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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. 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 with very high melt temperatures 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. Previously announced in STAR as N83-27018

  11. Ultrasonic Mixing of Epoxy Curing Agents

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    New ultrasonic mixing technique used to mix several curing agents/epoxy combinations. Major component of commercially available base epoxy resin used in tetraglycidylmethylenedianiline (TGMDA). In ultrasonic mixing system cup holds resin and curing agent during acoustic excitation. Samples placed in cup with top to ultrasonic horn forming bottom of cup. Ultrasonically treated until amber colored and transparent. Because ultrasonic agitation drives out entrapped air, degassing not necessary before cure.

  12. 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.

  13. 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.

  14. Hierarchical morphology of carbon single-walled nanotubes during sonication in an aliphatic diamine

    SciTech Connect

    Brown, Janis M.; Anderson, David P.; Justice, Ryan S.; Lafdi, Khalid; Belfor, Max; Strong, Karla L.; Schaefer, Dale W.

    2010-07-13

    Dispersion of single-walled carbon nanotubes (SWNTs) by sonication into diamine curing agents is studied as a means to improve the dispersion of SWNTs in cured epoxy. Cured and uncured specimens are analyzed by light microscopy, electron microscopy, light scattering (LS), ultra small-angle X-ray scattering (USAXS), electrical conductivity and Raman spectroscopy. A flexible diamine (D2000) forms a stable SWNT suspension leading to good homogeneity in both the diamine and the cured epoxy. High resolution transmission electron microscopy (TEM) shows that small ropes of SWNTs (mostly under 15 nm) are present despite the sample's visual homogeneity. Further morphological investigation of cured and uncured D2000 resins using light and small-angle X-ray scattering indicates that the SWNTs are networked into fractal clusters that electrically percolate at low SWNTs loadings (0.05 wt%).

  15. 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.

  16. Phosphazene diamines

    NASA Technical Reports Server (NTRS)

    Paciorek, K. L.; Harris, D. H.; Ito, T. I.; Kratzer, R. H.

    1980-01-01

    The synthesis of a specific phosphazene diamine was optimized, other phosphorus-containing diamines were prepared, and their effect upon certain characteristics of epoxy resins, prepared via reaction with MY 720, in particular, char yield at elevated temperatures was evaluated. The synthesis of the phosphazene diamine resulting from the interaction of methylenedianline with 4,4'-bis(diphenylphosphino)biphenyl was simplified into a one step process giving 77 percent yield of the pure product. Using this procedure, a related diamine containing bis(diphenylphosphino)methane was obtained in a 70 percent yield. Preparation of another class of phosphorus containing amines based upon p-aminophenyldiphenyl-phosphine was unsuccessful; the inability to produce p-aminophenylithlum was responsible for this failure. Seven epoxy resins employing Araldite MY 720, diaminodiphenylsulfone, and two of the phosphorus containing diamines were prepared, characterized, and their char yield capacity at elevated temperatures assessed. Based on these investigations, the resins containing phosphorus appear to exhibit significantly better char formation characteristics than materials hardened using conventional amines, without impairing the other properties measured.

  17. 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

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

    PubMed

    Zhao, Chenhui; Zhang, Guangcheng; Zhao, Lei

    2012-01-01

    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.

  20. 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.

  1. 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.

  2. 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. PMID:26235448

  3. 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.

  4. 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

  5. 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.

  6. 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

  7. Influence of glazed zirconia on dual-cure luting agent bond strength.

    PubMed

    Valentino, T A; Borges, G A; Borges, L H; Platt, J A; Correr-Sobrinho, L

    2012-01-01

    The current study evaluated the influence of a novel surface treatment that uses a low-fusing porcelain glaze for promoting a bond between zirconia-based ceramic and a dual-cure resin luting agent. Bond strengths were compared with those from airborne particle abrasion, hydrofluoric acid etching, and silanization-treated surfaces. Twenty-four yttrium-stabilized tetragonal zirconia (Cercon Smart Ceramics, Degudent, Hanau, Germany) discs were fabricated and received eight surface treatments: group 1: 110 μm aluminum oxide air-borne particle abrasion; group 2: 110 μm aluminum oxide airborne particle abrasion and silane; group 3: 50 μm aluminum oxide airborne particle abrasion; group 4: 50 pm aluminum oxide airborne particle abrasion and silane; group 5: glaze and hydrofluoric acid;group 6: glaze, hydrofluoric acid, and silane;group 7: glaze and 50 pm aluminum oxide airborne particle abrasion; and group 8: glaze,50 pm aluminum oxide airborne particle abrasion and silane. After treatment, Enforce resin cement (Dentsply, Caulk, Milford, DE, USA) was used to fill an iris cut from microbore Tygontubing that was put on the ceramic surface to create 30 cylinders of resin cement in each treatment group (n=30). Micro shear bond test-ing was performed at a cross head speed of 0.5mm/min. One-way analysis of variance, and multiple comparisons were made using Tukey's test (p<0.5). The bond strength was affected only by surface treatments other than silanization. The groups that utilized the low-fusing porcelain glaze with airborne particle abrasion or hydrofluoric acid showed bond strength values statistically superior to groups that utilized conventional airborne particle abrasion treatments with 50 or 110 pm aluminum oxide (p<0.001). The treatment that utilized low-fusing porcelain glaze and hydrofluoric acid showed bond strength values statistically superior to remaining groups (p<0.001). Treatment of zirconia ceramic surfaces with a glaze of low-fusing porcelain

  8. Influence of glazed zirconia on dual-cure luting agent bond strength.

    PubMed

    Valentino, T A; Borges, G A; Borges, L H; Platt, J A; Correr-Sobrinho, L

    2012-01-01

    The current study evaluated the influence of a novel surface treatment that uses a low-fusing porcelain glaze for promoting a bond between zirconia-based ceramic and a dual-cure resin luting agent. Bond strengths were compared with those from airborne particle abrasion, hydrofluoric acid etching, and silanization-treated surfaces. Twenty-four yttrium-stabilized tetragonal zirconia (Cercon Smart Ceramics, Degudent, Hanau, Germany) discs were fabricated and received eight surface treatments: group 1: 110 μm aluminum oxide air-borne particle abrasion; group 2: 110 μm aluminum oxide airborne particle abrasion and silane; group 3: 50 μm aluminum oxide airborne particle abrasion; group 4: 50 pm aluminum oxide airborne particle abrasion and silane; group 5: glaze and hydrofluoric acid;group 6: glaze, hydrofluoric acid, and silane;group 7: glaze and 50 pm aluminum oxide airborne particle abrasion; and group 8: glaze,50 pm aluminum oxide airborne particle abrasion and silane. After treatment, Enforce resin cement (Dentsply, Caulk, Milford, DE, USA) was used to fill an iris cut from microbore Tygontubing that was put on the ceramic surface to create 30 cylinders of resin cement in each treatment group (n=30). Micro shear bond test-ing was performed at a cross head speed of 0.5mm/min. One-way analysis of variance, and multiple comparisons were made using Tukey's test (p<0.5). The bond strength was affected only by surface treatments other than silanization. The groups that utilized the low-fusing porcelain glaze with airborne particle abrasion or hydrofluoric acid showed bond strength values statistically superior to groups that utilized conventional airborne particle abrasion treatments with 50 or 110 pm aluminum oxide (p<0.001). The treatment that utilized low-fusing porcelain glaze and hydrofluoric acid showed bond strength values statistically superior to remaining groups (p<0.001). Treatment of zirconia ceramic surfaces with a glaze of low-fusing porcelain

  9. 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.

  10. 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. PMID:26186089

  11. In vitro mutagenicity testing. II. Silastic 386 Foam Elastomer, Irganox 1010, mixture of Sylgard 184 with Encapsulating Resin and Curing Agent, and dimethylbenzanthracene. [Ames test

    SciTech Connect

    Wang, S.Y.; Smith, D.M.

    1980-02-01

    Four materials, Silastic 386 Foam Elastomer, Irganox 1010, Sylgard 184 with Encapsulating Resin and Curing Agent, and 7,12-dimethylbenzanthracene (DMBA), were tested for in vitro mutagenicity by the Ames Salmonella assay method. Silastic 386 Foam Elastomer, Irganox 1010, and Sylgard 184 Encapsulating Resin with Curing Agent were not mutagenic; the mutagenicity of DMBA was corroborated.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. Effect of curing agent polarity on water absorption and free volume in epoxy resin studied by PALS

    NASA Astrophysics Data System (ADS)

    Wang, Junjun; Gong, Jing; Gong, Zhenli; Yan, Xiaoli; Wang, Bo; Wu, Qili; Li, Shanjun

    2010-07-01

    Microstructure and water absorption were systematically studied by positron annihilation lifetime spectroscopy (PALS), gravimetric measurements and Differential Scanning Calorimetry (DSC) for epoxy resins DER331 (E51) cured with three different kinds of amine curing agents DDS, DDM and MOCA. Experimental results indicated that the water absorption as a function of immersed time could be well fitted to Fick's second law. Based on the gravimetric measurement, we found that the equilibrium water sorption M∞ and the diffusion coefficients D of the epoxy resins have an order: E51-DDS > E51-DDM > E51-MOCA, which indicated that the curing agent plays an important role in determining the content of the water absorbed. Positron experimental results showed that the o-Ps lifetime dramatically decreased with the immersed time from 0 to 6 h, which suggested that water molecules were filled into free-volume holes and the interaction between the water-polymer decreased the mobility of molecular chains. In order to deeply discern the influence of water absorption upon the free volume, the continuous lifetime analysis, i.e. the maximum entropy lifetime method (MELT) was employed to obtain the distributions of the ortho-positronium (o-Ps) lifetime and the of the free-volume holes. From MELT analyses, we found the existences of two the long-lived components ( τ3 and τ4), which indicated that two kinds of different o-Ps states exist. The shorter long-lived component ( τ3) is related to the segmental packing density in local ordered region. Compared to dry sample, two peaks of the o-Ps lifetime and the free-volume hole in the wet samples all drift to low values, especially, this drifts is more marked for the water sorption occurring at higher temperature 75 °C. This fact suggested that when the epoxy resin is in the glassy state, the interaction between the water and matrix restricts the motion of segmental chains and prevents from the free-volume hole swelling.

  19. The molecular mechanism of Hsp100 chaperone inhibition by the prion curing agent guanidinium chloride.

    PubMed

    Zeymer, Cathleen; Werbeck, Nicolas D; Schlichting, Ilme; Reinstein, Jochen

    2013-03-01

    The Hsp100 chaperones ClpB and Hsp104 utilize the energy from ATP hydrolysis to reactivate aggregated proteins in concert with the DnaK/Hsp70 chaperone system, thereby playing an important role in protein quality control. They belong to the family of AAA+ proteins (ATPases associated with various cellular activities), possess two nucleotide binding domains per monomer (NBD1 and NBD2), and oligomerize into hexameric ring complexes. Furthermore, Hsp104 is involved in yeast prion propagation and inheritance. It is well established that low concentrations of guanidinium chloride (GdmCl) inhibit the ATPase activity of Hsp104, leading to so called "prion curing," the loss of prion-related phenotypes. Here, we present mechanistic details about the Hsp100 chaperone inhibition by GdmCl using the Hsp104 homolog ClpB from Thermus thermophilus. Initially, we demonstrate that NBD1 of ClpB, which was previously considered inactive as a separately expressed construct, is a fully active ATPase on its own. Next, we show that only NBD1, but not NBD2, is affected by GdmCl. We present a crystal structure of ClpB NBD1 in complex with GdmCl and ADP, showing that the Gdm(+) ion binds specifically to the active site of NBD1. A conserved essential glutamate residue is involved in this interaction. Additionally, Gdm(+) interacts directly with the nucleotide, thereby increasing the nucleotide binding affinity of NBD1. We propose that both the interference with the essential glutamate and the modulation of nucleotide binding properties in NBD1 is responsible for the GdmCl-specific inhibition of Hsp100 chaperones. PMID:23341453

  20. 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

  1. 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.

  2. 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.

  3. Acidic gas capture by diamines

    SciTech Connect

    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.

  4. Diamines and polyimides containing pendent ethynyl groups

    NASA Technical Reports Server (NTRS)

    Hergenrother, Paul M. (Inventor); Jensen, Brian J. (Inventor)

    1994-01-01

    Diamines containing pendent ethynyl and substituted ethynyl groups are synthesized. These diamines are reacted with dianhydrides to form polyamide acids, which are chemically or thermally cyclodehydrated to form polyimides and copolyimides with pendent ethynyl groups. Upon heating, the pendent ethynyl groups react to form crosslinked resins that are useful as adhesives, composite matrices, coatings, moldings, and films.

  5. 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.

  6. 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.

  7. 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.

  8. 2015 Philip S. Portoghese Medicinal Chemistry Lectureship. Curing Hepatitis C Virus Infection with Direct-Acting Antiviral Agents: The Arc of a Medicinal Chemistry Triumph.

    PubMed

    Meanwell, Nicholas A

    2016-08-25

    The development of direct-acting antiviral agents that can cure a chronic hepatitis C virus (HCV) infection after 8-12 weeks of daily, well-tolerated therapy has revolutionized the treatment of this insidious disease. In this article, three of Bristol-Myers Squibb's HCV programs are summarized, each of which produced a clinical candidate: the NS3 protease inhibitor asunaprevir (64), marketed as Sunvepra, the NS5A replication complex inhibitor daclatasvir (117), marketed as Daklinza, and the allosteric NS5B polymerase inhibitor beclabuvir (142), which is in late stage clinical studies. A clinical study with 64 and 117 established for the first time that a chronic HCV infection could be cured by treatment with direct-acting antiviral agents alone in the absence of interferon. The development of small molecule HCV therapeutics, designed by medicinal chemists, has been hailed as "the arc of a medical triumph" but may equally well be described as "the arc of a medicinal chemistry triumph". PMID:27501244

  9. Effect of crosslinking agent functionality and curing beam intensity on the phase separation kinetics of a photopolymerizing PDLC

    NASA Astrophysics Data System (ADS)

    Crawford, Nathan; Dadmun, Mark

    2004-03-01

    Polymer dispersed liquid crystals (PDLC's) are used to construct a variety of electro-optical devices, including privacy windows and holographic diffraction gratings. The final morphology of a given PDLC device depends not only on the initial syrup composition but also the polymerization and phase separation rate. In this work we report time-resolved light scattering results that monitor the phase separation kinetics of PDLC syrups undergoing photo-polymerization. Both the intensity of the curing beam and the composition of the syrups were allowed to vary. The presence of an intensity maximum at a given wave vector, q, during the early stages of polymerization appear to support spinodal decomposition (SD) as the phase separation mechanism. This process is analyzed to provide quantification of the interphase periodic distance and the mobility of the components in this process.

  10. The effect of microwave processing and use of antimicrobial agent on porosity of conventional heat cured denture base resin: An in vitro study

    PubMed Central

    Kartika, U. K.; Agrawal, Benaiffer; Yadav, Naveen S.; Singh, Praval Pratap; Rahangdale, Tripty

    2015-01-01

    Statement of Problem: The occurrence porosity in polymethyl methacrylate, the most commonly used denture base material is a problem. The occurrence of oral candidiasis and other infections has also been reported in denture users. Purpose: The aim of this study was to evaluate the effect of addition of an antimicrobial agent, silver zeolite on the porosity of denture base resin, which will be an effective tool in the prevention of oral candidiasis among denture wearers. This study also aims to analyze the effect of polymerization technique on porosity in zeolite incorporated dentures to develop a denture base resin which will be easy to process with optimal mechanical and antimicrobial properties. Materials and Methods: Eighty rectangular resin specimens (65 mm × 40 mm × 5 mm) were divided into one control group (A) and three experimental groups (B – Microwave cured denture base resin specimens, C – Conventionally cured denture base resin incorporated with antibacterial zeolites, D – Microwave cured denture base resin incorporated with antibacterial zeolites) porosity was calculated by measurement of the specimen volume before and after its immersion in water. Data were analyzed using one-way analysis of variance. Results: The mean values of the percent mean porosity were: A = 0.9555%, B = 0.9590%, C = 0.9630%, D = 0.9695%. No significant differences were found in mean porosity among the groups evaluated. Conclusion: Within the limitations of this study, it could be concluded that the addition of zeolites did not result in significant porosity and that the use of microwave processing is a viable option for denture processing. PMID:26929522

  11. 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

  12. The effect of monomer/polymer mixing ratio, time between mixing and packing of heat cured acrylic resin denture base material and bond assisting agents on the bond strength to acrylic resin denture teeth.

    PubMed

    Alshahrani, A M; Spithourakis, S A; Juszczyk, A S; Radford, D R; Clark, R K F

    2012-09-01

    The aim of the study was to investigate the effect of varying the monomer/polymer mixing ratio, the time from mixing to packing heat cured acrylic resin and the effect of two bond assisting agents on the strength of the bond between denture base acrylic resin and acrylic resin denture teeth. Statistical differences were found in bond strength with monomer/polymer ratio and time between mixing and packing with one of the heat cured resins investigated. The benefit of using the bonding agents was not demonstrated.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. Dual cure photocatalyst systems

    SciTech Connect

    DeVoe, R.J.; Brown-Wensley, K.A.; Holmes, G.L.; Mathis, M.D.; McCormick, F.B.; Palazzotto, M.C.; Spurgeon, K.M. . Corporate Research Labs.)

    1990-01-01

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

  20. Macrocyclization of Folded Diamines in Cavitands.

    PubMed

    Shi, Qixun; Masseroni, Daniele; Rebek, Julius

    2016-08-31

    Synthetic access to water-soluble cavitands and capsules has moved recognition events from organic solvents into aqueous media. Here we report the binding and reactivity of long-chain α,ω-diamines (C11 to C18) in cavitand hosts. The containers bind the diamines in folded conformations that bury the hydrocarbon chains and expose the amino groups to the aqueous medium. Their acylation with succinic anhydride results in improved yields of monofunctionalized products. The cavitand-bound amino acid products were cyclized to the corresponding macrocyclic dilactams in D2O using water-soluble carbodiimide. Direct reaction of the folded diamines in the cavitand with activated diesters of succinic acid and glutaric acids resulted in 54-96% yields of the 17- to 25-membered dilactams. These cavitand-chaperoned reactions provided 3- to 10-fold improvements over the yields obtained in bulk solution and offer an alternative to high dilution methods. The cavitand induces unlikely conformations in flexible guests and channels their reactivity along otherwise improbable paths. PMID:27529442

  1. 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. PMID:12839751

  2. 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.

  3. Defining cure.

    PubMed

    Hilton, Paul; Robinson, Dudley

    2011-06-01

    This paper is a summary of the presentations made as Proposal 2-"Defining cure" to the 2nd Annual meeting of the ICI-Research Society, in Bristol, 16th June 2010. It reviews definitions of 'cure' and 'outcome', and considers the impact that varying definition may have on prevalence studies and cure rates. The difference between subjective and objective outcomes is considered, and the significance that these different outcomes may have for different stakeholders (e.g. clinicians, patients, carers, industry etc.) is discussed. The development of patient reported outcome measures and patient defined goals is reviewed, and consideration given to the use of composite end-points. A series of proposals are made by authors and discussants as to how currently validated outcomes should be applied, and where our future research activity in this area might be directed.

  4. 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.

  5. 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

  6. 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. 721.825 Section 721.825 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC... Substances § 721.825 Certain aromatic ether diamines. (a) Chemical substances and significant new...

  7. 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...

  8. Development of high-performance diamine-based polybenzoxazines

    NASA Astrophysics Data System (ADS)

    Allen, Douglas James

    A series of linear aliphatic diamine-based benzoxazine monomers has been synthesized and characterized. These benzoxazine monomers polymerize at elevated temperatures into transparent, crosslinked materials with an inherently flexible network structure. These aliphatic diamine-based benzoxazines are atypical in that polyfunctionality is provided by the amine portion of the benzoxazine structure, rather than by a multifunctional phenol as is more conventional utilized. The kinetics of thermally activated polymerization for this series of diamine-based benzoxazine monomers is investigated by infrared spectroscopy and reveals that the rate of polymerization is inversely proportional to the length of the aliphatic diamine chain. The monomer based on the shortest diamine, ethylene diamine, is shown by differential scanning calorimetry to polymerize by a dual-mode process with an onset temperature that is lower than ever previously seen for bisphenol-based benzoxazines. The normalized heat of polymerization for monomers based on longer diamines is largely independent of the diamine chain length. The polybenzoxazines that are prepared from the linear aliphatic diamine-based benzoxazine monomers display a high degree of inherent flexibility, with mechanical and physical properties that strongly depend on the length of the aliphatic chain. Despite the flexible nature of the diamine chains, several of the aliphatic diamine-based polybenzoxazines have high glass transition temperatures and crosslink densities that exceed those of typical bisphenol-based polybenzoxazines. By selective blocking of the ortho, para, and meta reactive sites on the aromatic ring with a series of methyl-substituted monomers, polymerization is regiospecified and the type of linkage in the network structure is controlled. The substituted benzoxazines are shown to polymerize by similar mechanisms and possess a heat of polymerization by differential scanning calorimetry that is independent of both

  9. The effect of dentin pre-treatment and heat-augmented cure on marginal gap formation of a dentin bonding agent.

    PubMed

    Zidan, O; Ross, G; Lee, I K; Gomez-Marin, O; Yeh, S H

    1991-07-01

    This study evaluated the effect of enhancing the cure of a DBA and the effect of dentin surface pre-treatment on marginal gap formation. Dentin cavities were prepared on extracted teeth and were pre-treated either with EDTA or phosphoric acid. Marginal leakage was expressed as percent length of margins with gaps. The mean percent length of margins with gaps for the chemically cured groups ranged from a maximum of 97% to a minimum of 85%. For the chemical/thermal-cured group, the mean percent length of margins with gaps was 95%, 95%, 73%, 35%, and 65%, corresponding to the following: pretreatment, no pre-treatment, EDTA, and phosphoric acid for 60, 15, or five s, respectively. SEM micrographs showed partial removal of one smear layer with EDTA and total removal of the smear layers with phosphoric acid. It is concluded that dentin pre-treatment methods have an effect on the percent length of margins with gaps when the DBA used had its cure supplemented with heat.

  10. Synthesis and evaluation of some lipidic aminoalcohols and diamines as immunomodulators.

    PubMed

    del Olmo, Esther; Plaza, Alvaro; Muro, Antonio; Martínez-Fernández, Antonio R; Nogal-Ruiz, Juan J; López-Pérez, José L; Feliciano, Arturo San

    2006-12-01

    Lymphoproliferation inhibition and cytotoxicity of a number of lipidic aminoacids, aminoalcohols and diamines were evaluated as a preliminary screening to select potential immunomodulators. The four most potent/less toxic compounds were submitted to delayed hypersensibility (DTH) assays to define the best to be evaluated further Graft-vs-Host, NO production and other immunoevaluation (CD4(+), CD45, CD8, CD11b, I-Ek, and NK cells) assays, to establish their immunomodulation potential for being further considered as auxiliary agents for vaccination against some parasitic infections. Compounds 5d, 6d, 6f, 7a, and 9a, fairly inhibited the lymphoproliferation (71.6-79.5%, at 3.2-2.4 nM), while the aminoalcohol derivative 6f and the diamine 7a gave the most promising results in the DTH assays. Diamine derivative 8b induced nitrite production on normal macrophages, whereas compounds 6f and 7a induced nitrite production on LPS pre-stimulated macrophages. These two last compounds have been selected to follow in vivo vaccination assays. PMID:17000108

  11. 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.

  12. Catalytic Diamination of Olefins via N–N Bond Activation

    PubMed Central

    2015-01-01

    Conspectus Vicinal diamines are important structural motifs present in various biologically and chemically significant molecules. Direct diamination of olefins provides an effective approach to this class of compounds. Unlike well-established oxidation processes such as epoxidation, dihydroxylation, and aminohydroxylation, direct diamination of olefins had remained a long-standing challenge and had been less well developed. In this Account, we summarize our recent studies on Pd(0)- and Cu(I)-catalyzed diaminations of olefins using di-tert-butyldiaziridinone and its related analogues as nitrogen sources via N–N bond activation. A wide variety of imidazolidinones, cyclic sulfamides, indolines, imidazolinones, and cyclic guanidines can be obtained from conjugated dienes and terminal olefins. For conjugated dienes, the diamination proceeds regioselectively at the internal double bond with the Pd(0) catalyst. Mechanistic studies show that the diamination likely involves a four-membered Pd(II) species resulting from the insertion of Pd(0) into the N–N bond of di-tert-butyldiaziridinone. Interestingly, the Cu(I)-catalyzed process occurs regioselectively at either the terminal or internal double bond depending on the reaction conditions via two mechanistically distinct pathways. The Cu(I) catalyst cleaves the N–N bond of di-tert-butyldiaziridinone to form a Cu(II) nitrogen radical and a four-membered Cu(III) species, which are likely in rapid equilibrium. The Cu(II) nitrogen radical and the four-membered Cu(III) species lead to the terminal and internal diamination, respectively. Terminal olefins are effectively C–H diaminated at the allylic and homoallylic carbons with Pd(0) as catalyst and di-tert-butyldiaziridinone as nitrogen source, likely involving a diene intermediate generated in situ from the terminal olefin via formation of a π-allyl Pd complex and subsequent β-hydride elimination. When di-tert-butylthiadiaziridine 1,1-dioxide is used as nitrogen source

  13. Oxidation of polymines by diamine oxidase from human seminal plasma.

    PubMed Central

    Hölttä, E; Pulkkinen, P; Elfving, K; Jänne, J

    1975-01-01

    1. Diamine oxidase [amine-oxygen oxidoreductase (deaminating)(pyridoxal-containing), EC 1.4.3.6] was purified from human seminal plasma more than 1,700-fold. The enzyme appeared to be homogeneous on polyacrylamide-gel electrophoresis at two different pH values. 2. The general properties of the enzyme were comparable with those described for other diamine oxidases from different mammalian sources. The molecular weight of the enzyme was calculated to be about 182,000. 3. The enzyme had highest affinity for diamines, but polyamines spermidine and spermine were also degraded at concentrations that can be considered physiological in human semen. 3. The possible degradation of spermine by diamine oxidase in human semen in vivo may give rise to the formation of cytotoxic aldehydes that conceivably can influence the motility and survival of the spermatozoa. PMID:239684

  14. Catalytic diamination of olefins via N-N bond activation.

    PubMed

    Zhu, Yingguang; Cornwall, Richard G; Du, Haifeng; Zhao, Baoguo; Shi, Yian

    2014-12-16

    CONSPECTUS: Vicinal diamines are important structural motifs present in various biologically and chemically significant molecules. Direct diamination of olefins provides an effective approach to this class of compounds. Unlike well-established oxidation processes such as epoxidation, dihydroxylation, and aminohydroxylation, direct diamination of olefins had remained a long-standing challenge and had been less well developed. In this Account, we summarize our recent studies on Pd(0)- and Cu(I)-catalyzed diaminations of olefins using di-tert-butyldiaziridinone and its related analogues as nitrogen sources via N-N bond activation. A wide variety of imidazolidinones, cyclic sulfamides, indolines, imidazolinones, and cyclic guanidines can be obtained from conjugated dienes and terminal olefins. For conjugated dienes, the diamination proceeds regioselectively at the internal double bond with the Pd(0) catalyst. Mechanistic studies show that the diamination likely involves a four-membered Pd(II) species resulting from the insertion of Pd(0) into the N-N bond of di-tert-butyldiaziridinone. Interestingly, the Cu(I)-catalyzed process occurs regioselectively at either the terminal or internal double bond depending on the reaction conditions via two mechanistically distinct pathways. The Cu(I) catalyst cleaves the N-N bond of di-tert-butyldiaziridinone to form a Cu(II) nitrogen radical and a four-membered Cu(III) species, which are likely in rapid equilibrium. The Cu(II) nitrogen radical and the four-membered Cu(III) species lead to the terminal and internal diamination, respectively. Terminal olefins are effectively C-H diaminated at the allylic and homoallylic carbons with Pd(0) as catalyst and di-tert-butyldiaziridinone as nitrogen source, likely involving a diene intermediate generated in situ from the terminal olefin via formation of a π-allyl Pd complex and subsequent β-hydride elimination. When di-tert-butylthiadiaziridine 1,1-dioxide is used as nitrogen source

  15. 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.

  16. 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

  17. Covalent IR820-PEG-diamine nanoconjugates for theranostic applications in cancer

    PubMed Central

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

    2014-01-01

    Near-infrared dyes can be used as theranostic agents in cancer management, based on their optical imaging and localized hyperthermia capabilities. However, their clinical translatability is limited by issues such as photobleaching, short circulation times, and nonspecific biodistribution. Nanoconjugate formulations of cyanine dyes, such as IR820, may be able to overcome some of these limitations. We covalently conjugated IR820 with 6 kDa polyethylene glycol (PEG)-diamine to create a nanoconjugate (IRPDcov) with potential for in vivo applications. The conjugation process resulted in nearly spherical, uniformly distributed nanoparticles of approximately 150 nm diameter and zeta potential −0.4±0.3 mV. The IRPDcov formulation retained the ability to fluoresce and to cause hyperthermia-mediated cell-growth inhibition, with enhanced internalization and significantly enhanced cytotoxic hyperthermia effects in cancer cells compared with free dye. Additionally, IRPDcov demonstrated a significantly longer (P<0.05) plasma half-life, elimination half-life, and area under the curve (AUC) value compared with IR820, indicating larger overall exposure to the theranostic agent in mice. The IRPDcov conjugate had different organ localization than did free IR820, with potential reduced accumulation in the kidneys and significantly lower (P<0.05) accumulation in the lungs. Some potential advantages of IR820-PEG-diamine nanoconjugates may include passive targeting of tumor tissue through the enhanced permeability and retention effect, prolonged circulation times resulting in increased windows for combined diagnosis and therapy, and further opportunities for functionalization, targeting, and customization. The conjugation of PEG-diamine with a near-infrared dye provides a multifunctional delivery vector whose localization can be monitored with noninvasive techniques and that may also serve for guided hyperthermia cancer treatments. PMID:25336944

  18. 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.

  19. 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.

  20. 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.

  1. 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...

  2. Diamination of phenylene dihalides catalyzed by a dicopper complex.

    PubMed

    Liao, Bei-Sih; Liu, Shiuh-Tzung

    2012-08-01

    Diamination of phenylene dihalides with aqueous ammonia to give the corresponding phenylenediamines can be achieved by using a dicopper complex [Cu(2)(bpnp)(OH)(CF(3)COO)(3)] (1) (bpnp = 2,7-bis(pyridine-2-yl)-l,8-naphthyridine) as the catalyst in the presence of Bu(4)NBr and Cs(2)CO(3) in high yields. In addition, 1,3,5-tribromobenzene was converted into benzenetriamine quantitatively under the same conditions. This method offers a new opportunity, particularly simplifying steps and increasing yields, for the preparation of aryl diamines. PMID:22808946

  3. Cu(I)-catalyzed sequential diamination and dehydrogenation of terminal olefins: a facile approach to imidazolinones.

    PubMed

    Zhu, Yingguang; Shi, Yian

    2014-10-20

    Diamination of olefins presents a powerful strategy to access vicinal diamines. During the last decade, metal-catalyzed diamination of olefins has received considerable attention. This study describes an efficient sequential diamination and dehydrogenation process of terminal olefins with CuBr as catalyst and di-tert-butyldiaziridinone as nitrogen source, providing a facile and viable approach to a variety of imidazolin-2-ones, which are important structural motifs present in various biologically active molecules. PMID:25213994

  4. 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...

  5. 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...

  6. 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...

  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, 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...

  9. Final amended report of the safety assessment of toluene-2,5-diamine, toluene-2,5-diamine sulfate, and toluene-3,4-diamine as used in cosmetics.

    PubMed

    Burnett, Christina L; Bergfeld, Wilma F; Belsito, Donald V; Klaassen, Curtis D; Marks, James G; Shank, Ronald C; Slaga, Thomas J; Snyder, Paul W; Alan Andersen, F

    2010-05-01

    Toluene-2,5-diamine, toluene-2,5-diamine sulfate, and toluene-3,4-diamine are diaminotoluenes used as colorants in permanent hair dyes and tints. Toluene-2,5-diamine is used in 79 products at concentrations up to 3%; toluene-2,5-diamine sulfate is used in 168 products at concentrations up to 4%. Toluene-3,4-diamine does not appear to be in current use. Previously, the Cosmetic Ingredient Review Expert Panel determined that all 3 ingredients were safe for use as hair dyes. New data suggest that differences in toxicity, especially with respect to carcinogenicity, may exist as a function of placement of amine groups around the benzene ring. The Expert Panel concluded that toluene-2,5-diamine and toluene-2,5-diamine sulfate and are safe as hair dye ingredients in the present practices of use and concentrations but that there are insufficient data supporting the safety of toluene-3,4-diamine. PMID:20448268

  10. 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.

  11. 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)

  12. 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. ...

  13. 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.

  14. Pig kidney diamine oxidase. A new method of purification.

    PubMed

    Floris, G; Fadda, M B

    1979-07-15

    Diamine oxidase has been purified from pig kidney by a new method to rapidly obtain larger amounts of pure enzyme with a good yield. The enzyme obtained gives only one band in SDS gel electrophoresis. The specific activity and the absorption spectra were identical to those of already preparations homogeneous reported by different methods of purification. PMID:121960

  15. 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

  16. 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

  17. Ethylene diamine-assisted synthesis of iron oxide nanoparticles in high-boiling polyolys.

    PubMed

    Arndt, Darius; Zielasek, Volkmar; Dreher, Wolfgang; Bäumer, Marcus

    2014-03-01

    The decomposition of iron(III) acetylacetonate in high-boiling polyols such as diethylene glycole is an efficient way to produce water-soluble iron oxide nanoparticles (IONPs) with small sizes. We present an extension of this method by introducing ethylene diamine (EDA) or diethylene triamine (DTA) as a structure-directing agent and adding polyvinylpyrrolidone (PVP) as a stabilizing agent. The synthesis was studied with respect to effects of the chain length of the polyol used as solvent, the chain length of the structure-directing agent, the presence of PVP, the heating rate, and the nature of the precursor. By varying these parameters, we were able to show, that probably an interplay of the structure-directing agent and the polyol plays an important role for the stabilization and growth of the different facets of the IONP crystal. The chain length of the polyol used as solvent alters the influence of EDA or DTA as stabilizer of {111} facets, leading to IONPs with spherical, tetrahedral, or nanoplate morphology and mean diameters ranging from 4 nm up to 25 nm. PVP in the reaction medium narrows down particle size and shape distributions and promotes the formation of very stable, water-based colloidal solutions. The saturation magnetization of the particles was determined by a superconducting quantum interference device (SQUID) and their ability to act as a T2-contrast agent was tested by magnetic resonance imaging (MRI).

  18. Effects of the presence of the curing agent sodium nitrite, used in the production of fermented sausages, on bacteriocin production by Weissella paramesenteroides DX grown in meat simulation medium.

    PubMed

    Papagianni, M; Sergelidis, D

    2013-06-10

    Weissellin A is a listericidal bacteriocin produced by the sausage-isolated strain of Weissella paramesenteroides DX. The response of the strain to various concentrations of the added curing agent NaNO2 (0.0025, 0.005 and 0.01g/L) was evaluated in bioreactor fermentations using a meat simulation medium. The presence of nitrite suppressed bacteriocin production - the effect being more pronounced with increasing concentrations. Weissellin A was produced as a growth-associated metabolite in the absence of nitrite or its presence in the low concentration of 0.005g/L under aerobic conditions. The suppressive effect of nitrite was apparent under conditions supporting increased specific production rates, e.g. 50% and 100% dissolved oxygen tension, but no effect was observed under anaerobic conditions. As the latter prevail in the microenvironment of fermented meat products, the absence of any influence of nitrite on bacteriocin production is an important finding that enlightens the role of this species of lactic acid bacteria in its common substrates.

  19. 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.

  20. Diamine Functionalized Cubic Mesoporous Silica for Ibuprofen Controlled Delivery.

    PubMed

    Sivaguru, J; Selvaraj, M; Ravi, S; Park, H; Song, C W; Chun, H H; Ha, C-S

    2015-07-01

    A diamine functionalized cubic mesostructured KIT-6 (N-KIT-6) has been prepared by post-synthetic method using calcined mesoporous KIT-6 with a diamine source, i.e., N-'[3-(tri methoxysilyl)- propyl]'ethylenediamine. The KIT-6 mesoporous silica used for N-KIT-6 was synthesized under weak acidic hydrothermal method using bitemplates, viz., Pluronic P123 and 1-butanol. The synthesized mesoporous materials, KIT-6 and N-KIT-6, have been characterized by the relevant instrumental techniques such as SAXS, N2 sorption isotherm, FT-IR, SEM, TEM and TGA to prove the standard mesoporous materials with the identification of diamine groups. The characterized mesoporous materials, KIT-6 and N-KIT-6, have been extensively used in the potential application of controlled drug delivery, where ibuprofen (IBU) employed as a model drug. The rate of IBU adsorption and release was monitored by UV vis-spectrometer. On the basis of the experimental results of controlled drug delivery system, the results of IBU adsorption and releasing rate in N-KIT-6 are higher than those of KIT-6 because of the higher hydrophobic nature as well as rich basic sites on the surface of inner pore wall silica.

  1. Morphology and structure of microcapsules prepared by interfacial polycondensation of methylene bis(phenyl isocyanate) with hexamethylene diamine.

    PubMed

    Jabbari, E

    2001-01-01

    Polyurea microcapsules containing 2- chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl) acetamide as the active agent were prepared by the method of interfacial polycondensation with methylene bis(phenyl isocyanate) the multifunctional isocyanatae, hexamethylene diamine as the diamine, and anionic (SLS) as the emulsifying sodium lignin liinin the agent. The internal structure and morphology of the microcapsules were examined with transmission electron microscopy. The microcapsules had a micro-reservoir structure in which the wall extended well into the core and the active agent was accomodated by the micro-reservoirs, distributed uniformly throughout the entire volume of a microcapsule. Based on the observed morphology, permeability of the water soluble monomer in the polyurea film and its solubility in the oil phase have a significant effect on the morphology and microstructure of the microcapsules. The multivalent salt, calcium chloride, plays a significant role in stabilizing the microcapsule structure, by interacting with the anionic surfactant SLS, and physically crosslinks the SLS chains, by interacting with the negatively charged carboxylic and phenolic groups, with subsequent phase separation of the physically crosslinked chains to form a concentrated gel phase. This gel phase encompasses the microcapsule, increases the stability, and modifies its release behaviour.

  2. 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.

  3. 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. PMID:24720632

  4. 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.

  5. Fiber-optic epoxy composite cure sensor. I. Dependence of refractive index of an autocatalytic reaction epoxy system at 850 nm on temperature and extent of cure

    NASA Astrophysics Data System (ADS)

    Lam, Kai-Yuen; Afromowitz, Martin A.

    1995-09-01

    We discuss the behavior of the refractive index of a typical epoxy-aromatic diamine system. Near 850 nm the index of refraction is found to be largely controlled by the density of the epoxy. Models are derived to describe its dependence on temperature and extent of cure. Within the range of temperatures studied, the refractive index decreases linearly with increasing temperature. In addition, as the epoxy is cured, the refractive index increases linearly with conversion to the gel point. >From then on, shrinkage in the volume of the epoxy is restricted by local viscosity. Therefore the linear relationship between the refractive index and the extent of cure does not hold beyond the gel point.

  6. 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).

  7. 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. PMID:27128188

  8. Pea (Pisum sativum) diamine oxidase contains pyrroloquinoline quinone as a cofactor.

    PubMed

    Glatz, Z; Kovár, J; Macholán, L; Pec, P

    1987-03-01

    Diamine oxidase was prepared from pea (Pisum sativum) seedlings by a new purification procedure involving two h.p.l.c. steps. We studied the optical and electrochemical properties of the homogeneous enzyme and also analysed the hydrolysed protein by several methods. The data presented here suggest that the carbonyl cofactor of diamine oxidase is firmly bound pyrroloquinoline quinone.

  9. Curing of liquid crystalline epoxy resins with a biguanide

    NASA Astrophysics Data System (ADS)

    Szczepaniak, Barbara; Penczek, Piotr; Frisch, Kurt C.; Rejdych, Jerzy

    1998-01-01

    This work extends the authors' investigation son liquid crystalline epoxy resins prepared from diglycidyl ether of 4,4'-dihydroxybiphenyl and aliphatic dicarboxylic compounds or difunctional aromatic compounds. Syntheses and properties of these liquid crystalline epoxy resins are described elsewhere. In this paper a study on the curing reaction of two from the above mentioned liquid crystalline epoxy resins is presented. Ortho-tolylbiguanide was applied as the curing agent. The curing reactions were investigated by differential scanning calorimetry, microscopic observations and IR spectroscopy. Depending upon the temperature program of curing, it was possible to obtain polymeric networks with liquid crystalline order.

  10. Make this new C/sub 10/ diamine

    SciTech Connect

    Drake, C.A.; Campbell, R.W.; Hill, H.W.; Marwil, S.T.; Vanderveen, J.W.

    1982-11-01

    A new technology has been developed which permits production of C/sub 10/ diamines from acrylonitrile and isobutylene. In this work, methods were developed to conduct an ''ene'' type reaction using a suitable solvent in a continuous stirred tank reactor. The solvent used was a mixture of unsaturated C/sub 7/ nitriles, produced as an intermediate in the reaction. Technical problems solved in this area which materially contributed to the success of this project include: (1) means to minimize reactor fouling and (2) means to prevent isomerization of the solvent. Unsaturated C/sub 10/ dinitriles produced in the first half of the process were hydrogenated to saturated C/sub 10/ diamines using a suitable catalyst in a trickle bed reactor. Use of NH/sub 3/ in the hydrogenation reactor prevented formation of secondary and tertiary amines. Alkylation products in the hydrogenation reactor were avoided by selection and use of suitable solvents. Condensation of MND with terephthalic acid produced a polyamide (designated as MND-T) having a glass transition temperature above the boiling point of water. Fabrics prepared from MND-T fiber showed outstanding performance when compared with nylon, polyester and Quiana fabrics. MND-T polyamide was also evaluated as an engineering plastic and compared with other nylon resins. Processing data and properties of MND-T showed it to be a hard, strong, tough, injection moldable polyamide with better moisture and chemical resistance and higher heat deflection temperature than nylon 6-6 or 6-12.

  11. 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

  12. 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.

  13. 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

    ... 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...

  14. 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

    ... 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...

  15. 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...

  16. 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

    ... 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. 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...

  18. Mono- and polynuclear Co(II) silanethiolates with aliphatic diamines

    NASA Astrophysics Data System (ADS)

    Pladzyk, Agnieszka; Baranowska, Katarzyna

    2014-01-01

    Four Co(II) complexes, [Co{SSi(OtBu)3}2(dmpda)] 1, [Co{SSi(OtBu)3}2(bda)2]n2 [Co{SSi(OtBu)3}2(pda)2]n3 and [Co{SSi(OtBu)3}2(hda)2]n4 [dmpda = 3-(dimethylamino)-1-propylamine; bda = 1.4-butanediamine; pda = 1.5-pentanediamine; had = 1.6-hexanediamine] have been synthesized and characterized using X-ray diffraction. Complex 1 is mononuclear and contains Co(II) coordinated by dmpda molecule in chelating mode, whereas compounds 3 and 4 are one-dimensional polymers with pda and hda diamines as bridges between the metallic centers respectively. In all complexes tri-tert-butoxysilanethiolate residue acts as terminal S-donor ligand. Full characterization of obtained compounds 1-4 was additionally carried out with the use of IR and UV-vis spectroscopy, elemental and thermal analysis.

  19. An indolocarbazole dimer as a new stereodynamic probe for chiral 1,2-diamines.

    PubMed

    Jeon, Hae-Geun; Kim, Min Jun; Jeong, Kyu-Sung

    2014-08-01

    An indolocarbazole dimer that contains aldehyde groups at both ends was prepared by connecting two monomeric units through a rod-like 1,4-butadiynyl spacer. Upon mixing with chiral 1,2-diamines at room temperature, the dimer was in situ converted to the corresponding cyclic diimines in the presence of tetrabutylammonium acetate as a template. The resulting diimines fold to helical conformations of right-handed (P) or left-handed (M) orientations, depending on the absolute stereochemistries of chiral 1,2-diamines. The patterns and intensities of the CD spectra can be used to determine the absolute configurations and enantiomeric excesses of chiral 1,2-diamines.

  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. Curing Metastatic Breast Cancer.

    PubMed

    Sledge, George W

    2016-01-01

    Metastatic breast cancer is generally considered incurable, and this colors doctor-patient interactions for patients with metastatic disease. Although true for most patients, there appear to be important exceptions, instances where long-term disease-free survival occurs. Although these instances are few in number, they suggest the possibility of cure. How will we move toward cure for a much larger population of patients with metastatic disease? This article outlines a potential research agenda that might move us toward that distant goal. PMID:26759458

  2. Recombinant human diamine oxidase activity is not inhibited by ethanol, acetaldehyde, disulfiram, diethyldithiocarbamate or cyanamide.

    PubMed

    Bartko, Johann; Gludovacz, Elisabeth; Petroczi, Karin; Borth, Nicole; Jilma, Bernd; Boehm, Thomas

    2016-08-01

    Human diamine oxidase (hDAO, EC 1.4.3.22) is the key enzyme in the degradation of extracellular histamine. Consumption of alcohol is a known trigger of mast cell degranulation in patients with mast cell activation syndrome. Ethanol may also interfere with enzymatic histamine degradation, but reports on the effects on DAO activity are controversial. There are also conflicting reports whether disulfiram, an FDA-approved agent in the treatment of alcohol dependence, inhibits DAO. We therefore investigated the inhibitory potential of ethanol and disulfiram and their metabolites on recombinant human DAO (rhDAO) in three different assay systems. Relevant concentrations of ethanol, acetaldehyde, and acetate did not inhibit rhDAO activity in an in vitro assay system using horseradish peroxidase (HRP) -mediated luminol oxidation. The aldehyde dehydrogenase (ALDH; EC 1.2.1.3) inhibitors cyanamide and its dimer dicyanamide also had no effect on DAO activity. In one assay system, the irreversible ALDH inhibitor disulfiram and its main metabolite diethyldithiocarbamate seemed to inhibit DAO activity. However, the decreased product formation was not due to a direct block of DAO activity but resulted from inhibition of peroxidase employed in the coupled system. Our in vitro data do not support a direct blocking effect of ethanol, disulfiram, and their metabolites on DAO activity in vivo. PMID:27401969

  3. Studies on microleakage associated with visible light cured dental composites.

    PubMed

    Krishnan, V K; Bindhu, D B; Manjusha, K

    1996-04-01

    The objective of this investigation was twofold: 1) to determine the extent of microleakage associated with two visible light cured dental composites, one of which is an indigenously developed light cure composite (chitra light cure system) compared with a commercially available control material (Prisma APH light cure system), and 2) to study the effect of using bonding agents upon the above phenomena. The bonding agents used along with the above composites during restoration were chitra bonding agent system containing chitra primer/chitra resin and a control (Probond) which was purchased commercially. A comparison of microleakage in freshly restored human premolar teeth by silver nitrate staining technique was made during the above study. Cavities were restored with both composites with and without bonding agents, stored in 50 percent silver nitrate, and sections were cut after developing. The microtomed sections were observed under the optical light microscope and scanning electron microscope. Results indicate that bonding agents are mandatory for effective bonding at the tooth/resin interface and subsequent reduction in marginal leakage. Chitra bonding agent showed excellent adhesive bonding characteristics at the dentine/composite interface with minimal marginal leakage compared to the control bonding system. The chitra light cure composite material also showed lower shrinkage characteristics compared to Prisma APH composite. PMID:8859406

  4. Curing Children's Cancer

    MedlinePlus

    ... ALL is a cancer of the white blood cells, which fight infection. It is the most common cancer in children, representing 23 percent of all cancers among those 15 or younger. Forty years ago, ALL was incurable. Today, in the United States, its cure rate is a major success story—as many ...

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

    PubMed

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

    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

  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. Which therapeutic strategy will achieve a cure for HIV-1?

    PubMed

    Cillo, Anthony R; Mellors, John W

    2016-06-01

    Strategies to achieve a cure for HIV-1 infection can be broadly classified into three categories: eradication cure (elimination of all viral reservoirs), functional cure (immune control without reservoir eradication), or a hybrid cure (reservoir reduction with improved immune control). The many HIV-1 cure strategies being investigated include modification of host cells to resist HIV-1, engineered T cells to eliminate HIV-infected cells, broadly HIV-1 neutralizing monoclonal antibodies, and therapeutic vaccination, but the 'kick and kill' strategy to expose latent HIV-1 with latency reversing agents (LRAs) and kill the exposed cells through immune effector functions is currently the most actively pursued. It is unknown, however, whether LRAs can deplete viral reservoirs in vivo or whether current LRAs are sufficiently safe for clinical use.

  8. Dielectric Monitoring of Curing Composites

    NASA Technical Reports Server (NTRS)

    Goldberg, Benjamin E.; Semmel, Marie L.

    1987-01-01

    Report describes preliminary attempts at dielectric monitoring of curing of graphite/epoxy and carbon/phenolic composites. Objective is to develop dielectric monitoring for optimizing curing process and reduce incidence of failures of produced composite structures.

  9. 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. PMID:21543462

  10. 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.

  11. Hepatitis C, stigma and cure.

    PubMed

    Marinho, Rui Tato; Barreira, David Pires

    2013-10-28

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

  12. Soluble monometallic salen complexes derived from O-functionalised diamines as metalloligands for the synthesis of heterobimetallic complexes.

    PubMed

    Schley, Michael; Fritzsche, Sebastian; Lönnecke, Peter; Hey-Hawkins, Evamarie

    2010-05-01

    O-Functionalised salen ligands were employed as bridging ligands in the synthesis of homo- and heterometallic salen complexes with early and late transition metals (H(2)salen: N,N'-bis(salicylidene)ethylenediamine, systematic name: 2,2'-{ethane-1,2-diylbis(nitrilomethylidine)}diphenol). A new type of O-functionalised salen ligand was synthesised, which contains alkyl groups to enhance the solubility in organic solvents as well as carboxyl groups to allow introduction of an early transition metal. Two new salen ligands derived from O-functionalised diamines were synthesised from 3,5-di-tert-butylsalicylaldehyde (bsal) and 3,4-diaminobenzoic acid (4cpn) or (R)-2,3-diaminopropionic acid (cen). By using the aryl diamines, a conjugated backbone is obtained, and the alkyl diamines can be used to introduce a chiral centre. The salen ligand derived from 3,4-diaminobenzoic acid was accessible only via a zinc(II)-mediated template reaction. Monometallic salen complexes could be obtained by template synthesis with nickel(II) and copper(II). The analogous chromium(III), manganese(III) and molybdenum(IV) salen complexes were synthesised directly from the salen ligands. The crystal structures of the molybdenum(IV) salen complex and a decomposition product thereof gave insight into the stability of this compound. Starting from (R)-2,3-diaminopropionic acid the corresponding nickel(II), chromium(III), manganese(III) and molybdenum(IV) salen complexes were obtained. Reactions of the conjugated nickel(II) salen complex with metallocene derivatives resulted in the formation of soluble di- and trinuclear heterobimetallic complexes, depending on the stoichiometry used. The compounds were characterised by NMR, IR and EPR spectroscopy, mass spectrometry and, for selected complexes, by X-ray crystallography. For selected mono- and bimetallic salen complexes the catalytic activity in the epoxidation of styrene was tested under different reaction conditions and with different oxidising

  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. 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

  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. Non-Enzymatic Glucose Sensor Based on 3D Graphene Oxide Hydrogel Crosslinked by Various Diamines.

    PubMed

    Hoa, Le Thuy; Hur, Seung Hyun

    2015-11-01

    The non-enzymatic glucose sensor was fabricated by well-controlled and chemically crosslinked graphene oxide hydrogels (GOHs). By using various diamines such as ethylenediamine (EDA), p-phenylene diamine (pPDA) and o-phenylene diamine (oPDA) that have different amine to amine distance, we can control the structures of GOHs such as surface area and pore volume. The pPDA-GOH fabricated by pPDA exhibited the largest surface area and pore volume due to its longest amine to amine distance, which resulted in highest sensitivity in glucose and other monosaccharide sensing such as fructose (C6H12O6), galactose (C6H12O6) and sucrose (C12H22O11). It also showed fast and wide range glucose sensing ability in the amperometric test, and an excellent selectivity toward other interference species such as an Ascorbic acid. PMID:26726578

  17. 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.

  18. 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.

  19. Dual cure solventless coating process

    SciTech Connect

    DeVoe, R.J.; Palazzotto, M.C.; Chambers, W.L.; Brown-Wensley, K.A.; Holmes, G.L.; Keipert, S.J.; Mathis, M.D.; McCormick, F.B.; Spurgeon, K.M.; Williams, J.W.

    1992-02-01

    The objective is to determine the feasibility of using the Dual Cure Photocatalyst technology for reduction of gaseous waste emissions through the minimization of coating solvent use. This is to be accomplished by developing a photocuring technology that would allow the use of solvent free (100% solids) formulations while preserving or improving upon the performance of conventional solvent based materials. Four Dual Cure Photocatalyst systems and one conventional catalyst system were investigated for use in curing combinations of epoxies with acrylates and acrylates with polyurethane precursors (polyol/polyisocyanate mixtures). Photocatalyst screening results showed that Dual Cure Photocatalyst Systems based upon cationic organometallic compounds alone or in combination with free radical photoinitiators or oxidants provide significantly better processing performance than systems based upon conventional catalysts or neutral organometallic compounds in combination with oxidants. Mechanical testing of materials prepared with the five catalyst systems showed that: (1) Dual Cure compositions can produce materials with better properties than the component parts and (2) Compositions cured with Dual Cure Photocatalysts produce materials superior to those cured with conventional catalyst systems in a number of cases. Cost, economic and energy analyses are presented based upon laboratory scale coating and curing studies.

  20. 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

    ..., 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). (a... generically as alkenedioic acid dialkyl ester, reaction products with alkenoic acid alkyl esters and...

  1. 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

    ..., 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). (a... generically as alkenedioic acid dialkyl ester, reaction products with alkenoic acid alkyl esters and...

  2. Composite cure and shrinkage associated with high intensity curing light.

    PubMed

    Yap, Adrian U J; Wong, N Y; Siow, K S

    2003-01-01

    This study investigated the effectiveness of cure and post-gel shrinkage of three visible light-cured composite resins (In Ten-S [IT], Ivoclar Vivadent; Z100 [ZO], 3M-ESPE; Tetric Ceram [TC], Ivoclar Vivadent) when polymerized with a very high intensity (1296 +/- 2 mW/cm2) halogen light (Astralis 10, Ivoclar Vivadent) for 10 seconds. Irradiation with a conventional (494 +/- 3 mW/cm2) halogen light (Spectrum, Dentsply) for 40 seconds was used for comparison. The effectiveness of cure was assessed by computing the hardness gradient between the top and bottom surfaces of 2-mm composite specimens after curing. A strain-monitoring device was used to measure the linear polymerization shrinkage associated with the various composites and curing lights. A sample size of five was used for both experiments. Data was analyzed using ANOVA/Scheffe's post-hoc and Independent Samples t-tests at significance level 0.05. Results showed that the effect of the curing method on the effectiveness of cure and shrinkage was material-dependent. Polymerization of IT and TC with Spectrum for 40 seconds resulted in significantly more effective cure than polymerization with Astralis for 10 seconds. Polymerization of ZO with Spectrum for 40 seconds resulted in significantly more shrinkage than polymerization with Astralis for 10 seconds. In view of the substantial time saving, using high intensity lights may be a viable method to polymerize composites.

  3. 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

  4. Synthesis and oxidation of aminoalkyl-onium compounds by pig kidney diamine oxidase

    PubMed Central

    Bardsley, W. G.; Ashford, J. S.; Hill, C. M.

    1971-01-01

    1. The preparation of a series of compounds derived from diamines by replacing one amino group by a dimethylsulphonium, isothiuronium, trimethylammonium, NN′-dimethylimidazolium or N-methylpyridinium species is described. 2. The behaviour of these compounds as substrates of pig kidney diamine oxidase is reported. All but the trimethylammonium compounds proved to be substrates. 3. Many of these compounds showed potent inhibition at high substrate concentration and this was studied. 4. On the basis of these and other observations a scheme for enzyme–substrate interaction is suggested. PMID:5001323

  5. 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.

  6. 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.

  7. Nonpost mold cure compound

    NASA Astrophysics Data System (ADS)

    Hirata, Akihiro

    1997-08-01

    The recent low price trend of electronic products has made IC manufacturing efficiency a top priority in the semiconductor industry. Post mold cure (PMC) process, which generally involves heating the packages in the oven at 175 C for 4 to 8 hours, takes up much longer time than most other assembly processes. If this PMC process can be reduced or eliminated, semiconductor makers will be rewarded with a much higher cost merit. We define the purpose of Non-PMC as 'to get high reliability with suitable physical and electrical properties without PMC'. We compared carious properties of molding compound before and after PMC. We found that curing reaction has almost complete through DSC and C-NMR measurement, but several properties have not stabilized yet, and that not all properties after PMC were better than before PMC. We developed new grade of molding compound considering these facts. And we found that main factors to accomplish non-PMC compound are curability and flowability, and more, increasing of fundamental properties. To accomplish non-PMC, at first, molding compound need to have very high curability. Generally speaking, too high curability causes low flowability, and causes incomplete filing, wire sweep, pad shift, and weak adhesion to inner parts of IC packages. To prevent these failures, various compound properties were studied, and we achieved in adding good flowability to very high curable molding compound. Finally, anti-popcorn property was improved by adding low moisture, high adhesion, high Tg, and high flexural strengths at high temperature. Through this study, we developed new compound grade for various package, especially large QFP using standard ECN resin.

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. 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

  14. 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.

  15. 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.

  16. Asymmetric hydrogenation of 2- and 2,3-substituted quinoxalines with chiral cationic ruthenium diamine catalysts.

    PubMed

    Qin, Jie; Chen, Fei; Ding, Ziyuan; He, Yan-Mei; Xu, Lijin; Fan, Qing-Hua

    2011-12-16

    The enantioselective hydrogenation of 2-alkyl- and 2-aryl-subsituted quinoxalines and 2,3-disubstituted quinoxalines was developed by using the cationic Ru(η(6)-cymene)(monosulfonylated diamine)(BArF) system in high yields with up to 99% ee. The counteranion was found to be critically important for the high enantioselectivity and/or diastereoselectivity. PMID:22098608

  17. 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.

  18. Accelerated dry curing of hams.

    PubMed

    Marriott, N G; Kelly, R F; Shaffer, C K; Graham, P P; Boling, J W

    1985-01-01

    Uncured pork legs from the right side of 18 carcasses were treated with a Ross Tenderizer and the left side were controls. All 36 samples were dry-cured for 40, 56 or 70 days and evaluated for appearance traits, cure penetration characteristics, microbial load, Kramer Shear force and taste attributes. The tenderization treatment had no effect (P > 0·05) on visual color or cure penetration rate, weight loss before curing, percentage moisture, nitrate level, nitrite level, total plate count, anaerobic counts, psychrotrophic counts, objective and subjective tenderness measurements or juiciness. However, the higher values of salt suggested a possible acceleration of the dry cure penetration process among the tenderized samples. Cure time had no effect (P > 0·05) on percentage moisture, percentage salt, nitrate content, nitrite content, shear force and juiciness. Results suggest a limited effect of the mechanical tenderization process on certain traits related to dry curing and that total process time should be at least 70 days if color stability during cooking is desired. PMID:22056076

  19. Towards a 'cure' for IBD.

    PubMed

    Fiocchi, Claudio

    2012-01-01

    To discuss a cure for IBD, one should first define the concept 'a cure'. If it is intended as the general restoration of health, this is already possible, as many current therapies do a good job in inducing long periods of remission in Crohn's disease, and colectomy can technically cure ulcerative colitis. If it is more strictly defined as the complete and permanent elimination of the cause, predisposing and permissive factors, reinstatement of normal microbial ecology and restoration of mucosal immune homeostasis, then a cure for IBD is out of reach, at least for now. Regardless of the definition, major strides have been made in attempting to cure IBD by addressing the key components of its pathogenesis: the environment (exposome), the genetic makeup (genome), the gut microbiota (microbiome) and the immune system (immunome). However, the isolated modulation of each component is insufficient to provide a cure, and different requirements may be needed depending on the stage of the disease and each patient subset. To achieve a cure, one key approach is currently missing: the integration of knowledge from all the pathogenic components. We continue to learn more and more about each component using traditional 'canonical' systems, which allow the accumulation of data without taking into consideration the other components. We are still not studying the 'omes' of IBD, we should be using 'omics' technologies that can generate a more global vision of IBD pathogenesis on which to base novel, multiple pathway-integrated therapies. PMID:22796811

  20. Synthesis, characterization, and reactivity of ruthenium diene/diamine complexes including catalytic hydrogenation of ketones.

    PubMed

    Morilla, M Esther; Rodríguez, Pilar; Belderrain, Tomas R; Graiff, Claudia; Tiripicchio, Antonio; Nicasio, M Carmen; Pérez, Pedro J

    2007-10-29

    Thermal reactions between [RuCl2(diene)]n (diene = 2,5-norbornadiene, nbd; 1,5-cyclooctadiene, cod) with an excess of N,N,N',N'-tetramethylethylene diamine (tmeda) afforded derivatives [RuCl2(diene)(tmeda)] (diene = nbd, 1; cod, 2) as a mixture of cis and trans isomers. When thermolysis was performed under H2 mixtures of hydride species [RuCl(H)(diene)(tmeda)] (diene = nbd, 3; cod, 4) and the bis-tmeda adduct trans-[RuCl2(tmeda)2] (5) were obtained in different ratios depending upon the reaction conditions and reaction times. Heating polymeric Ru(II) precursors in toluene in the presence of a 5-fold excess of the bulkier N,N,N',N'-tetraethylethylene diamine (teeda) resulted in a rare diamine dealkylation process with formation of trans-[RuCl2(nbd)(Et2NCH2CH2NHEt)] (6) and trans-[RuCl2(cod)(EtHNCH2CH2NHEt)] (7) in high yields. The presence of N-H functionalities in the coordinated diamine ligands of 6 and 7 was unambiguously established by single-crystal X-ray diffraction studies. The dealkylation process of the teeda ligand seems to proceed intramolecularly as shown by solution NMR studies performed with the soluble Ru(II) precursors trans-[RuCl2(amine)2(diene)] (diene = nbd, amine = morpholine, 9; diene = cod, amine = Et2NH, 10). The above complexes [RuCl2(diene)(diamine)] have been tested as precatalysts in the hydrogenation of ketones both for transfer as well as direct hydrogenation, the latter route being the most effective.

  1. Curing HIV: Moving Forward Faster.

    PubMed

    Flores, Marcella; Johnston, Rowena

    2016-02-01

    There is enormous enthusiasm in the scientific community for finding a cure for HIV. Although much remains to be discovered regarding the mechanisms of viral persistence and how it may be disrupted, some assumptions regarding the goals of a cure, applicability to target populations, and what is required of the assays we employ, may lead to missed opportunities and discoveries and hamper the discovery of a product that will safely cure tens of millions of HIV-infected people around the world. The field will benefit from an awareness and critical interrogation of assumptions that may be implicit in their scientific pursuits. PMID:26862662

  2. Measurement of the degree of cure in epoxies with ultrasonic velocity

    NASA Technical Reports Server (NTRS)

    Winfree, W. P.; Parker, F. R.

    1986-01-01

    The use of ultrasonic longitudinal velocity values to measure the degree of cure (defined for an epoxide system as the concentration of epoxide/amine bonds divided by the initial epoxide concentration) in epoxy resins is investigated. The experimental setup used to measure the changes in longitudinal velocity with time is described, together with the technique used to calculate the degree of cure from the acoustic data, using the principle of additive module. Measurements were done with diglycidyl ether of bisphenol A epoxy resin cured with an amine adduct agent. Good qualitative agreement was shown between the time dependence of the acoustically measured degree of cure and the predicted rate of reaction.

  3. Hardness measurements of silicone rubber and polyurethane rubber cured by ionizing radiation

    NASA Astrophysics Data System (ADS)

    Basfar, Ahmed Ali

    1997-12-01

    This work investigates the hardness of both silicone rubber and polyurethane rubber cured by ionizing radiation. Shore A hardness is used to characterize the subject elastomers in relation to the crosslinking process. Various formulations of both materials have been investigated in order to achieve the optimum cure conditions. A small amount of a chemical curing agent has been incorporated in some formulations in order to reduce the required dose to achieve full cure conditions. Silicone rubber improved in hardness with increasing absorbed dose, whereas hardness remained constant over a broad range of absorbed doses for polyurethane rubber.

  4. Curing Efficacy of Light Emitting Diodes of Dental Curing Units

    PubMed Central

    Mousavinasab, Seyed Mostafa; Meyers, Ian

    2009-01-01

    Background and aims The aim of the present study was to compare the efficacy of quartz tungsten halogen (QTH) and light emitting diode (LED) curing lights on polymerization of resin composite. Materials and methods A hybrid resin composite was used to prepare samples which were cured using two QTH and ten LED light curing sources. Twelve groups, each containing ten samples, were prepared using each light source. The cured depth of the resin was determined using ISO 4049 method and Vickers hardness values were determined at 1.0 mm intervals. Data was analyzed by ANOVA and Tukey test. Results Data analysis demonstrated a significant difference between light sources for depth of cure. At 1.0 mm below the surface all the tested light sources and at 2.0-mm intervals all light sources except two (Optilux 501 and LEDemetron I) and at 3.0-mm intervals only two light sources (PenCure and LEDemetron II) could produce hardness values higher than 80% of superficial layer values. Conclusion This study showed that a variety of LED light sources used in the present study are as effective as the high-intensity QTH lights in polymerization of resin composite. PMID:23230474

  5. Accelerated Hazards Mixture Cure Model

    PubMed Central

    Zhang, Jiajia; Peng, Yingwei

    2010-01-01

    We propose a new cure model for survival data with a surviving or cure fraction. The new model is a mixture cure model where the covariate effects on the proportion of cure and the distribution of the failure time of uncured patients are separately modeled. Unlike the existing mixture cure models, the new model allows covariate effects on the failure time distribution of uncured patients to be negligible at time zero and to increase as time goes by. Such a model is particularly useful in some cancer treatments when the treat effect increases gradually from zero, and the existing models usually cannot handle this situation properly. We develop a rank based semiparametric estimation method to obtain the maximum likelihood estimates of the parameters in the model. We compare it with existing models and methods via a simulation study, and apply the model to a breast cancer data set. The numerical studies show that the new model provides a useful addition to the cure model literature. PMID:19697127

  6. [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

  7. 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

  8. Modeling of complex viscosity changes in the curing of epoxy resins from near-infrared spectroscopy and multivariate regression analysis.

    PubMed

    Garrido, M; Larrechi, M S; Rius, F X

    2004-12-01

    The present study investigates the relationship between the changes in complex viscosity and near-infrared spectra. Principal component regression analysis is applied to a near-infrared data set obtained from the in situ monitoring of the curing of diglycidyl ether of bisphenol A with the diamine 4,4'-diaminodiphenylmethane. The values of complex viscosity obtained by dynamic mechanical analysis during the cure process were used as a reference. The near-infrared spectra recorded throughout the reaction, unlike the univariate data analysis at some wavelengths of the spectra, contain a sufficient amount of information to estimate the complex viscosity. The relationship found was high and the results demonstrate the quality of the fitted model. Also, a simple user-friendly procedure for applying the model, focused on the user, is shown.

  9. Direct synthesis of polyamides via catalytic dehydrogenation of diols and diamines.

    PubMed

    Zeng, Hanxiang; Guan, Zhibin

    2011-02-01

    We report a direct synthesis of polyamides via catalytic dehydrogenation of diols and diamines. A PNN pincer ruthenium complex, the Milstein catalyst, was used for this reaction and polyamides with number average molecular weight from ∼10 to 30 kDa could be obtained from a wide variety of diols and diamines bearing aliphatic or aromatic, linear or cyclic spacers. Because of the high catalytic selectivity of primary amine over secondary amine, polyamines could be conveniently incorporated into linear polyamides without tedious protection/deprotection steps. Compared with conventional condensation method, this catalytic system avoids the requirement of stoichiometric preactivation or in situ activation reagents and provides a much cleaner process with high atomic economy.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  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. The Trypanosoma cruzi Diamine Transporter Is Essential for Robust Infection of Mammalian Cells

    PubMed Central

    Hasne, Marie-Pierre; Soysa, Radika; Ullman, Buddy

    2016-01-01

    Trypanosoma cruzi is incapable of synthesizing putrescine or cadaverine de novo, and, therefore, salvage of polyamines from the host milieu is an obligatory nutritional function for the parasite. A high-affinity diamine transporter (TcPOT1) from T. cruzi has been identified previously that recognizes both putrescine and cadaverine as ligands. In order to assess the functional role of TcPOT1 in intact parasites, a Δtcpot1 null mutant was constructed by targeted gene replacement and characterized. The Δtcpot1 mutant lacked high-affinity putrescine-cadaverine transport capability but retained the capacity to transport diamines via a non-saturable, low-affinity mechanism. Transport of spermidine and arginine was not impacted by the Δtcpot1 lesion. The Δtcpot1 cell line exhibited a significant but not total defect in its ability to subsist in Vero cells, although initial infection rates were not affected by the lesion. These findings reveal that TcPOT1 is the sole high-affinity diamine permease in T. cruzi, that genetic obliteration of TcPOT1 impairs the ability of the parasite to maintain a robust infection in mammalian cells, and that a secondary low-affinity uptake mechanism for this key parasite nutrient is operative but insufficient for optimal infection. PMID:27050410

  16. Determination of Diamine Oxidase in Lentil Seedlings by Enzymic Activity and Immunoreactivity

    PubMed Central

    Federico, Rodolfo; Angelini, Riccardo; Cesta, Alberinda; Pini, Carlo

    1985-01-01

    A competitive radioimmunoassay for the quantitation of diamine oxidase (EC 1.4.3.6) from Lens culinaris is reported. Specific antibodies raised in rabbits immunized with a homogeneous preparation of the enzyme were incubated with purified 125I-enzyme and with either unlabeled diamine oxidase or plant material. Antigen-antibody complexes were isolated from the mixture by incubation with Staphylococcus protein A. The sensitivity of the test was about 5 nanograms in terms of enzyme protein. This assay was applied to the determination of the enzyme in extracts from lentil shoots grown either in the dark or in the light. Diamine oxidase activity and enzyme protein (as determined by radioimmunoassay) were measured during 7 days after germination. Both enzymic activity and enzyme protein declined slowly in the dark and rapidly in the light. These results indicate that fluctuation of the enzymic activity in this organ, both in the light and in the dark, are mediated via changes in the amount of the enzyme protein and not via the action of an inhibitor. PMID:16664402

  17. The Trypanosoma cruzi Diamine Transporter Is Essential for Robust Infection of Mammalian Cells.

    PubMed

    Hasne, Marie-Pierre; Soysa, Radika; Ullman, Buddy

    2016-01-01

    Trypanosoma cruzi is incapable of synthesizing putrescine or cadaverine de novo, and, therefore, salvage of polyamines from the host milieu is an obligatory nutritional function for the parasite. A high-affinity diamine transporter (TcPOT1) from T. cruzi has been identified previously that recognizes both putrescine and cadaverine as ligands. In order to assess the functional role of TcPOT1 in intact parasites, a Δtcpot1 null mutant was constructed by targeted gene replacement and characterized. The Δtcpot1 mutant lacked high-affinity putrescine-cadaverine transport capability but retained the capacity to transport diamines via a non-saturable, low-affinity mechanism. Transport of spermidine and arginine was not impacted by the Δtcpot1 lesion. The Δtcpot1 cell line exhibited a significant but not total defect in its ability to subsist in Vero cells, although initial infection rates were not affected by the lesion. These findings reveal that TcPOT1 is the sole high-affinity diamine permease in T. cruzi, that genetic obliteration of TcPOT1 impairs the ability of the parasite to maintain a robust infection in mammalian cells, and that a secondary low-affinity uptake mechanism for this key parasite nutrient is operative but insufficient for optimal infection.

  18. What Will It Take to Cure HIV?

    PubMed

    Ananworanich, Jintanat

    2015-01-01

    Investigational strategies to attempt HIV cure or remission include very early initiation of antiretroviral therapy to limit the latent HIV reservoir and preinfection vaccination. In the setting of viral suppression, strategies include reactivation of latently infected cells (eg, through "shock" therapy with histone deacetylase inhibitors or other agents); use of broadly neutralizing antibodies, therapeutic vaccines, immunotoxins, or other immune-based therapies to kill latently infected cells; and gene editing to induce target cell resistance (eg, by eliminating the CC chemokine receptor 5 [CCR5] coreceptor). Improved ability to detect and quantify very low levels of virus is needed. This article summarizes a presentation by Jintanat Ananworanich, MD, PhD, at the IAS-USA continuing education program held in New York, New York, in October 2014.

  19. 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

  20. Sodium nitrite: the "cure" for nitric oxide insufficiency.

    PubMed

    Parthasarathy, Deepa K; Bryan, Nathan S

    2012-11-01

    This process of "curing" food is a long practice that dates back thousands of years long before refrigeration or food safety regulations. Today food safety and mass manufacturing are dependent upon safe and effective means to cure and preserve foods including meats. Nitrite remains the most effective curing agent to prevent food spoilage and bacterial contamination. Despite decades of rigorous research on its safety and efficacy as a curing agent, it is still regarded by many as a toxic undesirable food additive. However, research within the biomedical science community has revealed enormous therapeutic benefits of nitrite that is currently being developed as novel therapies for conditions associated with nitric oxide (NO) insufficiency. Much of the same biochemistry that has been understood for decades in the meat industry has been rediscovered in human physiology. This review will highlight the fundamental biochemistry of nitrite in human physiology and highlight the risk benefit evaluation surrounding nitrite in food and meat products. Foods or diets enriched with nitrite can have profound positive health benefits.

  1. Challenging Roadblocks to Cancer Cure.

    PubMed

    Loda, Massimo

    2016-09-01

    The Pezcoller Symposium in Trento, Italy, June 2015, focused entirely on the question of why advanced cancer cure is so uncommon despite the extraordinarily rapid growth of invaluable therapeutic information. Participants were asked to define and to critically evaluate real and potential obstacles to permanent disease eradication. High-level concepts on potential road blocks to cures as well as opportunities for intervention in diverse areas of investigation ranging from genomic alterations to metabolism, microenvironment, immunity, and mechanotransduction were discussed. Provocative concepts and novel therapeutic avenues were proposed. What follows is a critical analysis of the highlights of this meeting. Cancer Res; 76(17); 4924-30. ©2016 AACR. PMID:27520451

  2. Advances in light curing adhesives

    NASA Astrophysics Data System (ADS)

    Bachmann, Andy

    2001-11-01

    This paper describes the development of a new family of light curing adhesives containing a new reactive additive previously not used in optical grade light curing adhesives are obtained with the addition of functionalized cellulositics. Outgassing as low as 10-6 grams/gram has been observed based on headspace sampling. Other additives have lowered the shrinkage rates of positioning adhesives from near 1 percent to less than 0.1 percent with fractional, percentage movements over thermal range of -40 degrees C to +200 degrees C.

  3. The viscoelasticity of curing thermosets

    SciTech Connect

    Adolf, D.; Martin, J.E.

    1990-01-01

    As a crosslinking polymer cures, dramatic changes in molecular architecture occur. These structural changes in turn affect the viscoelastic behavior of the material. At a critical extent of reaction (the gel point), the polymer undergoes a transition from a viscous liquid to an elastic solid. We have monitored the evolution of structure and viscoelasticity in an epoxy encapsulant used at Sandia, the diglycidyl ether of Bisphenol A (BADGE) cured with diethanolamine (DEA). The structure evolves according to percolation theory, and the viscoelasticity evolves according to out dynamic scaling theory for branched polymers. 7 refs., 4 figs.

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

    PubMed

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

    2004-02-01

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

  5. 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.

  6. 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.

  7. Hydrothermal synthesis, structure and thermal stability of diamine templated layered uranyl-vanadates

    SciTech Connect

    Rivenet, Murielle Vigier, Nicolas; Roussel, Pascal; Abraham, Francis

    2007-02-15

    .776(2){sup o}, 6 monoclinic, space group C2/m with a=17.440(2), b=7.1904(9), c=6.8990(8) A and {beta}=98.196(2){sup o}. - Graphical abstract: The three types of layer in layered uranyl-vanadates using diamine as a structure-directing agent.

  8. Diamine Oxidase in Cotyledons of Pisum sativum Develops as a Result of the Supply of Oxygen through the Embryonic Axis during Germination 1

    PubMed Central

    Hirasawa, Eiji

    1988-01-01

    The activity of diamine oxidase (EC 1.4.3.6.) in pea, Pisum sativum cv Alaska, cotyledons was studied. The rapid hydration caused by soaking seeds in water, the excision of the embryonic axis, and the suppression of the elongation of the embryonic axis by indoleacetic acid generate anaerobic conditions in these cotyledons that suppress diamine oxidase activity. These results show that oxygen is essential for the induction of diamine oxidase activity in pea cotyledons. During germination cotyledonary diamine oxidase develops as a result of the supply of oxygen through the embryonic axis of the intact pea seedling. PMID:16666323

  9. 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. PMID:25034122

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

    PubMed

    Poon, Chin-Kuen; Kan, Chi-Wai

    2015-05-01

    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. PMID:25659721

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

    PubMed

    Poon, Chin-Kuen; Kan, Chi-Wai

    2015-05-01

    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.

  12. 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

  13. 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 ...

  14. 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

  15. HBV cure: why, how, when?

    PubMed

    Levrero, Massimo; Testoni, Barbara; Zoulim, Fabien

    2016-06-01

    Current HBV treatments control replication and liver disease progression in the vast majority of treated patients. However, HBV patients often require lifelong therapies due to the persistence of transcriptionally active viral cccDNA mini-chromosome in the nucleus, which is not directly targeted by current antiviral therapies. A true complete cure of HBV would require clearance of intranuclear cccDNA from all infected hepatocytes. An intermediate but still relevant step forward that would allow treatment cessation would be reaching a functional cure, equivalent to resolved acute infection, with a durable HBsAg loss±anti-HBs seroconversion, undetectable serum DNA and persistence of cccDNA in a transcriptionally inactive status. Recent advances in technologies and pharmaceutical sciences, including the cloning of the mayor HBV receptor (i.e. the NTCP transporter) and the development in vitro HBV infection models, have heralded a new horizon of innovative antiviral and immune-therapeutic approaches. PMID:27447092

  16. 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

  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. 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.

  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

    2016-06-01

    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. 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.

  1. Composite cure monitoring with Bragg grating sensors

    NASA Astrophysics Data System (ADS)

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

    1998-03-01

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

  2. 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.

  3. An extended cure model and model selection.

    PubMed

    Peng, Yingwei; Xu, Jianfeng

    2012-04-01

    We propose a novel interpretation for a recently proposed Box-Cox transformation cure model, which leads to a natural extension of the cure model. Based on the extended model, we consider an important issue of model selection between the mixture cure model and the bounded cumulative hazard cure model via the likelihood ratio test, score test and Akaike's Information Criterion (AIC). Our empirical study shows that AIC is informative and both the score test and the likelihood ratio test have adequate power to differentiate between the mixture cure model and the bounded cumulative hazard cure model when the sample size is large. We apply the tests and AIC methods to leukemia and colon cancer data to examine the appropriateness of the cure models considered for them in the literature.

  4. Stereocontrolled synthesis of 1,2- and 1,3-diamine building blocks from aziridine aldehyde dimers.

    PubMed

    Liew, Sean K; He, Zhi; St Denis, Jeffrey D; Yudin, Andrei K

    2013-12-01

    Vicinal aziridine-containing diamines have been obtained with high syn-stereoselectivity from readily available aziridine aldehyde dimers in the Petasis borono-Mannich reaction. Subsequent solvent- and/or nucleophile-dependent ring-opening of the aziridine ring yields functionalized 1,2- and 1,3-diamines with high regioselectivity. The ring opening is also influenced by the substitution at the C3 position of the aziridine. A mechanistic rationale for the highly syn-selective three-component reaction is proposed.

  5. 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.

  6. Lymphatic diamine oxidase secretion stimulated by fat absorption is linked with histamine release

    PubMed Central

    Sakata, Yasuhisa; Li, Xiaoming; Zhang, Chao; Yang, Qing; Xu, Min; Wollin, Armin; Langhans, Wolfgang; Tso, Patrick

    2013-01-01

    Diamine oxidase (DAO) is abundantly expressed in mammalian small intestine catalyzing the oxidative breakdown of polyamines and histamine. The aim of this study was to determine the relationship between stimulation of intestinal diamine oxidase secretion with intestinal fat absorption and histamine release. Conscious intestinal lymph fistula rats were used. The mesenteric lymph ducts were cannulated and intraduodenal tubes were installed for the infusion of Liposyn II 20% (an intralipid emulsion). Lymphatic DAO activity and protein secretion were analyzed by radiometric assay and Western blot, respectively. Lymphatic histamine concentration was measured by ELISA. Infusion of Liposyn II (4.43 kcal/3 ml) resulted in a ∼3.5-fold increase in lymphatic DAO protein secretion and DAO activity, peaking at 1 h and lasting for 3 h. Liposyn II infusion also increased the lymphatic histamine release, a substrate for DAO. To determine the relationship of DAO release with histamine release, histamine was administered intraperitoneally (10 mg/kg) in fasting rats and resulted in a significant doubling in lymphatic DAO activity, supporting a link between histamine and DAO. In addition, ip administration of the histamine H4 receptor antagonist JNJ7777120 significantly reduced the Liposyn II-induced DAO output by 65.9%, whereas H1 (pyrilamine maleate), H2 (ranitidine), and H3 (thioperamide maleate) receptor antagonists had little effect. We conclude that DAO secretion may contribute to the catabolism of histamine released during fat absorption and this is probably mediated through the histamine H4 receptor. PMID:23413254

  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. Regulation of a high-affinity diamine transport system in Trypanosoma cruzi epimastigotes.

    PubMed Central

    Le Quesne, S A; Fairlamb, A H

    1996-01-01

    Trypanosoma cruzi epimastigotes take up exogenous [3H]putrescine and [3H]cadaverine by a rapid, high-affinity, transport system that exhibits saturable kinetics (putrescine K(m) 2.0 microM, V(max) 3.3 nmol/min per 10(8) cells; cadaverine K(m) 13.4 microM, V(max) 3.9 nmol/min per 10(8) cells). Putrescine transport is temperature dependent and requires the presence of a membrane potential and thiol groups for activity. Its activity is altered in response to extracellular putrescine levels and as the cells proceed through the growth cycle. This transporter shows high specificity for the diamines putrescine and cadaverine, but low specificity for the polyamines spermidine and spermine. The existence of rapid diamine/polyamine transport systems whose activity can be adjusted in response to the growth conditions is of particular importance, as they seem unable to synthesize their own putrescine [Hunter, Le Quesne and Fairlamb (1994) Eur. J. Biochem. 226, 1019-1027]. PMID:8687391

  9. 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.

  10. 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.

  11. 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

  12. 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

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

    2015-10-20

    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 Escherichia 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

  13. 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. PMID:26002014

  14. 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.

  15. 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.

  16. How visible light curing came into dentistry.

    PubMed

    Wilson, N H F

    2016-01-01

    The present paper details the history of the introduction of visible light curing into dentistry. This history provides an excellent example of 'out of the box', lateral thinking translation of innovative scientific technology into dentistry. Visible light curing is an important UK contribution to the recent history and current practice of dentistry, with several million visible light curing procedures being carried out globally on a daily basis.

  17. Curing rate and flowing properties of silicone rubber at injection molding

    SciTech Connect

    Yoshino, M.; Nakamura, T. )

    1992-04-01

    Generally, silicone rubbers are mold-cured after mixing the rubber and peroxide curing agent with a two-roll mill or a kneader. Typically this is done at pressures of 5 MPa to 10 MPa and at temperatures between 120 to 200 C. Compression molding, transfer molding and injection molding are common molding ways for silicone rubbers. Recently, injection molding techniques are developing rapidly that have the advantages of molding automatically with high cycle mechanisms. To reduce the molding time and to make a precision part, both the flowing and curing properties of a particular rubber compound will be important. In this article, correlations between the curing and the flowing properties of silicone rubber are investigated by using the Rheovulkameter device.

  18. 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.

  19. Ab initio study of the electrochemical polymerization mechanism of ω-diamines

    NASA Astrophysics Data System (ADS)

    Lakard, Boris; Herlem, Guillaume; Fahys, Bernard

    2001-10-01

    The anodic oxidation of liquid ω-diamine based-electrolyte leads to the passivation of the electrode surface by an insulating film as shown by using an electrochemical quartz crystal microbalance (EQCM) coupled with cyclic voltammetry (CV) technique. These films were identified by infrared-attenuated total reflectance (IR-ATR) as polymeric films: linear polyethylenimine (L-PEI) film for EDA based-electrolyte and linear propylenimine (L-PPI) for 1,3 DAP. We also performed computations of energy and thermochemical values with the quantum-chemical Onsager self-consistent reaction field (SCRF) method at the Hartree-Fock level for modeling the reaction mechanisms leading to the polymeric films.

  20. 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.

  1. Cu(I)-catalyzed diamination of conjugated dienes. Complementary regioselectivity from two distinct mechanistic pathways involving Cu(II) and Cu(III) species.

    PubMed

    Zhao, Baoguo; Peng, Xingao; Zhu, Yingguang; Ramirez, Thomas A; Cornwall, Richard G; Shi, Yian

    2011-12-28

    Conjugated dienes can be diaminated at the internal and/or terminal double bonds using Cu(I) as catalyst and N,N-di-t-butyldiaziridinone (1) as nitrogen source. The regioselectivity is highly dependent upon the choice of Cu(I) catalyst and the substituents on diene substrates. The diamination likely proceeds via two mechanistically distinct pathways. The N-N bond of N,N-di-t-butyldiaziridinone (1) is first homolytically cleaved by the Cu(I) catalyst to form four-membered Cu(III) species A and Cu(II) radical species B, which are in rapid equilibrium. The internal diamination likely proceeds in a concerted manner via Cu(III) species A, and the terminal diamination likely involves Cu(II) radical species B. Kinetic studies have shown that the diamination is first-order in N,N-di-t-butyldiaziridinone (1), zero-order in olefin, and first-order in total Cu(I) catalyst, and the cleavage of the N-N bond of 1 by the Cu(I) catalyst is the rate-determining step. The internal diamination is favored by use of CuBr without ligand and electron-rich dienes. The terminal diamination is favored when using CuCl-L and dienes with radical-stabilizing groups. PMID:22081888

  2. Cu(I)-Catalyzed Diamination of Conjugated Dienes. Complementary Regioselectivity from Two Distinct Mechanistic Pathways Involving Cu(II) and Cu(III) Species

    PubMed Central

    Zhao, Baoguo; Peng, Xingao; Zhu, Yingguang; Ramirez, Thomas A.; Cornwall, Richard G.

    2011-01-01

    Conjugated dienes can be diaminated at the internal and/or terminal double bonds using Cu(I) as catalyst and N,N-di-t-butyldiaziridinone (1) as nitrogen source. The regioselectivity is highly dependent upon the choice of Cu(I) catalyst and the substituents on diene substrates. The diamination likely proceeds via two mechanistically distinct pathways. The N-N bond of N,N-di-t-butyldiaziridinone (1) is first homolytically cleaved by the Cu(I) catalyst to form four-membered Cu(III) species A and Cu(II) radical species B, which are in rapid equilibrium. The internal diamination likely proceeds in a concerted manner via Cu(III) species A and the terminal diamination likely involves Cu(II) radical species B. Kinetic studies have shown that the diamination is first-order in N,N-di-t-butyldiaziridinone (1), zero-order in olefin, first-order in total Cu(I) catalyst, and the cleavage of the N-N bond of 1 by the Cu(I) catalyst is the rate-determining step. The internal diamination is favored by use of CuBr without ligand and electron-rich dienes. The terminal diamination is favored when using CuCl-L and dienes with radical-stabilizing groups. PMID:22081888

  3. 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. PMID:27595059

  4. 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.

  5. Selective removal of copper (II) from natural waters by nanoporous sorbents functionalized with chelating diamines

    SciTech Connect

    Chouyyok, Wilaiwan; Shin, Yongsoon; Davidson, Joseph D.; Samuels, William D.; LaFemina, Nikki H.; Rutledge, Ryan D.; Fryxell, Glen E.; Sangvanich, Thanapon; Yantasee, Wassana

    2010-04-13

    The essential trace metal copper has been identified as a pollutant of concern by the Environmental Protection Agency (EPA) because of its widespread occurrence in the environment, often being found in concentrations capable of causing problems in organisms in that ecosystem. In this work, three different nanoporous sorbents containing chelating diamine functionalities were evaluated for Cu2+ adsorption in natural waters; these sorbents are ethylenediamine functionalized self-assembled monolayers on mesoporous supports (EDA-SAMMS®, SAMMS is a registered trademark of Steward Advanced Materials), ethylenediamine functionalized activated carbon (AC-CH2-EDA), and 1,10-Phenanthroline functionalized mesoporous carbon (Phen-FMC). The pH dependence of Cu2+ sorption and the Cu2+ sorption capacities of sorbents were determined. The Cu2+ adsorption rates and metal ion selectivity of these sorbents were compared to those of commercial sorbents (Chelex-100 ion exchange resin and Darco KB-B activated carbon). All three chelating diamine sorbents showed the excellent Cu2+ removal (~ 95-99%) from river water and sea water over the pH range of 6.0-8.0. Even under acidic conditions (e.g. pH of 3), AC-CH2-EDA and Phen-FMC were able to remove approximately ~49-58% of Cu2+ in sea water. EDA-SAMMS and AC-CH2-EDA demonstrated rapid Cu2+ sorption kinetics (reaching equilibrium within 5 min) and large adsorption capacities (26 and 17 mg Cu/g sorbent, respectively) in sea water. They also showed good selectivity for Cu2+ over other metal ions (e.g. Ca2+, Fe2+, Ni2+, and Zn2+) in sea water.

  6. [Nonnius and the Spa cure].

    PubMed

    Lecomte, J; Lemli, J; Marganne, M H; Melard, M

    1996-01-01

    The 12th of July 1635, Jan van Beverwyck wrote a letter from Dordrecht to his esteemed friend Luis Nunez, in Antwerp. He asked him for indications about the cure of kidney stones of which he was suffering. He had just passed two calculi very painfully. Nunez answered on July 31. His letter summarized his own experience with this disease. In such cases, temperate diuretics and emollients are well indicated: ingestion of light decoctions of Malva and Viola, Caerefolium and Parieteria as well as Marshmallow syrup. No purge and no 'chemicals'. However, the best remedy was drinking Spa water. Usually the best way to absorb it is to come to the springs, in the Ardennes, part of the independent Principality of Liège. However, considering the horrors of the war (the Thirty Years War) endangering the country, van Beverwyck would be wise to drink imported water during 40 or 50 days, while staying home quietly, in Dordrecht. The letter points out the importance of provoked diuresis in the treatment of kidney stones. On the other hand the letter is an illustration of the continuing contacts between the United Provinces and the Spanish territories and of the commercial traffic between Antwerp, Dordrecht and Spa. The exported water was bottled from many 'pouhons'. It was acid, ferruginous, sulfurous and saturated with carbon dioxide; no pathogen germs, at least at the spring. Nunez quoted the large number of his patients cured with Spa water in Antwerp. This is an illustration of its commercial expansion even during this critical period. PMID:8848877

  7. Chiral diamines 4: a computational study of the enantioselective deprotonation of Boc-pyrrolidine with an alkyllithium in the presence of a chiral diamine.

    PubMed

    Wiberg, K B; Bailey, W F

    2001-08-29

    The enantioselective deprotonation of N-Boc-pyrrolidine (1) with i-PrLi-(-)-sparteine has been studied at theoretical levels up through B3P86/6-31G. Four low-energy intermediate complexes involving i-PrLi-(-)-sparteine and 1 were located via geometry optimizations; two of these complexes would lead to abstraction of the pro-S hydrogen from 1, and the other two complexes would lead to loss of the pro-R hydrogen. The lowest-energy intermediate complex was found to lead to loss of the pro-S hydrogen as observed experimentally. Transition states for the deprotonations were located using the synchronous transit-guided quasi-Newton method. The calculated activation enthalpy for transfer of the pro-S hydrogen within the lowest-energy intermediate complex, 10.8 kcal/mol, is reasonable for a reaction that occurs at a relatively low temperature, and the calculated kinetic hydrogen isotope effect is in agreement with experimental data. The lower enantioselectivity observed experimentally for deprotonation of 1 using t-BuLi-(-)-sparteine is attributed to a transition-state effect due to increased steric interaction engendered by the bulky t-BuLi. Replacement of the tert-butoxycarbonyl group in 1 by a methoxycarbonyl is predicted to result in a slower deprotonation with somewhat decreased enantioselectivity. Asymmetric deprotonation of 1 using i-PrLi in combination with the C(2)-symmetric diamine, (S,S)-1,2-bis(N,N-dimethylamino)cyclohexane, was calculated to be much less selective than is the deprotonation mediated by (-)-sparteine as observed experimentally. The relative energies of the intermediate complexes were fairly well-reproduced by ONIUM calculations in which the sparteine ligand less its nitrogen atoms was treated by molecular mechanics and the remainder of the complex was treated by quantum mechanics. PMID:11516274

  8. Agent Orange

    MedlinePlus

    ... Index Agent Orange Agent Orange Home Facts about Herbicides Veterans' Diseases Birth Defects Benefits Exposure Locations Provider ... millions of gallons of Agent Orange and other herbicides on trees and vegetation during the Vietnam War. ...

  9. Animal Models for HIV Cure Research.

    PubMed

    Policicchio, Benjamin B; Pandrea, Ivona; Apetrei, Cristian

    2016-01-01

    The HIV-1/AIDS pandemic continues to spread unabated worldwide, and no vaccine exists within our grasp. Effective antiretroviral therapy (ART) has been developed, but ART cannot clear the virus from the infected patient. A cure for HIV-1 is badly needed to stop both the spread of the virus in human populations and disease progression in infected individuals. A safe and effective cure strategy for human immunodeficiency virus (HIV) infection will require multiple tools, and appropriate animal models are tools that are central to cure research. An ideal animal model should recapitulate the essential aspects of HIV pathogenesis and associated immune responses, while permitting invasive studies, thus allowing a thorough evaluation of strategies aimed at reducing the size of the reservoir (functional cure) or eliminating the reservoir altogether (sterilizing cure). Since there is no perfect animal model for cure research, multiple models have been tailored and tested to address specific quintessential questions of virus persistence and eradication. The development of new non-human primate and mouse models, along with a certain interest in the feline model, has the potential to fuel cure research. In this review, we highlight the major animal models currently utilized for cure research and the contributions of each model to this goal.

  10. Framing expectations in early HIV cure research.

    PubMed

    Dubé, Karine; Henderson, Gail E; Margolis, David M

    2014-10-01

    Language used to describe clinical research represents a powerful opportunity to educate volunteers. In the case of HIV cure research there is an emerging need to manage expectations by using the term 'experiment'. Cure experiments are proof-of-concept studies designed to evaluate novel paradigms to reduce persistent HIV-1 reservoirs, without any expectation of medical benefit.

  11. 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...

  12. 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...

  13. Animal Models for HIV Cure Research

    PubMed Central

    Policicchio, Benjamin B.; Pandrea, Ivona; Apetrei, Cristian

    2016-01-01

    The HIV-1/AIDS pandemic continues to spread unabated worldwide, and no vaccine exists within our grasp. Effective antiretroviral therapy (ART) has been developed, but ART cannot clear the virus from the infected patient. A cure for HIV-1 is badly needed to stop both the spread of the virus in human populations and disease progression in infected individuals. A safe and effective cure strategy for human immunodeficiency virus (HIV) infection will require multiple tools, and appropriate animal models are tools that are central to cure research. An ideal animal model should recapitulate the essential aspects of HIV pathogenesis and associated immune responses, while permitting invasive studies, thus allowing a thorough evaluation of strategies aimed at reducing the size of the reservoir (functional cure) or eliminating the reservoir altogether (sterilizing cure). Since there is no perfect animal model for cure research, multiple models have been tailored and tested to address specific quintessential questions of virus persistence and eradication. The development of new non-human primate and mouse models, along with a certain interest in the feline model, has the potential to fuel cure research. In this review, we highlight the major animal models currently utilized for cure research and the contributions of each model to this goal. PMID:26858716

  14. A new hypothesis on HIV cure

    PubMed Central

    Hladik, Florian

    2015-01-01

    In this opinion article, I provide the rationale for my hypothesis that nucleoside reverse transcriptase inhibitors (NRTIs) may prevent human immunodeficiency virus (HIV) cure by promoting the survival of cells with integrated provirus. If correct, we may be closer to a cure than we realize. PMID:26380071

  15. Dental resin cure monitoring by inherent fluorescence

    NASA Astrophysics Data System (ADS)

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

    2008-02-01

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

  16. Biodegradable Epoxy Networks Cured with Polypeptides

    NASA Astrophysics Data System (ADS)

    Nakamura, Shigeo; Kramer, Edward J.

    2006-03-01

    Epoxy resins are used widely for adhesives as well as coatings. However, once cured they are usually highly cross-linked and are not biodegradable. To obtain potentially biodegradable polypeptides that can cure with epoxy resins and achieve as good properties as the conventional phenol novolac hardeners, poly(succinimide-co-tyrosine) was synthesized by thermal polycondensation of L-aspartic acid and L-tyrosine with phosphoric acid under reduced pressure. The tyrosine/succinimide ratio in the polypeptide was always lower than the tyrosine/(aspartic acid) feed ratio and was influenced by the synthesis conditions. Poly(succinimide-tyrosine- phenylalanine) was also synthesized from L-aspartic acid, L- tyrosine and L-phenylalanine. The thermal and mechanical properties of epoxy resins cured with these polypeptides are comparable to those of similar resins cured with conventional hardeners. In addition, enzymatic degradability tests showed that Chymotrypsin or Subtilisin A could cleave cured films in an alkaline borate buffer.

  17. 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.

  18. 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...

  19. 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...

  20. 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...

  1. 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...

  2. 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...

  3. 9 CFR 319.103 - Cured beef tongue.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 2 2012-01-01 2012-01-01 false Cured beef tongue. 319.103 Section 319... Cured beef tongue. In preparing “Cured Beef Tongue,” the application of curing solution to the fresh beef tongue shall not result in an increase in the weight of the cured beef tongue of more than...

  4. 9 CFR 319.103 - Cured beef tongue.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 2 2013-01-01 2013-01-01 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...

  5. 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...

  6. 9 CFR 319.103 - Cured beef tongue.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 2 2011-01-01 2011-01-01 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...

  7. 9 CFR 319.103 - Cured beef tongue.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 2 2014-01-01 2014-01-01 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...

  8. 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

  9. Synthesis of enantioenriched 1,2-trans-diamines using the borono-Mannich reaction with N-protected α-amino aldehydes.

    PubMed

    Norsikian, Stéphanie; Beretta, Margaux; Cannillo, Alexandre; Martin, Amélie; Retailleau, Pascal; Beau, Jean-Marie

    2015-06-21

    The three-component Petasis borono-Mannich reaction starting with easily accessible N-protected α-amino aldehydes produces efficiently and diastereoselectively 1,2-trans-diamines with an enantiomeric excess of up to 98%.

  10. Effects of argon laser curing on dentin shear bond strengths

    NASA Astrophysics Data System (ADS)

    Powell, G. L.; Blankenau, Richard J.

    1996-04-01

    Previous studies have demonstrated the ability of the argon laser to polymerize light activated materials and improve enamel shear bond strengths. This study was conducted to evaluate the effects of the argon laser on dentin shear bond strengths of current dentin bonding systems. Argon laser (HGM Model 8) at 231 mw and 280 mw, 5 second bonding agent, 10 seconds composite and a conventional curing light (Translux EC/Kulzer) at 10 seconds bonding agent, 20 second composite were used to polymerize samples of dentin bonding systems: Scotchbond Multi-Purpose Plus (3M) and Prime Bond (Dentsply/Caulk), both with TPH (Dentsply/Caulk) composite. A flat dentin bonding site (600 grit) was prepared on the buccal surface of extracted human teeth. Twelve samples were made for each set of parameters for both laser and conventional light totaling 60 samples. Samples were stored in distilled water in light- proof containers for 24 hours at 37 degree(s)C. Shear bond strengths (MPa) were determined for each sample on the Instron testing machine. Mean values were calculated for each set of data and ANOVA with Fisher PLSD were used for statistical analysis. The argon laser provided bond strengths that were 21 - 24% greater than those of the conventional curing light system.

  11. Characterization of cure kinetics and physical properties of a high performance, glass fiber-reinforced epoxy prepreg and a novel fluorine-modified, amine-cured commercial epoxy

    NASA Astrophysics Data System (ADS)

    Bilyeu, Bryan

    Kinetic equation parameters for the curing reaction of a commercial glass fiber reinforced high performance epoxy prepreg composed of the tetrafunctional epoxy tetraglycidyl 4,4-diaminodiphenyl methane (TGDDM), the tetrafunctional amine curing agent 4,4'-diaminodiphenylsulfone (DDS) and an ionic initiator/accelerator, are determined by various thermal analysis techniques and the results compared. The reaction is monitored by heat generated determined by differential scanning calorimetry (DSC) and by high speed DSC when the reaction rate is high. The changes in physical properties indicating increasing conversion are followed by shifts in glass transition temperature determined by DSC, temperature-modulated DSC (TMDSC), step scan DSC and high speed DSC, thermomechanical (TMA) and dynamic mechanical (DMA) analysis and thermally stimulated depolarization (TSD). Changes in viscosity, also indicative of degree of conversion, are monitored by DMA. Thermal stability as a function of degree of cure is monitored by thermogravimetric analysis (TGA). The parameters of the general kinetic equations, including activation energy and rate constant, are explained and used to compare results of various techniques. The utilities of the kinetic descriptions are demonstrated in the construction of a useful time-temperature-transformation (TTT) diagram and a continuous heating transformation (CHT) diagram for rapid determination of processing parameters in the processing of prepregs. Shrinkage due to both resin consolidation and fiber rearrangement is measured as the linear expansion of the piston on a quartz dilatometry cell using TMA. The shrinkage of prepregs was determined to depend on the curing temperature, pressure applied and the fiber orientation. Chemical modification of an epoxy was done by mixing a fluorinated aromatic amine (aniline) with a standard aliphatic amine as a curing agent for a commercial Diglycidylether of Bisphenol-A (DGEBA) epoxy. The resulting cured network

  12. 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.

  13. A bisphenol-A-based resin system that cures via triazole ring formation for marine composite applications

    NASA Astrophysics Data System (ADS)

    Gorman, Irene Elizabeth

    Large composite panels, such as those utilized in marine applications, cannot be economically cured in an autoclave. For these structures the elevated temperatures necessary to achieve high crosslink density must come from the curing reaction itself. We are developing a resin system that cures via triazole ring formation (cycloaddition reaction of azides with terminal alkynes) instead of the traditional oxirane/amine reaction. The high exothermicity of the azido/alkyne reaction is expected to yield higher extents of reaction under ambient-cure conditions, making the resin system potentially suitable for "out-of-autoclave" curing processes. This work was conducted through a multi-tiered approach involving synthesis, kinetic studies, thermal characterization, and mechanical analysis. The difunctional azide-terminated resin, di(3-azido-2 hydroxypropyl) ether of bisphenol-A (DAHP-BPA), was selected as the baseline diazide. A number of alkyne crosslinkers were synthesized and characterized, including propiolate esters of di- and trifunctional alcohols, propargyl esters of di- and trifunctional carboxylic acids, propargyl ethers of di- and trifunctional alcohols, and N,N,N',N'-tetrapropargyl derivatives of primary diamines. Commercially available tripropargylamine (TPA) was also studied. Curing energetics as a function of alkyne type and catalyst loading, investigated through a dynamic differential scanning calorimetry approach, displayed two distinct kinetic profiles when considering propiolate and propargyl type crosslinkers. Those systems employing a propiolate-based alkyne were found to be much more reactive towards the Huisgen 1,3-dipolar cycloaddition than the propargyl species. Additionally, the mechanical and thermal properties of resin systems, both un-catalyzed and catalyzed, composed of DAHP-BPA and tripropargyl amine were investigated by compression and rheological studies, differential scanning calorimetry, and thermogravametric analysis. The moduli of both

  14. Recent advances in electron-beam curing of carbon fiber-reinforced composites

    NASA Astrophysics Data System (ADS)

    Coqueret, Xavier; Krzeminski, Mickael; Ponsaud, Philippe; Defoort, Brigitte

    2009-07-01

    Cross-linking polymerization initiated by high-energy radiation is a very attractive technique for the fabrication of high-performance composite materials. The method offers many advantages compared to conventional energy- and time-consuming thermal curing processes. Free radical and cationic poly-addition chemistries have been investigated in some details by various research groups along the previous years. A high degree of control over curing kinetics and material properties can be exerted by adjusting the composition of matrix precursors as well as by acting on process parameters. However, the comparison with state-of-the-art thermally cured composites revealed the lower transverse mechanical properties of radiation-cured composites and the higher brittleness of the radiation-cured matrix. Improving fiber-matrix adhesion and upgrading polymer network toughness are thus two major challenges in this area. We have investigated several points related to these issues, and particularly the reduction of the matrix shrinkage on curing, the wettability of carbon fibers, the design of fiber-matrix interface and the use of thermoplastic toughening agents. Significant improvements were achieved on transverse strain at break by applying original surface treatments on the fibers so as to induce covalent coupling with the matrix. A drastic enhancement of the K IC value exceeding 2 MPa m 1/2 was also obtained for acrylate-based matrices toughened with high T g thermoplastics.

  15. 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.

  16. 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.

  17. 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.

  18. [Is it possible to cure HIV infection?].

    PubMed

    Gutiérrez, Carolina; Madrid, Nadia P; Moreno, Santiago

    2015-09-01

    Antiretroviral therapy has significantly improved the life expectancy in HIV-infected people, but it cannot cure the disease by itself. Several barriers have been identified for the cure of HIV infection, including a reservoir of latently infected cells, persistent viral replication in tissues, and anatomical sanctuaries. The main strategy proposed for the cure of HIV consists on the administration of drugs that, through the reactivation of latent HIV, would eliminate the cell reservoir. Ongoing clinical trials have shown the proof of concept, but the efficacy of these drugs in decreasing the reservoir size has not been proved so far.

  19. [Is it possible to cure HIV infection?].

    PubMed

    Gutiérrez, Carolina; Madrid, Nadia P; Moreno, Santiago

    2015-09-01

    Antiretroviral therapy has significantly improved the life expectancy in HIV-infected people, but it cannot cure the disease by itself. Several barriers have been identified for the cure of HIV infection, including a reservoir of latently infected cells, persistent viral replication in tissues, and anatomical sanctuaries. The main strategy proposed for the cure of HIV consists on the administration of drugs that, through the reactivation of latent HIV, would eliminate the cell reservoir. Ongoing clinical trials have shown the proof of concept, but the efficacy of these drugs in decreasing the reservoir size has not been proved so far. PMID:26365737

  20. 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.

  1. Helicenes as All-in-One Organic Materials for Application in OLEDs: Synthesis and Diverse Applications of Carbo- and Aza[5]helical Diamines.

    PubMed

    Jhulki, Samik; Mishra, Abhaya Kumar; Chow, Tahsin J; Moorthy, Jarugu Narasimha

    2016-06-27

    A set of eight helical diamines were designed and synthesized to demonstrate their relevance as all-in-one materials for multifarious applications in organic light-emitting diodes (OLEDs), that is, as hole-transporting materials (HTMs), EMs, bifunctional hole transporting + emissive materials, and host materials. Azahelical diamines function very well as HTMs. Indeed, with high Tg values (127-214 °C), they are superior alternatives to popular N,N'-di(1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (NPB). All the helical diamines exhibit emissive properties when employed in nondoped as well as doped devices, the performance characteristics being superior in the latter. One of the carbohelical diamines (CHTPA) serves the dual function of hole transport as well as emission in simple double-layer devices; the efficiencies observed were better by quite some margin than those of other emissive helicenes reported. The twisting endows helical diamines with significantly high triplet energies such that they also function as host materials for red and green phosphors, that is, [Ir(btp)2 acac] (btp=2-(2'-benzothienyl)pyridine; acac=acetylacetonate) and [Ir(ppy)3 ] (ppy=2-phenylpyridine), respectively. The results of device fabrications demonstrate how helicity/ helical scaffold may be diligently exploited to create molecular systems for maneuvering diverse applications in OLEDs. PMID:27244223

  2. Graphene-based porous materials with tunable surface area and CO2 adsorption properties synthesized by fluorine displacement reaction with various diamines.

    PubMed

    Li, Baoyin; Fan, Kun; Ma, Xin; Liu, Yang; Chen, Teng; Cheng, Zheng; Wang, Xu; Jiang, Jiaxing; Liu, Xiangyang

    2016-09-15

    A mild, operationally simple and controllable protocol for preparing graphene-based porous materials is essential to achieve a good pore-design development. In this paper, graphene-based porous materials with tunable surface area were constructed by the intercalation of fluorinated graphene (FG) based on the reaction of reactive CF bonds attached to graphene sheets with various amine-terminated molecules. In the porous materials, graphene sheets are like building blocks, and the diamines covalently grafted onto graphene framework act as pillars. Various diamines are successfully grafted onto graphene sheets, but the grafting ratio of diamines and reduction degree of FG differ greatly and depend on the chemical reactivity of diamines. Pillared diamine molecules chemically anchor at one end and are capable of undergoing a different reaction on the other end, resulting in three different conformations of graphene derivatives. Nitrogen sorption isotherms revealed that the surface area and pore distribution of the obtained porous materials depend heavily on the size and structure of diamine pillars. CO2 uptake capacity characterization showed that ethylenediamine intercalated FG achieved a high CO2 uptake density of 18.0 CO2 molecules per nm(2) at 0°C and 1.1bars, and high adsorption heat, up to 46.1kJmol(-1) at zero coverage. PMID:27280538

  3. Helicenes as All-in-One Organic Materials for Application in OLEDs: Synthesis and Diverse Applications of Carbo- and Aza[5]helical Diamines.

    PubMed

    Jhulki, Samik; Mishra, Abhaya Kumar; Chow, Tahsin J; Moorthy, Jarugu Narasimha

    2016-06-27

    A set of eight helical diamines were designed and synthesized to demonstrate their relevance as all-in-one materials for multifarious applications in organic light-emitting diodes (OLEDs), that is, as hole-transporting materials (HTMs), EMs, bifunctional hole transporting + emissive materials, and host materials. Azahelical diamines function very well as HTMs. Indeed, with high Tg values (127-214 °C), they are superior alternatives to popular N,N'-di(1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (NPB). All the helical diamines exhibit emissive properties when employed in nondoped as well as doped devices, the performance characteristics being superior in the latter. One of the carbohelical diamines (CHTPA) serves the dual function of hole transport as well as emission in simple double-layer devices; the efficiencies observed were better by quite some margin than those of other emissive helicenes reported. The twisting endows helical diamines with significantly high triplet energies such that they also function as host materials for red and green phosphors, that is, [Ir(btp)2 acac] (btp=2-(2'-benzothienyl)pyridine; acac=acetylacetonate) and [Ir(ppy)3 ] (ppy=2-phenylpyridine), respectively. The results of device fabrications demonstrate how helicity/ helical scaffold may be diligently exploited to create molecular systems for maneuvering diverse applications in OLEDs.

  4. Graphene-based porous materials with tunable surface area and CO2 adsorption properties synthesized by fluorine displacement reaction with various diamines.

    PubMed

    Li, Baoyin; Fan, Kun; Ma, Xin; Liu, Yang; Chen, Teng; Cheng, Zheng; Wang, Xu; Jiang, Jiaxing; Liu, Xiangyang

    2016-09-15

    A mild, operationally simple and controllable protocol for preparing graphene-based porous materials is essential to achieve a good pore-design development. In this paper, graphene-based porous materials with tunable surface area were constructed by the intercalation of fluorinated graphene (FG) based on the reaction of reactive CF bonds attached to graphene sheets with various amine-terminated molecules. In the porous materials, graphene sheets are like building blocks, and the diamines covalently grafted onto graphene framework act as pillars. Various diamines are successfully grafted onto graphene sheets, but the grafting ratio of diamines and reduction degree of FG differ greatly and depend on the chemical reactivity of diamines. Pillared diamine molecules chemically anchor at one end and are capable of undergoing a different reaction on the other end, resulting in three different conformations of graphene derivatives. Nitrogen sorption isotherms revealed that the surface area and pore distribution of the obtained porous materials depend heavily on the size and structure of diamine pillars. CO2 uptake capacity characterization showed that ethylenediamine intercalated FG achieved a high CO2 uptake density of 18.0 CO2 molecules per nm(2) at 0°C and 1.1bars, and high adsorption heat, up to 46.1kJmol(-1) at zero coverage.

  5. 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.

  6. Diastereodivergent Catalytic Asymmetric Michael Addition of 2-Oxindoles to α,β-Unsaturated Ketones by Chiral Diamine Catalysts.

    PubMed

    Wei, Yuan; Wen, Shigang; Liu, Zunwu; Wu, Xinxin; Zeng, Bubing; Ye, Jinxing

    2015-06-01

    A diastereodivergent catalytic asymmetric Michael addition of 2-oxindoles to α,β-unsaturated ketones has been successfully developed with two complementary chiral diamine catalysts, affording chiral 3,3-disubstituted oxindoles with two adjacent chiral centers. Diastereodivergence has been realized through modifying substrates and utilizing different catalysts. Either anti-or syn-configured products possessing vicinal quaternary and tertiary stereogenic centers were produced with high enantioselectivities. PMID:25973971

  7. 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.

  8. Polyol-acid anhydride-n-alkyl-alkylene diamine reaction product and motor fuel composition containing same

    SciTech Connect

    Sung, R.L.; Jenkins, R.H. Jr.

    1987-02-17

    A fuel composition for an internal combustion engine comprising: (a) a major portion of a liquid hydrocarbon fuel and (b) a minor amount, as a deposit inhibitor additive, of a reaction product of a process comprising: (i) reacting a dibasic acid anhydride with a polyol, thereby forming an ester of maleic acid; (ii) reacting the ester of maleic acid with an N-alkyl-alkylene diamine, thereby forming the reaction product; and (iii) recovering the reaction product.

  9. 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.

  10. The conjugates of ferrocene-1,1'-diamine and amino acids. A novel synthetic approach and conformational analysis.

    PubMed

    Kovačević, Monika; Kodrin, Ivan; Cetina, Mario; Kmetič, Ivana; Murati, Teuta; Semenčić, Mojca Čakić; Roca, Sunčica; Barišić, Lidija

    2015-10-01

    A novel synthetic approach toward a poorly explored bioorganometallic consisting of ferrocene-1,1'-diamine bearing structurally and chirally diverse amino acid sequences is reported. Until now, ferrocene-1,1'-diamine was suitable for accommodating only identical amino acid sequences at its N-termini, leading to the symmetrically disubstituted homochiral products stabilized through a 14-membered intramolecular hydrogen-bonded ring as is seen in antiparallel β-sheet peptides. The key step of the novel synthetic pathway is the transformation of Ac-Ala-NH-Fn-COOH (5) (Fn = 1,1'-ferrocenylene) to orthogonally protected Ac-Ala-NH-Fn-NHBoc (7). The spectroscopic analysis (IR, NMR, CD) of the novel compounds, corroborated with DFT studies, suggests the interesting feature of the ferrocene-1,1'-diamine scaffold. The same hydrogen-bonding pattern, i.e. a 14-membered hydrogen-bonded ring, was determined both in solution and in the solid state, thus making them promising, yet simple scaffolds capable of mimicking β-sheet peptides. In vitro screening of potential anticancer activity in Hep G2 human liver carcinoma cells and Hs 578 T human breast cancer cells revealed a cytotoxic pattern for novel compounds (150-500 μM) with significantly decreased cell proliferation.

  11. Financing cures in the United States.

    PubMed

    Basu, Anirban

    2015-02-01

    True cures in health care are rare but likely not for long. The high price tag that accompanies a cure along with its rapid uptake create challenges in the financing of cures by public and private payers. In the US, the disaggregated nature of health insurance system adds to this challenge as patients frequently churn across multiple health plans. This creates a 'free-rider' problem, where no one health plan has the incentive to invest in cure since the returns will be scattered over many health plans. Here, a new health currency is proposed as a generalized version of a social impact bond that has the potential to solve this free-rider problem, as it can be traded not only between public and private payers but also within the private sector. An ensuing debate as to whether and how to develop such a currency can serve the US health care system well. PMID:25482146

  12. Financing cures in the United States.

    PubMed

    Basu, Anirban

    2015-02-01

    True cures in health care are rare but likely not for long. The high price tag that accompanies a cure along with its rapid uptake create challenges in the financing of cures by public and private payers. In the US, the disaggregated nature of health insurance system adds to this challenge as patients frequently churn across multiple health plans. This creates a 'free-rider' problem, where no one health plan has the incentive to invest in cure since the returns will be scattered over many health plans. Here, a new health currency is proposed as a generalized version of a social impact bond that has the potential to solve this free-rider problem, as it can be traded not only between public and private payers but also within the private sector. An ensuing debate as to whether and how to develop such a currency can serve the US health care system well.

  13. 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.

  14. Thread-Pull Test Of Curing Adhesive

    NASA Technical Reports Server (NTRS)

    Johnson, James A.

    1992-01-01

    Hardness (and degree of cure) of adhesive layer measured by pulling previously inserted thread out of layer. Strength of bond measured directly on assembly rather than on samples, which can be misleading.

  15. Independent evolutionary origins of functional polyamine biosynthetic enzyme fusions catalyzing de novo diamine to triamine formation

    PubMed Central

    Green, Robert; Hanfrey, Colin C.; Elliott, Katherine A.; McCloskey, Diane E.; Wang, Xiaojing; Kanugula, Sreenivas; Pegg, Anthony E.; Michael, Anthony J.

    2011-01-01

    Summary We have identified gene fusions of polyamine biosynthetic enzymes S-adenosylmethionine decarboxylase (AdoMetDC, speD) and aminopropyltransferase (speE) orthologues in diverse bacterial phyla. Both domains are functionally active and we demonstrate the novel de novo synthesis of the triamine spermidine from the diamine putrescine by fusion enzymes from β-proteobacterium Delftia acidovorans and δ-proteobacterium Syntrophus aciditrophicus, in a ΔspeDE gene deletion strain of Salmonella enterica sv. Typhimurium. Fusion proteins from marine α-proteobacterium Candidatus Pelagibacter ubique, actinobacterium Nocardia farcinica, chlorobi species Chloroherpeton thalassium, and β-proteobacterium Delftia acidovorans each produce a different profile of non-native polyamines including sym-norspermidine when expressed in Escherichia coli. The different aminopropyltransferase activities together with phylogenetic analysis confirm independent evolutionary origins for some fusions. Comparative genomic analysis strongly indicates that gene fusions arose by merger of adjacent open reading frames. Independent fusion events, and horizontal and vertical gene transfer contributed to the scattered phyletic distribution of the gene fusions. Surprisingly, expression of fusion genes in E. coli and S. Typhimurium revealed novel latent spermidine catabolic activity producing non-native 1,3-diaminopropane in these species. We have also identified fusions of polyamine biosynthetic enzymes agmatine deiminase and N-carbamoylputrescine amidohydrolase in archaea, and of S-adenosylmethionine decarboxylase and ornithine decarboxylase in the single-celled green alga Micromonas. PMID:21762220

  16. 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.

  17. 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. PMID:27207576

  18. 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.

  19. Absorption and desorption of SO2 in aqueous solutions of diamine-based molten salts.

    PubMed

    Lim, Seung Rok; Hwang, Junhyeok; Kim, Chang Soo; Park, Ho Seok; Cheong, Minserk; Kim, Hoon Sik; Lee, Hyunjoo

    2015-05-30

    SO2 absorption and desorption behaviors were investigated in aqueous solutions of diamine-derived molten salts with a tertiary amine group on the cation and a chloride anion, including butyl-(2-dimethylaminoethyl)-dimethylammonium chloride ([BTMEDA]Cl, pKb=8.2), 1-butyl-1,4-dimethylpiperazinium chloride ([BDMP]Cl, pKb=9.8), and 1-butyl-4-aza-1-azoniabicyclo[2,2,2]octane chloride ([BDABCO]Cl, pKb=11.1). The SO2 absorption and desorption performance of the molten salt were greatly affected by the basicity of the molten salt. Spectroscopic, X-ray crystallographic, and computational results for the interactions of SO2 with molten salts suggest that two types of SO2-containg species could be generated depending on the basicity of the unquaternized amino group: a dicationic species comprising two different anions, HSO3(-) and Cl(-), and a monocationic species bearing Cl(-) interacting with neutral H2SO3.

  20. Characterization of recombinant human diamine oxidase (rhDAO) produced in Chinese Hamster Ovary (CHO) cells.

    PubMed

    Gludovacz, Elisabeth; Maresch, Daniel; Bonta, Maximilian; Szöllösi, Helen; Furtmüller, Paul G; Weik, Robert; Altmann, Friedrich; Limbeck, Andreas; Borth, Nicole; Jilma, Bernd; Boehm, Thomas

    2016-06-10

    Human diamine oxidase (hDAO) efficiently degrades polyamines and histamine. Reduced enzyme activities might cause complications during pregnancy and be involved in histamine intolerance. So far hDAO has been characterized after isolation from either native sources or the heterologous production in insect cells. Accessibility to human enzyme is limited and insect cells produce non-human glycosylation patterns that may alter its biochemical properties. We present the heterologous expression of hDAO in Chinese Hamster Ovary (CHO) cells and a three step purification protocol. Analysis of metal content using ICP-MS revealed that 93% of the active sites were occupied by copper. Topaquinone (TPQ) cofactor content was determined using phenylhydrazine titration. Ninety-four percent of DAO molecules contained TPQ and therefore the copper content at the active site was indirectly confirmed. Mass spectrometric analysis was conducted to verify sequence integrity of the protein and to assess the glycosylation profile. Electronic circular dichroism and UV-vis spectra data were used to characterize structural properties. The substrate preference and kinetic parameters were in accordance with previous publications. The establishment of a recombinant production system for hDAO enables us to generate decent amounts of protein with negligible impurities to address new scientific questions.

  1. Diphenylether-Modified 1,2-Diamines with Improved Drug Properties for Development against Mycobacterium tuberculosis.

    PubMed

    Foss, Marie H; Pou, Sovitj; Davidson, Patrick M; Dunaj, Jennifer L; Winter, Rolf W; Pou, Sovijja; Licon, Meredith H; Doh, Julia K; Li, Yuexin; Kelly, Jane X; Dodean, Rozalia A; Koop, Dennis R; Riscoe, Michael K; Purdy, Georgiana E

    2016-07-01

    New treatments for tuberculosis infection are critical to combat the emergence of multidrug- and extensively drug-resistant Mycobacterium tuberculosis (Mtb). We report the characterization of a diphenylether-modified adamantyl 1,2-diamine that we refer to as TBL-140, which has a minimal inhibitory concentration (MIC99) of 1.2 μg/mL. TBL-140 is effective against drug-resistant Mtb and nonreplicating bacteria. In addition, TBL-140 eliminates expansion of Mtb in cell culture infection assays at its MIC. To define the mechanism of action of this compound, we performed a spontaneous mutant screen and biochemical assays. We determined that TBL-140 treatment affects the proton motive force (PMF) by perturbing the transmembrane potential (ΔΨ), consistent with a target in the electron transport chain (ETC). As a result, treated bacteria have reduced intracellular ATP levels. We show that TBL-140 exhibits greater metabolic stability than SQ109, a structurally similar compound in clinical trials for treatment of MDR-TB infections. Combined, these results suggest that TBL-140 should be investigated further to assess its potential as an improved therapeutic lead against Mtb. PMID:27626102

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

    PubMed

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

    2016-03-01

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

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Cure fraction estimation from the mixture cure models for grouped survival data.

    PubMed

    Yu, Binbing; Tiwari, Ram C; Cronin, Kathleen A; Feuer, Eric J

    2004-06-15

    Mixture cure models are usually used to model failure time data with long-term survivors. These models have been applied to grouped survival data. The models provide simultaneous estimates of the proportion of the patients cured from disease and the distribution of the survival times for uncured patients (latency distribution). However, a crucial issue with mixture cure models is the identifiability of the cure fraction and parameters of kernel distribution. Cure fraction estimates can be quite sensitive to the choice of latency distributions and length of follow-up time. In this paper, sensitivity of parameter estimates under semi-parametric model and several most commonly used parametric models, namely lognormal, loglogistic, Weibull and generalized Gamma distributions, is explored. The cure fraction estimates from the model with generalized Gamma distribution is found to be quite robust. A simulation study was carried out to examine the effect of follow-up time and latency distribution specification on cure fraction estimation. The cure models with generalized Gamma latency distribution are applied to the population-based survival data for several cancer sites from the Surveillance, Epidemiology and End Results (SEER) Program. Several cautions on the general use of cure model are advised.

  13. Biological Agents

    MedlinePlus

    ... to Z Index Contact Us FAQs What's New Biological Agents This page requires that javascript be enabled ... and Health Topics A-Z Index What's New Biological agents include bacteria, viruses, fungi, other microorganisms and ...

  14. 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.

  15. Comparative depths of cure among various curing light types and methods.

    PubMed

    Soh, M S; Yap, Adrian U J; Siow, K S

    2004-01-01

    This study evaluated the depth of cure associated with commercial LEDs (light-emitting diodes) (Elipar FreeLight [FL], 3M-ESPE; GC e-Light [EL], GC), high intensity (Elipar TriLight [TL], 3M-ESPE) and very high intensity (Astralis 10 [AS], Ivoclar Vivadent) Quartz Tungsten Halogen (QTH) curing lights. Depth of cure of the various lights/curing modes were compared to a conventional QTH light (Max [Mx], Dentsply-Caulk). Ten exposure regimens were investigated: FL1 - 400 mW/cm2 [40 seconds]; FL2 - 0-400 mW/cm2 [12 seconds] --> 400 mW/cm2 [28 seconds]; EL1 - 750 mW/cm2 [10 pulses x 2 seconds], EL2 - 350 mW/cm2 [40 seconds]; EL3 - 600 mW/cm2 [20 seconds]; EL4 - 0 - 600 mW/cm2 [20 seconds] --> 600 mW/cm2 [20 seconds]; TL1 - 800 mW/cm2 [40 seconds]; TL2 - 100- 800 mW/cm2 [15 seconds] --> 800 mW/cm2 [25 seconds]; AS1 - 1200 mW/cm2 [10 seconds]; MX - 400 mW/cm2 [40 seconds]. Depth of cure was determined by penetration, scraping and microhardness techniques. The results were analyzed using one-way ANOVA/Scheffe's post-hoc test and Pearson's correlation at significance level 0.05 and 0.01, respectively. All light curing regimens met the ISO depth of cure requirement of 1.5 mm with the exception of EL1-EL3 with the microhardness technique. Curing with most modes of EL resulted in significantly lower depths of cure than the control [MX]. No significant difference in depth of cure was observed among the control and the two modes of FL. Curing with TL1 resulted in significantly greater depth of cure compared to MX with all testing techniques. No significant difference in depth of cure was observed between the control and AS1 for all testing techniques except for the penetration technique. The depth of composite cure is light unit and exposure mode dependent. Scraping and penetration techniques were found to correlate well but tend to overestimate depth of cure compared to microhardness.

  16. Softening patterns of post-cure heat-treated dental composites.

    PubMed

    Mante, F; Saleh, N; Mante, M

    1993-09-01

    The softening of post-cure, heat-treated dental composites in various solutions was evaluated by Knoop hardness measurements. The samples were heated at 120 degrees C for 7 min immediately after curing and immersed in various solutions, water, ethanol, heptane and 0.1 N NaOH. Significant increases in hardness were observed for heated samples when compared to unheated samples. The various solutions softened both heated and unheated composites but heated samples were softened to a lesser degree. Plots of hardness of heated and unheated samples were nearly parallel, indicating that mechanisms such as penetration of the resin matrix, degradation of the silane coupling agent and fillers may be involved in the softening of both heated and unheated composites. Post-cure heat treatment improved the resistance to softening of dental composites.

  17. 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...

  18. 7 CFR 29.3502 - Air-cured.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

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

  19. 7 CFR 29.3502 - Air-cured.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

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

  20. 7 CFR 29.3002 - Air-cured.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Air-cured. 29.3002 Section 29.3002 Agriculture... Air-cured. Tobacco cured under natural atmospheric conditions. Artificial heat is sometimes used to control excess humidity during the curing period to prevent house-burn and barn-burn in damp weather....

  1. 7 CFR 29.3002 - Air-cured.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Air-cured. 29.3002 Section 29.3002 Agriculture... Air-cured. Tobacco cured under natural atmospheric conditions. Artificial heat is sometimes used to control excess humidity during the curing period to prevent house-burn and barn-burn in damp weather....

  2. 7 CFR 29.3502 - Air-cured.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

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

  3. 7 CFR 29.3002 - Air-cured.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Air-cured. 29.3002 Section 29.3002 Agriculture... Air-cured. Tobacco cured under natural atmospheric conditions. Artificial heat is sometimes used to control excess humidity during the curing period to prevent house-burn and barn-burn in damp weather....

  4. 7 CFR 29.3002 - Air-cured.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Air-cured. 29.3002 Section 29.3002 Agriculture... Air-cured. Tobacco cured under natural atmospheric conditions. Artificial heat is sometimes used to control excess humidity during the curing period to prevent house-burn and barn-burn in damp weather....

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 7 CFR 29.3502 - Air-cured.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 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...

  11. 7 CFR 29.3002 - Air-cured.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Air-cured. 29.3002 Section 29.3002 Agriculture... Air-cured. Tobacco cured under natural atmospheric conditions. Artificial heat is sometimes used to control excess humidity during the curing period to prevent house-burn and barn-burn in damp weather....

  12. 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...

  13. Selection of luting agents, part 1.

    PubMed

    Jivraj, Sajid A; Kim, Tae Hyung; Donovan, Terry E

    2006-02-01

    The clinical success of indirect restorations is dependent on multiple factors that include preparation design, mechanical forces, restorative material selection, oral hygiene, and selection of a proper luting agent. The selection of the luting agent is dependent on the specific clinical situation, the type of restoration utilized and the physical, biologic, and handling properties of the luting agent. Although it is important to choose the best luting agent for each clinical situation, far greater variations in physical properties result from improper manipulation of a given luting agent than exist between different types of cements. One study listed loss of retention as the third-leading cause of prosthetic replacement, with failure occurring after only 5.8 years in service. The primary purpose of the luting procedure is to achieve a durable bond and to have good marginal adaptation of the luting material to the restoration and tooth. Conventional cements have always relied upon retention and resistance forms in tooth preparations; Adhesive-type luting agents offer the clinician an added advantage by bonding to the tooth structure. Three main types of conventional "cements" are commonly used, zinc phosphate and the polyelectrolyte cements polycarboxylate, and glass ionomer cements. Because of its long history of successful clinical use, zinc phosphate is considered the gold standard against which all other luting agents are compared because of its long clinical history of successful use. Currently, two additional types of luting agents have gained considerable popularity. These include the resin-modified glass ionomer cements and resin cements. The resin cement category includes light-cured, dual-cured and chemically cured agents. The purpose of this article is to discuss the ideal attributes of a luting agent and make clinical recommendations for their use.

  14. 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.

  15. 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. PMID:26505487

  16. 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.

  17. 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.

  18. Localization of hydrogen peroxide accumulation and diamine oxidase activity in pea root nodules under aluminum stress.

    PubMed

    Sujkowska-Rybkowska, Marzena; Borucki, Wojciech

    2014-02-01

    Aluminum (Al) is one of the environmental stressors that induces formation of reactive oxygen species (ROS) in plants. Hydrogen peroxide (H2O2) and H2O2-generated apoplast diamine oxidase (DAO) activity were detected cytochemically via transmission electron microscopy (TEM), in pea (Pisum sativum L.) root nodules exposed to high (50 μM AlCl3, for 2 and 24h) Al stress. The nodules were shown to respond to Al stress by disturbances in infection thread (IT) growth, bacteria endocytosis, premature degeneration of bacteroidal tissue and generation of H2O2 in nodule apoplast. Large amounts of peroxide were found at the same sites as high DAO activity under Al stress, suggesting that DAO is a major source of Al-induced peroxide accumulation in the nodules. Peroxide distribution and DAO activity in the nodules of both control plants and Al-treated ones were typically found in the plant cell walls, intercellular spaces and infection threads. However, 2 h Al treatment increased DAO activity and peroxide accumulation in the nodule apoplast and bacteria within threads. A prolonged Al treatment (24 h) increased the H2O2 content and DAO activity in the nodule apoplast, especially in the thread walls, matrix and bacteria within infection threads. In addition to ITs, prematurely degenerated bacteroids, which occurred in response to Al, were associated with intense staining for H2O2 and DAO activity. These results suggest the involvement of DAO in the production of a large amount of H2O2 in the nodule apoplast under Al stress. The role of reactive oxygen species in pea-Rhizobium symbiosis under Al stress is discussed. PMID:24246127

  19. 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.

  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. DTI-015 produces cures in T9 gliosarcoma.

    PubMed

    Pietronigro, Dennis; Drnovsky, Frank; Cravioto, Humberto; Ransohoff, Joseph

    2003-01-01

    DTI-015 (BCNU in 100% ethanol) utilizes solvent-facilitated perfusion for the intratumoral treatment of gliomas. The water-miscible organic solvent vehicle, ethanol, facilitates a rapid and thorough saturation of the'tumor with the dissolved anticancer agent, BCNU. Rats bearing established intracranial T9 gliosarcoma tumors received no treatment (group 1), a single intratumoral injection of ethanol vehicle (group 2) or DTI-015 (5 mg/kg BCNU) (group 3), or a single intratumoral injection of DTI-015 followed by systemic BCNU (group 4). Ethanol alone (n=13) had no effect on survival; MST=17 days compared to 18 days for untreated controls (n=35). DTI-015 (n=45) produced an ILS of 417% (MST=93) and 472% (MST=103) when combined with systemic BCNU (n=14). Overall, 24 of 59 rats receiving DTI-015 were judged to be cured, with 20 living a normal life span of 600 to 700 days, and 4 rats sacrificed healthy at 121, 135, 307, and 384 days post DTI-015 with no evidence of viable T9 tumor. Histology demonstrated that DTI-015 totally eradicated the T9 tumors in animals living a normal life span. The results demonstrate that a single injection of DTI-015 produces a 40% cure rate in rats bearing established intracranial T9 tumors.

  2. 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

  3. 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. PMID:27652207

  4. 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.

  5. Analysis of cure in composites processing

    NASA Technical Reports Server (NTRS)

    Aylward, L.; Roylance, D.; Douglas, C.

    1984-01-01

    Finite element analysis is a general numerical tool for solving the field equations of engineering practice, and this paper demonstrates its use in modeling the nonisothermal cure of pultruded composite material. A very simple grid is used in this case to model a narrow strip of material, and this grid is then solved using a time-stepping transient algorithm to simulate the passage of the strip along the pultruder die. As time proceeds, heat is conducted into the strip from the heated boundaries at the die walls, and cure proceeds at a rate dependent on the local temperature. The computer model can be used to minimize the time needed for sufficient cure, and helps avoid such processing errors as undercure or thermal degradation.

  6. Adhesive curing through low-voltage activation

    NASA Astrophysics Data System (ADS)

    Ping, Jianfeng; Gao, Feng; Chen, Jian Lin; Webster, Richard D.; Steele, Terry W. J.

    2015-08-01

    Instant curing adhesives typically fall within three categories, being activated by either light (photocuring), heat (thermocuring) or chemical means. These curing strategies limit applications to specific substrates and can only be activated under certain conditions. Here we present the development of an instant curing adhesive through low-voltage activation. The electrocuring adhesive is synthesized by grafting carbene precursors on polyamidoamine dendrimers and dissolving in aqueous solvents to form viscous gels. The electrocuring adhesives are activated at -2 V versus Ag/AgCl, allowing tunable crosslinking within the dendrimer matrix and on both electrode surfaces. As the applied voltage discontinued, crosslinking immediately terminated. Thus, crosslinking initiation and propagation are observed to be voltage and time dependent, enabling tuning of both material properties and adhesive strength. The electrocuring adhesive has immediate implications in manufacturing and development of implantable bioadhesives.

  7. Outdoor durability of radiation-cured coatings

    SciTech Connect

    Holman, R.; Kennedy, R.

    1997-12-31

    Radiation cured coatings are used almost exclusively on products which have little or no exposure to moisture or the weather; inks, furniture varnishes, floor varnishes and coatings for electronic components. However there is considerable interest in being able to use this technology in exterior environments as a substitute for solvent-borne coatings. A 3-year study examining the possible reasons for the poor durability of radiation curable coatings showed that the resistance of the monomers and oligomers to hydrogen abstraction was crucially important, and the water permeability of the cured coating influenced the long-term adhesion performance. The project concluded that with the appropriate combination of curing technology and monomer/oligomer selection, the prospects of UV curable coatings for outdoor exposure are very encouraging.

  8. Adhesive curing through low-voltage activation

    PubMed Central

    Ping, Jianfeng; Gao, Feng; Chen, Jian Lin; Webster, Richard D.; Steele, Terry W. J.

    2015-01-01

    Instant curing adhesives typically fall within three categories, being activated by either light (photocuring), heat (thermocuring) or chemical means. These curing strategies limit applications to specific substrates and can only be activated under certain conditions. Here we present the development of an instant curing adhesive through low-voltage activation. The electrocuring adhesive is synthesized by grafting carbene precursors on polyamidoamine dendrimers and dissolving in aqueous solvents to form viscous gels. The electrocuring adhesives are activated at −2 V versus Ag/AgCl, allowing tunable crosslinking within the dendrimer matrix and on both electrode surfaces. As the applied voltage discontinued, crosslinking immediately terminated. Thus, crosslinking initiation and propagation are observed to be voltage and time dependent, enabling tuning of both material properties and adhesive strength. The electrocuring adhesive has immediate implications in manufacturing and development of implantable bioadhesives. PMID:26282730

  9. 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.

  10. 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).

  11. 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. PMID:24986185

  12. 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.

  13. Composite cure and pulp-cell cytotoxicity associated with LED curing lights.

    PubMed

    Yap, Adrian U J; Saw, T Y; Cao, T; Ng, Mary M L

    2004-01-01

    This study compared the cure and pulp-cell cytotoxicity of composites polymerized with light-emitting diode (LED) and halogen-based light curing units. A mini-filled resin composite (Tetric Ceram, Vivadent), two LED (E-light [EL], GC and Freelight [FL], 3M-ESPE), a conventional halogen (Max [MX], Dentsply) and a high-intensity halogen light (Astralis 10 [AS], Vivadent) were evaluated. Cure associated with the different lights was determined by measuring the top and bottom surface hardness (KHN; n = 5) of 2-mm thick specimens using a digital microhardness tester (load = 500 gf; dwell time = 15 seconds). Pulp-cell cytotoxicity was assessed using a direct contact method involving incisor tooth slices dissected from 28-day old Wistar rats maintained in Dulbecco's Modified Eagle's Medium (DMEM) and 1% agarose. The bottom surfaces of the cured composite specimens (7-mm diameter and 2-mm deep) were placed in contact with the openings of each tooth slice. After incubation in 5% CO2 atmosphere at 37 degrees C for 48 hours, the tooth slices were fixed, demineralized and processed for histological examination. Pulp fibroblasts and odontoblasts were counted histomorphometrically at 400x magnification within a 1500 microm2 area using a computerized micro-imaging system. Eighteen readings were obtained for each curing light. Data was subjected to ANOVA/Scheffe's test and Pearson's correlation at significance level 0.05 and 0.01, respectively. At the top surfaces, the cure with AS was significantly greater than the other curing lights, with MX and FL being significantly greater than EL. At the bottom surfaces, MX, AS and FL had significantly better cure than EL. Specimens cured with MX were less cytotoxic than those polymerized with other curing lights. Specimens cured with AS and EL were significantly less cytotoxic than FL. Composite cure and cytotoxicity associated with LED lights is device dependent. Composite cure was not correlated to pulp-cell cytotoxicity. The response of

  14. Providing a cure for beta thalassaemia major.

    PubMed

    Chan, L L; Lin, H P; Ariffn, W A; Ariffin, H

    2001-12-01

    The current treatment options for beta thalassaemia major patients include conservative treatment with blood cell transfusions and iron chelation or stem cell transplantation. Regular blood transfusions inevitably lead to multi-organ haemosiderosis and are attended by risks of blood-borne infections. Results from stem cell transplantation are good and suggest that this should be offered as first line therapy when a matched sibling donor is available because the patient is often cured and able to live a normal life. Of 38 Malaysian children who underwent bone marrow or cord blood transplantations using matched sibling donors, 29 (76%) are now cured.

  15. Destructive weighted Poisson cure rate models.

    PubMed

    Rodrigues, Josemar; de Castro, Mário; Balakrishnan, N; Cancho, Vicente G

    2011-07-01

    In this paper, we develop a flexible cure rate survival model by assuming the number of competing causes of the event of interest to follow a compound weighted Poisson distribution. This model is more flexible in terms of dispersion than the promotion time cure model. Moreover, it gives an interesting and realistic interpretation of the biological mechanism of the occurrence of event of interest as it includes a destructive process of the initial risk factors in a competitive scenario. In other words, what is recorded is only from the undamaged portion of the original number of risk factors.

  16. 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.

  17. 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.

  18. Pharmacodynamics and pharmacokinetics of SQ109, a new diamine-based antitubercular drug.

    PubMed

    Jia, Lee; Tomaszewski, Joseph E; Hanrahan, Colleen; Coward, Lori; Noker, Patricia; Gorman, Gregory; Nikonenko, Boris; Protopopova, Marina

    2005-01-01

    SQ109 is a novel [1,2]-diamine-based ethambutol (EMB) analog developed from high-throughput combinatorial screening. The present study aimed at characterizing its pharmacodynamics and pharmacokinetics. The antimicrobial activity of SQ109 was confirmed in vitro (Mycobacterium tuberculosis-infected murine macrophages) and in vivo (M. tuberculosis-infected C57BL/6 mice) and compared to isoniazid (INH) and EMB. SQ109 showed potency and efficacy in inhibiting intracellular M. tuberculosis that was similar to INH, but superior to EMB. In vivo oral administration of SQ109 (0.1-25 mg kg(-1) day(-1)) to the mice for 28 days resulted in dose-dependent reductions of mycobacterial load in both spleen and lung comparable to that of EMB administered at 100 mg kg(-1) day(-1), but was less potent than INH at 25 mg kg(-1) day(-1). Monitoring of SQ109 levels in mouse tissues on days 1, 14 and 28 following 28-day oral administration (10 mg kg(-1) day(-1)) revealed that lungs and spleen contained the highest concentration of SQ109, at least 10 times above its MIC. Pharmacokinetic profiles of SQ109 in mice following a single administration showed its C(max) as 1038 (intravenous (i.v.)) and 135 ng ml(-1) (p.o.), with an oral T(max) of 0.31 h. The elimination t(1/2) of SQ109 was 3.5 (i.v.) and 5.2 h (p.o.). The oral bioavailability was 4%. However, SQ109 displayed a large volume of distribution into various tissues. The highest concentration of SQ109 was present in lung (>MIC), which was at least 120-fold (p.o.) and 180-fold (i.v.) higher than that in plasma. The next ranked tissues were spleen and kidney. SQ109 levels in most tissues after a single administration were significantly higher than that in blood. High tissue concentrations of SQ109 persisted for the observation period (10 h). This study demonstrated that SQ109 displays promising in vitro and in vivo antitubercular activity with favorable targeted tissue distribution properties.

  19. Cure-rate data for silicone adhesive

    NASA Technical Reports Server (NTRS)

    Clatterbuck, C.; Fisher, A.

    1978-01-01

    Report describes work with concentrations down to 0.07 percent and is useful when applying adhesives in terrestrial and space applications. Cured Silicone retains low-outgassing properties as well as its snap, elongation, and resilience. Tests for hardness of silicone material also showed good results. No gross hysteresis observable on recovery from stretching nor was there any decrease in hardness.

  20. Adhesive curing options for photonic packaging

    NASA Astrophysics Data System (ADS)

    Martin, Steven C.; Hubert, Manfred; Tam, Robin

    2002-06-01

    Varying the intensity of illumination used to cure photoactivated adhesives has been applied in medical and dental applications to improve the performance of polymer materials. For example, it has been observed that dental polymer composite materials express reduced shrinkage, important for durability of non-amalgam restorations, by introducing a phased time-intensity cure schedule. This work identified that curing conditions could influence the final properties of materials, and suggested the possibility of extending the characteristics that could be influenced beyond shrinkage to humidity resistance, Tg, outgassing and other important material properties. Obviously, these results have important ramifications for the photonic industry, with current efforts focused on improved manufacturing techniques. Improvement in low cost packaging solutions, including adhesives, will have to be made to bring the component cost down to address the needs of Metro and similar markets. However, there are perceived problems with the widespread use of adhesives, the most prevalent of these involving long term durability of the bond. Devices are typically aligned to sub-micron precision using active feedback and then must be locked in position to maintain performance. In contrast to traditional fastening methods, adhesive bonding is a highly attractive option due to the ease of deployment, lower equipment costs, and improved flexibility. Moreover, using methods analogous to those employed in dental applications, materials properties of photonic adhesives may be tailored using a programmed cure approach.

  1. 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 Student Conduct"…

  2. 7 CFR 30.10 - Cure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Cure. 30.10 Section 30.10 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.10...

  3. 7 CFR 30.10 - Cure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.10 Cure... done under such conditions as will permit of the chemical and physiological changes necessary to develop the desired quality of color in tobacco....

  4. 7 CFR 30.10 - Cure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.10 Cure... done under such conditions as will permit of the chemical and physiological changes necessary to develop the desired quality of color in tobacco....

  5. 7 CFR 30.10 - Cure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.10 Cure... done under such conditions as will permit of the chemical and physiological changes necessary to develop the desired quality of color in tobacco....

  6. Heat-cured silicone bimaxillary mouthguard.

    PubMed

    Milward, P J; Jagger, R G

    1995-10-01

    A laboratory procedure for the construction of a heat-cured, silicone, custom-made bimaxillary mouthguard for contact sports is described. Contours and vertical dimension are easier to control than with the conventional thermoformed product, and there is no danger of injury from contact between the maxillary and mandibular components.

  7. 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.

  8. Human Toll-like Receptor (TLR) 8-Specific Agonistic Activity in Substituted Pyrimidine-2,4-diamines.

    PubMed

    Beesu, Mallesh; Salyer, Alex C D; Trautman, Kathryn L; Hill, Justin K; David, Sunil A

    2016-09-01

    Activation of human toll-like receptor-8 (TLR8) evokes a distinct cytokine profile favoring the generation of Type 1 helper T cells. A multiplexed high-throughput screen had led to the identification of N(4)-butyl-5-iodo-6-methylpyrimidine-2,4-diamine as a pure TLR8 agonist, and a detailed structure-activity relationship study of this chemotype was undertaken. A butyl substituent at N(4) was optimal, and replacement of the 5-iodo group with chloro, bromo, or fluoro groups led to losses in potency, as did the introduction of aromatic bulk. Drawing from our previous structure-based design, several 5-alkylamino derivatives were evaluated. Significant enhancement of potency was achieved in 5-(4-aminobutyl)-N(4)-butyl-6-methylpyrimidine-2,4-diamine. This compound potently induced Th1-biasing IFN-γ and IL-12 in human blood, but lower levels of the proinflammatory cytokines IL-1β, IL-6, and IL-8. These results suggest that the inflammatory and reactogenic propensities of this compound could be considerably more favorable than other TLR8 agonists under evaluation. PMID:27513008

  9. Insights into the Self-assembly of Two Diamine Derivatives Low Molecular Mass Organogelators in Quasi-solid-state Electrolytes

    NASA Astrophysics Data System (ADS)

    Mo, Shu-Fan; Zhang, Bing; Zhou, Kai-Xuan; Yao, Jian-Xi; Dai, Song-Yuan

    2016-05-01

    Electrolyte materials are the key components in dye-sensitized solar cells and are very crucial to the performance and long-term stability of the cells. The diamide derivatives have been proved in our lab to be effective to improve the stability of the traditional liquid electrolyte as low molecular mass organogelator (LMOGs). Our previous experiments and simulations indicated that the relationship between the morphology of the electrolyte and the self-assembly of the LMOGs. In the current study, the self-assembly of two diamine derivatives (N,N'-1,8-octanediylbis-dodecanamide and N,N'-1,9-nonanediylbis-dodecanamide) has been investigated and characterized using molecular dynamics. Although the structure of the two these molecules is only different in one methylene, the simulations revealed that the self-assembly patterns of the two diamine derivatives are quite different. The differences seems to be suitable to explain the diverse morphologies formed by the assembly of the LMOGs.

  10. Ethylene polymerization initiated by tertiary diamine/n-butyllithium complexes: an interpretation from density functional theory study.

    PubMed

    Li, Huayi; Zhang, Liaoyun; Wang, Zhi-Xiang; Hu, Youliang

    2010-02-25

    The mechanism of ethylene insertions into eight tertiary diamine/n-butyllithium complexes has been studied at the BLYP/DNP level. In contrast to the cationic coordination polymerization in which a strong coordination complex between ethylene and the metal center is formed prior to ethylene insertion, there is only a weak van der Waals complex between ethylene and tertiary diamine/n-butyllithium complex. After crossing a four-membered-ring transition state, ethylene inserts into the Li-C bond. The insertion barriers for the eight reactions are in the range of 6.9-11.0 kcal/mol, comparable to those of ethylene cationic coordination polymerizations. However, the polymerization activities of ethylene anionic polymerizations are much lower than those of cationic coordination polymerizations. Comparing the energy profiles of these ethylene anionic polymerizations with those of cationic coordination polymerizations, it can be found that the transition states in the ethylene anionic polymerizations are higher in energy than the reactants, while the transition states in ethylene cationic coordination polymerizations are lower than the reactants. Therefore, ethylene anionic polymerizations need additional energy to climb the energy barriers, while the energies for overcoming the transition states in the cationic coordination polymerizations can be obtained from reactants that are higher in energy than the reactants. We reason the differences in their energy profiles could be one of the reasons for the lower activity of ethylene anionic polymerization than ethylene cationic coordination polymerization despite their comparable insertion barriers.

  11. Direct anti-HCV agents.

    PubMed

    Zhang, Xingquan

    2016-01-01

    Unlike human immunodeficiency virus (HIV) and hepatitis B virus (HBV), hepatitis C virus (HCV) infection is a curable disease. Current direct antiviral agent (DAA) targets are focused on HCV NS3/4A protein (protease), NS5B protein (polymerase) and NS5A protein. The first generation of DAAs includes boceprevir and telaprevir, which are protease inhibitors and were approved for clinical use in 2011. The cure rate for genotype 1 patients increased from 45% to 70% when boceprevir or telaprevir was added to standard PEG-IFN/ribavirin. More effective and less toxic second generation DAAs supplanted these drugs by 2013. The second generation of DAAs includes sofosbuvir (Sovaldi), simeprevir (Olysio), and fixed combination medicines Harvoni and Viekira Pak. These drugs increase cure rates to over 90% without the need for interferon and effectively treat all HCV genotypes. With these drugs the "cure HCV" goal has become a reality. Concerns remain about drug resistance mutations and the high cost of these drugs. The investigation of new HCV drugs is progressing rapidly; fixed dose combination medicines in phase III clinical trials include Viekirax, asunaprevir+daclatasvir+beclabuvir, grazoprevir+elbasvir and others.

  12. Direct anti-HCV agents

    PubMed Central

    Zhang, Xingquan

    2015-01-01

    Unlike human immunodeficiency virus (HIV) and hepatitis B virus (HBV), hepatitis C virus (HCV) infection is a curable disease. Current direct antiviral agent (DAA) targets are focused on HCV NS3/4A protein (protease), NS5B protein (polymerase) and NS5A protein. The first generation of DAAs includes boceprevir and telaprevir, which are protease inhibitors and were approved for clinical use in 2011. The cure rate for genotype 1 patients increased from 45% to 70% when boceprevir or telaprevir was added to standard PEG-IFN/ribavirin. More effective and less toxic second generation DAAs supplanted these drugs by 2013. The second generation of DAAs includes sofosbuvir (Sovaldi), simeprevir (Olysio), and fixed combination medicines Harvoni and Viekira Pak. These drugs increase cure rates to over 90% without the need for interferon and effectively treat all HCV genotypes. With these drugs the “cure HCV” goal has become a reality. Concerns remain about drug resistance mutations and the high cost of these drugs. The investigation of new HCV drugs is progressing rapidly; fixed dose combination medicines in phase III clinical trials include Viekirax, asunaprevir+daclatasvir+beclabuvir, grazoprevir+elbasvir and others. PMID:26904396

  13. 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.

  14. Time-temperature profiles of post-cure composite ovens.

    PubMed

    Loza-Herrero, M A; Rueggeberg, F A

    1998-01-01

    Previous research indicates that there are improved physical properties resulting from post-cure heating of light-activated resin composite. Currently, a large variety of commercial devices and techniques are used for post-cure heating. This study determined differences among the time-temperature profiles of selected commercial post-cure devices. It also compared the biaxial flexure strength of resin composite which was post-cure heated in each device.

  15. 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.

  16. 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}.

  17. Kinetics of conversion of two dual-cured adhesive systems.

    PubMed

    Faria-e-Silva, André Luis; Casselli, Denise Sá Maia; Lima, Giana Silveira; Ogliari, Fabrício Aulo; Piva, Evandro; Martins, Luis Roberto Marcondes

    2008-09-01

    The aim of this study was to evaluate the kinetics of conversion of Scotchbond Multi-purpose Plus (3M ESPE, St Paul, MN) and Prime&Bond NT (Dentsply De Trey, Konstanz, Germany) used in light-cured, self-cured, or dual-cured versions. The adhesive systems were used in the light-cured version (without the use of chemical initiator) or mixed with its respective chemical initiator either with light activation (dual-cured) or not (self-cured). The degree of conversion (DC) was monitored as a function of time during 5 minutes with a Fourier transform infrared spectrometer equipped with an attenuated total reflectance device. Light-cured and dual-cured modes of Scotchbond Multi-purpose Plus presented the highest DC at 5 minutes. The addition of the self-cure activator (dual-cured mode) to Prime&Bond NT reduced the DC. For the self-cured versions, only the Scotchbond Multi-purpose Plus presented any polymerization reaction at 5 minutes. For the two bonding systems tested, it appears that light curing of the adhesive is important in order to reach a high DC in the first moments after the bonding procedure.

  18. 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....

  19. 7 CFR 29.6002 - Air-cured.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 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....

  20. 7 CFR 29.6002 - Air-cured.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 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, 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...

  2. 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...

  3. 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...

  4. 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...

  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 30.11 - Flue-cure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...-cure. To cure tobacco under artificial atmospheric conditions by a process of regulating the heat and... 7 Agriculture 2 2012-01-01 2012-01-01 false Flue-cure. 30.11 Section 30.11 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  7. 7 CFR 30.11 - Flue-cure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...-cure. To cure tobacco under artificial atmospheric conditions by a process of regulating the heat and... 7 Agriculture 2 2011-01-01 2011-01-01 false Flue-cure. 30.11 Section 30.11 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  8. 7 CFR 30.11 - Flue-cure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...-cure. To cure tobacco under artificial atmospheric conditions by a process of regulating the heat and... 7 Agriculture 2 2014-01-01 2014-01-01 false Flue-cure. 30.11 Section 30.11 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  9. 7 CFR 30.11 - Flue-cure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...-cure. To cure tobacco under artificial atmospheric conditions by a process of regulating the heat and... 7 Agriculture 2 2013-01-01 2013-01-01 false Flue-cure. 30.11 Section 30.11 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  10. 7 CFR 30.11 - Flue-cure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...-cure. To cure tobacco under artificial atmospheric conditions by a process of regulating the heat and... 7 Agriculture 2 2010-01-01 2010-01-01 false Flue-cure. 30.11 Section 30.11 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  11. Hematopoietic stem cell transplantation for HIV cure.

    PubMed

    Kuritzkes, Daniel R

    2016-02-01

    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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Contactless optoelectronic technique for monitoring epoxy cure.

    PubMed

    Cusano, A; Buonocore, V; Breglio, G; Calabrò, A; Giordano, M; Cutolo, A; Nicolais, L

    2000-03-01

    We describe a novel noninvasive optical technique to monitor the refractive-index variation in an epoxy-based resin that is due to the polymerization process. This kind of resin is widely used in polymer matrix composites. It is well known that the process of fabricating a thermoset-based composite involves mass and heat transfer coupled with irreversible chemical reactions that induce physical changes. To improve the quality and the reliability of these materials, monitoring the cure and optimization of the manufacturing process are of key importance. We discuss the basic operating principles of an optical system based on angle deflection measurements and present typical cure-monitoring results obtained from optical characterization. The method provides a flexible, high-sensitivity, material-independent, low-cost, noninvasive tool for monitoring real-time refractive-index variation.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Using Sex to Cure the Genome

    PubMed Central

    Rocha, Eduardo P. C.

    2016-01-01

    The diversification of prokaryotes is accelerated by their ability to acquire DNA from other genomes. However, the underlying processes also facilitate genome infection by costly mobile genetic elements. The discovery that cells can uptake DNA by natural transformation was instrumental to the birth of molecular biology nearly a century ago. Surprisingly, a new study shows that this mechanism could efficiently cure the genome of mobile elements acquired through previous sexual exchanges. PMID:26987049

  2. 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.

  3. 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).

  4. Self-assembly of alpha,omega-aliphatic diamines on Ag nanoparticles as an effective localized surface plasmon nanosensor based in interparticle hot spots.

    PubMed

    Guerrini, Luca; Izquierdo-Lorenzo, Irene; Garcia-Ramos, José V; Domingo, Concepción; Sanchez-Cortes, Santiago

    2009-09-14

    The adsorption and self-assembly of alpha,omega-aliphatic diamines on silver nanoparticles is studied in this work by surface-enhanced Raman scattering (SERS) spectroscopy and plasmon resonance. These bifunctional diamines can act as linkers of metal nanoparticles (NPs) inducing the formation of hot spots (HS), i.e. interparticle junctions or gaps between metal NPs, which are points where a huge intensification of the electromagnetic field occurs. In addition, the dicationic nature of these diamines leads to the formation of cavities just at the induced hot spots which can be applied to molecular recognition of analytes. The influence of the surface coverage and the aliphatic chain length in diamines on their self-assembly was tested by the vibrational spectra and correlated to the different plasmon resonances of the dimers detected in the extinction spectra. These factors can be used for tuning the plasmon resonance of dimers formed by two metal nanoparticles where interparticle hot spots are formed. Finally, the analytical potential of these functionalized Ag nanoparticles is demonstrated for the trace detection of the pesticide aldrin.

  5. 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

  6. Hepatitis C Virus Treatment: Is It Possible To Cure All Hepatitis C Virus Patients?

    PubMed Central

    Muir, Andrew J.; Naggie, Susanna

    2016-01-01

    The recent advances in hepatitis C virus (HCV) therapeutics have brought combinations of direct acting antiviral medications that offer interferon-free, well-tolerated regimens with sustained virologic response rates greater than 90% in clinical trials for many patient groups. The successes have prompted discussions regarding cure for all patients. These regimens have already demonstrated the ability to cure previously challenging patient groups, including human immunodeficiency virus–HCV coinfection, decompensated cirrhosis, and post-liver transplantation. Limitations exist in the current portfolio of agents, with suboptimal outcomes for genotype 3 and limited data in genotypes 5 and 6. More data are urgently needed in patients with chronic kidney disease and in children. With ongoing developments, highly effective regimens for all these patient groups are within reach. To deliver HCV treatment throughout the world and particularly in low-and middle-income countries, regimens need to be affordable but also pan-genotypic, well-tolerated, and delivered once daily for 4–8 weeks. With such a regimen, cure for all patients would then hinge on the ability to identify patients with HCV infection and deliver treatment within their communities. This review will discuss the strategies that will be necessary to realize this opportunity to cure all persons with HCV infection. PMID:26192145

  7. 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

  8. Prevention of Root Caries: A Literature Review of Primary and Secondary Preventive Agents

    PubMed Central

    Gluzman, Rima; Frey, Barbara J.; McGowan, Richard

    2012-01-01

    Purpose This literature review summarizes the effectiveness of the seven leading root caries preventive agents and provides recommendations for use of those agents in clinical practice with older adults and vulnerable elderly. Method Studies were eligible if they assessed the effectiveness of either fluoride, chlorhexidine, xylitol, amorphous calcium phosphate, sealants, saliva stimulators, or silver diamine fluoride to prevent/control root caries in an English-language articles between 1979–2010 Results In the 31 eligible studies, the most effective primary (1°) prevention agents had reductions in RC incidence ranging from 72% to nearly 200% as compared to a placebo while for secondary (2°) prevention, the best agents demonstrated arrest rates between 67–80%. Conclusion For 1° prevention of root caries the recommended ‘best choice’ is a 38% Silver Diamine Fluoride solution professionally applied annually, while for the 2° prevention of root caries, the recommended ‘best choice’ is a 22,500 ppm Sodium Fluoride varnish professionally applied every 3 months. PMID:23600985

  9. 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.

  10. 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

  11. The effectiveness of cure of LED and halogen curing lights at varying cavity depths.

    PubMed

    Soh, M S; Yap, Adrian U J; Siow, K S

    2003-01-01

    This study compared the effectiveness of cure of two LED (light-emitting diodes) lights (Elipar FreeLight [FL], 3M-ESPE and GC e-Light [EL], GC) to conventional (Max [MX] (control), Dentsply-Caulk), high intensity (Elipar TriLight [TL], 3M-ESPE) and very high intensity (Astralis 10 [AS], Ivoclar Vivadent) halogen lights at varying cavity depths. Ten light curing regimens were investigated. They include: FL1-400 mW/cm2 [40 seconds], FL2-0-400 mW/cm2 [12 seconds] --> 400 mW/cm2 [28 seconds], EL1-750 mW/cm2 [10 pulses x 2 seconds], EL2-350 mW/cm2 [40 seconds], EL3-600 mW/cm2 [20 seconds], EL4-0-600 mW/cm2 [20 seconds] --> 600 mW/cm2 [20 seconds], TL1-800 mW/cm2 [40 seconds], TL2-100-800 mW/cm2 [15 seconds] --> 800 mW/cm2 [25 seconds], AS1-1200 mW/cm2 [10 seconds], MX-400 mW/cm2 [40 seconds]. The effectiveness of cure of the different modes was determined by measuring the top and bottom surface hardness (KHN) of 2-mm, 3-mm and 4-mm thick composite (Z100, [3M-ESPE]) specimens using a digital microhardness tester (n = 5, load = 500 g; dwell time = 15 seconds). Results were analyzed using ANOVA/Scheffe's post-hoc test and Independent Samples t-Test (p < 0.05). For all lights, effectiveness of cure was found to decrease with increased cavity depths. The mean hardness ratio for all curing lights at a depth of 2 mm was found to be greater than 0.80 (the accepted minimum standard). At 3 mm, all halogen lights produced a hardness ratio greater than 0.80 but some LED light regimens did not; and at a depth of 4 mm, the mean hardness ratio observed with all curing lights was less than 0.80. Significant differences in top and bottom KHN values were observed among different curing regimens for the same light and between LED and halogen lights. While curing with most modes of EL resulted in significantly lower top and bottom KHN values than the control (MX) at all depths, the standard mode of FL resulted in significantly higher top and bottom KHN at a depth of 3 mm and 4 mm. The

  12. The hepatitis C genotype 1 paradox: cost per treatment is increasing, but cost per cure is decreasing.

    PubMed

    Shafran, Stephen D

    2015-01-01

    Significant attention has been focused on the perceived increase in the cost of antiviral treatment for hepatitis C genotype 1 infection since the approval of the first direct-acting antiviral agents in 2011. Using Canadian list prices, the present analysis points out a paradox: while the cost per antiviral regimen is increasing, the cost per cure is decreasing, especially with interferon-free therapy. In a publicly funded health care system, the lowest cost per cure is a more valuable measure of value for public money than the cost per regimen. PMID:25706574

  13. Devices and topical agents for rosacea management.

    PubMed

    Mansouri, Yasaman; Goldenberg, Gary

    2014-07-01

    Rosacea is a chronic inflammatory disease that predominantly affects facial skin in light-skinned individuals and can be divided into 4 subtypes. Patients can display signs of more than 1 subtype. Diffuse facial erythema is a common finding in rosacea patients and can lead to persistent erythema. Although there is no cure for rosacea, reduction of signs and symptoms can be achieved via various treatment modalities. This article reviews devices and topical agents currently available for the management of rosacea. PMID:25101340

  14. 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.

  15. Antiparasitic agents.

    PubMed

    Rosenblatt, J E

    1992-03-01

    In recent years, introduction of new and more effective agents has improved the overall therapy for parasitic infections. This field, however, is still plagued by numerous problems, including the development of resistance to antimicrobial agents (especially with malaria), unavailability of agents in the United States or lack of approval by the Food and Drug Administration, and major toxicities or lack of experience in pregnant women and children, which limits use in these groups of patients. Widespread resistance of Plasmodium falciparum to chloroquine and other agents has complicated the treatment and prophylaxis of this type of malaria. A combination of quinine and Fansidar is usually effective oral therapy for falciparum malaria; quinidine may be administered if intravenous therapy is needed. Mefloquine, which is currently recommended for prophylaxis against chloroquine-resistant P. falciparum, is also effective for single-dose oral treatment, although this regimen has not yet been approved by the Food and Drug Administration. Metronidazole has been widely used for treatment of gastroenteritis due to Entamoeba histolytica and Giardia lamblia (not approved by the Food and Drug Administration for the latter) and is considered safe and effective. A new macrolide, azithromycin, has been reported to be effective for cryptosporidiosis in experimental animals; currently, no effective therapy is available for human infections. Combinations of sulfonamides with other antifolates, trimethoprim or pyrimethamine, are recommended therapy for Pneumocystis carinii pneumonia or toxoplasmosis, respectively. Therapies for the various types of leishmaniasis and trypanosomiasis are complex, often toxic, and often of limited efficacy. The benzimidazoles are effective for roundworm infections, although thiabendazole has severe toxic effects. The recent introduction of ivermectin has revolutionized the treatment and control of onchocerciasis. Another relatively new agent, praziquantel

  16. Argon Ion Laser Polymerized Acrylic Resin: A Comparative Analysis of Mechanical Properties of Laser Cured, Light Cured and Heat Cured Denture Base Resins

    PubMed Central

    Murthy, S Srinivasa; Murthy, Gargi S

    2015-01-01

    Background: Dentistry in general and prosthodontics in particular is evolving at greater pace, but the denture base resins poly methyl methacrylate. There has been vast development in modifying chemically and the polymerization techniques for better manipulation and enhancement of mechanical properties. One such invention was introduction of visible light cure (VLC) denture base resin. Argon ion lasers have been used extensively in dentistry, studies has shown that it can polymerize restorative composite resins. Since composite resin and VLC resin share the same photo initiator, Argon laser is tested as activator for polymerizing VLC resin. In the Phase 1 study, the VLC resin was evaluated for exposure time for optimum polymerization using argon ion laser and in Phase 2; flexural strength, impact strength, surface hardness and surface characteristics of laser cured resin was compared with light cure and conventional heat cure resin. Materials and Methods: Phase 1; In compliance with American Dental Association (ADA) specification no. 12, 80 samples were prepared with 10 each for different curing time using argon laser and evaluated for flexural strength on three point bend test. Results were compared to established performance requirement specified. Phase 2, 10 specimen for each of the mechanical properties (30 specimen) were polymerized using laser, visible light and heat and compared. Surface and fractured surface of laser, light and heat cured resins were examined under scanning electron microscope (SEM). Results: In Phase 1, the specimen cured for 7, 8, 9 and 10 min fulfilled ADA requirement. 8 min was taken as suitable curing time for laser curing. Phase 2 the values of mechanical properties were computed and subjected to statistical analysis using one-way ANOVA and Tukey post-hoc test. The means of three independent groups showed significant differences between any two groups (P < 0.001). Conclusion: Triad VLC resin can be polymerized by argon ion laser with

  17. Structural characterization of two benzene-1,2-di-amine complexes of zinc chloride: a mol-ecular compound and a co-crystal salt.

    PubMed

    Zick, Patricia L; Geiger, David K

    2016-07-01

    The structures of two zinc complexes containing bidentate benzene-1,2-di-amine ligands are reported. (Benzene-1,2-di-amine-κ(2) N,N')di-chloro-idozinc, [ZnCl2(C6H8N2)], (I), displays a distorted tetra-hedral coordination sphere for the metal cation. The di-amine ligand and the Zn atom reside on a crystallographic mirror plane. In the 1:1 co-crystal salt trans-di-aqua-bis-(4,5-di-methyl-benzene-1,2-di-amine-κ(2) N,N')zinc chloride-4,5-di-methyl-benzene-1,2-di-amine (1/1), [Zn(C8H12N2)2(H2O)2]Cl2·2C8H12N2, (II), the zinc(II) complex cation exhibits a tetra-gonally distorted octa-hedral coordination sphere. The Zn atom sits on a crystallographically imposed inversion center and the di-amine ligands are tilted 30.63 (6)° with respect to the ZnN4 plane. Both complexes exhibit extensive hydrogen bonding. In (I), a stacked-sheet extended structure parallel to (101) is observed. In (II), the co-crystallized di-amine is hydrogen-bonded to the complex cation via O-H⋯N and N-H⋯N linkages. These units are in turn linked into planes along (200) by O-H⋯Cl and N-H⋯Cl hydrogen bonds. PMID:27555958

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

    PubMed

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

    2012-02-01

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

  19. Effect of delayed light curing of a resin composite on marginal integrity in cylindrical dentine cavities.

    PubMed

    Manabe, A; Debari, K; Itoh, K; Hisamitsu, H; Wakumoto, S

    1993-12-01

    The effect of delayed light curing of resin composite on marginal adaptation has been examined by measuring the wall-to-wall polymerization contraction gap when using a commercial resin composite together with experimental dentine bonding systems to restore cylindrical preparations in dentine. Morphological changes in dentine during dentine bonding procedures were observed using a scanning electron microscope. In a previous report, the contraction gap width for a resin composite increased when irradiation of the resin system was delayed, despite the use of a dentine bonding system considered to be 'contraction' gap free. Such deterioration in marginal adaptation was minimized by use of an experimental dentine primer, 40% erythritol methacrylate aqueous solution (EM), followed by the use of a commercial dual- or autocured dentine bonding agent. Under scanning electron microscopy, the dentine surface microstructure became unclear after EM priming, and a polymer film was detected after polymerization of the dual-cured dentine bonding agent. The hydrogelled primer and the formation of a polymer network on the dentine surface may prevent the flow of fluid from the pulp through the dentine tubules, and maintain marginal integrity if there is delay in light curing of light-activated resin composite systems.

  20. Dichlorido{N-[1-(2-pyrid-yl)ethyl-idene]ethane-1,2-diamine}copper(II).

    PubMed

    Wang, Qiang; Bi, Cai-Feng; Wang, Da-Qi; Fan, Yu-Hua

    2009-03-25

    The title complex, [CuCl(2)(C(9)H(13)N(3))], is mononuclear and contains a five-coordinate Cu(II) atom. The geometry of the Cu(II) atom can be described as tetra-gonal-pyramidal derived from the calculation of the value τ = 0.102. The three N atoms of the pyridine and ethane-1,2-diamine ligands and one Cl atom belong to the basal plane and the other Cl atom represents the axial position of the pyramid. The Cu atom is displaced by 0.2599 (2) Å from the basal plane towards the axial Cl atom. In the crystal, mol-ecules are linked into chains by inter-molecular N-H⋯Cl and C-H⋯Cl hydrogen bonds.

  1. Fluorinated porphyrin tweezer: a powerful reporter of absolute configuration for erythro and threo diols, amino alcohols, and diamines.

    PubMed

    Li, Xiaoyong; Tanasova, Marina; Vasileiou, Chrysoula; Borhan, Babak

    2008-02-13

    A general and sensitive nonempirical protocol to determine the absolute configurations of erythro and threo diols, amino alcohols, and diamines is reported. Binding of diols to the porphyrin tweezer system is greatly enhanced by increasing the Lewis acidity of the metalloporphyrin. Supramolecular complexes formed between the porphyrin tweezer host and chiral substrates exhibited exciton-coupled bisignate CD spectra with predictable signs based on the substituents on the chiral center. The working model suggests that the observed helicity of the porphyrin tweezer is dictated via steric differentiation experienced by the porphyrin ring bound to each chiral center. A variety of erythro and threo substrates were investigated to verify this chiroptical method. Their absolute configurations were unequivocally determined, and thus a general mnemonic is provided for the assignment of chirality.

  2. Adsorption Properties of Thin Films Prepared by RF Sputtering with a Poly(biphenyltetracarboxylic dianhydride-paraphenylene diamine) Polyimide Target

    NASA Astrophysics Data System (ADS)

    Iwamori, Satoru; Yano, Satoshi; Sugimoto, Ryousuke; Uemura, Akihiro; Matsumoto, Hiroyuki; Noda, Kazutoshi

    2010-04-01

    Thin films were deposited onto a quartz crystal with a poly(biphenyltetracarboxylic dianhydride-paraphenylene diamine) (BPDA-PDA) polyimide target by RF sputtering, and the adsorption properties of these thin films for water, ethanol, acetone, acetaldehyde, toluene, and methyl salicylate were evaluated by the quartz crystal microbalance (QCM) method to characterize the surface properties of these thin films. Chemical structures, especially surface free energies of these thin films would affect the gas adsorption properties. In addition, the number of adsorbed gas molecules increased with decreasing molecular weight on each sputtered thin film. Furthermore, these gas molecules would be adsorbed inside the sputtered thin films as well as on the top surface. The number of adsorbed gas molecules increased with decreasing molecular size on each sputtered thin film.

  3. Humidity affects relative ion abundance in direct analysis in real time mass spectrometry of hexamethylene triperoxide diamine.

    PubMed

    Newsome, G Asher; Ackerman, Luke K; Johnson, Kevin J

    2014-12-16

    Unstable explosive hexamethylene triperoxide diamine (HMTD) is dangerous in quantity and benefits from the minimal sampling handling associated with atmospheric pressure chemical ionization for mass spectral analysis. Seasonal variation observed in HMTD mass spectra suggested a humidity dependence. Therefore, direct analysis in real time (DART) ionization mass spectra were acquired at a range of humidity values. An enclosure was designed to fit around the ion source and mass spectrometer inlet at atmospheric pressure. The enclosure was supplied with controlled amounts of humidified air from a test atmosphere generator to create programmable conditions for ambient analysis. The relative abundance and fragmentation of analyte ions were observed to change reliably with changing humidity values and, to a lesser degree, temperature. Humidity at such plasma-based ion sources should be regulated to avoid ∼90% shifts in relative ion abundance and provide stability and reproducibility of HMTD analysis.

  4. A cure for HIV: is it in sight?

    PubMed

    Pace, Matthew; Frater, John

    2014-07-01

    HIV is a devastating disease affecting millions of people worldwide despite the advent of successful antiretroviral therapy (ART). However, ART does not result in a cure and has to be taken for life. Accordingly, researchers are turning towards cure efforts, particularly in the light of two patients whose HIV has been seemingly eradicated. Numerous approaches and strategies have been considered for curing HIV, but no scalable and safe solution has yet been reached. With newly discovered difficulties in measuring the HIV reservoir, the main barrier to a cure, the only true test of cure is to stop ART and see whether the virus becomes detectable. However, it is possible that this treatment interruption may be associated with certain risks for patients. Here, we compare the current major approaches and recent advances for curing HIV, as well as discuss ways of evaluating HIV cure and the safety concerns involved.

  5. 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.

  6. 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.

  7. A new series of pillared uranyl-vanadates based on uranophane-type sheets in the uranium-vanadium-linear alkyl diamine systems

    SciTech Connect

    Jouffret, Laurent; Rivenet, Murielle; Abraham, Francis

    2010-01-15

    A new family of three-dimensional (3D) uranyl vanadates (C{sub 3}N{sub 2}H{sub 12}){l_brace}[(UO{sub 2})(H{sub 2}O)][(UO{sub 2})(VO{sub 4})]{sub 4}{r_brace}.1H{sub 2}O (C3UV), (C{sub 4}N{sub 2}H{sub 14}){l_brace}[(UO{sub 2})(H{sub 2}O)][(UO{sub 2})(VO{sub 4})]{sub 4}{r_brace}.2H{sub 2}O (C4UV), (C{sub 5}N{sub 2}H{sub 16}) {l_brace}[(UO{sub 2})(H{sub 2}O)][(UO{sub 2})(VO{sub 4})]{sub 4}{r_brace} (C5UV), (C{sub 6}N{sub 2}H{sub 20}) {l_brace}[(UO{sub 2})(H{sub 2}O)][(UO{sub 2})(VO{sub 4})]{sub 4}{r_brace} (C6UV) and (C{sub 7}N{sub 2}H{sub 22}) {l_brace}[(UO{sub 2})(H{sub 2}O)][(UO{sub 2})(VO{sub 4})]{sub 4}{r_brace} (C7UV) was prepared from mild-hydrothermal reactions using 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane and 1,7-diaminoheptane as structure directing agents. The five compounds are orthorhombic, space group Cmc2{sub 1}, with a{approx}15.6, b{approx}14.1, c{approx}13.6 A. The structures were solved using single-crystal X-ray diffraction data. The compounds contain the same three-dimensional inorganic framework built from uranyl-vanadate layers of uranophane-type anion topology pillared by [UO{sub 6}(H{sub 2}O)] pentagonal bipyramids. The doubly protonated diamines reside in the cavities created by the inorganic framework and are linked to the inorganic framework through hydrogen bonds involving one nitrogen atom. The structure is compared with that of uranyl-phosphates and uranyl-arsenates containing alkaline metals. The use of alkaline metals for the synthesis of uranyl-vanadates leads to carnotite-type compounds. - Graphical abstract: The (C{sub 6}N{sub 2}H{sub 20}){l_brace}[(UO{sub 2})(H{sub 2}O)][(UO{sub 2})(VO{sub 4})]{sub 4}{r_brace} compound: projection in the (1 0 0) and in the (0 0 1) planes showing the amine position.

  8. 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…

  9. Modern high powered led curing lights and their effect on pulp chamber temperature of bulk and incrementally cured composite resin.

    PubMed

    Oberholzer, T G; Makofane, M E; du Preez, I C; George, R

    2012-06-01

    Pulpal temperature changes induced by modern high powered light emitting diodes (LEDs) are of concern when used to cure composite resins. This study showed an increase in pulp chamber temperature with an increase in power density for all light cure units (LCU) when used to bulk cure composite resin. Amongst the three LEDs tested, the Elipar Freelight-2 recorded the highest temperature changes. Bulk curing recorded a significantly larger rise in pulp chamber temperature change than incrementally cured resin for all light types except for the Smartligh PS. Both the high powered LED and the conventional curing units can generate heat. Though this temperature rise may not be sufficient to cause irreversible pulpal damage, it would be safer to incrementally cure resins.

  10. 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.

  11. Electron beam curing of polymer matrix composites

    SciTech Connect

    Janke, C.J.; Wheeler, D.; Saunders, C.

    1998-01-08

    The purpose of the CRADA was to conduct research and development activities to better understand and utilize the electron beam PMC curing technology. This technology will be used to replace or supplement existing PMC thermal curing processes in Department of Energy (DOE) Defense Programs (DP) projects and American aircraft and aerospace industries. This effort involved Lockheed Martin Energy Systems, Inc./Lockheed Martin Energy Research Corp. (Contractor), Sandia National Laboratories, and ten industrial Participants including four major aircraft and aerospace companies, three advanced materials companies, and three electron beam processing organizations. The technical objective of the CRADA was to synthesize and/or modify high performance, electron beam curable materials that meet specific end-use application requirements. There were six tasks in this CRADA including: Electron beam materials development; Electron beam database development; Economic analysis; Low-cost Electron Beam tooling development; Electron beam curing systems integration; and Demonstration articles/prototype structures development. The contractor managed, participated and integrated all the tasks, and optimized the project efforts through the coordination, exchange, and dissemination of information to the project participants. Members of the Contractor team were also the principal inventors on several electron beam related patents and a 1997 R and D 100 Award winner on Electron-Beam-Curable Cationic Epoxy Resins. The CRADA achieved a major breakthrough for the composites industry by having successfully developed high-performance electron beam curable cationic epoxy resins for use in composites, adhesives, tooling compounds, potting compounds, syntactic foams, etc. UCB Chemicals, the world`s largest supplier of radiation-curable polymers, has acquired a license to produce and sell these resins worldwide.

  12. 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).

  13. 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.

  14. Care not cure: dialogues at the transition.

    PubMed

    Gordon, Geoffrey H

    2003-05-01

    Physicians and patients find it hard to communicate when treatment fails to cure or control cancer. Communication barriers include fear of "giving up," losing the medical team, and discussing death. The quality of physician-patient communication affects important outcomes including patient distress, coping, and quality of life, and physician burnout. Communication skills that can be taught, learned, and maintained for physicians at all levels of training, and effective educational programs have been described. Research on communication skills training should focus on the best method of delivery, the "dose-response" effect, and how to measure success of training in complex health care environments.

  15. 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.

  16. 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.

  17. 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.

  18. Evaluation of new UV-cured adhesives and effects of post-cure UV exposure

    NASA Astrophysics Data System (ADS)

    Daly, John G.

    2002-09-01

    Recent developments in adhesives have yielded products well suited for optical applications. Ultraviolet light-cured adhesives can be cured in seconds and are an attractive candidate. Selection of the adhesive properties can be made to achieve optimum performance. For improved alignment stability and reduced stress, low shrinkage adhesives have been needed. New UV-cured adhesives are evaluated with shrinkage values of less than 0.2%. In addition to controlled bonding for alignment stability, the effects of post-cure UV laser exposure (266 nm) are evaluated. Adhesives needed for systems employing UV lasers must consider off-axis exposure that can cause photo-reactive degradation. Relatively low power laser exposure is used as a simulated source for off-axis or scattered irradiation. None of these candidate adhesives are intended for in-the-light path use at 266 nm, but rather as structural adhesives. Evaluation of these candidates included a outgassing screening test that may be employed to select materials.

  19. 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.

  20. X-ray curing of composite materials

    NASA Astrophysics Data System (ADS)

    Berejka, Anthony J.; Cleland, M. R.; Galloway, R. A.; Gregoire, O.

    2005-12-01

    The development of high current electron beam (EB) accelerators makes it possible to consider X-ray processing for industrial applications. The well-known inefficiency in converting electron beams to X-rays still affords better overall process efficiency when compared with historic thermal processes. X-ray processing permits depth of penetration of ionizing radiation into a material and, when derived from high current accelerators, can yield process through-puts comparable to low powered EB devices. X-rays are generated at lower dose-rates which are controlled by equipment and process parameters. Two feasibility studies were conducted which illustrate the potential for X-ray processing: (1) the curing of a reactive monomeric impregnant in a thick cross-section block of wood and (2) the curing of the matrix binder in fiber reinforced composites while the composite material was still constrained within a metal mold used to form an article. The ability to control dose-rate and to penetrate thick materials, such as the walls of a metal mold, indicate that X-ray processing can be of significant industrial interest.

  1. Radiation curing of carbon fibre composites

    NASA Astrophysics Data System (ADS)

    Spadaro, G.; Alessi, S.; Dispenza, C.; Sabatino, M. A.; Pitarresi, G.; Tumino, D.; Przbytniak, G.

    2014-01-01

    Epoxy/carbon fibre reinforced composites were produced by means of e-beam irradiation through a pulsed 10 MeV electron beam accelerator. The matrix consisted of a difunctional epoxy monomer (DGEBA) and an initiator of cationic polymerisation, while the reinforcement was a unidirectional high modulus carbon fibre fabric. Dynamic mechanical thermal analysis was carried out in order to determine the cross-linking degree. The analysis pointed out a nonuniformity in the cross-linking degree of the e-beam cured panels, with the formation of clusters at low Tg (glass transition temperature) and clusters at high Tg. An out-of-mould post irradiation thermal treatment on e-beam cured samples provides a higher uniformity in the network although some slight degradation effects. Mode I delamination fracture toughness and Interlaminar Shear Strength (ISS) were also investigated by means of Double Cantilever Beam (DCB) and Short Beam Shear tests, respectively. Results from this mechanical characterisation allowed to correlate fracture toughness of the bulk matrix resin, cross-linking density and fibre/matrix interaction to the delamination fracture behaviour of the fibre reinforced material.

  2. 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.

  3. Dr. Hall and the work cure.

    PubMed

    Reed, Kathlyn L

    2005-01-01

    Herbert James Hall, MD (1870-1923), was a pioneer in the systematic and organized study of occupation as therapy for persons with nervous and mental disorders that he called the "work cure." He began his work in 1904 during the early years of the Arts and Crafts Movement in the United States. His primary interest was the disorder neurasthenia, a condition with many symptoms including chronic fatigue, stress, and inability to work or perform everyday tasks. The prevailing treatment of the day was absolute bed rest known as the "rest cure." Hall believed that neurasthenia was not caused by overwork but by faulty living habits that could be corrected through an ordered life schedule and selected occupations. He identified several principles of therapy that are still used today including graded activity and energy conservation. Dr. Adolph Meyer credits Hall for organizing the ideas on the therapeutic use of occupation (Meyer, 1922). Hall also provided the name American Occupational Therapy Association for the professional organization and served as the fourth president. For his many contributions to the profession Hall deserves to be recognized as a major contributor to the development and organization of occupational therapy. PMID:23927746

  4. 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.

  5. [Current strategy to cure pancreatic cancer].

    PubMed

    Tanaka, Masao

    2002-03-01

    For more than a decade extensive retroperitoneal dissection, chemotherapy, or radiotherapy has not prolonged the survival of patients with pancreatic cancer. Two prospective randomized studies addressing the clinical significance of extensive dissection or pancreatic resection for advanced cancer are now in progress. Nonetheless, at present, resection offers the patient the only possibility of cure. Although the diagnosis of curable pancreatic cancer is difficult, recent evidences have given a few hints. The first is pancreatic duct dilatation caused by cancerous stricture. The second is diabetes as a sign of pancreatic cancer. Our prospective pancreatographic screening of diabetic patients selected by our criteria(Table 1) revealed 7 cancers in 98 patients(7.1%). Within 3 years from diagnosis, the prevalence was 15%. Although the 7 cancers were advanced, this suggests that earlier examinations in diabetic patients may possibly lead to earlier diagnosis. The third is a small cystic lesion as a sentinel of pancreatic cancer. Endoscopic retrograde cholangiopancreatography with cytology of the pancreatic juice may show the presence of in situ cancer in patients with a pancreatic cyst. At the moment, careful checks for the presence of these hints seem to be the only strategy to offer a chance for cure to patients with pancreatic cancer.

  6. The effect of post-curing on Vickers Hardness of four light-cure resin composite materials.

    PubMed

    Marais, J T; Dannheimer, M F; Oosthuizen, M P; Booyse, A

    1999-03-01

    The use of post-curing ovens to post-cure light-cured resin composite restorations leads to a decrease in the negative effects of polymerization shrinkage and an increase in the hardness and wear resistance of the material. The aim of this study was to compare the Vickers Hardness (VH) of four different light-cure resin composite materials. In one group, samples of the four materials, Z100, Tetric Ceram, F2000 and Heliomolar were light-cured only, and in the other group a similar set of samples were light-cured and also post-cured in a DI 500 post-curing oven. VH vests were then carried out on the samples. All samples in the post-cured group had higher VH values (p = 0.000) than the corresponding samples in the light-cured only group. Z100 and F2000 had, in both groups, significantly higher VH values (p = 0.000) than Tetric Ceram and Heliomolar.

  7. Comparison of three types of light-curing devices

    NASA Astrophysics Data System (ADS)

    Powell, G. L.; Blankenau, Richard J.

    2000-03-01

    Shortened curing times for light activated composites have been sought for many years. This study was conducted to compare diametral tensile strengths (DTS) of four composites cured with three light curing devices: halogen lamp, argon laser and plasma arc. Twelve samples were made for each composite and light curing device for a total of 192 samples. Diametral tensile strengths were measured on the Instron testing machine and statistical analysis performed using ANOVA and Fisher PLSD. Results indicate there wee no statistical differences in the DTS of the composites tested as a result of the curing light source. The Plasma Arc curing light was able to produce statistically equal diametral tensile strengths in 3 and 6 seconds as compared to the argon laser in 10 seconds and the halogen light in 40 seconds. Supported in part by Dental Medical Diagnostics.

  8. 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.

  9. Dual cure solventless coating process. Phase 1, Final report

    SciTech Connect

    DeVoe, R.J.; Palazzotto, M.C.; Chambers, W.L.; Brown-Wensley, K.A.; Holmes, G.L.; Keipert, S.J.; Mathis, M.D.; McCormick, F.B.; Spurgeon, K.M.; Williams, J.W.

    1992-02-01

    The objective is to determine the feasibility of using the Dual Cure Photocatalyst technology for reduction of gaseous waste emissions through the minimization of coating solvent use. This is to be accomplished by developing a photocuring technology that would allow the use of solvent free (100% solids) formulations while preserving or improving upon the performance of conventional solvent based materials. Four Dual Cure Photocatalyst systems and one conventional catalyst system were investigated for use in curing combinations of epoxies with acrylates and acrylates with polyurethane precursors (polyol/polyisocyanate mixtures). Photocatalyst screening results showed that Dual Cure Photocatalyst Systems based upon cationic organometallic compounds alone or in combination with free radical photoinitiators or oxidants provide significantly better processing performance than systems based upon conventional catalysts or neutral organometallic compounds in combination with oxidants. Mechanical testing of materials prepared with the five catalyst systems showed that: (1) Dual Cure compositions can produce materials with better properties than the component parts and (2) Compositions cured with Dual Cure Photocatalysts produce materials superior to those cured with conventional catalyst systems in a number of cases. Cost, economic and energy analyses are presented based upon laboratory scale coating and curing studies.

  10. Light-curing acrylic resin as an orthodontic baseplate material.

    PubMed

    Brown, J; Kerr, W J

    1998-08-01

    Heat-curing autopolymerizing (self-cure or cold-cure), thermoplastic, and light-curing acrylic resin are the most commonly used orthodontic baseplate materials. While cured acrylic resins present few problems to the patient, in the laboratory acrylic resin has to be sprayed, mixed, or packed in a fume-extraction unit because of the harmful fumes emitted by the raw inflammable chemicals. Light-curing material, on the other hand, is virtually nonflammable and has virtually no aroma. A light-cure technique for the construction of orthodontic baseplates is described. While buildup of the baseplate is slightly slower than for self-cured material, the shorter time involved in trimming and polishing means that overall construction is faster. It is easier to obtain a uniform thickness with light-cured material, and it provides superior fit. These results, however, are subject to more extensive clinical trials. The only apparent disadvantage is the fine powder produced during trimming. Even with a bench equipped with an extraction unit, it is advisable to use a face mask to prevent the inhalation of dust.

  11. Accelerated curing of silicone adhesive in medical catheter applications

    NASA Astrophysics Data System (ADS)

    Yoon, Hyun Joong

    This work presents a systematic approach to more effective thermal curing of the silicone adhesive used in medical catheter construction. A 2.45 GHZ microwave energy source provides heat more quickly and uniformly than the conventional oven heating process. Microwave heating effects are due both to dielectric and ohmic phenomena. It is shown experimentally that low frequency (60 HZ) current passed through the conductive catheter coil generates heat internally that facilitates the cross-linking process of cure. The changes with temperature of catheter material dielectric constant and conductivity at microwave frequencies are shown to enhance the curing process. Local humidity also affects the quality of curing process as moisture and acetic acid are driven from the inner radius to outer radius of the catheter body. With the microwave assisted curing technique, the curing process may complete in less than sixty seconds; a significant improvement from days to minutes. Microwave energy reflected from the curing site may be used to monitor the curing process and detect thermal runaway, i.e. The condition of a hot spot with attendant material destruction. Feedback from the reflected signal to the input microwave energy source allows a maximum rate of curing energy delivery without damaging the temperature sensitive polyurethane layer in the medical catheters.

  12. Sample size calculation for the proportional hazards cure model.

    PubMed

    Wang, Songfeng; Zhang, Jiajia; Lu, Wenbin

    2012-12-20

    In clinical trials with time-to-event endpoints, it is not uncommon to see a significant proportion of patients being cured (or long-term survivors), such as trials for the non-Hodgkins lymphoma disease. The popularly used sample size formula derived under the proportional hazards (PH) model may not be proper to design a survival trial with a cure fraction, because the PH model assumption may be violated. To account for a cure fraction, the PH cure model is widely used in practice, where a PH model is used for survival times of uncured patients and a logistic distribution is used for the probability of patients being cured. In this paper, we develop a sample size formula on the basis of the PH cure model by investigating the asymptotic distributions of the standard weighted log-rank statistics under the null and local alternative hypotheses. The derived sample size formula under the PH cure model is more flexible because it can be used to test the differences in the short-term survival and/or cure fraction. Furthermore, we also investigate as numerical examples the impacts of accrual methods and durations of accrual and follow-up periods on sample size calculation. The results show that ignoring the cure rate in sample size calculation can lead to either underpowered or overpowered studies. We evaluate the performance of the proposed formula by simulation studies and provide an example to illustrate its application with the use of data from a melanoma trial. PMID:22786805

  13. 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.

  14. 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. PMID:15125601

  15. Synthesis of tunable diamine ligands with spiro indane-2,2′-pyrrolidine backbone and their applications in enantioselective Henry reaction.

    PubMed

    Ćwiek, Rafał; Niedziejko, Piotr; Kałuża, Zbigniew

    2014-02-01

    Novel diamine ligands with spiro indane-2,2′-pyrrolidine scaffold were synthesized starting from Seebach’s oxazolidinone 6 and were subsequently employed in asymmetric Henry reaction. Following the initial experimental findings, further synthesis resulted in two types of spiro diamines, with varying substituents at both nitrogen atoms. Ligands of type A, containing a small substituent at N-1′ atom, and a large group at N-1 atom gave predominantly the S-configured β-nitroalcohol, while ligands of type B, with the reversed location of small and large substituents furnished the R-configured product. Both types of ligands turned out to be versatile catalysts for the Henry reaction between nitromethane and an assortment of aryl as well as alkyl aldehydes offering either S- (lig. A) or R-configured (lig. B) nitroalcohols in a good to high chemical yield and an excellent enantioselectivity up to 99% ee.

  16. The effects of restorative composite resins on the cytotoxicity of dentine bonding agents.

    PubMed

    Kim, Kyunghwan; Son, Kyung Mi; Kwon, Ji Hyun; Lim, Bum-Soon; Yang, Hyeong-Cheol

    2013-01-01

    During restoration of damaged teeth in dental clinics, dentin bonding agents are usually overlaid with restorative resin composites. The purpose of this study was to investigate the effects of restorative resin composites on cytotoxicity of dentin bonding agents. Dentin bonding agents were placed on glass discs, pre-cured and uncured resin composite discs. Bonding agents on the glass discs and composite resins discs were light cured and used for agar overlay cytotoxicity testing. Dentin bonding agents on composite resin discs exhibited far less cytotoxicity than that on glass discs. The polymerization of resin composite increased the surface hardness and decreased the cytotoxicity of bonding agents. In conclusion, composite resins in dental restorations are expected to enhance the polymerization of dentin bonding agents and reduce the elution of resin monomers, resulting in the decrease of cytotoxicity.

  17. Effect of curing mode on the hardness of dual-cured composite resin core build-up materials.

    PubMed

    Arrais, César Augusto Galvão; Kasaz, Aline de Cerqueira; Albino, Luís Gustavo Barrote; Rodrigues, José Augusto; Reis, Andre Figueiredo

    2010-01-01

    This study evaluated the Knoop Hardness (KHN) values of two dual-cured composite resin core build-up materials and one resin cement exposed to different curing conditions. Two dual-cured core build-up composite resins (LuxaCore-Dual, DMG; and FluoroCore2, Dentsply Caulk), and one dual-cured resin cement (Rely X ARC, 3M ESPE) were used in the present study. The composite materials were placed into a cylindrical matrix (2 mm in height and 3 mm in diameter), and the specimens thus produced were either light-activated for 40 s (Optilux 501, Demetron Kerr) or were allowed to self-cure for 10 min in the dark (n = 5). All specimens were then stored in humidity at 37 degrees C for 24 h in the dark and were subjected to KHN analysis. The results were submitted to 2-way ANOVA and Tukey's post-hoc test at a pre-set alpha of 5%. All the light-activated groups exhibited higher KHN values than the self-cured ones (p = 0.00001), regardless of product. Among the self-cured groups, both composite resin core build-up materials showed higher KHN values than the dual-cured resin cement (p = 0.00001). LuxaCore-Dual exhibited higher KHN values than FluoroCore2 (p = 0.00001) when they were allowed to self-cure, while no significant differences in KHN values were observed among the light-activated products. The results suggest that dual-cured composite resin core build-up materials may be more reliable than dual-cured resin cements when curing light is not available.

  18. Effectiveness of composite cure associated with different curing modes of LED lights.

    PubMed

    Soh, M S; Yap, Adrian U J; Siow, K S

    2003-01-01

    This study compared the effectiveness of cure of two LED (light-emitting diodes) lights (Elipar FreeLight [FL], 3M-ESPE; GC e-Light [EL], GC) to conventional (Max [MX], Dentsply-Caulk [control]), high intensity (Elipar TriLight [TL], 3M-ESPE) and very high intensity (Astralis 10 [AS], Ivoclar Vivadent) halogen lights. The 10 light-curing regimens investigated were: FL1 400 mW/cm2 [40 seconds], FL2 0-400 mW/cm2 [12 seconds] --> 400 mW/cm2 [28 seconds], EL1 750 mW/cm2 [10 pulses x 2 seconds], EL2 350 mW/cm2 [40 seconds], EL3 600 mW/cm2 [20 seconds], EL4 0-600 mW/cm2 [20 seconds] --> 600 mW/cm2 [20 seconds], TL1 800 mW/cm2 [40 seconds], TL2 100-800 mW/cm2 [15 seconds] --> 800 mW/cm2 [25 seconds], AS1 1200 mW/cm2 [10 seconds], MX 400 mW/cm2 [40 seconds]. Effectiveness of cure with the different modes was determined by measuring the top and bottom surface hardness (KHN) of 2-mm thick composite (Z100, [3M-ESPE]) specimens using a digital microhardness tester (n=5, load=500 g; dwell time=15 seconds). Results were analyzed using one-way ANOVA/Scheffe's post-hoc test and Independent Samples t-test (p<0.05). At the top surface, the mean KHN observed with LED lights ranged from 55.42 +/- 1.47 to 68.54 +/- 1.46, while that of halogen lights was 62.64 +/- 1.87 to 73.14 +/- 0.97. At the bottom surface, the mean KHN observed with LED and halogen lights ranged from 46.90 +/- 1.73 to 66.46 +/- 1.18 and 62.26 +/- 1.93 to 70.50 +/- 0.87, respectively. Significant differences in top and bottom KHN values were observed between different curing regimens for the same light, and between LED and halogen lights. Although curing with most modes of EL resulted in significantly lower top and bottom KHN values than the control, no significant difference was observed for the different modes of FL. Hence, the effectiveness of composite cure with LED LCUs is product dependent.

  19. Asymmetric Ring Opening/Cyclization/Retro-Mannich Reaction of Cyclopropyl Ketones with Aryl 1,2-Diamines for the Synthesis of Benzimidazole Derivatives.

    PubMed

    Xia, Yong; Lin, Lili; Chang, Fenzhen; Liao, Yuting; Liu, Xiaohua; Feng, Xiaoming

    2016-09-26

    A highly efficient asymmetric ring-opening/cyclization/retro-Mannich reaction of cyclopropyl ketones with aryl 1,2-diamines has been realized using a chiral N,N'-dioxide/Sc(III) catalyst. Benzimidazoles containing chiral side chains were generated under mild reaction conditions in excellent outcomes (up to 99 % yield and 97 % ee). This method also provides efficient access to chiral benzimidazole-substituted amide and cycloheptene derivatives. PMID:27376785

  20. 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

    2015-07-01

    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].

  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. Synthesis of multibranched australine derivatives from reducing castanospermine analogues through the Amadori rearrangement of gem-diamine intermediates: selective inhibitors of β-glucosidase.

    PubMed

    Sánchez-Fernández, Elena M; Álvarez, Eleuterio; Ortiz Mellet, Carmen; García Fernández, José M

    2014-12-01

    A practical one-pot synthesis of bi- and triantennated australine analogues from a pivotal sp(2)-iminosugar-type reducing castanospermine precursor is reported. The transformation involves a gem-diamine intermediate that undergoes the indolizidine → pyrrolizidine Amadori-type rearrangement and proceeds under strict control of the generalized anomeric effect to afford a single diastereomer. The final compounds behave as selective competitive inhibitors of β-glucosidase and are promising candidates as pharmacological chaperones for Gaucher disease.

  3. 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.

  4. How do we value a cure?

    PubMed

    Husereau, Don

    2015-01-01

    Future perceptions of the value of curative therapies will likely reflect debates happening today about preferences for funding of preventive versus treatment programs, as well as funding orphan drugs. Little is known about how society will value curative therapies versus standard treatments, and the significant role of a host of psychological factors compared to overarching concerns about opportunity costs will likely lead to significant tension between payers and the public. More research to clarify societal preferences and healthcare goals in regards to curative therapies and in light of the potential for significant opportunity costs will be required. Given what we know about preferences for the funding of prevention and treatment measures, we should expect that cures will not be held to a different measure.

  5. Patienthood in medieval Tuscany: beliefs and cures.

    PubMed

    Lawless, Catherine

    2016-06-01

    This paper focuses on intersections of holy and sick bodies in the Tuscan Middle Ages to examine how the faithful accessed miraculous cures from contact with, or belief in, the relics of the saints. Rather than examine the relationship between the long dead martyrs (whose relics were abundant), however, it will look at the relationship between relatively recent saints and their devotees. The miracles discussed are traditional-that is, they are found in the lives of many saints and are not exceptional. It is hoped, however, that by concentrating on Tuscany, some insights can be secured on the relationship between Tuscan individuals of the late middle ages and those of their community who were recognised, either officially or through vox populi, as saints. PMID:27174846

  6. 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.

  7. 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.

  8. 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

  9. 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

  10. Proportion cured models applied to 23 cancer sites in Norway.

    PubMed

    Cvancarova, Milada; Aagnes, Bjarte; Fosså, Sophie D; Lambert, Paul C; Møller, Bjørn; Bray, Freddie

    2013-04-01

    Statistical cure is reached when a group of patients has the same mortality as cancer-free individuals. Cure models predict the cured proportion and the median survival of fatal cases. Cure models have seldom been applied and tested systematically across all major cancer sites. Incidence and follow-up data on 23 cancer sites recorded at the Cancer Registry of Norway 1963-2007 were obtained. Mixture cure models were fitted to obtain trends and up-to-date estimates (based on period approach) assuming cured and uncured groups exist. The model converged for cancers of the mouth and pharynx, oesophagus, stomach, colon, rectum, liver, gallbladder, pancreas, lung and trachea, ovary, kidney, bladder, CNS, non-Hodgkin lymphoma (only for males) and leukemia. The proportion of cured patients increased 1963-2002 for both sexes, with the largest changes (in percent) seen for leukemia (46.4 and 46.7) and CNS (35.9, 42.0), males given first. Median survival time for the uncured cases increased for colon and rectal cancer, and there was a three- fold increase in median survival time for patients with fatal ovarian cancers. Cancers of bladder and CNS had the highest up-to-date proportion cured (in percent), 67.4 and 64.0, respectively, pancreas and liver were amongst the lowest (5.7 and 9.9, respectively). Cure models are useful when monitoring progress in cancer care, but must be applied and interpreted with caution. The absolute estimates of the cure proportion are speculative and should not be calculated where cure is not medically anticipated.

  11. Proportion cured models applied to 23 cancer sites in Norway.

    PubMed

    Cvancarova, Milada; Aagnes, Bjarte; Fosså, Sophie D; Lambert, Paul C; Møller, Bjørn; Bray, Freddie

    2013-04-01

    Statistical cure is reached when a group of patients has the same mortality as cancer-free individuals. Cure models predict the cured proportion and the median survival of fatal cases. Cure models have seldom been applied and tested systematically across all major cancer sites. Incidence and follow-up data on 23 cancer sites recorded at the Cancer Registry of Norway 1963-2007 were obtained. Mixture cure models were fitted to obtain trends and up-to-date estimates (based on period approach) assuming cured and uncured groups exist. The model converged for cancers of the mouth and pharynx, oesophagus, stomach, colon, rectum, liver, gallbladder, pancreas, lung and trachea, ovary, kidney, bladder, CNS, non-Hodgkin lymphoma (only for males) and leukemia. The proportion of cured patients increased 1963-2002 for both sexes, with the largest changes (in percent) seen for leukemia (46.4 and 46.7) and CNS (35.9, 42.0), males given first. Median survival time for the uncured cases increased for colon and rectal cancer, and there was a three- fold increase in median survival time for patients with fatal ovarian cancers. Cancers of bladder and CNS had the highest up-to-date proportion cured (in percent), 67.4 and 64.0, respectively, pancreas and liver were amongst the lowest (5.7 and 9.9, respectively). Cure models are useful when monitoring progress in cancer care, but must be applied and interpreted with caution. The absolute estimates of the cure proportion are speculative and should not be calculated where cure is not medically anticipated. PMID:22927104

  12. Bisimide amine cured epoxy /IME/ resins and composites. II - Ten-degree off-axis tensile and shear properties of Celion 6000/IME composites

    NASA Technical Reports Server (NTRS)

    Scola, D. A.

    1982-01-01

    Bisimide amines (BIAs), which are presently used as curing agents in a state-of-the-art epoxy resin, are oligomeric and polymeric mixtures. A series of composites consisting of the novel BIA-cured epoxy resin reinforced with Celion 6000 graphite fibers were fabricated and evaluated, and the ten-degree, off-axis uniaxial tensile and shear properties of these composites were determined. The use of the intralaminar shear strain-to-failure was used in the calculation of resin shear strain-to-failure. Study results indicate that several of these novel composite systems exhibit shear strain properties that are superior to those of the control composite system of the present experiments, which employed a sulfone curing agent.

  13. Mechanistic Insights into the Cure of Prion Disease by Novel Antiprion Compounds▿

    PubMed Central

    Webb, Sarah; Lekishvili, Tamuna; Loeschner, Corinna; Sellarajah, Shane; Prelli, Frances; Wisniewski, Thomas; Gilbert, Ian H.; Brown, David R.

    2007-01-01

    Prion diseases are fatal neurodegenerative disorders. Identification of possible therapeutic tools is important in the search for a potential treatment for these diseases. Congo red is an azo dye that has been used for many years to detect abnormal prion protein in the brains of diseased patients or animals. Congo red has little therapeutic potential for the treatment of these diseases due to toxicity and poor permeation of the blood-brain barrier. We have prepared two Congo red derivatives, designed without these liabilities, with potent activity in cellular models of prion disease. One of these compounds cured cells of the transmissible agent. The mechanism of action of these compounds is possibly multifactorial. The high affinity of Congo red derivatives, including compounds that are ineffective and are effective at the cure of prion disease, for abnormally folded prion protein suggests that the amyloidophylic property of these derivatives is not as critical to the mechanism of action as other effects. Congo red derivatives that are effective at the cure of prion disease increased the degradation of abnormal PrP by the proteasome. Therefore, the principal mechanism of action of the Congo red analogues was to prevent inhibition of proteasomal activity by PrPSc. PMID:17652397

  14. 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.

  15. Filling agents.

    PubMed

    Glavas, Ioannis P

    2005-06-01

    Injectable fillers have become an important component of minimally invasive facial rejuvenation modalities. Their ease of use, effectiveness, low morbidity, and fast results with minimal downtime are factors that have made them popular among patients. Soft tissue augmentation has evolved to a unique combination of medicine and art. A wide selection of available agents and new products, each one with unique properties, may be used alone or in combination. The physician acquires the tools to rebalance facial characteristics not only by filling wrinkles but also by having the ability to shape the face and restore bony contours and lines. Careful selection of candidates, realistic expectations, and an understanding of the limitations of fillers are crucial for a successful result.

  16. FTIR spectroscopic characterization of polyurethane-urea model hard segments (PUUMHS) based on three diamine chain extenders

    NASA Astrophysics Data System (ADS)

    Zhang, Shijie; Ren, Zhiyong; He, Suqing; Zhu, Yan; Zhu, Chengshen

    2007-01-01

    Six polyurethane-urea model hard segments (PUUMHS) were prepared by a solution method based, respectively, on two isocyanates: 4,4'-methylene-diphenyl-diisocyanate (MDI), 4,4'-methylene-dicyclohexyl diisocyanate (HMDI) and three amine chain extenders: ethylene diamine (EDA), methylene-bis-ortho-chloroaniline (MOCA), 2,4-diamino-3,5-dimethylsuphylchlorobenzene (DDSCB). FTIR was used to study their spectroscopic characterization. The main FTIR bands of the six samples were assigned and compared. It was found that most of N-H and C dbnd O are H-bonded in these PUUMHS. However, the N-H in three MDI based PUUMHS is all in the stronger H-bond state than that in their corresponding HMDI based while the C dbnd O in three HMDI based PUUMHS is all in the stronger H-bond state than that in their corresponding MDI based, respectively. In addition, the order of the H-bond strength in HMDI based PUUMHS is MOCA, DDSCB and EDA whether according to νN sbnd H or νC dbnd O band wavenumbers, which is, however, different from that in MDI based PUUMHS. Moreover, the HMDI based PUUMHS shows obvious double amide III bands while the MDI based has only prominent one. The results are discussed according mainly to the different characteristics of the three chain extenders as well as the structure difference between MDI and HMDI.

  17. Continuous administration of heparin in patients with deep vein thrombosis can increase plasma levels of diamine oxidase.

    PubMed

    Klocker, Josef; Perkmann, Reinhold; Klein-Weigel, Peter; Mörsdorf, Gabriele; Drasche, Astrid; Klingler, Anton; Fraedrich, Gustav; Schwelberger, Hubert G

    2004-01-01

    Besides its anticoagulant activity, the sulfated polysaccharide heparin has numerous other biological effects. Especially the antiinflammatory and immunoregulatory properties of heparin may be associated with its ability to release the histamine-degrading enzyme diamine oxidase (DAO) from tissue-bound sites into the circulation. Whereas DAO activity is at the limits of detection in normal human plasma, the application of heparin leads to a significant increase of plasma DAO activity. However, previously, only the effect of bolus injection of unfractionated heparin (UFH) had been studied. To investigate DAO release during continuous heparin infusion, 28 patients with deep vein thrombosis (DVT) undergoing heparin therapy were analyzed. Whereas continuous heparin infusion did not lead to any increase of plasma DAO activity in 12 patients (43%), 6 patients (21%) showed a single elevated and 10 patients (36%) permanently elevated plasma DAO activity. The groups of patients exhibiting different DAO release responses did not differ in age, sex, body weight, concomitant diseases, heparin infusion rates, coagulation indices, location and extension of thrombosis, or clinical outcome. However, the rate of idiopathic DVT was significantly higher in the group of patients releasing DAO. This study shows, for the first time, that continuous heparin infusion can lead to DAO release and that individuals exhibit considerable differences in their release response. Although the significance of heparin-induced DAO release needs further clarification, our results indicate that postheparin plasma DAO activity could be an interesting parameter correlated with idiopathic DVT.

  18. Post-Blast Analysis of Hexamethylene Triperoxide Diamine using Liquid Chromatography-Atmospheric Pressure Chemical Ionization-Mass Spectrometry.

    PubMed

    Marsh, Christine M; Mothershead, Robert F; Miller, Mark L

    2015-09-01

    A qualitative method using liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (LC/APCI-MS) has been developed and validated for the identification of trace hexamethylene triperoxide diamine (HMTD) using three structurally-specific ions. Residues are extracted with deionized water (DI) and identified using a gradient mobile phase program and positive ion full scan mode on a Thermo Finnigan LCQ Ion Trap Mass Spectrometer. This method was validated according to several performance characteristics for the qualitative identification of an analyte using the characteristic ions, demonstrating the method's reliability for use on forensic applications. The method's limit of detection (LOD) can identify HMTD in an extract from a cotton matrix to which 20 μg of HMTD has been applied (equivalent to 10 ppm in extract). Previous scientific publications using LC/MS have not demonstrated post-blast HMTD residue analyses and suffer from a lack of chromatographic retention, sufficient number of mass spectral ions with validation, or require more complex/expensive instrumental methods (accurate mass or MS/MS). Post-blast analyses were successfully conducted with two syringe detonations that verified the efficacy of the method on the analysis of debris and residues following detonation. PMID:26385711

  19. 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

    2011-11-01

    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. PMID:21942768

  20. 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.

  1. 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

    2011-11-01

    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.

  2. 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

  3. An iron(II) diketonate-diamine complex as precursor for thin film fabrication by atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Bratvold, Jon E.; Carraro, Giorgio; Barreca, Davide; Nilsen, Ola

    2015-08-01

    A new divalent Fe precursor has been explored for deposition of iron-containing thin films by atomic layer deposition and molecular layer deposition (ALD/MLD). The Fe(II) β-diketonate-diamine complex, Fe(hfa)2TMEDA, (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate, TMEDA = N,N,N‧,N‧-tetramethylethylenediamine) can be handled in air, and sublimation at 60 °C ensures a satisfactory vaporization rate. The reactivity of the precursor does not allow for direct reaction with water as co-reactant. Nevertheless, it reacts with carboxylic acids, resulting in organic-inorganic hybrid materials, and with ozone, yielding α-Fe2O3. The divalent oxidation state of iron was maintained during deposition when oxalic acid was used as co-reactant, demonstrating the first preservation of Fe(II) from precursor to film during an MLD process. A self-saturating growth mode was proven by in situ quartz crystal microbalance (QCM) measurements, and the films were further characterized by grazing incidence X-ray diffraction (GIXRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS).

  4. 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.

  5. 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…

  6. 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.

  7. Post-cure heat treatments for composites: properties and fractography.

    PubMed

    Ferracane, J L; Condon, J R

    1992-09-01

    Two commercial and four experimental composites were subjected to post-cure heat treatments of 10 min and 3 h duration immediately after light-curing. Fracture toughness, flexural modulus, microhardness and degree of conversion (FTIR) were evaluated 24 h later. The results showed that post-cure heat treatments at 120 degrees C of short or long duration can be used to produce significant improvements in the degree of cure and the mechanical properties of dental composites used as inlays. A 10 min heat treatment was as effective as a 3 h treatment in enhancing properties and degree of cure. In addition, a 3 h heat treatment carried out 7 days after the initial light-curing was capable of improving properties and cure to almost the same extent as the immediate heat treatments. The improvement in properties, in conjunction with the fractography, indicate a toughening of the filled resin matrix and possibly an improved filler/matrix adhesion in the microfills. The changes appear to be predominantly the result of an increase in degree of cure.

  8. 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.

  9. Monitoring resin cure of medium density fiberboard using dielectric sensors

    SciTech Connect

    King, R.J.; Rice, R.W.

    1996-12-31

    Flush mounted, in-press microwave (600--800 MHz) sensors have been developed for monitoring the complex permittivity in real time during the cure of medium density fiberboard. The measured dielectric constant ({var_epsilon}{prime}) and loss factor ({var_epsilon}{double_prime}) are independent diagnostic indicators of dynamic cure events that are catalyzed by heat, pressure and moisture. In particular, with this technique the instantaneous effects of resin viscosity, rate and degree of adhesive cure, the wood density, the changes in phase of the moisture and the rate of moisture depletion can be monitored during the entire curing process. The comparative roles of moisture and adhesive content are discussed, along with the comparative modulus of rupture with cure duration. Results are presented comparing the dynamics of phenol-formaldehyde and isocyanate resins.

  10. Fiber-optic epoxy composite cure sensor. II. Performance characteristics

    NASA Astrophysics Data System (ADS)

    Lam, Kai-Yuen; Afromowitz, Martin A.

    1995-09-01

    The performance of a fiber-optic epoxy composite cure sensor, as previously proposed, depends on the optical properties and the reaction kinetics of the epoxy. The reaction kinetics of a typical epoxy system are presented. It is a third-order autocatalytic reaction with a peak observed in each isothermal reaction-rate curve. A model is derived to describe the performance characteristics of the epoxy cure sensor. If a composite coupon is cured at an isothermal temperature, the sensor signal can be used to predict the time when the gel point occurs and to monitor the cure process. The sensor is also shown to perform well in nonstoichiometric epoxy matrices. In addition the sensor can detect the end of the cure without calibration.

  11. 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.

  12. A penalized likelihood approach for mixture cure models.

    PubMed

    Corbière, Fabien; Commenges, Daniel; Taylor, Jeremy M G; Joly, Pierre

    2009-02-01

    Cure models have been developed to analyze failure time data with a cured fraction. For such data, standard survival models are usually not appropriate because they do not account for the possibility of cure. Mixture cure models assume that the studied population is a mixture of susceptible individuals, who may experience the event of interest, and non-susceptible individuals that will never experience it. Important issues in mixture cure models are estimation of the baseline survival function for susceptibles and estimation of the variance of the regression parameters. The aim of this paper is to propose a penalized likelihood approach, which allows for flexible modeling of the hazard function for susceptible individuals using M-splines. This approach also permits direct computation of the variance of parameters using the inverse of the Hessian matrix. Properties and limitations of the proposed method are discussed and an illustration from a cancer study is presented.

  13. 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...

  14. 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...

  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. 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 ...

  17. Short-course, cost-effective treatment with amphotericin B-fat emulsion cures visceral leishmaniasis.

    PubMed

    Sundar, S; Gupta, L B; Rastogi, V; Agrawal, G; Murray, H W

    2000-01-01

    Although short-course therapy with new lipid formulations of amphotericin B represents an advance over lengthy traditional treatments in visceral leishmaniasis (kala-azar), high cost has rendered these agents largely irrelevant in developing countries where the disease is endemic. Therefore, we tested standard amphotericin B deoxycholate mixed with a commercial fat emulsion as short-course treatment for Indian visceral leishmaniasis in Bihar in 1997/98. Seventy children and adults with splenic aspirate-documented infection, 23 of whom had failed prior antimony (Sb) therapy, received 5 alternate-day infusions of 2 mg/kg. Apparent cure, which required a parasite-free splenic aspirate smear, was assessed 20 days after treatment (day 30); definitive cure was determined at 6 months. Other than anticipated infusion-related fever and/or chills, treatment was safe and well tolerated. One patient required dose modification because of mild, reversible renal insufficiency. Sixty-nine patients (98.6%, CI 92.3-100%) had apparent cures; during follow-up, there were 4 treatment failures (relapses, 3; unrelated death, 1), yielding definitive cures in 65 of 70 patients (92.9%, CI 84.1-97.6%). Including retreatment costs for patients in Bihar (who now often fail initial Sb therapy), the final per patient cost of the tested regimen (US $260) was 59% and 43% less than treatment with Sb or conventional amphotericin B alone, respectively. Short-course treatment with amphotericin B-fat emulsion is active, cost-effective treatment for patients with visceral leishmaniasis including those with Sb-unresponsive infection.

  18. 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.

  19. 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.

  20. 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

  1. Activities of pork muscle proteases in model cured meat systems.

    PubMed

    Toldrá, F; Rico, E; Flores, J

    1992-03-01

    The effect of curing agents (salt, nitrate, ascorbic acid and glucose) and processing parameters (pH, water activity and drying and cooking temperatures) on pork muscle cathepsins B, D, H and L as well as leucyl, arginyl and tyrosyl hydrolysing activities is reported. Salt (60 g/l) showed a powerful inhibitory effect, especially on cathepsin D and aminopeptidase activities where less than 13% of the original activity was recovered. Cathepsin H was also affected (38% of the original activity) while cathepsins B and B+L recovered 72.5 and 63.0%, respectively. Nitrate (0.2-0.25 g/l) and ascorbic acid (0.2-0.4 g/l) did not significantly affect the enzyme activities. On the other hand, 0.5-2 g/l of glucose activated both cathepsins B and D with an increase of 39.5 and 28.5% and also leucyl and arginyl hydrolysing activities which were 75.0 and 24.0%, respectively. No aminopeptidase activity was detected when assayed in 100 mM sodium citrate buffer, pH 5.1. Cathepsin H was also very affected at that pH and only 12.0% of activity was recovered. A decrease in water activity, especially below 0.84, also affected the enzyme activities which were found below 50%. Temperatures in the usual range of the drying process (22 and 30 degrees C) gave substantial enzyme activities (around 40-50 and 80%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Significance of the conformation of building blocks in curing of barnacle underwater adhesive.

    PubMed

    Kamino, Kei; Nakano, Masahiro; Kanai, Satoru

    2012-05-01

    Barnacles are a unique sessile crustacean that attach irreversibly and firmly to foreign underwater surfaces. Its biological underwater adhesive is a peculiar extracellular multi-protein complex. Here we characterize one of the two major proteins, a 52 kDa protein found in the barnacle cement complex. Cloning of the cDNA revealed that the protein has no homolog in the nonredundant database. The primary structure consists of four long sequence repeats. The process of dissolving the protein at the adhesive joint of the animal by various treatments was monitored in order to obtain insight into the molecular mechanism involved in curing of the adhesive bulk. Treatments with protein denaturant, reducing agents and/or chemical-specific proteolysis in combination with 2D diagonal PAGE indicated no involvement of the protein in intermolecular cross-linkage/polymerization, including formation of intermolecular disulfide bonds. As solubilization of the proteins required high concentrations of denaturing agents, it appears that both the conformation of the protein as building blocks and non-covalent molecular interactions between the building blocks, possibly hydrophobic interactions and hydrogen bonds, are crucial for curing of the cement. It was also suggested that the protein contributes to surface coupling by an anchoring effect to micro- to nanoscopic roughness of surfaces.

  3. Dry-cured ham restructured with fibrin.

    PubMed

    Romero de Ávila, M D; Hoz, L; Ordóñez, J A; Cambero, M I

    2014-09-15

    The viability of a fibrinogen-thrombin system (FT) to bind fresh deboned hams for incorporation in the salting and ripening processes, to produce cured ham, was studied. The effects of the different processing variables (pH, NaCl concentration, temperature and gelation time) on FT, a meat emulsion mixed with FT, fresh pork portions and deboned hams restructured with FT were analyzed. The most stable and firmest fibrin gels were obtained after 6h of adding the FT, with less than 2% NaCl and pH 7-8.4. Scanning electron microscopy of the fibrin gel showed fibrillar structures with a high degree of cross-linking and a high density. Two structures were found in the binding area of restructured meat; one in the central part with similar characteristics to fibrin gels and, another in the area of contact between the meat surfaces, where a filamentous structure connected the fibrin gels with the muscle bundles. PMID:24767091

  4. 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.

  5. 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.

  6. A 'cure' for Down syndrome: what do parents want?

    PubMed

    Inglis, A; Lohn, Z; Austin, J C; Hippman, C

    2014-10-01

    Recent advancements in molecular genetics raise the possibility that therapeutics or a 'cure' for Down syndrome (DS) may become available. However, there are no data regarding how parents of children with DS perceive the possibility of mitigating specific manifestations such as the intellectual disability (ID) associated with DS, or curing the condition entirely. To explore these issues, we distributed a questionnaire to members of the Lower Mainland Down Syndrome Society in British Columbia, Canada. Questionnaires were completed by 101 parents (response rate=41%). A majority (61%) viewed the possibility of reversing ID in DS positively, but only 41% said that they would 'cure' their child of DS if it were possible. Twenty-seven percent of respondents said they would not 'cure' their child, and 32% were unsure if they would 'cure' their child. The most commonly cited motivation for opting for a 'cure' was to increase their child's independence. However, parental attitudes' towards a 'cure' for DS were complex, affected by ethical issues, perceived societal values, and pragmatic factors such as the age of the individual and long-term care-giving burden. These findings could be used by healthcare professionals supporting families who include a member with DS and to direct future research.

  7. Cured meat consumption increases risk of readmission in COPD patients.

    PubMed

    de Batlle, Jordi; Mendez, Michelle; Romieu, Isabelle; Balcells, Eva; Benet, Marta; Donaire-Gonzalez, David; Ferrer, Jaume J; Orozco-Levi, Mauricio; Antó, Josep M; Garcia-Aymerich, Judith

    2012-09-01

    Recent studies have shown that a high dietary intake of cured meat increases the risk of chronic obstructive pulmonary disease (COPD) development. However, its potential effects on COPD evolution have not been tested. We aimed to assess the association between dietary intake of cured meat and risk of COPD readmission in COPD patients. 274 COPD patients were recruited during their first COPD admission between 2004 and 2006, provided information on dietary intake of cured meat during the previous 2 yrs, and were followed until December 31, 2007 (median follow-up 2.6 yrs). Associations between cured meat intake and COPD admissions were assessed using parametric regression survival-time models. Mean ± SD age was 68 ± 8 yrs, 93% of patients were male, 42% were current smokers, mean post-bronchodilator forced expiratory volume in 1 s (FEV(1)) was 53 ± 16% predicted, and median cured meat intake was 23 g · day(-1). After adjusting for age, FEV(1), and total caloric intake, high cured meat intake (more than median value) increased the risk of COPD readmission (adjusted HR 2.02, 95% CI 1.31-3.12; p=0.001). High cured meat consumption increases the risk of COPD readmission in COPD patients. The assessment of the effectiveness of healthy diet advice should be considered in the future.

  8. Variation of Resin Properties Through the Thickness of Cured Samples

    NASA Technical Reports Server (NTRS)

    1984-01-01

    It is the purpose of this work to gain knowledge of the glassy materials used as matrices in composites and to study the homogeneity resulting from the curing process. An attempt is made to link the glass transition quantitatively with the presence of a given material. Expoxy resins containing various amounts of hardener (TGDDM/DDS system) were cured in a muffle furnace at 473 K for seven hours. The glass transition temperature, T sub g versus weight minus percent of hardener in the epoxy resin were measured. A limit was rapidly reached in T sub g at only two percent hardener. Thus, the glass transition of the fully cured epoxy-amine matrix seems not much different from the epoxide-epoxide cure. The T sub g versus cure-time for the epoxide-epoxide reaction was also studied. My 720 was cured by itself in an oil bath at 473 K for different lengths of time. The T sub g was found to increase exponentially with the cure time, and a maximum T sub g of about 450 K was reached after eleven hours. The reaction was found to be inhibited by running the sample under argon.

  9. Electron beam curing of epoxy resins by cationic polymerization

    SciTech Connect

    Janke, C.J.; Dorsey, G.F.; Havens, S.J.

    1996-12-31

    A Cooperative Research and Development Agreement (CRADA) sponsored by the Department of Energy Defense Programs and 10 industrial partners has been established to develop high performance Electron Beam (EB) curable polymer matrix composites. EB curing of composites has a number of advantages over conventional thermal curing. Composites cured by EB have much shorter cure times, lower overall energy requirements, and reduced thermal stresses in the cured part. Furthermore, less expensive tooling can be used since the process occurs at lower temperatures. Preliminary investigations have determined that conventional epoxy resins can be cured at selectable temperatures with high glass transition temperatures (essentially the same as with thermal curing), while still exhibiting equivalent or comparable mechanical properties. A cationic photoinitiator at a concentration of 1-3 parts per hundred of the epoxy resin is required for this process. Gamma cell screening of cationic photoinitiators with bisphenol A, bisphenol F, and cycloaliphatic epoxies demonstrated that diaryliodonium salts of weakly nucleophilic anions such as hexafluoroantimonate are most effective. Diaryliodonium salts were also found to be the most effective initiators for the cationic polymerization of epoxy resins when a high energy/power electron beam accelerator was used as the source of ionizing radiation. For example Dow Tactix 123 (bisphenol A epoxy) containing 3 phr (4-octyloxyphenyl) phenyliodonium hexafluoroantimonate was irradiated at a total dosage of 100 kGy. Glass transition temperature (tan delta) of the cured material as determined by dynamic mechanical analysis was 182{degrees}C as compared to 165{degrees}C for the thermally cured material.

  10. 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.

  11. Thermoanalytical characterization of visible light cure dental composites.

    PubMed

    Vaidyanathan, J; Vaidyanathan, T K; Wang, Y; Viswanadhan, T

    1992-01-01

    Selected commercial and experimental composites and resin systems have been evaluated by thermal analysis techniques of Differential Scanning Calorimetry, Thermogravimetric Analysis and Thermomechanical Analysis. Important thermal data such as heat of cure, coefficient of thermal expansion, dimensional changes over selected temperature ranges, filler weight percent, onset temperature of decomposition, etc. have been determined. Heat of cure, thermal expansion coefficient and dimensional changes appear to follow an inverse linear regression fit with filler fraction in the composite. Thermal expansion changes and exothermic reactions with temperature indicate secondary cure during postcure heating. The thermally-induced decomposition occurs in multiple stages indicating presence of different structural species in the resin matrix.

  12. 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

  13. Cure4Kids - building online learning and collaboration networks.

    PubMed

    Quintana, Yuri; Nambayan, Ayda; Ribeiro, Raul; Bowers, Lynne; Shuler, Ana; O'Brien, Richard

    2003-01-01

    The International Outreach Program of St. Jude Childrens' Research Hospital has been developing programs to help countries with limited resources develop treatment centers to treat children with catastrophic diseases such as pediatric cancer and AIDS. Cure4Kids (www.cure4kids.org) is the Internet learning network that delivers medical education to doctors and nurses on pediatric cancer and AIDS. The objective of Cure4Kids is not only education, but also to provide tools for communications and collaborations among individuals. PMID:14728482

  14. Remnant percolative disorder in highly-cured networks

    SciTech Connect

    Adolf, D.; Hance, B.; Martin, J.E. )

    1993-05-24

    The authors have previously reported viscoelastic measurements demonstrating that fully-cured networks and critical gels exhibit similar relaxation spectra, implying that fully-cured networks are somewhat ill- connected. Here, they present restricted valence percolation simulations of networks well beyond the percolation transition that explicitly display remnant disorder over length scales less than the correlation length of the network. They conclude that the topology of highly-cured networks is not well described by a regular three- dimensional tennis net but is ill-connected over length scales that correspond to relaxation modes of practical interest.

  15. Intestinal diamine oxidases and enteral-induced histaminosis: studies on three prognostic variables in an epidemiological model.

    PubMed

    Sattler, J; Lorenz, W

    1990-01-01

    The danger of luminal histamine administered orally or formed in the intestinal fluid by bacteria has long been neglected. However, the demonstration of blocking intestinal diamine oxidase (DAO) by a variety of common drugs has revived the discussion and has created a new disease concept: enteral-induced histaminosis. In an animal model the three central prognostic variables of this disease concept (large amounts of histamine in food to make the individual ill, blocking of DAO by commonly used drugs, and the relationship between increased plasma histamine levels and disease manifestation by exogenous histamine application) were tested with randomized trials in vivo and biochemical tests in vitro using semipurified enzymes from pig and man. In the first trials authentic histamine in quantities similar to that in normal amounts of food or cheese bought from a supermarket produced life-threatening reactions if the DAO was inhibited by pretreatment with aminoguanidine. In the second series of experiments in vitro a numerous commonly used drugs was shown to inhibit both the porcine and human enzyme. Some of the inhibitors were really strong, such as dihydralazine, chloroquine, pentamidine, cycloserine, clavulanic acid, dobutamine, pancuronium and others. The type of inhibition was sometimes competitive as in the case of dihydralazine and pancuronium, sometimes non competitive (e.g. pentamidine) which may be important for long-term treatment. In the third group of experiments a relationship between the dose of i.v. injected histamine and the elevation in plasma histamine levels and clinical symptoms in pigs was demonstrated. Hence, elevated plasma histamine in pigs acts as a pathogenetic factor for the disease manifestation. It is concluded that after modelling enteral-induced histaminosis in an animal the trias of variables shown in this study should be consequently investigated in man.

  16. Involvement of diamine oxidase and peroxidase in insolubilization of the extracellular matrix: implications for pea nodule initiation by Rhizobium leguminosarum.

    PubMed

    Wisniewski, J P; Rathbun, E A; Knox, J P; Brewin, N J

    2000-04-01

    Rhizobium leguminosarum colonizes host cells and tissues through infection threads, which are tubular in-growths of the plant cell wall. Monoclonal antibody MAC265 recognizes a plant matrix glycoprotein (MGP) associated with the lumen of these infection threads. This glycoprotein is also released in soluble form from the root tips of pea seedlings. In the presence of hydrogen peroxide, release of glycoprotein from root tips was not observed. Extractability from root tips was therefore used as the basis for investigating the peroxide-driven insolubilization of MGP and the possible involvement of two extracellular enzymes, peroxidase (POD) and diamine oxidase (DAO), was investigated. Release of MGP from root tips was enhanced by application of POD and DAO inhibitors (salicylhydroxamic acid and o-phenanthroline, respectively). Furthermore, release of MGP was inhibited by pretreatment of roots with putrescine (the substrate of DAO) and also by application of a partially purified extract of DAO from pea shoots. Following inoculation of pea roots with R. leguminosarum, elevated levels of DAO transcript were observed by reverse transcriptase-polymerase chain reaction (RT-PCR), but these then dropped to a low level from 4 to 10 days post inoculation, rising again in more mature nodules. In situ hybridization studies indicated that the bulk of the transcription was associated with the infected tissue in the center of the nodule. On the basis of these observations, we postulate that DAO may be involved in the peroxide-driven hardening of MGP in the lumen of infection threads and in the intercellular matrix.

  17. Urine 1,6-Hexamethylene Diamine (HDA) Levels Among Workers Exposed to 1,6-Hexamethylene Diisocyanate (HDI)

    PubMed Central

    Gaines, Linda G. T.; Fent, Kenneth W.; Flack, Sheila L.; Thomasen, Jennifer M.; Ball, Louise M.; Richardson, David B.; Ding, Kai; Whittaker, Stephen G.; Nylander-french, Leena A.

    2010-01-01

    Urinary 1,6-hexamethylene diamine (HDA) may serve as a biomarker for systemic exposure to 1,6-hexamethylene diisocyanate (HDI) in occupationally exposed populations. However, the quantitative relationships between dermal and inhalation exposure to HDI and urine HDA levels have not been established. We measured acid-hydrolyzed urine HDA levels along with dermal and breathing-zone levels of HDI in 48 automotive spray painters. These measurements were conducted over the course of an entire workday for up to three separate workdays that were spaced approximately 1 month apart. One urine sample was collected before the start of work with HDI-containing paints and subsequent samples were collected during the workday. HDA levels varied throughout the day and ranged from nondetectable to 65.9 μg l−1 with a geometric mean and geometric standard deviation of 0.10 μg l−1 ± 6.68. Dermal exposure and inhalation exposure levels, adjusted for the type of respirator worn, were both significant predictors of urine HDA levels in the linear mixed models. Creatinine was a significant covariate when used as an independent variable along with dermal and respirator-adjusted inhalation exposure. Consequently, exposure assessment models must account for the water content of a urine sample. These findings indicate that HDA exhibits a biphasic elimination pattern, with a half-life of 2.9 h for the fast elimination phase. Our results also indicate that urine HDA level is significantly associated with systemic HDI exposure through both the skin and the lungs. We conclude that urinary HDA may be used as a biomarker of exposure to HDI, but biological monitoring should be tailored to reliably capture the intermittent exposure pattern typical in this industry. PMID:20530123

  18. Synthesis and biological studies of pyrazolyl-diamine Pt(II) complexes containing polyaromatic DNA-binding groups.

    PubMed

    Gama, Sofia; Mendes, Filipa; Esteves, Teresa; Marques, Fernanda; Matos, António; Rino, José; Coimbra, Joana; Ravera, Mauro; Gabano, Elisabetta; Santos, Isabel; Paulo, António

    2012-11-01

    New [PtCl(pz*NN)](n+) complexes anchored by pyrazolyl-diamine (pz*NN) ligands incorporating anthracenyl or acridine orange DNA-binding groups have been synthesized so as to obtain compounds that would display synergistic effects between platination and intercalation of DNA. Study of their interaction with supercoiled DNA indicated that the anthracenyl-containing complex L(2) Pt displays a covalent type of binding, whereas the acridine orange counterpart L(3) Pt shows a combination of intercalative and covalent binding modes with a strong contribution from the former. L(2) Pt showed a very strong cytotoxic effect on ovarian carcinoma cell lines A2780 and A2780cisR, which are, respectively, sensitive to and resistant to cisplatin. In these cell lines, L(2) Pt is nine to 27 times more cytotoxic than cisplatin. In the sensitive cell line, L(3) Pt showed a cytotoxic activity similar to that of cisplatin, but like L(2) Pt was able significantly to overcome cisplatin cross-resistance. Cell-uptake studies showed that L(2) Pt accumulates preferentially in the cytoplasm, whereas L(3) Pt reaches the cell nucleus more easily, as clearly visualized by time-lapse confocal imaging of live A2870 cells. Altogether, these findings seem to indicate that interaction with biological targets other than DNA might be involved in the mechanism of action of L(2) Pt because this compound, despite having a weaker ability to target the cell nucleus than L(3) Pt, as well as an inferior DNA affinity, is nevertheless more cytotoxic. Furthermore, ultrastructural studies of A2870 cells exposed to L(2) Pt and L(3) Pt revealed that these complexes induce different alterations in cell morphology, thus indicating the involvement of different modes of action in cell death.

  19. 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.

  20. 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.