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Sample records for diamine curing agents

  1. Diamine curing agents for polyurethanes

    NASA Technical Reports Server (NTRS)

    Bell, V. L.; St. Clair, T. L.

    1975-01-01

    Three aromatic diamines have properties that make them promising candidates as curing agents for converting isocyanates to polyurethanes with higher adhesive strengths, higher softening temperatures, better toughness, and improved abrasion resistance.

  2. Low toxicity aromatic diamine curing agents for adhesives

    SciTech Connect

    Dorsey, G.F.

    1993-08-24

    Increasing severity of regulations for handling of hazardous materials has led to formulation of adhesives with considerably lowered toxicities for use at the Oak Ridge Y-12 Plant. Fundamental was the development of Asilamine aromatic diamines, a family of liquid aromatic diamines useful as substitutes for methylenedianiline (MDA), a widely used adhesives curing agent. The use of Asilamine has allowed us to continue operations without dealing with expensive measures for regulation of MDA as a carcinogen promulgated by the Occupational Safety and Health Administration (OSHA).

  3. Use of 2,5-dimethyl-2,5-hexane diamine as a curing agent for epoxy resins. [Patent application

    DOEpatents

    Rinde, J.A.; Newey, H.A.

    Primary diamines are prepared for use as a curing agent for epoxy resins. These curing agents can be used to form epoxy resin mixtures useful in filament winding and preimpregnated fiber molding and in formulating film adhesives, powder coatings and molding powders. The epoxy mixtures form for such uses a room temperature non-reacting, intermediate stable state which has a latent cross-linking capability.

  4. Use of 2,5-dimethyl-2,5-hexane diamine as a curing agent for epoxy resins

    DOEpatents

    Rinde, James A. [Livermore, CA; Newey, Herbert A. [Lafayette, CA

    1981-02-24

    Primary diamines of the formula ##STR1## wherein R is a straight chain saturated hydrocarbon of 2 to 4 carbons, a disubstituted benzene ring, or disubstituted dibenzo methane for use as a curing agent for epoxy resins. These curing agents can be used to form epoxy resin mixtures useful in filament winding and pre-impregnated fiber molding and in formulating film adhesives, powder coatings and molding powders. The epoxy mixtures form for such uses as room temperature non-reacting, intermediate stable state which has a latent cross-linking capability.

  5. Use of 2,5-dimethyl-2,5-hexane diamine as a curing agent for epoxy resins

    DOEpatents

    Rinde, J.A.; Newey, H.A.

    1981-02-24

    Primary diamines are disclosed of the formula shown in a diagram wherein R is a straight chain saturated hydrocarbon of 2 to 4 carbons, a disubstituted benzene ring, or disubstituted dibenzomethane for use as a curing agent for epoxy resins. These curing agents can be used to form epoxy resin mixtures useful in filament winding and pre-impregnated fiber molding and in formulating film adhesives, powder coatings and molding powders. The epoxy mixtures form for such uses as room temperature non-reacting, intermediate stable state which has a latent cross-linking capability.

  6. Exploratory study on the effects of novel diamine curing agents and isocyanate precursors on the properties of new epoxy and urethane adhesives

    NASA Technical Reports Server (NTRS)

    Glasgow, D. G.

    1976-01-01

    The effects of novel aromatic diamine structures on the adhesive properties of epoxy and polyurethane adhesives were studied. Aromatic diamines based on benzophenone and diphenyl-methane isomers were evaluated as curing agents for epoxy resins and benzophenone and diphenyl-methane based diamine isomers were evaluated as curing agents for polyurethane adhesives. Polyurethane adhesives were prepared based on m, m prime-diisocyanato-diphenyl-methane and m, m prime-diisocyanato-benzophenone. The m, m prime-diisocayanato-diphenyl-methane based adhesive had properties comparable to state-of-the-art adhesives. The m, m prime-diisocyanato-benzophenone based adhesive was extremely reactive.

  7. Exploratory study on the effects of novel diamine curing agents and isocyanate precursors on the properties on new epoxy and urethane adhesives

    NASA Technical Reports Server (NTRS)

    Glasgow, D. G.; Garthwait, C.

    1977-01-01

    Aromatic diamines based on diphenyl sulfone and benzophenone were studied as epoxy adhesive curing agents. Previously found differences in adhesive strengths for meta vs para orientation were not found in these series. The use of aluminum and alumina as fillers in a m,m prime-methylene dianiline-cured epoxy adhesive was not found to be beneficial to adhesive strength. Alumina filled adhesives had much lower strength than unfilled adhesives. The unfilled m,m prime-methylene dianiline-based epoxy adhesive had excellent resistance to moisture relative to a p,p prime-methylene dianiline-based adhesive and maintained good strengths up to 250 F. A glass fiber composite based on a m,m prime-methylene dianiline-cured epoxy appeared to be equivalent to the p,p prime-methylene dianiline-cured epoxy as judged by short beam shear tests.

  8. Exploratory Study on the Effects of Novel Diamine Curing Agents and Isocyanate Precursors on the Properties of New Epoxy and Urethane Adhesives

    NASA Technical Reports Server (NTRS)

    Glasgow, D. Gerald; Garthwait, Clayborn

    1977-01-01

    This report covers the results of investigations directed toward studying the effects of novel aromatic diamine structures on epoxy adhesive properties and includes work done under a modification to the original contract. Three aromatic diamines based on diphenylsulfone and benzophenone were studied as epoxy adhesive curing agents. Previously found differences in adhesive strengths for meta vs para orientation were not found in these series. The use of aluminum and alumina as fillers in a m,m'-methylene dianiline-cured epoxy adhesive was not found to be beneficial to adhesive strength. Alumina filled adhesives had much lower strength than unfilled adhesives. The unfilled m,m'-methylene dianiline-based epoxy adhesive had excellent resistance to moisture relative to a p,p'-methylene dianiline-based adhesive and maintained good strengths up to 250 F. A glass fiber composite based on a m,m'-methylene dianiline-cured epoxy appeared to be equivalent to the p,p'-methylene dianiline-cured epoxy as judged by short beam shear tests.

  9. Ultrasonic mixing of epoxy curing agents

    NASA Technical Reports Server (NTRS)

    Hodges, W. T.; St.clair, T. L.

    1983-01-01

    A new technique for mixing solid curing agents into liquid epoxy resins using ultrasonic energy was developed. This procedure allows standard curing agents such as 4,4 prime-diaminodiphenyl sulfone (4,4 prime-DDS) and its 3,3 prime-isomer, (3,3 prime-DDS) to be mixed without prior melting of the curing agent. It also allows curing agents such as 4,4 prime-diaminodiphenyl sulfone (4,4 prime-DDS) and its 3,3 prime-isomer, (3,3 prime-DDS) to be mixed without prior melting of the curing agent. It also allows curing agents with very high melt temperatures such as 4,4 prime-diaminobenzophenone (4,4 prime-DABP) (242 C) to be mixed without premature curing. Four aromatic diamines were ultrasonically blended into MY-720 epoxy resin. These were 4,4 prime-DDS; 3,3 prime-DDA; 4,4 prime-DABP and 3,3 prime-DABP. Unfilled moldings were cast and cured for each system and their physical and mechanical properties compared.

  10. Epoxy foams using multiple resins and curing agents

    DOEpatents

    Russick, Edward M.; Rand, Peter B.

    2000-01-01

    An epoxy foam comprising a plurality of resins, a plurality of curing agents, at least one blowing agent, at least one surfactant and optionally at least one filler and the process for making. Preferred is an epoxy foam comprising two resins of different reactivities, two curing agents, a blowing agent, a surfactant, and a filler. According to the present invention, an epoxy foam is prepared with tailorable reactivity, exotherm, and pore size by a process of admixing a plurality of resins with a plurality of curing agents, a surfactant and blowing agent, whereby a foamable mixture is formed and heating said foamable mixture at a temperature greater than the boiling temperature of the blowing agent whereby said mixture is foamed and cured.

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

    NASA Technical Reports Server (NTRS)

    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.

  12. Synthesis of aminosilane and aromatic diamine intermediates for polymerization

    NASA Technical Reports Server (NTRS)

    Mcmanus, S. P.

    1982-01-01

    The preparation of monomers for use in a study to improve properties of epoxy polymers and silicone elastomers is described. Various approaches to the solution of the synthesis of aminosilane and diamine curing agents were examined. Ortho-, meta-, and para-substituted diamines where X is CH2, C(CH3)2, O, S, NH, or SO2 and n = 0, 1, 2, and 3 were investigated.

  13. Chiral trimethylsilylated C2-symmetrical diamines as phosphorous derivatizing agents for the determination of the enantiomeric excess of chiral alcohols by 1H NMR

    PubMed Central

    Chauvin, Anne-Sophie; Alexakis, Alexandre

    2006-01-01

    The use of organophosphorus derivatising agents, prepared from C2 symmetric trimethylsilylated diamines, for the 1H NMR and 31P NMR determination of the enantiomeric composition of chiral alcohols is described. PMID:16566844

  14. Developing the Manufacturing Process for Hylene MP Curing Agent

    SciTech Connect

    Eastwood, Eric

    2009-02-16

    This report details efforts to scale-up and re-establish the manufacturing process for the curing agent known as Hylene MP. First, small scale reactions were completed with varying conditions to determine key drivers for yielding high quality product. Once the optimum conditions were determined on the small scale, the scaled-up process conditions were determined. New equipment was incorporated into the manufacturing process to create a closed production system and improve chemical exposure controls and improve worker safety. A safe, efficient manufacturing process was developed to manufacture high quality Hylene MP in large quantities.

  15. Kinetic study of polymerization/curing of filament-wound composite epoxy resin systems with aromatic diamines

    NASA Technical Reports Server (NTRS)

    Golub, M. A.; Lerner, N. R.; Hsu, M. S.

    1986-01-01

    The kinetics of polymerization/curing of a filament-wound composite epoxy resin consisting of an 80/20 DGEBA/DGEBD blend and an MDA/m-PDA blend (Tonox 60/40) was studied at various temperatures and at amine epoxy ratios between 1.1 and 4.4 by means of Fourier-transform (FT) IR and bulk viscosity measurements. The activation energy for the polymerization/curing reaction using an amine/epoxy ratio of 1.1 was 11.9 kcal/mole, in agreement with a previous value. The FT-IR conversion-time plots were fitted to a kinetic expression containing two rate constants with activation energies of 13.7 and 10.0 kcal/mole. The bulk viscosity followed the Williams et al. (1955) equation, with a Di Benedetto (1965) expression for the glass transition temperature.

  16. Ethylene diamine

    Integrated Risk Information System (IRIS)

    Ethylene diamine ; CASRN 107 - 15 - 3 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  17. Influence of curing agent on fibrosis around silicone implants.

    PubMed

    Joseph, Josna; Mohanty, Mira

    2013-01-01

    Severe capsular contracture around silicone expander breast implants leading to pain and failure is a major clinical problem. Even though earlier studies have implicated the immunogenicity of silicone, the role of physical and chemical properties of the silicone material in excessive collagen deposition and fibrosis has been less addressed. The present study investigates whether there is any correlation between the type of curing systems i.e. addition and free radical curing and the fibrosis around silicone elastomer. The experiment carried out uses commercially available silicone ventriculo-peritoneal shunt material elastomer cured by platinum and the results are compared with results obtained in a similar study carried out by the authors using commercially available silicone tissue expander material cured by peroxide. Ultra-high molecular weight poly-ethylene (UHMWPE), the standard reference for biocompatibility evaluation, was used as the control material. The materials were implanted in rat skeletal muscle for 30 and 90 days. Inflammatory cells, myofibroblasts, cytokines, and collagen deposition at the material-tissue interface were identified by haematoxylin-eosin and Masson's Trichrome stains and semi-quantitated based on immunohistochemical studies. Results indicate that even though the cellular response in the initial phase of wound healing was similar in both platinum and peroxide-cured materials, the collagen deposition in the proliferative phase was more around peroxide-cured material in comparison to the platinum-cured silicone elastomer. There is a need to look into the molecular mechanisms of this interaction and the possibility of using curing systems other than free radical peroxide in the manufacture of silicone elastomer expanders for breast prosthesis.

  18. Diamines Containing Pendent Phenylethynyl Groups

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Smith, Joseph G., Jr. (Inventor); Hergenrother, Paul M. (Inventor)

    1997-01-01

    Controlled molecular weight imide oligomers and co-oligomers containing pendent phenylethynyl groups (PEPIs) and endcapped with nonreactive or phenylethynyl groups have been prepared by the cyclodehydration of the precursor amide acid oligomers or co-oligomers containing pendent phenylethynyl groups and endcapped with nonreactive or phenylethynyl groups. The amine terminated amide acid oligomers or co-oligomers are prepared from the reaction of dianhydride(s) with an excess of diamine(s) and diamine containing pendent phenylethynyl groups and subsequently endcapped with a phenylethynyl phthalic anhydride or monofunctional anhydride. The anhydride terminated amide acid oligomers and co-oligomers are prepared from the reaction of diamine(s) and diamine containing pendent phenylethynyl group(s) with an excess of dianhydride(s) and subsequently endcapped with a phenylethynyl amine or monofunctional amine. The polymerizations are carried out in polar aprotic solvents such as and N,N-dimethylacetamide under nitrogen at room temperature. The amide acid oligomers or co-oligomers are subsequently cyclodehydrated either thermally or chemically to the corresponding imide oligomers. The polymers and copolymers prepared from these materials exhibit a unique and unexpected combination of properties that includes higher glass transition temperatures after curing and higher retention of neat resin, adhesive and carbon fiber reinforced mechanical properties at temperatures up to 204 C under wet conditions without sacrificing melt flow behavior and processability as compared to similar materials. These materials are useful as adhesives, coatings, films, moldings, and composite matrices.

  19. Solvent permits solid curing agents to be used at room temperatures

    NASA Technical Reports Server (NTRS)

    St. Cyr, M. C.

    1967-01-01

    Solvent system dissolves the solid curing agents used with polyurethane resins in adhesive systems. The system developed yields bond strengths comparable to 100 percent solid formulations. The optimum solvent chosen was a 55.5 percent solution in anhydrous tetrahydrofuran.

  20. Effect of curing agent and temperature on the rheological behavior of epoxy resin systems.

    PubMed

    Zhao, Chenhui; Zhang, Guangcheng; Zhao, Lei

    2012-07-17

    The effect of curing agent (6610) content and temperature on the rheological behavior of the epoxy resin CYD-128 was studied by DSC analysis and viscosity experiments. The results show that the resin system meets the requirements of processing technology. A complete reaction occurs when the curing agent content (40 parts per hundred resin, phr) is a little higher than the theoretical value (33.33 phr), while the degree of reaction of the resin system is reduced when the curing agent content is lower (25.00 phr) than theoretical value. However, excessive curing agent (50.00 phr) results in a lower reaction rate. Curing agent content has little influence on gel time when curing agent content exceeded 33.33 phr and the temperature was less than 70 °C. The isothermal viscosity-time curves shift towards the -x axis when the temperature rises from 50 °C to 80 °C. Meanwhile, higher temperature results in higher reaction rates.

  1. Development of polyimide foams with blowing agents

    NASA Technical Reports Server (NTRS)

    Gagliani, John (Inventor); Sorathia, Usman A. K. (Inventor); Lee, Raymond (Inventor)

    1985-01-01

    A method of preparing a polyimide foam which includes the steps of: preparing, foaming, and curing a precursor containing at least one alkyl ester of 3,3'4,4'-benzophenonetetracarboxylic acid; a meta- or para-substituted aromatic diamine; a heterocyclic diamine; an aliphatic diamine; and a solid blowing agent. The blowing agent is added to said precursor in a concentration which is sufficient to effect at least one of the following attributes of the foam: cell size, proportion of open cells, cell density, and indentation load deflection.

  2. Health Problems of Epoxy Resins and Amine-curing Agents

    PubMed Central

    Bourne, L. B.; Milner, F. J. M.; Alberman, K. B.

    1959-01-01

    Epoxy resins were first introduced about 10 years ago. Toxic effects, particularly dermatitis, have been frequently described. An investigation into the possible causes of pathological sequelae following the use of epoxy resin/amine mixtures has been undertaken. The cause of most cases of dermatitis and sensitization appears to be uncombined amine which is present in recent mixtures and persists in hardened resin for long periods. The results of experiments with two of the most commonly used resin/amine mixtures confirm this. Cold-cured resins are more dangerous and remain so even when hardened. A simple theory is suggested for the mechanism of the reaction between epoxy resins, amines, and biological systems. This theory leads logically to the handling precautions outlined. Images PMID:13651551

  3. New structure of diamine curing agent for epoxy resins with self-restoration ability: Synthesis and spectroscopy characterization

    NASA Astrophysics Data System (ADS)

    Raimondo, Marialuigia; Guadagno, Liberata; Naddeo, Carlo; Longo, Pasquale; Mariconda, Annaluisa; Agovino, Anna

    2017-02-01

    The development of smart materials in aeronautical structures consisting of compounds based on epoxy resins having self-repair capability has been hampered by some criticalities. One of the main critical points is related to the impossibility to use primary amines (e.g.: 4,4‧-diaminodiphenyl sulfone, DDS) as hardeners, because they can poison the catalyst responsible for the healing mechanisms. In this paper, the synthesis, characterization and some tests of applicability of a new hardener, the tetramethylated diaminodiphenyl sulfone (tm-DDS), are shown. The tm-DDS is able to rapidly react with epoxy resin, giving a composite material having some characteristics significantly better than composites hardened with different tertiary amines. The new hardener is able to increase the glass transition temperature (Tg) of about 90 °C with respect to the more common hardener, ancamine K54, already used in self-healing epoxy formulations.

  4. Metal (2) 4,4',4",4'" phthalocyanine tetraamines as curing agents for epoxy resins

    NASA Technical Reports Server (NTRS)

    Achar, B. N.; Fohlen, G. M.; Parker, J. A. (Inventor)

    1985-01-01

    Metal, preferably divalent copper, cobalt or nickel, phthalocyanine tetraamines are used as curing agents for epoxides. The resulting copolymers have high thermal and chemical resistance and are homogeneous. They are useful as binders for laminates, e.g., graphite cloth laminate.

  5. Determination of the enantiomeric excess of chiral carboxylic acids by 31P NMR with phosphorylated derivatizing agents from C2-symmetrical diamines containing the (S)-alpha-phenylethyl group.

    PubMed

    Mastranzo, Virginia M; Quintero, Leticia; de Parrodi, Cecilia Anaya

    2007-06-01

    The use of P(III) and P(V) organophosphorus derivatizing agents prepared from C(2) symmetrical (1R,2R)- and (1S,2S)-trans-N,N'-bis-[(S)-alpha-phenylethyl]-cyclohexane-1,2-diamines 1 and 2, as well as (1R,2R)- and (1S,2S)-trans-N,N'-bis-[(S)-alpha-phenylethyl]-4-cyclohexene-1,2-diamines 3 and 4 for the determination of enantiomeric composition of chiral carboxylic acids by (31)P NMR, is described.

  6. Effects of Several Flame Retardants and Curing Agents on the Fire and Mechanical Properties of Epoxy Resin

    NASA Astrophysics Data System (ADS)

    Li, Pei; Min, Yang; Ban, Da-Ming

    2016-05-01

    Effect of different flame retardant (FR) and curing agent on the epoxy resin was investigated by limiting oxygen index (LOI), mechanical properties and FTIR. The results show that flame retardant effect of PODOPP is better than PSDPP. The curing agent order is: m-phenylenediamine>ethanediamine> polyethylene polyamine. The effect of flame retardant behaviors better when synergist OMMT was added.

  7. Citric acid and ethylene diamine tetra-acetic acid as effective washing agents to treat sewage sludge for agricultural reuse.

    PubMed

    Ren, Xianghao; Yan, Rui; Wang, Hong-Cheng; Kou, Ying-Ying; Chae, Kyu-Jung; Kim, In S; Park, Yong-Jin; Wang, Ai-Jie

    2015-12-01

    This paper presents the effects of different concentrations of citric acid (CA) and ethylene diamine tetra-acetic acid (EDTA) when used as additive reagents for the treatment of sewage sludge for agricultural use. Herein, both the retention of nutrients and removal of metals from the sewage sludge are examined. The average removal rate for the metals after treatment by CA decreased in the order Cu>Pb>Cd>Cr>Zn, while the rates after treatment by EDTA decreased in the order of Pb>Cu>Cr>Cd>Zn. After treatment with CA and EDTA, total nitrogen and total phosphorus concentrations in the sludge decreased, while the content of available nitrogen and Olsen-P increased. In addition, a multi-criteria analysis model-fuzzy analytic network process method (with 3 main factors and 12 assessment sub-factors) was adopted to evaluate the effectiveness of different treatment methods. The results showed that the optimal CA and EDTA concentrations for sewage sludge treatment were 0.60 and 0.125 mol/L, respectively.

  8. Involvement of monoamine oxidase and diamine oxidase in the metabolism of the cell differentiating agent hexamethylene bisacetamide (HMBA).

    PubMed

    Conley, B A; Callery, P S; Egorin, M J; Subramanyam, B; Geelhaar, L A; Pan, S S

    1988-01-01

    We have previously demonstrated a number of metabolites of hexamethylene bisacetamide (HMBA) in the urine of patients treated with HMBA. These include N-acetyl-1,6-diaminohexane (NADAH), 6-acetamidohexanoic acid (6AcHA), 1,6-diaminohexane (DAH) and 6-aminohexanoic acid (6AmHA). Because these compounds have potential roles in the dose-limiting metabolic acidosis and neurotoxicity associated with HMBA therapy, and are similar in structure to known substrates of monoamine oxidase (MAO) and diamine oxidase (DAO), we investigated the activities of these enzymes in the metabolic interconversion of HMBA metabolites. NADAH (5 mM) was incubated with MAO and aldehyde dehydrogenase. 6AcHA production was verified by gas chromatography-mass spectrometry and quantified by gas chromatography. 6AcHA production was linear for up to 4 hr. Complete inhibition of MAO activity was observed with 2 mM tranyl-cypromine or pargyline. Mouse liver microsomes, which do not contain MAO, did not convert NADAH to 6AcHA and, in control experiments, did not degrade 6AcHA. The HMBA metabolite, DAH, was a substrate for DAO, producing 3,4,5,6-tetrahydro-2H-azepine. Participation of DAO in the metabolism of HMBA implies potential interaction of HMBA and metabolites with polyamine metabolism and may represent a mechanism for HMBA's effects on cellular growth and differentiation. Metabolism of NADAH, also a differentiator, by MAO implies that concurrent use of HMBA and an MAO inhibitor may be clinically useful.

  9. Safe Deactivation of Energetic Materials and Use of By-products as Epoxy Curing Agents

    DTIC Science & Technology

    2001-11-01

    was investigated. The commercial, biosensor-based Microtox Toxicity system was used to test powders of epoxy samples prepared from a curing agent...Jeffamine”), which was first reacted with RDX and with TNT. The Microtox test is based upon the use of luminescent bacteria, which produce light as...correspondence from Darryl Sasaki, Sandia National Laboratories. 3) MicroTox Toxicity Testing Procedure, instrument manual, ToxScan, Inc

  10. Methods for direct alkene diamination, new & old

    PubMed Central

    de Jong, Sam; Nosal, Daniel G.; Wardrop, Duncan J.

    2012-01-01

    The 1,2-diamine moiety is a ubiquitous structural motif present in a wealth of natural products, including non-proteinogenic amino acids and numerous alkaloids, as well as in pharmaceutical agents, chiral ligands and organic reagents. The biological activity associated with many of these systems and their chemical utility in general has ensured that the development of methods for their preparation is of critical importance. While a wide range of strategies for the preparation of 1,2-diamines have been established, the diamination of alkenes offers a particularly direct and efficient means of accessing these systems. The purpose of this review is to provide an overview of all methods of direct alkene diamination, metal-mediated or otherwise. PMID:22888177

  11. Curing depth of a resin-modified glass ionomer and two resin-based luting agents.

    PubMed

    Sigemori, Ricardo Massao; Reis, André Figueiredo; Giannini, Marcelo; Paulillo, Luís Alexandre M S

    2005-01-01

    The degree of conversion of resin-based luting agents used for retention of prefabricated posts has been questioned due to the difficulty of light penetration into the resin-filled root canal. This study evaluated the depth of cure of a resin-modified glass ionomer cement (Rely X--3M ESPE) and two resin-based luting agents (Rely X ARC--3M ESPE and Enforce-Dentsply). Twenty-four 14x2x2mm3 specimens were prepared in a Teflon split mold with the three luting agents (n=8). After preparation, the specimens were stored at 37 degrees C in a dark box for 24 hours prior to microhardness testing. Measurements of Knoop hardness were performed at three different depths: superficial, medium and deep thirds. The results (KHN) were statistically analyzed by repeated measures ANOVA and Tukey test (0.05), which showed that resin-based luting agents presented the highest Knoop hardness values within the superficial third. Within the medium third, there were no significant differences among luting materials. However, within the deep third, Rely X presented the highest values. KHN values of resin-based luting agents decreased remarkably as depth increased.

  12. Fluorinated aromatic diamine

    NASA Technical Reports Server (NTRS)

    Jones, Robert J. (Inventor); O'Rell, Michael K. (Inventor); Hom, Jim M. (Inventor)

    1980-01-01

    This invention relates to a novel aromatic diamine and more particularly to the use of said diamine for the preparation of thermally stable high-molecular weight polymers including, for example, polyamides, polyamideimides, polyimides, and the like. This diamine is obtained by reacting a stoichometric amount of a disodium salt of 2,2-bis(4-hydroxyphenyl) hexafluoropropane with 4-chloronitrobenzene to obtain an intermediate, 2,2-bis[4-(4-nitrophenoxy)phenyl] hexafluoropropane, which is reduced to the corresponding 2,2-bis[4-(4-aminophenoxy)phenyl] hexafluoropropane.

  13. Evaluation of Adhesive Bonding of Lithium Disilicate Ceramic Material with Duel Cured Resin Luting Agents

    PubMed Central

    Gundawar, Sham M.; Radke, Usha M.

    2015-01-01

    Purpose: The purpose of this vitro study was to comparatively evaluate the adhesive bonding of dual cured resin luting agents with lithium disilicate ceramic material. Materials and Methods: Porcelain laminate veneers were prepared with lithium disilicate ceramic material i.e. IPS Empress II( E-Max Press). These laminates were bonded with RelyX ARC, Panavia F 2.0, Variolink II, Duolink and Nexus NX3.The porcelain laminates were etched with 9.6% hydrofluoric acid (Pulpdent Corporation) for one minute, washed for 15 sec with three way syringe and dried for 15 sec with air syringe. The silane (Ultradent) was applied with the help of applicator tip in a single coat and kept undisturbed for one minute. The prepared surfaces of the premolars were treated with 37% phosphoric acid (Prime dent) for 15 sec, thoroughly rinsed and dried as per manufactures instructions. The shear bond test was carried out on all samples with the Universal testing machine (Instron U.S.A.) The scanning electron microscopic study was performed at the fractured interface of representative samples from each group of luting agents. Result: In this study, the highest value of shear bond strength was obtained for NEXUS NX3 and the lowest for VARIOLINK II. Conclusion: The difference in bond strength can be interpreted as the difference in fracture resistance of luting agents, to which shearing load was applied during the shear bond strength test. It is inferred from this study that the composition of the luting agent determines the adhesive characteristics in addition to surface treatment and bonding surface area. PMID:25859514

  14. Novel Multifunctional Organic-Inorganic Hybrid Curing Agent with High Flame-Retardant Efficiency for Epoxy Resin.

    PubMed

    Tan, Yi; Shao, Zhu-Bao; Chen, Xue-Fang; Long, Jia-Wei; Chen, Li; Wang, Yu-Zhong

    2015-08-19

    A novel multifunctional organic-inorganic hybrid was designed and prepared based on ammonium polyphosphate (APP) by cation exchange with diethylenetriamine (DETA), abbreviated as DETA-APP. Then DETA-APP was used as flame-retardant curing agent for epoxy resin (EP). Curing behavior, including the curing kinetic parameters, was investigated by differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS). The flame retardance and burning behavior of DETA-APP cured EP were also evaluated. The limiting oxygen index (LOI) value of DETA-APP/EP was enhanced to 30.5% with only 15 wt % of DETA-APP incorporated; and the UL-94 V-0 rating could be easily passed through with only 10 wt % of the hybrid. Compared with DETA/EP, the peak-heat release rate (PHRR), total heat release (THR), total smoke production (TSP), and peak-smoke production release (SPR) of DETA-APP/EP (15 wt % addition), obtained from cone calorimetry, were dropped by 68.3, 79.3, 79.0, and 30.0%, respectively, suggesting excellent flame-retardant and smoke suppression efficiency. The flame-retardant mechanism of DETA-APP/EP has been investigated comprehensively. The results of all the aforementioned studies distinctly confirmed that DETA-APP was an effective flame-retardant curing agent for EP.

  15. The Effect of a Curing Agent and an Accelerator on the Glass Transition of Brominated and Unbrominated Diglycidyl Ether of Bisphenol A

    DTIC Science & Technology

    1998-03-01

    Dicyandiamide -a solid with a melting point of 209 deg C-is one of a unique group of curing agents that are insoluble in epoxy at room temperature. As...a curing agent for epoxy resins, dicyandiamide can react through all four nitrogen groups--reacting with the resin at both epoxide and hydroxyl sites

  16. Host-Targeting Agents to Prevent and Cure Hepatitis C Virus Infection

    PubMed Central

    Zeisel, Mirjam B.; Crouchet, Emilie; Baumert, Thomas F.; Schuster, Catherine

    2015-01-01

    Chronic hepatitis C virus (HCV) infection is a major cause of liver cirrhosis and hepatocellular carcinoma (HCC) which are leading indications of liver transplantation (LT). To date, there is no vaccine to prevent HCV infection and LT is invariably followed by infection of the liver graft. Within the past years, direct-acting antivirals (DAAs) have had a major impact on the management of chronic hepatitis C, which has become a curable disease in the majority of DAA-treated patients. In contrast to DAAs that target viral proteins, host-targeting agents (HTAs) interfere with cellular factors involved in the viral life cycle. By acting through a complementary mechanism of action and by exhibiting a generally higher barrier to resistance, HTAs offer a prospective option to prevent and treat viral resistance. Indeed, given their complementary mechanism of action, HTAs and DAAs can act in a synergistic manner to reduce viral loads. This review summarizes the different classes of HTAs against HCV infection that are in preclinical or clinical development and highlights their potential to prevent HCV infection, e.g., following LT, and to tailor combination treatments to cure chronic HCV infection. PMID:26540069

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

    NASA Technical Reports Server (NTRS)

    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.

  18. Evaluation of light curing units used for polymerization of orthodontic bonding agents.

    PubMed

    Oyama, Nanako; Komori, Akira; Nakahara, Rizako

    2004-12-01

    This study evaluated the light intensity of various light curing units, the effect of distance of the light guide, and the validity of a tapered light guide. Light curing units tested included (1) four blue light-emitting diode curing units, Lux-O-Max, LEDemetronl, Ortholux LED, and The Cure; (2) two tungsten-quartz halogen curing units, Optilux 501 and Co-bee; and (3) one plasma arc curing unit, Apollo95E. The Optilux 501 was also evaluated for combinations of normal mode and boost mode and Standard tip and Turbo tip light guide. The spectral output of each unit was measured from 300 to 600 nm with a spectroradiometer. The light intensities at distances of zero, five, 10, 15, and 20 mm were determined with the radiometer. The peak value of Ortholux LED and The Cure surpassed that of Apollo95E. The light intensity significantly decreased with distance. Although The Cure showed a higher light intensity than the LEDemetron1 at zero-mm distance, the light intensity of the LEDemetron1 was higher than that of The Cure at five to 20 mm, resulting in no significant difference. The boost mode increased light intensity at any distance. Although the Turbo tip enhanced light intensity at zero-mm distance, reduction of light intensity by Turbo tip was demonstrated at five- to 20-mm distance.

  19. Synthesis and evaluation of 5-(arylthio)-9H-pyrimido[4,5-b]indole-2,4-diamines as receptor tyrosine kinase and thymidylate synthase inhibitors and as antitumor agents.

    PubMed

    Zaware, Nilesh; Kisliuk, Roy; Bastian, Anja; Ihnat, Michael A; Gangjee, Aleem

    2017-04-01

    In an effort to optimize the structural requirements for combined cytostatic and cytotoxic effects in single agents, a series of 5-(arylthio)-9H-pyrimido[4,5-b]indole-2,4-diamines 3-7 were synthesized and evaluated as inhibitors of receptor tyrosine kinases (RTKs) as well as thymidylate synthase (TS). The synthesis of these compounds involved the nucleophilic displacement of the common intermediate 5-bromo/5-chloro-9H-pyrimido[4,5-b]indole-2,4-diamine with appropriate aryl thiols. A novel four step synthetic scheme to the common intermediate was developed which is more efficient relative to the previously reported six-step sequence. Biological evaluation of these compounds indicated dual activity in RTKs and human TS (hTS). In the VEGFR-2 assay, compound 5 was equipotent to the standard compound semaxanib and was better than standard TS inhibitor pemetrexed, in the hTS assay. Compounds 3, 6 and 7 were nanomolar inhibitors of hTS and were several fold better than pemetrexed.

  20. Effects of Metallo-Organic Decomposition Agents on Thermal Decomposition and Electrical Conductivity of Low-Temperature-Curing Silver Paste

    NASA Astrophysics Data System (ADS)

    Lu, Chun-An; Lin, Pang; Lin, Hong-Ching; Wang, Sea-Fue

    2006-09-01

    Six low-temperature-curing silver pastes were prepared from silver flake, α-terpineol and various metallo-organic decomposition (MOD) compounds. The thermal decomposition behaviors of the pastes were determined. The microstructures and resistivities of screen-printed films on alumina substrate after thermal treatment were characterized and discussed. Results indicated that 2-ethylhexanoate possesses the lowest decomposition temperature (190.3 °C) among the MOD agents studied, and it forms silver particles to promote the linking of silver flake powders and thus reduces the resistivity to <13 μΩ\\cdotcm at a temperature as low as 200 °C.

  1. Diamine-sulfuric acid reactions are a potent source of new particle formation

    NASA Astrophysics Data System (ADS)

    Jen, Coty N.; Bachman, Ryan; Zhao, Jun; McMurry, Peter H.; Hanson, David R.

    2016-01-01

    Atmospheric nucleation from sulfuric acid depends on the concentrations and the stabilizing effect of other trace gases, such as ammonia and amines. Diamines are an understudied class of atmospherically relevant compounds, and we examine how they affect sulfuric acid nucleation in both flow reactor experiments and the atmosphere. The number of particles produced from sulfuric acid and diamines in the flow reactor was equal to or greater than the number formed from monoamines, implying that diamines are more effective nucleating agents. Upper limits of diamine abundance were also monitored during three field campaigns: Lamont, OK (2013); Lewes, DE (2012); and Atlanta, GA (2009). Mixing ratios were measured as high as tens of parts per trillion by volume (GA and OK). Laboratory results suggest that diamines at these levels are important for atmospheric nucleation. Diamines likely participate in atmospheric nucleation and should be considered in nucleation measurements and models.

  2. Polyimides prepared from perfluoroisopropylidene diamine

    NASA Technical Reports Server (NTRS)

    Jones, Robert J. (Inventor); O'Rell, Michael K. (Inventor); Hom, Jim M. (Inventor)

    1978-01-01

    This invention relates to a novel aromatic diamine and more particularly to the use of said diamine for the preparation of thermally stable high-molecular weight polymers including, for example, polyamides, polyamideimides, polyimides, and the like. This diamine is obtained by reacting a stoichometric amount of a disodium salt of 2,2-bis(4-hydroxyphenyl) hexafluoropropane with 4-chloronitrobenzene to obtain an intermediate, 2,2-bis[4-(4-nitrophenoxy)phenyl] hexafluoropropane, which is reduced to the corresponding 2,2-bis[4-(4-aminophenoxy)phenyl] hexafluoropropane.

  3. Combining immunotherapy and anticancer agents: the right path to achieve cancer cure?

    PubMed

    Apetoh, L; Ladoire, S; Coukos, G; Ghiringhelli, F

    2015-09-01

    Recent clinical trials revealed the impressive efficacy of immunological checkpoint blockade in different types of metastatic cancers. Such data underscore that immunotherapy is one of the most promising strategies for cancer treatment. In addition, preclinical studies provide evidence that some cytotoxic drugs have the ability to stimulate the immune system, resulting in anti-tumor immune responses that contribute to clinical efficacy of these agents. These observations raise the hypothesis that the next step for cancer treatment is the combination of cytotoxic agents and immunotherapies. The present review aims to summarize the immune-mediated effects of chemotherapeutic agents and their clinical relevance, the biological and clinical features of immune checkpoint blockers and finally, the preclinical and clinical rationale for novel therapeutic strategies combining anticancer agents and immune checkpoint blockers.

  4. Synthesis of a Novel Phosphorus-Containing Flame Retardant Curing Agent and Its Application in Epoxy Resins.

    PubMed

    Zhang, Hongkun; Xu, Miaojun; Li, Bin

    2016-03-01

    A novel phosphorus-containing compound diphenyl-(2,5-dihydroxyphenyl)-phosphine oxide defined as DPDHPPO was synthesized and used as flame retardant and curing agent for epoxy resins (EP). The chemical structure was well characterized by Fourier transform infrared (FTIR) spectroscopy, 1H, 13C and 31P nuclear magnetic resonance. The flame retardant properties, combusting performances and thermal degradation behaviors of the cured epoxy resins were investigated by limiting oxygen index (LOI), vertical burning tests (UL-94), cone calorimeter and thermogravimetric analysis (TGA) tests. The morphologies and chemical compositions of char residues for cured epoxy resins were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The water resistant properties were evaluated by putting the samples into distilled water at 70 degrees C for 168 h. The results revealed that the EP/40 wt% DPDHPPO/60 wt% PDA thermosets successfully passed UL-94 V-0 flammability rating and the LOI value was as high as 31.9%. The cone tests results revealed that the incorporation of DPDHPPO efficiently reduced the combustion parameters of epoxy resins thermosets, such as heat release rate (HRR), total heat release (THR) and so on. The TGA results indicated that the introduction of DPDHPPO promoted epoxy resins matrix decomposed ahead of time compared with that of pure EP and led to a higher char yield and thermal stability at high temperature. The morphological structures and analysis of XPS of char residues revealed that DPDHPPO benefited to the formation of a sufficient, compact and homogeneous char layer with rich flame retardant elements on the epoxy resins materials surface during combustion. After water resistance tests, EP/40 wt% DPDHPPO/60 wt% PDA thermosets still remained excellent flame retardancy, the moisture absorption of epoxy resins thermosets decreased with the increase of DPDHPPO contents in the thermosets due to the existing

  5. Sofalcone, a mucoprotective agent, increases the cure rate of Helicobacter pylori infection when combined with rabeprazole, amoxicillin and clarithromycin

    PubMed Central

    Isomoto, Hajime; Furusu, Hisashi; Ohnita, Ken; Wen, Chun-Yang; Inoue, Kenichiro; Kohno, Shigeru

    2005-01-01

    AIM: The mucoprotective agents, sofalcone and polaprezinc have anti-Helicobacter pylori (H pylori) activities. We determined the therapeutic effects of sofalcone and polaprezinc when combined with rabeprazole, amoxicillin and clarithromycin for Helicobacter pylori infection. METHODS: One hundred and sixty-five consecutive outpatients with peptic ulcer and H pylori infection were randomly assigned to one of the following three groups and medicated for 7 d. Group A: triple therapy with rabeprazole (10 mg twice daily), clarithromycin (200 mg twice daily) and amoxicillin (750 mg twice daily). Group B: sofalcone (100 mg thrice daily) plus the triple therapy. Group C: polaprezinc (150 mg twice daily) plus the triple therapy. Eradication was considered successful if 13C-urea breath test was negative at least 4 wk after cessation of eradication regimens or successive famotidine in the cases of active peptic ulcer. RESULTS: On intention-to-treat basis, H pylori cure was achieved in 43 of 55 (78.2%) patients, 47 of 54 (87.0%) and 45 of 56 (80.4%) for the groups A, B and C respectively. Using per protocol analysis, the eradication rates were 81.1% (43/53), 94.0% (47/50) and 84.9% (45/53) respectively. There was a significant difference in the cure rates between group A and B. Adverse events occurred in 10, 12 and 11 patients, from groups A, B and C respectively, but the events were generally mild. CONCLUSION: The addition of sofalcone, but not polaprezinc, significantly increased the cure rate of H pylori infection when combined with the rabeprazole-amoxicillin-clarithromycin regimen. PMID:15786539

  6. Do blood contamination and haemostatic agents affect microtensile bond strength of dual cured resin cement to dentin?

    PubMed Central

    KİLİC, Kerem; ARSLAN, Soley; DEMETOGLU, Goknil Alkan; ZARARSIZ, Gokmen; KESİM, Bulent

    2013-01-01

    Objective: The purpose of this study was to evaluate the effects of blood contamination and haemostatic agents such as Ankaferd Blood Stopper (ABS) and hydrogen peroxide (H2O2) on the microtensile bond strength between dual cured resin cement-dentin interface. Material and Methods: Twelve pressed lithium disilicate glass ceramics were luted to flat occlusal dentin surfaces with Panavia F under the following conditions: Control Group: no contamination, Group Blood: blood contamination, Group ABS: ABS contamination Group H2O2: H2O2 contamination. The specimens were sectioned to the beams and microtensile testing was carried out. Failure modes were classified under stereomicroscope. Two specimens were randomly selected from each group, and SEM analyses were performed. Results: There were significant differences in microtensile bond strengths (µTBS) between the control and blood-contaminated groups (p<0.05), whereas there were no significant differences found between the control and the other groups (p>0.05). Conclusions: Contamination by blood of dentin surface prior to bonding reduced the bond strength between resin cement and the dentin. Ankaferd Blood Stoper and H2O2 could be used safely as blood stopping agents during cementation of all-ceramics to dentin to prevent bond failure due to blood contamination. PMID:23559118

  7. Influence of triallyl cyanurate as co-agent on gamma irradiation cured high density polyethylene/reclaimed tire rubber blend

    NASA Astrophysics Data System (ADS)

    Mali, Manoj N.; Arakh, Amar A.; Dubey, K. A.; Mhaske, S. T.

    2017-02-01

    Utilization of waste from tire industry as reclaimed tire rubber (RTR) by formation of blends with high density polyethylene (HDPE) is great area to be focused. Enhancement of properties by the addition of triallyl cyanurate (TAC) as a co-agent with 1%, 3% and 5% to blend of HDPE 50 wt% and RTR 50 wt% in presence of gamma irradiation curing were investigated. Specifically, mechanical and thermal properties were studied as a function of amount of TAC and gamma irradiation dose in range of 50-200 kGy. The resultant blends were evaluated for the values of impact strength, gel content, thermal stability, tensile properties, rheological properties and morphological properties with increasing irradiation dosage and TAC loading. The mechanical properties tensile strength, hardness, impact strength of blend containing 3% of TAC were substantially increased with increasing irradiation dosage up to 150 KGy. Rheological analysis has shown increase in viscosity with increase in TAC loading up to 3% and 150 KGy irradiation dosages. 3% loading of TAC lead to better set of properties with150 KGy gamma irradiation dosage.

  8. Edge-Selectively Functionalized Graphene-Like Platelets as a Co-curing Agent and a Nanoscale Additive to Epoxy Resin

    DTIC Science & Technology

    2012-08-12

    second method is where graphene can be grown using chemical vapor deposition (CVD) on a metal substrate18–20 or from single crystal silicon carbide...1 Final Report for AOARD Grant 114042 “Edge-selectively functionalized graphene -like platelets as a co-curing agent and a nanoscale additive...the role of a molecular wedge to exfoliate the AB-graphite into individual graphene and graphene -like platelets upon dispersion in polar solvents

  9. Synthesis of perfluoroalkylene aromatic diamines

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

  10. Application of a silver-olefin coordination polymer as a catalytic curing agent for self-healing epoxy polymers

    NASA Astrophysics Data System (ADS)

    Everitt, D. T.; Coope, T. S.; Trask, R. S.; Wass, D. F.; Bond, I. P.

    2015-05-01

    A silver-olefin based coordination polymer was prepared in a simple, one step process to act as an initiator to facilitate the ring-opening polymerization of epoxides. Thermal analysis found the complex to be capable of curing a range of commercially available epoxy resins used in the manufacture of conventional composite materials. Curing of the oligomeric diglycidyl ether bisphenol A resin, Epon 828, in combination with a non-toxic solvent, ethyl phenylacetate, was studied by differential scanning calorimetry. The mechanical characterization of the resultant cured polymers was conducted by single lap shear tests. Tapered double cantilever beam (TDCB) test specimens containing 2.5 pph of silver-olefin initiator, both with and without embedded microcapsules, were analyzed for their healing performance. Healing efficiency values were found to be strongly dependent on the applied healing temperature. A mean recovery of 74% fracture load was found in TDCB samples after being healed at 70 °C for 48 h.

  11. Acidic gas capture by diamines

    DOEpatents

    Rochelle, Gary; Hilliard, Marcus

    2011-05-10

    Compositions and methods related to the removal of acidic gas. In particular, the present disclosure relates to a composition and method for the removal of acidic gas from a gas mixture using a solvent comprising a diamine (e.g., piperazine) and carbon dioxide. One example of a method may involve a method for removing acidic gas comprising contacting a gas mixture having an acidic gas with a solvent, wherein the solvent comprises piperazine in an amount of from about 4 to about 20 moles/kg of water, and carbon dioxide in an amount of from about 0.3 to about 0.9 moles per mole of piperazine.

  12. Synthesis of aromatic secondary diamines

    NASA Technical Reports Server (NTRS)

    Wolfe, J. F.; Greenwood, T. D.; Kahley, R. A.

    1979-01-01

    A series of N-methyl substituted aromatic polyamides derived from the secondary aromatic diamines, 4,4'-bis(methylamino)diphenylmethane, 3,3'-bis(methylamino) diphenylmethane, 4,4'-bis(methylamino)benzophenone or 3,3'-bis(methylamino)benzophenone and isophthaloyl dichloride, terphthaloyl dichloride or 3,3'diphenylmethane dicarboxylic acid dichloride was prepared by high temperature solution polymerization in s-tetrachloroethane. Compared to analogous unsubstituted and partially N-methylated aromatic polyamides, the full N-methylated polyamides exhibited significantly lower glass transition temperatures, reduced crystallinity, improved thermal stability and good solubility in chlorinated solvents.

  13. Immediate dentin sealing of onlay preparations: thickness of pre-cured Dentin Bonding Agent and effect of surface cleaning.

    PubMed

    Stavridakis, Minos M; Krejci, Ivo; Magne, Pascal

    2005-01-01

    This study evaluated the thickness of Dentin Bonding Agent (DBA) used for "immediate dentin sealing" of onlay preparations prior to final impression making for indirect restorations. In addition, the amount of DBA that is removed when the adhesive surface is cleaned with polishing or air abrasion prior to final cementation was evaluated. For this purpose, a standardized onlay preparation was prepared in 12 extracted molars, and either OptiBond FL (Kerr) or Syntac Classic (Vivadent) was applied to half of the teeth and cured in the absence of oxygen (air blocking). Each tooth was bisected in a bucco-lingual direction into two sections, and the thickness of the DBA was measured under SEM on gold sputtered epoxy resin replicas at 11 positions. The DBA layer of each half tooth was treated with either air abrasion or polishing. The thickness of the DBAs was then re-measured on the replicas at the same positions. The results were statistically analyzed with non-parametric statistics (Mann-Whitney U test and Kruskal-Wallis test) at a confidence level of 95% (p=0.05). The film thickness of the DBA was not uniform across the adhesive interface (121.13 +/- 107.64 microm), and a great range of values was recorded (0 to 500 microm). Statistically significant differences (p<0.05) were noted, which were both material (OptiBond FL or Syntac Classic) and position (1 to 11) dependent. Syntac Classic presented a higher thickness of DBA (142.34 +/- 125.10 microm) than OptiBond FL (87.99 +/- 73.76 microm). The higher film thickness of both DBAs was at the deepest part of the isthmus (the most concave part of the preparation), while the lowest was at the line angles of the dentinal crest (the most convex part of the preparation). OptiBond FL presented a more uniform thickness around the dentinal crest of preparation; Syntac Classic pooled at the lower parts of the preparation. The amount of DBA that was removed with air abrasion or polishing was not uniform (11.94 +/- 16.46 microm

  14. Addition Polyimides from Non-Mutagenic Diamines

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  15. Radiation curing of epoxies

    NASA Astrophysics Data System (ADS)

    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.

  16. Antibacterial properties of a self-cured acrylic resin composed of a polymer coated with a silver-containing organic composite antibacterial agent.

    PubMed

    Kiriyama, Takashi; Kuroki, Kenjiro; Sasaki, Keisuke; Tomino, Masahumi; Asakura, Masaki; Kominami, Yoshiko; Takahashi, Yoshihumi; Kawai, Tatsushi

    2013-01-01

    A novel antibacterial polymer, coated with a silver-containing organic composite antibacterial agent, was dispersed in a self-cured acrylic resin. Residual viable cell count of each oral bacterial and fungal species cultivated on acrylic resin specimens containing the antibacterial polymer was significantly decreased when compared to those cultivated on specimens prepared from untreated polymer. A strong inverse correlation was found between the amount of eluted silver ions and the residual viable cell count of all species grown on the antibacterial polymer: the lower the viable cell count, the higher the amount of eluted silver ions. This clearly indicated the antibacterial activity of silver ions. As the content of organic composite antibacterial agent added to the polymer increased from 0.5% to 1.5% in 0.5% increments, amount of eluted silver ions significantly increased with each 0.5% increment to exert greater antibacterial effect.

  17. Comparative investigation of thermal and mechanical properties of cross-linked epoxy polymers with different curing agents by molecular dynamics simulation.

    PubMed

    Jeyranpour, F; Alahyarizadeh, Gh; Arab, B

    2015-11-01

    Molecular dynamics (MD) simulations were carried out to predict the thermal and mechanical properties of the cross-linked epoxy system composed of DGEBA resin and the curing agent TETA. To investigate the effects of curing agents, a comprehensive and comparative study was also performed on the thermal and mechanical properties of DGEBA/TETA and DGEBA/DETDA epoxy systems such as density, glass transition temperature (Tg), coefficient of thermal expansion (CTE) and elastic properties of different cross-linking densities and different temperatures. The results indicated that the glass transition temperature of DGEBA/TETA system calculated through density-temperature data, ∼ 385-395 °K, for the epoxy system with the cross-linking density of 62.5% has a better agreement with the experimental value (Tg, ∼ 400 °K) in comparison to the value calculated through the variation of cell volume in terms of temperature, 430-440 °K. They also indicated that CTE related parameters and elastic properties including Young, Bulk, and shear's moduli, and Poisson's ratio have a relative agreement with the experimental results. Comparison between the thermal and mechanical properties of epoxy systems of DGEBA/TETA and DGEBA/DETDA showed that the DGEBA/DETDA has a higher Tg in all cross linking densities than that of DGEBA/TETA, while higher mechanical properties was observed in the case of DGEBA/TETA in almost all cross linking densities.

  18. Effects of Laboratory Disinfecting Agents on Dimensional Stability of Three Commercially Available Heat-Cured Denture Acrylic Resins in India: An In-Vitro Study

    PubMed Central

    Jujare, Ravikanth Haridas; Varghese, Rana Kalappattil; Singh, Vishwa Deepak; Gaurav, Amit

    2016-01-01

    Introduction Dental professionals are exposed to a wide variety of microorganisms which calls for use of effective infection control procedures in the dental office and laboratories that can prevent cross-contamination that could extend to dentists, dental office staff, dental technicians as well as patients. This concern has led to a renewed interest in denture sterilization and disinfection. Heat polymerized dentures exhibit dimensional change during disinfection procedure. Aim The purpose of this study was to determine the influence of different types of widely used laboratory disinfecting agents on the dimensional stability of heat-cured denture acrylic resins and to compare the dimensional stability of three commercially available heat-cured denture acrylic resins in India. Materials and Methods Twelve specimens of uniform dimension each of three different brands namely Stellon, Trevalon and Acralyn-H were prepared using circular metal disc. Chemical disinfectants namely 2% alkaline glutaraldehyde, 1% povidone-iodine, 0.5% sodium hypochlorite and water as control group were used. Diameter of each specimen was measured before immersion and after immersion with time interval of 1 hour and 12 hours. The data was evaluated statistically using one way analysis of variance. Results All the specimens in three disinfectants and in water exhibited very small amount of linear expansion. Among three disinfectants, specimens in 2% alkaline glutaraldehyde exhibited least(0.005mm) and water showed highest (0.009mm) amount of dimensional change. Among resins, Trevalon showed least (0.067mm) and Acralyn-H exhibited highest (0.110mm) amount of dimensional change. Conclusion Although, all the specimens of three different brands of heat-cured denture acrylic resins exhibited increase in linear dimensional change in all the disinfectants and water, they were found to be statistically insignificant. PMID:27134996

  19. Rigid bifunctional chelating agents

    DOEpatents

    Sweet, M.P.; Mease, R.C.; Srivastava, S.C.

    1998-07-21

    Bicyclo[2.2.2] octane-2,3 diamine-N,N,N`,N`-tetraacetic acids (BODTA) and bicyclo[2.2.1] heptane-2,3 diamine-N,N,N`,N`-tetraacetic acid (BHDTA) are chelating agents useful in forming detectably labeled bioconjugate compounds for diagnostic and therapeutic purposes. New compounds and processes of forming BODTA and BHDTA are disclosed. Radioimmunoconjugates of the present invention show high and prolonged tumor uptake with low normal tissue uptakes.

  20. Rigid bifunctional chelating agents

    DOEpatents

    Sweet, Mark P.; Mease, Ronnie C.; Srivastava, Suresh C.

    1998-07-21

    Bicyclo›2.2.2! octane-2,3 diamine-N,N,N',N'-tetraacetic acids (BODTA) and bicyclo›2.2.1! heptane-2,3 diamine-N,N,N',N'-tetraacetic acid (BHDTA) are chelating agents useful in forming detectably labeled bioconjugate compounds for diagnostic and therapeutic purposes. New compounds and processes of forming BODTA and BHDTA are disclosed. Radioimmunoconjugates of the present invention show high and prolonged tumor uptake with low normal tissue uptakes.

  1. Rigid bifunctional chelating agents

    DOEpatents

    Sweet, Mark P.; Mease, Ronnie C.; Srivastava, Suresh C.

    2000-02-08

    Bicyclo[2.2.2]octane-2,3 diamine-N,N,N',N'-tetraacetic acids (BODTA) and bicyclo[2.2.1]heptane-2,3 diamine-N,N,N',N'-tetraacetic acid (BHDTA) are chelating agents useful in forming detectably labeled bioconjugate compounds for diagnostic and therapeutic purposes. New compounds and processes of forming BODTA and BHDTA are disclosed. Radioimmunoconjugates of the present invention show high and prolonged tumor uptake with low normal tissue uptakes.

  2. Gas chromatographic method for the determination of residual monomers, 2-(acryloyloxy)ethyl isocyanate and 2-(methacryloyloxy)ethyl isocyanate, as curing agents in an ultraviolet curable adhesive.

    PubMed

    Kim, Byoung-Hyoun; Kim, Nosun; Moon, Dong Cheul

    2014-02-01

    A gas chromatographic method is described for the determination of residual 2-(acryloyloxy)ethyl isocyanate (AOI) and 2-(methacryloyloxy)ethyl isocyanate (MOI) as curing agents in an ultraviolet curable adhesive. Pre-column derivatization was employed in the determination of AOI and MOI as a means of enhancing the response of the flame ionization detector. Urethane derivatives of AOI and MOI were derived using methanol for 30 min at room temperature. The accuracies (n = 5, three concentration levels) were in the range of 113.4 to 126.7%, and precisions (n = 5, three concentration levels) were in the range of 0.8 to 4.3% for AOI-OMe. Furthermore, the accuracies were in the range of 79.5 to 108.6% and the precisions were in the range of 1.0 to 2.4% for MOI-OMe. The correlation coefficients of six calibration standards were all greater than 0.9999 for AOI-OMe and greater than 0.9998 for MOI-OMe over the range from 10 to 100 µg/mL.

  3. Cure SMA

    MedlinePlus

    ... the SMA drug pipeline. Together, we're making real progress toward a treatment and a cure. Latest ... Announce SPINRAZA (nusinersen) Meets Primary Endpoint at Interim Analysis of Phase 3 CHERISH Study Biogen and Ionis ...

  4. Polyenamines from aromatic diacetylenic diketones and diamines

    NASA Technical Reports Server (NTRS)

    Hergenrother, Paul M. (Inventor); Bass, Robert G. (Inventor); Sinsky, Mark S. (Inventor); Connell, John W. (Inventor)

    1987-01-01

    The synthesis and characterization of several polyenamine ketones are discussed wherein conjugated diacetylenic diketones and aromatic diamines are used as a route to the formation of high molecular weight polyenamine ketones which exhibit good mechanical properties and can be cast into creasible films. Typical polymerization conditions involved the reaction of stoichiometric amounts of 1,4- or 1,3-PPPO and a diamine at 60 to 130 C in m-cresol at (w/w) solids content of 8 to 26% for a specified period of time under a nitrogen atmosphere. Novel polyenamine ketones were prepared with inherent viscosities as high as 1.99 dl/g and tough, clear amber films with tensile strengths of 12,400 psi and tensile moduli of 397,000 psi were cast from solutions of the polymers in chloroform. In most cases, the elemental analyses for the polyenamine ketones agree within + or - 0.3% of the theoretical values.

  5. Diamine Ligands in Copper-Catalyzed Reactions

    PubMed Central

    Surry, David S.

    2012-01-01

    The utility of copper-mediated cross-coupling reactions has been significantly increased by the development of mild reaction conditions and the ability to employ catalytic amounts of copper. The use of diamine-based ligands has been important in these advances and in this review we discuss these systems, including the choice of reaction conditions and applications in the synthesis of pharmaceuticals, natural products and designed materials. PMID:22384310

  6. The curing agent sodium nitrite, used in the production of fermented sausages, is less inhibiting to the bacteriocin-producing meat starter culture Lactobacillus curvatus LTH 1174 under anaerobic conditions.

    PubMed

    Verluyten, Jurgen; Messens, Winy; De Vuyst, Luc

    2003-07-01

    Curvacin A is a listericidal bacteriocin produced by Lactobacillus curvatus LTH 1174, a strain isolated from fermented sausage. The response of this strain to an added curing agent (sodium nitrite) in terms of cell growth and bacteriocin production was investigated in vitro by laboratory fermentations with modified MRS broth. The strain was highly sensitive to nitrite; even a concentration of 10 ppm of curing agent inhibited its growth and both volumetric and specific bacteriocin production. A meat simulation medium containing 5 ppm of sodium nitrite was tested to investigate the influence of the gas phase on the growth and bacteriocin production of L. curvatus LTH 1174. Aerating the culture during growth had no effect on biomass formation, but the oxidative stress caused a higher level of specific bacteriocin production and led to a metabolic shift toward acetic acid production. Anaerobic conditions, on the other hand, led to an increased biomass concentration and less growth inhibition. Also, higher maximum volumetric bacteriocin activities and a higher level of specific bacteriocin production were obtained in the presence of sodium nitrite than in fermentations under aerobic conditions or standard conditions of air supply. These results indicate that the inhibitory effect of the curing agent is at least partially masked under anaerobic conditions.

  7. High Tg and fast curing epoxy-based anisotropic conductive paste for electronic packaging

    NASA Astrophysics Data System (ADS)

    Keeratitham, Waralee; Somwangthanaroj, Anongnat

    2016-03-01

    Herein, our main objective is to prepare the fast curing epoxy system with high glass transition temperature (Tg) by incorporating the multifunctional epoxy resin into the mixture of diglycidyl ether of bisphenol A (DGEBA) as a major epoxy component and aromatic diamine as a hardener. Furthermore, the curing behavior as well as thermal and thermomechanical properties were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermomechanical analysis (TMA). It was found that Tg obtained from tan δ of DGEBA/aromatic diamine system increased from 100 °C to 205 °C with the presence of 30 percentage by weight of multifunctional epoxy resin. Additionally, the isothermal DSC results showed that the multifunctional epoxy resin can accelerate the curing reaction of DGEBA/aromatic diamine system. Namely, a high degree of curing (˜90%) was achieved after a few minutes of curing at low temperature of 130 °C, owing to a large number of epoxy ring of multifunctional epoxy resin towards the active hydrogen atoms of aromatic diamine.

  8. Plasmid curing of Oenococcus oeni.

    PubMed

    Mesas, Juan M; Rodríguez, M Carmen; Alegre, M Teresa

    2004-01-01

    Two strains of Oenococcus oeni, RS1 (which carries the plasmid pRS1) and RS2 (which carries the plasmids pRS2 and pRS3), were grown in the presence of different curing agents and at different temperatures. Sublethal temperature together with acriflavine generated all possible types of cured strains, i.e., lacking pRS1 (from strain RS1), and lacking pRS2, pRS3, or both (from strain RS2). Sublethal temperature together with acridine orange only generated cured strains lacking pRS3. These results suggest that acriflavine is a better curing agent than acridine orange for O. oeni, and that pRS3 is the most sensitive to these curing agents. We also observed spontaneous loss of pRS2 or both pRS2 and pRS3 by electroporation. The ability to cure O. oeni strains of plasmids provides a critical new tool for the genetic analysis and engineering of this commercially important bacterium.

  9. Antileishmanial Activity of a Series of N2,N4-Disubstituted Quinazoline-2,4-diamines

    PubMed Central

    2015-01-01

    A series of N2,N4-disubstituted quinazoline-2,4-diamines has been synthesized and tested against Leishmania donovani and L. amazonensis intracellular amastigotes. A structure–activity and structure–property relationship study was conducted in part using the Topliss operational scheme to identify new lead compounds. This study led to the identification of quinazolines with EC50 values in the single digit micromolar or high nanomolar range in addition to favorable physicochemical properties. Quinazoline 23 also displayed efficacy in a murine model of visceral leishmaniasis, reducing liver parasitemia by 37% when given by the intraperitoneal route at 15 mg kg–1 day–1 for 5 consecutive days. Their antileishmanial efficacy, ease of synthesis, and favorable physicochemical properties make the N2,N4-disubstituted quinazoline-2,4-diamine compound series a suitable platform for future development of antileishmanial agents. PMID:24874647

  10. 40 CFR 721.825 - Certain aromatic ether diamines.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Certain aromatic ether diamines. 721... Substances § 721.825 Certain aromatic ether diamines. (a) Chemical substances and significant new uses...,5-benzenetetracarboxylic acid, diethyl ester, compound with 4,4′- -2,5-diylbis(oxy)]bis (1:1) (PMN...

  11. 40 CFR 721.825 - Certain aromatic ether diamines.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Certain aromatic ether diamines. 721... Substances § 721.825 Certain aromatic ether diamines. (a) Chemical substances and significant new uses...,5-benzenetetracarboxylic acid, diethyl ester, compound with 4,4′- -2,5-diylbis(oxy)]bis (1:1) (PMN...

  12. 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.

    PubMed

    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.

  13. Why cure, why now?

    PubMed Central

    Kuritzkes, Daniel R

    2017-01-01

    Combination antiretroviral therapy (cART) is highly effective at preventing morbidity and mortality due to infection with human immunodeficiency virus (HIV), but does not eradicate the virus. Consequently, cART must be administered life-long. Recent progress has stimulated research towards a cure of HIV infection. Approaches under investigation include hematopoietic stem cell transplantation, latency reactivating agents, immune based therapies, and cell-based therapies. Each of these approaches carries potential risks that must be weighed against the availability of safe and effective cART. Balancing the risks and benefits of this research poses unique challenges to potential study participants, clinicians and investigators. PMID:27273887

  14. The Effect of Simplified Bonding Agents on the Bond Strength to Dentin of Self-Activated Dual-Cure Resin Cements

    DTIC Science & Technology

    2013-04-26

    barbituric acids , aromatic sulphonate amides and tert-butyl peroxymaleic acid in dental adhesive resin. J Polym Sci 1999;72:1655- 1668. Lee Ann...is the aim of this study to verify the accuracy of the claim so that clinicians can take advantage of its properties with the comfort of knowing it...the Incompatibilities between Simplified Dental Adhesives and Self-Cure Resin Cements……………..……30 I. Eliminate the Acid -Base Reaction…………..……………31

  15. Kinetics of pulpal temperature rise during light curing of 6 bonding agents from different generations, using light emitting diode and quartz-tungsten-halogen units: An in-vitro simulation

    PubMed Central

    Khaksaran, Najmeh Khatoon; Kashi, Tahereh Jafarzadeh; Rakhshan, Vahid; Zeynolabedin, Zahra Sadat; Bagheri, Hossein

    2015-01-01

    Background: Application of bonding agents (BA) into deep cavities and light curing them might increase pulpal temperature and threaten its health. The purpose of this study was to evaluate temperature rise of pulp by light curing six BA using two different light curing units (LCU), through a dent in wall of 0.5 mm. Materials and Methods: This in vitro experiment was carried out on 96 slices of the same number of human third molars (6 BAs × 2 LCUs × 8 specimens in each group). There were 6 groups of BAs: N Bond, G-Bond, OptiBond XTR, Clearfil SE, Adper Single Bond 2 and V Bond. Each group of BA (n = 16) had two subgroups of light emitting diode (LED) and quartz-tungsten-halogen light cure units (n = 8). Each of these 16 specimens were subjected to light emitting for 20 s, once without any BAs (control) and later when a BA was applied to surface of disk. Temperature rises in 140 s were evaluated. Their mean temperature change in first 20 s were calculated and analyzed using two-way repeated-measures and one-way analysis of variance (ANOVA) and Tukey (α = 0.05). Furthermore rate of temperature increase was calculated for each material and LCU. Results: Minimum and maximum temperature rises in all subgroups were 1.7 and 2.8°C, respectively. Repeated measures ANOVA showed that both of adhesive and LCU types had significant effect on temperature rise after application of adhesives. Tukey post-hoc analysis showed Clearfil SE showed significantly higher temperature rise in comparison with Adper Single bond 2 (P = 0.047) and N Bond (P = 0.038). Temperature rose in a linear fashion during first 30-40 s and after that it was non-linear. Conclusion: 20 s of light curing seems safe for pulpal health (with critical threshold of 5.5°C). However, in longer durations and especially when using LED units, the process should be broken to two sessions. PMID:25878684

  16. Vicinal Diamination of Alkenes under Rh-Catalysis

    PubMed Central

    2015-01-01

    The synthesis of 1,2-diamines has been achieved through a single-step, tandem sequence involving Rh-catalyzed aziridination followed by NaI-promoted rearrangement to an isomeric cyclic sulfamide. Facile ring opening of these products in hot water and pyridine affords differentially protected vicinal diamines. Demonstration of the utility of this method for the syntheses of (±)-enduracididine and (±)-allo-enduracididine is highlighted. PMID:25233140

  17. Preparation of polyimides from mixtures of monomeric diamines and esters of polycarboxylic acids

    NASA Technical Reports Server (NTRS)

    Serafini, T. T.; Delvigs, P.; Lightsey, G. R. (Inventor)

    1973-01-01

    Polyimides having high thermal and oxidative stability are prepared by the reaction of a mixture of monomers comprising (1) a dialkyl or tetraalkyl ester of an aromatic tetracarboxylic acid; (2) an aromatic diamine; and (3) a monoalkyl or dialkyl ester of a dicarboxylic acid where in the ratio of a:b:c is n:(n+1):2, wherein n has a value from 1 to 20. The mixture of monomers is prepared in a 30 to 70 percent by weight solution of an organic solvent, a substrate impregnated with the solution and heated at 50 to 205 C to remove said solvent and form a low molecular weight prepolymer, and thereafter heated at 275 to 350 C to cure to a high molecular weight polyimide.

  18. Dynamically cured thermoplastic olefin polymers

    SciTech Connect

    Hazelton, D.R.; Puydak, R.C.; Booth, D.A.

    1986-08-19

    A thermoplastic composition is described comprising a polyolefin resin, a first rubber component selected from the group consisting of polyisobutylene, and ethylene propylene copolymer (EPM) and EPDM and a second rubber component selected from the group consisting of halogenated butyl rubber and polychoroprene, the second rubber component being cured utilizing a curative other than a peroxide, which is a vulcanizing agent for the second rubber but not for the first rubber, the second rubber being cured to a fully vulcanized state by dynamic vulcanization in the presence of the polyolefin resin and first rubber compound.

  19. Structure-to-property relationships in addition cured polymers. 4: Correlations between thermo-oxidative weight losses of norbornenyl cured polyimide resins and their composites

    NASA Technical Reports Server (NTRS)

    Alston, William B.

    1992-01-01

    Relationships are identified between the thermo-oxidative stability (TOS) at 316 C of a wide variety of PMR (polymerization of monomeric reactants) addition cured polyimide resins and their corresponding graphite fiber composites. Weight loss results at 316 C confirmed the expected relationship of increasing aliphatic endcap content with decreasing TOS. Moreover, the resin TOS study also showed an unexpected linear correlation of decreasing weight loss to increasing ratio of benzylic diamine to aliphatic endcap in the range of the stoichiometries studied. Only after long term 316 C aging does the dianhydride used with the benzylic diamines become an additional factor in influencing the amount of PMR resin and composite weight losses. Also, the benzylic systems consistently showed much lower resin and composite weight losses at 316 C than the corresponding nonbenzylic norbornenyl resins and composites, except when the nonbenzylic diamine monomer does not contain a connecting group. Instead, this diamine resulted in a 316 C resin and composite weight loss that was only competitive with benzylic type diamines. Results show excellent correlation between TOS of all graphite fiber PMR composites and resins.

  20. Agents.

    PubMed

    Chambers, David W

    2002-01-01

    Although health care is inherently an economic activity, it is inadequately described as a market process. An alternative, grounded in organizational economic theory, is to view professionals and many others as agents, contracted to advance the best interests of their principals (patients). This view untangles some of the ethical conflicts in dentistry. It also helps identify major controllable costs in dentistry and suggests that dentists can act as a group to increase or decrease agency costs, primarily by controlling the bad actors who damage the value of all dentists.

  1. Improved cure method for single component silicone rubber

    NASA Technical Reports Server (NTRS)

    Lippitt, M. W.

    1969-01-01

    Water is incorporated in a carrier and then thoroughly mixed with the single component silicone rubber containing acetic anhydride as a curing agent. Because curing occurs with the water supplied internally, controlled curing is possible within a reasonable period of time, regardless of the thickness of the material.

  2. Optimal Composite Curing System

    NASA Astrophysics Data System (ADS)

    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.

  3. The structure and inhibition of human diamine oxidase†,‡

    PubMed Central

    McGrath, Aaron P; Hilmer, Kimberly M; Collyer, Charles A; Shepard, Eric M; Elmore, Bradley O.; Brown, Doreen E; Dooley, David M; Guss, J Mitchell

    2009-01-01

    Humans have three functioning genes that code for copper-containing amine oxidases. The product of the AOC1 gene is a so-called diamine oxidase (hDAO), named for its substrate preference for diamines, particularly histamine. hDAO has been cloned and expressed in insect cells and the structure of the native enzyme determined by X-ray crystallography to a resolution of 1.8 Å. The homodimeric structure has the archetypal amine oxidase fold. Two active sites, one in each subunit, are characterized by the presence of a copper ion and a topaquinone residue formed by the post-translational modification of a tyrosine. Although hDAO shares 37.9 % sequence identity with another human copper amine oxidase, semicarbazide sensitive amine oxidase or vascular adhesion protein-1, its substrate binding pocket and entry channel are distinctly different in accord with the different substrate specificities. The structures of two inhibitor complexes of hDAO, berenil and pentamidine, have been refined to resolutions of 2.1 Å and 2.2 Å, respectively. They bind non-covalently in the active site channel. The inhibitor binding suggests that an aspartic acid residue, conserved in all diamine oxidases but absent from other amine oxidases, is responsible for the diamine specificity by interacting with the second amino group of preferred diamine substrates. PMID:19764817

  4. Renewable rigid diamines: efficient, stereospecific synthesis of high purity isohexide diamines.

    PubMed

    Thiyagarajan, Shanmugam; Gootjes, Linda; Vogelzang, Willem; van Haveren, Jacco; Lutz, Martin; van Es, Daan S

    2011-12-16

    We report an efficient three-step strategy for synthesizing rigid, chiral isohexide diamines derived from 1,4:3,6-dianhydrohexitols. These biobased chiral building blocks are presently the subject of several investigations (in our and several other groups) because of their application in high-performance biobased polymers, such as polyamides and polyurethanes. Among the three possible stereo-isomers, dideoxy-diamino isoidide and dideoxy-diamino isosorbide can be synthesized from isomannide and isosorbide respectively in high yield with absolute stereo control. Furthermore, by using this methodology dideoxy-amino isomannide-a tricyclic adduct-was obtained starting from isoidide in high yield. Our improved synthetic route is a valuable advance towards meeting scale and purity demands for evaluating the properties of new biobased performance materials, which will benefit the development of these plastics.

  5. 40 CFR 721.10309 - Ethoxylated, propoxylated diamine diaryl substituted phenylmethane ester with alkenylsuccinate...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... diaryl substituted phenylmethane ester with alkenylsuccinate (generic). 721.10309 Section 721.10309... Ethoxylated, propoxylated diamine diaryl substituted phenylmethane ester with alkenylsuccinate (generic). (a... generically as ethoxylated, propoxylated diamine diaryl substituted phenylmethane ester with...

  6. 40 CFR 721.2582 - Reaction product of alkylene diamine, MDl, substituted carbomonocyclic amine and alkylamine...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Reaction product of alkylene diamine... Reaction product of alkylene diamine, MDl, substituted carbomonocyclic amine and alkylamine (generic). (a... generically as reaction product of alkylene diamine, MDl, substituted carbomonocyclic amine and...

  7. 40 CFR 721.2582 - Reaction product of alkylene diamine, MDl, substituted carbomonocyclic amine and alkylamine...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Reaction product of alkylene diamine... Reaction product of alkylene diamine, MDl, substituted carbomonocyclic amine and alkylamine (generic). (a... generically as reaction product of alkylene diamine, MDl, substituted carbomonocyclic amine and...

  8. 40 CFR 721.2582 - Reaction product of alkylene diamine, MDl, substituted carbomonocyclic amine and alkylamine...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Reaction product of alkylene diamine... Reaction product of alkylene diamine, MDl, substituted carbomonocyclic amine and alkylamine (generic). (a... generically as reaction product of alkylene diamine, MDl, substituted carbomonocyclic amine and...

  9. 40 CFR 721.2582 - Reaction product of alkylene diamine, MDl, substituted carbomonocyclic amine and alkylamine...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Reaction product of alkylene diamine... Reaction product of alkylene diamine, MDl, substituted carbomonocyclic amine and alkylamine (generic). (a... generically as reaction product of alkylene diamine, MDl, substituted carbomonocyclic amine and...

  10. 40 CFR 721.2582 - Reaction product of alkylene diamine, MDl, substituted carbomonocyclic amine and alkylamine...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Reaction product of alkylene diamine... Reaction product of alkylene diamine, MDl, substituted carbomonocyclic amine and alkylamine (generic). (a... generically as reaction product of alkylene diamine, MDl, substituted carbomonocyclic amine and...

  11. CNS-specific regulatory elements in brain-derived HIV-1 strains affect responses to latency-reversing agents with implications for cure strategies

    PubMed Central

    Gray, L R; Cowley, D; Welsh, C; Lu, H K; Brew, B J; Lewin, S R; Wesselingh, S L; Gorry, P R; Churchill, M J

    2016-01-01

    Latency-reversing agents (LRAs), including histone deacetylase inhibitors (HDACi), are being investigated as a strategy to eliminate latency in HIV-infected patients on suppressive antiretroviral therapy. The effectiveness of LRAs in activating latent infection in HIV strains derived from the central nervous system (CNS) is unknown. Here we show that CNS-derived HIV-1 strains possess polymorphisms within and surrounding the Sp transcription factor motifs in the long terminal repeat (LTR). These polymorphisms result in decreased ability of the transcription factor specificity protein 1 to bind CNS-derived LTRs, reducing the transcriptional activity of CNS-derived viruses. These mutations result in CNS-derived viruses being less responsive to activation by the HDACi panobinostat and romidepsin compared with lymphoid-derived viruses from the same subjects. Our findings suggest that HIV-1 strains residing in the CNS have unique transcriptional regulatory mechanisms, which impact the regulation of latency, the consideration of which is essential for the development of HIV-1 eradication strategies. PMID:26303660

  12. Carbon dioxide insertion into diamines: a computational study of solvent effects.

    PubMed

    Eger, Wilhelm A; Genest, Alexander; Rieger, Bernhard; Rösch, Notker

    2012-10-01

    We studied computationally, on the model compound ethylenediamine, the insertion of carbon dioxide into diamines, yielding cyclic urea compounds. Two mechanisms were elaborated, depending on the value of the dielectric constant (DC) of the solvent. Accordingly, reaction mixtures with a high DC lead to carbamates, whereas lower DC values result in the preferred product cyclic urea. Additives behaving as "proton shuttles" act as catalysts, significantly reducing the activation barriers of insertion and ring closure to surmountable values. CO(2) insertion into diamines may also occur by autocatalysis, even without further additives, but under less favorable conditions, for example, lower yields. Amine reagents are most efficient at proton shuttling, followed by alcohols. The activation barrier of the rate-limiting step is lowered in a reaction mixture with higher values of DC, up to a critical value ε(cr) ≈ 18. Hence, in a suitably optimized reaction mixture, ring closure is suggested to occur under milder conditions than those previously applied experimentally. The two roles of the additive, that is, acting as proton shuttling agent and adjusting the effective DC of the reaction mixture, do not have to be assigned to a single compound, possibly affording a handle on process optimization.

  13. Testing Penetration of Epoxy Resin and Diamine Hardeners through Protective Glove and Clothing Materials.

    PubMed

    Henriks-Eckerman, Maj-Len; Mäkelä, Erja A; Suuronen, Katri

    2015-10-01

    Efficient, comfortable, yet affordable personal protective equipment (PPE) is needed to decrease the high incidence of allergic contact dermatitis arising from epoxy resin systems (ERSs) in industrial countries. The aim of this study was to find affordable, user-friendly glove and clothing materials that provide adequate skin protection against splashes and during the short contact with ERS that often occurs before full cure. We studied the penetration of epoxy resin and diamine hardeners through 12 glove or clothing materials using a newly developed test method. The tests were carried out with two ERS test mixtures that had a high content of epoxy resin and frequently used diamine hardeners of different molar masses. A drop (50 µl) of test mixture was placed on the outer surface of the glove/clothing material, which had a piece of Fixomull tape or Harmony protection sheet attached to the inner surface as the collection medium. The test times were 10 and 30 min. The collecting material was removed after the test was finished and immersed into acetone. The amounts of diglycidyl ether of bisphenol A (DGEBA), isophorone diamine (IPDA), and m-xylylenediamine (XDA) in the acetone solution were determined by gas chromatography with mass spectrometric detection. The limit for acceptable penetration of XDA, IPDA, and DGEBA through glove materials was set at 2 µg cm(-2). Penetration through the glove materials was 1.4 µg cm(-2) or less. The three tested chemical protective gloves showed no detectable penetration (<0.5 µg cm(-2)). Several affordable glove and clothing materials were found to provide adequate protection during short contact with ERS, in the form of, for example, disposable gloves or clothing materials suitable for aprons and as additional protective layers on the most exposed parts of clothing, such as the front of the legs and thighs and under the forearms. Every ERS combination in use should be tested separately to find the best skin protection material

  14. RECRYSTALLIZATION OF PMDA AND SYNTHESIS OF AN ACETYLENIC DIAMINE

    SciTech Connect

    Sanner, R; Cook, R C

    2004-09-21

    This memo provides documentation for the method of recrystallization of pyromeletic dianhydride (PMDA), the dianhydride used in the vapor deposition of Kapton-like polyimide for ICF shell ablators and for the synthesis of bis(3-aminophenyl) acetylene, a unique acetylenic diamine developed for vapor deposition testing.

  15. Rhodium complexes bearing tetradentate diamine-bis(phenolate) ligands

    SciTech Connect

    Liu, Xiang Y; Lokare, Kapil S; Ganesh, Somesh K; Gonzales, Jason M; Oxgaard, Jonas; Goddard, William A; Periana, Roy A

    2011-01-01

    Using tetradentate, dianionic ligands, several new rhodium complexes have been prepared. Some of these diamine-bis(phenolate) compounds, are active for C–H activation of benzene. These complexes are air and thermally stable. All four complexes were characterized by X-ray diffraction.

  16. MICROWAVE-ASSISTED PREPARATION OF CYCLIC UREAS FROM DIAMINES

    EPA Science Inventory

    Rajender S. Varma* and Yong-Jin Kim
    Cyclic ureas are useful intermediates for a variety of pharmaceuticals and pesticides. One of the attractive approaches for the synthesis of cyclic ureas uses condensation of diamines with urea as a carbonyl source under dynamic evacuation. ...

  17. Determination of Ethane-1,2-diamine in Inert Complexes.

    ERIC Educational Resources Information Center

    Searle, Graeme H.

    1985-01-01

    Describes a procedure for determining ethane-1,2-diamine (EN) which is generally applicable for inert or labile complexes or for EN in its salts, although it cannot be used directly with ammonium or coordinated ammonia. It gives results with five percent accuracy or better and requires less than one hour laboratory time. (JN)

  18. Aromatic/aliphatic diamine derivatives for advanced compositions and polymers

    NASA Technical Reports Server (NTRS)

    Delozier, Donovan M. (Inventor); Watson, Kent A. (Inventor); Connell, John W. (Inventor); Smith, Jr., Joseph G. (Inventor)

    2010-01-01

    Novel compositions of matter comprise certain derivatives of 9,9-dialkyl fluorene diamine (AFDA). The resultant compositions, whether compositions of matter or monomers that are subsequently incorporated into a polymer, are unique and useful in a variety of applications. Useful applications of AFDA-based material include heavy ion radiation shielding components and components of optical and electronic devices.

  19. Highly Enantioselective Direct Synthesis of Endocyclic Vicinal Diamines through Chiral Ru(diamine)-Catalyzed Hydrogenation of 2,2'-Bisquinoline Derivatives.

    PubMed

    Ma, Wenpeng; Zhang, Jianwei; Xu, Cong; Chen, Fei; He, Yan-Mei; Fan, Qing-Hua

    2016-10-04

    An asymmetric hydrogenation of 2,2'-bisquinoline and bisquinoxaline derivatives, catalyzed by chiral cationic ruthenium diamine complexes, was developed. A broad range of chiral endocyclic vicinal diamines were obtained in high yields with excellent diastereo- and enantioselectivity (up to 93:7 dl/meso and >99 % ee). These chiral diamines could be easily transformed into a new class of chiral N-heterocyclic carbenes (NHCs), which are important but difficult to access.

  20. Differential expression on mitochondrial tryparedoxin peroxidase (mTcTXNPx) in Trypanosoma cruzi after ferrocenyl diamine hydrochlorides treatments.

    PubMed

    Kohatsu, Andréa A N; Silva, Flávia A J; Francisco, Acácio I; Rimoldi, Aline; Silva, Marco T A; Vargas, Maria D; Rosa, João A da; Cicarelli, Regina M B

    Resistance to benznidazole in certain strains of Trypanosoma cruzi may be caused by the increased production of enzymes that act on the oxidative metabolism, such as mitochondrial tryparedoxin peroxidase which catalyses the reduction of peroxides. This work presents cytotoxicity assays performed with ferrocenyl diamine hydrochlorides in six different strains of T. cruzi epimastigote forms (Y, Bolivia, SI1, SI8, QMII, and SIGR3). The last four strains have been recently isolated from triatominae and mammalian host (domestic cat). The expression of mitochondrial tryparedoxin peroxidase was analyzed by the Western blotting technique using polyclonal antibody anti mitochondrial tryparedoxin peroxidase obtained from a rabbit immunized with the mitochondrial tryparedoxin peroxidase recombinant protein. All the tested ferrocenyl diamine hydrochlorides were more cytotoxic than benznidazole. The expression of the 25.5kDa polypeptide of mitochondrial tryparedoxin peroxidase did not increase in strains that were more resistant to the ferrocenyl compounds (SI8 and SIGR3). In addition, a 58kDa polypeptide was also recognized in all strains. Ferrocenyl diamine hydrochlorides showed trypanocidal activity and the expression of 25.5kDa mitochondrial tryparedoxin peroxidase is not necessarily increased in some T. cruzi strains. Most likely, other mechanisms, in addition to the over expression of this antioxidative enzyme, should be involved in the escape of parasites from cytotoxic oxidant agents.

  1. Isotopically sensitive regioselectivity in the oxidative deamination of a homologous series of diamines catalyzed by diamine oxidase.

    PubMed

    Callery, P S; Subramanyam, B; Yuan, Z M; Pou, S; Geelhaar, L A; Reynolds, K A

    1992-11-30

    The equivalence of aminomethylene groups in selected diamine substrates of diamine oxidase was exploited for the determination of intramolecular isotope effects. In the series of substrates, [1,1-2H2]-1,3-diaminopropane, [1,1-2H2]-1,5-diaminopentane, [1,1-2H2]-1,6-diaminohexane, [1,1-2H2]-1,7-diaminoheptane and [alpha,alpha-2H2]-4-(aminomethyl)benzylamine, the preference of the enzyme for reaction at the unlabeled methylene was found to vary from 1.45 to 10.5-fold. The observed partitioning ratios go through a minimum value with 1,5-diaminopentane, the best substrate of diamine oxidase of the compounds tested. The results suggest that fast substrates have less opportunity to reorient into alternate binding conformations while bound to the active site of the enzyme. On the other hand, diamine substrates tested that cannot exist in energetically favorable conformations with internitrogen distances of about 7-8 A showed larger intramolecular isotope effects.

  2. N2-Trimethylacetyl substituted and unsubstituted-N4-phenylsubstituted-6-(2-pyridin-2-ylethyl)-7H-pyrrolo[2,3-d]pyrimidine-2,4-diamines: Design, cellular receptor tyrosine kinase inhibitory activities and in vivo evaluation as antiangiogenic, antimetastatic and antitumor agents

    PubMed Central

    Gangjee, Aleem; Namjoshi, Ojas A.; Yu, Jianming; Ihnat, Michael A.; Thorpe, Jessica E.; Bailey-Downs, Lora C.

    2013-01-01

    Six novel N4-phenylsubstituted-6-(2-pyridin-2-ylethyl)-7H-pyrrolo[2,3-d]pyrimidine-2,4-diamines and their N2-trimethylacetyl substituted analogs were synthesized as receptor tyrosine kinase (RTK) inhibitors. A microwave-mediated Sonogashira reaction was used as a key step for the synthesis of these compounds. Biological evaluation, in whole cell assays, showed that some analogs had remarkable inhibitory activity against a variety of RTKs and in particular cytotoxic activity against A431 tumor cells in culture. The inhibitory data against RTKs in this study demonstrated that variation of the 4-anilino substituents of thse analogs dictates both potency and specificity of inhibitory activity against various RTKs. The study also supported the hypothesis that interaction of substituents on the 2-amino group with hydrophobic site-II provides an increase in potency. Compound 8 of this series was selected for evaluation in vivo in a B16-F10 syngeneic mouse tumor model and exhibited significant reduction in tumor growth rate, in tumor vascular density and in metastases to the lung compared to the control. PMID:23375090

  3. Recyclable, strong thermosets and organogels via paraformaldehyde condensation with diamines.

    PubMed

    García, Jeannette M; Jones, Gavin O; Virwani, Kumar; McCloskey, Bryan D; Boday, Dylan J; ter Huurne, Gijs M; Horn, Hans W; Coady, Daniel J; Bintaleb, Abdulmalik M; Alabdulrahman, Abdullah M S; Alsewailem, Fares; Almegren, Hamid A A; Hedrick, James L

    2014-05-16

    Nitrogen-based thermoset polymers have many industrial applications (for example, in composites), but are difficult to recycle or rework. We report a simple one-pot, low-temperature polycondensation between paraformaldehyde and 4,4'-oxydianiline (ODA) that forms hemiaminal dynamic covalent networks (HDCNs), which can further cyclize at high temperatures, producing poly(hexahydrotriazine)s (PHTs). Both materials are strong thermosetting polymers, and the PHTs exhibited very high Young's moduli (up to ~14.0 gigapascals and up to 20 gigapascals when reinforced with surface-treated carbon nanotubes), excellent solvent resistance, and resistance to environmental stress cracking. However, both HDCNs and PHTs could be digested at low pH (<2) to recover the bisaniline monomers. By simply using different diamine monomers, the HDCN- and PHT-forming reactions afford extremely versatile materials platforms. For example, when poly(ethylene glycol) (PEG) diamine monomers were used to form HDCNs, elastic organogels formed that exhibited self-healing properties.

  4. New advanced shotcrete admixtures: Internal curing

    SciTech Connect

    Melbye, T.A.

    1995-12-31

    Tunnels and other underground construction projects have one of the worst curing conditions due to the ventilation that blows continuously dry (cold or hot) air into the tunnel. It can be compared with concrete exposed to a windy area. One would think that tunnels have ideal curing conditions with high humidity (water leakage), no wind and no sun exposure. However, this is not the case. MBT has developed a new system for more efficient and secure curing of wet shotcrete, repair mortars as well as concrete. Internal curing means that a special admixture is added to the concrete/mortar during batching as a normal admixture. This admixture produces an internal barrier in the shotcrete/concrete which secures safer hydration and better chemical resistance than the application of conventional curing agents. The benefits resulting from the new technology are impressive: The time consuming application and, in the case of various shotcrete layers, removal of curing agents are no longer necessary; curing is guaranteed from the very beginning of hydration; and there is no negative influence on bonding between layers. As a consequence of th is optimum curing effect, all other shotcrete characteristics are improved: density, final strengths, freeze/thaw and chemical resistances, watertightness, less cracking and shrinkage. In addition, MEYCO TCC 735 also improves pumpability and workability of shotcrete, even with low-grade aggregates. It particularly improves the pumpability of steel fiber reinforced shotcrete mixes. In combination with the MEYCO TCC system it contrives to even increase the beneficial effects of the slump killing system by further improving fiber orientation, reducing fiber rebound and thus raising toughness values.

  5. Freud's psychoanalysis: a moral cure.

    PubMed

    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.

  6. From HCV To HBV Cure.

    PubMed

    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.

  7. Prevent and cure disuse bone loss

    NASA Technical Reports Server (NTRS)

    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.

  8. Electrochemical hydrogen permeation studies of several mono- and diamines

    SciTech Connect

    Al-Janabi, Y.T.; Lewis, A.L.; Oweimreen, G.A.

    1995-09-01

    The combined presence of moisture and hydrogen sulfide, known in the oil industry as a sour environment, enhances corrosion reactions at a metal surface as well as promotes the entry of hydrogen atoms, resulting from these reactions, into the metal. Increased entry of hydrogen atoms increases the probability of occurrence of hydrogen-induced cracking. The objective of this study is to evaluate the ability of several organic amines to inhibit the overall process of hydrogen entry and to relate their inhibition abilities to their molecular structures. The diffusion coefficients for the permeation of hydrogen atoms through steel estimated in this study using the time-lag and Laplace methods are of the same order of magnitude as those in the published literature. In several hydrogen permeation curves, a characteristic hump was observed. The authors propose that this hump is due to the trapping of hydrogen at sites other than voids and microvoids. The electrochemical system was also sued to study the effectiveness of diethanolamine (DEA), morpholine (MOR), triethanolamine (TEA), ethylenediamine (EDA), and hexamethylene diamine (HMDA) in inhibiting the entry of hydrogen atoms into steel. The diamines were found to be more effective than the monoamines. A nonlinear relationship was observed between the inhibition effectiveness and the concentration of the amines studied. The inhibiting abilities of the monoamines were similar at the high concentration limit (0.01 M) but followed the trend TEA > MOR > DEA at the low concentration limit (5 {times} 10{sup {minus}5} M). For the diamines the inhibiting abilities were also similar at the high concentration limit (5 {times} 10{sup {minus}3} M) and followed the trend HMDA > EDA at the low concentration limit (5 {times} 10{sup {minus}5} M).

  9. Strong Hydrogen Bonded Molecular Interactions between Atmospheric Diamines and Sulfuric Acid.

    PubMed

    Elm, Jonas; Jen, Coty N; Kurtén, Theo; Vehkamäki, Hanna

    2016-05-26

    We investigate the molecular interaction between methyl-substituted N,N,N',N'-ethylenediamines, propane-1,3-diamine, butane-1,4-diamine, and sulfuric acid using computational methods. Molecular structure of the diamines and their dimer clusters with sulfuric acid is studied using three density functional theory methods (PW91, M06-2X, and ωB97X-D) with the 6-31++G(d,p) basis set. A high level explicitly correlated CCSD(T)-F12a/VDZ-F12 method is used to obtain accurate binding energies. The reaction Gibbs free energies are evaluated and compared with values for reactions involving ammonia and atmospherically relevant monoamines (methylamine, dimethylamine, and trimethylamine). We find that the complex formation between sulfuric acid and the studied diamines provides similar or more favorable reaction free energies than dimethylamine. Diamines that contain one or more secondary amino groups are found to stabilize sulfuric acid complexes more efficiently. Elongating the carbon backbone from ethylenediamine to propane-1,3-diamine or butane-1,4-diamine further stabilizes the complex formation with sulfuric acid by up to 4.3 kcal/mol. Dimethyl-substituted butane-1,4-diamine yields a staggering formation free energy of -19.1 kcal/mol for the clustering with sulfuric acid, indicating that such diamines could potentially be a key species in the initial step in the formation of new particles. For studying larger clusters consisting of a diamine molecule with up to four sulfuric acid molecules, we benchmark and utilize a domain local pair natural orbital coupled cluster (DLPNO-CCSD(T)) method. We find that a single diamine is capable of efficiently stabilizing sulfuric acid clusters with up to four acid molecules, whereas monoamines such as dimethylamine are capable of stabilizing at most 2-3 sulfuric acid molecules.

  10. Synthesis and biological studies of N-alkylated cyclic diamines.

    PubMed

    Xiong, Xiao-Qin; Liang, Feng; Yang, Li; Zhou, Xiang; Zheng, Cong-Yi; Cao, Xiao-Ping

    2007-01-01

    Several alkyl-substituted mesocyclic diamines were synthesized, and their interaction with DNA were studied by melting-temperature measurements and the ethidium bromide (EB)-fluorescence competitive method. The supercoiled DNA hydrolytic cleavage by 1,4-dioctyl-1,4-diazepan-6-ol (4) was supported by the evidence from free-radical quenching and T4-ligase ligation. Preliminary pharmacological tests showed that only 1,4-dioctyl-1,4-diazepan-6-ol (4) had antitumor activity against HeLa cell lines in vitro.

  11. Hydroboration/amination of N-trimethylsilyl protected olefinic amines and diolefins: Synthesis of isomerically pure diamines

    SciTech Connect

    Kabalka, G.W.; Zhe Wang )

    1990-01-01

    N-Trimethylsilyl protected olefinic amines and terminal diolefins were hydroborated with dimethylborane and the resulting organoboranes were treated with in situ generated chloramine or chloralkylamines to produce isomerically pure diamines or N-substituted diamines in good yields.

  12. Carboxymethyl starch/alginate microspheres containing diamine oxidase for intestinal targeting

    PubMed Central

    Blemur, Lindsay; Le, Tien Canh; Marcocci, Lucia; Pietrangeli, Paola

    2015-01-01

    Abstract The association of carboxymethyl starch (CMS) and alginate is proposed as a novel matrix for the entrapment of bioactive agents in microspheres affording their protection against gastrointestinal degradation. In this study, the enzyme diamine oxidase (DAO) from white pea (Lathyrus sativus) was immobilized by inclusion in microspheres formed by ionotropic gelation of CMS/alginate by complexation with Ca2+. The association of CMS to alginate generated a more compact structure presenting a lesser porosity, thus decreasing the access of gastric fluid inside the microspheres and preventing the loss of entrapped enzyme. Moreover, the immobilized enzyme remained active and was able to oxidize the polyamine substrates even in the presence of degrading proteases of pancreatin. The inclusion yield in terms of entrapped protein was of about 82%–95%. The DAO entrapped in calcium CMS/alginate beads retained up to 70% of its initial activity in simulated gastric fluid (pH 2.0). In simulated intestinal fluid (pH 7.2) with pancreatin, an overall retention of 65% of activity for the immobilized DAO was observed over 24 H, whereas in similar conditions the free enzyme was totally inactivated. Our project proposes the vegetal DAO as an antihistaminic agent orally administered to treat food histaminosis and colon inflammation. PMID:25779356

  13. Carboxymethyl starch/alginate microspheres containing diamine oxidase for intestinal targeting.

    PubMed

    Blemur, Lindsay; Le, Tien Canh; Marcocci, Lucia; Pietrangeli, Paola; Mateescu, Mircea Alexandru

    2016-05-01

    The association of carboxymethyl starch (CMS) and alginate is proposed as a novel matrix for the entrapment of bioactive agents in microspheres affording their protection against gastrointestinal degradation. In this study, the enzyme diamine oxidase (DAO) from white pea (Lathyrus sativus) was immobilized by inclusion in microspheres formed by ionotropic gelation of CMS/alginate by complexation with Ca(2+) . The association of CMS to alginate generated a more compact structure presenting a lesser porosity, thus decreasing the access of gastric fluid inside the microspheres and preventing the loss of entrapped enzyme. Moreover, the immobilized enzyme remained active and was able to oxidize the polyamine substrates even in the presence of degrading proteases of pancreatin. The inclusion yield in terms of entrapped protein was of about 82%-95%. The DAO entrapped in calcium CMS/alginate beads retained up to 70% of its initial activity in simulated gastric fluid (pH 2.0). In simulated intestinal fluid (pH 7.2) with pancreatin, an overall retention of 65% of activity for the immobilized DAO was observed over 24 H, whereas in similar conditions the free enzyme was totally inactivated. Our project proposes the vegetal DAO as an antihistaminic agent orally administered to treat food histaminosis and colon inflammation.

  14. Nano-indentation of Polycarbonate and Diamine Blends

    NASA Astrophysics Data System (ADS)

    Ahuja, Suresh

    2012-02-01

    Nanoindentation of complex surfaces is of great interest from academic and industrial point of view. There are unique properties such as indentation effects resulting in strain softening and strain hardening. There is a differentiation in structure with the depth exhibited with variation of Tg. Hertzian and non-linear deformation models including usage of FEM offer opportunity in analyzing nano-indentation. In polycarbonate, the effective elastic modulus and the hardness decreases as the applied load is increased. As the hold time was increased, the effective elastic modulus and the hardness also decreased. The contact stress increases as the contact strain rate is increased. Presence of diamine(MTBD) in polycarbonate results in making the surface and bulk brittle and acts as an anti-plasticizer by increasing it modulus and reducing yield stress (hardness) and strain to break. Data on modulus and hardness of polycarbonate and blends of diamine as function of depth (strain) and strain rate are presented and compared with those of composites with silica.

  15. 40 CFR 721.10190 - Formaldehyde, polymer with aliphatic diamine and phenol, reaction products with 4-methyl-2...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... diamine and phenol, reaction products with 4-methyl-2-pentanone (generic). 721.10190 Section 721.10190... Formaldehyde, polymer with aliphatic diamine and phenol, reaction products with 4-methyl-2-pentanone (generic... identified generically as formaldehyde, polymer with aliphatic diamine and phenol, reaction products with...

  16. 40 CFR 721.10190 - Formaldehyde, polymer with aliphatic diamine and phenol, reaction products with 4-methyl-2...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... diamine and phenol, reaction products with 4-methyl-2-pentanone (generic). 721.10190 Section 721.10190... Formaldehyde, polymer with aliphatic diamine and phenol, reaction products with 4-methyl-2-pentanone (generic... identified generically as formaldehyde, polymer with aliphatic diamine and phenol, reaction products with...

  17. Cure behavior of epoxy polymers used in microelectronics

    NASA Astrophysics Data System (ADS)

    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

  18. Antisolvent crystallization method for synthesis of hexamethylene triperoxide diamine nanoparticles

    NASA Astrophysics Data System (ADS)

    Riffle, Eric Edward

    Hexamethylene triperoxide diamine (HMTD) is an explosive organic peroxide, that is considered a homemade explosive (HME) because of the simplicity of the reaction and ease in acquiring the necessary reactants. It has also been investigated for use as a "green" initiating explosive [Ilyushin 2012]. HMTD's sensitivity and thermal stability have been the limiting factor in its use as a cheaply produced military explosive. HMTD is a primary explosive, with good initiating capabilities, but it is highly friction sensitive and thermally unstable. For this reason antisolvent crystallization method was used in order to reduce the particle size, and in turn reduce the friction sensitivity. A method for the variable sized core shell coating of particles was also established.

  19. Effect of silver diamine fluoride on microtensile bond strength to dentin.

    PubMed

    Quock, R L; Barros, J A; Yang, S W; Patel, S A

    2012-01-01

    The aim of this in vitro study was to investigate the effect of the cariostatic and preventive agent silver diamine fluoride (SDF) on the microtensile bond strength of resin composite to dentin. Forty-two caries-free, extracted molars were flattened occlusally and apically using a diamond saw, and the exposed occlusal dentin was polished with a series of silicon carbide papers, all under water irrigation. The teeth were then randomly divided into six groups of seven teeth each that were treated as follows: 1) Peak SE self-etch bonding agent; 2) 12% SDF + Peak SE; 3) 38% SDF + Peak SE; 4) Peak LC etch-and-rinse bonding agent; 5) 12% SDF + Peak LC; and 6) 38% SDF + Peak LC. Four-millimeter buildups of Amelogen Plus were incrementally placed on all teeth; after a 24-hour storage period in distilled water, the specimens were sectioned perpendicular to the adhesive interface to produce beams of cross-sectional surface area measuring approximately 1 mm(2). The beams were placed on a microtensile testing machine, which utilized a single-speed pump motor and force gauge at 20 kgf × 0.01 second to record maximum tensile force before failure occurred. Two-way analysis of variance and post hoc Tukey tests were performed to compare the effects of the SDF on microtensile bond strength, with statistical significance set at α = 0.05. None of the experimental groups treated with different concentrations of SDF showed a significant difference in bond strength compared to the control groups, and there was no significant difference in bond strength between self-etch and etch-and-rinse groups. However, the effect of SDF on self-etch bonded teeth compared to etch-and-rinse bonded teeth was statistically significant (p=0.0363), specifically at the 12% concentration. SDF does not adversely affect the bond strength of resin composite to noncarious dentin.

  20. Current shot noise characteristics in biphenyl diamine and biphenyl dithiol devices

    NASA Astrophysics Data System (ADS)

    kalsoom, Ambreen; Song, Siyu; Li, Guiqin

    2014-09-01

    Current shot noise characteristics, away from their average current, in biphenyl diamine and biphenyl dithiol devices are investigated. The relations among the shot noise and the applied bias, the coupling factors, as well as the alligator clips are revealed. The regular change of the shot noise in biphenyl diamine device and irregular change of the shot noise in biphenyl dithiol device are shown as the coupling strength change from full coupling to weak coupling. It is found that the shot noise suppression in biphenyl diamine device is enhanced at the higher bias. The large differences of the shot noise suppression in the biphenyl dithiol device are revealed.

  1. Process for curing bismaleimide resins

    NASA Technical Reports Server (NTRS)

    Parker, John A. (Inventor); OTHY S.imides alone. (Inventor)

    1986-01-01

    This invention relates to vinyl pyridine group containing compounds and oligomers, their advantageous copolymerization with bismaleimide resins, and the formation of reinforced composites based on these copolymers. When vinyl pyridines including vinyl stilbazole materials and vinyl styrylpyridine oligomer materials are admixed with bismaleimides and cured to form copolymers the cure temperatures of the copolymers are substantially below the cure temperatures of the bismaleimides alone.

  2. New addition curing polyimides

    NASA Technical Reports Server (NTRS)

    Frimer, Aryeh A.; Cavano, Paul

    1991-01-01

    In an attempt to improve the thermal-oxidative stability (TOS) of PMR-type polymers, the use of 1,4-phenylenebis (phenylmaleic anhydride) PPMA, was evaluated. Two series of nadic end-capped addition curing polyimides were prepared by imidizing PPMA with either 4,4'-methylene dianiline or p-phenylenediamine. The first resulted in improved solubility and increased resin flow while the latter yielded a compression molded neat resin sample with a T(sub g) of 408 C, close to 70 C higher than PME-15. The performance of these materials in long term weight loss studies was below that of PMR-15, independent of post-cure conditions. These results can be rationalized in terms of the thermal lability of the pendant phenyl groups and the incomplete imidization of the sterically congested PPMA. The preparation of model compounds as well as future research directions are discussed.

  3. Exploratory Development of an Ultrafast-Curing Wound Dressing

    DTIC Science & Technology

    1988-11-30

    topical antimicrobial agent should: Be poorly absorbed through skin for maximum kill potential at the applied slite * Be bactericidal at low local...our development of non -toxic, tissue compa- tible oligomers which cure under UV radiation. Curing by UV radiation is a breakthrough in medical-grade...suitable way to prevent adhesion; we concluded that poly- urethanes (being relatively tacky) could not be made non - adhe-ent. Silicone gums, on the other

  4. 77 FR 75085 - Proposed Significant New Use Rule on Ethoxylated, Propoxylated Diamine Diaryl Substituted...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-19

    ... Diamine Diaryl Substituted Phenylmethane Ester With Alkenylsuccinate, Dialkylethanolamine Salt AGENCY..., dialkylethanolamine salt, which was the subject of premanufacture notice (PMN) P-01-384. This action would require... diaryl substituted phenylmethane ester with alkenylsuccinate, dialkylethanolamine salt...

  5. Curing mechanism of flexible aqueous polymeric coatings.

    PubMed

    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.

  6. UCSF Protocol for Caries Arrest Using Silver Diamine Fluoride: Rationale, Indications, and Consent

    PubMed Central

    Horst, Jeremy A; Ellenikiotis, Hellene; Milgrom, Peter M

    2016-01-01

    The Food and Drug Administration recently cleared silver diamine fluoride for reducing tooth sensitivity. Clinical trials document arrest and prevention of dental caries by silver diamine fluoride; this off-label use is now permissible and appropriate under U.S. law. A CDT code was approved for caries arresting medicaments for 2016 to facilitate documentation and billing. We present a systematic review, clinical indications, clinical protocol, and consent procedure to guide application for caries arrest treatment. PMID:26897901

  7. Relaxed Poisson cure rate models.

    PubMed

    Rodrigues, Josemar; Cordeiro, Gauss M; Cancho, Vicente G; Balakrishnan, N

    2016-03-01

    The purpose of this article is to make the standard promotion cure rate model (Yakovlev and Tsodikov, ) more flexible by assuming that the number of lesions or altered cells after a treatment follows a fractional Poisson distribution (Laskin, ). It is proved that the well-known Mittag-Leffler relaxation function (Berberan-Santos, ) is a simple way to obtain a new cure rate model that is a compromise between the promotion and geometric cure rate models allowing for superdispersion. So, the relaxed cure rate model developed here can be considered as a natural and less restrictive extension of the popular Poisson cure rate model at the cost of an additional parameter, but a competitor to negative-binomial cure rate models (Rodrigues et al., ). Some mathematical properties of a proper relaxed Poisson density are explored. A simulation study and an illustration of the proposed cure rate model from the Bayesian point of view are finally presented.

  8. UV curing with water based materials

    SciTech Connect

    Beck, E.; Haeussling, L.; Jaeger, U.

    1995-12-01

    Conventional coatings technology requires a large effort to reduce emissions of organic solvents and other volatile organic components. Alleviations, yet not a solution to this problem are high solids coatings formulations or even powder coatings technology. An entirely different concept is used in radiation curing of coatings, where all the elements of the originally low molar mass components of the coating formulation are polymerized into one large network. Thus there should be no emissions of low molar mass compounds from UV- or Electron beam cured films. Water as a diluent in UV-curable formulations can either be used directly as a solvent or in emulsions (with the help of emulsifying agents) without a loss in performance of coatings properties, such as hardness, elasticity and reactivity. To the contrary, the prearrangement of functionalities in the final coating due to the prior phase separation in the emulsion seems to slightly increase hardness and adhesion as well as elasticity.

  9. Theoretical Study of Strong Basicity in Aromatic Diamines.

    PubMed

    Fujiwara, Eiichi; Omoto, Kiyoyuki; Fujimoto, Hiroshi

    1997-10-17

    The basic strength of NH(3), NH(2)(CH(3)), NH(CH(3))(2), and N(CH(3))(3) has been evaluated by generating for each species the orbital that plays the dominant role in electron delocalization to an attached proton. The theoretically determined strength has been found to correlate well with the calculated value of proton affinity. The analysis has then been extended to a so-called "proton-sponge" compound, 1,8-bis(dimethylamino)naphthalene. The major component of the orbital of the diamine that captures the proton has been demonstrated to be an in-phase combination of two lone-pair orbitals. The out-of-phase combination elevated in energy by a strong antibonding interaction between two lone pairs of electrons is not necessarily the source of the exceptionally high basicity. The electrostatic interaction has been shown to be the major origin of stabilizing the protonated system, but the location of the captured proton is governed by electron delocalization. A similar conclusion has also been derived for 4,5-bis(dimethylamino)fluorene.

  10. Haemoglobin adducts of aromatic amines: diamines and polyaromatic amines.

    PubMed

    Sabbioni, G; Beyerbach, A

    2000-07-21

    Aromatic amines and nitroarenes are important antioxidants and intermediates in the synthesis of dyes, pesticides and plastics. In the present paper we introduce methods for the synthesis of deuterated standards: 3-[2H8]aminofluoranthene, 3,3'-dimethyl-[2H4]benzidine, [2H4]benzidine, N'-acetyl-[2H4]benzidine, 2,4-[2H6]toluenediamine, 2,6-[2H6]toluenediamine. These standards have been used for the quantification of haemoglobin adducts of diamines and polyaromatic amines. Haemoglobin was hydrolysed in 0.1 M sodium hydroxide and the hydrolysate extracted with dichloromethane. The extracts were derivatised with heptafluorobutyric anhydride and analysed by GC-MS with negative chemical ionisation. In one run up to 15 aromatic amines can be determined: 6-aminochrysene, 3-aminofluoranthene, 2-aminofluorene, 1-aminopyrene, benzidine, 3,3'-dichlorobenzidine, 3,3'-dimethoxybenzidine, 3,3'-dimethylbenzidine, 3,3'-methylenedianiline, 4,4'-methylenedianiline, N'-acetyl-benzidine, N'-acetyl-4,4'-methylenedianiline, 4,4'-methylene bis(2-chloroaniline), 2,4-toluenediamine and 2,6-toluenediamine.

  11. Paraphenylene diamine hair dye poisoning in an adolescent.

    PubMed

    Abdelraheem, Mohamed; Ali, El-Tigani; Hussien, Rasha; Zijlstra, Eduard

    2011-11-01

    A 14-year-old female was referred to the pediatric nephrology unit with a short history of progressive angio-oedema of the face requiring tracheostomy. She ingested an unusual substance which caused swollen tongue, cervical oedema and dark coloured brown urine. These clinical features with the laboratory tests confirmed the diagnosis of paraphenylene diamine (PPD) poisoning. Psychological assessment confirmed that the child had severe depression. The suicide attempt was just immediately after failure in the final qualifying examination to secondary school. She did not have any family support but she used to be punished in different ways. In Sudan PPD in its pure form is available in the local market and until recently there was no restrictions for its use or trade. Adolescents are well aware of its toxic effects and it is commonly used to attempt suicide. Legislation and laws should prevent its use in different hair dye formulations and look for another substitute. Clinical management is hampered by the lack of a rapid diagnostic test; no other treatment other than supportive measures can be offered.

  12. The Lourdes Medical Cures Revisited†

    PubMed Central

    François, Bernard; Sternberg, Esther M.; Fee, Elizabeth

    2014-01-01

    This article examines the cures recorded in Lourdes, France, between 1858, the year of the Visions, and 1976, the date of the last certified cure of the twentieth century. Initially, the records of cures were crude or nonexistent, and allegations of cures were accepted without question. A Medical Bureau was established in 1883 to examine and certify the cures, and the medical methodology improved steadily in the subsequent years. We discuss the clinical criteria of the cures and the reliability of medical records. Some 1,200 cures were said to have been observed between 1858 and 1889, and about one hundred more each year during the “Golden Age” of Lourdes, 1890–1914. We studied 411 patients cured in 1909–14 and thoroughly reviewed the twenty-five cures acknowledged between 1947 and 1976. No cure has been certified from 1976 through 2006. The Lourdes phenomenon, extraordinary in many respects, still awaits scientific explanation. Lourdes concerns science as well as religion. PMID:22843835

  13. Effectiveness of Membrane-Forming Curing Compounds for Curing Concrete

    DTIC Science & Technology

    1990-04-01

    Type I portland cement designated WES-48, C-I and a graded silica sand from Ottawa, IL, C-109, was used in preparing the mortar for testing. The test...report for the portland cement is shown in Table 1. Membrane-Forming Curing Compounds 6. Nine curing compounds obtained from four manufacturers were...evaluating the effectiveness of cure of portland - cement mortar were investigated that included: water absorptivity at different depths, capillary porosity

  14. Comparative static curing versus dynamic curing on tablet coating structures.

    PubMed

    Gendre, Claire; Genty, Muriel; Fayard, Barbara; Tfayli, Ali; Boiret, Mathieu; Lecoq, Olivier; Baron, Michel; Chaminade, Pierre; Péan, Jean Manuel

    2013-09-10

    Curing is generally required to stabilize film coating from aqueous polymer dispersion. This post-coating drying step is traditionally carried out in static conditions, requiring the transfer of solid dosage forms to an oven. But, curing operation performed directly inside the coating equipment stands for an attractive industrial application. Recently, the use of various advanced physico-chemical characterization techniques i.e., X-ray micro-computed tomography, vibrational spectroscopies (near infrared and Raman) and X-ray microdiffraction, allowed new insights into the film-coating structures of dynamically cured tablets. Dynamic curing end-point was efficiently determined after 4h. The aim of the present work was to elucidate the influence of curing conditions on film-coating structures. Results demonstrated that 24h of static curing and 4h of dynamic curing, both performed at 60°C and ambient relative humidity, led to similar coating layers in terms of drug release properties, porosity, water content, structural rearrangement of polymer chains and crystalline distribution. Furthermore, X-ray microdiffraction measurements pointed out different crystalline coating compositions depending on sample storage time. An aging mechanism might have occur during storage, resulting in the crystallization and the upward migration of cetyl alcohol, coupled to the downward migration of crystalline sodium lauryl sulfate within the coating layer. Interestingly, this new study clearly provided further knowledge into film-coating structures after a curing step and confirmed that curing operation could be performed in dynamic conditions.

  15. Modeling HIV Cure

    NASA Astrophysics Data System (ADS)

    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.

  16. [Towards the definition of cure].

    PubMed

    Touzet, Patrick

    Is the term cure adapted to psychiatry? Firstly, it is important to establish what this status represents. What is immediately clear is that the term cure cannot be addressed in isolation. Considering the term leads us to question notions such as those of disease and the norm, without forgetting the actual purpose of care. Cure can then be envisaged more as a 'possible' for caregivers.

  17. Fatty pain cures.

    PubMed

    Imming, Peter

    2007-12-01

    In this issue, Alvin King, Daniele Piomelli, and colleagues publish another interesting paper on inhibition of monoacylglycerol lipase (MGL). MGL is a hot target for antinociceptive agents, being the chief degrading enzyme of the endocannabinoid 2-arachidonoylglycerol.

  18. Fabrication and electrochemical properties of insoluble fullerene-diamine adduct thin-films as buffer layer by alternate immersion process

    NASA Astrophysics Data System (ADS)

    Saito, Jo; Akiyama, Tsuyoshi; Suzuki, Atsushi; Oku, Takeo

    2017-01-01

    Insoluble fullerene-diamine adduct thin-films consisting of C60 and 1,2-diaminoethane were easily fabricated on an electrode by an alternate immersion process. Formation of the C60-diamine adduct films were confirmed using transmission absorption spectroscopy and atomic force microscopy. An inverted-type organic solar cells were fabricated by using the C60-diamine adduct film as the electron transport layer. The resultant photoelectric conversation performance of the solar cells suggested that photocurrent is generated via the photoexcitation of polythiophene. The result suggests that the present insoluble fullerene-diamine adduct films worked as buffer layer for organic thin-film solar cells.

  19. Dielectric cure monitoring: Preliminary studies

    NASA Technical Reports Server (NTRS)

    Goldberg, B. E.; Semmel, M. L.

    1984-01-01

    Preliminary studies have been conducted on two types of dielectric cure monitoring systems employing both epoxy resins and phenolic composites. An Audrey System was used for 23 cure monitoring runs with very limited success. Nine complete cure monitoring runs have been investigated using a Micromet System. Two additional measurements were performed to investigate the Micromet's sensitivity to water absorption in a post-cure carbon-phenolic material. While further work is needed to determine data significance, the Micromet system appears to show promise as a feedback control device during processing.

  20. Delayed cure bismaleimide resins

    DOEpatents

    Adams, Johnnie E.; Jamieson, Donald R.

    1984-08-07

    Polybismaleimides prepared by delayed curing of bis-imides having the formula ##STR1## wherein R.sub.1 and R.sub.2 each independently is H, C.sub.1-4 -alkyl, C.sub.1-4 -alkoxy, Cl or Br, or R.sub.1 and R.sub.2 together form a fused 6-membered hydrocarbon aromatic ring, with the proviso that R.sub.1 and R.sub.2 are not t-butyl or t-butoxy; X is O, S or Se; n is 1-3; and the --(CH.sub.2).sub.n -- group, optionally, is substituted by 1-3 methyl groups or by fluorine.

  1. Alkali metal derivatives of an ortho-phenylene diamine.

    PubMed

    Robinson, Sarah; Davies, E Stephen; Lewis, William; Blake, Alexander J; Liddle, Stephen T

    2014-03-21

    Treatment of the ortho-phenylene diamine C6H4-1,2-{N(H)Tripp}2 (1, PDAH2, Tripp = 2,4,6-triisopropylphenyl) with two equivalents of MR (M = Li, R = Bu(n); M = Na or K, R = CH2C6H5) afforded the dimetallated alkali metal ortho-phenylene diamide dianion complexes [(PDALi2)(THF)3] (2), [{(PDANa2)(THF)2}2] (3), and [{(PDAK2)(THF)3}2] (4). In contrast, treatment of 2 with two equivalents of rubidium or cesium 2-ethylhexoxide, or treatment of 1 with two equivalents of MR (M = Rb or Cs, R = CH2C6H5) did not afford the anticipated dialkali metal ortho-phenylene diamide dianion derivatives and instead formally afforded the monometallic ortho-diiminosemiquinonate radical anion species [PDAM] (M = Rb, 5; M = Cs, 6). The structure of 2 is monomeric with one lithium coordinated to the two nitrogen centres and the other lithium η(4)-coordinated to the diazabutadiene portion of the PDA scaffold. Similar structural cores are observed for 3 and 4, except that the larger sodium and potassium ions give dimeric structures linked by multi-hapto interactions from the PDA backbone phenyl ring to an alkali metal centre. Complex 5 was not characterised in the solid state, but the structure of 6 reveals coordination of cesium ions to both PDA amide centres and multi-hapto interactions to a PDA backbone phenyl ring in the next unit to generate a one-dimensional polymer. Complexes 2-6 have been variously characterised by X-ray crystallography, multi-nuclear NMR, FTIR, and EPR spectroscopies, and CHN microanalyses.

  2. Epoxy resin cure. [Phenyl glycidyl ether

    SciTech Connect

    Smith, R.E.; Woodburn, G.L.

    1986-07-01

    The reactions that occur between the model epoxy, phenyl glycidyl ether, and the cure agent dicyandiamide (DICY) have been investigated using nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), gel permeation chromatography (GPC), and high-performance liquid chromatography (HPLC) techniques. It is shown that the reaction at 130/sup 0/C requires 90 min for completion when catalyzed by boron trifluoride monoethyl amine (BF/sub 3/-MEA). At least three major products are formed. The identity of these products is based on previously published spectroscopic data. 3 refs., 5 figs.

  3. Pulsed NMR study of the curing process of epoxy resin.

    PubMed

    Kimoto, Hiroki; Tanaka, Chikako; Yaginuma, Michiko; Shinohara, Emi; Asano, Atsushi; Kurotsu, Takuzo

    2008-07-01

    To analyze a curing process of epoxy resin in terms of molecular motion, we adapted a pulsed NMR method. Three kinds of (1)H spin-spin relaxation times (T(2L) (long), T(2S) (short) and T(2M) (intermediate)) were estimated from observed solid echo train signals as the curing process proceeded. A short T(2S) value below 20 micros suggests the existence of a motion-restricted chain, that is, cured elements of resin, and its fraction, P(S), sigmoidally increased with the curing time. On the other hand, the fraction of T(2L), P(L), decreased with the reaction time reciprocally against P(S), suggesting the disappearance of highly mobile molecules raised from pre-cured resin. The spin-lattice relaxation time, T(1), was also measured to check another aspect of molecular motion in the process. T(1) of the mixed epoxy resin and curing agent gradually increased just after mixing both of them. This corresponds to an increment of a less-mobile fraction, of which the correction time is more than 10(-6) s, and also means that the occurrence of a network structure whose mobility is strongly restricted by chemically bonded bridges between the epoxy resin and curing agent. The time courses of these parameters coincided with those of IR peaks pertinent to the curing reaction. Therefore, pulsed NMR is a useful tool to monitor the hardening process of epoxy resin in real time non-distractively in terms of the molecular motion of protons.

  4. Response of Anastrepha suspensa (Diptera: Tephritidae) to terminal diamines in a food-based synthetic attractant.

    PubMed

    Kendra, Paul E; Epsky, Nancy D; Montgomery, Wayne S; Heath, Robert R

    2008-10-01

    A current trapping system for Anastrepha fruit flies uses a two-component food-based synthetic attractant consisting of ammonium acetate and putrescine (1,4-diaminobutane). Development of more effective monitoring programs may be realized through identification of additional attractant chemicals. This study examined response of the Caribbean fruit fly, Anastrepha suspensa (Loew), to putrescine and four homologous terminal diamines, differing only in carbon chain length. Using a fixed dose of each diamine substrate, electroantennogram (EAG) responses from mature females to putrescine and cadaverine (1,5-diaminopentane) were not significantly different from each other but were significantly greater than responses to longer chain diamines. Over a range of doses tested, mean female EAG response was greater than male response to both putrescine and cadaverine. In an initial field test, capture of female flies in traps baited with ammonium acetate and either putrescine or cadaverine was higher than in traps baited with ammonium acetate and any of the other diamines. In a subsequent field test, traps baited with putrescine, cadaverine, or 1,6-diaminohexane in combination with ammonium acetate captured more female flies than traps baited with ammonium acetate alone. A significantly greater synergistic effect on female captures was observed with either putrescine or cadaverine than with 1,6-diaminohexane. Thus, of the diamines evaluated, cadaverine elicited both antennal and behavioral responses comparable to that of putrescine and will be studied further as a potential attractant for pest Anastrepha species.

  5. Ambient curing fire resistant foams

    NASA Technical Reports Server (NTRS)

    Hamermesh, C. L.; Hogenson, P. A.; Tung, C. Y.; Sawko, P. M.; Riccitiello, S. R.

    1979-01-01

    The feasibility of development of an ambient curing foam is described. The thermal stability and flame spread index of the foams were found to be comparable to those of the high-temperature cured polyimide foams by Monsanto two-foot tunnel test and NASA T-3 Fire test. Adaptation of the material to spray in place applications is described

  6. Is toluene diamine a sensitizer and is there cross-reactivity between toluene diamine and toluene diisocyanate?

    PubMed

    Vanoirbeek, Jeroen A J; De Vooght, Vanessa; Synhaeve, Nicholas; Nemery, Benoit; Hoet, Peter H M

    2009-06-01

    Toluene diamine (TDA) is formed when toluene diisocyanate (TDI), a potent sensitizer, comes in contact with an aqueous environment. The sensitizing capacity of TDA and the cross-reactivity between TDI and TDA are unknown. TDA (5-25%) and TDI (0.3%), dissolved in acetone/olive oil (AOO) (4:1) were tested in the mouse local lymph node assay (LLNA). To determine the capacity of TDA to elicit an asthmatic response and to determine the cross-reaction with TDI, a locally developed experimental mouse model of chemical-induced asthma was used. On days 1 and 8, BALB/c mice received 20 microl of TDI (0.3%), TDA (20%), or AOO (4:1) on each ear. On day 15, they received an intranasal instillation of TDI (0.1%), TDA (0.5%) or AOO (3:2). The EC(3) of TDA in the LLNA is 19%. In the model of chemical-induced asthma, TDI induced a ventilatory response [increased Penh after challenge; increased airway hyperreactivity (AHR)], inflammatory changes (bronchoalveolar lavage neutrophils), and immunological changes (increased CD19(+) lymphocytes, IL-4 and total serum IgE), whereas TDA did not show any of these responses. Mice sensitized with TDI and challenged with TDA also did not show any airway or inflammatory response, although they had increased levels of total serum IgE. Mice sensitized with TDA and challenged with TDI did not show any response. According to the classification of sensitizers in the LLNA, TDA is a weak dermal sensitizer. In the experimental mouse model of chemical-induced asthma, TDA does not act as a respiratory sensitizer, at the concentration used. No cross-reactivity between TDI and TDA was found.

  7. N-15 NMR Spectroscopy as a Method for Comparing the Rates of Imidization of Several Diamines

    NASA Technical Reports Server (NTRS)

    Johnson, J. Christopher; Kuczmarski, Maria A.

    2006-01-01

    The relative rates of the conversion of amide-acid to imide was measured for a series or aromatic diamines that have been identified as potential replacements for 4,4'-methylene dianiline (MDA) in high-temperature polyimides and polymer composites. These rates were compared with the N-15 NMR resonances of the unreacted amines. The initial rates of imidization track with the difference in chemical shift between the amine nitrogens in MDA and those in the subject diamines. This comparison demonstrated that N-15 NMR spectroscopy is appropriate for the rapid screening of candidate diamines to determine their reactivity relative to MDA, and can serve to provide guidance to the process of creating the time-temperature profiles used in processing these materials into polymer matrix composites.

  8. Cure reaction of epoxy resins catalyzed by graphite-based nanofiller

    NASA Astrophysics Data System (ADS)

    Corcione, C. Esposito; Acocella, Maria Rosaria; Giuri, Antonella; Maffezzoli, Alfonso; Guerra, Gaetano

    2015-12-01

    A significant effort was directed to the synthesis of graphene stacks/epoxy nanocomposites and to the analysis of the effect of a graphene precursor on cure reaction of a model epoxy matrix. A comparative thermal analysis of epoxy resins filled with an exfoliated graphite oxide eGO were conducted. The main aim was to understand the molecular origin of the influence of eGO on the Tg of epoxy resins. The higher Tg values previously observed for low curing temperatures, for epoxy resins with graphite-based nanofillers, were easily rationalized by a catalytic activity of graphitic layers on the reaction between the epoxy and amine groups of the resin, which leads to higher crosslinking density in milder conditions. A kinetic analysis of the cure mechanism of the epoxy resin associated to the catalytical activity of the graphite based filler was performed by isothermal DSC measurements. The DSC results showed that the addition of graphite based filler greatly increased the enthalpy of epoxy reaction and the reaction rate, confirming the presence of a catalytic activity of graphitic layers on the crosslinking reaction between the epoxy resin components (epoxide oligomer and di-amine). A kinetic modelling analysis, arising from an auto-catalyzed reaction mechanism, was finally applied to isothermal DSC data, in order to predict the cure mechanism of the epoxy resin in presence of the graphite based nanofiller.

  9. 40 CFR 721.10664 - Alkenedioic acid dialkyl ester, reaction products with alkenoic acid alkyl esters and diamine...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkenedioic acid dialkyl ester, reaction products with alkenoic acid alkyl esters and diamine (generic). 721.10664 Section 721.10664... Alkenedioic acid dialkyl ester, reaction products with alkenoic acid alkyl esters and diamine (generic)....

  10. 40 CFR 721.10664 - Alkenedioic acid dialkyl ester, reaction products with alkenoic acid alkyl esters and diamine...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkenedioic acid dialkyl ester, reaction products with alkenoic acid alkyl esters and diamine (generic). 721.10664 Section 721.10664... Alkenedioic acid dialkyl ester, reaction products with alkenoic acid alkyl esters and diamine (generic)....

  11. 40 CFR 721.10190 - Formaldehyde, polymer with aliphatic diamine and phenol, reaction products with 4-methyl-2...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Formaldehyde, polymer with aliphatic... Formaldehyde, polymer with aliphatic diamine and phenol, reaction products with 4-methyl-2-pentanone (generic... identified generically as formaldehyde, polymer with aliphatic diamine and phenol, reaction products with...

  12. 40 CFR 721.10190 - Formaldehyde, polymer with aliphatic diamine and phenol, reaction products with 4-methyl-2...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Formaldehyde, polymer with aliphatic... Formaldehyde, polymer with aliphatic diamine and phenol, reaction products with 4-methyl-2-pentanone (generic... identified generically as formaldehyde, polymer with aliphatic diamine and phenol, reaction products with...

  13. 40 CFR 721.10190 - Formaldehyde, polymer with aliphatic diamine and phenol, reaction products with 4-methyl-2...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Formaldehyde, polymer with aliphatic... Formaldehyde, polymer with aliphatic diamine and phenol, reaction products with 4-methyl-2-pentanone (generic... identified generically as formaldehyde, polymer with aliphatic diamine and phenol, reaction products with...

  14. Cure of incurable lymphoma

    SciTech Connect

    De Nardo, Gerald L.

    2006-10-01

    The most potent method for augmenting the cytocidal power of monoclonal antibody (MAb) treatment is to conjugate radionuclides to the MAb to deliver systemic radiotherapy (radioimmunotherapy; RIT). The antigen, MAb, and its epitope can make a difference in the performance of the drug. Additionally, the radionuclide, radiochemistry, chelator for radiometals and the linker between the MAb and chelator can have a major influence on the performance of drugs (radiopharmaceuticals) for RIT. Smaller radionuclide carriers, such as antibody fragments and mimics, and those used for pretargeting strategies, have been described and evaluated. All of these changes in the drugs and strategies for RIT have documented potential for improved performance and patient outcomes. RIT is a promising new therapy that should be incorporated into the management of patients with B-cell non-Hodgkin's lymphoma (NHL) soon after these patients have proven incurable. Predictable improvements using better drugs, strategies, and combinations with other drugs seem certain to make RIT integral to the management of patients with NHL, and likely lead to cure of currently incurable NHL.

  15. Primary-tertiary diamine-catalyzed Michael addition of ketones to isatylidenemalononitrile derivatives.

    PubMed

    Kumar, Akshay; Chimni, Swapandeep Singh

    2014-01-01

    Simple primary-tertiary diamines easily derived from natural primary amino acids were used to catalyze the Michael addition of ketones with isatylidenemalononitrile derivatives. Diamine 1a in combination with D-CSA as an additive provided Michael adducts in high yield (up to 94%) and excellent enantioselectivity (up to 99%). The catalyst 1a was successfully used to catalyze the three-component version of the reaction by a domino Knoevenagel-Michael sequence. The Michael adduct 4a was transformed into spirooxindole 6 by a reduction with sodium borohydride in a highly enantioselective manner.

  16. CO2 Capture Using 2,2-Dialkylpropane-1,3-diamines

    SciTech Connect

    O'Brien, MJ; Farnum, RL; Perry, RJ

    2013-01-01

    A series of 2,2-dialkylpropane-1,3-diamines were synthesized and evaluated as potential phase-changing CO2 sorbents. In general, these compounds readily absorbed CO2 to form solid carbamate salts, which were relatively insensitive to the presence of moisture. This is one of the key performance attributes phase-changing sorbents must possess. However, these diamines were found to be less thermally stable in air than expected. The main reaction products obtained during heat aging at 150 degrees C appeared to be 1,4,5,6-tetrahydropyrimidine derivatives.

  17. Origins of Stereoselectivity of Chiral Vicinal Diamine-Catalyzed Aldol Reactions.

    PubMed

    Simon, Adam; Yeh, Alexander J; Lam, Yu-Hong; Houk, K N

    2016-12-16

    The sources of asymmetric induction in aldol reactions catalyzed by cinchona alkaloid-derived amines, and chiral vicinal diamines in general, have been determined by density functional theory calculations. Four vicinal diamine-catalyzed aldol reactions were examined. The cyclic transition states of these reactions involve nine-membered hydrogen-bonded rings in distinct conformations. Using nomenclature from eight-membered cycloalkanes, the heavy atoms of the low-energy transition states are in crown (chair-chair) and chair-boat conformations. The factors that control which of these are favored have been identified.

  18. Synthesis and biological evaluation against Mycobacterium tuberculosis and Leishmania amazonensis of a series of diaminated terpenoids.

    PubMed

    Dos Reis, Dijovani Batista; Souza, Thalita Cristina Alves; Lourenço, Maria Cristina S; de Almeida, Mauro Vieira; Barbosa, Adriano; Eger, Iriane; Saraiva, Mauricio Frota

    2016-12-01

    We report the synthesis of a series of diaminated terpenoids containing, as side-chain of the diamine core, the "head-to-tail" prenyl derivatives, with amino amino spacers of variable length. In vitro biological activity of these compounds was evaluated against Mycobacterium tuberculosis and Leishmania amazonensis, and the structure-activity relationships are discussed. Different biological results were observed depending on the terpenic side-chain length. The best results were obtained for trans,trans-farnesol derivatives. Moreover, these results demonstrated that the stereochemistry of the double bond could play an important role in determining antitubercular and antileishmanial activities of these compounds.

  19. Cu(I)-catalyzed N,N’-diarylation of natural diamines and polyamines with aryl iodides

    PubMed Central

    Panchenko, Svetlana Petrovna; Averin, Alexei Dmitrievich; Anokhin, Maksim Viktorovich; Maloshitskaya, Olga Aleksandrovna

    2015-01-01

    Summary The Cu(I)-catalyzed N,N’-diarylation of natural diamines and polyamines such as putrescine, cadaverine, spermine, spermidine and their homologues is described. Aryl iodides bearing electron-donating and electron-withdrawing groups have been employed in the study. The CuI/2-(isobutyryl)cyclohexanone/DMF catalytic system has found to be more efficient in the diarylation of diamines and spermine while the CuI/L-proline/EtCN system proved to be preferable for the diarylation of other tri- and tetraamines like spermidine, norspermidine and norspermine. PMID:26734078

  20. Cu(I)-catalyzed N,N'-diarylation of natural diamines and polyamines with aryl iodides.

    PubMed

    Panchenko, Svetlana Petrovna; Averin, Alexei Dmitrievich; Anokhin, Maksim Viktorovich; Maloshitskaya, Olga Aleksandrovna; Beletskaya, Irina Petrovna

    2015-01-01

    The Cu(I)-catalyzed N,N'-diarylation of natural diamines and polyamines such as putrescine, cadaverine, spermine, spermidine and their homologues is described. Aryl iodides bearing electron-donating and electron-withdrawing groups have been employed in the study. The CuI/2-(isobutyryl)cyclohexanone/DMF catalytic system has found to be more efficient in the diarylation of diamines and spermine while the CuI/L-proline/EtCN system proved to be preferable for the diarylation of other tri- and tetraamines like spermidine, norspermidine and norspermine.

  1. Investigations on N-nitrosopyrrolidine in dry-cured bacon.

    PubMed

    Fiddler, W; Pensabene, J W; Gates, R A; Foster, J M; Smith, W J

    1989-01-01

    Dry-cured or "country-style" bacon is a low volume specialty product typically made by small producers whose production practices vary widely. These practices include the direct application of dry-cure formulations containing varying concentrations of salt, sugar, flavoring agents, sodium nitrite, and sometimes sodium nitrate, and the use of lengthy curing and processing times. Because of the possibility of generating higher levels of N-nitrosopyrrolidine (NPYR) after frying in this product type compared with pump-cured bacon, an investigation was carried out on dry-cured bacon obtained from cooperating state or federally inspected establishments. Three different samples from each of the 16 plants were analyzed. Only one sample from each of 2 different producers exceeded the Food Safety and Inspection Service (FSIS) action level of 17 ppb NPYR, indicating that the majority of samples tested were in compliance. A significant correlation (P less than 0.01) was found between residual NaNO2 prior to frying and NPYR after frying. The elimination of added nitrate in the dry-cure formulations is recommended.

  2. 40 CFR 721.5585 - 4,4′-(1-methylethylidene)bisphenol, polymer with (chloromethyl)oxirane and a diamine (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., polymer with (chloromethyl)oxirane and a diamine (generic). 721.5585 Section 721.5585 Protection of...-methylethylidene)bisphenol, polymer with (chloromethyl)oxirane and a diamine (generic). (a) Chemical substance and...-methylethylidene)bisphenol, polymer with (chloromethyl) oxirane and a diamine (PMN P-97-0916) is subject...

  3. 40 CFR 721.5585 - 4,4′-(1-methylethylidene)bisphenol, polymer with (chloromethyl)oxirane and a diamine (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., polymer with (chloromethyl)oxirane and a diamine (generic). 721.5585 Section 721.5585 Protection of...-methylethylidene)bisphenol, polymer with (chloromethyl)oxirane and a diamine (generic). (a) Chemical substance and...-methylethylidene)bisphenol, polymer with (chloromethyl) oxirane and a diamine (PMN P-97-0916) is subject...

  4. 40 CFR 721.5585 - 4,4′-(1-methylethylidene)bisphenol, polymer with (chloromethyl)oxirane and a diamine (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., polymer with (chloromethyl)oxirane and a diamine (generic). 721.5585 Section 721.5585 Protection of...-methylethylidene)bisphenol, polymer with (chloromethyl)oxirane and a diamine (generic). (a) Chemical substance and...-methylethylidene)bisphenol, polymer with (chloromethyl) oxirane and a diamine (PMN P-97-0916) is subject...

  5. 40 CFR 721.5585 - 4,4′-(1-methylethylidene)bisphenol, polymer with (chloromethyl)oxirane and a diamine (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., polymer with (chloromethyl)oxirane and a diamine (generic). 721.5585 Section 721.5585 Protection of...-methylethylidene)bisphenol, polymer with (chloromethyl)oxirane and a diamine (generic). (a) Chemical substance and...-methylethylidene)bisphenol, polymer with (chloromethyl) oxirane and a diamine (PMN P-97-0916) is subject...

  6. 40 CFR 721.5585 - 4,4′-(1-methylethylidene)bisphenol, polymer with (chloromethyl)oxirane and a diamine (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., polymer with (chloromethyl)oxirane and a diamine (generic). 721.5585 Section 721.5585 Protection of...-methylethylidene)bisphenol, polymer with (chloromethyl)oxirane and a diamine (generic). (a) Chemical substance and...-methylethylidene)bisphenol, polymer with (chloromethyl) oxirane and a diamine (PMN P-97-0916) is subject...

  7. Enantiomerically pure isophorone diamine [3-(aminomethyl)-3,5,5-trimethylcyclohexylamine]: a chiral 1,4-diamine building block made available on large scale.

    PubMed

    Berkessel, Albrecht; Roland, Katrin; Schröder, Michael; Neudörfl, Jörg M; Lex, Johann

    2006-12-08

    Isophorone diamine [IPDA, 3-(aminomethyl)-3,5,5-trimethylcyclohexylamine] is a chiral non-C2-symmetric 1,4-diamine which is produced industrially on large scale as the mixture of all four stereoisomers (cis/trans ca. 3:1). Starting from this industrial bulk product, the preparation of the bis-tosyl, bis-Fmoc, bis-Boc and bis-Z derivatives of cis-IPDA, the preparation of the pure cis enantiomers by HPLC on chiral stationary phase, and the assignment of absolute configurations to the isolated enantiomers are described. We furthermore report an efficient method for the optical resolution of IPDA by salt formation with dibenzoyl tartaric acid. The latter method conveniently affords enantiomerically pure cis-IPDA in 100 g quantities. A number of salen ligands have been prepared from this enantiomerically pure 1,4-diamine and fully characterized. The nickel complex of one of the salen ligands was prepared and analyzed by X-ray crystallography. The crystal structure of the Ni4L4 complex illustrates the pronounced preference of cis-IPDA for adopting the chair conformation in which both the amino- and the aminomethyl substituents occupy equatorial positions. As a consequence, the two salicylidene imine moieties of one ligand molecule do not converge on one metal ion, but act as bridging ligands between two nickel ions.

  8. Tetracycline: a cure all?

    PubMed

    Kennedy, Robert; Alibhai, Mustansir; Shakib, Kaveh

    2014-04-01

    Tetracyclines are used to treat a range of oral conditions. Their efficacy in the treatment of periodontitis is well established, and they are authoritatively recommended in the management of avulsed teeth. There is a growing evidence base to support the use of tetracycline to treat recurrent aphthous stomatitis, but its use in white spongy naevus is limited to a handful of case reports. The mechanism of action in these conditions is either unknown or indicated to be through the inhibition of matrix metalloproteinases (MMP). The use of a single agent to treat diverse oral conditions has important implications for oral medicine.

  9. Correlation of cure monitoring techniques

    NASA Astrophysics Data System (ADS)

    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.

  10. Polyimides from 2,3,3',4'-Biphenyltetracarboxylic Dianhydride and Aromatic Diamines

    NASA Technical Reports Server (NTRS)

    Hergenrother, Paul M. (Inventor); Smith, Joseph G. (Inventor); Connell, John W. (Inventor); Watson, Kent A. (Inventor)

    2005-01-01

    The present invention relates generally to polyimides. It relates particularly to novel polyimides prepared from 2,3, 3',4' -biphenyltetracarboxylic dianhydride and aromatic diamines. These novel polyimides have low color, good solubility, high thermal emissivity, low solar absorptivity and high tensile strength.

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

    PubMed

    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

  12. A study on the reactions of plant copper amine oxidase with C3 and C4 aliphatic diamines.

    PubMed

    Sebela, M; Frébort, I; Lemr, K; Brauner, F; Pec, P

    2000-12-01

    The paper reports a study on the reactions of grass pea (Lathyrus sativus) amine oxidase (GPAO) with several aliphatic diamines. The influence of the chain length and of unsaturations in the molecules was examined. Kinetic measurements confirmed that trans-, i.e., (E)-2-butene-1,4-diamine (TDABE) and cis-, i.e., (Z)-2-butene-1,4-diamine (CDABE) could be classified as good substrates. Propane-1,3-diamine (DAP) and propene-1,3-diamine (DAPE) were only weakly oxidized, whereas 1,3-diamino-2-propanol (DAPL) was not utilized as a substrate. Contrary to the inactivator 2-butyne-1,4-diamine (DABI), DAPE was shown to be only a competitive inhibitor. DAP itself did not inhibit the catalytic activity. Irreversible inhibition of the activity occurred only after the incubation of GPAO with DABI; other diamines were without this effect. Differential pulse polarography and chromatofocusing confirmed that the aminoaldehyde product of DABI oxidation binds to the enzyme. Activity assay of pea aminoaldehyde dehydrogenase enabled us to detect the products of the oxidation of TDABE, CDABE, and DAP by GPAO. As the product of DAP oxidation, 3-amino-propanal (APAL) was detected by mass spectrometry and confirmed to be a potent noncompetitive inhibitor of GPAO. The absorption changes that occurred in the course of the reaction of GPAO with the diamines were investigated using rapid-scanning spectrophotometry. DABI, TDABE, CDABE, DAP, and DAPE reacted with GPAO providing characteristic maxima of the Cu(I)-semiquinolamine species that is formed in the catalytic cycle. The results presented here confirm that with the exception of DAPL, all the studied diamines could be classified as GPAO substrates, but only DABI can be considered as a mechanism-based inhibitor.

  13. Curing chemistry of phenylethynyl-terminated imide oligomers: Model compounds, carbon-13 labeling and cure analysis

    NASA Astrophysics Data System (ADS)

    Roberts, Christopher Chad

    1998-11-01

    Phenylethynyl-terminated imide oligomers (PETI) are currently considered the state-of-the-art high performance resins for aerospace applications. The processing of these resins is more facile because of their low molecular weight, but PETI's cure to form a tough, solvent-resistant material. However, the final cure structure was a complete mystery. Hence, the present study was set forth with three essential goals. The determination of the final structure of the crosslinked polymer is of obvious importance. Second, the crosslinking mechanism and controlling factors is also of interest. Lastly, the final structure of the crosslinked polymers was correlated with mechanical and thermal properties, thereby helping to establish the structure-processing-properties relationships for PETI resins. These goals were accomplished by using a combination of synthesis of model compounds synthesis and proposed cure products, sp{13}C labeling of the ethynyl endgroup in PETI's, monitoring of the thermal cure using solid state sp{13}C NMR and ESR and molecular modeling techniques. Phenylethynyl endcapping agents, 4-(phenylethynyl)phthalic anhydride (PEPA) and 3-(phenylethynyl)aniline (3PEA), were synthesized via the palladium-catalyzed coupling of phenylacetylene with 4-bromophthalic anhydride or 3-iodonitrobenzene followed by reduction to 3PEA, respectively. Isolated yields of 41 and 86% for 3PEA and PEPA were obtained, respectively. Model compounds were synthesized from 3PEA and PEPA by reacting with them the appropriate aniline or phthalic anhydride derivative. Model compounds included N-pentafluorophenyl-4-(phenylethynyl)phthalimide (PEPA/F5An), N-(4-trifluoromethyl-phenyl)4-(phenylethynyl)phthalimide (PEPA/F3CAn), N-lbrack 3-(phenylethynyl)phenylrbrack\\ phthalimide (3PEA/PA), N-phenyl-4-(phenylethynyl)phthalimide (PEPA/An), N-(4-phenoxyphenyl)4-(phenylethynyl)phthalimide (PEPA/POAn), and N-(1-naphthyl)-4-(phenylethynyl)phthalimide (PEPA/Anaph). Proposed cure products such as

  14. [Mineral water as a cure].

    PubMed

    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

  15. A New Kind of Curing

    NASA Technical Reports Server (NTRS)

    2001-01-01

    A new curing method using automated tape placement (ATP) with electron beam (EB), or e-beam, produces a combination known as in situ e-beam curing. Through a Small Business Innovation Research (SBIR) contract from NASA's Marshall Space Flight Center, Science Research Laboratory, Inc., created the in situ e-beam curing technique, which uses a low-energy electron beam gun to cure various composite materials. One important benefit is the technique's utilization of room temperature curing, which lessens the chance of mismatching the thermal expansion coefficients of different materials. For instance, metals and composites will expand at different rates when heated, but the low-energy e-beam gun reduces the expansion differential. Using a low-energy gun also results in less x-ray shielding, significantly reduced capital costs, reduced facility space, and increased processing capabilities for larger parts. However, using a low-energy gun also means that each tape layer is treated individually because the gun can penetrate only one layer at a time. The e-beam gun emits lower energy x-rays, which are more easily shielded than those emitted by previous guns. The low-energy system is relatively portable due to its light weight and small size. The gun weighs about 70 pounds and can be easily mounted on a robotic arm or an ATP head.

  16. An insight of traditional plasmid curing in Vibrio species.

    PubMed

    Letchumanan, Vengadesh; Chan, Kok-Gan; Lee, Learn-Han

    2015-01-01

    As the causative agent of foodborne related illness, Vibrio species causes a huge impact on the public health and management. Vibrio species is often associated with seafood as the latter plays a role as a vehicle to transmit bacterial infections. Hence, antibiotics are used not to promote growth but rather to prevent and treat bacterial infections. The extensive use of antibiotics in the aquaculture industry and environment has led to the emerging of antibiotic resistant strains. This phenomenon has triggered an alarming public health concern due to the increase number of pathogenic Vibrio strains that are resistant to clinically used antibiotics and is found in the environment. Antibiotic resistance and the genes location in the strains can be detected through plasmid curing assay. The results derived from plasmid curing assay is fast, cost effective, sufficient in providing insights, and influence the antibiotic management policies in the aquaculture industry. This presentation aims in discussing and providing insights on various curing agents in Vibrio species. To our best of knowledge, this is a first review written discussing on plasmid curing in Vibrio species.

  17. An insight of traditional plasmid curing in Vibrio species

    PubMed Central

    Letchumanan, Vengadesh; Chan, Kok-Gan; Lee, Learn-Han

    2015-01-01

    As the causative agent of foodborne related illness, Vibrio species causes a huge impact on the public health and management. Vibrio species is often associated with seafood as the latter plays a role as a vehicle to transmit bacterial infections. Hence, antibiotics are used not to promote growth but rather to prevent and treat bacterial infections. The extensive use of antibiotics in the aquaculture industry and environment has led to the emerging of antibiotic resistant strains. This phenomenon has triggered an alarming public health concern due to the increase number of pathogenic Vibrio strains that are resistant to clinically used antibiotics and is found in the environment. Antibiotic resistance and the genes location in the strains can be detected through plasmid curing assay. The results derived from plasmid curing assay is fast, cost effective, sufficient in providing insights, and influence the antibiotic management policies in the aquaculture industry. This presentation aims in discussing and providing insights on various curing agents in Vibrio species. To our best of knowledge, this is a first review written discussing on plasmid curing in Vibrio species. PMID:26347714

  18. Experimental and theoretical study of local curing on thermosetting resins using a CO2 laser

    NASA Astrophysics Data System (ADS)

    Scarparo, Marco A. F.; Munhoz, Andre L. J.; Wagner, Paulo R. S.; Ieradi, Maria C. F.; Kiel, Alvin E.; Allen, Susan D.

    1998-04-01

    We present a theoretical and experimental study of thermosetting resins used in thermal stereolithography. In usual practice, stereolithography makes use of photosensitive resins where HeCd (0.352 micrometers ) laser ultraviolet laser initiates the curing process. In this work we study the process of local curing through the application of infrared radiation, which has proved to be useful in a new technique for the making of prototypes by means of selective heating with a CO2 laser (10.6 micrometers ). The sample consists of a thermosetting resins (epoxy) with the curing agent (diethylene triamine) and a filler (silica). The ideal composition of the thermosetting resins has proved to be 10 parts epoxy, 1.4 part diethylene triamine (the curing agent) and 0.7 part silica powder. A physical theoretical model is applied for control of the parameters which influence the confinement of the curing in the irradiated bulk. A mathematical model was developed through the solution of the time dependent heat conduction equation in cylindrical co-ordinates, which enables the determination fo the behavior of curing in terms of irradiation conditions. An experimental analysis has determined the temperature range at which the curing process starts and the optimum silica concentration for efficient curing.

  19. Electromembrane extraction of diamine plastic restricted substances in soft drinks followed by capillary electrophoresis with contactless conductivity detection.

    PubMed

    Liu, Yan; Guo, Lin; Wang, Yu; Huang, Fengying; Shi, Jing; Gao, Ge; Wang, Xiaoxin; Ye, Jiannong; Chu, Qingcui

    2017-04-15

    Ethane-1,2-diamine (EA) and hexane-1,6-diamine (HA) are two important plastic restricted substances commonly existing in food contact materials. A capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C(4)D) method has been developed for direct determination of above analytes, and the detection sensitivity has been significantly improved based on electromembrane extraction (EME). Under the optimum conditions, EA and HA could be well separated from their aliphatic diamine homologs as well as the common inorganic cations within 25min. The limits of detection could reach sub-ng/mL level, and good linearity (r>0.998) between peak area and analyte concentration could be obtained at three orders of magnitude. This EME/CE-C(4)D method provided a novel application for determining these plastic restricted substances in different bottled soft drinks, providing an alternative for the sensitive analyses of diamine substances.

  20. Breather cloth for vacuum curing

    NASA Technical Reports Server (NTRS)

    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.

  1. Cleaner Vacuum-Bag Curing

    NASA Technical Reports Server (NTRS)

    Clemons, J. M.; Penn, B. G.; Ledbetter, Frank E., III; Daniels, J. G.

    1987-01-01

    Improvement upon recommended procedures saves time and expense. Autoclave molding in vacuum bag cleaner if adhesive-backed covering placed around caul plate as well as on mold plate. Covering easy to remove after curing and leaves caul plate free of resin deposits.

  2. Cure shrinkage in casting resins

    SciTech Connect

    Spencer, J. Brock

    2015-02-01

    A method is described whereby the shrinkage of a casting resin can be determined. Values for the shrinkage of several resin systems in frequent use by Sandia have been measured. A discussion of possible methods for determining the stresses generated by cure shrinkage and thermal contraction is also included.

  3. Dielectric Analysis of Thermoset Cure.

    DTIC Science & Technology

    1985-10-07

    the polymerization of thermosetting polymers, 3. Polyst . Sci., 31, 30S (1959) 58. Warfield, R. V. * Petro*, M. C.: A study of the polymerization of...cure: isothemal curs kinetics, Ihermochimica Acta, 14. 41 (1976) 64. ludd. N. C. W.: Investigation of the polymerization of an unsaturated polyester

  4. Polyimides formulated from a partially fluorinated diamine for aerospace tribological applications

    NASA Technical Reports Server (NTRS)

    Fusaro, R. L.

    1984-01-01

    Preliminary pribological studies on polyimides formulated from the diamine 2,2-bis 4-(4-aminophenoxy)phenyl hexafluoropane (4-BDAF) indicate that polyimides formulated from this diamine have excellent potential for high temperature tribological applications. The dianhydrides used to make the polyimides were pyromellitic (PMDA) and benzophenonetetracarboxylic acid (BTDA). Friction and wear studies at 25 and 200 C indicate that polyimides formulated using 50 mole percent of the PMDA dianhydride and 50 mole percent of the BTDA dianhydride perform better than polyimides formulated solely with the BTDA dianhydride. Graphite fiber reinforced polyimide composites were formulated with the polyimide made from the BTDA dianhydride and both graphitic and non-graphitic fibers were evaluated. Graphitic fibers produced better tribological results, since thin, flowing, 'layer-like' transfer films were produced which did not build up with long sliding durations. Non-graphitic fibers did not produce this type of transfer. Previously announced in STAR as N83-22423

  5. Polyimides formulated from a partially fluorinated diamine for aerospace tribological applications

    NASA Technical Reports Server (NTRS)

    Fusaro, R. L.

    1983-01-01

    Preliminary tribological studies on polyimides formulated from the diamine 2,2-bis 4-(4-aminophenoxy)phenyl hexafluorapane (4-BDAF) indicate that polyimides formulated from this diamine have excellent potential for high temperature tribological applications. The dianhydrides used to make the polyimides were pyromellitic (PMDA) and benzophenonetetracarboxylic acid (BTDA). Friction and wear studies at 25 and 200 C indicate that polyimides formulated using 50 mole percent of the PMDA dianhydride and 50 mole percent of the BTDA dianhydride perform better than polyimides formulated solely with the BTDA dianhydride. Graphite fiber reinforced polyimide composites were formulated with the polyimide made from the BTDA dianhydride, both graphitic and non-graphitic fibers were evaluated. Graphitic fibers produced better tribological results, since thin, flowing, "layer-like' transfer films were produced which did not build-up with long sliding durations. Non-graphitic fibers did not produce this type of transfer.

  6. Kinetic and solvent deuterium isotope effects in the oxidation of putrescine catalysed by enzyme diamine oxidase.

    PubMed

    Pałka, Katarzyna; Szymańska, Jolanta; Kańska, Marianna

    2013-01-01

    In this study, the kinetic isotope effects and solvent isotope effects in the reaction of the deamination of [(1R)-(2)H ] putrescine--catalysed by enzyme diamine oxidase (EC 1.4.3.6)--were determined using a non-competitive spectroscopic method. Putrescine, stereospecifically labelled with deuterium, was obtained by enzymatic decarboxylation of l-ornithine that was carried out in a fully deuteriated incubation medium.

  7. Synthesis of Chiral Vicinal Diamines by Silver(I)-Catalyzed Enantioselective Aminolysis of N-Tosylaziridines.

    PubMed

    Chai, Zhuo; Yang, Pei-Jun; Zhang, Hu; Wang, Shaowu; Yang, Gaosheng

    2017-01-09

    The kinetic resolution of 2-aryl-N-tosylaziridines and the asymmetric desymmetrization of meso-N-tosylaziridines by ring openings with various primary and secondary anilines, and aliphatic amines as nucleophile have been realized by using a single silver(I)/chiral diphosphine complex as catalyst for the first time. The simple starting materials, broad scope, and easy scalability render this protocol a practical way to chiral vicinal diamine derivatives.

  8. C2-Symmetric diamines and their derivatives as promising organocatalysts for asymmetric synthesis

    NASA Astrophysics Data System (ADS)

    Zlotin, S. G.; Kochetkov, S. V.

    2015-11-01

    The review is devoted to the application of C2-symmetric diamines and their derivatives as organocatalysts for asymmetric reactions (aldol, Michael, Mannich, Diels-Alder reactions, desymmetrization, allylation, etc.). Amino acid derivatives, di- and polyamides (sulfamides), bisureas, bisthioureas, bisamidines and bisguanidines are considered. Significant attention is given to the effect of the catalyst structure on the mechanism of catalytic action. Successful applications of such catalysts in enantioselective synthesis of chiral biologically active compounds are summarized. The bibliography includes 181 references.

  9. Synthesis of trifluoromethyl-containing vicinal diamines by asymmetric decarboxylative mannich addition reactions.

    PubMed

    Wu, Lingmin; Xie, Chen; Mei, Haibo; Dai, Yanling; Han, Jianlin; Soloshonok, Vadim A; Pan, Yi

    2015-03-20

    Herein is reported a study of asymmetric decarboxylative Mannich addition reactions between (Ss)-N-t-butylsulfinyl-3,3,3-trifluoroacetaldimine and Schiff bases derived from various aldehydes and lithium 2,2-diphenylglycinate. These reactions proceed with excellent diastereoselectivities and good chemical yields, providing a practical method for preparation of trifluoromethyl-containing vicinal diamines. The procedures can be conducted under convenient conditions, rendering this approach of high synthetic value.

  10. Novel syntheses of tetrahydrobenzodiazepines and dihydropyrazines via isocyanide-based multicomponent reactions of diamines.

    PubMed

    Shaabani, Ahmad; Maleki, Ali; Hajishaabanha, Fatemeh; Mofakham, Hamid; Seyyedhamzeh, Mozhdeh; Mahyari, Mojtaba; Ng, Seik Weng

    2010-01-01

    In this work, two novel isocyanide-based multicomponent reactions of 1,2-diamine compounds with diketene have been developed as efficient strategies for the synthesis of 2,3,4,5-tetrahydro-1H-benzo[b][1,4]diazepine-2-carboxamides with regiochemical control and 1,6-dihydropyrazine-2,3-dicarbonitriles in good to excellent yields at ambient temperature.

  11. Monodentate coordination of the normally chelating chiral diamine (R,R)-TMCDA.

    PubMed

    Ojeda-Amador, Ana I; Martínez-Martínez, Antonio J; Kennedy, Alan R; Armstrong, David R; O'Hara, Charles T

    2016-12-22

    After isolating an unusual binuclear, but monosolvated NaHMDS complex [{(R,R)-TMCDA}·(NaHMDS)2]∞ which polymerises via intermolecular electrostatic NaMeHMDS interactions, further (R,R)-TMCDA was added to produce the discrete binuclear amide [{κ(2)-(R,R)-TMCDA}·(NaHMDS)2{κ(1)-(R,R)-TMCDA}], whose salient feature is the unique monodentate coordination of one of the chiral diamine ligands.

  12. Action of Steroidal Diamines on Active Transport and Permeability Properties of Escherichia coli

    PubMed Central

    Silver, Simon; Levine, Elaine

    1968-01-01

    The steroidal diamine irehdiamine A (IDA) is a potent inhibitor of bacteriophage growth and macromolecular synthesis in Escherichia coli. By using radioactive 42K and 14C-thiomethylgalactoside (TMG), rapid effects of IDA and related steroids, both on the influx of potassium and TMG via their respective transport systems and on the efflux (leakage) of radioactivity from the treated cells, have been measured. IDA affects both the influx and efflux of 42K at concentrations of steroid as low as 2 × 10−5m. Because of the increased leakage, it is not possible to tell whether there is a direct effect reducing the rate of active transport of potassium. The primary diamine, IDA, and its bis-secondary, bis-tertiary, and bis-quaternary diamine analogues are decreasingly effective in altering cell permeability properties in the order 1° > 2° > 3° > 4°. The effects of IDA on potassium transport are mirrored by similar effects on the transport of TMG. Therefore, the action of IDA is on the cell membrane and not directly on one or another transport system. The effects of IDA on cell permeability can reasonably explain the inhibitory actions of the drugs on bacteriophage growth and cellular metabolism. PMID:4877122

  13. Rational design of catalysts for asymmetric diamination reaction using transition state modeling.

    PubMed

    Jindal, Garima; Sunoj, Raghavan B

    2014-05-07

    The stereoselective synthesis of 1,2-diamines has remained a formidable challenge. A recent palladium-catalyzed asymmetric diamination of conjugated double bonds using di-tert-butyldiaziridinone appears promising. The axially chiral binol phosphoramidite ligands are successful in offering high enantioselectivity. The density functional theory investigations revealed that the energies of the stereocontrolling transition states for the C-N bond formation depend on a number of weak non-covalent interactions such as C-H···π, C-H···O and anagostic interactions. We envisaged that the modulation in these interactions in the transition states, through subtle changes in chiral phosphoramidite substituents, could be exploited toward steering the stereoselectivity. The effect of systematic modifications on both 3,3' positions of the binol as well as on the amido nitrogen on the stereochemical outcome is predicted. It is identified that high enantioselectivity requires a balance between the nature of the substituents on binol and amido groups. The reduced size of the amido substituents demands increased bulk on the binol whereas lowering the size on the binol demands increased bulk on the amido for higher stereoselectivity. The substituent at the α-position of the amido group is found to be vital and appears to be a hot spot for modifications. These insights derived from studies on the stereocontrolling transition states could help improve the catalytic efficacies in palladium-catalyzed asymmetric diamination reactions.

  14. Chemical ionization of clusters formed from sulfuric acid and dimethylamine or diamines

    NASA Astrophysics Data System (ADS)

    Jen, Coty N.; Zhao, Jun; McMurry, Peter H.; Hanson, David R.

    2016-10-01

    Chemical ionization (CI) mass spectrometers are used to study atmospheric nucleation by detecting clusters produced by reactions of sulfuric acid and various basic gases. These instruments typically use nitrate to deprotonate and thus chemically ionize the clusters. In this study, we compare cluster concentrations measured using either nitrate or acetate. Clusters were formed in a flow reactor from vapors of sulfuric acid and dimethylamine, ethylene diamine, tetramethylethylene diamine, or butanediamine (also known as putrescine). These comparisons show that nitrate is unable to chemically ionize clusters with high base content. In addition, we vary the ion-molecule reaction time to probe ion processes which include proton-transfer, ion-molecule clustering, and decomposition of ions. Ion decomposition upon deprotonation by acetate/nitrate was observed. More studies are needed to quantify to what extent ion decomposition affects observed cluster content and concentrations, especially those chemically ionized with acetate since it deprotonates more types of clusters than nitrate.Model calculations of the neutral and ion cluster formation pathways are also presented to better identify the cluster types that are not efficiently deprotonated by nitrate. Comparison of model and measured clusters indicate that sulfuric acid dimers with two diamines and sulfuric acid trimers with two or more base molecules are not efficiently chemical ionized by nitrate. We conclude that acetate CI provides better information on cluster abundancies and their base content than nitrate CI.

  15. Cluster Formation of Sulfuric Acid with Dimethylamine or Diamines and Detection with Chemical Ionization

    NASA Astrophysics Data System (ADS)

    Jen, C. N.; McMurry, P. H.; Hanson, D. R.

    2015-12-01

    Chemical ionization (CI) mass spectrometers are used to study atmospheric nucleation by detecting clusters produced by reactions of sulfuric acid and various basic gases. These instruments typically use nitrate to chemically ionize clusters for detection. In this study, we compare measured cluster concentrations formed by reacting sulfuric acid vapor with dimethylamine, ethylene diamine, tetramethylethylene diamine, or butanediamine (also known as putrescine) using nitrate and acetate ions. We show from flow reactor measurements that nitrate is unable to chemically ionize clusters with weak acidities. In addition, we vary the ion-molecule reaction time to probe the chemical ionization processes and lifetimes of ions composed of sulfuric acid and base molecules. We then model the neutral and ion cluster formation pathways, including chemical ionization, ion-induced clustering, and ion decomposition, to better identify which cluster types cannot be chemically ionized by nitrate. Our results show that sulfuric acid dimer with two diamines and sulfuric acid trimer with 2 or more base molecules cannot be chemical ionized by nitrate. We conclude that cluster concentrations measured with acetate CI gives a better representation of both cluster abundancies and their base content than nitrate CI.

  16. Accelerated Cure Project for Multiple Sclerosis

    MedlinePlus

    ... 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 ...

  17. FDA Warns Against Bogus Autism 'Cures'

    MedlinePlus

    ... news/fullstory_164602.html FDA Warns Against Bogus Autism 'Cures' Unproven therapies won't help and could ... Don't fall for products claiming to cure autism, the U.S. Food and Drug Administration warns. There's ...

  18. Fluoride release from new light-cured orthodontic bonding agents.

    PubMed

    McNeill, C J; Wiltshire, W A; Dawes, C; Lavelle, C L

    2001-10-01

    The purpose of this study was to compare the rates of fluoride release with time from 1 nonfluoridated and 3 fluoride-containing orthodontic bonding materials in distilled water and artificial saliva. Materials tested were Assure (Reliance Orthodontic Products, Itasca, Ill), Fuji Ortho LC (GC, Tokyo, Japan), Python (TP Orthodontics, LaPorte, Ind), and Transbond XT (3M Dental Products, Monrovia, Calif). Ten specimens of each material type were stored in distilled water, and 10 of each type were stored in artificial saliva at 37 degrees C. Fluoride release was measured with an ion-specific electrode. Readings were taken periodically for a total time period of 6 months. At day 1, Assure released the most fluoride into distilled water (66.2 microg/cm(2)) and into artificial saliva (65.8 microg/cm(2)), followed by Fuji Ortho LC (25.9 microg/cm(2); 18.8 microg/cm(2)), Python (6.3 microg/cm(2); 4.2 microg/cm(2)), and Transbond (0.1 microg/cm(2); 0.1 microg/cm(2)). The fluoride release rates were highest during the first days of testing, declining to lower but more stable levels. At the end of 6 months, Fuji Ortho LC released the most fluoride (3.8 microg/cm(2); 3.5 microg/cm(2)) followed by Assure (3.1 microg/cm(2); 2.8 microg/cm(2)), Python (2.6 microg/cm(2); 1.7 microg/cm(2)), and Transbond (0.1 microg/cm(2); 0.1 microg/cm(2)). The type of storage medium did not dramatically affect fluoride release. The second part of the study, undertaken after a year of sample storage, tested the 20 samples of Assure for a further 2-week period, after exposure to running and still distilled water. Although fluoride release rates declined with time, they were still higher than the 1.5 microg/cm(2) level that is referenced as inhibiting decalcification of enamel in a clinical environment. Release rates were similar in running and still water at all time points. Throughout the 6-month period, all 3 fluoride-containing materials had rates of fluoride release that could theoretically inhibit decalcification of enamel.

  19. New composite nitrite-free and low-nitrite meat-curing systems using natural colorants

    PubMed Central

    Eskandari, Mohammad H; Hosseinpour, Sara; Mesbahi, GholamReza; Shekarforoush, Shahram

    2013-01-01

    Nitrite-free and low-nitrite meat-curing systems were developed to eliminate or reduce nitrite in frankfurter-type sausages. Different composite meat-curing mixtures were formulated using cochineal and paprika as natural colorants, sodium hypophosphite (SHP) as antimicrobial agent, butylated hydroxyanisole (BHA) as antioxidant and sodium nitrite. The treatment, which contained 0.015% cochineal, most closely resembled the 120 ppm NaNO2 in its ability to create cured-meat color. BHA was found to be a strong antioxidant at the 30 ppm level in cooked sausages during refrigerated storage for 5 weeks. All treatments containing 40 ppm sodium nitrite were successful in replicating sensory attributes of frankfurter samples. Our findings support the use of SHP as possible antibotulinal agent in nitrite-free meat-curing systems. PMID:24804046

  20. Effects of TiO₂ and curing temperatures on flame retardant finishing of cotton.

    PubMed

    Poon, Chin-Kuen; Kan, Chi-Wai

    2015-05-05

    The performance of flame retardancy of cotton cellulose can be influenced by curing conditions. In this study, cotton cellulose was imparted durable flame retardant properties by a reaction between a flame retardant agent (Pyrovatex CP New) and a cross linking agent (Knittex CHN), in the presence of catalysts phosphoric acid and titanium dioxide (TiO2). After treating cotton fabrics at different curing temperatures for different curing time, its flame retardant performance was evaluated by 45° fabric flammability standard test method. For cotton fabrics cured at 150 and 170°C, good flame retardant characteristics were retained even after three home laundering cycles. The use of TiO2 as a co-catalyst in the treatment improved the flame retardant properties and reduced the loss of tearing strength of cotton fabrics. No significant negative effect in the whiteness index was observed, as compared with conventional flame retardant treatment.

  1. Monitoring Polymer Curing Via Electromagnetic Impedance

    NASA Technical Reports Server (NTRS)

    Freeman, William T.; Covington, John C.; Kranbuehl, David E.; Hoff, Melanie; Delos, Susan

    1992-01-01

    New nondestructive in-situ electromagnetic-impedance measurement technique senses cure-processing properties of high-temperature, high-performance thermostat and thermoplastic resins. Continuous frequency-dependent measurement and analysis performed during curing cycle. Monitors and measures molecular properties of polymeric resin in liquid and solid states. Applications include nondestructive means for evaluation of materials, determination of "window" boundaries of curing cycles of thermoplastics and thermoset resins, and for online, closed-loop control of curing cycles.

  2. 7 CFR 51.1412 - Well cured.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Well cured. 51.1412 Section 51.1412 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Well cured. Well cured means that the kernel separates freely from the shell, breaks cleanly when...

  3. 7 CFR 51.1412 - Well cured.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Well cured. 51.1412 Section 51.1412 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Grades of Pecans in the Shell 1 Definitions § 51.1412 Well cured. Well cured means that...

  4. 7 CFR 51.1412 - Well cured.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Well cured. 51.1412 Section 51.1412 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Well cured. Well cured means that the kernel separates freely from the shell, breaks cleanly when...

  5. 7 CFR 51.1412 - Well cured.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Well cured. 51.1412 Section 51.1412 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Grades of Pecans in the Shell 1 Definitions § 51.1412 Well cured. Well cured means that...

  6. Idrothermal Aging of Ionizing Radiation Cured Epoxy Matrices for Carbon Fiber Composites

    NASA Astrophysics Data System (ADS)

    Conduruta, D.; Alessi, S.; Pitarresi, G.; Dispenza, C.; Lavalle, M.; Corda, U.; Spadaro, G.

    2008-08-01

    A poly(ethersulfone) (PES) engineering thermoplastic was used as toughening agent for an epoxy resin. Different percentages of PES in the resin were used, then cured by electron beam irradiation and some samples were thermally post-cured. The influence of the hydrothermal ageing on all types of samples was studied, measuring the water absorption percentage, the thermal properties, by dynamical mechanical thermal analysis (DMTA), and the toughness, by K|c measurements.

  7. Composite Curing Process Nondestructive Evaluation

    DTIC Science & Technology

    1988-06-01

    selected cure cycles, and conservative methods have been adopted to offset potentially degrading conditions. This approach invariably increases...fluoresce in ordinary solvents will, however, fluoresce strongly in viscous media such as glycerol at low temperatures. A number of studies on the...viscosity solvents is due to fasL nonradiative deactivation (relaxation) of the excited state by intramolecular torsional motions. When such torsional

  8. Hybrid Helmet Cure Cycle Optimization

    DTIC Science & Technology

    2008-02-01

    Distribution List 11 iv List of Figures Figure 1. DSC scans of cured and uncured carbon fiber-epoxy prepreg ...thermoplastic fabrics, molded with thermoset prepregs was designed at ARL. Proposed manufacturing of the helmet involved pressure molding a number...of plies of aramid fabric with a thermoplastic film, and two plies of carbon fiber-epoxy prepreg , BT250-E (Bryte Technologies, Inc.) that would add

  9. Curing of polymer thermosets via click reactions and on demand processes

    NASA Astrophysics Data System (ADS)

    Brei, Mark Richard

    In the first project, an azide functional resin and tetra propargyl aromatic diamines were fabricated for use as a composite matrix. These systems take already established epoxy/amine matrices and functionalize them with click moieties. This allows lower temperatures to be used in the production of a thermoset part. These new systems yield many better mechanical properties than their epoxy/amine derivatives, but their Tgs are low in comparison. The second project investigates the characterization of a linear system based off of the above azide functional resin and a difunctional alkyne. Through selectively choosing catalyst, the linear system can show regioselectivity to either a 1,4-disubstituted triazole, or a 1,5-disubstituted triazole. Without the addition of catalyst, the system produces both triazoles in almost an equal ratio. The differently catalyzed systems were cured and then analyzed by 1H and 13C NMR to better understand the structure of the material. The third project builds off of the utility of the aforementioned azide/alkyne system and introduces an on-demand aspect to the curing of the thermoset. With the inclusion of copper(II) within the azide/alkyne system, UV light is able to catalyze said reaction and cure the material. It has been shown that the copper(II) loading levels can be extremely small, which helps in reducing the copper's effect on mechanical properties The fourth project takes a look at polysulfide-based sealants. These sealants are normally cured via an oxidative reaction. This project took thiol-terminated polysulfides and fabricated alkene-terminated polysulfides for use as a thiol-ene cured material. By changing the mechanism for cure, the polysulfide can be cured via UV light with the use of a photoinitiator within the thiol/alkene polysulfide matrix. The final chapter will focus on a characterization technique, MALDI-TOF, which was used to help characterize the above materials as well as many others. By using MALDI-TOF, the

  10. High Flow Addition Curing Polyimides

    NASA Technical Reports Server (NTRS)

    Chuang, Kathy C.; Vannucci, Raymond D.; Ansari, Irfan; Cerny, Lawrence L.; Scheiman, Daniel A.

    1994-01-01

    A new series of high flow PMR-type addition curing polyimides was developed, which employed the substitution of 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (BTDB) for p-phenylenediamine (p -PDA) in a PMR-IL formulation. These thermoset polyimides, designated as 12F resins, were prepared from BTDB and the dimethyl ester of 4,4'- (hexafluo- roisopropylidene) -diphthalic acid (HFDE) with either nadic ester (NE) or p-aminostyrene (PAS) as the endcaps for addition curing. The 12F prepolymers displayed lower melting temperatures in DSC analysis, and higher melt flow in rheological studies than the cor- responding PMR-11 polyimides. Long-term isothermal aging studies showed that BTDB- based 12F resins exhibited comparable thermo-oxidative stability to P-PDA based PMR-11 polyimides. The noncoplanar 2- and 2'-disubstituted biphenyldiamine (BTDB) not only lowered the melt viscosities of 12F prepolymers, but also retained reasonable thermal sta- bility of the cured resins. The 12F polyimide resin with p-aminostyrene endcaps showed the best promise for long-term, high-temperature application at 343 C (650 F).

  11. Cure shrinkage of thermoset composites

    SciTech Connect

    Russell, J.D. )

    1993-01-01

    The shrinkage of thermoset composites during cure was studied using a volumetric dilatometer. The material systems studied were AS4 carbon fiber/Hercules' 3501-6 epoxy, IM7 carbon fiber/Hercules 8551-7A toughened epoxy and IM7 carbon fiber/BASF's 5250-4 bismaleimide. Shrinkage of the samples due to both polymerization and thermal expansion effects was seen. The volume changes of the materials during cure were then compared to results from dynamic mechanical analysis (DMA) and dielectric cure monitoring. Maximums in volume corresponded to minimums in storage and loss modulus from DMA and maximums in the dielectric loss factor. Resin shrinkage during the 177 deg C (350 F) hold corresponded to the onset of polymerization seen by the rapid increase in the storage modulus and the decrease in the dielectric loss factor response due to reduced ion mobility. These results show that volumetric dilatometry can be an effective tool in the development of materials processing strategies and can be useful in studying residual stresses in composites. 9 refs.

  12. Synthesis, spectroscopic characterization, electrochemical behavior and computational analysis of mixed diamine ligand gold(III) complexes: antiproliferative and in vitro cytotoxic evaluations against human cancer cell lines.

    PubMed

    Al-Jaroudi, Said S; Monim-ul-Mehboob, M; Altaf, Muhammad; Al-Saadi, Abdulaziz A; Wazeer, Mohammed I M; Altuwaijri, Saleh; Isab, Anvarhusein A

    2014-12-01

    The gold(III) complexes of the type [(DACH)Au(en)]Cl3, 1,2-Diaminocyclohexane ethylenediamine gold(III) chloride [where 1,2-DACH = cis-, trans-1,2- and S,S-1,2diaminocyclohexane and en = ethylenediamine] have been synthesized and characterized using various analytical and spectroscopic techniques including elemental analysis, UV-Vis and FTIR spectra; and solution as well as solid-state NMR measurements. The solid-state (13)C NMR shows that 1,2-diaminocyclohexane (1,2-DACH) and ethylenediamine (en) are strongly bound to the gold(III) center via N donor atoms. The stability of the mixed diamine ligand gold(III) was determined by (1)H and (13)C NMR spectra. Their electrochemical behavior was studied by cyclic voltammetry. The structural details and relative stabilities of the four possible isomers of the complexes were also reported at the B3LYP/LANL2DZ level of theory. The coordination sphere of these complexes around gold(III) center adopts distorted square planar geometry. The computational study also demonstrates that trans- conformations is slightly more stable than the cis-conformations. The antiproliferative effects and cytotoxic properties of the mixed diamine ligand gold(III) complexes were evaluated in vitro on human gastric SGC7901 and prostate PC3 cancer cells using MTT assay. The antiproliferative study of the gold(III) complexes on PC3 and SGC7901 cells indicate that complex 1 is the most effective antiproliferative agent among mixed ligand based gold(III) complexes 1-3. The IC50 data reveal that the in vitro cytotoxicity of complexes 1 and 3 against SGC7901 cancer cells are fairly better than that of cisplatin.

  13. Photo-Curing: UV Radiation curing of polymers

    NASA Technical Reports Server (NTRS)

    Inman, Christina A.

    2004-01-01

    The Polymers Branch of the Materials Division is dedicated to the development of high-performance for a variety of applications. Areas of significant interest include high- temperature polymers, low density, and high strength insulating materials, conductive polymers, and high density polymer electrolytes. This summer our group is working diligently on a photo-curing project. There is interest in the medical community feel the need for a new and improved balloon that will be used for angioplasty (a form of heart surgery). This product should maintain flexibility but add many other properties. Like possibly further processability and resistance to infection. Our group intends on coming up with this product by using photo-enolization (or simply, photo-curing) by Diels-Alder trapping. The main objective was to synthesize a series of new polymers by Diels-Alder cycloaddition of photoenols with more elastomeric properties. Our group was responsible for performing the proper photo-curing techniques of the polymers with diacrylates and bismaleimides, synthesizing novel monomers, and evaluating experimental results. We attempted to use a diacrylate to synthesize the polymer because of previous research done within the Polymers Branch here at NASA. Most acrylates are commercially available, have more elastometric properties than a typical rigid aromatic structure has and they contain ethylene oxides in the middle of their structure that create extensive flexibility. The problem we encountered with the acrylates is that they photo chemically and thermally self polymerize and create diradicals at low temperatures; these constraints caused a lot of unnecessary side reactions. We want to promote solely, diketone polymerization because this type of polymerization has the ability to cause very elastic polymers. We chose to direct our attention towards the usage of maleimides because they are known for eliminating these unnecessary side reactions.

  14. Curing depth of composite resin light cured by LED and halogen light-curing units

    NASA Astrophysics Data System (ADS)

    Calixto, L. R.; Lima, D. M.; Queiroz, R. S.; Rastelli, A. N. S.; Bagnato, V. S.; Andrade, M. F.

    2008-11-01

    The purpose of this study was to evaluate the polymerization effectiveness of a composite resin (Z-250) utilizing microhardness testing. In total, 80 samples with thicknesses of 2 and 4 mm were made, which were photoactivated by a conventional halogen light-curing unit, and light-curing units based on LED. The samples were stored in water distilled for 24 h at 37°C. The Vickers microhardness was performed by the MMT-3 microhardness tester. The microhardness means obtained were as follows: G1, 72.88; G2, 69.35; G3, 67.66; G4, 69.71; G5, 70.95; G6, 75.19; G7, 72.96; and G8, 71.62. The data were submitted to an analysis of variance (ANOVA’s test), adopting a significance level of 5%. The results showed that, in general, there were no statistical differences between the halogen and LED light-curing units used with the same parameters.

  15. Synthesis, crystal structure and characterization of novel open framework CHA-type aluminophosphate involving a chiral diamine.

    PubMed

    Komura, Kenichi; Horibe, Yukiko; Yajima, Hiroaki; Hiyoshi, Norihito; Ikeda, Takuji

    2016-09-27

    A highly crystalline new precursor of CHA-type zeolite AlPO4-34 was obtained by using an aluminophosphate gel with a chiral diamine [(S)-(+)-1-(2-pyrrolidinylmethyl)pyrrolidine; C9H18N2] as an organic structure directing agent under hydrothermal synthesis conditions. This precursor (called GAM-1) was changed into the zeolite AlPO4-34 which had a high porosity (the Brunauer-Emmett-Teller (BET) surface area is approximately 700 m(3) g(-1)) using calcination. The GAM-1 obtained was characterized by various measurements, e.g., powder X-ray diffraction, scanning electron microscopy, and solid-state nuclear magnetic resonance spectroscopy, and so on. Structure determination from powder diffraction data revealed that the new precursor GAM-1 has triclinic symmetry [space group P1[combining macron], a = 9.16535(11) Å, b = 9.23042(11) Å, c = 9.29228(11) Å, α = 79.8243(7)°, β = 87.4593(7)°, γ = 86.5365(7)°] and the chemical formula was estimated to be: |Al6P6O24H2F2|(C9H18N2)·2.5(H2O). It also revealed that a two edge sharing AlO4F2 octahedron with an [triple bond, length as m-dash]Al-F-Al[triple bond, length as m-dash] bridge was included in the framework. GAM-1 was transformed into AlPO4-34 with rhombohedral symmetry (R3[combining macron]) by elevating temperature to over 400 °C. At high temperatures, AlO4F2 octahedron connectivity was changed into an AlO4 tetrahedron. The crystal structure of the dehydrated AlPO4-34 changed back to a triclinic symmetry (P1) model again after rehydration in the atmosphere.

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

    PubMed

    Passos, Sheila Pestana; Souza, Rodrigo Othávio Assunção; Michida, Silvia Masae Araújo; Zamboni, Sandra Costa; Oliveira, Simone Helena Gonçalves de

    2013-01-01

    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 (6.40)ab; G2 - 12.02 (4.59)ab; G3 - 13.09 (5.62)ab; G4 - 15.96 (6.32)a; G5 - 6.22 (5.90)c; G6 - 9.48 (5.99)bc; G7 - 12.78 (11.30)ab; and G8 - 8.34 (5.98)bc. 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.

  17. High temperature resistant polyimide from tetra ester, diamine, diester and N-arylnadimide

    NASA Technical Reports Server (NTRS)

    Pater, R. H. (Inventor)

    1985-01-01

    The invention described relates to improved polyimide resins which are noted for their high thermal and oxidative stability, high strength at elevated temperatures and which exhibit many other outstanding physical and chemical properties, especially useful in high temperature applications. The polyimides are prepared by the reaction, with application of heat of a mixture of monomers comprising: (1) a dialkyl or tetraalkyl ester of an aromatic tetracarboxylic acid, (2) and aromatic diamine, (3) a monoalkyl or dialky ester of a dicarboxylic acid, and (4) a N-arylnadimide such as N-phenylnadimide. Polyimides of monomers (1), (2) and (3) are known.

  18. Copper-catalyzed aerobic oxidative coupling: From ketone and diamine to pyrazine

    PubMed Central

    Wu, Kun; Huang, Zhiliang; Qi, Xiaotian; Li, Yingzi; Zhang, Guanghui; Liu, Chao; Yi, Hong; Meng, Lingkui; Bunel, Emilio E.; Miller, Jeffrey T.; Pao, Chih-Wen; Lee, Jyh-Fu; Lan, Yu; Lei, Aiwen

    2015-01-01

    Copper-catalyzed aerobic oxidative C–H/N–H coupling between simple ketones and diamines was developed toward the synthesis of a variety of pyrazines. Various substituted ketones were compatible for this transformation. Preliminary mechanistic investigations indicated that radical species were involved. X-ray absorption fine structure experiments elucidated that the Cu(II) species 5 coordinated by two N atoms at a distance of 2.04 Å and two O atoms at a shorter distance of 1.98 Å was a reactive one for this aerobic oxidative coupling reaction. Density functional theory calculations suggested that the intramolecular coupling of cationic radicals was favorable in this transformation. PMID:26601302

  19. Determining Chiral Configuration of Diamines via Contact Angle Measurements on Enantioselective Alanine-Appended Benzene-Tricarboxamide Gelators.

    PubMed

    Jung, Sung Ho; Kim, Ka Young; Ahn, Ahreum; Choi, Myong Yong; Jaworski, Justyn; Jung, Jong Hwa

    2016-06-08

    Spectroscopic techniques exist that may discern between enantiomers and assess chiral purity. A nonspectroscopic approach that may be directly observed could provide numerous benefits. Using chiral alanine-appended benzene-tricarboxamide gelators, we reveal a methanol gel system that is capable of providing visual discrimination between enantiomers of various diamines. Specifically, gelation is induced by supramolecular nanofiber assembly resulting from interaction between a chiral gelator and a diamine of opposing chirality (i.e., a heterochiral system). Upon further implementing the chiral gelator in electrospun fibers as solid state films, we revealed enantioselective surface wetting properties that allowed for determining chirality through contact angle measurements. While these two approaches of observable gelation and surface wetting offer nonspectroscopic approaches, we also find that the supramolecular nanofiber assembly was able to enhance the induced circular dichroism signal resulting from addition of chiral diamines, allowing precise quantification of their enantiomeric purity.

  20. Chromothriptic Cure of WHIM Syndrome

    PubMed Central

    McDermott, David H.; Gao, Ji-Liang; Liu, Qian; Siwicki, Marie; Martens, Craig; Jacobs, Paejonette; Velez, Daniel; Yim, Erin; Bryke, Christine R.; Hsu, Nancy; Dai, Zunyan; Marquesen, Martha M.; Stregevsky, Elina; Kwatemaa, Nana; Theobald, Narda; Long Priel, Debra A.; Pittaluga, Stefania; Raffeld, Mark A.; Calvo, Katherine R.; Maric, Irina; Desmond, Ronan; Holmes, Kevin L.; Kuhns, Douglas B.; Balabanian, Karl; Bachelerie, Françoise; Porcella, Stephen F.; Malech, Harry L.; Murphy, Philip M.

    2015-01-01

    Summary Chromothripsis is a catastrophic cellular event recently described in cancer in which chromosomes undergo massive deletion and rearrangement. Here we report a case in which chromothripsis spontaneously cured a patient with WHIM syndrome, an autosomal dominant combined immunodeficiency disease caused by gain-of-function mutation of the chemokine receptor CXCR4. In this patient, deletion of the disease allele, CXCR4R334X, as well as 163 other genes from one copy of chromosome 2 occurred in a hematopoietic stem cell (HSC) that repopulated the myeloid but not the lymphoid lineage. In competitive mouse bone marrow (BM) transplantation experiments, Cxcr4 haploinsufficiency was sufficient to confer a strong long-term engraftment advantage of donor BM over BM from either wild-type or WHIM syndrome model mice, suggesting a potential mechanism for the patient’s cure. Our findings suggest that partial inactivation of CXCR4 may have general utility as a strategy to promote HSC engraftment in transplantation. PMID:25662009

  1. New epoxy/episulfide resin system for electronic and coating applications: Curing mechanisms and properties

    NASA Astrophysics Data System (ADS)

    Tsuchida, Katsuyuki

    This work involves research on a new resin system useful for printed circuit board and protective coating applications. The system provides excellent adhesion to copper and corrosion resistance for copper. The research involved detailed studies of the reaction mechanisms, and correlation of these mechanisms with the observed properties. The epoxy/episulfide system, when used with a dicyandiamide (DICY) curing agent, exhibits better adhesion to copper substrate, a better pot life and prepreg storage life, a lower thermal expansion coefficient, a lower heat of reaction, a lower degradation temperature, and higher water absorption as compared with the standard epoxy system. From model compound studies, the sulfur of the opened episulfide ring reacts with copper, resulting in a durable bond between the copper and matrix resin even after water boiling. Since the S- formed by the reaction of the episulfide with the curing agent easily reacts with both the episulfide and the epoxy, a C-S-C bond is formed and more unreacted curing agent remains as compared to the standard epoxy system. The new bond formation causes a lower thermal expansion coefficient and somewhat lower degradation temperature. The unreacted curing agent causes slightly higher water absorption. Since the episulfide ring has less stress than the epoxy ring the epoxy/episulfide system shows lower heat of reaction, i.e., a lower exotherm. and lower shrinkage. The epoxy/episuffide system, when used with a polyamide curing agent, exhibits better corrosion protection for copper substrates, a lower thermal expansion coefficient and a lower degradation temperature. From model compound studies, the curing reactions are changed by changing curing temperature and the presence of copper: the episulfide homopolymerization and the S--epoxy reactions increase in the case of room temperature curing or in the presence of copper. In the presence of copper, the sulfur of the episulfide also reacts with copper, although the

  2. Chemical reactivity of C-F bonds attached to graphene with diamines depending on their nature and location.

    PubMed

    Li, Baoyin; He, Taijun; Wang, Zaoming; Cheng, Zheng; Liu, Yang; Chen, Teng; Lai, Wenchuan; Wang, Xu; Liu, Xiangyang

    2016-06-29

    The attachment of fluorine to graphene is a facile means to activate the carbon bonds for subsequent covalent bonding to other molecules for the preparation of desired graphene derivatives. Therefore, an insight into the chemical reactivity of fluorinated graphene (FG) is very essential to enable precise control of the composition and structure of the final products. In this study, FG has been treated with various mass amounts of poly(oxypropylene)diamine (PEA) ranging from starvation to saturation to explore the dependence of a substitution reaction of diamines on the nature and location (attached onto the basal planes or along defects or edges) of C-F bonds. X-ray photoelectron spectroscopy directly tracked the atomic percentage of fluorine present and the carbon 1s bonding state, showing that the grafting ratio of diamines gradually increases with increased diamine mass ratio. The varying of the types and orientation of C-F bonds characterized by polarized attenuated total reflectance Fourier transform infrared spectroscopy indicates that "covalent" C-F bonds are more sensitive to the substitution reaction of diamines than ''semi-ionic'' C-F bonds, and the C-F bonds attached onto basal planes more preferably participate in the functionalization reaction of diamines than that of C-F bonded on non-coplanar regions (edges or defects). The one-dimensional expansion along the graphene c-axis shown by wide angle X-ray diffraction provides further evidence on the preferred functionalization reaction of C-F attached on the basal planes, resulting in a change of the average intersheet distance by various magnitudes.

  3. ASRM test report: Autoclave cure process development

    NASA Technical Reports Server (NTRS)

    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.

  4. ASRM test report: Autoclave cure process development

    NASA Astrophysics Data System (ADS)

    Nachbar, D. L.; Mitchell, Suzanne

    1992-05-01

    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.

  5. Synthesis and photoreaction of Schiff bases derived from p-nitro cinnamaldehyde and diamines in Langmuir and Langmuir Blodgett films

    NASA Astrophysics Data System (ADS)

    Kanthimathi, Mookandi; Dhathathreyan, Aruna

    2003-01-01

    Monolayers of Schiff bases derived from ethylene diamine and o-phenylene diamine with p-nitro cinnamaldehyde, (compounds 1 and 2) at air/water interface have been studied. Photolysis of 1 in chloroform solution undergoes cis- trans isomerization on irradiation of white light while compound 2 does not undergo isomerization under photolytic conditions. The photolysis of 1 and 2 in Langmuir-Blodgett films (LB films) transferred to quartz plates form dimers. The change in product distribution is attributed to the influence of bridging group of the cinnamaldehyde moieties, molecular configuration and mobility of the compounds in solution, solid state and the aggregation of molecules in monolayer assemblies.

  6. Interfacial Properties of Electron Beam Cured Composites

    SciTech Connect

    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.

  7. Process for preparing essentially colorless polyimide film containing phenoxy-linked diamines

    NASA Technical Reports Server (NTRS)

    Stclair, A. K.; Stclair, T. L.

    1986-01-01

    A polyimide film that is approximately 90% transparent at 500 nm, useful for thermal protective coatings and solar cells, and the processes for preparing the same by thermal and chemical conversion are disclosed. An essential feature for achieving maximum optical transparency films requires utilizing recrystallized and/or sublimated specific aromatic diamines and dianhydride monomers and introducing phenoxy or thiophenyl separator groups and isomeric m,m' or o,p'-oriented diamines into the polymer molecular structure. The incorporation of these groups in the polymer structure serves to separate the chromaphoric centers and reduce the formation of inter-chain and intra-chain charge transfer complexes which normally cause absorptions in the UV-visible range. The films may be obtained by hand, brushing, casting, or spraying a layer of polyamic acid solutions onto a surface and thermally converting the applied layer to the polyimide, or the polyamic acid solution can be chemically converted to the polyimide, subsequentially dissolved in an organic solvent, and applied as a polyimide film layer with the solvent therein thermally removed.

  8. Interaction of linear mono- and diamines with dimyristoylphosphatidylcholine and dimyristoylphosphatidylglycerol multilamellar liposomes.

    PubMed

    Momo, F; Fabris, S; Stevanato, R

    2000-10-15

    The effect of linear monoamines on dimyristoylphosphatidylglycerol and dimyristoylphosphatidylcholine multilamellar liposomes was studied as a function of their length and compared with the behavior of linear carboxylic acids. The role of the hydrophobic interactions was demonstrated and the free energy of the binding for each interacting carbon atom was determined. The thermotropic behavior of the liposomes was characterized by differential scanning calorimetry and it was shown that these molecules affect the temperature and the cooperativity of the gel to fluid state transition of the membrane differently. In particular, it appeared that membrane perturbation was maximum when the chain length of the amphipathic molecules ranged between 7 and 9 carbon atoms, with more pronounced effects in the case of monoamines. Molecules shorter than 3-4 carbon atoms did not produce any observable change in the transition temperature. The study was extended to linear alpha,omega-diamines to investigate the amphipathic character of long diamines and to investigate the role of bridging bonds established with neighboring phospholipids.

  9. Aromatic Diamines and Polyimides Based on 4,4'-Bis-(4-Aminophenoxy)-2,2' or 2,2',6,6'- Substituted Biphenyl

    NASA Technical Reports Server (NTRS)

    Chuang, Chun-Hua K. (Inventor)

    2000-01-01

    This invention relates the novel diamines. the polyimide oligomers and the polyimides derived therefrom and to the method of preparing the diamines, oligomers and the polyimides. The thermoplastic polyimides derived from the aromatic diamines of this invention are characterized as having a high glass transition temperature. good mechanical properties and improved processability in the manufacture of adhesives. electronic and composite materials for use in the automotive and aerospace industry. The distinction of the novel aromatic diamines of this invention is the 2.2',6.6substituted biphenyl radicals which exhibit noncoplanar conformation that enhances the solubility of the diamine as well as the processability of the polyimides. while retaining a relatively high glass transition temperature and improved mechanical properties at useful temperature ranges.

  10. New "cures" for ailing communications.

    PubMed

    Johnston, B

    1988-07-01

    The benefits of voice processing technologies applied "one piece at a time" in the proper fashion can provide four "cures" to communications problems: The image of the healthcare facility in the eyes of the public will improve because calls are handled more quickly, efficiently, and professionally than before. Providing faster patient care information and eliminating delays in medical staff and personnel communications creates the opportunity to give better patient care and customer service. Elimination of time wasting "telephone tag" and "memo blizzards" will result in an increase in employee productivity. Personnel can be reassigned to more productive tasks. The net effect of voice processing on the healthcare industry is a continued merging of computers and telephones, resulting in a voice capability system which includes the telephone system, the call processing system, the voice messaging system, the voice response system, and the host computer system, all being accessed by the same terminal. Just the basic plain-vanilla touchtone telephone will handle it all.

  11. Invasive Scedosporium sternal osteomyelitis following lung transplant: Cured.

    PubMed

    Denton, E J; Smibert, O; Gooi, J; Morrissey, C O; Snell, G; McGiffin, D; Paraskeva, M

    2016-06-01

    Scedosporium is an important pathogen in cystic fibrosis (CF) and post-transplant but rarely causes invasive infection. Treatment remains challenging, particularly due to inherent resistance to multiple antifungal agents. We present a young man with CF who developed invasive sternal and rib infection 10-months following lung transplant. The infection has been clinically and radiologically cured with extensive surgery and triazole therapy. This case highlights the importance of adjunctive surgery in addition to prolonged triazole treatment to manage invasive Scedosporium infections in immunosuppressed patients.

  12. Ohmic Curing of Printed Silver Conductive Traces

    NASA Astrophysics Data System (ADS)

    Roberson, D. A.; Wicker, R. B.; MacDonald, E.

    2012-09-01

    Ohmic heating was demonstrated as a novel curing method (or curing enhancement) useful in decreasing the resistivity of conductive traces printed with both micro- and nanoparticle-loaded inks while (1) only locally heating the substrate and (2) curing in a matter of seconds compared with the range of 30 min to 1 h required by traditional oven-curing. In one experiment using traces composed of microparticle ink, which required initial air-drying as a preprocess step, application of an ohmic curing cycle resulted in resistivity of 80 nΩ m, roughly six times that of bulk silver. In a second experiment employing nanoparticle inks, which required an initial thermal cure as a preprocess, a resistivity of 43 nΩ m, roughly three times that of bulk silver, was attained after the application of an ohmic curing cycle. Electrical characterization of the ohmic curing process was performed in real time to understand the impact of cycling and duration on the resulting conductivity. Finally, the effect of printed trace length on the ohmic curing process was explored and found to have a near-linear relationship with the reduction in resistance when the applied electrical current was normalized to measured resistance. The microstructural changes which occurred as a result of ohmic curing such as particle sintering and grain growth were characterized by scanning electron microscopy. The results presented in this work demonstrate the use of ohmic heating to overcome temperature limitations imposed on a thermal curing process by substrate material properties or other sources.

  13. Ligand binding studies, preliminary structure-activity relationship and detailed mechanistic characterization of 1-phenyl-6,6-dimethyl-1,3,5-triazine-2,4-diamine derivatives as inhibitors of Escherichia coli dihydrofolate reductase

    PubMed Central

    Srinivasan, Bharath; Tonddast-Navaei, Sam; Skolnick, Jeffrey

    2015-01-01

    Gram-negative bacteria are implicated in the causation of life-threatening hospital-acquired infections. They acquire rapid resistance to multiple drugs and available antibiotics. Hence, there is the need to discover new antibacterial agents with novel scaffolds. For the first time, this study explores the 1,3,5-triazine-2,4-diamine and 1,2,4-triazine-2,4-diamine group of compounds as potential inhibitors of E. coli DHFR, a pivotal enzyme in the thymidine and purine synthesis pathway. Using differential scanning fluorimetry, DSF, fifteen compounds with various substitutions on either the 3rd or 4th positions on the benzene group of 6,6-dimethyl-1-(benzene)-1,3,5-triazine-2,4-diamine were shown to bind to the enzyme with varying affinities. Then, the dose dependence of inhibition by these compounds was determined. Preliminary quantitative structure-activity relationship analysis and docking studies implicate the alkyl linker group and the sulfonyl fluoride group in increasing the potency of inhibition. 4-[4-[3-(4,6-diamino-2,2-dimethyl-1,3,5-triazin-1-yl)phenyl]butyl]benzenesulfonyl fluoride (NSC120927), the best hit from the study and a molecule with no reported inhibition of E. coli DHFR, potently inhibits the enzyme with a Ki value of 42.50 ± 5.34 nM, followed by 4-[6-[4-(4,6-diamino-2,2-dimethyl-1,3,5-triazin-1-yl)phenyl]hexyl]benzenesulfonyl fluoride(NSC132279), with a Ki value of 100.9 ± 12.7 nM. Detailed kinetic characterization of the inhibition brought about by five small-molecule hits shows that these inhibitors bind to the dihydrofolate binding site with preferential binding to the NADPH-bound binary form of the enzyme. Furthermore, in search of novel diaminotriazine scaffolds, it is shown that lamotrigine, a 1,2,4-triazine-3,5-diamine and a sodium-ion channel blocker class of antiepileptic drug, also inhibits E. coli DHFR. This is the first comprehensive study on the binding and inhibition brought about by diaminotriazines of a gram

  14. Synthesis, structure, and properties of a series of chiral tweezer-diamine complexes consisting of an achiral zinc(II) bisporphyrin host and chiral diamine guest: induction and rationalization of supramolecular chirality.

    PubMed

    Brahma, Sanfaori; Ikbal, Sk Asif; Rath, Sankar Prasad

    2014-01-06

    We report here the synthesis, structure, and spectroscopic properties of a series of supramolecular chiral 1:1 tweezer-diamine complexes consisting of an achiral Zn(II) bisporphyrin (Zn2DPO) host and five different chiral diamine guests, namely, (R)-diaminopropane (DAP), (1S,2S)-diaminocyclohexane (CHDA), (S)-phenylpropane diamine (PPDA), (S)-phenyl ethylenediamine (PEDA), and (1R,2R)-diphenylethylene diamine (DPEA). The solid-state structures are preserved in solution, as reflected in their (1)H NMR spectra, which also revealed the remarkably large upfield shifts of the NH2 guest protons with the order Zn2DPO·DAP > Zn2DPO·CHDA > Zn2DPO·PPDA> Zn2DPO·PEDA ≫ Zn2DPO·DPEA, which happens to be the order of binding constants of the respective diamines with Zn2DPO. As the bulk of the substituent at the chiral center of the guest ligand increases, the Zn-Nax distance of the tweezer-diamine complex also increases, which eventually lowers the binding of the guest ligand toward the host. Also, the angle between the two porphyrin rings gradually increases with increasing bulk of the guest in order to accommodate the guest within the bisporphyrin cavity with minimal steric clash. The notably high amplitude bisignate CD signal response by Zn2DPO·DAP, Zn2DPO·CHDA, and Zn2DPO·PPDA can be ascribed to the complex's high stability and the formation of a unidirectional screw as observed in the X-ray structures of the complexes. A relatively lower value of CD amplitude shown by Zn2DPO·PEDA is due to the lower stability of the complex. The projection of the diamine binding sites of the chiral guest would make the two porphyrin macrocycles oriented in either a clockwise or anticlockwise direction in order to minimize host-guest steric clash. In sharp contrast, Zn2DPO·DPEA shows a very low amplitude bisignate CD signal due to the presence of both left- (dictated by the pre-existing chirality of (1R,2R)-DPEA) and right-handed screws (dictated by the steric differentiation at

  15. 1H-nuclear magnetic resonance determination of the enantiomeric purity of aliphatic primary amines, β-aminoalcohols, β-diamines and α-amino-acids with 1 R-(-)-myrtenal: scope and limitations

    NASA Astrophysics Data System (ADS)

    Dufrasne, François; Gelbcke, Michel; Nève, Jean

    2003-04-01

    1 R-(-)-myrtenal was tested as a chiral derivatising agent for the determination of the enantiomeric purity of aliphatic primary amines, β-aminoalcohols, β-diamines and α-amino-acids. Derivatisation procedure consists in mixing one equivalent each of the amine and 1 R-(-)-myrtenal directly into the nuclear magnetic resonance (NMR) tube before addition of the appropriate deuterated solvent and, for α-amino-acids, one equivalent of NaOH was added to neutralise the acidic function. Diastereoisomeric imines were completely formed after 12 h and analysed by 1H-NMR except for N-methyl β-diamines for which imidazolidines were obtained. The method gave satisfactory results only for α- and β-arylalkylamines for which CDCl 3 could be advantageously replaced by C 6D 6 or pyridine- d5 in order to increase the difference between the chemical shifts. The main advantage of the procedure is its simplicity as it does not involve steps such as activation, heating, solvent evaporation and isolation of the product. Its limitations are the limited series of compounds susceptible to be analysed and the small difference between the chemical shifts of the diastereoisomeric imines obtained.

  16. 7 CFR 29.6010 - Cured.

    Code of Federal Regulations, 2010 CFR

    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...

  17. Evaluation of Degreasers as Brine Curing Additives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The length of time needed for brine curing of raw hides and skins, a minimum of 18 h, is a time-consuming and expensive process. In this paper we initially report the results of an investigation of the stratigraphic distribution of sodium chloride and water in fleshed hides cured for varying interv...

  18. Curing of Graphite/Epoxy Composites.

    DTIC Science & Technology

    1983-03-01

    365-371 (1973). 21. Pappalardo , L. T., "DSC Evaluation of B-Stage Epoxy-Glass Prepregs For Multilayer Boards," SPE Technical Papers, 20, 13-16 (1974...Kamal, M. R., "Differential Scanning Calorimetry of Epoxy Cure: Isothermal Cure Kinetics," Thermochimica Acta, 14, 41-59 (1976). 24. Pappalardo , L. T

  19. Polyamines and cellular metabolism in plants: Transgenic approaches reveal different responses to diamine putrescine versus higher polyamines spermidine and spermine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Distribution of biogenic amines – the diamine putrescine (Put), triamine spermidine (Spd), and tetraamine spermine (Spm) - differs between species with Put and Spd being particularly abundant and Spm the least abundant in plant cells. These amines are important for cell viability and their intracel...

  20. Visual determination of aliphatic diamines based on host-guest recognition of calix[4]arene derivatives capped gold nanoparticles.

    PubMed

    Chen, Yangyang; Zhang, Jiangjiang; Gao, Yanmin; Lee, Jaebeom; Chen, Hongxia; Yin, Yongmei

    2015-10-15

    Since amine compounds have been widespread pollutants in nature and they are extensively used in pharmaceutical industries and dye manufacturing, it is highly desirable to develop simple, effective and naked-eye available analytical methods for such aliphatic diamines determination. Calixarenes as macrocycles have drawn intensive interests for fields such as biomedicine, supramolecular chemistry and smart materials. Here, instead of the normal complicated modification strategy, a facile and efficient method for one-pot synthesis of calix[4]arene crown ether (CCE4) capped gold nanoparticles (AuNPs) is proposed. The as-prepared CCE4-AuNPs are not only high water dispersity and stability even after storage for 3 months, but also capable of host-guest recognition of diamines in aqueous systems. Size-selective encapsulation of amine group between CCE4 and diamines carry out the aggregation of CCE4-AuNPs. The determination of diamines such as hexamethylenediamine or spermine can be realized by the UV-vis absorbance change and visual color difference.

  1. A dramatic synergistic effect of a flexible achiral linker on a rigid chiral cis-1,2-diamine bifunctional organocatalyst.

    PubMed

    Matsunaga, Hirofumi; Tajima, Daisuke; Kawauchi, Tetsuro; Yasuyama, Takuro; Ando, Shin; Ishizuka, Tadao

    2017-04-05

    The combination of a "rigid" chiral bicyclic cis-1,2-diamine skeleton with steric bulkiness and a "flexible" achiral linker was newly designed as a bifunctional organocatalyst framework and it showed excellent catalytic activity of up to 0.05 mol%, accompanied by the reversal of enantioselection depending on the position of the linker, in an amine-thiourea organocatalyzed asymmetric Michael reaction.

  2. Cure Chemistry of Phenylethynyl Terminated Oligomers

    NASA Technical Reports Server (NTRS)

    Wood, Karen H.; Orwoll, Robert A.; Young, Philip R.; Jensen, Brian J.; McNair, Harold M.

    1997-01-01

    The ability to process high performance polymers into quality, void-free composites has been significantly advanced using oligomers terminated with reactive groups which cure or crosslink at elevated temperature without the evolution of volatile byproducts. Several matrix resin systems of considerable interest to the aerospace community utilize phenylethynyl-terminated imide (PETI) technology to achieve this advantage. The present paper addresses the cure chemistry of PETI oligomers. The thermal cure of a low molecular weight model compound was studied using a variety of analytical techniques including differential scanning calorimetry, Fourier transform infrared spectroscopy, and liquid chromatography-mass spectroscopy. The studies indicate an extremely complex cure process. Many stable products were isolated and this paper reports current work on identification of those products. The intent of this research is to provide fundamental insight into the molecular structure of the cured PETI engineering materials so that performance and durability can be more fully assessed.

  3. 7 CFR 29.2519 - Fire-cured.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Fire-cured. 29.2519 Section 29.2519 Agriculture... INSPECTION Standards Official Standard Grades for Kentucky and Tennessee Fire-Cured and Foreign-Grown Fire-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2519 Fire-cured. Tobacco cured...

  4. 7 CFR 29.2519 - Fire-cured.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Fire-cured. 29.2519 Section 29.2519 Agriculture... INSPECTION Standards Official Standard Grades for Kentucky and Tennessee Fire-Cured and Foreign-Grown Fire-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2519 Fire-cured. Tobacco cured...

  5. 7 CFR 29.2519 - Fire-cured.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Fire-cured. 29.2519 Section 29.2519 Agriculture... INSPECTION Standards Official Standard Grades for Kentucky and Tennessee Fire-Cured and Foreign-Grown Fire-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2519 Fire-cured. Tobacco cured...

  6. 7 CFR 29.2519 - Fire-cured.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Fire-cured. 29.2519 Section 29.2519 Agriculture... INSPECTION Standards Official Standard Grades for Kentucky and Tennessee Fire-Cured and Foreign-Grown Fire-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2519 Fire-cured. Tobacco cured...

  7. 7 CFR 29.2519 - Fire-cured.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Fire-cured. 29.2519 Section 29.2519 Agriculture... INSPECTION Standards Official Standard Grades for Kentucky and Tennessee Fire-Cured and Foreign-Grown Fire-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2519 Fire-cured. Tobacco cured...

  8. 9 CFR 319.103 - Cured beef tongue.

    Code of Federal Regulations, 2010 CFR

    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...

  9. Dihydrogen phosphate-water tape and layers vs dihydrogen phosphate layers tuned by hydrophobic isomeric pyridine-diamine functionalized molecules

    NASA Astrophysics Data System (ADS)

    Huang, Jing; Liu, Tong-Peng; Huo, Li-Hua; Deng, Zhao-Peng; Gao, Shan

    2017-01-01

    Assembly of six isomeric pyridine-diamine-based molecules, N,N‧-bis(pyridin-4-ylmethyl)ethane-1,2-diamine (M1), N,N‧-bis(pyridin-3-ylmethyl)ethane-1,2-diamine (M2), N,N‧-bis(pyridin-2-ylmethyl)ethane-1,2-diamine (M3), N,N‧-bis(pyridin-4-ylmethyl)propane-1,3-diamine (M4), N,N‧-bis(pyridin-3-ylmethyl)propane-1,2-diamine (M5), and N,N‧-bis(pyridin-2-ylmethyl)propane-1,3-diamine (M6), with phosphoric acid (H3PO4) in different ratio (1:2 and 1:4), leads to the formation of nine salts, H2M12+·2H2PO4-·4H2O (1), H2M22+·2H2PO4-·2H2O (2), H2M32+·2H2PO4-·2H2O (3), H4M14+·4H2PO4- (4), H4M24+·4H2PO4- (5), H4M34+·4H2PO4- (6), H2M42+·2H2PO4-·3H2O (7), 2H2M52+·4H2PO4-·2H3PO4 (8), and H2M62+·2H2PO4- (9), which have been characterized by elemental analysis, IR, TG, PL, powder and single-crystal X-ray diffraction. Structural analyses indicate that hydrogen-bonding patterns of H2PO4- anions, conformation of protonated cations can effectively influence the supramolecular architectures through diverse non-covalent interactions. Hydrous salts 1-3 and 7 present 2D and 3D host-guest supramolecular networks, in which the connection of H2PO4- anions and water molecules generates diverse tape and layer motifs. H2PO4- anions in anhydrous salts 4-6 interconnect with each other through hydrogen bonds to form two types of layers, which are joined by discrete H4M4+ cations into 3D inorganic-organic hybrid supramolecular networks. Salts 8-9 also present 2D and 3D host-guest supramolecular networks where the interconnection of H2PO4- anions and its combination with H3PO4 molecules leads to diverse layers. Luminescent analyses indicate that salts 1-9 exhibit violet and blue emission maximum in the range of 390-467 nm at room temperature.

  10. Curing efficiency of modern LED units.

    PubMed

    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 < 0.05). The degree of cure at 6-mm depth was less but significantly influenced by the curing unit and curing time and was independent from the type of RBC. A 5-s irradiation time is not recommended for these units. Whereas a 5-s irradiation is acceptable at the sample's surface, a minimum of 20 s of irradiation is necessary for an adequate polymerisation 2 mm beyond the surface.

  11. Effectiveness of light emitting diode and halogen light curing units for curing microhybrid and nanocomposites

    PubMed Central

    Choudhary, Shwetha; Suprabha, BS

    2013-01-01

    Aim: To compare the polymerization efficacy of micro-hybrid and nanocomposites cured with Quartz-tungsten halogen (QTH) and light emitting diode (LED) light curing units (LCUs). The effectiveness of pulse cure mode in LED LCU was also investigated. Materials and Methods: Both micro-hybrid and nanocomposite specimens were cured using four different curing protocols giving a total of eight experimental groups. Ten cylindrical specimens were prepared for each group, and light cured for 40 s on the top surface, thus giving a total of eighty specimens. Vicker hardness measurements were carried out on the top and bottom surfaces after 24 h and hardness ratio was calculated. Results: For both micro-hybrid and nanocomposites, highest mean VHN was observed for the group cured with QTH LCU, and the lowest was observed for the group cured with second LED LCU in standard mode but the difference was significant only in case of nanocomposite. Conclusion: Curing nanocomposites with QTH LCU results in better micro hardness. Pulse cure mode does not effectively increase polymerization efficacy than the standard mode of curing. PMID:23833457

  12. Extension of a Cox proportional hazards cure model when cure information is partially known

    PubMed Central

    Wu, Yu; Lin, Yong; Lu, Shou-En; Li, Chin-Shang; Shih, Weichung Joe

    2014-01-01

    When there is evidence of long-term survivors, cure models are often used to model the survival curve. A cure model is a mixture model consisting of a cured fraction and an uncured fraction. Traditional cure models assume that the cured or uncured status in the censored set cannot be distinguished. But in many practices, some diagnostic procedures may provide partial information about the cured or uncured status relative to certain sensitivity and specificity. The traditional cure model does not take advantage of this additional information. Motivated by a clinical study on bone injury in pediatric patients, we propose a novel extension of a traditional Cox proportional hazards (PH) cure model that incorporates the additional information about the cured status. This extension can be applied when the latency part of the cure model is modeled by the Cox PH model. Extensive simulations demonstrated that the proposed extension provides more efficient and less biased estimations, and the higher efficiency and smaller bias is associated with higher sensitivity and specificity of diagnostic procedures. When the proposed extended Cox PH cure model was applied to the motivating example, there was a substantial improvement in the estimation. PMID:24511081

  13. Biodegradation of toluene diamine (TDA) in activated sludge acclimated with aniline and TDA.

    PubMed

    Asakura, S; Okazaki, S

    1995-06-01

    The biodegradability of toluene diamine (TDA) which has been regarded as a "recalcitrant compound" was examined in activated sludges. In this study, a microorganic-enzyme system which metabolized TDA was obtained by acclimating the activated sludge with aniline and TDA. In the sludge subject to be 200 days' acclimation, the considerable increase in respiration rate with the addition of TDA, accompanied the sharp decrease in its concentration. This indicated that TDA was metabolized fortuitously. The rate of biodegradation of TDA in the absence of aniline was first order with respect to its concentration when the initial TDA concentration was less than about 5 mg/l. The rate constant in this relation was proportional to mixed liquor suspended solid (MLSS). However, when the initial TDA concentration exceeded 5 mg/l, the plots were deviated from a first order rate equation.

  14. Electron-microscopic cytochemical localization of diamine and polyamine oxidases in pea and maize tissues

    NASA Technical Reports Server (NTRS)

    Slocum, R. D.; Furey MJ, 3. d.

    1991-01-01

    An electron-microscopic cytochemical method was used to localize diamine oxidase (DAO) in pea and polyamine oxidase (PAO) in maize (Zea mays L.). The method, based on the precipitation of amine-oxidase-generated H2O2 by CeCl3, was shown to be specific for DAO and PAO and permitted their localization in plant tissues with a high degree of resolution. Both enzymes are localized exclusively in the cell wall. Both DAO- and PAO-activity staining is most intense in the middle lamellar region of the wall and in cells exhibiting highly lignified walls. The oxidases could provide H2O2 for peroxidase-mediated cross-linking reactions in the cell wall and may, in this capacity, play a role in the regulation of plant growth.

  15. Labeling of human hepatocellular carcinoma cells by hexamethylene diamine modified fluorescent carbon dots

    NASA Astrophysics Data System (ADS)

    Dong, Wei; Dong, Yan; Wang, Ying; Zhou, Shiqi; Ge, Xin; Sui, Lili; Wang, Jingwen

    2013-12-01

    Fluorescent carbon dots (CDs) were synthesized by a solvothermal method with glucose as carbon source and surface-modified with 1,6-hexamethylene diamine. In this hybrid CDs, the modification played important role for improving the fluorescent performance by introducing nitrogenous compound to passivate CD's surface, making the CDs emit strong fluorescence. The as-prepared CDs were linked with mouse anti-human Alpha fetoprotein (AFP) antibody and goat anti-mouse immunoglobulin (IgG) to directly and indirectly label fixed human hepatocellular carcinoma cells, respectively. The cytotoxicity of these CDs were also tested using the human hepatocellular carcinoma cells. No apparent cytotoxicity was observed, which suggested the potential application of the as-prepared CDs in bioimaging.

  16. Application of ethylene diamine tetra acetic acid degrading bacterium Burkholderia cepacia on biotreatment process.

    PubMed

    Chen, Wei-Ting; Shen, Shu-Min; Shu, Chi-Min

    2015-10-01

    Ethylene diamine tetra acetic acid (EDTA), the effluent of secondary biotreatment units, can be properly biodegraded by Burkholderia cepacia. Through batch degradation of EDTA, the raw wastewater of EDTA was controlled at 50 mg/L, and then nutrients was added in diluted wastewater to cultivate activated sludge, which the ratio of composition is depicted as "COD:N:P:Fe = 100:5:1:0.5". After 27 days, the removal efficiency of Fe-EDTA and COD was 100% and 92.0%, correspondingly. At the continuous process, the raw wastewater of EDTA was dictated at 166 mg/L before adding nutrients to cultivate activated sludge, in which the ratio of composition did also follow with batch process. After 22 days, the removal efficiency of Fe-EDTA and COD for experimental group was 71.46% and 62.58%, correspondingly. The results showed that the batch process was more suited for EDTA biodegradation.

  17. Synthesis of planar chiral ferrocenyl 1,3-diamines and 1,3-amino ethers.

    PubMed

    Anderson, James C; Blake, Alexander J; Arnall-Culliford, Jennifer C

    2003-10-21

    The efficient syntheses of novel planar chiral 1,3-diamines and 1,3-amino ethers with an oxy or amino function directly bound to the cyclopentadienyl ring of ferrocene has been developed. The key reaction is the Cu2O promoted substitution of (pR)-N,N-diisopropyl-2-iodoferrocenecarboxamide with either phthalimide or AcOH to introduce nitrogen or oxygen functionality onto the cyclopentadienyl ring. The enantiomerically pure iodoferrocene derivative is available from the known enantioselective ortho-lithiation of N,N-diisopropylferrocenecarboxamide with n-BuLi-sparteine. In the course of these studies the synthesis of a novel C2 symmetric C-2 dimer of N,N-dimethyl-1-ferrocenylethylamine was characterised by single crystal X-ray diffraction.

  18. Help us find the cures.

    PubMed

    Morgan, Delyth

    2013-01-01

    Despite significant advances in research, breast cancer is still the most common form of cancer, with 50,000 cases diagnosed and 12,000 dying of the disease each year in the UK. In October 2013, Breast Cancer Campaign published a Gap Analysis of breast cancer research that provides us with what we need to know about and what we now need to do to overcome - prevent, cure and outlive - breast cancer. In addition to highlighting the gaps in our understanding of breast cancer, the paper identifies five strategic solutions, which require a collaborative approach amongst researchers in academia and industry, funders, donors, policy-makers and parliamentarians, healthcare professionals and patients to achieve significant progress. Breast Cancer Campaign is calling for funding organizations to reverse the decline in resources targeted towards breast cancer research, an improved and collaborative infrastructure to support breast cancer research, multidisciplinary collaboration and improved clinical trial design. We hope that breast cancer can be overcome by 2050, but this can only be achieved through collaboration with others. The actions that will make a difference have been identified and we must act now.

  19. Metabolic engineering of Escherichia coli for the production of putrescine: a four carbon diamine.

    PubMed

    Qian, Zhi-Gang; Xia, Xiao-Xia; Lee, Sang Yup

    2009-11-01

    A four carbon linear chain diamine, putrescine (1,4-diaminobutane), is an important platform chemical having a wide range of applications in chemical industry. Biotechnological production of putrescine from renewable feedstock is a promising alternative to the chemical synthesis that originates from non-renewable petroleum. Here we report development of a metabolically engineered strain of Escherichia coli that produces putrescine at high titer in glucose mineral salts medium. First, a base strain was constructed by inactivating the putrescine degradation and utilization pathways, and deleting the ornithine carbamoyltransferase chain I gene argI to make more precursors available for putrescine synthesis. Next, ornithine decarboxylase, which converts ornithine to putrescine, was amplified by a combination of plasmid-based and chromosome-based overexpression of the coding genes under the strong tac or trc promoter. Furthermore, the ornithine biosynthetic genes (argC-E) were overexpressed from the trc promoter, which replaced the native promoter in the genome, to increase the ornithine pool. Finally, strain performance was further improved by the deletion of the stress responsive RNA polymerase sigma factor RpoS, a well-known global transcription regulator that controls the expression of ca. 10% of the E. coli genes. The final engineered E. coli strain was able to produce 1.68 g L(-1) of putrescine with a yield of 0.168 g g(-1) glucose. Furthermore, high cell density cultivation allowed production of 24.2 g L(-1) of putrescine with a productivity of 0.75 g L(-1) h(-1). The strategy reported here should be useful for the bio-based production of putrescine from renewable resources, and also for the development of strains capable of producing other diamines, which are important as nitrogen-containing platform chemicals.

  20. Covalent IR820-PEG diamine conjugates: characterization and in vivo biodistribution

    NASA Astrophysics Data System (ADS)

    Fernandez-Fernandez, Alicia; Manchanda, Romila; Carvajal, Denny A.; Lei, Tingjun; McGoron, Anthony J.

    2013-02-01

    Introduction: IR820 is a near-infrared probe with potential applications in optical imaging and hyperthermia. Its chlorosubstituted cyclohexene makes it amenable to forming conjugates as multifunctional probes. We prepared a novel covalent IR820/PEG-diamine (IRPDcov) nanoconjugate. Methods: IRPDcov was prepared using IR820 and 6kDa PEG-diamine, characterized by SEM, H-NMR, spectrophotometry, and spectrofluorometry; and studied in vitro and in vivo. Mice (n=36) were used to explore the biodistribution of IRPDcov compared to IR820 and indocyanine green (ICG) after i.v. injection of a 0.24 mg/kg dose of dye, with plasma samples collected at 15-30-60 minutes and 24 hours. The plasma concentrations were fit to a biexponential curve following a two compartment model. Organ samples were collected after 24 hours. Results and Discussion: IRPDcov retained the ability to fluoresce for in vivo optical imaging and also to generate heat, and was significantly more stable than IR820 in aqueous solution over a period of 72 hours. IRPDcov and IR820 demonstrated significantly longer (p<0.05) plasma half-lives, elimination half-lives, and area-under-the-curve values compared to ICG. This could pose an advantage in therapeutic probe applications such as hyperthermia or drug delivery. Both IR820 and IRPDcov showed a very strong signal in the liver and lower-intensity signal in the kidneys 24 hours after injection, whereas the predominant signal for ICG was weak and located in the intestines, demonstrating a much more rapid GI elimination. IR820 showed signal in the lungs, which was not present in IRPDcov subjects indicating that IRPDcov may have been able to escape detection by alveolar macrophages.

  1. Hypoxanthine enhances the cured meat taste.

    PubMed

    Ichimura, Sayaka; Nakamura, Yukinobu; Yoshida, Yuka; Hattori, Akihito

    2017-02-01

    We evaluated the enhancement of cured meat taste during maturation by sensory analysis. We focused on the heat-stable sarcoplasmic fraction (HSSF) to identify the factors related to cured meat taste. Because the dry matter of HSSF contained more than 30% nitrogen, nitrogen compounds such as free amino acids, small peptides and adenosine triphosphate-related compounds seemed to be the important components of HSSF. The samples cured with HSSF for 2 h exhibited the same taste profile as ones cured without HSSF for 168 h. Therefore, the changes in the amount and fractions of nitrogen compounds were examined in HSSF during incubation from 0 to 168 h. The concentration of hypoxanthine (Hx) gradually increased, while inosine-5'-monophosphate decreased during the incubation. The samples cured with pickles containing various concentrations of Hx were subjected to sensory analysis. The addition of Hx, in a dose-dependent fashion, enhanced cured meat taste by maturation for 2 h. It was concluded that Hx is essential for the enhancement of cured meat taste.

  2. Hypoxanthine enhances the cured meat taste

    PubMed Central

    Nakamura, Yukinobu; Yoshida, Yuka; Hattori, Akihito

    2016-01-01

    Abstract We evaluated the enhancement of cured meat taste during maturation by sensory analysis. We focused on the heat‐stable sarcoplasmic fraction (HSSF) to identify the factors related to cured meat taste. Because the dry matter of HSSF contained more than 30% nitrogen, nitrogen compounds such as free amino acids, small peptides and adenosine triphosphate‐related compounds seemed to be the important components of HSSF. The samples cured with HSSF for 2 h exhibited the same taste profile as ones cured without HSSF for 168 h. Therefore, the changes in the amount and fractions of nitrogen compounds were examined in HSSF during incubation from 0 to 168 h. The concentration of hypoxanthine (Hx) gradually increased, while inosine‐5′‐monophosphate decreased during the incubation. The samples cured with pickles containing various concentrations of Hx were subjected to sensory analysis. The addition of Hx, in a dose‐dependent fashion, enhanced cured meat taste by maturation for 2 h. It was concluded that Hx is essential for the enhancement of cured meat taste. PMID:27169902

  3. 7 CFR 29.3002 - Air-cured.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Air-cured. Tobacco cured under natural atmospheric conditions. Artificial heat is sometimes used to...-cured tobacco should not carry the odor of smoke or fumes resulting from the application of...

  4. 7 CFR 29.3002 - Air-cured.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Air-cured. Tobacco cured under natural atmospheric conditions. Artificial heat is sometimes used to...-cured tobacco should not carry the odor of smoke or fumes resulting from the application of...

  5. 7 CFR 29.3002 - Air-cured.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Air-cured. Tobacco cured under natural atmospheric conditions. Artificial heat is sometimes used to...-cured tobacco should not carry the odor of smoke or fumes resulting from the application of...

  6. 7 CFR 29.3002 - Air-cured.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Air-cured. Tobacco cured under natural atmospheric conditions. Artificial heat is sometimes used to...-cured tobacco should not carry the odor of smoke or fumes resulting from the application of...

  7. Chemoenzymatic preparation of optically active trans-cyclohexane-1,2-diamine derivatives: an efficient synthesis of the analgesic U-(-)-50,488.

    PubMed

    González-Sabín, Javier; Gotor, Vicente; Rebolledo, Francisca

    2004-11-05

    Stereoespecific syntheses of (+/-)-trans-N,N-cyclohexane-1,2-diamines ((+/-)-4 a-g) were carried out from the corresponding (+/-)-trans-N,N-dialkylaminocyclohexanols by successive treatment with mesyl chloride and aqueous ammonia. The stereochemical outcome indicates the formation of a meso-aziridinium ion intermediate. Kinetic resolutions of diamines (+/-)-4 were efficiently accomplished in aminolysis reactions catalyzed by lipase B from Candida antarctica with ethyl acetate as the solvent and acyl donor. Acetamides and the remaining diamines, isolated as the benzyloxycarbonyl derivatives, were obtained with very high ee values (92-99%). One of the carbamates was used as a precursor of the analgesic U-(-)-50,488.

  8. The curing of high-performance concrete

    NASA Astrophysics Data System (ADS)

    Meeks, Kenneth Wayne

    This dissertation describes the latest information, technology, and research on the curing of high performance concrete (HPC). Expanded somewhat beyond the scope of HPC, it examines the current body of knowledge on the effects of various curing regimes on concrete. The significance and importance of curing are discussed as well as the various definitions of HPC. The current curing requirements, standards, and criteria as proposed by ACI, as well as those of other countries, are reviewed and discussed. The current prescriptive curing requirements may not be applicable to high performance concrete. The research program reported in this dissertation looked at one approach to development of curing criteria for this relatively new class of concrete. The program applies some of the basic concepts of the methodology developed by the German researcher, H. K. Hilsdorf, to the curing of HPC with the objective to determine minimum curing durations for adequate strength development. The approach is to determine what fraction of the standard-cured 28-day strength has to be attained at the end of the curing period to assure that the design strength is attained in the interior of the member. An innovative direct tension test was developed to measure the strength at specific depths from the drying surface of small mortar cylinders (50 x 127 mm (2 x 5 in.)). Two mortar mixtures were investigated, w/c = 0.30 and w/c = 0.45, and three different moist curing regimes, 1-day, 3-day, and 7-day. Specimens were stored in two environmental chambers at 25sp°C, 50% RH; and 25sp°C, 70% RH, until testing at the age of 28 days. Direct tensile tests were conducted using steel disks epoxied to the ends of the specimens. Also, the penetration of the drying front was calculated from the drying data using porosity and degree of hydration relationships. The major observation from these tests was that adequate strength is attained in both mortar mixtures with only one day of moist curing. The drying

  9. One-step microwave foaming and curing

    NASA Technical Reports Server (NTRS)

    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.

  10. Surface and pulpal temperature comparison of tooth whitening using lasers and curing lights

    NASA Astrophysics Data System (ADS)

    White, Joel M.; Pelino, Jose; Rodrigues, Rively; Zwhalen, Brian J.; Nguyen, Max H.; Wu, Emily

    2000-03-01

    Chemical action of bleaching agents applied to tooth surface is accelerated by increase in temperature. This in vitro study measured the temperature rises on the surface and in the pulp of teeth during whitening using a diode laser, a plasma arc curing (PAC) light and conventional curing lights. Extracted, non-carious single-rooted teeth were exposed to PAC light and laser at times ranging from 10 to 60 seconds and energy ranges of 2 W, 4 W, and 6 W, and to low-intensity curing lights from 1 to 4 minutes. Maximum temperature rises were analyzed for both pulpal and surface temperature. Diode laser exposures at 2 W for all times and at 4 watts for 10 seconds and PAC light exposures at 10 seconds all produced acceptably safe pulpal rises equivalent to conventional light-curing exposures. Exposures at these settings also attained surface temperature rises that were significantly higher than those using conventional light-curing. The diode laser demonstrated bleaching results equivalent to the PAC light, and both were achieved in significantly less times than conventional light- curing.

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

    PubMed

    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.

  12. Visible light-curing unit.

    PubMed

    2002-10-01

    Ortholux XT is a high-intensity light source emitting filtered visible blue light in the 400- to 500-nanometer range for polymerization of visible-light-cured resins. The Ortholux handpiece comes with a portable power supply, a light-intensity check in the power supply, a spare lamp, an eyeshield and a mounting kit. The handpiece consists of a pistol grip with a thermoplastic housing that contains the light source, cooling fan, light guide receptacle (8- or 13-millimeter-diameter fused quartz lightguide), optical filter, light switch and timer switch. The timer is operator-selectable with options of five, 10, 15 and 20 seconds and an XT option of up to 600 seconds. The push-button switch allows for timer disruption and reactivation. 3M Unitek reported (3M Unitek, unpublished data submitted to the ADA, date not known) that the cooling fan generates noise below 43 decibels when the internal handpiece temperature is below 100 C. At 120 C, the fan speed increases, generating 52 dBA. The U.S. Air Force Dental Investigative Service reported that the cooling fan is extremely quiet. The light shuts off when it reaches 140 C. The light source is a 75-watt tungsten/halogen lamp. The handpiece weighs less than one pound. The power supply contains the built-in intensity meter that illuminates a green light-emitting diode when the tested light exceeds 400 milliwatts per square centimeter. The power cord is six feet in length. A built-in voltage regulator ensures a steady voltage supply to the unit.

  13. The stability of new transparent polymeric materials: The epoxy trimethoxyboroxine system. Part 1: The preparation, characterization and curing of epoxy resins and their copolymers

    NASA Technical Reports Server (NTRS)

    Pearce, E.; Lin, S. C.

    1981-01-01

    The effects of resin composition, curing conditions fillers, and flame retardant additives on the flammability of diglycidyl ether of bisphenol-A (DGEBA) as measured by the oxygen index is examined. The oxygen index of DGEBA cured with various curing agents was between 0.198 to 0.238. Fillers and flame retardant additives can increase the oxygen index dependent on the material and the amount used. Changes in the basic cured resin properties can be anticipated with the addition of noncompatible additives. High flame resistant epoxy resins with good stability and mechanical properties are investigated.

  14. Effects of light curing modes and resin composites on temperature rise under human dentin: an in vitro study.

    PubMed

    Hubbezoglu, Ihsan; Dogan, Arife; Dogan, Orhan Murat; Bolayir, Giray; Bek, Bulent

    2008-07-01

    The influence of three curing modes of a high-powered LED curing unit on temperature rise under 2-mm-thick dentin was investigated during the polymerization of resin composite samples of Admira, Filtek P60, Premise, Tetric Flow, Tetric Ceram, and Filtek Z250. Ninety standard specimens were prepared. The bonding agents and resin composites were cured with standard, pulse, or soft-start mode (n=5 for each curing mode). Temperature rise was measured using a type L thermocouple. Data were analyzed by two-way ANOVA and Tukey's test. Soft-start curing led to statistically higher temperature rises compared than the other two modes. The highest temperature rise was observed for Admira and Tetric Flow cured with soft-start mode. The lowest temperature rise was observed for Premise cured with pulse mode. However, temperature rise did not reach the critical value that can cause pulpal damage by virtue of a prominent safety feature of the high-powered LED LCU, which ensures that no excessive heat is produced by all the three curing modes.

  15. Inelastic micromechanics of curing stresses in composites

    NASA Technical Reports Server (NTRS)

    Foye, R. L.

    1975-01-01

    The combined finite element/laminate analysis method is used to study the thermal curing stresses in composite materials with a nonlinearly elastic matrix subject to creep. The application of this analysis to boron/epoxy composites shows that curing stress levels in the laminate are of sufficient magnitude to cause widespread yielding in the matrix. The stress levels, based on the creep analysis of a typical laminate cure cycle, indicate that the residual stresses can vary from 80 to 100% of the residual stress estimates based on linear thermoelastic analysis. It is shown that there is virtually no change in the static longitudinal or shear response of unidirectional and cross-ply boron/epoxy laminates as a result of curing stresses. Results of a series of constant-stress, high temperature creep tests are presented.

  16. Curing of Furfuryl Alcohol-Impregnated Parts

    NASA Technical Reports Server (NTRS)

    Lawton, J. W.; Brayden, T. H.

    1983-01-01

    Delamination problem in reinforced carbon/carbon parts impregnated with oxalic acid-catalyzed furfuryl alcohol overcome by instituting two additional quality-control tests on alcohol and by changing curing conditions.

  17. Fast Curing of Composite Wood Products

    SciTech Connect

    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

  18. Tracking Polymer Cure Via Embedded Optical Fibers

    NASA Technical Reports Server (NTRS)

    Dean, David L.; Davidson, T. Fred

    1993-01-01

    Fourier-transform infrared spectroscopy applied in interior of specimen of material by bringing infrared light through specimen in optical fiber. Light interacts with material via evanescent-wave effect. Spectra obtained in this way at various times during curing process also combined with data from ultrasonic, thermographic, and dielectric-impedance monitoring, and other measurement techniques to obtain more complete characterization of progress of curing process.

  19. The cure of cancer: a European perspective.

    PubMed

    Francisci, Silvia; Capocaccia, Riccardo; Grande, Enrico; Santaquilani, Mariano; Simonetti, Arianna; Allemani, Claudia; Gatta, Gemma; Sant, Milena; Zigon, Giulia; Bray, Freddie; Janssen-Heijnen, Maryska

    2009-04-01

    Cancer survival analyses based on cancer registry data do not provide direct information on the main aim of cancer treatment, the cure of the patient. In fact, classic survival indicators do not distinguish between patients who are cured, and patients who will die of their disease and in whom prolongation of survival is the main objective of treatment. In this study, we applied parametric cure models to the cancer incidence and follow-up data provided by 49 EUROCARE-4 (European Cancer Registry-based study, fourth edition) cancer registries, with the aims of providing additional insights into the survival of European cancer patients diagnosed from 1988 to 1999, and of investigating between-population differences. Between-country estimates the proportion of cured patients varied from about 4-13% for lung cancer, from 9% to 30% for stomach cancer, from 25% to 49% for colon and rectum cancer, and from 55% to 73% for breast cancer. For all cancers combined, estimates varied between 21% and 47% in men, and 38% and 59% in women and were influenced by the distribution of cases by cancer site. Countries with high proportions of cured and long fatal case survival times for all cancers combined were characterised by generally favourable case mix. For the European pool of cases both the proportion of cured and the survival time of fatal cases were associated with age, and increased from the early to the latest diagnosis period. The increases over time in the proportions of Europeans estimated cured of lung, stomach and colon and rectum cancers are noteworthy and suggest genuine progress in cancer control. The proportion of cured of all cancers combined is a useful general indicator of cancer control as it reflects progress in diagnosis and treatment, as well as success in the prevention of rapidly fatal cancers.

  20. Energy curable compositions having improved cure speeds

    DOEpatents

    Halm, Leo W.

    1993-01-01

    A composition and method provide improved physical properties and cure speed of polyurethane precursors, with or without free radical polymerizable monomers or oligomers present, by use of a two component catalyst system. The resin blend can be activated with a latent organometallic catalyst combined with an organic peroxide which can be a hydroperoxide or an acyl peroxide to decrease the cure time while increasing the break energy and tangent modulus of the system.

  1. Energy curable compositions having improved cure speeds

    DOEpatents

    Halm, L.W.

    1993-05-18

    The composition and method provide improved physical properties and cure speed of polyurethane precursors, with or without free radical polymerizable monomers or oligomers present, by use of a two component catalyst system. The resin blend can be activated with a latent organometallic catalyst combined with an organic peroxide which can be a hydroperoxide or an acyl peroxide to decrease the cure time while increasing the break energy and tangent modulus of the system.

  2. Radiation Curing of Natural Fiber Composite

    NASA Astrophysics Data System (ADS)

    Liu, Xueyuan

    This research is a study of the process and feasibility of applying UV to cure natural and recycled fiber composites. The influence of HEMA on the water absorption and mechanical properties of the composites also investigated. Results show that UV curing is feasible in the manufacture of natural and recycle fiber composites. HEMA significantly improved the water resistance of the composite. HEMA-treated natural and recycled fiber composites have better bending strength after water impregnation, than non-treated composites.

  3. Can liver transplantation provide the statistical cure?

    PubMed

    Cucchetti, Alessandro; Vitale, Alessandro; Cescon, Matteo; Gambato, Martina; Maroni, Lorenzo; Ravaioli, Matteo; Ercolani, Giorgio; Burra, Patrizia; Cillo, Umberto; Pinna, Antonio D

    2014-02-01

    Liver transplantation (LT) represents the only chance of long-term survival for patients with end-stage liver disease. When the mortality rate for transplant patients returns to the same level as that for the general population, they can be considered statistically cured. However, cure models in the setting of LT have never been applied. Data from 1371 adult patients undergoing LT for the first time between January 1999 and December 2012 at 2 Italian centers were reviewed in order to establish probabilities of being cured by LT. A parametric Weibull model was applied to compare the mortality rate after LT to the rate expected for the general population (matched by sex and age). The observed 3-, 5-, and 10-year overall survival rates after LT were 77.8%, 73.3%, and 65.6%, respectively, and they did not differ between the 2 centers (P = 0.37). The cure fraction for the entire study population was 63.4% (95% confidence interval = 52.6%-72.0%), and the time to cure was 10 years with a 90% confidence level. The best cure fraction was observed for younger recipients without hepatitis C virus (HCV) who had favorable donor-recipient matches, that is, low Donor Model for End-Stage Liver Disease (D-MELD) scores (90.1%); conversely, the lowest probability was observed for elderly HCV recipients with high D-MELD scores (34.6%). The time to cure was 6.22 years for non-HCV patients and 14.78 years for HCV patients. The median survival time for uncured patients was 2.29 years. Among uncured recipients, the longest survival time was observed for younger patients (7.31 years). In conclusion, we provide here a new clinical measure for LT suggesting that survival after transplantation can approximate that of the general population and provide a statistical cure.

  4. Anomalous Behavior of Cured Epoxy Resins: Density at Room Temperature versus Time and Temperature of Cure

    DTIC Science & Technology

    1988-07-01

    density (at 250 C) of a OGEBA epoxy resin cured with phthalic acid anhydride increased with time of cure at a single cure temperature, reached a maximum...time to vitrification to eventually form a glass. A more appropriate time indicator for the formation of glassy-state material in principle is that... enthalpy relaxation immediately above the assigned Tg, is typical of all slow-cooled, and also of fast-cooled specimens which had vitrified during

  5. High Power UV LED Industrial Curing Systems

    SciTech Connect

    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.

  6. Assessing the fit of parametric cure models.

    PubMed

    Wileyto, E Paul; Li, Yimei; Chen, Jinbo; Heitjan, Daniel F

    2013-04-01

    Survival data can contain an unknown fraction of subjects who are "cured" in the sense of not being at risk of failure. We describe such data with cure-mixture models, which separately model cure status and the hazard of failure among non-cured subjects. No diagnostic currently exists for evaluating the fit of such models; the popular Schoenfeld residual (Schoenfeld, 1982. Partial residuals for the proportional hazards regression-model. Biometrika 69, 239-241) is not applicable to data with cures. In this article, we propose a pseudo-residual, modeled on Schoenfeld's, to assess the fit of the survival regression in the non-cured fraction. Unlike Schoenfeld's approach, which tests the validity of the proportional hazards (PH) assumption, our method uses the full hazard and is thus also applicable to non-PH models. We derive the asymptotic distribution of the residuals and evaluate their performance by simulation in a range of parametric models. We apply our approach to data from a smoking cessation drug trial.

  7. Iodine catalyzed one-pot diamination of glycals with chloramine-T: a new approach to 2-amino-beta-glycosylamines for applications in N-glycopeptide synthesis.

    PubMed

    Kumar, Vipin; Ramesh, Namakkal G

    2006-12-21

    Iodine catalyzes a facile one-pot direct diamination of glycals with chloramine-T to afford stereoselectively 2-amino-beta-glycosylamine derivatives that serve as convenient precursors for the synthesis of N-linked glycopeptides.

  8. Curing of epoxy resins with 1-DI(2-chloroethoxyphosphinyl) methyl-2,4 and -2,6-diaminobenzene

    NASA Technical Reports Server (NTRS)

    Mikroyannidis, J. A.; Kourtides, D. A.

    1983-01-01

    Fire resistant compositions were prepared using 1-di(2-chloroethoxy-phosphinyl)methyl-2,4- and -2,6-diaminobenzene (DCEPD) as a curing agent for typical epoxy resins such as EPON 828 (Shell), XD 7342 (Dow), and My 720 (Ciba Geigy). In addition, compositions of these three epoxy resins with common curing agents such as m-phenylenediamine (MPD) or 4,4'-diaminodiphenylsulphone (DDS) were studied to compare their reactions with those of DCEPD. The reactivity of the three curing agents toward the epoxy resins, measured by differential calorimetry (DSC), was of the order MPD DCEPD DDS. The relatively lower reactivity of DCEPD toward epoxy resins was attributed to electronic effects.

  9. Mg(II) -Catalyzed Desymmetrization Reaction of meso-Aziridines with Hydroxylamines: Synthesis of Novel Chiral 1,2-Diamine Skeletons.

    PubMed

    Li, Dan; Yang, Dongxu; Wang, Linqing; Liu, Xihong; Jiang, Xianxing; Wang, Rui

    2016-11-21

    A Mg(II) -catalyzed desymmetrization reaction of meso-aziridines with hydroxylamines has been disclosed for the first time. A series of novel chiral 1,2-diamine skeletons were obtained in good yields and enantioselectivities. The reaction employed magnesium catalysis generated in situ from a simple oxazoline-OH chiral ligand. Obviously, the diverse structures of the obtained chiral 1,2-diamine compounds could allow them to be potential chiral ligands in future catalytic asymmetric synthesis studies.

  10. Poly-phenylated diamines and their use as polycondensation monomers in the synthesis of polyamide, poly(amide-imide), and polyimide polymers

    NASA Technical Reports Server (NTRS)

    Harris, Frank W. (Inventor)

    1992-01-01

    New polyphenylated polynuclear aromatic diamines, such as 1,3-bis[4-aminophenyl]-2,3,5-triphenylbenzene, a process for their manufacture and their use as polycondensation components for the manufacture of polyamide, polyamide-imide and polyimide polymers are described. The polymers obtained with the aromatic diamines according to the invention are readily soluble, rigid-rod polymers and are distinguished by outstanding modulus, tensile compression strength, energy absorption, coefficient of expansion and electrical properties.

  11. Selective iridium-catalyzed alkylation of (hetero)aromatic amines and diamines with alcohols under mild reaction conditions.

    PubMed

    Blank, Benoît; Michlik, Stefan; Kempe, Rhett

    2009-01-01

    A P,N-ligand-coordinated iridium complex has been employed as an efficient catalyst for the selective monoalkylation of (hetero)aromatic amines with alcohols. A significant improvement of this alkylation method has been achieved, such that it can be performed at a temperature of 70 degrees C and with catalyst loadings as low as 0.1 mol % Ir, while still affording excellent yields of secondary amines. Furthermore, the high selectivity of this catalyst for the monoalkylation of aromatic amino functions has been successfully exploited for the alkylation of diamines in both symmetric and nonsymmetric fashions, providing a novel and very efficient synthetic tool for the preparation of N,N'-dialkylated aromatic diamines.

  12. Peptides containing acylated C-terminal gem diamines: novel irreversible inactivators of the cysteine and serine proteinases.

    PubMed

    Gilmore, B F; Lynas, J F; Harriott, P; Healy, A; Walker, B

    2006-05-01

    This study reports on the synthesis of peptides containing C-terminal acylated gem-diamines and their utilization for the preparation of irreversible inactivators of the serine and cysteine proteinases. We have succeeded in obtaining an inhibitor Acetyl-Val-Pro-g-Val-CO-O-C(6)H(4)-NO(2) of neutrophil and pancreatic elastases that functions in a time-dependent manner, indicative of the action of an irreversible inactivator, functioning, most probably, through the formation of a long-lived acyl enzyme intermediate. In addition, we have demonstrated the irreversible inhibition of the cysteine proteinase bovine cathepsin B, by chloroacetyl and bromoacetyl derivatives of a dipeptide gem-diamine, Cbz-Phe-g-Ala-CO-CH(2)Hal (Hal = Br, Cl).

  13. Monomers for thermosetting and toughening epoxy resins. [glycidyl amine derivatives, propargyl-containing amines, and mutagenic testing of aromatic diamines

    NASA Technical Reports Server (NTRS)

    Pratt, J. R.

    1981-01-01

    Eight glycidyl amines were prepared by alkylating the parent amine with epichlorohydrin to form chlorohydrin, followed by cyclization with aqueous NaOH. Three of these compounds contained propargyl groups with postcuring studies. A procedure for quantitatively estimating the epoxy content of these glycidyl amines was employed for purity determination. Two diamond carbonates and several model propargly compounds were prepared. The synthesis of three new diamines, two which contain propargyloxy groups, and another with a sec-butyl group is in progress. These materials are at the dinitro stage ready for the final hydrogenation step. Four aromatic diamines were synthesized for mutagenic testing purposes. One of these compounds rapidly decomposes on exposure to air.

  14. Organocatalysed asymmetric beta-amination and multicomponent syn-selective diamination of alpha,beta-unsaturated aldehydes.

    PubMed

    Jiang, Hao; Nielsen, Johanne B; Nielsen, Martin; Jørgensen, Karl Anker

    2007-01-01

    An easy and affordable route for obtaining chiral beta-aminated- and alpha,beta-diaminated aldehydes, 1,3-aminoalcohols, and related compounds by using organocatalysis is presented. The chiral secondary amine (S)-2-[bis(3,5-bistrifluoromethylphenyl)trimethylsilanyloxymethyl]pyrrolidine is used as the catalyst to activate alpha,beta-unsaturated aldehydes, which allows succinimide to add in a 1,4-regio- and stereoselective fashion thereby forming N-protected 1,3-aminoaldehydes in good yields and enantioselectivities. This is followed by two easy transformations giving rise to optically active 1,3-aminoalcohols, a common motif in many biologically active compounds, for example, fibrinogen receptor antagonists. Furthermore, optically active alpha,beta-syn-diaminated aldehydes were obtained by the addition of diethyl azodicarboxylate in a one-pot reaction.

  15. Angiogenesis: a curse or cure?

    PubMed

    Gupta, K; Zhang, J

    2005-04-01

    Angiogenesis, the growth of new blood vessels is essential during fetal development, female reproductive cycle, and tissue repair. In contrast, uncontrolled angiogenesis promotes the neoplastic disease and retinopathies, while inadequate angiogenesis can lead to coronary artery disease. A balance between pro-angiogenic and antiangiogenic growth factors and cytokines tightly controls angiogenesis. Considerable progress has been made in identifying these molecular components to develop angiogenesis based treatments. One of the most specific and critical regulators of angiogenesis is vascular endothelial growth factor (VEGF), which regulates endothelial proliferation, permeability, and survival. Several VEGF based treatments including anti-VEGF and anti-VEGF receptor antibodies/agents are in clinical trials along with several other antiangiogenic treatments. While bevacizumab (anti-VEGF antibody) has been approved for clinical use in colorectal cancer, the side effects of antiangiogenic treatment still remain a challenge. The pros and cons of angiogenesis based treatment are discussed.

  16. Camphor-derived C1-symmetric chiral diamine organocatalysts for asymmetric Michael addition of nitroalkanes to enones.

    PubMed

    Zhou, Yirong; Liu, Qiang; Gong, Yuefa

    2012-10-07

    A series of stable C(1)-symmetric chiral diamines (2a–2l) were conveniently synthesized by condensing exo-(-)-bornylamine or (+)-(1S,2S,5R)-menthylamine with various commercially available Cbz-protected amino acids. Among them, 2a can efficiently promote the Michael addition of nitroalkanes to a broad scope of enones with high yields (up to 96%) and excellent enantioselectivities (up to 98%) under mild conditions.

  17. Synthesis and characterization of CdSe/ZnS quantum dots conjugated with poly (ethylene glycol) diamine

    NASA Astrophysics Data System (ADS)

    Bharti, Shivani; Kaur, Gurvir; Gupta, Shikha; Tripathi, S. K.

    2015-08-01

    Bio-functionalization or surface modification is an important technique to obtain biocompatibility in semiconductor nanoparticles for biomedical applications. In this study semiconductor core/shell quantum dots of CdSe/ZnS have been prepared by chemical reduction method and then further PEGylated using Poly(ethylene glycol) diamine of Mw 2000. They were characterized by UV-vis spectroscopy & Fourier transform infrared spectroscopy. The results reveals the successful PEGylation of CdSe/ZnS quantum dots.

  18. Synthesis and characterization of CdSe/ZnS quantum dots conjugated with poly (ethylene glycol) diamine

    SciTech Connect

    Bharti, Shivani; Tripathi, S. K.; Kaur, Gurvir; Gupta, Shikha

    2015-08-28

    Bio-functionalization or surface modification is an important technique to obtain biocompatibility in semiconductor nanoparticles for biomedical applications. In this study semiconductor core/shell quantum dots of CdSe/ZnS have been prepared by chemical reduction method and then further PEGylated using Poly(ethylene glycol) diamine of M{sub w} 2000. They were characterized by UV-vis spectroscopy & Fourier transform infrared spectroscopy. The results reveals the successful PEGylation of CdSe/ZnS quantum dots.

  19. 7 CFR 29.2269 - Fire-cured.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Fire-cured. 29.2269 Section 29.2269 Agriculture... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) § 29.2269 Fire-cured. Tobacco cured under artificial atmospheric conditions by the use of open fires from which...

  20. 7 CFR 29.2269 - Fire-cured.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Fire-cured. 29.2269 Section 29.2269 Agriculture... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) § 29.2269 Fire-cured. Tobacco cured under artificial atmospheric conditions by the use of open fires from which...

  1. 7 CFR 29.2269 - Fire-cured.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Fire-cured. 29.2269 Section 29.2269 Agriculture... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) § 29.2269 Fire-cured. Tobacco cured under artificial atmospheric conditions by the use of open fires from which...

  2. 7 CFR 29.2269 - Fire-cured.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Fire-cured. 29.2269 Section 29.2269 Agriculture... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) § 29.2269 Fire-cured. Tobacco cured under artificial atmospheric conditions by the use of open fires from which...

  3. 7 CFR 29.2269 - Fire-cured.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Fire-cured. 29.2269 Section 29.2269 Agriculture... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) § 29.2269 Fire-cured. Tobacco cured under artificial atmospheric conditions by the use of open fires from which...

  4. [Progress in endogenous plasmid curing of bacteria--a review].

    PubMed

    Feng, Jun; Zhang, Wei; Song, Cunjiang

    2013-11-04

    To investigate the functions of the bacteria endogenous plasmid, which include bacterial drug resistance, symbiosis, capsular formation and heavy metal resistance, the endogenous plasmid needs to be cured first. We reviewed physical, chemical and molecular biological methods of endogenous plasmid curing, clarified the curing principles. The prospective of research on plasmid curing was also discussed, based on our own studies.

  5. 7 CFR 29.3502 - Air-cured.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Air-cured. 29.3502 Section 29.3502 Agriculture... INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) § 29.3502 Air-cured. Tobacco cured under natural atmospheric conditions without the use...

  6. 7 CFR 29.6002 - Air-cured.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Air-cured. 29.6002 Section 29.6002 Agriculture... INSPECTION Standards Definitions § 29.6002 Air-cured. Tobacco cured under natural atmospheric conditions..., pole-burn, and shed-burn in damp weather. Air-cured tobacco should not carry the odor of smoke or...

  7. 7 CFR 29.6002 - Air-cured.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Air-cured. 29.6002 Section 29.6002 Agriculture... INSPECTION Standards Definitions § 29.6002 Air-cured. Tobacco cured under natural atmospheric conditions..., pole-burn, and shed-burn in damp weather. Air-cured tobacco should not carry the odor of smoke or...

  8. 7 CFR 58.412 - Coolers or curing rooms.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Coolers or curing rooms. 58.412 Section 58.412... Specifications for Dairy Plants Approved for USDA Inspection and Grading Service 1 Rooms and Compartments § 58.412 Coolers or curing rooms. Coolers or curing rooms where cheese is held for curing or storage...

  9. Factors affecting the intramolecular decomposition of hexamethylene triperoxide diamine and implications for detection.

    PubMed

    Steinkamp, Frank Lucus; DeGreeff, Lauryn E; Collins, Greg E; Rose-Pehrsson, Susan L

    2016-06-17

    Hexamethylene triperoxide diamine (HMTD) is an easily synthesized and highly sensitive organic peroxide frequently used as a primary explosive. The vapor pressure of HMTD is very low, impeding vapor detection, especially when compared to other peroxide explosives, such as triacetone triperoxide (TATP) or diacetone diperoxide (DADP). Despite this fact, HMTD has a perceptible odor that could be utilized in the indirect detection of HMTD vapor. Headspace measurements above solid HMTD samples confirm that HMTD readily decomposes under ambient conditions to form highly volatile products that include formic acid, ammonia, trimethylamine and formamides. The presence and quantity of these compounds are affected by storage condition, time, and synthetic method, with synthetic method having the most significant effect on the content of the headspace. A kinetic study of HMTD decomposition in solution indicated a correlation between degradation rate and the presence of decomposition species identified in the headspace, and provided further insight into the mechanism of decomposition. The study provided evidence for a proton assisted decomposition reaction with water, as well as an intramolecular decomposition process facilitated by the presence of water.

  10. Degradation of toluene-2,4-diamine by persulphate: kinetics, intermediates and degradation pathway.

    PubMed

    Jiang, Yong-hai; Zhang, Jin-bao; Xi, Bei-dou; An, Da; Yang, Yu; Li, Ming-xiao

    2015-01-01

    In this study, the degradation of toluene-2,4-diamine (TDA) by persulphate (PS) in an aqueous solution at near-neutral pH was examined. The result showed that the degradation rate of TDA increased with increasing PS concentrations. The optimal dosage of PS in the reaction system was determined by efficiency indicator (I) coupling in the consumption of PS and decay half-life of TDA. Calculation showed that 0.74 mM of PS was the most effective dosage for TDA degradation, at that level the maximum I of 24.51 was obtained. PS can oxidize TDA for an extended reaction time period. Under neutral condition without activation, four degradation intermediates, 2,4-diamino-3-hydroxy-5-sulfonicacidtoluene, 2,4-diaminobenzaldehyde, 2,4-bis(vinylamino)benzaldehyde and 3,5-diamino-4-hydroxy-2-pentene, were identified by high-performance liquid chromatography-mass spectrometry. The tentative degradation pathway of TDA was proposed as well. It was found that hydroxyl radical played an important role in degradation of TDA with the activation of Fe2+, whereas PS anion and sulphate radicals were responsible for the degradation without activation of Fe2+.

  11. Engineering biotin prototrophic Corynebacterium glutamicum strains for amino acid, diamine and carotenoid production.

    PubMed

    Peters-Wendisch, P; Götker, S; Heider, S A E; Komati Reddy, G; Nguyen, A Q; Stansen, K C; Wendisch, V F

    2014-12-20

    The Gram-positive Corynebacterium glutamicum is auxotrophic for biotin. Besides the biotin uptake system BioYMN and the transcriptional regulator BioQ, this bacterium possesses functional enzymes for the last three reactions of biotin synthesis starting from pimeloyl-CoA. Heterologous expression of bioF from the Gram-negative Escherichia coli enabled biotin synthesis from pimelic acid added to the medium, but expression of bioF together with bioC and bioH from E. coli did not entail biotin prototrophy. Heterologous expression of bioWAFDBI from Bacillus subtilis encoding another biotin synthesis pathway in C. glutamicum allowed for growth in biotin-depleted media. Stable growth of the recombinant was observed without biotin addition for eight transfers to biotin-depleted medium while the empty vector control stopped growth after the first transfer. Expression of bioWAFDBI from B. subtilis in C. glutamicum strains overproducing the amino acids l-lysine and l-arginine, the diamine putrescine, and the carotenoid lycopene, respectively, enabled formation of these products under biotin-depleted conditions. Thus, biotin-prototrophic growth and production by recombinant C. glutamicum were achieved.

  12. Cooperative insertion of CO2 in diamine-appended metal-organic frameworks.

    PubMed

    McDonald, Thomas M; Mason, Jarad A; Kong, Xueqian; Bloch, Eric D; Gygi, David; Dani, Alessandro; Crocellà, Valentina; Giordanino, Filippo; Odoh, Samuel O; Drisdell, Walter S; Vlaisavljevich, Bess; Dzubak, Allison L; Poloni, Roberta; Schnell, Sondre K; Planas, Nora; Lee, Kyuho; Pascal, Tod; Wan, Liwen F; Prendergast, David; Neaton, Jeffrey B; Smit, Berend; Kortright, Jeffrey B; Gagliardi, Laura; Bordiga, Silvia; Reimer, Jeffrey A; Long, Jeffrey R

    2015-03-19

    The process of carbon capture and sequestration has been proposed as a method of mitigating the build-up of greenhouse gases in the atmosphere. If implemented, the cost of electricity generated by a fossil fuel-burning power plant would rise substantially, owing to the expense of removing CO2 from the effluent stream. There is therefore an urgent need for more efficient gas separation technologies, such as those potentially offered by advanced solid adsorbents. Here we show that diamine-appended metal-organic frameworks can behave as 'phase-change' adsorbents, with unusual step-shaped CO2 adsorption isotherms that shift markedly with temperature. Results from spectroscopic, diffraction and computational studies show that the origin of the sharp adsorption step is an unprecedented cooperative process in which, above a metal-dependent threshold pressure, CO2 molecules insert into metal-amine bonds, inducing a reorganization of the amines into well-ordered chains of ammonium carbamate. As a consequence, large CO2 separation capacities can be achieved with small temperature swings, and regeneration energies appreciably lower than achievable with state-of-the-art aqueous amine solutions become feasible. The results provide a mechanistic framework for designing highly efficient adsorbents for removing CO2 from various gas mixtures, and yield insights into the conservation of Mg(2+) within the ribulose-1,5-bisphosphate carboxylase/oxygenase family of enzymes.

  13. Generator produced I-122 labeled amines and diamines for brain blood flow measurements in neurologic disorders

    SciTech Connect

    Mathis, C.A.; Budinger, T.F.; Sargent, T. III; Shulgin, A.T.; Kung, H.F.

    1985-05-01

    In response to a need for an extracted brain blood flow tracer for positron tomograhy, the authors have developed from our original iodoamphetamine an I-122 radiopharmaceutical produced from a 20h Xe-122 generator and have demonstrated its application in animals and humans. The I-122 (t1/2 3.6m) is collected in the reaction vessel by a 10 min ingrowth from the Xe-122. The radiopharmaceutical, 2,4-dimethoxy-N,N-dimethyl-5(I-122)iodophenylisorpropylamine (5-(I-122)-2,4-DNNA), is synthesized using I-122 and chloramine-T, purified and sterilized for injection in 3 min. Synthesis can be repeated every 20-30 min. The diamine HIPDM was also labeled with I-122 by an exchange reaction for comparison. Using the Donner 280 crystal tomography system, anesthetized dogs showed rapid uptake of the activity in the brain using 5-(I-122)-2,4-DNNA and I-122 HIPDM. The ratio of activity in the brain to surrounding tissue was 6.1 and the distribution was the same as that from 18-FDG injected 30 min later.

  14. cDNA sequences of variant forms of human placenta diamine oxidase

    SciTech Connect

    Zhang, X.; Kim, J.; McIntire, S.

    1995-08-01

    Genes for two forms of human placenta diamine oxidase (dao) were cloned from a cDNA library and sequenced. One gene, pdao1, is identical in length to human kidney dao but differs from it by two bases in the coding region and differs slightly in the 3{prime} - and 5{prime}-noncoding regions. The second gene, pdao2, is nearly identical to these genes in the coding region, except that it has an extra 57-nucleotide coding segment near the 3{prime} end of this region. This segment corresponds to the contiguous sequence of the 3{prime} end of intron 3 of human kidney dao. pdao2 also differs significantly from pdao1 and human kidney dao in a 13-base sequence in the t{prime}-noncoding region. It is proposed that pdao1 and human kidney dao are polymorphic forms of the same allele. Whether pdao2 is a polymorph of these two is not certain, because of the significant differences in the coding and noncoding regions. pdao2 may represent a different allele. 21 refs., 2 figs.

  15. Cooperative insertion of CO2 in diamine-appended metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    McDonald, Thomas M.; Mason, Jarad A.; Kong, Xueqian; Bloch, Eric D.; Gygi, David; Dani, Alessandro; Crocellà, Valentina; Giordanino, Filippo; Odoh, Samuel O.; Drisdell, Walter S.; Vlaisavljevich, Bess; Dzubak, Allison L.; Poloni, Roberta; Schnell, Sondre K.; Planas, Nora; Lee, Kyuho; Pascal, Tod; Wan, Liwen F.; Prendergast, David; Neaton, Jeffrey B.; Smit, Berend; Kortright, Jeffrey B.; Gagliardi, Laura; Bordiga, Silvia; Reimer, Jeffrey A.; Long, Jeffrey R.

    2015-03-01

    The process of carbon capture and sequestration has been proposed as a method of mitigating the build-up of greenhouse gases in the atmosphere. If implemented, the cost of electricity generated by a fossil fuel-burning power plant would rise substantially, owing to the expense of removing CO2 from the effluent stream. There is therefore an urgent need for more efficient gas separation technologies, such as those potentially offered by advanced solid adsorbents. Here we show that diamine-appended metal-organic frameworks can behave as `phase-change' adsorbents, with unusual step-shaped CO2 adsorption isotherms that shift markedly with temperature. Results from spectroscopic, diffraction and computational studies show that the origin of the sharp adsorption step is an unprecedented cooperative process in which, above a metal-dependent threshold pressure, CO2 molecules insert into metal-amine bonds, inducing a reorganization of the amines into well-ordered chains of ammonium carbamate. As a consequence, large CO2 separation capacities can be achieved with small temperature swings, and regeneration energies appreciably lower than achievable with state-of-the-art aqueous amine solutions become feasible. The results provide a mechanistic framework for designing highly efficient adsorbents for removing CO2 from various gas mixtures, and yield insights into the conservation of Mg2+ within the ribulose-1,5-bisphosphate carboxylase/oxygenase family of enzymes.

  16. Concomitant Prevalence of Low Serum Diamine Oxidase Activity and Carbohydrate Malabsorption

    PubMed Central

    Meinitzer, Andreas; Mangge, Harald; Kriegshäuser, Gernot; Halwachs-Baumann, Gabriele; Reininghaus, Eva Z.; Bengesser, Susanne A.; Schnedl, Wolfgang J.

    2016-01-01

    The aim of this retrospective study was to analyze the concomitant prevalence rates for lactose malabsorption (LM), fructose malabsorption (FM), and histamine intolerance (HI) in patients with so far unexplained gastrointestinal (GI) symptoms. A total of 439 outpatients, who presented unclear abdominal discomfort, underwent lactose (50 g) and fructose (25 g) hydrogen (H2) breath tests. Additionally, serum diamine oxidase (DAO) measurements were performed. Individuals with low serum DAO activity (<10 U/mL), GI symptoms, and response to histamine-free diet were diagnosed with HI. Of all 439 patients, 341 (77.7%) were found with 7 various GI conditions. In total, 94 (21.4%), 31 (7.1%), and 100 (22.8%) individuals presented LM, FM, or HI only, whereas 116 (26.4%) patients showed an overlap of GI entities investigated here. Interestingly, 89 out of 241 (36.9%) individuals with carbohydrate malabsorption were also diagnosed with HI (LM + HI: 52 [11.8%], FM + HI: 23 [5.2%], and LM + FM + HI 14 [3.2%] individuals). In conclusion different combinations of LM, FM, and HI are present in individuals with unclear abdominal discomfort/pain. In clinical practice we suggest testing for LM, FM, and additional HI in the diagnostic work-up of these patients. Depending on these various diagnoses possible, patients should get an individualized dietary advice. PMID:28042564

  17. Mass spectrometry analysis of hexamethylene triperoxide diamine by its decomposition products

    NASA Astrophysics Data System (ADS)

    Peña-Quevedo, Alvaro J.; Hernández-Rivera, Samuel P.

    2009-05-01

    Hexamethylene triperoxide diamine (HMTD) is a well known amine peroxide that starts to decompose at ambient temperature. At 40°C HMTD began to break up into volatile pungent compounds, including trimethyl amine. The production of these compounds could be useful for the vapor detection of HMTD by common techniques such as GC-MS and IMS. GC-MS analysis was performed and several volatile amines could be detected including initial reagents, such as hexamine. IMS produced an alarm indicating the presence of other compounds. Open-Air Chemical Ionization (OACI)-Time of Flight (TOF)-Mass Spectroscopy was the most useful technique for the analysis of HMTD. Even at high temperatures (250°C), it was possible to detect the molecular ion at m/z 209.078. Other fragments observed in the mass spectrum were the loss of formaldehyde at m/z 179.069 and the loss of hydrogen peroxide at m/z 145.060. A mixture of 30 ppb of HMTD and triacetone triperoxide (TATP) was successfully analyzed by OACI-TOF-MS, thus demonstrating its feasibility for trace analysis of organic peroxides and related compounds.

  18. Synthesis of ethylene diamine-based ferrocene terminated dendrimers and their application as burning rate catalysts.

    PubMed

    Zain-Ul-Abdin; Wang, Li; Yu, Haojie; Saleem, Muhammad; Akram, Muhammad; Khalid, Hamad; Abbasi, Nasir M; Yang, Xianpeng

    2017-02-01

    Ferrocene-based derivatives are widely used as ferrocene-based burning rate catalysts (BRCs) for ammonium perchlorate (AP)-based propellant. However, in long storage, small ferrocene-based derivatives migrate to the surface of the propellant, which results in changes in the designed burning parameters and finally causes unstable combustion. To retard the migration of ferrocene-based BRCs in the propellant and to increase the combustion of the solid propellant, zero to third generation ethylene diamine-based ferrocene terminated dendrimers (0G, 1G, 2G and 3G) were synthesized. The synthesis of these dendrimers was confirmed by (1)H NMR and FT-IR spectroscopy. The electrochemical behavior of 0G, 1G, 2G and 3G was investigated by cyclic voltammetry (CV) and the burning rate catalytic activity of 0G, 1G, 2G and 3G on thermal disintegration of AP was examined by thermogravimetry (TG) and differential thermogravimetry (DTG) techniques. Anti-migration studies show that 1G, 2G and 3G exhibit improved anti-migration behavior in the AP-based propellant.

  19. Infrared curing simulations of liquid composites molding

    NASA Astrophysics Data System (ADS)

    Nakouzi, S.; Pancrace, J.; Schmidt, F. M.; Le Maoult, Y.; Berthet, F.

    2011-05-01

    Infrared radiation is an effective energy source to cure thermosetting polymers. Its usage is expected to reduce curing time in comparison with thermal heating and mold thermally regulated. In addition, because of the polymerization mechanism and instant on-off control of this power, an improvement in the final properties of the material is also expected. In this paper, we studied the infrared interaction with carbon (or glass) fibers reinforced epoxy matrix, where Liquid resin infusion (LRI) is used to manufacture the composite. Temperature of the composite is a key parameter that affects its mechanical properties and is controlled by the infrared emitters and the exothermic heat released from the polymerization. Radiative heat flux is computed using the in-lab developed software RAYHEAT. Then, the heat flux (or absorbed energy for glass fibers) is exported to the finite element based program COMSOLMULTIPHYSICS where heat balance equation is solved. This equation is coupled with the exothermic heat released during the curing process in order to predict the composite temperature versus time and degree of cure. Numerical simulations will be performed on planar parts (sheet shape) as well as curvilinear shapes. Experimental validations of the infrared curing carbon (glass)-epoxy composite system are presented in this paper Sheet surface temperature distribution are measured thanks to infrared camera. Kinetic parameters were estimated from differential scanning calorimeter (DSC) experimental data.

  20. Infrared curing simulations of liquid composites molding

    SciTech Connect

    Nakouzi, S.; Pancrace, J.; Schmidt, F. M.; Le Maoult, Y.; Berthet, F.

    2011-05-04

    Infrared radiation is an effective energy source to cure thermosetting polymers. Its usage is expected to reduce curing time in comparison with thermal heating and mold thermally regulated. In addition, because of the polymerization mechanism and instant on-off control of this power, an improvement in the final properties of the material is also expected. In this paper, we studied the infrared interaction with carbon (or glass) fibers reinforced epoxy matrix, where Liquid resin infusion (LRI) is used to manufacture the composite. Temperature of the composite is a key parameter that affects its mechanical properties and is controlled by the infrared emitters and the exothermic heat released from the polymerization. Radiative heat flux is computed using the in-lab developed software RAYHEAT. Then, the heat flux (or absorbed energy for glass fibers) is exported to the finite element based program COMSOLMULTIPHYSICS where heat balance equation is solved. This equation is coupled with the exothermic heat released during the curing process in order to predict the composite temperature versus time and degree of cure. Numerical simulations will be performed on planar parts (sheet shape) as well as curvilinear shapes. Experimental validations of the infrared curing carbon (glass)-epoxy composite system are presented in this paper Sheet surface temperature distribution are measured thanks to infrared camera. Kinetic parameters were estimated from differential scanning calorimeter (DSC) experimental data.

  1. Cured products from different animal species.

    PubMed

    Paleari, Maria Antonietta; Moretti, Vittorio Maria; Beretta, Giuseppe; Mentasti, Tiziana; Bersani, Carla

    2003-04-01

    An assessment was made of the proximate composition, pH and a(W) of raw beef, horsemeat and the meat of wild boar, deer and goat. The same assessment, together with one of fatty acids, cholesterol and free amino acids, was made of the same meats as cured products. The raw meat of the different animal species was found to have a reduced lipid, but high protein content. The cured meat of the horse and wild boar had low saturated fatty acid levels; the wild boar, goatmeat and beef were quantitatively similar with regard to monounsaturated fatty acids (MUFA) while in the horsemeat the polyunsaturated fatty acids (PUFA) were more raised, at an intermediate level in deer and extremely reduced in the beef final product. The cholesterol content in the cured product was markedly reduced in the horsemeat. The free amino acids content in the cured deer, wild boar and goat meat was more elevated, than in beef and horse cured meat.

  2. Evaluation of heat-cured resin bases following the addition of denture teeth using a second heat cure.

    PubMed

    Polukoshko, K M; Brudvik, J S; Nicholls, J I; Smith, D E

    1992-04-01

    This study compared heat-cured acrylic resin denture baseplate distortions following a second heat cure used to add the denture teeth. The second heat cure was done with three different water-bath curing temperatures. The distortions were evaluated in three planes by use of a measuring microscope. Recorded distortions were not clinically significant.

  3. Spermidine cures yeast of prions

    PubMed Central

    Speldewinde, Shaun H.; Grant, Chris M.

    2015-01-01

    Prions are self-perpetuating amyloid protein aggregates which underlie various neurodegenerative diseases in mammals. The molecular basis underlying their conversion from a normally soluble protein into the prion form remains largely unknown. Studies aimed at uncovering these mechanism(s) are therefore essential if we are to develop effective therapeutic strategies to counteract these disease-causing entities. Autophagy is a cellular degradation system which has predominantly been considered as a non-selective bulk degradation process which recycles macromolecules in response to starvation conditions. We now know that autophagy also serves as a protein quality control mechanism which selectively degrades protein aggregates and damaged organelles. These are commonly accumulated in various neurodegenerative disorders including prion diseases. In our recent study [Speldewinde et al. Mol. Biol. Cell. (2015)] we used the well-established yeast [PSI+]/Sup35 and [PIN¬+]/Rnq1 prion models to show that autophagy prevents sporadic prion formation. Importantly, we found that spermidine, a polyamine that has been used to increase autophagic flux, acts as a protective agent which prevents spontaneous prion formation.

  4. Bond strengths of lingual orthodontic brackets bonded with light-cured composite resins cured by transillumination.

    PubMed

    King, L; Smith, R T; Wendt, S L; Behrents, R G

    1987-04-01

    A method of curing light-cured composite resins by transillumination to cement acid-etched fixed partial dentures was adapted to bond solid mesh-backed lingual orthodontic brackets. Results of this investigation showed that the bond strengths of the orthodontic brackets bonded with light-cured composite resins were significantly less (P less than 0.05) than the bond strengths of the orthodontic brackets cemented with traditional adhesives and orthodontic composite resins. Notwithstanding, the bond strengths achieved with the transilluminated light-cured composite resins should be adequate to withstand the forces of mastication and orthodontic movements. There was no correlation of bond strengths of the brackets cemented with the transilluminated light-cured composite resins when compared to the faciolingual widths of the teeth.

  5. Agent Orange

    MedlinePlus

    ... Index Agent Orange Agent Orange Home Facts about Herbicides Veterans' Diseases Birth Defects Benefits Exposure Locations Provider ... Orange Parkinson’s Awareness Month Were you exposed to herbicides during service and have Parkinson’s disease? You may ...

  6. Targeting the Brain Reservoirs: Toward an HIV Cure

    PubMed Central

    Marban, Céline; Forouzanfar, Faezeh; Ait-Ammar, Amina; Fahmi, Faiza; El Mekdad, Hala; Daouad, Fadoua; Rohr, Olivier; Schwartz, Christian

    2016-01-01

    One of the top research priorities of the international AIDS society by the action “Towards an HIV Cure” is the purge or the decrease of the pool of all latently infected cells. This strategy is based on reactivation of latently reservoirs (the shock) followed by an intensifying combination antiretroviral therapy (cART) to kill them (the kill). The central nervous system (CNS) has potential latently infected cells, i.e., perivascular macrophages, microglial cells, and astrocytes that will need to be eliminated. However, the CNS has several characteristics that may preclude the achievement of a cure. In this review, we discuss several limitations to the eradication of brain reservoirs and how we could circumvent these limitations by making it efforts in four directions: (i) designing efficient latency-reversal agents for CNS-cell types, (ii) improving cART by targeting HIV transcription, (iii) improving delivery of HIV drugs in the CNS and in the CNS-cell types, and (iv) developing therapeutic immunization. As a prerequisite to these efforts, we also believe that a better comprehension of molecular mechanisms involved in establishment and persistence of HIV latency in brain reservoirs are essential to design new molecules for strategies aiming to achieve a cure for instance the “shock and kill” strategy. PMID:27746784

  7. The effect of simplified adhesives on the bond strength to dentin of dual-cure resin cements.

    PubMed

    Shade, A M; Wajdowicz, M N; Bailey, C W; Vandewalle, K S

    2014-01-01

    The purpose of this study was to compare the shear bond strengths to dentin of two dual-cure resin cements, one with a unique initiator, NX3 (Kerr Corp), and the other with a traditional redox-initiator system, Calibra (Dentsply), when used in combination with simplified or nonsimplified adhesive agents. The two dual-cure resin cements, in either self- or dual-cure activation modes, were bonded to human dentin with four dental adhesives to create 16 subgroups of 10 specimens each. After 24 hours of storage in distilled water at 37°C, the specimens were tested in shear in a universal testing machine. With both NX3 and Calibra, bond strengths significantly increased when the specimens were dual cured. In addition, with either cement in either mode, the nonsimplified adhesives performed significantly better than did the simplified adhesive bonding agents. When used specifically with simplified adhesives in either cure mode, NX3 did not produce significantly higher bond strengths than did Calibra. In general, lower dentin bond strengths were found with simplified adhesives or self-cure activation with either resin cement.

  8. Light curing time reduction: in vitro evaluation of new intensive light-emitting diode curing units.

    PubMed

    Mavropoulos, A; Staudt, C B; Kiliaridis, S; Krejci, I

    2005-08-01

    The aim of the present in vitro study was to establish the minimum necessary curing time to bond stainless steel brackets (Mini Diamond Twin) using new, intensive, light-emitting diode (LED) curing units. Seventy-five bovine primary incisors were divided into five equal groups. A standard light curing adhesive (Transbond XT) was used to bond the stainless steel brackets using different lamps and curing times. Two groups were bonded using an intensive LED curing lamp (Ortholux LED) for 5 and 10 seconds. Two more groups were bonded using another intensive LED curing device (Ultra-Lume LED 5) also for 5 and 10 seconds. Finally, a high-output halogen lamp (Optilux 501) was used for 40 seconds to bond the final group, which served as a positive control. All teeth were fixed in hard acrylic and stored for 24 hours in water at 37 degrees C. Shear bond strength (SBS) was measured using an Instron testing machine. Weibull distribution and analysis of variance were used to test for significant differences. The SBS values obtained were significantly different between groups (P < 0.001). When used for 10 seconds, the intensive LED curing units achieved sufficient SBS, comparable with the control. In contrast, 5 seconds resulted in significantly lower SBS. The adhesive remnant index (ARI) was not significantly affected.A curing time of 10 seconds was found to be sufficient to bond metallic brackets to incisors using intensive LED curing units. These new, comparatively inexpensive, curing lamps seem to be an advantageous alternative to conventional halogen lamps for bonding orthodontic brackets.

  9. Lower-curing-temperature PMR polyimides

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    Studies were performed to achieve a lower-curing-temperature PMR polyimide. The use of m-aminostyrene as the end-cap instead of the monoalkyl ester of 5-normbornene-2,3 dicarboxylic acid was investigated in typical PMR formulations. Model compound studies were also performed. Differential scanning calorimetry studies were performed on model compounds and neat resins to establish their melting and curing characteristics. The elevated temperature weight loss characteristics of neat resins and graphite fiber composites were determined. The room temperature and short-time 260 C (500 F) mechanical properties of the composites were also determined. The use of m-aminostyrene end-caps reduced the final cure temperature of PMR resins by about 55 C (100 F), but the composites prepared with these resins are limited to use temperatures of about 260 C (500 F).

  10. The research of UV curing injection molding

    NASA Astrophysics Data System (ADS)

    Xie, Pengcheng; Chang, Le; Song, Le; Cai, Tianze; Ding, Yumei; Yang, Weimin

    2015-05-01

    The micro-injection molding technology and the UV (ultraviolet) curing technique are combined to bring about a new plastic forming method, UV curing injection molding. The mean weight of micro-product is an important process characteristic for UV curing injection molding as well as the surface quality of micro-features is another important process characteristic for this new plastic forming method. This research investigates three effects of processing factors on the mass-change rate of micro-product and the surface quality of micro-features. In every particular, the following two factors are considered: UV material system temperature and the packing pressure. The study revealed that as usual, the micro-products gain weight with the imported increasing UV material system temperature and the improved packing pressure. Meanwhile, the increasing packing pressure also improves the surface quality, yet, warming the UV system temperature up has no effect on the quality of the product.

  11. Integrative physicians and an herbal cancer "cure".

    PubMed

    Ben-Arye, Eran; Rosenberg, Shoshana Keren; Samuels, Noah

    2016-08-01

    Oncologists are frequently asked about herbal remedies claiming to "cure" cancer, or at least delay its progression. While complementary and integrative medicine (CIM) should be aimed primarily at improving quality-of-life (QOL) related concerns, "wonder cures" are part of an alternative health belief model providing hope for a "miracle" where conventional treatment has failed. We describe a physician with extensive small-cell lung cancer (SCLC) undergoing chemotherapy, with significant toxicities and impaired daily function. He had come for an integrative physician (IP) consultation, provided by a medical doctor dually trained in CIM and supportive cancer care, taking place in a conventional supportive cancer care service. We describe the IP consultation in general and regarding an herbal remedy which was being promoted as a "cure" for cancer. The subsequent patient-tailored CIM treatment process, in which patients receive evidence-based guidance on treatments which address QOL-related concerns, are presented.

  12. Cure-in-place process for seals

    DOEpatents

    Hirasuna, Alan R.

    1981-01-01

    A cure-in-place process which allows a rubber seal element to be deformed to its service configuration before it is cross-linked and, hence, is a plastic and does not build up internal stress as a result of the deformation. This provides maximum residual strength to resist the differential pressure. Furthermore, the process allows use of high modulus formulations of the rubber seal element which would otherwise crack if cured and then deformed to its service configuration, resulting in a seal which has better gap bridging capability. Basically, the process involves positioning an uncured seal element in place, deforming it to its service configuration, heating the seal element, curing it in place, and then fully seating the seal.

  13. Crime, criminals, and cures: medical model revisited.

    PubMed

    Sampson, R J

    2000-06-01

    David Lykken's target article assesses the causes of crime and advocates a controversial "cure"--parental licensure. Although Lykken gets many of the facts about criminals right, ultimately the disease metaphor breaks down. Crime requires three things--motivated offenders ("criminals"), suitable targets or victims, and the absence of capable guardians to prevent the act. Typical of medical model approaches, failure to consider the convergence in time and space of the three necessary elements for crime results in a misdiagnosis. In this invited commentary, I briefly note three reasons why Lykken's cure, along with the medical model in general, is unlikely to bear fruit.

  14. Chiropractor charged with claiming HIV cure.

    PubMed

    1999-07-23

    The Missouri Board of Chiropractic Examiners will decide later this year if [name removed]' license should be revoked or suspended because [name removed] allegedly told an HIV-positive patient that he had been cured. [Name removed] denies claiming that the patient was cured by his Interro machine. The patient claims he and his wife then decided to have children. The mother gave birth in 1992, and although the infant is not infected, the mother is. The patient's mother-in-law testified that [name removed] had assured her that the patient's virus had been absolutely eradicated by his treatments.

  15. The mechanisms of cure in psychoanalysis.

    PubMed

    Lander, Rómulo

    2007-01-01

    The author considers the theoretical contributions of Lacan and Bion in relation to therapeutic action or the mechanisms of the cure. Whereas Bion felt that the analysand should ultimately experience transformation in O, Lacan described the analysand's goal as not to give in to one's desire or to be one's self. The author distinguishes among various types of neurotic and psychotic structures in discussing the limits of the cure, noting that the analyst's acts--as well as his words--can function as analytic interpretations. Lacan's theories of jouissance, the sexual phantom, identification with the analytic function, and post-analytic effects are also discussed.

  16. FTIR Monitoring Of Curing Of Composites

    NASA Technical Reports Server (NTRS)

    Druy, Mark A.; Stevenson, William A.; Young, Philip R.

    1990-01-01

    Infrared-sensing optical fiber system developed to monitor principal infrared absorption bands resulting from vibrations of atoms and molecules as chemical bonds form when resin cured. System monitors resin chemistry more directly. Used to obtain Fourier transform infrared (FTIR) spectrum from graphite fiber/polyimide matrix resin prepreg. Embedded fiber optic FTIR sensor used to indicate state of cure of thermosetting composite material. Developed primarily to improve quality of advanced composites, many additional potential applications exist because principal of operation applicable to all organic materials and most inorganic gases. Includes monitoring integrities of composite materials in service, remote sensing of hazardous materials, and examination of processes in industrial reactors and furnaces.

  17. Residual monomer leaching from chemically cured and visible light-cured orthodontic adhesives.

    PubMed

    Eliades, T; Eliades, G; Brantley, W A; Johnston, W M

    1995-09-01

    The objective of this study was to quantify the amount of residual monomer leached from chemically cured and visible light-cured orthodontic adhesives based on Bis-GMA/TEGDMA monomers, when bonded to ceramic and stainless steel brackets. The residual TEGDMA and Bis-GMA monomer concentrations were determined by high performance liquid chromatographic (HPLC) analysis of the extracts after specimen immersion in ethanol/water solution for 15 days at 37 +/- 1 degree C. According to the results the highest monomer concentrations eluted were obtained from the chemically cured adhesive. Direct (through the bracket) irradiation of stainless steel brackets bonded to the visible light-cured adhesive showed high monomer elution as well. A polycarbonate base ceramic bracket manifested significantly greater amount of monomer release compared with ceramic brackets when combined with the visible light-cured adhesive. Indirect (from the incisal and cervical edges of the bracket) irradiation of the visible light-cured adhesive bonded to the stainless steel brackets resulted in lower residual monomer elution compared to that of directly (through the bracket) irradiated metallic brackets. No statistical difference was found between direct or indirect irradiation of the ceramic brackets tested, with respect to monomer elution from the light-cured adhesive.

  18. Curing kinetics of visible light curing dental resin composites investigated by dielectric analysis (DEA).

    PubMed

    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.

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

    PubMed

    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.

  20. Fermentative Production of the Diamine Putrescine: System Metabolic Engineering of Corynebacterium Glutamicum

    PubMed Central

    Nguyen, Anh Q. D.; Schneider, Jens; Reddy, Gajendar Komati; Wendisch, Volker F.

    2015-01-01

    Corynebacterium glutamicum shows great potential for the production of the glutamate-derived diamine putrescine, a monomeric compound of polyamides. A genome-scale stoichiometric model of a C. glutamicum strain with reduced ornithine transcarbamoylase activity, derepressed arginine biosynthesis, and an anabolic plasmid-addiction system for heterologous expression of E. coli ornithine decarboxylase gene speC was investigated by flux balance analysis with respect to its putrescine production potential. Based on these simulations, enhancing glycolysis and anaplerosis by plasmid-borne overexpression of the genes for glyceraldehyde 3-phosphate dehydrogenase and pyruvate carboxylase as well as reducing 2-oxoglutarate dehydrogenase activity were chosen as targets for metabolic engineering. Changing the translational start codon of the chromosomal gene for 2-oxoglutarate dehydrogenase subunit E1o to the less preferred TTG and changing threonine 15 of OdhI to alanine reduced 2-oxoglutarate dehydrogenase activity about five fold and improved putrescine titers by 28%. Additional engineering steps improved further putrescine production with the largest contributions from preventing the formation of the by-product N-acetylputrescine by deletion of spermi(di)ne N-acetyltransferase gene snaA and from overexpression of the gene for a feedback-resistant N-acetylglutamate kinase variant. The resulting C. glutamicum strain NA6 obtained by systems metabolic engineering accumulated two fold more putrescine than the base strain, i.e., 58.1 ± 0.2 mM, and showed a specific productivity of 0.045 g·g−1·h−1 and a yield on glucose of 0.26 g·g−1. PMID:25919117

  1. Vapor Pressure of Hexamethylene Triperoxide Diamine (HMTD) Estimated Using Secondary Electrospray Ionization Mass Spectrometry.

    PubMed

    Aernecke, Matthew J; Mendum, Ted; Geurtsen, Geoff; Ostrinskaya, Alla; Kunz, Roderick R

    2015-11-25

    A rapid method for vapor pressure measurement was developed and used to derive the vapor pressure curve of the thermally labile peroxide-based explosive hexamethylene triperoxide diamine (HMTD) over the temperature range from 28 to 80 °C. This method uses a controlled flow of vapor from a solid-phase HMTD source that is presented to an ambient-pressure-ionization mass spectrometer equipped with a secondary-electrospray-ionization (SESI) source. The subpart-per-trillion sensitivity of this system enables direct detection of HMTD vapor through an intact [M + H](+) ion in real time at temperatures near 20 °C. By calibrating this method using vapor sources of cocaine and heroin, which have known pressure-temperature (P-T) curves, the temperature dependence of HMTD vapor was determined, and a Clausius-Clapeyron plot of ln[P (Pa)] vs 1/[T (K)] yielded a straight line with the expression ln[P (Pa)] = {(-11091 ± 356) × 1/[T (K)]} + 25 ± 1 (error limits are the standard error of the regression analysis). From this equation, the sublimation enthalpy of HMTD was estimated to be 92 ± 3 kJ/mol, which compares well with the theoretical estimate of 95 kJ/mol, and the vapor pressure at 20 °C was estimated to be ∼60 parts per trillion by volume, which is within a factor of 2 of previous theoretical estimates. Thus, this method provides not only the first direct experimental determination of HMTD vapor pressure but also a rapid, near-real-time capability to quantitatively measure low-vapor-pressure compounds, which will be useful for aiding in the development of training aids for bomb-sniffing canines.

  2. Self-assembly of gold nanoparticles induced by poly(oxypropylene)diamines.

    PubMed

    Huang, Hsin-Yeh; Chen, Wei-Fu; Kuo, Ping-Lin

    2005-12-29

    A series of poly(oxypropylene)diamines D230, D400, D2000, and D4000, having molecular weights of hydrophobic segments of 230, 400, 2000, and 4000, were used as ligands to synthesize self-organized gold nanocrystals. Ligand exchange significantly reduced the average particle size and the polydispersity of nanocrystals, and this effect was more remarkable as the molar ratio of amine groups to Au3+ ions ([N]/[Au3+] ratio) was increased. Under the same [N]/[Au3+] ratio of 100, D2000 generated an ordered 2D-monolayer; however, D230 and D400 colloids formed mainly a densely packed 3D structure with minor 2-D layers, and D4000 presented disordered 3D and 2D structures. The gap among the nanoparticles was found to be increased with the increasing molecular weight of the hydrophobic segment of ligands, accompanied by the decreasing wavelength of UV-vis absorption bands. This increased gap can be interpreted as the ligand thickness calculated from the equation of steric force increasing with increasing molecular weight of the hydrophobic segment. The potential energies obtained from the calculated ligand thickness according to the soft sphere model show more steep potential wells for D230 and D400 colloids than that for the D2000 colloid. This explains why the aggregation hardly occurred for the gold nanoparticles obtained under D2000, where the nanoparticles are single crystals having face center crystal structure with a lattice constant of 2.36 A and have grain sizes close to the average particle sizes, evidenced from the results of transmission electron microscopy and X-ray diffraction spectroscopy.

  3. Effect of creatinine and specific gravity normalization on urinary biomarker 1,6-hexamethylene diamine.

    PubMed

    Gaines, Linda G T; Fent, Kenneth W; Flack, Sheila L; Thomasen, Jennifer M; Ball, Louise M; Zhou, Haibo; Whittaker, Stephen G; Nylander-French, Leena A

    2010-03-01

    Urine amine levels used as biomarkers of diisocyanate exposure have usually been normalized with creatinine concentration. The suitability of using creatinine concentration or specific gravity for these biomarkers in exposure assessment has not been established. We investigated the effect of creatinine concentration and specific gravity on urine 1,6-hexamethylene diamine (HDA) levels in multiple mixed linear regression models using quantitative dermal and inhalation exposure data derived from a survey of automotive spray painters occupationally exposed to 1,6-hexamethylene diisocyanate (HDI). Painters' dermal and breathing-zone HDI exposure were monitored for an entire workday for up to three workdays spaced approximately one month apart. One urine sample was collected before the start of work with HDI-containing paints, and multiple samples were collected throughout the workday. Both creatinine concentration and specific gravity were highly significant predictors (p < 0.0001) of urine HDA levels. When these two were used together in the same model, creatinine remained highly significant (p < 0.0001), but specific gravity decreased in significance (p-values 0.10-0.17). We used different individual factors to determine which affected creatinine and specific gravity. Urine collection time was a highly significant predictor of specific gravity (p = 0.003) and creatinine concentration (p = 0.001). Smoker status was significant (p = 0.026) in the creatinine model. The findings indicate that creatinine concentration is more appropriate to account for urine water content than specific gravity and that creatinine is best used as an independent variable in HDI exposure assessment models instead of traditional urine normalization with creatinine concentration.

  4. Modeling the interaction Between Ethylene Diamine and Water Films on the Surface of a Carbon Nanotube

    NASA Technical Reports Server (NTRS)

    Jaffe, Richard L.; Walther, Jens H.; Zimmerli, Urs; Koumoutsakos, Petros

    2004-01-01

    It has been observed that a carbon nanotube (CNT) AFM tip coated with ethylene diamine (EDA) penetrates the liquid water-air interface more easily than an uncoated nanotube tip. The EDA coating remains intact through repeated cycles of dipping and removal. In order to understand the physical basis for this observation, we use ab initio quantum chemistry calculations to study the EDA-CNT-water interaction and to parameterize a force field describing this system. Molecular dynamics (MD) simulations are carried out for EDA-water mixtures and an EDA-coated carbon nanotube immmed in water. These simulations are similar to our earlier MD study that characterized the CNT-water interface. The attractive CNT-EDA and CNT-water interactions arise primarily from van der Waals forces, and the EDA-EDA, EDA-water and water-water interactions are mainly due to hydrogen bond formation. The binding energ of single EDA molecule to the nanotube is nearly three times larger than the corresponding value found for water (4.3 versus 1.5 kcal mol, respectively). The EDA molecules readily stick to and diffuse along the CNT surface. As a resulf mixing of the EDA and water films does not occur on the timescale of the MD simulations. The EDA film reduces the hydrophobicity of the nanotube surface and acts like a prototypical surfactant in stabilizing the suspension of carbon nanotubes in water. For this presentation, we use the MD simulations to determine how the presence of the carbon nanotube surface perturbs the properties of EDA-water mixtures.

  5. Advanced Fast Curing Adhesives for Adverse Conditions

    DTIC Science & Technology

    2007-07-01

    set of battle damage repair adhesives include Belzona 2311 elastomer , Belzona 1221 super metal, and Belzona metal plug, which are very fast curing...resin, and dinonylphenol (10). Marine use A-788 Splash Zone epoxy- polyamide mastic from Z Spar, Los Angeles, CA was used for testing (11). The

  6. Campus Violence: Kinds, Causes, and Cures.

    ERIC Educational Resources Information Center

    Whitaker, Leighton C., Ed.; Pollard, Jeffrey W., Ed.

    This volume offers 14 papers on the types, sources, and possible cures of violence on college campuses from prominent workers in higher education. Following a preface the titles are: (1) "Conceptualizing Campus Violence: Definitions, Underlying Factors, and Effects" by Mary L. Roark; (2) "Administrative Perspectives on Disruptive…

  7. Quantitative prediction of stresses during thermoset cure

    SciTech Connect

    Adolf, D.; Chambers, B.; Burchett, S.

    1996-07-01

    Two thin-walled Al tubes were filled with epoxy which were cured isothermally; one tube was instrumented with strain gauges, and the other with thermocouples. Finite element codes were used. Predicted and measured centerline hoop strains are shown; predictions and measurements agree. This is being applied to encapsulated components.

  8. Audacious Cures for America's Ailing Schools

    ERIC Educational Resources Information Center

    Gevirtzman, Bruce

    2011-01-01

    The problems in our nation's schools, and the cures for those problems, have been mired in confusion, innuendo, and deception. It is time someone separated the truths about our schools from the lies. Now retired from education, and finally free to speak up, veteran high school teacher Bruce J. Gevirtzman reveals his shocking ideas for fixing our…

  9. Novel Agents for the Treatment of Multiple Myeloma: Proteasome Inhibitors and Immunomodulatory Agents

    PubMed Central

    Kurtin, Sandra E.; Bilotti, Elizabeth

    2013-01-01

    The integration of novel agents into the treatment of multiple myeloma (MM) has shifted the focus from an incurable disease to one that is chronic, with a realistic hope of someday achieving a cure. Proteasome inhibitors and immunomodulatory agents are the backbone of novel therapies for MM. These agents are particularly important for patients with relapsed or refractory disease, a fate faced by the majority of myeloma patients over the course of their disease. Review of recent clinical trial data for the proteasome inhibitors and immunomodulatory agents, including clinical efficacy and safety information, will assist the advanced practitioner in oncology with integrating these data into the current treatment guidelines for MM. PMID:25032010

  10. Rhenium(I) polypyridine diamine complexes as intracellular phosphorogenic sensors: synthesis, characterization, emissive behavior, biological properties, and nitric oxide sensing.

    PubMed

    Choi, Alex Wing-Tat; Yim, Vicki Man-Wai; Liu, Hua-Wei; Lo, Kenneth Kam-Wing

    2014-07-28

    We report the development of a series of rhenium(I) polypyridine complexes appended with an electron-rich diaminoaromatic moiety as phosphorogenic sensors for nitric oxide (NO). The diamine complexes [Re(N^N)(CO)3 (py-DA)][PF6 ] (py-DA=3-(N-(2-amino-5-methoxyphenyl)aminomethyl)pyridine; N^N=1,10-phenanthroline (phen) (1 a), 3,4,7,8-tetramethyl-1,10-phenanthroline (Me4 -phen) (2 a), 4,7-diphenyl-1,10-phenanthroline (Ph2 -phen) (3 a)) have been synthesized and characterized. In contrast to common rhenium(I) diimines, these diamine complexes were very weakly emissive due to quenching of the triplet metal-to-ligand charge-transfer ((3) MLCT) emission by the diaminoaromatic moiety through photoinduced electron transfer (PET). Upon treatment with NO, the complexes were converted into the triazole derivatives [Re(N^N)(CO)3 (py-triazole)][PF6 ] (py-triazole=3-((6-methoxybenzotriazol-1-yl)methyl)pyridine; N^N=phen (1 b), Me4 -phen (2 b), Ph2 -phen (3 b)), resulting in significant emission enhancement (I/I0 ≈60). The diamine complexes exhibited high reaction selectivity to NO, and their emission intensity was found to be independent on pH. Also, these complexes were effectively internalized by HeLa cells and RAW264.7 macrophages with negligible cytotoxicity. Additionally, the use of complex 3 a as an intracellular phosphorogenic sensor for NO has been demonstrated.

  11. In Vitro Antileishmanial, Trypanocidal, and Mammalian Cell Activities of Diverse N,N′ -Dihetaryl Substituted Diamines and Related Compounds

    PubMed Central

    Leal, Sandra M.; Amado, Diego F.; Kouznetsov, Vladimir V.; Escobar, Patricia

    2013-01-01

    The leishmaniasis and Chagas diseases constitute a serious public health problem worldwide with few and ineffective treatment options. The search for new antiparasitic candidates at the initial steps of drug discovery and development is still necessary. The synthesis of 22 de novo synthetized N,N′-dihetaryl-alkyldiamine derivatives and in vitro antiparasitic activity were evaluated for the first time against intracellular and extracellular forms of Leishmania (Leishmania) infantum, L. (Viannia) panamensis, L. (Leishmania) amazonensis, and Trypanosoma cruzi. Additionally, the toxicity on mammalian cells was determined. Some of these substituted N,N′-diamines (25–35 % of the tested compounds) showed interesting results against free-living forms of parasites with activities at the inhibitory concentration (IC50) level of 1.96 to 28.83 μM for L. (L.) infantum promastigotes and IC50 of 0.02 to 5.31 μM for T. cruzi epimastigotes. No activity at the IC50 level on intracellular amastigotes of T. cruzi was observed. However, N1,N2-dibenzylethane-1,2-diamine 5a revealed an important activity against the intracellular amastigotes of L. infantum (IC50 25.42 μM ±0.33) and L. panamensis (IC50 58.20 μM ±3.23), while their analogue N1,N4-dibenzylbutane-1,4-diamine 5c resulted in activity only against L. panamensis (IC50 11.19 μM ±0.20) without toxicity on Vero and THP-1 mammalian cells. The active compounds against intracellular parasites with low toxicity in mammalian cells may be considered for future studies in experimental models. PMID:23641328

  12. Characterization of the relationship of the cure cycle chemistry to cure cycle processing properties

    NASA Technical Reports Server (NTRS)

    Kranbuehl, D. E.

    1985-01-01

    Dynamic dielectric analysis (DDA) is used to study curing polymer systems and thermoplastics. Measurements are made over a frequency range of six decades. This wide range of frequencies increases the amount of information which can be obtained. The data is analyzed in terms of the frequency dependence of the complex permittivity epsilon sup *, specific conductivity sigma (ohm/cm) and the relaxation time tau, parameters which are characteristic of the cure state of the material and independent of the size of the sample.

  13. Dibromido[N-propyl-N'-(2-pyridylmethyl-idene)ethane-1,2-diamine]zinc(II).

    PubMed

    Zhu, Xue-Wen; Yang, Xu-Zhao

    2008-07-31

    The title complex, [ZnBr(2)(C(11)H(17)N(3))], is a mononuclear zinc(II) compound derived from the Schiff base N-propyl-N'-(1-pyridin-2-ylmethyl-idene)ethane-1,2-diamine. The Zn(II) atom is five-coordinate, binding to the imine N, pyridine N, and amine N atoms of the Schiff base ligand and to two bromide anions in a distorted trigonal-bipyramidal coordination geometry. Adjacent mol-ecules are linked through inter-molecular N-H⋯Br hydrogen bonds, forming dimers.

  14. Bond strength of a light-cured and two auto-cured glass ionomer liners.

    PubMed

    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.

  15. Cationic cure kinetics of a polyoxometalate loaded epoxy nanocomposite

    SciTech Connect

    Anderson, Benjamin J.

    2012-08-06

    The reaction cure kinetics of a novel polyoxometalate (POM) loaded epoxy nanocomposite is described. The POM is dispersed in the epoxy resin up to volume fractions of 0.1. Differential scanning calorimetry measurements show the cure of the epoxy resin to be sensitive to the POM loading. A kinetics study of the cure exotherm confirms that POM acts as a catalyst promoting cationic homopolymerization of the epoxy resin. The cure reaction is shown to propagate through two cure regimes. A fast cure at short time is shown to be propagation by the activated chain end (ACE) mechanism. A slow cure at long time is shown to be propagation by the activated monomer (AM) mechanism. The activation energies for the fast and slow cure regimes agree well with other epoxy based systems that have been confirmed to propagate by the ACE and AM mechanisms.

  16. A Study of Upgraded Phenolic Curing for RSRM Nozzle Rings

    NASA Technical Reports Server (NTRS)

    Smartt, Ziba

    2000-01-01

    A thermochemical cure model for predicting temperature and degree of cure profiles in curing phenolic parts was developed, validated and refined over several years. The model supports optimization of cure cycles and allows input of properties based upon the types of material and the process by which these materials are used to make nozzle components. The model has been refined to use sophisticated computer graphics to demonstrate the changes in temperature and degree of cure during the curing process. The effort discussed in the paper will be the conversion from an outdated solid modeling input program and SINDA analysis code to an integrated solid modeling and analysis package (I-DEAS solid model and TMG). Also discussed will be the incorporation of updated material properties obtained during full scale curing tests into the cure models and the results for all the Reusable Solid Rocket Motor (RSRM) nozzle rings.

  17. Silicone rubber curing by high intensity infrared radiation

    SciTech Connect

    Huang, T.; Tsai, J.; Cherng, C.; Chen, J.

    1994-08-10

    A high-intensity (12 kW) and compact (80 cm) infrared heating oven for fast curing (12 seconds) of tube-like silicone rubber curing studies is reported. Quality inspection by DSC and DMA and results from pilot-scale curing oven all suggest that infrared heating provides a better way of vulcanization regarding to curing time, quality, cost, and spacing over conventional hot air heating. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  18. Silicone rubber curing by high intensity infrared radiation

    NASA Astrophysics Data System (ADS)

    Huang, Tung-Way; Tsai, Jen-Hui; Cherng, Chung-Pin; Chen, Jan-Ku

    1994-08-01

    A high-intensity (12 kW) and compact (80 cm) infrared heating oven for fast curing (12 seconds) of tube-like silicone rubber curing studies is reported. Quality inspection by DSC and DMA and results from pilot-scale curing oven all suggest that infrared heating provides a better way of vulcanization regarding to curing time, quality, cost, and spacing over conventional hot air heating.

  19. Electron Beam Curing of Polymer Matrix Composites - CRADA Final Report

    SciTech Connect

    Janke, C. J.; Howell, Dave; Norris, Robert E.

    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.

  20. 7 CFR 29.6002 - Air-cured.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... INSPECTION Standards Definitions § 29.6002 Air-cured. Tobacco cured under natural atmospheric conditions. Artificial heat sometimes is used to control excess humidity during the curing period to prevent pole-sweat... resulting from the application of artificial heat....

  1. 7 CFR 30.12 - Fire-cure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 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...

  2. 7 CFR 30.12 - Fire-cure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 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...

  3. 7 CFR 30.12 - Fire-cure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 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...

  4. 7 CFR 30.12 - Fire-cure.

    Code of Federal Regulations, 2010 CFR

    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...

  5. 7 CFR 30.12 - Fire-cure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 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...

  6. 7 CFR 29.3502 - Air-cured.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) § 29.3502 Air-cured. Tobacco cured under natural atmospheric conditions without the use of fire, except for the purpose of preventing pole-burn in damp weather....

  7. Hematopoietic stem cell transplantation for HIV cure

    PubMed Central

    Kuritzkes, Daniel R.

    2016-01-01

    The apparent cure of an HIV-infected person following hematopoietic stem cell transplantation (HSCT) from an allogeneic donor homozygous for the ccr5Δ32 mutation has stimulated the search for strategies to eradicate HIV or to induce long-term remission without requiring ongoing antiretroviral therapy. A variety of approaches, including allogeneic HSCT from CCR5-deficient donors and autologous transplantation of genetically modified hematopoietic stem cells, are currently under investigation. This Review covers the experience with HSCT in HIV infection to date and provides a survey of ongoing work in the field. The challenges of developing HSCT for HIV cure in the context of safe, effective, and convenient once-daily antiretroviral therapy are also discussed. PMID:26731468

  8. Vacuum deposition and curing of liquid monomers

    DOEpatents

    Affinito, John D.

    1993-01-01

    The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of "standard" polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface.

  9. Vacuum deposition and curing of liquid monomers

    DOEpatents

    Affinito, John D.

    1995-01-01

    The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of "standard" polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal or oxide may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface.

  10. Vacuum deposition and curing of liquid monomers

    DOEpatents

    Affinito, J.D.

    1993-11-09

    The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of standard polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface.

  11. Vacuum deposition and curing of liquid monomers

    DOEpatents

    Affinito, J.D.

    1995-03-07

    The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of ``standard`` polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal or oxide may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface.

  12. Light-Curing Adhesive Repair Tapes

    NASA Technical Reports Server (NTRS)

    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.

  13. Aloe vera as cure for lichen planus.

    PubMed

    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.

  14. Plasma diamine oxidase: a biomarker of copper deficiency in the bovine.

    PubMed

    Legleiter, L R; Spears, J W

    2007-09-01

    This study was designed to test the efficacy of plasma diamine oxidase (DAO) activity as a biomarker of Cu deficiency in the bovine. Angus steers (n = 11) and heifers (n = 17) were assigned to 1 of 3 treatments: 1) control (adequate dietary Cu), 2) Cu-deficient (-Cu), and 3) Cu-deficient plus high dietary Mn (-Cu+Mn), and fed from weaning through finishing. Molybdenum (2 mg/kg of DM) was supplemented to treatments -Cu and -Cu+Mn to induce Cu deficiency via the formation of ruminal thiomolybdates. Samples were collected on 2 sampling dates (d 160 and 190) to determine the efficacy of plasma DAO activity as a biomarker of Cu deficiency. For both sampling dates, liver Cu, plasma Cu, and plasma ceruloplasmin activity indicated that cattle receiving diets designed to induce Cu deficiency (-Cu and -Cu+Mn) were Cu-deficient, with all indices of Cu status lower (P < 0.001) than the control animals. In addition to these traditional indices of Cu status, plasma DAO activity also effectively identified Cu-deficient animals because plasma DAO levels were reduced (P < 0.001) by 2- to 3-fold compared with controls. Correlation analysis indicated that plasma DAO activity was highly correlated to all other indices of Cu status (Pearson R = 0.73 to 0.87). During the growing phase, ADG (P = 0.09) and G:F (P = 0.002) were depressed in Cu-deficient animals compared with controls, whereas cattle performed equally well across all treatments in the finishing phase. The plasma DAO activity assay was precise and reliable based on an intraassay CV of 4.4% and interassay CV of 11.1%. Due to increased variability, freezing and thawing of plasma samples resulted in significant changes in DAO activity relative to fresh plasma DAO activity values. Thus, fresh plasma DAO activity, a relatively simple assay, may serve as an effective tool to diagnose Cu deficiency in the bovine.

  15. Sage Gene Expression Profiles Characterizing Cure

    DTIC Science & Technology

    2005-10-01

    early stage tumours (the cacoethesis of Celsus). Twentieth century progress in antisepsis , anaesthesia, and surgery changed this point of view. The first... antisepsis or anaesthesia. Nitrous oxide was described in 1842 and ether was first demonstrated in 1846. Schleiden (1838), a German, was among the first to...and antisepsis which allowed surgeons to attempt a radical cure of breast cancer. He describes a series of 616 cases, 70% of whom had skin infiltration

  16. Coating and curing apparatus and methods

    DOEpatents

    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.

  17. Improved Cure-in-Place Silicone Adhesives

    NASA Technical Reports Server (NTRS)

    Blevins, C. E.; Sweet, J.; Gonzalez, R.

    1982-01-01

    Two improved cure-in-place silicone-elastomer-based adhesives have low thermal expansion and low thermal conductivity. Adhesives are flexible at low temperature and withstand high temperatures without disintegrating. New ablative compounds were initially developed for in-flight repair of insulating tile on Space Shuttle orbiter. Could find use in other applications requiring high-performance adhesives, such as sealants for solar collectors.

  18. Photothermal Monitoring Of Curing Of Polymers

    NASA Technical Reports Server (NTRS)

    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.

  19. Characterization and Cure Monitoring of Structural Adhesives

    DTIC Science & Technology

    1989-02-01

    OX tiLE (OP? MTL TR 89-15 AD CHARACTERIZATION AND CURE MONITORING OF STRUCTURAL ADHESIVES CD WALTER X. ZUKAS, HOWARD H. WONG, DAVID A. DUNN, and...REPORT NUMB3ER 7. AUTHOR(s) 8. CONTRACT OR GRANT NUMBERs) Walter X. Zukas, Howard H. Wong, David A. Dunn, and Stanley E. Wentworth I. PERFORING...Technology, Gaithersburg, MD 20899 1 ATTN: B. Fanconi, Polymer Standards Division 1 D. Hunston, Polymer Standards Division 1 Dr. Stanley M. Barkin , Staff

  20. Coating and curing apparatus and methods

    DOEpatents

    Brophy, Brenor L; Maghsoodi, Sina; Neyman, Patrick J; Gonsalves, Peter R; Hirsch, Jeffrey G; Yang, Yu S

    2015-02-24

    Disclosed are 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 skin curing sol-gel coatings deposited onto the surface of glass substrates using a high temperature air-knife are disclosed.

  1. Curing efficiency of various resin-based materials polymerized through different ceramic thicknesses and curing time

    PubMed Central

    Lee, Jung-Won; Cha, Hyun-Suk

    2011-01-01

    PURPOSE The aim of this in vitro study was to examine the curing efficiency of various resin-based materials polymerized through ceramic restorations with 3 different thicknesses. Curing efficiency was evaluated by determining the surface microhardness (VHN) of the resin specimens. MATERIALS AND METHODS Four kinds of resin materials were used. Z350 (3M ESPE Filtek™ Z350: A2 Shade), Z250 (3M ESPE Filtek™ Z250: A2 Shade) and Variolink® II (VL: Ivoclar vivadent, base: transparent) either with or without a self-curing catalyst (VLC: Ivoclar vivadent, catalyst: low viscosity/transparent) were filled into the silicone mold (10 mm diameter, 1 mm thick). They were cured through ceramic discs (IPS e.max Press MO-0 ingot ivoclar vivadent, 10 mm diameter, 0.5, 1 and 2 mm thicknesses) by LED light-curing units for 20 and 40 seconds. Vicker's microhardness numbers (VHNs) were measured on the bottom surfaces by a microhardness tester. Data were analyzed using a 3- way analysis of variance (ANOVA) at a significance level of 0.05. RESULTS The thickness of ceramic disc increased, the VHNs of all four resin types were decreased (P<.05). The mean VHN values of the resins light cured for 40 seconds were significantly higher than that of LED for 20 seconds in all four resin materials (P<.05). VLC showed significantly higher VHN values than VL regardless of other conditions (P<.05). Z350 and Z250 showed higher values than VL or VLC (P<.01). CONCLUSION Thinner ceramic disc with increased curing time resulted higher VHN values of all resin materials. The use of a catalyst produced a greater hardness with all polymerization methods. Restorative resin materials (Z350, Z250) showed higher VHN values than resin cement materials (VL, VLC). PMID:22053242

  2. Organic Modification of a Layered Silicate by Co-Ion Exchange of an Alkyl Ammonium and a Mono-Protonated Diamine

    NASA Technical Reports Server (NTRS)

    Campbell, Sandi G. (Inventor)

    2004-01-01

    Co-Ion exchange of the interlayer cations of a layered silicate with a mono-protonated aromatic diamine and an alkyl ammonium ion into the silicate galleries. The presence of the alkyl ammonium ion provides low oligomer melt viscosity during processing. The presence of the diamine allows chemical reaction between the silicate surface modification and the monomers. This reaction strengthens the polymer silicate interface, and ensures irreversible separation of the individual silicate layers. Improved polymer thermal oxidative stability and mechanical properties are obtained.

  3. Synthesis of N1-tritylethane-1,1,2,2-d4-1,2-diamine: a novel mono-protected C-deuterated ethylenediamine synthon

    SciTech Connect

    Yang, Jun; Hong, Kunlun; Bonnesen, Peter V

    2012-01-01

    A convenient and high-yield synthesis for N1-tritylethane-1,1,2,2-d4-1,2-diamine, a novel mono-protected ethylenediamine-C-d4, is reported. N1-tritylethane-1,1,2,2-d4-1,2-diamine was prepared in three steps from ethylene oxide-d4 in a combined yield in the range 68-76%. Also reported is a synthesis of ethylenediamine-C-d4 in two steps from 1,2-dibromoethane-d4 in a combined yield in the range 61-65%.

  4. Immobilizing Molecular Metal Dithiolene-Diamine Complexes on 2D Metal-Organic Frameworks for Electrocatalytic H2 Production.

    PubMed

    Dong, Renhao; Zheng, Zhikun; Tranca, Diana C; Zhang, Jian; Chandrasekhar, Naisa; Liu, Shaohua; Zhuang, Xiaodong; Seifert, Gotthard; Feng, Xinliang

    2017-02-16

    Carbon electrocatalysts consisting of metal complexes such as MNx or MSx are promising alternatives to high-cost Pt catalysts for the hydrogen evolution reaction (HER). However, the exact HER active sites remain elusive. Here, molecular metal dithiolene-diamine (MS2 N2 , M=Co and Ni), metal bis(dithiolene) (MS4 ), and metal bis(diamine) (MN4 ) complexes were selectively incorporated into carbon-rich 2D metal-organic frameworks (2D MOFs) as model carbon electrocatalysts. The 2D MOF single layers, powders, and composites with graphene were thus prepared and showed definite active sites for H2 generation. The electrocatalytic HER activity of the 2D MOF-based catalysts with different metal complexes follow the order of MS2 N2 >MN4 >MS4 . Moreover, the protonation preferentially occurred on the metal atoms, and the concomitant heterolytic elimination of H2 was favored on the M-N units in the MS2 N2 active centers. The results provide an in-depth understanding of the catalytic active sites, thus making way for the future development of metal complexes in carbon-rich electrode materials for energy generation.

  5. EPDM-HDPE Blends with Different Cure Systems/Mechanical and Infra-Red Spectrometric Properties

    NASA Astrophysics Data System (ADS)

    Moldovan, Zenovia; Ionescu, Florica; Litescu, Simona; Vasilescu, Ioana; Lucian Radu, Gabriel

    The physico-mechanical properties and the Infra-red (IR) spectra (obtained by applying the Attenuated Total Reflectance (ATR) technique) of high density polyethylene (HDPE)/ethylene propylene diene terpolymer (EPDM) blends were investigated using a Zwick Tensile Testing machine and a Fourier Transform Infra-red (FTIR) spectrometer. Three kinds of cure systems were used: sulfur, tetramethylthiuram disulfide (TH) and 2-mercaptobenzothiazole (M); sulfur, tetramethylthiuram disulfide (TH) and zinc-diethyldithiocarbamate (ZDEC); sulfur, tetramethylthiuram disulfide (TH) and diphenylguanidine (D). The composition of HDPE and EPDM was fixed at 50/50 by weight and the ratio cure accelerators/sulfur was varied from 0.4 to 6.34 by weight. Results indicated that polymer alloys EPDM/HDPE containing as cure agents Sulfur, TH and M, in a ratio cure accelerators/sulfur = 6.34 and 1.85, respectively, showed improved physico-mechanical properties as compared to the other polymer blends. This behavior was confirmed by the recorded ATR-FTIR spectra of the studied samples.

  6. Assessing the prediction accuracy of cure in the Cox proportional hazards cure model: an application to breast cancer data.

    PubMed

    Asano, Junichi; Hirakawa, Akihiro; Hamada, Chikuma

    2014-01-01

    A cure rate model is a survival model incorporating the cure rate with the assumption that the population contains both uncured and cured individuals. It is a powerful statistical tool for prognostic studies, especially in cancer. The cure rate is important for making treatment decisions in clinical practice. The proportional hazards (PH) cure model can predict the cure rate for each patient. This contains a logistic regression component for the cure rate and a Cox regression component to estimate the hazard for uncured patients. A measure for quantifying the predictive accuracy of the cure rate estimated by the Cox PH cure model is required, as there has been a lack of previous research in this area. We used the Cox PH cure model for the breast cancer data; however, the area under the receiver operating characteristic curve (AUC) could not be estimated because many patients were censored. In this study, we used imputation-based AUCs to assess the predictive accuracy of the cure rate from the PH cure model. We examined the precision of these AUCs using simulation studies. The results demonstrated that the imputation-based AUCs were estimable and their biases were negligibly small in many cases, although ordinary AUC could not be estimated. Additionally, we introduced the bias-correction method of imputation-based AUCs and found that the bias-corrected estimate successfully compensated the overestimation in the simulation studies. We also illustrated the estimation of the imputation-based AUCs using breast cancer data.

  7. Thermal rheological analysis of cure process of epoxy prepreg

    NASA Astrophysics Data System (ADS)

    Sun, Liangfeng

    2002-01-01

    The cure process of epoxy prepreg used as composite pipe joints was studied by means of differential scanning calorimetry (DSC), Bohlin Rheometer and other techniques. Isothermal DSC measurements were conducted between 110 and 220°C, at 10°C intervals. The results show that the complete cure reaction could be achieved at 220°C. The isothermal cure process was simulated with the four-parameter autocatalytic model. Except in the late stage of cure reaction, the model agrees well with the experimental data, especially at high temperatures. To account for the effect of diffusion on the cure rate, a diffusion factor was introduced into the model. The modified model greatly improved the predicated data at the late stage of cure reaction. The dynamic cure process was different from the isothermal cure process in that it is composed of two cure reactions. For dynamic cure process, a three-parameter autocatalytic model was used. The parameters in the model were determined by two methods. One was based on Kissinger and Ozawa approach. The whole curing process was modeled with two reactions. Another method was based on Borchardt and Daniels kinetic approach with whole curing process was modeled with one reaction. The fitting results by first and second method agreed well with experimental value in the late and early cure stage, separately. Rheological properties of epoxy prepreg are closely related to the cure process. With the development of cure reaction, gelation occurs and epoxy prepreg becomes difficult to process. As temperature increases, the gel time decreases. Viscosity profiles were described by different models. Except the first and nth order viscosity models, new viscosity models were proposed. The proposed new viscosity models are better than the old models for both isothermal and dynamic cure processes. To graphically represent the phase changes of the cure process, the isothermal cure diagrams of time-temperature-transformation (TTT) and conversion

  8. Antibiotic Agents

    MedlinePlus

    ... producing ). Examples of this type are the alcohols, chlorine, peroxides, and aldehydes. The second group consists mostly ... viruses have some kind of antibacterial agent. Alcohols, chlorine and peroxides have been used for many decades ...

  9. Agent Orange

    MedlinePlus

    ... Z) Hepatitis HIV Mental Health Mental Health Home Suicide Prevention Substance Abuse Military Sexual Trauma PTSD Research ( ... eligible Veterans a free Agent Orange Registry health exam for possible long-term health problems related to ...

  10. Characterization of the relationship of the cure cycle chemistry to cure cycle processing properties

    NASA Technical Reports Server (NTRS)

    Kranbuehl, D. E.

    1986-01-01

    Dynamic Dielectric measurements made over a wide range of frequency provide a sensitive and convenient means for monitoring the cure process in thermosets and thermoplastics. The measurement of dielectric relaxation is one of only a few instrumental techniques available for studying molecular properties in both the liquid and solid states. Furthermore, it is probably the only convenient experimental technique for studying the polymerization process of going from a monomeric liquid of varying viscosity to a crosslinked, insoluble, high temperature solid. The objective of the research is to develop on-line dielectric instrumentation for quantitative nondestructive material evaluation and closed loop smart cure cycle control. The key is to relate the chemistry of the cure cycle process to the dielectric properties of the polymer system by correlating the time, temperature, and frequency dependent dielectric measurements with chemical characterization measurements. Measurement of the wide variation in magnitude of the complex permittivity with both frequency and state of cure, coupled with chemical characterization work, have been shown in the laboratory to have the potential to determine: resin quality, composition and age; cure cycle window boundaries; onset of flow and point of maximum flow; extent of and completion of reaction; evolution of volatiles; T sub g; and, crosslinking and molecular weight buildup.

  11. Microhardness and Young's modulus of a bonding resin cured with different curing units.

    PubMed

    Yamauti, Monica; Nikaido, Toru; Ikeda, Masaomi; Otsuki, Masayuki; Tagami, Junji

    2004-12-01

    This study evaluated the microhardness and Young's modulus of a photocurable bonding resin, Clearfil SE Bond (SE), cured with four curing units at different distances. The curing units used were: Candelux (Quartz-tungsten halogen), Lux-O-Max (Blue light emitting diode), Arc-light (Plasma-arc), and Rayblaze (Metal halide). Discs of bonding resin were prepared using vinyl molds and were photocured at the top surface with light tip at three different distances (contact, 2 and 4 mm). After 24 hours of storage in water at 37 degrees C, the specimens were sectioned into halves, embedded in epoxy resin, and polished. The microhardness and Young's modulus of this bonding resin were measured using a nanoindentation tester. Six specimens were prepared for each group. The data was statistically analyzed using two-way ANOVA test and Tukey multiple comparison test (p < 0.01). The microhardness of SE was affected by light source and distance, as was Young's modulus. Candelux and Rayblaze presented the highest hardness and Young's modulus results. Both properties presented high values when the curing unit tip was maintained in contact with the irradiated surface. Increasing the distance between the curing unit tip and the irradiated surface decreased the hardness and Young's modulus of SE.

  12. Two-year color changes of light-cured composites: influence of different light-curing units.

    PubMed

    Usumez, Aslihan; Ozturk, Nilgun; Ozturk, Bora

    2005-01-01

    This study determined color changes in a composite cured with various types of curing units after two years. A hybrid (Clearfil AP-X) composite was cured with a conventional halogen, a high intensity halogen, a plasma arc and a light emitting diode unit. The specimens were stored in light-proof boxes after the curing procedure to avoid further exposure to light and stored in 37 degrees C in 100% humidity. Colorimetric values of the specimens immediately after curing and after two years were measured using a colorimeter. The CIE 1976 L*a*b color system was used to determine color differences. Differences from baseline were calculated as deltaE*ab. Data were analyzed with two-way analysis of variance (p<0.05). The deltaE*ab values varied significantly, depending on the curing unit used. The specimens cured with a plasma arc curing unit induced significantly higher color changes than any other specimen and the color differences were also visually appreciable by the non-skilled operator (deltaE*ab >2.5). The specimens cured with a high intensity halogen curing unit produced the lowest color change; however, there were no statistically significant differences among the color changes of specimens cured with conventional halogen, high intensity halogen and the light emitting diode unit, and the color changes were not clinically relevant (deltaE*ab <2.5). The results of this study suggest that composite materials undergo measurable changes due to curing unit exposure. The specimens cured with a plasma arc light showed the highest color changes as compared to specimens cured with other curing units.

  13. Bond Strength of Repaired Acrylic Denture Teeth Using Visible Light Cure Composite Resin

    PubMed Central

    Muhsin, Saja Ali

    2017-01-01

    Background: Although bonding to denture teeth after surface treatment with chemical agents is desirable, there is little information on the use of Visible Light Cure composite resin (VLC) as bonding denture materials. Objectives: To determine the effect of various surface treatments on shear bond strength between Visible Light Cure composite resin and the acrylic denture teeth interface. Methods: Forty cylindrical sticks of acrylic resin with denture teeth mounted atop were prepared. Various treatments were implemented upon the acrylic resin teeth surfaces. The samples were divided into four groups (n = 10). Light-cured composite resin (LC) was applied over all treated and untreated surfaces of tested groups. The shear bond was tested using a universal tensile testing apparatus with the knife-edge of a 0.8mm shear tester. Data were statistically analyzed using one-way ANOVA performed at a confidence level of 95% and significant P-value of (P ≤ 0.05). Results: Analysis of variance (ANOVA) showed statistically significant difference (P < 0.05) between treated and untreated teeth surfaces. The treated surfaces exhibited various levels of bond strength depending on the type of treatment. Conclusion: Application of VLC bonding agent with prior treatment of methylmethacrylate (MMA) on the acrylic resin denture teeth resulted in maximum bond strength with composite resin.

  14. Cure shrinkage effects in epoxy and polycyanate matrix composites

    SciTech Connect

    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.

  15. Chelating compounds as potential flash rust inhibitors and melamine & aziridine cure of acrylic colloidal unimolecular polymers (CUPs)

    NASA Astrophysics Data System (ADS)

    Mistry, Jigar Kishorkumar

    Waterborne coatings on ferrous substrates usually show flash rusting which decreases the adhesion of the coating and the corrosion products can form a stain. Chelating compounds were investigated as potential flash rust inhibitors. Compounds being evaluated include amine alcohols, diamines and sulfur containing amines. A new corrosion inhibitor 2,5-bis(thioaceticacid)-1,3,4-thiadiazole (H2ADTZ) was synthesized and its performance characteristics were evaluated. It was noted that the observed structure of 1,3,4-thiadiazolidine-2,5-dithione (also known as 2,5-dimercapto-1,3,4-thiadiazole (DMTD or DMcT)) has been previously reported in three different tautomeric forms including -dithiol and -dithione. The relative stability of each form as well as the synthesis and characterization of the structures of mono- and dialkylated forms of 5-mercapto-1,3,4-thiadiazole-2(3H)-thione (MTT) were examined. The methods of X-ray crystallography, NMR spectroscopy and ab-initio electronic structure calculations were combined to understand the reactivity and structure of each compound. Polymers were synthesized with a 1:7 or 1:8 ratio of acrylic acid to acrylate monomers to produce an acid rich resin. The polymers were reduced and solvent stripped to produce Colloidal Unimolecular Polymers (CUPs). These particles are typically 3-9 nanometers in diameter depending upon the molecular weight. They were then formulated into a clear coating with either a melamine (bake) or an aziridine (ambient cure) and then cured. The melamine system was solvent free, a near zero VOC and the aziridine system was very low to near zero VOC. The coatings were evaluated for their MEK resistance, adhesion, hardness, gloss, flexibility, wet adhesion, abrasion and impact resistance properties.

  16. Curing and Post-curing Viscoelastic Monitoring of an Epoxy Resin

    NASA Astrophysics Data System (ADS)

    Ghodhbani, N.; Marechal, P.; Duflo, H.

    An experimental setup has been developed for the monitoring of ultrasonic parameters during polymerization in the context of the monitoring of composite plate production. An analytical approach is proposed based on the modeling of the wave velocity fitted by a Weibull distribution and was investigated to validate this approach by the Debye series modeling (DSM). The monitoring of the cured epoxy is also performed after curing in order to study the thermal transformation compared with DSC measurements. As a result, an approximated frequency-temperature (f, T) model is proposed for attenuation and velocity frequency and temperature dispersions.

  17. Sunscreening Agents

    PubMed Central

    Martis, Jacintha; Shobha, V; Sham Shinde, Rutuja; Bangera, Sudhakar; Krishnankutty, Binny; Bellary, Shantala; Varughese, Sunoj; Rao, Prabhakar; Naveen Kumar, B.R.

    2013-01-01

    The increasing incidence of skin cancers and photodamaging effects caused by ultraviolet radiation has increased the use of sunscreening agents, which have shown beneficial effects in reducing the symptoms and reoccurrence of these problems. Many sunscreen compounds are in use, but their safety and efficacy are still in question. Efficacy is measured through indices, such as sun protection factor, persistent pigment darkening protection factor, and COLIPA guidelines. The United States Food and Drug Administration and European Union have incorporated changes in their guidelines to help consumers select products based on their sun protection factor and protection against ultraviolet radiation, whereas the Indian regulatory agency has not yet issued any special guidance on sunscreening agents, as they are classified under cosmetics. In this article, the authors discuss the pharmacological actions of sunscreening agents as well as the available formulations, their benefits, possible health hazards, safety, challenges, and proper application technique. New technologies and scope for the development of sunscreening agents are also discussed as well as the role of the physician in patient education about the use of these agents. PMID:23320122

  18. Reductive Umpolung of Carbonyl Derivatives with Visible‐Light Photoredox Catalysis: Direct Access to Vicinal Diamines and Amino Alcohols via α‐Amino Radicals and Ketyl Radicals

    PubMed Central

    Fava, Eleonora; Millet, Anthony; Nakajima, Masaki; Loescher, Sebastian

    2016-01-01

    Abstract Visible‐light‐mediated photoredox‐catalyzed aldimine–aniline and aldehyde–aniline couplings have been realized. The reductive single electron transfer (SET) umpolung of various carbonyl derivatives enabled the generation of intermediary ketyl and α‐amino radical anions, which were utilized for the synthesis of unsymmetrically substituted 1,2‐diamines and amino alcohols. PMID:27136443

  19. A novel chiral aliphatic-aromatic diamine promoted direct, highly enantio- and diastereoselective Michael addition of cyclohexanone to nitroolefins under solvent-free conditions.

    PubMed

    Miao, Shifeng; Bai, Jinjin; Yang, Jin; Zhang, Yawen

    2010-10-01

    A series of new highly efficient chiral aliphatic-aromatic diamine catalysts have been designed and successfully applied to the asymmetric Michael addition of cyclohexanone with nitroolefins under solvent-free conditions without any acidic additives. The desired adducts were obtained in high yields with excellent enantio- and diastereoselectivities of syn products (up to >99% ee, >99:1 dr).

  20. Elements as Direct Feedstocks for Organic Synthesis: Fe/I2/O2 for Diamination of 2-Cyclohexenones with 2-Aminopyrimidine and 2-Aminopyridines.

    PubMed

    Nguyen, Thanh Binh; Corbin, Mathilde; Retailleau, Pascal; Ermolenko, Ludmila; Al-Mourabit, Ali

    2015-10-16

    Elements as feedstocks for organic synthesis, the trio of metallic iron, molecular iodine, and dioxygen, were found to be an excellent tool for oxidative regioselective diamination of conjugated enones with 2-aminopyrimidine (a guanidine surrogate) and 2-aminopyridines leading to unaromatized coupled products in moderate to good yields.

  1. Scope and mechanism of enantioselective Michael additions of 1,3-dicarbonyl compounds to nitroalkenes catalyzed by nickel(II)-diamine complexes.

    PubMed

    Evans, David A; Mito, Shizue; Seidel, Daniel

    2007-09-19

    Readily prepared Ni(II)-bis[(R,R)-N,N'-dibenzylcyclohexane-1,2-diamine]Br(2) was shown to catalyze the Michael addition of 1,3-dicarbonyl compounds to nitroalkenes at room temperature in good yields with high enantioselectivities. The two diamine ligands in this system each play a distinct role: one serves as a chiral ligand to provide stereoinduction in the addition step while the other functions as a base for substrate enolization. Ligand modification within the catalyst was also investigated to facilitate the reaction of aliphatic nitroalkenes, 1,3-diketones, and beta-ketoacids. Ni(II)-bis[(R,R)-N,N'-di-p-bromo-benzylcyclohexane-1,2-diamine]Br(2) was found to be an effective catalyst in these instances. Furthermore, monodiamine complex, Ni(II)-[(R,R)-N,N'-dibenzylcyclohexane-1,2-diamine]Br(2), catalyzed the addition reaction in the presence of water. The proposed model for stereochemical induction is shown to be consistent with X-ray structure analysis.

  2. Palladium-catalyzed stereoselective intramolecular oxidative amidation of alkenes in the synthesis of 1,3- and 1,4-amino alcohols and 1,3-diamines.

    PubMed

    Malkov, Andrei V; Lee, Darren S; Barłóg, Maciej; Elsegood, Mark R J; Kočovský, Pavel

    2014-04-22

    An efficient and practical Pd-catalyzed intramolecular oxidative allylic amidation provides facile access to derivatives of 1,3- and 1,4-amino alcohols and 1,3-diamines. The method operates under mild reaction conditions (RT) with molecular oxygen (1 atm) as the sole reoxidant of Pd. Excellent diastereoselectivities were attained with substrates bearing a secondary stereogenic center.

  3. Curing APL through PML/RARA degradation by As2O3.

    PubMed

    Lallemand-Breitenbach, Valerie; Zhu, Jun; Chen, Zhu; de Thé, Hugues

    2012-01-01

    Acute promyelocytic leukemia (APL) is a hematological malignancy driven by the PML/RARA oncogene. The prognosis for patients with APL was revolutionized by two treatments: retinoic acid (RA) and As(2)O(3) (arsenic trioxide). These were both shown a posteriori to target PML/RARA, explaining their exquisite specificity for APL. Arsenic, as a single agent, cures up to 70% of patients, whereas APL patients treated with the combination of RA and As(2)O(3) reach a stunning 90% cure rate. Recent physiopathological models highlight the key role of RA- and As(2)O(3)-triggered PML/RARA degradation, and the molecular mechanisms underlying As(2)O(3)-induced PML/RARA degradation have been recently clarified. As discussed below, arsenic binding, oxidation, sumoylation on PML nuclear bodies, and RNF4-mediated ubiquitination all contribute to the As(2)O(3)-triggered catabolism of PML/RARA.

  4. The development of low temperature curing adhesives

    NASA Technical Reports Server (NTRS)

    Green, H. E.; Sutherland, J. D.; Hom, J. M.; Sheppard, C. H.

    1975-01-01

    An approach for the development of a practical low temperature (293 K-311 K/68 F-100 F) curing adhesive system based on a family of amide/ester resins was studied and demonstrated. The work was conducted on resin optimization and adhesive compounding studies. An improved preparative method was demonstrated which involved the reaction of an amine-alcohol precursor, in a DMF solution with acid chloride. Experimental studies indicated that an adhesive formulation containing aluminum powder provided the best performance when used in conjunction with a commercial primer.

  5. Lower-curing-temperature PMR polyimides

    NASA Technical Reports Server (NTRS)

    Delvigs, P.

    1982-01-01

    Partial substitution of a p-aminostyrene end-cap for the monomethyl ester of 5-norbornene-2, 3-dicarboxylic acid lowered the final cure temperature of typical PMR resins from 600 F to 500 F. The weight loss characteristics of neat resins and graphite fiber composites prepared by using the mixed end-cap approach were determined at 600 F. The room temperature and short-time elevated temperature mechanical properties of the composites at 550 F and 600 F were determined. The mechanical property retention characteristics of the composites at 550 F and 600 F are discussed.

  6. The cure for employee malaise--motivation.

    PubMed

    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.

  7. Reaction cured glass and glass coatings

    NASA Technical Reports Server (NTRS)

    Goldstein, H. E.; Leiser, D. B.; Katvala, V. W. (Inventor)

    1978-01-01

    The invention relates to reaction cured glass and glass coatings prepared by reacting a compound selected from the group consisting of silicon tetraboride, silicon hexaboride, other boron silicides, boron and mixtures with a reactive glass frit composed of a porous high silica borosilicate glass and boron oxide. The glassy composites of the present invention are useful as coatings on low density fibrous porous silica insulations used as heat shields and for articles such as reaction vessels that are subjected to high temperatures with rapid heating and cooling and that require resistance to temperature and repeated thermal shock at temperatures up to about 1482C (2700PF).

  8. Asymmetric Hydrogenation of Quinoline Derivatives Catalyzed by Cationic Transition Metal Complexes of Chiral Diamine Ligands: Scope, Mechanism and Catalyst Recycling.

    PubMed

    Luo, Yi-Er; He, Yan-Mei; Fan, Qing-Hua

    2016-12-01

    This personal account is focused on the asymmetric hydrogenation of quinolines and their analogues recently developed by using phosphorus-free chiral cationic ruthenium(II)/η(6) -arene-N-monosulfonylated diamine complexes. In our initial study, the chiral Ru-diamine complexes were found to be highly effective catalysts for the asymmetric hydrogenation of difficult quinoline substrates in room temperature ionic liquids (RTILs) with unprecedentedly excellent enantioselectivity. Our further systematic study revealed that a wide range of quinoline derivatives could be efficiently hydrogenated in alcoholic solvents, or under solvent-free and concentrated conditions with good to excellent stereoselectivity. Complexes of iridium analogues could also efficiently catalyze the asymmetric hydrogenation of quinolines in undegassed solvent. Asymmetric tandem reduction of various 2-(aroylmethyl)quinolines was achieved in high yield with excellent enantioselectivity and good diastereoselectivity. More challenging substrates, alkyl- and aryl-substituted 1,5- and 1,8-naphthyridine derivatives were successfully hydrogenated with these chiral ruthenium catalysts to give 1,2,3,4-tetrahydronaphthyridines with good to excellent enantioselectivity. Unlike the asymmetric hydrogenation of ketones, quinoline is reduced via a stepwise H(+) /H(-) transfer process outside the coordination sphere rather than a concerted mechanism. The enantioselectivity originates from the CH/π attraction between the η(6) -arene ligand in the Ru-complex and the fused phenyl ring of dihydroquinoline via a 10-membered ring transition state with the participation of TfO(-) anion. In addition, the Ru-catalyzed asymmetric hydrogenation of quinolines could be carried out in some environmentally benign reaction media, such as undegassed water, RTILs and oligo(ethylene glycol)s (OEGs). In the latter two cases, unique chemoselectivity and/or reactivity were observed. Catalyst recycling could also be realized by using

  9. Critical parameters for electron beam curing of cationic epoxies and property comparison of electron beam cured cationic epoxies versus thermal cured resins and composites

    SciTech Connect

    Janke, C.J.; Norris, R.E.; Yarborough, K.; Havens, S.J.; Lopata, V.J.

    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.

  10. High performance heat curing copper-silver powders filled electrically conductive adhesives

    NASA Astrophysics Data System (ADS)

    Cui, Hui-Wang; Jiu, Jin-Ting; Sugahara, Tohru; Nagao, Shijo; Suganuma, Katsuaki; Uchida, Hiroshi

    2015-03-01

    In this study, high performance electrically conductive adhesives were fabricated from a vinyl ester resin, a thermal initiator, silver coated copper powders, and pure silver powders, without using any other coupling agent, dispersing agent, and reducing agent. The heat cured copper-silver powders filled electrically conductive adhesives presented low bulk resistivity (e.g., 4.53 × 10-5 Ω·cm) due to the silver powders that had given high electrical conductivity to the adhesives, and high shear strength (e.g., 16.22 MPa) provided by the crosslinked structures of vinyl ester resin. These high performance copper-silver powders filled electrically conductive adhesives have lower cost than those filled by pure silver powders, which can be well used in the electronic packaging and can enlarge the application prospects of electrically conductive adhesives. [Figure not available: see fulltext.

  11. Informed consent to HIV cure research.

    PubMed

    Bromwich, Danielle; Millum, Joseph R

    2017-02-01

    Trials with highly unfavourable risk-benefit ratios for participants, like HIV cure trials, raise questions about the quality of the consent of research participants. Why, it may be asked, would a person with HIV who is doing well on antiretroviral therapy be willing to jeopardise his health by enrolling in such a trial? We distinguish three concerns: first, how information is communicated to potential participants; second, participants' motivations for enrolling in potentially high risk research with no prospect of direct benefit; and third, participants' understanding of the details of the trials in which they enrol. We argue that the communication concern is relevant to the validity of informed consent and the quality of decision making, that the motivation concern does not identify a genuine problem with either the validity of consent or the quality of decision making and that the understanding concern may not be relevant to the validity of consent but is relevant to the quality of decision making. In doing so, we derive guidance points for researchers recruiting and enrolling participants into their HIV cure trials, as well as the research ethics committees reviewing proposed studies.

  12. CURE: Clean use of reactor energy

    SciTech Connect

    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.

  13. Out-of-Autoclave Cure Composites

    NASA Technical Reports Server (NTRS)

    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.

  14. Adhesive Properties of Cured Phenylethynyl Containing Imides

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J.; Chang, Alice C.

    1997-01-01

    Considerable attention has been directed towards acetylene terminated oligomers over the last 20 years' and recent work has focused on phenylethynyl terminated imide (PETI) oligomers. These reactive oligomers possess several features which make them attractive candidates for use as composite matrices and adhesives. The phenylethynyl group can be readily incorporated into many different functionalized oligomers. The reactive oligomers possess relatively low melt viscosities and thermally cure without the evolution of volatile by-products. Once cured, they typically display high glass transition temperatures (Tgs), excellent solvent resistance and high mechanical properties. new modified phenylethynyl-terminated imide (LaRC MPEI) oligomers were synthesized at various molecular weights utilizing a small amount of trifunctional amine. As long as the amount of triamine is relatively small, this approach produces a mixture of linear, star-shaped and branched polymer chains that has lower melt and solution viscosity than an equivalent molecular weight linear phenylethynyl terminated imide oligomers. The work reported herein involves the synthesis and characterization of a copolymer using this approach and the preparation of blends utilizing a phenylethynyl containing reactive plasticizer of lower molecular weight called LaRC LV-121. The chemistry and properties of this new MPEI as well as some blends of MPEI with LV-121, are presented and compared to the linear version, LARC-PETI-5.

  15. Structure-activity relationships of 4-position diamine quinoline methanols as intermittent preventative treatment (IPT) against Plasmodium falciparum.

    PubMed

    Milner, Erin; Gardner, Sean; Moon, Jay; Grauer, Kristina; Auschwitz, Jennifer; Bathurst, Ian; Caridha, Diana; Gerena, Lucia; Gettayacamin, Montip; Johnson, Jacob; Kozar, Michael; Lee, Patricia; Leed, Susan; Li, Qigui; McCalmont, William; Melendez, Victor; Roncal, Norma; Sciotti, Richard; Smith, Bryan; Sousa, Jason; Tungtaeng, Anchalee; Wipf, Peter; Dow, Geoffrey

    2011-09-22

    A library of diamine quinoline methanols were designed based on the mefloquine scaffold. The systematic variation of the 4-position amino alcohol side chain led to analogues that maintained potency while reducing accumulation in the central nervous system (CNS). Although the mechanism of action remains elusive, these data indicate that the 4-position side chain is critical for activity and that potency (as measured by IC(90)) does not correlate with accumulation in the CNS. A new lead compound, (S)-1-(2,8-bis(trifluoromethyl)quinolin-4-yl)-2-(2-(cyclopropylamino)ethylamino)ethanol (WR621308), was identified with single dose efficacy and substantially lower permeability across MDCK cell monolayers than mefloquine. This compound could be appropriate for intermittent preventative treatment (IPTx) indications or other malaria treatments currently approved for mefloquine.

  16. Bis(μ-N,N′-di-4-pyridylpyridine-2,6-diamine)bis[dimethacrylatocobalt(II)] dihydrate

    PubMed Central

    Wang, Liang-Gui; Peng, Ai-Hua

    2008-01-01

    The CoII ion in the title complex, [Co2(C4H5O2)4(C15H13N5)2]·2H2O, has a distorted square-planar coordination formed by the bridging bidentate N,N′-di-4-pyridylpyrid­ine-2,6-diamine (dapmp) ligands and two monodentate carboxyl­ate groups from methacrylates. Two dapmp ligands bridge two Co atoms, forming a dinuclear complex arranged around an inversion centre. N—H⋯O and O—H⋯O hydrogen bonds involving the solvent water mol­ecule result in the formation of a three-dimensional network. The aliphatic moiety of one of the methacrylate groups is disordered over two positions with fixed occupancies of 0.67 and 0.33. PMID:21581181

  17. Antidiabetic Agents.

    ERIC Educational Resources Information Center

    Plummer, Nancy; Michael, Nancy, Ed.

    This module on antidiabetic agents is intended for use in inservice or continuing education programs for persons who administer medications in long-term care facilities. Instructor information, including teaching suggestions, and a listing of recommended audiovisual materials and their sources appear first. The module goal and objectives are then…

  18. Properties of radiation cured vinyl-divinyl copolymers. [Gamma rays

    SciTech Connect

    Micko, M.M.; Paszner, L.

    1980-04-01

    Analysis of compression stress-strain curves of radiation-cured vinyl methacrylate copolymers shows that addition of small concentrations of vinyl comonomers significantly alter all mechanical strength properties in compression. Stress-strain behavior is found to be a function of the copolymer composition. Best strength results are limited to a narrow comonomer concentration region; between 5 to 10% of divinyl monomer (DVM) for the four systems studied. This concentration range broadens with increasing molecular bridge length of the crosslinking agent being narrowest for ethylene glycol dimethylacrylate and broadest for tetraethylene glycol dimethacrylate. Copolymer connection number (CN/sub co/), as introduced earlier, is found to be useful structural parameter for crosslinked copolymers in that it correlates quantitatively mechanical or thermomechanical properties with crosslink densities within copolymers. The Methyl methacrylate-TEGDMA comonomer system was found to be the most suitable and economically attractive. It represents a well balanced compromise of improved polymerization parameters and copolymer properties desirable in many polymeric products. 9 figures, 2 tables.

  19. Revisiting the Radical Initiation Mechanism of the Diamine-Promoted Transition-Metal-Free Cross-Coupling Reaction.

    PubMed

    Zhang, Li; Yang, Huan; Jiao, Lei

    2016-06-08

    Radical chain reactions leading to C-C bond formation are widely used in organic synthesis, and initiation of the radical chain process usually requires thermolabile radical initiators. Recent studies on transition-metal-free cross-coupling reactions between aryl halides and arenes have demonstrated an unprecedented initiation system for radical chain reactions, where the combination of simple organic additives and a base was used in place of conventional radical initiators. Among them, the combination of N,N'-dimethylethylenediamine (DMEDA) and t-BuOK is one of the most efficient and representative reaction systems, and the radical initiation mechanism of this system has attracted considerable research interest. In this study, through the combination of kinetic studies, deuterium labeling experiments, and DFT calculations, the radical initiation mechanism of the diamine-promoted cross-coupling reaction was carefully reinvestigated. In light of the present study, a mechanistic network of radical initiation in the DMEDA/t-BuOK system was revealed, which differs dramatically from the previously realized single radical initiation pathway. In this mechanism, the diamine acts as a hydrogen atom donor and plays a dual role as both "radical amplifier" and "radical regulator" to initiate the radical chain process as well as to control the concentration of reactive radical species. This represents a rare example of a structurally simple molecule playing such a subtle role in the radical chain reaction system. The present study sheds some light on the novel radical initiation mode in transition-metal-free cross-coupling reactions following a base-promoted homolytic aromatic substitution (BHAS) mechanism, and may also help to understand the mechanism of relevant reactions.

  20. In situ cure monitoring of advanced fiber reinforced composites

    NASA Astrophysics Data System (ADS)

    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.

  1. Development of Castor Oil Resistant Urethane Sonar Encapsulants.

    DTIC Science & Technology

    1983-03-01

    Wyandotte 26.46 or ( Quadrol ) Ferric Acetonyl Acetonate Harshaw Chemical 0.04 100.00 This basic curing agent formula was selected so that the resulting cured...be accomplished while retaining a reasonable level of diamine solubility. The initial attempts involved replacing a portion of the Quadrol with...curing agent viscosities were ultimately overcome by replacing the Quadrol and 1500 equivalent weight PTMG diol with castor oil and a very low

  2. Stress In A Fiber During Curing Of Surrounding Matrix Resin

    NASA Technical Reports Server (NTRS)

    Bowles, Kenneth J.; Madhukar, Madhu S.; Kosuri, Ranga P.

    1995-01-01

    Experiments run to determine variation in tensile stress in single fiber during curing of matrix resin surrounding fiber. Study part of effort to understand physical mechanisms affecting residual stresses in matrix/fiber composites, with view toward optimizing curing cycles (in particular, optimizing temperature-vs.-time schedules of final cooldowns to ambient temperature) to minimize residual stresses. Results signify primary mechanisms affecting residual stress in fibers are thermal expansion and contraction and cure shrinkage of matrix material.

  3. Cure Characteristics of Tricyanate Ester High Temperature Composite Resins (PREPRINT)

    DTIC Science & Technology

    2011-02-09

    measurements of cure kinetics were undertaken using both isothermal and non-isothermal DSC , and compared to measures of conversion obtained through IR...measurements of cure kinetics were undertaken using both isothermal and non-isothermal DSC , and compared to measures of conversion obtained through IR...the effect of impurities on cure kinetics, comparative kinetics derived from non-isothermal and isothermal differential scanning calorimetry ( DSC

  4. Process Formulations And Curing Conditions That Affect Saltstone Properties

    SciTech Connect

    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.

  5. Optical fibre grating refractometers for resin cure monitoring

    NASA Astrophysics Data System (ADS)

    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.

  6. Effect of Curing Profile on Kaolin-based Geopolymers

    NASA Astrophysics Data System (ADS)

    Heah, C. Y.; Kamarudin, H.; Bakri, A. M. Mustafa Al; Binhussain, M.; Luqman, M.; Nizar, I. Khairul; Ruzaidi, C. M.; Liew, Y. M.

    Depending on the processing conditions, geopolymers can exhibit a wide variety of properties and characteristics. Curing profile serves as a crucial parameter in synthesis of geopolymers. In this paper, the influence of curing temperature and curing time on the properties of kaolin-based geopolymer was studied. The samples were separated into several curing conditions; including curing at ambient temperature, 40 °C, 60 °C, 80 °C and 100 °C for 1 day, and up to 3 days. The compressive strength and SEM analysis of geopolymer products were evaluated. Results showed that curing condition has a significant effect on the mechanical properties of kaolin-based geopolymer. Generally, curing at ambient temperature was not feasible, while increase in temperature favored the strength development. In addition, prolonged curing time improved the geopolymerization process, and led to higher strength gain. However, curing at high temperature for a long period of time caused failure of the sample at a later age.

  7. Bending strength and depth of cure of light-cured composite resins irradiated using filters that simulate enamel.

    PubMed

    Arikawa, H; Kanie, T; Fujii, K; Shinohara, N

    2004-01-01

    This study evaluates the light-attenuating effects of enamel on the properties of light-cured restorative resins using simple experimental filters. Three filters were designed to replicate the light transmittance characteristics of 0.5, 1.0 and 1.5 mm thick human enamel. The bending strength, depth of cure, and levels of residual monomer for 12 shades of three commercial light-cured composite resins were examined. These resins were cured either using direct irradiation from a light source or irradiation through one of the filters. For all materials, the bending strength and depth of cure of specimens irradiated through a filter were lower and the levels of residual monomer were higher than those found in specimens irradiated directly. The results indicate that the light-attenuating effect of enamel reduces the polymerization efficiency, resulting in poorer mechanical properties of light-cured composite resins.

  8. Ambient Cured Alkali Activated Flyash Masonry Units

    NASA Astrophysics Data System (ADS)

    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.

  9. Stratospheric experiments on curing of composite materials

    NASA Astrophysics Data System (ADS)

    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.

  10. Curing of epoxy matrix composite in stratosphere

    NASA Astrophysics Data System (ADS)

    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.

  11. Role of additives in wood polymer composites. Relationship to analogous radiation grafting and curing processes

    NASA Astrophysics Data System (ADS)

    Ng, Loo-Teck; Garnett, John L.; Mohajerani, Shahroo

    1999-08-01

    Wood polymer composites (WPC) were prepared by impregnating an Australian softwood, Pinus radiata with methyl methacrylate which subsequently underwent in situ polymerisation utilising either γ radiation or the catalyst-accelerator method. Novel additives including thermal initiator, crosslinking agents, an inclusion compound and oxygen scavenger were incorporated to improve the polymer loading and properties of the resulting WPC. Polymer loadings of WPC obtained utilising the accelerator-catalyst method corresponded well with those obtained using γ radiation with 20 kGy radiation dose. The mechanistic significance of the current work in analogous radiation grafting and curing processes is discussed.

  12. Spectrophotometric and colorimetric evaluation of staining of the light cured composite after exposure with different intensities of light curing units

    PubMed Central

    Chandrasekhar, Veeramachaneni; Reddy, L Pramod; Prakash, T Jaya; Rao, G Anitha; Pradeep, M

    2011-01-01

    Aim/Objective: To understand the importance of intensity of light in polymerizing light cured composites and its relation to color stability. Materials and Methods: Forty specimens of composite disc with 3mm diameter and 1.5 mm thick were divided into two groups of 20 samples each. Group1: Twenty samples were cured with a light curing unit of380mw/cm2. Group2: Twenty samples cured with a light curing unit of 680mw/cm2. These polymerized samples were immersed in methylene blue dye for 24hoursand later washed and immersed in absolute alcohol for 24 hours. The amount of color released into absolute alcohol was assessed by spectrophotometric and colorimetric analysis. Results: Results were analyzed for spectrophotometric and colorimetric values by using the Mann-Whitney test. The group cured with low intensity light stained more compared to the group cured with a normal intensity of light. Conclusions: Intensity of light plays a crucial role in staining of the polymerized light cured composite. The intensity of the curing unit has to be maintained in acceptable limits to achieve good clinical results. PMID:22144810

  13. Comparative study of the sealing ability of light-cured versus chemically cured materials placed into furcation perforations.

    PubMed

    Alhadainy, H A; Himel, V T

    1993-09-01

    Two light-cured materials, Vitrebond and Prisma VLC Dycal, were compared with two chemically cured materials, Ketac Fil and Dycal, for ability to seal furcation perforations. Access openings and furcation perforations were prepared in 60 teeth and randomly divided into four equal groups. Furcation perforations were repaired with each of the tested materials, and the access openings were filled with composite resin. After teeth were immersed in 2% erythrocin B dye solution for 10 days, they were sectioned longitudinally and dye penetration was measured. The light-cured materials allowed statistically significant less dye leakage than did the chemically cured materials.

  14. Evaluation of the curing depth of two translucent composite materials using a halogen and two LED curing units.

    PubMed

    Polydorou, Olga; Manolakis, Alexandros; Hellwig, Elmar; Hahn, Petra

    2008-03-01

    This in vitro study evaluated the influence of one halogen and two light-emitting diode (LED) curing units on the curing depth of a conventional hybrid and two translucent resin composites by measuring the Knoop microhardness. In the first part of the study, a conventional hybrid resin composite and three curing units (one halogen: 40 s polymerization time, two LEDs: 10 and 20 s) were used. Ten cylindrical resin composite samples were prepared for each curing unit and each polymerization time tested. After polymerization, the soft part of the samples was removed. The samples were embedded in a polyacrylic resin and separated in the middle towards the direction, top-bottom. On the section plane, Knoop microhardness measurements were performed every 1 mm, starting at 0.5 mm under the surface. In the second part of the study, two translucent resin composites and a conventional hybrid composite resin were cured with the three curing units, and the microhardness was measured as mentioned above. The difference between the curing units tested was found statistically significant (p = 0.0009), as well as the difference between the materials concerning curing depth (p = 0.0001). Both translucent materials achieved microhardness values equal to the 80% of the surface values, in depths 3.5-5.5 mm, depending on the curing units used.

  15. Colour Stability of Heat and Cold Cure Acrylic Resins

    PubMed Central

    Ganesh, P R; Reddy, Madan Mohan; Ebenezar, A.V. Rajesh; Sivakumar, G

    2015-01-01

    Introduction: To evaluate the colour stability of heat and cold cure acrylic resins under simulated oral conditions with different colorants. Materials and Methods: Three different brands of heat cure acrylic resin and two rapid cure auto polymerizing acrylic resin of commercial products such as Trevelon Heat Cure (THC), DPI Heat cure (DHC), Pyrax Heat Cure (PHC), DPI Cold cure (DCC) and Acralyn-R-Cold cure (ACC) have been evaluated for discoloration and colour variation on subjecting it to three different, commonly employed food colorants such as Erythrosine, Tartarizine and Sunset yellow. In order to simulate the oral condition the food colorants were diluted with artificial saliva to the samples taken up for the study. These were further kept in an incubator at 37°C ± 1°C. The UV-visible spectrophotometer has been utilized to evaluate the study on the basis of CIE L* a* b* system. The prepared samples for standard evaluation have been grouped as control group, which has been tested with a white as standard, which is applicable for testing the colour variants. Results: The least colour changes was found to be with Sunset Yellow showing AE* value of 3.55 with heat cure acrylic resin branded as PHC material and the highest colour absorption with Tartarizine showing AE* value of 12.43 in rapid cure autopolymerzing acrylic resin material branded as ACC material. Conclusion: ACC which is a self cure acrylic resin shows a higher colour variation to the tartarizine food coloration. There were not much of discoloration values shown on the denture base resins as the food colorants are of organic azodyes. PMID:25738078

  16. Aminophenoxycyclotriphosphazene cured epoxy resins and the composites, laminates, adhesives and structures thereof

    NASA Technical Reports Server (NTRS)

    Kumar, Devendra (Inventor); Fohlen, George M. (Inventor); Parker, John A. (Inventor)

    1977-01-01

    Aminophenoxy cyclotriphosphazenes such as hexakis (4-aminophenoxy) cyclotriphosphazene and tris (4-aminophenoxy)-tris phenoxy cyclotriphosphazene are used as curing agents for epoxy resins. These 1,2-epoxy resins are selected from di- or polyepoxide containing organic moieties of the formula (CH2-CHO-CH2) m-W-R-W- (CH2CH-CH2O)m where R is diphenyl dimethylmethane, diphenylmethane; W is a nitrogen or oxygen atom; and m is 1 when W is oxygen and 2 when W is nitrogen. The resins are cured thermally in stages at between about 110 to 135 C for between about 1 and 10 min, then at between about 175 to 185 C for between 0.5 to 10 hr and post cured at between about 215 and 235 C for between 0.1 and 2 hr. These resins are useful for making fire resistant elevated temperature stable composites, laminates, molded parts, and adhesives and structures, usually for aircraft secondary structures and for spacecraft construction.

  17. A method for observing gas evolution during plastic laminate cure

    NASA Technical Reports Server (NTRS)

    Nicholls, A. H.

    1969-01-01

    Polyimide, phenolic, and other resins which develop volatiles during laminating or molding cure are studied using optimum cure cycles. The specimen is placed on a platen and sealed in a plastic bag, then heated and observed for gas evolution using a binocular microscope. A cover plate is added to sumulate an autoclave.

  18. Improved method facilitates debulking and curing of phenolic impregnated asbestos

    NASA Technical Reports Server (NTRS)

    Gaines, P.

    1966-01-01

    Workpieces covered with phenolic impregnated asbestos tape and then wrapped with a specified thickness of nylon yarn under pressure, are debulked and cured in a standard oven. This method of debulking and curing is used in the fabrication of ablative chambers for the Gemini and Apollo attitude control engines.

  19. Cure cycle evaluation for multilayer printed wiring boards

    SciTech Connect

    Lula, J.W.

    1980-06-01

    The cure cycle for multilayer printed wiring boards (PWBs) made from general-puspore, fire-retardant epoxy/glass (GF) material has been evaluated for the optimum delamination resistance at soldering temperatures. The results that, for the epoxy resin system used to manufacture multilayer PWBs at Bendix Kansas City, a wide range of cure cycle variations has a minimal effect on delamination resistance.

  20. Teaching as Cure and Care: A Therapeutic Metaphor.

    ERIC Educational Resources Information Center

    Elias, John L.

    1990-01-01

    Uses the curing and caring aspects of medicine as an analogy for what education can be. Observes that the divinity expressed through medicine's ability to cure and care for people also can be expressed through teaching when it attempts to eliminate ignorance, prejudice, and misinformation. (DB)

  1. Computerized Ultrasound Risk Evaluation (CURE): First Clinical Results

    NASA Astrophysics Data System (ADS)

    Duric, N.; Littrup, P.; Rama, O.; Holsapple, E.

    The Karmanos Cancer Institute has developed an ultrasound (US) tomography system, known as Computerized Ultrasound Risk Evaluation (CURE), for detecting and evaluating breast cancer, with the eventual goal of providing improved differentiation of benign masses from cancer. We report on our first clinical findings with CURE.

  2. Mathematical Model of Raw Hide Curing with Brine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The most common method of preserving raw hides is brine curing with sodium chloride. However, this process has three important disadvantages: first, the length of time that it takes, which is a minimum of 18 hours; second, the insufficient degree of curing reached in some hides due to an overload a...

  3. From scientific discovery to cures: bright stars within a galaxy.

    PubMed

    Williams, R Sanders; Lotia, Samad; Holloway, Alisha K; Pico, Alexander R

    2015-09-24

    We propose that data mining and network analysis utilizing public databases can identify and quantify relationships between scientific discoveries and major advances in medicine (cures). Further development of such approaches could help to increase public understanding and governmental support for life science research and could enhance decision making in the quest for cures.

  4. Mental Retardation: The Search for Cures. Research Monograph Number 7.

    ERIC Educational Resources Information Center

    Menolascino, Frank J.; Neman, Ronald

    The booklet describes the Association for Retarded Citizens' (ARC's) goal of coordinating efforts to seek a cure for mental retardation. Cures are defined as any intervention that would significantly increase intellectual functioning and adaptive behavior beyond the upper level of retardation. It is explained that because of the variety of causes…

  5. The coating curing properties study using terahertz time domain spectroscopy

    NASA Astrophysics Data System (ADS)

    Ren, Jiaojiao; Zhao, Duo; Li, Lijuan

    2015-10-01

    Coating curing curve is one of the most important methods to reflect the coating curing properties. It is of great significance for the coating curing properties. In this paper, by using the reflective Terahertz (THz) time-domain spectroscope technique, the curing properties of coating with different thicknesses are studied. Three different parameters used for studying the properties of coating curing curve are proposed in this paper. They are respectively the differential time of flight, power spectrum and amplitude for reflective THz time-domain waveform. In this paper, two kinds of coating (with different thicknesses) curing properties curves are established and the relative errors from three parameter analysis methods are compared respectively. This study shows that the study on coating curing properties curves by using the power spectrum of reflective THz time-domain waveform is superior to the amplitude parameter method. But for the thick coating, the differential time of flight for the reflective THz time-domain waveform can also better reflect the coating curing properties.

  6. KGB agents

    NASA Astrophysics Data System (ADS)

    Gaina, Alex

    A short story is reported in which the activity of Communist Party of the USSR and secret KGB agents, which were payed by the State, in view of controlling of the conscience of population. The story reffers to the Physics Department of the Moscow University, Planing Institute of the Gosplan of Moldavian S.S.R. and Chishinau Technical University (actually: Technical University of Moldova), where the author has worked during Soviet times. Almost every 6-th citizen in the USSR was engaged in this activity, while actually the former communists rule in the Republic of Moldova.

  7. Shear Bond Strength of Acidic Primer, Light-Cure Glass Ionomer, Light-Cure and Self Cure Composite Adhesive Systems - An In Vitro Study

    PubMed Central

    D, Krishnakanth Reddy; V, Kishore M S; Safeena, Safeena

    2013-01-01

    Background: The purpose of this study was to determine shear bond strength and the effect on the bracket/ adhesive failure mode when an acidic primer and other etchants were used to condition the enamel surface before bonding. Materials & Methods: Group I: Brackets bonded with Ultimate cure-on-light Light-cure composite adhesive system. Group II: Brackets bonded with Ortho-one no-mix. Self-cure composite adhesive system. Group III: Brackets bonded with Light-cure glass ionomer adhesive system. Group IV: Brackets bonded with Transbond plus self etching primer. Results: The results of this study indicated that the shear bond strength when using Transbond plus self etching primer showed the highest bond strength Group- IV(8.69 2.54 MPa) followed by Ultimate cure-on-light Group-I (8.62 1.84 MPa), Ortho-one no-mix (Bisco Inc. USA)Group-II (8.07 1.72 MPa), and least bond strength was seen in G.C. Fuji Ortho L.C. Group-III (6.01 1.6) MPa Conclusion: Use of self etching primer saves chairside time and satisfactory high bond strength was obtained. Care should be taken during debonding of ceramic brackets How to cite this article: Reddy K D, Kishore M S V, Safeena S. Shear Bond Strength of Acidic Primer, Light-Cure Glass Ionomer, Light-Cure and Self Cure Composite Adhesive Systems - An In Vitro Study. J Int Oral Health 2013; 5(3):73-78. PMID:24155606

  8. Rat subchronic inhalation study of smoke from cigarettes containing flue-cured tobacco cured either by direct-fired or heat-exchanger curing processes.

    PubMed

    Kinsler, Steven; Pence, Deborah H; Shreve, W Keith; Mosberg, Arnold T; Ayres, Paul H; Sagartz, John W

    2003-07-01

    A subchronic, nose-only inhalation study compared the effects of mainstream smoke from a cigarette containing 100% flue-cured tobacco cured by a direct-fired process to that of a cigarette containing 100% flue-cured tobacco cured by a heat exchanger process. The tobaccos and mainstream smoke from tobaccos cured by the heat exchanger process have been shown to have significantly lower levels of tobacco-specific nitrosamines than tobaccos cured by a direct-fired process. Male and female rats were exposed for 1 h/day, 5 days/wk, for 13 wk to mainstream smoke at 0, 0.06, 0.20, or 0.80 mg wet total particulate matter per liter of air. Clinical signs, body and organ weights, clinical chemistry, hematology, carboxyhemoglobin, serum nicotine, plethysmography, gross pathology, and histopathology were determined. When histologic changes resulting from exposure to smoke from the two types of cigarettes were compared, the only significant difference was increased epithelial hyperplasia of the anterior nasal cavity in males in the high-exposure group for the heat-exchanger cigarette. At the end of the exposure period, subsets of rats from each group were maintained without smoke exposures for an additional 13 wk (recovery period). At the end of the recovery period, there were no statistically significant differences in histopathological findings observed between the heat-exchanger-cured tobacco cigarette when compared to the direct-fired cured tobacco cigarette. The complete toxicological assessment in this study of heat exchanger and direct-fired tobaccos suggests no overall biologically significant differences between the two cigarettes.

  9. Use of light-curing units in orthodontics.

    PubMed

    Goyal, Amit; Hurkadle, Jyothikiran; Magegowda, Shivalinga; Bhatia, Pankaj

    2013-08-01

    Because of their wide field of applications, light-curing units are now indispensable for orthodontists and general dentists; thus, it is important to be familiar with the various types of light-curing units, their history, specifications, advantages, and disadvantages. For this review, a search of the PubMed database (from 1966 to March 2010) was conducted using the search term "curing lights orthodontics". Eligibility of the selected studies was determined by reading the abstracts of articles identified by the search. All the articles that met the inclusion criteria were selected, and the articles collected. The reference lists of the retrieved articles were also hand searched for any applicable studies that might have been missed in the database searches. When selecting curing lights for an office, many variables need to be considered. Armed with knowledge about each curing-light category, orthodontists can evaluate their unique practice style and select the appropriate light/lights.

  10. Curing system for high voltage cross linked cables

    DOEpatents

    Bahder, George; Katz, Carlos; Bopp, Louis A.

    1978-01-01

    This invention makes extruded, vulcanized, high voltage cables insulated with thermosetting compounds at much higher rates of production and with superior insulation of reduced thickness and with reduced cavities or voids in the insulation. As the cable comes from an extruder, it passes into a curing chamber with a heat booster that quickly raises the insulation to a temperature at which it is cured much more quickly than with steam heating of the prior art. A high temperature liquid in contact with the insulation maintains the high temperature; and because of the greater curing heat, the cable can travel through the curing chamber at a faster rate and into a cooling tube where it contacts with a cooling liquid under high pressure. The insulation compound is treated to reduce the size of cavities; and the high pressure maintained by the curing and cooling mediums prevent expansion of cavities before the insulation is set.

  11. 7 CFR 30.38 - Class 3; air-cured types and groups.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... produced principally in the Green River section of Kentucky. (g) Type 37. That type of air-cured or sun-cured tobacco commonly known as Virginia Sun-cured, Virginia Sun and Air-cured, or Dark Air-cured...

  12. 7 CFR 30.38 - Class 3; air-cured types and groups.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... produced principally in the Green River section of Kentucky. (g) Type 37. That type of air-cured or sun-cured tobacco commonly known as Virginia Sun-cured, Virginia Sun and Air-cured, or Dark Air-cured...

  13. 7 CFR 30.38 - Class 3; air-cured types and groups.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... produced principally in the Green River section of Kentucky. (g) Type 37. That type of air-cured or sun-cured tobacco commonly known as Virginia Sun-cured, Virginia Sun and Air-cured, or Dark Air-cured...

  14. 7 CFR 30.38 - Class 3; air-cured types and groups.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... produced principally in the Green River section of Kentucky. (g) Type 37. That type of air-cured or sun-cured tobacco commonly known as Virginia Sun-cured, Virginia Sun and Air-cured, or Dark Air-cured...

  15. Cure models for the analysis of time-to-event data in cancer studies.

    PubMed

    Jia, Xiaoyu; Sima, Camelia S; Brennan, Murray F; Panageas, Katherine S

    2013-11-01

    In settings when it is biologically plausible that some patients are cured after definitive treatment, cure models present an alternative to conventional survival analysis. Cure models can inform on the group of patients cured, by estimating the probability of cure, and identifying factors that influence it; while simultaneously focusing on time to recurrence and associated factors for the remaining patients.

  16. Stress evolution in a conductive adhesive during curing and cooling

    NASA Astrophysics Data System (ADS)

    Mei, Yuhai

    2000-10-01

    There is increasing interest in using conductive adhesives, which are composites of polymers and conductive fillers, as replacements for solder in different types of microelectronic assemblies. However, conductive adhesives still suffer from several deficiencies, such as unstable electrical conductivity and inadequate adhesion. The reliability of the conductive adhesive joints is always one of the major considerations during their design and operation, and the curing and thermal stresses generated in polymers and composites during curing, cooling and thermal cycling play a very important role in determining reliability. Because of the mismatch in the mechanical properties between the conductive adhesive and the substrate, appreciable curing and thermal stress is generated during manufacturing, which may be detrimental to the reliability of conductive adhesive joints. In this dissertation, an interactive linear viscoelastic model which considers interaction between the initial gel network and the other networks that form during curing is proposed to simulate stress and volume shrinkage during the thermoset curing process, and an effective method for measuring volume shrinkage during the thermoset cure is developed. A systematic experimental study of the material properties of the conductive adhesive and its epoxy matrix during the curing and cooling processes has been conducted. Based on these experimental data, stresses generated during several spatially homogeneous curing and cooling processes of the conductive adhesive and its epoxy matrix are also calculated. It is found that the conductive adhesive possesses mechanical properties which are substantially different from those of the constituents, and that the conductive adhesive has a relaxation process which is similar to its matrix and generates appreciable curing and thermal stresses during curing and cooling. Finally, a processing procedure designed to provide desired residual stresses is discussed.

  17. Numerical natural rubber curing simulation, obtaining a controlled gradient of the state of cure in a thick-section part

    NASA Astrophysics Data System (ADS)

    El Labban, A.; Mousseau, P.; Bailleul, J. L.; Deterre, R.

    2007-04-01

    Although numerical simulation has proved to be a useful tool to predict the rubber vulcanization process, few applications in the process control have been reported. Because the end-use rubber properties depend on the state of cure distribution in the parts thickness, the prediction of the optimal distribution remains a challenge for the rubber industry. The analysis of the vulcanization process requires the determination of the thermal behavior of the material and the cure kinetics. A nonisothermal vulcanization model with nonisothermal induction time is used in this numerical study. Numerical results are obtained for natural rubber (NR) thick-section part curing. A controlled gradient of the state of cure in the part thickness is obtained by a curing process that consists not only in mold heating phase, but also a forced convection mold cooling phase in order to stop the vulcanization process and to control the vulcanization distribution. The mold design that allows this control is described. In the heating phase, the state of cure is mainly controlled by the chemical kinetics (the induction time), but in the cooling phase, it is the heat diffusion that controls the state of cure distribution. A comparison among different cooling conditions is shown and a good state of cure gradient control is obtained.

  18. Effect of three types of light-curing units on 5-year colour changes of light-cured composite.

    PubMed

    Tak, Onjen; Altintas, Subutay Han; Ozturk, Nilgun; Usumez, Aslihan

    2009-03-01

    The purpose of this study was to determine colour changes in a composite cured with tungsten-halogen, light-emitting diode (LED) or a plasma arc after 5 years. Five specimens 10 mm in diameter and 2 mm in height were prepared using Hybrid (Clearfil AP-X) composite for each test group. The corresponding specimens were cured with a tungsten-halogen curing light, a LED unit or with a plasma arc. Specimens were stored in light-proof boxes for 5 years after the curing procedure to avoid further exposure to light and stored in 37 degrees C in 100% humidity. Colorimetric values of the specimens immediately after curing and after 5 years were measured using colorimeter. The DeltaE*( ab ) values varied significantly depending on the curing unit used (p < 0.001). Curing time did not affect the colour changes of the specimens (p = 0.4). The results of this study suggest that composite materials undergo measurable changes due to the curing unit exposure.

  19. Synthesis, spectral, crystallography and thermal investigations of novel Schiff base complexes of manganese (III) derived from heterocyclic beta-diketone with aromatic and aliphatic diamine.

    PubMed

    Surati, Kiran R; Thaker, B T

    2010-01-01

    The Schiff base tetradentate ligands N,N-bis-(3,5-dimethyl-1-p-tolyl-1H-pyrazol-4-ylmethylene)-ethane-1,2-diamine (H(2)L(1)), N,N-bis-(3,5-dimethyl-1-p-sulfonyl-1H-pyrazol-4-ylmethylene)-ethane-1,2-diamine (H(2)L(2)), N,N-bis-(3,5-dimethyl-1-p-tolyl-1H-pyrazol-4-ylmethylene)-benzene-1,2-diamine (H(2)L(3)) and N,N-bis-(3,5-dimethyl-1-p-sulfonyl-1H-pyrazol-4-ylmethylene)-benzene-1,2-diamine (H(2)L(4)) were prepared from the reaction between 5-oxo-3-methyl-1-p-tolyl-1H-pyrazole-4-carbaldehyde or 4-(4-formyl-5-oxo-3-methyl-pyrazol-1-yl)-benzenesulfonic acid and o-phenylenediamine or ethylenediamine. And these are characterized by elemental analysis, FT-IR, (1)H NMR and GC-MS. The corresponding Schiff base complexes of Mn(III) were prepared by condensation of [Mn(3)(mu(3)-O)(OAc)(6)(H(2)O)(3)].3H(2)O with ligands H(2)L(1), H(2)L(2), H(2)L(3) and H(2)L(4). All these complexes have been characterized by elemental analysis, magnetic susceptibility, X-ray crystallography, conductometry measurement, FT-IR, electronic spectra and mass (FAB) spectrometry. Thermal behaviour of the complexes has been studied by TGA, DTA and DSC. Electronic spectra and magnetic susceptibility measurements indicate octahedral stereochemistry of manganese (III) complexes, while non-electrolytic behaviour complexes indicate the absence of counter ion.

  20. Synthesis, spectral, crystallography and thermal investigations of novel Schiff base complexes of manganese (III) derived from heterocyclic β-diketone with aromatic and aliphatic diamine

    NASA Astrophysics Data System (ADS)

    Surati, Kiran R.; Thaker, B. T.

    2010-01-01

    The Schiff base tetradentate ligands N,N-bis-(3,5-dimethyl-1-p-tolyl-1H-pyrazol-4-ylmethylene)-ethane-1,2-diamine (H 2L 1), N,N-bis-(3,5-dimethyl-1-p-sulfonyl-1H-pyrazol-4-ylmethylene)-ethane-1,2-diamine (H 2L 2), N,N-bis-(3,5-dimethyl-1-p-tolyl-1H-pyrazol-4-ylmethylene)-benzene-1,2-diamine (H 2L 3) and N,N-bis-(3,5-dimethyl-1-p-sulfonyl-1H-pyrazol-4-ylmethylene)-benzene-1,2-diamine (H 2L 4) were prepared from the reaction between 5-oxo-3-methyl-1-p-tolyl-1H-pyrazole-4-carbaldehyde or 4-(4-formyl-5-oxo-3-methyl-pyrazol-1-yl)-benzenesulfonic acid and o-phenylenediamine or ethylenediamine. And these are characterized by elemental analysis, FT-IR, 1H NMR and GC-MS. The corresponding Schiff base complexes of Mn(III) were prepared by condensation of [Mn 3(μ 3-O)(OAc) 6(H 2O) 3]·3H 2O with ligands H 2L 1, H 2L 2, H 2L 3 and H 2L 4. All these complexes have been characterized by elemental analysis, magnetic susceptibility, X-ray crystallography, conductometry measurement, FT-IR, electronic spectra and mass (FAB) spectrometry. Thermal behaviour of the complexes has been studied by TGA, DTA and DSC. Electronic spectra and magnetic susceptibility measurements indicate octahedral stereochemistry of manganese (III) complexes, while non-electrolytic behaviour complexes indicate the absence of counter ion.

  1. Oligomeric complexes of some heteroaromatic ligands and aromatic diamines with rhodium and molybdenum tetracarboxylates: 13C and 15N CPMAS NMR and density functional theory studies.

    PubMed

    Leniak, Arkadiusz; Kamieński, Bohdan; Jaźwiński, Jarosław

    2015-05-01

    Seven new oligomeric complexes of 4,4'-bipyridine; 3,3'-bipyridine; benzene-1,4-diamine; benzene-1,3-diamine; benzene-1,2-diamine; and benzidine with rhodium tetraacetate, as well as 4,4'-bipyridine with molybdenum tetraacetate, have been obtained and investigated by elemental analysis and solid-state nuclear magnetic resonance spectroscopy, (13)C and (15)N CPMAS NMR. The known complexes of pyrazine with rhodium tetrabenzoate, benzoquinone with rhodium tetrapivalate, 4,4'-bipyridine with molybdenum tetrakistrifluoroacetate and the 1 : 1 complex of 2,2'-bipyridine with rhodium tetraacetate exhibiting axial-equatorial ligation mode have been obtained as well for comparison purposes. Elemental analysis revealed 1 : 1 complex stoichiometry of all complexes. The (15)N CPMAS NMR spectra of all new complexes consist of one narrow signal, indicating regular uniform structures. Benzidine forms a heterogeneous material, probably containing linear oligomers and products of further reactions. The complexes were characterized by the parameter complexation shift Δδ (Δδ = δcomplex  - δligand). This parameter ranged from around -40 to -90 ppm in the case of heteroaromatic ligands, from around -12 to -22 ppm for diamines and from -16 to -31 ppm for the complexes of molybdenum tetracarboxylates with 4,4'-bipyridine. The experimental results have been supported by a density functional theory computation of (15)N NMR chemical shifts and complexation shifts at the non-relativistic Becke, three-parameter, Perdew-Wang 91/[6-311++G(2d,p), Stuttgart] and GGA-PBE/QZ4P levels of theory and at the relativistic scalar and spin-orbit zeroth order regular approximation/GGA-PBE/QZ4P level of theory. Nucleus-independent chemical shifts have been calculated for the selected compounds.

  2. New tetradentate Schiff bases of 2-amino-3,5-dibromobenzaldehyde with aliphatic diamines and their metal complexes: synthesis, characterization and thermal stability.

    PubMed

    Mohammadi, Khosro; Azad, Seyyedeh Sedigheh; Amoozegar, Ameneh

    2015-07-05

    The tetradentate Schiff base ligands (L(1)-L(4)), were synthesized by reaction between 2-amino-3,5-dibromobenzaldehyde and aliphatic diamines. Then, nickel and oxovanadium(IV) complexes of these ligands were synthesized and characterized by (1)H NMR, Mass, IR, UV-Vis spectroscopy and thermogravimetry. The kinetic parameters of oxovanadium(IV) complexes were calculated from thermal studies. According to the results of thermogravimetric data, the thermal stability of oxovanadium(IV) complexes is as follow: [Formula: see text].

  3. Arylmethylamino steroids as antiparasitic agents

    PubMed Central

    Krieg, Reimar; Jortzik, Esther; Goetz, Alice-Anne; Blandin, Stéphanie; Wittlin, Sergio; Elhabiri, Mourad; Rahbari, Mahsa; Nuryyeva, Selbi; Voigt, Kerstin; Dahse, Hans-Martin; Brakhage, Axel; Beckmann, Svenja; Quack, Thomas; Grevelding, Christoph G.; Pinkerton, Anthony B.; Schönecker, Bruno; Burrows, Jeremy; Davioud-Charvet, Elisabeth; Rahlfs, Stefan; Becker, Katja

    2017-01-01

    In search of antiparasitic agents, we here identify arylmethylamino steroids as potent compounds and characterize more than 60 derivatives. The lead compound 1o is fast acting and highly active against intraerythrocytic stages of chloroquine-sensitive and resistant Plasmodium falciparum parasites (IC50 1–5 nM) as well as against gametocytes. In P. berghei-infected mice, oral administration of 1o drastically reduces parasitaemia and cures the animals. Furthermore, 1o efficiently blocks parasite transmission from mice to mosquitoes. The steroid compounds show low cytotoxicity in mammalian cells and do not induce acute toxicity symptoms in mice. Moreover, 1o has a remarkable activity against the blood-feeding trematode parasite Schistosoma mansoni. The steroid and the hydroxyarylmethylamino moieties are essential for antimalarial activity supporting a chelate-based quinone methide mechanism involving metal or haem bioactivation. This study identifies chemical scaffolds that are rapidly internalized into blood-feeding parasites. PMID:28211535

  4. Reversal of Latency as Part of a Cure for HIV-1.

    PubMed

    Rasmussen, Thomas Aagaard; Tolstrup, Martin; Søgaard, Ole Schmeltz

    2016-02-01

    Here, the use of pharmacological agents to reverse HIV-1 latency will be explored as a therapeutic strategy towards a cure. However, while clinical trials of latency-reversing agents LRAs) have demonstrated their ability to increase production of latent HIV-1, such interventions have not had an effect on the size of the latent HIV-1 reservoir. Plausible explanations for this include insufficient host immune responses against virus-expressing cells, the presence of escape mutations in archived virus, or an insufficient scale of latency reversal. Importantly, these early studies of LRAs were primarily designed to investigate their ability to perturb the state of HIV-1 latency; using the absence of an impact on the size of the HIV-1 reservoir to discard their potential inclusion in curative strategies would be erroneous and premature.

  5. Auto-assembly of nanometer thick, water soluble layers of plasmid DNA complexed with diamines and basic amino acids on graphite: Greatest DNA protection is obtained with arginine.

    PubMed

    Khalil, T T; Boulanouar, O; Heintz, O; Fromm, M

    2017-02-01

    We have investigated the ability of diamines as well as basic amino acids to condense DNA onto highly ordered pyrolytic graphite with minimum damage after re-dissolution in water. Based on a bibliographic survey we briefly summarize DNA binding properties with diamines as compared to basic amino acids. Thus, solutions of DNA complexed with these linkers were drop-cast in order to deposit ultra-thin layers on the surface of HOPG in the absence or presence of Tris buffer. Atomic Force Microscopy analyses showed that, at a fixed ligand-DNA mixing ratio of 16, the mean thickness of the layers can be statistically predicted to lie in the range 0-50nm with a maximum standard deviation ±6nm, using a simple linear law depending on the DNA concentration. The morphology of the layers appears to be ligand-dependent. While the layers containing diamines present holes, those formed in the presence of basic amino acids, except for lysine, are much more compact and dense. X-ray Photoelectron Spectroscopy measurements provide compositional information indicating that, compared to the maximum number of DNA sites to which the ligands may bind, the basic amino acids Arg and His are present in large excess. Conservation of the supercoiled topology of the DNA plasmids was studied after recovery of the complex layers in water. Remarkably, arginine has the best protection capabilities whether Tris was present or not in the initial solution.

  6. trans,cis,cis-bis(benzoato)dichlorido(cyclohexane-1R,2R-diamine)platinum(IV): a prodrug candidate for the treatment of oxaliplatin-refractory colorectal cancer.

    PubMed

    Gandin, Valentina; Marzano, Cristina; Pelosi, Giorgio; Ravera, Mauro; Gabano, Elisabetta; Osella, Domenico

    2014-06-01

    The gold standard for the treatment of metastatic colorectal cancer consists of combination chemotherapy. Over time, however, the development of chemoresistant tumor clones leads to relapse. It may be possible to overcome oxaliplatin chemoresistance in colorectal cancer cells by exploiting a complex obtained from the insertion of the cyclohexane-1R,2R-diamine carrier ligand (the same diamine present in oxaliplatin) into an octahedral Pt(IV) scaffold with high lipophilicity conferred by two benzoate axial ligands. Herein we report the synthesis, characterization (including X-ray structure), biological activity, and cellular accumulation of trans,cis,cis-bis(benzoato)dichlorido(cyclohexane-1R,2R-diamine)platinum(IV) complex in a panel of several human cancer cell lines, including a colon carcinoma cell line resistant to oxaliplatin. The compound under investigation shows the best performance in terms of in vitro anti-proliferative activity and ability to overcome chemoresistance, with respect to oxaliplatin and some other Pt(II) reference complexes. This result is likely related to the high lipophilicity shown by the title compound that favors its cellular accumulation by passive diffusion.

  7. The natural cure of coronary heart disease.

    PubMed

    Withnell, Allan

    2003-01-01

    Following the development of coronary heart disease in 1989 I was introduced to an alumnus of the Pritikin Longevity Center in California and I adopted the regimen of diet and exercise. Within five months I was able to abandon all medication and was symptom free. My medical colleagues maintained that, because I had recovered, the Consultant's diagnosis must have been wrong--there can be no cure of coronary heart disease by lifestyle changes alone. As a result of my experience I decided to review the literature to study the natural history of coronary heart disease. My findings strongly suggest that the increase in incidence in the last hundred years from virtually nil to epidemic proportions is due to lifestyle changes and that the disease can be reversed. I list a number of doctors who have influenced large numbers of people to change their lifestyles with great success. They have utilised mainly plant-based diets whose composition is the same or similar to that which Pritikin originally used and which is still extant at the Longevity Center. I conclude by suggesting that the possibility of reversal of coronary heart disease has profound implications for its treatment with enormous potential savings for the National Health Service.

  8. [Spatial distribution of sulfur dioxide around a tobacco bulk-curing workshop cluster].

    PubMed

    He, Fan; Wang, Mei; Wang, Tao; Sun, Jian-Feng; Huang, Wu-Xing; Tian, Bin-Qiang; Gong, Chang-Rong

    2014-03-01

    In order to manifest lower energy consumption and less labor employment, and provide the theoretical basis for constructing environmentally friendly modem tobacco agriculture, this paper analyzed gas composition of the chimney from a bulk-curing barn and the dispersion of sulfur dioxide (SO2) around the workshop cluster using ecom-J2KN flue gas analyzer and air sampler. During curing, the concentrations of carbon dioxide (CO2) and SO2 in the chimney were both highest at 38 degrees C, while the concentration of nitrogen oxides (NOx) was highest at 42 degrees C. The emission concentration of SO2 from the chimney was 1327.60-2218.40 mg x m(-3). Average SO2 emission would decrease by 49.7% through adding 4.0% of a sulfur-fixed agent. The highest concentrations of SO2 in the surface soil appeared at the yellowing stage. SO2 concentration in horizontal direction localized at 43-80 m exceeded 0.5 mg x m(-3). The highest concentration of SO2 (0.57 mg x m(-3)) was observed at 50 m. At 50 m in the downstream wind direction of the workshop cluster, SO2 concentration in vertical direction localized at 0.9-1.8 m exceeded 0.5 mg x m(-3), and the highest concentration of SO2 in vertical direction was 0.65 mg x m(-3) at 1.6 m. During curing, the average concentration of SO2 was decreased by 0.43 mg x m(-3) by using the sulfur-fixed agent. The polluted boundary was localized at 120 m in the downstream wind direction of the workshop cluster.

  9. Magnesium sulphate as a new desensitizing agent.

    PubMed

    Liu, G H; Morimoto, M

    1991-07-01

    Various desensitizing agents have been used in clinics to solve the problem of dentinal hypersensitivity (DH), but none of them has been shown to be consistently effective. We here introduce a new type of desensitizing agent, i.e. 4% magnesium sulphate with iontophoresis at 2mA for 3 min. These optimal conditions were determined by animal experiments, while only a minor effect on dentinal issues was observed within 4 weeks after the treatment. When this desensitizing agent was used to treat DH, the cure rate of 62.4% remained steady within the 25-week observation period, while some effect was achieved in all the subjects who participated in the study.

  10. Development of a resin curing model for UV nanoimprint.

    PubMed

    Lee, Jin Woo; Cho, Dong-Woo

    2005-10-01

    UV nanoimprint lithography uses UV light as an energy source. It is performed at room temperature and low pressure, and has its own merits as compared to thermal nanoimprint. In this paper, a measurement system was developed to measure the degree of resin curing in UV nanoimprint to improve our understanding of the resin solidification phenomenon. A curing model was then established based on the measurement results. The measurement system measured the degree of cure in real time and was composed of a Fourier transform infrared spectroscopy system, a UV light source, and an optical guide. Also, new UV-curable resins that had low viscosity values were developed for the UV nanoimprint process, and imprint tests using these resins were performed successfully. The curing model considered the UV irradiation time, power, and curing temperature, which are important parameters in the UV nanoimprint process. The degree of cure had an exponential relation to UV irradiation time, power, and temperature; thus, the curing model was expressed as an exponential function of the UV irradiation time, power, and temperature. The developed model was verified for various UV-curable resins.

  11. Electron Beam Cured Epoxy Resin Composites for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Janke, Christopher J.; Dorsey, George F.; Havens, Stephen J.; Lopata, Vincent J.; Meador, Michael A.

    1997-01-01

    Electron beam curing of Polymer Matrix Composites (PMC's) is a nonthermal, nonautoclave curing process that has been demonstrated to be a cost effective and advantageous alternative to conventional thermal curing. Advantages of electron beam curing include: reduced manufacturing costs; significantly reduced curing times; improvements in part quality and performance; reduced environmental and health concerns; and improvement 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 the electron beam curing of PMC technology. Over the last several years a significant amount of effort within the CRADA has been devoted to the development and optimization of resin systems and PMCs that match the performance of thermal cured composites. This highly successful materials development effort has resulted in a board family of high performance, electron beam curable cationic epoxy resin systems possessing a wide range of excellent processing and property profiles. Hundreds of resin systems, both toughened and untoughened, offering unlimited formulation and processing flexibility have been developed and evaluated in the CRADA program.

  12. Comprehensive study of dynamic curing effect on tablet coating structure.

    PubMed

    Gendre, Claire; Genty, Muriel; da Silva, Julio César; Tfayli, Ali; Boiret, Mathieu; Lecoq, Olivier; Baron, Michel; Chaminade, Pierre; Péan, Jean Manuel

    2012-08-01

    The dissolution method is still widely used to determine curing end-points to ensure long-term stability of film coatings. Nevertheless, the process of curing has not yet been fully investigated. For the first time, joint techniques were used to elucidate the mechanisms of dynamic curing over time from ethylcellulose (Aquacoat)-based coated tablets. X-ray micro-computed tomography (XμCT), Near Infrared (NIR), and Raman spectroscopies as well as X-ray microdiffraction were employed as non-destructive techniques to perform direct measurements on tablets. All techniques indicated that after a dynamic curing period of 4h, reproducible drug release can be achieved and no changes in the microstructure of the coating were any longer detected. XμCT analysis highlighted the reduced internal porosity, while both NIR and Raman measurements showed that spectral information remained unaltered after further curing. X-ray microdiffraction revealed densification of the coating layer with a decrease in the overall coating thickness of about 10 μm as a result of curing. In addition, coating heterogeneity attributed to cetyl alcohol was observed from microscopic images and Raman analysis. This observation was confirmed by X-ray microdiffraction that showed that crystalline cetyl alcohol melted and spread over the coating surface with curing. Prior to curing, X-ray microdiffraction also revealed the existence of two coating zones differing in crystalline cetyl alcohol and sodium lauryl sulfate concentrations which could be explained by migration of these constituents within the coating layer. Therefore, the use of non-destructive techniques allowed new insights into tablet coating structures and provided precise determination of the curing end-point compared to traditional dissolution testing. This thorough study may open up new possibilities for process and formulation control.

  13. Changes on degree of conversion of dual-cure luting light-cured with blue LED

    NASA Astrophysics Data System (ADS)

    Bandéca, M. C.; El-Mowafy, O.; Saade, E. G.; Rastelli, A. N. S.; Bagnato, V. S.; Porto-Neto, S. T.

    2009-05-01

    The indirect adhesive procedures constitute recently a substantial portion of contemporary esthetic restorative treatments. The resin cements have been used to bond tooth substrate and restorative materials. Due to recently introduction of the self-bonding resin luting cement based on a new monomer, filler and initiation technology has become important to study the degree of conversion of these new materials. In the present work the polymerization reaction and the filler content of dual-cured dental resin cements were studied by means of infra-red spectroscopy (FT-IR) and thermogravimetry (TG). Twenty specimens were made in a metallic mold (8 mm diameter × 1 mm thick) from each of 2 cements, Panavia® F2.0 (Kuraray) and RelyX™ Unicem Applicap (3M/ESPE). Each specimen was cured with blue LED with power density of 500 mW/cm2 for 30 s. Immediately after curing, 24 and 48 h, and 7 days DC was determined. For each time interval 5 specimens were pulverized, pressed with KBr and analyzed with FT-IR. The TG measurements were performed in Netzsch TG 209 under oxygen atmosphere and heating rate of 10°C/min from 25 to 700°C. A two-way ANOVA showed DC (%) mean values statistically significance differences between two cements ( p < 0.05). The Tukey’s test showed no significant difference only for the 24 and 48 h after light irradiation for both resin cements ( p > 0.05). The Relx-Y™ Unicem mean values were significantly higher than Panavia® F 2.0. The degree of conversion means values increasing with the storage time and the filler content showed similar for both resin cements.

  14. Depth of cure of bulk fill composites with monowave and polywave curing lights

    PubMed Central

    Menees, Timothy S.; Lin, Chee Paul; Kojic, Dave D.; Burgess, John O.; Lawson, Nathaniel C.

    2016-01-01

    Purpose To measure and compare the depth of cure (DOC) of two bulk fill composite resins using a monowave and polywave light curing unit (LCU) according to ISO 4049 and using custom tooth molds. Methods The DOC of Tetric Evoceram Bulk Fill (Ivoclar Vivadent) and Filtek Bulk Fill Posterior (3M ESPE) were measured using a monowave LED LCU (Elipar S10 / 3M ESPE) and a polywave LED LCU (Bluephase G2 / Ivoclar Vivadent). Metal molds were used to fabricate 10 mm long DOC specimens (n=10) according to ISO 4049. Uncured composite material was scraped away with a plastic instrument and half the length of remaining composite was measured as the DOC. Custom tooth molds were fabricated by preparing >10mm long square-shaped (4 × 4 mm) holes into the mesial/distal surfaces of extracted human molars. Composite resin was placed into one end of the prepared tooth and light polymerized. Uncured composite resin was removed from the opposite side from which the tooth was irradiated and the tooth was sectioned mesio-distally. Half the length of remaining cured composite was measured as the DOC. Data were analyzed by three-way ANOVA (alpha=0.05) for factors material, LCU, and mold. Results The main effect LCU was not significant (p=.58). The interaction effect between material × mold was significant (p=.0001). The DOC of the composites differed significantly only with the stainless steel mold in which Tetric Evoceram Bulk Fill showed a deeper DOC than Filtek Bulk Fill Posterior (4.03 ± 0.14 vs 3.56 ± 0.38 mm, p<.0001). PMID:26897758

  15. Synthesis and in vitro antitumor activity of novel iridium(III) complexes with enantiopure C2-symmetrical vicinal diamine ligands.

    PubMed

    Yang, Qing; Chang, Jun; Song, Jiao; Qian, Meng-Ting; Yu, Jian-Ming; Sun, Xun

    2013-08-15

    Four novel iridium(III) complexes with enantiopure C2-symmetrical vicinal diamine ligands were designed, synthesized, and characterized by FT-IR, NMR, and MS. The cytotoxicities of all of the complexes against the human solid tumor cell lines A2780, A549, KB, and MDA-MB-231 were evaluated. Both R,R-configured complexes (R,R)-5a and (R,R)-5b exhibited more potent or similar activity compared with oxaliplatin, whereas their corresponding (S,S)-isomers (S,S)-5a and (S,S)-5b were found to be mostly inactive. As indicated by the activation of caspase-3, the cleavage of PARP, and the upregulation of p53, the preliminary mechanism studies revealed that the mode of cell death initiated by (R,R)-5a in A2780 cells was predominantly p53-mediated apoptosis. In addition, the structure of (R,R)-5a was unambiguously confirmed through single crystal X-ray structure determination.

  16. Factors influencing diamine oxidase activity and γ-aminobutyric acid content of fava bean (Vicia faba L.) during germination.

    PubMed

    Yang, Runqiang; Chen, Hui; Gu, Zhenxin

    2011-11-09

    Factors (germination time, spectra, temperature, pH, and chemical inhibitors) influencing diamine oxidase (DAO, EC 1.4.3.6) activity and γ-aminobutyric acid (GABA) content of fava bean (Vicia faba L.) during germination were investigated in this study. DAO activity significantly increased in germinating seeds but varied with different organs. The enzyme activity was higher in shoot than that in cotyledon, hypocotyl, and radicle. When seeds were germinated in the dark, DAO activity was 2.35-, 2.00-, 2.36-, 4.40-, and 1.67-fold of that under white, red, blue, green, and yellow spectra, respectively. The optimum germination temperature and pH value for increasing DAO activity were 30 °C and 3.0, respectively. The DAO activity was inhibited significantly by aminoguanidine and sodium ethylenediamine tetracetate, while it was activated by CuCl(2) and CaCl(2). Germinating at an appropriate temperature and pH, 30% of GABA formation was supplied by DAO. Calcium was related to the regulation of DAO activity and GABA accumulation.

  17. Optimizing anti-coking abilities of zeolites by ethylene diamine tetraacetie acid modification on catalytic fast pyrolysis of corn stalk

    NASA Astrophysics Data System (ADS)

    Zhang, Bo; Zhong, Zhaoping; Song, Zuwei; Ding, Kuan; Chen, Paul; Ruan, Roger

    2015-12-01

    In order to minimize coke yield during biomass catalytic fast pyrolysis (CFP) process, ethylene diamine tetraacetie acid (EDTA) chemical modification method is carried out to selectively remove the external framework aluminum of HZSM-5 catalyst. X-ray diffraction (XRD), nitrogen (N2)-adsorption and ammonia-temperature programmed desorption (NH3-TPD) techniques are employed to investigate the porosity and acidity characteristics of original and modified HZSM-5 samples. Py-GC/MS and thermo-gravimetric analyzer (TGA) experiments are further conducted to explore the catalytic effect of modified HZSM-5 samples on biomass CFP and to verify the positive effect on coke reduction. Results show that EDTA treatment does not damage the crystal structure of HZSM-5 zeolites, but leads to a slight increase of pore volume and pore size. Meanwhile, the elimination of the strong acid peak indicates the dealumination of outer surface of HZSM-5 zeolites. Treatment time of 2 h (labeled EDTA-2H) is optimal for acid removal and hydrocarbon formation. Among all modified catalysts, EDTA-2H performs the best for deacidification and can obviously increase the yields of positive chemical compositions in pyrolysis products. Besides, EDTA modification can improve the anti-coking properties of HZSM-5 zeolites, and EDTA-2H gives rise to the lowest coke yield.

  18. A rhenium complex with diamine ligand containing oxadiazole group and fluorine atom: Synthesis, characterization, photoluminescence and electroluminescence performances

    NASA Astrophysics Data System (ADS)

    Yang, Wensheng; Yang, Wan; Liu, Weisheng; Qin, Wenwu

    2013-03-01

    In this paper, a diamine ligand of 2-(4-fluorophenyl)-5-(pyridin-2-yl)-1,3,4-oxadiazole (FPYOZ), which owned both enlarged conjugation chain with electron-pulling group and fluorine atom, was synthesized. Its corresponding Re(I) complex was also synthesized and studied in detail, including single crystal analysis, electronic structure, photophysical performance, thermal stability and electrochemical property. Single crystal analysis suggested that there was a coordination ability difference between the N atom from pyridine ring and the one from oxadiazole moiety. Theoretical calculation on the complex suggested that the onset electronic transition owned a mixed character of metal-to-ligand-charge-transfer and ligand-to-ligand-charge-transfer. Upon photoexcitation of 375 nm, this complex showed a yellow emission peaking at 537 nm with excited state lifetime of 8.35 μs. Cyclic voltammetry result suggested that this complex owned HOMO and LUMO energy levels of -5.37 eV and -3.04 eV. The decomposition temperature of this complex was as high as 300 °C, as revealed by thermogravimetric analysis data. The optimal electroluminescence device using this complex as the emitting dopant showed an electroluminescence peaking at 562 nm, with a maximum luminance of 6250 cd/m2 and a maximum current efficiency of 7.3 cd/A.

  19. A promising Rhenium(I) complex with fluorine/oxadiazole-bifunctionalized diamine ligand: Synthesis, structure and photophysical property

    NASA Astrophysics Data System (ADS)

    Wang, Xin-Fang

    2013-01-01

    In this paper, a diamine ligand of 2-(4-fluorophenyl)-5-(pyridin-2-yl)-1,3,4-oxadiazole (denoted as FPO) and its corresponding Re(I) complex of Re(CO)3(FPO)Br are synthesized. Full characterization on Re(CO)3(FPO)Br, including NMR, elemental analysis and single crystal analysis, confirms its molecular identity. Upon photon excitation, the emission of Re(CO)3(FPO)Br owns a long excited state lifetime of 8.95 μs in pure N2 atmosphere and shows a maximum intensity at 540 nm. Theoretical calculation on Re(CO)3(FPO)Br single crystal suggests that the excited state has a triplet metal-to-ligand-charge-transfer character. By embedding Re(CO)3(FPO)Br into a polymer supporting matrix of polystyrene, the emission signal is found to be sensitive towards varying oxygen concentrations, with a maximum sensitivity of 7.84. Due to the porous structure of nanofibrous polystyrene matrix, a short response time of 8 s towards molecular oxygen is also observed with stable quenching signal.

  20. Charge localization in a diamine cation provides a test of energy functionals and self-interaction correction

    PubMed Central

    Cheng, Xinxin; Zhang, Yao; Jónsson, Elvar; Jónsson, Hannes; Weber, Peter M.

    2016-01-01

    Density functional theory (DFT) is widely applied in calculations of molecules and materials. Yet, it suffers from a well-known over-emphasis on charge delocalization arising from self-interaction error that destabilizes localized states. Here, using the symmetric diamine N,N′-dimethylpiperazine as a model, we have experimentally determined the relative energy of a state with positive charge localized on one of the two nitrogen atoms, and a state with positive charge delocalized over both nitrogen atoms. The charge-localized state was found to be 0.33 (0.04) eV higher in energy than the charge-delocalized state. This provides an important test of theoretical approaches to electronic structure calculations. Calculations with all DFT functionals commonly used today, including hybrid functionals with exact exchange, fail to predict a stable charge-localized state. However, the application of an explicit self-interaction correction to a semi-local functional identifies both states and gives relative energy in excellent agreement with both experiment and CCSD(T) calculations. PMID:26980327

  1. [Diamine oxidase as blood biomarker in rats and humans to GI tract toxicity of fluorouracil anti-cancer drugs].

    PubMed

    Goto, Tetsuhiro; Matsubara, Taketo; Yoshizawa, Yasuo; Sasaya, Shouji; Nemoto, Hiroshi; Sanada, Yutaka; Moriyama, Kenji; Kouchi, Yasuhide

    2011-05-01

    Diarrhea is a side effect of a 5-fluorouracil (5-FU) anti-cancer drug-induced intestinal mucosal disorder, which sometimes becomes more severe. Blood diamine oxidase (DAO; EC1. 4. 3. 6) activity is reported to be significantly correlated with activity in the small intestinal mucosal tissue, and to be a reliable indicator of small intestinal mucosal integrity and maturity. Here, we investigated whether blood DAO activity can be a biomarker for the gastrointestinal (GI) mucosal disorder caused by 5-FU anti-cancer drugs, both in rats and humans. From results of the rat study, the degree of jejunal mucosal disorder caused by the 5-FU anti-cancer drug was well correlated with a decrease in blood DAO activity. Clinically, 12 out of 28 patients (43%) administered 5-FU anti-cancer drug suffered from diarrhea. The plasma DAO activity within one week of the onset of diarrhea significantly decreased compared with that before the administration. Furthermore, before drug administration, plasma DAO activity in patients suffering from diarrhea was higher than those in patients without diarrhea. Although DAO activity differs by the individual, it is a useful biomarker for estimating the degree of intestinal mucosal disorder, and possibly for estimating manifestations of diarrhea induced by 5-FU anti-cancer drug administration.

  2. Synthesis, characterization and intermolecular interactions in crystals of two p-tert-butylthiacalix[4]arene diisocyanide and diamine derivatives

    NASA Astrophysics Data System (ADS)

    Shi, Sheng-Jie; Lv, Xue-Xin; Zhao, Mei; Ma, Jian-Ping; Guo, Dian-Shun

    2017-01-01

    The synthesis, the spectral characterization and the crystal structure of 25,27-bis(2-isocyanoethoxy)-5,11,17,23-tetra-tert-butyl-26,28-dihydroxythiacalix[4]arene and of the reaction intermediate 25,27-bis(2-aminoethoxy)-5,11,17,23-tetra-tert-butyl-26,28-dihydroxythiacalix[4]arene are here described. The target diisonitrile compound crystallizes in the triclinic system with space group P-1 while the diamine intermediate is trigonal with space group R-3. In both structures, the thiacalix[4]arene units adopt a broadly similar pinched cone conformation, where two aromatic rings bearing an ethereal group are almost parallel while two phenolic rings lie near-vertically. In the supramolecular structure of both molecules, various intermolecular interactions involving Csbnd H⋯O, Csbnd H⋯C, Csbnd H⋯π and weak Csbnd H⋯S interactions were found. Moreover, the Hirshfeld surface analysis of the target compound was made to further confirm the crystal packing driving forces.

  3. Feasibility assessment of piezoelectric crystals as chemical warfare agent sensors. Final report, 1 August 1983-31 August 1985

    SciTech Connect

    Balog, P.P.; Stanford, T.B.; Nordstrom, R.J.; Burgener, R.C.

    1986-04-01

    The feasibility of a vibrating piezoelectric crystal as a CW agent detector was assessed by applying CW agent-sensitive coatings to the crystal and testing the detector with 0.3 mg/cum of GB (Sarin). Eight different coating materials were selected, based on previous data with G-agent simulants. No responses were observed to 0.3 mg/cum. GB, but three costings (XAD-4/Cu(2=)-diamine, polyethylenemaleate, and succinyl choline chloride) gave responses of -59 Hz, -22 Hz, and =11 Hz, respectively, to 10 mg/cm.of DIMP (diisopropyl methylphosphonate). Circuit optimization and the use of an operating frequency higher than 9 MHz is recommended to enhance sensitivity. Far-term recommendations are to apply the same coatings to a high-frequency (e.g., 300 MHz) surface acoustic-wave device and test again with CW agents.

  4. Acute promyelocytic leukaemia: novel insights into the mechanisms of cure.

    PubMed

    de Thé, Hugues; Chen, Zhu

    2010-11-01

    The fusion oncogene, promyelocytic leukaemia (PML)-retinoic acid receptor-α (RARA), initiates acute promyelocytic leukaemia (APL) through both a block to differentiation and increased self-renewal of leukaemic progenitor cells. The current standard of care is retinoic acid (RA) and chemotherapy, but arsenic trioxide also cures many patients with APL, and an RA plus arsenic trioxide combination cures most patients. This Review discusses the recent evidence that reveals surprising new insights into how RA and arsenic trioxide cure this leukaemia, by targeting PML-RARα for degradation. Drug-triggered oncoprotein degradation may be a strategy that is applicable to many cancers.

  5. Cure-dependent Viscoelastic Poisson’s Ratio of Epoxy

    DTIC Science & Technology

    2007-01-26

    Faivre S, Roy LE, Trotignon JP, Verdu J (1996) Mechanical properties of thermosets. Part I. Tensile properties of an anhydride cured epoxy . J Mater...Experimental Mechanics (2007) 47: 237–249 DOI 10.1007/s11340-006-9013-9 Cure -dependent Viscoelastic Poisson’s Ratio of Epoxy D.J. O’Brien · N.R...Abstract The evolution of the lateral contraction ratio of two commercial (high and low temperature cure ) epoxy resins is studied in uniaxial tension

  6. Mathematical Model Of Curing Behavior Of A Polymer

    NASA Technical Reports Server (NTRS)

    Loomis, Willard C.; Beyer, Rodney B.; Liu, Edmund K. S.

    1995-01-01

    Mathematical model predicts selected aspects of chemical, thermal and mechanical responses of polymeric liner and propellant materials during curing process. Predictions made both prior to processing and during process in quasi-real time. Developed specifically for use in designing and analyzing process in which bondline materials (including polymeric liners) and propellant cast and cured in rocket motor. With modifications, model applicable to curing of other polymeric materials. Further development may provide direct "in-line" program for calculations, including comparisons, in real time. This will constitute basis for more sophisticated control of process.

  7. Mechanism of Monuron-Accelerated Dicyandiamide Cure of Epoxy Resins

    DTIC Science & Technology

    1981-07-01

    ÜBBSBBffl^w^r’r^^—. ■ «Mmfifißmwww-tr- oo o m* AMMRC TR 81-34 AD MECHANISM OF < MONURON-ACCELERATED ^ DICYANDIAMIDE CURE OF...REPORT NJJMMR RC-TR-81-34 2. GOVT ACCESSION NO. 4. TITLE fand Submit) AV-A/^if^ , MECHANISM OF MONURON-ACCELERATED DICYANDIAMIDE CURE OF EPOXY...4-chJqTophenyl)-tI,,N,-dimethylurea, >is the ability of this class of aryl ureas to accelerate the dicyandiamide (Dicy) cure of epoxy resins

  8. Micromechanical properties of veneer luting resins after curing through ceramics.

    PubMed

    Oztürk, Elif; Hickel, Reinhard; Bolay, Sükran; Ilie, Nicoleta

    2012-02-01

    The aim of this study was to assess the performance of light-cured luting resin after curing under the ceramic restoration in comparison to dual-cured luting resin, by evaluating the micromechanical properties. Two hundred seventy thin luting composite films of ca. 170 μm in thickness were prepared by using two light-cured luting resins (Variolink Veneer, Ivoclar Vivadent; RelyX Veneer, 3M ESPE) and a dual-cured luting resin (Variolink II, Ivoclar Vivadent). The composites were cured by using a LED-unit (Bluephase®, Ivoclar Vivadent) with three different curing times (10, 20, and 30 s) under two ceramics (IPS e.max Press, Ivoclar Vivadent; IPS Empress® CAD, Ivoclar Vivadent) of different thicknesses (0, 0.75, and 2 mm). Forty-five groups were included, each containing six thin films. The samples were stored after curing for 24 h at 37°C by maintaining moisture conditions with distilled water. Micromechanical properties of the composites were measured with an automatic microhardness indenter (Fisherscope H100C, Germany). For each sample, ten indentations were made, thus totalizing 60 measurements per group. Micromechanical properties of the luting resins were statistically analyzed (SPSS 17.0). Significant differences were observed between the micromechanical properties of the luting resins (p < 0.05). Variolink II showed the highest values in modulus of elasticity (E = 11 ± 0.5)* and Vickers hardness (HV = 48.2 ± 3.2)* and the lowest values in creep (Cr = 4.3 ± 0.1)* and elastic-plastic deformation (We/Wtot = 38.6 ± 0.7)* followed by RelyX Veneer (E = 6.9 ± 0.3, HV = 33 ± 2.5, Cr = 4.6 ± 0.2, We/Wtot = 41.8 ± 1.0)* and Variolink Veneer (E = 4.4 ± 0.4, HV = 20.1 ± 2.6, Cr = 5 ± 0.2, We/Wtot = 43.7 ± 1.3)*. Dual-cured luting resin expressed higher values in the micro-mechanical properties compared to the light-cured luting resins. The effect of luting resin type on the micromechanical properties of the luting resins was higher than the effect of

  9. Health care agents

    MedlinePlus

    Durable power of attorney for health care; Health care proxy; End-of-life - health care agent; Life support treatment - ... Respirator - health care agent; Ventilator - health care agent; Power of attorney - health care agent; POA - health care ...

  10. Comparison of the Amount of Temperature Rise in the Pulp Chamber of Teeth Treated With QTH, Second and Third Generation LED Light Curing Units: An In Vitro Study

    PubMed Central

    Mahant, Rajesh Harivadanbhai; Chokshi, Shraddha; Vaidya, Rupal; Patel, Pruthvi; Vora, Asima; Mahant, Priyanka

    2016-01-01

    Introduction: This in vitro study was designed to measure and compare the amount of temperature rise in the pulp chamber of the teeth exposed to different light curing units (LCU), which are being used for curing composite restorations. Methods: The study was performed in two settings; first, an in vitro and second was mimicking an in vivo situation. In the first setup of the study, three groups were formed according to the respective three light curing sources. i.e. quartz-tungsten-halogen (QTH) unit and two light-emitting diode (LED) units (second and third generations). In the in vitro setting, direct thermal emission from three light sources at 3 mm and 6 mm distances, was measured with a k-type thermocouple, and connected to a digital thermometer. For a simulation of an in vivo situation, 30 premolar teeth were used. Class I Occlusal cavity of all the teeth were prepared and they were restored with incremental curing of composite, after bonding agent application. While curing the bonding agent and composite in layers, the intrapulpal temperature rise was simultaneously measured with a k-type thermocouple. Results: The first setting of the study showed that the heat produced by irradiation with LCU was significantly less at 6 mm distance when compared to 3 mm distance. The second setting of the study showed that the rise of intrapulpal temperature was significantly less with third generation LED light cure units than with second generation LED and QTH light cure units. Conclusion: As the distance from the light source increases, less irradiation heat is produced. Third generation LED lights cause the least temperature change in the pulp chamber of single rooted teeth. PMID:28144440

  11. Comparison of the Amount of Temperature Rise in the Pulp Chamber of Teeth Treated With QTH, Second and Third Generation LED Light Curing Units: An In Vitro Study.

    PubMed

    Mahant, Rajesh Harivadanbhai; Chokshi, Shraddha; Vaidya, Rupal; Patel, Pruthvi; Vora, Asima; Mahant, Priyanka

    2016-01-01

    Introduction: This in vitro study was designed to measure and compare the amount of temperature rise in the pulp chamber of the teeth exposed to different light curing units (LCU), which are being used for curing composite restorations. Methods: The study was performed in two settings; first, an in vitro and second was mimicking an in vivo situation. In the first setup of the study, three groups were formed according to the respective three light curing sources. i.e. quartz-tungsten-halogen (QTH) unit and two light-emitting diode (LED) units (second and third generations). In the in vitro setting, direct thermal emission from three light sources at 3 mm and 6 mm distances, was measured with a k-type thermocouple, and connected to a digital thermometer. For a simulation of an in vivo situation, 30 premolar teeth were used. Class I Occlusal cavity of all the teeth were prepared and they were restored with incremental curing of composite, after bonding agent application. While curing the bonding agent and composite in layers, the intrapulpal temperature rise was simultaneously measured with a k-type thermocouple. Results: The first setting of the study showed that the heat produced by irradiation with LCU was significantly less at 6 mm distance when compared to 3 mm distance. The second setting of the study showed that the rise of intrapulpal temperature was significantly less with third generation LED light cure units than with second generation LED and QTH light cure units. Conclusion: As the distance from the light source increases, less irradiation heat is produced. Third generation LED lights cause the least temperature change in the pulp chamber of single rooted teeth.

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

    PubMed Central

    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. PMID:25587389

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

    PubMed

    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.

  14. Measuring Vapors To Monitor the State of Cure of a Resin

    NASA Technical Reports Server (NTRS)

    Cramer, Elliott; Perey, Daniel F.; Yost, William T.

    2006-01-01

    A proposed noninvasive method of monitoring the cure path and the state of cure of an epoxy or other resin involves measurement of the concentration( s) of one or more compound(s) in the vaporous effluent emitted during the curing process. The method is based on the following general ideas: (1) The concentrations of the effluent compounds in the vicinity of the curing resin are approximately proportional to the instantaneous rate of curing. (2) As curing proceeds at a given temperature, subsequent decreases in the concentrations are indicative of approaching completion of cure; that is, the lower are the concentrations, the more nearly complete is the cure.

  15. Detecting agents.

    PubMed Central

    Johnson, Susan C

    2003-01-01

    This paper reviews a recent set of behavioural studies that examine the scope and nature of the representational system underlying theory-of-mind development. Studies with typically developing infants, adults and children with autism all converge on the claim that there is a specialized input system that uses not only morphological cues, but also behavioural cues to categorize novel objects as agents. Evidence is reviewed in which 12- to 15-month-old infants treat certain non-human objects as if they have perceptual/attentional abilities, communicative abilities and goal-directed behaviour. They will follow the attentional orientation of an amorphously shaped novel object if it interacts contingently with them or with another person. They also seem to use a novel object's environmentally directed behaviour to determine its perceptual/attentional orientation and object-oriented goals. Results from adults and children with autism are strikingly similar, despite adults' contradictory beliefs about the objects in question and the failure of children with autism to ultimately develop more advanced theory-of-mind reasoning. The implications for a general theory-of-mind development are discussed. PMID:12689380

  16. Curing behavior and reaction kinetics of binder resins for 3D-printing investigated by dielectric analysis (DEA)

    NASA Astrophysics Data System (ADS)

    Möginger, B.; Kehret, L.; Hausnerova, B.; Steinhaus, J.

    2016-05-01

    3D-Printing is an efficient method in the field of additive manufacturing. In order to optimize the properties of manufactured parts it is essential to adapt the curing behavior of the resin systems with respect to the requirements. Thus, effects of resin composition, e.g. due to different additives such as thickener and curing agents, on the curing behavior have to be known. As the resin transfers from a liquid to a solid glass the time dependent ion viscosity was measured using DEA with flat IDEX sensors. This allows for a sensitive measurement of resin changes as the ion viscosity changes two to four decades. The investigated resin systems are based on the monomers styrene and HEMA. To account for the effects of copolymerization in the calculation of the reaction kinetics it was assumed that the reaction can be considered as a homo-polymerization having a reaction order n≠1. Then the measured ion viscosity curves are fitted with the solution of the reactions kinetics - the time dependent degree of conversion (DC-function) - for times exceeding the initiation phase representing the primary curing. The measured ion viscosity curves can nicely be fitted with the DC-function and the determined fit parameters distinguish distinctly between the investigated resin compositions.

  17. The effect of curing light and chemical catalyst on the degree of conversion of two dual cured resin luting cements.

    PubMed

    Souza-Junior, Eduardo José; Prieto, Lúcia Trazzi; Soares, Giulliana Panfiglio; Dias, Carlos Tadeu dos Santos; Aguiar, Flávio Henrique Baggio; Paulillo, Luís Alexandre Maffei Sartini

    2012-01-01

    The aim of this study was to evaluate the influence of different curing lights and chemical catalysts on the degree of conversion of resin luting cements. A total of 60 disk-shaped specimens of RelyX ARC or Panavia F of diameter 5 mm and thickness 0.5 mm were prepared and the respective chemical catalyst (Scotchbond Multi-Purpose Plus or ED Primer) was added. The specimens were light-cured using different curing units (an argon ion laser, an LED or a quartz-tungsten-halogen light) through shade A2 composite disks of diameter 10 mm and thickness 2 mm. After 24 h of dry storage at 37°C, the degree of conversion of the resin luting cements was measured by Fourier-transformed infrared spectroscopy. For statistical analysis, ANOVA and the Tukey test were used, with p ≤ 0.05. Panavia F when used without catalyst and cured using the LED or the argon ion laser showed degree of conversion values significantly lower than RelyX ARC, with and without catalyst, and cured with any of the light sources. Therefore, the degree of conversion of Panavia F with ED Primer cured with the quartz-tungsten-halogen light was significantly different from that of RelyX ARC regardless of the use of the chemical catalyst and light curing source. In conclusion, RelyX ARC can be cured satisfactorily with the argon ion laser, LED or quartz-tungsten-halogen light with or without a chemical catalyst. To obtain a satisfactory degree of conversion, Panavia F luting cement should be used with ED Primer and cured with halogen light.

  18. Effect of curing mode on the micro-mechanical properties of dual-cured self-adhesive resin cements.

    PubMed

    Ilie, Nicoleta; Simon, Alexander

    2012-04-01

    Light supplying to luting resin cements is impeded in several clinical situations, causing us to question whether materials can properly be cured to achieve adequately (or adequate) mechanical properties. The aim of this study was therefore to analyse the effect of light on the micro-mechanical properties of eight popular dual-cured self-adhesive resin cements by comparing them with two conventional, also dual-cured, resin cements. Four different curing procedures were applied: auto-polymerisation (dark curing) and light curing (LED unit, Freelight 2, 20 s) by applying the unit directly on the samples' surface, at a distance of 5 and 10 mm. Twenty minutes after curing, the samples were stored for 1 week at 37°C in a water-saturated atmosphere. The micro-mechanical properties-Vickers hardness, modulus of elasticity, creep and elastic/plastic deformation-were measured. Data were analysed with multivariate ANOVA followed by Tukey's test and partial eta-squared statistics (p < 0.05). A very strong influence of the material as well as filler volume and weight on the micro-mechanical properties was measured, whereas the influence of the curing procedure and type of cement-conventional or self-adhesive-was generally low. The influence of light on the polymerisation process was material dependent, with four different behaviour patterns to be distinguished. As a material category, significantly higher micro-mechanical properties were measured for the conventional compared to the self-adhesive resin cements, although this difference was low. Within the self-adhesive resin cements group, the variation in micro-mechanical properties was high. The selection of suitable resin cements should be done by considering, besides its adhesive properties, its micro-mechanical properties and curing behaviour also.

  19. 7 CFR 29.3002 - Air-cured.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... INSPECTION Standards Official Standard Grades for Burley Tobacco (u.s. Type 31 and Foreign Type 93) § 29.3002... control excess humidity during the curing period to prevent house-burn and barn-burn in damp weather....

  20. Investigation of Adhesive Bond Cure Conditions using Nonlinear Ultrasonic Methods

    NASA Technical Reports Server (NTRS)

    Berndt, Tobias P.; Green, Robert E., Jr.

    1999-01-01

    The objective of this presentation is to investigate various cure conditions of adhesive bonds using nonlinear ultrasonic methods with water coupling. Several samples were used to obtain normal incidence, oblique incidence, and wave mixing.