starch with acetic anhydride under iodine catalysis.

    Science.gov (United States)

    Bartz, Josiane; Goebel, Jorge Tiago; Giovanaz, Marcos Antônio; Zavareze, Elessandra da Rosa; Schirmer, Manoel Artigas; Dias, Alvaro Renato Guerra

    2015-07-01

    Barnyardgrass (Echinochloa crus-galli) is an invasive plant that is difficult to control and is found in abundance as part of the waste of the paddy industry. In this study, barnyardgrass starch was extracted and studied to obtain a novel starch with potential food and non-food applications. We report some of the physicochemical, functional and morphological properties as well as the effect of modifying this starch with acetic anhydride by catalysis with 1, 5 or 10mM of iodine. The extent of the introduction of acetyl groups increased with increasing iodine levels as catalyst. The shape of the granules remained unaltered, but there were low levels of surface corrosion and the overall relative crystallinity decreased. The pasting temperature, enthalpy and other gelatinisation temperatures were reduced by the modification. There was an increase in the viscosity of the pastes, except for the peak viscosity, which was strongly reduced in 10mM iodine.

  3. Evaluation of copolymer conformation states of vinylchloride-maleic anhydride

    Science.gov (United States)

    Ivanov, A. A.

    2016-11-01

    The quantum-chemical analysis and experimental study of alternating vinylchloride-maleic anhydride (VC-MA) copolymer macromolecules with polymerization degree 600 have been carried out. The VC-MA copolymer in solvents of different nature undergoes cycloanhydride-enol tautomerism and the macromolecules take the form of corrugated sticks according to viscometric measurements. The computer simulation has shown that the segment with polymerization degree n < 18 (model compound) is not a helix and rolls while if n = 18 the conformations get distorted. The model molecule optimal structure comprising a random sequence of alternating units of comonomers and their enol tautomers with minimal system total energy has been found by the semiempirical parametric method PM3.

  4. Electronic Effects of Aluminum Complexes in the Copolymerization of Propylene Oxide with Tricyclic Anhydrides: Access to Well-Defined, Functionalizable Aliphatic Polyesters.

    Science.gov (United States)

    Van Zee, Nathan J; Sanford, Maria J; Coates, Geoffrey W

    2016-03-02

    The synthesis of well-defined and functionalizable aliphatic polyesters remains a key challenge in the advancement of emerging drug delivery and self-assembly technologies. Herein, we investigate the factors that influence the rates of undesirable transesterification and epimerization side reactions at high conversion in the copolymerization of tricyclic anhydrides with excess propylene oxide using aluminum salen catalysts. The structure of the tricyclic anhydride, the molar ratio of the aluminum catalyst to the nucleophilic cocatalyst, and the Lewis acidity of the aluminum catalyst all influence the rates of these side reactions. Optimal catalytic activity and selectivity against these side reactions requires a careful balance of all these factors. Effective suppression of undesirable transesterification and epimerization was achieved even with sterically unhindered monomers using a fluorinated aluminum salph complex with a substoichiometric amount of a nucleophilic cocatalyst. This process can be used to synthesize well-defined block copolymers via a sequential addition strategy.

  5. 大理烤烟苹果酸含量的空间变异分析%Spatial variability of malic acid content of flue-cured tobacco in Dali

    Institute of Scientific and Technical Information of China (English)

    周喜新; 周冀衡; 武德传; 樊在斗; 李文璧; 杨程

    2011-01-01

    采用GPS定位,在云南大理州主要烟区选取100个采样点,分别于2007、2008年采集C3F烤烟样品各100份.将各取样点2年烤烟样品苹果酸含量的平均值作为原始统计数据,对苹果酸含量的原始数据、对数转化和Box-Cox转换后的数据进行正态分布性检验,采用地统计学进行烤烟苹果酸含量的空间趋势和空间变异分析.结果表明:大理烤烟苹果酸含量经对数转换后服从正态分布,在进行普通Kriging插值时宜选择1阶趋势效应和指数理论模型;大理烤烟苹果酸含量具有中等的空间相关性和线性空间趋势效应;大理烤烟苹果酸含量为41.26~124.45 mg/g,平均含量为81.00 mg/g,背景值为65.01~80.00 mg/g,苹果酸含量最高(100.01~123.45 mg/g)的板块分布在南涧县、巍山县和弥渡县;大理州南部烟区烤烟苹果酸含量自南向北呈梯度状由高到低分布.%Dali flue-cured tobacco plays an important role in formula of several core cigarette brands. Malic acid is one of major nonvolatile organic acids of tobacco leaf, and it is one of common aroma additives for high-grade cigarettes, so researchers highly focus on tobacco malic acid. The objective of the study was to investigate spatial distribution of malic acid content of Dali flue-cured tobacco, and to provide references for layout of tobacco planting and using of tobacco leaf. The main tobacco planting areas in Dali were selected as the experiment sites. 200 flue-cured tobacco samples of C3F grade were collected from 100 sites in 2007 and 2008 via global position system (GPS). Malic acid contents of tobacco samples were determined. The mean value of tobacco malic acid content of samples in each site was regarded as the original data. The original data, data obtained after logarithmic transformation and Box-Cox transformation were tested for normal distribution. Surface trend and spatial distribution of tobacco malic acid content were analyzed by geostatistical

  6. Controlled Release of Damascone from Poly(styrene-co-maleic anhydride-based Bioconjugates in Functional Perfumery

    Directory of Open Access Journals (Sweden)

    Andreas Herrmann

    2013-02-01

    Full Text Available Poly(styrene-co-maleic anhydrides were modified with poly(propylene oxide (PO-co-ethylene oxide (EO side chains (Jeffamine® with different EO/PO molar ratios, varying between 0.11 and 3.60. These copolymers were then further functionalized with a β-mercapto ketone of δ-damascone. The obtained poly(maleic acid monoamide-based β-mercapto ketones were then studied as delivery systems for the controlled release of δ-damascone by retro 1,4-addition. The release of δ-damascone, a volatile, bioactive molecule of the family of rose ketones, was studied by dynamic headspace analysis above a cotton surface after deposition of a cationic surfactant containing fabric softening formulation, as a function of the ethylene oxide (EO/propylene oxide (PO molar ratio of the grafted copolymer side chains. The polarity of the EO/PO side chain influenced the release efficiency of the damascone in a typical fabric softening application. PO-rich copolymers and the corresponding poly(styrene-co-maleic anhydride without Jeffamine® side chains were found to be less efficient for the desired fragrance release than the corresponding bioconjugate with a EO/PO ratio of 3.60 in the side chain. This copolymer conjugate seemed to represent a suitable balance between hydrophilicity and hydrophobicity to favor the release of the δ-damascone and to improve the deposition of the conjugate from an aqueous environment onto a cotton surface.

  7. Plasma Polymerized Thin Films of Maleic Anhydride and 1,2-methylenedioxybenzene for Improving Adhesion to Carbon Surfaces

    DEFF Research Database (Denmark)

    Drews, Joanna Maria; Goutianos, Stergios; Kingshott, Peter

    2007-01-01

    Low power 2-phase AC plasma polymerization has been used to surface modify glassy carbon substrates that are used as an experimental model for carbon fibers in reinforced composites. In order to probe the role of carboxylic acid density on the interfacial adhesion strength a combination...... of different plasma powers and monomer compositions was used. Maleic anhydride (MAR) and 1,2-methylenedioxybenzene (MDOB) were plasma deposited separately and as mixtures to create layers with different surface compositions. In all cases the MAR was hydrolyzed to form carboxylic acid groups. Some carboxylic...... total veflectanc~ Fourier transform infrared spectroscopy. Atomic force microscopy was used to measure the thickness of the plasma films and to monitor the surface roughness for the different polymerization conditions. Finally, preliminary results of fracture energy measurements of the plasma modified...

  8. Modeling HIV Cure

    Science.gov (United States)

    Perelson, Alan; Conway, Jessica; Cao, Youfang

    A large effort is being made to find a means to cure HIV infection. I will present a dynamical model of post-treatment control (PTC) or ``functional cure'' of HIV-infection. Some patients treated with suppressive antiviral therapy have been taken off of therapy and then spontaneously control HIV infection such that the amount of virus in the circulation is maintained undetectable by clinical assays for years. The model explains PTC occurring in some patients by having a parameter regime in which the model exhibits bistability, with both a low and high steady state viral load being stable. The model makes a number of predictions about how to attain the low PTC steady state. Bistability in this model depends upon the immune response becoming exhausted when over stimulated. I will also present a generalization of the model in which immunotherapy can be used to reverse immune exhaustion and compare model predictions with experiments in SIV infected macaques given immunotherapy and then taken off of antiretroviral therapy. Lastly, if time permits, I will discuss one of the hurdles to true HIV eradication, latently infected cells, and present clinical trial data and a new model addressing pharmacological means of flushing out the latent reservoir. Supported by NIH Grants AI028433 and OD011095.

  9. A fully coupled diffusion-reaction scheme for moisture sorption-desorption in an anhydride-cured epoxy resin

    KAUST Repository

    El Yagoubi, Jalal

    2012-11-01

    Thermoset materials frequently display non-classical moisture sorption behaviors. In this paper, we investigated this issue from an experimental point of view as well as in terms of modeling the water transport. We used the gravimetric technique to monitor water uptake by epoxy samples, with several thicknesses exposed to different levels of humidity during absorption and desorption tests. Our results revealed that the polymer displays a two-stage behavior with a residual amount of water that is desorbed progressively. We proposed a phenomenological reaction-diffusion scheme to describe this behavior. The model describes water transport as a competition between diffusion and the reaction, during which the local diffusivity and solubility depend on the local advancement of the reaction. We then implemented our model using COMSOL Multiphysics and identified it using a MATLAB-COMSOL optimization tool and the experimental data. We discussed the relation between the hydrophilicity of the product of the reaction and the diffusion behavior. We examined the reaction-induced modification of the water concentration field. It is worth noting that part of the phenomenology can be explained by the presence of hydrolyzable groups. © 2012 Elsevier Ltd. All rights reserved.

  10. Synthesis and cure mechanism characterization of phenylethynyl-terminated imide oligomers

    Science.gov (United States)

    Back, Susanna Branion

    Polymer matrix composites (PMC) are being investigated by the Air Force for use in engine applications, which are comprised of an intermediate carbon fiber-reinforced high temperature phenylethynyl-terminated fluorinated polyimide resin. The high-temperature phenylethynyl-terminated fluorinated polyimide resin is prepared from 4-(phenylethynyl)phthalic anhydride (4-PEPA), p-phenylenediamine (p-PDA), and hexafluoroisopropylidene bisphthalic dianhydride (6FDA). In order for these materials to be exploited to their full potential, many fundamental aspects of the polymer system need to be better understood. For this study, the high-temperature cure mechanism, the chemical structures of cure reaction products, and the effect of physical properties of impurities in the 4-PEPA monomer were investigated. A phenylethynyl-terminated imide model compound, N-(3-phenoxybenzene)-4-phenylethynylphthalimide (N-PBPEP), was prepared using both industrial 4-PEPA and recrystallized 4-PEPA. The thermal cure of this low molecular weight compound was studied using a variety of analytical techniques including differential scanning calorimetry, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), and mass spectrometry (MS). N-PBPEP made from industrial 4-PEPA begins curing 25°C later than N-PBPEP made from recrystallized 4-PEPA, indicating that thermal cure is affected by the purity of the 4-PEPA starting material. Also, both versions form an 830 g/mol dimer with three possible mechanistic pathways.

  11. Curing mechanism of TDE-85/MeTHPA epoxy resin modified by polyurethane

    Institute of Scientific and Technical Information of China (English)

    LI Zhi-hua; ZHENG Zi-qiao; REN Dong-yan; HUANG Yao-peng

    2007-01-01

    Diglycidyl 4,5-epoxy tetrahydro phthalate/methyl tetrahydrophthalic anhydride (TDE-85/MeTHPA) epoxy resin modified by polyurethane (PU) was prepared with 1,4-butanediol (1,4-BDO), trimethylol propane (TMP) and polyurethane prepolymer synthesized by polypropylene glycol and toluene diisocynate. Chemical reaction and curing mechanism of this system were discussed by incorporating the results of infra spectrum analysis. The results indicate that the epoxy polymeric network Ⅰ is obtained by the curing reaction between TDE-85 and MeTHPA, while the PU polymeric network Ⅱ is obtained by the chain-extended and crosslinking reaction between 1,4-BDO, TMP and polyurethane prepolymer(PUP). The graft chemical bonds are formed between polymer networks Ⅰ and Ⅱ that therefore increase the degree of blend and compatibility between epoxy polymer and PU.

  12. Investigation of Plasma Polymerized Maleic Anhydride Film in a Middle Frequency Dielectric Barrier Discharge

    Institute of Scientific and Technical Information of China (English)

    TANG Wenjie; CHEN Qiang; ZHANG Yuefei; GE Yuanjing

    2008-01-01

    Plasma polymerized maleic anhydride (MA) was carried out by using maleic anhydride supersaturated ethanol solution as a precursor in a dielectric barrier discharge (DBD). The film properties were characterized by water contact angle (WCA), Fourier transfer infrared (FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM) analysis, and a thickness profilometer. The influence of the processing parameters on the film properties such as the power frequency, and polymerization zone was investigated. The results show that anhydride group incorporated into the growing films is favorable at the frequency of 80 kHz and working pressure of 50 Pa. The poly (maleic anhydride) film is uniform and compact at an average deposition rate of 8 nm/min.

  13. TRIMELLITIC ANHYDRIDE (TMA) HYPERSENSITIVITY IN MICE AFTER DERMAL AND INTRATRACHAEL (IT) EXPOSURES

    Science.gov (United States)

    ABSTRACT for 2001 DMS213TRIMELLITIC ANHYDRIDE (TMA) HYPERSENSITIVITY INMICE AFTER DERMAL AND INTRATRACHEAL (IT) EXPOSURES. E Boykin, M Ward, MJ Selgrade, and D Sailstad. NHEERL, ORD, US EPA, RTP, NC, USA.TMA causes respiratory hypersensitivity (RH) responses. W...

  14. Inhibitory effect of organic acid salts on spoilage flora in culture medium and cured cooked meat products under commercial manufacturing conditions.

    Science.gov (United States)

    Drosinos, Eleftherios H; Mataragas, Marios; Kampani, Aikaterini; Kritikos, Dimitrios; Metaxopoulos, Ioannis

    2006-05-01

    Lactobacillus curvatus, isolated from a spoiled vacuum-packaged 'pariza' type meat product, was used to inoculate modified MRS broth containing sodium lactate, sodium acetate and potassium sorbate in different concentrations, alone or in inter se combinations. Two commercial preparations (MIX 1 and MIX 2) were also used containing combinations of the above antimicrobials. Results from the preservatives addition to the culture medium showed highest antimicrobial activity in the case of the sodium lactate (2%, 3% or 4%), sodium acetate (0.5%) and potassium sorbate (0.15%) combination. Results from the preservatives addition to two types of thermally processed meats showed that sodium lactate and the combination of sodium lactate, sodium acetate and potassium sorbate were the most effective; extending the products shelf life an additional 10 days. Finally, MIX 1 and MIX 2 suppressed the lactic acid bacteria (LAB) growth in the culture medium but not in the final product.

  15. Butanol Alcoholysis of Succinic Anhydride Under Neutral Condition%中性条件下丁二酸酐的丁醇解

    Institute of Scientific and Technical Information of China (English)

    高艳萍; 张利萍

    2011-01-01

    Alcoholysis of succinic anhydride and n - butyl alcohol takes place without catalysts and the monobutyl succinie forms. The IR and MS spectra of the products are measured respectively. The factors such as the molar radio between succinic anhydride and n - butanol, raction time are discussed. The radio of succinic acid to n - butanol is 1:3 ,the reaction time is 2h, alcoholysis radio is up to 95.8% ;the reaction time is over 2.5h,succinic anhydride has been alcoholyzed and a little amount of dibutyl has formed.%丁二酸酐和正丁醇在无催化剂参与下,直接醇解生成丁二酸正丁单酯。用IR谱和MS谱分别对产物进行了结构表征。反应讨论了物质的量比、反应时间对醇解反应的影响。当酸酐与醇的物质的量比为1:3,反应2h时,酸酐醇解率已达到95.8%;反应2.5h以上时,酸酐完全醇解,并且有少量丁二酸二丁酯生成。

  16. Determination of the Preferred Structure, Dynamics, and Planarity of Substituted Anhydrides by Cp-Ftmw

    Science.gov (United States)

    McMahon, Timothy J.; Bailey, Josiah R.; Bird, Ryan G.; Pratt, David

    2016-06-01

    The planarity of five-membered rings is derived from a competition between ring-angle strain and stability of the torsional angles. The planar form maximizes the already stressed, smaller-than-normal, C-C bond angles, while puckering reduces the unfavorable eclipsed interactions. The structure, dynamics, and planarity of three anhydrides, succinic, methylsuccinic, and methylene (itaconic) anhydride, were studied and compared using chirped-pulse Fourier transform microwave spectroscopy.

  17. Grafting of chitosan as a biopolymer onto wool fabric using anhydride bridge and its antibacterial property.

    Science.gov (United States)

    Ranjbar-Mohammadi, Marziyeh; Arami, Mokhtar; Bahrami, Hajir; Mazaheri, Firoozmehr; Mahmoodi, Niyaz Mohammad

    2010-04-01

    Weak binding of chitosan on the wool constitutes the main problem in its application. In this paper, the surface modification of wool fabric using anhydrides to graft the chitosan was studied. Weight gain, antibacterial and antifelting properties of the chitosan grafted-acylated wool fabric were investigated. Wool fabrics were acylated with two anhydrides, succinic anhydride (SA) and phthalic anhydride (PA), using different solvents (dimethylsulfoxide (DMSO) and N,N-dimethyl formamide (DMF)). The effects of anhydrides, solvents, anhydride concentration, liquor ratio (L:R) and reaction time on acylation of wool were investigated. Chitosan was grafted to the acylated wool and the effects of pH, chitosan concentration, and reaction time on chitosan grafting of acylated wool were evaluated. Fourier transform infra-red (FTIR), scanning electron microscope (SEM), differential scanning colorimetry (DSC) and weight gain analyses provided evidence that chitosan was grafted on to the acylated wool through the formation of new covalent bonds. The grafted samples have antibacterial potential due to existence of the antibacterial property of chitosan. In addition, the chitosan grafted-acylated wool samples have antifelting property. The findings of this research support the potential production of new environmentally friendly textile fabrics. Copyright (c) 2009 Elsevier B.V. All rights reserved.

  18. Preliminary report of rice to cure acid type soil conditioner%水稻施用治酸型土壤调理剂试验初报

    Institute of Scientific and Technical Information of China (English)

    魏之茂; 陈金洪; 高敏

    2014-01-01

    Unreasonable application of fertilizer, potential negative impacts on the environment and the quality of agro-ecological agricultural soils, water resources and other atmospheric become one source of pollution of rural surface major cause. Through the using of governance in Guangxi Tiandeng acid soil amendment applied comparative tests on rice, the growth and economic conditions of rice have good performance. The effect of increasing production is obvious.%化肥的不合理施用,对土壤、水资源大气等农业生态环境和农产品质造成潜在的负面影响,成为我国农村面源污染的主要诱因之一。通过在广西天等县利用治酸型土壤调理剂对水稻施用的对比试验,水稻的生长发育及经济性状表现良好,增产增收效果明显。

  19. Structural properties of pepsin-solubilized collagen acylated by lauroyl chloride along with succinic anhydride.

    Science.gov (United States)

    Li, Conghu; Tian, Zhenhua; Liu, Wentao; Li, Guoying

    2015-10-01

    The structural properties of pepsin-solubilized calf skin collagen acylated by lauroyl chloride along with succinic anhydride were investigated in this paper. Compared with native collagen, acylated collagen retained the unique triple helix conformation, as determined by amino acid analysis, circular dichroism and X-ray diffraction. Meanwhile, the thermostability of acylated collagen using thermogravimetric measurements was enhanced as the residual weight increased by 5%. With the temperature increased from 25 to 115 °C, the secondary structure of native and acylated collagens using Fourier transform infrared spectroscopy measurements was destroyed since the intensity of the major amide bands decreased and the positions of the major amide bands shifted to lower wavenumber, respectively. Meanwhile, two-dimensional correlation spectroscopy revealed that the most sensitive bands for acylated and native collagens were amide I and II bands, respectively. Additionally, the corresponding order of the groups between native and acylated collagens was different and the correlation degree for acylated collagen was weaker than that of native collagen, suggesting that temperature played a small influence on the conformation of acylated collagen, which might be concluded that the hydrophobic interaction improved the thermostability of collagen.

  20. An efficient acetylation of dextran using in situ activated acetic anhydride with iodine

    Directory of Open Access Journals (Sweden)

    MUHAMMAD A. HUSSAIN

    2010-02-01

    Full Text Available A facile, efficient, cost-effective and solvent-free acetylation method has been developed for the acetylation of dextran. Dextran acetates were successfully synthesized using different molar ratios of acetic anhydride in the presence of iodine as a catalyst without the use of any solvent. The reactions were realized at 50 °C for 3 h under stirring and nitrogen. This efficient method yielded highly pure and organosoluble dextran esters. The reaction appears highly effective for obtaining higher degrees of substitution (DS with great efficiency. Under solvent-free conditions, dextran triacetates were efficiently synthesized. It was also observed that the molar ratio can easily control the DS of pendant groups onto the polymer backbone. Hence, a range of products with varying DS were successfully designed, purified and characterized. Covalent attachment of the pendant groups onto the polymer backbone was verified by spectroscopic techniques. Thermogravimetric analysis indicated that the obtained dextran esters were thermally as stable as dextran. The DS of the pendant groups onto the polymer backbone was calculated using standard acid base titration after saponification. Furthermore, all products were thoroughly characterized by thermal analysis (TG and DTG, and FTIR and 1H-NMR spectroscopic analysis.

  1. The effect of gamma radiation on the ageing of sulfur cured nr/csm and nbr/csm rubber blends reinforced by carbon black

    Directory of Open Access Journals (Sweden)

    Gordana Marković

    2009-10-01

    Full Text Available In this work the effect of the γ-radiation dose on ageing of carbon black reinforced elastomeric materials was studied. The compounds based on natural rubber/chlorosulfonated rubber blend (NR/CSM and butadiene acrylonitrile rubber/chlorosulfonated rubber blend (NBR/CSM (50:50, w/w with different loadings (0, 20, 40, 50, 60, 80 and 100 phr of the filler with the average particle size of 40 nm were cured by sulfur. The obtained elastomeric composites were subjected to radiation doses (100, 200, 300 and 400 kGy in the presence of oxygen. The changes of material mechanical properties were estimated after radiation accelerated ageing. By using Fourier transform infrared measurements (ATR-FTIR it was assessed that after exposure to doses of 100 kGy alcohols, ethers, lactones, anhydrides, esters and carboxylic acids are formed in materials. The formation of shorter polyene sequences and aromatic rings in aged samples are assumed on the basis of the obtained spectra.

  2. Placental stem cells pre-treated with a hyaluronan mixed ester of butyric and retinoic acid to cure infarcted pig hearts: a multimodal study.

    Science.gov (United States)

    Simioniuc, Anca; Campan, Manuela; Lionetti, Vincenzo; Marinelli, Martina; Aquaro, Giovanni D; Cavallini, Claudia; Valente, Sabrina; Di Silvestre, Dario; Cantoni, Silvia; Bernini, Fabio; Simi, Claudia; Pardini, Silvia; Mauri, Pierluigi; Neglia, Danilo; Ventura, Carlo; Pasquinelli, Gianandrea; Recchia, Fabio A

    2011-06-01

    Pre-treating placenta-derived human mesenchymal stem cells (FMhMSCs) with a hyaluronan mixed ester of butyric and retinoic acid (HBR) potentiates their reparative capacity in rodent hearts. Our aim was to test FMhMSCs in a large-animal model by employing a novel combination of in vivo and ex vivo analyses. Matched regional quantifications of myocardial function and viability were performed by magnetic resonance imaging (MRI) and positron emission tomography (PET) 4 weeks after myocardial infarction combined with intramyocardial injection of FMhMSCs (n = 7), or HBR-pre-treated FMhMSCs (HBR-FMhMSCs, n = 6), or saline solution (PBS, n = 7). Sham-operated pigs (n = 4) were used as control animals. Despite no differences in the ejection fraction and haemodynamics, regional MRI revealed, in pigs treated with HBR-FMhMSCs compared with the other infarcted groups, a 40% smaller infarct scar size and a significant improvement of the end-systolic wall thickening and circumferential shortening of the infarct border zone. Consistently, PET showed that myocardial perfusion and glucose uptake were, respectively, 35 and 23% higher in the border zone of pigs treated with HBR-FMhMSCs compared with the other infarcted groups. Histology supported in vivo imaging; the delivery of HBR-FMhMSCs significantly enhanced capillary density and decreased fibrous tissue by approximately 68%. Moreover, proteomic analysis of the border zone in the HBR-FMhMSCs group and the FMhMSCs group indicated, respectively, 45 and 30% phenotypic homology with healthy tissue, while this homology was only 26% in the border zone of the PBS group. Our results support a more pronounced reparative potential of HBR-pre-treated FMhMSCs in a clinically relevant animal model of infarction and highlight the necessity of using combined diagnostic imaging to avoid underestimations of stem cell therapeutic effects in the heart.

  3. Effects of postharvest curing treatment on flesh colour and phenolic metabolism in fresh-cut potato products.

    Science.gov (United States)

    Wang, Qingguo; Cao, Yu; Zhou, Lili; Jiang, Cai-Zhong; Feng, Yanyan; Wei, Shaochong

    2015-02-15

    The flesh colour and phenolic metabolism in potato tuber during curing and after cut were investigated. Result indicated that postharvest curing not only changed phenolic metabolism during curing, but also improved fresh-cut colour for 12 days after fresh cut. Significantly lower PAL and higher phenolic content and PPO activities during curing treatment and fresh-cut potatoes were detected compared to the control, which lead to the lower browning in the slices from curing treated potatoes. HPLC analysis revealed that amounts of total phenolics, chlorogenic acid, gallic acid and protocatechuic acid were induced by curing and highly accumulated in the curing treated potatoes. Our results demonstrated that phenolic metabolism played an important role in the control of browning of fresh cut potato after curing.

  4. Controversies in HIV cure research

    Directory of Open Access Journals (Sweden)

    Johnston Rowena

    2012-03-01

    Full Text Available Abstract Background Antiretroviral therapy significantly reduces HIV viral burden and prolongs life, but does not cure HIV infection. The major scientific barrier to a cure is thought to be the persistence of the virus in cellular and/or anatomical reservoirs. Discussion Most efforts to date, including pharmaco, immuno or gene therapy, have failed to cure patients, with the notable exception of a stem cell transplant recipient commonly known as the Berlin patient. This case has revived interest in the potential to cure HIV infection and has highlighted the need to resolve critical questions in the basic, pre-clinical and clinical research spheres as they pertain specifically to efforts to eradicate HIV from the body of an infected person (a sterilizing cure or at least render the need for lifelong antiretroviral therapy obsolete (functional cure. This paper describes ongoing debates in each of these research spheres as they were presented and discussed at a satellite session that took place at the 6th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention in Rome in July 2011. Summary The resolution of these debates may have important implications for the search for a cure, the most efficient ways to identify and test promising interventions, and ultimately the availability of such a cure to diverse groups of HIV patients around the world.

  5. Mixture proportioning for internal curing

    DEFF Research Database (Denmark)

    Bentz, Dale P.; Pietro, Lura; Roberts, John W.

    2005-01-01

    hydration and strength development, reduced autogenous shrinkage and cracking, reduced permeability, and increased durability. The impact of internal curing begins immediately with the initial hydration of the cement, with benefits that are observed at ages as early as two days. Internal curing...

  6. Immunosuppression of the Trimellitic Anhydride-Induced Th2 Response by Novel Nonanatural Products Mixture in Mice

    Directory of Open Access Journals (Sweden)

    Min-Jung Bae

    2013-01-01

    Full Text Available Many natural dietary products prevent or cure allergic inflammation; however, the ability of mixtures of these natural medicinals to suppress allergic skin inflammation is unknown. We examined the inhibitory effects of nonanatural products mixture (NPM-9, which provides immunoregulatory activation, on Th2-mediated skin allergic inflammation. Oral administration of NPM-9 in mice reduced ear thickness and specific IgE production in trimellitic anhydride- (TMA-induced contact hypersensitivity (CHS. NPM-9 also suppressed IL-4 and IL-1β production in splenocytes but prevented only TMA-induced IL-1β production in inflamed ears. To characterize the mechanism of this effect, we examined NPM-9 immunosuppression on an OVA-induced Th2 allergic state. Oral administration of NPM-9 inhibited Th2-mediated serum IgE overproduction. NPM-9 also downregulated the polarized Th2 response, whereas it upregulated Th1 response in splenocytes. These data suggest that NPM-9 may be a useful therapeutic agent for allergic inflammatory diseases through its suppression of the Th2-mediated allergic response.

  7. CURING EFFICIENCY OF DUAL-CURE RESIN CEMENT UNDER ZIRCONIA WITH TWO DIFFERENT LIGHT CURING UNITS

    Directory of Open Access Journals (Sweden)

    Pınar GÜLTEKİN

    2015-04-01

    Full Text Available Purpose: Adequate polymerization is a crucial factor in obtaining optimal physical properties and a satisfying clinical performance from composite resin materials. The aim of this study was to evaluate the polymerization efficiency of dual-cure resin cement cured with two different light curing units under zirconia structures having differing thicknesses. Materials and Methods: 4 zirconia discs framework in 4 mm diameter and in 0.5 mm, 1 mm and 1.5 mm thickness were prepared using computer-aided design system. One of the 0.5 mm-thick substructures was left as mono-layered whereas others were layered with feldspathic porcelain of same thickness and ceramic samples with 4 different thicknesses (0.5, 1, 1.5 and 2.0 mm were prepared. For each group (n=12 resin cement was light cured in polytetrafluoroethylene molds using Light Emitting Diode (LED or Quartz-Tungsten Halogen (QHT light curing units under each of 4 zirconia based discs (n=96. The values of depth of cure (in mm and the Vickers Hardness Number values (VHN were evaluated for each specimen. Results: The use of LED curing unit produced a greater depth of cure compared to QTH under ceramic discs with 0.5 and 1 mm thickness (p<0.05.At 100μm and 300 μm depth, the LED unit produced significantly greater VHN values compared to the QTH unit (p<0.05. At 500 μm depth, the difference between the VHN values of LED and QTH groups were not statistically significant. Conclusion: Light curing may not result in adequate resin cement polymerization under thick zirconia structures. LED light sources should be preferred over QTH for curing dual-cure resin cements, especially for those under thicker zirconia restorations.

  8. Selective hydrogenation of maleic anhydride over Pd/Al2O3 catalysts prepared via colloid deposition

    Indian Academy of Sciences (India)

    Hongjing Yuan; Chunlei Zhang; Weitao Huo; Chunli Ning; Yong Tang; Yi Zhang; Dequan Cong; Wenxiang Zhang; Jiahuan Luo; Su Li; Zhenlu Wang

    2014-01-01

    Pd/Al2O3 catalysts were prepared via colloid deposition and the performance of the catalysts was examined in the selective hydrogenation of maleic anhydride to succinic anhydride. When the reaction was carried on in a batch system with 1,4-dioxane as the solvent (353K and 1.0MPa), high conversion of maleic anhydride (>98%) and high selectivity (>99%) for succinic anhydride were observed after 5 h. The as-prepared Pd/Al2O3 catalyst also showed excellent performance in solvent-free system and fixed-bed systems. The maleic anhydride (MA) conversion was greater than 98%, and high selectivity (>99%) for succinic anhydride was obtained after 1600 h in a fixed bed reacter. The results showed that the activity of the Pd/Al2O3 catalysts was excellent due to its high active surface area.

  9. The effect of light curing units, curing time, and veneering materials on resin cement microhardness

    Directory of Open Access Journals (Sweden)

    Nurcan Ozakar Ilday

    2013-06-01

    Conclusion: Light-curing units, curing time, and veneering materials are important factors for achieving adequate dual cure resin composite microhardness. High-intensity light and longer curing times resulted in the highest microhardness values.

  10. Towards an HIV cure

    Directory of Open Access Journals (Sweden)

    Steven Deeks

    2014-11-01

    Full Text Available Given the challenge of delivering complex, expensive and potentially harmful antiretroviral therapy (ART on a global level, there is intense interest in the development of short-term, well-tolerated regimens that allow individuals to interrupt therapy indefinitely without experiencing a rebound in viremia. This so-called “cure” or “remission” might be due to complete eradication of all replication-competent HIV during ART or durable host-mediated control of persistent virus in absence of ART. Recent heroic interventions such as hematopoietic stem cell transplant and very early initiation of antiretroviral therapy suggest that dramatic reductions in the reservoir size can be achieved, but that complete eradication will be difficult if not impossible to achieve. Most attempts to stimulate effective host-mediated control of HIV have failed. It is likely that for a true cure to be achieved, both approaches – reductions in the reservoir size and durable immune surveillance – will be needed, a state that is similar to that observed in “elite” controllers and post-treatment controllers. The implications for recent advances and setbacks in achieving HIV remission for future research priorities will be discussed.

  11. Towards a 'cure' for IBD.

    Science.gov (United States)

    Fiocchi, Claudio

    2012-01-01

    To discuss a cure for IBD, one should first define the concept 'a cure'. If it is intended as the general restoration of health, this is already possible, as many current therapies do a good job in inducing long periods of remission in Crohn's disease, and colectomy can technically cure ulcerative colitis. If it is more strictly defined as the complete and permanent elimination of the cause, predisposing and permissive factors, reinstatement of normal microbial ecology and restoration of mucosal immune homeostasis, then a cure for IBD is out of reach, at least for now. Regardless of the definition, major strides have been made in attempting to cure IBD by addressing the key components of its pathogenesis: the environment (exposome), the genetic makeup (genome), the gut microbiota (microbiome) and the immune system (immunome). However, the isolated modulation of each component is insufficient to provide a cure, and different requirements may be needed depending on the stage of the disease and each patient subset. To achieve a cure, one key approach is currently missing: the integration of knowledge from all the pathogenic components. We continue to learn more and more about each component using traditional 'canonical' systems, which allow the accumulation of data without taking into consideration the other components. We are still not studying the 'omes' of IBD, we should be using 'omics' technologies that can generate a more global vision of IBD pathogenesis on which to base novel, multiple pathway-integrated therapies. Copyright © 2012 S. Karger AG, Basel.

  12. Micro-leakage of a Fissure Sealant Cured Using Quartz-tungsten-halogen and Plasma Arc Light Curing Units.

    Science.gov (United States)

    Bahrololoomi, Zahra; Soleimani, Ali Asghar; Jafari, Najmeh; Varkesh, Bentolhoda

    2014-01-01

    Background and aims. Newer curing units such as plasma arc can polymerize the sealants in much shorter curing times. The aim of this study was to compare the effect of two different curing units on the micro-leakage of a fissure sealant material. Materials and methods. Sixty two extracted premolars without caries were randomly divided into two groups of 31 samples. Occlusal surfaces of all teeth were cleansed. Then, teeth surfaces were etched by 37% phosphoric acid. After rinsing and drying, occlusal surfaces of teeth were sealed by a fissure sealant. The sealant was then cured using either a halogen light curing unit or a plasma arc curing light. After sealing, the teeth were thermocycled for 500 cycles. The teeth were then sectioned and examined for micro-leakage. Statistical analyses were performed with Mann-Whitney test. Results. There was no significant difference between two groups regarding micro-leakage (P = 0.42). Conclusion. Results showed that there was no significant difference between two different curing units. Therefore, plasma arc unit might be a useful alternative for sealant polymerization.

  13. Performance of maleated castor oil based plasticizer on rubber: rheology and curing characteristic studies

    Science.gov (United States)

    Indrajati, I. N.; Dewi, I. R.

    2017-07-01

    The objective of this study was to evaluate the performance of maleated castor oil (MACO) as plasticizer on natural rubber (NR), ethylene propylene diene monomer (EPDM), and nitrile butadiene rubber (NBR). The parameter studied were involving rheological, curing and swelling properties. The MACOs were prepared by an esterification reaction between castor oil (CO) and maleic anhydride (MAH) with the help of xylene as water entrainer to improve water removal. Resulting oils then applied as a plasticizer in each of those rubbers within a fixed loading of 5 phr. Comparison has been made to evaluate the performance of MACO and conventional plasticizer (paraffinic oil for NR and EPDM, DOP for NBR) on each rubber. Rheology, curing characteristic and swelling of each rubber were studied. The results showed that rubber (NR/EPDM/NBR) plasticized with MACO had given similar flow characteristic to conventional plasticizers. MACO exhibited slow curing, confirmed by higher t90, but the scorch safety was of the same magnitude. MAH loading tended to decrease the flow properties and curing rate, while scorch time (ts2) was independent.

  14. Curing efficacy of light emitting diodes of dental curing units

    Directory of Open Access Journals (Sweden)

    Seyd Mostafa Mousavinasab

    2009-03-01

    Full Text Available Background and aims. The aim of the present study was to compare the efficacy of quartz tungsten halogen (QTH and light emitting diode (LED curing lights on polymerization of resin composite. Materials and Methods. A hybrid resin composite was used to prepare samples which were cured using two QTH and ten LED light curing sources. Twelve groups, each containing ten samples, were prepared using each light source. The cured depth of the resin was determined using ISO 4049 method and Vickers hardness values were determined at 1.0 mm intervals. Data was analyzed by ANOVA and Tukey test. Results. Data analysis demonstrated a significant difference between light sources for depth of cure. At 1.0 mm below the surface all the tested light sources and at 2.0-mm intervals all light sources except two (Optilux 501 and LEDemetron I and at 3.0-mm intervals only two light sources (PenCure and LEDemetron II could produce hardness values higher than 80% of superficial layer values. Conclusion. This study showed that a variety of LED light sources used in the present study are as effective as the high-intensity QTH lights in polymerization of resin composite.

  15. Syntheses of {gamma}-aminobutyric-1-{sup 14}C and of {alpha}-aminoadipic-6-{sup 14}C acid from methoxy-3 chloropropyl-magnesium and marked carbon dioxide; Syntheses de l'acide {gamma}-aminobutyrique{sup 14}C-1 et de l'acide {alpha}-aminoadipique {sup 14}C-6 a partir de methoxy-3 chloropropylmagnesium et d'anhydride carbonique marque

    Energy Technology Data Exchange (ETDEWEB)

    Phung Nhu Liem [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires, Departement des radioelements, Service des molecules marquees

    1967-04-01

    Carbonation of {gamma}-methoxypropyl-magnesium chloride by CO{sub 2} gives {gamma}-methoxy-butyric carboxylic-{sup 14}C acid with a yield of about 95 per cent. When the latter is treated successively with anhydrous HBr and with diazomethane, methyl carboxylic {gamma}-bromobutyrate-{sup 14}C is formed. This in turn gives {gamma}-amino-butyric carboxylic-{sup 14}C acid with an overall yield of 66 per cent with respect to Ba{sup 14}CO{sub 3}, when it is condensed with potassium phthalimide and hydrolyzed by acid. By reacting methyl-{gamma}-bromobutyrate-{sup 14}C with the sodium derivative of ethyl cyanacetamido-acetate in ethanol, followed by an acid hydrolysis, {alpha}-aminoadipic-6-{sup 14}C acid is obtained with an overall yield of 46 per cent with respect to Ba{sup 14}CO{sub 3}. (author) [French] La carbonatation du chlorure de {gamma}-methoxypropylmagnesium par {sup 14}CO{sub 2} donne l'acide {gamma}-methoxybutyrique carboxyle {sup 14}C avec un rendement d'environ 95 pour cent. Ce dernier traite successivement par HBr anhydre et par le diazomethane conduit au {gamma}-bromobutyrate de methyle carboxyle {sup 14}C. Celui-ci condense avec le phtalimide de potassium suivi d'une hydrolyse acide fournit l'acide {gamma}-aminobutyrique carboxyle {sup 14}C avec un rendement global de 66 pour cent par rapport a Ba{sup 14}CO{sub 3}. L'action du {gamma}-bromobutyrate de methyle {sup 14}C sur le derive sode du cyanacetamidoacetate d'ethyle dans l'ethanol suivie d'hydrolyse acide donne l'acide {alpha}-aminoadipique {sup 14}C-6 avec un rendement global de 46 pour cent par rapport a Ba{sup 14}CO{sub 3}. (auteur)

  16. Novel techniques for concrete curing

    DEFF Research Database (Denmark)

    Kovler, Konstantin; Jensen, Ole Mejlhede

    2005-01-01

    It is known that some high-strength/high-performance concretes (HSC/HPC) are prone to cracking at an early age unless special precautions are taken. The paper deals with the methods of curing as one of the main strategies to ensure good performance of concrete. Curing by both external (conventional......) and internal methods is reviewed and analyzed, among other methods of mitigating shrinkage and cracking of concrete. The focus is on the mitigation of autogenous shrinkage of low water to binder ratio (w/b) concrete by means of internal curing. The concepts of internal curing are based on using lightweight...... aggregate, superabsorbent polymers or water-soluble chemicals, which reduce water evaporation (so called "internal sealing"). These concepts have been intensively researched in the 90s, but still are not widespread among contractors and concrete suppliers. The differences between conventional methods...

  17. Correlation of cure monitoring techniques

    Science.gov (United States)

    Chang, S. S.; Mopsik, F. I.; Hunston, D. L.

    Six different composite matrix or neat resin cure-monitoring methods are presently used to follow the cure process in a model epoxy system, and the results obtained are compared. Differential scanning calorimetry, viscosity monitoring, the ultrasonic shear wave propagation technique, dielectric spectrometry, and two different fluorescence intensity techniques are compared with a view to common traits and differences. Dielectric fluorescence and ultrasonic measurement techniques are noted to be applicable to on-line process monitoring.

  18. Curing units' ability to cure restorative composites and dual-cured composite cements under composite overlay.

    Science.gov (United States)

    Park, Sung-Ho; Kim, Su-Sun; Cho, Yong-Sik; Lee, Chang-Kyu; Noh, Byng-Duk

    2004-01-01

    This study compared the efficacy of using conventional low-power density QTH (LQTH) units, high-power density QTH (HQTH) units, argon (Ar) laser and Plasma arc curing (PAC) units for curing dual-cured resin cements and restorative resin composites under a pre-cured resin composite overlay. The microhardness of the two types of restorative resins (Z100 and Tetric Ceram) and a dual-cured resin cement (Variolink II) were measured after they were light cured for 60 seconds in a 2 mm Teflon mold. The recorded microhardness was determined to be the optimum microhard-ness (OM). Either one of the two types of restorative resins (Z100, Tetric Ceram) or the dual cured resin cement (Variolink II) were placed under a 1.5-mm thick and 8 mm diameter pre-cured Targis (Vivadent/Ivoclar AG, Schaan, Liechtenstein) overlay. The specimens that were prepared for each material were divided into four groups depending upon the curing units used (HQTH, PAC, Laser or LQTH) and were further subdi-vided into subgroups according to light curing time. The curing times used were 30, 60, 90 and 120 seconds for HQTH; 12, 24, 36 and 48 seconds for the PAC unit; 15, 30, 45 and 60 for the Laser and 60, 120 or 180 seconds for the LQTH unit. Fifteen specimens were assigned to each sub- group. The microhardness of the upper and and lower composite surfaces under the Targis overlay were measured using an Optidur Vickers hardness-measuring instrument (Göttfert Feinwerktechnik GmbH, Buchen, Germany). In each material, for each group, a three-way ANOVA with Tukey was used at the 0.05 level of significance to compare the microhardnesses of the upper and lower composite surfaces and the previously measured OM of the material. From the OM of each material, 80% OM was calculated and the time required for the microhardness of the upper and lower surface of the specimen to reach 100% and 80% of OM was determined. In Z100 and Tetric Ceram, when the composites were light cured for 120 seconds using the HQTH lamp

  19. Selective oxidation of carbon monoxide in the presence of butane and maleic anhydride

    Energy Technology Data Exchange (ETDEWEB)

    Corbin, D.R.; Bonifaz, C. (DuPont Company, Wilmington, DE (United States))

    1994-03-01

    The selective oxidation of carbon monoxide in the presence of butane and maleic anhydride has been studied over platinum- and palladium-containing zeolites as well as palladium-on-silica (Pd/SiO[sub 2]) catalysts. The results show that although a zeolite support is needed in many systems to effect a kinetic control to improve selectivity, thermodynamic control using Pd([approximately]2-4 ppm)/SiO[sub 2] is sufficient to give the desired selectivities in this system. In addition, a palladium-containing vanadium-phosphate catalyst was prepared that showed complete oxidation of carbon monoxide, conversion of butane to maleic anhydride, and no observable decomposition of the maleic anhydride. 14 refs., 4 tabs.

  20. Solid—Liquid Equilibria of Several Binary and Ternary Systems Containing Meleic Anhydride

    Institute of Scientific and Technical Information of China (English)

    MAPeisheng; CHENMingming; 等

    2002-01-01

    Solid-liquid equilibria(SLE) of three binary systems and seven ternary systems containing maleic anhydride(MA) are measured by visual method. The experimental data are compared with the calculated ones with modified universal quasichemical functional group activity coefficient(UNIFAC) method in which the interaction parameters between groups come from two sources,dortmund data bank (DDB), if there′s any,and correlations based on our former presented experimental SLE data of twenty binary systems.New groups of MA,ACCOO group,COO group,>C=O group and cy-CH2 group are defined and the SLE data of maleic anhydride in isopropyl acetate in literature are cited in order to assess the new interaction parameters,correlated with Wilson equation and the λh equation.The modified UNIFAC method with these new regressed interaction parameters is also used to predict other three binary systems containing maleic anhydride.

  1. Crystal structure of 2,3-di-methyl-maleic anhydride: continuous chains of electrostatic attraction.

    Science.gov (United States)

    Wiscons, Ren A; Zeller, Matthias; Rowsell, Jesse L C

    2015-08-01

    In the crystal structure of 2,3-di-methyl-maleic anhydride, C6H6O3, the closest non-bonding inter-molecular distances, between the carbonyl C and O atoms of neighboring mol-ecules, were measured as 2.9054 (11) and 3.0509 (11) Å, which are well below the sum of the van der Waals radii for these atoms. These close contacts, as well as packing motifs similar to that of the title compound, were also found in the crystal structure of maleic anhydride itself and other 2,3-disubstituted maleic anhydrides. Computational modeling suggests that this close contact is caused by strong electrostatic inter-actions between the carbonyl C and O atoms.

  2. Collagen functionalized with unsaturated cyclic anhydrides-interactions in solution and solid state.

    Science.gov (United States)

    Potorac, S; Popa, M; Picton, L; Dulong, V; Verestiuc, L; Le Cerf, D

    2014-03-01

    Maleic anhydride (CMA) and itaconic anhydride modified collagen (CITA) were prepared as precursors for production of interpenetrated polymer networks (IPN). Calculated values for Huggins coefficient in aqueous diluted and semi-diluted solutions of modified collagen indicated a slightly tendency of aggregation for itaconic anhydride-modified collagen. In semi-diluted solution collagen (Coll) and CMA present slightly differences in the thixotropic behavior, while CITA has a pronounced thixotropic behavior. Flow and oscillatory measurements revealed an elastic behavior of the collagen solutions, pure and modified with MA or ITA, as the storage modulus (G') has always a superior value compared with the loss modulus (G″). The denaturation temperature (Td) of unmodified collagen increased from 34°C to 40°C for CMA and to 39°C for CITA respectively, by formation of covalent bonds that stabilize the triple helix.

  3. Synthesis of first row transition metal carboxylate complexes by ring opening reactions of cyclic anhydrides

    Indian Academy of Sciences (India)

    Jubaraj Bikash Baruah

    2011-03-01

    Hydrolytic and solvolytic ring opening reactions of phthalic anhydride, pyromellitic dianhydride and 2,3-pyridine dicarboxylic anhydride in the presence of various transition metal salts with or without a ancillary ligands were studied. The reactions were found to be dependent on stoichiometry of ligand and types of anhydride used. In the case of pyromellitic dianhydride selective ring opening reaction by cobalt(II) ions gave 1,3-benzene dicarboxylate derivatives, whereas use of copper(II) ions gave 1,4-benzene dicarboxylate derivatives. Preference for methanolysis was seen in the case of copper (II) promoted reactions of pyromellitic dianhydride in the presence of 1:1 metal to 1,10-phenanthroline ratio.

  4. [Studies on the characters and microstructure of enzyme and octenyl succinic anhydride modified starch].

    Science.gov (United States)

    Zhang, Xue-chun; Zheng, Wei-wan; Tu, Zong-cai; Lin, Hong-hui; Wang, Zhen-xing; Kong, Ling-wei

    2010-11-01

    Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), UV-Vis spectra, laser nano size detector (LNSD) and scanning electron microscope (SEM) were employed to analyze the characters and structure of enzyme and octenyl succinic anhydride modified starch. The results indicated that the enzymatic starch reacted with octenyl succinic anhydride, bringing only octenyl succinic anhydride groups but not any other groups. The esterification of enzymatic starch only took place in amorphous region, but had no effect on the crystal form of starch granule. The clarity of EOSS increased with the increase in substitution degree. The particle size of oil emulsion made by EOSS was fine and well-distributed, meaning that the emulsion has excellent emulsibility and emulsifying stability. The embedding of oil encapsulated with EOSS is fine. It can be concluded that the properties of EOSS is excellent, and can be used as emulsifier and wall material of microcapsule.

  5. Comparison of Catalysts Preyssler and Silica-Supported Nano Preyssler in the Synthesis of Acetyl Salicylic Acid

    OpenAIRE

    Nazari, H.; Ahmadpour, A.; Bamoharram, F. F.; Heravi, M. M.; Eslami, N.

    2012-01-01

    The extensive demand for cleaner environment is forcing chemical industry to use less hazardous materials. In this regard, heteropolyacids attracted considerable amount of interest due to the less toxic behavior in addition of possessing higher acidity. Heteropoly acids have been used as catalysts for the reaction of salicylic acid with acetic anhydride. The performance of different forms of heteropoly acids in the presence of acetic anhydride as acetylating agent for acetylation of salicylic...

  6. Changes in asthma-like responses after extended removal from exposure to trimellitic anhydride in the Brown Norway rat model.

    Science.gov (United States)

    Zhang, X D; Hubbs, A F; Siegel, P D

    2009-11-01

    Organic acid anhydride-induced occupational asthma is considered to be IgE-mediated. Airway and skin exposure are the two main routes of sensitization in the work place. Recently we developed an allergic asthmatic Brown Norway rat model sensitized by dermal exposure to trimellitic anhydride (TMA) using an occlusion patch application. The objectives of this study were (1) to develop a model of non-occluded dermal exposure leading to allergic sensitization and (2) to examine the effect of extended removal from exposure on persistence of both specific IgE and TMA aerosol-induced airway responses in this model. TMA powder (4 or 40 mg) was applied, unoccluded, to the skin of rats for 4 h, once/week for 4 weeks. Rats were given a 10-min aerosol challenge to 40 mg/m(3) TMA 2 weeks after the last dermal exposure (day 35). Another group was challenged on day 35 and again 18-24 months later. Respiratory enhanced pause (Penh), pulmonary histopathology and inflammation and specific IgE titres were measured. Rats produced dose-dependent specific IgE titres after exposure and developed early-phase (EAR) and late-phase airway responses (LAR) after airway challenge to TMA aerosol as well as airway eosinophilic inflammation. Specific airway responses were still manifested after a second TMA airway challenge given 18-24 months following the initial airway challenge. While persistent, airway inflammation, specific IgE and EAR were significantly attenuated following the second TMA challenge. LAR remained robust at 18-24 months and was not significantly different from the response on day 35. These results demonstrate the persistence of chemical sensitization and further suggest that IgE is not essential for LAR.

  7. Cold-Curing Structural Epoxy Resins: Analysis of the Curing Reaction as a Function of Curing Time and Thickness

    Directory of Open Access Journals (Sweden)

    Carola Esposito Corcione

    2014-09-01

    Full Text Available The curing reaction of a commercial cold-curing structural epoxy resin, specifically formulated for civil engineering applications, was analyzed by thermal analysis as a function of the curing time and the sample thickness. Original and remarkable results regarding the effects of curing time on the glass transition temperature and on the residual heat of reaction of the cold-cured epoxy were obtained. The influence of the sample thickness on the curing reaction of the cold-cured resin was also deeply investigated. A highly exothermal reaction, based on a self-activated frontal polymerization reaction, was supposed and verified trough a suitable temperature signal acquisition system, specifically realized for this measurement. This is one of the first studies carried out on the curing behavior of these peculiar cold-cured epoxy resins as a function of curing time and thickness.

  8. Cold-Curing Structural Epoxy Resins: Analysis of the Curing Reaction as a Function of Curing Time and Thickness.

    Science.gov (United States)

    Corcione, Carola Esposito; Freuli, Fabrizio; Frigione, Mariaenrica

    2014-09-22

    The curing reaction of a commercial cold-curing structural epoxy resin, specifically formulated for civil engineering applications, was analyzed by thermal analysis as a function of the curing time and the sample thickness. Original and remarkable results regarding the effects of curing time on the glass transition temperature and on the residual heat of reaction of the cold-cured epoxy were obtained. The influence of the sample thickness on the curing reaction of the cold-cured resin was also deeply investigated. A highly exothermal reaction, based on a self-activated frontal polymerization reaction, was supposed and verified trough a suitable temperature signal acquisition system, specifically realized for this measurement. This is one of the first studies carried out on the curing behavior of these peculiar cold-cured epoxy resins as a function of curing time and thickness.

  9. Thermal curing of PBI membranes for high temperature PEM fuel cells

    DEFF Research Database (Denmark)

    Aili, David; Cleemann, Lars N.; Li, Qingfeng

    2012-01-01

    to solubility, phosphoric acid doping, radical-oxidative resistance and mechanical strength indicated that the PBI membranes were irreversibly cured by the thermal treatment. After curing, the PBI membranes demonstrated features that are fundamental characteristics of a thermoset resin including complete...... insolubility, high resistance to swelling and improved mechanical toughness. Additionally, the thermal treatment was found to increase the degree of crystallinity of the membranes. The improved physicochemical characteristics of the membranes after curing were further illustrated by a dramatically improved...

  10. Structural properties of pepsin-solubilized collagen acylated by lauroyl chloride along with succinic anhydride

    Energy Technology Data Exchange (ETDEWEB)

    Li, Conghu [The Key Laboratory of Leather Chemistry and Engineering of Ministry of Education, Sichuan University, Chengdu 610065 (China); College of Life Sciences, Anqing Normal University, Anqing 246011 (China); Tian, Zhenhua; Liu, Wentao [The Key Laboratory of Leather Chemistry and Engineering of Ministry of Education, Sichuan University, Chengdu 610065 (China); Li, Guoying, E-mail: liguoyings@163.com [The Key Laboratory of Leather Chemistry and Engineering of Ministry of Education, Sichuan University, Chengdu 610065 (China)

    2015-10-01

    The structural properties of pepsin-solubilized calf skin collagen acylated by lauroyl chloride along with succinic anhydride were investigated in this paper. Compared with native collagen, acylated collagen retained the unique triple helix conformation, as determined by amino acid analysis, circular dichroism and X-ray diffraction. Meanwhile, the thermostability of acylated collagen using thermogravimetric measurements was enhanced as the residual weight increased by 5%. With the temperature increased from 25 to 115 °C, the secondary structure of native and acylated collagens using Fourier transform infrared spectroscopy measurements was destroyed since the intensity of the major amide bands decreased and the positions of the major amide bands shifted to lower wavenumber, respectively. Meanwhile, two-dimensional correlation spectroscopy revealed that the most sensitive bands for acylated and native collagens were amide I and II bands, respectively. Additionally, the corresponding order of the groups between native and acylated collagens was different and the correlation degree for acylated collagen was weaker than that of native collagen, suggesting that temperature played a small influence on the conformation of acylated collagen, which might be concluded that the hydrophobic interaction improved the thermostability of collagen. - Highlights: • Acylated collagen retained the unique triple helix conformation. • Acylated collagen had stronger thermostability than native collagen. • Amide I was the most sensitive band to the temperature for acylated collagen. • Amide II was the most sensitive band to the temperature for native collagen. • Auto-peak at 1680 cm{sup −1} for acylated collagen disappeared at higher temperature.

  11. Influence of the degree of hydrolysis of poly(styrene-alt-maleic anhydride) on miscibility with poly(vinyl acetate)

    NARCIS (Netherlands)

    Bosma, M.; Vorenkamp, E.J.; Brinke, G. ten; Challa, G.

    1988-01-01

    The influence of the hydrolysis of anhydride groups in poly(styrene-alt-maleic anhydride) (PSMA) on its miscibility with poly(vinyl acetate) (PVAc) is investigated. The cloudpoint curves of these blends are determined as a function of the degree of hydrolysis. The miscibility is shown to improve wit

  12. Enhancement of Adhesion between EPDM and Polyester Fabric by Using Natural Rubber Modified by Maleic Anhydride

    Directory of Open Access Journals (Sweden)

    A. A. El-Wakil

    2011-01-01

    Full Text Available This study presents a new method for improving adhesion between ethylene propylene diene monomer (EPDM rubber and polyester fabric. In this work, natural rubber was modified by maleic anhydride in order to improve the adhesion force between ethylene propylene diene monomer rubber and polyester fabric. The effect of thermal aging and ionizing radiation on the stability of the rubber mix as well as on the peel strength of the rubber-coated fabric was investigated. It was observed that the natural rubber modified by maleic anhydride improved the peel strength of the EPDM rubber-coated polyester fabric.

  13. Solvent-free esterification of poly(vinyl alcohol) and maleic anhydride through mechanochemical reaction

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A solid-state mechanochemical processing, that is, pan-milling, was used to conduct the esterification of poly(vinyl alcohol)(PVA) with maleic anhydride (MA) through stress-induced reaction. FTIR spectrum study indicated the presence of ester linkages and olefinic double bonds in maleic anhydride cross-linked PVA. Thermal properties of the cross-linked product were characterized by DSC. The results showed its glass transition temperature was 20 ℃ higher than the original linear PVA and the thermal stability was also improved.

  14. CATALYSIS OF POLYSTYRENE N-HYDROXYL SULFONAMIDE FOR ESTERIFICATION OF BUTANOL WITH ACETIC ANHYDRIDE

    Institute of Scientific and Technical Information of China (English)

    LI Shufeng; LI Qian; YANG Xinlin; HUANG Wenqiang

    2004-01-01

    Polystyrene N-hydroxyl sulfonamide resin 1 was prepared and used to catalyze the esterification of n-butanol and acetic anhydride. The mechanism of catalytic esterification proved by IR spectra of the resins was found that O-H and N-H of the N-hydroxyl sulfonamide resin reacted with the acetic anhydride respectively to form the active intermediate polystyrene N,O-diacetyl sulfonamate which was cleaved by n-butanol to produce butyl acetate. The catalytic esterification by resin 1 was in good agreement with the kinetic model of "bi-bi-ping-pong" mechanism.

  15. Triflic Anhydride-Mediated Beckmann Rearrangement Reaction of Β-Oximyl Amides: Access to 5-Iminooxazolines

    Indian Academy of Sciences (India)

    MANGFEI YU; QIAN ZHANG; JIA WANG; PENG HUANG; PENGFEI YAN; RUI ZHANG; DEWEN DONG

    2016-06-01

    Facile and efficient synthesis of 5-iminooxazolines fromΑ, Α-disubstituted Β-oximyl amidesmediated by triflic anhydride $(Tf_{2}O)$ in the presence of 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU) indichloromethane at room temperature is developed, and a mechanism involving tandem Beckmann rearrangementand intramolecular cyclization reaction is proposed.

  16. THE GRAFTING OF MALEIC-ANHYDRIDE ON HIGH-DENSITY POLYETHYLENE IN AN EXTRUDER

    NARCIS (Netherlands)

    GANZEVELD, KJ; JANSSEN, LPBM

    The grafting of maleic anhydride (MAH) on high density polyethylene in a counter-rotating twin screw extruder has been studied. As the reaction kinetics appear to be affected by mass transfer, good micro mixing in the extruder is important. Due to the competing mechanisms of increasing mixing and

  17. Molecular characterization of trimellitic anhydride-induced respiratory allergy in Brown Norway rats

    NARCIS (Netherlands)

    Kuper, C.F.; Heijne, W.H.; Dansen, M.; Verhoeckx, K.C.; Boorsma, A.; Radonjic, M.; Bruijntjes, J.; Stierum, R.; Muijser, H.; Arts, J.H.

    2008-01-01

    To contribute to the hazard identification of low molecular weight (LMW) respiratory allergens, respiratory allergy induced by trimellitic anhydride (TMA) was characterized by whole genome analysis of lung tissue and blood proteomics in Brown Norway rats. Dermal sensitization (50% and 25% w/v) with

  18. THE GRAFTING OF MALEIC-ANHYDRIDE ON HIGH-DENSITY POLYETHYLENE IN AN EXTRUDER

    NARCIS (Netherlands)

    GANZEVELD, KJ; JANSSEN, LPBM

    1992-01-01

    The grafting of maleic anhydride (MAH) on high density polyethylene in a counter-rotating twin screw extruder has been studied. As the reaction kinetics appear to be affected by mass transfer, good micro mixing in the extruder is important. Due to the competing mechanisms of increasing mixing and de

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

    Science.gov (United States)

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

    2017-08-07

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

  20. SELECTIVE HYDROGENATION OF ANHYDRIDES TO LACTONES UNDER SUPERCRITICAL CARBON DIOXIDE MEDIUM

    Science.gov (United States)

    Selective Hydrogenation of Anhydrides to Lactones Under Supercritical Carbon Dioxide MediumEndalkachew Sahle-Demessie Unnikrishnan R PillaiU.S. EPA , 26 W. Martin Luther King Dr. Cincinnati, OH 45268 Phone: 513-569-7739Fax: 513-569-7677Abstract:Hydrogenat...

  1. Maleic anhydride based copolymer dispersions for surface modification of polar substrates

    NARCIS (Netherlands)

    Gunbas, I.D.; Wouters, M.E.L.; Hendrix, M.M.R.M.; Benthem, R.A.T.M. van; Koning, C.E.; Noordover, B.A.J.

    2012-01-01

    In this article, we report the modification of poly(styrene-alt-maleic anhydride) (PSMA) with monofunctional amine-terminated poly(dimethyl siloxane) (PDMS-NH2) by thermal imidization, followed by the preparation and characterization of a surfactant-free artificial latex thereof and application of t

  2. TRIMELLITIC ANHYDRIDE (TMA) HYPERSENSITIVITY IN MICE AFTER MULTIPLE INTRATRACHAEL (IT) EXPOSURE

    Science.gov (United States)

    SOT 2001 DMS214TRIMELLITIC ANHYDRIDE (TMA) HYPERSENSITIVITY INMICE AFTER MULTIPLE INTRATRACHEAL (IT) EXPOSURES. D Sailstad, E Boykin, M Ward, and MJ Selgrade. NHEERL, ORD, US EPA, RTP, NC, USA.TMA causes Th2 related respiratory hypersensitivity (RH) responses. W...

  3. Blends of Styrene-Butadiene-Styrene Triblock Copolymer with Random Styrene-Maleic Anhydride Copolymers

    NARCIS (Netherlands)

    Piccini, Maria Teresa; Ruggeri, Giacomo; Passaglia, Elisa; Picchioni, Francesco; Aglietto, Mauro

    2002-01-01

    Blends of styrene-butadiene-styrene triblock copolymer (SBS) with random styrene-maleic anhydride copolymers (PS-co-MA), having different MA content, were prepared in a Brabender Plastigraph mixer. The presence of polystyrene (PS) blocks in the SBS copolymer and the high styrene content (93 and 86 w

  4. Maleic anhydride based copolymer dispersions for surface modification of polar substrates

    NARCIS (Netherlands)

    Gunbas, I.D.; Wouters, M.E.L.; Hendrix, M.M.R.M.; Benthem, R.A.T.M. van; Koning, C.E.; Noordover, B.A.J.

    2012-01-01

    In this article, we report the modification of poly(styrene-alt-maleic anhydride) (PSMA) with monofunctional amine-terminated poly(dimethyl siloxane) (PDMS-NH2) by thermal imidization, followed by the preparation and characterization of a surfactant-free artificial latex thereof and application of

  5. Synthesis of 24-phenyl-24-oxo steroids derived from bile acids by palladium-catalyzed cross coupling with phenylboronic acid. NMR characterization and X-ray structures.

    Science.gov (United States)

    Mayorquín-Torres, Martha C; Romero-Ávila, Margarita; Flores-Álamo, Marcos; Iglesias-Arteaga, Martin A

    2013-11-01

    Palladium-catalyzed cross coupling of phenyboronic acid with acetylated bile acids in which the carboxyl functions have been activated by formation of a mixed anhydride with pivalic anhydride afforded moderate to good yield of 24-phenyl-24-oxo-steroids. Unambiguous assignments of the NMR signals were made with the aid of combined 1D and 2D NMR techniques. X-ray diffraction studies confirmed the obtained structures.

  6. Novel 4-Arm Poly(Ethylene Glycol-Block-Poly(Anhydride-Esters Amphiphilic Copolymer Micelles Loading Curcumin: Preparation, Characterization, and In Vitro Evaluation

    Directory of Open Access Journals (Sweden)

    Li Lv

    2013-01-01

    Full Text Available A novel 4-arm poly(ethylene glycol-block-poly(anhydride-esters amphiphilic copolymer (4-arm PEG-b-PAE was synthesized by esterization of 4-arm poly(ethylene glycol and poly(anhydride-esters which was obtained by melt polycondensation of α-, ω-acetic anhydride terminated poly(L-lactic acid. The obtained 4-arm PEG-b-PAE was characterized by 1H-NMR and gel permeation chromatography. The critical micelle concentration of 4-arm PEG-b-PAE was 2.38 μg/mL. The curcumin-loaded 4-arm PEG-b-PAE micelles were prepared by a solid dispersion method and the drug loading content and encapsulation efficiency of the micelles were 7.0% and 85.2%, respectively. The curcumin-loaded micelles were spherical with a hydrodynamic diameter of 151.9 nm. Curcumin was encapsulated within 4-arm PEG-b-PAE micelles amorphously and released from the micelles, faster in pH 5.0 than pH 7.4, presenting one biphasic drug release pattern with rapid release at the initial stage and slow release later. The hemolysis rate of the curcumin-loaded 4-arm PEG-b-PAE micelles was 3.18%, which was below 5%. The IC50 value of the curcumin-loaded micelles against Hela cells was 10.21 μg/mL, lower than the one of free curcumin (25.90 μg/mL. The cellular uptake of the curcumin-loaded micelles in Hela cell increased in a time-dependent manner. The curcumin-loaded micelles could induce G2/M phase cell cycle arrest and apoptosis of Hela cells.

  7. Curing efficiency of various types of light-curing units.

    Science.gov (United States)

    Rahiotis, Chris; Kakaboura, Afrodite; Loukidis, Michalis; Vougiouklakis, George

    2004-02-01

    This study compared monomer conversion (DC), the per cent linear polymerization shrinkage (%LS), the wall-to-wall contraction pattern (per cent of peripheral opening, %DM, and maximal marginal gap, MG) and depth of cure (DOC), of a hybrid resin composite (Spectrum TPH) exposed to different types of light-curing units and exposure modes (Virtuoso-PAC, Elipar TriLight-QTH, and FreeLight-LED). The QTH and LED units were used in two curing modes: the exponential ramp and the continuous output modes. Monomer conversion was investigated by micro Multiple Internal Reflection (MIR)-Fourier-transform infrared (FTIR) spectroscopy and %LS was measured by the deflective disc method. The wall-to-wall contraction method used a cylindrical cavity model in extracted human teeth. The per cent debonded margins relative to the cavity periphery (%DM) and the width of maximum gap (MG) was evaluated. The DOC was determined using Vickers microhardness measurements (200 g load, 20 s) at the top surface (H0), at 2 mm (H2) and at 4 mm (H4) depths, and the results expressed as H2/H0 and H4/H0 ratios. Significantly lower %DC and %LS values were provided by PAC and LED units. No differences were found in %DM among the curing units and PAC exhibited the highest MG. No significant differences were noted among light-curing groups in terms of H2/H0 microhardness values. The QTH, operated in exponential mode, resulted in the highest H4/H0 value. The exponential mode of the QTH demonstrated superior performance for the total of the characteristics evaluated.

  8. Microwave synthesis and thermal properties of polyacrylate derivatives containing itaconic anhydride moieties

    Directory of Open Access Journals (Sweden)

    Osman Sameh M

    2012-08-01

    Full Text Available Abstract Background Microwave irradiation as an alternative heat source is now a well-known method in synthetic chemistry. Microwave heating has emerged as a powerful technique to promote a variety of chemical reactions, offering reduced pollution, low cost and offer high yields together with simplicity in processing and handling. On the other hand, copolymers containing both hydrophilic and hydrophobic segments are drawing considerable attention because of their possible use in biological systems. Various copolymer compositions can produce a very large number of different arrangements, producing materials of varying chemical and physical properties. Thus, the hydrophilicity of copolymers can be modified by changing the amount of incorporated itaconic anhydride. Results A series of methyl methacrylate (MMA and acrylamide (AA copolymers containing itaconic anhydride (ITA were synthesized by microwave irradiation employing a multimode reactor (Synthos 3000 Aton Paar, GmbH, 1400 W maximum magnetron as well as conventional method. The thermal properties of the copolymers were evaluated by different techniques. Structure-thermal property correlation based on changing the itaconic anhydride ratio was demonstrated. Results revealed that the incorporation of itaconic anhydride into the polymeric backbone of all series affect the thermal stability of copolymers. In addition, the use of the microwave method offers high molecular weight copolymers which lead eventually to an increase in thermal stability. Conclusions Microwave irradiation method showed advantages for the produced copolymers compared to that prepared by conventional method, where it can offer a copolymer in short time, high yield, more pure compounds and more thermally stable copolymers, rather than conventional method. Also, microwave irradiation method gives higher molecular weight due to prevention of the chain transfer. Moreover, as the itaconic anhydride content increases the thermal

  9. Breather cloth for vacuum curing

    Science.gov (United States)

    Reed, M. W.

    1979-01-01

    Finely-woven nylon cloth that has been treated with Teflon improves vacuum adhesive bonding of coatings to substrates. Cloth is placed over coating; entire assembly, including substrate, coating, and cloth, is placed in plastic vacuum bag for curing. Cloth allows coating to "breathe" when bag is evacuated. Applications include bonding film coatings to solar concentrators and collectors.

  10. Susan G. Komen for the Cure

    Science.gov (United States)

    ... an Event Komen Race for the Cure Susan G. Komen 3 Day Find Local Events Fundraise Fundraise ... 2016 Search Events Friday, September 22, 2017 Susan G. Komen Italia Race for the Cure® - Bologna Bologna, ...

  11. Accelerated Cure Project for Multiple Sclerosis

    Science.gov (United States)

    ... main content Accelerating research toward a cure for multiple sclerosis Home Contact Us Search form Search Connect Volunteer ... is to accelerate efforts toward a cure for multiple sclerosis by rapidly advancing research that determines its causes ...

  12. Rapid Development of the Radiation Curing Sector

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Radiation curing is an advanced material surface treatment technology using ultraviolet (UV) radiation and electronic beams (EB). With the greater attention paid to environ mentel protection in recent years ,radiation curing has developed rapidly.

  13. Techniques for internal water curing of concrete

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Pietro, Lura

    2003-01-01

    This paper gives an overview of different techniques for incorporation of internal curing water in concrete. Internal curing can be used to mitigate self-desiccation and self-desiccation shrinkage. Some concretes may need 50 kg/m3 of internal curing water for this purpose. The price of the internal...

  14. Facile and Efficient Acetylation of Primary Alcohols and Phenols with Acetic Anhydride Catalyzed by Dried Sodium Bicarbonate

    National Research Council Canada - National Science Library

    Fulgentius Nelson Lugemwa; Koonj Shaikh; Edwin Hochstedt

    2013-01-01

      A variety of primary alcohols and phenols were reacted with acetic anhydride at room temperature in the presence of sodium bicarbonate to produce corresponding esters in good to excellent yields...

  15. Ruthenium-catalyzed decarbonylative addition reaction of anhydrides with alkynes: a facile synthesis of isocoumarins and α-pyrones.

    Science.gov (United States)

    Prakash, Rashmi; Shekarrao, Kommuri; Gogoi, Sanjib; Boruah, Romesh C

    2015-06-21

    A novel ruthenium catalyzed straightforward and efficient synthesis of isocoumarin and α-pyrone derivatives has been accomplished by the decarbonylative addition reaction of anhydrides with alkynes under thermal conditions.

  16. Freud's psychoanalysis: a moral cure.

    Science.gov (United States)

    Eriksson, Johan

    2014-08-01

    That psychoanalytical treatment in its classical Freudian sense is primarily a moral or ethical cure is not a very controversial claim. However, it is far from obvious how we are to understand precisely the moral character of psychoanalysis. It has frequently been proposed that this designation is valid because psychoanalysis strives neither to cure psychological symptoms pharmaceutically, nor to superficially modify the behaviour of the analysand, but to lead the analysand through an interpretive process during which he gradually gains knowledge of the unconscious motives that determine his behaviour, a process that might ideally liberate him to obtain, in relation to his inner desires, the status of a moral agent. There resides something appealing in these claims. But it is the author's belief that there is an even deeper moral dimension applying to psychoanalytical theory and praxis. Freudian psychoanalysis is a moral cure due to its way of thematizing psychological suffering as moral suffering. And this means that the moral subject - the being that can experience moral suffering - is not primarily something that the psychoanalytical treatment strives to realize, but rather the presupposition for the way in which psychoanalysis theorizes psychological problems as such. Copyright © 2014 Institute of Psychoanalysis.

  17. From HCV To HBV Cure.

    Science.gov (United States)

    Schinazi, Raymond F; Asselah, Tarik

    2017-01-01

    Approximately 170 million people are chronically infected with HCV and 350 million are chronically infected with HBV worldwide. It is estimated that more than one million patients die from complications related to chronic viral hepatitis, mainly HCC which is one of the most frequent cancers in many countries, especially Africa, the Middle East and Asia. HCV drug development has been impressive, and this revolution led to several direct-acting antiviral agents achieving an HCV cure after only 6-12 weeks. This progress could theorically lead to HCV global elimination making HCV and its consequences a rarity. HBV research and development programs can learn from the HCV experience, to achieve an HBV functional or sterilizing cure. This review will summarize key steps which have been realized for an HCV cure, and discuss the next steps to achieve for an HCV elimination. And also, how this HCV revolution has inspired scientists and clinicians to achieve the same for HBV.

  18. Electron paramagnetic resonance and FT-IR spectroscopic studies of glycine anhydride and betaine hydrochloride

    Science.gov (United States)

    Halim Başkan, M.; Kartal, Zeki; Aydın, Murat

    2015-12-01

    Gamma irradiated powders of glycine anhydride and betaine hydrochloride have been investigated at room temperature by electron paramagnetic resonance (EPR). In these compounds, the observed paramagnetic species were attributed to the R1 and R2 radicals, respectively. It was determined that the free electron interacted with environmental protons and 14N nucleus in both radicals. The EPR spectra of gamma irradiated powder samples remained unchanged at room temperature for two weeks after irradiation. Also, the Fourier Transform Infrared (FT-IR), FT-Raman and thermal analyses of both compounds were investigated. The functional groups in the molecular structures of glycine anhydride and betaine hydrochloride were identified by vibrational spectroscopies (FT-IR and FT-Raman).

  19. Physicochemical Characterization and the Comparison of Chitin and Chitin Modified with Maleic Anhydride

    Directory of Open Access Journals (Sweden)

    İlhan Uzun

    2015-06-01

    Full Text Available Firstly, chitin was modified via ring-opening reaction with maleic anhydride in lithium chloride/N,N-dimethylacetamide. Then, both chitin and chitin modified with maleic anhydride (CMA were characterized by Fourier transform infrared (FTIR spectroscopy, X-ray diffraction (XRD method, ultraviolet-visible (UV-Vis spectroscopy, and scanning electron microscopy (SEM. Thermogravimetric analysis (TGA was performed to investigate the thermal stability of chitin and CMA. TGA results showed that chitin is thermally more stable than CMA. In addition, the electrical conductivity of chitin and CMA was also measured. Electrical conductivity measurement results showed that the electrical conductivity of CMA (4.3x10-4 S cm-1 is more than that of chitin (6.5x10-6 S cm-1.

  20. Preparation and characterization of poly(styrene/maleic anhydride)/kaolin nanocomposites

    Institute of Scientific and Technical Information of China (English)

    LIU Xuening; ZHANG Hongtao; YANG Zhizhong; HA Chengyong

    2005-01-01

    The direct exfoliation of in situ intercalative copolymerized styrene/maleic anhydride charge-transfercomplex (PSMA) into the inter lamellar spaces of modified kaolin (Kao-DMSO), which was intercalated and surface modified by dimethyl sulfoxide (DMSO), was reported. The nano structure of the composites was investigated by wide-angle X-ray diffraction (XRD) and transmission electron microscopy (TEM). The interaction between kaolin surface and PSMA chain was conformed by FTIR analysis. The XRD results showed that the intercalated polystyrene-maleic anhydride units were arranged in the flattened monolayer arrangements, and the 001 diffraction peak of the original kaolin disappeared. The TEM image showed that the kaolin was exfoliated into nanometer size and dispersed in the polymer matrix. Additionally the thermal stability of the nanocomposites was studied by thermo-gravimetric analysis (TGA), and the resulting thermogram indicated that the thermal stability of the nanocomposites was significantly increased.

  1. Preparation and Mechanical Properties of Chitosan-graft Maleic Anhydride Reinforced with Montmorillonite

    Science.gov (United States)

    Fajrin, A.; Sari, L. A.; Rahmawati, N.; Saputra, O. A.; Suryanti, V.

    2017-02-01

    The research aims to develop biodegradable composites as bio-based plastics from chitosan. The composites were prepared via solution casting method by introducing the maleic anhydride (MAH) as grafting agent and montmorillonite (MMt) as reinforcement. The grafting process of chitosan was conducted by varying concentrations of MAH which were 10, 20, and 30% w/w. It was observed that the chitosan-graft-maleic anhydride (Cs-g-MAH) containing 10% w/w of MAH increased its tensile strength by 70%. Reinforcement material was added to the Cs-g-MAH by varying MMt concentrations, e.g. 3, 6, 9 and 12% w/w. It was noted that the presence of 9% w/w of MMt in the Cs-g-MAH gave the best mechanical properties of the Cs-g-MAH/MMt composite.

  2. Wheat Gluten Blends with Maleic Anhydride-Functionalized Polyacrylate Cross-Linkers for Improved Properties.

    Science.gov (United States)

    Diao, Cheng; Xia, Hongwei; Parnas, Richard S

    2015-10-14

    A family of polyacrylate-based cross-linkers was synthesized to maximize the toughness of high Tg, high modulus wheat gluten blends in the glassy state. Mechanical testing and damping measurements were conducted to provide an example where the work of fracture and strength of the blend substantially exceeds polystyrene while maintaining flexure stiffness in excess of 3 GPa. The new rubbery cross-linkers, polymethyl acrylate-co-maleic anhydride and polyethyl acrylate-co-maleic anhydride, improve WG mechanical properties and reduce water absorption simultaneously. MDSC, FTIR, HPLC, and NMR data confirmed the cross-linking reaction with wheat gluten. Flexural, DMA, and water absorption testing were carried out to characterize the property improvements. DMA was conducted to investigate the relationship between energy damping and mechanical property improvement. If the cross-linker damping temperature is close to the testing temperature, the entire sample exhibits high damping, toughness, and strength.

  3. Changes of Polyphenols in Tobacco Leaves During the Flue-Curing Process and Correlation Analysis on Some Chemical Components

    Institute of Scientific and Technical Information of China (English)

    GONG Chang-rong; WANG Ai-hua; WANG Song-feng

    2006-01-01

    The changes of polyphenols in tobacco leaves during the flue-curing process and correlation analysis on some chemical components were studied. Leaf samples were taken from different tobacco-producing regions in Henan Province, China.The results indicated that the content of total phenols increased during the first 24 h of curing, and then decreased. It reached the lowest value at 72 h of curing and increased rapidly after that. The content of chlorogenic acid also increased during 0-24 h of curing. But the lowest point occurred at 60 or 72 h of curing and then it increased till the end of the curing process. The content of rutin generally increased with curing, and showed little fluctuations. The changes of PPO and POD activity were the opposite. Rutin was found to have a highly significant positive correlation with total sugar (r=0.822**),but a highly significant negative correlation with starch, nicotine, and protein.

  4. Comparative kinetic study and microwaves non-thermal effects on the formation of poly(amic acid) 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 4,4'-(hexafluoroisopropylidene)bis(p-phenyleneoxy)dianiline (BAPHF). Reaction activated by microwave, ultrasound and conventional heating.

    Science.gov (United States)

    Tellez, Hugo Mendoza; Alquisira, Joaquín Palacios; Alonso, Carlos Rius; Cortés, José Guadalupe López; Toledano, Cecilio Alvarez

    2011-01-01

    Green chemistry is the design of chemical processes that reduce or eliminate negative environmental impacts. The use and production of chemicals involve the reduction of waste products, non-toxic components, and improved efficiency. Green chemistry applies innovative scientific solutions in the use of new reagents, catalysts and non-classical modes of activation such as ultrasounds or microwaves. Kinetic behavior and non-thermal effect of poly(amic acid) synthesized from (6FDA) dianhydride and (BAPHF) diamine in a low microwave absorbing p-dioxane solvent at low temperature of 30, 50, 70 °C were studied, under conventional heating (CH), microwave (MW) and ultrasound irradiation (US). Results show that the polycondensation rate decreases (MW > US > CH) and that the increased rates observed with US and MW are due to decreased activation energies of the Arrhenius equation. Rate constant for a chemical process activated by conventional heating declines proportionally as the induction time increases, however, this behavior is not observed under microwave and ultrasound activation. We can say that in addition to the thermal microwave effect, a non-thermal microwave effect is present in the system.

  5. Comparative Kinetic Study and Microwaves Non-Thermal Effects on the Formation of Poly(amic acid 4,4′-(Hexafluoroisopropylidenediphthalic Anhydride (6FDA and 4,4′-(Hexafluoroisopropylidenebis(p-phenyleneoxydianiline (BAPHF. Reaction Activated by Microwave, Ultrasound and Conventional Heating

    Directory of Open Access Journals (Sweden)

    Hugo Mendoza Tellez

    2011-10-01

    Full Text Available Green chemistry is the design of chemical processes that reduce or eliminate negative environmental impacts. The use and production of chemicals involve the reduction of waste products, non-toxic components, and improved efficiency. Green chemistry applies innovative scientific solutions in the use of new reagents, catalysts and non-classical modes of activation such as ultrasounds or microwaves. Kinetic behavior and non-thermal effect of poly(amic acid synthesized from (6FDA dianhydride and (BAPHF diamine in a low microwave absorbing p-dioxane solvent at low temperature of 30, 50, 70 °C were studied, under conventional heating (CH, microwave (MW and ultrasound irradiation (US. Results show that the polycondensation rate decreases (MW > US > CH and that the increased rates observed with US and MW are due to decreased activation energies of the Arrhenius equation. Rate constant for a chemical process activated by conventional heating declines proportionally as the induction time increases, however, this behavior is not observed under microwave and ultrasound activation. We can say that in addition to the thermal microwave effect, a non-thermal microwave effect is present in the system.

  6. Synthesis and Characterization of Organic Impurities in Bortezomib Anhydride Produced by a Convergent Technology

    Science.gov (United States)

    Ivanov, Andrey S.; Shishkov, Sergey V.; Zhalnina, Anna A.

    2012-01-01

    A profile of impurities in bortezomib anhydride, produced by a recently developed convergent technology, has been characterized. HPLC-MS analysis of the drug essence revealed three impurities: an epimer of bortezomib, resulting from partial racemization of l-phenylalanine’s stereogenic center during the chemical synthesis, and two epimeric products of oxidative degradation of bortezomib, in which boron is replaced by the OH group. The impurities were obtained by chemical synthesis and characterized by physical methods. PMID:22396904

  7. Dodecenylsuccinic Anhydride Derivatives of Gum Karaya (Sterculia urens): Preparation, Characterization, and Their Antibacterial Properties

    OpenAIRE

    Padil, V.V.T.; Senan, Chandra; Cernik, M

    2015-01-01

    Esterifications of the tree-based gum, gum karaya (GK), using dodecenylsuccinic anhydride (DDSA) were carried out in aqueous solutions. GK was deacetylated using alkali treatment to obtain deacetylated gum karaya (DGK). The DGK and its DDSA derivative were characterized using gel permeation chromatography/multiangle laser light scattering (GPC/MALLS), attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), proton nuclear magnetic re...

  8. Perylene anhydride fused porphyrins as near-infrared sensitizers for dye-sensitized solar cells

    KAUST Repository

    Jiao, Chongjun

    2011-07-15

    Two perylene anhydride fused porphyrins 1 and 2 have been synthesized and employed successfully in dye-sensitized solar cells (DSCs). Both compounds showed broad incident monochromatic photon-to-current conversion efficiency spectra covering the entire visible spectral region and even extending into the near-infrared (NIR) region up to 1000 nm, which is impressive for ruthenium-free dyes in DSCs. © 2011 American Chemical Society.

  9. Composite cure monitoring with Bragg grating sensors

    Science.gov (United States)

    Slattery, Kerry T.; Corona-Bittick, Kelli; Dorr, Donald J.

    1998-03-01

    Residual stress is induced in fiber composite materials during the cure process because the thermal expansion coefficient of the fiber is generally much lower than that of the polymer matrix. The two materials are 'locked' together at the cure temperature. Then, as they cool, the matrix attempts to contract more than the fiber leading to tension in the matrix and compression in the fiber. This can lead to the formation of microcracks parallel to the fibers in thick composite piles or yarns. The magnitude of residual stress can be reduced by modifying the cure cycle; however, optimizing the cure cycle requires a complete understanding of the state of cure throughout the composite. This is a complex problem -- especially in thick composites. Pilot studies have been performed placing Bragg gratin sensors in glass fabric preforms and monitoring the response of the grating during resin infusion and cure. The typical response shows the initial thermal expansion of the Bragg grating, a rapid contraction of the grating as the resin gels, slower contraction during cure, and thermal contraction at the composite thermal expansion coefficient during cool down. This data is then sued with micromechanical models of the fiber/matrix interaction during cure to establish material parameters for cure simulation. Once verified, these cure simulation methods will be used to optimize tooling design and cure cycles in composite components.

  10. Study on oil absorbency of succinic anhydride modified banana cellulose in ionic liquid.

    Science.gov (United States)

    Shang, Wenting; Sheng, Zhanwu; Shen, Yixiao; Ai, Binling; Zheng, Lili; Yang, Jingsong; Xu, Zhimin

    2016-05-05

    Banana cellulose contained number of hydrophilic hydroxyl groups which were succinylated to be hydrophobic groups with high oil affinity. Succinic anhydride was used to modify banana cellulose in 1-allyl-3-methylimidazolium chloride ionic liquid in this study. The modified banana cellulose had a high oil absorption capacity. The effects of reaction time, temperature, and molar ratio of succinic anhydride to anhydroglucose on the degree of substitution of modified banana cellulose were evaluated. The optimal reaction condition was at a ratio of succinic anhydride and anhydroglucose 6:1 (m:m), reaction time 60min and temperature 90°C. The maximum degree of acylation reaction reached to 0.37. The characterization analysis of the modified banana cellulose was performed using X-ray diffractometer, Fourier transform infrared spectrometer, scanning electron microscopy and thermogravimetry. The oil absorption capacity and kinetics of the modified banana cellulose were evaluated at the modified cellulose dose (0.025-0.3g), initial oil amount (5-30g), and temperature (15-35°C) conditions. The maximum oil absorption capacity was 32.12g/g at the condition of the cellulose dose (0.05g), initial oil amount (25g) and temperature (15°C). The kinetics of oil absorption of the cellulose followed a pseudo-second-order model. The results of this study demonstrated that the modified banana cellulose could be used as an efficient bio-sorbent for oil adsorption.

  11. Synthesis and characterization of maleic anhydride esterified corn starch by the dry method.

    Science.gov (United States)

    Zuo, Yingfeng; Gu, Jiyou; Yang, Long; Qiao, Zhibang; Tan, Haiyan; Zhang, Yanhua

    2013-11-01

    Maleic anhydride esterified starch was synthesized by a dry method using corn starch as the material and maleic anhydride as the esterifying agent. The esterified starch (ES) was analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), which confirmed that there was a successful esterification reaction between the maleic anhydride and corn starch. The effects of reaction temperature and time on the degree of substitution of esterified starch were studied, where the results showed that 80 °C of reaction temperature and 3h of reaction time were optimal conditions. The result of XPS testing demonstrated that the esterification reaction led to increase of ester bonds in starch. The scanning electron microscopy (SEM) and laser particle size analyzer results showed that esterification led to roughness on the surface of the starch particle, and the particle size and distribution rate of esterification starch became larger. X-ray diffraction (XRD) analysis demonstrated that esterification reaction did not change the crystalline type of native starch. The differential scanning calorimeter (DSC) and thermo gravimetric analysis (TGA) confirmed that destruction of the crystal structure resulted in improved thermoplasticity of the starch, decreased the gelatinization temperature and increased the thermogravimetric rate of esterification starch. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Calorimetric study of benzaldehyde interaction with acetic anhydride

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, A.M.; Ivanova, L.A.

    1978-03-01

    Benzaldehyde conversion to benzylidene diacetate, a side reaction reducing the selectivity of benzaldehyde oxidation to acetylbenzoyl peroxide, studied at 6/sup 0/-50/sup 0/C, was an irreversible third-order reaction catalyzed by beryllium sulfate or by succinnic, chloroacetic, and particularly sulfuric and perchloric acids. In the presence of organic solvents, (e.g., benzene, hexane, or cyclohexane), the process was complicated by acidolysis and parallel C-acylation reactions, and the catalyst rapidly deactivated. A microcalorimetric method was developed to determine kinetic parameters of the process in the absence of the solvents. Tables and graphs.

  13. Effects of cement-curing mode and light-curing unit on the bond durability of ceramic cemented to dentin

    Directory of Open Access Journals (Sweden)

    Sheila Pestana Passos

    2013-04-01

    Full Text Available The aim of this study was to evaluate the effects of different light-curing units and resin cement curing types on the bond durability of a feldspathic ceramic bonded to dentin. The crowns of 40 human molars were sectioned, exposing the dentin. Forty ceramic blocks of VITA VM7 were produced according to the manufacturer's recommendations. The ceramic surface was etched with 10% hydrofluoric acid / 60s and silanized. The dentin was treated with 37% phosphoric acid / 15s, and the adhesive was applied. The ceramic blocks were divided and cemented to dentin according to resin cement / RC curing type (dual- and photo-cured, light-curing unit (halogen light / QTH and LED, and storage conditions (dry and storage / 150 days + 12,000 cycles / thermocycling. All blocks were stored in distilled water (37°C / 24h and sectioned (n = 10: G1 - QTH + RC Photo, G2 - QTH + RC Dual, G3 - LED + RC Photo, G4 - LED + RC Dual. Groups G5, G6, G7, and G8 were obtained exactly as G1 through G4, respectively, and then stored and thermocycled. Microtensile bond strength tests were performed (EMIC, and data were statistically analyzed by ANOVA and Tukey's test (5%. The bond strength values (MPa were: G1 - 12.95 (6.40ab; G2 - 12.02 (4.59ab; G3 - 13.09 (5.62ab; G4 - 15.96 (6.32a; G5 - 6.22 (5.90c; G6 - 9.48 (5.99bc; G7 - 12.78 (11.30ab; and G8 - 8.34 (5.98bc. The same superscript letters indicate no significant differences. Different light-curing units affected the bond strength between ceramic cemented to dentin when the photo-cured cement was used, and only after aging (LED > QTH. There was no difference between the effects of dual- and photo-cured resin-luting agents on the microtensile bond strength of the cement used in this study.

  14. Radiation grafting of styrene and maleic anhydride onto PTFE membranes and sequent sulfonation for applications of vanadium redox battery

    Energy Technology Data Exchange (ETDEWEB)

    Qiu Jingyi; Ni Jiangfeng [Beijing National Laboratory for Molecular Science, Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Zhai Maolin [Beijing National Laboratory for Molecular Science, Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)], E-mail: mlzhai@pku.edu.cn; Peng Jing [Beijing National Laboratory for Molecular Science, Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Zhou Henghui [Beijing National Laboratory for Molecular Science, Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)], E-mail: hhzhou@pku.edu.cn; Li Jiuqiang; Wei Genshuan [Beijing National Laboratory for Molecular Science, Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

    2007-11-15

    Using {gamma}-radiation technique, poly(tetrafluoroethylene) (PTFE) membrane was grafted with styrene (St) (PTFE-graft-PS) or binary monomers of St and maleic anhydride (MAn) (PTFE-graft-PS-co-PMAn), respectively. Then grafted membranes were further sulfonated with chlorosulfonic acid into ion-exchange membranes (denoted as PTFE-graft-PSSA and PTFE-graft-PSSA-co-PMAc, respectively) for application of vanadium redox battery (VRB). Micro-FTIR analysis indicated that PTFE was successfully grafted and sulfonated at the above two different conditions. However, a higher degree of grafting (DOG) was obtained in St/MAn binary system at the same dose due to a synergistic effect. Comparing with PTFE-graft-PSSA, PTFE-graft-PSSA-co-PMAc membrane showed higher water uptake and ion-exchange capacity (IEC) and lower area resistance (AR) at the same DOG. In addition, PTFE-graft-PSSA-co-PMAc with 6% DOG also showed a higher IEC and higher conductivity compared to Nafion membrane. Radiation grafting of PTFE in St/MAn binary system and sequent sulfonation is an appropriate method for preparing ion-exchange membrane of VRB.

  15. In vitro release of clomipramine HCl and buprenorphine HCl from poly adipic anhydride (PAA) and poly trimethylene carbonate (PTMC) blends.

    Science.gov (United States)

    Dinarvand, Rassoul; Alimorad, Mohammed Massoud; Amanlou, Massoud; Akbari, Hamid

    2005-10-01

    Controlled drug-delivery technology is concerned with the systematic release of a pharmaceutical agent to maintain a therapeutic level of the drug in the body for modulated and/or prolonged periods of time. This may be achieved by incorporating the therapeutic agent into a degradable polymer vehicle, which releases the agent continuously as the matrix erodes. In this study, poly trimethylene carbonate (PTMC), an aliphatic polycarbonate, and poly adipic anhydride (PAA), an aliphatic polyanhydride, were synthesized via melt condensation and ring-opening polymerization of trimethylene carbonate and adipic acid, respectively. The release of clomipramine HCl and buprenorphine HCl from discs prepared with the use of PTMC-PAA blends in phosphate buffer (pH 7.4) are also described. Clomipramine HCl and buprenorphine HCl were both used as hydrophilic drug models. Theoretical treatment of the data with the Peppas model revealed that release of clomipramine HCl (5%) in devices containing 70% PTMC or more followed a Fickian diffusion model. However, the releases of buprenorphine HCl (5%) in the same devices were anomalous. For devices containing 50% and more PAA, surface erosion may play a significant role in the release of both molecules.

  16. Cure-A-Phobia感

    Institute of Scientific and Technical Information of China (English)

    黄乔

    2015-01-01

    爵士乐源于二十世纪的非洲黑人音乐,被公认为欧洲现代流行音乐的开端,随着二十一世纪多元化文化的不断呈现,爵士乐在我国也愈来愈受到关注.特别是在各艺术类院校,相关爵士乐教学及演出活动也越来越多.本文在此将对瑞典爵士乐队Cure-A-Phobia的一场音乐会略抒己见.

  17. XPS depth profiling of derivatized amine and anhydride plasma polymers: Evidence of limitations of the derivatization approach

    Science.gov (United States)

    Manakhov, Anton; Michlíček, Miroslav; Felten, Alexandre; Pireaux, Jean-Jacques; Nečas, David; Zajíčková, Lenka

    2017-02-01

    The quantitative analysis of the chemistry at the surface of functional plasma polymers is highly important for the optimization of their deposition conditions and, therefore, for their subsequent applications. The chemical derivatization of amine and carboxyl-anhydride layers is a well-known technique already applied by many researchers, notwithstanding the known drawback of the derivatization procedures like side or uncomplete reactions that could lead to "unreliable" results. In this work, X-ray photoelectron spectroscopy (XPS) combined with depth profiling with argon clusters is applied for the first time to study derivatized amine and carboxyl-anhydride plasma polymer layers. It revealed an additional important parameter affecting the derivatization reliability, namely the permeation of the derivatizing molecule through the target analysed layer, i.e. the composite effect of the probe molecule size and the layer porosity. Amine-rich films prepared by RF low pressure plasma polymerization of cyclopropylamine were derivatized with trifluoromethyl benzaldehide (TFBA) and it was observed by that the XPS-determined NH2 concentration depth profile is rapidly decreasing over top ten nanometers of the layer. The anhydride-rich films prepared by atmospheric plasma co-polymerization of maleic anhydride and C2H2 have been reacted with, parafluoroaniline and trifluoroethyl amine. The decrease of the F signal in top surface layer of the anhydride films derivatized by the "large" parafluoroaniline was observed similarly as for the amine films but the derivatization with the smaller trifluoroethylamine (TFEA) led to a more homogenous depth profile. The data analysis suggests that the size of the derivatizing molecule is the main factor, showing that the very limited permeation of the TFBA molecule can lead to underestimated densities of primary amines if the XPS analysis is solely carried out at a low take-off angle. In contrast, TFEA is found to be an efficient

  18. ASRM test report: Autoclave cure process development

    Science.gov (United States)

    Nachbar, D. L.; Mitchell, Suzanne

    1992-01-01

    ASRM insulated segments will be autoclave cured following insulation pre-form installation and strip wind operations. Following competitive bidding, Aerojet ASRM Division (AAD) Purchase Order 100142 was awarded to American Fuel Cell and Coated Fabrics Company, Inc. (Amfuel), Magnolia, AR, for subcontracted insulation autoclave cure process development. Autoclave cure process development test requirements were included in Task 3 of TM05514, Manufacturing Process Development Specification for Integrated Insulation Characterization and Stripwind Process Development. The test objective was to establish autoclave cure process parameters for ASRM insulated segments. Six tasks were completed to: (1) evaluate cure parameters that control acceptable vulcanization of ASRM Kevlar-filled EPDM insulation material; (2) identify first and second order impact parameters on the autoclave cure process; and (3) evaluate insulation material flow-out characteristics to support pre-form configuration design.

  19. Effect of curing with a plasma light on the properties of polymerizable dental restorative materials.

    Science.gov (United States)

    Millar, B J; Nicholson, J W

    2001-06-01

    Specimens of light-curable dental restoratives have been prepared using either a conventional dental curing lamp (for 20 or 30 s) or a plasma light (for 1 or 2 s). The specimens were then stored in water until their mass equilibrated, then dried to constant mass. Most specimens lost material in this process but the losses in all specimens cured with the plasma light were significantly greater than those cured with the conventional lights (P cure times gave slightly reduced losses in water in most cases. The specimens were then returned to water and allowed to re-equilibrate and their equilibrium water uptake determined. There was no simple trend in this latter property because elution of loosely bound hydrophilic species may have resulted in a less hydrophilic specimen, whose equilibrium water content was therefore correspondingly lower. Overall, the losses through dissolution in water suggest that plasma curing is less effective for these materials than conventional light curing, as it probably results in material with lower molar mass. The losses for the resin-modified glass-ionomer were much greater than for other materials, and it was concluded that the more rapid polymerization with plasma light caused a significant inhibitation of the acid-base part of the setting process. These findings suggest that long-term durability of materials may be compromised by employing plasma light cure rather than a conventional cure system and further studies of this point are recommended.

  20. Interfacial Properties of Electron Beam Cured Composites

    Energy Technology Data Exchange (ETDEWEB)

    Eberle, C.C.

    1999-12-30

    The objectives of the CRADA are to: Confirm that fiber-resin adhesion is responsible for the observed poor shear properties; Determine the mechanism(s) responsible for poor adhesion between carbon fibers and epoxy resins after e-beam curing; Develop and evaluate resin systems and fiber treatments to improve the properties of e-beam cured, carbon-fiber-reinforced composites; and Develop refined methods for processing e-beam cured, carbon-fiber-reinforced composites.

  1. Microwave Cure of Phenol-Formaldehyde Adhesive

    OpenAIRE

    高谷, 政広; 田平, 英敏; 岡本, 忠

    2006-01-01

    [Synopsis] Phenol-formaldehyde resin has been used as a versatile material for adhesives and coatings of a wide range of adherends because of its excellent performance in water- resistance, strength against abrasion, and so on. However, it has a drawback of slow rate of cure and relevant emission of formaldehyde gas after bonding. We studied the curing performance under irradiation of microwave for the purpose of looking for a way of accelerating the cure rate of phenol formaldehyde resin. Th...

  2. Polymerization kinetics of dual-curing adhesive systems when used solely or in conjunction with chemically-cured resin cement.

    Science.gov (United States)

    Kim, Young Kyung; Chun, Ju-Na; Kwon, Pyung Cheol; Kim, Kyo-Han; Kwon, Tae-Yub

    2013-10-01

    To investigate the chemical polymerization kinetics of commercial dual-curing adhesive systems when used solely or in conjunction with chemically-curing resin cement. Four adhesive systems comprising simplified-step adhesives and activators (Prime&Bond NT with Self Cure Activator, Excite DSC, AQ Bond Plus, All-Bond SE) were used. The pH values of the adhesives and adhesive/activator blends were measured. Differential scanning calorimetry (DSC) was used to investigate the extent of the chemical polymerization of the adhesives when used alone or directly intermixed with a chemically-cured resin cement (C&B Cement) for 60 min (n = 5). The data derived from the DSC analysis were statistically compared using one-way ANOVA and the Games-Howell post-hoc test (α = 0.05). All the adhesives were highly acidic; when they were blended with the respective activators, their pH values increased. Neither the adhesive/activator blends nor the adhesive alone/cement mixtures showed any detectable heat generation. The Prime&Bond NT/activator showed delayed heat generation only when intermixed with the catalyst/base paste. The other three adhesive systems produced similar exotherms when intermixed with the catalyst paste alone or with the catalyst/base paste (p > 0.05), but at significantly different maximum rates of polymerization (p adhesive system/resin cement interface appears highly dependent on the adhesive system used and may be considerably delayed.

  3. Electron Beam Curing of Advanced Composites

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The fundamental concept of electron beam method and the application in cure of composites are elaborated in this paper. The components of electron beam curing system are introduced. The mechanisms of interaction between electron beam and polymer matrix composites are presented. Recent studies reported including work of authors themselves on electron beam curing of composites are also discussed. Moreover, the authors believe that it is necessary to do the basic research about understanding how electron beam affects cured network and the mechanical/physical properties of the composites, for establishing a quantitative or semi-quantitative formulation.

  4. Influence of Reactive Diluent on UV-curing of Acrylate Terminated Hyperbranched Polymers

    Institute of Scientific and Technical Information of China (English)

    TANG Li-ming; FANG Yu; YAN Liang; FU Zhi-wei

    2004-01-01

    A Aeries of hydroxylic hyperbranched polymers were derived from 2,2-bis(methylol) propionic acid and tris (methylol) propane reacted with acrylic acid to various extents. The obtained acrylated hyperbranched polymers alone or with a monofunctional diluent, isobornylene acrylate(IBOA) were further cured by UV radiation. The cured films based on the modified polymers alone all demonstrated poor mechanical properties due to their high network densities and low moving ability of polymer chains. For the composite systems, the cured films demonstrated improved mechanical properties due to the low network densities and high chain moving ability. With more IBOA included in the systems, acrylate groups can react to a higher extent during the curing process.

  5. Morphology and Cure Behavior of Multi-walled Carbon Nanotubes-based Thermally Conductive Adhesive

    Institute of Scientific and Technical Information of China (English)

    WANG Junxia; YAN Shilin; HE Yunban; YAN Fei; XIE Beiping

    2014-01-01

    We evaluated the cure behavior of multi-walled carbon nanotubes (MWCNTs) based thermally conductive adhesive by comprehensively thermal analysis, which presented extremely complicated variability of conversion ratioαas a function of temperature with synergistic action of positive effect and negative volume-blocking effect of MWCNTs and cross-linked network of cured polymer molecules. Due to the decomposition of MWCNTs and degradation of polymer, the mass drop is dramatically obvious over the temperature range of 330-370℃. Binary resins filled with acid-treated MWCNTs present similar reaction interval as neat epoxy and matrix resins, which is distinct from the material filled with raw MWCNTs. The alteration of the crystalline temperature and cure temperature of resins is attributed to heterogeneous nucleation of MWCNTs in matrix resins. The-COOH group of acid-treated MWCNTs reacts with epoxy groups and thus generates cross-linking, accelerates the reaction rate and reduces the cure temperature.

  6. Curing efficiency of three light emitting diode units at different curing profiles

    Directory of Open Access Journals (Sweden)

    Priyanka Verma

    2016-01-01

    Conclusions: Reduction of exposure time to 6 s with high-intensity curing light seemed to be clinically acceptable and should be recommended. Curing of metal brackets with single exposure from buccal side showed lower shear bond strength values.

  7. Prevention is better than cure

    CERN Multimedia

    Anaïs Schaeffer

    2012-01-01

    Throughout the year, members of the Safety Inspections Services section of HSE Unit devote themselves to ensuring the safety of all infrastructure and equipment that represent a specific hazard within the Organization. They regularly comb through all CERN's infrastructure to forestall any accidents and their potential impact, true to the adage that prevention is better than cure.   This site has a few (!) slight safety problems... Spot the mistakes! (Details of the game below.) Ensuring that an HV electrical installation is properly earthed, that a system under pressure has no weak points, that an item of lifting equipment can be used without risk, that safety valves operate at the right pressure threshold as well as checking that a heavy object that could inflict injury if it fell is not stored on top of a cupboard: such are the types of inspections performed by the Safety Inspection Service (DGS-SEE-SIS). "These checks reassure those in charge of equipment and infrastruct...

  8. UV-Assisted 3D Printing of Glass and Carbon Fiber-Reinforced Dual-Cure Polymer Composites

    Directory of Open Access Journals (Sweden)

    Marta Invernizzi

    2016-07-01

    Full Text Available Glass (GFR and carbon fiber-reinforced (CFR dual-cure polymer composites fabricated by UV-assisted three-dimensional (UV-3D printing are presented. The resin material combines an acrylic-based photocurable resin with a low temperature (140 °C thermally-curable resin system based on bisphenol A diglycidyl ether as base component, an aliphatic anhydride (hexahydro-4-methylphthalic anhydride as hardener and (2,4,6,-tris(dimethylaminomethylphenol as catalyst. A thorough rheological characterization of these formulations allowed us to define their 3D printability window. UV-3D printed macrostructures were successfully demonstrated, giving a clear indication of their potential use in real-life structural applications. Differential scanning calorimetry and dynamic mechanical analysis highlighted the good thermal stability and mechanical properties of the printed parts. In addition, uniaxial tensile tests were used to assess the fiber reinforcing effect on the UV-3D printed objects. Finally, an initial study was conducted on the use of a sizing treatment on carbon fibers to improve the fiber/matrix interfacial adhesion, giving preliminary indications on the potential of this approach to improve the mechanical properties of the 3D printed CFR components.

  9. Hepatitis C, stigma and cure.

    Science.gov (United States)

    Marinho, Rui Tato; Barreira, David Pires

    2013-10-28

    The infection with hepatitis C virus (HCV) is one of the most important global chronic viral infections worldwide. It is estimated to affect around 3% of the world population, about 170-200 million people. Great part of the infections are asymptomatic, the patient can be a chronic carrier for decades without knowing it. The most severe consequences of the chronic infection are liver cirrhosis and hepatocellular carcinoma, which appears in 20%-40% of the patients, leading to hepatic failure and death. The HCV was discovered 25 years ago in 1989, is a RNA virus and classified by the World Health Organization as an oncogenic one. Hepatocellular carcinoma is one of the most important cancers, the fifth worldwide in terms of mortality. It has been increasing in the Ocidental world, mainly due to chronic hepatitis C. Hepatitis C is not only a liver disease and a cause of cirrhosis, but also a mental, psychological, familiar, and social disease. The stigma that the infected person sometimes carries is tremendous having multiple consequences. The main cause is lack of adequate information, even in the health professionals setting. But, besides the "drama" of being infected, health professionals, family, society and the infected patients, must be aware of the chance of real cure and total and definitive elimination of the virus. The treatment for hepatitis C has begun in the last 80's with a percentage of cure of 6%. Step by step the efficacy of the therapy for hepatitis C is rapidly increasing and nowadays with the very new medications, the so called Direct Antiviral Agents-DAAs of new generation, is around 80%-90%.

  10. Quantification of free sphingosine in cultured cells by acylation with radioactive acetic anhydride.

    Science.gov (United States)

    Ohta, H; Ruan, F; Hakomori, S; Igarashi, Y

    1994-11-01

    A simple and sensitive method for quantification of sphingosine in cellular lipid extracts was developed. The assay is based on quantitative conversion of sphingosine to N-[3H]acetylated sphingosine ([3H]C2-ceramide) by N-acylation with [3H]acetic anhydride under certain conditions. Sphingosine was extracted from cultured cells with chloroform and methanol and then treated with base to remove interfering glycerolipids having reactive amino groups (e.g., phosphatidylethanolamine or phosphatidylserine). Sphingosine was acylated with [3H]acetic anhydride in the presence of 0.004 N NaOH. Acylation was complete in 1 h at 37 degrees C when sphingosine was present in the picomole range. After the acylation, samples were treated with NaOH to reduce background radioactivity by removing the remaining [3H]acetic anhydride and hydrolyzing any ester linkages formed during the acylation and resolved by thin-layer chromatography. [3H]C2-ceramide converted from sphingosine with the acylation was detected with radioautography and quantitated by scraping the corresponding band and counting its radioactivity with a scintillation counter. [3H]C2-ceramide formed was quantitatively measured. This assay allows quantification of sphingosine over a range of 10 to 1500 pmol. The amount of sphingosine in lipid extracts from cultured cells was proportional to the number of cells. Sphingosine levels in human gastric cancer KATO III cells, human promyelocytic leukemic HL60 cells, and human monoblastic U937 cells, determined by this method, were 26.6 +/- 2.2, 6.3 +/- 0.4, and 6.8 +/- 0.6 pmol per 10(6) cells, respectively. Our new procedure allows quantification of sphingosine levels present in the low picomole range in lipid extracts from biological samples.

  11. Analysis on the Quantitative Change Trend of Acid Value and Peroxide Value Over Time in Curing Meat Products as Well as Its Practicality in Food Safety Enterprise Standard%腌腊肉制品酸价、过氧化值时间与量变趋势及适用性分析

    Institute of Scientific and Technical Information of China (English)

    唐啸; 龚玲; 郑华民; 吴畏; 祝伟

    2016-01-01

    目的:了解腌腊肉制品酸价、过氧化值在保质期内时间与量变趋势,在食品安全企业标准中设置该质量指标的可行性与必要性。方法采集保质期内市售畜肉类腌腊肉制品143件,禽肉类腌腊肉制品73件,共计216件,分别在产品出厂(20±10)d 和临近保质期(20±10) d 对酸价、过氧化值进行检测。结果本次调查显示,酸价的量变在畜肉类腌腊肉制品和禽肉类腌腊肉制品中均随时间增加而增高(R=0.212, P <0.05;R=0.541,P <0.001);过氧化值量变在畜肉类腌腊肉制品中随时间增加而降低(R=-0.208,P <0.05),在禽肉类腌腊肉制品中与时间无关(P=0.091)。结论本次调查提示,酸价不能代表腌腊肉制品的脂肪氧化酸败程度;过氧化值作为腌腊肉制品的安全性指标存在一定局限性。%Objective To analysis the quantitative change trend of acid value and peroxide value over time in curing meat products within their shelf life,as wel as the feasibility and necessity to set relative quality indexes in food safety enterprise stand. Methods Selected 216 curing meat products as samples, including 143 livestock meat products and 73 poultry meat products within their shelf life sold in the market. And detected their acid value and peroxide value in two time points,one was(20±10)days after the products are manufactured,the other was(20±10)days near their shelf life. Results The investigation showed that the quantitative change of acid value in both livestock meat and poultry meat products are increased over time increased (R=0.212,P < 0.05;R=0.541,P < 0.001). The quantitative change of peroxide value in livestock meat products decreased over time(R=-0.208, P < 0.05),but unchanged in poultry meat products. Conclusion The investigation indicates that,the acid value cannot represent the oxidation and rancidity degrees of fat in curing meat products,and peroxide value as safety

  12. Maleic anhydride-g-low density polyethylene: Modification of LDPE molecular structure by γ-irradiation

    Science.gov (United States)

    Sheeja, Manaf, O.; Sujith, A.

    2017-06-01

    Polymer modification by radiation grafting of monomers onto polymers has received much attention recently. In the current study, γ-irradiation technique was used to achieve graft copolymerization of maleic anhydride (MA) onto low-density polyethylene (LDPE). To optimize, the process was performed at different γ-irradiation doses and MA concentration. The microstructure of grafted polymer film has been characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, field emission-scanning electron microscopy, and atomic force microscopy. The studies performed made possible the selection of experimental protocols adequate for the production of new copolymeric materials with high grafting yield.

  13. Electrospun mats from styrene/maleic anhydride copolymers: modification with amines and assessment of antimicrobial activity.

    Science.gov (United States)

    Ignatova, Milena; Stoilova, Olya; Manolova, Nevena; Markova, Nadya; Rashkov, Iliya

    2010-08-11

    New antimicrobial microfibrous electrospun mats from styrene/maleic anhydride copolymers were prepared. Two approaches were applied: (i) grafting of poly(propylene glycol) monoamine (Jeffamine® M-600) on the mats followed by formation of complex with iodine; (ii) modification of the mats with amines of 8-hydroxyquinoline or biguanide type with antimicrobial activity. Microbiological screening against S. aureus, E. coli and C. albicans revealed that both the formation of complex with iodine and the covalent attachment of 5-amino-8-hydroxyquinoline or of chlorhexidine impart high antimicrobial activity to the mats. In addition, S. aureus bacteria did not adhere to modified mats.

  14. Space charge behaviour in maleic anhydride grafted polyethylene/ethylene - vinyl - acetate copolymer laminates

    Science.gov (United States)

    Lee, Seung Hyung; Park, Jung Ki; Han, Jae Hong; Suh, Kwang S.

    1997-01-01

    Charge distributions in maleic anhydride (MAH) grafted polyethylene (g-PE)/ethylene - vinyl - acetate (EVA) copolymer laminates have been measured with materials of different composition. All laminates showed interfacial charge, the polarity and the magnitude of which are explained by interfacial polarization. It was found that the interfacial charge increased with the increase of MAH content in the g-PE, whereas it decreased with the increase of vinyl - acetate content in the EVA. This feature was attributed to the differences in electrical conductivity of the materials. Details of the experimental results are described.

  15. Crystal structure of γ-ethyl-l-glutamate N-carb-oxy anhydride.

    Science.gov (United States)

    Kanazawa, Hitoshi; Inada, Aya

    2015-01-01

    In the title compound (alternative name N-carboxy-l-glutamic anhydride γ-ethyl ester), C8H11NO5, the oxazolidine ring is essentially planar, with a maximum deviation of 0.019 (2) Å. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds between the imino group and the carbonyl O atom in the ethyl ester group, forming a tape structure along the c-axis direction. The oxazolidine rings of adjacent tapes are arranged into a layer parallel to the ac plane. This arrangement is favourable for the polymerization of the title compound in the solid state.

  16. Langmuir and Langmuir-Blodgett films of a maleic anhydride derivative: effect of subphase divalent cations.

    Science.gov (United States)

    Martín-García, B; Velázquez, M Mercedes; Pérez-Hernández, J A; Hernández-Toro, J

    2010-09-21

    We report the study of the equilibrium and dynamic properties of Langmuir monolayers of poly(styrene-co-maleic anhydride) partial 2-buthoxyethyl ester cumene terminated polymer and the effect of the Mg(NO(3))(2) addition in the water subphase on the film properties. Results show that the polymer monolayer becomes more expanded when the electrolyte concentration in the subphase increases. Dense polymer films aggregate at the interface. The aggregates are transferred onto silicon wafers using the Langmuir-Blodgett methodology and the morphology is observed by AFM. The structure of aggregates depends on the subphase composition of the Langmuir film transferred onto the silicon wafer.

  17. POLYMER—SUPPORTED RHODIUM CATALYSTS FOR CARBONYLATION OF METHYL ACETATE TO ACETIC ANHYDRIDE

    Institute of Scientific and Technical Information of China (English)

    CHENDean; HUANGShizhuan; 等

    1993-01-01

    Two kinds of rhodium catalysts supported on cross-linked styrene-divinylbenzene copolymers containing bipyridine or o-phenylene diamine have been prepared and found to display high activity for methyl acetate carbonylation to form acetic anhydride,the activities are even higher than their homogeneous counterparts. XPS analysis was used to characterize the synthetic catalysts.The apparent activation parameters were determined to be Eα=73.3KJ/mol,ΔH≠=66.3KJ/mol,ΔS≠=-28.6eu.These parameters are very close to those in methanol carbonylation and imply to have analogous mechanism in both cases.

  18. Curing Mechanism of Condensed Polynuclear Aromatic Resin and Thermal Stability of Cured Resin

    Institute of Scientific and Technical Information of China (English)

    Li Shibin; Sun Qiqian; Wang Yuwei; Wu Mingbo; Zhang Zailong

    2015-01-01

    In order to improve the thermal stability of condensed polynuclear aromatic (COPNA) resin synthesized from vacuum residue, 1,4-benzenedimethanol was added to cure COPNA resin. The curing mechanism was investigated by pro-ton nuclear magnetic resonance spectrometry, solid carbon-13 nuclear magnetic resonance spectrometry and Fourier trans-form infrared spectroscopy. Microstructures of the uncured and the cured COPNA resins were studied by scanning electron microscopy and X-ray diffractometry. The thermal stability of COPNA resins before and after curing was tested by thermo-gravimetric analysis. The element composition of the cured COPNA resin heated at different temperatures was analyzed by an element analyzer. The results showed that the uncured COPNA resin reacted with the cross-linking agent during the cur-ing process, and the curing mechanism was conifrmed to be the electrophilic substitution reaction. Compared with the un-cured COPNA resin, the cured COPNA resin had a smooth surface, well-ordered and streamlined sheet structure with more crystalline solids, better molecular arrangement and orientation. The weight loss process of the uncured and cured COPNA resins was divided into three stages. Carbon residue of the cured COPNA resin was 41.65%at 600℃, which was much higher than 25.02%of the uncured COPNA resin, which indicated that the cured COPNA resin had higher thermal stability.

  19. Subcutaneous and intermuscular fat characterisation of dry-cured Iberian hams.

    Science.gov (United States)

    Timón, M L; Ventanas, J; Carrapiso, A I; Jurado, A; García, C

    2001-05-01

    The fatty acid composition of the triacylglycerols and free fatty acids of subcutaneous (internal and superficial layers) and intermuscular fat and the contribution of these fatty acids to the formation of volatile compounds were determined in dry-cured Iberian ham. The profile of the fatty acids and volatile compounds showed that lipolytic and oxidative processes occur more intensively in subcutaneous than intermuscular fat, however, few differences were found compared to those found in ham lean.

  20. Dental resin cure monitoring by inherent fluorescence

    Science.gov (United States)

    Li, Qun; Zhou, Jack X.; Li, Qingxiong; Wang, Sean X.

    2008-02-01

    It is demonstrated that the inherent fluorescence of a dental composite resin can be utilized to monitor the curing status, i.e. degree of conversion of the resin. The method does not require any sample preparation and is potentially very fast for real time cure monitoring. The method is verified by Raman spectroscopy analysis.

  1. 7 CFR 29.6010 - Cured.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Cured. 29.6010 Section 29.6010 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Definitions § 29.6010 Cured. Tobacco dried of its sap by either natural or...

  2. Properties of Cement Mortar with Phosphogpysum under Steam Curing Condition

    Directory of Open Access Journals (Sweden)

    Kyoungju Mun

    2008-01-01

    Full Text Available The purpose of this study is to utilize waste PG as an admixture for concrete products cured by steam. For the study, waste PG was classified into 4 forms (dehydrate, β-hemihydrate, III-anhydrite, and II-anhydrite, which were calcined at various temperatures. Also, various admixtures were prepared with PG, fly-ash (FA, and granulated blast-furnace slag (BFS. The basic properties of cement mortars containing these admixtures were analyzed and examined through X-ray diffraction, scanning electron microscopy, compressive strength, and acid corrosion resistance. According to the results, cement mortars made with III-anhydrite of waste PG and BFS exhibited strength similar to that of cement mortars made with II-anhydrite. Therefore, III-anhydrite PG calcined at lower temperature can be used as a steam curing admixture for concrete second production.

  3. 9 CFR 319.103 - Cured beef tongue.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Cured beef tongue. 319.103 Section 319... Cured beef tongue. In preparing “Cured Beef Tongue,” the application of curing solution to the fresh beef tongue shall not result in an increase in the weight of the cured beef tongue of more than...

  4. Curing agent for polyepoxides and epoxy resins and composites cured therewith. [preventing carbon fiber release

    Science.gov (United States)

    Serafini, T. T.; Delvigs, P.; Vannucci, R. D. (Inventor)

    1981-01-01

    A curing for a polyepoxide is described which contains a divalent aryl radical such as phenylene a tetravalent aryl radical such as a tetravalent benzene radical. An epoxide is cured by admixture with the curing agent. The cured epoxy product retains the usual properties of cured epoxides and, in addition, has a higher char residue after burning, on the order of 45% by weight. The higher char residue is of value in preventing release to the atmosphere of carbon fibers from carbon fiber-epoxy resin composites in the event of burning of the composite.

  5. Performance of epoxy resin-anhydride pouring materials modified with hyperbranched polyester%超支化聚酯改性环氧-酸酐浇注树脂及性能研究

    Institute of Scientific and Technical Information of China (English)

    井丰喜; 石兆从; 张道洪

    2016-01-01

    The epoxy pouring resin was prepared by using the hydroxyl-terminated hyperbranched polyester, epoxy resin, methyl tetrahydrophthalic anhydride and silica powder as the main materials. The effects of hyperbranched polyester as the addictive on the viscosity, settleability, heat-resistance, mechanical and electrical properties of the cured pouring resin were in detail studied. The results showed that hyperbranched polyester not only increased the heat-resistance, mechanical and electrical properties of the cured pouring resin, but also effectively dispersed the silica powder into the pouring resin and improved the evenness of the mixing system.%采用端羟基超支化聚酯、环氧树脂、甲基四氢苯酐和活性硅微粉为主要材料制备了高性能环氧浇注树脂。研究了超支化聚酯对体系黏度、沉降性、耐温指数、机械性能和电性能的影响及其规律。结果表明,超支化聚酯可有效分散硅微粉,提高混合体系的均匀度,提高浇筑树脂的耐热性、机械强度和电性能。

  6. Soluble Synthetic Analogs of Malaria Pigment: Structure of Mesohematin Anhydride [FeIII(MP-IX)]2 and Solution Interaction with Chloroquine

    Energy Technology Data Exchange (ETDEWEB)

    D Bohle; E Dodd; A Kosar; L Sharma; P Stephens; L Suarez; D Tazoo

    2011-12-31

    Changing the vinyl groups of hematin anhydride to either ethyl or hydrogen groups results in increased solubility (Por=porphyrin). Determination of the weak binding constants of the antimalarial drug chloroquine to dimers of these hematin anhydride analogues suggests that solution-phase heme/drug interactions alone are unlikely to be the origin of the action of the drug.

  7. SELECTIVE HYDROGENATION OF MALEIC ANHYDRIDE TO Y-BUTYROLACTONE OVER PD/AL(2)O(3) CATALYST USING SUPERCRITICAL CO(2) AS SOLVENT

    Science.gov (United States)

    A selective hydrogenation of maleic anhydride to either y-butyrolactone or succinic anhydride over simple Pd/Al(2)O(3) catalyst under supercritical CO(2) medium is described for the first time which has considerable promise for obht lab-scale as well as industrial selective hydro...

  8. CHARGE-TRANSFER AND ENERGY-TRANSFER IN THE PHOTO-INDUCED COPOLYMERIZATION OF 2-VINYLNAPHTHALENE WITH MALEIC ANHYDRIDE

    Institute of Scientific and Technical Information of China (English)

    LI Tong; LUO Bin; LI Shanjun; CHU Guobei

    1990-01-01

    The initiation mechanism of the copolymerization of 2-vinylnaphthalene with maleic anhydride was studied under irradiation of 365 nm. The excited complex was formed from ( 1 ) the local excitation of 2-vinylnaphthalene followed by the charge-transfer interaction with maleic anhydride and ( 2 ) the excitation of the ground state charge-transfer complex, and then it collapsed to 1,4-tetramethylene biradical for initiation. A 1:1 alternating copolymer was formed in different monomer feeds. Addition of benzophenone could greatly enhance the rate of copolymerization through energy-transfer mechanism.

  9. Pomelo peel modified with acetic anhydride and styrene as new sorbents for removal of oil pollution.

    Science.gov (United States)

    Chai, Wenbo; Liu, Xiaoyan; Zou, Junchen; Zhang, Xinying; Li, Beibei; Yin, Tiantian

    2015-11-01

    Pomelo peel (PP), as one of the well-known agricultural wastes, is cost-effective and environmentally friendly. Based on PP, two new kinds of oil sorbents were prepared by using acetic anhydride and styrene. The structures of raw pomelo peel (RP), acetic anhydride-treated pomelo peel (AP) and styrene-treated pomelo peel (SP) were characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM), contact-angle (CA) measurements. The optimum reaction conditions for preparation of AP and SP were also investigated. The resulting products exhibited better oil sorption capacity than that of RP for diesel and lubricating oil, also SP had better oil sorption capacity than AP, while the oil sorption capacities of SP for diesel and lubricating oil reached 18.91 and 26.36 g/g, respectively. Adsorption kinetics was well described by the pseudo-second-order model. The results indicated that AP and SP, especially SP could be used as the substitute for non-biodegradable oil sorption materials.

  10. Characterization and in vitro degradation of salicylate-derived poly(anhydride-ester microspheres).

    Science.gov (United States)

    Yeagy, Brian A; Prudencio, Almudena; Schmeltzer, Robert C; Uhrich, Kathryn E; Cook, Thomas J

    2006-09-01

    The aim of this study was to investigate how glass transition temperature (Tg) influenced polymer microsphere formation and degradation of three chemically, similar novel salicylatebased poly(anhydride-esters): poly[1,6-bis(o-carboxyphenoxy)hexanoate] (CPH), Tg = 59 degrees C; poly[1,8-bis(o-carboxyphenoxy)octanoate] (CPO), Tg = 30 degrees C; and poly[1,10-bis(ocarboxyphenoxy) decanoate] (CPD), Tg = 27 degrees C. Microspheres of these polymers were prepared using a modified oil-in-water solvent evaporation method and processed by either resuspension or washed by centrifugation. The morphology of the microspheres determined by scanning electron microscopy (SEM) revealed that an extra washing step appears to increase aggregation as the Tg decreases; whereas only limited aggregation occurred in the polymer with the lowest Tg, CPD, in those not washed by centrifugation. Residual polyvinyl alcohol apparently affected the drug release rates from the microspheres by a stabilization process that produced an 8 h lag time and a 5% decrease in the amount of drug released over a 7 day period compared to microspheres washed free of PVA. These results demonstrate that salicylate-based poly(anhydride-esters) with sufficiently high Tgs, can be processed into microspheres that release salicylate over a time period amenable for drug delivery applications.

  11. Flexible Polyimide Aerogel Cross-linked by Poly(maleic Anhydride-alt-alkylene)

    Science.gov (United States)

    Guo, Haiquan; Meador, Mary Ann B.; Wilkewitz, Brittany Marie

    2014-01-01

    Aerogels are potential materials for aerospace applications due to their lower thermal conductivity, lighter weight, and low dielectric constant. However, silica aerogels are restricted due to their inherent fragility, hygroscopic nature, and poor mechanical properties, especially in extreme aerospace environments. In order to fit the needs of aerospace applications, developing new thermal insulation materials that are flexible, and moisture resistant is needed. To this end, we fabricated a series of polyimide aerogels crosslinked with different poly(maleic anhydride-alt-alkylene)s as seen in Scheme 1. The polyimide oligomers were made with 3,3,4,4-biphenyltetracarboxylic dianhydride (BPDA), and different diamines or diamine combinations. The resulting aerogels have low density (0.06 gcm3 to 0.16 gcm3) and high surface area (240-440 m2g). The effect of the different backbone structures on density, shrinkage, porosity, surface area, mechanical properties, moisture resistance and thermal properties will be discussed. These novel polyalkylene-imide aerogels may be potential candidates for applications such as space suit insulation for planetary surface missions, insulation for inflatable structures for habitats, inflatable aerodynamic decelerators for entry, descent and landing (EDL) operations, and cryotank insulation for advance space propulsion systems. Scheme 1. Network of polyimide aerogels crosslinked with deifferent poly(maleic anhydride).

  12. Efficient photochemical generation of peroxycarboxylic nitric anhydrides with ultraviolet light emitting diodes

    Directory of Open Access Journals (Sweden)

    N. D. Rider

    2015-01-01

    Full Text Available Photochemical sources of peroxycarboxylic nitric anhydrides (PANs are utilized in many atmospheric measurement techniques for calibration or to deliver an internal standard. Conventionally, such sources rely on phosphor-coated low-pressure mercury (Hg lamps to generate the UV light necessary to photo-dissociate a dialkyl ketone (usually acetone in the presence of a calibrated amount of nitric oxide (NO and oxygen (O2. In this manuscript, a photochemical PAN source in which the Hg lamp has been replaced by arrays of ultraviolet light-emitting diodes (UV-LEDs is described. The output of the UV-LED source was analyzed by gas chromatography (PAN-GC and thermal dissociation cavity ring-down spectroscopy (TD-CRDS. Using acetone, diethyl ketone (DIEK, diisopropyl ketone (DIPK, or di-n-propyl ketone (DNPK, respectively, the source produces peroxyacetic (PAN, peroxypropionic (PPN, peroxyisobutanoic (PiBN, or peroxy-n-butanoic nitric anhydride (PnBN from NO in high yield (> 90%. Box model simulations with a subset of the Master Chemical Mechanism (MCM were carried out to rationalize products yields and to identify side products. The use of UV-LED arrays offers many advantages over conventional Hg lamp setups, including greater light output over a narrower wavelength range, lower power consumption, and minimal generation of heat.

  13. Interaction and release of catechin from anhydride maleic-grafted polypropylene films.

    Science.gov (United States)

    López de Dicastillo, Carol; Castro-López, Maria Del Mar; Lasagabaster, Aurora; López-Vilariño, Jose M; González-Rodríguez, M Victoria

    2013-04-24

    In this paper, investigations were carried out on catechin-loaded maleic anhydride (MAH)-modified polypropylenes (PP). Two maleic-modified polypropylenes (PPMAH) with different maleic concentrations have been blended with PP and catechin to obtain composites of improved catechin retention with the aim of studying the possible interactions between these grafted polymers with antioxidants, and a secondary interest in developing an active antioxidant packaging. Composite physicochemical properties were measured by thermal analysis (thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and oxidation induction time (OIT)) and infrared spectroscopy studies. Catechin release profiles into food simulants were obtained by HPLC-PDA-QqQ, following European legislation. Antiradical activity of composites was analyzed by the ABTS and DPPH method. The formation of intermolecular hydrogen bonds between catechin and functionalized PP has been confirmed by Fourier transform infrared (FTIR) studies. Besides, a small fraction of ester bonds, formed as a result of a chemical reaction between a fraction of the hydrolyzed anhydride and the catechin hydroxyl groups, is not discarded. OIT results also showed an increase in antioxidant effectiveness caused by the presence of catechin- and maleic-modified PPMAH in the blend formulations. Incorporation of MAH-grafted PP increased substantially the retention rate of catechin, being dependent on the MAH content of the grafted polypropylene. The described interactions between catechin and maleic groups, together with changes in PP morphology in comparison with reference PP explained lower antioxidant release. Besides formulation, antioxidant release was dependent on the type of food, the temperature, and the time.

  14. Polycondensation of Tetrahydrofuran with Phthalic Anhydride Induced By a Proton Exchanged Montmorillonite Clay

    Directory of Open Access Journals (Sweden)

    Mohammed Belbachir

    2003-05-01

    Full Text Available Abstract: “Maghnite” a montmorillonite sheet silicate clay, exchanged with protons to produce “H-Maghnite” is an efficient catalyst for polymerization of many vinylic and heterocyclic monomers (Belbachir, M. U.S. Patent. 066969.0101 –2001. The structure compositions of both “Maghnite” and “H-Maghnite” have been developed. This catalyst was used for the polycondensation of the tetrahydrofuran with phthalic anhydride. The polymerization was performed under suitable conditions at temperature (40°C, in presence of acetic anhydride. Experiments revealed that polymerization induced by “H-Maghnite”, proceed in bulk and the conversion increases with increasing “H-Maghnite” proportion.

  15. EFFECT OF MALEIC ANHYDRIDE ON KENAF DUST FILLED POLYCAPROLACTONE/THERMOPLASTIC SAGO STARCH COMPOSITES

    Directory of Open Access Journals (Sweden)

    Siang Yee Chang,

    2012-02-01

    Full Text Available The utilization of biodegradable polymers for various applications has been restricted mainly by its high cost. This report aims to study the water absorption and mechanical properties of kenaf dust-filled polycaprolactone/thermoplastic sago starch biodegradable composites as a function of filler loading and treatment with maleic anhydride. While water absorption in untreated biocomposites increased as a function of filler loading, treated biocomposites resulted in weight loss, whereby low molecular weight substances were dissolved into the aging medium. The kenaf dust imparts reinforcing effects on the biocomposites, resulting in improved mechanical properties. This is further attested by morphological studies in which kenaf dust was well dispersed in the polycaprolactone/ thermoplastic sago starch blend matrix. The addition of maleic anhydride into the polycaprolactone/thermoplastic sago starch blend resulted in a homogeneous mixture. At low filler loading, strain at break of the maleated polycaprolactone/thermoplastic sago starch blend increased at the expense of tensile strength and modulus. This is most likely due to the excessive dicumyl peroxide content, which caused chain scission of the polycaprolactone backbone. Tensile strength and modulus improved only when high filler loading was employed.

  16. Synthesis and properties of starch-g-poly(maleic anhydride-co-vinyl acetate

    Directory of Open Access Journals (Sweden)

    2010-01-01

    Full Text Available Starch-g-poly(maleic anhydride-co-vinyl acetate (SMV was synthesized via the esterification reaction of starch with the copolymer of maleic anhydride and vinyl acetate. The carboxylic unit percentage (CUP of SMV was tailored with reaction conditions, and it ranged from 29.8 to 46.9%. The structure and the morphology of the copolymers were characterized with Fourier Transform Infrared spectroscopy and X-ray diffraction analysis. It was found that SMV could form complex with some metal cations such as Ca2+, Pb2+ and Hg2+ or cationic polyelectrolyte chitosan, and precipitate from the solution. The weight of precipitation increases with an increase of the CUP of SMV. In addition, a physically cross-linked hydrogel of SMV/poly(vinyl alcohol (PVA was obtained by freeze/thaw technique. Scanning electron microscopy exhibited the hydrogel was uniform. The gel exhibited pH-responsive re-swelling. The maximum swelling-ratio values of SMV/PVA (9:1, wt/wt gel were 3.29 and 5.34 in HCl (pH 1.0 and phosphate-buffer saline (PBS (pH 12 respectively.

  17. 茶油皂脚脂肪酸甲酯制备的水溶性改性胺固化物性能研究%Properties of the Cured Water-soluble Modified Amine from Fatty Acid Methyl Esters of Tea Oil Soapstock

    Institute of Scientific and Technical Information of China (English)

    李梅; 夏建陵; 黄坤; 连建伟

    2011-01-01

    以茶油皂脚脂肪酸甲酯制备的水溶性改性胺(CA-921)与水性环氧树脂固化,通过热重分析、差示扫描量热法(DSC)、机械性能测试及扫描电镜分析,研究了环氧树脂分散相粒子的粒径和黏度、环氧基与胺氢物质的量之比及固化温度对固化物性能的影响.研究结果表明,黏度及粒径均较小的水性环氧乳液AB-EP-20与固化剂CA-921复配所得漆膜热稳定性较佳;水性环氧体系AB-EP-20/CA-921在环氧基与胺氢物质的量之比为1.1∶1、室温下固化3h后60℃固化3h的条件下,固化物的综合性能最佳,此时漆膜的柔韧性为1mm、铅笔硬度2H、附着力1级、耐冲击性≥50 kg·cm、耐水性(25℃)≥7 d、耐醇性≥30 d.%The effects of the diameter and viscosity of epoxy resin dispersion, the molar ratio of epoxy group to amino hydrogen and the curing temperature on the properties of the cured water soluble modified amine from fatty acid methyl esters of tea oil soapstock were investigated by thermal gravimetric analysis (TGA) , differential scanning calorimetry ( DSC) , mechanical property test and scanning electron microscopy ( SEM ). It was shown from the results that the thermal stability of the cured film from the water-soluble modified amine CA-921 and the epoxy emulsion AB-EP-20 with smaller particle size and lower viscosity was better. When the water-soluble modified amine CA-921 cured wilh the epoxy emulsion AB-EP-20 in molar ratio of epoxy group to amine hydrogen 1.1:1 at room temperature for 3 h and then 60 ℃ for 3 h, the cured film exhibited the optimum properties with flexibility 1 mm, pencil hardness 2 H, adhesion 1, impact resistance ≥50 kg·cm, water-resistance(25 ℃)≥7 d and alcohol-resistance ≥30 d respectively.

  18. Ultrasound-assisted catalytic synthesis of acyclic imides in the presence of p-toluenesulfonic acid under solvent free conditions

    Directory of Open Access Journals (Sweden)

    Nasr-Esfahani Masoud

    2012-01-01

    Full Text Available A rapid and convenient preparation of acyclic imides by the reaction of aliphatic and aromatic nitriles with acyclic carboxylic anhydride in the presence of catalytic amounts of p-toluenesulfonic acid under thermal or ultrasonic conditions is reported. The advantages of this procedure are moderate reaction times, good to excellent yields, use of inexpensive and ecofriendly catalyst. The reaction of nitriles with aliphatic anhydrides proceeds in thermal conditions, while by the use of ultrasound irradiations these reactions get accelerated.

  19. Polymerization and curing kinetics of furan resins under conventional and microwave heating

    Energy Technology Data Exchange (ETDEWEB)

    Lopez de Vergara, Unai, E-mail: bergara@gaiker.es [Plastics and Composites Department, Gaiker IK4 Research Centre, Parque Tecnológico, Ed. 202, 48170 Zamudio Spain (Spain); Mechanical Engineering and Industrial Manufacturing Department, Mondragón Unibertsitatea, Loramendi 4, 20500 Mondragón Spain (Spain); Sarrionandia, Mariasun [Mechanical Engineering and Industrial Manufacturing Department, Mondragón Unibertsitatea, Loramendi 4, 20500 Mondragón Spain (Spain); Gondra, Koldo [Plastics and Composites Department, Gaiker IK4 Research Centre, Parque Tecnológico, Ed. 202, 48170 Zamudio Spain (Spain); Aurrekoetxea, Jon [Mechanical Engineering and Industrial Manufacturing Department, Mondragón Unibertsitatea, Loramendi 4, 20500 Mondragón Spain (Spain)

    2014-04-01

    Graphical abstract: - Highlights: • The furan resin structure was investigated using IR and RMN techniques. • The polymerization of furan resins was developed based on multistage kinetics. • Vyazovkin numerical analysis was found the most accurate kinetic method. • Microwave curing of furan resins was much faster than thermal curing. - Abstract: The challenge of this work is the microwave curing study of low free-furfuryl alcohol content furan resins. The chemical characterization of the furan resins has been made by infrared spectroscopy and nuclear magnetic resonance spectroscopy. The chemical composition of the resin and its reactions with p-toluensulfonic acid are proposed, with the aim of understanding the mechanism responsible for the main reactions. The results show the presence of methyl and ether bridges between the furan rings, and the formation of ketone and conjugated structures. Furthermore, the curing kinetics of the furan resins has been characterized by differential scanning calorimetry. Different methods have been applied in order to obtain and compare the activation energy of the process. Vyazovkin numerical analysis was found the most accurate method. Finally, microwave and conventional curing processes has been compared. The analysis showed that microwave curing of furan resins was twice faster than thermal curing.

  20. Gas-Phase Partial Oxidation of Lignin to Carboxylic Acids over Vanadium Pyrophosphate and Aluminum-Vanadium-Molybdenum.

    Science.gov (United States)

    Lotfi, Samira; Boffito, Daria C; Patience, Gregory S

    2015-10-26

    Lignin is a complex polymer that is a potential feedstock for aromatic compounds and carboxylic acids by cleaving the β-O-4 and 5-5' linkages. In this work, a syringe pump atomizes an alkaline solution of lignin into a catalytic fluidized bed operating above 600 K. The vanadium heterogeneous catalysts convert all the lignin into carboxylic acids (up to 25 % selectivity), coke, carbon oxides, and hydrogen. Aluminum-vanadium-molybdenum mostly produced lactic acid (together with formic acid, acrylic acid, and maleic anhydride), whereas the vanadium pyrophosphate catalyst produced more maleic anhydride.

  1. Comparison of Catalysts Preyssler and Silica-Supported Nano Preyssler in the Synthesis of Acetyl Salicylic Acid

    Directory of Open Access Journals (Sweden)

    H. Nazari

    2012-01-01

    Full Text Available The extensive demand for cleaner environment is forcing chemical industry to use less hazardous materials. In this regard, heteropolyacids attracted considerable amount of interest due to the less toxic behavior in addition of possessing higher acidity. Heteropoly acids have been used as catalysts for the reaction of salicylic acid with acetic anhydride. The performance of different forms of heteropoly acids in the presence of acetic anhydride as acetylating agent for acetylation of salicylic acid was compared. The best conditions were observed using Preyssler and Silica-supported Preyssler Nanoparticles as catalysts. The catalyst is recyclable and reusable.

  2. Dry cured ham quality as related to lipid quality of raw material and lipid changes during processing: a review.

    OpenAIRE

    Gilles, Gandemer

    2009-01-01

    Lipids play a key role in sensory traits of dry cured hams. Both the quantity and the composition of lipids in raw material affect dry-cured hams quality. The lipid characteristics strongly depend on rearing systems developed in different area in Europe. During processing, lipids undergo lipolysis and oxidation. Phospholipids are the main substrates of both lipolysis and oxidation. Lipolysis forms free fatty acids rich in polyunsaturated fatty acids all along the process. Lipids are also subj...

  3. Thermal curing of an epoxy-anhydride system modified with hyperbranched poly(ethylene imine)s with different terminal groups

    OpenAIRE

    Morancho Llena, José María; Fernández Francos, Xavier; Acebo Gorostiza, Cristina; Ramis Juan, Xavier; Salla Tarragó, José María; Serra Albet, Àngels

    2015-01-01

    Epoxy resins are widely used in applications such as adhesives, coatings, electric laminates, encapsulation of semiconductor devices, matrix material for composites, structural components and cryogenic engineering because of their mechanical properties, adhesion and chemical resistance. However, epoxy resins are inherently brittle due to their high cross-link density. To increase their toughness different modifiers such as rubber, thermoplastic and glass particles can be added, but they al...

  4. Curing efficiency of modern LED units.

    Science.gov (United States)

    Rencz, Adam; Hickel, Reinhard; Ilie, Nicoleta

    2012-02-01

    Recent reports claim that modern light-emitting diode (LED) curing units improve curing efficiency by increasing the units' irradiance. In this context also, short polymerisation times up to 5 s are proposed. The aim of this study was to examine whether there are differences in the curing efficiency of modern LED curing units by assessing their effect on two different composite materials and by varying the irradiation time. A nano- and a micro-hybrid resin-based composite (RBC) were polymerised for 5, 10 and 20 s with three commercial and a Prototype LED unit (Elipar™ S10). Cylindrical specimens (6 mm in depth, 4 mm in diameter) were prepared in three increments, each 2-mm thick, and were consecutively cured. Degree of cure was measured for 20 min in real time at the bottom of the samples, starting with the photoinitiation. The micro-mechanical properties (modulus of elasticity, E and Vickers hardness, HV) were measured as a function of depth, in 100-μm steps, on the above described samples stored in distilled water for 24 h at 37°C. Data were analysed with multivariate ANOVA followed by Tukey's test, t test and partial eta-squared statistics. In descending order of the strength of their effect, the type of RBC, depth, polymerisation time and curing unit were significant factors affecting the micro-mechanical parameters (p surface, a minimum of 20 s of irradiation is necessary for an adequate polymerisation 2 mm beyond the surface.

  5. One-step microwave foaming and curing

    Science.gov (United States)

    Gagliani, J.; Lee, R.; Sorathia, U. A. K.; Wilcoxson, A. L.

    1981-01-01

    Process that combines microwave foaming and curing of polyimide precursors in single step produces fire-resistant foam slabs of much larger volume than has previously been possible. By adding selected conductive fillers to powder precursors and by using high-power microwave oven, foam slabs with dimensions in excess of 61 by 61 by 7.6 cm are made. Typical foaming and curing and curing time is 35 minutes in microwave oven with additional 1 to 2 hour postcure in conventional oven.

  6. PREPARATION AND PROPERTIES OF THERMOSETTING ACRYLIC COATINGS USING TITANIUM-OXO-CLUSTER AS A CURING AGENT

    Institute of Scientific and Technical Information of China (English)

    Kun Xu; Shu-xue Zhou; Li-min Wu

    2009-01-01

    Thermosetting acrylic coatings were prepared by using carboxyl acid group-containing acrylic oligomer and curing with titanium-oxo-clusters which were first pre-hydrolyzed from titanium n-butoxide. The curing ability of the titanium-oxo-cluster was examined using a microdielectric analytical (DEA) curing monitor, Fourier transformed infrared spectroscopy (FTIR), and Soxhlet extraction experiments, and the properties of the resulted coatings were investigated with pendulum hardness tester, dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA) and ultraviolet-visible spectrometer. The effect of titania-oxo-cluster in leading acrylic oligomers to form thermosetting acrylic coatings was confirmed. An increasing pendulum hardness and modulus of acrylic coatings with increasing titania content was observed, which resulted from the increment of crosslinking degree rather than of the titania content. The thermosetting acrylic/titania coatings also showed better thermal stability and higher UV-blocking properties than those coatings using organic curing agent.

  7. Acceleration of curing of resin composite at the bottom surface using slow-start curing methods.

    Science.gov (United States)

    Yoshikawa, Takako; Morigami, Makoto; Sadr, Alireza; Tagami, Junji

    2013-01-01

    The aim of this study was to evaluate the effect of two slow-start curing methods on acceleration of the curing of resin composite specimens at the bottom surface. The light-cured resin composite was polymerized using one of three curing techniques: (1) 600 mW/cm(2) for 60 s, (2) 270 mW/cm(2) for 10 s+0-s interval+600 mW/cm(2) for 50 s, and (3) 270 mW/cm(2) for 10 s+5-s interval+600 mW/cm(2) for 50 s. After light curing, Knoop hardness number was measured at the top and bottom surfaces of the resin specimens. The slow-start curing method with the 5-s interval caused greater acceleration of curing of the resin composite at the bottom surface of the specimens than the slow-start curing method with the 0-s interval. The light-cured resin composite, which had increased contrast ratios during polymerization, showed acceleration of curing at the bottom surface.

  8. [Mineral water as a cure].

    Science.gov (United States)

    Nocco, Priska Binz

    2008-01-01

    The treatment of diseases with mineral spring water belongs to the oldest medical therapies. The "remedy" mineral water is therefore of importance also within the pharmacy. The present pharmacy historical work examines the impact of the use of mineral waters, as well as of their dried components, as therapeutic agents in the 19th and early 20th centuries, i.e. from approx. 1810 to 1930, as well as the contributions given by pharmacists in the development and analysis of mineral water springs. Beside these aspects, the aim here is also to describe the role played by pharmacists in the production of artificial mineral water as well as in the sale and wholesale of natural and artificial mineral water. In the first part of this work the situation in Switzerland and its surrounding countries, such as Germany, France, Italy and Austria, is discussed. The second part contains a case-study of the particular situation in the Canton Tessin. It is known from the scientific literature published at that time that information on mineral water was frequently reported. Starting from the beginning of the 19th century the number of such publications increased tremendously. The major part of them were publications in scientific journals or contributions to medical and pharmaceutical manuals and reference books. In particular the spa-related literature, such as spa-guides, was of growing interest to a broad public. The inclusion of monographs into the Swiss, the Cantonal as well the foreign pharmacopoeias granted a legal frame for the mineral waters and their dried components. These works are of major importance from a pharmacy historical standpoint and represent a unique proof of historical evidence of the old medicinal drug heritage. The most frequently used therapies based on mineral waters were drinking and bath cures. Several diseases, particularly those of a chronic character, were treated with mineral waters. The positive influence of these cures on the recovery of the patients

  9. High-Performance Liquid Chromatographic Determination of Oxytetracycline Residue in Cured Meat Products

    OpenAIRE

    ŞENYUVA, Hamide; ÖZDEN, Tuncel; SARICA, Deniz Yurtsever

    2000-01-01

    The development of a sensitive automated method for residue control of oxytetracycline (OTC) in cured meat (soudjouk) is described. The principle steps involve the extraction of OTC from cured meat in the presence of citric acid with nitric acid, methanol and de-ionized water, and then the determination by HPLC. In HPLC, Hypersil BDC C18 column was used and OTC was separated at 24 oC using a mobile phase of H2O (pH=2.10 with H2SO4): ACN (85:15, v/v) at a flow rate of 1.5 ml/min. A variable wa...

  10. Kinetics of Hydrolysis of Acetic Anhydride by In-Situ FTIR Spectroscopy: An Experiment for the Undergraduate Laboratory

    Science.gov (United States)

    Haji, Shaker; Erkey, Can

    2005-01-01

    A reaction kinetics experiment for the chemical engineering undergraduate laboratory course was developed in which in-situ Fourier Transfer Infrared spectroscopy was used to measure reactant and product concentrations. The kinetics of the hydrolysis of acetic anhydride was determined by experiments carried out in a batch reactor. The results…

  11. RAFT copolymerization of itaconic anhydride and 2-methoxyethyl acrylate: a multifunctional scaffold for preparation of “clickable” gold nanoparticles

    DEFF Research Database (Denmark)

    Javakhishvili, Irakli; Kasama, Takeshi; Jankova, Katja Atanasova

    2013-01-01

    RAFT copolymerization of 2-methoxyethyl acrylate and itaconic anhydride – a monomer derived from renewable resources – is carried out in a controlled fashion. The copolymer allows preparation of gold nanoparticles with abundant surficial carboxyl and alkyne functional groups that are dendronized ...... via Cu(i)-mediated “click” reaction....

  12. Light-cured resin for post patterns.

    Science.gov (United States)

    Waldmeier, M D; Grasso, J E

    1992-09-01

    A method of using light-cured acrylic resin as an alternative to the use of chemically-cured acrylic resins with elastomeric impressions for direct post patterns is presented. The GC Unifast LC acrylic resin is a powder/liquid type resin cured by exposure to visible light. The polymerization process has four stages before final curing: slurry, stringy, dough-like (plastic), and rubber-like (elastic). Advantages over current direct and indirect procedures include ease of manipulation of the material and no change in laboratory handling procedures. While in the dough-like state, the material can be contoured. In the rubber-like state, it is flexible to disengage from minor undercut areas.

  13. Fast Curing of Composite Wood Products

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Arthur J. Ragauskas

    2006-04-26

    The overall objective of this program is to develop low temperature curing technologies for UF and PF resins. This will be accomplished by: • Identifying the rate limiting UF and PF curing reactions for current market resins; • Developing new catalysts to accelerate curing reactions at reduced press temperatures and times. In summary, these new curing technologies will improve the strength properties of the composite wood products and minimize the detrimental effects of wood extractives on the final product while significantly reducing energy costs for wood composites. This study is related to the accelerated curing of resins for wood composites such as medium density fiberboard (MDF), particle board (PB) and oriented strandboard (OSB). The latter is frequently manufactured with a phenol-formaldehyde resin whereas ureaformaldehyde (UF) resins are usually used in for the former two grades of composite wood products. One of the reasons that hinder wider use of these resins in the manufacturing of wood composites is the slow curing speed as well as inferior bondability of UF resin. The fast curing of UP and PF resins has been identified as an attractive process development that would allow wood to be bonded at higher moisture contents and at lower press temperatures that currently employed. Several differing additives have been developed to enhance cure rates of PF resins including the use of organic esters, lactones and organic carbonates. A model compound study by Conner, Lorenz and Hirth (2002) employed 2- and 4-hydroxymethylphenol with organic esters to examine the chemical basis for the reported enhanced reactivity. Their studies suggested that the enhance curing in the presence of esters could be due to enhanced quinone methide formation or enhanced intermolecular SN2 reactions. In either case the esters do not function as true catalysts as they are consumed in the reaction and were not found to be incorporated in the polymerized resin product. An

  14. Effect of cure cycle on curing process and hardness for epoxy resin

    Directory of Open Access Journals (Sweden)

    2009-09-01

    Full Text Available A 3-dimensional finite element model is developed to simulate and analyze the temperature and degree of cure field of epoxy casting part during cure process. The present model based on general finite element software ABAQUS is verified by literature example and experimental data. The numerical results show good agreement with literature example and measured data, and are even more accurate than the simulation of literature. After modeling successfully, the influence of temperature cure cycle ramps have on the temperature and degree of cure gradient is investigated. Moreover, the effect of non-uniform temperature and degree of cure field within epoxy casting part on hardness is demonstrated. The present model provides an accurate and novel method that allows further insight into the process of cure for epoxy resin.

  15. EVALUATION OF DIELECTRIC CURING MONITORING INVESTIGATING LIGHT-CURING DENTAL FILLING COMPOSITES

    Directory of Open Access Journals (Sweden)

    Johannes Steinhaus

    2011-05-01

    Full Text Available The aim of this study is the evaluation of a dielectric analysis (DEA method monitoring the curing behaviour of a light curing dental filling material in real-time. The evaluation is to extract the influence of light intensity on the photo-curing process of dental composite filling materials. The intensity change is obtained by measuring the curing process at different sample depth. It could be shown that increasing sample thickness, and therefore exponentially decreasing light intensity, causes a proportional decrease in the initial curing rate. Nevertheless, the results give rise to the assumption that lower illumination intensities over a long period cause higher overall conversion, and thus better mechanical properties. This would allow for predictions of the impact of different curing-rates on the final mechanical properties.

  16. High Power UV LED Industrial Curing Systems

    Energy Technology Data Exchange (ETDEWEB)

    Karlicek, Robert, F., Jr; Sargent, Robert

    2012-05-14

    UV curing is a green technology that is largely underutilized because UV radiation sources like Hg Lamps are unreliable and difficult to use. High Power UV LEDs are now efficient enough to replace Hg Lamps, and offer significantly improved performance relative to Hg Lamps. In this study, a modular, scalable high power UV LED curing system was designed and tested, performing well in industrial coating evaluations. In order to achieve mechanical form factors similar to commercial Hg Lamp systems, a new patent pending design was employed enabling high irradiance at long working distances. While high power UV LEDs are currently only available at longer UVA wavelengths, rapid progress on UVC LEDs and the development of new formulations designed specifically for use with UV LED sources will converge to drive more rapid adoption of UV curing technology. An assessment of the environmental impact of replacing Hg Lamp systems with UV LED systems was performed. Since UV curing is used in only a small portion of the industrial printing, painting and coating markets, the ease of use of UV LED systems should increase the use of UV curing technology. Even a small penetration of the significant number of industrial applications still using oven curing and drying will lead to significant reductions in energy consumption and reductions in the emission of green house gases and solvent emissions.

  17. Dual-Functional Hydrazide-Reactive and Anhydride-Containing Oligomeric Hydrogel Building Blocks.

    Science.gov (United States)

    Kascholke, Christian; Loth, Tina; Kohn-Polster, Caroline; Möller, Stephanie; Bellstedt, Peter; Schulz-Siegmund, Michaela; Schnabelrauch, Matthias; Hacker, Michael C

    2017-02-08

    Biomimetic hydrogels are advanced biomaterials that have been developed following different synthetic routes. Covalent postfabrication functionalization is a promising strategy to achieve efficient matrix modification decoupled of general material properties. To this end, dual-functional macromers were synthesized by free radical polymerization of maleic anhydride with diacetone acrylamide (N-(1,1-dimethyl-3-oxobutyl)acrylamide) and pentaerythritol diacrylate monostearate. Amphiphilic oligomers (Mn 40%). Efficient hydrazide/hydrazine immobilization depending on solution pH, hydrogel ketone content as well as ligand concentration for bioconjugation was shown and reversibility of hydrazone formation was indicated by physiologically relevant hydrazide release over 7 days. Proof-of-concept experiments with hydrazido-functionalized hyaluronan demonstrated potential for covalent aECM immobilization. The presented dual-functional macromers have perspective as reactive hydrogel building blocks for various biomedical applications.

  18. Synthesis of Poly(aryl amide imide)s Derived from o-diphenyltrimellitic Anhydride

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The synthesis and characterization of a series of novel poly(aryl amide imide)s based on o-diphenyltrimellitic anhydride are described.The poly(aryl amide-imide)s having inherent viscosities of 0.39-1.43dL/g in N-methyl-2-pyrrolidinone at 30℃,were prepared by polymerization with aromatic diamines in N,N-dimethylacetamide and subsequent chemical imidization.All the polymers were amorphous,readily soluble in aprotic polar solvents such as DMAC,NMP,DMF,DMSO,and m-cresol,and could be cast to form flexible and tough films.The glass trsanition temperatures were in the range of 284-336℃,and the temperatures for 5% weight loss in nitrogen were above 468℃.

  19. Oil recovery with sulfomethylated poly (lower alkyl vinyl ether/maleic anhydride)

    Energy Technology Data Exchange (ETDEWEB)

    Norton, C.J.; Falk, D.O.

    1973-05-22

    Lower alkyl vinyl ether e.g., methyl vinyl ether, propyl vinyl ether, isopropyl vinyl ether, hexyl vinyl ether, is copolymerized conventionally with maleic anhydride, the resulting copolymer is treated with ammonia or ammonium hydroxide to form the partial amide-ammonium salt, and this salt is in turn treated with formaldehyde and thereafter or simultaneously with ammonium or alkali metal salt sulfite (including bisulfites, etc.) to form an at least partially sulfomethylated copolymer. Aqueous solutions of the sulfomethylated copolymer are useful in increasing the viscosity of drive fluids used in the supplemented recovery of petroleum from subterranean formations. In general, enhancing the polyionic character of mobility control agents used in supplemented recovery of petroleum provides enhanced recovery. Achieving this enhancement of polyionic character through use of sulfonate groups provides a mobility control agent with good ability to sustain viscosity in the presence of brine and lime, usually present in the connate waters of petroleum-bearing formations. (7 claims)

  20. Role of Cellulose Nanocrystals on the Microstructure of Maleic Anhydride Plasma Polymer Thin Films.

    Science.gov (United States)

    Brioude, Michel M; Roucoules, Vincent; Haidara, Hamidou; Vonna, Laurent; Laborie, Marie-Pierre

    2015-07-01

    Recently, it was shown that the microstructure of a maleic anhydride plasma polymer (MAPP) could be tailored ab initio by adjusting the plasma process parameters. In this work, we aim to investigate the ability of cellulose nanocrystals (CNCs) to induce topographical structuration. Thus, a new approach was designed based on the deposition of MAPP on CNCs model surfaces. The nanocellulosic surfaces were produced by spin-coating the CNC suspension on a silicon wafer substrate and on a hydrophobic silicon wafer substrate patterned with circular hydrophilic microsized domains (diameter of 86.9 ± 4.9 μm), resulting in different degrees of CNC aggregation. By depositing the MAPP over these surfaces, it was possible to observe that the surface fraction of nanostructures increased from 20% to 35%. This observation suggests that CNCs can act as nucleation points resulting in more structures, although a critical density of the CNCs is required.

  1. Functionalization of poly(dimethylsiloxane) surfaces with maleic anhydride copolymer films.

    Science.gov (United States)

    Cordeiro, Ana L; Zschoche, Stefan; Janke, Andreas; Nitschke, Mirko; Werner, Carsten

    2009-02-01

    Combining advantageous bulk properties of polymeric materials with surface-selective chemical conversions is required in numerous advanced technologies. For that aim, we investigate strategies to graft maleic anhydride (MA) copolymer films onto poly(dimethylsiloxane) (PDMS) precoatings. Amino groups allowing the covalent attachment of the MA copolymer films to the PDMS (Sylgard 184) surface were introduced either by low-pressure ammonia plasma treatment, or by attachment of 3-aminopropyltriethoxysilane (APTES) onto air plasma-treated PDMS. The resultant coatings were extensively characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), contact angle measurements, and atomic force microscopy (AFM). The results show that the impact of the plasma treatment on the physical properties on the topmost surface of the PDMS is critically important for the characteristics of the layered coatings.

  2. Preparation and Characterization of Octenyl Succinic Anhydride Modified Taro Starch Nanoparticles.

    Science.gov (United States)

    Jiang, Suisui; Dai, Lei; Qin, Yang; Xiong, Liu; Sun, Qingjie

    2016-01-01

    The polar surface and hydrophilicity of starch nanoparticles (SNPs) result in their poor dispersibility in nonpolar solvent and poor compatibility with hydrophobic polymers, which limited the application in hydrophobic system. To improve their hydrophobicity, SNPs prepared through self-assembly of short chain amylose debranched from cooked taro starch, were modified by octenyl succinic anhydride (OSA). Size via dynamic light scattering of OSA-SNPs increased compared with SNPs. Fourier transform infrared spectroscopy data indicated the OSA-SNPs had a new absorption peak at 1727 cm-1, which was the characteristic peak of carbonyl, indicating the formation of the ester bond. The dispersibility of the modified SNPs in the mixture of water with nonpolar solvent increased with increasing of degree of substitution (DS). OSA-SNPs appear to be a potential agent to stabilize the oil-water systems.

  3. Synthesis and paste properties of octenyl succinic anhydride modified early Indica rice starch

    Institute of Scientific and Technical Information of China (English)

    SONG Xiao-yan; CHEN Qi-he; RUAN Hui; HE Guo-qing; XU Qiong

    2006-01-01

    Octenyl succinic anhydride (OSA) modified early Indica rice starch was prepared in aqueous slurry systems using response surface methodology. The paste properties of the OSA starch were also investigated. Results indicated that the suitable parameters for the preparation of OSA starch from early Indica rice starch were as follows: reaction period 4 h, reaction temperature 33.4 ℃, pH of reaction system 8.4, concentration of starch slurry 36.8% (in proportion to water, w/w), amount of OSA 3% (in proportion to starch, w/w). The degree of substitution was 0.0188 and the reaction efficiency was 81.0%. The results of paste properties showed that with increased OSA modification, the starch derivatives had higher paste clarity, decreased retrogradation and better freeze-thaw stability.

  4. Polycondensation of Tetrahydrofuran with Phthalic Anhydride Induced By a Proton Exchanged Montmorillonite Clay

    OpenAIRE

    Mohammed Belbachir; Mohammed Issam Ferrahi

    2003-01-01

    Abstract: “Maghnite†a montmorillonite sheet silicate clay, exchanged with protons to produce “H-Maghnite†is an efficient catalyst for polymerization of many vinylic and heterocyclic monomers (Belbachir, M. U.S. Patent. 066969.0101 –2001). The structure compositions of both “Maghnite†and “H-Maghnite†have been developed. This catalyst was used for the polycondensation of the tetrahydrofuran with phthalic anhydride. The polymerization was performed un...

  5. Ionic liquids as novel solvents for biosynthesis of octenyl succinic anhydride-modified waxy maize starch.

    Science.gov (United States)

    Li, Dandan; Zhang, Xiwen; Tian, Yaoqi

    2016-05-01

    Biosynthesis of octenyl succinic anhydride (OSA) starch was investigated using ionic liquids (ILs) as reaction media. Waxy maize starch was pretreated in 1-butyl-3-methylimidazolium chlorine and then esterified with OSA in 1-octyl-3-methylimidazolium nitrate by using Novozyme 435 as catalyst. The degree of substitution of OSA starch reached 0.0130 with 5 wt% starch concentration and 1 wt% lipase dosage based on ILs weight at 50 °C for 3h. The formation of OSA starch was confirmed by fourier transform infrared spectroscopy. Scanning electron microscopy and X-ray diffraction revealed that the morphology and crystal structure of starch were significantly destroyed. Thermogravimetric analysis showed that esterification decreased the thermal stability of starch. The successful lipase-catalyzed synthesis of OSA starch in ILs suggests that ILs are potential replacement of traditional organic solvents for starch ester biosynthesis.

  6. Physico-mechanical properties of silanized-montmorillonite reinforced chitosan-co-poly(maleic anhydride) composites

    Science.gov (United States)

    Saputra, O. A.; Fajrin, A.; Nauqinida, M.; Suryanti, V.; Pramono, E.

    2017-07-01

    To solve the problems of dependence on petroleum as starting material in the manufacturing of plastics in Indonesia, green plastic from biopolymer like chitosan to be one of promising options and alternative to replace the conventional plastics. However, to overcome the mechanical and physical properties of chitosan, the addition of reinforcement agent was introduced. In this study, silanized-montmorillonite (sMMt) has been prepared as a reinforcement agent in the chitosan-co-poly(maleic anhydride) (referred as Cs-MAH) matrix. Silanizing of montmorillonite is one of strategy to improve the interaction between montmorillonite and chitosan, consequently, the mechanical properties, tensile strength of composites contained 6 phr of sMMt improved 56.5% to chitosan. Moreover, the presence both MAH and sMMt on the comosites also reduced swelling degree and swelling area by 20.6% and 26.7%.

  7. Crystal structure of O-benzyl-l-tyrosine N-carb-oxy anhydride.

    Science.gov (United States)

    Inada, Aya; Kanazawa, Hitoshi

    2017-04-01

    In the title compound, C17H15NO4 (alternative name; O-benzyl-l-tyrosine N-carb-oxy anhydride), the oxazolidine ring is planer, with an r.m.s. deviation of 0.039 Å. The benz-yloxy and benzyl rings are almost coplanar, making a dihedral angle of 0.078 (10)°, and are inclined to the oxazolidine ring by 59.16 (11) and 58.42 (11)°, respectively. In the crystal, mol-ecules are linked by N-H⋯O and C-H⋯O hydrogen bonds, forming ribbons propagating along [010]. The ribbons are linked by C-H⋯π inter-actions, forming a three-dimensional supra-molecular structure. The oxazolidine rings of adjacent ribbons are arranged into a layer parallel to the ab plane. This arrangement is favourable for the polymerization of the compound in the solid state.

  8. Stereodynamic control of star-epoxy/anhydride crosslinking actuated by liquid-crystalline phase transitions.

    Science.gov (United States)

    Pin, Jean-Mathieu; Mija, Alice; Sbirrazzuoli, Nicolas

    2017-02-07

    The epoxy/anhydride copolymerization kinetics of an original star-epoxy monomer (TriaEP) was explored in dynamic heating mode using a series of isoconversional methods. Negative values of the apparent activation energy (Eα) related to an anti-Arrhenius behavior were observed. The transition from Arrhenius to anti-Arrhenius behavior and vice versa depending on the Eα of polymerization was correlated with the dynamics of mesophasic fall-in/fall-out events, physically induced transition (PIT) and chemically induced transition (CIT). This self-assembly phenomenon induces the generation of an anisotropic crosslinked architecture exhibiting both nematic discotic (ND) and nematic columnar (NC) organization. Particular emphasis was placed on evaluating the juxtaposition/contribution of the liquid-crystalline transitions to crosslinking, considering both the reaction dynamics and the macromolecular vision.

  9. Terpolymerization of 2-ethoxy ethylmethacrylate, styrene and maleic anhydride: determination of the reactivity ratios

    Indian Academy of Sciences (India)

    C S Sanmathi; S Prasannakumar; B S Sherigara

    2004-06-01

    Terpolymerization of 2-ethoxyethyl methacrylate (2-EOEMA), styrene (St) and maleic anhydride (Ma) initiated by benzoyl peroxide was carried out in acetone as common solvent for three monomers. The structure and composition of terpolymer were determined by FTIR spectroscopy by recording analytical absorption bands for St (3002 cm-1), Ma (1781 cm-1) and 2-EOEMA (1261 cm-1) units, respectively. The reactivity ratios for the monomers were calculated according to the general copolymerization equations following the Finnemann–Ross and Kelen–Tudos models. The results show that terpolymerization were carried out through primary ``complex" mechanism at near-binary copolymerization of [St...Ma] complex with 2-EOEMA. Structure of the resulting terpolymer illustrated by 1H-NMR and differential scanning calorimeter showed reduction in g value.

  10. Salivary contamination and post-cured resin/resin lute bond.

    Science.gov (United States)

    Stokes, A N; Pereira, B P

    1994-01-01

    A previous study has shown that sandblasting and silane priming a post-cured inlay resin gave a secure bond to dual-cure luting resin. To determine the influence of salivary contamination 4 additional groups of 15 post-cured resin discs were mounted in acrylic cylinders, their faces sandblasted with 50 microns alumina and silane primed. Surface treatments with saliva (sa), air/water spray (a/w), phosphoric acid gel (pa), and silane (si) followed in the order listed: A) control, no further treatment; B) sa, a/w; C) sa, a/w, si; D) sa, a/w, pa a/w; E) sa, a/w, pa, a/w, si. A 3.9 mm diameter column of dual-cure resin lute was then bonded to the dry stored in water surfaces. Specimens were stored in water for 2 weeks after which the dual-cure resin columns were sheared off the post-cured resin discs. Shear bond strengths were A) 19.2 +/- 3.7, B) 17.4 +/- 3.9, C) 16.7 +/- 3.1, D) 15.6 +/- 3.5, E) 15.4 +/- 2.3 MPa. One-way ANOVA and Duncan's Multiple Range Procedure showed groups D and E to be significantly lower than the uncontaminated control group A (p < 0.05). There were 2 adhesive failures in group B and all others were cohesive within the post-cured resin discs. This implies that air/water alone after salivary contamination is an unreliable cleansing method. The low shear bond values for Groups D and E may have been related to inadequate clearance of the phosphoric acid gel. It was concluded that salivary contamination adversely affected the quality of the bonds studied and decontamination using phosphoric acid gel resulted in significantly reduced shear bond strengths.

  11. Comparative study on compressive strength of Self cured SCC and Normally cured SCC

    Directory of Open Access Journals (Sweden)

    Ms. Akanksha A. Patil

    2014-11-01

    Full Text Available Curing is the process of maintaining proper moisture content particularly within 28 days to promote optimum cement hydration immediately after placement. Self-compacting concrete is made up of admixture i.e. superplasticizer. In recent years, self-compacting concrete (SCC has gained wide use for placement in congested reinforced concrete structures with difficult casting conditions. Also various curing methods are adopted in the construction industry especially for vertical structures, inaccessible areas s.a. high rise buildings, water scarce areas etc. In such structures conventional curing is not practically possible in most of the cases. But we need efficient curing which improves the strength and durability of concrete. In the present work, comparison of compressive strength of normally cured SCC and SCC cured with self curing material i.e. wax based, white pigmented, membrane forming concrete curing compound has been done. This study is investigating that weather the use of self curing compound is economical or not in remote areas of water without compromising with the compressive strength of concrete.

  12. Cure fraction estimation from the mixture cure models for grouped survival data.

    Science.gov (United States)

    Yu, Binbing; Tiwari, Ram C; Cronin, Kathleen A; Feuer, Eric J

    2004-06-15

    Mixture cure models are usually used to model failure time data with long-term survivors. These models have been applied to grouped survival data. The models provide simultaneous estimates of the proportion of the patients cured from disease and the distribution of the survival times for uncured patients (latency distribution). However, a crucial issue with mixture cure models is the identifiability of the cure fraction and parameters of kernel distribution. Cure fraction estimates can be quite sensitive to the choice of latency distributions and length of follow-up time. In this paper, sensitivity of parameter estimates under semi-parametric model and several most commonly used parametric models, namely lognormal, loglogistic, Weibull and generalized Gamma distributions, is explored. The cure fraction estimates from the model with generalized Gamma distribution is found to be quite robust. A simulation study was carried out to examine the effect of follow-up time and latency distribution specification on cure fraction estimation. The cure models with generalized Gamma latency distribution are applied to the population-based survival data for several cancer sites from the Surveillance, Epidemiology and End Results (SEER) Program. Several cautions on the general use of cure model are advised.

  13. Controlled delivery of paclitaxel from stent coatings using novel styrene maleic anhydride copolymer formulations.

    Science.gov (United States)

    Richard, Robert; Schwarz, Marlene; Chan, Ken; Teigen, Nikolai; Boden, Mark

    2009-08-01

    The controlled release of paclitaxel (PTx) from stent coatings comprising an elastomeric polymer blended with a styrene maleic anhydride (SMA) copolymer is described. The coated stents were characterized for morphology by scanning electron microscopy (SEM) and atomic force microscopy (AFM), and for drug release using high-performance liquid chromatography (HPLC). Differential scanning calorimetry (DSC) was used to measure the extent of interaction between the PTx and polymers in the formulation. Coronary stents were coated with blends of poly(b-styrene-b-isobutylene-b-styrene) (SIBS) and SMA containing 7% or 14% maleic anhydride (MA) by weight. SEM examination of the stents showed that the coating did not crack or delaminate either before or after stent expansion. Examination of the coating surface via AFM after elution of the drug indicated that PTx resides primarily in the SMA phase and provided information about the mechanism of PTx release. The addition of SMA altered the release profile of PTx from the base elastomer coatings. In addition, the presence of the SMA enabled tunable release of PTx from the elastomeric stent coatings, while preserving mechanical properties. Thermal analysis reveled no shift in the glass transition temperatures for any of the polymers at all drug loadings studied, indicating that the PTx is not miscible with any component of the polymer blend. An in vivo evaluation indicated that biocompatibility and vascular response results for SMA/SIBS-coated stents (without PTx) are similar to results for SIBS-only-coated and bare stainless steel control stents when implanted in the non-injured coronary arteries of common swine for 30 and 90 days.

  14. 河南省烤烟常规化学成分与烟叶有机酸含量关系分析%Relationship between Organic Acid Contents and Conventional Chemical Compositions in Flue-cured Tobacco Leaves in Henan

    Institute of Scientific and Technical Information of China (English)

    王超; 胡战军; 孙曙光; 王鹏; 朱海滨; 叶协锋

    2012-01-01

    选取了河南省不同产区的353个烤烟样品为供试材料,测定了18种有机酸和8种常规化学成分,并分析了其相关关系.结果表明:不同种类有机酸的含量差异较大,以苹果酸的含量最高,柠檬酸次之,十五酸含量最小;富马酸的变异系数最高,软脂酸的变异系数最小;氯的变异系数最大,淀粉次之,总氮最小,为14%.烟碱和钾含量偏低,总糖和还原糖含量偏高;总氮、淀粉、氯和石油醚提取物含量都存在过高或过低的现象.常规化学成分与有机酸之间存在较强的相关性,其中,K+属于与有机酸关系非常密切的指标;总氮、烟碱、还原糖、淀粉、总糖和石油醚提取物属于关系密切的指标;氯属于关系不密切的指标.%Eighteen different organic acid contents and 8 different conventional chemical compositions were analyzed in 353 flue -cured tobacco samples from Henan province. Correlations were also studied between them. Results showed that the great difference existed among different kinds of organic acid. Malic acid had the highest content and citric acid took the second place, and pentadecano-ic acid had the lowest content. Fumaric acid had the biggest coefficient of variation and palmitic acid took the minimum among the organic acids. Chlorine had the biggest coefficient of variation and starch took the second place. The content of total nitrogen, which was only 14 percent, took the minimum among the conventional chemical compositions. The contents of nicotine and potassium were slightly lower than the standard but the contents of total sugar and reducing sugar were higher than the standard. It happened that the contents of total nitrogen, starch, chlorine, and petroleum ether extraction were too high or low. The conventional chemical compositions contents had the close relationship with organic acids. Potassium index had very close relationship with organic acids. Total nitrogen, nicotine, reducing sugar, starch

  15. Effect of curing conditions on the dimensional and thermal stability of calcium phosphate cement for elevated temperature applications

    Energy Technology Data Exchange (ETDEWEB)

    Blom, Johan [Vrije Universiteit Brussel, Department of Mechanics of Materials and Constructions, Pleinlaan 2, Brussels 1050 (Belgium); Rahier, Hubert [Vrije Universiteit Brussel, Research Group of Physical Chemistry and Polymer Sciences, Pleinlaan 2, Brussels 1050 (Belgium); Wastiels, Jan, E-mail: Jan.Wastiels@vub.ac.be [Vrije Universiteit Brussel, Department of Mechanics of Materials and Constructions, Pleinlaan 2, Brussels 1050 (Belgium)

    2014-12-15

    Calcium phosphate cements (CPCs) are attractive materials for elevated temperature applications, like moulds to process thermoplastics up to 300 °C. The CPC resulting from the reaction of wollastonite with phosphoric acid cured at room temperature however contains hydrated phases like brushite, and is thus not stable when exposed to temperatures above 200 °C. A non-contact method based on digital image correlation demonstrated that isothermal curing at 60 °C reduces the thermal shrinkage up to 300 °C by 25%. This curing method results in the direct formation of the more stable monetite in a shorter curing time. The correlated results of TGA, pH of the filtration water, and DSC analysis on partially cured material indicate this. XRD diffractograms and SEM images in combination with EDX show the evolution of the transformation of wollastonite into monetite, and the structure and morphology of the formed material.

  16. Investigation of the formation of benzoyl peroxide, benzoic anhydride, and other potential aerosol products from gas-phase reactions of benzoylperoxy radicals

    Science.gov (United States)

    Strollo, Christen M.; Ziemann, Paul J.

    2016-04-01

    The secondary organic aerosol (SOA) products of the reaction of benzaldehyde with Cl atoms and with OH radicals in air in the absence of NOx were investigated in an environmental chamber in order to better understand the possible role of organic peroxy radical self-reactions in SOA formation. SOA products and authentic standards were analyzed using mass spectrometry and liquid chromatography, and results show that the yields of benzoyl peroxide (C6H5C(O)OO(O)CC6H5) and benzoic anhydride (C6H5C(O)O(O)CC6H5), two potential products from the gas-phase self-reaction of benzoylperoxy radicals (C6H5C(O)OO·), were less than 0.1%. This is in contrast to results of recent studies that have shown that the gas-phase self-reactions of β-nitrooxyperoxy radicals formed from reactions of isoprene with NO3 radicals form dialkyl peroxides that contribute significantly to gas-phase and SOA products. Such reactions have also been proposed to explain the gas-phase formation of extremely low volatility dimers from autooxidation of terpenes. The results obtained here indicate that, at least for benzoylperoxy radicals, the self-reactions form only benzoyloxy radicals. Analyses of SOA composition and volatility were inconclusive, but it appears that the SOA may consist primarily of oligomers formed through heterogeneous/multiphase reactions possibly involving some combination of phenol, benzaldehyde, benzoic acid, and peroxybenzoic acid.

  17. Repair bond strength of dual-cured resin composite core buildup materials.

    Science.gov (United States)

    El-Deeb, Heba A; Ghalab, Radwa M; Elsayed Akah, Mai M; Mobarak, Enas H

    2016-03-01

    The reparability of dual-cured resin composite core buildup materials using a light-cured one following one week or three months storage, prior to repair was evaluated. Two different dual-cured resin composites; Cosmecore™ DC automix and Clearfil™ DC automix core buildup materials and a light-cured nanofilled resin composite; Filtek™ Z350 XT were used. Substrate specimens were prepared (n = 12/each substrate material) and stored in artificial saliva at 37 °C either for one week or three months. Afterward, all specimens were ground flat, etched using Scotchbond™ phosphoric acid etchant and received Single Bond Universal adhesive system according to the manufacturers' instructions. The light-cured nanofilled resin composite (Filtek™ Z350 XT) was used as a repair material buildup. To determine the cohesive strength of each solid substrate material, additional specimens from each core material (n = 12) were prepared and stored for the same periods. Five sticks (0.8 ± 0.01 mm(2)) were obtained from each specimen (30 sticks/group) for microtensile bond strength (μTBS) testing. Modes of failure were also determined. Two-way ANOVA revealed a significant effect for the core materials but not for the storage periods or their interaction. After one week, dual-cured resin composite core buildup materials (Cosmecore™ DC and Clearfil™ DC) achieved significantly higher repair μTBS than the light-cured nanofilled resin composite (Filtek™ Z350 XT). However, Clearfil™ DC revealed the highest value, then Cosmecore™ DC and Filtek™ Z350 XT, following storage for 3-month. Repair strength values recovered 64-86% of the cohesive strengths of solid substrate materials. The predominant mode of failure was the mixed type. Dual-cured resin composite core buildup materials revealed acceptable repair bond strength values even after 3-month storage.

  18. HEAT-RESISTANT COMPOSITES CURED BY ELECTRON BEAM

    Institute of Scientific and Technical Information of China (English)

    Jian-wen Bao; Yang Li; Xiang-bao Chen; Feng-mei Li

    2001-01-01

    Electron beam (EB) curing of composites has many advantages. Heat-resistant EB-curing composites could substitute polyimide composites used in aeronautical engines. In this paper, the effects of catalyst and dose on the cured resin were investigated. The heat-resistance of the resin cured by EB was evaluated by dynamic mechanical analysis (DMA). The experimental results show that the mechanical properties of the composites cured by EB could meet the specifications of aeronautical engines at 250°C.

  19. FATTY ACID PROFILE OF TWO CURED MEAT PRODUCTS: DRY-CURED HAM AND CECINA.

    Science.gov (United States)

    Fernández, Domingo; Menéndez, Rosa Ana; Sanz, José Javier; García-Fernández, María Del Camino

    2015-07-01

    Introducción y objetivos: el objetivo de este estudio fue evaluar el perfil de ácidos grasos de dos derivados cárnicos curados-madurados, relativamente similares en cuanto a composición y proceso de elaboración: el jamón (JA) y la cecina (CE), haciendo una revisión de los resultados obtenidos desde el punto de vista de los efectos individuales que los principales ácidos grasos de consumo dietético tienen sobre la salud humana. Materiales y métodos: para ello se tomaron 10 muestras de 100 g de jamón y de cecina en distintos establecimientos de la provincia de León, España. Se extrajo la grasa y se metiló para posteriormente realizar el análisis de los ácidos grasos resultantes mediante cromatografía de gases masas. Resultados y discusión: los perfiles lipídicos obtenidos para el JA y la CE presentaron diferencias significativas (p fracciones lipídicas mayoritarias, ácidos grasos saturados (SFA), ácidos grasos monoinsaturados (MUFA) y ácidos grasos poliinsaturados (PUFA), respectivamente: 42,86%, 43,27% y 13,87 para el JA y 46,87%, 46,96% y 6,20% para la CE. Los porcentajes de SFA y MUFA fueron mayores en la CE en detrimento de los PUFA, en concreto de la serie n-6, para la que se obtuvieron valores de 11,06% en JA y de 3,91% en CE. En ambos productos el ácido graso detectado en mayor cantidad fue un ácido graso monoinsaturado, el ácido oleico, con porcentajes del 37,28% en JA y 38,48% en CE. Otros dos ácidos grasos presentes en porcentajes elevados respecto al total de la grasa fueron dos ácidos grasos saturados: el ácido palmítico, 20,63% en JA y 22,95% en CE, y el ácido esteárico, 18,65% en JA y 17,14% en CE.

  20. Acetic acid assisted cobalt methanesulfonate catalysed chemoselective diacetylation of aldehydes

    Institute of Scientific and Technical Information of China (English)

    Min Wang; Zhi Guo Song; Hong Gong; Heng Jiang

    2008-01-01

    Cobalt methanesulfonate in combination with acetic acid catalysed the chemoselective diacetylation of aldehyde with acetic anhydride at room temperature under solvent free conditions. After reaction, cobalt methanesulfonate can be easily recovered and mused many times. The reaction was mild and efficient with good to high yields.

  1. Assessment of Curing Efficiency and Effect of Moist Curing on Performance of Fly Ash Concrete

    Institute of Scientific and Technical Information of China (English)

    LI Meili; QIAN Jueshi; WANG Lixia; XU Shanshan; JIA Xingwen; FAN Yunyan

    2011-01-01

    This study was conducted to evaluate the sensitivity of compressive strength,water permeability and electrical resistance of near-surface layer concrete with different fly ash contents to curing conditions. It is shown that the sensitivity to curing condition and fly ash content descends in the following order: difference between internal and surface resistivity (ρ)at 28 days, water permeability and compressive strength; both of longer duration of moist curing and use of fly ash in concrete enhanced the water penetration resistance. It is indicated that the resistivity difference p at 28 days can reflect accurately the curing history of fly ash concrete regardless of mix proportions; and use of fly ash in concrete requires longer moist curing duration.

  2. The Fracture of Thermosetting Resins after Exposure to Water.

    Science.gov (United States)

    1980-09-01

    1.0 water. 23 0C uptakeamine- cured 0.6 /* anhydride cured 0.2 bisphenol cured epoxy /glass laminate (VF =0.55) Source: H W Gitschner and G Menges...for this in the highly cross-linked epoxy systems . The fracture surfaces of polyesters with different flexibiliser additions, and consequently...procedure are (a) replacement of phthalic anhydride by isophthalic acid and (b) use of different glycols. Different proportions of unsaturated (maleic) to

  3. A study of access and compliance of iron and folic acid tablets for prevention and cure of anaemia among adolescent age group females in Ahmedabad district of India surveyed under multi indicator cluster survey 2011

    Directory of Open Access Journals (Sweden)

    Rajshree J. Bhatt

    2013-09-01

    Full Text Available Objective The knowledge and utilization of Iron and folic acid tablets supplementation of the adolescent girls in Ahmedabad district. Setting The study was conducted over a time span of 20 weeks period, from April 2011 till Aug 2011 in selected areas of Ahmedabad district, which has an approximate population of 15,94,010 as per census 2001. Study design Cross sectional observational study. Participants All the adolescent girls in the population surveyed by MICS 2011. Methodology 30 clusters sampling method based on PPS (Probability Proportional to Size for cluster selection. Results 431 adolescent girls were included in the survey of total population of 6076. The result showed that 51.5% (222 girls went to school and only 36.2% (156 received IFA tablets. Out of them 66% (103 girls stopped taking these tablets due to one or other side effects of the tablets. Nearly 47.4% (74 girls were unaware of the positive effects of these tablets on their health.

  4. Effects of feeding high protein or conventional canola meal on dry cured and conventionally cured bacon.

    Science.gov (United States)

    Little, K L; Bohrer, B M; Stein, H H; Boler, D D

    2015-05-01

    Objectives were to compare belly, bacon processing, bacon slice, and sensory characteristics from pigs fed high protein canola meal (CM-HP) or conventional canola meal (CM-CV). Soybean meal was replaced with 0 (control), 33, 66, or 100% of both types of canola meal. Left side bellies from 70 carcasses were randomly assigned to conventional or dry cure treatment and matching right side bellies were assigned the opposite treatment. Secondary objectives were to test the existence of bilateral symmetry on fresh belly characteristics and fatty acid profiles of right and left side bellies originating from the same carcass. Bellies from pigs fed CM-HP were slightly lighter and thinner than bellies from pigs fed CM-CV, yet bacon processing, bacon slice, and sensory characteristics were unaffected by dietary treatment and did not differ from the control. Furthermore, testing the existence of bilateral symmetry on fresh belly characteristics revealed that bellies originating from the right side of the carcasses were slightly (P≤0.05) wider, thicker, heavier and firmer than bellies from the left side of the carcass.

  5. Cure kinetics and mechanical interfacial characteristics of zeolite/DGEBA composites

    Energy Technology Data Exchange (ETDEWEB)

    Park, Soo Jin; Kim, Young Mi [Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of); Shin, Jae Sup [Chungbuk National Univ., Cheongju (Korea, Republic of)

    2003-10-15

    In this work, the zeolite/diglycidylether of bisphenol A(DGEBA) systems were investigated in terms of the cure kinetics and mechanical interfacial properties of the composites. The 4, 4-Diamino Diphenyl Methane(DDM) was used as a curing agent for epoxy. Two types of zeolite(PZ) were prepared with 15 and 35 wt% KOH treatments(15-BZ and 35-BZ, respectively) for 24 h, and their surface characteristics were studied by X-ray Photoelectron Spectroscopy (XPS) and X-Ray Diffraction (XRD). Cure kinetics of the composites were examined in the context of Differential Scanning Calorimetry(DSC), and mechanical interfacial properties were investigated in critical stress intensity factor(K{sub IC}) and critical strain energy release rate(G{sub IC}). In the results of XPS and XRD, sodium ion(Na) of zeolite was exchanged for potassium ion(K), resulting from the treatment of KOH. Also, Si{sub 2p}/A1{sub 2p} composition ratios of the treated zeolite were increased, which could be attributed to the weakening of A1-O bond in framework. Cure activation energy(E{sub a}) of 15-BZ composites was decreased, whereas K{sub IC} and G{sub IC} were increased, compared with those of the pure zeolite/DGEBA composites. It was probably accounted that the acidity of zeolite was increased by surface treatments and the cure reaction between zeolite and epoxy was influenced on the increased acidity of zeolite.

  6. A Quick and Simple Conversion of Carboxylic Acids into Their Anilides of Heating with Phenyl Isothiocyanate.

    Science.gov (United States)

    Ram, Ram N.; And Others

    1983-01-01

    Converting carboxylic acids into their anilides, which usually involves preparation of acid chloride or mixed anhydride followed by treatment with aniline, is tedious and/or time-consuming. A quick and easier procedure, using phenyl isothiocyanate, is provided. Reactions involved and a summary table of results are included. (JN)

  7. Modular access to vicinally functionalized allylic (thio)morpholinonates and piperidinonates by substrate-controlled annulation of 1,3-azadienes with hexacyclic anhydrides.

    Science.gov (United States)

    Braunstein, Hannah; Langevin, Spencer; Khim, Monique; Adamson, Jonathan; Hovenkotter, Katie; Kotlarz, Lindsey; Mansker, Brandon; Beng, Timothy K

    2016-09-21

    A modular substrate-controlled hexannulation of inherently promiscuous 1,3-azadienes with hexacyclic anhydrides, which affords versatile vicinally functionalized allylic lactams, in high yields, regio- and stereoselectivities is described.

  8. Preparation and properties of acrylic acid grafted starch based UV-curing degradable superabsorbent polymer%丙烯酸接枝淀粉基可降解紫外光固化高吸水性树脂的制备与性能

    Institute of Scientific and Technical Information of China (English)

    贺倩; 郭文迅

    2011-01-01

    A degradable superabsorbent resin was prepared by acrylic acid grafted starch with unsaturated polyester-urea amide as a cross-linking agent,a membrane was prepared by the resin,in the condition of UV-curing without adding any photo-initiator.The influence of absorbency rate of the resin,the dosage of cross-linking agent and the UV-curing time on the absorbency were discussed.The results showed that the product had good absorbency ability to different solutions,and the absorbency rate was the fast.Water absorbency in distilled water,tap water,0.9% NaCl,0.9% KC1 solution were 905,350,100,120 g/g,respectively.Moreover,water absorbency in distilled water can reach 200 g/g in 10 min.The degradation originate from surface and evolve towards inside gradually.%以丙烯酸接枝淀粉为基体,不饱和聚酯酰胺脲树脂为交联剂制备出一种可降解高吸水性树脂,该树脂小加任何光引发剂即可紫外光固化成膜.研究了树脂的吸水速率及交联剂的加入量、光同化时间对产品吸水率的影响.结果表明,该高吸水性树脂对不同溶液均具有较好的吸收能力,吸水速度较快,在蒸馏水、自来水、0.9%NaCl溶液、0.9%KCl溶液中的吸水率分别为905,350,100,120g/g;10 min内对蒸馏水的吸收倍率达200 g.该高吸水性树脂的降解从表面开始,逐渐向里面降解.

  9. Curing mechanism of flexible aqueous polymeric coatings.

    Science.gov (United States)

    Irfan, Muhammad; Ahmed, Abid Riaz; Dashevskiy, Andriy; Kolter, Karl; Bodmeier, Roland

    2017-02-25

    The objective of this study was to explain curing phenomena for pellets coated with a flexible polymeric coating based on poly(vinyl acetate) (Kollicoat(®) SR 30D) with regard to the effect of starter cores, thickness of drug layer, adhesion of coating to drug-layered-cores as well as coating properties. In addition, appropriate approaches to eliminate the curing effect were identified. Sugar or MCC cores were layered with the model drugs carbamazepine, theophylline, propranolol HCl, tramadol HCl and metoprolol HCl using HPMC (5 or 25% w/w, based on drug) as a binder. Drug-layered pellets were coated with Kollicoat(®) SR 30D in a fluidized bed coater using TEC (10% w/w) as plasticizer and talc (35-100% w/w) as anti-tacking agent. Drug release, pellet properties (morphology, water uptake-weight loss and osmolality) and adhesion of the coating to the drug layer were investigated as a function of curing at 60 °C or 60 °C/75% RH for 24 h. The film formation of the aqueous dispersion of Kollicoat(®) SR 30D was complete, and therefore, a strong curing effect (decrease in drug release) at elevated temperature and humidity (60 °C/75% RH) could not be explained by the well-known hydroplasticization and the further gradual coalescence of the colloidal polymer particles. According to the provided mechanistic explanation, the observed curing effect was associated with 1) high flexibility of coating, 2) adhesion between coating and drug layer, 3) water retaining properties of the drug layer, and 4) osmotically active cores. Unwanted curing effects could be minimized/eliminated by the addition of talc or/and pore-forming water soluble polymers in the coating, increasing binder amount or applying an intermediate coating, by increasing the thickness of drug layer or using non-osmotic cores. A new insight into curing phenomena mainly associated with the adhesion between drug layer and coating was provided. Appropriate approaches to avoid unwanted curing effect were identified.

  10. Prevent and cure disuse bone loss

    Science.gov (United States)

    Jee, Webster S. S.

    1994-01-01

    Anabolic agents like parathyroid hormone and postagladin E-like substances were studied in dogs and rats to determine their effectiveness in the prevention and cure of bone loss due to immobilization. It was determined that postagladin E2 administration prevented immobilization while at the same time it added extra bone in a dose responsive manner. Although bone mass returns, poor trabecular architecture remains after normal ambulation recovery from immobilization. Disuse related bone loss and poor trabecular architecture were cured by post-immobilization postagladin E2 treatment.

  11. Changes in intramuscular lipids during ripening of Iberian dry-cured ham.

    Science.gov (United States)

    Martín, L; Córdoba, J J; Ventanas, J; Antequera, T

    1999-02-01

    Thirty-one thighs were obtained from Iberian pigs fattened with acorns and were processed during 22 months in the traditional dry-curing process. Lipolysis affecting intramuscular fat during the processing of Iberian dry-cured ham has been analyzed by studying the changes of glycerides, phospholipids and free fatty acids in lipids from Biceps femoris muscle. Little change affected the fatty acid composition of glycerides during processing. A double-phased increase in the acidity values and a decrease in the quantity of fatty acids of phospholipids during the processing were observed. There seems to be a relationship between the extension of the lipolysis taking place during the maturing and the processing conditions and raw material used.

  12. Grafting amino drugs to poly(styrene-alt-maleic anhydride) as a potential method for drug release

    Energy Technology Data Exchange (ETDEWEB)

    Khazaei, Ardeshir; Saednia, Shahnaz; Saien, Javad; Abbasi, Fatemeh, E-mail: Khazaei_1326@yahoo.com, E-mail: ssaednia@gmail.com [Faculty of Chemistry, Bu-Ali Sina University, Hamedan (Iran, Islamic Republic of); Kazem-Rostami, Masoud [Young Researchers Club and Elite, Takestan Branch, Islamic Azad University, Takestan (Iran, Islamic Republic of); Sadeghpour, Mahdieh [Department of Chemistry, Takestan Branch, Islamic Azad University, Takestan (Iran, Islamic Republic of); Borazjani, Maryam Kiani [Faculty of Science, Department of Chemistry, Bushehr Payame Noor University (PNU), Bushehr (Iran, Islamic Republic of)

    2013-07-15

    Drug delivery systems based on polymer-drug conjugates give an improved treatment with lower toxicity or side effects and be used for the treatment of different diseases. Conjugates of biodegradable poly(styrene-alt-maleic anhydride) (PSMA), with a therapeutic agents such as amantadine hydrochloride, amlodipine, gabapentin, zonisamide and mesalamine, were afforded by the formation of the amide bonds of the amino drugs that reacted with the PSMA anhydride groups. The amounts of covalently conjugated drugs were determined by a {sup 1}H NMR spectroscopic method, and the in vitro release rate in buffer solution (pH 1.3) was studied at body temperature 37 Degree-Sign C. In kinetic studies, different dissolution models were examined to obtain drug release data and the collected data were well-fitted to the Korsmeyer-Peppas equation, revealing a dominant Fickian diffusion mechanism for drug release under the in vitro conditions. (author)

  13. Facile and Efficient Acetylation of Primary Alcohols and Phenols with Acetic Anhydride Catalyzed by Dried Sodium Bicarbonate

    Directory of Open Access Journals (Sweden)

    Fulgentius Nelson Lugemwa

    2013-12-01

    Full Text Available A variety of primary alcohols and phenols were reacted with acetic anhydride at room temperature in the presence of sodium bicarbonate to produce corresponding esters in good to excellent yields. The acetylation of 4-nitrobenzyl alcohol was also carried out using other bicarbonates and carbonates. The reaction in the presence of cesium bicarbonate and lithium carbonate gave 4-nitrobenzyl acetate in excellent yield, while in the presence of Na2CO3, K2CO3, Cs2CO3, or KHCO3 the yield was in the range of 80%–95%. Calcium carbonate and cobaltous carbonate did not promote the acetylation of 4-ntirobenzyl alcohol using acetic anhydride. The acetylation of 4-nitrobenzyl alcohol was carried out using ethyl acetate, THF, toluene, diethyl ether, dichloromethane and acetonitrile, and gave good yields ranging from 75%–99%. Toluene was the best solvent for the reaction, while diethyl ether was the poorest.

  14. Luminescence spectroscopy applied to a study of the curing process of diglycidyl-ether of bisphenol-A (DGEBA)

    OpenAIRE

    Rita de Cássia Mendonça Sales; Deborah Dibbern Brunelli

    2005-01-01

    This work involved the application of luminescence spectroscopy under steady-state conditions to study the curing process of the epoxy resin diglycidyl-ether of bisphenol-A (DGEBA) using the curing agents 4,4'-diaminodiphenylmethane (DDM) and 4,4'-diaminodiphenylsulfone (DDS). Two fluorescence methods were employed: the intrinsic method related to the polymeric matrix and the extrinsic method, using the molecular probe 9-anthroic acid (9-AA). Stoichiometric mixtures, with and without 9-AA, we...

  15. Buffering Capacity of Fast-Growing Species and Curing Time of UF Resin Modified With Zinc Borate and Monoammonium Phosphate

    Directory of Open Access Journals (Sweden)

    Izran Kamal

    2010-01-01

    Full Text Available Problem statement: Occupying a suitable hot pressing time for particleboard fabrication seems very tricky for manufacturers of the wood-based panel. Longer or shorter pressing times can affect physical and mechanical properties of the produced particleboards and that is why extra care should be given on this matter. Longer pressing time can cause resin in a particleboard to over-cure whereas shorter pressing time can cause insufficient curing of the resin. Determination of hot pressing time is influenced by the type of filler and chemical used. The acidity or alkalinity of a filler and chemical can lengthen or shorten the time taken by the resin to cure. These parameters are usually assessed using buffering capacity test and curing time test. In this study, the two analyses were occupied to assess acidity or alkalinity of kenaf, Shorea macrophylla and Acacia mangium as well as the effect of fire retardants (zinc borate and monoammonium phosphate to the curing rate of urea formaldehyde resin. Determine acidity or alkalinity of the wood particles through buffering capacity test. The effect of the fire retardants to the curing of Urea Formaldehyde (UF resin was also studied. Approach: For buffering capacity test, the wood particles were extracted. Then, the extracts were separated into two parts. One part was tested with sodium hydroxide (NaOH and another part was tested with sulphuric acid (H2SO4. Sodium hydroxide was added into the extracts until they reached pH 11. The other part was added with sulphuric acid until they reached pH 3. The pH value was recorded each time 5 mL chemicals added. The acidity of the plants was observed by looking at the volume of sulphuric acid needed to reduce their pH to 3, whereas alkalinity was evaluated by looking at the volume of sodium hydroxide used to increase their pH to 11. Curing times of UF resin added or not added with fire retardants were calculated in second (sec. Results: Buffering capacity study

  16. Synthesis and characterization of biodegradable polymer: Poly (ethene maleic acid ester-co-D,L-lactide acid)

    Institute of Scientific and Technical Information of China (English)

    Mei Na Huang; Yan Feng Luo; Jia Chen; Yong Gang Li; Chun Hua Fu; Yuan Liang Wang

    2007-01-01

    A novel biodegradable polymer-poly (ethene maleic acid ester-co-D,L-lactide acid) was synthesized by copolymerizing lactide and prepolymer, which was prepared by the condensation of maleic anhydride and glycol, using p-toluene sulphonic acid as a catalyst, attempting to improve the hydrophilicity, increase flexibility and modulate the degradation rate. FTIR, 1H NMR, MALLS and DSC were employed to characterize these polymers.

  17. Curing kinetics of visible light curing dental resin composites investigated by dielectric analysis (DEA).

    Science.gov (United States)

    Steinhaus, Johannes; Hausnerova, Berenika; Haenel, Thomas; Großgarten, Mandy; Möginger, Bernhard

    2014-03-01

    During the curing process of light curing dental composites the mobility of molecules and molecule segments is reduced leading to a significant increase of the viscosity as well as the ion viscosity. Thus, the kinetics of the curing behavior of 6 different composites was derived from dielectric analysis (DEA) using especially redesigned flat sensors with interdigit comb electrodes allowing for irradiation at the top side and measuring the ion viscosity at the bottom side. As the ion viscosities of dental composites change 1-3 orders of magnitude during the curing process, DEA provides a sensitive approach to evaluate their curing behavior, especially in the phase of undisturbed chain growth. In order to determine quantitative kinetic parameters a kinetic model is presented and examined for the evaluation of the ion viscosity curves. From the obtained results it is seen that DEA might be employed in the investigation of the primary curing process, the quality assurance of ingredients as well as the control of processing stability of the light curing dental composites. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  18. Strength of Geopolymer Cement Curing at Ambient Temperature by Non-Oven Curing Approaches: An Overview

    Science.gov (United States)

    Wattanachai, Pitiwat; Suwan, Teewara

    2017-06-01

    At the present day, a concept of environmentally friendly construction materials has been intensively studying to reduce the amount of releasing greenhouse gases. Geopolymer is one of the cementitious binders which can be produced by utilising pozzolanic wastes (e.g. fly ash or furnace slag) and also receiving much more attention as a low-CO2 emission material. However, to achieve excellent mechanical properties, heat curing process is needed to apply to geopolymer cement in a range of temperature around 40 to 90°C. To consume less oven-curing energy and be more convenience in practical work, the study on geopolymer curing at ambient temperature (around 20 to 25°C) is therefore widely investigated. In this paper, a core review of factors and approaches for non-oven curing geopolymer has been summarised. The performance, in term of strength, of each non-oven curing method, is also presented and analysed. The main aim of this review paper is to gather the latest study of ambient temperature curing geopolymer and to enlarge a feasibility of non-oven curing geopolymer development. Also, to extend the directions of research work, some approaches or techniques can be combined or applied to the specific properties for in-field applications and embankment stabilization by using soil-cement column.

  19. Ficusmicrochlorin A-C, two new methoxy lactone chlorins and an anhydride chlorin from the leaves of Ficus microcarpa.

    Science.gov (United States)

    Lin, Huan-You; Chiu, Hsi-Lin; Lu, Te-Ling; Tzeng, Chih-Ying; Lee, Tzong-Huei; Lee, Ching-Kuo; Shao, Yi-Yuan; Chen, Chiy-Rong; Chang, Chi-I; Kuo, Yueh-Hsiung

    2011-01-01

    Two new methoxy lactone chlorins ficusmicrochlorin A (1) and ficusmicrochlorin B (2), and one new anhydride chlorin ficusmicrochlorin C (3), along with eight known pheophytins were isolated from the leaves of Ficus microcarpa. Their structures were determined by the extensive 1D- and 2D-NMR techniques. New pheophytin compound was rarely obtained from natural sources. In the past ten years, only three new natural pheophytins were characterized.

  20. Relationship between global indices of reactivity, electrodonating and electroaccepting powers, and the hammet constant in isatoic anhydride derivatives

    Indian Academy of Sciences (India)

    J S Durand-Niconoff; L Cruz-Kuri; M H Matus; J Correa-Basurto; J S Cruz-Sánchez; F R Ramos-Morales

    2011-09-01

    The possible correlation between Hammett’s constant (p), a characteristic parameter of functional groups with electrodonating or electroaccepting properties, and two indices of global reactivity were calculated in the gas phase. Parameters associated to a set of 22 structural variants of isatoic anhydride (2-3, 1-benzoxazin-2,4(1)-dione, ISA), replaced with diverse functional groups, were explored applying linear and quadratic statistical models for numerical analysis of the results.

  1. The Reaction of Crotonic Anhydride with Scots and Corsican Pine: Investigation of Kinetic Profiles and Determination of Activation Energies

    OpenAIRE

    Özmen, Nilgül; ÇETİN, Nihat Sami

    2014-01-01

    The kinetics of the reaction of crotonic anhydride with Scots pine (Pinus sylvestris) and Corsican pine (Pinus nigra) using pyridine as catalyst/solvent was investigated and activation energies for the initial reaction determined. Activation energies were calculated from the Arrhenius equation using rate data obtained from time-course experiments repeated at several temperatures. In one method, reaction constants (k) were determined experimentally, while in the other method initial rates were...

  2. Comparative study of the use of non-ionizing and ionizing radiation in the cure of epoxy resin: microwave versus electron electron

    Energy Technology Data Exchange (ETDEWEB)

    Kersting, Daniel, E-mail: daniel.kersting@usp.br [Centro Tecnologico da Marinha em Sao Paulo (CTMSP/USP), Sao Paulo, SP (Brazil); Wiebeck, Helio, E-mail: hwiebeck@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Escola Politecnica. Dept. de Engenharia Metalurgica; Marinucci, Gerson; Silva, Leonardo G.A. e, E-mail: marinuci@ipen.br, E-mail: gasilva@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    Several processes for curing epoxy resins were developed over the years. Two methods are discussed in this paper, in order to present the main advantages and disadvantages of using microwave radiation (non-ionizing radiation) and electron beam radiation (ionizing radiation). The microwave radiation is a non-ionizing radiation, with great power of penetration and transfer of heat in microwave absorbing materials, or materials with microwave absorbing fillers. The frequency usually used in research and development is 2.45 GHz, the same available in commercial equipment. The microwave effect provides increase on the collision velocity between the reactant which, combined with energy absorbed by the reaction system, accelerates the curing reaction. None modifications in the epoxy system are required to use microwave heating for the curing process.On the other hand, the electron beam is a form of ionizing radiation in which the high energy electrons have the ability to interact with the irradiated material and produce ions, free radicals, and molecules in excited state, which can be used to initiate and propagate a polymerization. Specific initiators are necessary for an effective cure of the resin. In this study, a DGEBA epoxy resin with initiators based on anhydride and amine was used under the same conditions indicated by the manufacturer. The curing of the catalyzed system was performed in a domestic microwave oven adapted for laboratory use. The degradation and glass transition temperatures were evaluated by thermal analysis techniques. For comparative purposes, it was used data available in the literature for electron beam irradiation. (author)

  3. Effect of prestorage curing on storage life, internal and external qualities of sweet orange (Citrus sinensis)

    OpenAIRE

    Aborisade,Abiola Titilola; Ajibade,Ayodeji Adeyeye

    2010-01-01

    Orange fruits from two seasons, in April and August 2006 representing late 2005 and early 2006 harvests respectively were cured in hot air at 36-37(0)C to 1%, 3%, 5% and 7% weight loss before storage at 28(0)C and 86% relative humidity (RH). The fruits were observed for incidence of decay, further weight loss, juice content, firmness or softening of the peel, total soluble solids (TSS), pH, titratable acidity, and colour during storage. Curing reduced the incidence of decay. All control fruit...

  4. Crystallization and melting behavior of {beta}-nucleated isotactic polypropylene/polyamide 6 blends with maleic anhydride grafted polyethylene-vinyl acetate as a compatibilizer

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhugen [Materials Science Institute, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Key Laboratory of Polymeric Composites and Functional Materials of the Ministry of Education, Guangzhou 510275 (China); Institut des Nanotechnologies de Lyon, UMR 5270 CNRS, Ecole centrale de Lyon, Equipe Chimie et Nanobiotechnologies, 36 Avenue Guy-de-Collongue, 69134 Ecully (France); Mai, Kancheng, E-mail: cesmkc@mail.sysu.edu.cn [Materials Science Institute, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Key Laboratory of Polymeric Composites and Functional Materials of the Ministry of Education, Guangzhou 510275 (China)

    2010-11-20

    {beta}-Nucleated isotactic polypropylene ({beta}-iPP) blend with maleic anhydride grafted polyethylene-vinyl acetate (EVA-g-MA) and {beta}-iPP/polyamide (PA) 6 blend, as well as its compatibilized version with EVA-g-MA as a compatibilizer were prepared with an internal mixer. Analysis from differential scanning calorimeter (DSC) and wide angle X-ray diffraction (WAXD) indicates that the addition of EVA-g-MA into {beta}-nucleated iPP decreases the crystallization temperature (T{sub c}{sup p}) of PP, but it has no pronounced influence on the {beta}-crystal content for {beta}-nucleated iPP. For {beta}-nucleated iPP/PA6 blends, PA6 obviously decreases the {beta}-crystal content. However, the addition of EVA-g-MA is quite benefit for the formation of {beta}-crystal in {beta}-nucleated iPP/PA6 blends and the {beta}-crystal content increases with increasing EVA-g-MA content. It is suggested that the nucleating agent mainly disperses in the PA6 phase and/or the interface between iPP and PA6 in iPP/PA6 blend, which was proved by etching the blends with sulfuric acid and experimental facts from SEM.

  5. Mechanical characterization and modeling of curing thermosets

    NARCIS (Netherlands)

    Van 't Hof, C.

    2006-01-01

    Chemical shrinkage and simultaneous build-up of mechanical properties in curing thermosets leads to the build-up of residual stresses and strains. Depending on the constraints these may cause interface failure, dimensional inaccuracy or failure in the thermoset or its surrounding structure. The pre

  6. Creep measurements on curing epoxy systems

    DEFF Research Database (Denmark)

    Kammer, Charlotte; Szabo, Peter

    1998-01-01

    The chemical curing of a stoichiometric mixture of the diglycidyl ether of bisphenol A and a 1,3-bis-(aminomethyl)-cyclohexane is studied.Creep experiments are combined with measurements in a Differential Scanning Calorimeter (DSC) to determine the change in bulk viscosity due to network formation....

  7. Internal water curing with Liapor aggregates

    DEFF Research Database (Denmark)

    Lura, Pietro

    2005-01-01

    Internal water curing is a very efficient way to counteract self-desiccation and autogenous shrinkage in high performance concrete, thereby reducing the likelihood of early-age cracking. This paper deals with early-age volume changes and moisture transport in lightweight aggregate concrete realiz...

  8. Creep measurements on curing epoxy systems

    DEFF Research Database (Denmark)

    Kammer, Charlotte; Szabo, Peter

    1998-01-01

    The chemical curing of a stoichiometric mixture of the diglycidyl ether of bisphenol A and a 1,3-bis-(aminomethyl)-cyclohexane is studied.Creep experiments are combined with measurements in a Differential Scanning Calorimeter (DSC) to determine the change in bulk viscosity due to network formation....

  9. Preparation and characterization of porous titania-grafted poly(styrene-divinylbenzene)/maleic anhydride nanocomposite microspheres

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Mesoporous titania-grafted poly(styrene-divinylbenzene)/maleic anhydride [P(St-DVB)/MA] nanocomposite microspheres were prepared by an open ring reaction method.The titania nanoparticles were first modified by attachment of amino groups to their surface to prevent particle aggregation,and to allow the nanoparticles to covalently bond the polymer microspheres,the surface of which was modified by attachment of MA functional groups to enable the polymer to retain their porous structures and to react with the amino groups on the surface of the titania particles.The porous nanocomposite microspheres were detected by FTIR,SEM,TEM,XRD and UV-Vis spectrophotometry.The results indicated that the nanocomposite microspheres were composed of nanosized titania uniformly distributed on the surface,and exhibited better UV absorbing property than pure polymer microspheres or unmodified titania.Furthermore,compared with pure porous polymer microspheres,the nanocomposite microspheres showed more efficient UV protection and slow release of Parsol-1789(a photo-reactive and cosmetic agent) held inside the porous network of the microspheres.

  10. Effect of maleic anhydride treatment on the mechanical properties of sansevieria fiber/vinyl ester composites

    Science.gov (United States)

    Pradipta, Rangga; Mardiyati, Steven, Purnomo, Ikhsan

    2017-03-01

    Sanseviera trifasciata commonly called mother-in-law tongue also known as snake plant is native to Indonesia, India and Africa. Sansevieria is a new fiber in composite research and has showed promising properties as reinforcement material in polymer matrix composites. Chemical treatment on reinforcing fiber is crucial to reduce hydrophilic tendency and thus improve compatibility with the matrix. In this study, effect of maleic anhydride as chemical treatment on the mechanical properties of Sansevieria fiber/vinyl ester composite was investigated. Sansevieria fibers were immersed by using NaOH 3% for two hours at 100°C and then treated by using maleic anhydrate for two hours at 120°C. Composites were prepared by solution casting with various volume fractions of fiber; 0%, 2.5%, 5%, 7.5% and 10%. Actual density, volume fraction of void and mechanical properties of composite were conducted according to ASTM standard testing methods D792, D3171 and D3039. It was found that mechanical properties of composites increased as volume fractions of fiber was increased. The highest tensile strength and modulus of elasticity of composites were 57.45 MPa and 3.47 GPa respectively, obtained from composites with volume fraction of fiber 10%.

  11. Effect of surface modified kaolin on properties of polypropylene grafted maleic anhydride

    Science.gov (United States)

    Yang, Ni; Zhang, Zuo-Cai; Ma, Ning; Liu, Huan-Li; Zhan, Xue-Qing; Li, Bing; Gao, Wei; Tsai, Fang-Chang; Jiang, Tao; Chang, Chang-Jung; Chiang, Tai-Chin; Shi, Dean

    To achieve reinforcement of mechanical and thermal performances of polypropylene (PP) product, this work aimed at fabrication of surface modified kaolin (M-kaolin) filled polypropylene grafted maleic anhydride (PP-g-MAH) composites with varying contents of fillers and investigation of their mechanical and thermal properties. And the prepared PP-g-MAH/M-kaolin composites were characterized by means of Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Fracture analysis by SEM showed M-kaolin particles were well dispersed in the PP-g-MAH matrix. Mechanical behaviors were determined by tensile strength, tensile strain at break and impact strength analysis. Impact strength of PP-g-MAH/2 wt% M-kaolin composites was improved up to 30% comparing with unfilled composites. Thermostability had been found enhanced when M-kaolin added. The results revealed PP-g-MAH/M-kaolin composites showed the optimal thermal and mechanical properties when 2 wt% of M-kaolin was added.

  12. Radical coupling of maleic anhydride onto graphite to fabricate oxidized graphene nanolayers

    Indian Academy of Sciences (India)

    Fatemeh Samadaei; Mehdi Salami-Kalajahi; Hossein Roghani-Mamaqani

    2016-02-01

    Radical coupling was used to modify graphite with maleic anhydride (MAH). Azobisisobutyronitrile (AIBN) as radical generator activated MAH radically and it was reacted with defects at the surface of nanolayers. A set of batches with different reaction times (24, 48 and 72 h) were performed to obtain fully-modified nanolayers (GMA1, GMA2 and GMA3, respectively). Fourier transform infrared results approved the synthesis of MAHgrafted graphite. Thermogravimetric analysis showed that 5.9, 11.1 and 13.2 wt% of MAH was grafted onto the surface of GMA1, GMA2 and GMA3, respectively, and that was approved by X-ray photoelectron spectroscopy results. Also, X-ray diffraction patterns showed that $d$-spacing increased from 0.34 nm for graphite to 1.00 nm for all modified samples. However, GMA1 showed a weak peak related to graphite structure that disappeared when reaction time was increased. After modification with MAH, lamella flake structure of graphite was retained whereas the edges of sheets became distinguishable as depicted by scanning electron microscopy images. According to Raman spectra, modification progression resulted in more disorder structure of nanolayers due to grafting of MAH. Also, transmission electron microscopy images showed graphite as transparent layers while after modification, surface of nanolayers became folded due to the opposite effects of $\\pi$-conjugated domains and electrostatic repulsion of oxygen-containing groups.

  13. Morphology and Mechanical Properties of Nylon 6/PBT Blends Compatibilized with Styrene/Maleic Anhydride Copolymer

    Institute of Scientific and Technical Information of China (English)

    QIN Shu-hao; YU Jie; ZHENG Qiang; HE Min; ZHU Hong

    2007-01-01

    The mechanical properties and dynamic mechanical properties of blends composed of Nylon 6 and poly( butylenes terephthalate) (PBT), with styrene/maleic anhydride(SMA) as compatibilizer, were studied. The observation on the morphologies of the etched surfaces of the cryogenically fractured specimens via scanning electron microscopy(SEM)demonstrated that in the compatibilized Nylon 6/PBT blends, there exists a finer and more uniform dispersion induced by thein-situ interfacial chemical reactions during the preparation than that in the corresponding uncompatibilized blends. On the other hand, the overall mechanical properties of the compatibilized blends could be remarkably improved compared with those of the uncompatibilized ones. Moreover, increasing the amount of the compatibilizer SMA leads to a more efficient dispersion of the PBT phase in Nylon 6/PBT blends. Furthermore, there exists an optimum level of SMA added to achieve the maximum mechanical properties. As far as the mechanism of this reactive compatibilization is concerned, the enhanced interfacial adhesion is necessary to obtain improved dispersion, stable phase morphology, and better mechanical properties.

  14. Reaction of octenylsuccinic anhydride with a mixture of granular starch and soluble maltodextrin.

    Science.gov (United States)

    Bai, Yanjie; Shi, Yong-Cheng

    2013-11-06

    The reaction of octenylsuccinic anhydride (OSA) with a mixture of granular waxy maize starch and soluble maltodextrin was investigated. OSA was reacted with a 1:1 (w/w) mixture of the granular starch and maltodextrin at OSA levels of 1.5, 3, 9, and 15% (wt% based on starch weight). After the first 0.5h of the reaction, degree of substitution (DS) on maltodextrin reached 0.021, 0.030, 0.080, and 0.10 for 1.5, 3, 9, and 15% OSA, respectively, whereas DS for granular starch was only 0.0020, 0.0087, 0.014, and 0.016. At 2h of the reaction, the bound OS ratio of maltodextrin to granular starch was 10.8 when OSA concentration was 1.5% and the ratio decreased to ca. 5 at higher OSA concentrations. OSA preferred to react with maltodextrin than semi-crystalline granular starch when both existed in the system. OSA reacted with maltodextrin at a much faster rate and to a greater extent than with granular starch, but a significant amount of OSA reacted with granular starch at 3-15% OSA concentrations.

  15. Granular size of potato starch affects structural properties, octenylsuccinic anhydride modification and flowability.

    Science.gov (United States)

    Wang, Chan; Tang, Chuan-He; Fu, Xiong; Huang, Qiang; Zhang, Bin

    2016-12-01

    Native potato starch (PS) granules were separated into three size fractions: larger than 30μm (P-L), 15-30μm (P-M), and smaller than 15μm (P-S). The morphological and crystalline structure of fractionated potato starches were investigated by light and scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The P-L fraction showed ellipsoidal shape and B-type X-ray pattern, whereas the P-S fraction had spherical shape and A-type pattern. The fluorophore-assisted capillary electrophoresis data showed that the P-L fraction had more B2 chains and less short A and B1 chains than the P-S counterparts. Smaller granules with larger specific surface area had higher degree of substitution when reacted with octenylsuccinic anhydride (OSA), and showed more uniform distribution of octenylsuccinate substituents. Both OSA modified and unmodified P-S samples showed higher flowability compared with the P-L counterparts.

  16. Separation of maleic anhydride grafted polypropylene using multidimensional high-temperature liquid chromatography.

    Science.gov (United States)

    Prabhu, K N; Macko, T; Brüll, R; Remerie, K; Tacx, J; Garg, P; Ginzburg, A

    2016-04-01

    Functionalization addresses a property gap of polyolefins and opens new perspectives due to improved surface properties in applications like composites (e.g., glass fiber reinforced polypropylene) and anti-corrosive coatings for metals. Various techniques have been developed to characterize functionalized polyolefins, yet no analytical approach addressing their chemical heterogeneity exists. Using High Temperature Size Exclusion Chromatography (HT-SEC) coupled to infrared spectroscopy we could show for two model samples of polypropylene grafted maleic anhydride (PP-g-MA), differing in their nominal MA content, that the grafting density increases with decreasing molar mass. Crystallization Analysis Fractionation (CRYSTAF) does not enable to separate these samples according to their composition to the extent required. Yet, when using High Temperature High Performance Liquid Chromatography (HT-HPLC), with either silica gel or Mica as stationary phase and a gradient mobile phase, a deformulation into a grafted and a non-grafted fraction could be achieved. This was confirmed by analyzing the eluted fractions by infrared spectroscopy. Hyphenating the separation according to composition with a separation according to molar mass (HT-HPLC x HT-SEC) enabled for the first time to reveal the bivariate distribution of PP-g-MA with regard to the molar mass and composition. Using on-line infrared detection quantitative information on the compositional and molar mass parameters of the individual fractions could be obtained.

  17. Position of modifying groups on starch chains of octenylsuccinic anhydride-modified waxy maize starch.

    Science.gov (United States)

    Bai, Yanjie; Kaufman, Rhett C; Wilson, Jeff D; Shi, Yong-Cheng

    2014-06-15

    Octenylsuccinic anhydride (OSA)-modified starches with a low (0.018) and high (0.092) degree of substitution (DS) were prepared from granular native waxy maize starch in aqueous slurry. The position of OS substituents along the starch chains was investigated by enzyme hydrolysis followed by chromatographic analysis. Native starch and two OS starches with a low and high DS had β-limit values of 55.9%, 52.8%, and 34.4%, respectively. The weight-average molecular weight of the β-limit dextrin from the OS starch with a low DS was close to that of the β-limit dextrin from native starch but lower than that of the β-limit dextrin from the OS starch with a high DS. Debranching of OS starches was incomplete compared with native starch. OS groups in the OS starch with a low DS were located on the repeat units near the branching points, whereas the OS substituents in the OS starch with a high DS occurred both near the branching points and the non-reducing ends.

  18. Dodecenylsuccinic anhydride derivatives of gum karaya (Sterculia urens): preparation, characterization, and their antibacterial properties.

    Science.gov (United States)

    Padil, Vinod Vellora Thekkae; Senan, Chandra; Černík, Miroslav

    2015-04-15

    Esterifications of the tree-based gum, gum karaya (GK), using dodecenylsuccinic anhydride (DDSA) were carried out in aqueous solutions. GK was deacetylated using alkali treatment to obtain deacetylated gum karaya (DGK). The DGK and its DDSA derivative were characterized using gel permeation chromatography/multiangle laser light scattering (GPC/MALLS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), proton nuclear magnetic resonance spectroscopy ((1)H NMR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) analysis, and rheological studies. The degree of substitution was found to be 10.25% for DGK using (1)H NMR spectroscopy. The critical aggregation concentration of DDSA-DGK was determined using dye solubilization and surface tension methods. The antibacterial activity of the DDSA-DGK derivative was then investigated against Gram-negative Escherichia coli and Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus. The DDSA-DGK derivative has the potential for use as a stabilizing agent in food and nonfood applications. It can also be developed as an antibacterial agent.

  19. Gelatinization and pasting properties of rice starch modified with 2-octen-1-ylsuccinic anhydride.

    Science.gov (United States)

    Shih, Fred F; Daigle, Kim W

    2003-02-01

    Rice starch was modified with various levels of 2-octen-1-ylsuccinic anhydride (OSA). Treatments with OSA at 3, 5, and 10% resulted in starch derivatives with 0.016, 0.033, and 0.070 degrees of substitution (DS), respectively. Thermovisco properties of the derivatives were investigated by differential scanning calorimetry (DSC) and rapid visco analysis (RVA). Water content in the sample was found to have a significant effect on the characteristics of the DSC endotherm. Pasting properties of the OSA-starch and the effect of pH and salt on the RVA profiles were also studied. In general, with increased OSA-modification, the starch derivatives swelled and gelatinized at lower temperatures to achieve higher viscosities. Specifically, based on DSC analysis at 80% water, the peak temperature of gelatinization decreased from 68.5 to 63.2 degrees C as the OSA modification increased in DS from 0 (intact starch) to 0.070. On the other hand, RVA results indicate that, for samples undergoing similar increase in OSA modification, the pasting temperature decreased from 88.7 to 51.5 degrees C and the peak viscosity increased from 668 to 6822 cP.

  20. Crystal structure of γ-methyl l-glutamate N-carb-oxy anhydride.

    Science.gov (United States)

    Kanazawa, Hitoshi; Inada, Aya; Sakon, Aya; Uekusa, Hidehiro

    2015-01-01

    In the title compound, C7H9NO5, alternative name N-carb-oxy-l-glutamic anhydride γ-methyl ester, the oxazolidine ring is essentially planar with a maximum deviation of 0.020 (3) Å. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds between the imino group and the carbonyl O atom in the methyl ester group, forming a tape structure along the a-axis direction. The tapes are linked by C-H⋯O inter-actions into a sheet parallel to the ac plane. The tapes are also stacked along the b axis with short contacts between the oxazolidine rings [C⋯O contact distances = 2.808 (4)-3.060 (4) Å], so that the oxazolidine rings are arranged in a layer parallel to the ab plane. This arrangement of the oxazolidine rings is very preferable for the polymerization of the title compound in the solid state.

  1. RING OPENING COPOLYMERIZATION OF SUCCINIC ANHYDRIDE-ETHYLENE OXIDE BY Al (Ⅲ) ORGANOMETALLIC CATALYSTS

    Institute of Scientific and Technical Information of China (English)

    CHEN Xianhai; ZHANG Yifeng; SHEN Zhiquan

    1997-01-01

    Ring opening copolymerization of succinic anhydride (SA) with ethylene oxide (EO)was successfully carried out by using a series of aluminum-based catalyst in 1,4-dioxane at 62±2℃. The results showed that in-situ AlR3-H2O (R=ethyl, iso-butyl) catalysts gave higher molecular weight ((-M)w ~ 104), while Al(OR)3 catalysts gave the higher alternating copolymer structure with slightly lower molecular weight. The in-situ AlR3-H2O systems have been evaluated in more detail for the reaction which showed the optimum H2O/Al molar ratio to be 0.5. The copolymers with different composition (FSA/FEO = 36/64 to 45/55 mol/mol) were synthesized by using different monomer feed ratio. The melting point (Tm), glass transition temperature (Tg) and enthalpy of fusion (ΔHf) of these copolymers are depended on the copolymer composition and in the range of 87~ 102℃,-12 ~ -18℃, and 37 ~ 66J/g, respectively. The second heating scan of DSC also indicated that the higher alternating copolymer was more easily recrystallized. The onset decomposition temperature was more than 300℃ under nitrogen and influenced by the copolymer composition.

  2. Acetylation of Wood Flour from Four Wood Species Grown in Nigeria Using Vinegar and Acetic Anhydride

    Directory of Open Access Journals (Sweden)

    Yakubu Azeh

    2013-01-01

    Full Text Available Effect of acetylation on pretreated wood flour of four different wood species, Boabab (Adansonia digitata, Mahoganny (Daniella oliveri, African locust bean (Parkia biglobosa and Beech wood (Gmelina arborea, had been investigated. The first batch of wood species were acetylated using acetic anhydride while the second batch were acetylated with commercial vinegar. Both experiments were conducted in the presence of varying amount of CaCl2 as catalyst and at temperature of 120°C for 3 h. The success of acetylation was determined based on Weight Percent Gain for each sample treated with either chemicals used. FT-IR, a veritable tool was used for the analysis of both treated and untreated samples to further investigate the success of acetylation. The results showed the presence of important band such as carbonyl absorptions at 1743, 1744, 1746, 1731, 1718 and 1696 cm−1 as appeared separately in the spectra of acetylated samples, confirming esterification occurred. The purpose of this work was to investigate the applicability of vinegar for acetylation of lignocellulosic fibers. Blends/composites were prepared by solution casting and their kinetics investigated in distilled water. The results indicated they could be used in outdoor applications such as, decking and packaging.

  3. THERMAL properties and morphology of Polypropylene/Polycarbonate/Polypropylene-Graft-Maleic anhydride blends

    Directory of Open Access Journals (Sweden)

    Mat-Shayuti M. S.

    2016-01-01

    Full Text Available This work investigates the effect of blending polycarbonate (PC into polypropylene (PP matrix polymer on thermal properties and morphology. The blends, containing 5% to 35% of polycarbonate and 5% compatibilizer, were compounded using twin-screw extruder and fabricated into standard tests samples using injection or compression molding. The compatibilizer used was polypropylene-graft-maleic anhydride (PP-g-MA. Thermogravimetric analysis (TGA showed improved thermal degradation temperature of PP/PC/PP-g-MA blends compared to pure PP. As PC content increased, the thermal degradation temperature also improved. The highest improvement of thermal degradation temperature was 23.3%, demonstrated by 60/35/5 composition. It was found that the thermal stability of PP/PC blends was improved with the addition of PP-g-MA. PP-g-MA was suspected to enhance the phase adhesion between PP and PC, thus improving thermal stability. Microscopy analysis showed PC reinforcement phase existed as particulates dispersed in PP matrix phase. PC also was in irregular shapes of fibers or flakes in certain compositions, depending on PC fraction and compatibilizer content.

  4. Cantharidin and its anhydride-modified derivatives: relation of structure to insecticidal activity.

    Science.gov (United States)

    Sun, Wenbo; Liu, Zhongyi; Zhang, Yalin

    2012-12-20

    Cantharidin is a natural compound of novel structure with ideal insecticidal activity. However, the relationship of structure to insecticidal activity of cantharidin and its derivatives has not been ever clarified. To explore what determines the insecticidal activity structurally of cantharidin-related compounds, two series target compounds 6 and 7 were synthesized by replacing the anhydride ring of norcantharidin with an aromatic amine or fatty amine with different electron density, respectively. The structures of these compounds were characterized by 1H NMR, 13C NMR and HRMS-ESI. A bioassay showed that compounds 6 (a-m) lacked any larvicidal activity against Plutella xylostella; whereas their ring-opened partners 7 (a-m) provided a variety of larvicidal activities against P. xylostella, and compound 7f indicated the highest larvicidal activity with LC(50) value of 0.43 mM. The present work demonstrated that the form of the compound (cyclic or ring-opened) or their ability to hydrolyze facilely was the key to determine whether it exhibits larvicidal activity. Moreover, it revealed that the improvement of insecticidal activity required a reasonable combination of both aliphatic amide and aromatic amide moieties, and the type of substituent Y on the aniline ring was critical.

  5. Talking Cure Models: A Framework of Analysis

    Science.gov (United States)

    Marx, Christopher; Benecke, Cord; Gumz, Antje

    2017-01-01

    Psychotherapy is commonly described as a “talking cure,” a treatment method that operates through linguistic action and interaction. The operative specifics of therapeutic language use, however, are insufficiently understood, mainly due to a multitude of disparate approaches that advance different notions of what “talking” means and what “cure” implies in the respective context. Accordingly, a clarification of the basic theoretical structure of “talking cure models,” i.e., models that describe therapeutic processes with a focus on language use, is a desideratum of language-oriented psychotherapy research. Against this background the present paper suggests a theoretical framework of analysis which distinguishes four basic components of “talking cure models”: (1) a foundational theory (which suggests how linguistic activity can affect and transform human experience), (2) an experiential problem state (which defines the problem or pathology of the patient), (3) a curative linguistic activity (which defines linguistic activities that are supposed to effectuate a curative transformation of the experiential problem state), and (4) a change mechanism (which defines the processes and effects involved in such transformations). The purpose of the framework is to establish a terminological foundation that allows for systematically reconstructing basic properties and operative mechanisms of “talking cure models.” To demonstrate the applicability and utility of the framework, five distinct “talking cure models” which spell out the details of curative “talking” processes in terms of (1) catharsis, (2) symbolization, (3) narrative, (4) metaphor, and (5) neurocognitive inhibition are introduced and discussed in terms of the framework components. In summary, we hope that our framework will prove useful for the objective of clarifying the theoretical underpinnings of language-oriented psychotherapy research and help to establish a more comprehensive

  6. Reaction kinetics of piperylene and maleic anhydride%间戊二烯和顺酐反应动力学

    Institute of Scientific and Technical Information of China (English)

    雷昊; 杨阿三; 孙勤; 程榕; 郑燕萍

    2011-01-01

    The reaction of C5 and maleic anhydride to synthesize crude methyltetrahydrophthalic anhydride (MTHPA) is a key step in the production of MTHPA and methylhexahydrophthalic anhydride (MHHPA). The reaction kinetics of piperylene and maleic anhydride under the appropriate solvent was studied. Single-factor multilevel experiment was conducted to show the effects of the initial mole ratio (0.4-1. 1 )of maleic anhydride to piperylene, reaction temperature(1545 t), and solvents (MTHPA, toluene and acetone)on the reaction, and the kinetics data of piperylene and maleic anhydride reaction was determined. Based .on the basic mechanisms of Diels-Alder reaction, a kinetics model was established. By regressing experimental data to a linear fitting based on numerical calculation method, the activation energy and pre-exponential factor were obtained with methyl tetrahydrophthalic anhydride, toluene and acetone as solvents. The results show that the reaction process accords with second-order reaction; different solvents have little influence on activation energy, but have great influences on the pre-exponential factor, in which the activation energy and pre-exponential factor approach the highest values when MTHPA is used as solvent.%C5和顺酐反应合成粗甲基四氢苯酐是生产甲基四氢苯酐及甲基六氢苯酐的关键步骤.为了研究C5中间戊二烯与顺酐反应动力学,选择合适溶剂并设计单因素多水平方案,考察了顺酐与间戊二烯摩尔比(0.4-1.1)、反应温度( 15-45℃)、溶剂(甲基四氢苯酐、甲苯和丙酮)等因素对反应的影响,测定了间戊二烯与顺酐反应的动力学数据.依据Diels-Alder反应的基本原理,建立了动力学模型.利用数值计算方法对实验数据进行线性拟合,分别得到了以甲基四氢苯酐、甲苯和丙酮为溶剂时的活化能和指前因子,结果表明反应符合二级反应.不同溶剂对反应的活化能影响较小,对指前因子影响较大,其中以甲基

  7. Bond strength of a light-cured and two auto-cured glass ionomer liners.

    Science.gov (United States)

    Holtan, J R; Nystrom, G P; Olin, P S; Rudney, J; Douglas, W H

    1990-10-01

    Ninety-nine extracted human molar teeth were used in this study comparing the shear bond strengths on dentine of one light-cured and two auto-cured polyalkenoate (glass ionomer) cements. Bond strength can be influenced by differences in tooth structure. A balanced-incomplete block design (Hull and Nie, 1981) was used to reduce variation attributable to such differences. Cements were applied to paired dentine surfaces in combinations such that 66 tooth sides were treated with each material. A light-cured dentinal adhesive and composite resin restorative material were then placed and shear bond strength testing was conducted exactly 24 h after the completion of each specimen. Mean forces (MPa) for the three materials were compared using an appropriate analysis of variance model (balanced-incomplete-blocks) The shear bond strengths (MPa) of the light-cured liner (Espe, Seefeld/Oberbay, FRG) was 4.71 +/- 1.16. Vitrabond showed the greatest variance of all three materials tested, however this material's average bond strength was greater than the maximum achieved for the other materials. Student-Newman-Keuls comparison of means showed that all cements differed significantly from each other (alpha = 0.05). It is concluded that the light-cured glass ionomer liner exhibited significantly better shear bond strength performance than the two auto-cured glass ionomers tested.

  8. Thermal and Cure Kinetics of Epoxy Molding Compounds Cured with Thermal Latency Accelerators

    Directory of Open Access Journals (Sweden)

    Chean-Cheng Su

    2013-01-01

    Full Text Available The cure kinetics and mechanisms of a biphenyl type epoxy molding compounds (EMCs with thermal latency organophosphine accelerators were studied using differential scanning calorimetry (DSC. Although the use of triphenylphosphine-1,4-benzoquinone (TPP-BQ and triphenylphosphine (TPP catalysts in biphenyl type EMCs exhibited autocatalytic mechanisms, thermal latency was higher in the TPP-BQ catalyst in EMCs than in the TPP catalyst in EMCs. Analyses of thermal characteristics indicated that TPP-BQ is inactive at low temperatures. At high temperatures, however, TPP-BQ increases the curing rate of EMC in dynamic and isothermal curing experiments. The reaction of EMCs with the TPP-BQ latent catalyst also had a higher temperature sensitivity compared to the reaction of EMCs with TPP catalyst. In resin transfer molding, EMCs containing the TPP-BQ thermal latency accelerator are least active at a low temperature. Consequently, EMCs have a low melt viscosity before gelation, and the resins and filler are evenly mixed in the kneading process. Additionally, flowability is increased before the EMCs form a network structure in the molding process. The proposed kinetic model adequately describes curing behavior in EMCs cured with two different organophosphine catalysts up to the rubber state in the progress of curing.

  9. Effect of curing on clinical retention. A 7-year evaluation

    DEFF Research Database (Denmark)

    van Dijken, Jan WV; Pallesen, Ulla

    Objective: To evaluate in a prospective evaluation the retention of Class V compomer and hybrid resin composite restorations placed with a 1-step self etch system and cured with continuous, soft-start and pulse-delay curing. Methods: 139 Class V restorations were placed and cured at random in 60...... subjects with a compomer (Dyract AP;68) or resin composite (Tetric Ceram:67) and cured for 40s with continuous, soft-start and pulse-delay modes. The restorations were evaluated with slightly modified USPHS criteria yearly during 7 years. Results: Of 135 restorations evaluated at 7 years, 29 were lost, 17...... compomer (25%) and 12 Tetric Ceram (18%). The cumulative loss rates for the compomer and resin composite restorations cured with the three curing modes were. continuous cure: 26.1%/18.2%, soft-start: 22.7%/19.0%, pulse delay: 26.1%/16.7%. No statistical difference were seen between the curing modes...

  10. INTRODUCTION Curing is holding fruits at temperatures and ...

    African Journals Online (AJOL)

    One of the. EFFECT OF CURING ON THE SHELF LIFE OF AMBERSWEET ORANGES ... Alternaria citri. Incidence was lowest in fruits cured in the shade to 7% weight loss. .... Period of Storage (Weeks)/ Incidence of Decay (%). (% Wt. loss). 1.

  11. Drinking Peroxide as 'Natural' Cure Leads to Dangerous Blood Clots

    Science.gov (United States)

    ... https://medlineplus.gov/news/fullstory_163513.html Drinking Peroxide as 'Natural' Cure Leads to Dangerous Blood Clots ... 9, 2017 (HealthDay News) -- Ingesting high-concentration hydrogen peroxide as a "natural cure" or cleansing agent may ...

  12. [Dimensional accuracy of microwave-cured denture base resin].

    Science.gov (United States)

    Uchida, K; Okamoto, F; Ogata, K; Sato, T

    1989-02-01

    Recently, microwave-cured denture base resin was developed, and the resin solved the problem of internal porosity which had been generated by curing the conventional denture base resins with microwave irradiation. In this study, the dimensional accuracy of microwave-cured denture base resin was compared with that of other denture base resins, such as pour-type resin, heat-cured resin and heat-shock resin. From the experiment, the following results were obtained. 1. Dimensional accuracy of microwave-cured denture base resin was better than that of heat-cured resin and heat-shock resin, and was similar to that of pour-type resin. 2. Dimensional accuracy of microwave-cured denture base resin by slow cooling method and rapid cooling method was almost the same. Those findings suggest that microwave-cured denture base resin is valuable in clinic.

  13. Determinant of flexible Parametric Estimation of Mixture Cure ...

    African Journals Online (AJOL)

    PROF. OLIVER OSUAGWA

    2015-12-01

    Dec 1, 2015 ... Gastric Cancer data from 76 patients received adjuvant CRT and 125 receiving ... Keywords: Cure Fraction Model, Gastric Cancer, flexible Model, AIC, Mean time to cure. 1.0 Introduction ..... finish cancer registry. Int J Cancer ...

  14. Electron Beam Curing of Polymer Matrix Composites - CRADA Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Janke, C. J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Howell, Dave [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Norris, Robert E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    1997-05-01

    The major cost driver in manufacturing polymer matrix composite (PMC) parts and structures, and one of the elements having the greatest effect on their quality and performance, is the standard thermal cure process. Thermal curing of PMCs requires long cure times and high energy consumption, creates residual thermal stresses in the part, produces volatile toxic by-products, and requires expensive tooling that is tolerant of the high cure temperatures.

  15. Techniques and materials for internal water curing of concrete

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Lura, Pietro

    2006-01-01

    This paper gives an overview of different techniques for incorporation of internal curing water in concrete. Internal water curing can be used to mitigate self-desiccation and selfdesiccation shrinkage. Some concretes may need 50 kg/m3 of internal curing water for this purpose. The price of the i...

  16. 7 CFR 29.6002 - Air-cured.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Air-cured. 29.6002 Section 29.6002 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Definitions § 29.6002 Air-cured. Tobacco cured under natural atmospheric...

  17. 7 CFR 30.12 - Fire-cure.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Fire-cure. 30.12 Section 30.12 Agriculture Regulations... AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.12 Fire-cure. To cure tobacco under artificial atmospheric conditions by the use of open fires, the smoke and...

  18. Curing Reaction Model of Epoxy Asphalt Binder

    Institute of Scientific and Technical Information of China (English)

    QIAN Zhendong; CHEN Leilei; WANG Yaqi; SHEN Jialin

    2012-01-01

    In order to understand the strength developing law of the epoxy asphalt mixture,a curing reaction model of the epoxy asphalt binder was proposed based upon the thermokinetic analysis.Given some assumptions,the model was developed by applying the Kissinger law as well as Arrhenius equation,and the differential scanning calorimetry was performed for estimating the model parameters.To monitor the strength development of the epoxy asphalt mixture,a strength test program was employed and then results were compared to those produced from the proposed model.The comparative evaluation shows that a good consistency exists between the outputs from test program and the proposed model,indicating that the proposed model can be used effectively for simulating the curing reaction process for the epoxy asphalt binder and predicting the strength development for the epoxy asphalt mixture.

  19. Contactless optoelectronic technique for monitoring epoxy cure.

    Science.gov (United States)

    Cusano, A; Buonocore, V; Breglio, G; Calabrò, A; Giordano, M; Cutolo, A; Nicolais, L

    2000-03-01

    We describe a novel noninvasive optical technique to monitor the refractive-index variation in an epoxy-based resin that is due to the polymerization process. This kind of resin is widely used in polymer matrix composites. It is well known that the process of fabricating a thermoset-based composite involves mass and heat transfer coupled with irreversible chemical reactions that induce physical changes. To improve the quality and the reliability of these materials, monitoring the cure and optimization of the manufacturing process are of key importance. We discuss the basic operating principles of an optical system based on angle deflection measurements and present typical cure-monitoring results obtained from optical characterization. The method provides a flexible, high-sensitivity, material-independent, low-cost, noninvasive tool for monitoring real-time refractive-index variation.

  20. Cure of HCV related liver disease.

    Science.gov (United States)

    Shiffman, Mitchell L; Benhamou, Yves

    2015-01-01

    Chronic hepatitis C virus (HCV) causes chronic liver injury and can lead to cirrhosis and hepatocellular carcinoma (HCC). HCV can also interact with the immune system to cause several HCV related disorders including essential mixed cryoglobulinemia, vasculitis, dermatitis, glomerulonephritis and lymphoma. A strong association between HCV and diabetes mellitus also exists. These extrahepatic features may lead to increased fatigue and a reduced quality of life. It is now possible to cure most patients with chronic HCV using oral antiviral therapy. Many of these HCV-related disorders and symptoms can be cured when HCV is eradicated. However, some patients may have irreversible injury to extrahepatic sites, cirrhosis that cannot resolve, an increased risk for HCC, persistent fatigue and a reduced quality of life, despite achieving sustained virological response.

  1. Alternative cancer cures: "unproven" or "disproven"?

    Science.gov (United States)

    Vickers, Andrew

    2004-01-01

    Oncology has always coexisted with therapies offered outside of conventional cancer treatment centers and based on theories not found in biomedicine. These alternative cancer cures have often been described as "unproven," suggesting that appropriate clinical trials have not been conducted and that the therapeutic value of the treatment is unknown. Contrary to much popular and scientific writing, many alternative cancer treatments have been investigated in good quality clinical trials, and they have been shown to be ineffective. In this article, clinical trial data on a number of alternative cancer cures including Livingston-Wheeler, Di Bella Multitherapy, antineoplastons, vitamin C, hydrazine sulfate, Laetrile, and psychotherapy are reviewed. The label "unproven" is inappropriate for such therapies; it is time to assert that many alternative cancer therapies have been "disproven."

  2. Aloe vera as cure for lichen planus.

    Science.gov (United States)

    Patil, Bharati A; Bhaskar, Hebbar Pragati; Pol, Jyoti S; Sodhi, Amandeep; Madhu, Asha V

    2013-01-01

    Oral lichen planus is a difficult condition to treat because of its chronic nature. Various treatment modalities have resulted in partial regression of symptoms but not a complete cure. Aloe vera, a product with minimal adverse effects, can be tried to treat this disorder. A 38-year-old male patient diagnosed with lichen planus of the skin and the oral mucosa was suffering from severe pain and a burning sensation intraorally and pruritus of the skin lesions. Considering the extensive involvement, an herbal alternative was considered. The patient was prescribed aloe vera juice and gel application for two months. At the nine-month follow-up, the patient was symptom-free and totally cured of the intraoral and skin lesions.

  3. Light-Curing Adhesive Repair Tapes

    Science.gov (United States)

    Allred, Ronald; Haight, Andrea Hoyt

    2009-01-01

    Adhesive tapes, the adhesive resins of which can be cured (and thereby rigidized) by exposure to ultraviolet and/or visible light, are being developed as repair patch materials. The tapes, including their resin components, consist entirely of solid, low-outgassing, nonhazardous or minimally hazardous materials. They can be used in air or in vacuum and can be cured rapidly, even at temperatures as low as -20 C. Although these tapes were originally intended for use in repairing structures in outer space, they can also be used on Earth for quickly repairing a wide variety of structures. They can be expected to be especially useful in situations in which it is necessary to rigidize tapes after wrapping them around or pressing them onto the parts to be repaired.

  4. Fast curing ethylene vinyl acetate films with dual curing agent towards application as encapsulation materials for photovoltaic modules

    Directory of Open Access Journals (Sweden)

    W-H. Ruan

    2014-02-01

    Full Text Available To speed up curing of ethylene vinyl acetate (EVA films as encapsulation materials for photovoltaic modules, a dual curing agent of benzoyl peroxide (BPO and butylperoxy 2-ethylhexyl carbonate (TBEC was introduced in this work. The experimental results indicated that for the weight ratio of BPO/TBEC of 0.6/2.4, over 80% gel content of EVA was yielded after curing at 130°C for 12 min. Compared with the case of single curing agent, the present one obviously operated at much lower temperature with faster rate. By carefully studying the influence of curing agent proportion and curing conditions on gel content of EVA films, as well as rheology and curing kinetics, the mechanism involved was analyzed and verified. The results are believed to be useful for developing new curing system of EVA encapsulation films with improved processability.

  5. Synthesis of a Novel UV Curable Aqueous Dispersion Polyurethane PDHA-PEDA-PU and the Properties of Cured Film

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A novel ultraviolet (UV) curable aqueous dispersion polyurethane PDHA-PEDA-PU was synthesized based on isophorone diisocyanate (IPDI), polyester dihydric alcohol (PDHA),dimethylol propionic acid (DMPA), pentaerythritol diacrylate (PEDA), 2-hydroxyethyl acrylate (HEA) and triethylamine (TEA). Acrylate groups were incorporated in the side and end of PDHA-PEDA-PU chain. The C=C content in the chain can be controlled easily through the change of IPDI/PDHA/PEDA ratio. Fourier transform infrared spectroscopy (FTIR) was used to identify the structure of prepolymer, aqueous dispersion and cured polyurethane. The curing rule of the polyurethane for different C=C content has been investigated depending on the change of C=C content during the curing process. The hardness, thermal stability and scrub resistance to MEK of UV cured PDHA-PEDA-PU were also discussed for the samples with different C=C content.

  6. Luminescence spectroscopy applied to a study of the curing process of diglycidyl-ether of bisphenol-A (DGEBA

    Directory of Open Access Journals (Sweden)

    Rita de Cássia Mendonça Sales

    2005-09-01

    Full Text Available This work involved the application of luminescence spectroscopy under steady-state conditions to study the curing process of the epoxy resin diglycidyl-ether of bisphenol-A (DGEBA using the curing agents 4,4'-diaminodiphenylmethane (DDM and 4,4'-diaminodiphenylsulfone (DDS. Two fluorescence methods were employed: the intrinsic method related to the polymeric matrix and the extrinsic method, using the molecular probe 9-anthroic acid (9-AA. Stoichiometric mixtures, with and without 9-AA, were heated to 120 °C at a 5 °C/min heating rate. These samples were then cured at 120 °C for a further 2 hours and allowed to cool to room temperature for 20 minutes. The results obtained by the two methods indicate that the cross-linking reaction can be monitored by analyzing the spectral changes of the emission bands of DGEBA, curing agents and 9-AA.

  7. Trimellitic anhydride-conjugated serum albumin activates rat alveolar macrophages in vitro

    Directory of Open Access Journals (Sweden)

    Bloksma Nanne

    2006-06-01

    Full Text Available Abstract Background Occupational exposure to airborne low molecular weight chemicals, like trimellitic anhydride (TMA, can result in occupational asthma. Alveolar macrophages (AMs are among the first cells to encounter these inhaled compounds and were previously shown to influence TMA-induced asthma-like symptoms in the Brown Norway rat. TMA is a hapten that will bind to endogenous proteins upon entrance of the body. Therefore, in the present study we determined if TMA and TMA conjugated to serum albumin induced the production of the macrophage mediators nitric oxide (NO, tumour necrosis factor (TNF, and interleukin 6 (IL-6 in vitro using the rat AM cell line NR8383 and primary AMs derived from TMA-sensitized and naïve Brown Norway rats. Methods Cells were incubated with different concentrations of TMA, TMA conjugated to bovine serum albumin (BSA, and BSA as a control for 24 h and the culture supernatant was analyzed for mediator content. Results TMA alone was not able to induce the production of mediators by NR8383 cells and primary AMs from sensitized and sham-treated rats. TMA-BSA, on the contrary, dose-dependently stimulated the production of NO, TNF, and IL-6 by NR8383 cells and of NO and TNF, but not IL-6, by primary AMs independent of sensitization. Conclusion Results suggest that although TMA is a highly reactive compound, conjugation to a suitable protein is necessary to induce mediator production by AMs. Furthermore, the observation that effects of TMA-BSA were independent of sensitization suggests involvement of an immunologically non-specific receptor. In the discussion it is argued that a macrophage scavenger receptor is a likely candidate.

  8. Evaporative Derivatization of Phenols with 2-Sulfobenzoic Anhydride for Detection by MALDI-MS

    Science.gov (United States)

    Yao, Yuanyuan; Wang, Poguang; Giese, Roger

    2014-01-01

    RATIONALE Phenols are an important class of analytes, for example as bioactive environmental contaminants. Towards a goal of improving their detection by MALDI-TOF-MS or MALDI-TOF/TOF-MS, we studied their derivatization with 2-sulfobenzoic anhydride (SBA). We chose SBA for this purpose since it is commercially available, inexpensive, and forms an anionic derivative. METHODS In selected conditions developed here for phenols, a reaction mixture of one or more of such compounds in acetonitrile containing SBA and 4-dimethylaminopyridine (DMAP) is evaporated to a solid, heated at 60°C for 1 h, redissolved in 50% acetonitrile containing matrix, spotted onto a MALDI target, and subjected to negative ion MALDI-TOF/TOF-MS. RESULTS While conventional (solution-phase) reaction of 4-phenylphenol (model analyte) with SBA and DMAP only gave a 47% yield of SBA-tagged 4-phenylphenol, evaporative derivatization as above gave a 96% yield, and 25 pmol (4.3 ng) of 4-phenylphenol could be detected in this way by MALDI-TOF/TOF-MS at S/N = 260, whereas even 1 nmol of the nonderivatized phenol was not detected in the absence of derivatization. A wide range of responses was observed when a mixture of 15 phenols was derivatized, with the higher responses coming from phenols with a pKa value above 9. Without derivatization, phenols with pKa values below 5 were the most readily detected. CONCLUSION Evaporative derivatization with SBA (a convenient reagent) can improve the detection of phenols with relatively high pKa values (above 9) by negative ion MALDI-TOF-MS, and accomplish this in the absence of post-derivatization reaction cleanup. PMID:24519828

  9. Elucidation of substituted ester group position in octenylsuccinic anhydride modified sugary maize soluble starch.

    Science.gov (United States)

    Ye, Fan; Miao, Ming; Huang, Chao; Lu, Keyu; Jiang, Bo; Zhang, Tao

    2014-12-01

    The octenylsuccinic groups in esterification-modified sugary maize soluble starches with a low (0.0191) or high (0.0504) degree of substitution (DS) were investigated by amyloglucosidase hydrolysis followed by a combination of chemical and physical analysis. The results showed the zeta-potential remained at approximately the same value regardless of excessive hydrolysis. The weight-average molecular weight decreased rapidly and reached 1.22 × 10(7) and 1.60 × 10(7) g/mol after 120 min for low-DS and high-DS octenylsuccinic anhydride (OSA) modified starch, respectively. The pattern of z-average radius of gyration as well as particle size change was similar to that of Mw, and z-average radius of gyration decreased much more slowly, especially for high-DS OSA starch. Compared to native starch, two characteristic absorption peaks at 1726.76 and 1571.83 cm(-1) were observed in FT-IR spectra, and the intensity of absorption peaks increased with increasing DS. The NMR results showed that OSA starch had several additional peaks at 0.8-3.0 ppm and a shoulder at 5.56 ppm for OSA substituents, which were grafted at O-2 and O-3 positions in soluble starch. The even distribution of OSA groups in the center area of soluble starch particle has been directly shown under CLSM. Most substitutions were located near branching points of soluble starch particles for a low-DS modified starch, whereas the substituted ester groups were located near branching points as well as at the nonreducing ends in OSA starch with a high DS.

  10. Trimellitic anhydride (TMA) dust induces airway obstruction and eosinophilia in non-sensitized guinea pigs.

    Science.gov (United States)

    Larsen, Christen P; Regal, Jean F

    2002-09-02

    Trimellitic anhydride (TMA) causes asthma after a latency period of sensitization. In non-sensitized humans and animals, limited studies indicate that TMA exposure may also cause symptoms of asthma without a latency period. Our previous studies (J. Pharmacol. Exp. Ther. 296 (2001) 284) in a guinea pig model of TMA-induced asthma demonstrated that sensitization and the complement system were required for eosinophilia. TMA conjugated to guinea pig serum albumin (TMA-GPSA) was used to elicit the response. Since occupational exposure to TMA occurs by inhalation of dust, the present studies determined if exposure to TMA dust in a non-sensitized guinea pig elicited airway obstruction and inflammation, and whether a significantly greater response occurred after a latency period of sensitization. Guinea pigs were intradermally injected with either corn oil (non-sensitized animals) or 30% TMA (sensitized animals). Three weeks later they were challenged by intratracheal insufflation with 1 mg TMA dust or lactose dust (control) using a dry powder delivery device. Pulmonary resistance, dynamic lung compliance, mean arterial blood pressure and heart rate were monitored for 10 min. In non-sensitized guinea pigs, significant increases in pulmonary resistance and decreases in dynamic lung compliance and blood pressure occurred after TMA challenge. In sensitized animals, the same dose of TMA caused significantly greater effects compared to non-sensitized animals. In a separate experiment, cellular infiltration into the lung was determined 24 h after challenge with TMA dust or lactose dust. In both non-sensitized and sensitized animals, eosinophils in the lung tissue were increased after TMA dust challenge compared to controls. Thus, these studies suggest that the response in non-sensitized animals differs depending on whether TMA dust or TMA-GPSA is used to elicit the response. TMA dust elicits significant airway obstruction and eosinophilia in a non-sensitized animal, with even

  11. Coating and curing apparatus and methods

    Energy Technology Data Exchange (ETDEWEB)

    Brophy, Brenor L.; Gonsalves, Peter R.; Maghsoodi, Sina; Colson, Thomas E.; Yang, Yu S.; Abrams, Ze' ev R.

    2016-04-19

    Disclosed is a coating apparatus including flow coating and roll-coating that may be used for uniform sol-gel coating of substrates such as glass, solar panels, windows or part of an electronic display. Also disclosed are methods for substrate preparation, flow coating and roll coating. Lastly, systems and methods for curing sol-gel coatings deposited onto the surface of glass substrates using high temperature air-knives, infrared emitters and direct heat applicators are disclosed.

  12. Photothermal Monitoring Of Curing Of Polymers

    Science.gov (United States)

    Rooney, Michael

    1993-01-01

    Time-resolved infrared radiometry (TRIR) adapted to monitoring curing of some polymers in production. Proposal part of continuing effort to perfect production of hydroxy-terminated polybutadiene for use in liners of solid-fuel rocket motors. Applicable to monitoring changing states of many other materials in process. TRIR, non-contact technique implemented with remotely situated equipment and better suited to use in production.

  13. Using Sex to Cure the Genome.

    Directory of Open Access Journals (Sweden)

    Eduardo P C Rocha

    2016-03-01

    Full Text Available The diversification of prokaryotes is accelerated by their ability to acquire DNA from other genomes. However, the underlying processes also facilitate genome infection by costly mobile genetic elements. The discovery that cells can uptake DNA by natural transformation was instrumental to the birth of molecular biology nearly a century ago. Surprisingly, a new study shows that this mechanism could efficiently cure the genome of mobile elements acquired through previous sexual exchanges.

  14. Sage Gene Expression Profiles Characterizing Cure

    Science.gov (United States)

    2006-10-01

    therapies to improve breast cancer cure frequency. Down Regulation of VEGF in MTCL Cells. RNA interference has been a powerful genetic tool to study...Science 296, 550 (2002). 100. D. A. Rubinson et al., Nat Genet 33, 401 (2003). 101. E. Devroe, P. A. Silver, BMC Biotechnol 2 (2002). 102. J. P...double- plotted along the estrous cycle. Double plotting of rhythmic patterns is a standard chronobiological technique that allows visualization of

  15. Synthesis, characterisation, and evaluation of a cross-linked disulphide amide-anhydride-containing polymer based on cysteine for colonic drug delivery.

    Science.gov (United States)

    Lim, Vuanghao; Peh, Kok Khiang; Sahudin, Shariza

    2013-12-18

    The use of disulphide polymers, a low redox potential responsive delivery, is one strategy for targeting drugs to the colon so that they are specifically released there. The objective of this study was to synthesise a new cross-linked disulphide-containing polymer based on the amino acid cysteine as a colon drug delivery system and to evaluate the efficiency of the polymers for colon targeted drug delivery under the condition of a low redox potential. The disulphide cross-linked polymers were synthesised via air oxidation of 1,2-ethanedithiol and 3-mercapto-N-2-(3-mercaptopropionamide)-3-mercapto propionic anhydride (trithiol monomers) using different ratio combinations. Four types of polymers were synthesised: P10, P11, P151, and P15. All compounds synthesised were characterised by NMR, IR, LC-MS, CHNS analysis, Raman spectrometry, SEM-EDX, and elemental mapping. The synthesised polymers were evaluated in chemical reduction studies that were performed in zinc/acetic acid solution. The suitability of each polymer for use in colon-targeted drug delivery was investigated in vitro using simulated conditions. Chemical reduction studies showed that all polymers were reduced after 0.5-1.0 h, but different polymers had different thiol concentrations. The bacterial degradation studies showed that the polymers were biodegraded in the anaerobic colonic bacterial medium. Degradation was most pronounced for polymer P15. This result complements the general consensus that biodegradability depends on the swellability of polymers in an aqueous environment. Overall, these results suggest that the cross-linked disulphide-containing polymers described herein could be used as coatings for drugs delivered to the colon.

  16. Synthesis, Characterisation, and Evaluation of a Cross-Linked Disulphide Amide-Anhydride-Containing Polymer Based on Cysteine for Colonic Drug Delivery

    Directory of Open Access Journals (Sweden)

    Vuanghao Lim

    2013-12-01

    Full Text Available The use of disulphide polymers, a low redox potential responsive delivery, is one strategy for targeting drugs to the colon so that they are specifically released there. The objective of this study was to synthesise a new cross-linked disulphide-containing polymer based on the amino acid cysteine as a colon drug delivery system and to evaluate the efficiency of the polymers for colon targeted drug delivery under the condition of a low redox potential. The disulphide cross-linked polymers were synthesised via air oxidation of 1,2-ethanedithiol and 3-mercapto-N-2-(3-mercaptopropionamide-3-mercapto propionic anhydride (trithiol monomers using different ratio combinations. Four types of polymers were synthesised: P10, P11, P151, and P15. All compounds synthesised were characterised by NMR, IR, LC-MS, CHNS analysis, Raman spectrometry, SEM-EDX, and elemental mapping. The synthesised polymers were evaluated in chemical reduction studies that were performed in zinc/acetic acid solution. The suitability of each polymer for use in colon-targeted drug delivery was investigated in vitro using simulated conditions. Chemical reduction studies showed that all polymers were reduced after 0.5–1.0 h, but different polymers had different thiol concentrations. The bacterial degradation studies showed that the polymers were biodegraded in the anaerobic colonic bacterial medium. Degradation was most pronounced for polymer P15. This result complements the general consensus that biodegradability depends on the swellability of polymers in an aqueous environment. Overall, these results suggest that the cross-linked disulphide-containing polymers described herein could be used as coatings for drugs delivered to the colon.

  17. Safety evaluation of long-term vas occlusion with styrene maleic anhydride and its non-invasive reversal on accessory reproductive organs in langurs

    Institute of Scientific and Technical Information of China (English)

    B. Manivannan; S. S. Bhande; S. Panneerdoss; S. Sriram; N. K. Lohiya

    2005-01-01

    Aim: To evaluate the safety of the long term vas occlusion with styrene maleic anhydride (SMA) and its non-invasive reversal at the level of accessory reproductive glands (ARGs) in langurs. Methods: The morphology of seminal vesicle and ventral prostate was evaluated by light as well as transmission electron microscopy. Serum clinical chemistry and urine albumin were evaluated in an autoanalyzer using reagent kits. Fructose, acid phosphatase and zinc in the seminal plasma were evaluated spectrophotomet-ically according to the WHO manual. Serum testosterone,prostate specific antigen and sperm antibodies were evaluated by enzyme-linked immunosorbent assays (ELISA)using reagent kits and hematology was estimated according to standard procedures. Results: The morphological features and secretory activity of the seminal vesicle and prostate were normal as evidenced by the presence of welldeveloped mitochondria, rough endoplasmic reticulum, Golgi bodies, secretory granules and normal nuclear characteristics throughout the course of investigation. Serum testosterone and prostate specific antigen remained unaltered and serum antisperm antibodies level presented negative titres. Urine albumin was nil. Total red blood corpuscles (RBC), white blood corpuscles (WBC), hemoglobin (Hb) and red cell indices, serum protein, glucose, cholesterol,creatinine, creatine kinase (CK), serum glutamate oxalate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT), lactate dehydrogenase (LDH), bilirubin, urea, triglycerides and high-density lipoprotein (HDL) did not show appreciable changes following vas occlusion and after its non-invasive reversal. Although fructose, acid phosphatase (ACP) and zinc in the seminal plasma showed a significant reduction following vas occlusion, it could not be related to the morphology of seminal vesicle and prostate. Conclusion: SMA vas occlusion and its non-invasive reversal do not damage the accessory reproductive organs.

  18. Cure Behavior and Thermal Properties of Diepoxidized Cardanol Resin Cured by Electron Beam Process

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Donghwan; Cheon, Jinsil [Kumoh National Institute of Technology, Gumi (Korea, Republic of)

    2013-07-01

    Thermal curing of epoxy resin requires high temperature, time-consuming process and the volatilization of hardener. It has known that electron beam curing of epoxy resin is a fast process and occurs at low or room temperature that help reduce residual mechanical stresses in thermosetting polymers. Diepoxidized cardanol (DEC) can be synthesized by an enzymatic method from cashew nut shell liquid (CNSL), that constitutes nearly one-third of the total nut weight. A large amount of CNSL can be formed as a byproduct of the mechanical processes used to render the cashew kerneledible and its total production approaches one million tons annually, which can be bio-degradable and replace the industrial thermosetting plastics. It is expected that DEC may be cured as in an epoxy resin, which was constituted on two epoxide group and long alkyl chain, and two-types of onium salts (cationic initiator) were used as a photo-initiator. The experimental variables of this study are type and concentration of photo-initiators and electron beam dosage. In this study, the effects of initiator type and concentration on the cure behavior and the thermal properties of DEC resin processed by using electron beam technology were studied using FT-IR, TGA, TMA, DSC, and DMA. Figure 1 is the FT-IR results, showing the change of chemical structure of pure DEC and electron beam cured DEC. The characteristic absorption peak of epoxide group appeared at 850cm{sup -1}. The shape and the height were reduced when the sample was irradiated with electron beam. From this result, the epoxide groups is DEC were opened by electron beam and cured. After then, electron beam cured DEC was investigated the effect of forming 3-dimensional network.

  19. Ultrasonic characterization of the fat source and composition of formulated dry-cured meat products.

    Science.gov (United States)

    Jimenez, Edith Corona; García-Pérez, Jose Vicente; Canillas, Sonia Ventanas; Fort, Jose Javier Benedito

    2014-06-01

    The aim of this work was to test the feasibility of using ultrasonic measurements to estimate the fat content and identify the fat sources used in formulated dry-cured pork meat products. For that purpose, dry-cured sausages were prepared using different fat sources (two Iberian pork backfats, Iberian lard, and sunflower oil) and contents (fat content from 3% to 17% wet basis) and characterized by measuring the ultrasonic velocity (at 2 degrees C, 6 degrees C, 10 degrees C, 15 degrees C, 20 degrees C, and 25 degrees C), fatty acid profile, thermal behavior, and composition. The fatty acid composition affected the melting behavior of the sausages, which also involved different ultrasonic velocities, depending on the fat source used for the sausage formulation. Significant (p sausage batches were differentiated according to the fat source used. The ultrasonic velocity temperature dependence allowed the determination of the fat content (explained variance 96.1%) by measuring the ultrasonic velocity in the dry-cured sausages at 2 degrees C and 25 degrees C and using a semi-empirical equation. Therefore, the ultrasonic measurements could be considered as a reliable tool for the characterization and differentiation of formulated dry-cured meat products with different fat sources and contents.

  20. Dentin Bond Strength of Two One-Bottle Adhesives after Delayed Activation of Light-Cured Resin Composites

    Directory of Open Access Journals (Sweden)

    F. Shafiei

    2007-12-01

    Full Text Available Objective: Adverse surface interactions between one-bottle adhesives and chemical-cured composites may occur with delayed light activation of light-cured composites. The purpose of this study was to assess the Effects of delayed activation of light-cured compositeson shear bond strength of two one-bottle adhesives with different acidity to bovine dentin.Materials and Methods: Flat dentin surface was prepared on sixty-six bovine incisors using 600 grit carbide papers. Prime&Bond NT, and One-Step adhesives and resin composite were applied in six groups: 1 immediate curing of the composite, 2 the composite was left 2.5 minutes over the cured adhesive before light activation, 3 prior to delayed activation of the composite, the cured adhesive was covered with a layer of nonacidic hydrophobic porcelain bonding resin (Choice 2 and cured immediately. After thermocycling,shear bond strength (SBS test was performed using a universal testing machine at 1 mm/min crosshead speed. Data were analyzed with Friedmans two-way Non-parametric ANOVA.Results: The SBS of delayed activation of Prime&Bond was significantly lower than immediate activated (P<0.05. Decrease in the SBS of One-Step was not statistically significant after delayed activation. The SBS of delayed activation of Prime&Bond and One-Step with an additional resin layer was significantly higher than delayed activation (P<0.001.Conclusion: The bond strength of Prime&Bond might be compromised by the higher acidity of this adhesive during the 2.5 minutes delayed activation of light-cured composite.Addition of a layer of hydrophobic resin compensated the effect of delayed activation andimproved the bond strength.

  1. Effects of Salicylic Acid on Photosynthesis and Chlorophyll Fluorescence Characteristics of Flue-cured Tobacco Leaf in Subdued Light%弱光下水杨酸对烤烟光合特性与叶绿素荧光的影响

    Institute of Scientific and Technical Information of China (English)

    王辉; 刘国顺; 云菲; 张军; 郭超超

    2014-01-01

    [Objective] This study aimed to test whether salicylic acid (SA) can im-prove the physiological functions of flue-cured tobacco under subdued light condition, and to determine the mechanism of its action. [Method] The tobacco plants under subdued light were foliar-sprayed with 100 mg/L of SA. Then, the physiological in-dices such as plant fresh weight and dry weight, chlorophyl content, photosynthetic parameters and chlorophyl fluorescence parameters were measured. SPSS17.0 and Excellwere adopted for variance analysis and significance test. [Result] The leaf photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) of tobacco plants in subdued light were al decreased while the intercellular CO2 con-centration (Ci) was increased, suggesting that non-stomatal limitation led to the de-crease of Pn under weak light intensity stress. SA released the inhibition of tobacco plant growth in weak light, as it elevated the leaf photosynthetic rate, the maximum photochemical efficiency of PSⅡ, potential activity of PSⅡ, effective photochemical efficiency of PSⅡ and photochemical quenching coefficient in weak light significant-ly, and reduced the non-photochemical quenching coefficient. [Conclusion] SA has significant effects on the photosynthetic characteristics of flue-cured tobacco in weak light, and it can improve the synthesis or distribution of photosynthesis product, and the efficiency of light energy, conducive to plant growth and development.%[目的]探讨外源水杨酸(SA)能否提高烤烟在弱光条件下的生理功能及其作用机制。[方法]在弱光条件下,对烤烟叶面进行 SA喷施,测定喷施后烟草植株的生理指标,包括植株鲜重和干重、叶绿素含量、光合参数和叶绿素荧光参数。数据采用 SPSS17.0和 Excel软件进行方差分析和显著性检验。[结果]弱光下烤烟叶片的光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)分别降低,而胞间 CO2浓度(Ci)

  2. Mammalian-like Purple Acid Phosphatases in Plants

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Introduction Purple acid phosphatases (PAPs) comprise of a family of binuclear metal-containing hydrolases, some members of which have been isolated and characterized from animal, plant and fungal sources[1]. PAPs not only catalyze the hydrolyses of a wide range of phosphate esters and anhydrides under acidic reaction conditions,but also catalyze the generation of hydroxyl radicals in a Fenton-like reaction, by virtue of the presence of a redox-active binuclear metal center.

  3. Biocompatible photocrosslinked poly(ester anhydride) based on functionalized poly(epsilon-caprolactone) prepolymer shows surface erosion controlled drug release in vitro and in vivo.

    Science.gov (United States)

    Mönkäre, J; Hakala, R A; Vlasova, M A; Huotari, A; Kilpeläinen, M; Kiviniemi, A; Meretoja, V; Herzig, K H; Korhonen, H; Seppälä, J V; Järvinen, K

    2010-09-15

    Star-shaped poly(epsilon-caprolactone) oligomers functionalized with succinic anhydride were used as prepolymers to prepare photocrosslinked poly(ester anhydride) to evaluate their in vivo drug delivery functionality and biocompatibility. Thus, in this work, erosion, drug release and safety of the photocrosslinked poly(ester anhydride) were examined in vitro and in vivo. A small water-soluble drug, propranolol HCl (M(w) 296 g/mol, solubility 50 mg/ml), was used as the model drug in an evaluation of the erosion controlled release. Drug-free and drug-loaded (10-60% w/w) poly(ester anhydride) discoids eroded in vitro (pH 7.4 buffer, +37 degrees C) linearly within 24-48 h. A strong correlation between the polymer erosion and the linear drug release in vitro was observed, indicating that the release had been controlled by the erosion of the polymer. Similarly, in vivo studies (s.c. implantation of discoids in rats) indicated that surface erosion controlled drug release from the discoids (drug loading 40% w/w). Oligomers did not decrease cell viability in vitro and the implanted discoids (s.c., rats) did not evoke any cytokine activity in vivo. In summary, surface erosion controlled drug release and the safety of photocrosslinked poly(ester anhydride) were demonstrated in this study.

  4. An Examination of the Chemistry of Peroxycarboxylic Nitric Anhydrides and Related Volatile Organic Compounds During Texas Air Quality Study 2000 Using Ground-Based Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, James M.; Jobson, B Tom T.; Kuster, W. C.; Goldan, P. D.; Murphy, Paul; Williams, Eric; Frost, G. J.; Riemer, D.; Apel, Eric; Stroud, C.; Wiedinmyer, Christine; Fehsenfeld, Fred C.

    2003-08-19

    Measurements of peroxycarboxylic nitric anhydrides (PANs) along with related volatile organic compounds (VOCs) were made at the La Porte super site during the TexAQS 2000 Houston study. The PAN mixing ratios ranged up to 6.5 ppbv and were broadly correlated with O3, characteristic of a highly polluted urban environment. The anthropogenic PAN homologue concentrations were generally consistent with those found in other urban environments; peroxypropionic nitric anhydride (PPN) averaged 15%, and peroxyisobutyric nitric anhydride (PiBN) averaged 3% of PAN,. Some periods were noted where local petrochemical sources resulted in anomalous PANs chemistry. This effect was especially noticeable in the case of peroxyacrylic nitric anhydride (APAN) where local sources of 1,3-butadiene and acrolein resulted in APAN as high as 30% of PAN. Peroxymethacrylic nitric anhydride (MPAN) was a fairly minor constituent of the PANs except for two periods on 4 and 5 September when air masses from high biogenic hydrocarbons (BHC) areas were observed. BHC chemistry was not a factor in the highest ozone pollution episodes in Houston but may have an impact on daily average ozone levels in some circumstances.

  5. Accurate Cure Modeling for Isothermal Processing of Fast Curing Epoxy Resins

    Directory of Open Access Journals (Sweden)

    Alexander Bernath

    2016-11-01

    Full Text Available In this work a holistic approach for the characterization and mathematical modeling of the reaction kinetics of a fast epoxy resin is shown. Major composite manufacturing processes like resin transfer molding involve isothermal curing at temperatures far below the ultimate glass transition temperature. Hence, premature vitrification occurs during curing and consequently has to be taken into account by the kinetic model. In order to show the benefit of using a complex kinetic model, the Kamal-Malkin kinetic model is compared to the Grindling kinetic model in terms of prediction quality for isothermal processing. From the selected models, only the Grindling kinetic is capable of taking into account vitrification. Non-isothermal, isothermal and combined differential scanning calorimetry (DSC measurements are conducted and processed for subsequent use for model parametrization. In order to demonstrate which DSC measurements are vital for proper cure modeling, both models are fitted to varying sets of measurements. Special attention is given to the evaluation of isothermal DSC measurements which are subject to deviations arising from unrecorded cross-linking prior to the beginning of the measurement as well as from physical aging effects. It is found that isothermal measurements are vital for accurate modeling of isothermal cure and cannot be neglected. Accurate cure predictions are achieved using the Grindling kinetic model.

  6. Post-cure depth of cure of bulk fill dental resin-composites.

    Science.gov (United States)

    Alrahlah, A; Silikas, N; Watts, D C

    2014-02-01

    To determine the post-cure depth of cure of bulk fill resin composites through using Vickers hardness profiles (VHN). Five bulk fill composite materials were examined: Tetric EvoCeram(®) Bulk Fill, X-tra base, Venus(®) Bulk Fill, Filtek™ Bulk Fill, SonicFill™. Three specimens of each material type were prepared in stainless steel molds which contained a slot of dimensions (15 mm × 4 mm × 2 mm), and a top plate. The molds were irradiated from one end. All specimens were stored at 37°C for 24h, before measurement. The Vickers hardness was measured as a function of depth of material, at 0.3mm intervals. Data were analysed by one-way ANOVA using Tukey post hoc tests (α=0.05). The maximum VHN ranged from 37.8 to 77.4, whilst the VHN at 80% of max.VHN ranged from 30.4 to 61.9. The depth corresponding to 80% of max.VHN, ranged from 4.14 to 5.03 mm. One-way ANOVA showed statistically significant differences between materials for all parameters tested. SonicFill exhibited the highest VHN (presin composites can be cured to an acceptable post-cure depth, according to the manufacturers' claims. SonicFill and Tetric EvoCeram Bulk Fill had the greatest depth of cure among the composites examined. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  7. Samarium-modified vanadium phosphate catalyst for the selective oxidation of n-butane to maleic anhydride

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Hua-Yi [State Key Laboratory of Physical Chemistry of Solid Surfaces, National Engineering Laboratory for Green Chemical Productions of Alcohols, Ethers and Esters, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Wang, Hai-Bo [Fushun Res InstPetr& Petrochem, Fushun, 113001 (China); Liu, Xin-Hua; Li, Jian-Hui; Yang, Mei-Hua [State Key Laboratory of Physical Chemistry of Solid Surfaces, National Engineering Laboratory for Green Chemical Productions of Alcohols, Ethers and Esters, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Huang, Chuan-Jing, E-mail: huangcj@xmu.edu.cn [State Key Laboratory of Physical Chemistry of Solid Surfaces, National Engineering Laboratory for Green Chemical Productions of Alcohols, Ethers and Esters, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Weng, Wei-Zheng [State Key Laboratory of Physical Chemistry of Solid Surfaces, National Engineering Laboratory for Green Chemical Productions of Alcohols, Ethers and Esters, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Wan, Hui-Lin, E-mail: hlwan@xmu.edu.cn [State Key Laboratory of Physical Chemistry of Solid Surfaces, National Engineering Laboratory for Green Chemical Productions of Alcohols, Ethers and Esters, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China)

    2015-10-01

    Graphical abstract: The addition of a small amount of Sm into VPO catalyst brought about great changes in its physicochemical properties such as surface area, surface morphology, phase composition and redox property, thus leading to a higher catalytic performance in the selective oxidation of n-butane to maleic anhydride, as compared to the undoped VPO catalyst. - Highlights: • The addition of Sm leads to great changes in the structure of VPO catalyst. • Sm improves performance of VPO for oxidation of n-butane to maleic anhydride. • Catalytic performance is closely related to structure of VPO catalyst. - Abstract: A series of samarium-modified vanadium phosphate catalysts were prepared and studied in selective oxidation of n-butane to maleic anhydride. The catalytic evaluation showed that Sm modification significantly increased the overall n-butane conversion and intrinsic activity. N{sub 2}-adsorption, XRD, SEM, Raman, XPS, EPR and H{sub 2}-TPR techniques were used to investigate the intrinsic difference among these catalysts. The results revealed that the addition of Sm to VPO catalyst can increase the surface area of the catalyst, lead to a significant change in catalyst morphology from plate-like structure into rosette-shape clusters, and largely promote the formation of (VO){sub 2}P{sub 2}O{sub 7}. All of these were related to the different catalytic performance of Sm-doped and undoped VPO catalysts. The roles of the different VOPO{sub 4} phases and the influence of Sm were also described and discussed.

  8. Short-chain grafting of tetrahydrofuran and 1,4-dioxane cycles on vinylchloride-maleic anhydride copolymer

    Directory of Open Access Journals (Sweden)

    2009-01-01

    Full Text Available Mass increase of vinylchloride-maleic anhydride (VC-MA copolymer samples aged in tetrahydrofuran (THF or in 1,4-dioxane results from chemical interaction of VC-MA macromolecules with 1,4-dioxane or THF. Microstructure of the products of such modification was proved by infrared spectroscopy (IR- and nuclear magnetic resonance spectroscopy (13C NMR and 1H NMR. Mechanism of modification has been proposed. The results of microstructure research of VC-MA samples aged in THF and in 1,4-dioxane coincide with already known data on the reactions of opening of these and other oxygen-containing cycles under mild conditions.

  9. SELECTIVE SEPARATION OF WATER—ETHANOL MIXTURE THROUGH COPOLYMERIC MEMBRANES.Ⅱ.ACRYLONITRILE AND MALEIC ANHYDRIDE COPOLYMERIC MEMBRANES

    Institute of Scientific and Technical Information of China (English)

    ZHangFuyao; ZhangYifeng; 等

    1993-01-01

    Acrylonitrile(AN) and maleic anhydride(MA) copolymer has been synthesized by radical polymerization using ammonium persulfate and sodium bisulfite as initiator.The pervaporation properties of the copolymeric membranes prepared have been investigated for the first time. The dependences of pervaporation characteristics on coplymer composition,feed concentration and operating temperature have been studied.In order to improve the separation properties of the copolymeric membranes,the membranes were hydrolyzed with 10 wt% soldium hydroxide or potassium hydroxide aqueous solution.The hydrolyzed membranes containing more than 0.069MA mol fraction showed higher tensile strength and separation properties than the original membranes.

  10. CURING OF POLYMERIC COMPOSITES USING MICROWAVE RESIN TRANSFER MOULDING (RTM

    Directory of Open Access Journals (Sweden)

    R. YUSOFF

    2007-08-01

    Full Text Available The main objective of this work is to compare the difference between microwave heating and conventional thermal heating in fabricating carbon/epoxy composites. Two types of epoxy resin systems were used as matrices, LY5052-HY5052 and DGEBA-HY917-DY073. All composite samples were fabricated using resin transfer moulding (RTM technique. The curing of the LY5052-HY5052-carbon and the DGEBA-HY917-DY073-carbon composite systems, were carried out at 100 °C and 120 °C, respectively. Microwave heating showed better temperature control than conventional heating, however, the heating rate of the microwave cured samples were slower than the conventionally cured samples. This was attributed to the lower power (250 W used when heating with microwaves compared to 2000 W used in conventional heating. Study of thermal characteristics as curing progressed showed that the polymerisation reaction occurred at a faster rate during microwave curing than in conventional curing for both the DGEBA and the LY/HY5052 carbon composite systems. The actual cure cycle was reduced from 60 minutes to 40 minutes when using microwaves for curing DGEBA-carbon composites. As for LY/HY5052-carbon composites, the actual cure cycle was reduced from 3 hours to 40 minutes. Both conventional and microwave heating yielded similar glass transition temperatures (120 °C for DGEBA systems and 130 °C for LY/HY5052 systems. Microwave cured composites had higher void contents than conventionally cured composites (2.2-2.8% and 1.8-2.4% for DGEBA and LY/HY5052 microwave cured composites, respectively, compared to 0.2-0.4% for both DGEBA and LY/HY5052 thermally cured composites. C-scan traces showed that all composites, regardless of methods of curing, had minimal defects.

  11. Cure shrinkage effects in epoxy and polycyanate matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Spellman, G.P.

    1995-12-22

    A relatively new advanced composite matrix, polycyanate ester, was evaluated for cure shrinkage. The chemical cure shrinkage of composites is difficult to model but a number of clever experimental techniques are available to the investigator. In this work the method of curing a prepreg layup on top of a previously cured laminate of identical ply composition is utilized. The polymeric matrices used in advanced composites have been primarily epoxies and therefore a common system of this type, Fiberite 3501-6, was used as a base case material. Three polycyanate matrix systems were selected for the study. These are: Fiberite 954-2A, YLA RS-3, and Bryte Technology BTCy-1. The first three of these systems were unidirectional prepreg with carbon fiber reinforcement. The Bryte Technology material was reinforced with E-glass fabric. The technique used to evaluate cure shrinkage results in distortion of the flatness of an otherwise symmetric laminate. The first laminate is cured in a conventional fashion. An identical layup is cured on this first laminate. During the second cure all constituents are exposed to the same thermal cycles. However, only the new portion of the laminate will experience volumetric changes associate with matrix cure. The additional strain of cure shrinkage results in an unsymmetric distribution of residual stresses and an associated warpage of the laminate. The baseline material, Fiberite 3501-6, exhibited cure shrinkage that was in accordance with expectations. Cure strains were {minus}4.5E-04. The YLA RS-3 material had cure strains somewhat lower at {minus}3.2E-04. The Fiberite 954-2A cure strain was {minus}1.5E-04 that is 70% lower than the baseline material. The glass fabric material with the Bryte BTCy-1 matrix did not result in meaningful results because the processing methods were not fully compatible with the material.

  12. CURING KINETICS AND PROPERTIES OF ACRYLIC RESIN CURED WITH AZIRIDINE CROSSLINKER

    Institute of Scientific and Technical Information of China (English)

    Fei Xie; Zong-hui Liu; De-qing Wei

    2002-01-01

    A kind of aziridine crosslinkers was synthesized and used to crosslink acrylate copolymers. The crosslinking properties and curing kinetics of the resin were studied. It was found that with the increase of the content of crosslinker in the emulsion, the mechanical properties and solvent resistance of the resin will be apparently improved, but its glass transition temperature (Tg) is very low. The lowest amount of crosslinker used in the acrylic resin emulsion is 0.25%. Curing kinetics studied by DSC show that this curing reaction occurs readily because the apparent activation energy of the reaction is low(65.1 KJ/mol). These results demonstrate that the aziridine crosslinker is indeed a low temperature crosslinking agent and can be used at room temperature.

  13. Experimental Study on the Curing Effect of Dredged Sediments with Three Types of Curing Agents

    Directory of Open Access Journals (Sweden)

    Yan Lei-Ming

    2016-01-01

    Full Text Available Sediment solidification technology is widely used to dispose dredged sediment, three types of curing agents were used in this study to solidified the dredged sediment from shallows in Nantong with three types of curing agents: JY, ZL and FJ. The results showed that the optimal additive amounts of these three curing agents were 140g JY, 16g ZL, 2.0g FJ per 1000g of the dredged sediment respectively, their 28d USC were up to 2.48 MPa, 2.96 MPa and 3.00 MPa. JY has obvious early strength effect, which of FJ is not that obvious, but the later-stage strength of sediment solidified by FJ are relatively higher.

  14. Curing Study of Epoxy/clay Nanocomposite by a New Aromatic Diamine Functional Curing Agent

    Directory of Open Access Journals (Sweden)

    Seyed Mahdi Saadati

    2013-12-01

    Full Text Available The curing behavior of an epoxy/clay nanocomposite system composed of diglycidyl ether of bisphenol A (DGEBA epoxy resin with a new aromatic diamine curing agent and organically modified clay was investigated. Epoxy/clay nanocomposite samples were prepared by mixing DGEBA, different percentages of nanoclay (1, 3, 5, 7, and 9% and 4-(4-(2,6-diphenylpyridin-4-ylphenoxybenzene-1,3-diamine (DAP. The optimum ratio of the epoxy/clay nanocomposite system (3% was investigated by total enthalpy of the curing reaction from differential scanning calorimetry (DSC thermograms. The kinetic parameters such as activation energy, pre-exponential factor, and rate constant were obtained from DSC data.

  15. Acid-base and surface energy characterization of grafted polyethylene using inverse gas chromatography.

    Science.gov (United States)

    Uhlmann, Petra; Schneider, Steffen

    2002-09-06

    For a specific design of interfaces, i.e. in composites and blends, it is essential to know the surface thermodynamics of the components. Polyethylene grafted with maleic anhydride and maleic anhydride-styrene mixtures, respectively, was the component of interest of our investigations. Inverse gas chromatography (IGC) at infinite dilution was shown to be an appropriate method to evaluate the dispersive and acid-base surface characteristics although there is an influence of bulk absorption and morphology when performing IGC above the glass transition temperature of the polymer.

  16. Degradation and contamination of perfluorinated sulfonic acid membrane due to swelling-dehydration cycles

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma; Morgen, Per; Skou, Eivind Morten

    Formation of sulfonic anhydride S-O-S (from the condensation of sulfonic acids) was known one of the important degradation mechanisms [i] for Nafion membrane under hydrothermal aging condition, which is especially critical for hydrogen fuel cells. Similar mechanism would also have be desirable...... to the membrane degradation in direct methanol fuel cells (DMFCs), where liquid water has direct contact with the electrolyte. An ex-situ experiment was established with swelling-dehydration cycles on the membrane. However, formation of sulfonic anhydride was not detected during the entire treatment; instead...

  17. 架空导线用碳纤维复合芯固化剂应用研究%Application of Curing Agent in Carbon Fiber Composite Core For Overhead Transmission Lines

    Institute of Scientific and Technical Information of China (English)

    何州文; 陈新; 药宁娜; 杨长龙; 陈懿夫

    2012-01-01

    A compound curing agent was prepared with methyl tetrahydrophthalic anhydride curing agent and a kind of flexible curing agent by a certain percentage for carbon fiber composite core epoxy matrix toughening. The structure of curing agent was studied by means of FTIR. The effects of the compound curing agent on impact strength, winding performance, apparent shear strength and temperature resistance of the carbon fiber composite core were investigated. The results showed that the flexible curing agent contained long-chain flexible segments, which could improve the impact strength, winding performance and apparent shear strength and had less effect on the temperature resistance for the carbon fiber composite core.%将甲基四氢苯酐固化剂与柔性固化剂按一定比例复配,用于碳纤维复合芯环氧树脂基体的增韧改性.采用傅里叶变换红外光谱分析固化剂的结构;研究了固化剂对碳纤维复合芯冲击强度、卷绕性能、剪切强度及耐温性的影响.结果表明,柔性固化剂含有长链结构的柔性链段,提高了碳纤维复合芯冲击强度、卷绕性能及表观剪切强度,并且对碳纤维复合芯的耐温性影响较小.

  18. 石灰对酸化黄壤整治烟田土壤酸度的影响及其应用效果%Influence of lime dosage on soil acidity of acidified yellow soil in renovated flue-cured tobacco field and application effects

    Institute of Scientific and Technical Information of China (English)

    朱经伟; 李志宏; 刘青丽; 梁永江; 黄纯扬; 霍沁建; 彭友; 夏昊; 张云贵

    2016-01-01

    phase was a stable stage presenting stable pH value, in which lime dosage and soil pH was significantly positively correlated and fitted to non-linear relationship. The field experiment showed that the trend of pH value varied with the amount of liming, which was basically consistent with results of incubation experiment. Combined with effects of soil pH value and flue-cured tobacco, ap-plying 1. 50 t/hm2 lime into ridges before transplanting period about 60 days was suitable for correcting acidity of yellow soil at the condition of pH value was about 5. 0.

  19. 石灰对酸化黄壤整治烟田土壤酸度的影响及其应用效果%Influence of lime dosage on soil acidity of acidified yellow soil in renovated flue-cured tobacco field and application effects

    Institute of Scientific and Technical Information of China (English)

    朱经伟; 李志宏; 刘青丽; 梁永江; 黄纯扬; 霍沁建; 彭友; 夏昊; 张云贵

    2016-01-01

    A series of laboratory and field experiments were conducted to study the effects of lime dosage on dynamic response of pH value, agronomic traits and economic traits of flue-cured tobacco in acidified yellow soil in renovated flue-cured tobacco field. The results showed that: the pH changes of acidified yellow soil were roughly divided into three phases according to the response characteristics of soil pH value to lime dosage in different periods during incubation course. The first phase was a rap-id changing stage, showing a sharp increase in soil pH value with relatively short duration. The second phase was a slowly changing stage which the direction of change, rate of change in soil pH value and duration period were affected by lime dosage. When the lime dosage was less than 3. 00 t/hm2 , the duration was about 60 days. When the lime dosage was more than 4. 50 t/hm2 , rate of pH change increased with increasing liming dosage and the duration was risen from 15 days to 30 days. The last phase was a stable stage presenting stable pH value, in which lime dosage and soil pH was significantly positively correlated and fitted to non-linear relationship. The field experiment showed that the trend of pH value varied with the amount of liming, which was basically consistent with results of incubation experiment. Combined with effects of soil pH value and flue-cured tobacco, ap-plying 1. 50 t/hm2 lime into ridges before transplanting period about 60 days was suitable for correcting acidity of yellow soil at the condition of pH value was about 5. 0.%采用室内培养试验和田间试验相结合的方法,研究土壤酸度对石灰施用量的动态响应规律,以及石灰施用量对烤烟农艺性状及经济性状的影响。结果表明:酸化黄壤在室内培养环境下对石灰的响应可分为3个阶段,即快速变化阶段,土壤pH值急剧升高,持续时间较短;缓慢变化阶段,土壤pH值的变化速度以及持续时间受石灰施用量

  20. Improving a self-curing dental resin by eliminating oxygen, hydroquinone and water from its curing process.

    Science.gov (United States)

    Keh, En-Sheng; Hayakawa, Iwao; Takahashi, Hidekazu; Watanabe, Akihiko; Iwasaki, Yasuhiko; Akiyoshi, Kazunari; Nakabayashi, Nobuo

    2002-12-01

    Self-curing dental resins are always manipulated in the presence of curing inhibitory factors such as oxygen, hydroquinone, water and another contaminants such as saliva and blood. The purpose of this study was to elucidate the effects of eliminating these curing inhibitory factors on resin properties. Several clinically relevant characteristics of an experimental resin cured in the absence of inhibitory factors (purified group) were determined and compared with the resin cured conventionally (control group). The purified group showed a significantly shorter induction period and higher reaction exotherm. It also showed significantly higher tensile strength and lower strain to failure. With regard to the amount of residual monomer, fracture toughness and fatigue strength the improvements were not significant. These findings suggest that the polymerization outcomes and mechanical properties of the purified group resin can be improved in general. Dental clinicians should pay attention to the storage and curing environments while manipulating the self-curing resin.

  1. 琥珀酸酐生产新工艺探讨%The Study of New Technology of Producing Amber Anhydride

    Institute of Scientific and Technical Information of China (English)

    吕杨

    2012-01-01

    It introduced the properties of Amber Anhydride and widely used in every field.Introducing the major technology of producing Amber Anhydride.Reviewing new tecnology of producing Amber Anhydride and comparing the major technology with new technology to explaining the superiority of new technology.%介绍了琥珀酸酐的性质及在各个领域的广泛用途,介绍了目前国内琥珀酸酐的主要生产工艺技术方案,综述了琥珀酸酐生产新技术,并对目前国内琥珀酸酐的主要生产工艺和琥珀酸酐生产新工艺进行了比较,突出了新工艺的优势。

  2. Nonfermentable, glucose-containing products formed from glucose under cellulose acid hydrolysis conditions

    Science.gov (United States)

    J. L. Minor

    1983-01-01

    Solutions of D-glucose in dilute sulfuric acid were allowed to react under time and temperature conditions which simulated the production of glucose from cellulose. Under these conditions, glucose undergoes a number of reactions including isomerization, dehydration, transglycosidation, polymerization, and anhydride formation. The specific interest in this report was to...

  3. Effect of Acid pH Condition on Biochemical Physiological Indices and Tissue Structure of Flue-cured Tobacco%酸性pH条件对烤烟生理指标及叶片组织结构的影响

    Institute of Scientific and Technical Information of China (English)

    朱英华; 屠乃美; 肖汉乾; 张国

    2011-01-01

    A pot experiment was carried out to evaluate the effects of different pH value on physiological indices and tissue structure of flue-cured tobacco Yunyan 85. The results showed SOD activities, palisade tissue/leaf tissue value, palisade tissue/sponge tissue value and proline contents in pH≥3.0 treatments increased with pH value decrease. Further decrease in pH value resulted in a decrease in these parameters. The change trend was an inverted "V"-type and pH 3.0 was their turning point POD activities in pH≤3.0 treatments were significantly higher than the control and pH≥3.5 treatments, but sponge tissue thickness in pH≤3.0 treatments were significantly lower than the control and pH≥3.5 treatments. Palisade tissue thickness increased from pH 5.6 to pH 3.5 and further decrease in acid pH resulted in significant decrease in the said parameters. Soluble protein contents pH≤3.0 treatments were significantly higher than the control and pH≥4.0 treatments, but they had no significant difference with pH 3.5 treatment Soluble sugar and leaf thickness were significantly decreased with pH value decrease. pH 3.0 could be the hazard threshold for flue-cured tobacco. Acid pH condition had no significant difference on the ratio of sponge tissue thickness/leaf thickness among the treatments. NR was very sensitive to acid pH condition, and NR activities in pH<4.5 treatment were significantly lower than the control.%以烤烟云烟85为供试材料,采用土培盆栽的方法研究了不同pH对烤烟叶片生理生化指标及叶片组织结构的影响.结果表明,pH≥3.0处理烤烟叶片的SOD活性、栅栏组织/叶厚、栅栏组织/海绵组织和脯氨酸含量随pH的降低而升高,而pH<3.0处理却随pH降低而降低,其变化趋势呈倒“V”型,pH3.0是其变化的转折点.pH≤3.0处理烤烟叶片的POD活性显著高于对照及pH≥3.5处理,而pH≤3.0处理烤烟叶片的海绵组织厚度则显著低于对照及pH≥3.5处理.烤烟叶片

  4. Lipolysis and lipid oxidation during processing of Chinese traditional smoke-cured bacon.

    Science.gov (United States)

    Huang, Yechuan; Li, Hongjun; Huang, Tian; Li, Feng; Sun, Juan

    2014-04-15

    Lipolysis and lipid oxidation as well as the relationship between them during processing of Chinese traditional smoke-cured bacon were studied by evaluating the changes in physicochemical parameters, lipase and lipoxygenase (LOX) activities, lipid content, fatty acid composition, peroxide value (POV), and thiobarbituric acid reactive substances (TBARS). Besides phospholipids, triacylglycerols (TAG) were an important source of free fatty acids in bacon, resulting in an increase in free fatty acid content in the mid-late stage of processing, whilst phospholipids hydrolysed intensely in the early stage. Preferential lipolysis was observed for polyunsaturated fatty acids in phospholipids and for linoleic and palmitic acids in TAG. The lipolysis of TAG and phospholipids was independent and catalysed by acid lipase and phospholipase, respectively. ANOVA-partial least squares regression (APLSR) analysis showed that POV and TBARS were poorly related to LOX and closely associated with phospholipid degradation. Therefore, autoxidation may be the main cause of muscle lipid oxidation in smoke-cured bacon, which was promoted by phospholipid hydrolysis.

  5. The cure for employee malaise--motivation.

    Science.gov (United States)

    Dawson, K M; Dawson, S N

    1991-01-01

    Although working conditions, hours, pay, and advancement opportunities are better now than in the 1950s--the "golden age" of American business--today's workers are significantly less satisfied. Why? The authors believe the cause of this malaise is lack of motivation. This article examines several techniques to cure employee malaise and discusses the long-term benefits of these techniques, which include empowerment, recognition, career development, the Pygmalion effect, incentives, and rewards. By making a commitment to these motivational techniques, managers will boost the morale and enthusiasm of their employees and their organization. This motivational process is not quick and easy; developing your employees is an ongoing process.

  6. Contribution of a selected fungal population to the volatile compounds on dry-cured ham.

    Science.gov (United States)

    Martín, Alberto; Córdoba, Juan J; Aranda, Emilio; Córdoba, M Guía; Asensio, Miguel A

    2006-07-01

    Dry-cured ham is obtained after several months of ripening. Different fungi strive on the surface, including toxigenic molds. Proteolysis and lipolysis by the endogenous and microbial enzymes seem to play a decisive role in the generation of flavor precursors in dry-cured meat products. In addition, fungi show a positive impact on the volatile compounds of ripened pork loins. However, the contribution of the fungal population to flavor formation in dry-cured ham remains unclear. One selected strain each of Penicillium chrysogenum and Debaryomyces hansenii was inoculated as starter cultures on dry-cured ham. Volatile compounds extracted by solid phase micro-extraction technique were analyzed by gas chromatography/mass spectrometry. A trained panel evaluated flavor and texture of fully ripened hams. The wild fungal population on non-inoculated control hams correlates with higher levels of short chain aliphatic carboxylic acids and their esters, branched carbonyls, branched alcohols, and some sulfur compounds, particularly at the outer muscle. Conversely, P. chrysogenum and D. hansenii seem to be responsible for higher levels of long chain aliphatic and branched hydrocarbons, furanones, long chain carboxylic acids and their esters. The very limited impact of P. chrysogenum on pyrazines in inoculated hams can be due to the activity of the yeast. Lower levels for some of the more volatile linear carbonyls at the ham surface suggest an anti-oxidant effect by micro-organisms. The differences in volatile compounds did not show a neat impact on flavor in the sensorial analysis. Nonetheless, inoculated hams got a better overall acceptability, which has to be attributed to their improved texture. The lower toughness of inoculated hams is a direct consequence of an early settling of a highly proteolytic mold. Thus, the use of selected fungi as starter cultures may be useful to obtain high-quality and safe dry-cured ham.

  7. Mechanical modeling of stress generation during cure of encapsulating resins

    Energy Technology Data Exchange (ETDEWEB)

    Lagasse, R.R.; Chambers, R.S.; Guess, T.R. (Sandia National Labs., Albuquerque, NM (USA)); Plazek, D.J.; Bero, C. (Pittsburgh Univ., PA (USA). Dept. of Materials Science and Engineering)

    1991-01-01

    We have developed a numerical model for calculating stresses generated during cure of shrinking encapsulating resins. Mechanical modeling of polymer encapsulated electronic devices usually focuses on stress generated during cooling after cure. The stress developed during cure, due to shrinkage of the encapsulant, is normally neglected. That assumption is valid if both the shear and bulk moduli of the encapsulant at the cure temperature are negligible with respect to the moduli at lower temperatures. Our measurements on a model epoxy encapsulant show that the shear modulus during cure, varying from 0 to 6 MPa, is at least 100 times smaller than that at ambient temperature. In contrast, the bulk modulus at the cure temperature is only 2.5 times smaller. Since the bulk modulus during cure cannot be neglected, significant stress can be produced if volume shrinkage is constrained by a stiff mold or embedded elements. In fact, mechanical failure of encapsulating materials during cure has been evident in some of our experiments. Using measurements of shear and bulk moduli plus volume shrinkage as inputs to a finite element model, we have successfully predicted the shrinkage strains and stresses developed during cure of a model epoxy resin inside a cylindrical tube. Consideration of cure shrinkage stress has led to a process modification that appears to reduce mechanical failures in a real encapsulated device. 6 refs., 6 figs.

  8. Critical parameters for electron beam curing of cationic epoxies and property comparison of electron beam cured cationic epoxies versus thermal cured resins and composites

    Energy Technology Data Exchange (ETDEWEB)

    Janke, C.J.; Norris, R.E.; Yarborough, K. [Oak Ridge National Lab., TN (United States). Oak Ridge Centers for Manufacturing Technology; Havens, S.J. [Oak Ridge Inst. for Science and Education, TN (United States); Lopata, V.J. [Atomic Energy of Canada Ltd., Pinawa, Manitoba (Canada). Whiteshell Labs.

    1997-01-16

    Electron beam curing of composites is a nonthermal, nonautoclave curing process offering the following advantages compared to conventional thermal curing: substantially reduced manufacturing costs and curing times; improvements in part quality and performance; reduced environmental and health concerns; and improvements in material handling. In 1994 a Cooperative Research and Development Agreement (CRADA), sponsored by the Department of Energy Defense Programs and 10 industrial partners, was established to advance electron beam curing of composites. The CRADA has successfully developed hundreds of new toughened and untoughened resins, offering unlimited formulation and processing flexibility. Several patent applications have been filed for this work. Composites made from these easily processable, low shrinkage material match the performance of thermal cured composites and exhibit: low void contents comparable to autoclave cured composites (less than 1%); superb low water absorption values in the same range as cyanate esters (less than 1%); glass transition temperatures rivaling those of polyimides (greater than 390 C); mechanical properties comparable to high performance, autoclave cured composites; and excellent property retention after cryogenic and thermal cycling. These materials have been used to manufacture many composite parts using various fabrication processes including hand lay-up, tow placement, filament winding, resin transfer molding and vacuum assisted resin transfer molding.

  9. Anhydride functionalised calcium ferrite nanoparticles: a new selective magnetic material for enrichment of lead ions from water and food samples.

    Science.gov (United States)

    Pirouz, Mojgan Jafari; Beyki, Mostafa Hossein; Shemirani, Farzaneh

    2015-03-01

    In this research a sonochemistry route for manufacture of uniform nanocrystalline CaFe2O4 and its anhydride functionalisation were reported. The potential of raw and modified material as a magnetically separable sorbent in selective enrichment of lead ions from water and food samples is outlined. This material was characterised using FT-IR, XRD, SEM and VSM techniques. The SEM and VSM results indicated that the calcium ferrite nanoparticles are sphere-like particles possessing superparamagnetic properties with an average diameter of 40 nm. Various analytical parameters, including pH, contact time, type and concentration of eluent, adsorption capacity, sample volume and interference of ions, were optimised. Following a modification by anhydride, calcium ferrite selectivity toward lead ions was raised more than twofold compared to the unmodified nanoparticles. Finally a pre-concentration procedure was applied for determination of trace Pb(II) in canned tuna fish, canned tomato paste, parsley, milk and well-water samples with satisfactory results.

  10. Increased oral bioavailability of paclitaxel by its encapsulation through complex formation with cyclodextrins in poly(anhydride) nanoparticles.

    Science.gov (United States)

    Agüeros, M; Zabaleta, V; Espuelas, S; Campanero, M A; Irache, J M

    2010-07-01

    The aim of this work was to study the oral bioavailability in rats of paclitaxel (PTX) when encapsulated as a complex with cyclodextrins in poly(anhydride) nanoparticles (NP). For this purpose three different cyclodextrins were selected: beta-cyclodextrin (CD), 2-hydroxypropyl-beta-cyclodextrin (HPCD) and 6-monodeoxy-6-monoamino-beta-cyclodextrin (NHCD). A single dose of 10mg paclitaxel per kg body weight as PTX-cyclodextrin nanoparticles was used. Plasma curves were characterised by a plateau of paclitaxel concentration close to the C(max) from T(max) till 24h post-administration. For PTX-CD NP and PTX-HPCD NP, these sustained levels of the anticancer drug were found to be between 27 and 33-fold higher than the reported value of drug activity whereas the relative oral bioavailability of paclitaxel was calculated to be higher than 80%. These facts would be directly related with a synergistic effect obtained by the combination of the bioadhesive properties of poly(anhydride) nanoparticles and the inhibitory effect of cyclodextrins on the activity of P-glycoprotein and cythocrome P450.

  11. Amphiphilic graft copolymer based on poly(styrene-co-maleic anhydride with low molecular weight polyethylenimine for efficient gene delivery

    Directory of Open Access Journals (Sweden)

    Duan XP

    2012-09-01

    Full Text Available Xiaopin Duan,1,2 Jisheng Xiao,2 Qi Yin,2 Zhiwen Zhang,2 Shirui Mao,1 Yaping Li21School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, 2Center of Pharmaceutics, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, ChinaBackground and methods: A new amphiphilic comb-shaped copolymer (SP was synthesized by conjugating poly(styrene-co-maleic anhydride with low molecular weight polyethyleneimine for gene delivery. Fourier transform infrared spectrum, 1H nuclear magnetic resonance, and gel permeation chromatography were used to characterize the graft copolymer.Results: The buffering capability of SP was similar to that of polyethyleneimine within the endosomal pH range. The copolymer could condense DNA effectively to form complexes with a positive charge (13–30 mV and a small particle size (130–200 nm at N/P ratios between 5 and 20, and protect DNA from degradation by DNase I. In addition, SP showed much lower cytotoxicity than polyethyleneimine 25,000. Importantly, the gene transfection activity and cellular uptake of SP-DNA complexes were all markedly higher than that of complexes of polyethyleneimine 25,000 and DNA in MCF-7 and MCF-7/ADR cell lines.Conclusion: This work highlights the promise of SP as a safe and efficient synthetic vector for DNA delivery.Keywords: poly(styrene-co-maleic anhydride, polyethylenimine, DNA, gene delivery

  12. Using maleic anhydride functionalized graphene oxide for improving the interfacial properties of carbon fiber/BMI composites

    Directory of Open Access Journals (Sweden)

    W. Li

    2016-11-01

    Full Text Available Maleic anhydride functionalized graphene oxide (MAH-GO was synthesized and then introduced into carbon fiber (CF reinforced bismaleimide (BMI composites, with the aim of improving the interfacial adhesion strength between CF and BMI resin. Various characterization techniques including Fourier transform infrared spectroscopy (FT-IR, X-ray photoelectron spectra (XPS and thermogravimetric analysis (TGA demonstrated that the maleic anhydride has been successfully grafted onto the GO surfaces. The study showed that the interlaminar shear strength (ILSS and flexural properties of CF/BMI composites were all improved by the incorporation of GO and MAH-GO, and the MAH-GO showed the substantially improved effect due to the strong interaction between the MAH-GO and the resin matrix. The maximum increment of the ILSS, flexural strength and flexural modulus of composites were 24.4, 28.7 and 49.7%, respectively. Scanning electron microscope (SEM photographs of the fracture surfaces revealed that the interfacial bonding between CF and resin matrix was significantly strengthened by the addition of MAH-GO. The results suggest that this feasible method may be an ideal substitute for the traditional method in the interfacial modification of composites.

  13. Development of novel melt-compounded starch-grafted polypropylene/polypropylene-grafted maleic anhydride/organoclay ternary hybrids

    Directory of Open Access Journals (Sweden)

    E. Lafranche

    2012-11-01

    Full Text Available Starch-grafted polypropylene (PP-g-starch/organoclay nanocomposites were melt-compounded using a corotating twin-screw extruder. Homopolymer or copolymer-based polypropylene-grafted maleic anhydrides (PP-g-MA with different molecular weights and different maleic anhydride (MA grafting levels were added at different weight contents as compatibilizer. Two organo-modified montmorillonites were used, the first one containing polar functional groups (Cloisite®30B having affinity to the starch phase, and the other one containing non polar-groups (Cloisite®20A having affinity to the polypropylene phase of the polymer matrix. Whatever the MA grafting level and the molecular weight and content of PP-g-MA, no significant immiscibility of PP-g-starch/PP-g-MA blends is evidenced. Regarding clay dispersion, adding a low content of ethylene-propylene copolymer-based PP-g-MA compatibilizer having a high MA-grafting level, and a polar organoclay (Cloisite®30B is the most desirable formulation to optimize clay intercalation and exfoliation in PP-g-starch. Nevertheless, regarding the reinforcement effect, whatever the PP-g-MA compatibilizer, the addition of non polar organoclay (Cloisite®20A is preferably recommended to reach higher tensile properties (modulus, yield stress, strength without significant loss of ductility.

  14. Bond strength of a resin cement to a cured composite inlay material.

    Science.gov (United States)

    Latta, M A; Barkmeier, W W

    1994-08-01

    Although resin cements have been effectively bonded to mineralized tooth structures, bonding to a cured composite material has remained a challenge. This study evaluated the shear bond strength of a resin cement bonded to a cured composite inlay material by use of a variety of composite surface treatments: (1) hydrofluoric acid/60 seconds, (2) ammonium bifluoride/60 seconds, (3) resin adhesive, (4) microabrasion with 50 microns aluminum oxide, and (5) microabrasion with 50 microns aluminum oxide and application of a resin adhesive. The resin cement was also bonded to human enamel that was etched with phosphoric acid. Scanning electron microscopy examinations were completed to evaluate the effects of the composite surface treatments. The results indicated that microabrasion of a cured composite enhances bonding of a resin cement. The bond strength of a resin cement to a composite surface that was air abraded with aluminum oxide, with or without the application of a resin adhesive, was higher than surface treatments with hydrofluoric acid or ammonium bifluoride. Scanning electron microscopy indicated that an irregular surface on the composite was created with aluminum oxide air abrasion.

  15. Thin-layer chromatography of hippuric and m-methylhippuric acid in urine after mixed exposure to toluene and xylene.

    OpenAIRE

    bieniek, G; Wilczok, T

    1981-01-01

    The separation of hippuric and m-methylhippuric acid as toluene and m-xylene metabolites present in urine of people exposed simultaneously to toluene and xylene is described. Chloroform was used for hippuric and m-methylhippuric acid extraction. Satisfactory separation of these metabolites was obtained on TLC plates covered with silica gels and developed in chloroform acetic acid-water (4:1:1);p-dimethylaminobenzaldehyde in acetic acid anhydride was applied to develop the colour. The sensitiv...

  16. Influence of curing protocol on selected properties of light-curing polymers

    DEFF Research Database (Denmark)

    Dewaele, Magali; Asmussen, Erik; Peutzfeldt, Anne;

    2009-01-01

    The purpose of this study was to investigate the effect of light-curing protocol on degree of conversion (DC), volume contraction (C), elastic modulus (E), and glass transition temperature (T(g)) as measured on a model polymer. It was a further aim to correlate the measured values with each other....

  17. Heavy metal content in flue cured and air cured tobaccos from main production areas in Serbia

    Directory of Open Access Journals (Sweden)

    Radojičić Vesna

    2004-01-01

    Full Text Available The aim of this work was to examine the influence of growing conditions on heavy metal content in virginia (flue cured and burley (air cured tobacco type. Moreover, some of these metals could appear in the tobacco cigarette smoke. This fact may cause negative consequences for cigarette consumers. Examinations were carried out in five various production areas, for each tobacco type, during two years, 1998 and 1999; those were extreme years for production.Considering the results, it can be concluded: The most important factor for heavy metal content in tobacco leaves are weather conditions especially the amount of rainfall, since there is a direct correlation between the rainfall and size of roots, a dominant vegetation organ. It is inevitable that the metals content in flue cured and air cured tobaccos grown at different experimental lots, is still below the legally prescribed values. Tobacco leaves from Šabac production area have a little higher metal content than tobacco grown in other production areas, because a larger amount of copper was found. The metal content in plants can increase because of its absorption from soil, atmosphere, or mineral fertilizers and pesticides, and, what is very important, the content of metals can be high due to the vicinity of large industrial centers.

  18. CURE: Clean use of reactor energy

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1990-05-01

    This paper presents the results of a joint Westinghouse Hanford Company (Westinghouse Hanford)-Pacific Northwest Laboratory (PNL) study that considered the feasibility of treating radioactive waste before disposal to reduce the inventory of long-lived radionuclides, making the waste more suitable for geologic disposal. The treatment considered here is one in which waste would be chemically separated so that long-lived radionuclides can be treated using specific processes appropriate for the nuclide. The technical feasibility of enhancing repository performance by this type of treatment is considered in this report. A joint Westinghouse Hanford-PNL study group developed a concept called the Clean Use of Reactor Energy (CURE), and evaluated the potential of current technology to reduce the long-lived radionuclide content in waste from the nuclear power industry. The CURE process consists of three components: chemical separation of elements that have significant quantities of long-lived radioisotopes in the waste, exposure in a neutron flux to transmute the radioisotopes to stable nuclides, and packaging of radionuclides that cannot be transmuted easily for storage or geologic disposal. 76 refs., 32 figs., 24 tabs.

  19. Radiation curing of carbon fibre composites

    Science.gov (United States)

    Spadaro, G.; Alessi, S.; Dispenza, C.; Sabatino, M. A.; Pitarresi, G.; Tumino, D.; Przbytniak, G.

    2014-01-01

    Epoxy/carbon fibre reinforced composites were produced by means of e-beam irradiation through a pulsed 10 MeV electron beam accelerator. The matrix consisted of a difunctional epoxy monomer (DGEBA) and an initiator of cationic polymerisation, while the reinforcement was a unidirectional high modulus carbon fibre fabric. Dynamic mechanical thermal analysis was carried out in order to determine the cross-linking degree. The analysis pointed out a nonuniformity in the cross-linking degree of the e-beam cured panels, with the formation of clusters at low Tg (glass transition temperature) and clusters at high Tg. An out-of-mould post irradiation thermal treatment on e-beam cured samples provides a higher uniformity in the network although some slight degradation effects. Mode I delamination fracture toughness and Interlaminar Shear Strength (ISS) were also investigated by means of Double Cantilever Beam (DCB) and Short Beam Shear tests, respectively. Results from this mechanical characterisation allowed to correlate fracture toughness of the bulk matrix resin, cross-linking density and fibre/matrix interaction to the delamination fracture behaviour of the fibre reinforced material.

  20. Out-of-Autoclave Cure Composites

    Science.gov (United States)

    Hayes, Brian S.

    2015-01-01

    As the size of aerospace composite parts exceeds that of even the largest autoclaves, the development of new out-of-autoclave processes and materials is necessary to ensure quality and performance. Many out-of-autoclave prepreg systems can produce high-quality composites initially; however, due to long layup times, the resin advancement commonly causes high void content and variations in fiber volume. Applied Poleramic, Inc. (API), developed an aerospace-grade benzoxazine matrix composite prepreg material that offers more than a year out-time at ambient conditions and provides exceptionally low void content when out-of-autoclave cured. When compared with aerospace epoxy prepreg systems, API's innovation offers significant improvements in terms of out-time at ambient temperature and the corresponding tack retention. The carbon fiber composites developed with the optimized matrix technology have significantly better mechanical performance in terms of hot-wet retention and compression when compared with aerospace epoxy matrices. These composites also offer an excellent overall balance of properties. This matrix system imparts very low cure shrinkage, low coefficient of thermal expansion, and low density when compared with most aerospace epoxy prepreg materials.

  1. Synthesis of the Biomimetic Polymer: Aliphatic Diamine and RGDS Modified Poly(d,l-lactic acid)

    Institute of Scientific and Technical Information of China (English)

    Xu Feng NIU; Yuan Liang WANG; Yan Feng LUO; Jun PAN; Juan Fang SHANG; Li Xia GUO

    2005-01-01

    A novel poly(d,l-lactic acid) (PDLLA) based biomimetic polymer was synthesized by grafting maleic anhydride, butanediamine and arg-gly-asp-ser (RGDS) peptides onto the backbone of PDLLA, aiming to overcome the acidity and auto-accelerating degradation of PDLLA during degradation and to improve its biospecificity and biocompatibility. The synthetic copolymer was characterized by FTIR, 13C NMR and amino acid analyzer (AAA).

  2. Production of cured meat color in nitrite-free Harbin red sausage by Lactobacillus fermentum fermentation.

    Science.gov (United States)

    Zhang, Xue; Kong, Baohua; Xiong, Youling L

    2007-12-01

    Lactobacillus fermentum was substituted for nitrite to produce cured pink color in a Chinese-style sausage. Treatments included inoculations (10(4), 10(6), and 10(8)CFU/g meat) followed by fermentation at 30°C for 8h and then at 4°C for 16h. Control sausage (with sodium nitrite, 60mg/kg meat) was cured at 4°C for 24h without L. fermentum. The UV-Vis spectra of pigment extract from L. fermentum-treated sausage were identical to that of nitrosylmyoglobin (NO-Mb) formed in nitrite-treated control. The NO-Mb concentration and the colorimetric a(∗) value of sausage treated with 10(8)CFU/g meat of L. fermentum essentially replicated those in nitrite-cured meat. Free amino acid content in sausage treated with L. fermentum was greater and the pH slightly lower compared with the nitrite-cured control sample. This study showed that L. fermentum has the potential to substitute for nitrite in the sausage production.

  3. Stability of α-tocotrienol and α-tocopherol in salami-type sausages and curing brine depending on nitrite and pH.

    Science.gov (United States)

    Gerling, Eva-Maria; Ternes, Waldemar

    2014-12-01

    We studied the stability of the valuable vitamer nutrients α-tocotrienol and α-tocopherol and options for their protection in salami-type sausages (blended with α-tocotrienol-rich barley oil) and curing brine. Four different sausage formulations were produced containing nitrite curing salt; nitrite curing salt and ascorbic acid (300mg/kg); nitrite curing salt and carnosic acid (45mg/kg); or sodium chloride. Initial vitamer contents (100mg/kg) did not decrease significantly during ripening and decreased only slightly during storage. Ascorbic acid and carnosic acid were found to be effective in preserving the vitamers in fresh sausages. Freeze-drying of sausages resulted in a significant loss of vitamers (97%), particularly after 14-day storage at room temperature, even in the presence of shielding gases. The vitamer content in the curing brine decreased with decreasing pH in the presence of nitrite. A nitrite concentration of 136mg/L at pH4 resulted in significant loss (90%) of the vitamers. Sufficient stability of the vitamers in salami-type sausage and curing brine can be achieved by processing, formulation, and storage conditions.

  4. In situ cure monitoring of advanced fiber reinforced composites

    Science.gov (United States)

    Powell, Graham R.; Crosby, Peter A.; Fernando, Gerard F.; France, Chris M.; Spooncer, Ronald C.; Waters, David N.

    1995-04-01

    This paper describes a comparative study of in-situ cure monitoring and cure modelling by three methods: (a) evanescent wave spectroscopy, (b) refractive index change, (c) near- infrared spectroscopy. Optical fibers were embedded into aerospace epoxy resins during the manufacturing process of the composite. The cure characteristics were then tracked in real- time during the processing of the material via evanescent wave interaction. This technique is based upon monitoring of characteristic infrared absorption bands of the resin system to find the concentration of the epoxy and amine hardener as a function of cure time. Hence this technique is suitable for on-line process monitoring and optimization. Results obtained from the optical fiber sensors were used to model the curing behavior of the resin system. The results were compared with near-infrared spectroscopy and differential scanning calorimetry experiments carried out under similar conditions. The feasibility of utilizing refractive index changes to monitor the extent of cure has also been demonstrated.

  5. Photoacoustic monitoring of inhomogeneous curing processes in polystyrene emulsions

    Energy Technology Data Exchange (ETDEWEB)

    Vargas-Luna, M.; Gutierrez-Juarez, G.; Rodriguez-Vizcaino, J.M.; Varela-Nsjera, J.B.; Rodriguez-Palencia, J.M.; Bernal-Alvarado, J.; Sosa, M. [Instituto de Fisica, Universidad de Guanajuato, Leon, Guanajuato (Mexico); Alvarado-Gil, J.J. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Merida, Antigua Carretera a Progreso, Merida, Yucatan (Mexico)

    2002-07-07

    The time evolution of the inhomogeneous curing process of polystyrene emulsions is studied using a variant of the conventional photoacoustic (PA) technique. The thermal effusivity, as a function of time, is determined in order to monitor the sintering process of a styrene emulsion in different steps of the manufacturing procedure. PA measurements of thermal effusivity show a sigmoidal growth as a function of time during the curing process. The parameterization of these curves permits the determination of the characteristic curing time and velocity of the process. A decreasing of the curing time and an increasing curing velocity for the final steps of the manufacturing process are observed. The feasibility of our approach and its potentiality for the characterization of other curing process are discussed. (author)

  6. Setting Reaction of Dental Resin-Modified Glass Ionomer Restoratives as a Function of Curing Depth and Postirradiation Time

    Directory of Open Access Journals (Sweden)

    Young Kyung Kim

    2015-01-01

    Full Text Available Specular reflectance Fourier transform infrared (SR-FTIR spectroscopy was used to study the setting reaction of dental resin-modified glass ionomer (RMGI restoratives as a function of curing depth and postirradiation time. Two light-cure and one tri-cure RMGI materials were selected and used according to the manufacturers’ instructions. Samples were prepared by filling the mixed materials into custom-made molds and then light-irradiating using a dental curing light. The degree of conversion and the extent of acid-base reaction of the materials at different depths (0, 1, 2, and 4 mm and postirradiation times (10 min, 1 day, and 7 days were determined using SR-FTIR spectroscopy in conjunction with the Kramers-Kronig (K-K transformation. The setting reaction was also investigated using microhardness measurements. The results showed that the depth of cure increased over time by the continuous acid-base reaction rather than photopolymerization or chemical polymerization. Microhardness tests seemed less suitable for studying the setting reaction as a function of postirradiation time, probably due to softening from the humidity. Analysis using specular reflectance in conjunction with the K-K algorithm was an easy and effective method for monitoring the setting reaction of dental RMGI materials.

  7. Process Formulations And Curing Conditions That Affect Saltstone Properties

    Energy Technology Data Exchange (ETDEWEB)

    Reigel, M. M.; Pickenheim, B. R.; Daniel, W. E.

    2012-09-28

    The first objective of this study was to analyze saltstone fresh properties to determine the feasibility of reducing the formulation water to premix (w/p) ratio while varying the amount of extra water and admixtures used during processing at the Saltstone Production Facility (SPF). The second part of this study was to provide information for understanding the impact of curing conditions (cure temperature, relative humidity (RH)) and processing formulation on the performance properties of cured saltstone.

  8. The curing process of layered silicate/epoxy nanocomposites

    OpenAIRE

    Nieminen, Ilkka

    2009-01-01

    The industrial methods of processing polymeric thermoset matrix nanocomposites require a good knowledge of the matrix curing process. The dispersion of nanoparticles in the matrix effects the curing process due to the interaction between nanoparticles and the matrix at the atomic level, especially when the nanoparticles have been treated with a surfactant agent ( alquilammonium) that is in competition with the reactive groups of the hardener. This thesis investigates the curing process o...

  9. Effect of IGF-II (insulin-like growth factor-II) genotype on the quality of dry-cured hams and shoulders.

    Science.gov (United States)

    Reina, Raquel; López-Buesa, Pascual; Sánchez del Pulgar, José; Ventanas, Jesús; García, Carmen

    2012-12-01

    The aim of this study was to investigate the effect of the paternal allele (homozygous AA and heterozygous AG) of the IGF-II gene on the fat content, fatty acid composition and sensory characteristics of dry-cured hams and shoulders. The effects were more evident in the subcutaneous fat thickness than in the intramuscular fat (IMF) content, and in the dry-cured hams rather than the dry-cured shoulders. Subcutaneous fat thickness was significantly higher in AG dry-cured hams and shoulders; however, IMF content was only significantly higher in AG dry-cured hams. These effects produce changes in fatty acid composition and sensory characteristics when comparing both batches of each product, but the behavior differed with the type of product. Sensory characteristics were similar in both batches of dry-cured hams in spite of the differences in IMF content. Nevertheless, AG dry-cured shoulders showed higher scores in most of the attributes evaluated, despite the IMF content being similar between batches.

  10. Reaction of Silane Alkoxide with Acid Anhydride as a Novel Synthetic Method for Organic-Inorganic Hybrid Materials

    Institute of Scientific and Technical Information of China (English)

    Masahiro Fujiwara

    2005-01-01

    @@ 1Introduction Sol-gel method is a potent method to produce new inorganic and organic-inorganic hybrid materials. The key step of this methodology is the hydrolysis of a metal alkoxide or other metal substrates such as acetylacetonates to form hydroxyl metal species, followed by their condensation to metal-oxygen-metal (M - O - M)bonds. In this process, the utilization of water, generally in excess, is essential and alcoholic solvents such as ethanol are often required to homogenize the solution when organic compounds coexist. As the common sol-gel method using water allows for limited uses of organic substrates due to their low solubility and stability in aqueous solution, modified variations of sol-gel method are required. Recently, some processes were reported for preparing metal oxides from metal alkoxides without the utilization of water.

  11. Relationship Between Color Parameters and Free Amino Acids and Biogenic Amines of Sliced Cooked Cured Beef Ham%西式蒸煮火腿切片货架期褪色与游离氨基酸和生物胺的关系

    Institute of Scientific and Technical Information of China (English)

    孙卫青; 周光宏; 徐幸莲

    2014-01-01

    Objective]Discoloration during storage is a key problem that limits the shelf-life of cooked cured meats. The purpose of the experiment is to study the relationship of color parameters and amino acids and biogenic amines of sliced cooked cured beef ham (SCCBH), to reveal the effects of the nitrogen compounds in meat products on the stability of the heme pigment and apparent color, in the hope of providing theoretical guidances for color protection of this type of products. [Method]Color parameters, free amino acids and biological amines of SCCH during storage were examined and factor analysis was used to explain the effect of free amino acids and biogenic amines on the color parameters. Principal component analysis (PCA) was used to extract the principal factor. Varimax orthogonal rotation with Kaiser normalization method was adopted in data analysis. [Result]Eight kinds of biogenic amines and 16 kinds of free amino acids were detected in this experiment. Biological amines showed no significant changes during storage, while, threonine (Thr), valine (Val), methionine (Met), lysine (Lys) and arginine (Arg) changed significantly. The factor analysis results showed that the first principal factor (F1) explained 45.72% of the total variation, and the second (F2) explained 21.52%. F1 was a concentrated reflection of color changes of SCCBH during storage, especially of the redness (a*), Chroma (C) and pigment NO-Heme (NH), and nitrogen compounds directly affecting the apparent color. F2 was mainly expressed the information of the hue and of the nitrogen compounds indirectly affecting apparent redness through the hue (H) or yellowness (b*), these nitrogen compounds mainly contained acidic and alkaline free amino acids. Tyramine (TYR) and spermine (SPM) significantly affected the stability of heme pigment and apparent color of SCCBH, which were shown by a high factor loading value (0.98) in F1. Further, TYR and SPM negatively correlated with the color parameters of SCCBH

  12. Curing Methods and Their Effects on The Strength of Concrete

    OpenAIRE

    Nuruddeen Usman; Muhammad Nura Isa

    2015-01-01

    There are a lot of arguments on which method of curing concrete gives good strength. These different opinions results into this study, which aim at investigating the effects of different curing methods on the strength of concrete. Laboratory test was employed for this study. Normal concretes were prepared using specified mix ratio of 1:2:4 and 1:3:6. The cubes tested for compressive strength at 3, 7, 21, and 28 days of curing respectively using four curing methods namely immersion...

  13. Optical fibre grating refractometers for resin cure monitoring

    Science.gov (United States)

    Buggy, S. J.; Chehura, E.; James, S. W.; Tatam, R. P.

    2007-06-01

    The use of fibre grating refractometers as a means of monitoring the cure of a UV-cured epoxy resin is presented. The wavelength shift of the attenuation bands of a long period grating and the spectral response of a tilted fibre Bragg grating sensor were measured simultaneously during the cure of the resin and compared with measurements made using a fibre optic Fresnel-based refractometer. The results showed a good correlation (6 × 10-3 rius) and illustrate the potential of the techniques for non-invasive composite material cure monitoring.

  14. Polyphenols, phytosterols, and reducing sugars in air-cured tobacco leaves injured by ozone air pollution

    Energy Technology Data Exchange (ETDEWEB)

    Menser, H.A.; Chaplin, J.F.; Cheng, A.L.S.; Sorokin, T.

    1977-03-13

    Air-cured tobacco (Nicotiana tabacum L.) leaves of several production types were analyzed chemically to determine the effects of ozone-induced weather fleck on polyphenols, phytosterols, and reducing sugars. Seven domestic cultivars provided leaf samples for analysis of polyphenols and phytosterols. Quantities of chlorogenic acid, rutin, scopoletin, free quinic acid, and phytosterols were higher in severely flecked leaves than in leaves flecked only minimally. Greenhouse studies disclosed that leaves grown in carbon-filtered air analyzed as greenpunch samples contained significantly higher levels of reducing sugars than leaves grown in polluted air, regardless of plant injury.

  15. Brane polarization is no cure for tachyons

    CERN Document Server

    Bena, Iosif

    2015-01-01

    Anti-M2 and anti-D3 branes placed in regions with charges dissolved in fluxes have a tachyon in their near-horizon region, which causes these branes to repel each other. If the branes are on the Coulomb branch this tachyon gives rise to a runaway behavior, but when the branes are polarized into five-branes this tachyon only appears to lower the energy of the polarized branes, without affecting its stability. We analyze brane polarization in the presence of a brane-brane-repelling tachyon and show that when the branes are polarized along the direction of the tachyon the polarized shell is unstable. This implies that tachyons cannot be cured by brane polarization and indicates that, at least in a certain regime of parameters, anti-D3 branes polarized into NS5 branes at the bottom of the Klebanov-Strassler solution have an instability.

  16. Ambient Cured Alkali Activated Flyash Masonry Units

    Science.gov (United States)

    Venugopal, K.; Radhakrishna; Sasalatti, Vinod M.

    2016-09-01

    Geopolymers belong to a category of non-conventional and non-Portland cement based cementitious binders which are produced using industrial by products like fly ash and ground granulated blast furnace slag (GGBFS). This paper reports on the development of geopolymer mortars for production of masonry units. The geopolymer mortars were prepared by mixing various by products with manufactured sand and a liquid mixture of sodium silicate and sodium hydroxide solutions. After curing at ambient conditions, the masonry units were tested for strength properties such as water absorption, initial rate of absorption, compression, shear- bond, and stress-strain behaviour etc. It was observed that the flexural strength of the blocks is more than 2 MPa and shear bond strength is more than 0.4MPa. It was found that the properties of geopolymer blocks were superior to the traditional masonry units. Hence they can be recommended for structural masonry.

  17. Helicobacter pylori: Basic Mechanisms to Clinical Cure

    Directory of Open Access Journals (Sweden)

    ABR Thomson

    1995-01-01

    Full Text Available Since its rediscovery 10 years ago, Helicobacter pylori has reshaped our thinking about the course of peptic ulcer disease. Our approach to the patient with a duodenal ulcer has become one of attempting eradication therapy at the time of first diagnosis, in the hope of curing the ulcer disease. Gastric and duodenal ulceration are only two of the manifestations of this chronic antral infection; other complications of H pylori include gastritis, gastric cancer and possible maltomas. Therapy of H pylori infection is complicated and involves dual therapy with an antibiotic plus a protein pump inhibitor, such as omeprazole 20 mg bid plus amoxicillin 1 g bid for two weeks, triple or quadruple therapy with bismuth, two antibiotics and an H2-receptor antagonist. Vaccination against H pylori is on the far horizon.

  18. Curing of epoxy matrix composite in stratosphere

    Science.gov (United States)

    Kondyurin, Alexey; Kondyurina, Irina; Bilek, Marcela

    Large structures for habitats, greenhouses, space bases, space factories are needed for next stage of space exploitation. A new approach enabling large-size constructions in space relies on the use of the polymerization technology of fiber-filled composites with a curable polymer matrix applied in the free space environment. The polymerisation process is proposed for the material exposed to high vacuum, dramatic temperature changes, space plasma, sun irradiation and atomic oxygen (in low Earth orbit), micrometeorite fluence, electric charging and microgravitation. The stratospheric flight experiments are directed to an investigation of the curing polymer matrix under the stratospheric conditions on. The unique combination of low atmospheric pressure, high intensity UV radiation including short wavelength UV and diurnal temperature variations associated with solar irradiation strongly influences the chemical processes in polymeric materials. The first flight experiment with uncured composites was a part of the NASA scientific balloon flight program realised at the NASA stratospheric balloon station in Alice Springs, Australia. A flight cassette installed on payload was lifted with a “zero-pressure” stratospheric balloon filled with Helium. Columbia Scientific Balloon Facility (CSBF) provided the launch, flight telemetry and landing of the balloon and payload. A cassette of uncured composite materials with an epoxy resin matrix was exposed 3 days in the stratosphere (40 km altitude). The second flight experiment was realised in South Australia in 2012, when the cassette was exposed in 27 km altitude. An analysis of the chemical structure of the composites showed, that the space irradiations are responsible for crosslinking of the uncured polymers exposed in the stratosphere. The first prepreg in the world was cured successfully in stratosphere. The investigations were supported by Alexander von Humboldt Foundation, NASA and RFBR (12-08-00970) grants.

  19. Stratospheric experiments on curing of composite materials

    Science.gov (United States)

    Chudinov, Viacheslav; Kondyurin, Alexey; Svistkov, Alexander L.; Efremov, Denis; Demin, Anton; Terpugov, Viktor; Rusakov, Sergey

    2016-07-01

    Future space exploration requires a large light-weight structure for habitats, greenhouses, space bases, space factories and other constructions. A new approach enabling large-size constructions in space relies on the use of the technology of polymerization of fiber-filled composites with a curable polymer matrix applied in the free space environment on Erath orbit. In orbit, the material is exposed to high vacuum, dramatic temperature changes, plasma of free space due to cosmic rays, sun irradiation and atomic oxygen (in low Earth orbit), micrometeorite fluence, electric charging and microgravitation. The development of appropriate polymer matrix composites requires an understanding of the chemical processes of polymer matrix curing under the specific free space conditions to be encountered. The goal of the stratospheric flight experiment is an investigation of the effect of the stratospheric conditions on the uncured polymer matrix of the composite material. The unique combination of low residual pressure, high intensity UV radiation including short-wave UV component, cosmic rays and other aspects associated with solar irradiation strongly influences the chemical processes in polymeric materials. We have done the stratospheric flight experiments with uncured composites (prepreg). A balloon with payload equipped with heater, temperature/pressure/irradiation sensors, microprocessor, carrying the samples of uncured prepreg has been launched to stratosphere of 25-30 km altitude. After the flight, the samples have been tested with FTIR, gel-fraction, tensile test and DMA. The effect of cosmic radiation has been observed. The composite was successfully cured during the stratospheric flight. The study was supported by RFBR grants 12-08-00970 and 14-08-96011.

  20. Greener Friedel-Crafts Acylation using Microwave-enhanced reactivity of Bismuth Triflate in the Friedel-Crafts Benzoylation of Aromatic Compounds with Benzoic Anhydride

    DEFF Research Database (Denmark)

    Tran, Phuong Hoang; Nguyen, hai Truong; Hansen, Poul Erik

    2017-01-01

    An efficient and facile bismuth trifluoromethanesulfonate-catalyzed benzoylation of aromatic compounds using benzoic anhydride under solvent-free microwave irradiation has been developed. The microwave-assisted Friedel-Crafts benzoylation results in good yields within short reaction times. Bismut...