Quantitation of buried contamination by use of solvents. [degradation of silicone polymers by amine solvents

NASA Technical Reports Server (NTRS)

Pappas, S. P.; Hsiao, Y. C.; Hill, L. W.

1973-01-01

Spore recovery form cured silicone potting compounds using amine solvents to degrade the cured polymers was investigated. A complete list of solvents and a description of the effect of each on two different silicone polymers is provided.

Development and evaluation of epoxidized soybean oil-based polymers

NASA Astrophysics Data System (ADS)

Juangvanich, Nuanpen

Epoxidized Soybean Oil (ESO) based polymers were developed using diamine curing agents and BF3:NH2C2H5 as catalyst. Reactions involved the curing process were explored and monitored by DSC and IR analysis. Amine-epoxy addition reactions governed the main curing reaction at the temperature range of 60--235°C, and the supplementary reactions at higher temperatures were either homopolymerization or etherification reaction. In the aliphatic curing reactions, the epoxy-rich system favored the supplementary reactions at high temperature, however, ESO cured with 1,6 hexanediamine (HDA) always produced the high temperature reaction products, due to some side reactions and the high volatile nature. The curing reaction with aromatic diamines produced inherent rigidity to the cured ESO network, which decreased the high temperature reactions. The system cured with a short aromatic diamine, 1,4-phenyldiamine (PDA), produced a small extent of high temperature reaction, as well. It was believed that the long length diamine with wide separation of the two amines underwent an intermolecular cross-linking reaction, and derived better properties than the shorter diamine. A post-cure process was used to improve the final polymer properties by increasing the temperature after the initial curing reaction was quenched due to gelation. Extending the time of post-curing did not significantly improve properties of the final ESO polymers. Exposing the cured samples at 180°C for longer than 12 hours decreased the properties of the cured material, due to thermal strain generating in the network structure. To increase time efficiency, short heat cycles were performed by post-curing right after gelation, and the cured ESO polymer had tensile strength of 32 MPa, modulus 750 MPa and toughness 1.3 MPa. With the introduction of EPON 828, the mechanical properties of a new ESO polymer improved; having strength above 40 MPa, modulus great than 1,000 MPa, and Tg higher than 40°C. Finally, a rice hull particleboard was developed using the cured ESO resin as adhesive, and the board had strength comparable to the National Bureau of Standards minimum requirement for particleboard. A 35 wt % of ESO resin imparted the highest strength for the rice hull board, with a value of 15.5 MPa.

Influence of various cooking methods on the concentrations of volatile N-nitrosamines and biogenic amines in dry-cured sausages.

PubMed

Li, Ling; Wang, Peng; Xu, Xinglian; Zhou, Guanghong

2012-05-01

N-nitrosamines, biogenic amines, and residual nitrites are harmful substances and are often present in cured meats. The effects of different cooking methods (boiling, pan-frying, deep-frying, and microwave) were investigated on their contents in dry-cured sausage. The various N-nitrosamines were isolated by a steam distillation method and analyzed by gas chromatography mass spectrometry (GC-MS). The biogenic amines were determined after extraction with perchloric acid as dansyl derivatives by high-performance liquid chromatography (HPLC) method. The results showed that initial dry-cured raw sausage contained 5.31 μg/kg of total N-nitrosamines. Cooking by deep-frying or pan-frying resulted in products having the highest (P < 0.05) contents, compared with boiling or microwave treatments, which were not different from the raw. Although frying increased the content of N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), and N-nitrosopyrrolidine (NPYR), it decreased the contents of histamine and cadaverine. Boiling and microwave treatments decreased the total biogenic amines significantly (P < 0.05). Residual nitrite was significantly reduced by cooking treatments. The results suggest that boiling and microwave treatments were more suitable methods for cured meat. © 2012 Institute of Food Technologists®

Effects of plant polyphenols and a-tocopherol on lipid oxidation, microbiological characteristics, and biogenic amines formation in dry-cured bacons

USDA-ARS?s Scientific Manuscript database

Effects of plant polyphenols (tea polyphenol, grape seed extract, and gingerol) and a-tocopherol on physicochemical parameters, microbiological counts, and biogenic amines were determined in dry-cured bacons at the end of ripening. Results showed that plant polyphenols and a-tocopherol significantly...

Monomer-to-polymer conversion and micro-tensile bond strength to dentine of experimental and commercial adhesives containing diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide or a camphorquinone/amine photo-initiator system.

PubMed

Miletic, Vesna; Pongprueksa, Pong; De Munck, Jan; Brooks, Neil R; Van Meerbeek, Bart

2013-10-01

To compare the degree of conversion (DC) of adhesives initiated by diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) or a camphorquinone/tertiary amine system (CQ/Amine) as well as their 'immediate' micro-tensile bond strength (μTBS) to bur-cut dentine. DC of Scotchbond Universal ('SBU'; 3M ESPE), its experimental counterpart containing TPO as photo-initiator system, an experimental G-aenial Bond ('Ga-B'; GC) adhesive formulation, and an experimental LUB-102 adhesive formulation ('LUB', Kuraray Noritake), containing as photo-initiatior system either 2wt% CQ along with 2wt% tertiary amine ('SBU_CQ/Amine'; 'Ga-B_CQ/Amine'; 'LUB_CQ/Amine'), or 2wt% TPO ('SBU_TPO'; 'Ga-B_TPO'; 'LUB_TPO'), was determined using Fourier-transform infrared spectroscopy (FTIR), after being cured with a dual-wavelength light-curing unit (bluephase 20i, Ivoclar Vivadent). The same adhesive formulations were applied to bur-cut mid-coronal dentine of intact human molars, and subjected to a μTBS test after 1-week water storage. Besides being applied following a self-etch (SE) application mode, the adhesive formulations SBU_CQ/Amine and SBU_TPO were also applied following an etch-and-rinse (E&R) mode, this both for DS and μTBS measurement. No significant difference in DC was found for any of the adhesive formulations, except for SBU_CQ/Amine_SE and SBU_TPO_SE. For both SBU formulations, a significantly higher DC was reached for the E&R than the SE approach. Regarding μTBS, no significant differences were recorded, except for the significantly higher μTBS measured for SBU_CQ/Amine_E&R and SBU_TPO_E&R. In self-etch adhesives, the photo-initiator TPO may be used instead of CQ/Amine. The curing and 'immediate' bonding efficiency depended on the application protocol (E&R versus SE), but not on the photo-initiator system. The photo-initiator TPO may be used in self-etch adhesives instead of CQ/Amine with similar curing and 'immediate' bonding efficiency. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

Jones, Brad H.; Wheeler, David R.; Black, Hayden T.

Physical stress relaxation in rubbery, thermoset polymers is limited by cross-links, which impede segmental motion and restrict relaxation to network defects, such as chain ends. In parallel, the cure shrinkage associated with thermoset polymerizations leads to the development of internal residual stress that cannot be effectively relaxed. Recent strategies have reduced or eliminated such cure stress in thermoset polymers largely by exploiting chemical relaxation processes, wherein temporary cross-links or otherwise transient bonds are incorporated into the polymer network. In this paper, we explore an alternative approach, wherein physical relaxation is enhanced by the incorporation of organometallic sandwich moieties into themore » backbone of the polymer network. A standard epoxy resin is cured with a diamine derivative of ferrocene and compared to conventional diamine curing agents. The ferrocene-based thermoset is clearly distinguished from the conventional materials by reduced cure stress with increasing cure temperature as well as unique stress relaxation behavior above its glass transition in the fully cured state. The relaxation experiments exhibit features characteristic of a physical relaxation process. Furthermore, the cure stress is observed to vanish precipitously upon deliberate introduction of network defects through an increasing imbalance of epoxy and amine functional groups. Finally, we postulate that these beneficial properties arise from fluxional motion of the cyclopentadienyl ligands on the polymer backbone.« less

Solubilization and spore recovery from silicone polymers. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Hsiao, Y. C.

1974-01-01

A non-sporicidal technique for solvent degradation of cured silicone polymers was developed which involves chemical degradation of cured silicone polymers by amine solvents at room temperature. Substantial improvements were obtained in the recovery of seeded spores from room temperature cured polymers as compared to the standard recovery procedures, which indicates that the curing process is not sufficiently exothermic to reduce spore viability. The dissolution reaction of cured silicone polymers whith amine solvents is proposed to occur by bimolecular nucleophilic displacement. The chemical structure of silicone polymers was determined by spectroscopic methods. The phenyl to methyl ratio, R/Si ratio, molecular weight, and hydroxyl content of the silicone resins were determined.

Effects of plant polyphenols and a-tocopherol on lipid oxidation, residual nitrites, biogenic amines, and N-nitrosamines formation during ripening and storage of dry-cured bacon

USDA-ARS?s Scientific Manuscript database

Effects of plant polyphenols (green tea polyphenols (GTP) and grape seed extract (GSE) and a-tocopherol on physicochemical parameters, lipid oxidation, residual nitrite, microbiological counts, biogenic amines, and N-nitrosamines were determined in bacons during dry-curing and storage. Results show ...

Component Release and Mechanical Properties of Endodontic Sealers following Incorporation of Antimicrobial Agents.

PubMed

Gjorgievska, Elizabeta S; Nicholson, John W; Coleman, Nichola J; Booth, Samantha; Dimkov, Aleksandar; Hurt, Andrew

2017-01-01

Root canal sealers with antimicrobial activity are highly beneficial; therefore, their antimicrobial properties could be improved by incorporation of antimicrobial agents. In the present study, the release of the quaternary ammonium compounds from endodontic sealers admixed with either benzalkonium chloride (BC) or cetylpyridinium chloride (CPC) at loadings of 2% wt was monitored. The effect of these additives on the compressive strengths and their release from the sealers was determined after 1 and 4 weeks. All of the materials studied were found to be capable of releasing antimicrobial additive in useful quantities. The release of CPC occurred to a statistically significant greater extent than BC for all materials. The addition of both BC and CPC generally decreased the compressive strength of all the endodontic sealers, with the exception of CPC in AH Plus, where the compressive strength was significantly increased. This suggests that, for these endodontic sealers, the antimicrobial additives alter the setting chemistry. AH Plus is an epoxy-based material cured with an amine, and in this case the increase in compressive strength with CPC is attributed to an enhanced cure reaction with this system. In all other cases, the additive inhibited the cure reaction to a greater or lesser extent.

Effects of plant polyphenols and α-tocopherol on lipid oxidation, microbiological characteristics, and biogenic amines formation in dry-cured bacons.

PubMed

Wang, Yongli; Li, Feng; Zhuang, Hong; Li, Lianghao; Chen, Xiao; Zhang, Jianhao

2015-03-01

Effects of plant polyphenols (tea polyphenol [TP], grape seed extract [GSE], and gingerol) and α-tocopherol on physicochemical parameters, microbiological counts, and biogenic amines were determined in dry-cured bacons at the end of ripening. Results showed that plant polyphenols and α-tocopherol significantly decreased pH, thiobarbituric acid reactive substances content, and total volatile basic nitrogen (TVBN) compared with the control (P < 0.05). Microbial counts and biogenic amine contents in dry-cured bacons were affected by plant polyphenols or α-tocopherol, with TP being the most effective (P < 0.05) in reducing aerobic plate counts, Enterobacteriaceae, Micrococcaceae, yeast, and molds, as well as in inhibiting formation of putrescine, cadaverine, tyramine, and spermine. Principal component analysis indicated that the first 2 principal components (PC) explained about 85.5% of the total variation. PC1 was related with physicochemical factors, parts of biogenic amines, and spoilage microorganisms, whereas PC2 grouped the TVBN, tyramine, 2-phenylethylamine, yeast, and molds. These findings suggest that plant polyphenols, especially TP, could be used to process dry-cured bacons to improve the quality and safety of finished products. © 2015 Institute of Food Technologists®

Sprayable low density ablator and application process

NASA Technical Reports Server (NTRS)

Sharpe, M. H.; Hill, W. E.; Simpson, W. G.; Carter, J. M.; Brown, E. L.; King, H. M.; Schuerer, P. H.; Webb, D. D. (Inventor)

1978-01-01

A sprayable, low density ablative composition is described consisting esentially of: (1) 100 parts by weight of a mixture of 25-65% by weight of phenolic microballoons, 0-20% by weight of glass microballoons, 4-10% by weight of glass fibers, 25-45% by weight of an epoxy-modified polyurethane resin, 2-4% by weight of a bentonite dispersing aid, and 1-2% by weight of an alcohol activator for the bentonite; (2) 1-10 parts by weight of an aromatic amine curing agent; and (3) 200-400 parts by weight of a solvent.

Photo-cured PMMA/PEI core/shell nanoparticles surface-modified with Gd-DTPA for T1 MR imaging.

PubMed

Ratanajanchai, Montri; Lee, Don Haeng; Sunintaboon, Panya; Yang, Su-Geun

2014-02-01

Herein, we introduced amine-functionalized core-shell nanoparticles (Polymethyl methacrylate/Polyethyleneimine; PMMA/PEI) with surface primary amines (3.15×10(5) groups/particle) and uniform size distribution (150-200nm) that were prepared by one-step photo-induced emulsion polymerization. Further PEI-surface was modified with diethylenetriamine pentaacetic acid (DTPA) and introduced with Gd(III). The modified particles possessing DTPA can entrap a high content of Gd(III) ions of over 5.5×10(4)Gd/particle with stable chelation (no release of free Gd) at least 7h. The Gd-DTPA-conjugated core-shell nanoparticles (PMMA/PEI-DTPA-Gd NPs) enhanced the MRI intensity more than Primovist (a commercial hepatic contrast agent). Moreover, the PMMA/PEI-DTPA-Gd NPs showed non-cytotoxicity up to 250μM in normal liver cells. Thus, in vitro data suggested the PMMA/PEI-DTPA-Gd NPs is promising delivery system as a superior MRI contrast agent, especially for hepatic lesion targeted MR imaging. Copyright © 2013 Elsevier Inc. All rights reserved.

Component Release and Mechanical Properties of Endodontic Sealers following Incorporation of Antimicrobial Agents

PubMed Central

Nicholson, John W.; Coleman, Nichola J.; Booth, Samantha; Dimkov, Aleksandar

2017-01-01

Root canal sealers with antimicrobial activity are highly beneficial; therefore, their antimicrobial properties could be improved by incorporation of antimicrobial agents. In the present study, the release of the quaternary ammonium compounds from endodontic sealers admixed with either benzalkonium chloride (BC) or cetylpyridinium chloride (CPC) at loadings of 2% wt was monitored. The effect of these additives on the compressive strengths and their release from the sealers was determined after 1 and 4 weeks. All of the materials studied were found to be capable of releasing antimicrobial additive in useful quantities. The release of CPC occurred to a statistically significant greater extent than BC for all materials. The addition of both BC and CPC generally decreased the compressive strength of all the endodontic sealers, with the exception of CPC in AH Plus, where the compressive strength was significantly increased. This suggests that, for these endodontic sealers, the antimicrobial additives alter the setting chemistry. AH Plus is an epoxy-based material cured with an amine, and in this case the increase in compressive strength with CPC is attributed to an enhanced cure reaction with this system. In all other cases, the additive inhibited the cure reaction to a greater or lesser extent. PMID:28620615

Latent curing systems stabilized by reaction equilibrium in homogeneous mixtures of benzoxazine and amine

PubMed Central

Wang, Jun; Xu, Ya Zhen; Fu, Ya Fei; Liu, Xiang Dong

2016-01-01

Latent curing systems are widely used in industrial thermosets in applications such as adhesion, coating, and composites. Despite many attempts to improve the practicality of this dormant reaction system, the majority of commercially available latent products still use particulate hardeners or liquid compounds with blocked active groups. These formulations generally lack fluidity or rapid reaction characteristics and thus are problematic in some industry applications. Here we describe a novel concept that stabilizes highly reactive benzoxazine/amine mixtures by reaction equilibrium. These new latent benzoxazine curing systems have a long storable lifetime but very short gel time at 150 °C. The reversible reaction between benzoxazine and amine is further demonstrated by FT-IR spectral measurements and rheological experiments, and it is shown that the overall characteristics of the latent system are promising for many industrial applications. PMID:27917932

New diamine hardeners for epoxies

NASA Technical Reports Server (NTRS)

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

1977-01-01

Stronger amine-cured polyepoxides can be obtained by using those diaminobenzophenones and diaminodiphenylmethanes that have amine groups located at ortho or meta positions to carbonyl or methylene groups joining two benzene rings.

Surface engineering of nanoparticles with macromolecules for epoxy curing: Development of super-reactive nitrogen-rich nanosilica through surface chemistry manipulation

NASA Astrophysics Data System (ADS)

Jouyandeh, Maryam; Jazani, Omid Moini; Navarchian, Amir H.; Shabanian, Meisam; Vahabi, Henri; Saeb, Mohammad Reza

2018-07-01

Curing behavior of epoxy-based nanocomposites depends on dispersion state of nanofillers and their physical and chemical interactions with the curing moieties. In this work, a systematic approach was introduced for chemical functionalization of nanoparticles with macromolecules in order to enrich crosslinking potential of epoxy/amine systems, particularly at late stages of cure where the curing is diffusion-controlled. Super-reactive hyperbranched polyethylenimine (PEI)-attached nanosilica was materialized in this work to facilitate epoxy-amine curing. Starting from coupling [3-(2,3-epoxypropoxy) propyl] trimethoxysilane (EPPTMS) with hyperbranched PEI, a super-reactive macromolecule was obtained and subsequently grafted onto the nanosilica surface. Eventually, a thermally-stable highly-curable nanocomposite was attained by replacement of amine and imine groups of the PEI with imide and amide groups through the reaction with pyromellitic acid dianhydride. Fourier-transform infrared spectrophotometry, X-ray diffractometry, X-ray photoelectron spectroscopy and transmission electron microscopy approved successful grafting of polymer chains onto the nanosilica surface. Thermogravimetric analyses approved a relatively high grafting ratio of ca. 21%. Curing potential of the developed super-reactive nanoparticle was uncovered through nonisothermal differential scanning calorimetry signifying an enthalpy rise of ca. 120 J/g by addition of 2 wt.% to epoxy at 5 °C/min heating rate. Even at low concentration of 0.5 wt.%, the glass transition temperature of epoxy increased from 128 to 156 °C, demonstrating prolonged crosslinking.

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

NASA Astrophysics Data System (ADS)

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

2017-02-01

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

Hydrophobic Modification of Layered Clays and Compatibility for Epoxy Nanocomposites

PubMed Central

Lin, Jiang-Jen; Chan, Ying-Nan; Lan, Yi-Fen

2010-01-01

Recent studies on the intercalation and exfoliation of layered clays with polymeric intercalating agents involving poly(oxypropylene)-amines and the particular uses for epoxy nanocomposites are reviewed. For intercalation, counter-ionic exchange reactions of clays including cationic layered silicates and anionic Al-Mg layered double hydroxide (LDH) with polymeric organic ions afforded organoclays led to spatial interlayer expansion from 12 to 92 Å (X-ray diffraction) as well as hydrophobic property. The inorganic clays of layered structure could be modified by the poly(oxypropylene)amine-salts as the intercalating agents with molecular weights ranging from 230 to 5,000 g/mol. Furthermore, natural montmorillonite (MMT) clay could be exfoliated into thin layer silicate platelets (ca. 1 nm thickness) in one step by using polymeric types of exfoliating agents. Different lateral dimensions of MMT, synthetic fluorinated Mica and LDH clays had been cured into epoxy nanocomposites. The hydrophobic amine-salt modification resulting in high spacing of layered or exfoliation of individual clay platelets is the most important factor for gaining significant improvements of properties. In particular, these modified clays were reported to gain significant improvements such as reduced coefficient of thermal expansion (CTE), enhanced thermal stability, and hardness. The utilization of these layered clays for initiating the epoxy self-polymerization was also reported to have a unique compatibility between clay and organic resin matrix. However, the matrix domain lacks of covalently bonded crosslink and leads to the isolation of powder material. It is generally concluded that the hydrophobic expansion of the clay inter-gallery spacing is the crucial step for enhancing the compatibility and the ultimate preparation of the advanced epoxy materials.

Why do different criteria for 'cure' yield different conclusions in comparing two treatments for bacterial vaginosis?

PubMed

Thomas, Katherine K; Sanchez, Sixto; Garcia, Patricia J; Holmes, King K

2005-09-01

The objective of this study was to determine why different criteria for response to treatment of bacterial vaginosis (BV) led to markedly different conclusions about treatment efficacy in a randomized trial comparing metronidazole gel versus metronidazole/nystatin ovules. We compared the impact of two treatment regimens on individual components of Amsel and Nugent criteria at follow-up visits 14, 42, and 104 days after initiating treatment. Compared with gel, ovules more effectively eliminated amines, clue cells, and Gardnerella, Prevotella, or Mobiluncus morphotypes from vaginal fluid, thus achieving cure based on "usual" criteria (absence of BV by Amsel or Nugent criteria), but did not more effectively restore Lactobacillus morphotypes or lower vaginal pH, thus not meeting Federal Drug Administration (FDA) criteria for cure. Because early vaginal recolonization by lactobacilli was poor after both gel and ovules, FDA draft criteria for cure missed marked differences in treatment efficacies against Gardnerella, clue cells, and amines. Cure defined more "usually" may give more useful information.

Complex Cure Kinetics of the Tertiary Amine activated Reaction in DGEBA Epoxy Hardened with Diethanolamine

NASA Astrophysics Data System (ADS)

Ancipink, Windy; McCoy, John; Clarkson, Caitlyn; Kropka, Jamie; Celina, Mathias; Giron, Nicholas; Hailesilassie, Lebelo; Fredj, Narjes

The curing of a diglycidyl ether of bisphenol-A (DGEBA) epoxy with diethanolamine (DEA) involves a well understood fast amine-epoxide reaction followed by a more complicated slower hydroxyl-epoxide reaction. The time scale of these two reactions are well separated and can be studied independently from one another. The initial amine-epoxide reaction results in a tertiary amine adduct which is a product of the direct reaction of a secondary amine from the DEA reacting with a single DGEBA epoxide. The second hydroxyl-epoxide reaction results in a highly crosslinked glassy epoxy resin. The deviation in the mechanisms between high and low temperatures are discerned through the use of differential scanning calorimetry (DSC), infrared spectroscopy (IR), and isothermal microcalorimetry (IMC) data. Observations of reaction rates at temperatures ranging from 30° C to 110° C have led to the determination that the hydroxyl-epoxide reaction is temperature sensitive. The hydroxyl-epoxide reaction occurs through two different mechanisms: at low temperatures, the reaction is catalyzed by the tertiary amine adduct; at higher temperatures, the reaction does not appear to be catalyzed. Sandia National Laboratories, Albuquerque, NM.

A one-pot parallel reductive amination of aldehydes with heteroaromatic amines.

PubMed

Bogolubsky, Andrey V; Moroz, Yurii S; Mykhailiuk, Pavel K; Panov, Dmitriy M; Pipko, Sergey E; Konovets, Anzhelika I; Tolmachev, Andrey

2014-08-11

A parallel reductive amination of heteroaromatic amines has been performed using a combination of ZnCl2-TMSOAc (activating agents) and NaBH(OAc)3 (reducing agent). A library of diverse secondary amines was easily prepared on a 50-300 mg scale.

Grafting of polyethylenimine onto cellulose nanofibers for interfacial enhancement in their epoxy nanocomposites.

PubMed

Zhao, Jiangqi; Li, Qingye; Zhang, Xiaofang; Xiao, Meijie; Zhang, Wei; Lu, Canhui

2017-02-10

Cellulose nanofibers (CNFs) were surface-modified with polyethyleneimine (PEI), which brought plentiful amine groups on the surface of CNFs, leading to a reduced hydrogen bond density between CNFs and consequently less CNFs agglomerates. The amine groups could also react with the epoxy as an effective curing agent that could increase the interfacial crosslinking density and strengthen interfacial adhesion. The tensile strength and Young's modulus of CNFs-PEI/Epoxy nanocomposites were 88.1% and 237.6% higher than those of neat epoxy, respectively. The tensile storage modulus of the nanocomposites also increased significantly at the temperature either below or above the Tg. The coefficient of thermal expansion for the CNFs-PEI/Epoxy nanocomposites was 22.2ppmK -1 , much lower than that of the neat epoxy (88.6ppmK -1 ). In addition, the thermal conductivity of the nanocomposites was observed to increase as well. The exceptional and balanced properties may provide the nanocomposites promising applications in automotive, construction and electronic devices. Copyright © 2016 Elsevier Ltd. All rights reserved.

Novel self-healing materials chemistries for targeted applications

NASA Astrophysics Data System (ADS)

Wilson, Gerald O.

Self-healing materials of the type developed by White and co-workers [1] were designed to autonomically heal themselves when damaged, thereby extending the lifetime of various applications in which such material systems are employed. The system was based on urea-formaldehyde microcapsules containing dicyclopentadiene (DCPD) and Grubbs' catalyst particles embedded together in an epoxy matrix. When a crack propagates through the material, it ruptures the microcapsules, releasing DCPD into the crack plane, where it comes in contact and reacts with the catalyst to initiate a ring opening metathesis polymerization (ROMP), bonding the crack and restoring structural continuity. The present work builds on this concept in several ways. Firstly, it expands the scope and versatility of the ROMP self-healing chemistry by incorporation into epoxy vinyl ester matrices. Major technical challenges in this application include protection of the catalyst from deactivation by aggressive curing agents, and optimization of the concentration of healing agents in the matrix. Secondly, new ruthenium catalysts are evaluated for application in ROMP-based self-healing materials. The use of alternative derivatives of Grubbs' catalyst gave rise to self-healing systems with improved healing efficiencies and thermal properties. Evaluation of the stability of these new catalysts to primary amine curing agents used in the curing of common epoxy matrices also led to the discovery and characterization of new ruthenium catalysts which exhibited ROMP initiation kinetics superior to those of first and second generation Grubbs' catalysts. Finally, free radical polymerization was evaluated for application in the development of bio-compatible self-healing materials. [1] White, S. R.; Sottos, N. R.; Geubelle, P. R.; Moore, J. S.; Kessler, M. R.; Sriram, S. R.; Brown, E. N.; Viswanathan, S. Nature 2001, 409, 794.

Morphology and properties of amine terminated poly(arylene ether ketone) and poly(arylene ether sulfone) modified epoxy resin systems

NASA Technical Reports Server (NTRS)

Cecere, J. A.; Mcgrath, J. E.; Hedrick, J. L.

1986-01-01

Epoxy resin networks cured with DDS were modified by incorporating tough ductile thermoplastics such as the amine terminated polyether sulfones and amine terminated polyether ketones. Both linear copolymers were able to significantly improve the fracture toughness values at the 15 and 30 weight percent concentrations examined. These improvements in fracture toughness were achieved without any significant change in the flexural modulus.

Durability of self-healing woven glass fabric/epoxy composites

NASA Astrophysics Data System (ADS)

Yin, Tao; Rong, Min Zhi; Zhang, Ming Qiu; Zhao, Jian Qing

2009-07-01

In this work, the durability of the healing capability of self-healing woven glass fabric/epoxy laminates was investigated. The composites contained a two-component healing system with epoxy-loaded urea-formaldehyde microcapsules as the polymerizable binder and CuBr2(2-methylimidazole)4 (CuBr2(2-MeIm)4) as the latent hardener. It was found that the healing efficiency of the laminates firstly decreased with storage time at room temperature, and then leveled off for over two months. By means of a systematic investigation and particularly verification tests with dynamic mechanical analysis (DMA), diffusion of epoxy monomer from the microcapsules due to volumetric contraction of the composites during manufacturing was found to be the probable cause. The diffusing sites on the microcapsules were eventually blocked because the penetrated resin was gradually cured by the remnant amine curing agent in the composites' matrix, and eventually the healing ability was no longer reduced after a longer storage time. The results should help to develop approaches for improving the service stability of the laminates.

Anti-corrosion mechanism of epoxy-resin and different content Fe2O3 coatings on magnesium alloy

NASA Astrophysics Data System (ADS)

Jin, Tao; Kong, Fan-mei; Bai, Rui-qin; Zhang, Ru-liang

2016-12-01

In this study, anti-corrosion coatings were prepared and coated successfully on magnesium alloy substrates by mixing nanopowders, solvent, curing agent with epoxy resin. The effect of the amount of iron trioxide (Fe2O3) on the adhesion strength and corrosion resistance on magnesium alloy was investigated with standard protocols, and electrochemical measurements were also made in 3.5 wt.% NaCl solutions. The surface morphology and corrosion mechanism after corrosion tests was characterized using FESEM analysis. Nanoparticles in matrix acted as filler, and interstitial cross-linked spaces and other coating artifacts regions (micro cracks and voids) would all affect the anti-corrosion properties of coating. The results showed the proper powder content not only provided adhesion strength to these coatings but also improved obviously their anticorrosion. Hydrogen bound to the amine nitrogen (1N) could take part in the curing process rather than hydrogen of the amide site due to the smaller Δ G and the more stable configuration.

Transition Metal Free C-N Bond Forming Dearomatizations and Aryl C-H Aminations by in Situ Release of a Hydroxylamine-Based Aminating Agent.

PubMed

Farndon, Joshua J; Ma, Xiaofeng; Bower, John F

2017-10-11

We outline a simple protocol that accesses directly unprotected secondary amines by intramolecular C-N bond forming dearomatization or aryl C-H amination. The method is dependent on the generation of a potent electrophilic aminating agent released by in situ deprotection of O-Ts activated N-Boc hydroxylamines.

Quantitation of buried contamination by use of solvents

NASA Technical Reports Server (NTRS)

Pappas, S. P.; Hsiao, P.; Hill, L. W.

1972-01-01

Solubilization studies were carried out on various cured silicone resins. A solvent spectrum was prepared. It was found that complete dissolution of cured silicone resins could be achieved without extensive physical degradation of samples. Based on the solubilization results, amine solvents were selected for spore viability studies.

A Simple Secondary Amine Synthesis: Reductive Amination Using Sodium Triacetoxyborohydride

NASA Astrophysics Data System (ADS)

Carlson, Merle W.; Ciszewski, James T.; Bhatti, Micah M.; Swanson, Wesley F.; Wilson, Anne M.

2000-02-01

We present a reductive amination experiment for a second-semester organic chemistry class. It utilizes an imine intermediate and sodium triacetoxyborohydride, a mild reducing agent. The progress of the reaction is followed by TLC as the starting materials (the aldehyde and primary amine), the imine intermediate, and the secondary amine product are visible under ultraviolet light. This experiment provides an introduction to the observation of intermediates, the synthesis of amines, and the concept of mild reducing agents.

Laminate comprising fibers embedded in cured amine terminated bis-imide

NASA Technical Reports Server (NTRS)

Kumar, D. (Inventor); Fohlen, G. M. (Inventor); Parker, J. A. (Inventor)

1986-01-01

Amine terminated bisaspartimides are prepared by a Michael type reaction of an aromatic bismaleimide and an aromatic diamine in an aprotic solvent. These bisaspartimides are thermally polymerized to yield tough, resinous polymers crosslinked through -NH- groups. Such polymers are useful in applications requiring materials with resistance to change at elevated temperatures.

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

PubMed

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

2017-03-01

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

69 FR 41789 - Notice of Availability of Government-Owned Inventions; Available for Licensing

Federal Register 2010, 2011, 2012, 2013, 2014

2004-07-12

...,441: Phthalonitrile Prepolymer as High Temperature Sizing Material for Composite Fibers, Navy Case No... Microwave Electrode Structures, Navy Case No. 74,654.//U.S. Patent No. 5,410,404: Fiber Grating-based...,001,926: Fiber-reinforced Phthalonitrile Composite Cured with Low-reactivity Aromatic Amine Curing...

Characterization-curing-property studies of HBRF 55A resin formulations

NASA Technical Reports Server (NTRS)

Pearce, E. M.; Mijovic, J.

1985-01-01

Characterization curing property investigations on HBRF 55A resin formulations are reported. The initial studies on as received cured samples cut from a full-size FWC are reviewed. Inadequacies of as-received and aged samples are pointed out and additional electron microscopic evidence is offered. Characterization of as-received ingredients of HBRF 55A formulation is described. Specifically, Epon 826, Epon 828, EpiRez 5022, RD-2 and various amines, including Tonox and Tonox 60.40, were characterized. Cure kinetics of various formulations are investigated. Changes in physical/thermal properties (viscosity, specific heat, thermal conductivity and density) during cure are described.

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

Happe, J.A.; Morgan, R.J.; Walkup, C.M.

The chemical composition of commercial BF/sub 3/:amine complexes are variable and contain BF/sub 4//sup -/ and BF/sub 3/(OH)/sup -/ salts together with other unidentified highly reactive species. The BF/sub 3/:amine complexes, which are susceptible to hydrolysis, also partially convert to the BF/sub 4//sup -/ salt (i.e. BF/sub 4//sup -/NH/sub 3//sup +/C/sub 2/H/sub 5/) upon heating. This salt formation is accelerated in dimethyl sulfoxide solution and in the presence of the epoxides that are present in commercial prepregs. Commercial C fiber-epoxy prepregs are shown to contain either BF/sub 3/:NH/sub 2/C/sub 2/H/sub 5/ or BF/sub 3/:NHC/sub 5/H/sub 10/ species together with theirmore » BF/sub 4//sup -/ salts and a variety of boron-fluorine or carbon-fluorine prepreg species. Considerable variation in the relative quantities of BF/sub 3/:amine to its BF/sub 4//sup -/ salt was observed from prepreg lot to lot, which will cause variable viscosity-time-temperature prepreg cure profiles. It is concluded that the chemically stable and mobile BF/sub 4//sup -/ salt is the pre-dominant catalytic species, acting as a cationic catalyst for the prepreg cure reactions. During the early stages of cure the BF/sub 3/:amine catalyst converts to the BF/sub 4//sup -/ salt in the presence of epoxides, whereas the BF/sub 3/-prepreg species are susceptible to catalytic deactivation and immobilization.« less

Irradiated Chinese Rugao ham: Changes in volatile N-nitrosamine, biogenic amine and residual nitrite during ripening and post-ripening.

PubMed

Wei, Fashan; Xu, Xinglian; Zhou, Guanghong; Zhao, Gaiming; Li, Chunbao; Zhang, Yingjun; Chen, Lingzhen; Qi, Jun

2009-03-01

N-nitrosamines, biogenic amines and residual nitrite are harmful substances and often present in cured meat. The effects of gamma-irradiation (γ-irradiation) on these chemicals in dry-cured Chinese Rugao ham during ripening and post-ripening were investigated. Rugao hams were irradiated at a dose of 5kGy before ripening and were then ripened in an aging loft. Although γ-irradiation degraded tyramine, putrescine and spermine, on the other hand, it promoted the formation of spermidine, phenylethylamine, cadaverine and tryptamine. Residual nitrite was significantly reduced by γ-irradiation. N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA) and N-nitrosopyrrolidine (NPYR) were found in Chinese Rugao ham during ripening and post-ripening but could be degraded with γ-irradiation. The results suggest that γ-irradiation may be a potential decontamination measure for certain chemical compounds found in dry-cured meat.

The efficacy of vaginal clindamycin for the treatment of abnormal genital tract flora in pregnancy.

PubMed

Lamont, Ronald F; Jones, Brian M; Mandal, Debashis; Hay, Philip E; Sheehan, Marie

2003-01-01

To assess the efficacy of 2% clindamycin vaginal cream (CVC) to treat bacterial vaginosis (BV) in pregnancy. A prospective, randomized, double-blind, placebo-controlled, tricenter study. Four hundred and four women with BV on Gram stain at their first antenatal clinic visit were randomized to receive a 3-day course of 2% CVC or placebo. The outcome was assessed using an intention to treat analysis at 3 weeks and 6 weeks post-treatment according to three different diagnostic methods based on five criteria (Gram stain and all four elements of clinical composite criteria: vaginal discharge, abnormal vaginal pH, clue cells, amine odor), three criteria (vaginal pH, clue cells, amine odor) or two criteria (clue cells and amine odor) to reflect stringency of diagnosis, historical precedence and government agency recommendations respectively. Using five diagnostic criteria, 18% of CVC patients were cured and 70.8% either cured and/or improved compared to 1.6% and 12% of placebo patients respectively (p < 0.0001). Using three diagnostic criteria, 44.8% of CVC patients were cured and 77.3% were either cured and/or improved compared to 9.3% and 28.8% of placebo patients respectively (p < 0.000 1). Using two diagnostic criteria, 75.0% of CVC patients were cured compared to 18.0% of placebo patients (p < 0.0001 ). Recurrence rates in those CVC patients successfully treated were approximately 6% at 6 weeks post baseline and 10% at 28 to 34 weeks gestation. A 3-day course of CVC appears to be well tolerated by the mother and statistically significantly more efficacious than placebo in the treatment of BV during the second trimester of pregnancy.

Fluorescence Characterization of Cure and Water-Uptake in Polymers and Composites

DTIC Science & Technology

1994-06-01

the different wavelength DDS) in the stoichiometric mixture of DDS and EDDA calibration in both instruments as well as to some (ethylene dioxyl...diethyl amine) were obtained before temperature dependence of the excitation maxima. and after 1 h cure at 120°C. EDDA is an aliphatic However, the overall

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.

Urea Derivatives of 2-Aryl-benzothiazol-5-amines: A New Class of Potential Drugs for Human African Trypanosomiasis.

PubMed

Patrick, Donald A; Gillespie, J Robert; McQueen, Joshua; Hulverson, Matthew A; Ranade, Ranae M; Creason, Sharon A; Herbst, Zackary M; Gelb, Michael H; Buckner, Frederick S; Tidwell, Richard R

2017-02-09

A previous publication from this lab (Patrick, et al. Bioorg. Med. Chem. 2016, 24 , 2451 - 2465 ) explored the antitrypanosomal activities of novel derivatives of 2-(2-benzamido)ethyl-4-phenylthiazole (1), which had been identified as a hit against Trypanosoma brucei, the causative agent of human African trypanosomiasis. While a number of these compounds, particularly the urea analogues, were quite potent, these molecules as a whole exhibited poor metabolic stability. The present work describes the synthesis of 65 new analogues arising from medicinal chemistry optimization at different sites on the molecule. The most promising compounds were the urea derivatives of 2-aryl-benzothiazol-5-amines. One such analogue, (S)-2-(3,4-difluorophenyl)-5-(3-fluoro-N-pyrrolidylamido)benzothiazole (57) was chosen for in vivo efficacy studies based upon in vitro activity, metabolic stability, and brain penetration. This compound attained 5/5 cures in murine models of both early and late stage human African trypanosomiasis, representing a new lead for the development of drugs to combat this neglected disease.

Effects of a low-shrinkage methacrylate monomer and monoacylphosphine oxide photoinitiator on curing efficiency and mechanical properties of experimental resin-based composites.

PubMed

Manojlovic, Dragica; Dramićanin, Miroslav D; Milosevic, Milos; Zeković, Ivana; Cvijović-Alagić, Ivana; Mitrovic, Nenad; Miletic, Vesna

2016-01-01

This study investigated the degree of conversion, depth of cure, Vickers hardness, flexural strength, flexural modulus and volumetric shrinkage of experimental composite containing a low shrinkage monomer FIT-852 (FIT; Esstech Inc.) and photoinitiator 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO; Sigma Aldrich) compared to conventional composite containing Bisphenol A-glycidyl methacrylate (BisGMA) and camphorquinone-amine photoinitiator system. The degree of conversion was generally higher in FIT-based composites (45-64% range) than in BisGMA-based composites (34-58% range). Vickers hardness, flexural strength and modulus were higher in BisGMA-based composites. A polywave light-curing unit was generally more efficient in terms of conversion and hardness of experimental composites than a monowave unit. FIT-based composite containing TPO showed the depth of cure below 2mm irrespective of the curing light. The depth of cure of FIT-based composite containing CQ and BisGMA-based composites with either photoinitiator was in the range of 2.8-3.0mm. Volumetric shrinkage of FIT-based composite (0.9-5.7% range) was lower than that of BisGMA-based composite (2.2-12% range). FIT may be used as a shrinkage reducing monomer compatible with the conventional CQ-amine system as well as the alternative TPO photoinitiator. However, the depth of cure of FIT_TPO composite requires boosting to achieve clinically recommended thickness of 2mm. Copyright © 2015 Elsevier B.V. All rights reserved.

Elastomer-induced crevice corrosion and stress corrosion cracking of stainless steel heat exchanger plates in sour amine service

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

Hay, M.G.; Baron, J.J.; Moffat, T.A.

1996-08-01

Types S31600 and S31254 stainless steel heat exchanger plates have suffered crevice corrosion and stress corrosion cracking under gaskets in rich amine service in a sour gas plant. The gasket material, ethylene-propylene-diene monomer (EPDM), has been used successfully for many years at other sour gas plants. Laboratory testing has duplicated the corrosion observed and shown that the mechanism is synergistic sulfide-halide attack. The use of a bromine plus chlorine-activated curing system for the EPDM rubber gaskets provided the necessary halides. Laboratory testing identified some nickel-based superalloys which were resistant to this corrosion and also demonstrated that essentially halogen-free, peroxide-cured EPDMmore » gaskets do not cause attack of S31600 or S31254. The heat exchanger packs were replaced with S31600 plates and peroxide-cured EPDM gaskets having a specified total halogen concentration of 200 ppm maximum. Field operating experience has been excellent.« less

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.

Prediction of the Formulation Dependence of the Glass Transition Temperature for Amine-Epoxy Copolymers Using a Quantitative Structure-Property Relationship Based on the AM1 Method

DTIC Science & Technology

2004-02-01

Products and Chemicals , Inc . The stoichiometry of the DGEBA-PACM polymerization reaction was varied to yield epoxy/amine ratios ranging from ~2:1 through...equivalent). The DGEBA epoxy resin was cured with bis(p-aminocyclohexyl)methane (PACM) (EEW = 52.5 g/equivalent), which was acquired from Air

Degradable Networks Containing Silyl Ether Bonds

NASA Astrophysics Data System (ADS)

Bassampour, Zahra S.

Degradable networks possess applications in many fields such as medical implants, electrical devices, industrial coatings, adhesives, and aerospace. Silyl ether bonds are reactive functionalities capable of degrading under physiological condition without significantly affecting the pH of the surrounding environment. This dissertation focuses on preparative methods of degradable networks utilizing silyl ether functionalities. Epoxy polymers are broadly utilized in many different applications. Despite the broad utilization of epoxy polymer thermosets in long-term applications, these thermosets are not very popular candidates in short-term applications. This unpopularity is mostly due to the fact that epoxy networks are non-degradable systems, which results in their recycling being very costly and environmentally unfriendly. In the first and second part of this dissertation, the synthesis of various amine and thiol curing agents containing hydrolyzable silyl ether bonds is described. Using these curing agents, thermosetting epoxy polymers with degradable properties were prepared. The degradation behavior and thermal properties of the cured networks were studied. Age-related macular degeneration (AMD) is a leading cause of vision loss in the industrialized world. The high prevalence of AMD and the complications and shortcomings of available treatment options give rise to a great need for the development of novel types of biodegradable implants to provide sustainable drug release. The third part of this dissertation describes the utilization of hydrolyzable silyl ether bonds in the synthesis of novel implants capable of reserving and releasing a drug in a controlled manner in order to treat AMD. Base- catalyzed thiol-Michael reactions were exploited to prepare a series of biodegradable cross- linked networks. The networks were characterized by FTIR, TGA, and DMA. The effect of monomer structure on degradation, release behavior, and thermal properties was investigated.

Silane coupling agent for attaching fusion-bonded epoxy to steel.

PubMed

Tchoquessi Diodjo, Madeleine R; Belec, Lénaïk; Aragon, Emmanuel; Joliff, Yoann; Lanarde, Lise; Perrin, François-Xavier

2013-07-24

We describe the possibility of using γ-aminopropyltriethoxysilane (γ-APS) to increase the durability of epoxy powder coating/steel joints. The curing temperature of epoxy powder coatings is frequently above 200 °C, which is seen so far as a major limitation for the use of the heat-sensitive aminosilane coupling agent. Despite this limitation, we demonstrate that aminosilane is a competitive alternative to traditional chromate conversion to enhance the durability of epoxy powder coatings/steel joints. Fourier-transform reflection-absorption infrared spectroscopy (FT-RAIRS), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) were used to identify the silane deposition conditions that influence the adhesion of epoxy powder coatings on steel. We show that AFM analysis provides highly sensitive measurements of mechanical property development and, as such, the degree of condensation of the silane. The joint durability in water at 60 °C was lower when the pH of the γ-APS solution was controlled at 4.6 using formic acid, rather than that at natural pH (10.6). At the curing temperature of 220 °C, oxidation of the carbon adjacent to the amine headgroup of γ-APS gives amide species by a pseudofirst-order kinetics. However, a few amino functionalities remain to react with oxirane groups of epoxy resin and, thus, strengthen the epoxy/silane interphase. The formation of ammonium formate in the acidic silane inhibits the reaction between silane and epoxy, which consequently decreases the epoxy/silane interphase cohesion. We find that the nanoroughness of silane deposits increases with the cure temperature which is beneficial to the wet stability of the epoxy/steel joints, due to increased mechanical interlocking.

A One-Component, Fast-Cure, and Economical Epoxy Resin System Suitable for Liquid Molding of Automotive Composite Parts.

PubMed

Wang, Yiru; Liu, Wanshuang; Qiu, Yiping; Wei, Yi

2018-04-27

Imidazole cured epoxy resin systems were evaluated for one-component, fast-curing resins for liquid molding of automotive composite parts according to industry requirements. It was demonstrated that an epoxy resin-1-(cyanoethyl)-2-ethyl-4-methylimidazol(EP-1C2E4MIM) system would cure in a few minutes at 120 °C, while exhibiting acceptable pot life, viscosity profiles, and low water absorption. Moreover, this system yielded high T g parts with mechanical properties similar to the amine-epoxy systems, which are the mainstream two-component epoxy resin systems for automobiles.

A One-Component, Fast-Cure, and Economical Epoxy Resin System Suitable for Liquid Molding of Automotive Composite Parts

PubMed Central

Wang, Yiru; Qiu, Yiping; Wei, Yi

2018-01-01

Imidazole cured epoxy resin systems were evaluated for one-component, fast-curing resins for liquid molding of automotive composite parts according to industry requirements. It was demonstrated that an epoxy resin-1-(cyanoethyl)-2-ethyl-4-methylimidazol(EP-1C2E4MIM) system would cure in a few minutes at 120 °C, while exhibiting acceptable pot life, viscosity profiles, and low water absorption. Moreover, this system yielded high Tg parts with mechanical properties similar to the amine-epoxy systems, which are the mainstream two-component epoxy resin systems for automobiles. PMID:29702575

Metal and alloy nanoparticles by amine-borane reduction of metal salts by solid-phase synthesis: atom economy and green process.

PubMed

Sanyal, Udishnu; Jagirdar, Balaji R

2012-12-03

A new solid state synthetic route has been developed toward metal and bimetallic alloy nanoparticles from metal salts employing amine-boranes as the reducing agent. During the reduction, amine-borane plays a dual role: acts as a reducing agent and reduces the metal salts to their elemental form and simultaneously generates a stabilizing agent in situ which controls the growth of the particles and stabilizes them in the nanosize regime. Employing different amine-boranes with differing reducing ability (ammonia borane (AB), dimethylamine borane (DMAB), and triethylamine borane (TMAB)) was found to have a profound effect on the particle size and the size distribution. Usage of AB as the reducing agent provided the smallest possible size with best size distribution. Employment of TMAB also afforded similar results; however, when DMAB was used as the reducing agent it resulted in larger sized nanoparticles that are polydisperse too. In the AB mediated reduction, BNH(x) polymer generated in situ acts as a capping agent whereas, the complexing amine of the other amine-boranes (DMAB and TMAB) play the same role. Employing the solid state route described herein, monometallic Au, Ag, Cu, Pd, and Ir and bimetallic CuAg and CuAu alloy nanoparticles of <10 nm were successfully prepared. Nucleation and growth processes that control the size and the size distribution of the resulting nanoparticles have been elucidated in these systems.

Fast Curing of Composite Wood Products

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

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 compositesmore » 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 alternative approach to accelerated PF curing can be accomplished with the addition amines or amides. The later functionality undergoes base catalyzed hydrolysis yielding the corresponding carboxyl ate and free amine which rapidly reacts with the phenolic methylol groups facilitating polymerization and curing of the PF resin (Pizzi, 1997).« less

Room Temperature Curing Polymers

DTIC Science & Technology

1977-05-01

diglycidyl esters are low melting solids, they are easily purified by recrystallization . Both diglycidyl adipate and sebacate were prepared in 88...aromatic amine Shell Z (a eutectic mixture of methylene dianiline and m-phenylene- diamine). The Shell Z cured resins had apparent Tg’s near...cooled to 0oC. The white crystals which formed were recrystallized three times from methanol-water (9:1) to yield 248 g (88%) EEW = 125 (Theory 115

Greensilica® vectors for smart textiles.

PubMed

Matos, Joana C; Avelar, Inês; Martins, M Bárbara F; Gonçalves, M Clara

2017-01-20

The present work aims developing a versatile Greensilica ® vector/carrier, able to bind to a wide range of textile matrices of carbohydrate polymers and susceptible of being loaded with chemicals/drugs/therapeutic molecules, to create a green tailor-made (multi)functional high-tech textile. A green, eco-friendly, ammonia-free, easily scalable, time-saving sol-gel process was established for the production of those silica-based colloidal particles (SiO 2 , amine-SiO 2 , diamine-SiO 2 , and epoxy-SiO 2 ). Two different textile matrices (cotton, polyester) were functionalized, through the impregnation of Greensilica® particles. The impregnation was performed with and without cure. Diamine-SiO 2 colloidal particles exhibited the higher bonding efficiency in cured textile matrices (both cotton and polyester), while with no cure the best adherence to cotton and polyester textile matrices was achieved with diamine-SiO 2 and amine-SiO 2 , respectively. Use once and throw away and continued use applications were envisaged and screened through washing tests. The efficiency of the textiles impregnation was confirmed by SEM, and quantified by ICP. Copyright © 2016 Elsevier Ltd. All rights reserved.

Self-curing concrete with different self-curing agents

NASA Astrophysics Data System (ADS)

Gopala krishna sastry, K. V. S.; manoj kumar, Putturu

2018-03-01

Concrete is recognised as a versatile construction material globally. Properties of concrete depend upon, to a greater extent, the hydration of cement and microstructure of hydrated cement. Congenial atmosphere would aid the hydration of cement and hence curing of concrete becomes essential, till a major portion of the hydration process is completed. But in areas of water inadequacy and concreting works at considerable heights, curing is problematic. Self-Curing or Internal Curing technique overcomes these problems. It supplies redundant moisture, for more than sufficient hydration of cement and diminish self-desiccation. Self-Curing agents substantially help in the conservation of water in concrete, by bringing down the evaporation during the hydration of Concrete. The present study focuses on the impact of self-curing agents such as Poly Ethylene Glycol (PEG), Poly Vinyl Alcohol (PVA) and Super Absorbent Polymer (SAP) on the concrete mix of M25 grade (reference mix). The effect of these agents on strength properties of Concrete such as compressive strength, split tensile strength and flexural strength was observed on a comparative basis which revealed that PEG 4000 was the most effective among all the agents.

Synthesis and antibacterial activity of Schiff bases and amines derived from alkyl 2-(2-formyl-4-nitrophenoxy)alkanoates.

PubMed

Goszczyńska, Agata; Kwiecień, Halina; Fijałkowski, Karol

A series of novel Schiff bases and secondary amines were obtained in good yields, as a result of the reductive amination of alkyl 2-(2-formyl-4-nitrophenoxy)alkanoates with both aniline and 4-methoxyaniline under established mild reaction conditions. Sodium triacetoxyborohydride as well as hydrogen in the presence of palladium on carbon were used as efficient reducing agents of the Schiff bases, in both direct and stepwise reductive amination processes. The Schiff bases, amines, and amine hydrochlorides were designed as potential antibacterial agents, and structure-activity relationship could be established following in vitro assays against Gram-positive and Gram-negative bacteria. The minimal inhibitory concentration and zone of inhibition were also determined. In these tests, some of Schiff bases and secondary amine hydrochlorides showed moderate-to-good activity against Gram-positive bacteria, including S. aureus , M. luteus , and S. mutans .

Effect of Monomer Structure on Curing Behavior, CO2 Solubility, and Gas Permeability of Ionic Liquid-Based Epoxy-Amine Resins and Ion-Gels

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

McDanel, WM; Cowan, MG; Barton, JA

2015-04-29

New imidazolium- and pyrrolidinium-based bis(epoxide)-functionalized ionic liquid (IL) monorners were synthesized: and reacted with multifunctional amine monomers to produce cross-linked, epoxy-amine poly(ionic liquid) (PIL) resins and PIL/IL ion-gel membranes. The length and chemical nature (i.e., alkyl versus ether) between the irrildazolium group and epokitie groups were studied to determine their effects on CO2 affinity. The CO2 uptake (millimoles per gram) of the epoxy amine resins (between 0.1 and 1 mmol/g) was found to depend predominately on the epoxide-to-amine ratio and the bis(epoxide) IL molecular weight. The effect of using a primary versus a secondary amine-containing multifunctional monoiner was also assessedmore » for the resin-synthesis. Secondary amines can increase CO2 permeability but also increase the iime required for biS(epoxide) coriversion. When either the epoxide or athine monomer structure is changed, the CO2 solubility and permeability of the resulting PIL resins and ion-sel membranes can be tuned.« less

Epoxy Grout With Silica Thickener

NASA Technical Reports Server (NTRS)

Mcclung, C. E.

1984-01-01

Grout cures quickly, even in presence of hydraulic oil. Grout is mixture of aggregate particles, finely-divided silica, epoxy resin, and triethylenetetramine curing agent, with mixture containing about 85 percent silica and aggregate particle sand 15 percent resin and curing agent. Silica is thickening agent and keeps grout from sagging.

Phosphorus Moieties Make Polymers Less Flammable

NASA Technical Reports Server (NTRS)

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

1992-01-01

Phosphorus incorporated into epoxies and polyamides via curing agent. According to report, use of 1-(di(2-chloroethoxyphosphinyl)methyl)-2,4- and -2,6-diaminobenzene (DCEPD) as curing agent for epoxies and polyamides makes these polymers more fire-retardant than corresponding polymers made with standard curing agents not containing phosphorus.

Nonthrombogenic Hydrogel Coatings with Carbene-Cross-Linking Bioadhesives.

PubMed

Nanda, Himansu Sekhar; Shah, Ankur Harish; Wicaksono, Gautama; Pokholenko, Oleksandr; Gao, Feng; Djordjevic, Ivan; Steele, Terry W J

2018-05-14

Bioadhesives are a current unmet clinical need for mending of blood contacting soft tissues without inducing thrombosis. Recent development of carbene precursor bioadhesives with the advantages of on-demand curing, tuneable modulus, and wet adhesion have been synthesized by grafting diazirine onto poly (amidoamine) (PAMAM-G5) dendrimers. Herein, the structure activity relationships of platelet adhesion and activation is evaluated for the first time on the cured PAMAM-g-diazirine bioadhesives. Three strategies were employed to prevent healthy human donor platelets from adhering and activating on light-cured bioadhesive surfaces: (1) Attenuation of cationic surface charge, (2) antifouling composites by incorporating heparin and alginate in uncured formulation, and (3) heparin wash of cured bioadhesive surface. Topographical imaging of cured and ethanol dehydrated bioadhesive surfaces was used to quantify the adhered and activated platelets with scanning electron microscopy, whose resolution allowed identification of round senescent, short dendritic, and long dendritic platelets. Cured surfaces of PAMAM-g-diazirine (15%) had 10300 ± 500 adhered platelets mm -2 with 99.7% activation into short/long dendritic cells. Reduction of primary amines by higher degree of diazirine grafting or capping of free amines by acetylation reduces platelet adherence (2400 ± 200 vs 3000 ± 300, respectively). Physical incorporation of heparin and alginate in the formulations reduced the activated platelet; 1300 ± 300 and 300 ± 50, activated platelets mm -2 , in comparison with additive free adhesive formulation. Similarly, heparin rinse of the surface of additive free bioadhesive reduced the activated platelet to platelets of heparin composites at 600 ± 100 platelets mm -2 . PAMAM-g-diazirine (15%) bioadhesive retained the photocured mechanical properties and lap shear adhesion despite the addition of heparin and alginate additives.

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

Walker, J.M.

The physical properties: mechanical, electrical, and thermal of a general purpose epoxy potting compound, filled with either glass microspheres, aluminum oxide or beta-eucryptite and catalyzed with either an aliphatic amine, a liquid aromatic amine eutectic blend, or a liquid anhydride are discussed. The properties of a CTBN modified epoxy are also included. Twelve formulation-cure cycle combinations were chosen for evaluation. The temperature dependent properties from -65/sup 0/ to 400/sup 0/F (-54/sup 0/ to 204/sup 0/C) for the 12 combinations are given.

Phenylethynyl amine

NASA Technical Reports Server (NTRS)

Hergenrother, Paul M. (Inventor); Bryant, Robert G. (Inventor); Jensen, Brian J. (Inventor); Havens, Stephen J. (Inventor)

1997-01-01

Four phenylethynyl amine compounds--3 and 4-aminophenoxy-4'-phenylethynylbenzophenone, and 3 and 4-amino-4'-phenylethynylbenzophenone--were readily prepared and were used to endcap imide oligomers. Phenylethynyl-terminated amide acid oligomers and phenylethynyl-terminated imide oligomers with various molecular weights and compositions were prepared and characterized. These oligomers were cured at 300.degree. C. to 400.degree. C. to provide crosslinked polyimides with excellent solvent resistance, high strength and modulus and good high temperature properties. Adhesive panels, composites, films and moldings from these phenylethynyl terminated imide oligomers gave excellent mechanical performance.

Aging Effects of Environmentally-Friendly Cleaners on Adhesive Bond Integrity

NASA Technical Reports Server (NTRS)

Biegert, L. L.; Anderson, G. L.; Evans, K. B.; Olsen, B. D.; Weber, B. L.; McCool, A. A. (Technical Monitor)

2000-01-01

Because of the 1990 Clean Air Act Amendment many chlorinated solvents are being phased out of use in manufacturing industries. Replacement of the ODC (ozone- depleting chemicals) with less volatile, non-ozone depleting cleaners has been extensively studied over the past nine years at Thiokol Propulsion, Cordant Technologies. Many of the non-ODC cleaners contain compounds that can potentially degrade over time under conditions of high temperature, humidity and exposure to light. The chemical composition of environmentally conditioned cleaners and the subsequent effect on aluminum/amine-cured epoxy bond integrity as measured by Tapered Double Cantilever Beam were evaluated. From this study it is observed that moisture content increases for those cleaners containing polar compounds. Non-volatile residue content increases as stabilizers are depleted and the chemical compound limonene is oxidized. A change in aluminum/ amine-cured epoxy bond fracture toughness is observed as some of these cleaners age with increases in moisture and NVR content.

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

Zia-ul-Mustafa, M., E-mail: engr.ziamustafa@gmail.com; Ahmad, Faiz; Megat-Yusoff, Puteri S. M.

In this study, intumescent fire retardant coatings (IFRC) were developed to investigate the synergistic effects of reinforced mica and wollastonite fillers based IFRC towards heat shielding, char expansion, char composition and char morphology. Ammonium poly-phosphate (APP) was used as acid source, expandable graphite (EG) as carbon source, melamine as blowing agent, boric acid as additive and Hardener H-2310 polyamide amine in bisphenol A epoxy resin BE-188(BPA) was used as curing agent. Bunsen burner fire test was used for thermal performance according to UL-94 for 1 h. Field Emission Scanning Electron Microscopy (FESEM) was used to observe char microstructure. X-Ray Diffraction (XRD)more » and Fourier transform infrared spectroscopy (FTIR) were used to analyse char composition. The results showed that addition of clay filler in IFRC enhanced the fire protection performance of intumescent coating. X-Ray Diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) results showed the presence of boron phosphate, silicon phosphate oxide, aluminium borate in the char that improved the thermal performance of intumescent fire retardant coating (IFRC). Resultantly, the presence of these developed compounds enhanced the Integrity of structural steel upto 500°C.« less

Evaluation of an Interdigitated Gate Electrode Field-Effect Transistor (IGEFET) for In Situ Resin Cure Monitoring

DTIC Science & Technology

1991-12-01

School of Engineering, Air Force Institute of Technology, Wright-Patterson AFB OH, October 1988. 8. Billmeyer, Fred W., Jr. Textbook of Polymer Science...448-453 (April 1989). 10. Sheppard, Norman Fred , Jr. Dielectric Analysis of the Cure of Thermosetting Epoxy/Amine Systems. PhD Dissertation...Viscosity and Chemical Changes During Polymerization," American Chemical Society Symposium Series on Photophysics of Polymers, edited by C. E. Hoyle and J. M

Photopolymerization of N,N-dimethylaminobenzyl alcohol as amine co-initiator for light-cured dental resins.

PubMed

Schroeder, Walter F; Cook, Wayne D; Vallo, Claudia I

2008-05-01

The present study was carried out in order to assess the suitability of N,N-dimethylaminobenzyl alcohol (DMOH) as co-initiator of camphorquinone (CQ) and 1-phenyl-1,2-propanedione (PPD) in light-cured dental resins. DMOH was synthesized and used as co-initiator for the photopolymerization of a model resin based on {2,2-bis[4-(2-hydroxy-3-methacryloxyprop-1-oxy)phenyl]propane} (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA). Experimental formulations containing CQ or PPD in combination with DMOH at different concentrations were studied. The photopolymerization was carried out by means of a commercial light-emitting diode (LED) curing unit. The evolution of double bonds consumption versus irradiation time was followed by near-infrared spectroscopy (NIR). The photon absorption efficiency (PAE) of the photopolymerization process was calculated from the spectral distribution of the LED unit and the molar absorption coefficient distributions of PPD and CQ. DMOH is an efficient photoreducer of CQ and PPD resulting in higher polymerization rate and higher double bond conversion compared with dimethylaminoethylmethacrylate. The PAE for PPD was higher than that for CQ. However, the polymerization initiated by PPD progressed at a lower rate and exhibited lower values of final conversion compared with the resins containing CQ. This observation indicates that the lower polymerization rate of the PPD/amine system should be explained in terms of the mechanism of generating primary radicals by PPD, which is less efficient compared with CQ. The DMOH/benzoyl peroxide redox system, has recently been proposed as a more biocompatible accelerator for the polymerization of bone cements based on poly(methyl methacrylate), because cytotoxity tests have demonstrated that DMOH possesses better biocompatibility properties compared with traditional tertiary amines. The results obtained in the present study reveal the suitability of the CQ/DMOH initiator system for the polymerization of light-cured dental composites.

Reductive amination of tertiary anilines and aldehydes.

PubMed

Lv, Yunhe; Zheng, Yiying; Li, Yan; Xiong, Tao; Zhang, Jingping; Liu, Qun; Zhang, Qian

2013-10-09

An unprecedented oxidant-mediated reductive amination of tertiary anilines and aldehydes without external reducing agents was developed via the nucleophilic attack of the oxygen atom of the carbonyl group to in situ generated iminium ions, in which tertiary anilines were used as both nitrogen source and reducing agent for the first time.

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.

Nature of the Elimination of the Penicillinase Plasmid from Staphylococcus aureus by Surface-Active Agents

PubMed Central

Sonstein, Stephen A.; Baldwin, J. N.

1972-01-01

Growth of Stapylococcus aureus in various ionic surface-active agents resulted in loss of the ability to produce penicillinase, whereas growth in nonionic surface-active agents had no effect on penicillinase production. The curing effect of various alkyl sulfates was found to be dependent upon the chain length. Curing by surface-active agents could be inhibited by magnesium. Reciprocal transduction experiments showed that curing by a surface-active agent was a property of the plasmid, not of the bacterial strain in which the plasmic resides. PMID:4204903

Formation of N-alkylpyrroles via intermolecular redox amination.

PubMed

Pahadi, Nirmal K; Paley, Miranda; Jana, Ranjan; Waetzig, Shelli R; Tunge, Jon A

2009-11-25

A wide variety of aldehydes, ketones, and lactols undergo redox amination when allowed to react with 3-pyrroline in the presence of a mild Brønsted acid catalyst. This reaction utilizes the inherent reducing power of 3-pyrroline to perform the equivalent of a reductive amination to form alkyl pyrroles. In doing so, the reaction avoids stoichiometric reducing agents that are typically associated with reductive aminations. Moreover, the redox amination protocol allows access to alkyl pyrroles that cannot be made via standard reductive amination.

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.

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 researcher is able to elicit the molecular weight of the repeat unit and end group, which allows the determination of the polymer's structure. This technique can also determine the Mn and M w, as well as the PDI for each given polymer.

Role of Curing Agents in the Preservation of Shelf-stable Canned Meat Products1

PubMed Central

Duncan, Charles L.; Foster, E. M.

1968-01-01

Experiments were conducted to gain a better understanding of the mechanism by which sodium chloride, sodium nitrate, and sodium nitrite supplement the action of heat in preserving canned cured meat products. Heated spores of putrefactive anaerobe 3679h were less tolerant of all three curing agents in the outgrowth medium than were unheated spores. When the curing agents were added to the heating menstruum, but not to the outgrowth medium, sodium chloride and sodium nitrate tended to protect the spores against heat injury, but sodium nitrite did not. When the spores were both heated and cultured in the presence of the curing agents: (i) nitrate and salt increased the apparent heat resistance at low concentrations (0.5 to 1%) but decreased it at concentrations of 2 to 4%; (ii) nitrite was markedly inhibitory, especially at pH 6.0. At the normal pH of canned luncheon meats (approximately 6.0), nitrite appears to be the chief preservative agent against spoilage by putrefactive anaerobes. PMID:5645422

Adhesives and method for making the same

DOEpatents

Dorsey, George F.

1991-01-01

A thermosetting mixture for use as an adhesive, as well as other applications, that is substantially nonmutagenic. This mixture is based upon a thermosetting resin selected from polyurethane and epoxy resins, using an improved curing agent that does not contain mutagenic components. Specifically, the curing agent is a multi-mixture of substituted alkylanilines produced by an improved process. These alkylanilines are formed by condensation of at least two 2,6-dialkylanilines with a formaldehyde in an acid solution. Upon purification, at least three aromatic diamines are formed that are used for the curing agent with the polyurethane and epoxy resisn. Pot life, green strength and ultimate strength are comparable to adhesives of the prior art that contain mutagenic constituents. Although several dianilines are described, the preferred curing agents are formed using 2,6-diethylaniline (DEA) and 2,6-diisopropylaniline (DIPA), where the mole % of DEA and DIPA is 38-48 and 62-52, respectively. Curing agents within the preferred range have been designated as "Asilamine 4852" and "Asilamine 4555".

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.

Readily Available Chiral Benzimidazoles-Derived Guanidines as Organocatalysts in the Asymmetric α-Amination of 1,3-Dicarbonyl Compounds.

PubMed

Benavent, Llorenç; Puccetti, Francesco; Baeza, Alejandro; Gómez-Martínez, Melania

2017-08-11

The synthesis and the evaluation as organocatalysts of new chiral guanidines derived from benzimidazoles in the enantioselective α-amination of 1,3-dicarbonyl compounds using di- t -butylazodicarboxylate as aminating agent is herein disclosed. The catalysts are readily synthesized through the reaction of 2-chlorobezimidazole and a chiral amine in moderate-to-good yields. Among all of them, those derived from ( R )-1-phenylethan-1-amine ( 1 ) and ( S )-1-(2-naphthyl)ethan-1-amine ( 3 ) turned out to be the most efficient for such asymmetric transformation, rendering good-to-high yields and moderate-to-good enantioselectivities for the amination products.

Synergistic effects of mica and wollastonite fillers on thermal performance of intumescent fire retardant coating

NASA Astrophysics Data System (ADS)

Zia-ul-Mustafa, M.; Ahmad, Faiz; Megat-Yusoff, Puteri S. M.; Aziz, Hammad

2015-07-01

In this study, intumescent fire retardant coatings (IFRC) were developed to investigate the synergistic effects of reinforced mica and wollastonite fillers based IFRC towards heat shielding, char expansion, char composition and char morphology. Ammonium poly-phosphate (APP) was used as acid source, expandable graphite (EG) as carbon source, melamine as blowing agent, boric acid as additive and Hardener H-2310 polyamide amine in bisphenol A epoxy resin BE-188(BPA) was used as curing agent. Bunsen burner fire test was used for thermal performance according to UL-94 for 1 h. Field Emission Scanning Electron Microscopy (FESEM) was used to observe char microstructure. X-Ray Diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to analyse char composition. The results showed that addition of clay filler in IFRC enhanced the fire protection performance of intumescent coating. X-Ray Diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) results showed the presence of boron phosphate, silicon phosphate oxide, aluminium borate in the char that improved the thermal performance of intumescent fire retardant coating (IFRC). Resultantly, the presence of these developed compounds enhanced the Integrity of structural steel upto 500°C.

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.

Comparison of the Nanostructure and Mechanical Performance of Highly Exfoliated Epoxy-Clay Nanocomposites Prepared by Three Different Protocols

PubMed Central

Shiravand, Fatemeh; Hutchinson, John M.; Calventus, Yolanda; Ferrando, Francesc

2014-01-01

Three different protocols for the preparation of polymer layered silicate nanocomposites based upon a tri-functional epoxy resin, triglycidyl para-amino phenol (TGAP), have been compared in respect of the cure kinetics, the nanostructure and their mechanical properties. The three preparation procedures involve 2 wt% and 5 wt% of organically modified montmorillonite (MMT), and are: isothermal cure at selected temperatures; pre-conditioning of the resin-clay mixture before isothermal cure; incorporation of an initiator of cationic homopolymerisation, a boron tri-fluoride methyl amine complex, BF3·MEA, within the clay galleries. It was found that features of the cure kinetics and of the nanostructure correlate with the measured impact strength of the cured nanocomposites, which increases as the degree of exfoliation of the MMT is improved. The best protocol for toughening the TGAP/MMT nanocomposites is by the incorporation of 1 wt% BF3·MEA into the clay galleries of nanocomposites containing 2 wt% MMT. PMID:28788672

Comparison of the Nanostructure and Mechanical Performance of Highly Exfoliated Epoxy-Clay Nanocomposites Prepared by Three Different Protocols.

PubMed

Shiravand, Fatemeh; Hutchinson, John M; Calventus, Yolanda; Ferrando, Francesc

2014-05-30

Three different protocols for the preparation of polymer layered silicate nanocomposites based upon a tri-functional epoxy resin, triglycidyl para -amino phenol (TGAP), have been compared in respect of the cure kinetics, the nanostructure and their mechanical properties. The three preparation procedures involve 2 wt% and 5 wt% of organically modified montmorillonite (MMT), and are: isothermal cure at selected temperatures; pre-conditioning of the resin-clay mixture before isothermal cure; incorporation of an initiator of cationic homopolymerisation, a boron tri-fluoride methyl amine complex, BF₃·MEA, within the clay galleries. It was found that features of the cure kinetics and of the nanostructure correlate with the measured impact strength of the cured nanocomposites, which increases as the degree of exfoliation of the MMT is improved. The best protocol for toughening the TGAP/MMT nanocomposites is by the incorporation of 1 wt% BF₃·MEA into the clay galleries of nanocomposites containing 2 wt% MMT.

Shear Bond Strength of Resin Buttons to Lithium Disilicate and Leucite Reinforced Feldspathic Restorations

DTIC Science & Technology

2016-05-01

Hydrofluoric acid, silane coupling agent, light cured composite and ceramic restoration specimens (10 of each IPS e.max and Empress). The surface treatment...cured composite and ceramic restoration specimens (10 of each IPS e.max and Empress). The surface treatment in group C was applied to all specimens...and light cured for 20 seconds. 4) Group D: 5% Hydrofluoric acid, silane coupling agent, light cured composite and ceramic restoration (10 of

Metal and base free synthesis of primary amines via ipso amination of organoboronic acids mediated by [bis(trifluoroacetoxy)iodo]benzene (PIFA).

PubMed

Chatterjee, Nachiketa; Goswami, Avijit

2015-08-07

A metal and base free synthesis of primary amines has been developed at ambient temperature through ipso amination of diversely functionalized organoboronic acids, employing a combination of [bis(trifluoroacetoxy)iodo]benzene (PIFA)-N-bromosuccinimide (NBS) and methoxyamine hydrochloride as the aminating reagent. The amines were primarily obtained as their trifluoroacetate salts which on subsequent aqueous alkaline work up provided the corresponding free amines. The combination of PIFA-NBS is found to be the mildest choice compared to the commonly used strong bases (e.g. n-BuLi, Cs2CO3) for activating the aminating agent. The reaction is expected to proceed via activation of the aminating reagent followed by B-N 1,2-aryl migration.

Hypolipidemic, anti-obesity, anti-inflammatory, anti-osteoporotic, and anti-neoplastic properties of amine carboxyboranes.

PubMed Central

Hall, I H; Chen, S Y; Rajendran, K G; Sood, A; Spielvogel, B F; Shih, J

1994-01-01

The amine-carboxyborane derivatives were shown to be effective antineoplastic/cytotoxic agents with selective activity against single-cell and solid tumors derived from murine and human leukemias, lymphomas, sarcomas, and carcinomas. The agents inhibited DNA and RNA synthesis in preference to protein synthesis in L1210 lymphoid leukemia cells. Inosine-monophosphate dehydrogenase apparently is a target site of the compounds; similar effects on phosphoribosyl-pyrophosphate amido transferase, orotidine-monophosphate decarboxylase, and both nucleoside and nucleotide kinases were observed. Deoxyribonucleotide pool levels were reduced in the cells; DNA strand scission was observed with the agents. In rodents, the amine carboxyboranes were potent hypolipidemic agents, lowering both serum cholesterol and triglyceride concentrations, in addition to lowering cholesterol content of very low-density lipoprotein and low-density lipoprotein (LDL) and elevating high-density lipoprotein (HDL) cholesterol concentrations. De novo regulatory enzymes involved in lipid synthesis were also inhibited (e.g., hypocholesterolemic 3-hydroxy-3-methyl-Coenzyme A reductase, acyl-Coenzyme A cholesterol acyltransferase, and sn-glycerol-3-phosphate acyltransferase). Concurrently, the agents modulated LDL and HDL receptor binding, internalization, and degradation, so that less cholesterol was delivered to the plaques and more broken down from esters and conducted to the liver for biliary excretion. Tissue lipids in the aorta wall of the rat were reduced and fewer atherosclerotic morphologic lesions were present in quail aortas after treatment with the agents. Cholesterol resorption from the rat intestine was reduced in the presence of drug. Genetic hyperlipidemic mice demonstrated the same types of reduction after treatment with the agents. The agents would effectively lower lipids in tissue based on the inhibition of regulatory enzymes in pigs. These findings should help improve domestic meat supplies from fowl and pigs. The amine-carboxyboranes were effective anti-inflammatory agents against septic shock, induced edema, pleurisy, and chronic arthritis at 2.5 to 8 mg/kg. Lysosomal and proteolytic enzyme activities were also inhibited. More significantly, the agents were dual inhibitors of prostaglandin cyclooxygenase and 5'-lipoxygenase activities. These compounds also affected cytokine release and white cell migration. Subsequent studies showed that the amine-carboxyboranes were potent anti-osteoporotic agents reducing calcium resorption as well as increasing calcium and proline incorporation into mouse pup calvaria and rat UMR-106 collagen. PMID:7889876

The synthesis and dynamics research of new curing agent for epoxy resin

NASA Astrophysics Data System (ADS)

Peng, Yongli; Huang, Hengyu; Sun, Yong

2017-05-01

Two-step synthesis of trimellitic anhydride trimellitic anhydride n - butyl ester (TMNB) was introduced which could be used as an epoxy resin curing agent. The kinetics of the curing reaction was analyzed by N-order model and autocatalytic model. The curing kinetics parameters, the results show that the curing activation energy (Ea) of this system was 35.79kJ / mol. The kinetic equation of curing was d/a d t =2.1061 ×104e x p (-35.79/R T ) α0.5163(l-α ) 0.366 . Combined with β-1 / T extrapolation and experimental adjustment to obtain the resin system curing process: 75°C for 1h, 140°C for 3h, 160°C for 2h.

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.

1984-01-01

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.

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.

Stronger Fire-Resistant Epoxies

NASA Technical Reports Server (NTRS)

Fohlen, George M.; Parker, John A.; Kumar, Devendra

1988-01-01

New curing agent improves mechanical properties and works at lower temperature. Use of aminophenoxycyclotriphosphazene curing agents yields stronger, more heat- and fire-resistant epoxy resins. Used with solvent if necessary for coating fabrics or casting films.

Fluorometric determination of nitrite in cured meats.

PubMed

Coppola, E D; Wickroski, A F; Hanna, J G

1975-05-01

An indirect fluorometric method for determining sodium nitrite in meat products is presented. The extracted sodium nitrite is consumed in a diazotization reaction with a measured excess of sulfanilic acid. Fluorescamine, which acts selectively with primary amines such as sulfanilic acid, is a fluorogenic reagent for the excess amine. The amine consumed, calculated by difference from the total originally present, is directly related to the sodium nitrite content of the sample. Interferences from amino acids and soluble proteins in the meat extract are eliminated by judicious use of a secondary peak in the fluorescence spectra (436 nm excitation, 495 nm fluorescence) combined with measurement at low pH (3.30). The recoveries of sodium nitrite ranged from 83.2 to 99.6% with an average of 93.4 and a standard deviation of +/- 5.28% for 11 determinations.

Development of self-healing polymers via amine-epoxy chemistry: I. Properties of healing agent carriers and the modelling of a two-part self-healing system

NASA Astrophysics Data System (ADS)

Zhang, He; Yang, Jinglei

2014-06-01

Two types of healing agent carriers (microcapsules containing epoxy solution, referred to as EP-capsules, and etched hollow glass bubbles (HGBs) loaded with amine solution, referred to as AM-HGBs) used in self-healing epoxy systems were prepared and characterized in this study. The core percentages were measured at about 80 wt% and 33 wt% for EP-capsules and AM-HGBs, respectively. The loaded amine in AM-HGB, after incorporation into the epoxy matrix, showed high stability at ambient temperature, but diffused out gradually during heat treatment at 80 °C. The amount and the mass ratio of the two released healants at the crack plane were correlated with the size, concentration, and core percentage of the healing agent carriers. A simplified cubic array model for randomly distributed healing agent carriers was adopted to depict the longest diffusion distance of the released healants, which is inversely proportional to the cubic root of the carrier concentration.

Amine oxidases as important agents of pathological processes of rhabdomyolysis in rats.

PubMed

Gudkova, O O; Latyshko, N V; Shandrenko, S G

2016-01-01

In this study we have tested an idea on the important role of amine oxidases (semicarbazide-sensitive amine oxidase, diamine oxidase, polyamine oxidase) as an additional source of oxidative/carbonyl stress under glycerol-induced rhabdomyolysis, since the enhanced formation of reactive oxygen species and reactive carbonyl species in a variety of tissues is linked to various diseases. In our experiments we used the sensitive fluorescent method devised for estimation of amine oxidases activity in the rat kidney and thymus as targeted organs under rhabdomyolysis. We have found in vivo the multiple rises in activity of semicarbazide-sensitive amine oxidase, diamine oxidase, polyamine oxidase (2-4.5 times) in the corresponding cell fractions, whole cells or their lysates at the 3-6th day after glycerol injection. Aberrant antioxidant activities depended on rhabdomyolysis stage and had organ specificity. Additional treatment of animals with metal chelator ‘Unithiol’ adjusted only the activity of antioxidant enzymes but not amine oxidases in both organs. Furthermore the in vitro experiment showed that Fenton reaction (hydrogen peroxide in the presence of iron) products alone had no effect on semicarbazide-sensitive amine oxidase activity in rat liver cell fraction whereas supplementation with methylglyoxal resulted in its significant 2.5-fold enhancement. Combined action of the both agents had additive effect on semicarbazide-sensitive amine oxidase activity. We can assume that biogenic amine and polyamine catabolism by amine oxidases is upregulated by oxidative and carbonyl stress factors directly under rhabdomyolysis progression, and the increase in catabolic products concentration contributes to tissue damage in glycerol-induced acute renal failure and apoptosis stimulation in thymus.

Encapsulation Processing and Manufacturing Yield Analysis

NASA Technical Reports Server (NTRS)

Willis, P.

1985-01-01

Evaluation of the ethyl vinyl acetate (EVA) encapsulation system is presented. This work is part of the materials baseline needed to demonstrate a 30 year module lifetime capability. Process and compound variables are both being studied along with various module materials. Results have shown that EVA should be stored rolled up, and enclosed in a plastic bag to retard loss of peroxide curing agents. The TBEC curing agent has superior shelf life and processing than the earlier Lupersol-101 curing agent. Analytical methods were developed to test for peroxide content, and experimental methodologies were formalized.

Silane coupling agent bearing a photoremovable succinimidyl carbonate for patterning amines on glass and silicon surfaces with controlled surface densities.

PubMed

Nakayama, Hidekazu; Nakanishi, Jun; Shimizu, Takahiro; Yoshino, Yutaro; Iwai, Hideo; Kaneko, Shingo; Horiike, Yasuhiro; Yamaguchi, Kazuo

2010-03-01

Patterned immobilization of synthetic and biological ligands on material surfaces with controlled surface densities is important for various bioanalytical and cell biological purposes. This paper describes the synthesis, characterization, and application of a novel silane coupling agent bearing a photoremovable succinimidyl carbonate, which enables the photopatterning of various primary amines on glass and silicon surfaces. The silane coupling agent is 1-[5-methoxy-2-nitro-4-(3-trimethoxysilylpropyloxy)phenyl]ethyl N-succinimidyl carbonate. The distinct feature of this molecule is that it has a photocleavable 2-nitrobenzyl switch between a trimethoxysilyl group and a succinimidyl carbonate, each reactive to the hydroxy groups of inorganic oxides and primary amines. Based on this molecular design, the compound allows for the one-step introduction of succinimidyl carbonates onto the surface of glass and silicon, immobilization of primary amines, and region-selective and dose-dependent release of the amines by near-UV irradiation. Therefore, we were able to pattern amine ligands on the substrates in given surface densities and arbitrary geometries by controlling the doses and regions of photoirradiation. These features were verified by UV-vis spectroscopy, contact angle measurements, infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), ellipsometry, and atomic force microscopy (AFM). The compound was applied to form a chemical density gradient of amino-biotin on a silicon substrate in a range of 0.87-0.12 chains/nm(2) by controlling photoirradiation under a standard fluorescence microscope. Furthermore, we also succeeded in forming a chemical density gradient at a lower surface density range (0.15-0.011 chains/nm(2)) on the substrate by diluting the feed amino-biotin with an inert control amine.

77 FR 48976 - Certain New Chemicals; Receipt and Status Information

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-15

... surface active agent. fluorinated alcohol, reaction products with phosphorus oxide (P205), amine salts. P.... fluorinated alcohol, reaction products with phosphorus oxide (P205), amine salts. P-12-0452...... 07/09/2012...

Phthalocyanine Tetraamine Epoxy-Curing Agents

NASA Technical Reports Server (NTRS)

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

1986-01-01

Tough fire- and chemical-resistant epoxies produced by using metalphthalocyanine tetraamines (MPT's) of copper, cobalt, or nickel as curing agents. Synthesis of MPT's commercially realizable and gives pure compounds with almost 90-percent yield. Synthesis applicable for metals with atomic radii of about 1.35 angstroms, including Cu, Co, Ni, Zn, Fe, Pt, Al, and V. Possible to use metal phthalocyanines to cure epoxy resins in homogeneous reaction.

Influence of putrescine, cadaverine, spermidine or spermine on the formation of N-nitrosamine in heated cured pork meat.

PubMed

Drabik-Markiewicz, G; Dejaegher, B; De Mey, E; Kowalska, T; Paelinck, H; Vander Heyden, Y

2011-06-15

The influence of biogenic amines (i.e. putrescine, cadaverine, spermidine and spermine) on the N-nitrosamine formation in heated cured lean meat was studied in the presence or absence of sodium nitrite and at different meat processing temperatures. Experimental evidence was produced using gas chromatography with thermal energy analysis detection (GC-TEA). Concentration of N-nitrosamines was modelled as a function of the temperature and the nitrite concentration for two situations, i.e. presence or absence of added biogenic amines to the meat. The significance of the influence of the changing parameters was evaluated by ANOVA (Analysis of Variance). It was found that higher processing temperatures and higher added amounts of sodium nitrite increase the yields of N-nitrosodimethylamine (NDMA) and N-nitrosopiperidine (NPIP). Spermidine and putrescine amplify the formation of NDMA, but spermine and cadeverine do not influence the formation of this N-nitrosamine. Spermidine and cadeverine cause a significant increase of NPIP. Beside N-nitrosopyrrolidine (NPYR) in some rare cases, no other volatile N-nitrosamines are detected. Copyright © 2010 Elsevier Ltd. All rights reserved.

Susceptibility of dry-cured tuna to oxidative deterioration and biogenic amines generation: I. Effect of NaCl content, antioxidant type and ageing.

PubMed

Roseiro, L C; Santos, C; Gonçalves, H; Serrano, C; Aleixo, C; Partidário, A; Lourenço, A R; Dias, M Abreu; da Ponte, D J B

2017-08-01

This study aimed to assess lipid oxidation and biogenic amine (BA) development in "muxama", a dry-cured tuna muscle product, as affected by salt content, antioxidant type and ageing time. Overall, BA contents decreased with NaCl level (2785.1mgkg -1 , 1148.1mgkg -1 and 307.7mgkg -1 ) and increased with ageing time (366.2mgkg -1 , 1711.8mgkg -1 and 2959.2mgkg -1 in the final product (T0), and after 1 (T1) and 3 (T3) months of ageing, respectively). Regardless of the test conditions, the most concentrated BA was always tyramine. For the ageing periods considered in the present study, malondialdehyde formation was affected by the NaCl level, with the saltiest samples exhibiting lower content. Rosemary and sage extracts represented promising technological options for preserving muxama from oxidation and to minimize the presence of a fishy flavour and odour, but this treatment may cause the colour to lose some of its redness and become less appealing. Copyright © 2017 Elsevier Ltd. All rights reserved.

Activation of water soluble amines by halogens for trapping methyl radioactive iodine from air streams

DOEpatents

Deitz, Victor R.; Blachly, Charles H.

1977-01-01

Gas adsorbent charcoals impregnated with an aqueous solution of the reaction product of a tertiary amine and elemental iodine or bromine are better than 99 per cent efficient in trapping methyl iodine.sup.131. The chemical addition of iodine or bromine to the tertiary amine molecule increases the efficiency of the impregnated charcoal as a trapping agent, and in conjunction with the high flash point of the tertiary amine raises the ignition temperature of the impregnated charcoal.

Method of making thermally removable adhesives

DOEpatents

Aubert, James H.

2004-11-30

A method of making a thermally-removable adhesive is provided where a bismaleimide compound, a monomeric furan compound, containing an oxirane group an amine curative are mixed together at an elevated temperature of greater than approximately 90.degree. C. to form a homogeneous solution, which, when cooled to less than approximately 70.degree. C., simultaneously initiates a Diels-Alder reaction between the furan and the bismaleimide and a epoxy curing reaction between the amine curative and the oxirane group to form a thermally-removable adhesive. Subsequent heating to a temperature greater than approximately 100.degree. C. causes the adhesive to melt and allows separation of adhered pieces.

Predicting the Macroscopic Fracture Energy of Epoxy Resins from Atomistic Molecular Simulations

DOE PAGES

Meng, Zhaoxu; Bessa, Miguel A.; Xia, Wenjie; ...

2016-12-06

Predicting the macroscopic fracture energy of highly crosslinked glassy polymers from atomistic simulations is challenging due to the size of the process zone being large in these systems. Here, we present a scale-bridging approach that links atomistic molecular dynamics simulations to macroscopic fracture properties on the basis of a continuum fracture mechanics model for two different epoxy materials. Our approach reveals that the fracture energy of epoxy resins strongly depends on the functionality of epoxy resin and the component ratio between the curing agent (amine) and epoxide. The most intriguing part of our study is that we demonstrate that themore » fracture energy exhibits a maximum value within the range of conversion degrees considered (from 65% to 95%), which can be attributed to the combined effects of structural rigidity and post-yield deformability. Our study provides physical insight into the molecular mechanisms that govern the fracture characteristics of epoxy resins and demonstrates the success of utilizing atomistic molecular simulations towards predicting macroscopic material properties.« less

Predicting the Macroscopic Fracture Energy of Epoxy Resins from Atomistic Molecular Simulations

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

Meng, Zhaoxu; Bessa, Miguel A.; Xia, Wenjie

Predicting the macroscopic fracture energy of highly crosslinked glassy polymers from atomistic simulations is challenging due to the size of the process zone being large in these systems. Here, we present a scale-bridging approach that links atomistic molecular dynamics simulations to macroscopic fracture properties on the basis of a continuum fracture mechanics model for two different epoxy materials. Our approach reveals that the fracture energy of epoxy resins strongly depends on the functionality of epoxy resin and the component ratio between the curing agent (amine) and epoxide. The most intriguing part of our study is that we demonstrate that themore » fracture energy exhibits a maximum value within the range of conversion degrees considered (from 65% to 95%), which can be attributed to the combined effects of structural rigidity and post-yield deformability. Our study provides physical insight into the molecular mechanisms that govern the fracture characteristics of epoxy resins and demonstrates the success of utilizing atomistic molecular simulations towards predicting macroscopic material properties.« less

Mussel-inspired hyperbranched poly(amino ester) polymer as strong wet tissue adhesive.

PubMed

Zhang, Hong; Bré, Lígia P; Zhao, Tianyu; Zheng, Yu; Newland, Ben; Wang, Wenxin

2014-01-01

Current medical adhesives based on cyanoacrylates typically exhibit cellular toxicity. In contrast, fibrin adhesives are non-toxic but have poor adhesive properties. To overcome these drawbacks we designed a simple and scalable adhesive precursor inspired by marine mussel adhesion that functioned with strong adhesion in wet conditions and with low cytotoxicity. Dopamine, an-amine derivative of an amino acid abundantly present in mussel adhesive proteins, was co-polymerised with a tri-functional vinyl monomer, to form a hyperbranched poly(β-amino ester) polymer termed poly(dopamine-co-acrylate) (PDA). A variety of molecular weights and crosslinking methods were analysed using an ex vivo porcine skin model and an almost 4 fold increase in wet adhesion strength was observed compared to TISSEEL(®) fibrin sealant. With a fast curing time, degradable properties and low cytotoxicity, PDA is highly attractive for medical purposes and could have a broad impact on surgeries where surgical tissue adhesives, sealants, and haemostatic agents are used. Copyright © 2013 Elsevier Ltd. All rights reserved.

Kinetic studies of chemical shrinkage and residual stress formation in thermoset epoxy adhesives under confined curing conditions

NASA Astrophysics Data System (ADS)

Schumann, M.; Geiß, P. L.

2015-05-01

Faultless processing of thermoset polymers in demanding applications requires a profound mastering of the curing kinetics considering both the physico-chemical changes in the transition from the liquid to the solid state and the consolidation of the polymers network in the diffusion controlled curing regime past the gel point. Especially in adhesive joints shrinkage stress occurring at an early state of the curing process under confined conditions is likely to cause defects due to local debonding and thus reduce their strength and durability1. Rheometry is considered the method of choice to investigate the change of elastic and viscous properties in the progress of curing. Drawbacks however relate to experimental challenges in accessing the full range of kinetic parameters of thermoset resins with low initial viscosity from the very beginning of the curing reaction to the post-cure consolidation of the polymer due to the formation of secondary chemical bonds. Therefore the scope of this study was to interrelate rheological data with results from in-situ measurements of the shrinkage stress formation in adhesive joints and with the change of refractive index in the progress of curing. This combination of different methods has shown to be valuable in gaining advanced insight into the kinetics of the curing reaction. The experimental results are based on a multi component thermoset epoxy-amine adhesive.

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.

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.

Polymer Claw: Instant Underwater Adhesive

DTIC Science & Technology

2012-03-23

technology is the use of pressure sensitive microcapsules , which release reactive amine crosslinkers into an adhesive putty when pressed against the...PROIECT GOALS AND OBIECTIVES 2 2 KEY ACCOMPLISHMENTS 2 3.1 KICKOFF MEETING 3 3.2 AMINE MICROENCAPSULATION 3 3.3 CAUSTIC CLEANING AGENT 5 3.4...caustic, and the abrasive brush. We successfully synthesized amine-filled microcapsules and a dry mixture of caustic ingredients that only activate when

Release of Self-Healing Agents in a Material: What Happens Next?

PubMed

Lee, Min Wook; Yoon, Sam S; Yarin, Alexander L

2017-05-24

A microfluidic chip-like setup consisting of a vascular system of microchannels alternatingly filled with either a resin monomer or a curing agent is used to study the intrinsic physical healing mechanism in self-healing materials. It is observed that, as a prenotched crack propagates across the chip, the resin and curing agent are released from the damaged channels. Subsequently, both the resin and the curing agent wet the surrounding polydimethylsiloxane (PDMS) matrix and spread over the crack banks until the two blobs come in contact, mix, and polymerize through an organometallic cross-linking reaction. Moreover, the polymerized domains form a system of pillars, which span the crack banks on the opposite side. This "stitching" phenomenon prevents further propagation of the crack.

Low Temperature Synthesis of CdSe Quantum Dots with Amine Derivative and Their Chemical Kinetics

NASA Astrophysics Data System (ADS)

Seongmi Hwang,; Youngmin Choi,; Sunho Jeong,; Hakyun Jung,; Chang Gyoun Kim,; Teak-Mo Chung,; Beyong-Hwan Ryu,

2010-05-01

The chemical kinetics of growing CdSe nanocrystals was studied in order to investigate the effects of amine capping agents on the size of resulting quantum dots (QDs). CdSe QDs were prepared in phenyl ether, and the amine ligand dependence of QD size was determined. The results show that the size of CdSe nanocrystals can be regulated by controlling reaction rate, with smaller QDs being formed in slower processes. The results of photoluminescence (PL) studies show that the emission wavelengths of the QDs well correlate with particle size. This simple process for forming different-sized QDs, which uses a cheap solvent and various capping agents, has the potential for preparing CdSe nanocrystals more economically.

Fiber-Reinforced Epoxy Composites and Methods of Making Same Without the Use of Oven or Autoclave

NASA Technical Reports Server (NTRS)

Barnell, Thomas J. (Inventor); Rauscher, Michael D. (Inventor); Stienecker, Rick D. (Inventor); Nickerson, David M. (Inventor); Tong, Tat H. (Inventor)

2016-01-01

Method embodiments for producing a fiber-reinforced epoxy composite comprise providing a mold defining a shape for a composite, applying a fiber reinforcement over the mold, covering the mold and fiber reinforcement thereon in a vacuum enclosure, performing a vacuum on the vacuum enclosure to produce a pressure gradient, insulating at least a portion of the vacuum enclosure with thermal insulation, infusing the fiber reinforcement with a reactive mixture of uncured epoxy resin and curing agent under vacuum conditions, wherein the reactive mixture of uncured epoxy resin and curing agent generates exothermic heat, and producing the fiber-reinforced epoxy composite having a glass transition temperature of at least about 100.degree. C. by curing the fiber reinforcement infused with the reactive mixture of uncured epoxy resin and curing agent by utilizing the exothermically generated heat, wherein the curing is conducted inside the thermally insulated vacuum enclosure without utilization of an external heat source or an external radiation source.

Comparing the shear bond strength of direct and indirect composite inlays in relation to different surface conditioning and curing techniques

PubMed Central

Zorba, Yahya Orcun; Ilday, Nurcan Ozakar; Bayındır, Yusuf Ziya; Demirbuga, Sezer

2013-01-01

Objective: The aim of this study was to test the null hypothesis that different surface conditioning (etch and rinse and self-etch) and curing techniques (light cure/dual cure) had no effect on the shear bond strength of direct and indirect composite inlays. Materials and Methods: A total of 112 extracted human molar teeth were horizontally sectioned and randomly divided into two groups according to restoration technique (direct and indirect restorations). Each group was further subdivided into seven subgroups (n = 8) according to bonding agent (etch and rinse adhesives Scotchbond multi-purpose plus, All-Bond 3, Adper Single Bond and Prime Bond NT; and self-etch adhesives Clearfil Liner Bond, Futurabond DC and G bond). Indirect composites were cemented to dentin surfaces using dual-curing luting cement. Shear bond strength of specimens was tested using a Universal Testing Machine. Two samples from each subgroup were evaluated under Scanning electron microscopy to see the failing modes. Data was analyzed using independent sample t-tests and Tukey's tests. Results: Surface conditioning and curing of bonding agents were all found to have significant effects on shear bond strength (P < 0.05) of both direct and indirect composite inlays. With direct restoration, etch and rinse systems and dual-cured bonding agents yielded higher bond strengths than indirect restoration, self-etch systems and light-cured bonding agents. Conclusions: The results of the present study indicated that direct restoration to be a more reliable method than indirect restoration. Although etch and rinse bonding systems showed higher shear bond strength to dentin than self-etch systems, both systems can be safely used for the adhesion of direct as well as indirect restorations. PMID:24932118

Comparing the shear bond strength of direct and indirect composite inlays in relation to different surface conditioning and curing techniques.

PubMed

Zorba, Yahya Orcun; Ilday, Nurcan Ozakar; Bayındır, Yusuf Ziya; Demirbuga, Sezer

2013-10-01

The aim of this study was to test the null hypothesis that different surface conditioning (etch and rinse and self-etch) and curing techniques (light cure/dual cure) had no effect on the shear bond strength of direct and indirect composite inlays. A total of 112 extracted human molar teeth were horizontally sectioned and randomly divided into two groups according to restoration technique (direct and indirect restorations). Each group was further subdivided into seven subgroups (n = 8) according to bonding agent (etch and rinse adhesives Scotchbond multi-purpose plus, All-Bond 3, Adper Single Bond and Prime Bond NT; and self-etch adhesives Clearfil Liner Bond, Futurabond DC and G bond). Indirect composites were cemented to dentin surfaces using dual-curing luting cement. Shear bond strength of specimens was tested using a Universal Testing Machine. Two samples from each subgroup were evaluated under Scanning electron microscopy to see the failing modes. Data was analyzed using independent sample t-tests and Tukey's tests. Surface conditioning and curing of bonding agents were all found to have significant effects on shear bond strength (P < 0.05) of both direct and indirect composite inlays. With direct restoration, etch and rinse systems and dual-cured bonding agents yielded higher bond strengths than indirect restoration, self-etch systems and light-cured bonding agents. The results of the present study indicated that direct restoration to be a more reliable method than indirect restoration. Although etch and rinse bonding systems showed higher shear bond strength to dentin than self-etch systems, both systems can be safely used for the adhesion of direct as well as indirect restorations.

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

NASA Technical Reports Server (NTRS)

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

1985-01-01

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

The vascular effects of trace amines and amphetamines.

PubMed

Broadley, Kenneth J

2010-03-01

Trace amines, including tyramine, beta-phenylethylamine (beta-PEA), tryptamine and octopamine, are biologically active amines mostly based on phenylethylamine, occurring in the body in trace amounts. They are a diverse group of naturally occurring and synthetic amines, which are also found in the diet and in herbal plants, such as ephedrine and cathinone. They include amphetamine and its analogues, such as MDMA ('ecstasy'), and synthetic proprietary sympathomimetic agents such as phenylpropanolamine and pseudoephedrine. On the vascular system they cause vasoconstriction and a rise in blood pressure. This effect is the basis of their use as nasal decongestants. For over 50 years, they have been assumed to be indirectly acting sympathomimetic amines, their responses being due to the release of noradrenaline from sympathetic neurones. There are, however, results that suggest that this is not their only mechanism of action and that they may also exert direct vascular effects independent of a noradrenergic mechanism. Recently, a group of novel trace amine-associated receptors (TAARs) have been cloned and identified in the brain and peripheral tissues including blood vessels. Trace amines bind to these cloned receptors and it is suggested that their vasoconstrictor effects can in part be attributed to this mechanism. This review describes the cardiovascular pharmacology of this diverse group of amines, their structures and uses and their endogenous synthesis and metabolism. The review also considers their clinical relevance as constituents of the diet, as therapeutic agents (ritodrine, phenylpropanolamine, and pseudoephedrine) and as drugs of abuse (amphetamine, 'ecstasy') and their mechanisms of action. 2009 Elsevier Inc. All rights reserved.

Chemical analysis of DC745 Materials: DEV Lot 1 reinvestigation; barcodes P053387, P053388, and P053389

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

Dirmyer, Matthew R.

This report serves as a follow up to our initial development lot 1 chemical analysis report (LA-UR-16-21970). The purpose of that report was to determine whether or not certain combinations of resin lots and curing agent lots resulted in chemical differences in the final material. One finding of that report suggested that pad P053389 was different from the three other pads analyzed. This report consists of chemical analysis of P053387, P053388, and a reinvestigation of P053389 all of which came from the potentially suspect combination of resin and curing agents lot. The goal of this report is to determine whethermore » the observations relating to P053389 were isolated to that particular pad or systemic to that combination of resin and curing agent lot. The following suite of analyses were performed on the pads: Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy (FT-IR), and Solid State Nuclear Magnetic Resonance (NMR). The overall conclusions of the study are that pads P053387 and P053388 behave more consistently with the pads of other resin lot and curing agent lot combinations and that the chemical observations made regarding pad P053389 are isolated to that pad and not representative of an issue with that resin lot and curing agent lot combination.« less

Novel aminobenzyl and imidobenzyl benzenes

NASA Technical Reports Server (NTRS)

Bell, V. L.; Pratt, J. R.; Stump, B. L.

1976-01-01

Compounds are useful as intermediates for several classes of polymers. Amines can function as cross-linking agents for epoxide and urethane polymers, as well as intermediates for synthesis of thermally-stable addition-type polyimides. Imide derivatives can be obtained by reacting amines with certain monoanhydrides containing olefinic unsaturation.

The sources, fate, and toxicity of chemical warfare agent degradation products.

PubMed Central

Munro, N B; Talmage, S S; Griffin, G D; Waters, L C; Watson, A P; King, J F; Hauschild, V

1999-01-01

We include in this review an assessment of the formation, environmental fate, and mammalian and ecotoxicity of CW agent degradation products relevant to environmental and occupational health. These parent CW agents include several vesicants: sulfur mustards [undistilled sulfur mustard (H), sulfur mustard (HD), and an HD/agent T mixture (HT)]; nitrogen mustards [ethylbis(2-chloroethyl)amine (HN1), methylbis(2-chloroethyl)amine (HN2), tris(2-chloroethyl)amine (HN3)], and Lewisite; four nerve agents (O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX), tabun (GA), sarin (GB), and soman (GD)); and the blood agent cyanogen chloride. The degradation processes considered here include hydrolysis, microbial degradation, oxidation, and photolysis. We also briefly address decontamination but not combustion processes. Because CW agents are generally not considered very persistent, certain degradation products of significant persistence, even those that are not particularly toxic, may indicate previous CW agent presence or that degradation has occurred. Of those products for which there are data on both environmental fate and toxicity, only a few are both environmentally persistent and highly toxic. Major degradation products estimated to be of significant persistence (weeks to years) include thiodiglycol for HD; Lewisite oxide for Lewisite; and ethyl methyl phosphonic acid, methyl phosphonic acid, and possibly S-(2-diisopropylaminoethyl) methylphosphonothioic acid (EA 2192) for VX. Methyl phosphonic acid is also the ultimate hydrolysis product of both GB and GD. The GB product, isopropyl methylphosphonic acid, and a closely related contaminant of GB, diisopropyl methylphosphonate, are also persistent. Of all of these compounds, only Lewisite oxide and EA 2192 possess high mammalian toxicity. Unlike other CW agents, sulfur mustard agents (e.g., HD) are somewhat persistent; therefore, sites or conditions involving potential HD contamination should include an evaluation of both the agent and thiodiglycol. Images Figure 1 Figure 3 Figure 5 PMID:10585900

Direct reductive amination of aldehyde bisulfite adducts induced by 2-picoline borane: application to the synthesis of a DPP-IV inhibitor.

PubMed

Faul, Margaret; Larsen, Rob; Levinson, Adam; Tedrow, Jason; Vounatsos, Filisaty

2013-02-15

Aldehyde-bisulfite adducts dervied from unstable parent aldehydes were reductively alkylated in a direct fashion with a variety of amines. This approach features the use of 2-picoline borane as the reducing agent and a protic solvent for the reaction media and has been successfully applied to the synthesis of a DPP-IV inhibitor and a variety of other amines.

Increasing Fire Safety of Epoxies

NASA Technical Reports Server (NTRS)

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

1985-01-01

Epoxy with increased resistance to fire made by reacting any of three commercial epoxide monomers with curing agent consisting of mixture of isomers called "DCEPD". Curing agent incorporates phosphorus and chlorine directly into crosslinking part of polymer. DCEPD produced by nitrating precursor phosphonylmethyl benzene, then reducing resulting isomeric mixture of dinitro compounds.

Short communication: pre- and co-curing effect of adhesives on shear bond strengths of composite resins to primary enamel and dentine: an in vitro study.

PubMed

Viswanathan, R; Shashibhushan, K K; Subba Reddy, V V

2011-12-01

To evaluate and compare shear bond strengths of composite resins to primary enamel and dentine when the adhesives are pre-cured (light cured before the application of the resin) or co-cured (adhesive and the resin light cured together). Buccal surfaces of 80 caries-free primary molars were wet ground to create bonding surfaces on enamel and dentine and specimens mounted on acrylic blocks. Two bonding agents (Prime and Bond NT® and Xeno III®) were applied to either enamel or dentine as per manufacturer's instructions. In 40 specimens, the bonding agent was light cured immediately after the application (pre-cured). The other 40 specimens were not light cured until the composite resin application (co-cured). Resin composite cylinders were made incrementally using acrylic moulds over the adhesives and light cured. Specimens were stored in deionised water for 24 hours at room temperature. Shear bond strength was measured using an Instron universal testing machine (in MPa) and was analysed with Student's unpaired t test. Light curing the adhesive separately produced significantly higher bond strengths to primary dentine than co-curing (p<0.001). At the same time light curing the adhesive separately did not produce significantly different bond strengths to primary enamel (p>0.05). Curing sequence had no significant effect on shear bond strength of adhesives on the primary enamel. Pre-curing adhesives before curing composite resins produced greater shear bond strength to primary dentine.

Exploration Of `Click' Chemistry For Microelectronic Applications

NASA Astrophysics Data System (ADS)

Musa, Osama M.; Sridhar, Laxmisha M.

The ‘Click’ chemistry was explored for low temperature snap cure and for possible use as an adhesion promoter in electronic applications. Several azide and alkyne resins were synthesized and their curing potential was evaluated with a special emphasis on exploring Cu(I) catalyst effect. The preliminary curing study in the absence of catalysts showed a strong dependence of cure temperatures on the electronic nature of alkynes. The cure temperatures showed a tendency to increase with decreasing electronegativity of the substituent on alkynes. The capability of Cu(I) catalysts to accelerate the ‘Click’ chemistry was demonstrated for the first time in bulk phase. Using several Cu(I) catalysts, the cure temperatures could be lowered by as much as 40-100°C compared to the control, depending on the nature of catalyst and the catalyst loading. We discovered a novel synergistic effect between Cu(I) and silver filler in lowering the cure temperatures. Using this combination, lower cure temperatures could be obtained than using either alone. Among several resins screened, one resin system has shown promise for 80°C snap-cure in which the aforementioned synergistic effect is operative. Solution phase ‘Click’ chemistry was employed for the synthesis of a hybrid triazole-epoxy resin system. This system was found to cure without added amine curative. The triazole group here serves as a linker as well as an internal adhesion promoter. To address the incompatibility and volatility issues, which arose during evaluation, a controlled oligomerization method has been developed using controlled heating of azides and alkynes in solution phase.

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

USDA-ARS?s Scientific Manuscript database

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

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

USDA-ARS?s Scientific Manuscript database

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

Simultaneous extraction and quantitation of several bioactive amines in cheese and chocolate.

PubMed

Baker, G B; Wong, J T; Coutts, R T; Pasutto, F M

1987-04-17

A method is described for simultaneous extraction and quantitation of the amines 2-phenylethylamine, tele-methylhistamine, histamine, tryptamine, m- and p-tyramine, 3-methoxytyramine, 5-hydroxytryptamine, cadaverine, putrescine, spermidine and spermine. This method is based on extractive derivatization of the amines with a perfluoroacylating agent, pentafluorobenzoyl chloride, under basic aqueous conditions. Analysis was done on a gas chromatograph equipped with an electron-capture detector and a capillary column system. The procedure is relatively rapid and provides derivatives with good chromatographic properties. Its application to analysis of the above amines in cheese and chocolate products is described.

Facile reductive amination of aldehydes with electron-deficient anilines by acyloxyborohydrides in TFA: application to a diazaindoline scale-up.

PubMed

Boros, Eric E; Thompson, James B; Katamreddy, Subba R; Carpenter, Andrew J

2009-05-01

A scale-up of diazaindoline 1 was achieved in four stages and 32% overall yield. The key step involved rapid reductive amination of aldehyde 8 with aniline 5 by sodium triacetoxyborohydride (STAB-H) and TFA followed by ring closure of intermediate amine 9 to compound 1 in the same pot. These reaction conditions were also applied to facile reductive aminations with anilines known to have little reactivity under STAB-H/AcOH conditions. Spectral data supported the tris(trifluoroacetoxy)borohydride anion (16) as the active reducing agent.

The Anti-Inflammatory Activity of Boron Derivatives in Rodents

PubMed Central

Hall, Iris H.; Burnham, Bruce S.; Chen, Shang Y.; Sood, Anup; Spielvogel, Bernard F.; Morse, Karen W.

1995-01-01

Acyclic amine-carboxyboranes were effective anti-inflammatory agents in mice at 8 mg/kg x 2. These amine-carboxyboranes were more effective than the standard indomethacin at 8 mg/kg x 2, pentoxifylline at 50 mg/kg x 2, and phenylbutazone at 50 mg/kg x 2. The heterocyclic amine derivatives as well as amine-carbamoylboranes, carboalkoxyboranes, and cyanoboranes were generally less active. However, selected aminomethyl-phosphonate-N-cyanoboranes demonstrated greater than 60% reduction of induced inflammation. The boron compounds were also active in the rat induced edema, chronic arthritis, and pleurisy screens, demonstrating activity similar to the standard indomethacin. The compounds were effecive in reducing local pain and decreased the tail flick reflex to pain. The derivatives which demonstrated good anti-inflammatory activity were effective inhibitors of hydrolytic lysosomal, and proteolytic enzyme activities with IC50 50 values equal to -6M in mouse macrophages, human leukocytes, and Be Sal osteofibrolytic cells. In these same cell lines, the agents blocked prostaglandin cyclooxygenase activity with IC50 values of -6M. In mouse macrophage and human leukocytes, 5′ lipoxygenase activity was also inhibited by the boron derivatives with IC50 values of 10-6M. These IC50 values for inhibition of these enzyme activities are consistent with published values of known anti-inflammatory agents which target these enzymes. PMID:18472741

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

Li, Yuzhan; Zhang, Yuehong; Rios, Orlando

In this study, a liquid crystalline epoxy network (LCEN) with exchangeable disulfide bonds is synthesized by polymerizing a biphenyl-based epoxy monomer with an aliphatic dicarboxylic acid curing agent containing a disulfide bond. The effect of disulfide bonds on curing behavior and liquid crystalline (LC) phase formation of the LCEN is investigated. The presence of the disulfide bonds results in an increase in the reaction rate, leading to a reduction in liquid crystallinity of the LCEN. In order to promote LC phase formation and stabilize the self-assembled LC domains, a similar aliphatic dicarboxylic acid without the disulfide bond is used asmore » a co-curing agent to reduce the amount of exchangeable disulfide bonds in the system. After optimizing the molar ratio of the two curing agents, the resulting LCEN exhibits improved reprocessability and recyclability because of the disulfide exchange reactions, while preserving LC properties, such as the reversible LC phase transition and macroscopic LC orientation, for shape memory applications.« less

Facile fabrication of superhydrophobic films with fractal structures using epoxy resin microspheres

NASA Astrophysics Data System (ADS)

Quan, Yun-Yun; Zhang, Li-Zhi

2014-02-01

A simple method has been developed to fabricate superhydrophobic surfaces with fractal structures with epoxy resin microspheres (ERMs). The ERMs is produced by phase separation in an epoxy-amine curing system with a silica sol (SS) dispersant. The transparent epoxy solution becomes cloudy and turns into epoxy suspension (ES) in this process. The fractal structure (two tier structure) generated by synthetic epoxy resin microspheres (ERMs) and deposited nanoincrutations on the surfaces of these ERMs, which have been observed by scanning electron microscope (SEM). The curing time of ES is an important condition to obtain films with good comprehensive performances. Superhydrophobic films can be prepared by adding extra SS into ES with a curing time longer than 5 h. The optimal curing time is 10 h to fabricate a film with good mechanical stability and high superhydrophobicity. In addition, a surface with anti-wetting property of impacting microdroplets can be fabricated by prolonging the curing time of ES to 24 h. The gradually decreased hydrophilic groups resulted from a longer curing time enable the surface to have smaller surface adhesions to water droplets, which is the main reason to keep its superhydrophobicity under impacting conditions. The coated surface is highly hydrophobic and the impacting water droplets are bounced off from the surface.

Composition and method for encapsulating photovoltaic devices

DOEpatents

Pern, Fu-Jann

2000-01-01

A composition and method for encapsulating a photovoltaic device which minimizes discoloration of the encapsulant. The composition includes an ethylene-vinyl acetate encapsulant, a curing agent, an optional ultraviolet light stabilizer, and/or an optional antioxidant. The curing agent is preferably 1,1-di-(t-butylperoxy)-3,3,5-trimethylcyclohexane; the ultraviolet light stabilizer is bis-(N-octyloxy-tetramethyl) piperidinyl sebacate and the antioxidant is selected from the group consisting of tris (2,4-di-tert-butylphenyl) phosphite, tetrakis methylene (3,5-di-tert-butyl-4-hydroxyhydrocinnamate) methane, octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate, and 2,2'-ethylidene bis(4,6-di-t-butylphenyl) fluorophosponite. The composition is applied to a solar cell then cured. The cured product contains a minimal concentration of curing-generated chromophores and resists UV-induced degradation.

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.

Latent Hardeners for the Assembly of Epoxy Composites

NASA Technical Reports Server (NTRS)

Palmieri, Frank; Wohl, Christopher J.; Connell, John W.; Mercado, Zoar; Galloway, Jordan

2016-01-01

Large-scale composite structures are commonly joined by secondary bonding of molded-and-cured thermoset components. This approach may result in unpredictable joint strengths. In contrast, assemblies made by co-curing, although limited in size by the mold, result in stable structures, and are certifiable for commercial aviation because of structural continuity through the joints. Multifunctional epoxy resins were prepared that should produce fully-cured subcomponents with uncured joining surfaces, enabling them to be assembled by co-curing in a subsequent out-of-autoclave process. Aromatic diamines were protected by condensation with a ketone or aldehyde to form imines. Properties of the amine-cured epoxy were compared with those of commercially available thermosetting epoxy resins and rheology and thermal analysis were used to demonstrate the efficacy of imine protection. Optimum conditions to reverse the protecting chemistry in the solid state using moisture and acid catalysis were determined. Alternative chemistries were also investigated. For example, chain reaction depolymerization and photoinitiated catalysts would be expected to minimize liberation of volatile organic content upon deprotection and avoid residual reactive species that could damage the resin. Results from the analysis of protected and deprotected resins will be presented.

Chiral 2-Aminobenzimidazole as Bifunctional Catalyst in the Asymmetric Electrophilic Amination of Unprotected 3-Substituted Oxindoles.

PubMed

Benavent, Llorenç; Baeza, Alejandro; Freckleton, Megan

2018-06-06

The use of readily available chiral trans -cyclohexanediamine-benzimidazole derivatives as bifunctional organocatalysts in the asymmetric electrophilic amination of unprotected 3-substituted oxindoles is presented. Different organocatalysts were evaluated; the most successful one contained a dimethylamino moiety ( 5 ). With this catalyst under optimized conditions, different oxindoles containing a wide variety of substituents at the 3-position were aminated in good yields and with good to excellent enantioselectivities using di- tert -butylazodicarboxylate as the aminating agent. The procedure proved to be also efficient for the amination of 3-substituted benzofuranones, although with moderate results. A bifunctional role of the catalyst, acting as Brønsted base and hydrogen bond donor, is proposed according to the experimental results observed.

Rates of nickel(II) capture from complexes with NTA, EDDA, and related tetradentate chelating agents by the hexadentate chelating agents EDTA and CDTA: Evidence of a "semijunctive" ligand exchange pathway

NASA Astrophysics Data System (ADS)

Boland, Nathan E.; Stone, Alan T.

2017-09-01

Many siderophores and metallophores produced by soil organisms, as well as anthropogenic chelating agent soil amendments, rely upon amine and carboxylate Lewis base groups for metal ion binding. UV-visible spectra of metal ion-chelating agent complexes are often similar and, as a consequence, whole-sample absorbance measurements are an unreliable means of monitoring the progress of exchange reactions. In the present work, we employ capillary electrophoresis to physically separate Ni(II)-tetradentate chelating agent complexes (NiL) from Ni(II)-hexadentate chelating agent complexes (NiY) prior to UV detection, such that progress of the reaction NiL + Y → NiY + L can be conveniently monitored. Rates of ligand exchange for Ni(II) are lower than for other +II transition metal ions. Ni(II) speciation in environmental media is often under kinetic rather than equilibrium control. Nitrilotriacetic acid (NTA), with three carboxylate groups all tethered to a central amine Lewis base group, ethylenediamine-N,N‧-diacetic acid (EDDA), with carboxylate-amine-amine-carboxylate groups arranged linearly, plus four structurally related compounds, are used as tetradentate chelating agents. Ethylenediaminetetraacetic acid (EDTA) and the structurally more rigid analog trans-cyclohexaneethylenediaminetetraacetic acid (CDTA) are used as hexadentate chelating agents. Effects of pH and reactant concentration are explored. Ni(II) capture by EDTA was consistently more than an order of magnitude faster than capture by CDTA, and too fast to quantify using our capillary electrophoresis-based technique. Using NiNTA as a reactant, Ni(II) capture by CDTA is independent of CDTA concentration and greatly enhanced by a proton-catalyzed pathway at low pH. Using NiEDDA as reactant, Ni(II) capture by CDTA is first order with respect to CDTA concentration, and the contribution from the proton-catalyzed pathway diminished by CDTA protonation. While the convention is to assign either a disjunctive pathway or adjunctive pathway to multidentate ligand exchange reactions, our results indicate that a third "semijunctive" pathway is necessary to account for slow reactions progressing through Lsbnd Nisbnd Y ternary complexes. Ligand exchange pathways with NTA-type chelating agents are assigned a disjunctive pathway, while pathways with EDDA-type chelating agents are assigned a semijunctive pathway. Based upon operative mechanism(s), magnitudes of exchange rates and effects of ambient geochemical conditions can be predicted.

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

Socha, Aaron; Singh, Seema; Simmons, Blake A.

Methods and compositions are provided for synthesizing ionic liquids from lignin derived compounds comprising: contacting a starting material comprising lignin with a depolymerization agent to depolymerize the lignin and form a mixture of aldehyde containing compounds; contacting the mixture of aldehyde containing compounds with an amine under conditions suitable to convert the mixture of aldehyde containing compounds to a mixture of amine containing compounds; and contacting the mixture of amine containing compounds with an acid under conditions suitable to form an ammonium salt, thereby preparing the ionic liquid.

2-Aminoquinazolin-4(3H)-one as an Organocatalyst for the Synthesis of Tertiary Amines.

PubMed

Thakur, Maheshwar S; Nayal, Onkar S; Upadhyay, Rahul; Kumar, Neeraj; Maurya, Sushil K

2018-03-02

The potential of 2-aminoquinazolin-4(3H)-one as an organocatalyst for the activation of aldehydes via noncovalent interaction for the synthesis of tertiary amines using formic acid as a reducing agent is reported for the first time. The developed protocol demonstrated a dilated substrate scope for aromatic and aliphatic amines with aromatic and aliphatic aldehydes. Furthermore, the current method was also fruitful for the derivatization of ciprofloxacin and its derivative in good to excellent yields.

Siloxane Modifiers for Epoxy Resins.

DTIC Science & Technology

1983-12-01

similarly prepared ATBN- and CTBN -modified epoxies. Wear rate was quite dramatically reduced with some of the modifiers. Wear results are discussed in...similarly prepared ATBN- and CTBN -modified epoxies. Wear rate was quite dramatically reduced with some of the modifiers. Wear results are discussed...acrylonitrile copolymers having both carboxyl ( CTBN ) and amine (ATBN) end groups have been widely used as epoxy modifiers (4-11). During the curing process, the

Simple catalytic mechanism for the direct coupling of α-carbonyls with functionalized amines: a one-step synthesis of Plavix.

PubMed

Evans, Ryan W; Zbieg, Jason R; Zhu, Shaolin; Li, Wei; MacMillan, David W C

2013-10-30

The direct α-amination of ketones, esters, and aldehydes has been accomplished via copper catalysis. In the presence of catalytic copper(II) bromide, a diverse range of carbonyl and amine substrates undergo fragment coupling to produce synthetically useful α-amino-substituted motifs. The transformation is proposed to proceed via a catalytically generated α-bromo carbonyl species; nucleophilic displacement of the bromide by the amine then delivers the α-amino carbonyl adduct while the catalyst is reconstituted. The practical value of this transformation is highlighted through one-step syntheses of two high-profile pharmaceutical agents, Plavix and amfepramone.

A Simple Catalytic Mechanism for the Direct Coupling of α-Carbonyls with Functionalized Amines: A One-Step Synthesis of Plavix

PubMed Central

Evans, Ryan W.; Zbieg, Jason R.; Zhu, Shaolin; Li, Wei; MacMillan, David W. C.

2014-01-01

The direct α-amination of ketones, esters, and aldehydes has been accomplished via copper catalysis. In the presence of catalytic copper(II) bromide, a diverse range of carbonyl and amine substrates undergo fragment coupling to produce synthetically useful α-amino substituted motifs. The transformation is proposed to proceed via a catalytically generated α-bromo carbonyl species; nucleophilic displacement of the bromide by the amine then delivers the α-amino carbonyl adduct while the catalyst is reconstituted. The practical value of this transformation is highlighted through one-step syntheses of two high–profile pharmaceutical agents, Plavix and amfepramone. PMID:24107144

Highly luminescent carbon nanodots by microwave-assisted pyrolysis.

PubMed

Zhai, Xinyun; Zhang, Peng; Liu, Changjun; Bai, Tao; Li, Wenchen; Dai, Liming; Liu, Wenguang

2012-08-18

Carbon nanodots (CDs) with a low cytotoxicity have been synthesized by one-step microwave-assisted pyrolysis of citric acid in the presence of various amine molecules. The primary amine molecules have been confirmed to serve dual roles as N-doping precursors and surface passivation agents, both of which considerably enhanced the fluorescence of the CDs.

Synthesis of structurally diverse major groove DNA interstrand crosslinks using three different aldehyde precursors

PubMed Central

Mukherjee, Shivam; Guainazzi, Angelo; Schärer, Orlando D.

2014-01-01

DNA interstrand crosslinks (ICLs) are extremely cytotoxic lesions that block essential cellular processes, such as replication and transcription. Crosslinking agents are widely used in cancer chemotherapy and form an array of structurally diverse ICLs. Despite the clinical success of these agents, resistance of tumors to crosslinking agents, for example, through repair of these lesions by the cellular machinery remains a problem. We have previously reported the synthesis of site-specific ICLs mimicking those formed by nitrogen mustards to facilitate the studies of cellular responses to ICL formation. Here we extend these efforts and report the synthesis of structurally diverse major groove ICLs that induce severe, little or no distortion in the DNA. Our approach employs the incorporation of aldehyde precursors of different lengths into complementary strands and ICL formation using a double reductive amination with a variety of amines. Our studies provide insight into the structure and reactivity parameters of ICL formation by double reductive amination and yield a set of diverse ICLs that will be invaluable for exploring structure–activity relationships in ICL repair. PMID:24782532

Titanium(IV) isopropoxide mediated solution phase reductive amination on an automated platform: application in the generation of urea and amide libraries.

PubMed

Bhattacharyya, S; Fan, L; Vo, L; Labadie, J

2000-04-01

Amine libraries and their derivatives are important targets for high throughput synthesis because of their versatility as medicinal agents and agrochemicals. As a part of our efforts towards automated chemical library synthesis, a titanium(IV) isopropoxide mediated solution phase reductive amination protocol was successfully translated to automation on the Trident(TM) library synthesizer of Argonaut Technologies. An array of 24 secondary amines was prepared in high yield and purity from 4 primary amines and 6 carbonyl compounds. These secondary amines were further utilized in a split synthesis to generate libraries of ureas, amides and sulfonamides in solution phase on the Trident(TM). The automated runs included 192 reactions to synthesize 96 ureas in duplicate and 96 reactions to synthesize 48 amides and 48 sulfonamides. A number of polymer-assisted solution phase protocols were employed for parallel work-up and purification of the products in each step.

Preparation of amine-impregnated silica foams using agar as the gelling agent

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

Jardim, Iara M., E-mail: iaramj01@yahoo.com.br

In this work we successfully prepared amine-impregnated gel-cast silica foams using agar and atmospheric air as the gelling agent and heat treatment atmosphere, respectively. The concentration of 3,6-anhydrogalactose in agar was evaluated by ultraviolet–visible spectroscopy (UV–Vis). The obtained foams were examined by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG) coupled to mass spectrometry (TG-MS), scanning electron microscopy (SEM), X-ray microtomography (micro-CT), and Archimedes method. The cold crushing strength of the materials prepared in this work was assessed using a mechanical testing stage available in the micro-CT system. The obtained foams exhibited a highly interconnected pore network, with an expressivemore » presence of open pores. Samples heat-treated at 1300 °C for 2 h showed both an expressive porosity (≈ 77%) and a significant cold crushing strength (≈ 1.4 MPa). It was observed that the calcination of the prepared materials at 1200 °C for times as long as 16 h may lead to the rupture of pore walls. FTIR and TG-MS revealed that amine groups were properly incorporated into the foams structure. - Highlights: •Successful preparation of amine-impregnated gel-cast silica foams •Agar used as the gelling agent •Samples with expressive porosity and cold crushing strength •Sintering times as long as 16 h led to the rupture of the pore network.« less

Liquid crystalline epoxy networks with exchangeable disulfide bonds

DOE PAGES

Li, Yuzhan; Zhang, Yuehong; Rios, Orlando; ...

2017-06-09

In this study, a liquid crystalline epoxy network (LCEN) with exchangeable disulfide bonds is synthesized by polymerizing a biphenyl-based epoxy monomer with an aliphatic dicarboxylic acid curing agent containing a disulfide bond. The effect of disulfide bonds on curing behavior and liquid crystalline (LC) phase formation of the LCEN is investigated. The presence of the disulfide bonds results in an increase in the reaction rate, leading to a reduction in liquid crystallinity of the LCEN. In order to promote LC phase formation and stabilize the self-assembled LC domains, a similar aliphatic dicarboxylic acid without the disulfide bond is used asmore » a co-curing agent to reduce the amount of exchangeable disulfide bonds in the system. After optimizing the molar ratio of the two curing agents, the resulting LCEN exhibits improved reprocessability and recyclability because of the disulfide exchange reactions, while preserving LC properties, such as the reversible LC phase transition and macroscopic LC orientation, for shape memory applications.« less

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.

Multi-step cure kinetic model of ultra-thin glass fiber epoxy prepreg exhibiting both autocatalytic and diffusion-controlled regimes under isothermal and dynamic-heating conditions

NASA Astrophysics Data System (ADS)

Kim, Ye Chan; Min, Hyunsung; Hong, Sungyong; Wang, Mei; Sun, Hanna; Park, In-Kyung; Choi, Hyouk Ryeol; Koo, Ja Choon; Moon, Hyungpil; Kim, Kwang J.; Suhr, Jonghwan; Nam, Jae-Do

2017-08-01

As packaging technologies are demanded that reduce the assembly area of substrate, thin composite laminate substrates require the utmost high performance in such material properties as the coefficient of thermal expansion (CTE), and stiffness. Accordingly, thermosetting resin systems, which consist of multiple fillers, monomers and/or catalysts in thermoset-based glass fiber prepregs, are extremely complicated and closely associated with rheological properties, which depend on the temperature cycles for cure. For the process control of these complex systems, it is usually required to obtain a reliable kinetic model that could be used for the complex thermal cycles, which usually includes both the isothermal and dynamic-heating segments. In this study, an ultra-thin prepreg with highly loaded silica beads and glass fibers in the epoxy/amine resin system was investigated as a model system by isothermal/dynamic heating experiments. The maximum degree of cure was obtained as a function of temperature. The curing kinetics of the model prepreg system exhibited a multi-step reaction and a limited conversion as a function of isothermal curing temperatures, which are often observed in epoxy cure system because of the rate-determining diffusion of polymer chain growth. The modified kinetic equation accurately described the isothermal behavior and the beginning of the dynamic-heating behavior by integrating the obtained maximum degree of cure into the kinetic model development.

Reaction of Orthoesters with Amine Hydrochlorides: An Introductory Organic Lab Experiment Combining Synthesis, Spectral Analysis, and Mechanistic Discovery

ERIC Educational Resources Information Center

Saba, Shahrokh; Ciaccio, James A.

2016-01-01

While orthoesters are often used by chemists as alkylating, acylating, and formylating agents, they are rarely encountered in introductory organic chemistry curricula. We describe a second-semester organic chemistry laboratory experiment in which students acetylate unknown amine hydrochloride salts with trimethyl orthoacetate (TMOA) in the absence…

Cure Kinetics of Epoxy Nanocomposites Affected by MWCNTs Functionalization: A Review

PubMed Central

Saeb, Mohammad Reza; Bakhshandeh, Ehsan; Khonakdar, Hossein Ali; Mäder, Edith; Scheffler, Christina; Heinrich, Gert

2013-01-01

The current paper provides an overview to emphasize the role of functionalization of multiwalled carbon nanotubes (MWCNTs) in manipulating cure kinetics of epoxy nanocomposites, which itself determines ultimate properties of the resulting compound. In this regard, the most commonly used functionalization schemes, that is, carboxylation and amidation, are thoroughly surveyed to highlight the role of functionalized nanotubes in controlling the rate of autocatalytic and vitrification kinetics. The current literature elucidates that the mechanism of curing in epoxy/MWCNTs nanocomposites remains almost unaffected by the functionalization of carbon nanotubes. On the other hand, early stage facilitation of autocatalytic reactions in the presence of MWCNTs bearing amine groups has been addressed by several researchers. When carboxylated nanotubes were used to modify MWCNTs, the rate of such reactions diminished as a consequence of heterogeneous dispersion within the epoxy matrix. At later stages of curing, however, the prolonged vitrification was seen to be dominant. Thus, the type of functional groups covalently located on the surface of MWCNTs directly affects the degree of polymer-nanotube interaction followed by enhancement of curing reaction. Our survey demonstrated that most widespread efforts ever made to represent multifarious surface-treated MWCNTs have not been directed towards preparation of epoxy nanocomposites, but they could result in property synergism. PMID:24348181

Modification of the effects of guanethidine on cardiac catechol amines by various agents

PubMed Central

Bhagat, B.

1964-01-01

A study has been made of the effect of injections of guanethidine in rats, in depleting catechol amines from the whole cardiac ventricles and from various subcellular fractions. Unlike reserpine, guanethidine first affected the concentration of the amines in the soluble fraction of the cell. Neither [2-(2,6-dimethylphenoxy)-propyl]trimethylammonium chloride monohydrate (β-methyl xylocholine) nor hemicholinium affected the endogenous catechol amines or the uptake of injected noradrenaline, but each significantly reduced the action of guanethidine in depleting catechol amines. Administration of choline chloride after hemicholinium reversed its influence on guanethidine depletion. In cats, cocaine potentiated the pressor response to noradrenaline, but antagonized the response to tyramine and guanethidine, while bretylium and N-o-chlorobenzyl-N'N”-dimethylguanidine sulphate (BW392C60) potentiated the responses to noradrenaline, tyramine and guanethidine. PMID:14190459

Microleakage of light-cured resin and resin-modified glass-ionomer dentin bonding agents applied with co-cure vs pre-cure technique.

PubMed

Tulunoglu, O; Uçtaşh, M; Alaçam, A; Omürlü, H

2000-01-01

This in vitro study evaluated the effect of dentin bonding agents in reducing microleakage after three months in Class V restorations restored with Z100 resin composite. Materials tested were three types of resin-based dentin bonding agents: a multi-step (Scotchbond Multi-Purpose); a one-step (Scotchbond One-Step); a self-etching, self-priming (Clearfil Liner Bond) and a resin-modified glass ionomer (GC Fuji Bond LC). Class V cavity preparations with occlusal margins in enamel and gingival margins in cementum were prepared both on labial and lingual surfaces of extracted premolar teeth. Restorations (two per tooth) were distributed randomly into nine test groups (n = 10) consisting of the various DBAs applied with co-cure and pre-cure techniques, and no dentin bonding as a negative control group. Samples were stored in saline for three months, thermocycled, stained with silver nitrate, then sectioned through the middle of the preparation to facilitate the removal of the composite resin restoration. For groups treated with the pre-cure technique, the differences between the enamel leakage values of SBMP-control, CFLB-control and SB1S-control subgroups were significant (p < 0.05). For enamel leakage values of groups treated with the co-cure technique, the differences between the SBMP-control, SB1S-control, CFLB-control and Fuji LC-control subgroups were significant (p < 0.05). For cementum leakage values of groups treated with pre-cure technique, the difference between the CFLB-control and the Fuji, SBMP and SB1S groups was significant (p < 0.05). No significant differences could be detected between the cementum leakage values of groups treated with the co-cure technique (p > 0.05). The differences between the values obtained with application of CFLB with the pre-cure and co-cure techniques at the cementum margins were found to be statistically significant (p = 0.02). No statistically significant differences could be detected between the pre-cure and co-cure values of the other test materials. Generally for every group, cementum microleakage values were greater than enamel microleakage values (p < 0.05). The use of Scotchbond Multi-Purpose, Scotchbond One-Step and Fuji Bond LC with the co-cure technique to decrease the application time did not cause any significant increase in microleakage. Only pre-curing using Clearfil Liner Bond provided better microleakage properties than the other pre-cured adhesives.

Ultrasonic characterization of changes in viscoelastic properties of epoxy during cure

NASA Technical Reports Server (NTRS)

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

1985-01-01

A technique for using the longitudinal velocity (LV) of an ultrasonic wave to monitor the extent of cross linking (CL) during the cure of thermosetting resins is described. The method was developed by monitoring the rate of change in LV during the cure of a bisphenol-A epoxy resin with an amine adduct. The experiment included variations in the temperature and stoichiometry in order to express the rate of change in terms of the reaction kinetics. The pulse-echo method was used with a single transducer operating at 20 MHz. Numerical models were defined to account for the acoustic response of a single layer, the attenuation and the reflection coefficient. A linear relationship was observed between the inverse of the temperature and the log of the rate of change in the velocity, supporting the theory that the velocity could be used to monitor the extent of the cross-linking reaction. An activation energy of 11.9 kcal/mole was calculated for the mixture being investigated.

Preparation of hyperbranched poly (amidoamine)-grafted graphene nanolayers as a composite and curing agent for epoxy resin

NASA Astrophysics Data System (ADS)

Gholipour-Mahmoudalilou, Meysam; Roghani-Mamaqani, Hossein; Azimi, Reza; Abdollahi, Amin

2018-01-01

Thermal properties of epoxy resin were improved by preparation of a curing agent of poly (amidoamine) (PAMAM) dendrimer-grafted graphene oxide (GO). Hyperbranched PAMAM-modified GO (GD) was prepared by a divergent dendrimer synthesis methodology. Modification of GO with (3-Aminopropyl)triethoxysilane (APTES), Michael addition of methacrylic acid, and amidation reaction with ethylenediamine results in the curing agent of GD. Then, epoxy resin was cured in the presence of different amounts of GD and the final products were compared with ethylenediamine-cured epoxy resin (E) in their thermal degradation temperature and char contents. Functionalization of GO with APTES and hyperbranched dendrimer formation at the surface of GO were evaluated by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and thermogravimetric analysis (TGA) results. TGA results showed that the weight loss associated with chemical moieties in GONH2, GOMA, and GD is estimated to be 10.1, 12.2, and 14.1%, respectively. Covalent attachment of dendrimer at the surface of GO increases its thermal stability. TGA also showed that decomposition temperature and char content are higher for composites compared with E. Scanning and transmission electron microscopies show that flat and smooth graphene nanolayers are wrinkled in GO and re-stacking and flattening of nanolayers is observed in GD.

Ultrasonic Mixing of Epoxy Curing Agents.

DTIC Science & Technology

1983-05-01

Li~fl , • 4 Future generation aircraft need higher performance polymer matrices to fully achieve the weight savings possible with composite materials...ref. 1). New resins are being formulated in an effort to understand basic polymer behav- ior and to develop improved resins (refs. 2, 3 and 4). Some... polymer /curing agent combinations that could be useful, cannot be mixed properly using conven- tional methods because of the high melting temperature

Epoxy matrix with triaromatic mesogenic unit in dielectric spectroscopy observation

NASA Astrophysics Data System (ADS)

Włodarska, Magdalena; Mossety-Leszczak, Beata; Bąk, Grzegorz W.; Kisiel, Maciej; Dłużniewski, Maciej; Okrasa, Lidia

2018-04-01

This paper describes the dielectric response of a selected liquid crystal epoxy monomer (plain and in curing systems) in a wide range of frequency and temperature. The dielectric spectroscopy, thanks to its sensitivity, is a very good tool for studying phase transitions, reaction progress, or material properties. This sensitivity is important in the case of liquid crystal epoxy resins, where properties of the final network depend on the choice of monomers, curing agents, curing conditions and post-curing treatment, or applying an external electric or magnetic field during the reaction. In most of the obtained cured products, the collected dielectric data show two relaxation processes. The α-process is related to a structural reorientation; it can usually be linked with the glass transition and the mechanical properties of the material. The β-process can be identified as a molecular motion process, probably associated with the carboxyl groups in the mesogen. A transient Maxwell-Wagner relaxation observed in one of the compositions after the initial curing is removed by post-curing treatment at elevated temperatures. Post-curing is therefore necessary for obtaining uniformly cured products in those cases. In the investigated systems, the choice of a curing agent can change the glass transition temperature by at least 70 °C. The obtained results are in a good agreement with an earlier study employing other techniques. Finally, we assess the influence of the direction of mesogen alignment on the dielectric properties of one selected system, where a global order was induced by applying an external magnetic field in the course of curing.

Development of a fast curing tissue adhesive for meniscus tear repair.

PubMed

Bochyńska, Agnieszka Izabela; Hannink, Gerjon; Janssen, Dennis; Buma, Pieter; Grijpma, Dirk W

2017-01-01

Isocyanate-terminated adhesive amphiphilic block copolymers are attractive materials to treat meniscus tears due to their tuneable mechanical properties and good adhesive characteristics. However, a drawback of this class of materials is their relatively long curing time. In this study, we evaluate the use of an amine cross-linker and addition of catalysts as two strategies to accelerate the curing rates of a recently developed biodegradable reactive isocyanate-terminated hyper-branched adhesive block copolymer prepared from polyethylene glycol (PEG), trimethylene carbonate, citric acid and hexamethylene diisocyanate. The curing kinetics of the hyper-branched adhesive alone and in combination with different concentrations of spermidine solutions, and after addition of 2,2-dimorpholinodiethylether (DMDEE) or 1,4-diazabicyclo [2.2.2] octane (DABCO) were determined using FTIR. Additionally, lap-shear adhesion tests using all compositions at various time points were performed. The two most promising compositions of the fast curing adhesives were evaluated in a meniscus bucket handle lesion model and their performance was compared with that of fibrin glue. The results showed that addition of both spermidine and catalysts to the adhesive copolymer can accelerate the curing rate and that firm adhesion can already be achieved after 2 h. The adhesive strength to meniscus tissue of 3.2-3.7 N was considerably higher for the newly developed compositions than for fibrin glue (0.3 N). The proposed combination of an adhesive component and a cross-linking component or catalyst is a promising way to accelerate curing rates of isocyanate-terminated tissue adhesives.

Bio-based epoxy/chitin nanofiber composites cured with amine-type hardeners containing chitosan.

PubMed

Shibata, Mitsuhiro; Enjoji, Motohiro; Sakazume, Katsumi; Ifuku, Shinsuke

2016-06-25

Sorbitol polyglycidyl ether (SPE) which is a bio-based water-soluble epoxy resin was cured with chitosan (CS) and/or a commercial water-soluble polyamidoamine- or polyetheramine-type epoxy hardener (PAA or PEA). Furthermore, biocomposites of the CS-cured SPE (CS-SPE) and CS/PAA- or CS/PEA-cured SPE (SPE-CA or SPE-CE) biocomposites with chitin nanofiber (CNF) were prepared by casting and compression molding methods, respectively. The curing reaction of epoxy and amino groups of the reactants was confirmed by the FT-IR spectral analysis. SPE-CS and SPE-CA were almost transparent films, while SPE-CE was opaque. Transparency of SPE-CS/CNF and SPE-CA/CNF became a little worse with increasing CNF content. The tanδ peak temperature of SPE-CS was higher than those of SPE-PAA and SPE-PEA. SPE-CA or SPE-CE exhibited two tanδ peak temperatures related to glass transitions of the CS-rich and PAA-rich or PEA-rich moieties. The tanδ peak temperatures related to the CS-rich and PAA-rich moieties increased with increasing CNF content. A higher order of tensile strengths and moduli of the cured resins was SPE-CS≫SPE-CA>SPE-CE. The tensile strength and modulus of each sample were much improved by the addition of 3wt% CNF, while further addition of CNF caused a lowering of the strength and modulus. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Effect of Water on the Work of Adhesion at Epoxy Interfaces by Molecular Dynamics Simulation

NASA Technical Reports Server (NTRS)

Hinkley, J.A.; Frankland, S.J.V.; Clancy, T.C.

2009-01-01

Molecular dynamics simulation can be used to explore the detailed effects of chemistry on properties of materials. In this paper, two different epoxies found in aerospace resins are modeled using molecular dynamics. The first material, an amine-cured tetrafunctional epoxy, represents a composite matrix resin, while the second represents a 177 C-cured adhesive. Surface energies are derived for both epoxies and the work of adhesion values calculated for the epoxy/epoxy interfaces agree with experiment. Adding water -- to simulate the effect of moisture exposure -- reduced the work of adhesion in one case, and increased it in the other. To explore the difference, the various energy terms that make up the net work of adhesion were compared and the location of the added water was examined.

A one-pot radioiodination of aryl amines via stable diazonium salts: preparation of 125I-imaging agents.

PubMed

Sloan, Nikki L; Luthra, Sajinder K; McRobbie, Graeme; Pimlott, Sally L; Sutherland, Andrew

2017-10-05

An operationally simple, one-pot, two-step tandem procedure that allows the incorporation of radioactive iodine into aryl amines via stable diazonium salts is described. The mild conditions are tolerant of various functional groups and substitution patterns, allowing late-stage, rapid access to a wide range of 125 I-labelled aryl compounds and SPECT radiotracers.

Elastomer toughened polyimide adhesives

NASA Technical Reports Server (NTRS)

St.clair, A. K.; St.clair, T. L. (Inventor)

1983-01-01

A rubber-toughened addition-type polyimide composition is disclosed which has excellent high temperature bonding characteristics in the fully cured state, and improved peel strength and adhesive fracture resistance physical property characteristics. The process for making the improved adhesive involves preparing the rubber containing amic acid prepolymer by chemically reacting an amine-terminated elastomer and an aromatic diamine with an aromatic dianhydride with which a reactive chain stopper anhydride was mixed, and utilizing solvent or mixture of solvents for the reaction.

Copper-catalyzed selective hydroamination reactions of alkynes

PubMed Central

Shi, Shi-Liang; Buchwald, Stephen L.

2014-01-01

The development of selective reactions that utilize easily available and abundant precursors for the efficient synthesis of amines is a longstanding goal of chemical research. Despite the centrality of amines in a number of important research areas, including medicinal chemistry, total synthesis and materials science, a general, selective, and step-efficient synthesis of amines is still needed. In this work we describe a set of mild catalytic conditions utilizing a single copper-based catalyst that enables the direct preparation of three distinct and important amine classes (enamines, α-chiral branched alkylamines, and linear alkylamines) from readily available alkyne starting materials with high levels of chemo-, regio-, and stereoselectivity. This methodology was applied to the asymmetric synthesis of rivastigmine and the formal synthesis of several other pharmaceutical agents, including duloxetine, atomoxetine, fluoxetine, and tolterodine. PMID:25515888

Copper-catalysed selective hydroamination reactions of alkynes

NASA Astrophysics Data System (ADS)

Shi, Shi-Liang; Buchwald, Stephen L.

2015-01-01

The development of selective reactions that utilize easily available and abundant precursors for the efficient synthesis of amines is a long-standing goal of chemical research. Despite the centrality of amines in a number of important research areas, including medicinal chemistry, total synthesis and materials science, a general, selective and step-efficient synthesis of amines is still needed. Here, we describe a set of mild catalytic conditions utilizing a single copper-based catalyst that enables the direct preparation of three distinct and important amine classes (enamines, α-chiral branched alkylamines and linear alkylamines) from readily available alkyne starting materials with high levels of chemo-, regio- and stereoselectivity. This methodology was applied to the asymmetric synthesis of rivastigmine and the formal synthesis of several other pharmaceutical agents, including duloxetine, atomoxetine, fluoxetine and tolterodine.

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

Pern, F.J.; Glick, S.H.; Czanderna, A.W.

Results from extensive studies of the commercial ethylene vinyl acetate (EVA) formulations show that the UV absorber and curing-generated UV-excitable, {alpha},{beta}-unsaturated carbonyl chromophores facilitate the EVA discoloration, which is further enhanced by curing-generated acetic acid and probably residual peroxide curing agent also. Formation and concentration of the UV-excitable chromophores are substantially promoted by the antioxidant, Naugard P. The discoloration rate is greater under higher UV light intensity and temperatures. Heating in the dark at elevated temperatures (e.g., 85&hthinsp;{degree}C) in the air for {approximately}200 days only results in light yellowing. The discoloration reactions compete with photobleaching reactions, which destroy curing-generated chromophoresmore » and result in non-discoloring of EVA. By using better performance stabilizers to minimize the curing-generated UV-excitable chromophores, a new fast curing agent, and no UV absorber, the NREL-developed EVA formulations show a superior photothermal stability against browning to the commercial counterparts. Alternatively, the discoloration rate of the commercial EVA pottants can be considerably reduced by using UV-filtering glass superstrates that largely inhibit the UV-induced photooxidation reactions, or completely eliminated by using air-permeable polymer superstrate films that enable photobleaching reactions. {copyright} {ital 1999 American Institute of Physics.}« less

Thermal processing of EVA encapsulants and effects of formulation additives

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

Pern, F.J.; Glick, S.H.

1996-05-01

The authors investigated the in-situ processing temperatures and effects of various formulation additives on the formation of ultraviolet (UV) excitable chromophores, in the thermal lamination and curing of ethylene-vinyl acetate (EVA) encapsulants. A programmable, microprocessor-controlled, double-bag vacuum laminator was used to study two commercial as formulated EVA films, A9918P and 15295P, and solution-cast films of Elvaxrm (EVX) impregnated with various curing agents and antioxidants. The results show that the actual measured temperatures of EVA lagged significantly behind the programmed profiles for the heating elements and were affected by the total thermal mass loaded inside the laminator chamber. The antioxidant Naugardmore » P{trademark}, used in the two commercial EVA formulations, greatly enhances the formation of UV-excitable, short chromophores upon curing, whereas other tested antioxidants show little effect. A new curing agent chosen specifically for the EVA formulation modification produces little or no effect on chromophore formation, no bubbling problems in the glass/EVX/glass laminates, and a gel content of {approximately}80% when cured at programmed 155{degrees}C for 4 min. Also demonstrated is the greater discoloring effect with higher concentrations of curing-generated chromophores.« less

Thermal processing of EVA encapsulants and effects of formulation additives

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

Pern, F.J.; Glick, S.H.

1996-09-01

The authors investigated the in-situ processing temperatures and effects of various formulation additives on the formation of ultraviolet (UV) excitable chromophores in the thermal lamination and curing of ethylene-vinyl acetate (EVA) encapsulants. A programmable, microprocessor-controlled, double-bag vacuum laminator was used to study two commercial as-formulated EVA films. A9918P and 15295P, and solution-cast films of Elvax{trademark} (EVX) impregnated with various curing agents and antioxidants. The results show that the actual measured temperatures of EVA lagged significantly behind the programmed profiles for the heating elements and were affected by the total thermal mass loaded inside the laminator chamber. The antioxidant Naugard P{trademark},more » used in the two commercial EVA formulations, greatly enhances the formation of UV-excitable, short chromophores upon curing, whereas other tested antioxidants show little effect. A new curing agent chosen specifically for the EVA formulation modification produces little or no effect on chromophore formation, no bubbling problems in the glass/EVX/glass laminates, and a gel content of {approximately}80% when cured at programmed 155 C for 4 min. Also demonstrated is the greater discoloring effect with higher concentrations of curing-generated chromophores.« less

Diastereoselective preparation of (R)- and (S)-2-methoxy-2-phenylpent-3-ynoic acids and their use as reliable chiral derivatizing agents.

PubMed

Pérez-Estrada, Salvador; Joseph-Nathan, Pedro; Jiménez-Vázquez, Hugo A; Medina-López, Manuel E; Ayala-Mata, Francisco; Zepeda, L Gerardo

2012-02-17

Benzoyl-S,O-acetals 1a and 1b were used as chiral auxiliaries to achieve the diastereoselective preparation of both enantiomers of 2-methoxy-2-phenylpent-3-ynoic acids (MPPAs). The latter were condensed with several chiral secondary alcohols and some primary amines to evaluate their potential as chiral derivatizing agents (CDAs). The (1)H NMR spectra of the corresponding esters and amides showed strong consistency with the absolute configuration of the carbinol and amine moieties, whose observed ΔδL(1) and ΔδL(2) values were in the ranges of 0.1-0.4 and 0.02-0.12 ppm, respectively.

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.

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 Central

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

2003-01-01

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

Method of stripping metals from organic solvents

DOEpatents

Todd, Terry A [Aberdeen, ID; Law, Jack D [Pocatello, ID; Herbst, R Scott [Idaho Falls, ID; Romanovskiy, Valeriy N [St. Petersburg, RU; Smirnov, Igor V [St.-Petersburg, RU; Babain, Vasily A [St-Petersburg, RU; Esimantovski, Vyatcheslav M [St-Petersburg, RU

2009-02-24

A new method to strip metals from organic solvents in a manner that allows for the recycle of the stripping agent. The method utilizes carbonate solutions of organic amines with complexants, in low concentrations, to strip metals from organic solvents. The method allows for the distillation and reuse of organic amines. The concentrated metal/complexant fraction from distillation is more amenable to immobilization than solutions resulting from current practice.

Sequential continuous flow processes for the oxidation of amines and azides by using HOF·MeCN.

PubMed

McPake, Christopher B; Murray, Christopher B; Sandford, Graham

2012-02-13

The generation and use of the highly potent oxidising agent HOF·MeCN in a controlled single continuous flow process is described. Oxidations of amines and azides to corresponding nitrated systems by using fluorine gas, water and acetonitrile by sequential gas-liquid/liquid-liquid continuous flow procedures are reported. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Occurrence of aromatic amines and N-nitrosamines in the different steps of a drinking water treatment plant.

PubMed

Jurado-Sánchez, Beatriz; Ballesteros, Evaristo; Gallego, Mercedes

2012-09-15

The occurrence of 24 amines within a full scale drinking water treatment plant that used chlorinated agents as disinfectants was evaluated for the first time in this research. Prior to any treatment (raw water), aniline, 3-chloroaniline, 3,4-dichloroaniline and N-nitrosodimethylamine were detected at low levels (up to 18 ng/L) but their concentration increased ∼10 times after chloramination while 9 new amines were produced (4 aromatic amines and 5 N-nitrosamines). Within subsequent treatments, there were no significant changes in the amine levels, although the concentrations of 2-nitroaniline, N-nitrosodimethylamine and N-nitrosodiethylamine increased slightly within the distribution system. Eleven of the 24 amines studied were undetected either in the raw and in the treatment plant samples analysed. There is an important difference in the behaviour of the aromatic amines and N-nitrosamines with respect to water temperature and rainfall events. Amine concentrations were higher in winter due to low water temperatures, this effect being more noticeable for N-nitrosamines. Aromatic amines were detected at their highest concentrations (especially 3,4-dichloroaniline and 2-nitroaniline) in treated water after rainfall events. These results may be explained by the increase in the levels of amine precursors (pesticides and their degradation products) in raw water since the rainfall facilitated the transport of these compounds from soil which was previously contaminated as a result of intensive agricultural practices. Copyright © 2012 Elsevier Ltd. All rights reserved.

Design and assembly of new non-viral RNAi delivery agents by microwave-assisted quaternization (MAQ) of tertiary amines

PubMed Central

Ghosh, Animesh; Mukherjee, Koushik; Jiang, Xinpeng; Zhou, Ying; McCarroll, Joshua; Qu, James; Swain, Pamela M.; Baigude, Huricha; Rana, Tariq M.

2010-01-01

RNA interference (RNAi), a gene-silencing phenomenon whereby double-stranded RNA (dsRNA) triggers the sequence-specific degradation of homologous mRNA. RNAi has been quickly and widely applied to discover gene functions and holds great potential to provide a new class of therapeutic agents. However, new chemistry and delivery approaches are greatly needed to silence disease-causing genes without toxic effects. We reasoned that conjugation of the cholesterol moiety to cationic lipids would enhance RNAi efficiencies and lower the toxic effects of lipid-mediated RNAi delivery. Here, we report the first design and synthesis of new cholesterol-conjugated cationic lipids for RNAi delivery using microwave-assisted quaternization (MAQ) of tertiary amines. This strategy can be employed to develop new classes of non-viral gene delivery agents under safe and fast reaction conditions. PMID:20722369

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

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. Copyright © 2012 Elsevier Ltd. All rights reserved.

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.

Landscape review of current HIV 'kick and kill' cure research - some kicking, not enough killing.

PubMed

Thorlund, Kristian; Horwitz, Marc S; Fife, Brian T; Lester, Richard; Cameron, D William

2017-08-29

Current antiretroviral therapy (ART) used to treat human immunodeficiency virus (HIV) patients is life-long because it only suppresses de novo infections. Recent efforts to eliminate HIV have tested the ability of a number of agents to reactivate ('Kick') the well-known latent reservoir. This approach is rooted in the assumption that once these cells are reactivated the host's immune system itself will eliminate ('Kill') the virus. While many agents have been shown to reactivate large quantities of the latent reservoir, the impact on the size of the latent reservoir has been negligible. This suggests that the immune system is not sufficient to eliminate reactivated reservoirs. Thus, there is a need for more emphasis on 'kill' strategies in HIV cure research, and how these might work in combination with current or future kick strategies. We conducted a landscape review of HIV 'cure' clinical trials using 'kick and kill' approaches. We identified and reviewed current available clinical trial results in human participants as well as ongoing and planned clinical trials. We dichotomized trials by whether they did not include or include a 'kill' agent. We extracted potential reasons why the 'kill' is missing from current 'kick and kill' strategies. We subsequently summarized and reviewed current 'kill' strategies have entered the phase of clinical trial testing in human participants and highlighted those with the greatest promise. The identified 'kick' trials only showed promise on surrogate measures activating latent T-cells, but did not show any positive effects on clinical 'cure' measures. Of the 'kill' agents currently being tested in clinical trials, early results have shown small but meaningful proportions of participants remaining off ART for several months with broadly neutralizing antibodies, as well as agents for regulating immune cell responses. A similar result was also recently observed in a trial combining a conventional 'kick' with a vaccine immune booster ('kill'). While an understanding of the efficacy of each individual component is crucial, no single 'kick' or 'kill' agent is likely to be a fully effective cure. Rather, the solution is likely found in a combination of multiple 'kick and kill' interventions.

Poly(Amide-imide) Aerogel Materials Produced via an Ice Templating Process

PubMed Central

Gawryla, Matthew D.; Arndt, Eric M.

2018-01-01

Low density composites of sodium montmorillonite and poly(amide-imide) polymers have been created using an ice templating method, which serves as an alternative to the often-difficult foaming of high temperature/high performance polymers. The starting polymer was received in the poly(amic acid) form which can be cured using heat, into a water insoluble amide-imide copolymer. The resulting materials have densities in the 0.05 g/cm3 range and have excellent mechanical properties. Using a tertiary amine as a processing aid provides for lower viscosity and allows more concentrated polymer solutions to be used. The concentration of the amine relative to the acid groups on the polymer backbone has been found to cause significant difference in the mechanical properties of the dried materials. The synthesis and characterization of low density versions of two poly(amide-imide) polymers and their composites with sodium montmorillonite clay are discussed in the present work. PMID:29401663

Poly(Amide-imide) Aerogel Materials Produced via an Ice Templating Process.

PubMed

Gawryla, Matthew D; Arndt, Eric M; Sánchez-Soto, Miguel; Schiraldi, David A

2018-02-03

Low density composites of sodium montmorillonite and poly(amide-imide) polymers have been created using an ice templating method, which serves as an alternative to the often-difficult foaming of high temperature/high performance polymers. The starting polymer was received in the poly(amic acid) form which can be cured using heat, into a water insoluble amide-imide copolymer. The resulting materials have densities in the 0.05 g/cm³ range and have excellent mechanical properties. Using a tertiary amine as a processing aid provides for lower viscosity and allows more concentrated polymer solutions to be used. The concentration of the amine relative to the acid groups on the polymer backbone has been found to cause significant difference in the mechanical properties of the dried materials. The synthesis and characterization of low density versions of two poly(amide-imide) polymers and their composites with sodium montmorillonite clay are discussed in the present work.

Differences in interfacial bond strengths of graphite fiber-epoxy resin composites

NASA Technical Reports Server (NTRS)

Needles, H. L.

1985-01-01

The effect of epoxy-size and degree of cure on the interfacial bonding of an epoxy-amine-graphite fiber composite system is examined. The role of the fiber-resin interface in determining the overall mechanical properties of composites is poorly understood. A good interfacial adhesive bond is required to achieve maximum stress transfer to the fibers in composites, but at the same time some form of energy absorbing interfacial interaction is needed to achieve high fracture toughening. The incompatibility of these two processes makes it important to understand the nature and basic factors involved at the fiber-resin interface as stress is applied. The mechanical properties including interlaminar shear values for graphite fiber-resin composites are low compared to glass and boron-resin composites. These differences have been attributed to poor fiber-matrix adhesion. Graphite fibers are commonly subjected to post-treatments including application of organic sizing in order to improve their compatibility with the resin matrix and to protect the fiber tow from damage during processing and lay-up. In such processes, sized graphite fiber tow is impregnated with epoxy resin and then layed-up i nto the appropriate configuration. Following an extended ambient temperature cure, the graphite-resin composite structure is cured at elevated temperature using a programmed temperature sequence to cure and then cool the product.

Palladium-catalysed transannular C-H functionalization of alicyclic amines

NASA Astrophysics Data System (ADS)

Topczewski, Joseph J.; Cabrera, Pablo J.; Saper, Noam I.; Sanford, Melanie S.

2016-03-01

Discovering pharmaceutical candidates is a resource-intensive enterprise that frequently requires the parallel synthesis of hundreds or even thousands of molecules. C-H bonds are present in almost all pharmaceutical agents. Consequently, the development of selective, rapid and efficient methods for converting these bonds into new chemical entities has the potential to streamline pharmaceutical development. Saturated nitrogen-containing heterocycles (alicyclic amines) feature prominently in pharmaceuticals, such as treatments for depression (paroxetine, amitifadine), diabetes (gliclazide), leukaemia (alvocidib), schizophrenia (risperidone, belaperidone), malaria (mefloquine) and nicotine addiction (cytisine, varenicline). However, existing methods for the C-H functionalization of saturated nitrogen heterocycles, particularly at sites remote to nitrogen, remain extremely limited. Here we report a transannular approach to selectively manipulate the C-H bonds of alicyclic amines at sites remote to nitrogen. Our reaction uses the boat conformation of the substrates to achieve palladium-catalysed amine-directed conversion of C-H bonds to C-C bonds on various alicyclic amine scaffolds. We demonstrate this approach by synthesizing new derivatives of several bioactive molecules, including varenicline.

STUDY OF THE RADIATION-PROTECTIVE ACTION OF SOME PROTECTIVE MATERIALS ON PROTOZOA (in Russian)

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

Graevskii, E.Ya.; Nekrasova, I.V.; Shul'mina, A.I.

1962-01-01

The behavior of thiourea derivatives as protective agents during the irradiation of protozoa were investigated together with heroin which possesses a known ability of reducing the radiation reaction of tissues in aqueous solution. It was attempted to determine the effect of toxicity of the radiolytic products and of the medium itself. Cultures of Paramaecium caudatum were used for determining the ef fect of aminoethylisothiuronium bromide hydrobromide, cysteine amine, cystine amine, and heroin. The H/sub 2/Osub 2/ formed during the radiolysis was determined by titration with KMnO/sub 4/. After exposure of the protozea to 100 kr, a protective action was notedmore » by the aminoethylisothiuronium bromide hydrobromide and cystine amine. The lack of efficiency of the cysteine amine is due to its decomposition by radiolysis. (TTT)« less

Phenylethynyl terminated imide oligomers

NASA Technical Reports Server (NTRS)

Hergenrother, Paul M. (Inventor); Bryant, Robert G. (Inventor); Jensen, Brian J. (Inventor); Havens, Stephen J. (Inventor)

1994-01-01

Four phenylethynyl amine compounds - 3 and 4-aminophenoxy-4'-phenylethynylbenzophenone, and 3 and 4-amino-4'-phenylethynylbenzophenone - were readily prepared and were used to endcap imide oligomers. Phenylethynyl-terminated amide acid oligomers and phenylethynyl-terminated imide oligomers with various molecular weights and compositions were prepared and characterized. These oligomers were cured at 300 to 400 C to provide crosslinked polyimides with excellent solvent resistance, high strength and modulus, and good high temperature properties. Adhesive panels, composites, films, and moldings from these phenylethynyl terminated imide oligomers gave excellent mechanical performance.

Phenylethynyl terminated imide oligomers

NASA Technical Reports Server (NTRS)

Hergenrother, Paul M. (Inventor); Bryant, Robert G. (Inventor); Jensen, Brian J. (Inventor); Havens, Stephen J. (Inventor)

1995-01-01

Four phenylethynyl amine compounds - 3 and 4-aminophenoxy-4'-phenylethynylbenzophenone, and 3 and 4-amino-4'-phenylethynylbenzophenone - were readily prepared and were used to endcap imide oligomers. Phenylethynyl-terminated amide acid oligomers and phenylethynyl-terminated imide oligomers with various molecular weights and compositions were prepared and characterized. These oligomers were cured at 300 to 400 C to provide crosslinked polyimides with excellent solvent resistance, high strength and modulus, and good high temperature properties. Adhesive panels, composites, films, and moldings from these phenylethynyl terminated imide oligomers gave excellent mechanical performance.

Isomer effects on polyimide properties

NASA Technical Reports Server (NTRS)

Stump, B. L.

1975-01-01

Polyimide polymers which are thermally stable and processable are developed. The addition of alkyl substituents to an aromatic ring in the polymer backbone is examined along with polyimide precursor amines containing functional groups that allow for post-cure crosslinking. The synthesis of key monomers is reported, including 2,4,6-tris (m-aminobenzyl) 1,3,5-trimethyl benzene and 2,4,6-tris (p-aminobenzyl) 1,3,5-trimethyl benzene. The preparation of a key monomer, 2,5,3-triamino benzophenone, is reported.

Whole-cell bioluminescent bioreporter sensing of foodborne toxicants

NASA Astrophysics Data System (ADS)

Ripp, Steve A.; Applegate, Bruce M.; Simpson, Michael L.; Sayler, Gary S.

2001-03-01

The presence of biologically derived toxins in foods is of utmost significance to food safety and human health concerns. Biologically active amines, referred to as biogenic amines, serve as a noteworthy example, having been implicated as the causative agent in numerous food poisoning episodes. Of the various biogenic amines encountered, histamine, putrescine, cadaverine, tyramine, tryptamine, beta-phenylethylamine, spermine, and spermidine are considered to be the most significant, and can be used as hygienic-quality indicators of food. Biogenic amines can be monitored using whole-cell bioluminescent bioreporters, which represent a family of genetically engineered microorganisms that generate visible light in response to specific chemical or physical agents in their environment. The light response occurs due to transcriptional activation of a genetically incorporated lux cassette, and can be measured using standard photomultiplier devices. We have successfully engineered a lux-based bioreporter capable of detecting and monitoring the biogenic amine beta-phenylethylamine. This research represents a biologically-based sensor technology that can be readily integrated into Hazard Analysis Critical Control Point programs to provide a rugged monitoring regime that can be uniformly applied for field-based and in-house laboratory quality control analyses. Since the bioreporter and biosensing elements are completely self-contained within the sensor design, this system provides ease of use, with operational capabilities realized by simply combining the food sample with the bioreporter and allowing the sensor to process the ensuing bioluminescent signal and communicate the results. The application of this technology to the critically important issue of food safety and hygienic quality represents a novel method for detecting, monitoring, and preventing biologically active toxins in food commodities.

In situ Synthesis of Metal Nanoparticle Embedded Free Standing Multifunctional PDMS Films.

PubMed

Goyal, Anubha; Kumar, Ashavani; Patra, Prabir K; Mahendra, Shaily; Tabatabaei, Salomeh; Alvarez, Pedro J J; John, George; Ajayan, Pulickel M

2009-07-01

We demonstrate a simple one-step method for synthesizing noble metal nanoparticle embedded free standing polydimethylsiloxane (PDMS) composite films. The process involves preparing a homogenous mixture of metal salt (silver, gold and platinum), silicone elastomer and the curing agent (hardener) followed by curing. During the curing process, the hardener crosslinks the elastomer and simultaneously reduces the metal salt to form nanoparticles. This in situ method avoids the use of any external reducing agent/stabilizing agent and leads to a uniform distribution of nanoparticles in the PDMS matrix. The films were characterized using UV-Vis spectroscopy, transmission electron microscopy and X-ray photoemission spectroscopy. The nanoparticle-PDMS films have a higher Young's modulus than pure PDMS films and also show enhanced antibacterial properties. The metal nanoparticle-PDMS films could be used for a number of applications such as for catalysis, optical and biomedical devices and gas separation membranes. Copyright © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

The effects of light curing units and environmental temperatures on C 000000000000 000000000000 000000000000 111111111111 000000000000 111111111111 000000000000 000000000000 000000000000 C conversion of commercial and experimental bonding agents.

PubMed

Jafarzadeh-Kashi, Tahereh Sadat; Erfan, Mohmmad; Kalbasi, Salmeh; Ghadiri, Malihe; Rakhshan, Vahid

2014-10-01

Polymerization of bonding agents (BA) is a critical factor in determining the success of bonded restorations. We aimed to assess the effects of two light curing units and two temperatures on the extent of polymerization (EP) of a commercial BA and an experimental BA. Forty BA specimens were randomly divided into 8 subgroups of n = 5 to compare the polymerization of two BAs (experimental/Scotchbond) based on the variables: temperature (23/37 °C) and light-curing unit (quartz-tungsten-halogen/light-emitting diode). The EP (%) was measured using differential scanning calorimetry, and analyzed using the t-test, two- and three-way analyses of variance (ANOVA), and the Bonferroni test (α = 0.05). There were significant differences between the EP results between the two BAs (P = 0.012) and due to the different temperatures (P = 0.001), but not between the different light-curing units (P = 0.548). The interaction between BA and temperature was significant (P < 0.001). The other interactions were nonsignificant. The two light-curing units had similar effects on the EP. The EP values were better when curing was performed at human body temperature.

Direct and indirect hyperpolarisation of amines using parahydrogen† †Electronic supplementary information (ESI) available: Full experimental procedures, characterisation data and example spectra. See DOI: 10.1039/c8sc00526e

PubMed Central

Iali, Wissam; Rayner, Peter J.; Alshehri, Adel; Holmes, A. Jonathan.; Ruddlesden, Amy J.

2018-01-01

Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) are two widely used techniques for the study of molecules and materials. Hyperpolarisation methods, such as Signal Amplification By Reversible Exchange (SABRE), turn typically weak magnetic resonance responses into strong signals. In this article we detail how it is possible to hyperpolarise the 1H, 13C and 15N nuclei of a range of amines. This involved showing how primary amines form stable but labile complexes of the type [Ir(H)2(IMes)(amine)3]Cl that allow parahydrogen to relay its latent polarisation into the amine. By optimising the temperature and parahydrogen pressure a 1000-fold per proton NH signal gain for deuterated benzylamine is achieved at 9.4 T. Additionally, we show that sterically hindered and electron poor amines that bind poorly to iridium can be hyperpolarised by either employing a co-ligand for complex stabilisation, or harnessing the fact that it is possible to exchange hyperpolarised protons between amines in a mixture, through the recently reported SABRE-RELAY method. These chemical refinements have significant potential to extend the classes of agent that can be hyperpolarised by readily accessible parahydrogen. PMID:29780498

Ionic liquids as silica deactivating agents in gas chromatography for direct analysis of primary amines in water.

PubMed

Krzyżaniak, Agnieszka; Weggemans, Wilko; Schuur, Boelo; de Haan, André B

2011-12-16

Analysis of primary amines in aqueous samples remains a challenging analytical issue. The preferred approach by gas chromatography is hampered by interactions of free silanol groups with the highly reactive amine groups, resulting in inconsistent measurements. Here, we report a method for direct analysis of aliphatic amines and diamines in aqueous samples by gas chromatography (GC) with silanol deactivation using ionic liquids (ILs). ILs including trihexyl(tetradecyl)phosphonium bis 2,4,4-(trimethylpentyl)phosphinate (Cyphos IL-104), 1-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide [pmim][Tf(2)N] and N″-ethyl-N,N,N',N'-tetramethylguanidinium tris(pentafluoroethyl)trifluorophosphate [etmg][FAP] were tested as deactivating media for the GC liner. Solutions of these ILs in methanol were injected in the system prior to the analysis of primary amines. Butane-1,4-diamine (putrescine, BDA) was used as a reference amine. The best results were obtained using the imidazolium IL [pmim][Tf(2)N]. With this deactivator, excellent reproducibility of the analysis was achieved, and the detection limit of BDA was as low as 1mM. The applicability of the method was proven for the analysis of two different primary amines (C4-C5) and pentane-1,5-diamine. Copyright © 2011 Elsevier B.V. All rights reserved.

Transarterial onyx embolization of cranial dural arteriovenous fistulas: long-term follow-up.

PubMed

Chandra, R V; Leslie-Mazwi, T M; Mehta, B P; Yoo, A J; Rabinov, J D; Pryor, J C; Hirsch, J A; Nogueira, R G

2014-09-01

Endovascular therapy with liquid embolic agents is a common treatment strategy for cranial dural arteriovenous fistulas. This study evaluated the long-term effectiveness of transarterial Onyx as the single embolic agent for curative embolization of noncavernous cranial dural arteriovenous fistulas. We performed a retrospective review of 40 consecutive patients with 41 cranial dural arteriovenous fistulas treated between March 2006 and June 2012 by using transarterial Onyx embolization with intent to cure. The mean age was 57 years; one-third presented with intracranial hemorrhage. Most (85%) had cortical venous drainage. Once angiographic cure was achieved, long-term treatment effectiveness was assessed with DSA and clinical follow-up. Forty-nine embolization sessions were performed; 85% of cranial dural arteriovenous fistulas were treated in a single session. The immediate angiographic cure rate was 95%. The permanent neurologic complication rate was 2% (mild facial palsy). Thirty-five of the 38 patients with initial cure underwent short-term follow-up DSA (median, 4 months). The short-term recurrence rate was only 6% (2/35). All patients with occlusion at short-term DSA undergoing long-term DSA (median, 28 months) had durable occlusion. No patient with long-term clinical follow-up (total, 117 patient-years; median, 45 months) experienced hemorrhage. Transarterial embolization with Onyx as the single embolic agent results in durable long-term cure of noncavernous cranial dural arteriovenous fistulas. Recurrence rates are low on short-term follow-up, and all patients with angiographic occlusion on short-term DSA follow-up have experienced a durable long-term cure. Thus, angiographic cure should be defined at short-term follow-up angiography instead of at the end of the final embolization session. Finally, long-term DSA follow-up may not be necessary if occlusion is demonstrated on short-term angiographic follow-up. © 2014 by American Journal of Neuroradiology.

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

Doll, D.C.; Ringenberg, Q.S.; Yarbro, J.W.

Although cancer during pregnancy is infrequent, its management is difficult for patients, their families, and their physicians. When termination of the pregnancy is unacceptable, decisions regarding the use of irradiation and chemotherapy are complicated by the well-known high risks of abortion and fetal malformation. This risk is concentrated in the first trimester and varies with the choice of chemotherapeutic agents or combinations of agents. There is only minimal evidence of increased risk of malformation or abortion in the second or third trimester. Recent progress in cancer therapy has made cure a reasonable goal, and for some malignant neoplasms, cure ismore » still possible even when initial therapy is modified or delayed. When cure is a reasonable goal, curative therapy should not be compromised by modification or delay. When treatment for cure or significant palliation is not possible, however, the goal should shift to protection of the fetus from damage by the injudicious use of teratogenic cancer therapy. This report will review the available data that may assist in these difficult decisions. 114 references.« less

Complete cure of persistent virus infections by antiviral siRNAs.

PubMed

Saulnier, Aure; Pelletier, Isabelle; Labadie, Karine; Colbère-Garapin, Florence

2006-01-01

Small interfering RNAs (siRNAs) have been developed as antiviral agents for mammalian cells. The capacity of specific siRNAs to prevent virus infections has been demonstrated, and there is evidence that these new antiviral agents could have a partial therapeutic effect a few days after infection. We investigated the possibility of curing a persistent infection, several months after becoming established, using an in vitro model of persistent poliovirus (PV) infection in HEp-2 cells. Despite high virus titers and the presence of PV mutants, repeated treatment with a mixture of two siRNAs targeting both noncoding and coding regions, one of them in a highly conserved region, resulted in the complete cure of the majority of persistently infected cultures. No escape mutants emerged in treated cultures. The antiviral effect of specific siRNAs, consistent with a mechanism of RNA interference, correlated with a decrease in the amount of viral RNA, until its complete disappearance, resulting in cultures cured of virions and viral RNA.

Release Of Gaseous NH(3) From NH(4)CIO(4) By HTPB-Bonding Agents

NASA Technical Reports Server (NTRS)

Mccomb, James C.

1993-01-01

Report describes experimental study of rate of generation of ammonia and total amount of ammonia generated by chemical reactions between bonding agents and grains of ammonium perchlorate in solid rocket propellants. Also provides insight into mechanisms of chemical reactions between several types of organic amines with solid ammonium perchlorate.

Precursors to radiopharmaceutical agents for tissue imaging

DOEpatents

Srivastava, Prem C.; Knapp, Jr., Furn F.

1988-01-01

A class of radiolabeled compounds to be used in tissue imaging that exhibits rapid brain uptake, good brain:blood radioactivity ratios, and long retention times. The imaging agents are more specifically radioiodinated aromatic amines attached to dihydropyridine carriers, that exhibit heart as well as brain specificity. In addition to the radiolabeled compounds, classes of compounds are also described that are used as precursors and intermediates in the preparation of the imaging agents.

Microenvironment-Sensitive Multimodal Contrast Agent for Prostate Cancer Diagnosis

DTIC Science & Technology

2015-10-01

with a biopolymer (i.e. starch ) to improve biocompatibility, and tagged with prostate cancer-targeting ligands. A significant challenge to translation... starch coating of 50 nm and 100 nm SPIONs was crosslinked and coated with amine groups, and then functionalized with NHS-polyethylene glycol (PEG) of...varying molecular weight (i.e., 2k, 5k or 20k Da) as shown in Scheme 1. Scheme 1. Surface modification of starch -coated SPIONs into aminated and

Microenvironment Sensitive Multimodal Contrast Agent for Prostate Cancer Diagnosis

DTIC Science & Technology

2016-10-01

coated with a biopolymer (i.e. starch ) to improve biocompatibility, and tagged with prostate cancer-targeting ligands. A significant challenge to...The starch coating of 50 nm and 100 nm SPIONs was crosslinked and coated with amine groups, and then functionalized with NHS-polyethylene glycol (PEG...of varying molecular weight (i.e., 2k, 5k or 20k Da) as shown in Scheme 1. Scheme 1. Surface modification of starch -coated SPIONs into aminated

Polyacrolein microspheres

NASA Technical Reports Server (NTRS)

Rembaum, Alan (Inventor)

1983-01-01

Microspheres of acrolein homopolymers and co-polymer with hydrophillic comonomers such as methacrylic acid and/or hydroxyethylmethacrylate are prepared by cobalt gamma irradiation of dilute aqueous solutions of the monomers in presence of suspending agents, especially alkyl sulfates such as sodium dodecyl sulfate. Amine or hydroxyl modification is achieved by forming adducts with diamines or alkanol amines. Carboxyl modification is effected by oxidation with peroxides. Pharmaceuticals or other aldehyde reactive materials can be coupled to the microspheres. The microspheres directly form antibody adducts without agglomeration.

Polyacrolein microspheres

NASA Technical Reports Server (NTRS)

Rembaum, Alan (Inventor)

1986-01-01

Microspheres of acrolein homopolymers and copolymer with hydrophillic comonomers such as methacrylic acid and/or hydroxyethylmethacrylate are prepared by cobalt gamma irradiation of dilute aqueous solutions of the monomers in presence of suspending agents, especially alkyl sulfates such as sodium dodecyl sulfate. Amine or hydroxyl modification is achieved by forming adducts with diamines or alkanol amines. Carboxyl modification is effected by oxidation with peroxides. Pharmaceuticals or other aldehyde reactive materials can be coupled to the microspheres. The microspheres directly form antibody adducts without agglomeration.

Polyacrolein microspheres

NASA Technical Reports Server (NTRS)

Rembaum, Alan (Inventor)

1987-01-01

Microspheres of acrolein homopolymers and copolymer with hydrophillic comonomers such as methacrylic acid and/or hydroxyethylmethacrylate are prepared by cobalt gamma irradiation of dilute aqueous solutions of the monomers in presence of suspending agents, especially alkyl sulfates such as sodium dodecyl sulfate. Amine or hydroxyl modification is achieved by forming adducts with diamines or alkanol amines. Carboxyl modification is effected by oxidation with peroxides. Pharmaceuticals or other aldehyde reactive materials can be coupled to the microspheres. The microspheres directly form antibody adducts without agglomeration.

A Systems Approach to Depaint Chemistry

DTIC Science & Technology

2009-02-01

continuous colored film by curing through solvent evaporation, oxidation, catylization or other means. – Vehicle: Film former, binder, resin or polymer...impart large changes in properties. – Suspending agents – Driers – Anti-Skinning Agents – Wetting Agents – Anti- Foaming Agents – Coalescing Agents ...volatile stripper inside the coating. Paint Release Agent Coating Removal Mechanism Zone1: PRA Layer Zone2: PRA Initial Permeation into coating system Epoxy

Epoxy Pipelining Composition and Method of Manufacture.

DTIC Science & Technology

1994-12-14

exemplary curing agent blend was prepared by reacting azelaic acid 3 (nonanedioic acid ), hexanoic acid , triethylene tetramine 4 (NH 2CH2CH2NHCH2CH2NHCH2CH...2NH2; TETA) and benzyl alcohol. The exemplary 5 curing agent blend was prepared as follows: 6 (a) Azelaic acid (solid; 90.9 gm.; 0.483 moles; C 9H 16 0...heated to 230 ’C over 10 - 20 11 minutes in a silicone oil bath. As the azelaic acid melted into a liquid, the 12 reaction mixture was stirred using a

Characterization of coagulase-negative staphylococci isolated from Spanish dry cured meat products.

PubMed

Landeta, G; Curiel, J A; Carrascosa, A V; Muñoz, R; de las Rivas, B

2013-03-01

Technological and safety-related properties were analyzed in a coagulase-negative staphylococci (CNS) collection isolated from Spanish dry-cured meat products in order to use them as starter cultures. The highest nitrate reductase and proteolytic activity was showed by Staphylococcus carnosus and Staphylococcus equorum. Only a few strains were able to form biofilms and the presence of the ica gene was analyzed on them. In relation to antibiotic resistance, all S. carnosus and most of the S. equorum strains were sensitive to the antibiotics tested and the presence of the blaZ gene in the β-lactamic resistant strains was studied. Biogenic amines were produced by 25% of the strains analyzed being all the S. carnosus strains tyramine producers. Taking into account the studied properties, two S. equorum strains could be selected as adequate and safe potential starter cultures for the elaboration of meat products. Copyright © 2012 Elsevier Ltd. All rights reserved.

Eco-friendly synthesis of size-controllable amine-functionalized graphene quantum dots with antimycoplasma properties

NASA Astrophysics Data System (ADS)

Jiang, Feng; Chen, Daiqin; Li, Ruimin; Wang, Yucheng; Zhang, Guoqiang; Li, Shumu; Zheng, Junpeng; Huang, Naiyan; Gu, Ying; Wang, Chunru; Shu, Chunying

2013-01-01

Size-controllable amine-functionalized graphene quantum dots (GQDs) are prepared by an eco-friendly method with graphene oxide sheets, ammonia and hydrogen peroxide as starting materials. Using a Sephadex G-25 gel column for fine separation, for the first time we obtain GQDs with either single or double layers. By atomic force microscopy characterization, we confirm that hydrogen peroxide and ammonia play a synergistic role on graphene oxide (GO), in which the former cuts the GO into small pieces and the latter passivates the active surface to give amine-modified GQDs. Due to the low cytotoxicity and excellent biocompatibility of the obtained amine-functionalized GQDs, besides the multiwavelength imaging properties of GQDs, for the first time we find that this kind of GQD exhibits good antimycoplasma properties. Given the superior antimycoplasma effect of the GQDs and their eco-friendly mass production with low cost, these new GQDs may offer opportunities for the development of new antimycoplasma agents, thus extending their widespread application in biomedicine.Size-controllable amine-functionalized graphene quantum dots (GQDs) are prepared by an eco-friendly method with graphene oxide sheets, ammonia and hydrogen peroxide as starting materials. Using a Sephadex G-25 gel column for fine separation, for the first time we obtain GQDs with either single or double layers. By atomic force microscopy characterization, we confirm that hydrogen peroxide and ammonia play a synergistic role on graphene oxide (GO), in which the former cuts the GO into small pieces and the latter passivates the active surface to give amine-modified GQDs. Due to the low cytotoxicity and excellent biocompatibility of the obtained amine-functionalized GQDs, besides the multiwavelength imaging properties of GQDs, for the first time we find that this kind of GQD exhibits good antimycoplasma properties. Given the superior antimycoplasma effect of the GQDs and their eco-friendly mass production with low cost, these new GQDs may offer opportunities for the development of new antimycoplasma agents, thus extending their widespread application in biomedicine. Electronic supplementary information (ESI) available: Experimental details and additional characterization data. See DOI: 10.1039/c2nr33191h

Nanoparticle strategies for cancer therapeutics: Nucleic acids, polyamines, bovine serum amine oxidase and iron oxide nanoparticles (Review).

PubMed

Agostinelli, Enzo; Vianello, Fabio; Magliulo, Giuseppe; Thomas, Thresia; Thomas, T J

2015-01-01

Nanotechnology for cancer gene therapy is an emerging field. Nucleic acids, polyamine analogues and cytotoxic products of polyamine oxidation, generated in situ by an enzyme-catalyzed reaction, can be developed for nanotechnology-based cancer therapeutics with reduced systemic toxicity and improved therapeutic efficacy. Nucleic acid-based gene therapy approaches depend on the compaction of DNA/RNA to nanoparticles and polyamine analogues are excellent agents for the condensation of nucleic acids to nanoparticles. Polyamines and amine oxidases are found in higher levels in tumours compared to that of normal tissues. Therefore, the metabolism of polyamines spermidine and spermine, and their diamine precursor, putrescine, can be targets for antineoplastic therapy since these naturally occurring alkylamines are essential for normal mammalian cell growth. Intracellular polyamine concentrations are maintained at a cell type-specific set point through the coordinated and highly regulated interplay between biosynthesis, transport, and catabolism. In particular, polyamine catabolism involves copper-containing amine oxidases. Several studies showed an important role of these enzymes in developmental and disease-related processes in animals through the control of polyamine homeostasis in response to normal cellular signals, drug treatment, and environmental and/or cellular stress. The production of toxic aldehydes and reactive oxygen species (ROS), H2O2 in particular, by these oxidases suggests a mechanism by which amine oxidases can be exploited as antineoplastic drug targets. The combination of bovine serum amine oxidase (BSAO) and polyamines prevents tumour growth, particularly well if the enzyme has been conjugated with a biocompatible hydrogel polymer. The findings described herein suggest that enzymatically formed cytotoxic agents activate stress signal transduction pathways, leading to apoptotic cell death. Consequently, superparamagnetic nanoparticles or other advanced nanosystem based on directed nucleic acid assemblies, polyamine-induced DNA condensation, and bovine serum amine oxidase may be proposed for futuristic anticancer therapy utilizing nucleic acids, polyamines and BSAO. BSAO based nanoparticles can be employed for the generation of cytotoxic polyamine metabolites.

Trowelable ablative coating composition and method of use

NASA Technical Reports Server (NTRS)

Headrick, Stephen E. (Inventor); Hill, Roger L. (Inventor)

1989-01-01

A trowelable ablative coating composition is disclosed. The composition comprises an epoxy resin, an amide curing agent, glass microspheres and ground cork. A method for protecting a substrate is also disclosed. The method comprises applying the trowelable ablative coating discussed above to a substrate and curing the coating composition.

Trowelable ablative coating composition and method of use

NASA Technical Reports Server (NTRS)

Headrick, Stephen E. (Inventor); Hill, Roger L. (Inventor)

1988-01-01

A trowelable ablative coating composition is disclosed. The composition comprises an epoxy resin, an amide curing agent, glass microspheres and ground cork. A method for protecting a substrate is also disclosed. The method comprises applying the trowelable ablative coating discussed above to a substrate and curing the coating composition.

Elastomer toughened polyimide adhesives. [bonding metal and composite material structures for aircraft and spacecraft

NASA Technical Reports Server (NTRS)

St.clair, A. K.; St.clair, T. L. (Inventor)

1985-01-01

A rubber-toughened, addition-type polyimide composition is disclosed which has excellent high temperature bonding characteristics in the fully cured state and improved peel strength and adhesive fracture resistance physical property characteristics. The process for making the improved adhesive involves preparing the rubber-containing amic acid prepolymer by chemically reacting an amine-terminated elastomer and an aromatic diamine with an aromatic dianhydride with which a reactive chain stopper anhydride has been mixed, and utilizing solvent or mixture of solvents for the reaction.

Isomer effects on polyimide properties

NASA Technical Reports Server (NTRS)

Stump, B. L.

1975-01-01

The effect of structure variation on the solubility and glass-transition temperature of polyimide polymers is investigated. The addition of alkyl substituents to an aromatic ring in the polymer molecule, the reduction in the number of imide rings per average polymer chain-length, and a variation in the symmetry of the polymer molecule are studied. The synthesis of key intermediates for the preparation of the monomers required in this investigation is reported along with progress made in the synthesis of polyimide-precursor amines that contain functional groups to allow for post-cure cross-linking.

Guanidine hydrochloride embedded polyurethanes as antimicrobial and absorptive wound dressing membranes with promising cytocompatibility.

PubMed

Sahraro, Maryam; Yeganeh, Hamid; Sorayya, Marziyeh

2016-02-01

Preparation and assessments of novel absorptive wound dressing materials with efficient antimicrobial activity as well as very good cytocompatibility were described in this work. An amine terminated poly(hexamethylene guanidine hydrochloride) was prepared and used as curing agent of different epoxy-terminated polyurethane prepolymers. The structures of prepared materials were elucidated by evaluation of their (1)H NMR and FTIR spectra. The recorded tensile strength of membranes confirmed the excellent dimensional stability of the film type dressings even at fully hydrated conditions. Therefore, these dressings could protect the wound bed from external forces during the healing period. The structurally optimized dressing membranes could preserve the desired moist environment over the wounded area, as a result of their balanced equilibrium, water absorption and water vapor transmission rate. Therefore, a very good condition for stimulation of self-healing of wound bed was attained. Also, owing to the presence of guanidine hydrochloride moieties embedded into the structure of dressings, efficient antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans were detected. In vitro cytotoxicity assay of the prepared dressings revealed cytocompatibility of these materials against fibroblast cells. Therefore, they could support cell growth and proliferation at the wounded area. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

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. Copyright © 2016. Published by Elsevier B.V.

Geopolymer lightweight bricks manufactured from fly ash and foaming agent

NASA Astrophysics Data System (ADS)

Ibrahim, Wan Mastura Wan; Hussin, Kamarudin; Abdullah, Mohd Mustafa Al Bakri; Kadir, Aeslina Abdul

2017-04-01

This paper deals with the development of lightweight geopolymer bricks by using foaming agent and fly ash. The mix parameters analysed through a laboratory experiment with fix ratio of sodium silicate/sodium hydroxide solution mass ratio 2.5, fly ash/alkaline activator solution mass ratio 2.0, foaming agent/paste mass ratio 1:2 and molarity of sodium hydroxide solution used was 12M. Different curing temperature (Room Temperature, 60, 80) and foaming agent/water mass ratio (1:10 and 1:20) were studied. Compressive strength, density analysis, and water absorption has been investigated. The results show that the foamed geopolymer bricks with a lower foam/water mass ratio (1:10)and high curing temperature (80°C) leading to a better properties. Mixtures with a low density of around 1420 kg/m3 and a compressive strength of around 10 MPa were achieved.

Evaluation of several types of curing and protective materials for concrete : final report on part I : laboratory and outdoor exposure studies preliminary to field trials.

DOT National Transportation Integrated Search

1970-01-01

Concern for improving the durability of concrete has focused renewed attention on all aspects of concrete technology. Numerous proprietary products which are claimed to improve durability have been marketed as protective coatings, curing agents or co...

Study on Synthesis of Thoreau-modified 3, 5-Dimethyl-Thioltoluenediamine Used as Epoxy Resin Curing Agent and Its Performance

NASA Astrophysics Data System (ADS)

Peng, Yongli; Xiao, Wenzheng

2017-06-01

A novel curing agent Thoreau modified 3, 5-Dimethyl-thioltoluenediamine was synthesized and its molecular structure was characterized by FTIR and DSC. The curing kinetics of a high toughness and low volume shrinkage ratio epoxy system (modified DMTDA/DGEBA) was studied by differential scanning calorimetry (DSC) under noni so thermal conditions. The data were fitted to an order model and autocatalytic model respectively. The results indicate that in order model deviates significantly from experimental data. Malik’s method was used to prove that the curing kinetics of the system concerned follow single-step autocatalytic model, and a “single-point model-free” approach was employed to calculate meaningful kinetic parameters. The DSC curves derived from autocatalytic model gave satisfactory agreement with that of experiment in the range 5K/min∼25K/min. As the heating rate increased, the predicted DSC curves deviated from experimental curves, and the total exothermic enthalpy declined owing to the transition of competition relationship between kinetics control and diffusion control.

The use of fluoroepoxy compounds as adhesives to bond fluoroplastics without any surface treatment

NASA Technical Reports Server (NTRS)

Lee, Sheng Yen

1988-01-01

The use of fluoroepoxy compounds as adhesives to bond fluoroplastics was investigated. Fluoroepoxy compounds with a F-content higher than 46 percent were able to bond a highly fluorinated plastic such as Teflon PTFE (76 percent F) to give a respectable bond strength without any surface treatment. The advantage of the fluoroepoxy adhesive vanished when applied to a less fluorinated plastic such as Tefzel which contains 55 percent fluorine. Among the curing agents explored, octafluorooctamethylenediamine showed its potential as a cocuring agent for improving both the viscosity of the compound and the flexibility of the cured product.

Structure-Property Relationships of Bismaleimides

NASA Technical Reports Server (NTRS)

Tenteris-Noebe, Anita D.

1997-01-01

The purpose of this research was to control and systematically vary the network topology of bismaleimides through cure temperature and chemistry (addition of various coreactants) and subsequently attempt to determine structure-mechanical property relationships. Characterization of the bismaleimide structures by dielectric, rheological, and thermal analyses, and density measurements was subsequently correlated with mechanical properties such as modulus, yield strength, fracture energy, and stress relaxation. The model material used in this investigation was 4,4'-BismaleiMidodIphenyl methane (BMI). BMI was coreacted with either 4,4'-Methylene Dianiline (MDA), o,o'-diallyl bisphenol A (DABA) from Ciba Geigy, or Diamino Diphenyl Sulfone (DDS). Three cure paths were employed: a low- temperature cure of 140 C where chain extension should predominate, a high-temperature cure of 220 C where both chain extension and crosslinking should occur simultaneously, and a low-temperature (140 C) cure followed immediately by a high-temperature (220 C) cure where the chain extension reaction or amine addition precedes BMI homopolymerization or crosslinking. Samples of cured and postcured PMR-15 were also tested to determine the effects of postcuring on the mechanical properties. The low-temperature cure condition of BMI/MDA exhibited the highest modulus values for a given mole fraction of BMI with the modulus decreasing with decreasing concentration of BMI. The higher elastic modulus is the result of steric hindrance by unreacted BMI molecules in the glassy state. The moduli values for the high- and low/high-temperature cure conditions of BMI/MDA decreased as the amount of diamine increased. All the moduli values mimic the yield strength and density trends. For the high-temperature cure condition, the room- temperature modulus remained constant with decreasing mole fraction of BMT for the BMI/DABA and BMI/DDS systems. Postcuring PMR-15 increases the modulus over that of the cured material even though density values of cured and postcured PMR were essentially the same. Preliminary results of a continuous and intermittent stress relaxation experiment for BMI:MDA in a 2:1 molar ratio indicate that crosslinking is occurring when the sample is in the undeformed state. Computer simulation of properties such as density, glass transition temperature, and modulus for the low- temperature cure conditions of BMI/MDA and BMI/DABA were completed. The computer modeling was used to help further understand and confirm the structure characterization results. The simulations correctly predicted the trends of these properties versus mole fraction BMI and were extended to other BMI/diamine systems.

Vitamine--vitamin. The early years of discovery.

PubMed

Rosenfeld, L

1997-04-01

In 1905, Cornelius Adrianus Pekelharing found that animals fed purified proteins, carbohydrates, fats, inorganic salts, and water would thrive only if small amounts of milk were added to the diet. He concluded that the milk contained some unrecognized substance that in very small quantities was necessary for normal growth and maintenance. In 1911, Casimir Funk isolated a concentrate from rice polishings that cured polyneuritis in pigeons. He named the concentrate "vitamine" because it appeared to be vital to life and because it was probably an amine. Although the concentrate and other "accessory food substances" were not amines, the name stuck, but the final "e" was dropped. In 1913 two groups discovered a "fat-soluble" accessory food substance. Initially believed to be a single vitamin, two separate factors were involved. One, effective against xerophthalmia, was named vitamin A; the other, effective against rickets, was named vitamin D. The factor that prevented scurvy was isolated in 1928. Known as "water-soluble C," it was renamed ascorbic acid.

77 FR 61515 - Alkyl Amines Polyalkoxylates; Exemption From the Requirement of a Tolerance

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-10

... polyoxyethylene polymers and fatty acids; carriers such as clay and diatomaceous earth; thickeners such as carrageenan and modified cellulose; wetting, spreading, and dispersing agents; propellants in aerosol...

A renewable amine for photochemical reduction of CO(2).

PubMed

Richardson, Robert D; Holland, Edward J; Carpenter, Barry K

2011-04-01

Photochemical reduction of CO₂ (to produce formic acid) can be seen both as a method to produce a transportable hydrogen-based fuel and also to reduce levels of CO₂ in the atmosphere. However, an often overlooked necessity for photochemical CO₂ reduction is the need for a sacrificial electron donor, usually a tertiary amine. Here, we describe a new strategy for coupling the photochemical reduction of CO₂ to photochemical water splitting, and illustrate this with a prototype example. Instead of seeking to eliminate the use of an external reducing agent altogether, our alternative strategy makes the reducing agent recyclable. This has two potential advantages over the direct coupling of CO₂ reduction and water oxidation. First, it allows the two redox reactions to be carried out with existing chemistry, and second, it permits these reactions to be conducted under mutually incompatible conditions.

Roles of free radicals in type 1 phototherapeutic agents: aromatic amines, sulfenamides, and sulfenates.

PubMed

Lin, Tien-Sung; Rajagopalan, Raghavan; Shen, Yuefei; Park, Sungho; Poreddy, Amruta R; Asmelash, Bethel; Karwa, Amolkumar S; Taylor, John-Stephen A

2013-07-03

Detailed analyses of the electron spin resonance (ESR) spectra, cell viability, and DNA degradation studies are presented for the photolyzed Type I phototherapeutic agents: aromatic amines, sulfenamides, and sulfenates. The ESR studies provided evidence that copious free radicals can be generated from these N-H, N-S, and S-O containing compounds upon photoirradiation with UV/visible light. The analyses of spectral data allowed us to identify the free radical species. The cell viability studies showed that these agents after exposure to light exert cytotoxicity to kill cancer cells (U937 leukemia cell lines HTC11, KB, and HT29 cell lines) in a dosage- and time-dependent manner. We examined a possible pathway of cell death via DNA degradation by a plasmid cleavage assay for several compounds. The effects of photosensitization with benzophenone in the presence of oxygen were examined. The studies indicate that planar tricyclic amines and sulfenamides tend to form π-electron delocalized aminyl radicals, whereas nonplanar ones tend to yield nitroxide radicals resulting from the recombination of aminyl radicals with oxygen. The ESR studies coupled with the results of cell viability measurements and DNA degradation reveal that planar N-centered radicals can provide higher potency in cell death and allow us to provide some insights on the reaction mechanisms. We also found the formation of azatropylium cations possessing high aromaticity derived from azepines can facilitate secondary electron transfer to form toxic O2(•-) radicals, which can further exert oxidative stress and cause cell death.

The effect of bleaching agents on the microhardness of dental aesthetic restorative materials.

PubMed

Türker, S B; Biskin, T

2002-07-01

This study investigated the effects of three home bleaching agents on the microhardness of various dental aesthetic restorative materials. The restorative materials were: feldspatic porcelain, microfilled composite resin and light-cured modified glass-ionomer cement and the bleaching agents Nite-White (16% carbamide peroxide), Opalescence (10% carbamide peroxide and carbapol jel) and Rembrandt (10% carbamide peroxide jel). A total of 90 restorative material samples were prepared 1 cm diameter and 6 mm thick and kept in distilled water for 24 h before commencing bleaching which was carried out for 8 h day-1 for 4 weeks. Microhardness measurements were then made using a Tukon tester. Statistically significant differences with respect to unbleached controls were found only for the feldspatic porcelain and microfilled composite resins (P <0.05) for Nite-White and Opalescence. All the bleaching agents decreased the microhardness of the porcelain and increased that of the light cured modified glass-ionomer cement. For the composite resin, whereas Nite-White increased its microhardness, the other bleaching agents decreased it. There were no significant differences between the bleaching agents for any of the restorative materials.

Host Methyltransferases and Demethylases: Potential New Epigenetic Targets for HIV Cure Strategies and Beyond.

PubMed

Boehm, Daniela; Ott, Melanie

2017-11-01

A successful HIV cure strategy may require reversing HIV latency to purge hidden viral reservoirs or enhancing HIV latency to permanently silence HIV transcription. Epigenetic modifying agents show promise as antilatency therapeutics in vitro and ex vivo, but also affect other steps in the viral life cycle. In this review, we summarize what we know about cellular DNA and protein methyltransferases (PMTs) as well as demethylases involved in HIV infection. We describe the biology and function of DNA methyltransferases, and their controversial role in HIV infection. We further explain the biology of PMTs and their effects on lysine and arginine methylation of histone and nonhistone proteins. We end with a focus on protein demethylases, their unique modes of action and their emerging influence on HIV infection. An outlook on the use of methylation-modifying agents in investigational HIV cure strategies is provided.

Development of toughened epoxy polymers for high performance composite and ablative applications

NASA Technical Reports Server (NTRS)

Allen, V. R.

1982-01-01

A survey of current procedures for the assessment of state of cure in epoxy polymers and for the evaluation of polymer toughness as related to nature of the crosslinking agent was made to facilitate a cause-effect study of the chemical modification of epoxy polymers. Various conformations of sample morphology were examined to identify testing variables and to establish optimum conditions for the selected physical test methods. Dynamic viscoelasticity testing was examined in conjunction with chemical analyses to allow observation of the extent of the curing reaction with size of the crosslinking agent the primary variable. Specifically the aims of the project were twofold: (1) to consider the experimental variables associated with development of "extent of cure" analysis, and (2) to assess methodology of fracture energy determination and to prescribe a meaningful and reproducible procedure. The following is separated into two categories for ease of presentation.

Effect of curing agents on the oxidative and nitrosative damage to meat proteins during processing of fermented sausages.

PubMed

Villaverde, A; Morcuende, D; Estévez, M

2014-07-01

The effect of increasing concentrations of curing agents, ascorbate (0, 250, and 500 ppm), and nitrite (0, 75, and 150 ppm), on the oxidative and nitrosative damage to proteins during processing of fermented sausages was studied. The potential influence of these reactions on color and texture of the fermented sausages was also addressed. Nitrite had a pro-oxidant effect on tryptophan depletion and promoted the formation of protein carbonyls and Schiff bases. The nitration degree in the fermented sausages was also dependent on nitrite concentration. On the other hand, ascorbate acted as an efficient inhibitor of the oxidative and nitrosative damage to meat proteins. As expected, nitrite clearly favored the formation of the cured red color and ascorbate acted as an enhancer of color formation. Nitrite content was positively correlated with hardness. The chemistry behind the action of nitrite and ascorbate on muscle proteins during meat fermentation is thoroughly discussed. The results suggest that ascorbate (500 ppm) may be required to compensate the pro-oxidant impact of nitrite on meat proteins. This study provides insight on the action of curing agents on meat proteins during processing of fermented sausages. This chemistry background provides understanding of the potential influence of the oxidative and nitrosative damage to proteins on the quality of processed muscle foods. The study provides novel information on the impact of the combination of nitrite and ascorbate on the chemical deterioration of proteins and the influence on particular quality traits of fermented sausages. These data may be of interest for the design of cured muscle foods of enhanced quality. © 2014 Institute of Food Technologists®

Influence of ceramic thickness and type on micromechanical properties of light-cured adhesive bonding agents.

PubMed

Öztürk, Elif; Bolay, Sükran; Hickel, Reinhard; Ilie, Nicoleta

2014-10-01

The aim of this study was to evaluate the micromechanical properties of different adhesive bonding agents when polymerized through ceramics. Sixty sound extracted human third molars were selected and the crowns were sectioned perpendicular to the long axis in order to obtain dentin slices to be bonded with one of the following adhesives: Syntac/Heliobond (Ivoclar-Vivadent) or Adper-Scotchbond-1XT (3M-ESPE). The adhesives were cured by using a LED-unit (Bluephase®, Ivoclar Vivadent) with three different curing times (10 s, 20 s and 30 s) under two ceramics (IPS-e.max-Press, Ivoclar-Vivadent; IPS-Empress®CAD, Ivoclar-Vivadent) of different thicknesses (0 mm, 0.75 mm, 2 mm). Thirty groups were included, each containing 60 measurements. Micromechanical properties (Hardness, HV; indentation modulus, E; and creep, Cr) of the adhesives were measured with an automatic microhardness indenter (Fisherscope H100C, Germany). Data were statistically analyzed by using one-way ANOVA and Tukey's post-hoc test, as well as a multivariate analysis to test the influence of the study parameters (SPSS 18.0). Significant differences were observed between the micromechanical properties of the adhesives (p < 0.05). The ceramic type showed the highest effect on HV (Partial-eta squared (η(2)) = 0.109) of the tested adhesives, while E (η(2) = 0.275) and Cr (η(2) = 0.194) were stronger influenced by the adhesive type. Ceramic thickness showed no effect on the E and Cr of the adhesives. The adhesive bonding agents used in this study performed well by curing through different thicknesses of ceramics. The micromechanical properties of the adhesives were determined by the adhesive type and were less influenced by ceramic type and curing time.

Surface functionalization of microwave plasma-synthesized silica nanoparticles for enhancing the stability of dispersions

NASA Astrophysics Data System (ADS)

Sehlleier, Yee Hwa; Abdali, Ali; Schnurre, Sophie Marie; Wiggers, Hartmut; Schulz, Christof

2014-08-01

Gas phase-synthesized silica nanoparticles were functionalized with three different silane coupling agents (SCAs) including amine, amine/phosphonate and octyltriethoxy functional groups and the stability of dispersions in polar and non-polar dispersing media such as water, ethanol, methanol, chloroform, benzene, and toluene was studied. Fourier transform infrared spectroscopy showed that all three SCAs are chemically attached to the surface of silica nanoparticles. Amine-functionalized particles using steric dispersion stabilization alone showed limited stability. Thus, an additional SCA with sufficiently long hydrocarbon chains and strong positively charged phosphonate groups was introduced in order to achieve electrosteric stabilization. Steric stabilization was successful with hydrophobic octyltriethoxy-functionalized silica nanoparticles in non-polar solvents. The results from dynamic light scattering measurements showed that in dispersions of amine/phosphonate- and octyltriethoxy-functionalized silica particles are dispersed on a primary particle level. Stable dispersions were successfully prepared from initially agglomerated nanoparticles synthesized in a microwave plasma reactor by designing the surface functionalization.

Click and chemically triggered declick reactions through reversible amine and thiol coupling via a conjugate acceptor

NASA Astrophysics Data System (ADS)

Diehl, Katharine L.; Kolesnichenko, Igor V.; Robotham, Scott A.; Bachman, J. Logan; Zhong, Ye; Brodbelt, Jennifer S.; Anslyn, Eric V.

2016-10-01

The coupling and decoupling of molecular units is a fundamental undertaking of organic chemistry. Herein we report the use of a very simple conjugate acceptor, derived from Meldrum's acid, for the sequential ‘clicking’ together of an amine and a thiol in aqueous conditions at neutral pH. Subsequently, this linkage can be ‘declicked’ by a chemical trigger to release the original amine and thiol undisturbed. The reactivity differs from that of other crosslinking agents because the selectivity for sequential functionalization derives from an altering of the electrophilicity of the conjugate acceptor on the addition of the amine. We describe the use of the procedure to modify proteins, create multicomponent libraries and synthesize oligomers, all of which can be declicked to their starting components in a controlled fashion when desired. Owing to the mild reaction conditions and ease of use in a variety of applications, the method is predicted to have wide utility.

Cancer-selective, single agent chemoradiosensitising gold nanoparticles

PubMed Central

Grellet, Sophie; Tzelepi, Konstantina; Roskamp, Meike; Williams, Phil; Sharif, Aquila; Slade-Carter, Richard; Goldie, Peter; Whilde, Nicky; Śmiałek, Małgorzata A.; Mason, Nigel J.

2017-01-01

Two nanometre gold nanoparticles (AuNPs), bearing sugar moieties and/or thiol-polyethylene glycol-amine (PEG-amine), were synthesised and evaluated for their in vitro toxicity and ability to radiosensitise cells with 220 kV and 6 MV X-rays, using four cell lines representing normal and cancerous skin and breast tissues. Acute 3 h exposure of cells to AuNPs, bearing PEG-amine only or a 50:50 ratio of alpha-galactose derivative and PEG-amine resulted in selective uptake and toxicity towards cancer cells at unprecedentedly low nanomolar concentrations. Chemotoxicity was prevented by co-administration of N-acetyl cysteine antioxidant, or partially prevented by the caspase inhibitor Z-VAD-FMK. In addition to their intrinsic cancer-selective chemotoxicity, these AuNPs acted as radiosensitisers in combination with 220 kV or 6 MV X-rays. The ability of AuNPs bearing simple ligands to act as cancer-selective chemoradiosensitisers at low concentrations is a novel discovery that holds great promise in developing low-cost cancer nanotherapeutics. PMID:28700660

Eco-friendly synthesis of size-controllable amine-functionalized graphene quantum dots with antimycoplasma properties.

PubMed

Jiang, Feng; Chen, Daiqin; Li, Ruimin; Wang, Yucheng; Zhang, Guoqiang; Li, Shumu; Zheng, Junpeng; Huang, Naiyan; Gu, Ying; Wang, Chunru; Shu, Chunying

2013-02-07

Size-controllable amine-functionalized graphene quantum dots (GQDs) are prepared by an eco-friendly method with graphene oxide sheets, ammonia and hydrogen peroxide as starting materials. Using a Sephadex G-25 gel column for fine separation, for the first time we obtain GQDs with either single or double layers. By atomic force microscopy characterization, we confirm that hydrogen peroxide and ammonia play a synergistic role on graphene oxide (GO), in which the former cuts the GO into small pieces and the latter passivates the active surface to give amine-modified GQDs. Due to the low cytotoxicity and excellent biocompatibility of the obtained amine-functionalized GQDs, besides the multiwavelength imaging properties of GQDs, for the first time we find that this kind of GQD exhibits good antimycoplasma properties. Given the superior antimycoplasma effect of the GQDs and their eco-friendly mass production with low cost, these new GQDs may offer opportunities for the development of new antimycoplasma agents, thus extending their widespread application in biomedicine.

Solidifying process and flame retardancy of epoxy resin cured with boron-containing phenolic resin

NASA Astrophysics Data System (ADS)

Deng, Peng; Shi, Yan; Liu, Yuansen; Liu, Yuan; Wang, Qi

2018-01-01

For the sake of improving the charring performance and flame retardancy of epoxy resin (EP), boron-containing phenolic resin (BPR) instead of a conventional curing agent, linear phenolic resin (LPR) was employed to cure EP. Of several possible chemical structures for BPR, the existence of benzyl hydroxy groups in BPR chains has been confirmed using 1H nuclear magnetic resonance spectroscopy. The resonance of these groups may reasonably explain the higher curing reactivity of BPR-cured EP than that of LPR-cured EP. Thermogravimetric analysis, observation of the morphologies of the char residues and X-ray photoelectron spectroscopic were performed to characterize the charring process. Due to the presence of B2O3 produced on the char surface from decomposition of phenyl borates and the facile high self-crosslinking reaction of BPR, a more continuous and stronger char barrier was formed for BPR-cured EP compared to that for the LPR-cured EP system. Therefore the former exhibited much better flame retardancy. In addition, BPR-cured EP also displayed better dynamic mechanical properties, than those observed for LPR-cured EP. It is not subject to the significant lowering the glass transition temperature of the polymer which accompanies curing with LPR. This suggests that BPR cured resin may meet the requirement for utilization at high temperature.

Tetrahydropyranodiquinolin-8-amines as new, non hepatotoxic, antioxidant, and acetylcholinesterase inhibitors for Alzheimer's disease therapy.

PubMed

Dgachi, Youssef; Sokolov, Olga; Luzet, Vincent; Godyń, Justyna; Panek, Dawid; Bonet, Alexandre; Martin, Hélène; Iriepa, Isabel; Moraleda, Ignacio; García-Iriepa, Cristina; Janockova, Jana; Richert, Lysiane; Soukup, Ondrej; Malawska, Barbara; Chabchoub, Fakher; Marco-Contelles, José; Ismaili, Lhassane

2017-01-27

Herein we report an efficient two step synthesis and biological assessment of 12 racemic tetrahydropyranodiquinolin-8-amines derivatives as antioxidant, cholinesterase inhibitors and non-hepatotoxic agents. Based on the results of the primary screening, we identified 7-(3-methoxyphenyl)-9,10,11,12-tetrahydro-7H-pyrano[2,3-b:5,6-h']diquinolin-8-amine (2h) as a particularly interesting non-hepatotoxic compound that shows moderate antioxidant activity (1.83 equiv Trolox in the ORAC assay), a non competitive inhibition of hAChE (IC 50  = 0.75 ± 0.01 μM), and brain permeable as determined by the PAMPA-Blood Brain Barrier assay. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Partial Analysis of Insta-Foam

NASA Technical Reports Server (NTRS)

Chou, L. W.

1983-01-01

Insta-Foam, used as a thermal insulator for the non-critical area of the external tank during the prelaunch phase to minimize icing, is a two-component system. Component A has polyisocyanates, blowing agents, and stabilizers; Component B has the polyols, catalysts, blowing agents, stabilizers and fire retardant. The blowing agents are Freon 11 and Freon 12, the stabilizers are silicone surfactants, the catalysts are tertiary amines, and the fire retardant is tri-(beta-chloro-isopropyl) phosphate (PCF). High performance liquid chromatography (HPLC) was quantitatively identified polyols and PFC.

High performance UV and thermal cure hybrid epoxy adhesive

NASA Astrophysics Data System (ADS)

Chen, C. F.; Iwasaki, S.; Kanari, M.; Li, B.; Wang, C.; Lu, D. Q.

2017-06-01

New type one component UV and thermal curable hybrid epoxy adhesive was successfully developed. The hybrid epoxy adhesive is complete initiator free composition. Neither photo-initiator nor thermal initiator is contained. The hybrid adhesive is mainly composed of special designed liquid bismaleimide, partially acrylated epoxy resin, acrylic monomer, epoxy resin and latent curing agent. Its UV light and thermal cure behavior was studied by FT-IR spectroscopy and FT-Raman spectroscopy. Adhesive samples cured at UV only, thermal only and UV + thermal cure conditions were investigated. By calculated conversion rate of double bond in both acrylic component and maleimide compound, satisfactory light curability of the hybrid epoxy adhesive was confirmed quantitatively. The investigation results also showed that its UV cure components, acrylic and bismalimide, possess good thermal curability too. The initiator free hybrid epoxy adhesive showed satisfactory UV curability, good thermal curability and high adhesion performance.

Trace amine-associated receptors and their ligands

PubMed Central

Zucchi, R; Chiellini, G; Scanlan, T S; Grandy, D K

2006-01-01

Classical biogenic amines (adrenaline, noradrenaline, dopamine, serotonin and histamine) interact with specific families of G protein-coupled receptors (GPCRs). The term ‘trace amines' is used when referring to p-tyramine, β-phenylethylamine, tryptamine and octopamine, compounds that are present in mammalian tissues at very low (nanomolar) concentrations. The pharmacological effects of trace amines are usually attributed to their interference with the aminergic pathways, but in 2001 a new gene was identified, that codes for a GPCR responding to p-tyramine and β-phenylethylamine but not to classical biogenic amines. Several closely related genes were subsequently identified and designated as the trace amine-associated receptors (TAARs). Pharmacological investigations in vitro show that many TAAR subtypes may not respond to p-tyramine, β-phenylethylamine, tryptamine or octopamine, suggesting the existence of additional endogenous ligands. A novel endogenous thyroid hormone derivative, 3-iodothyronamine, has been found to interact with TAAR1 and possibly other TAAR subtypes. In vivo, micromolar concentrations of 3-iodothyronamine determine functional effects which are opposite to those produced on a longer time scale by thyroid hormones, including reduction in body temperature and decrease in cardiac contractility. Expression of all TAAR subtypes except TAAR1 has been reported in mouse olfactory epithelium, and several volatile amines were shown to interact with specific TAAR subtypes. In addition, there is evidence that TAAR1 is targeted by amphetamines and other psychotropic agents, while genetic linkage studies show a significant association between the TAAR gene family locus and susceptibility to schizophrenia or bipolar affective disorder. PMID:17088868

Preparation of amine functionalized carbon nanotubes via a bioinspired strategy and their application in Cu2+ removal

NASA Astrophysics Data System (ADS)

Zhang, Xiaoyong; Huang, Qiang; Liu, Meiying; Tian, Jianwen; Zeng, Guangjian; Li, Zhen; Wang, Ke; Zhang, Qinsong; Wan, Qing; Deng, Fengjie; Wei, Yen

2015-07-01

The environmental applications of carbon nanotubes (CNTs) have attracted great research attention since their first discovery. However, the performance of pristine CNTs for removal of heavy metal ions is greatly limited by their severe aggregation and lack of functional groups. In this work, a novel method has been developed for preparation of amine functionalized CNTs via combination of mussel inspired chemistry and Michael addition reaction. CNTs were first coated with polydopamine (PDA) through mussel inspired chemistry. And then commercial available agent polyethylene polyamine with a number of amine groups was further conjugated with PDA coated CNTs via Michael addition reaction. A series of characterization techniques have demonstrated that the amine functionalized CNTs have been successfully prepared. Furthermore, the adsorption application of thus amine functionalized CNTs for Cu2+ was examined. The effects of various parameters including pH solution, temperature, initial Cu2+ concentration and the adsorbent concentration were investigated. The data from experiments were analyzed by the Langmuir and Freundlich models of adsorption. Due to the universal of mussel inspired chemistry, the method described in this work should be a general strategy for surface modification of materials for environmental applications.

Palladium-Catalyzed Transannular C–H Functionalization of Alicyclic Amines

PubMed Central

Saper, Noam I.; Sanford, Melanie S.

2016-01-01

The discovery of pharmaceutical candidates is a resource-intensive enterprise that frequently requires the parallel synthesis of hundreds or even thousands of molecules. Carbon-hydrogen bonds are present in almost all pharmaceutical agents. As such, the development of selective, rapid, and efficient methods for converting carbon-hydrogen bonds into new chemical entities has the potential to dramatically streamline pharmaceutical development1,2,3,4. Saturated nitrogen-containing heterocycles (alicyclic amines) feature prominently in pharmaceuticals, including treatments for depression (paroxetine, amitifadine), diabetes (gliclazide), leukemia (alvocidib), schizophrenia (risperidone, belaperidone), and nicotine addiction (cytisine and varenicline)5. However, existing methods for the C–H functionalization of saturated nitrogen heterocycles, particularly at sites remote to nitrogen, remain extremely limited 6,7. Here we report a new approach to selectively manipulate the carbon–hydrogen bonds of alicyclic amines at sites remote to nitrogen. Our reaction leverages the boat conformation of the substrates to achieve the palladium-catalyzed amine-directed conversion of C–H bonds to C–C bonds on various alicyclic amine scaffolds. This approach is applied to the synthesis of novel derivatives of several bioactive molecules, including the top-selling smoking cessation drug varenicline (Chantix®). We anticipate that this method should prove broadly useful in medicinal chemistry. PMID:26886789

Investigations on N-nitrosopyrrolidine in dry-cured bacon.

PubMed

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

1989-01-01

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

Effects of Trace Amine-associated Receptor 1 Agonists on the Expression, Reconsolidation, and Extinction of Cocaine Reward Memory.

PubMed

Liu, Jian-Feng; Thorn, David A; Zhang, Yanan; Li, Jun-Xu

2016-07-01

As a modulator of dopaminergic system, trace amine-associated receptor 1 has been shown to play a critical role in regulating the rewarding properties of additive drugs. It has been demonstrated that activation of trace amine-associated receptor 1 decreased the abuse-related behaviors of cocaine in rats. However, the role of trace amine-associated receptor 1 in specific stages of cocaine reward memory is still unclear. Here, using a cocaine-induced conditioned place preference model, we tested the effects of a selective trace amine-associated receptor 1 agonist RO5166017 on the expression, reconsolidation, and extinction of cocaine reward memory. We found that RO5166017 inhibited the expression but not retention of cocaine-induced conditioned place preference. RO5166017 had no effect on the reconsolidation of cocaine reward memory. Pretreatment with RO5166017 before extinction hindered the formation of extinction long-term memory. RO5166017 did not affect the movement during the conditioned place preference test, indicating the inhibitory effect of RO5166017 on the expression of cocaine-induced conditioned place preference was not caused by locomotion inhibition. Using a cocaine i.v. self-administration model, we found that the combined trace amine-associated receptor 1 partial agonist RO5263397 with extinction had no effect on the following cue- and drug-induced reinstatement of cocaine-seeking behavior. Repeated administration of the trace amine-associated receptor 1 agonist during extinction showed a continually inhibitory effect on the expression of cocaine reward memory both in cocaine-induced conditioned place preference and cocaine self-administration models. Taken together, these results indicate that activation of trace amine-associated receptor 1 specifically inhibited the expression of cocaine reward memory. The inhibitory effect of trace amine-associated receptor 1 agonists on cocaine reward memory suggests that trace amine-associated receptor 1 agonists could be a promising agent to prevent cocaine relapse. © The Author 2016. Published by Oxford University Press on behalf of CINP.

Evaluation of experimental epoxy monomers

NASA Technical Reports Server (NTRS)

Hodges, W. T.; St.clair, T. L.; Pratt, J. R.; Ficklin, R.

1985-01-01

Future generation aircraft need higher performance polymer matrices to fully achieve the weight savings possible with composite materials. New resins are being formulated in an effort to understand basic polymer behavior and to develop improved resins. Some polymer/curing agent combinations that could be useful are difficult to process. In the area of epoxies, a major problem is that some components have physical properties which make them difficult to utilize as matrix resins. A previous study showed that the use of ultrasonic energy can be advantageous in the mixing of curing agents into a standard epoxy resin, such as MY 720 (Ciba-Geigy designation). This work is expanded to include three novel epoxides.

Effect of granular porous media on the composting of swine manure

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

Kim, Ku-Yong; Kim, Hyun-Woo; Han, Sun-Kee

2008-11-15

This study investigated the feasibility of a bulking agent of granular porous media (GPM) for the composting of swine manure. Two lab-scale composting reactors were operated to evaluate the general performances and maturity parameters using GPM made of wastes from the Portland cement manufacturing processes as an alternative bulking agent. The overall volatile solid (VS) removal was 38.5% (dry basis). During the experiments, moisture content ranged between 41% and 53%, ensuring feasibility of microbial activity in composting. Cured compost showed proper maturity and low phytotoxicity, despite the slight decreases of CO{sub 2} production and VS removal at the second batchmore » operation. Various physico-chemical parameters of the cured compost met the regulatory standards reported elsewhere. The pH, carbon-to-nitrogen ratio, ammonia nitrogen and soluble organic carbon (SOC) of the cured compost were significantly correlated to the germination index (GI) using the seeds of Chinese cabbage and lettuce, indicating the progressive biodegradation of phytotoxins as well as organic matter. Consequently, the results obtained in this study demonstrate that GPM could contribute to the environmentally friendly and economical composting of problematic swine manure as a recyclable bulking agent.« less

Single dose treatment of gonococcal urethritis with augmentin in Ibadan.

PubMed

Osoba, A O; Oyelese, A O; Ashiru, J O; Ekweozor, C C; Ochei, J

1985-01-01

Augmentin, a new orally absorbed broadspectrum antibacterial agent comprising of amoxycillin trihydrate and potassium clavulanate, was investigated in the treatment of gonococcal urethritis in Ibadan, Nigeria, where penicillinase producing Neisseria gonorrhoeae (PPNG) constitute about 80% of the circulating strains of gonococci. Two different formulations of the agent were employed in the study. The first formulation consisting of 3.0 g amoxycillin and 125 mg clavulanic acid, achieved a cure rate of 75% (i.e. eighteen out of twenty-four patients) among PPNG infections, but 100% cure rate among nine patients with non-PPNG infections. The second formulation consisting of 3.0 g amoxycillin and 250 mg clavulanic acid, had a cure rate of 86% (i.e. fifty-seven out of sixty-six patients) among PPNG infections, and 91% (i.e. ten out of eleven patients) among non-PPNG infections. Clavulanic acid appears to potentiate and enhance the activity of amoxycillin against the beta-lactamase produced by the gonococci. Augmentin seems to be a good and acceptable agent for the treatment of gonococcal infections, in this environment and further studies on its efficacy are therefore justified, such as the simultaneous administration of probenecid.

Study on epoxy resin modified by polyether ionic liquid

NASA Astrophysics Data System (ADS)

Jin, X. C.; Guo, L. Y.; Deng, L. L.; Wu, H.

2017-06-01

Chloride 1-carboxyl polyether-3-methyl imidazole ionic liquid (PIIL) was synthesized. Then blended with epoxy resin(EP) to prepare the composite materials of PIIL/EP, which cured with aniline curing agent. The structure and curing performance of PIIL/EP were determined by FT-IR and DSC. The effects of the content of PIIL on strength of EP were studied. The results show that the PIIL was the target product. The strength was improved significantly with increase of the PIIL content. The obvious rubber elasticity of PIIL/EP after cured was showed when the content of PIIL accounts for 40% and the impact strength was up to 15.95kJ/m2.

Cage-like bifunctional chelators, copper-64 radiopharmaceuticals and PET imaging using the same

DOEpatents

Conti, Peter S.; Cai, Hancheng; Li, Zibo; Liu, Shuanglong

2016-08-02

Disclosed is a class of versatile Sarcophagine based bifunctional chelators (BFCs) containing a hexa-aza cage for labeling with metals having either imaging, therapeutic or contrast applications radiolabeling and one or more linkers (A) and (B). The compounds have the general formula ##STR00001## where A is a functional group selected from group consisting of an amine, a carboxylic acid, an ester, a carbonyl, a thiol, an azide and an alkene, and B is a functional group selected from the group consisting of hydrogen, an amine, a carboxylic acid, and ester, a carbonyl, a thiol, an azide and an alkene. Also disclosed are conjugate of the BFC and a targeting moiety, which may be a peptide or antibody. Also disclosed are metal complexes of the BFC/targeting moiety conjugates that are useful as radiopharmaceuticals, imaging agents or contrast agents.

Effects of Nano-Aluminum Nitride on the Performance of an Ultrahigh-Temperature Inorganic Phosphate Adhesive Cured at Room Temperature

PubMed Central

Ma, Chengkun; Chen, Hailong; Wang, Chao; Zhang, Jifeng; Qi, Hui; Zhou, Limin

2017-01-01

Based on the optimal proportion of resin and curing agent, an ultrahigh-temperature inorganic phosphate adhesive was prepared with aluminum dihydric phosphate, aluminium oxide (α-Al2O3), etc. and cured at room temperature (RT). Then, nano-aluminum nitride (nano-AlN), nano-Cupric oxide (nano-CuO), and nano-titanium oxide (nano-TiO2) were added into the adhesive. Differential scanning calorimetry was conducted using the inorganic phosphate adhesive to analyze the phosphate reactions during heat treatment, and it was found that 15 wt % nano-AlN could clearly decrease the curing temperature. Scanning electron microscopy was used to observe the microphenomenon of the modified adhesive at ultrahigh-temperature. The differential thermal analysis of the inorganic phosphate adhesive showed that the weight loss was approximately 6.5 wt % when the mass ratio of resin to curing agent was 1:1.5. An X-ray diffraction analysis of the adhesive with 10% nano-AlN showed that the phase structure changed from AlPO4(11-0500) to the more stable AlPO4(10-0423) structure after heat treatment. The shear strength of the adhesive containing 10% nano-AlN reached 7.3 MPa at RT due to the addition of nano-AlN, which promoted the formation of phosphate and increased the Al3+. PMID:29099812

Reduction of aromatic and heterocyclic aromatic N-hydroxylamines by human cytochrome P450 2S1.

PubMed

Wang, Kai; Guengerich, F Peter

2013-06-17

Many aromatic amines and heterocyclic aromatic amines (HAAs) are known carcinogens for animals, and there is also strong evidence of some in human cancer. The activation of these compounds, including some arylamine drugs, involves N-hydroxylation, usually by cytochrome P450 enzymes (P450) in Family 1 (1A2, 1A1, and 1B1). We previously demonstrated that the bioactivation product of the anticancer agent 2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole (5F 203), an N-hydroxylamine, can be reduced by P450 2S1 to its amine precursor under anaerobic conditions and, to a lesser extent, under aerobic conditions [Wang, K., and Guengerich, F. P. (2012) Chem. Res. Toxicol. 25, 1740-1751]. In the study presented here, we tested the hypothesis that P450 2S1 is involved in the reductive biotransformation of known carcinogenic aromatic amines and HAAs. The N-hydroxylamines of 4-aminobiphenyl (4-ABP), 2-naphthylamine (2-NA), and 2-aminofluorene (2-AF) were synthesized and found to be reduced by P450 2S1 under both anaerobic and aerobic conditions. The formation of amines due to P450 2S1 reduction also occurred under aerobic conditions but was less apparent because the competitive disproportionation reactions (of the N-hydroxylamines) also yielded amines. Further, some nitroso and nitro derivatives of the arylamines could also be reduced by P450 2S1. None of the amines tested were oxidized by P450 2S1. These results suggest that P450 2S1 may be involved in the reductive detoxication of several of the activated products of carcinogenic aromatic amines and HAAs.

Reduction of Aromatic and Heterocyclic Aromatic N-Hydroxylamines by Human Cytochrome P450 2S1

PubMed Central

Wang, Kai; Guengerich, F. Peter

2013-01-01

Many aromatic amines and heterocyclic aromatic amines (HAAs) are known carcinogens for animals and there is also strong evidence for some in human cancer. The activation of these compounds, including some arylamine drugs, involves N-hydroxylation, usually by cytochrome P450 enzymes (P450) in Family 1 (1A2, 1A1, and 1B1). We previously demonstrated that the bioactivation product of the anti-cancer agent 2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole (5F 203), an N-hydroxylamine, can be reduced by P450 2S1 to its amine precursor under anaerobic conditions and, to a lesser extent, under aerobic conditions (Wang, K., and Guengerich, F. P. (2012) Chem. Res. Toxicol. 25, 1740–1751). In the present study, we tested the hypothesis that P450 2S1 is involved in the reductive biotransformation of known carcinogenic aromatic amines and HAAs. The N-hydroxylamines of 4-aminobiphenyl (4-ABP), 2-naphthylamine (2-NA), and 2-aminofluorene (2-AF) were synthesized and found to be reduced by P450 2S1 under both anaerobic and aerobic conditions. The formation of amines due to P450 2S1 reduction also occurred under aerobic conditions but was less apparent because the competitive disproportionation reactions (of the N-hydroxylamines) also yielded amines. Further, some nitroso and nitro derivatives of the arylamines could also be reduced by P450 2S1. None of the amines tested were oxidized by P450 2S1. These results suggest that P450 2S1 may be involved in the reductive detoxication of several of the activated products of carcinogenic aromatic amines and HAAs. PMID:23682735

Development of resistance of mutans streptococci and Porphyromonas gingivalis to chlorhexidine digluconate and amine fluoride/stannous fluoride-containing mouthrinses, in vitro.

PubMed

Kulik, Eva M; Waltimo, Tuomas; Weiger, Roland; Schweizer, Irene; Lenkeit, Krystyna; Filipuzzi-Jenny, Elisabeth; Walter, Clemens

2015-07-01

The aim if this study was to determine the minimal inhibitory concentrations of chlorhexidine digluconate and an amine fluoride/stannous fluoride-containing mouthrinse against Porphyromonas gingivalis and mutans streptococci during an experimental long-term subinhibitory exposition. Five P. gingivalis strains and four mutans streptococci were subcultivated for 20-30 passages in subinhibitory concentrations of chlorhexidine digluconate or an amine fluoride/stannous fluoride-containing mouthrinse. Pre-passaging minimal inhibitory concentrations for chlorhexidine ranged from 0.5 to 2 mg/l for mutans streptococci and from 2 to 4 mg/l for the P. gingivalis isolates. For the amine fluoride/stannous fluoride-containing mouthrinse minimal inhibitory values from 0.125 to 0.25% for the mutans streptococci and from 0.063 to 0.125% for the P. gingivalis isolates were determined. Two- to fourfold increased minimal inhibitory concentrations against chlorhexidine were detected for two of the five P. gingivalis isolates, whereas no increase in minimal inhibitory concentrations was found for the mutans streptococci after repeated passaging through subinhibitory concentrations. Repeated exposure to subinhibitory concentrations of the amine fluoride/stannous fluoride-containing mouthrinse did not alter the minimally inhibitory concentrations of the bacterial isolates tested. Chlorhexidine and the amine fluoride/stannous fluoride-containing mouthrinse are effective inhibitory agents against the oral bacterial isolates tested. No general development of resistance against chlorhexidine or the amine fluoride/stannous fluoride-containing mouthrinse was detected. However, some strains showed potential to develop resistance against chlorhexidine after prolonged exposure. The use of chlorhexidine should be limited to short periods of time. The amine fluoride/stannous fluoride-containing mouthrinse appears to have the potential to be used on a long-term basis.

Reply to Commentary: "Are HIV-Infected Candidates for Participation in Risky Cure-Related Studies Otherwise Healthy?"

PubMed

Dubé, Karine; Sylla, Laurie; Dee, Lynda

2018-02-01

We respond to Eyal et al.'s commentary focusing on how people living with HIV participating in HIV cure-related studies are defined. We argue that the types of participants enrolled in research cannot be dissociated from the study interventions, the types of anticipated risks, and the background standard of care. As the field of HIV cure research advances, more nuance and granularity will be needed to define research criteria and acceptable risk/benefit ratios for cure study participants, as well as specific tiered protocol designs that serve to protect various participant populations from untoward risks, especially in very early phase research with interventions known to have potentially serious toxicities. We highlight key lessons from the ACTIVATE study involving a latency-reversing agent, Panobinostat, for HIV cure study design involving "otherwise healthy volunteers".

Volatile N-nitrosamines in meat products: Potential precursors, influence of processing, and mitigation strategies.

PubMed

De Mey, Eveline; De Maere, Hannelore; Paelinck, Hubert; Fraeye, Ilse

2017-09-02

Meat products can be contaminated with carcinogenic N-nitrosamines, which is ascribed to the reaction between a nitrosating agent, originating from nitrite or smoke, and a secondary amine, derived from protein and lipid degradation. Although in model systems it is demonstrated that many amine containing compounds can be converted to N-nitrosamines, the yield is dependent of reaction conditions (e.g., low pH and high temperature). In this article, the influence of the composition of the meat products (e.g., pH, a w , spices) and processing (e.g., ageing, ripening, fermentation, smoking, heat treatment and storage) on the presence and availability of the amine precursors and the N-nitrosamine formation mechanism is discussed. In addition, this article explores the current N-nitrosamine mitigation strategies in order to obtain healthier and more natural meat products.

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.

A Survey and Evaluation of Chemical Warfare Agent-Decontaminants and Decontamination

DTIC Science & Technology

1984-10-15

0.21 citric acid monohydrate, 0.05% detergent, and 98.251 water) all contain calcium hypochlorite and have been used for decontaminating agents from...water repellent chemicals consist of an aluminum salt of a saturated carboxylic acid (such as format, acetate, palmitate, or stearate) mixed with...been conducted. Sawdust, soil, silicone, coal dust, amine or sulfonic acid -containing polymers, organic and inorganic ion-exchange materials, and metal

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.

WATER STABILITY OF FILLED ELASTOMERS,

DTIC Science & Technology

ELECTRICAL INSULATION, *BUTYL RUBBER , ELASTOMERS, STABILITY, STABILITY, HYDROLYSIS, CURING AGENTS, ADDITIVES, WATER, ABSORPTION, THICKNESS, ELECTRICAL RESISTANCE, LEAKAGE(ELECTRICAL), DIFFUSION, TALC, ELECTRIC CABLES.

Nitromethane with IBX/TBAF as a nitrosating agent: synthesis of nitrosamines from secondary or tertiary amines under mild conditions.

PubMed

Potturi, Hima K; Gurung, Ras K; Hou, Yuqing

2012-01-06

Aliphatic or aromatic N,N-disubstituted nitrosamine was generated in fair to excellent yield from the reaction of a secondary or tertiary amine with o-iodoxybenzoic acid (IBX) or o-iodosylbenzoic acid (IBA)/R(4)NX (X = halide) and nitromethane. The product yield was strongly influenced by both the halide of R(4)NX and iodanes. IBX gave a higher yield than IBA, while the halides follow F(-) > Cl(-) > Br(-) ∼ I(-). Nitrous acid formed in situ from nitromethane and IBX (or IBA)/halides is likely responsible for the observed reaction.

Finding a cure for HIV: will it ever be achievable?

PubMed Central

2011-01-01

Combination antiretroviral therapy (cART) has led to a major reduction in HIV-related mortality and morbidity. However, HIV still cannot be cured. With the absence of an effective prophylactic or therapeutic vaccine, increasing numbers of infected people, emerging new toxicities secondary to cART and the need for life-long treatment, there is now a real urgency to find a cure for HIV. There are currently multiple barriers to curing HIV. The most significant barrier is the establishment of a latent or "silent" infection in resting CD4+ T cells. In latent HIV infection, the virus is able to integrate into the host cell genome, but does not proceed to active replication. As a consequence, antiviral agents, as well as the immune system, are unable to eliminate these long-lived, latently infected cells. Reactivation of latently infected resting CD4+ T cells can then re-establish infection once cART is stopped. Other significant barriers to cure include residual viral replication in patients receiving cART, even when the virus is not detectable by conventional assays. In addition, HIV can be sequestered in anatomical reservoirs, such as the brain, gastrointestinal tract and genitourinary tract. Achieving either a functional cure (long-term control of HIV in the absence of cART) or a sterilizing cure (elimination of all HIV-infected cells) remains a major challenge. Several studies have now demonstrated that treatment intensification appears to have little impact on latent reservoirs. Some potential and promising approaches that may reduce the latent reservoir include very early initiation of cART and the use of agents that could potentially reverse latent infection. Agents that reverse latent infection will promote viral production; however, simultaneous administration of cART will prevent subsequent rounds of viral replication. Such drugs as histone deacetylase inhibitors, currently used and licensed for the treatment of some cancers, or activating latently infected resting cells with cytokines, such as IL-7 or prostratin, show promising results in reversing latency in vitro when used either alone or in combination. In order to move forward toward clinical trials that target eradication, there needs to be careful consideration of the risks and benefits of these approaches, agreement on the most informative endpoints for eradication studies and greater engagement of the infected community. PMID:21255462

Unique applications of fluoroepoxy materials

NASA Technical Reports Server (NTRS)

Lee, Sheng Yen

1991-01-01

The following subject areas are covered: (1) fluoroepoxy and curing agents; (2) an excellent moisture vapor barrier coating; (3) as adhesives to bond Teflon without any surface treatment; (4) a new method to make thermosetting fluoropolymer foam; and (5) as a new antifoaming agent for epoxy material manufacturing and processing.

Emulsification Of Eutectic Salt Mixtures In Fluid Vehicles

NASA Astrophysics Data System (ADS)

Vanderhoff, J. W.; El-Aasser, M. S.; Hawkins, T. W.

1988-05-01

High-internal-phase-volume emulsions of 75 volt 3/18/79 potassium iodide/sodium iodide/ urea model eutectic salt mixture in 83.5/16.5 Sartomer R-45HT hydroxy-terminated polybutadi-ene/Nujol mineral oil binder mixture were prepared at 60°C using water-in-oil emulsifiers and cured with isophorone diisocyanate or Desmodur N-100. The Nujol mineral oil enhanced the emulsification with a negligible reduction in the tensile properties of the cured elastomer. The average emulsion droplet sizes were ca. 200 nm initially, but increased slowly during curing to 500-1000 nm. The coalescence of the emulsion droplets followed the second-order dependence predicted by the von Smoluchowski diffusion-controlled flocculation; the rate constants were 1.05x10-18 and 9.58x10-18 cc/droplet-sec for dirnethyldioctadecylammonium bromide and Span 85 sorbitan trioleate, respectively. The isophorone diisocyanate reacted with emulsifiers containing primary hydroxyl or amine groups, to give unstable emulsions or no emulsions at all. Dimethyldioctadecylammonium bromide with no primary hydroxyl or amine groups, however, did not react with isocyanates and gave stable emulsions. The reaction of the R-45HT hydroxy-terminated polybutadiene with isophorone diisocyanate followed the expec-ted second-order kinetics with a rate constant of 3.42x10-4 liters/mole-sec at 60°C. The tensile properties of the cured elastomers and emulsions generally increased with increasing NCO/OH ratio up to 1.6/1.0. With increasing volume fraction of dispersed phase, the maximum stress (tensile strength) decreased, the maximum strain (percent elongation) increased, and the initial modulus (tensile modulus) decreased, in contrast to the behavior of conventional filled polymer systems; however, the maximum stresses were in accord with theoretical values for a filled polymer in which the filler particles bear no load, the initial moduli were in accord with the predictions of an isostrain model, and the maximum strain increased with in-creasing volume fraction of dispersed phase; these unusual variations, which were attributed to the liquid nature of the emulsion droplets, were used to estimate the elastomer proper-ties required to give the desired properties: 60-100 psi maximum stress, 80-150% maximum strain, and 500-2000 psi initial modulus for an 88/12 eutectic salt/crosslinked polybutadi-ene composite containing 20% aluminum particles. The addition of 20% aluminum particles gave a modest improvement in tensile properties, and the addition of 2.5% or 3.5% submicroscopic carbon black particles gave a greater improvement; however, the tensile properties were still slightly short of the desired properties.

From Metal Thiobenzoates to Metal Sulfide Nanocrystals: An Experimental and Theoretical Investigation

PubMed Central

Zhang, Zhihua; Lim, Wen Pei; Wong, Chiong Teck; Xu, Hairuo; Yin, Fenfang; Chin, Wee Shong

2012-01-01

A simple preparation of metal sulfide nanoparticles via the decomposition of thiobenzoate precursors at room temperature is presented and discussed. Long chain alkylamines were found to mediate the breakdown of metal thiobenzoates, such as those containing Ag, Cu, In and Cd, to produce uniform Ag2S, Cu2−xS, In2S3 and CdS nanoparticles respectively. The long chain amines are assumed to play dual roles as the nucleophilic reagent and the capping agent. It was found that sizes of the nanoparticles can be controlled by changing the type of amine used, as well as the molar ratio between amine and the precursor. We performed DFT calculations on a proposed mechanism involving an initial nucleophilic addition of amine molecule onto the thiocarboxylates. The proposed reaction was also confirmed through the analysis of by-products via infrared spectroscopy. On the basis of this understanding, we propose to manipulate the stability of the precursors by coordination with suitable stabilizing groups, such that the reaction kinetics can be modified to generate different nanostructures of interest. PMID:28348299

Silica-alumina trihydrate filled epoxy castings resistant to arced SF.sub.6

DOEpatents

Chenoweth, Terrence E.; Yeoman, Frederick A.

1978-01-01

A cured, insulating, casting composition, having a coefficient of linear thermal expansion of below about 38 .times. 10.sup.-6 in./in./.degree. C and being resistant to arced sulfur hexafluoride gas, in contact with a metal surface in a sulfur hexafluoride gas environment, is made from hydantoin epoxy resin, anhydride curing agent and a filler combination of fused silica and alumina trihydrate.

The Artificial Eye: A Focal Plane Detector/Read-Out IC Imaging Array Fabrication on Interior Spherical Surfaces

DTIC Science & Technology

2008-08-07

photolithography. A curing agent and PDMS prepolymer were thoroughly mixed at a 1:7 weight ratio, followed by degassing for lh to remove all air bubbles and to...ensure complete mixing. The prepolymer was then poured onto the Si master and cured at 100°C for lh to form a stamp with duplicated patterns from the

Bond strength of a pit-and-fissure sealant associated to etch-and-rinse and self-etching adhesive systems to saliva-contaminated enamel: individual vs. simultaneous light curing.

PubMed

Gomes-Silva, Jaciara Miranda; Torres, Carolina Paes; Contente, Marta Maria Martins Giamatei; Oliveira, Maria Angélica Hueb de Menezes; Palma-Dibb, Regina Guenka; Borsatto, Maria Cristina

2008-01-01

This study evaluated in vitro the shear bond strength (SBS) of a resin-based pit-and-fissure sealant [Fluroshield (F), Dentsply/Caulk] associated with either an etch-and-rinse [Adper Single Bond 2 (SB), 3M/ESPE] or a self-etching adhesive system [Clearfil S3 Bond (S3), Kuraray Co., Ltd.] to saliva-contaminated enamel, comparing two curing protocols: individual light curing of the adhesive system and the sealant or simultaneous curing of both materials. Mesial and distal enamel surfaces from 45 sound third molars were randomly assigned to 6 groups (n=15), according to the bonding technique: I - F was applied to 37% phosphoric acid etched enamel. The other groups were contaminated with fresh human saliva (0.01 mL; 10 s) after acid etching: II - SB and F were light cured separately; III - SB and F were light cured together; IV - S3 and F were light cured separately; V - S3 and F were light cured simultaneously; VI - F was applied to saliva-contaminated, acid-etched enamel without an intermediate bonding agent layer. SBS was tested to failure in a universal testing machine at 0.5 mm/min. Data were analyzed by one-way ANOVA and Fisher's test (alpha=0.05).The debonded specimens were examined with a stereomicroscope to assess the failure modes. Three representative specimens from each group were observed under scanning electron microscopy for a qualitative analysis. Mean SBS in MPa were: I-12.28 (+/-4.29); II-8.57 (+/-3.19); III-7.97 (+/-2.16); IV-12.56 (+/-3.11); V-11.45 (+/-3.77); and VI-7.47 (+/-1.99). In conclusion, individual or simultaneous curing of the intermediate bonding agent layer and the resin sealant did not seem to affect bond strength to saliva-contaminated enamel. S3/F presented significantly higher SBS than the that of the groups treated with SB etch-and-rinse adhesive system and similar SBS to that of the control group, in which the sealant was applied under ideal dry, noncontaminated conditions.

Effect of amine structure on CO2 capture by polymeric membranes.

PubMed

Taniguchi, Ikuo; Kinugasa, Kae; Toyoda, Mariko; Minezaki, Koki

2017-01-01

Poly(amidoamine)s (PAMAMs) incorporated into a cross-linked poly(ethylene glycol) exhibited excellent CO 2 separation properties over H 2 . However, the CO 2 permeability should be increased for practical applications. Monoethanolamine (MEA) used as a CO 2 determining agent in the current CO 2 capture technology at demonstration scale was readily immobilized in poly(vinyl alcohol) (PVA) matrix by solvent casting of aqueous mixture of PVA and the amine. The resulting polymeric membranes can be self-standing with the thickness above 3 μm and the amine fraction less than 80 wt%. The gas permeation properties were examined at 40 °C and under 80% relative humidity. The CO 2 separation performance increased with increase of the amine content in the polymeric membranes. When the amine fraction was 80 wt%, the CO 2 permeability coefficient of MEA containing membrane was 604 barrer with CO 2 selectivity of 58.5 over H 2 , which was much higher than the PAMAM membrane (83.7 barrer and 51.8, respectively) under the same operation conditions. On the other hand, ethylamine (EA) was also incorporated into PVA matrix to form a thin membrane. However, the resulting polymeric membranes exhibited slight CO 2 -selective gas permeation properties. The hydroxyl group of MEA was crucial for high CO 2 separation performance.

Effect of amine structure on CO2 capture by polymeric membranes

PubMed Central

Taniguchi, Ikuo; Kinugasa, Kae; Toyoda, Mariko; Minezaki, Koki

2017-01-01

Abstract Poly(amidoamine)s (PAMAMs) incorporated into a cross-linked poly(ethylene glycol) exhibited excellent CO2 separation properties over H2. However, the CO2 permeability should be increased for practical applications. Monoethanolamine (MEA) used as a CO2 determining agent in the current CO2 capture technology at demonstration scale was readily immobilized in poly(vinyl alcohol) (PVA) matrix by solvent casting of aqueous mixture of PVA and the amine. The resulting polymeric membranes can be self-standing with the thickness above 3 μm and the amine fraction less than 80 wt%. The gas permeation properties were examined at 40 °C and under 80% relative humidity. The CO2 separation performance increased with increase of the amine content in the polymeric membranes. When the amine fraction was 80 wt%, the CO2 permeability coefficient of MEA containing membrane was 604 barrer with CO2 selectivity of 58.5 over H2, which was much higher than the PAMAM membrane (83.7 barrer and 51.8, respectively) under the same operation conditions. On the other hand, ethylamine (EA) was also incorporated into PVA matrix to form a thin membrane. However, the resulting polymeric membranes exhibited slight CO2-selective gas permeation properties. The hydroxyl group of MEA was crucial for high CO2 separation performance. PMID:29383045

Transparent ceramics and methods of preparation thereof

DOEpatents

Hollingsworth, Joel P.; Kuntz, Joshua D.; Seeley, Zachary M.; Soules, Thomas F.

2012-12-25

A method for forming a transparent ceramic preform in one embodiment includes forming a suspension of oxide particles in a solvent, wherein the suspension includes a dispersant, with the proviso that the suspension does not include a gelling agent; and uniformly curing the suspension for forming a preform of gelled suspension. A method according to another embodiment includes creating a mixture of inorganic particles, a solvent and a dispersant, the inorganic particles having a mean diameter of less than about 2000 nm; agitating the mixture; adding the mixture to a mold; and curing the mixture in the mold for gelling the mixture, with the proviso that no gelling agent is added to the mixture.

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.

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

Jones, Brad Howard; Alam, Todd M.; Black, Hayden T

This report catalogues the results of a project exploring the incorporation of organometallic compounds into thermosetting polymers as a means to reduce their residual stress. Various syntheses of polymerizable ferro cene derivatives were attempted with mixed success. Ultimately, a diamine derivative of ferrocene was used as a curing agen t for a commercial epoxy resin, where it was found to give similar cure kinetics and mechanical properties in comparison to conventional curing agents. T he ferrocen e - based material is uniquely able to relax stress above the glass transition, leading to reduced cure stress. We propose that this behaviormore » arises from the fluxional capacity of ferrocene. In support of this notion, nuclear magnetic resonance spectroscopy indicates a substantial increase in chain flexibility in the ferrocene - containing network. Although t he utilization of fluxionality is a novel approach to stress management in epoxy thermosets, it is anticipated to have greater impact in radical - cured ther mosets and linear polymers.« less

Encapsulant materials and associated devices

DOEpatents

Kempe, Michael D [Littleton, CO; Thapa, Prem [Lima, OH

2011-03-08

Compositions suitable for use as encapsulants are described. The inventive compositions include a high molecular weight polymeric material, a curing agent, an inorganic compound, and a coupling agent. Optional elements include adhesion promoting agents, colorants, antioxidants, and UV absorbers. The compositions have desirable diffusivity properties, making them suitable for use in devices in which a substantial blocking of moisture ingress is desired, such as photovoltaic (PV) modules.

Encapsulant materials and associated devices

DOEpatents

Kempe, Michael D [Littleton, CO; Thapa, Prem [Lima, OH

2012-05-22

Compositions suitable for use as encapsulants are described. The inventive compositions include a high molecular weight polymeric material, a curing agent, an inorganic compound, and a coupling agent. Optional elements include adhesion promoting agents, colorants, antioxidants, and UV absorbers. The compositions have desirable diffusivity properties, making them suitable for use in devices in which a substantial blocking of moisture ingress is desired, such as photovoltaic (PV) modules.

Experimental study on the foundation of soft soil solidification formula based on the Design - Expert software search

NASA Astrophysics Data System (ADS)

Qian, Chaojun; Li, Dahua; Zhang, xian; Zhou, Dongqing; Zhang, Baoliang

2017-08-01

Xuan city + 1100 kv search for converter station in Anhui province, in the process of foundation treatment, there is a cloth with a large number of lacustrine soft soil can not reach the need of engineering construction, so we want to cure the soft soil. By combining ratio of blast furnace slag (GGBS), gypsum, exciting agent CaO as a main curing agent for combination of reinforcing soft soil, the indoor unconfined compressive strength test, the influence factors on blast furnace slag, exciting agent and dosage of gypsum as impact factors, response value is 7 d and 28 d unconfined compressive strength of solidified soil, the experimental method is the Box - Behnken. The results show that the 7 d gypsum and the interaction of the blast furnace slag is obvious; 28 d exciting agent and gypsum interaction is obvious. By the analysis plaster, CaO, GGBSIn 7 d optimal proportion is 3.71%, 3.62%, 12.18%, the actual strength of the solidified soil age 1479.33 kPa; 28 d optimal proportion was 4.08%, 4.50%, 11.6%, the actual strength of the solidified soil age 2936.78 kPa. In the soil and the water curing effect of GGBS solidified soil, thereby GGBS this is a kind of new solidification material that can be used as the engineering foundation treatment of soft soil stabilizer has a certain value.

Functional copolymer/organo-MMT nanoarchitectures. VI. Synthesis and characterization of novel nanocomposites by interlamellar controlled/living radical copolymerization via preintercalated RAFT-agent/organoclay complexes.

PubMed

Rzayev, Zakir M O; Söylemez, A Ernur

2011-04-01

We have developed a new approach for the synthesis of polymer nanocomposites using a bifunctional reversible addition-fragmentation chain transfer (RAFT) agent, two types of organo-montmorillonites, such as a non-reactive dimethyldodecyl ammonium (DMDA)-MMT and a reactive octadecylamine (ODA)-MMT organoclays, and a radical initiator. The method includes the following stages: (1) synthesis of RAFT intercalated O-MMTs by a physical or chemical interaction of the RAFT agent having two pendant carboxylic groups [S,S-bis(alpha,alpha'-dimethyl-alpha"-acetic acid)trithiocarbonate] with surface alkyl amines of O-MMT containing tertiary ammonium cation or primary amine groups through strong H-bonding and complexing/amidization reactions, respectively, and (2) utilization of these well-dispersed and intercalated RAFT ... O-MMT complexes and their amide derivatives as new modified RAFT agents in radical-initiated interlamellar controlled/living copolymerization of itaconic acid (IA)-n-butylmethacrylate (BMA) monomer pair. The structure and compositions of the synthesized RAFT ... O-MMT complexes and functional copolymer/O-MMT hybrids were confirmed by FTIR, XRD, thermal (DSC-TGA), SEM and TEM morphology analyses. It was demonstrated that the degree of interaction/exfoliation, morphology and thermal behavior of nanocomposites significantly depended on the type of organoclay and in situ interaction, as well as on the content of flexible butyl-ester linkages as a internal plasticizer. The results of the comparative analysis of the nanocomposites structure-composition-property relations show that the functional copolymer-organoclay hybrids prepared with reactive RAFT ... ODA-MMT complex and containing a combination of partially intercalated and predominantly exfoliated nano-structures exhibit relatively higher thermal stability and fine dispersed morphology. These effects were explained by in situ interfacial chemical reactions through amidization of RAFT with surface alkyl amine of MMT clay in interlamellar copolymerization. This simple and versatile method can be applied to a wide range of functional monomer/comonomer systems and mono- and bifunctional RAFT compounds for preparation new generation of nanomaterials.

Design of amine modified polymer dispersants for liquid-phase exfoliation of transition metal dichalcogenide nanosheets and their photodetective nanocomposites

NASA Astrophysics Data System (ADS)

Lee, Jinseong; Hahnkee Kim, Richard; Yu, Seunggun; Babu Velusamy, Dhinesh; Lee, Hyeokjung; Park, Chanho; Cho, Suk Man; Jeong, Beomjin; Sol Kang, Han; Park, Cheolmin

2017-12-01

Liquid-phase exfoliation (LPE) of transition metal dichalcogenide (TMD) nanosheets is a facile, cost-effective approach to large-area photoelectric devices including photodetectors and non-volatile memories. Non-destructive exfoliation of nanosheets using macromolecular dispersing agents is beneficial in rendering the TMD nanocomposite films suitable for mechanically flexible devices. Here, an efficient LPE of molybdenum disulfide (MoS2) with an amine modified poly(styrene-co-maleic anhydride) co-polymer (AM-PSMA) is demonstrated, wherein the maleic anhydrides were converted into maleic imides with primary amines using N-Boc-(CH2) n -NH2. The exfoliation of nanosheets was facilitated through Lewis acid-base interaction between the primary amine and transition metal. The results demonstrate that the exfoliation depends upon both the fraction of primary amines in the polymer chain and their distance from the polymer backbone. Under optimized conditions of primary amine content and its distance from the backbone, AM-PSMA gave rise to a highly concentrated MoS2 nanosheet suspension that was stable for over 10 d. Exfoliation of several other TMDs was also achieved using the optimized AM-PSMA, indicating the scope of AM-PSMA applications. Furthermore, a flexible composite film of AM-PSMA and MoS2 nanosheets fabricated by vacuum-assisted filtration showed excellent photoconductive performances including a high I on/I off ratio of 102 and a fast photocurrent switching of 300 ms.

Surface grafting of poly(ethylene glycol) onto poly(acrylamide-co-vinyl amine) cross-linked films under mild conditions.

PubMed

Yamamoto, Y; Sefton, M V

1998-01-01

Poly(ethylene glycol) (PEG) was grafted onto poly(acrylamide-co-vinyl amine) (poly(AM-co-VA)) film using tresylated PEG (TPEG) at 37 degrees C in aqueous buffers (pH 7.4) with a view to surface-modifying microencapsulated mammalian cells. Poly(AM-co-VA) film was synthesized by Hofmann degradation of a cross-linked poly(acrylamide) film. Conversion to vinyl amine on the surface of the film was approximately 50%, but bulk conversion was not observed; surface specificity was thought to be the result of cleavage of aminated polymer chains at the surface due to chain scission. Reaction between primary amine and TPEG gave a graft yield of 2 mol% (based on XPS) with respect to available surface amine groups, equivalent to 54 mol% ethylene oxide based on monomer units. Physical adsorption of non-activated polymer was done under identical conditions as a control and the difference in oxygen content was significant compared to TPEG. The type of buffer agent and buffer concentration did not influence graft yields. This graft reaction, which was completed in as little as 2 h was considered to be mild enough to be used for a surface modification of microcapsules containing cells without affecting their viability. Such a surface modification technique may prove to be a useful means of enhancing the biocompatibility of microcapsules (or any tissue engineering construct) even after cell encapsulation or seeding.

Poly-l-Lactic Acid Nanofiber-Polyamidoamine Hydrogel Composites: Preparation, Properties, and Preliminary Evaluation as Scaffolds for Human Pluripotent Stem Cell Culturing.

PubMed

Gualandi, Chiara; Bloise, Nora; Mauro, Nicolò; Ferruti, Paolo; Manfredi, Amedea; Sampaolesi, Maurilio; Liguori, Anna; Laurita, Romolo; Gherardi, Matteo; Colombo, Vittorio; Visai, Livia; Focarete, Maria Letizia; Ranucci, Elisabetta

2016-10-01

Electrospun poly-l-lactic acid (PLLA) nanofiber mats carrying surface amine groups, previously introduced by nitrogen atmospheric pressure nonequilibrium plasma, are embedded into aqueous solutions of oligomeric acrylamide-end capped AGMA1, a biocompatible polyamidoamine with arg-gly-asp (RGD)-reminiscent repeating units. The resultant mixture is finally cured giving PLLA-AGMA1 hydrogel composites that absorb large amounts of water and, in the swollen state, are translucent, soft, and pliable, yet as strong as the parent PLLA mat. They do not split apart from each other when swollen in water and remain highly flexible and resistant, since the hydrogel portion is covalently grafted onto the PLLA nanofibers via the addition reaction of the surface amine groups to a part of the terminal acrylic double bonds of AGMA1 oligomers. Preliminary tested as scaffolds, the composites prove capable of maintaining short-term undifferentiated cultures of human pluripotent stem cells in feeder-free conditions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Highly Functionalized 1,2–Diamino Compounds through Reductive Amination of Amino Acid-Derived β–Keto Esters

PubMed Central

Pérez-Faginas, Paula; Aranda, M. Teresa; García-López, M. Teresa; Infantes, Lourdes; Fernández-Carvajal, Asia; González-Ros, José Manuel; Ferrer-Montiel, Antonio; González-Muñiz, Rosario

2013-01-01

1,2-Diamine derivatives are valuable building blocks to heterocyclic compounds and important precursors of biologically relevant compounds. In this respect, amino acid-derived β–keto esters are a suitable starting point for the synthesis of β,γ–diamino ester derivatives through a two-step reductive amination procedure with either simple amines or α–amino esters. AcOH and NaBH3CN are the additive and reducing agents of choice. The stereoselectivity of the reaction is still an issue, due to the slow imine-enamine equilibria through which the reaction occurs, affording mixtures of diastereoisomers that can be chromatographically separated. Transformation of the β,γ–diamino esters into pyrrolidinone derivatives allows the configuration assignment of the linear compounds, and constitutes an example of their potential application in the generation of molecular diversity. PMID:23308167

Facile synthesis of microporous SiO2/triangular Ag composite nanostructures for photocatalysis

NASA Astrophysics Data System (ADS)

Sirohi, Sidhharth; Singh, Anandpreet; Dagar, Chakit; Saini, Gajender; Pani, Balaram; Nain, Ratyakshi

2017-11-01

In this article, we present a novel fabrication of microporous SiO2/triangular Ag nanoparticles for dye (methylene blue) adsorption and plasmon-mediated degradation. Microporous SiO2 nanoparticles with pore size <2 nm were synthesized using cetyltrimethylammonium bromide as a structure-directing agent and functionalized with APTMS ((3-aminopropyl) trimethoxysilane) to introduce amine groups. Amine-functionalized microporous silica was used for adsorption of triangular silver (Ag) nanoparticles. The synthesized microporous SiO2 nanostructures were investigated for adsorption of different dyes including methylene blue, congo red, direct green 26 and curcumin crystalline. Amine-functionalized microporous SiO2/triangular Ag nanostructures were used for plasmon-mediated photocatalysis of methylene blue. The experimental results revealed that the large surface area of microporous silica facilitated adsorption of dye. Triangular Ag nanoparticles, due to their better charge carrier generation and enhanced surface plasmon resonance, further enhanced the photocatalysis performance.

Rapid Prototyping of Composite Structures

NASA Technical Reports Server (NTRS)

Colton, Jonathan S.

1998-01-01

This progress report for the project Rapid Production of Composite Structures covers the period from July 14, 1997 to June 30, 1998. It will present a short overview of the project, followed by the results to date and plans for the future. The goal of this research is to provide a minimum 100x reduction in the time required to produce arbitrary, laminated products without the need for a separate mold or an autoclave. It will accomplish this by developing the science underlying the rapid production of composite structures, specifically those of carbon fiber-epoxy materials. This scientific understanding will be reduced to practice in a demonstration device that will produce a part on the order of 12" by 12" by 6". Work in the past year has focussed on developing an understanding of the materials issues and of the machine design issues. Our initial goal was to use UV cureable resins to accomplish full cure on the machine. Therefore, we have centered our materials work around whether or not UV cureable resins will work. Currently, the answer seems to be that they will not work, because UV light cannot penetrate the carbon fibers, and because no "shadow" curing seems to occur. As a result, non-UV cureable resins are being investigated. This has resulted in a change in the machine design focus. We are now looking into a "dip and place" machine design, whereby a prepreg layer would have one side coated with a curing agent, and then would be placed onto the previous layer. This would lead to cure at the interface, but not to the top of the layer. The formulation of the resins to accomplish this task at room or slightly elevated temperatures is being investigated, as is the machine design needed to apply the curing agent and then cure or partially cure the part. A final, out-of-autoclave, post-cure may be needed with this strategy, as final cure on the machine may not be possible, as it was for the initial UV cure strategy. The remainder of this report details the progress in the materials and machine design areas. Materials Development The material system must be designed to fulfill the following requirements: to reduce the time and labor requirements of typical cure cycles; to reduce the thermal stresses developed during conventional heat curing; and to develop a structure that the build sequence requires. In order to accomplish these goals, there have been parallel tracks of investigation. One area has tested photopolymerizable (ultraviolet (UV) curable) materials and combinations of these materials with standard heat curing resins. The second area has investigated resins that cure rapidly at room or low heat temperatures. The main goal of these investigations has been to identify a system that will rapidly set or cure at room temperature during a tape lay-up process and hold its structure during a post-cure cycle.

Polyethylene glycol grafted polyethylene: a versatile platform for nonmigratory active packaging applications.

PubMed

Barish, Jeffrey A; Goddard, Julie M

2011-01-01

Nonmigratory active packaging, in which bioactive components are tethered to the package, offers the potential to reduce the need for additives in food products while maintaining safety and quality. A challenge in developing nonmigratory active packaging materials is the loss of biomolecular activity that can occur when biomolecules are immobilized. In this work, we describe a method in which a biocompatible polymer (polyethylene glycol, PEG) is grafted from the surface of ozone-treated low-density polyethylene (LDPE) resulting in a surface functionalized polyethylene to which a range of amine-terminated bioactive molecules can be immobilized. Free radical graft polymerization is used to graft PEG onto the LDPE surface, followed by immobilization of ethylenediamine onto the PEG tether. Ethylenediamine was used to demonstrate that amine-terminated molecules could be covalently attached to the PEG-grafted film. Changes in surface chemistry and topography were measured by attenuated total reflectance Fourier transform infrared spectroscopy, contact angle, atomic force microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. We demonstrate the ability to graft PEG onto the surface of polymer packaging films by free radical graft polymerization, and to covalently link an amine-terminated molecule to the PEG tether, demonstrating that amine-terminated bioactive compounds (such as peptides, enzymes, and some antimicrobials) can be immobilized onto PEG-grafted LDPE in the development of nonmigratory active packaging.   Nonmigratory active packaging offers the potential for improving food safety and quality while minimizing the migration of the active agent into food. In this paper, we describe a technique to modify polyethylene packaging films such that active agents can be covalently immobilized by a biocompatible tether. Such a technique can be adapted to a number of applications such as antimicrobial, antioxidant, or immobilized enzyme active packaging. © 2011 Institute of Food Technologists®

Developing testing methods for characterizing emissions and sources of exposures from polyurehane products

EPA Science Inventory

The relationship between onsite manufacture of spray polyurethane foam insulation (SPFI) and potential exposures to diisocyanate compounds, amine catalysts, flame retardants, and blowing agents, as well as aldehydes and other volatile or semivolatile organic compounds that may be...

Long-term follow-up of bulking agents for stress urinary incontinence in older patients.

PubMed

Plotti, Francesco; Montera, Roberto; Terranova, Corrado; Luvero, Daniela; Marrocco, Francesca; Miranda, Andrea; Gatti, Alessandra; De Cicco Nardone, Carlo; Angioli, Roberto; Scaletta, Giuseppe

2018-06-01

Implantation of bulking agents represents a noninvasive procedure for the treatment of stress urinary incontinence (SUI) in all patients where a more invasive procedure may increase perioperative risks. The primary aim of this retrospective study was to evaluate the efficacy over time of bulking agent implantation. As secondary aims, we evaluated long-term (patients' subjective) satisfaction rate, rate of de novo urinary symptoms, and the impact of urinary incontinence on the quality of life. All patients who underwent implantation of bulking agents between 1999 and 2013 at Campus Bio-Medico of Rome were retrospectively considered eligible for this study. Patients were interviewed using two standardized questionnaires: International Consultation on Incontinence Questionnaire Short Form and Patient Global Impression of Improvement. Cure rate, improvement rate, failure rate, and the onset of new symptoms were also investigated through specific questions. The original group of patients was then divided into two subgroups according to follow-up time (group A: shorter than median follow-up; group B: longer than median follow-up). Sixty-three patients were enrolled. Mean follow-up was 8.3 ± 3.5 years with a range of 3.5 to 18 years. Fifteen (24%) cured patients (cure rate), 12 (19%) improved patients (improvement rate), 36 (57%) failed treatment (failure rate). We reported an overall success rate of 43%. No differences were reported among groups in terms of overall success rate (42% vs 44% for group A and group B, respectively). Bulking agent implantation is an effective treatment for people with intrinsic sphincter deficiency (type III SUI) and it is a valid alternative to more invasive surgeries in older patients. Moreover, it shows an overall success rate (43%) that remains high even after many years.

Synthesis and biological evaluation of radio and dye labeled amino functionalized dendritic polyglycerol sulfates as multivalent anti-inflammatory compounds.

PubMed

Gröger, Dominic; Paulus, Florian; Licha, Kai; Welker, Pia; Weinhart, Marie; Holzhausen, Cornelia; Mundhenk, Lars; Gruber, Achim D; Abram, Ulrich; Haag, Rainer

2013-09-18

Herein we describe a platform technology for the synthesis and characterization of partially aminated, (35)S-labeled, dendritic polyglycerol sulfate (dPG(35)S amine) and fluorescent dPGS indocarbocyanine (ICC) dye conjugates. These polymer conjugates, based on a biocompatible dendritic polyglycerol scaffold, exhibit a high affinity to inflamed tissue in vivo and represent promising candidates for therapeutic and diagnostic applications. By utilizing a one-step sequential copolymerization approach, dendritic polyglycerol (Mn ≈ 4.5 kDa) containing 9.4% N-phthalimide protected amine functionalities was prepared on a large scale. Sulfation and simultaneous radio labeling with (35)SO3 pyridine complex, followed by cleavage of the N-phthalimide protecting groups, yielded dPG(35)S amine as a beta emitting, inflammation specific probe with free amino functionalities for conjugation. Furthermore, efficient labeling procedures with ICC via iminothiolane modification and subsequent "Michael" addition of the maleimide functionalized ICC dye, as well as by amide formation via NHS derivatized ICC on a dPGS amine scaffold, are described. The dPGS-ICC conjugates were investigated with respect to their photophysical properties, and both the radiolabeled and fluorescent compounds were comparatively visualized in histological tissue sections (radio detection and fluorescence microscopy) of animals treated with dPGS. Furthermore, cellular uptake of dPGS-ICC was found in endothelial cord blood (HUVEC) and the epithelial lung cells (A549). The presented synthetic routes allow a reproducible, controlled synthesis of dPGS amine on kilogram scale applying a one-pot batch reaction process. dPGS amine can be used for analysis via radioactivity or fluorescence, thereby creating a new platform for inflammation specific, multimodal imaging purposes using other attachable probes or contrast agents.

Dietary trace amine-dependent vasoconstriction in porcine coronary artery

PubMed Central

Herbert, A A; Kidd, E J; Broadley, K J

2008-01-01

Background and purpose: The dietary trace amines tyramine and β-phenylethylamine (β-PEA) can increase blood pressure. However, the mechanisms involved in the vascular effect of trace amines have not been fully established. The purpose of this study was to evaluate whether trace amine-dependent vasoconstriction was brought about by tyramine and β-PEA acting as indirect sympathomimetic agents, as previously assumed, or whether trace amine-dependent vasoconstriction could be mediated by recently discovered trace amine-associated (TAA) receptors. Experimental approach: The responses to p-tyramine and β-PEA were investigated in vitro in rings of the left anterior descending coronary arteries of pigs. Key results: p-Tyramine induced a concentration-dependent (0.1–3 mM) vasoconstriction. The maximum response and pD2 value for p-tyramine was unaffected by endothelium removal or pre-treatment with antagonists for adrenoceptors, histamine, dopamine or 5-HT receptors. β-PEA also produced a concentration-dependent (0.3–10 mM) vasoconstriction which was unaffected by endothelium removal, β-adrenoceptor or 5-HT receptor antagonists. A substantial, but reduced, response to β-PEA was obtained in the presence of prazosin (α1-adrenoceptor antagonist), haloperidol (D2/D3 dopamine receptor antagonist) or mepyramine (H1 histamine receptor antagonist). The pD2 value for β-PEA was unaffected by any of the antagonists tested. Conclusions and implications: Vasoconstriction induced by p-tyramine does not involve an indirect sympathomimetic effect, although vasoconstriction caused by β-PEA may occur, in part, by this mechanism. We therefore propose that trace amine-dependent vasoconstriction is mediated by phenylethylamine-specific receptors, which are closely related to or identical to TAA receptors. These receptors could provide a target for new antihypertensive therapies. PMID:18604230

Method for chemically inactivating energetic materials and forming a nondetonable product therefrom

DOEpatents

Tadros, Maher E.

2002-01-01

A method for rendering nondetonble energetic materials, such as are contained in or removed from decommissioned ordnance. The energetic materials are either combined with epoxy hardener or are combined with other compounds, preferably amine compounds, to form a substance that functions as an epoxy hardener. According to the invention, energetic materials (including TNT, RDX and Composition B) that are treated according to the invention method yield a reaction product that is non-explosive, that serves to harden or cure conventional epoxy resin to form a stable, nonexplosive waste product. Epoxy hardener made using the method of the invention is also described.

Participation in HIV cure-related research: a scoping review of the proxy literature and implications for future research.

PubMed

Dubé, Karine; Ramirez, Catalina; Handibode, Jessica; Taylor, Jeffrey; Skinner, Asheley; Greene, Sandra; Tucker, Joseph D

2015-10-01

To identify the main types of HIV cure-related strategies and examine possible risks (and benefits) associated with participating in HIV cure-related research studies. We undertook a scoping review to first map out the landscape of HIV cure-related research and then examined the risks and potential benefits associated with participating in HIV cure research. Given the early stage of many HIV cure-related studies, we used proxy literatures from non-cure HIV research and cancer research in order to anticipate possible motivators and deterrents of participation in HIV cure-related studies. We discussed four main categories of HIV cure-related research: (1) early antiretroviral treatment (ART); (2) latency-reversing agents (LRAs); (3) therapeutic vaccinations and immune-based therapies (IBT); and (4) stem-cell transplantation and gene therapy. At this juncture, these categories of HIV cure-related research have substantial individual risks and negligible individual and clinical benefits. Non-cure HIV research (including HIV prevention and treatment) and cancer research have empirical similarities (and differences) to HIV cure research and may provide an opportunity to anticipate ethical and logistical challenges associated with HIV cure-related research participation and decision-making. Learning from the cancer field, a strong foundation of patient-participant and clinician-researcher trust will need to be established to facilitate recruitment of participants into HIV cure-related studies. Further empirical social science and ethics research will be necessary to inform clinical HIV cure-related research. The study of participation in HIV cure-related research can gain insights from proxy fields by incorporating study elements to clearly explain motivators and deterrents to participation and to inform the implementation of HIV cure-related studies. Study-specific contexts from the reviewed literature further demonstrate the importance of various types of research to assess factors affecting participation in HIV cure-related research, including adequate formative and ethics research.

Functionalized graphene oxide quantum dot-PVA hydrogel: a colorimetric sensor for Fe2+, Co2+ and Cu2+ ions

NASA Astrophysics Data System (ADS)

Baruah, Upama; Chowdhury, Devasish

2016-04-01

Functionalized graphene oxide quantum dots (GOQDs)-poly(vinyl alcohol) (PVA) hybrid hydrogels were prepared using a simple, facile and cost-effective strategy. GOQDs bearing different surface functional groups were introduced as the cross-linking agent into the PVA matrix thereby resulting in gelation. The four different types of hybrid hydrogels were prepared using graphene oxide, reduced graphene oxide, ester functionalized graphene oxide and amine functionalized GOQDs as cross-linking agents. It was observed that the hybrid hydrogel prepared with amine functionalized GOQDs was the most stable. The potential applicability of using this solid sensing platform has been subsequently explored in an easy, simple, effective and sensitive method for optical detection of M2+ (Fe2+, Co2+ and Cu2+) in aqueous media involving colorimetric detection. Amine functionalized GOQDs-PVA hybrid hydrogel when put into the corresponding solution of Fe2+, Co2+ and Cu2+ renders brown, orange and blue coloration respectively of the solution detecting the presence of Fe2+, Co2+ and Cu2+ ions in the solution. The minimum detection limit observed was 1 × 10-7 M using UV-visible spectroscopy. Further, the applicability of the sensing material was also tested for a mixture of co-existing ions in solution to demonstrate the practical applicability of the system. Insight into the probable mechanistic pathway involved in the detection process is also being discussed.

NITRILE ELASTOMER-NYLON LAMINATES INCLUDING BARRIER FILMS.

DTIC Science & Technology

ADHESIVES, *NYLON, *NITRILE RUBBER , LAMINATES, LAMINATES, FILMS, TEXTILES, RUBBER COATINGS, BUTADIENES, ACRYLONITRILE POLYMERS, BONDING, ADHESION... DEGRADATION , MOISTUREPROOFING, PHENOLIC PLASTICS, HALOGENATED HYDROCARBONS, ISOCYANATES, CURING AGENTS, ELASTOMERS.

Agent-Based Models and Optimal Control in Biology: A Discrete Approach

DTIC Science & Technology

2012-01-01

different parts of the human body to cure diseases such as hypertension, cancer, or heart disease. And we need to control microbes for the efficient...antelope herd interacts with an aggregated prey agent such as cheetahs or lions, the size of each may expand or contract accordingly). Of course, such

Aqueous vinylidene fluoride polymer coating composition

NASA Technical Reports Server (NTRS)

Bartoszek, Edward J. (Inventor); Christofas, Alkis (Inventor)

1978-01-01

A water-based coating composition which may be air dried to form durable, fire resistant coatings includes dispersed vinylidene fluoride polymer particles, emulsified liquid epoxy resin and a dissolved emulsifying agent for said epoxy resin which agent is also capable of rapidly curing the epoxy resin upon removal of the water from the composition.

Development of test systems for characterizing emissions from spray polyurethane foam insulation (SPFI)

EPA Science Inventory

The relationship between onsite manufacture of spray polyurethane foam insulation (SPFI) and potential exposures to diisocyanates, amines, flame retardants (FRs), blowing agents, aldehydes and other organic compounds that may be emitted from SPFI is not well understood. EPA is de...

Problems encountered with conventional fiber-reinforced composites

NASA Technical Reports Server (NTRS)

Landel, R. F.

1981-01-01

Preparational, computational, and operational problems associated with fiber-reinforced composites (FRC) are reviewed. Initial preparation of FRCs is shown to involve consideration of the type of prepreg, the setting time, cure conditions and cycles, and cure temperatures. The effects of the choice of bonding agents, the fiber transfer length, and individual fiber responses to bonding agents are noted to have an impact on fiber strength, moisture uptake, and fatigue resistance. The deformation prior to failure and the failure region are modeled through models of mini-, micro- and macro mechanics formulations employing a stiffness matrix, failure criterion, or fracture mechanics. The detection, evaluation, and repair of defects comprises the operational domain, and it is stressed that no good repair techniques exist for FRCs.

Environmental Exposures, Genetic Polymorphisms and p53 Mutational Spectra in a Case-Control Study of Breast Cancer.

DTIC Science & Technology

1997-01-01

frequently reported in premenopausal rather than postmenopausal women. It is currently unknown what might be the carcinogenic agents in alcoholic... agents in human main-that they could affect heterogeneity of Breast cancer and cigarette smoking. N Engl J mary epithelial cells. CancerRes. 1992;52:5617...trosamines, polycyclic aromatic hydrocarbons, aryl aro- Abbreviations: NMU, N-methyl-N- nitrosourea ; CYP2E1, cytochrome matic amines, and heterocyclic

Enhanced phenol-photodegradation by particulate semiconductor mixtures: interparticle electron-jump.

PubMed

Karunakaran, C; Dhanalakshmi, R; Gomathisankar, P; Manikandan, G

2010-04-15

Degradation of phenol on suspended TiO(2), ZnO, CdO, Fe(2)O(3), CuO, ZnS and Nb(2)O(5) particles under UV-A light exhibit identical photokinetic behavior; follow first-order kinetics, display linear dependence on the photon flux and slowdown with increase of pH. All the semiconductors show sustainable photocatalytic activity. Dissolved O(2) is essential for the photodegradation and oxidizing agents like H(2)O(2), Na(2)BO(3), K(2)S(2)O(8), KBrO(3), KIO(3) and KIO(4), reducing agents such as NaNO(2) and Na(2)SO(3) and sacrificial electron donors like hydroquinone, diphenyl amine and trimethyl amine enhance the degradation. However, the photocatalysis is insensitive to pre-sonication. Two particulate semiconductors present together, under suspension and at continuous motion, enhance the photocatalytic degradation up to about four-fold revealing interparticle electron-jump. 2009 Elsevier B.V. All rights reserved.

Silane surface modification for improved bioadhesion of esophageal stents

NASA Astrophysics Data System (ADS)

Karakoy, Mert; Gultepe, Evin; Pandey, Shivendra; Khashab, Mouen A.; Gracias, David H.

2014-08-01

Stent migration occurs in 10-40% of patients who undergo placement of esophageal stents, with higher migration rates seen in those treated for benign esophageal disorders. This remains a major drawback of esophageal stent therapy. In this paper, we propose a new surface modification method to increase the adhesion between self-expandable metallic stents (SEMS) and tissue while preserving their removability. Taking advantage of the well-known affinity between epoxide and amine terminated silane coupling agents with amine and carboxyl groups that are abundant in proteins and related molecules in the human body; we modified the surfaces of silicone coated esophageal SEMS with these adhesive self-assembled monolayers (SAMs). We utilized vapor phase silanization to modify the surfaces of different substrates including PDMS strips and SEMS, and measured the force required to slide these substrates on a tissue piece. Our results suggest that surface modification of esophageal SEMS via covalent attachment of protein-binding coupling agents improves adhesion to tissue and could offer a solution to reduce SEMS migration while preserving their removability.

Synthesis of valproic acid amides of a melatonin derivative, a piracetam and amantadine for biological tests.

PubMed

Chatterjie, N; Alexander, G; Wang, H

2001-10-01

Three new amide derivatives of valproic acid have been synthesized and characterized by spectrophotometric studies. The rationale for the preparation of such agents has been based on the observation that chemical combination of the anticonvulsant pharmacophore, valproic acid with amine moieties produces more effective and less toxic amides. The amine components selected in this work also exhibit neuroactivity with the prospect of these agents being biologically active in controlling not just seizures and but also possessing neuroprotective properties. We report here the synthesis and properties of the valproylamides of 5-methoxytryptamine, related to melatonin (1), of N-substituted 2-pyrrolidinone related to piracetam (2), and of adamantylamine related to amantadine (3). In preliminary tests these compounds showed low toxicity and a variety of anticonvulsive properties, including a delay in onset of activity. These compounds and their derivatives are now available to be tested additionally for control of subclinical seizures, enhancement of cognition, behavior modification and alleviation of symptoms and disorders due to neuronal damage.

Enhancement of in vitro Guayule propagation

NASA Technical Reports Server (NTRS)

Dastoor, M. N.; Schubert, W. W.; Petersen, G. R. (Inventor)

1982-01-01

A method for stimulating in vitro propagation of Guayule from a nutrient medium containing Guayule tissue by adding a substituted trialkyl amine bioinducing agent to the nutrient medium is described. Selective or differentiated propagation of shoots or callus is obtained by varying the amounts of substituted trialky amine present in the nutrient medium. The luxuriant growth provided may be processed for its poly isoprene content or may be transferred to a rooting medium for production of whole plants as identical clones of the original tissue. The method also provides for the production of large numbers of Guayule plants having identical desirable properties such as high polyisoprene levels.

Diastereoselective synthesis of furanose and pyranose substituted glycine and alanine derivatives via proline-catalyzed asymmetric α-amination of aldehydes.

PubMed

Petakamsetty, Ramu; Ansari, Anas; Ramapanicker, Ramesh

2016-11-29

A concise organocatalytic route toward the synthesis of furanose and pyranose substituted glycine and alanine derivatives is reported. These compounds are core structural units of some of the naturally available antibiotics and antifungal agents. Proline-catalyzed asymmetric α-amination of aldehydes derived from sugars is used as the key reaction to synthesize twelve sugar amino acid derivatives. The asymmetric transformations proceeded in good yields and with good to excellent diastereoselectivity. The application of the synthesized amino acids is demonstrated by synthesizing a tripeptide containing one of them. Copyright © 2016 Elsevier Ltd. All rights reserved.

Curing Effects on Interfacial Adhesion between Recycled Carbon Fiber and Epoxy Resin Heated by Microwave Irradiation

PubMed Central

Shimamoto, Daisuke; Hotta, Yuji

2018-01-01

The interfacial adhesion of recycled carbon fiber (CF) reinforced epoxy composite heated by microwave (MW) irradiation were investigated by changing the curing state of the epoxy resin. The recycled CF was recovered from the composite, which was prepared by vacuum-assisted resin transfer molding, by thermal degradation at 500 or 600 °C. Thermogravimetric analysis showed that the heating at 600 °C caused rough damage to the CF surface, whereas recycled CF recovered at 500 °C have few defects. The interfacial shear strength (IFSS) between recycled CF and epoxy resin was measured by a single-fiber fragmentation test. The test specimen was heated by MW after mixing the epoxy resin with a curing agent or pre-curing, in order to investigate the curing effects on the matrix resin. The IFSSs of the MW-irradiated samples were significantly varied by the curing state of the epoxy resin and the surface condition of recycled CF, resulting that they were 99.5 to 131.7% of oven heated samples Furthermore, rheological measurements showed that the viscosity and shrinking behaviors of epoxy resin were affected based on the curing state of epoxy resin before MW irradiation. PMID:29587422

Curing Effects on Interfacial Adhesion between Recycled Carbon Fiber and Epoxy Resin Heated by Microwave Irradiation.

PubMed

Tominaga, Yuichi; Shimamoto, Daisuke; Hotta, Yuji

2018-03-26

The interfacial adhesion of recycled carbon fiber (CF) reinforced epoxy composite heated by microwave (MW) irradiation were investigated by changing the curing state of the epoxy resin. The recycled CF was recovered from the composite, which was prepared by vacuum-assisted resin transfer molding, by thermal degradation at 500 or 600 °C. Thermogravimetric analysis showed that the heating at 600 °C caused rough damage to the CF surface, whereas recycled CF recovered at 500 °C have few defects. The interfacial shear strength (IFSS) between recycled CF and epoxy resin was measured by a single-fiber fragmentation test. The test specimen was heated by MW after mixing the epoxy resin with a curing agent or pre-curing, in order to investigate the curing effects on the matrix resin. The IFSSs of the MW-irradiated samples were significantly varied by the curing state of the epoxy resin and the surface condition of recycled CF, resulting that they were 99.5 to 131.7% of oven heated samples Furthermore, rheological measurements showed that the viscosity and shrinking behaviors of epoxy resin were affected based on the curing state of epoxy resin before MW irradiation.

Enhanced inhibition of Aspergillus niger on sedge (Lepironia articulata) treated with heat-cured lime oil.

PubMed

Matan, N; Matan, N; Ketsa, S

2013-08-01

This study aimed to examine heat curing effect (30-100°C) on antifungal activities of lime oil and its components (limonene, p-cymene, β-pinene and α-pinene) at concentrations ranging from 100 to 300 μl ml(-1) against Aspergillus niger in microbiological medium and to optimize heat curing of lime oil for efficient mould control on sedge (Lepironia articulata). Broth dilution method was employed to determine lime oil minimum inhibitory concentration, which was at 90 μl ml(-1) with heat curing at 70°C. Limonene, a main component of lime oil, was an agent responsible for temperature dependencies of lime oil activities observed. Response surface methodology was used to construct the mathematical model describing a time period of zero mould growth on sedge as functions of heat curing temperature and lime oil concentration. Heat curing of 90 μl ml(-1) lime oil at 70°C extended a period of zero mould growth on sedge to 18 weeks under moist conditions. Heat curing at 70°C best enhanced antifungal activity of lime oil against A. niger both in medium and on sedge. Heat curing of lime oil has potential to be used to enhance the antifungal safety of sedge products. © 2013 The Society for Applied Microbiology.

A New Epoxy-Based Layered Silicate Nanocomposite Using a Hyperbranched Polymer: Study of the Curing Reaction and Nanostructure Development.

PubMed

Cortés, Pilar; Fraga, Iria; Calventus, Yolanda; Román, Frida; Hutchinson, John M; Ferrando, Francesc

2014-03-04

Polymer layered silicate (PLS) nanocomposites have been prepared with diglycidyl ether of bisphenol-A (DGEBA) epoxy resin as the matrix and organically modified montmorillonite (MMT) as the clay nanofiller. Resin-clay mixtures with different clay contents (zero, two, five and 10 wt%) were cured, both isothermally and non-isothermally, using a poly(ethyleneimine) hyperbranched polymer (HBP), the cure kinetics being monitored by differential scanning calorimetry (DSC). The nanostructure of the cured nanocomposites was characterized by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM), and their mechanical properties were determined by dynamic mechanical analysis (DMA) and impact testing. The results are compared with an earlier study of the structure and properties of the same DGEBA-MMT system cured with a polyoxypropylene diamine, Jeffamine. There are very few examples of the use of HBP as a curing agent in epoxy PLS nanocomposites; here, it is found to enhance significantly the degree of exfoliation of these nanocomposites compared with those cured with Jeffamine, with a corresponding enhancement in the impact energy for nanocomposites with the low clay content of 2 wt%. These changes are attributed to the different cure kinetics with the HBP, in which the intra-gallery homopolymerization reaction is accelerated, such that it occurs before the bulk cross-linking reaction.

Exploratory Development of Corrosion Inhibiting Primers

DTIC Science & Technology

1977-07-01

Phenolic Hardener From previous studies, phenol formaldehyde resins of the novolac (two-step) type have given superior properties when used to cure epoxy...novolacs and three resole (one-step) type phenol- formaldehyde resins which also perform as epoxide curing agents. First, Model #1, as de;crihed in Section...results. Varcum 4326 resin was chosen at this stage for further use with the model systems. It is a low molecular weight phenol- formaldehyde resin used

Imide modified epoxy matrix resins

NASA Technical Reports Server (NTRS)

Scola, D. A.

1982-01-01

Results of a program designed to develop tough imide modified epoxy (IME) resins cured by bisimide amine (BIA) hardeners are presented. State of the art epoxy resin, MY720, was used. Three aromatic bisimide amines and one aromatic aliphatic BIA were evaluated. BIA's derived from 6F anhydride (3,3 prime 4,4 prime-(hexafluoro isopropyl idene) bis (phthalic anhydride) and diamines, 3,3 prime-diam nodiphenyl sulfone (3,3 prime-DDS), 4,4 prime-diamino diphenyl sulfone (4,4 prime-DDS), 1.12-dodecane diamine (1,12-DDA) were used. BIA's were abbreviated 6F-3,3 prime-DDS, 6F-4,4 prime-DDS, 6F-3,3 prime-DDS-4,4 prime DDS, and 6F-3,3 prime-DDS-1,12-DDA corresponding to 6F anhydride and diamines mentioned. Epoxy resin and BIA's (MY720/6F-3,3 prime-DDS, MY720/6F-3,3 prime-DDS-4,4 prime-DDS, MY720/6F-3,3 prime-DDS-1,12-DDA and a 50:50 mixture of a BIA and parent diamine, MY720/6F-3,3 prime-DDS/3,3 prime-DDS, MY720/6F-3,3 prime-DDS-4,4 prime-DDS/3,3 prime-DDS, MY720/6F-3,3 prime-DDS-1,12-DDA/3,3 prime-DDS were studied to determine effect of structure and composition. Effect of the addition of two commercial epoxies, glyamine 200 and glyamine 100 on the properties of several formulations was evaluated. Bisimide amine cured epoxies were designated IME's (imide modified epoxy). Physical, thermal and mechanical properties of these resins were determined. Moisture absorption in boiling water exhibited by several of the IME's was considerably lower than the state of the art epoxies (from 3.2% for the control and state of the art to 2.0 wt% moisture absorption). Char yields are increased from 20% for control and state of the art epoxies to 40% for IME resins. Relative toughness characteristics of IME resins were measured by 10 deg off axis tensile tests of Celion 6000/IME composites. Results show that IME's containing 6F-3,3 prime-DDS or 6F-3,3 prime-DDS-1,12-DDA improved the "toughness" characteristics of composites by about 35% (tensile strength), about 35% (intralaminar shear strength), and about 78% (shear strain to failure) relative to the control composite.

Integrated on-chip derivatization and electrophoresis for the rapid analysis of biogenic amines.

PubMed

Beard, Nigel P; Edel, Joshua B; deMello, Andrew J

2004-07-01

We demonstrate the monolithic integration of a chemical reactor with a capillary electrophoresis device for the rapid and sensitive analysis of biogenic amines. Fluorescein isothiocyanate (FITC) is widely employed for the analysis of amino-group containing analytes. However, the slow reaction kinetics hinders the use of this dye for on-chip labeling applications. Other alternatives are available such as o-phthaldehyde (OPA), however, the inferior photophysical properties and the UV lambdamax present difficulties when using common excitation sources leading to a disparity in sensitivity. Consequently, we present for the first time the use of dichlorotriazine fluorescein (DTAF) as a superior in situ derivatizing agent for biogenic amines in microfluidic devices. The developed microdevice employs both hydrodynamic and electroosmotic flow, facilitating the creation of a polymeric microchip to perform both precolumn derivatization and electrophoretic analysis. The favorable photophysical properties of the DTAF and its fast reaction kinetics provide detection limits down to 1 nM and total analysis times (including on-chip mixing and reaction) of <60 s. The detection limits are two orders of magnitude lower than current limits obtained with both FITC and OPA. The optimized microdevice is also employed to probe biogenic amines in real samples.

Amination of nitroazoles--a comparative study of structural and energetic properties.

PubMed

Zhao, Xiuxiu; Qi, Cai; Zhang, Lubo; Wang, Yuan; Li, Shenghua; Zhao, Fengqi; Pang, Siping

2014-01-14

In this work, 3-nitro-1H-1,2,4-triazole (1) and 3,5-dinitro-1H-pyrazole (2) were C-aminated and N-aminated using different amination agents, yielding their respective C-amino and N-amino products. All compounds were fully characterized by NMR (1H, 13C, 15N), IR spectroscopy, differential scanning calorimetry (DSC). X-ray crystallographic measurements were performed and delivered insight into structural characteristics as well as inter- and intramolecular interactions of the products. Their impact sensitivities were measured by using standard BAM fallhammer techniques and their explosive performances were computed using the EXPLO 5.05 program. A comparative study on the influence of those different amino substituents on the structural and energetic properties (such as density, stability, heat of formation, detonation performance) is presented. The results showed that the incorporation of an N-amino group into a nitroazole ring can improve nitrogen content, heat of formation and impact sensitivity, while the introduction of a C-amino group can enhance density, detonation velocity and pressure. The potential of N-amino and C-amino moieties for the design of next generation energetic materials is explored.

Dangerous liaisons: anion-induced protonation in phosphate-polyamine interactions and their implications for the charge states of biologically relevant surfaces.

PubMed

Laucirica, Gregorio; Marmisollé, Waldemar A; Azzaroni, Omar

2017-03-22

Although not always considered a preponderant interaction, amine-phosphate interactions are omnipresent in multiple chemical and biological systems. This study aims to answer questions that are still pending about their nature and consequences. We focus on the description of the charge state as surface charges constitute directing agents of the interaction of amine groups with either natural or synthetic counterparts. Our results allow us to quantitatively determine the relative affinities of HPO 4 2- and H 2 PO 4 - from the analysis of the influence of phosphates on the zeta-potential of amino-functionalized surfaces in a broad pH range. We show that phosphate anions enhance the protonation of amino groups and, conversely, charged amines induce further proton dissociation of phosphates, yielding a complex dependence of the surface effective charge on the pH and phosphate concentration. We also demonstrate that phosphate-amine interaction is specific and the modulation of surface charge occurs in the physiological phosphate concentration range, emphasizing its biochemical and biotechnological relevance and the importance of considering this veiled association in both in vivo and in vitro studies.

The Synthesis and Characterization of Tetrakis [(p - amino phenoxy) methyl] methane

NASA Astrophysics Data System (ADS)

Peng, Yongli; Zou, Qian

2017-06-01

In order to solve the shortcomings of the cured epoxy resin poor toughness, this paper proceeded from the structural design of curing agent to synthesize a special curing agent tetrakis [(p-aminophenoxy) methyl] methane which containing both Benzene ring and amino group. A Symmetric compound of tetrakis [(p - acetamidophenoxy) methyl] methane was prepared by using simple and easy to get pentaerythritoltetratosylate and acetaminophen for raw materials, after Williamson etherification reaction intermediates for synthesis of a symmetrical structure of the compound tetrakis [(p-acetamido phenoxy) methyl] methane, then hydrolysed under acidic conditions it can be tetrakis [(p-amino phenoxy) methyl] methane. The influence of reaction time, reaction temperature and reactant ratio to production yield of tetrakis [(p - acetamidophenoxy) methyl] methane was studied by orthogonal experiment of three factors and three levels, and get the optimal process parameters: the reaction time: 16 h, the reaction temperature: 170 °C, reactant ratio, 1:5. The Structure of tetrakis [(p - acetamidophenoxy) methyl] methane and tetrakis [(p-amino phenoxy) methyl] methane were characterized by infrared and 1H-NMR.

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

Fatigue crack propagation in self-assembling nanocomposites

NASA Astrophysics Data System (ADS)

Klingler, Andreas; Wetzel, Bernd

2016-05-01

Self-assembling block-copolymers allow the easy manufacturing of nanocomposites due to the thermodynamically driven in situ formation of nanosized phases in thermosetting resins during the curing process. Complex mechanical dispersion processes can be avoided. The current study investigates the effect of a block-copolymer on the fatigue crack propagation resistance of a cycloaliphatic amine cured epoxy resin. It was found that a small amount of MAM triblock-copolymer significantly increases the resistance to fatigue crack propagation of epoxy. Crack growth rate and the Paris law exponent for fatigue-crack growth were considerably reduced from m=15.5 of the neat epoxy to m=8.1 of the nanocomposite. To identify the related reinforcing and fracture mechanisms structural analyses of the fractured surfaces were performed by scanning electron microscope. Characteristic features were identified to be deformation, debonding and fracture of the nano-phases as well as crack pinning. However, the highest resistance against fatigue crack propagation was achieved in a bi-continuous microstructure that consisted of an epoxy-rich phase with embedded submicron sized MAM inclusions, and which was surrounded by a block-copolymer-rich phase that showed rupture and plastic deformation.

Easy Debonding of Ceramic Brackets Bonded with a Light-Cured Orthodontic Adhesive Containing Microcapsules with a CO2 Laser.

PubMed

Arima, Shiori; Namura, Yasuhiro; Tamura, Takahiko; Shimizu, Noriyoshi

2018-03-01

An easy debonding method for ceramic brackets using a light-cured Bis-GMA resin containing heat-expandable microcapsules and CO 2 laser was investigated. Ceramic brackets are used frequently in orthodontic treatment because of their desirable esthetic properties. However, the application of heavy force to ceramic brackets in debonding can fracture the tooth enamel and ceramic brackets, causing tooth pain. In total, 60 freshly extracted bovine permanent mandibular incisors were divided randomly into 10 groups of 6 specimens each, corresponding to the number of variables tested. Ceramic brackets were bonded to bovine permanent mandibular incisors using an orthodontic bonding agent containing heat-expandable microcapsules at different levels (0-30 wt%) and resin composite paste, and cured by a curing device. The bond strengths were measured before and after CO 2 laser irradiation, and the temperature increase in the pulp chamber in fresh human first premolars was also evaluated. With CO 2 laser irradiation for 5 sec to the bracket, the bond strength in the 25% microcapsule group decreased significantly, to ∼0.17-fold, compared with that of the no-laser group (p < 0.05). The maximum temperature increase in the pulp chamber was 5.3°C with laser irradiation, which was less than the level that induces pulp damage. From these results, it seems likely that the combined use of a light-cured orthodontic bonding agent containing microcapsules and a CO 2 laser is a simple debonding system for ceramic brackets, with less debonding time and enamel damage.

Microtomography of elastomers for tire manufacture

NASA Astrophysics Data System (ADS)

Dunsmuir, John H.; Dias, A. J.; Peiffer, D. G.; Kolb, R.; Jones, G.

1999-09-01

X-ray microtomography is used to image the internal structure of carbon black filled isobutylene-p-methylstyrene-p- bromomethylstyrene (PIB-PMS/BrPMS or ExxProTM) curing bladders before and after use-to-failure in the manufacture of automobile tires. Curing bladders operate under extreme conditions with extended mechanical cycling at high temperatures. Manufacturers typically do not run the bladders until failure but rather a pull policy is established which emphasizes the distribution of cyclic lifetimes. We examine the bladder elastomer structure at a resolution of about 10 microns with the objective of reducing the variability in performance. Using both edge crossing and absorption contrast we identify several types of heterogeneity including voids, foreign inclusions, and the distribution of curative agent from which we infer the uniformity of the cure. The results indicate several potential failure mechanisms. The small number of voids and foreign inclusions are mechanical defects that can initiate cracking. More widespread through the polymer matrix are small regions of polymer devoid of curative agent as shown by absorption edge imaging. These regions may be uncured polymer with poor mechanical and thermal properties that may lead to early failure. After several cure cycles the uncured regions are no longer present in the bladder tread area but they remain near the bead. At high cycles an approximately 500 micrometer thick zinc rich cap develops where the bladder contacts the inner tread area of the tire. This zinc rich cap may cause over-curing of the polymer resulting in crack initiation at the surface of the bladder that contacts the tire.

Tensile strength of glass fiber posts submitted to different surface treatments.

PubMed

Faria, Maria Isabel A; Gomes, Érica Alves; Messias, Danielle Cristine; Silva Filho, João Manoel; Souza Filho, Celso Bernardo; Paulino, Silvana Maria

2013-01-01

The aim of this in vitro study was to evaluate the tensile strength of glass fiber posts submitted to different surface treatments. Forty-eight maxillary canines had their crowns sectioned and root canals endodontically treated. The roots were embedded in acrylic resin and distributed into 3 groups according to the surface treatment: Group I: the posts were treated with silane agent for 30 s and adhesive; Group II: the posts were cleaned with alcohol before treatment with silane agent and adhesive; Group III: the posts were submitted to conditioning with 37% phosphoric acid for 30 s before treatment with silane agent and adhesive. Each group was divided into 2 subgroups for adhesive polymerization or not before insertion into the canal: A - adhesive was not light cured and B - adhesive was light cured. All posts were cemented with Panavia F and the samples were subjected to tensile strength test in a universal testing machine at crosshead speed of 1 mm/min. Data were submitted to one-way ANOVA and Tukey's test at 5% significance level. There was statistically significant difference (p<0.01) only between group GIII-B and groups GI-A and GI-B. No significant difference was found among the other groups (p>0.05). It was concluded that the products used for cleaning the posts influenced the retention regardless of adhesive light curing.

Dynamics of polymerization induced phase separation in reactive polymer blends

NASA Astrophysics Data System (ADS)

Lee, Jaehyung

Mechanisms and dynamics of phase decomposition following polymerization induced phase separation (PIPS) of reactive polymer blends have been investigated experimentally and theoretically. The phenomenon of PIPS is a non-equilibrium and non-linear dynamic process. The mechanism of PIPS has been thought to be a nucleation and growth (NG) type originally, however, newer results indicate spinodal decomposition (SD). In PIPS, the coexistence curve generally passes through the reaction temperature at off-critical compositions, thus phase separation has to be initiated first in the metastable region where nucleation occurs. When the system farther drifts from the metastable to unstable region, the NG structure transforms to the SD bicontinuous morphology. The crossover behavior of PIPS may be called nucleation initiated spinodal decomposition (NISD). The formation of newer domains between the existing ones is responsible for the early stage of PIPS. Since PIPS is non- equilibrium kinetic process, it would not be surprising to discern either or both structures. The phase separation dynamics of DGEBA/CTBN mixtures having various kinds of curing agents from low reactivity to high reactivity and various amount of curing agents were examined at various reaction temperatures. The phase separation behavior was monitored by a quantity of scattered light intensity experimentally and by a quantity of collective structure factor numerically. Prior to the study of phase separation dynamics, a preliminary investigation on the isothermal cure behavior of the mixtures were executed in order to determine reaction kinetics parameters. The cure behavior followed the overall second order reaction kinetics. Next, based on the knowledge obtained from the phase separation dynamics study of DGEBA/CTBN mixtures, the phase separation dynamics of various composition of DGEBA/R45EPI mixtures having MDA as a curing agent were investigated. The phase separation behavior was quite dependent upon the composition variation. R45EPI itself can react with itself or with DGEBA without curing, therefore three-component system was considered in this mixture. For the numerical studies of this three- component mixture, a system that is composed of a reactive component-1 that is miscible with its growing molecules and another reactive component-2 that is not miscible with its growing molecules was considered with crosslinking reaction kinetics of the each component.

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

DTIC Science & Technology

2013-04-26

versions of the self-etch adhesives on the market are one-step systems where the acidified primer and adhesive monomer are mixed together and placed in a...Figure 3 - Adhesive Classification B. Effects of Simplification at the Microscopic level Using restorative systems with simplified...bonding failures when self-cured “build-up” composites were bonded with simplified adhesive systems (Swift, 1999). They were alerted to potential

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

DTIC Science & Technology

2001-11-01

National Laboratory has developed a lab- scale synthesis to convert TNT to higher value products such as TATB. 3.2 Firing Range Clean-Up Due to...1000 2000 3000 4000 5000 TCD1 , of Nitrogen Nitric Oxide Nitrous oxide ammonia Water Figure 1. Reactant Products for the Reaction of...SAND2001-3344 Unlimited Release Printed November 2001 Safe Deactivation of Energetic Materials and Use of By- products as Epoxy Curing

Thermal Expansion Measurements of Polymer Matrix Composites and Syntactics

DTIC Science & Technology

1992-04-01

828 (Shell Chemical) epoxy combined with 50.0 PBW EPON® V-40 polyamide curing agent (Shell Chemical) and Owens Corning (E-780) polyester combined 1...with 24 oz. woven roving with an Owens Corning 463 finish. " A 3 x 1, S-2 glass with 27 oz. woven roving with an Owens Corning 933 finish, nominally...wet polyester resin ( Owens Corning E-780) and subsequently processing the composites using the standard vacuum bag cure cycle for this polyester

A Durable Airfield Marking System.

DTIC Science & Technology

1985-06-01

Resin is Mixed with the Black Curing Agent to Form the Epoxy Adhesive ..... ........... 17 14 The Gray Adhesive (White Resin Mixed with Black Curing...rubber 100 0 Polyester (peroxide-catalyzed) 100 0 Urethane 100 0 Epoxy polyamide 100 0 Acrylic latex (TT-P-1952) 100 0 Thermoplastic Tapes Type 1 100 0...suzmarrizes cost data co1parisons for traffic marking tapes, CAS tiles, fluorocarbon composites (Teflon ),and acrylic latex paint TT-P-1952. 8 -p °’. TABLE 2

PCR Amplification and Cloning of Tyrosine Decarboxylase Involved in Synephrine Biosynthesis in Citrus

USDA-ARS?s Scientific Manuscript database

The phenolic amine synephrine is a vascoconstrictor and bronchiectatic agent and may have promise as an aid to weight management and obesity reduction. Synephrine is structurally similar to the active ingredients of several commercial cold remedies. Some Citrus have been shown to possess high conc...

Intrinsic Flame-Retardant and Thermally Stable Epoxy Endowed by a Highly Efficient, Multifunctional Curing Agent

PubMed Central

Dong, Chunlei; Wirasaputra, Alvianto; Luo, Qinqin; Liu, Shumei; Yuan, Yanchao; Zhao, Jianqing; Fu, Yi

2016-01-01

It is difficult to realize flame retardancy of epoxy without suffering much detriment in thermal stability. To solve the problem, a super-efficient phosphorus-nitrogen-containing reactive-type flame retardant, 10-(hydroxy(4-hydroxyphenyl)methyl)-5,10-dihydrophenophosphazinine-10-oxide (HB-DPPA) is synthesized and characterized. When it is used as a co-curing agent of 4,4′-methylenedianiline (DDM) for curing diglycidyl ether of bisphenol A (DGEBA), the cured epoxy achieves UL-94 V-0 rating with the limiting oxygen index of 29.3%. In this case, the phosphorus content in the system is exceptionally low (0.18 wt %). To the best of our knowledge, it currently has the highest efficiency among similar epoxy systems. Such excellent flame retardancy originates from the exclusive chemical structure of the phenophosphazine moiety, in which the phosphorus element is stabilized by the two adjacent aromatic rings. The action in the condensed phase is enhanced and followed by pressurization of the pyrolytic gases that induces the blowing-out effect during combustion. The cone calorimeter result reveals the formation of a unique intumescent char structure with five discernible layers. Owing to the super-efficient flame retardancy and the rigid molecular structure of HB-DPPA, the flame-retardant epoxy acquires high thermal stability and its initial decomposition temperature only decreases by 4.6 °C as compared with the unmodified one. PMID:28774127

Method for epoxy foam production using a liquid anhydride

DOEpatents

Celina, Mathias [Albuquerque, NM

2012-06-05

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

Tafenoquine: a promising new antimalarial agent.

PubMed

Crockett, Maryanne; Kain, Kevin C

2007-05-01

Malaria remains an important cause of global morbidity and mortality. As antimalarial drug resistance escalates, new safe and effective medications are necessary to prevent and treat malarial infection. Tafenoquine is an 8-aminoquinoline antimalarial that is presently under development. It has a long half-life of approximately 14 days and is generally safe and well tolerated, although it cannot be used in pregnant women and individuals who are deficient in the enzyme glucose-6-phosphate dehydrogenase. In well-designed studies, tafenoquine was highly effective in both the radical cure of relapsing malaria and causal prophylaxis of Plasmodium vivax and P. falciparum infections with protective efficacies of > or = 90%. Given its causal activity and safety profile, tafenoquine represents a potentially exciting alternative to standard agents for the prevention and radical cure of malaria.

Flame Retardant Epoxy Resins

NASA Technical Reports Server (NTRS)

Thompson, C. M.; Smith, J. G., Jr.; Connell, J. W.; Hergenrother, P. M.; Lyon, R. E.

2004-01-01

As part of a program to develop fire resistant exterior composite structures for future subsonic commercial aircraft, flame retardant epoxy resins are under investigation. Epoxies and their curing agents (aromatic diamines) containing phosphorus were synthesized and used to prepare epoxy formulations. Phosphorus was incorporated within the backbone of the epoxy resin and not used as an additive. The resulting cured epoxies were characterized by thermogravimetric analysis, propane torch test, elemental analysis and microscale combustion calorimetry. Several formulations showed excellent flame retardation with phosphorous contents as low as 1.5% by weight. The fracture toughness of plaques of several cured formulations was determined on single-edge notched bend specimens. The chemistry and properties of these new epoxy formulations are discussed.

Low Melt Viscosity Resins for Resin Transfer Molding

NASA Technical Reports Server (NTRS)

Harris, Frank W.

2002-01-01

In recent years, resin transfer molding (RTM) has become one of the methods of choice for high performance composites. Its cost effectiveness and ease of fabrication are major advantages of RTM. RTM process usually requires resins with very low melt viscosity (less than 10 Poise). The optimum RTM resins also need to display high thennal-oxidative stability, high glass transition temperature (T(sub g)), and good toughness. The traditional PMR-type polyimides (e.g. PMR-15) do not fit this requirement, because the viscosities are too high and the nadic endcap cures too fast. High T(sub g), low-melt viscosity resins are highly desirable for aerospace applications and NASA s Reusable Launch Vehicle (RLV) program. The objective of this work is to prepare low-melt viscosity polyimide resins for RTM or resin film infusion (RFI) processes. The approach involves the synthesis of phenylethynyl-terminated imide oligomers. These materials have been designed to minimize their melt viscosity so that they can be readily processed. During the cure, the oligomers undergo both chain extension and crosslinking via the thermal polymerization of the phenylethynyl groups. The Phenylethynyl endcap is preferred over the nadic group due to its high curing temperature, which provides broader processing windows. This work involved the synthesis and polymerization of oligomers containing zig-zag backbones and twisted biphenyl structures. Some A-B type precursors which possessed both nitro and anhydride functionality, or both nitro and amine functionality, were also synthesized in order to obtain the well defined oligomers. The resulting zig-zag structured oligomers were then end-capped with 4-phenylethynylphthalic anhydride (PEPA) for further cure. The properties of these novel imide oligomers are evaluated.

Extraction-spectrophotometric determination of tris(2-chloroethyl)amine using phthaleins.

PubMed

Rozsypal, Tomas; Halamek, Emil

2017-06-01

Procedures for the extraction-spectrophotometric determination of tris(2-chloroethyl)amine, an alkylating agent known as a drug as well as a chemical warfare agent (nitrogen mustard HN-3), with 7 acid-base indicators of a triphenylmethane lactone type, phthaleins, were developed. Representatives of phthaleins without an oxygen bridge (thymolphthalein, o-cresolphthalein, naphtholphthalein) and with an oxygen bridge (fluorescein, 2',7'-dichlorofluorescein, eosin B and eosin Y) were used. The methods were based on the formation of ion pair complexes. Chloroform was used as a non-polar solvent for an extraction. The conditions to determine were optimized for the optimal pH of the buffer and the concentration of a phthalein as a reagent. The dependence on the reaction time in a water phase and the stoichiometry of extraction products were studied. The detection limits and the limits of the determination of separate procedures and conditional extraction constants were determined. Comparison with the spectrophotometric method of the group determination of alkyl halides and acyl halides using alkaline ethanol-water solution of thymolphthalein, the so-called T-135 agent, was conducted. While studying the selectivity, the possible interference of bis(2-chloroethyl)sulphide and 3 nitrogen mustards in the proposed procedures were verified. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Alternative Causes of Wide-Spread, Low Concentration Perchlorate Impacts to Groundwater

DTIC Science & Technology

2005-05-05

to as water gels, contain AN in aqueous solution. To aid water resistance and handling, they are thickened and gelled with a gum , such as guar gum ...enamels Curing/Drying Agent Photography Flash powder / oxidizing agent Oxygen generators Burn Rate Modifier Road flares Oxidizing agent...fuse, stars, black powder , a launch tube, main fuse and a lift charge, as shown in Figure 3-1. The break or breaks house the stars in cardboard

Carbonic anhydrase activators: Activation of the β-carbonic anhydrase from Malassezia globosa with amines and amino acids.

PubMed

Vullo, Daniela; Del Prete, Sonia; Capasso, Clemente; Supuran, Claudiu T

2016-03-01

The β-carbonic anhydrase (CA, EC 4.2.1.1) from the dandruff producing fungus Malassezia globosa, MgCA, was investigated for its activation with amines and amino acids. MgCA was weakly activated by amino acids such as L-/D-His, L-Phe, D-DOPA, D-Trp, L-/D-Tyr and by the amine serotonin (KAs of 12.5-29.3μM) but more effectively activated by d-Phe, l-DOPA, l-Trp, histamine, dopamine, pyridyl-alkylamines, and 4-(2-aminoethyl)-morpholine, with KAs of 5.82-10.9μM. The best activators were l-adrenaline and 1-(2-aminoethyl)piperazine, with activation constants of 0.72-0.81μM. This study may help a better understanding of the activation mechanisms of β-CAs from pathogenic fungi as well as the design of tighter binding ligands for this enzyme which is a drug target for novel types of anti-dandruff agents. Copyright © 2016 Elsevier Ltd. All rights reserved.

N-isopropyl-(/sup 123/I)p-iodoamphetamine: single-pass brain uptake and washout; binding to brain synaptosomes; and localization in dog and monkey brain

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

Winchell, H.S.; Horst, W.D.; Braun, L.

1980-10-01

The kinetics of N-isopropyl-p-(/sup 123/I)iodoamphetamine in rat brains were determined by serial measurements of brain uptake index (BUI) after intracarotid injection; also studied were its effects on amine uptake and release in rat's brain cortical synaptosomes; and its in vivo distribution in the dog and monkey. No specific localization in brain nuclei of the dog was seen, but there was progressive accumulation in the eyes. Rapid initial brain uptake in the ketamine-sedated monkey was noted, and further slow brain uptake occurred during the next 20 min but without retinal localization. High levels of brain activity were maintained for several hours.more » The quantitative initial single-pass clearance of the agent in the brain suggests its use in evaluation of regional brain perfusion. Its interaction with brain amine-binding sites suggests its possible application in studies of cerebral amine metabolism.« less

Development of self-healing polymers via amine-epoxy chemistry: II. Systematic evaluation of self-healing performance

NASA Astrophysics Data System (ADS)

Zhang, He; Yang, Jinglei

2014-06-01

Part I of this study (H Zhang and J Yang 2014 Smart Mater. Struct. 23 065003) reported the preparation and characterization of epoxy microcapsules (EP-capsules) and amine loaded hollow glass bubbles (AM-HGBs), and the modeling of a two-part self-healing system. In part II, the self-healing performance of this material system is systematically investigated. Various factors including the ratio, the total concentration and the size of the two carriers are studied as well as the healing temperature and the post heat treatment process. The best healing performance is obtained at a ratio of 1:3 of EP-capsules to AM-HGBs. It is observed that a higher concentration of larger carriers, together with a higher healing temperature, enables better healing behavior. Healing efficiency of up to 93% is obtained in these systems. In addition, post heat treatment decreases the healing efficiency due to stoichiometric mismatch of healing agents caused by leakage of amine in the HGBs at elevated temperature.

Comparison of Zirconium Phosphonate-Modified Surfaces for Immobilizing Phosphopeptides and Phosphate-Tagged Proteins.

PubMed

Forato, Florian; Liu, Hao; Benoit, Roland; Fayon, Franck; Charlier, Cathy; Fateh, Amina; Defontaine, Alain; Tellier, Charles; Talham, Daniel R; Queffélec, Clémence; Bujoli, Bruno

2016-06-07

Different routes for preparing zirconium phosphonate-modified surfaces for immobilizing biomolecular probes are compared. Two chemical-modification approaches were explored to form self-assembled monolayers on commercially available primary amine-functionalized slides, and the resulting surfaces were compared to well-characterized zirconium phosphonate monolayer-modified supports prepared using Langmuir-Blodgett methods. When using POCl3 as the amine phosphorylating agent followed by treatment with zirconyl chloride, the result was not a zirconium-phosphonate monolayer, as commonly assumed in the literature, but rather the process gives adsorbed zirconium oxide/hydroxide species and to a lower extent adsorbed zirconium phosphate and/or phosphonate. Reactions giving rise to these products were modeled in homogeneous-phase studies. Nevertheless, each of the three modified surfaces effectively immobilized phosphopeptides and phosphopeptide tags fused to an affinity protein. Unexpectedly, the zirconium oxide/hydroxide modified surface, formed by treating the amine-coated slides with POCl3/Zr(4+), afforded better immobilization of the peptides and proteins and efficient capture of their targets.

Simple diazonium chemistry to develop specific gene sensing platforms.

PubMed

Revenga-Parra, M; García-Mendiola, T; González-Costas, J; González-Romero, E; Marín, A García; Pau, J L; Pariente, F; Lorenzo, E

2014-02-27

A simple strategy for covalent immobilizing DNA sequences, based on the formation of stable diazonized conducting platforms, is described. The electrochemical reduction of 4-nitrobenzenediazonium salt onto screen-printed carbon electrodes (SPCE) in aqueous media gives rise to terminal grafted amino groups. The presence of primary aromatic amines allows the formation of diazonium cations capable to react with the amines present at the DNA capture probe. As a comparison a second strategy based on the binding of aminated DNA capture probes to the developed diazonized conducting platforms through a crosslinking agent was also employed. The resulting DNA sensing platforms were characterized by cyclic voltammetry, electrochemical impedance spectroscopy and spectroscopic ellipsometry. The hybridization event with the complementary sequence was detected using hexaamineruthenium (III) chloride as electrochemical indicator. Finally, they were applied to the analysis of a 145-bp sequence from the human gene MRP3, reaching a detection limit of 210 pg μL(-1). Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis and preliminary biological evaluations of (+)-isocampholenic acid-derived amides.

PubMed

Grošelj, Uroš; Golobič, Amalija; Knez, Damijan; Hrast, Martina; Gobec, Stanislav; Ričko, Sebastijan; Svete, Jurij

2016-08-01

The synthesis of two novel (+)-isocampholenic acid-derived amines has been realized starting from commercially available (1S)-(+)-10-camphorsulfonic acid. The novel amines as well as (+)-isocampholenic acid have been used as building blocks in the construction of a library of amides using various aliphatic, aromatic, and amino acid-derived coupling partners using BPC and CDI as activating agents. Amide derivatives have been assayed against several enzymes that hold potential for the development of new drugs to battle bacterial infections and Alzheimer's disease. Compounds 20c and 20e showed promising selective sub-micromolar inhibition of human butyrylcholinesterase [Formula: see text] ([Formula: see text] values [Formula: see text] and [Formula: see text], respectively).

Using AFM Force Curves to Explore Properties of Elastomers

ERIC Educational Resources Information Center

Ferguson, Megan A.; Kozlowski, Joseph J.

2013-01-01

polydimethylsiloxane (PDMS) elastomers. Force curves are used to quantify the stiffness of elastomers prepared with different base-to-curing agent ratios. Trends in observed spring constants of the…

A New Epoxy-Based Layered Silicate Nanocomposite Using a Hyperbranched Polymer: Study of the Curing Reaction and Nanostructure Development

PubMed Central

Cortés, Pilar; Fraga, Iria; Calventus, Yolanda; Román, Frida; Hutchinson, John M.; Ferrando, Francesc

2014-01-01

Polymer layered silicate (PLS) nanocomposites have been prepared with diglycidyl ether of bisphenol-A (DGEBA) epoxy resin as the matrix and organically modified montmorillonite (MMT) as the clay nanofiller. Resin-clay mixtures with different clay contents (zero, two, five and 10 wt%) were cured, both isothermally andnon-isothermally, using a poly(ethyleneimine) hyperbranched polymer (HBP), the cure kinetics being monitored by differential scanning calorimetry (DSC). The nanostructure of the cured nanocomposites was characterized by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM), and their mechanical properties were determined by dynamic mechanical analysis (DMA) and impact testing. The results are compared with an earlier study of the structure and properties of the same DGEBA-MMT system cured with a polyoxypropylene diamine, Jeffamine. There are very few examples of the use of HBP as a curing agent in epoxy PLS nanocomposites; here, it is found to enhance significantly the degree of exfoliation of these nanocomposites compared with those cured with Jeffamine, with a corresponding enhancement in the impact energy for nanocomposites with the low clay content of 2 wt%. These changes are attributed to the different cure kinetics with the HBP, in which the intra-gallery homopolymerization reaction is accelerated, such that it occurs before the bulk cross-linking reaction. PMID:28788542

Dispersion stability in carbon nanotube modified polymers and its effect on the fracture toughness

NASA Astrophysics Data System (ADS)

Mirjalili, Vahid; Yourdkhani, Mostafa; Hubert, Pascal

2012-08-01

In this paper, the dispersion stability of multiwall carbon nanotubes (MWNTs) mixed with an epoxy resin is studied. An instrumented optical microscope with a hot stage was used to study the evolution of the carbon nanotubes (CNTs) dispersion during the cure of the resin. A new image processing approach is then introduced to quantify dispersion and identify the source of dispersion degradation during the cure. The results showed that the reduction of the resin viscosity at temperatures greater than 100 °C caused an irreversible re-agglomeration of the CNTs in the matrix. It was shown that the fine-tuning of the ratio and type of curing agent as well as the curing temperature directly affect the dispersion stability of MWNTs in the epoxy polymer. The dispersion quality was then directly correlated to the fracture toughness of the modified resin and a maximum of 20% improvement was achieved.

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

Young, D.A.; Smith, C.H.

A carboxyl-terminated butadiene/acrylonitrile (CTBN)/epoxy resin adduct, used to encapsulate electronic devices, was studied to improve its quality and reliability. The average physical and mechanical properties of the amine-cured product were obtained by testing 16 batches of adduct prepared from 13 separate lots of CTBN. It was found that by using a CTBN with a higher acrylonitrile content (or one in which the chemical structure includes carboxyl groups in the chain backbone, in addition to end termination), a clear, soluble liquid adduct that does not separate in storage or transit could be prepared. These materials also produced clear epoxy castings andmore » filled potting compounds with improved impact, flexural, compressive, and tensile strengths.« less

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

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

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

2009-03-24

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

Syringaresinol: A Renewable and Safer Alternative to Bisphenol A for Epoxy-Amine Resins.

PubMed

Janvier, Marine; Hollande, Louis; Jaufurally, Abdus Samad; Pernes, Miguel; Ménard, Raphaël; Grimaldi, Marina; Beaugrand, Johnny; Balaguer, Patrick; Ducrot, Paul-Henri; Allais, Florent

2017-02-22

A renewable bisepoxide, SYR-EPO, was prepared from syringaresinol, a naturally occurring bisphenol deriving from sinapic acid, by using a chemo-enzymatic synthetic pathway. Estrogenic activity tests revealed no endocrine disruption for syringaresinol. Its glycidylation afforded SYR-EPO with excellent yield and purity. This biobased, safe epoxy precursor was then cured with conventional and renewable diamines for the preparation of epoxy-amine resins. The resulting thermosets were thermally and mechanically characterized. Thermal analyses of these new resins showed excellent thermal stabilities (T d5 % =279-309 °C) and T g ranging from 73 to 126 °C, almost reaching the properties of those obtained with the diglycidylether of bisphenol A (DGEBA), extensively used in the polymer industry (T d5 % =319 °C and T g =150 °C for DGEBA/isophorone diamine resins). Degradation studies in NaOH and HCl aqueous solutions also highlighted the robustness of the syringaresinol-based resins, similar to bisphenol A (BPA). All these results undoubtedly confirmed the potential of syringaresinol as a greener and safer substitute for BPA. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

21 CFR 133.102 - Asiago fresh and asiago soft cheese.

Code of Federal Regulations, 2014 CFR

2014-04-01

... § 133.5 (a), (b), and (d). It is cured for not less than 60 days. (b) Milk which may be pasteurized or clarified or both, and which may be warmed, is subjected to the action of harmless lactic-acid producing... artificial coloring is not used. (d) Safe and suitable antimycotic agent(s), the cumulative levels of which...

21 CFR 133.102 - Asiago fresh and asiago soft cheese.

Code of Federal Regulations, 2012 CFR

2012-04-01

... § 133.5 (a), (b), and (d). It is cured for not less than 60 days. (b) Milk which may be pasteurized or clarified or both, and which may be warmed, is subjected to the action of harmless lactic-acid producing... artificial coloring is not used. (d) Safe and suitable antimycotic agent(s), the cumulative levels of which...

21 CFR 133.102 - Asiago fresh and asiago soft cheese.

Code of Federal Regulations, 2013 CFR

2013-04-01

... § 133.5 (a), (b), and (d). It is cured for not less than 60 days. (b) Milk which may be pasteurized or clarified or both, and which may be warmed, is subjected to the action of harmless lactic-acid producing... artificial coloring is not used. (d) Safe and suitable antimycotic agent(s), the cumulative levels of which...

The Function of Emulsions on the Biogenic Amine Formation and their Indices of Sea Bass Fillets (Dicentrarchus Labrax) Stored in Vacuum Packaging.

PubMed

Ozogul, Yesim; Durmus, Mustafa; Kuley Boga, Esmeray; Uçar, Yılmaz; Ozogul, Fatih

2018-02-01

The impacts of emulsions based on commercial oils on the biogenic amine formation and their indices of vacuumed packed sea bass fillets were investigated. The results showed that among biogenic amines, cadaverine, putrescine, spermidine, spermine, serotonin, dopamine, and agmatine were predominant amines in sea bass fillets stored under vacuum packaging. Significant differences (P < 0.05) in biogenic amines concentrations of vacuumed packed sea bass treated with emulsions were observed. All groups contained histamine lower than 5.0 mg/100 g, regarded as the allowable limit by the U.S. Food and Drug Administration. Polyamine levels were not affected by application of emulsion. Quality index (QI) showed an increase and after 14 d of storage it decreased in all groups. The control generally seemed to higher QI value than those of treatment groups except at 14 and 18 days while soybean and corn gave lower QI among treatment groups. Only biogenic amine index correlated with sensory acceptability of vacuumed packed sea bass, indicating that this index can be used for determination of the degree of spoilage of vacuumed packed sea bass. Emulsions extended the shelf-life (approximately 2 to 4 d) of vacuumed packed sea bass fillets by inhibiting microbial growth compared to the control. Emulsions have become popular since they are regarded as ideal carrier for the delivery of lipophilic substances due to the ease of preparation, small particle size, their enhanced bioavailability, and long term kinetic stability. They have been proven to be self-preserving antimicrobials due to bound water in their structure and thus no available water to microorganisms. Antimicrobial emulsions have potential applications in many fields because they are inexpensive, stable, and nontoxic agents. © 2018 Institute of Food Technologists®.

Absorption spectroscopic and FTIR studies on EDA complexes between TNT (2,4,6-trinitrotoluene) with amines in DMSO and determination of the vertical electron affinity of TNT.

PubMed

Sharma, S P; Lahiri, S C

2008-06-01

TNT (2,4,6-trinitrotoluene) formed deep red 1:1 CT complexes with chromogenic agents like isopropylamine, ethylenediamine, bis(3-aminopropyl)amine and tetraethylenepentamine in DMSO. The complexes were also observed in solvents like methanol, acetone, etc. when the amines were present in large excess. The isopropylamine, complex showed three absorption peaks (at 378, 532 and 629 nm) whereas higher amines showed four peaks (at 370, 463, 532 and 629 nm). The peak at 463 nm vanished rapidly. The peak of the complexes near 530 nm required about 8-10 min to develop and the complexes were stable for about an hour but the peak slowly shifted towards 500 nm and the complexes were found to be stable for more than 24 h. The evidence of complex formation was obtained from distinct spots in HPTLC plates and from the shifts in frequencies and formation of new peaks in FTIR spectra. The peaks near 460 nm (transient) and 530 nm may be due to Janovsky reaction but could not be established. The extinction coefficients of the complexes were determined directly which enabled the accurate determination of the association constants KDA with TNT and amines in stoichiometric ratios. The results were verified using iterative method. The quantification of TNT was made using epsilon value of the complex with ethylenediamine. The vertical electron affinity (EA) of TNT was calculated using the method suggested by Mulliken.

Process for impregnating a concrete or cement body with a polymeric material

DOEpatents

Mattus, A.J.; Spence, R.D.

1988-05-04

A process for impregnating cementitious solids with polymeric materials by blending polymeric materials in a grout, allowing the grout to cure, and contacting the resulting solidified grout containing the polymeric materials with an organic mixture containing a monomer, a cross-linking agent and a catalyst. The mixture dissolves the polymerized particles and forms a channel for distributing the monomer throughout the network formed by the polymeric particles. The organic components are then cured to form a substantially water-impermeable mass.

Process for impregnating a concrete or cement body with a polymeric material

DOEpatents

Mattus, Alfred J.; Spence, Roger D.

1989-01-01

A process for impregnating cementitious solids with polymeric materials by blending polymeric materials in a grout, allowing the grout to cure, and contacting the resulting solidified grout containing the polymeric materials with an organic mixture containing a monomer, a cross-linking agent and a catalyst. The mixture dissolves the polymerized particles and forms a channel for distributing the monomer throughout the network formed by the polymeric particles. The organic components are then cured to form a substantially water-impermeable mass.

Epoxy Nanocomposites Containing Zeolitic Imidazolate Framework-8.

PubMed

Liu, Cong; Mullins, Michael; Hawkins, Spencer; Kotaki, Masaya; Sue, Hung-Jue

2018-01-10

Zeolitic imidazole framework-8 (ZIF-8) is utilized as a functional filler and a curing agent in the preparation of epoxy nanocomposites. The imidazole group on the surface of the ZIF-8 initiates epoxy curing, resulting in covalent bonding between the ZIF-8 crystals and epoxy matrix. A substantial reduction in dielectric constant and increase in tensile modulus were observed. The implication of the present study for utilization of metal-organic framework to improve physical and mechanical properties of polymeric matrixes is discussed.

[Results of a regional survey on the treatment of rhizomelic pseudopolyarthritis and temporal arteritis. Apropos of 242 cases treated by various modalities with synthetic antimalarials, corticoids and non-steroidal anti-inflammatory agents].

PubMed

David-Chaussé, J; Dehais, J; Leman, A

1983-01-01

The authors report the results of a retrospective therapeutic survey concerning 176 cases of rhizomelic pseudopolyarthritis (RPP) and 66 cases of temporal arteritis (TA). Of 128 cases of RPP treated initially by synthetic anti-malarials (SAM) and non-steroidal anti-inflammatory agents (NSAI), 66 were followed up until cure which was obtained after a mean of 23 months and 3 subsequently received brief steroid therapy. 45 cases of RPP were treated initially with corticosteroids. They were generally associated with SAM which enabled early weaning of the steroids, towards the 8 th month, or at least reducing the dose. Cure was obtained within 24 months. Three patients were treated by NSAI and gold therapy. After cure, 5 cases of recurrence and 1 case of TA were observed. 40 cases of TA were initially treated with SAM and NSAI. Twenty cures were obtained within a mean of 28 months. 4 patients later received brief corticosteroid therapy because of an extension of the signs, including two cases of ocular manifestations with a resolving course. Of 25 cases of TA initially treated with steroids, 20 received SAM in combination, or in relay which enabled either steroids, weaning towards the 14th month or a reduction in the dose of steroids. Cure was obtained in an average of 35 months. One case of impaired visual acuity occurred during corticosteroid treatment. Immunosuppressants were used in one patient. No cases of recurrence were observed. Iatrogenic complications with SAM were rare, generally benign and reversible, in contrast to those associated with corticosteroid therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

A multi-purpose tool for food inspection: Simultaneous determination of various classes of preservatives and biogenic amines in meat and fish products by LC-MS.

PubMed

Molognoni, Luciano; Daguer, Heitor; de Sá Ploêncio, Leandro Antunes; De Dea Lindner, Juliano

2018-02-01

This paper describes an innovative fast and multipurpose method for the chemical inspection of meat and fish products by liquid chromatography-tandem mass spectrometry. Solid-liquid extraction and low temperature partitioning were applied to 17 analytes, which included large bacteriocins (3.5kDa) and small molecules (organic acids, heterocyclic compounds, polyene macrolides, alkyl esters of the p-hydroxybenzoic acid, aromatic, and aliphatic biogenic amines and polyamines). Chromatographic separation was achieved in 10min, using stationary phase of di-isopropyl-3-aminopropyl silane bound to hydroxylated silica. Method validation was in accordance to Commission Decision 657/2002/CE. Linear ranges were among 1.25-10.0mgkg -1 (natamycin and parabens), 2.50-10.0mgkg -1 (sorbate and nisin), 25.0-200mgkg -1 (biogenic amines, hexamethylenetetramine, benzoic and lactic acids), and 50.0-400mgkg -1 (citric acid). Expanded measurement uncertainty (U) was estimated by single laboratory validation combined to modeling in two calculation approaches: internal (U = 5%) and external standardization (U = 24%). Method applicability was checked on 89 real samples among raw, cooked, dry fermented and cured products, yielding acceptable recoveries. Many regulatory issues were revealed, corroborating the need for enhancement of the current analytical methods. This simple execution method dispenses the use of additional procedures of extraction and, therefore, reduces costs over time. It is suitable for routine analysis as a screening or confirmatory tool for both qualitative and quantitative results, replacing many time consuming analytical procedures. Copyright © 2017 Elsevier B.V. All rights reserved.

Manipulating the self-assembling process to obtain control over the morphologies of copper oxide in hydrothermal synthesis and creating pores in the oxide architecture.

PubMed

Zhong, Ziyi; Ng, Vivien; Luo, Jizhong; Teh, Siew-Pheng; Teo, Jaclyn; Gedanken, Aharon

2007-05-22

Copper oxide with various morphologies was synthesized by the hydrolysis of Cu(ac)2 with urea under mild hydrothermal conditions. In the synthesis, a series of organic amines with one or two amine groups (monoamine and diamine), including isobutylamine, octylamine (OLA), dodecylamine, octadecylamine (monoamines), ethylenediamine dihydrochloride, and hexamethylenediamine (diamines), was used as the "structure-directing agent". The monoamines led to the formation of one-dimensional (1D) aggregates of the copper oxide precursor particles (Pre-CuO), while the diamines led to the formation of two-dimensional (2D) aggregates. In both cases, the shorter carbon-chain amine molecules showed a stronger structure-directing function than that of the longer carbon-chain amine molecules. Next, in a series of syntheses, OLA was selected for further study, and the experimental parameters were systematically manipulated. When the hydrolysis was adjusted to a very slow rate by coupling the hydrolysis reaction with an esterification reaction, 1D aggregates of Pre-CuO were formed; when the hydrolysis rate was in the middle range, spherical Pre-CuO architectures composed of smaller linear aggregates were formed. However, under the high hydrolysis rates achieved by increasing the precipitation agent (urea) or by conducting the reaction at high temperatures (>/=120 degrees C), only Pre-CuO nanoparticles with a featureless morphology were formed. The formed spherical Pre-CuO architectures can be converted to a porous structure (CuOx) after removing the OLA molecules via calcination. Compared to the 1D and 2D aggregates, this porous architecture is highly thermally stable and did not collapse even after calcination at 500 degrees C. Preliminary results showed that the porous structure can be used both as a catalyst support and as a catalyst for the oxidation of CO at low temperatures.

Intumescent coatings containing 4,4'-dinitrosulfanilide

NASA Technical Reports Server (NTRS)

Sawko, P. M.; Riccitiello, S. R. (Inventor)

1977-01-01

A coating which is stable to the environment and to exposure to water, and which intumesces at a favorable temperature was developed. The composition comprises a mixture of 4, 4 prime dinitrousulfanilide as the intumescent agent in a polymer binder mixture of a chlorinated polyolefin, a bisphenol A epoxy resin, and a rubber-like amine hardener.

Silane surface modification for improved bioadhesion of esophageal stents

PubMed Central

Karakoy, Mert; Gultepe, Evin; Pandey, Shivendra; Khashab, Mouen A.; Gracias, David H.

2014-01-01

Stent migration occurs in 10-40% of patients who undergo placement of esophageal stents, with higher migration rates seen in those treated for benign esophageal disorders. This remains a major drawback of esophageal stent therapy. In this paper, we propose a new surface modification method to increase the adhesion between self-expandable metallic stents (SEMS) and tissue while preserving their removability. Taking advantage of the well-known affinity between epoxide and amine terminated silane coupling agents with amine and carboxyl groups that are abundant in proteins and related molecules in the human body; we modified the surfaces of silicone coated esophageal SEMS with these adhesive self-assembled monolayers (SAMs). We utilized vapor phase silanization to modify the surfaces of different substrates including PDMS strips and SEMS, and measured the force required to slide these substrates on a tissue piece. Our results suggest that surface modification of esophageal SEMS via covalent attachment of protein-binding coupling agents improves adhesion to tissue and could offer a solution to reduce SEMS migration while preserving their removability. PMID:25663731

Isospecific propylene polymerization with in situ generated bis(phenoxy-amine)zirconium and hafnium single site catalysts.

PubMed

Makio, Haruyuki; Prasad, Aitha Vishwa; Terao, Hiroshi; Saito, Junji; Fujita, Terunori

2013-07-07

Bis(phenoxy-imine) Zr and Hf complexes were activated with (i)Bu3Al or (i)Bu2AlH in conjunction with Ph3CB(C6F5)4 and tested as catalysts for propylene polymerization with emphasis on the enantioselectivity of the isospecific species and the single site polymerization characteristics. The isoselective species was identified as the in situ generated bis(phenoxy-amine) complex whose isoselectivity was sensitive to subtle changes in ligand structure. By employing specific substituents at certain key positions the isotacticity reached an extremely high level comparable to high-end commercial isotactic polypropylenes (Tm > 160 °C). Single site polymerization characteristics depended upon the efficiency and selectivity of the in situ imine reduction which is sensitive to the substituent on the imine nitrogen and the reaction conditions. By using (i)Bu2AlH as a reducing agent, quantitative imine reduction can be achieved with a stoichiometric amount of the reducing agent. This lower alkylaluminum loading is beneficial for the catalyst and significantly enhances the polymerization activity and the molecular weight of the resultant polymer.

Nitric Oxide-Releasing Chitosan Oligosaccharides as Antibacterial Agents

PubMed Central

Lu, Yuan; Slomberg, Danielle L.; Schoenfisch, Mark H.

2014-01-01

Secondary amine-functionalized chitosan oligosaccharides of different molecular weights (i.e., ~2500, 5000, 10000) were synthesized by grafting 2-methyl aziridine from the primary amines on chitosan oligosaccharides, followed by reaction with nitric oxide (NO) gas under basic conditions to yield N-diazeniumdiolate NO donors. The total NO storage, maximum NO flux, and half-life of the resulting NO-releasing chitosan oligosaccharides were controlled by the molar ratio of 2-methyl aziridine to primary amines (e.g., 1:1, 2:1) and the functional group surrounding the N-diazeniumdiolates (e.g., polyethylene glycol (PEG) chains), respectively. The secondary amine-modified chitosan oligosaccharides greatly increased the NO payload over existing biodegradable macromolecular NO donors. In addition, the water-solubility of the chitosan oligosaccharides enabled their penetration across the extracellular polysaccharides matrix of Pseudomonas aeruginosa biofilms and association with embedded bacteria. The effectiveness of these chitosan oligosaccharides at biofilm eradication was shown to depend on both the molecular weight and ionic characteristics. Low molecular weight and cationic chitosan oligosaccharides exhibited rapid association with bacteria throughout the entire biofilm, leading to enhanced biofilm killing. At concentrations resulting in 5-log killing of bacteria in Pseudomonas aeruginosa biofilms, the NO-releasing and control chitosan oligosaccharides elicited no significant cytotoxicity to mouse fibroblast L929 cells in vitro. PMID:24268196

Insights into the O-Acetylation Reaction of Hydroxylated Heterocyclic Amines by Human Arylamine N-Acetyltransferases: A Computational Study

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

Lau, E Y; Felton, J S; Lightstone, F C

2006-06-06

A computational study was performed to better understand the differences between human arylamine N-acetyltransferase (NAT) 1 and 2. Homology models were constructed from available crystal structures and comparisons of the active site residues 125, 127, and 129 for these two enzymes provide insight into observed substrate differences. The NAT2 model provided a basis for understanding how some of the common mutations may affect the structure of the protein. Molecular dynamics simulations of the human NAT models and the template structure (NAT from Mycobacterium smegmatis) were performed and showed the models to be stable and reasonable. Docking studies of hydroxylated heterocyclicmore » amines in the models of NAT1 and NAT2 probed the differences exhibited by these two proteins with mutagenic agents. The hydroxylated heterocyclic amines were only able to fit into the NAT2 active site, and an alternative binding site by the P-loop was found using our models and will be discussed. Additionally, quantum mechanical calculations were performed to study the O-acetylation reaction of the hydroxylated heterocyclic amines N-OH MeIQx and N-OH PhIP. This study has given us insight into why there are substrate differences among isoenzymes and explains some of the polymorphic activity differences.« less

Nitrogen-based drugs are not essential for blockade of monoamine transporters.

PubMed

Madras, B K; Pristupa, Z B; Niznik, H B; Liang, A Y; Blundell, P; Gonzalez, M D; Meltzer, P C

1996-12-01

In brain, monoamine transporters are principal targets of widely used therapeutic drugs including antidepressants, methylphenidate (Ritalin), and the addictive drug cocaine. Without exception, these transport blocking agents contain an amine nitrogen. A prevalent view and untested premise is that an amine nitrogen is needed to bind to the same counterion on the transporter as does the amine nitrogen of the monoamine neurotransmitter. We report that several compounds without nitrogen (8-oxa-bicyclo-3-aryl-[3.2.1] octanes, or aryloxatropanes) are active at monoamine transporters. One of these, tropoxane (0-914), bound with high affinity to the dopamine (IC50: 3.35 +/- 0.39 nM), serotonin (IC50: 6.52 +/- 2.05 nM), and norepinephrine (IC50: 20.0 +/- 0.3 nM) transporters in monkey brain, the human striatal dopamine transporter (IC50: 5.01 +/- 1.74 nM), and blocked dopamine transport (IC50: 7.2 +/- 3.0 nM) in COS-7 cells transfected with the human dopamine transporter. These unique compounds require a revision of current concepts of the drug binding domains on monoamine transporters, open avenues for discovery of a new generation of drugs and raise the issue of whether mammalian transporters and receptors may respond to, as yet, undiscovered non-amine bearing neurotransmitters or drugs.

Transparent ceramics and methods of preparation thereof

DOEpatents

Hollingsworth, Joel P [Oakland, CA; Kuntz, Joshua D [Livermore, CA; Seeley, Zachary M [Pullman, WA; Soules, Thomas F [Livermore, CA

2011-10-18

According to one embodiment, a method for forming a transparent ceramic preform includes forming a suspension of oxide particles in a solvent, adding the suspension to a mold of a desired shape, and uniformly curing the suspension in the mold for forming a preform. The suspension includes a dispersant but does not include a gelling agent. In another embodiment, a method includes creating a mixture without a gelling agent, the mixture including: inorganic particles, a solvent, and a dispersant. The inorganic particles have a mean diameter of less than about 2000 nm. The method also includes agitating the mixture, adding the mixture to a mold, and curing the mixture in the mold at a temperature of less than about 80.degree. C. for forming a preform. Other methods for forming a transparent ceramic preform are also described according to several embodiments.

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. Copyright © 2015 Elsevier Inc. All rights reserved.

The evaluation of dentinal tubule occlusion by desensitizing agents: a real-time measurement of dentinal fluid flow rate and scanning electron microscopy.

PubMed

Kim, S Y; Kim, E J; Kim, D S; Lee, I B

2013-01-01

The aims of this study were to examine changes in dentinal fluid flow (DFF) during the application of a desensitizing agent and to compare the permeability reduction levels among different types of desensitizing agents. A cervical cavity was prepared for the exposure of cervical dentin on an extracted human premolar connected to a subnanoliter fluid flow measuring device under 20 cm of water pressure. The cavity was acid-etched with 32% phosphoric acid to make dentin highly permeable. The different types of desensitizing agents that were applied on the cavity were Seal&Protect as the light-curing adhesive type, SuperSeal and BisBlock as oxalate types, Gluma Desensitizer as the protein-precipitation type, and Bi-Fluoride 12 as the fluoride type. DFF was measured from the time before the application of the desensitizing agent throughout the application procedure to five minutes after the application. The characteristics of dentinal tubule occlusion of each desensitizing agent were examined by scanning electron microscopy. The DFF rate after each desensitizing agent application was significantly reduced when compared to the initial DFF rate before application for all of the desensitizing agents (p<0.05). Seal&Protect showed a greater reduction in the DFF rate when compared to Gluma Desensitizer and Bi-Fluoride 12 (p<0.05). SuperSeal and BisBlock exhibited a greater reduction in DFF rate when compared to Bi-Fluoride 12 (p<0.05). The dentin hypersensitivity treatment effects of the employed desensitizing agents in this study were confirmed through real-time measurements of DFF changes. The light-curing adhesive and oxalate types showed greater reduction in the DFF rate than did the protein-precipitation and fluoride types.

Biocontrol of Listeria monocytogenes in a meat model using a combination of a bacteriocinogenic strain with curing additives.

PubMed

Orihuel, Alejandra; Bonacina, Julieta; Vildoza, María José; Bru, Elena; Vignolo, Graciela; Saavedra, Lucila; Fadda, Silvina

2018-05-01

The aim of this work was to evaluate the effect of meat curing agents on the bioprotective activity of the bacteriocinogenic strain, Enterococcus (E.) mundtii CRL35 against Listeria (L.) monocytogenes during meat fermentation. The ability of E. mundtii CRL35 to grow, acidify and produce bacteriocin in situ was assayed in a meat model system in the presence of curing additives (CA). E. mundtii CRL35 showed optimal growth and acidification rates in the presence of CA. More importantly, the highest bacteriocin titer was achieved in the presence of these food agents. In addition, the CA produced a statistical significant enhancement of the enterocin CRL35 activity. This positive effect was demonstrated in vitro in a meat based culture medium, by time-kill kinetics and finally by using a beaker sausage model with a challenge experiment with the pathogenic L. monocytogenes FBUNT strain. E. mundtii CRL35 was found to be a promising strain of use as a safety adjunct culture in meat industry and a novel functional supplement for sausage fermentation, ensuring hygiene and quality of the final product. Copyright © 2018 Elsevier Ltd. All rights reserved.

Aging Studies of VCE Dismantlement Returns

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

Letant, S; Alviso, C; Pearson, M

2011-10-17

VCE is an ethylene/vinyl acetate/vinyl alcohol terpolymer binder for filled elastomers which is designed to accept high filler loadings. Filled elastomer parts consist of the binder (VCE), a curing agent (Hylene MP, diphenol-4-4{prime}-methylenebis(phenylcarbamate)), a processing aid (LS, lithium stearate), and filler particles (typically 70% fraction by weight). The curing of the filled elastomer parts occurs from the heat-activated reaction between the hydroxyl groups of VCE with the Hylene MP curing agent, resulting in a cross-linked network. The final vinyl acetate content is typically between 34.9 and 37.9%, while the vinyl alcohol content is typically between 1.27 and 1.78%. Surveillance datamore » for this material is both scarce and scattered, complicating the assessment of any aging trends in systems. In addition, most of the initial surveillance efforts focused on mechanical properties such as hardness and tensile strength, and chemical information is therefore lacking. Material characterization and aging studies had been performed on previous formulations of the VCE material but the Ethylene Vinyl Acetate (EVA) starting copolymer is no longer commercially available. New formulations with replacement EVA materials are currently being established and will require characterization as well as updated aging models.« less

Flammability of Epoxy Resins Containing Phosphorus

NASA Technical Reports Server (NTRS)

Hergenrother, P. M.; Thompson, C. M.; Smith, J. G.; Connell, J. W.; Hinkley, J. A.

2005-01-01

As part of a program to develop fire-resistant exterior composite structures for future subsonic commercial and general aviation aircraft, flame-retardant epoxy resins are under investigation. Epoxies and their curing agents (aromatic diamines) containing phosphorus were synthesized and used to prepare epoxy formulations. Phosphorus was incorporated within the backbone of the epoxy resin and not used as an additive. The resulting cured neat epoxy formulations were characterized by thermogravimetric analysis, propane torch test, elemental analysis, microscale combustion calorimetry, and fire calorimetry. Several formulations showed excellent flame retardation with phosphorous contents as low as 1.5% by weight. The fracture toughness and compressive strength of several cured formulations showed no detrimental effect due to phosphorus content. The chemistry and properties of these new epoxy formulations are discussed.

Calcium and α-tocopherol suppress cured-meat promotion of chemically induced colon carcinogenesis in rats and reduce associated biomarkers in human volunteers123

PubMed Central

Martin, Océane CB; Santarelli, Raphaelle L; Taché, Sylviane; Naud, Nathalie; Guéraud, Françoise; Audebert, Marc; Dupuy, Jacques; Meunier, Nathalie; Attaix, Didier; Vendeuvre, Jean-Luc; Mirvish, Sidney S; Kuhnle, Gunter CG; Cano, Noel; Corpet, Denis E

2013-01-01

Background: Processed meat intake has been associated with increased colorectal cancer risk. We have shown that cured meat promotes carcinogen-induced preneoplastic lesions and increases specific biomarkers in the colon of rats. Objectives: We investigated whether cured meat modulates biomarkers of cancer risk in human volunteers and whether specific agents can suppress cured meat–induced preneoplastic lesions in rats and associated biomarkers in rats and humans. Design: Six additives (calcium carbonate, inulin, rutin, carnosol, α-tocopherol, and trisodium pyrophosphate) were added to cured meat given to groups of rats for 14 d, and fecal biomarkers were measured. On the basis of these results, calcium and tocopherol were kept for the following additional experiments: cured meat, with or without calcium or tocopherol, was given to dimethylhydrazine-initiated rats (47% meat diet for 100 d) and to human volunteers in a crossover study (180 g/d for 4 d). Rat colons were scored for mucin-depleted foci, putative precancer lesions. Biomarkers of nitrosation, lipoperoxidation, and cytotoxicity were measured in the urine and feces of rats and volunteers. Results: Cured meat increased nitroso compounds and lipoperoxidation in human stools (both P < 0.05). Calcium normalized both biomarkers in rats and human feces, whereas tocopherol only decreased nitro compounds in rats and lipoperoxidation in feces of volunteers (all P < 0.05). Last, calcium and tocopherol reduced the number of mucin-depleted foci per colon in rats compared with nonsupplemented cured meat (P = 0.01). Conclusion: Data suggest that the addition of calcium carbonate to the diet or α-tocopherol to cured meat may reduce colorectal cancer risk associated with cured-meat intake. This trial was registered at clinicaltrials.gov as NCT00994526. PMID:24025632

Survival of selected foodborne pathogens on dry cured pork loins.

PubMed

Morales-Partera, Ángela M; Cardoso-Toset, Fernando; Jurado-Martos, Francisco; Astorga, Rafael J; Huerta, Belén; Luque, Inmaculada; Tarradas, Carmen; Gómez-Laguna, Jaime

2017-10-03

The safety of ready-to-eat products such as cured pork loins must be guaranteed by the food industry. In the present study, the efficacy of the dry curing process of pork loins obtained from free-range pigs in the reduction of three of the most important foodborne pathogens is analysed. A total of 28 pork loin segments, with an average weight of 0.57±0.12kg, were divided into four groups with three being inoculated by immersion with 7logCFU/ml of either Salmonella Typhimurium, Campylobacter coli or Listeria innocua and the last one inoculated by immersion with sterile medium (control group). The loin segments were treated with a seasoning mixture of curing agents and spices, packed in a synthetic sausage casing and cured for 64days. Microbiological analysis, pH and water activity (a w ) were assessed at four stages. The values of pH and a w decreased with curing time as expected. S. Typhimurium and C. coli dropped significantly (3.28 and 2.14 log units, respectively), but limited reduction of L. innocua (0.84 log unit) was observed along the curing process. In our study, three factors were considered critical: the initial concentration of the bacteria, the progressive reduction of pH and the reduction of a w values. Our results encourage performing periodic analysis at different stages of the manufacturing of dry cured pork loins to ensure the absence of the three evaluated foodborne pathogens. Copyright © 2017 Elsevier B.V. All rights reserved.

Interference of oral hygiene products with an adhesion-based assay of salivary mutans streptococci.

PubMed

Söderling, E; Ketola, T; Parviainen, T

1991-04-01

The effect of several oral hygiene products on an adhesion-based assay for salivary mutans streptococci (Dentocult-SM Strip Mutans) was studied in three women. The mutans streptococci levels were recorded for up to 24 h after a 1-min rinse with the product. The chlorhexidine (0.05%) and stanno-amine fluoride solutions (corresponding 0.025% F) interfered selectively with the adhesion-based assay. No such effect was observed for a polyvidoneiodine solution (10 micrograms/ml) or two toothpastes containing either sodium lauryl sulfate or amine fluorides. The results indicate that antimicrobial agents showing retention in the oral cavity may interfere for several hours after their use with adhesion-based assays of salivary mutans streptococci.

Deprotonation of hydrogen bonded Schiff bases by three strong nitrogen bases

NASA Astrophysics Data System (ADS)

Schilf, Wojciech; Cmoch, Piotr; Szady-Chełmieniecka, Anna; Grech, Eugeniusz

2009-03-01

Three Schiff bases obtained from substituted salicylaldehydes and 2-hydroxy-1-naphthaldehyde and aliphatic amines were investigated in terms of possible withdrawal of tautomeric proton from intramolecular hydrogen bridge. Three strong nitrogen bases: 1,8-bis(dimethylamino)naphtalene (DMAN), 1,1,3,3-tetramethylguanidine (TMG) and 1,8-bis(tetramethylguanidino)naphthalene (TMGN) were used as deprotonating agents in acetonitrile solution at room temperature. In the specified conditions it was found that only in the case of 5-nitrosalicylaldehyde and isopropyl amine derivative this process could be performed using TMG and TMGN as a base. The other derivatives, where bridged proton is shifted to oxygen or nitrogen atom, do not undergo such reaction. The deprotonation process was monitored by nitrogen and proton NMR measurements.

Preparation of Pd/Fe3O4 nanoparticles by use of Euphorbia stracheyi Boiss root extract: A magnetically recoverable catalyst for one-pot reductive amination of aldehydes at room temperature.

PubMed

Nasrollahzadeh, Mahmoud; Sajadi, S Mohammad

2016-02-15

We describe a method for supporting palladium nanoparticles on magnetic nanoparticles using Euphorbia stracheyi Boiss root extract as the natural source of reducing and stabilizing agent. The progress of the reaction was monitored using UV-visible spectroscopy. The nanocatalyst was characterized by FE-SEM, TEM, XRD, EDS, FT-IR spectroscopy and ICP. The nanocatalyst was applied as an efficient, magnetically recoverable, highly reusable and heterogeneous catalyst for one-pot reductive amination of aldehydes at room temperature. The nanocatalyst was easily recovered by applying an external magnet and reused several times without considerable loss of activity. Copyright © 2015 Elsevier Inc. All rights reserved.

A fast, reliable, ultra high performance liquid chromatography method for the simultaneous determination of amino acids, biogenic amines and ammonium ions in cheese, using diethyl ethoxymethylenemalonate as a derivatising agent.

PubMed

Redruello, Begoña; Ladero, Victor; Cuesta, Isabel; Álvarez-Buylla, Jorge R; Martín, María Cruz; Fernández, María; Alvarez, Miguel A

2013-08-15

Derivatisation treatment with diethyl ethoxymethylenemalonate followed by ultra-HPLC allowed the simultaneous quantification of 22 amino acids, 7 biogenic amines and ammonium ions in cheese samples in under 10 min. This is the fastest elution time ever reported for such a resolution. The proposed method shows good linearity (R(2)>0.995) and sensitivity (detection limit 0.08-3.91 μM; quantification limit <13.02 μM). Intra- and inter-day repeatability ranged from 0.35% to 1.25% and from 0.85% to 5.2%, respectively. No significant effect of the cheese matrix was observed. Copyright © 2013 Elsevier Ltd. All rights reserved.

Graphite-reinforced bone cement

NASA Technical Reports Server (NTRS)

Knoell, A. C.

1976-01-01

Chopped graphite fibers added to surgical bone cement form bonding agent with mechanical properties closely matched to those of bone. Curing reaction produces less heat, resulting in reduced traumatization of body tissues. Stiffness is increased without affecting flexural strength.

Thermal expansion of an epoxy-glass microsphere composite

NASA Technical Reports Server (NTRS)

Price, H. L.; Burks, H. D.

1977-01-01

The thermal expansion of a composite of epoxy (diglycidyl ether of bisphenol A) and solid glass microspheres was investigated. The microspheres had surfaces which were either untreated or treated with a silicone release agent, an epoxy coupling agent, or a general purpose silane coupling agent. Both room temperature (about 300 K) and elevated temperature (about 475 K) cures were used for the epoxy. Two microsphere size ranges were used, about 50 microns, which is applicable in filled moldings, and about 125 microns, which is applicable as bond line spacers. The thermal expansion of the composites was measured from 300 to 350 K or from 300 to 500 K, depending on the epoxy cure temperature. Measurements were made on composites containing up to .6 volume fraction microspheres. Two predictive models, which required only the values of thermal expansion of the polymer and glass and their specific gravities, were tested against the experimental data. A finite element analysis was made of the thermal strain of a composite cell containing a single microsphere surrounded by a finite-thickness interface.

Tailored functionalization of iron oxide nanoparticles for MRI, drug delivery, magnetic separation and immobilization of biosubstances.

PubMed

Hola, Katerina; Markova, Zdenka; Zoppellaro, Giorgio; Tucek, Jiri; Zboril, Radek

2015-11-01

In this critical review, we outline various covalent and non-covalent approaches for the functionalization of iron oxide nanoparticles (IONPs). Tuning the surface chemistry and design of magnetic nanoparticles are described in relation to their applicability in advanced medical technologies and biotechnologies including magnetic resonance imaging (MRI) contrast agents, targeted drug delivery, magnetic separations and immobilizations of proteins, enzymes, antibodies, targeting agents and other biosubstances. We review synthetic strategies for the controlled preparation of IONPs modified with frequently used functional groups including amine, carboxyl and hydroxyl groups as well as the preparation of IONPs functionalized with other species, e.g., epoxy, thiol, alkane, azide, and alkyne groups. Three main coupling strategies for linking IONPs with active agents are presented: (i) chemical modification of amine groups on the surface of IONPs, (ii) chemical modification of bioactive substances (e.g. with fluorescent dyes), and (iii) the activation of carboxyl groups mainly for enzyme immobilization. Applications for drug delivery using click chemistry linking or biodegradable bonds are compared to non-covalent methods based on polymer modified condensed magnetic nanoclusters. Among many challenges, we highlight the specific surface engineering allowing both therapeutic and diagnostic applications (theranostics) of IONPs and magnetic/metallic hybrid nanostructures possessing a huge potential in biocatalysis, green chemistry, magnetic bioseparations and bioimaging. Copyright © 2015 Elsevier Inc. All rights reserved.

Fatigue crack propagation in self-assembling nanocomposites

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

Klingler, Andreas; Wetzel, Bernd

Self-assembling block-copolymers allow the easy manufacturing of nanocomposites due to the thermodynamically driven in situ formation of nanosized phases in thermosetting resins during the curing process. Complex mechanical dispersion processes can be avoided. The current study investigates the effect of a block-copolymer on the fatigue crack propagation resistance of a cycloaliphatic amine cured epoxy resin. It was found that a small amount of MAM triblock-copolymer significantly increases the resistance to fatigue crack propagation of epoxy. Crack growth rate and the Paris law exponent for fatigue-crack growth were considerably reduced from m=15.5 of the neat epoxy to m=8.1 of the nanocomposite.more » To identify the related reinforcing and fracture mechanisms structural analyses of the fractured surfaces were performed by scanning electron microscope. Characteristic features were identified to be deformation, debonding and fracture of the nano-phases as well as crack pinning. However, the highest resistance against fatigue crack propagation was achieved in a bi-continuous microstructure that consisted of an epoxy-rich phase with embedded submicron sized MAM inclusions, and which was surrounded by a block-copolymer-rich phase that showed rupture and plastic deformation.« less

Performance of purified grape pomace as a fining agent to reduce the levels of some contaminants from wine.

PubMed

Jiménez-Martínez, María Dolores; Gil-Muñoz, Rocío; Gómez-Plaza, Encarna; Bautista-Ortín, Ana Belén

2018-03-30

The quality of red wine depends on the absence of compounds which may affect its safety and/or stability such as ochratoxin A, biogenic amines and some metals and trace compounds. The presence of ochratoxin A in musts and wines is due to fungal contamination of the grapes and has been classified as a possible human carcinogen. Biogenic amines are formed by the microbiological descarboxylation of the corresponding amino acid precursors during the fermentation or aging and storage, and, at high concentrations, they may induce adverse reactions in sensitive people. Trace elements may have both a nutritional and a toxic effect on health, but also can cause turbidity and stability problems. Their presence is affected mainly by natural factors such as soil mineral content and direct contact with tank surfaces and metallic tubing during winemaking. One of the best options to remove these compounds when present in excess in wine is fining. However, some fining agents commonly used may themselves present problems related with their allergenic properties or with their propensity to increase the protein content, which can cause turbidity problems. In an attempt to avoid such these problems, purified grape pomace was tested as a fining alternative since it has been seen to have a high capacity to reduce the astringency, turbidity and also the ochratoxin A content. The main aim of this work, therefore, was to study if this material can limit the presence of ochratoxin A, biogenic amines and metals and some trace elements in a Monastrell red wine, thus increasing the value and safety of this product.

Linker design for the modular assembly of multifunctional and targeted platinum(ii)-containing anticancer agents.

PubMed

Ding, S; Bierbach, U

2016-08-16

A versatile and efficient modular synthetic platform was developed for assembling multifunctional conjugates and targeted forms of platinum-(benz)acridines, a class of highly cytotoxic DNA-targeted hybrid agents. The synthetic strategy involved amide coupling between succinyl ester-modified platinum compounds (P1, P2) and a set of 11 biologically relevant primary and secondary amines (N1-N11). To demonstrate the feasibility and versatility of the approach, a structurally and functionally diverse range of amines was introduced. These include biologically active molecules, such as rucaparib (a PARP inhibitor), E/Z-endoxifen (an estrogen receptor antagonist), and a quinazoline-based tyrosine kinase inhibitor. Micro-scale reactions in Eppendorf tubes or on 96-well plates were used to screen for optimal coupling conditions in DMF solution with carbodiimide-, uronium-, and phosphonium-based compounds, as well as other common coupling reagents. Reactions with the phosphonium-based coupling reagent PyBOP produced the highest yields and gave the cleanest conversions. Furthermore, it was demonstrated that the chemistry can also be performed in aqueous media and is amenable to parallel synthesis based on multiple consecutive reactions in DMF in a "one-tube" format. In-line LC-MS was used to assess the stability of the conjugates in physiologically relevant buffers. Hydrolysis of the conjugates occurs at the ester moiety and is facilitated by the aquated metal moiety under low-chloride ion conditions. The rate of ester cleavage greatly depends on the nature of the amine component. Potential applications of the linker technology are discussed.

Toughened epoxy resin system and a method thereof

DOEpatents

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

1998-03-10

Mixtures of epoxy resins with cationic initiators are curable under high energy ionizing radiation such as electron beam radiation, X-ray radiation, and gamma radiation. The composition of this process consists of an epoxy resin, a cationic initiator such as a diaryliodonium or triarylsulfonium salt of specific anions, and a toughening agent such as a thermoplastic, hydroxy-containing thermoplastic oligomer, epoxy-containing thermoplastic oligomer, reactive flexibilizer, rubber, elastomer, or mixture thereof. Cured compositions have high glass transition temperatures, good mechanical properties, and good toughness. These properties are comparable to those of similar thermally cured epoxies.

Toughened epoxy resin system and a method thereof

DOEpatents

Janke, Christopher J.; Dorsey, George F.; Havens, Stephen J.; Lopata, Vincent J.

1998-01-01

Mixtures of epoxy resins with cationic initiators are curable under high energy ionizing radiation such as electron beam radiation, X-ray radiation, and gamma radiation. The composition of this process consists of an epoxy resin, a cationic initiator such as a diaryliodonium or triarylsulfonium salt of specific anions, and a toughening agent such as a thermoplastic, hydroxy-containing thermoplastic oligomer, epoxy-containing thermoplastic oligomer, reactive flexibilizer, rubber, elastomer, or mixture thereof. Cured compositions have high glass transition temperatures, good mechanical properties, and good toughness. These properties are comparable to those of similar thermally cured epoxies.

Structure-Stability Relationships of Polymers Based on Thermogravimetric Analysis Data. Part 1. Polyaliphatics, Polyalicyclics, Spiro Polymers and Phenylene-R-Polymers

DTIC Science & Technology

1974-12-01

Polymerization 13 9. Polymers with Bridged Ring Systems 14 10. Spiro Polymers 14 11. Polyphenylene s 16 12. Phenol - Formaldehyde Resins 17 13. Polyphenylene... Formaldehyde Resins A wide variety of phenol- formaldehyde resins , cured with various curing agents, has been evaluated. The Tdec’s (N 2 ), which...415 0 570 415 540C 2- 410 0 -CHI - 0- c-Ci.f-CCH = 1-eC.- 390 540 0 (Phenol- Formaldehyde Resins ) -CVH- (aliph.) 390 / F_ 535 0 - CHL" (epoxy

[Sclerotherapy of idiopatic hydrocele with polidocanol: a study about 190 cases].

PubMed

Sallami, Sataa; Binous, Mohamed Yassine; Ben Rhouma, Sami; Chelif, Mohamed; Hmidi, Mohamed; Nouira, Yasssine; Ben Rais, Nawfel; Horchani, Ali

2011-05-01

To evaluate the efficacy and side-effects of Polidocanol used as sclerosing agent for testicular hydrocele. One hundred and ninety men, with a median age of 55,9 years (40-89), treated for idiopatic hydrocele were assessed. After puncture and aspiration, the empty sac was instilled with 3% Polidocanol. We recorded recurrence, complications and associated pain on a visual analogue scale. With a median follow-up of 19 months, The cure rate of hydroceles after one sclerotherapy session was 62,1%, and the overall cure rate using the procedure was 82,6%. Re-instillation was done for recurrences in 41% of patients. Polidocanol therapy was almost pain-free. A low rate of complications was observed. Polidocanol is a useful sclerosing agent for treating testicular hydrocele. Due to its ease of administration, low frequency of complications, high rate of effectiveness, and excellent tolerability; we recommend sclerotherapy with polidocanol as the primary treatment for hydroceles.

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. Copyright © 2015 Elsevier Ltd. All rights reserved.

Management of Aspergillus osteomyelitis: report of failure of liposomal amphotericin B and response to voriconazole in an immunocompetent host and literature review.

PubMed

Stratov, I; Korman, T M; Johnson, P D R

2003-05-01

Presented here is a case of Aspergillus osteomyelitis in an immunocompetent patient that progressed despite surgery and prolonged treatment with liposomal amphotericin B; the report is followed by a review of the literature. The review of this case and 41 similar cases found an overall cure rate of 69%. The importance of surgery when amphotericin B is used as first-line therapy is indicated by a 14% cure rate when amphotericin B is used alone compared to 75% when combined with surgery. When therapy is failing or surgery is contraindicated, dose escalation using a lipid formulation was not effective. On review, the addition of another agent, in particular 5-fluorocytosine, appears to be more beneficial. The patient reported here responded rapidly to voriconazole, a promising new antifungal agent for Aspergillus infections.

Highly flexible transparent self-healing composite based on electrospun core-shell nanofibers produced by coaxial electrospinning for anti-corrosion and electrical insulation

NASA Astrophysics Data System (ADS)

An, Seongpil; Liou, Minho; Song, Kyo Yong; Jo, Hong Seok; Lee, Min Wook; Al-Deyab, Salem S.; Yarin, Alexander L.; Yoon, Sam S.

2015-10-01

Coaxial electrospinning was used to fabricate two types of core-shell fibers: the first type with liquid resin monomer in the core and polyacrylonitrile in the shell, and the second type with liquid curing agent in the core and polyacrylonitrile in the shell. These two types of core-shell fibers were mutually entangled and embedded into two flexible transparent matrices thus forming transparent flexible self-healing composite materials. Such materials could be formed before only using emulsion electrospinning, rather than coaxial electrospinning. The self-healing properties of such materials are associated with release of healing agents (resin monomer and cure) from nanofiber cores in damaged locations with the subsequent polymerization reaction filing the micro-crack with polydimethylsiloxane. Transparency of these materials is measured and the anti-corrosive protection provided by them is demonstrated in electrochemical experiments.

Tinea and Onychomycosis.

PubMed

Rosen, Theodore

2016-06-01

Onychomycosis and tinea pedis are common fungal infections affecting the nails and feet, respectively. Two newly approved topical agents for onychomycosis are efinaconazole and tavaborole, both of which have demonstrated respectable cure rates in clinical studies. For tinea pedis, naftifine 2% and luliconazole 1% are new agents, both administered for relatively short courses, that may foster greater adherence Semin Cutan Med Surg 35(supp6):S110-S113. 2016 published by Frontline Medical Communications.

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

Lee, J.R.; Kim, J.H.

The weight loss and flexural property changes of the autoclave cured carbon/epoxy (0{degree}){sub 8} laminates toughened by CTBN at the temperatures of 200, 250 and 300{degree}C for the endurance times of 1, 2, 4, 8 and 16 hours were measured. The matrix resins is composed of 100 phr of tetrafunctional epoxy resin (MY-720), 28 phr of Diamine-diphenyl sulfone (DDS) and 1 phr of Borontrifluoride monoethylene amine (BF{sub 3}{center_dot}MEA). The added contents of CTBN were 5, 10 and 15% by weight to the matrix resins. The addition of CTBN improves the thermal stability of the carbon/epoxy specimens in terms of weightmore » loss and flexural modulus. But the flexural strength was decreased by addition of CTBN.« less

Thiamphenicol in the treatment of chancroid. A study of 1,128 cases.

PubMed

Belda Junior, W; Siqueira, L F; Fagundes, L J

2000-01-01

Thiamphenicol, an aminic derivate of hydrocarbilsulfonil propandiol, was used for the treatment of 1,171 chancroid bearing patients. Each patient was medicated with 5.0 g of granulated thiamphenicol, orally, in a single dose, and was reevaluated 3, 7 and 10 days after the treatment. Ten patients (0.89%) did not respond to the proposed treatment. 133 patients presented healed ulcers after 3 days of treatment, 976 patients healed chancres on the seventh day after the treatment, and 39 patients took 10 days to present healed chancres. The results of this study indicate that the rate of patients that were cured, the low incidence of side effects, and the practicality of administration make of thiamphenicol an excellent choice for the treatment of chancroid.

Overall migration and specific migration of bisphenol A diglycidyl ether monomer and m-xylylenediamine hardener from an optimized epoxy-amine formulation into water-based food simulants.

PubMed

Simal Gándara, J; López Mahía, P; Paseiro Losada, P; Simal Lozano, J; Paz Abuín, S

1993-01-01

The overall and specific migrations of BADGE n = 0 monomer and m-XDA hardener from a BEPOX LAB 889 (Gairesa internal code), epoxy system cured at room temperature, into three water-based food simulants are studied. Hydrolysis of BADGE n = 0 was observed in all of these simulants, giving more polar products. We thus propose changing the EEC Directives, which at present only legislate for levels of BADGE n = 0 monomer in the simulants, to include the hydrolysis products of BADGE monomers. Another alternative would be to express all the migration levels due to BADGE and its derived products in terms of BADGE itself.

Crystallization of a pentapeptide-repeat protein by reductive cyclic pentylation of free amines with glutaraldehyde

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

Vetting, Matthew W., E-mail: vetting@aecom.yu.edu; Hegde, Subray S.; Blanchard, John S.

2009-05-01

A method to modify proteins with glutaraldehyde under reducing conditions is presented. Treatment with glutaraldehyde and dimethylaminoborane was found to result in cyclic pentylation of free amines and facilitated the structural determination of a protein previously recalcitrant to the formation of diffraction quality crystals. The pentapeptide-repeat protein EfsQnr from Enterococcus faecalis protects DNA gyrase from inhibition by fluoroquinolones. EfsQnr was cloned and purified to homogeneity, but failed to produce diffraction-quality crystals in initial crystallization screens. Treatment of EfsQnr with glutaraldehyde and the strong reducing agent borane–dimethylamine resulted in a derivatized protein which produced crystals that diffracted to 1.6 Å resolution;more » their structure was subsequently determined by single-wavelength anomalous dispersion. Analysis of the derivatized protein using Fourier transform ion cyclotron resonance mass spectrometry indicated a mass increase of 68 Da per free amino group. Electron-density maps about a limited number of structurally ordered lysines indicated that the modification was a cyclic pentylation of free amines, producing piperidine groups.« less

Nanotechnology approaches to eradicating HIV reservoirs.

PubMed

Cao, Shijie; Woodrow, Kim A

2018-06-04

The advent of combination antiretroviral therapy (cART) has transformed HIV-1 infection into a controllable chronic disease, but these therapies are incapable of eradicating the virus to bring about an HIV cure. Multiple strategies have been proposed and investigated to eradicate latent viral reservoirs from various biological sanctuaries. However, due to the complexity of HIV infection and latency maintenance, a single drug is unlikely to eliminate all HIV reservoirs and novel strategies may be needed to achieve better efficacy while limiting systemic toxicity. In this review, we describe HIV latency in cellular and anatomical reservoirs, and present an overview of current strategies for HIV cure with a focus on their challenges for clinical translation. We also provide a summary of nanotechnology solutions that have been used to address challenges in HIV cure by delivering physicochemically diverse agents for combination therapy or targeting HIV reservoir sites. We also review nanocarrier-based gene delivery and immunotherapy used in cancer treatment but may have potential applications in HIV cure. Copyright © 2018. Published by Elsevier B.V.

Effects of adding red wine on the physicochemical properties and sensory characteristics of uncured frankfurter-type sausage.

PubMed

Feng, Xi; Sebranek, Joseph G; Lee, Hyun Yong; Ahn, Dong Uk

2016-11-01

The aim of this work was to evaluate the quality and sensory characteristics of RTE frankfurter-type sausage cured with celery juice powder and including red wine. Four frankfurter treatments including a conventionally cured treatment without red wine (control) and three treatments cured with pre-converted vegetable juice powder and 0%, 5% or 10% (v/w) red wine were prepared. Results showed that adding 5% red wine increased the a*-value, and the textural resilience, cohesiveness and springiness of the frankfurters, as well as decreased lipid/protein oxidation of the final products. Added wine also introduced new volatiles (alcohol and ester compounds) to the frankfurters. The principal component (PC) analysis showed that the pre-converted vegetable juice powder achieved the same effects as the conventional curing agents for typical frankfurter properties. However, the addition of excess amounts of red wine (10%) to the meat batter decreased the pH of meat batter and accelerated lipid oxidation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis and properties of a bio-based epoxy resin with high epoxy value and low viscosity.

PubMed

Ma, Songqi; Liu, Xiaoqing; Fan, Libo; Jiang, Yanhua; Cao, Lijun; Tang, Zhaobin; Zhu, Jin

2014-02-01

A bio-based epoxy resin (denoted TEIA) with high epoxy value (1.16) and low viscosity (0.92 Pa s, 258C) was synthesized from itaconic acid and its chemical structure was confirmed by 1H NMR and 13C NMR spectroscopy. Its curing reaction with poly(propylene glycol) bis(2-aminopropyl ether) (D230) and methyl hexahydrophthalic anhydride (MHHPA) was investigated. For comparison, the commonly used diglycidyl ether of bisphenol A (DGEBA) was also cured with the same curing agents. The results demonstrated that TEIA showed higher curing reactivity towards D230/MHHPA and lower viscosity compared with DGEBA, resulting in the better processability. Owing to its high epoxy value and unique structure, comparable or better glass transition temperature as well as mechanical properties could be obtained for the TEIA-based network relative to the DGEBA-based network. The results indicated that itaconic acid is a promising renewable feedstock for the synthesis of bio-based epoxy resin with high performance.

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.

Primary, secondary, and tertiary amines for CO2 capture: designing for mesoporous CO2 adsorbents.

PubMed

Ko, Young Gun; Shin, Seung Su; Choi, Ung Su

2011-09-15

CO(2) emissions, from fossil-fuel-burning power plants, the breathing, etc., influence the global worming on large scale and the man's work efficiency on small scale. The reversible capture of CO(2) is a prominent feature of CO(2) organic-inorganic hybrid adsorbent to sequester CO(2). Herein, (3-aminopropyl) trimethoxysilane (APTMS), [3-(methylamino)propyl] trimethoxysilane (MAPTMS), and [3-(diethylamino) propyl] trimethoxysilane (DEAPTMS) are immobilized on highly ordered mesoporous silicas (SBA-15) to catch CO(2) as primary, secondary, and tertiary aminosilica adsorbents. X-ray photoelectron spectroscopy was used to analyze the immobilized APTMS, MAPTMS, and DEAPTMS on the SBA-15. We report an interesting discovery that the CO(2) adsorption and desorption on the adsorbent depend on the amine type of the aminosilica adsorbent. The adsorbed CO(2) was easily desorbed from the adsorbent with the low energy consumption in the order of tertiary, secondary, and primary amino-adsorbents while the adsorption amount and the bonding-affinity increased in the reverse order. The effectiveness of amino-functionalized (1(o), 2(o), and 3(o) amines) SBA-15s as a CO(2) capturing agent was investigated in terms of adsorption capacity, adsorption-desorption kinetics, and thermodynamics. This work demonstrates apt amine types to catch CO(2) and regenerate the adsorbent, which may open new avenues to designing "CO(2) basket". Copyright © 2011. Published by Elsevier Inc.

Bridge decks : mitigation of cracking and increased durability.

DOT National Transportation Integrated Search

2016-06-01

The application of pre-soaked lightweight aggregates (LWA) as an internal curing agent in concrete to reduce the cracking due to drying shrinkage is thoroughly studied in this report. It is determined that although LWA can significantly reduce autoge...

Bridge Decks: Mitigation of Cracking and Increased Durability.

DOT National Transportation Integrated Search

2016-06-01

The application of pre-soaked lightweight aggregates (LWA) as an internal curing agent in concrete to reduce the cracking due to drying shrinkage is thoroughly studied in this report. It is determined that although LWA can significantly reduce autoge...

LAND AND SEA RESTORATION

EPA Pesticide Factsheets

Technical product bulletin: this bioremediation agent (nutrient additive) for oil spill cleanups can be used on water, soil, or hard surfaces. It will not damage cured asphalt if used as an absorbent for spills. Apply at 1 part to 3 parts hydrocarbon.

Effects of Grapefruit Seed Extract on Oxidative Stability and Quality Properties of Cured Chicken Breast.

PubMed

Kang, Su-Tae; Son, Hee-Kyoung; Lee, Hyun-Joo; Choi, Jung-Seok; Choi, Yang-Il; Lee, Jae-Joon

2017-01-01

This study investigated the antioxidative and functional effects of a curing agent containing grapefruit seed extract (GSE) on the quality and storage characteristics of chicken breast. The total polyphenol and total flavonoid contents of GSE were 45.06 mg/g and 36.06 mg/g, respectively. The IC 50 value of 2,2-diphenyl-1-picrylhydrazyl hydroxyl scavenging of GSE was 333.33 μg/mL. The chicken breast comprised six groups: no-treatment (N), 0.2% ascorbic acid + 70 ppm sodium nitrite (C), 0.05% GSE (G0.05), 0.1% GSE (G0.1), 0.3% GSE (G0.3), and 0.5% GSE (G0.5). The pH and cooking loss of cured chicken breast decreased with increasing GSE levels, and the water holding capacity increased with increasing GSE levels. The hardness and chewiness of GSE-treated chicken breast were higher than those of N and C. Hunter's L and a color values increased significantly after GSE addition. Moreover, 0.1% GSE (G0.1) increased the flavor and total acceptability scores. The 2-thiobarbituric acid and volatile basic nitrogen values of the 0.5% GSE group decreased significantly compared with those of C group. Total microbial counts of GSE-treated chicken breast were higher than those of C, but that lower than those of N. Adding GSE to chicken breast delayed lipid peroxidation and had antimicrobial effects during cold storage. GSE improved shelf life and palatability; therefore, it could be used as a natural antioxidant and functional curing agent ingredient in meat products.

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

PubMed Central

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

2005-01-01

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

Effects of Grapefruit Seed Extract on Oxidative Stability and Quality Properties of Cured Chicken Breast

PubMed Central

Lee, Hyun-Joo; Choi, Jung-Seok; Choi, Yang-Il

2017-01-01

This study investigated the antioxidative and functional effects of a curing agent containing grapefruit seed extract (GSE) on the quality and storage characteristics of chicken breast. The total polyphenol and total flavonoid contents of GSE were 45.06 mg/g and 36.06 mg/g, respectively. The IC50 value of 2,2-diphenyl-1-picrylhydrazyl hydroxyl scavenging of GSE was 333.33 μg/mL. The chicken breast comprised six groups: no-treatment (N), 0.2% ascorbic acid + 70 ppm sodium nitrite (C), 0.05% GSE (G0.05), 0.1% GSE (G0.1), 0.3% GSE (G0.3), and 0.5% GSE (G0.5). The pH and cooking loss of cured chicken breast decreased with increasing GSE levels, and the water holding capacity increased with increasing GSE levels. The hardness and chewiness of GSE-treated chicken breast were higher than those of N and C. Hunter's L and a color values increased significantly after GSE addition. Moreover, 0.1% GSE (G0.1) increased the flavor and total acceptability scores. The 2-thiobarbituric acid and volatile basic nitrogen values of the 0.5% GSE group decreased significantly compared with those of C group. Total microbial counts of GSE-treated chicken breast were higher than those of C, but that lower than those of N. Adding GSE to chicken breast delayed lipid peroxidation and had antimicrobial effects during cold storage. GSE improved shelf life and palatability; therefore, it could be used as a natural antioxidant and functional curing agent ingredient in meat products. PMID:28747829

Microwave-Assisted Curing of Silicon Carbide-Reinforced Epoxy Composites: Role of Dielectric Properties

NASA Astrophysics Data System (ADS)

Pal, Ranu; Akhtar, M. J.; Kar, Kamal K.

2018-05-01

In this work, the dielectric properties of epoxy-based composites are significantly improved with the help of the silicon carbide (SiC) filler at an operating frequency of 2.45 GHz to make them ideal candidates for microwave curing. The improvement is due to enhancement of the interfacial polarization because of the presence of the SiC filler. The dielectric properties are measured using the microwave cavity perturbation method. The cavity structure is simulated using the COMSOL@Multiphysics software to verify the measured data in terms of the resonant frequency. Finally, all the SiC-based composites including the neat epoxy resin are heated in the 2.45 GHz microwave oven at 300 W for 20 min. The thermal and mechanical properties of all the cured composites are measured, and the data are compared with their room temperature pre-cured counterparts. The dielectric properties of composite samples using SiC as a reinforcing agent in the epoxy are found to be substantially improved compared with those of the pure epoxy sample, which actually leads to better curing of these composite using the 2.45 GHz microwave system.

Chemoviscosity modeling for thermosetting resins - I

NASA Technical Reports Server (NTRS)

Hou, T. H.

1984-01-01

A new analytical model for chemoviscosity variation during cure of thermosetting resins was developed. This model is derived by modifying the widely used WLF (Williams-Landel-Ferry) Theory in polymer rheology. Major assumptions involved are that the rate of reaction is diffusion controlled and is linearly inversely proportional to the viscosity of the medium over the entire cure cycle. The resultant first order nonlinear differential equation is solved numerically, and the model predictions compare favorably with experimental data of EPON 828/Agent U obtained on a Rheometrics System 4 Rheometer. The model describes chemoviscosity up to a range of six orders of magnitude under isothermal curing conditions. The extremely non-linear chemoviscosity profile for a dynamic heating cure cycle is predicted as well. The model is also shown to predict changes of glass transition temperature for the thermosetting resin during cure. The physical significance of this prediction is unclear at the present time, however, and further research is required. From the chemoviscosity simulation point of view, the technique of establishing an analytical model as described here is easily applied to any thermosetting resin. The model thus obtained is used in real-time process controls for fabricating composite materials.

Thermodynamic and mechanical properties of epoxy resin DGEBF crosslinked with DETDA by molecular dynamics.

PubMed

Tack, Jeremy L; Ford, David M

2008-06-01

Fully atomistic molecular dynamics (MD) simulations were used to predict the properties of diglycidyl ether of bisphenol F (DGEBF) crosslinked with curing agent diethyltoluenediamine (DETDA). This polymer is a commercially important epoxy resin and a candidate for applications in nanocomposites. The calculated properties were density and bulk modulus (at near-ambient pressure and temperature) and glass transition temperature (at near-ambient pressure). The molecular topology, degree of curing, and MD force-field were investigated as variables. The models were created by densely packing pre-constructed oligomers of different composition and connectivity into a periodic simulation box. For high degrees of curing (greater than 90%), the density was found to be insensitive to the molecular topology and precise value of degree of curing. Of the two force-fields that were investigated, cff91 and COMPASS, the latter clearly gave more accurate values for the density as compared to experiment. In fact, the density predicted by COMPASS was within 6% of reported experimental values for the highly crosslinked polymer. The predictions of both force-fields for glass transition temperature were within the range of reported experimental values, with the predictions of cff91 being more consistent with a highly cured resin.

Structure Property Relationships of Biobased Epoxy Resins

NASA Astrophysics Data System (ADS)

Maiorana, Anthony Surraht

The thesis is about the synthesis, characterization, development, and application of epoxy resins derived from sustainable feedstocks such as lingo-cellulose, plant oils, and other non-food feedstocks. The thesis can be divided into two main topics 1) the synthesis and structure property relationship investigation of new biobased epoxy resin families and 2) mixing epoxy resins with reactive diluents, nanoparticles, toughening agents, and understanding co-curing reactions, filler/matrix interactions, and cured epoxy resin thermomechanical, viscoelastic, and dielectric properties. The thesis seeks to bridge the gap between new epoxy resin development, application for composites and advanced materials, processing and manufacturing, and end of life of thermoset polymers. The structures of uncured epoxy resins are characterized through traditional small molecule techniques such as nuclear magnetic resonance, high resolution mass spectrometry, and infrared spectroscopy. The structure of epoxy resin monomers are further understood through the process of curing the resins and cured resins' properties through rheology, chemorheology, dynamic mechanical analysis, tensile testing, fracture toughness, differential scanning calorimetry, scanning electron microscopy, thermogravimetric analysis, and notched izod impact testing. It was found that diphenolate esters are viable alternatives to bisphenol A and that the structure of the ester side chain can have signifi-cant effects on monomer viscosity. The structure of the cured diphenolate based epoxy resins also influence glass transition temperature and dielectric properties. Incorporation of reactive diluents and flexible resins can lower viscosity, extend gel time, and enable processing of high filler content composites and increase fracture toughness. Incorpora-tion of high elastic modulus nanoparticles such as graphene can provide increases in physical properties such as elastic modulus and fracture toughness. The synthesis of epoxy resins with aliphatic esters in the main chain of the polymer allow for chemical recycling under alkaline conditions and changing the hydrophobicity and access of main chain esters influences the rate of polymer degradation. The thesis further provides strategies and concepts that will allow for future researchers to rapidly understand how to manipulate epoxy resins for specific end uses and supplements current understanding of epoxy curing agents, accelerators, and interactions with fillers.

Is aspiration and sclerotherapy treatment for hydroceles in the aging male an evidence-based treatment?

PubMed

Taylor, W St J; Cobley, J; Mahmalji, W

2018-01-16

Symptomatic hydroceles are commonly treated with surgical repair. They are associated with sexual dysfunction in the aging male. Patients who are not fit for surgery often undergo aspiration and sclerotherapy of the hydrocele. There is a range of sclerosing agents used in the literature. I performed a literature search to assess whether one sclerosant was better than the others. STDS is the sclerosing agent with the best cure rate after a single injection and low side effect rates. The cure rates of sodium tetradecyl sulphate (STDS) after a single aspiration and injection were 76%. After multiple treatments 94% achieved a cure. Patient satisfaction rates at mean 40 months were 95%. Complication rates were generally low and much lower than surgical repair. Aspiration and sclerotherapy have a role in treating symptomatic hydroceles. This literature review shows that this is over and above its current use in the UK, where it is used for patients unfit for general anaesthetic. If the patients are carefully selected for this procedure, they can have a good outcome and avoid the higher complication rate and longer recovery rates of surgical repair. Patients should be counselled about aspiration and sclerotherapy as part of the informed consent process.

Adhesion of Candida albicans to Vanillin Incorporated Self-Curing Orthodontic PMMA Resin.

NASA Astrophysics Data System (ADS)

Zam, K.; Sawaengkit, P.; Thaweboon, S.; Thaweboon, B.

2018-02-01

It has been observed that there is an increase in Candida carriers during the treatment with orthodontic removable appliance. Vanillin is flavouring agent, which is known to have antioxidant and antimicrobial properties. The aim of this study was to evaluate the effect of vanillin incorporated PMMA on adhesion of Candida albicans. A total of 36 orthodontic self-curing PMMA resin samples were fabricated. The samples were divided into 3 groups depending on percentage of vanillin incorporated (0.1%, 0.5% and PMMA without vanillin as control). PMMA samples were coated with saliva. The adhesion assay was performed with C. albicans (ATCC 10231). The adherent yeast cells were stained with crystal violet and counted under microscope by random selection of 3 fields at 10X magnification. The statistical analyses performed by Kruskal Wallis and Mann Whitney non-parametric test. It was found that the PMMA resin samples with vanillin incorporation significantly reduced the adhesion of C. albicans as compared to the control group. This study indicates that vanillin incorporated resin can impede the adhesion of C. albicans to about 45 - 56 %. With further testing and development, vanillin can be employed as an antifungal agent to prevent adhesion of C. albicans to orthodontic self-curing PMMA resin.

Polyaniline-grafted reduced graphene oxide for efficient electrochemical supercapacitors.

PubMed

Kumar, Nanjundan Ashok; Choi, Hyun-Jung; Shin, Yeon Ran; Chang, Dong Wook; Dai, Liming; Baek, Jong-Beom

2012-02-28

An alternative and effective route to prepare conducting polyaniline-grafted reduced graphene oxide (PANi-g-rGO) composite with highly enhanced properties is reported. In order to prepare PANi-g-rGO, amine-protected 4-aminophenol was initially grafted to graphite oxide (GO) via acyl chemistry where a concomitant partial reduction of GO occurred due to the refluxing and exposure of GO to thionyl chloride vapors and heating. Following the deprotection of amine groups, an in situ chemical oxidative grafting of aniline in the presence of an oxidizing agent was carried out to yield highly conducting PANi-g-rGO. Electron microscopic studies demonstrated that the resultant composite has fibrillar morphology with a room-temperature electrical conductivity as high as 8.66 S/cm and capacitance of 250 F/g with good cycling stability.

Synthesis, biological evaluation and structure-activity relationship studies of isoflavene based Mannich bases with potent anti-cancer activity.

PubMed

Chen, Yilin; Cass, Shelley L; Kutty, Samuel K; Yee, Eugene M H; Chan, Daniel S H; Gardner, Christopher R; Vittorio, Orazio; Pasquier, Eddy; Black, David StC; Kumar, Naresh

2015-11-15

Phenoxodiol, an analogue of the isoflavone natural product daidzein, is a potent anti-cancer agent that has been investigated for the treatment of hormone dependent cancers. This molecular scaffold was reacted with different primary amines and secondary amines under different Mannich conditions to yield either benzoxazine or aminomethyl substituted analogues. These processes enabled the generation of a diverse range of analogues that were required for structure-activity relationship (SAR) studies. The resulting Mannich bases exhibited prominent anti-proliferative effects against SHEP neuroblastoma and MDA-MB-231 breast adenocarcinoma cell lines. Further cytotoxicity studies against MRC-5 normal lung fibroblast cells showed that the isoflavene analogues were selective towards cancer cells. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of tributylborane-activated adhesive and two silane agents on bonding computer-aided design and manufacturing (CAD/CAM) resin composite.

PubMed

Shinohara, Ayano; Taira, Yohsuke; Sawase, Takashi

2017-10-01

The present study was conducted to evaluate the effects of an experimental adhesive agent [methyl methacrylate-tributylborane liquid (MT)] and two adhesive agents containing silane on the bonding between a resin composite block of a computer-aided design and manufacturing (CAD/CAM) system and a light-curing resin composite veneering material. The surfaces of CAD/CAM resin composite specimens were ground with silicon-carbide paper, treated with phosphoric acid, and then primed with either one of the two silane agents [Scotchbond Universal Adhesive (SC) and GC Ceramic Primer II (GC)], no adhesive control (Cont), or one of three combinations (MT/SC, MT/GC, and MT/Cont). A light-curing resin composite was veneered on the primed CAD/CAM resin composite surface. The veneered specimens were subjected to thermocycling between 4 and 60 °C for 10,000 cycles, and the shear bond strengths were determined. All data were analyzed using analysis of variance and a post hoc Tukey-Kramer HSD test (α = 0.05, n = 8). MT/SC (38.7 MPa) exhibited the highest mean bond strengths, followed by MT/GC (30.4 MPa), SC (27.9 MPa), and MT/Cont (25.7 MPa), while Cont (12.9 MPa) and GC (12.3 MPa) resulted in the lowest bond strengths. The use of MT in conjunction with a silane agent significantly improved the bond strength. Surface treatment with appropriate adhesive agents was confirmed as a prerequisite for veneering CAD/CAM resin composite restorations.

Rhenium(i) complexes of N-heterocyclic carbene ligands that bind to amyloid plaques of Alzheimer's disease.

PubMed

Chan, Chung Ying; Noor, Asif; McLean, Catriona A; Donnelly, Paul S; Barnard, Peter J

2017-02-16

A series of [Re(i)L(CO) 3 ] + complexes (where L is a bifunctional bis(NHC)-amine ligand) that are analogues of potential Tc-99m diagnostic imaging agents for Alzheimer's disease have been synthesised. One of the complexes bound to amyloid plaques in human frontal cortex brain tissue from subjects with Alzheimer's disease.

Potential therapeutic agents derived from the cannabinoid nucleus.

PubMed

Pars, H G; Howes, J F

1977-01-01

Drugs derived from Cannabis sativa (Cannabinceae) were used until the 1940's for their stimulant and depressant effects for treating somatic and psychiatric illnesses. Renewed interest in marihuana research began in the 1970's and again pointed to the therapeutic potential of cannabinoids. Safer and more useful therapeutic agents may be generated from cannabinoids similarly to morphine, lysergic acid diethylamide, and cocaine which have structurally related analgesics, oxytoxics, and local anesthetics respectively. It has been shown that the C-ring in cannabinoids can be substituted with a variety of nitrogen and sulfur-containing rings without loss of CNS (central nervous system) activity. Cannabinoids have been shown to inhibit prostaglandin synthesis, intensify pressor effects of endogenous amines like norepinephrine, and enhance the stimulant effects of amphetamine. Cannabinoids' therapeutic potential lies in the areas of analgesics and anticonvulsants, and for use as a sedative-hypnotic, an antiglaucoma agent, an antiasthmatic agent, an antidiarrheal agent, and possibly as an anticancer and immunosuppressant agent.

Biosynthesised ZnO : Dy3+ nanoparticles: Biodiesel properties and reusable catalyst for N-formylation of aromatic amines with formic acid

NASA Astrophysics Data System (ADS)

Reddy Yadav, L. S.; Raghavendra, M.; Sudheer Kumar, K. H.; Dhananjaya, N.; Nagaraju, G.

2018-04-01

ZnO nanoparticles doped with trivalent dysprosium ions (Dy3+) were prepared through the green combustion technique using E. tirucalli plant latex as a fuel. The fundamental and optical properties of the samples are examined via the X-ray diffraction, FTIR, UV-visible analytical methods and morphology by scanning electron microscope and transmission electron microscope. Rietveld refinement results show that the ZnO : Dy3+ were crystallized in the wurtzite hexagonal structure with space group P63mc (No. 186). The average particle size of ZnO : Dy3+ prepared with the different concentration of latex was found to be in the range 30-38nm, which is also confirmed by TEM analysis. A rapid and convenient method for the one-pot preparation of N-formamide derivatives aromatic amines and amino acid esters has been developed using Dy3+ doped ZnO as a catalytic agent. This method provides an efficient and much improved modification over reported protocols regarding yield, clean and work-up procedure milder reaction conditions. In this work, Pongamiapinnata oil was recycled for the preparation of biodiesel via Dy3+ doped ZnO as a catalytic agent.

Combined method for simultaneously dewatering and reconstituting finely divided carbonaceous material

DOEpatents

Wen, Wu-Wey; Deurbrouck, Albert W.

1990-01-01

A finely-divided carbonaceous material is dewatered and reconstituted in a combined process by adding a binding agent directly into slurry of finely divided material and dewatering the material to form a cake or consolidated piece which can be hardened by drying at ambient or elevated temperatures. Alternatively, the binder often in the form of a crusting agent is sprayed onto the surface of a moist cake prior to curing.

Cancer Therapy Evaluation Program | Office of Cancer Genomics

Cancer.gov

The Cancer Therapy Evaluation Program (CTEP) seeks to improve the lives of cancer patients by finding better treatments, control mechanisms, and cures for cancer. CTEP funds a national program of cancer research, sponsoring clinical trials to evaluate new anti-cancer agents.

Autogenous accelerated curing of concrete cylinders. Part IV, Moisture relationships.

DOT National Transportation Integrated Search

1971-01-01

Eighteen different concrete mixtures were proportioned to investigate the influence of cement types (II and III), water cement ratios (0.4, 0.5, and 0.6), and admixtures (accelerator, retarder, and air entraining agent) on the moisture changes during...

Salting-out assisted liquid-liquid extraction for the determination of biogenic amines in fruit juices and alcoholic beverages after derivatization with 1-naphthylisothiocyanate and high performance liquid chromatography.

PubMed

Jain, Archana; Gupta, Manju; Verma, Krishna K

2015-11-27

A new method for determining biogenic amines in fruit juices and alcoholic beverages is described involving reaction of biogenic amines with 1-naphthylisothiocyanate followed by extraction of 1-naphthylthiourea derivatives with water-miscible organic solvent acetonitrile when solvents phase separation occurred using ammonium sulphate, a process called salting-out assisted liquid-liquid extraction. The extract was analyzed by high-performance liquid chromatography with UV detection at 254nm. The new reagent avoided many of the inconveniences as observed with existing derivatizing agents, such as dansyl chloride and benzoyl chloride, in regard to their inselectivity, instability, adverse effect of excess reagent, and necessity to remove excess reagent. The procedure has been optimized with respect to reaction time and temperature, water-miscible extraction solvent, and salt for solvents phase separation. Use of reagent as dispersed phase in aqueous medium produced derivatives in high yield. A linear calibration was obtained between the amount of biogenic amines in range 1-1000μgL(-1) and peak areas of corresponding thioureas formed; the correlation coefficient was 0.9965, and the limit of detection and limit of quantification found were 1.1μgL(-1) and 3.2μgL(-1), respectively. The pre-concentration method gave an average enrichment factor of 94. The application of the method has been demonstrated in the determination of biogenic amines in commercial samples of fruit juices and alcoholic beverages. In spiking experiments to real samples, the average recovery found by the present method was 94.5% that agreed well with 95.8% obtained by established comparison methods. Copyright © 2015 Elsevier B.V. All rights reserved.

Characterization of cationic polymers by asymmetric flow field-flow fractionation and multi-angle light scattering-A comparison with traditional techniques.

PubMed

Wagner, Michael; Pietsch, Christian; Tauhardt, Lutz; Schallon, Anja; Schubert, Ulrich S

2014-01-17

In the field of nanomedicine, cationic polymers are the subject of intensive research and represent promising carriers for genetic material. The detailed characterization of these carriers is essential since the efficiency of gene delivery strongly depends on the properties of the used polymer. Common characterization methods such as size exclusion chromatography (SEC) or mass spectrometry (MS) suffer from problems, e.g. missing standards, or even failed for cationic polymers. As an alternative, asymmetrical flow field-flow fractionation (AF4) was investigated. Additionally, analytical ultracentrifugation (AUC) and (1)H NMR spectroscopy, as well-established techniques, were applied to evaluate the results obtained by AF4. In this study, different polymers of molar masses between 10 and 120kgmol(-1) with varying amine functionalities in the side chain or in the polymer backbone were investigated. To this end, some of the most successful gene delivery agents, namely linear poly(ethylene imine) (LPEI) (only secondary amines in the backbone), branched poly(ethylene imine) (B-PEI) (secondary and tertiary amino groups in the backbone, primary amine end groups), and poly(l-lysine) (amide backbone and primary amine side chains), were characterized. Moreover, poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA), poly(2-(amino)ethyl methacrylate) (PAEMA), and poly(2-(tert-butylamino)ethyl methacrylate) (PtBAEMA) as polymers with primary, secondary, and tertiary amines in the side chain, have been investigated. Reliable results were obtained for all investigated polymers by AF4. In addition, important factors for all methods were evaluated, e.g. the influence of different elution buffers and AF4 membranes. Besides this, the correct determination of the partial specific volume and the suppression of the polyelectrolyte effect are the most critical issues for AUC investigations. Copyright © 2013 Elsevier B.V. All rights reserved.

Structural and electronic properties of carbon nanotube-reinforced epoxy resins.

PubMed

Suggs, Kelvin; Wang, Xiao-Qian

2010-03-01

Nanocomposites of cured epoxy resin reinforced by single-walled carbon nanotubes exhibit a plethora of interesting behaviors at the molecular level. We have employed a combination of force-field-based molecular mechanics and first-principles calculations to study the corresponding binding and charge-transfer behavior. The simulation study of various nanotube species and curing agent configurations provides insight into the optimal structures in lieu of interfacial stability. An analysis of charge distributions of the epoxy functionalized semiconducting and metallic tubes reveals distinct level hybridizations. The implications of these results for understanding dispersion mechanism and future nano reinforced composite developments are discussed.

Unexpected cure from cutaneous leukocytoclastic vasculitis in a patient treated with N-butyldeoxynojirimycin (miglustat) for Gaucher disease.

PubMed

Machaczka, M; Klimkowska, M; Hägglund, H

2012-06-01

Cutaneous leukocytoclastic vasculitis (CLV) is a necrotizing inflammation of the small vessels in the dermis. We report the case of a Swedish man with an untreated N370S/L444P Gaucher disease who developed CLV at the age of 79 years. The patient has been treated for CLV with topical and oral corticosteroids, moisturizing agents, and periodically with antibiotics for 3 years without improvement. Administration of miglustat (N-butyldeoxynojirimycin; Zavesca®) because of progress of Gaucher disease resulted in a prompt and durable cure of the CLV.

Effects of copper amine treatments on mechanical, biological and surface/interphase properties of poly (vinyl chloride)/wood composites

NASA Astrophysics Data System (ADS)

Jiang, Haihong

2005-11-01

The copper ethanolamine (CuEA) complex was used as a wood surface modifier and a coupling agent for wood-PVC composites. Mechanical properties of composites, such as unnotched impact strength, flexural strength and flexural toughness, were significantly increased, and fungal decay weight loss was dramatically decreased by wood surface copper amine treatments. It is evident that copper amine was a very effective coupling agent and decay inhibitor for PVC/wood flour composites, especially in high wood flour loading level. A DSC study showed that the heat capacity differences (DeltaCp) of composites before and after PVC glass transition were reduced by adding wood particles. A DMA study revealed that the movements of PVC chain segments during glass transition were limited and obstructed by the presence of wood molecule chains. This restriction effect became stronger by increasing wood flour content and by using Cu-treated wood flour. Wood flour particles acted as "physical cross-linking points" inside the PVC matrix, resulting in the absence of the rubbery plateau of PVC and higher E', E'' above Tg, and smaller tan delta peaks. Enhanced mechanical performances were attributed to the improved wetting condition between PVC melts and wood surfaces, and the formation of a stronger interphase strengthened by chemical interactions between Cu-treated wood flour and the PVC matrix. Contact angles of PVC solution drops on Cu-treated wood surfaces were decreased dramatically compared to those on the untreated surfaces. Acid-base (polar), gammaAB, electron-acceptor (acid) (gamma +), electron-donor (base) (gamma-) surface energy components and the total surface energies increased after wood surface Cu-treatments, indicating a strong tendency toward acid-base or polar interactions. Improved interphase and interfacial adhesion were further confirmed by measuring interfacial shear strength between wood and the PVC matrix.

Trialkylamine Derivatives Containing a Triazole Moiety as Promising Ergosterol Biosynthesis Inhibitor: Design, Synthesis, and Antifungal Activity.

PubMed

Sui, Guoqing; Zhang, Wen; Zhou, Kun; Li, Yulin; Zhang, Bingyu; Xu, Dan; Zou, Yong; Zhou, Wenming

2017-01-01

As a part of our continuing research on amine derivative antifungal agents, 19 novel target compounds containing 1,2,4-triazole and tertiary amine moieties were designed and synthesized, and their in vitro antifungal activities against six phytopathogenic fungi (Magnaporthe grisea, Alternaria solani, Fusarium solani, Curvularia lunata, A. alternata, F. graminearum) were assayed. All target compounds were elucidated by means of 1 H-NMR, 13 C-NMR, high resolution (HR)-MS, and IR analysis. The results showed that most of the derivatives exhibited obvious activity against each of the fungi at 50 µg/mL. Among them, compounds 7f, l, and o displayed excellent activity against A. solani with median effective concentration values (EC 50 ) of 2.88, 8.20, and 1.92 µg/mL. 7o in particular was superior to tebuconazole (EC 50 =2.03 µg/mL), a commercial fungicide. Furthermore, compounds 7j, k, and m also showed good activity against F. graminearum with EC 50 values of 11.60, 5.14, and 16.24 µg/mL, and the value of 7k was extremely close to that of tebuconazole (EC 50 =3.13 µg/mL). The preliminary analysis of the structure-activity relationship (SAR) demonstrated that combination of the active structure of 1,2,4-triazole with the tertiary amine group containing benzene rings effectively increased the antifungal activities. Generally, introducing halogen atoms obviously improved activities against most of the test fungi to varying degrees, while the presence of OMe decreased the activities. Thus, the results strongly indicate that the newly synthesized derivatives should be lead compounds for the development of novel antifungal agents for the effective control of phytopathogenic fungi.

Tyramine functions as a toxin in honey bee larvae during Varroa-transmitted infection by Melissococcus pluton.

PubMed

Kanbar, G; Engels, W; Nicholson, G J; Hertle, R; Winkelmann, G

2004-05-01

From wounds of honey bee pupae, caused by the mite Varroa destructor, coccoid bacteria were isolated and identified as Melissococcus pluton. The bacterial isolate was grown anaerobically in sorbitol medium to produce a toxic compound that was purified on XAD columns, gelfiltration and preparative HPLC. The toxic agent was identified by GC-MS and FTICR-MS as tyramine. The toxicity of the isolated tyramine was tested by a novel mobility test using the protozoon Stylonychia lemnae. A concentration of 0.2 mg/ml led to immediate inhibition of mobility. In addition the toxicity was studied on honey bee larvae by feeding tyramine/water mixtures added to the larval jelly. The lethal dosis of tyramine on 4-5 days old bee larvae was determined as 0.3 mg/larvae when added as a volume of 20 microl to the larval food in brood cells. Several other biogenic amines, such as phenylethylamine, histamine, spermine, cadaverine, putrescine and trimethylamine, were tested as their hydrochloric salts for comparison and were found to be inhibitory in the Stylonychia mobility test at similar concentrations. A quantitative hemolysis test with human red blood cells revealed that tyramine and histamine showed the highest membranolytic activity, followed by the phenylethylamine, trimethylamine and spermine, while the linear diamines, cadaverine and putrescine, showed a significantly lower hemolysis when calculated on a molar amine basis. The results indicate that tyramine which is a characteristic amine produced by M. pluton in culture, is the causative agent of the observed toxic symptoms in bee larvae. Thus this disease, known as European foulbrood, is possibly an infection transmitted by the Varroa destructor mite.

Antiplaque and antigingivitis toothpastes.

PubMed

Sanz, Mariano; Serrano, Jorge; Iniesta, Margarita; Santa Cruz, Isabel; Herrera, David

2013-01-01

Dentifrices are a general term used to describe preparations that are used together with a toothbrush with the purpose to clean and/or polish the teeth. Active toothpastes were first formulated in the 1950s and included ingredients such as urea, enzymes, ammonium phosphate, sodium lauryl sarcosinate and stannous fluoride. Later, therapeutic agents were included. Today's toothpastes have two objectives: to help the toothbrush in cleaning the tooth surface and to provide a therapeutic effect. The therapeutic effect may have an antiplaque or anti-inflammatory basis when the nature of the agents is antimicrobial. Plaque inhibitory and antiplaque activity of toothpastes used for chemical plaque control is evaluated in distinct consecutive stages, the last being home use randomized clinical trials of at least 6 months' duration. In this chapter, the scientific evidence supporting the use of the most common antiplaque agents, included in toothpaste formulations, is reviewed, with a special emphasis on 6-month clinical trials, and systematic reviews with meta-analyses of the mentioned studies. Among the active agents, the following have been included in toothpastes: enzymes, amine alcohols, herbal or natural products, triclosan, bisbiguanides (chlorhexidine), quaternary ammonium compounds (cetylpyridinium chloride) and different metal salts (zinc salts, stannous fluoride, stannous fluoride with amine fluoride). Dentifrices are the ideal vehicles for any active ingredient used as an oral health preventive measure since they are used in combination with toothbrushing, which is the most frequently employed oral hygiene method. The most important indications of dentifrices with active ingredients are associated with long-term use to prevent bacterial biofilm formation, mostly in gingivitis patients or in patients on supportive periodontal therapy. Copyright © 2013 S. Karger AG, Basel.

C 3-symmetric opioid scaffolds are pH-responsive DNA condensation agents

PubMed Central

McStay, Natasha; Molphy, Zara; Coughlan, Alan; Cafolla, Attilio; McKee, Vickie; Gathergood, Nicholas; Kellett, Andrew

2017-01-01

Herein we report the synthesis of tripodal C3-symmetric opioid scaffolds as high-affinity condensation agents of duplex DNA. Condensation was achieved on both supercoiled and canonical B-DNA structures and identified by agarose electrophoresis, viscosity, turbidity and atomic force microscopy (AFM) measurements. Structurally, the requirement of a tris-opioid scaffold for condensation is demonstrated as both di- (C2-symmetric) and mono-substituted (C1-symmetric) mesitylene-linked opioid derivatives poorly coordinate dsDNA. Condensation, observed by toroidal and globule AFM aggregation, arises from surface-binding ionic interactions between protonated, cationic, tertiary amine groups on the opioid skeleton and the phosphate nucleic acid backbone. Indeed, by converting the 6-hydroxyl group of C3-morphine (MC3) to methoxy substituents in C3-heterocodeine (HC3) and C3-oripavine (OC3) molecules, dsDNA compaction is retained thus negating the possibility of phosphate—hydroxyl surface-binding. Tripodal opioid condensation was identified as pH dependent and strongly influenced by ionic strength with further evidence of cationic amine-phosphate backbone coordination arising from thermal melting analysis and circular dichroism spectroscopy, with compaction also witnessed on synthetic dsDNA co-polymers poly[d(A-T)2] and poly[d(G-C)2]. On-chip microfluidic analysis of DNA condensed by C3-agents provided concentration-dependent protection (inhibition) to site-selective excision by type II restriction enzymes: BamHI, HindIII, SalI and EcoRI, but not to the endonuclease DNase I. PMID:27899572

Brief History of Syphilis

PubMed Central

Tampa, M; Sarbu, I; Matei, C; Benea, V; Georgescu, SR

2014-01-01

Abstract Before the discovery of Treponema pallidum as the etiologic agent, the origins of syphilis have been the subject of several debates. Diverse therapeutic agents were employed in an attempt to cure the disease. Examining the milestones in the history of syphilis, the present article reviews the existing theories that tried to explain the origins of the disease, the approach in art, the cultural and the evolution of the treatments from the empiric means to the discovery of penicillin. PMID:24653750

Past, Current, and Future Developments of Therapeutic Agents for Treatment of Chronic Hepatitis B Virus Infection.

PubMed

Pei, Yameng; Wang, Chunting; Yan, S Frank; Liu, Gang

2017-08-10

For decades, treatment of hepatitis B virus (HBV) infection has been relying on interferon (IFN)-based therapies and nucleoside/nucleotide analogues (NAs) that selectively target the viral polymerase reverse transcriptase (RT) domain and thereby disrupt HBV viral DNA synthesis. We have summarized here the key steps in the HBV viral life cycle, which could potentially be targeted by novel anti-HBV therapeutics. A wide range of next-generation direct antiviral agents (DAAs) with distinct mechanisms of actions are discussed, including entry inhibitors, transcription inhibitors, nucleoside/nucleotide analogues, inhibitors of viral ribonuclease H (RNase H), modulators of viral capsid assembly, inhibitors of HBV surface antigen (HBsAg) secretion, RNA interference (RNAi) gene silencers, antisense oligonucleotides (ASOs), and natural products. Compounds that exert their antiviral activities mainly through host factors and immunomodulation, such as host targeting agents (HTAs), programmed cell death protein 1 (PD-1)/programmed death ligand 1 (PD-L1) inhibitors, and Toll-like receptor (TLR) agonists, are also discussed. In this Perspective, we hope to provide an overview, albeit by no means being comprehensive, for the recent development of novel therapeutic agents for the treatment of chronic HBV infection, which not only are able to sustainably suppress viral DNA but also aim to achieve functional cure warranted by HBsAg loss and ultimately lead to virus eradication and cure of hepatitis B.

Enantioselective Decarboxylative Arylation of α-Amino Acids via the Merger of Photoredox and Nickel Catalysis.

PubMed

Zuo, Zhiwei; Cong, Huan; Li, Wei; Choi, Junwon; Fu, Gregory C; MacMillan, David W C

2016-02-17

An asymmetric decarboxylative Csp(3)-Csp(2) cross-coupling has been achieved via the synergistic merger of photoredox and nickel catalysis. This mild, operationally simple protocol transforms a wide variety of naturally abundant α-amino acids and readily available aryl halides into valuable chiral benzylic amines in high enantiomeric excess, thereby producing motifs found in pharmacologically active agents.

The impact of high hydrostatic pressure on the functionality and consumer acceptability of reduced sodium naturally cured wieners.

PubMed

Pietrasik, Z; Gaudette, N J; Johnston, S P

2017-07-01

The effects of high pressure processing (HPP; 600MPa for 3min at 8°C) on the quality and shelf life of reduced sodium naturally-cured wieners was studied. HPP did not negatively impact processing characteristics and assisted in extending shelf life of all wiener treatments up to a 12week storage period. At week 8, HPP wieners received higher acceptability scores, indicating HPP can effectively extend the sensory quality of products, including sodium reduced formulations containing natural forms of nitrite. Substitution of 50% NaCl with modified KCl had negative effect on textural characteristics of conventionally cured wieners but not those processed with celery powder as a source of nitrite. Celery powder favorably affected hydration of textural properties of wieners, and consumer acceptability of juiciness and texture was higher compared to nitrite. Sodium reduction, independent of curing agent, negatively impacted flavor acceptability, while only nitrite containing reduced sodium wieners scored significantly lower than both regular salt wieners for texture, juiciness and saltiness. Copyright © 2017 Elsevier Ltd. All rights reserved.

An eco-friendly method for short term preservation of skins/hides using Semecarpus anacardium nut extract.

PubMed

Iyappan, Kuttalam; Ponrasu, Thangavel; Sangeethapriya, Vilvanathan; Gayathri, Vinaya Subramani; Suguna, Lonchin

2013-09-01

Preservation or curing of hides and skins is performed as the primary step of leather processing. Common salt is employed as the conventional agent for curing purpose. Use of salt enhances the pollution load of tannery effluent which becomes highly contaminated with increased total dissolved solids and chlorides. To overcome this hurdle, researchers are in constant search of alternative preservation techniques which are either totally void of salt or use only a meager amount of salt. In the present study, we had explored the possibility of using Semecarpus anacardium nut extract as an alternative to salt for the curing process by assessing different parameters like hair slip, putrefaction odor, volatile nitrogen content, moisture content, bacterial count, and shrinkage temperature in comparison to the salt curing method. The antibacterial property of the plant extract was also investigated. The results obtained substantiated that the nut extract of S. anacardium effectively could preserve the skins for more than a month, by its antibacterial activity along with the dehydrating property of acetone.

A clinical trial of Empress II porcelain inlays luted to vital teeth with a dual-curing adhesive system and a self-curing resin cement.

PubMed

Fabianelli, Andrea; Goracci, Cecilia; Bertelli, Egidio; Davidson, Carel L; Ferrari, Marco

2006-12-01

The aim of the study was to clinically evaluate Empress II inlays cemented with a dual-curing bonding agent and a self-curing luting system. Forty patients were selected to receive one Empress II inlay. Empress II is a heat-pressed glass ceramic containing lithium disilicate and lithium orthophosphate crystals, purported to provide higher stress resistance and improved strength. The restorations were placed between March and May 2000. Recalls were performed after 6, 12, 24, and 36 months. At the 3-year recall, 7 patients were lost to follow-up. Inlays were evaluated for postoperative sensitivity, marginal integrity, marginal leakage, color stability, surface staining, retention, and surface crazing (microcracks). At the 3-year recall, all the restorations were in place and only one showed postoperative sensitivity (at the first recall, 1 week after placement). Only 3 inlays showed slight marginal staining, and 4 inlays showed gaps, with little surface staining or microcracks. No inlay debonded or fractured during theobservation period. All the evaluated inlays were in place and acceptable.

Specificity enhancement by electrospray ionization multistage mass spectrometry--a valuable tool for differentiation and identification of 'V'-type chemical warfare agents.

PubMed

Weissberg, Avi; Tzanani, Nitzan; Dagan, Shai

2013-12-01

The use of chemical warfare agents has become an issue of emerging concern. One of the challenges in analytical monitoring of the extremely toxic 'V'-type chemical weapons [O-alkyl S-(2-dialkylamino)ethyl alkylphosphonothiolates] is to distinguish and identify compounds of similar structure. MS analysis of these compounds reveals mostly fragment/product ions representing the amine-containing residue. Hence, isomers or derivatives with the same amine residue exhibit similar mass spectral patterns in both classical EI/MS and electrospray ionization-MS, leading to unavoidable ambiguity in the identification of the phosphonate moiety. A set of five 'V'-type agents, including O-ethyl S-(2-diisopropylamino)ethyl methylphosphonothiolate (VX), O-isobutyl S-(2-diethylamino)ethyl methylphosphonothiolate (RVX) and O-ethyl S-(2-diethylamino)ethyl methylphosphonothiolate (VM) were studied by liquid chromatography/electrospray ionization/MS, utilizing a QTRAP mass detector. MS/MS enhanced product ion scans and multistage MS(3) experiments were carried out. Based on the results, possible fragmentation pathways were proposed, and a method for the differentiation and identification of structural isomers and derivatives of 'V'-type chemical warfare agents was obtained. MS/MS enhanced product ion scans at various collision energies provided information-rich spectra, although many of the product ions obtained were at low abundance. Employing MS(3) experiments enhanced the selectivity for those low abundance product ions and provided spectra indicative of the different phosphonate groups. Study of the fragmentation pathways, revealing some less expected structures, was carried out and allowed the formulation of mechanistic rules and the determination of sets of ions typical of specific groups, for example, methylphosphonothiolates versus ethylphosphonothiolates. The new group-specific ions elucidated in this work are also useful for screening unknown 'V'-type agents and related compounds, utilizing precursor ion scan experiments. Copyright © 2013 John Wiley & Sons, Ltd.

Involvement of the immune response in the cure of metastatic murine CT-26 colon carcinoma by low electric field-enhanced chemotherapy.

PubMed

Plotnikov, Alexander; Tichler, Thomas; Korenstein, Rafi; Keisari, Yona

2005-12-10

Low electric field cancer treatment-enhanced chemotherapy (LEFCT-EC) is a new treatment modality that combines chemotherapeutic agents and low electric field stimulation. LEFCT-EC was found to destroy malignant mouse tumors and cause massive death of tumor cells. This may enable the immune system cells to efficiently recognize and eliminate tumor cells at the primary tumor site and at metastatic foci. Mice with 15 mm diameter intracutaneous colon carcinomas (CT-26) were injected with BCNU (35 mg/kg), and 2 min later the tumors were exposed to low electric fields (intensity 40 V/cm, pulse duration 180 micros, frequency 500 Hz) for 12 min (LEFCT-EC). We found that treatment with LEFCT-EC achieved complete cure of 93% of the animals. In comparison, electric fields alone (13% cure), chemotherapy alone (0%), surgery (15%) or a combination of surgery and bis-chloroethyl-nitrosurea, carmustine (BCNU; 84%) treatments resulted in lower cure rates. After treatment and cure with LEFCT-EC, 50% of the cured mice developed resistance to a tumor challenge (surgery + BCNU only 15%). Furthermore, splenocytes from cured animals protected naive animals from a tumorigenic dose of tumor cells. Separation of spleen cells into lymphocyte subpopulations indicated a major role for CD4 and CD8 T cells in this protection. FACS analysis revealed restoration of normal splenocyte subpopulation proportions impaired by cytotoxic chemotherapy. Our results suggest that LEFCT-EC can directly destroy primary tumors and facilitate the destruction of metastatic disease by enforcement of antitumor immune responses. Copyright 2005 Wiley-Liss, Inc

[Spatial distribution of sulfur dioxide around a tobacco bulk-curing workshop cluster].

PubMed

He, Fan; Wang, Mei; Wang, Tao; Sun, Jian-Feng; Huang, Wu-Xing; Tian, Bin-Qiang; Gong, Chang-Rong

2014-03-01

In order to manifest lower energy consumption and less labor employment, and provide the theoretical basis for constructing environmentally friendly modem tobacco agriculture, this paper analyzed gas composition of the chimney from a bulk-curing barn and the dispersion of sulfur dioxide (SO2) around the workshop cluster using ecom-J2KN flue gas analyzer and air sampler. During curing, the concentrations of carbon dioxide (CO2) and SO2 in the chimney were both highest at 38 degrees C, while the concentration of nitrogen oxides (NOx) was highest at 42 degrees C. The emission concentration of SO2 from the chimney was 1327.60-2218.40 mg x m(-3). Average SO2 emission would decrease by 49.7% through adding 4.0% of a sulfur-fixed agent. The highest concentrations of SO2 in the surface soil appeared at the yellowing stage. SO2 concentration in horizontal direction localized at 43-80 m exceeded 0.5 mg x m(-3). The highest concentration of SO2 (0.57 mg x m(-3)) was observed at 50 m. At 50 m in the downstream wind direction of the workshop cluster, SO2 concentration in vertical direction localized at 0.9-1.8 m exceeded 0.5 mg x m(-3), and the highest concentration of SO2 in vertical direction was 0.65 mg x m(-3) at 1.6 m. During curing, the average concentration of SO2 was decreased by 0.43 mg x m(-3) by using the sulfur-fixed agent. The polluted boundary was localized at 120 m in the downstream wind direction of the workshop cluster.

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

Towards the design of organocatalysts for nerve agents remediation: The case of the active hydrolysis of DCNP (a Tabun mimic) catalyzed by simple amine-containing derivatives.

PubMed

Barba-Bon, Andrea; Martínez-Máñez, Ramón; Sancenón, Félix; Costero, Ana M; Gil, Salvador; Pérez-Pla, Francisco; Llopis, Elisa

2015-11-15

We report herein a study of the hydrolysis of Tabun mimic DCNP in the presence of different amines, aminoalcohols and glycols as potential suitable organocatalysts for DCNP degradation. Experiments were performed in CD3CN in the presence of 5% D2O, which is a suitable solvent mixture to follow the DCNP hydrolysis. These studies allowed the definition of different DCNP depletion paths, resulting in the formation of diethylphosphoric acid, tetraethylpyrophosphate and phosphoramide species as final products. Without organocatalysts, DCNP hydrolysis occurred mainly via an autocatalysis path. Addition of tertiary amines in sub-stoichiometric amounts largely enhanced DCNP depletion whereas non-tertiary polyamines reacted even faster. Glycols induced very slight increment in the DCNP hydrolysis, whereas DCNP hydrolysis increased sharply in the presence of certain aminoalcohols especially, 2-(2-aminoethylamino)ethanol. For the latter compound, DCNP depletion occurred ca. 80-fold faster than in the absence of organocatalysts. The kinetic studies revealed that DCNP hydrolysis in the presence of 2-(2-aminoethylamino)ethanol occurred via a catalytic process, in which the aminoalcohol was involved. DCNP hydrolysis generally depended strongly on the structure of the amine, and it was found that the presence of the OHCH2CH2N moiety in the organocatalyst structure seems important to induce a fast degradation of DCNP. Copyright © 2015 Elsevier B.V. All rights reserved.

Selective Adsorption of Pb(II) from Aqueous Solution by Triethylenetetramine-Grafted Polyacrylamide/Vermiculite

PubMed Central

Gu, Shiqing; Wang, Lan; Mao, Xinyou; Yang, Liping; Wang, Chuanyi

2018-01-01

Amine groups play significant roles in polymeric composites for heavy metals removal. However, generating a composite with a large number of functional and stable amine groups based on clay is still a challenge. In this work, a new amine-functionalized adsorbent based on acid-activated vermiculite (a-Verm) was prepared by organic modification of silane coupling agent as bridge, followed by in situ polymerization of acrylamide (AM) and further grafting of triethylene tetramine (TETA). The obtained polymeric composite g-PAM/OVerm was characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), Fourier transform infrared (FTIR), thermal analysis (TG/DTG), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) analyses, confirming that amine groups were successfully grafted onto the surface of Verm. The efficacy g-PAM/OVerm for removing Pb(II) was tested. The adsorption equilibrium data on g-PAM/OVerm was in good accordance with the Langmuir adsorption isotherms, and the adsorption maximal value of Pb(II) was 219.4 mg·g−1. The adsorption kinetic data fit the pseudo-second-order kinetic model well. Additionally, g-PAM/OVerm has better selectivity for Pb(II) ion in comparison with Zn(II), Cd(II) and Cu(II) ions. The present work shows that g-PAM/OVerm holds great potential for removing Pb(II) from wastewater, and provides a new and efficient method for the removal of heavy metal ions from industrial wastewater. PMID:29597288

Methyl methacrylate as a healing agent for self-healing cementitious materials

NASA Astrophysics Data System (ADS)

Van Tittelboom, K.; Adesanya, K.; Dubruel, P.; Van Puyvelde, P.; De Belie, N.

2011-12-01

Different types of healing agents have already been tested on their efficiency for use in self-healing cementitious materials. Generally, commercial healing agents are used while their properties are adjusted for manual crack repair and not for autonomous crack healing. Consequently, the amount of regain in properties due to self-healing of cracks is limited. In this research, a methyl methacrylate (MMA)-based healing agent was developed specifically for use in self-healing cementitious materials. Various parameters were optimized including the viscosity, curing time, strength, etc. After the desired properties were obtained, the healing agent was encapsulated and screened for its self-healing efficiency. The decrease in water permeability due to autonomous crack healing using MMA as a healing agent was similar to the results obtained for manually healed cracks. First results seem promising: however, further research needs to be undertaken in order to obtain an optimal healing agent ready for use in practice.

Metal-Filled Adhesives Amenable To X-Ray Inspection

NASA Technical Reports Server (NTRS)

Hermansen, Ralph D.; Sutherland, Thomas H.; Predmore, Roamer

1994-01-01

Adhesive joints between metal parts made amenable to nondestructive radiographic inspection by incorporating radiopaque fillers that increase x-ray contrasts of joints. Adhesives can be epoxies, urethanes, acrylics, phenolics, or silicones, with appropriate curing agents and with such modifiers as polysulfides, polyamides, or butadiene rubbers.

The Management of Classical Hodgkin's Lymphoma: Past, Present, and Future.

PubMed

Richardson, S E; McNamara, C

2011-01-01

The management of classical Hodgkin's lymphoma (CHL) is a success story of modern multi-agent haemato-oncology. Prior to the middle of the twentieth century CHL was fatal in the majority of cases. Introduction of single agent radiotherapy (RT) demonstrated for the first time that these patients could be cured. Developments in chemotherapy including the mechlorethamine, vincristine, procarbazine and prednisolone (MOPP) and Adriamycin, bleomycin, vinblastine and dacarbazine (ABVD) regimens have resulted in cure rates of over 80%. Even in relapse, CHL patients can be salvaged with high dose chemotherapy and autologous haematopoietic stem cell transplantation (ASCT). Challenges remain, however, in finding new strategies to manage the small number of patients who continue to relapse or progress. In addition, the young age of many Hodgkin's patients forces difficult decisions in balancing the benefit of early disease control against the survival disadvantage of late toxicity. In this article we aim to summarise past trials, define the current standard of care and appraise future developments in the management of CHL.

Vulcanization characteristics and dynamic mechanical behavior of natural rubber reinforced with silane modified silica.

PubMed

Chonkaew, Wunpen; Minghvanish, Withawat; Kungliean, Ulchulee; Rochanawipart, Nutthaya; Brostow, Witold

2011-03-01

Two silane coupling agents were used for hydrolysis-condensation reaction modification of nanosilica surfaces. The surface characteristics were analyzed using Fourier transform infrared spectroscopy (FTIR). The vulcanization kinetics of natural rubber (NR) + silica composites was studied and compared to behavior of the neat NR using differential scanning calorimetry (DSC) in the dynamic scan mode. Dynamic mechanical analysis (DMA) was performed to evaluate the effects of the surface modification. Activation energy E(a) values for the reaction are obtained. The presence of silica, modified or otherwise, inhibits the vulcanization reaction of NR. The neat silica containing system has the lowest cure rate index and the highest activation energy for the vulcanization reaction. The coupling agent with longer chains causes more swelling and moves the glass transition temperature T(g) downwards. Below the glass transition region, silica causes a lowering of the dynamic storage modulus G', a result of hindering the cure reaction. Above the glass transition, silica-again modified or otherwise-provides the expected reinforcement effect.

[Bifunctional chelates of Rh-105, Au-199, and other metallic radionuclides as potential radiotherapeutic agents

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

Not Available

1991-12-31

Progress during this period is reported under the following headings: Diethylenetriamine based and related bifunctional chelating agents and their complexation with Rh-105, Au-198, Pd-109, cu-67, In-111, and Co-57; studies of Pd-109, Rh-105 and Tc-99m with bifunctional chelates based on phenylenediamine; establishment of an appropriate protein assay method for conjugated proteins; studies of new bifunctional Bi, Tri and tetradentate amine oxime ligands with Rh-105; IgG and antibody B72.3 conjugation studies by HPLC Techniques with bifunctional metal chelates; and progress on ligand systems for Au(III).

(Bifunctional chelates of Rh-105, Au-199, and other metallic radionuclides as potential radiotherapeutic agents)

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

Not Available

1991-01-01

Progress during this period is reported under the following headings: Diethylenetriamine based and related bifunctional chelating agents and their complexation with Rh-105, Au-198, Pd-109, cu-67, In-111, and Co-57; studies of Pd-109, Rh-105 and Tc-99m with bifunctional chelates based on phenylenediamine; establishment of an appropriate protein assay method for conjugated proteins; studies of new bifunctional Bi, Tri and tetradentate amine oxime ligands with Rh-105; IgG and antibody B72.3 conjugation studies by HPLC Techniques with bifunctional metal chelates; and progress on ligand systems for Au(III).

Anti-cancer agents based on 4-(hetero)Ary1-1,2,5-oxadiazol-3-yl Amino derivatives and a method of making

DOEpatents

Gakh, Andrei A.; Krasavin, Mikhail; Karapetian, Ruben; Rufanov, Konstantin A.; Konstantinov, Igor; Godovykh, Elena; Soldatkina, Olga; Sosnov, Andrey V.

2013-01-29

The present disclosure relates to novel compounds that can be used as anti-cancer agents in the prostate cancer therapy. ##STR00001## In particular, the invention relates N-substituted derivatives of 4-(hetero)aryl-1,2,5-oxadiazol-3-yl amines having the structural Formula (I) and (II), stereoisomers, tautomers, racemics, prodrugs, metabolites thereof, or pharmaceutically acceptable salt and/or solvate thereof. Meaning of R1 and R2 in the Formula (I) and (II) are defined in claim 1. The invention also relates to methods for preparing said compounds, and to pharmaceutical compositions comprising said compounds.

Towards an HIV cure based on targeted killing of infected cells: different approaches against acute versus chronic infection.

PubMed

Dey, Barna; Berger, Edward A

2015-05-01

Current regimens of combination antiretroviral therapy (cART) offer effective control of HIV infection, with maintenance of immune health and near-normal life expectancy. What will it take to progress beyond the status quo, whereby infectious virus can be eradicated (a 'sterilizing cure') or fully controlled without the need for ongoing cART (a 'functional cure')? On the basis of therapeutic advances in the cancer field, we propose that targeted cytotoxic therapy to kill HIV-infected cells represents a logical complement to cART for achieving an HIV cure. This concept is based on the fact that cART effectively blocks replication of the virus, but does not eliminate cells that are already infected; targeted cytotoxic therapy would contribute precisely this missing component. We suggest that different modalities are suited for curing primary acute versus established chronic infection. For acute infection, relatively short-acting potent agents such as recombinant immunotoxins might prove sufficient for HIV eradication, whereas for chronic infection, a long-lasting (lifelong?) modality is required to maintain full virus control, as might be achieved with genetically modified autologous T cells. We present perspectives for complementing cART with targeted cytotoxic therapy, whereby HIV infection is either eradicated or fully controlled, thereby eliminating the need for lifelong cART.

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.

Low electric field enhanced chemotherapy can cure mice with CT-26 colon carcinoma and induce anti-tumour immunity

PubMed Central

PLOTNIKOV, A; FISHMAN, D; TICHLER, T; KORENSTEIN, R; KEISARI, Y

2004-01-01

Low electric field cancer treatment − enhanced chemotherapy (LEFCT-EC) is a new anticancer treatment which utilizes a combination of chemotherapeutic agents and a low electric field. We investigated the antitumour effectiveness of this technique in a model of murine colon carcinoma (CT-26). The low electric field was applied to ∼65 mm3 intracutaneous tumours after intratumoral injection of 5FU, bleomycin or BCNU. We observed significant tumour size reduction and a prolongation of survival time. The complete cure of a significant fraction of animals treated by LEFCT-EC with 5FU (33%), bleomycin (51%) or BCNU (83%) was observed. Mice cured by LEFCT-EC developed resistance to a tumour challenge and their splenocytes had antitumour activity in vivo. Our results suggest that LEFCT-EC is an effective method for treatment of solid tumours. PMID:15544616

Low electric field enhanced chemotherapy can cure mice with CT-26 colon carcinoma and induce anti-tumour immunity.

PubMed

Plotnikov, A; Fishman, D; Tichler, T; Korenstein, R; Keisari, Y

2004-12-01

Low electric field cancer treatment-enhanced chemotherapy (LEFCT-EC) is a new anticancer treatment which utilizes a combination of chemotherapeutic agents and a low electric field. We investigated the antitumour effectiveness of this technique in a model of murine colon carcinoma (CT-26). The low electric field was applied to approximately 65 mm3 intracutaneous tumours after intratumoral injection of 5FU, bleomycin or BCNU. We observed significant tumour size reduction and a prolongation of survival time. The complete cure of a significant fraction of animals treated by LEFCT-EC with 5FU (33%), bleomycin (51%) or BCNU (83%) was observed. Mice cured by LEFCT-EC developed resistance to a tumour challenge and their splenocytes had antitumour activity in vivo. Our results suggest that LEFCT-EC is an effective method for treatment of solid tumours.

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. Copyright © 2011 Elsevier Ltd. All rights reserved.

Epoxy resin synthesis using low molecular weight lignin separated from various lignocellulosic materials.

PubMed

Asada, Chikako; Basnet, Sunita; Otsuka, Masaya; Sasaki, Chizuru; Nakamura, Yoshitoshi

2015-03-01

A low molecular weight lignin from various lignocellulosic materials was used for the synthesis of bio-based epoxy resins. The lignin extracted with methanol from steam-exploded samples (steaming time of 5 min at steam pressure of 3.5 MPa) from different biomasses (i.e., cedar, eucalyptus, and bamboo) were functionalized by the reaction with epichlorohydrin, catalyzed by a water-soluble phase transfer catalyst tetramethylammonium chloride, which was further reacted with 30 wt% aqueous NaOH for ring closure using methyl ethyl ketone as a solvent. The glycidylated products of the lignin with good yields were cured to epoxy polymer networks with bio-based curing agents i.e., lignin itself and a commercial curing agent TD2131. Relatively good thermal properties of the bio-based epoxy network was obtained and thermal decomposition temperature at 5% weight loss (Td5) of cedar-derived epoxy resin was higher than that derived from eucalyptus and bamboo. The bio-based resin satisfies the stability requirement of epoxy resin applicable for electric circuit boards. The methanol-insoluble residues were enzymatically hydrolyzed to produce glucose. This study indicated that the biomass-derived methanol-soluble lignin may be a promising candidate to be used as a substitute for petroleum-based epoxy resin derived from bisphenol A, while insoluble residues may be processed to give a bioethanol precursor i.e., glucose. Copyright © 2015 Elsevier B.V. All rights reserved.

Modeling HCV cure after an ultra-short duration of therapy with direct acting agents

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

Goyal, Ashish; Lurie, Yoav; Meissner, Eric G.

In cases of sustained-virological response (SVR or cure) after an ultra-short duration (≤ 27 days) of direct-acting antiviral (DAA)-based therapy, despite HCV being detected at end of treatment (EOT), have been reported. Established HCV mathematical models that predict the treatment duration required to achieve cure do not take into account the possibility that the infectivity of virus produced during treatment might be reduced. The aim of this study was to develop a new mathematical model that considers the fundamental and critical concept that HCV RNA in serum represents both infectious virus (V i) and non-infectious virus (V ni) in ordermore » to explain the observation of cure with ultrashort DAA therapy. Established HCV models were compared to the new mathematical model to retrospectively explain cure in 2 patients who achieved cure after 24 or 27 days of paritaprevir, ombitasvir, dasabuvir, ritonavir and ribavirin or sofosbuvir plus ribavirin, respectively. Fitting established models with measured longitudinal HCV viral loads indicated that in both cases, cure would not have been expected without an additional 3–6 weeks of therapy after the actual EOT. In contrast, the new model fits the observed outcome by considering that in addition to blocking V i and V ni production (ε~0.998), these DAA + ribavirin treatments further enhanced the ratio of V ni to V i, thus increasing the log (V ni/V i) from 1 at pretreatment to 6 by EOT, which led to <1 infectious-virus particle in the extracellular body fluid (i.e., cure) prior to EOT. This new model can explain cure after short duration of DAA + ribavirin therapy by suggesting that a minimum 6-fold increase of log (V ni/V i) results from drug-induced enhancement of the V ni/V i.« less

Modeling HCV cure after an ultra-short duration of therapy with direct acting agents

DOE PAGES

Goyal, Ashish; Lurie, Yoav; Meissner, Eric G.; ...

2017-06-30

In cases of sustained-virological response (SVR or cure) after an ultra-short duration (≤ 27 days) of direct-acting antiviral (DAA)-based therapy, despite HCV being detected at end of treatment (EOT), have been reported. Established HCV mathematical models that predict the treatment duration required to achieve cure do not take into account the possibility that the infectivity of virus produced during treatment might be reduced. The aim of this study was to develop a new mathematical model that considers the fundamental and critical concept that HCV RNA in serum represents both infectious virus (V i) and non-infectious virus (V ni) in ordermore » to explain the observation of cure with ultrashort DAA therapy. Established HCV models were compared to the new mathematical model to retrospectively explain cure in 2 patients who achieved cure after 24 or 27 days of paritaprevir, ombitasvir, dasabuvir, ritonavir and ribavirin or sofosbuvir plus ribavirin, respectively. Fitting established models with measured longitudinal HCV viral loads indicated that in both cases, cure would not have been expected without an additional 3–6 weeks of therapy after the actual EOT. In contrast, the new model fits the observed outcome by considering that in addition to blocking V i and V ni production (ε~0.998), these DAA + ribavirin treatments further enhanced the ratio of V ni to V i, thus increasing the log (V ni/V i) from 1 at pretreatment to 6 by EOT, which led to <1 infectious-virus particle in the extracellular body fluid (i.e., cure) prior to EOT. This new model can explain cure after short duration of DAA + ribavirin therapy by suggesting that a minimum 6-fold increase of log (V ni/V i) results from drug-induced enhancement of the V ni/V i.« less

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

Morphology and viscoelastic properties of sealing materials based on EPDM rubber.

PubMed

Milić, J; Aroguz, A; Budinski-Simendić, J; Radicević, R; Prendzov, S

2008-12-01

In this applicative study, the ratio of active and inactive filler loadings was the prime factor for determining the dynamic-mechanical behaviour of ethylene-propylene-diene monomer rubbers. Scanning electron microscopy was used to study the structure of reinforced dense and microcellular elastomeric materials. The effects of filler and blowing agent content on the morphology of composites were investigated. Microcellular samples cured in salt bath show smaller cells and uniform cell size compared with samples cured in hot air. Dynamic-mechanical thermal analysis showed appreciable changes in the viscoelastic properties by increasing active filler content, which could enable tailoring the material properties to suit sealing applications.

Sclerotherapy of hydroceles with polidocanol.

PubMed

Fuse, H; Sakamoto, M; Fujishiro, Y; Katayama, T

1994-01-01

Fifteen patients with hydroceles of the testis or spermatic cord were treated by aspiration and injection of the sclerosant solution polidocanol. The cure rate of hydroceles after one sclerotherapy session was 73%, and the overall cure rate using the procedure was 87%. No patient experienced pain during or after the procedure, which was conducted without anaesthesia. No complications were observed. It is concluded that sclerotherapy of hydroceles with polidocanol may be a useful alternative to open operation, due to its ease of administration, low frequency of complications, and high rate of effectiveness, and that this agent is preferable to certain other drugs in that it causes no pain during or after the injection.

Finding new cures for neurological disorders: a possible fringe benefit of biodefense research?

PubMed

Jett, David A

2010-03-17

The National Institutes of Health (NIH) supports research about and the development of better therapies for treating exposure to toxic chemicals that could be used in a terrorist attack or released during an industrial accident. A review of recent research published by NIH investigators working in this field indicates that scientific advances in this area also have implications for reducing the burden of other neurological diseases and disorders. Some key examples discussed include studies on the development of therapeutic drugs to treat seizures and the neuropathology caused by chemical nerve agents, which may help find better cures for epilepsy, stroke, and neurodegenerative diseases.

In vitro and in vivo impact of silica nanoparticle design on biocompatibility

NASA Astrophysics Data System (ADS)

Yu, Tian

Silica nanoparticles (SiO2) have utility in a wide range of applications, such as biologic delivery platforms, imaging and diagnostic agents, and targeted therapeutic carriers. Recent improvements in regulating the geometry, porosity, and surface characteristics of SiO2 have further facilitated their biomedical applications. Concerns however remain about the toxic effects of SiO2 upon exposure to biological systems. The impacts of geometry, porosity, and surface characteristics of SiO 2 on cellular toxicity and hemolytic activity were explored. It was shown that surface characteristics and porosity govern cellular toxicity. The cellular association of SiO2 increased in the following order: mesoporous SiO2 (aspect ratio 1, 2, 4, 8) < amine-modified mesoporous SiO2 (aspect ratio 1, 2, 4, 8) < amine-modified nonporous Stober SiO2 < nonporous Stober SiO2. Geometry did not seem to influence the extent of SiO2 cellular association. Hemolysis assay showed that the hemolytic activity was porosity- and geometry-dependent for pristine SiO2 and surface charge-dependent for amine-modified SiO2. The acute toxicity, biodistribution, and pharmacokinetics of SiO 2 of systematically varied geometry, porosity, and surface characteristics were evaluated in immune-competent mice when administered intravenously. Results suggest that in vivo toxicity, biodistribution and pharmacokinetics of SiO2 were mainly influenced by nanoparticle porosity and surface characteristics. The maximum tolerated dose (MTD) increased in the following order: Mesoporous SiO2 (aspect ratio 1, 2, 8) at 30 -- 65 mg/kg < amine-modified mesoporous SiO2 (aspect ratio 1, 2, 8) at 100 -- 150 mg/kg < unmodified or amine-modified nonporous SiO2 at 450 mg/kg. The adverse reactions above MTDs were primarily caused by the mechanical obstruction of SiO2 in the vasculature that led to congestion in multiple vital organs and subsequent organ failure. The nanoparticles were taken up extensively by the liver and spleen. Mesoporous SiO2 exhibited higher accumulation in the lung than nonporous SiO 2 of similar size. This accumulation was reduced by primary amine modification. Increasing the aspect ratio of amine-modified mesoporous SiO2 from 1 to 8 resulted in increased accumulation in the lung. These studies provide critical guidelines in rational design of SiO 2 for nanomedicine applications.

On-bead combinatorial synthesis and imaging of chemical exchange saturation transfer magnetic resonance imaging agents to identify factors that influence water exchange.

PubMed

Napolitano, Roberta; Soesbe, Todd C; De León-Rodríguez, Luis M; Sherry, A Dean; Udugamasooriya, D Gomika

2011-08-24

The sensitivity of magnetic resonance imaging (MRI) contrast agents is highly dependent on the rate of water exchange between the inner sphere of a paramagnetic ion and bulk water. Normally, identifying a paramagnetic complex that has optimal water exchange kinetics is done by synthesizing and testing one compound at a time. We report here a rapid, economical on-bead combinatorial synthesis of a library of imaging agents. Eighty different 1,4,7,10-tetraazacyclododecan-1,4,7,10-tetraacetic acid (DOTA)-tetraamide peptoid derivatives were prepared on beads using a variety of charged, uncharged but polar, hydrophobic, and variably sized primary amines. A single chemical exchange saturation transfer image of the on-bead library easily distinguished those compounds having the most favorable water exchange kinetics. This combinatorial approach will allow rapid screening of libraries of imaging agents to identify the chemical characteristics of a ligand that yield the most sensitive imaging agents. This technique could be automated and readily adapted to other types of MRI or magnetic resonance/positron emission tomography agents as well.

A review of Explosives Used in Explosive Excavation Research Laboratory Projects Since 1969

DTIC Science & Technology

1974-12-01

Boron compounds Potassium dichramat« Antimony compounds Bismuth compounds P«riodat«s Litharge Guar gum (polysaccSarid«) Storch Acrylomid... gum , and gelled with a cross- linking agent. The i-arliest slurries used Government surplus TNT as a fuel-sensitizer, but the majority o...Nonexplosive TNT PETN RDX Rentalite Composition B Guanidine nitrate Smokeless powder Nitres*: ch Alky’amine nitrates Nit.omannite Aluminum Sugar

Biofluidic Intelligent Processors for Preparative Manipulations of Biological Warfare Agents at the Attomole Level

DTIC Science & Technology

2005-11-01

micromixing and microreactor concept. OPA by itself is non- fluorescent, but it reacts with primary amine groups in the presence of β-mercaptoethanol to form...hybrid microchannel/nanopore-membrane devices can serve as efficient micromixers and microreactors, and (2) microscopic kinetics can be obtained from...single image measurements. An immediate application which extended from the micromixing and microreactor concept was microsensing. Calcium ions

Fire Safety Aspects of Polymeric Materials. Volume 10. Mines and Bunkers

DTIC Science & Technology

1980-01-01

Formaldehyde and Melamine / Formaldehyde Resins The basic chemistry, properties, and applications of urea / formaldehyde and melamine / formaldehyde resins ... Formaldehyde and Melamine Formaldehyde Rosins 71 4.2.3.3 Unsaturated Polyester Resins 71 4.2.3.4 Epoxy Resins 72 4.2.3.5 Furan Resins 72 4.2.3.6 Amine...aldehyde — most frequently formaldehyde . Urea is often used as a modifying agent. The

Study of Reactive Materials for Development of new Protective Clothing Concepts

DTIC Science & Technology

1977-10-01

G, and V agents and must not unduly change the fabric permeability. Microencapsulation , the technique of encasing extremely small droplets or...preparing and evaluating decontaminating microcapsules that contain strong-base alkali- metal hydroxides, s-Im-bis(N,chloro-2,4,6-trichlorophenyl) urea...and various amines as the core phase. We are now identifying and developing microcapsule wall materials that will be stable to the highly basic core

Polymer Claw: Instant Underwater Adhesive

DTIC Science & Technology

2012-08-27

technology is the use of pressure sensitive microcapsules , which release reactive amine crosslinkers into an adhesive putty when pressed against the surface...CLEANING AGENT RHEOLOGY 3 3.3 PRESSURE-ACTIVATED ADHESIVE 5 3.3.1 PROCESSING IMPROVEMENTS 5 3.3.2 MICROCAPSULE DIAMETER 5 3.3.3 MICROCAPSULE /RESIN...to attain a reasonable shelf life (- l wk.). The microcapsule diameter has been halved in order to improve mixing in the pressure-activated

Enantioselective Decarboxylative Arylation of α-Amino Acids via the Merger of Photoredox and Nickel Catalysis

PubMed Central

Zuo, Zhiwei; Cong, Huan; Li, Wei; Choi, Junwon; Fu, Gregory C.; MacMillan, David W. C.

2016-01-01

An asymmetric decarboxylative Csp3–Csp2 cross-coupling has been achieved via the synergistic merger of photoredox and nickel catalysis. This mild, operationally simple protocol transforms a wide variety of naturally abundant α-amino acids and readily available aryl halides into valuable chiral benzylic amines in high enantiomeric excess, thereby producing motifs found in pharmacologically active agents. PMID:26849354

Chemical Warfare Agent Decontamination Foaming Composition and Method

DTIC Science & Technology

2000-03-22

Drumgoole et al. The Drumgoole patent discloses an inflatable, portable apparatus having an aqueous foam for substantially mitigating the 15 effects...by weight to about 25% by weight. Exemplary 10 foaming components include AFFF manufactured by 3M of St. Paul, Minnesota, Knockdown manufactured...amines, amino alcohols and polyamines. For example, when the foam is water-based, the corrosion inhibitor also may be used as a solvent, as described

Process for the preparation of organoclays

DOEpatents

Chaiko, David J.

2004-11-23

A method for preparing organoclays for use as rheological control agents and in the preparation of nanocomposites. Typically, the clay is dispersed in water, and a specific amount of polymeric hydrotrope, ranging from 0.1 to 15 weight percent relative to the weight of the clay, is adsorbed onto the clay surface. Quaternary amine exchange is also performed on the clay to modify the surface hydrophilic/lipophilic balance (HLB) of the clay.

On-matrix Derivatization for Dynamic Headspace Sampling of Nonvolatile Surface Residues

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

Harvey, Scott D.; Wahl, Jon H.

2012-09-01

The goal of this study is to extend sampling by the field and laboratory emission cell (FLEC) purge-and-trap technique to applications that target nonvolatile residues. On-matrix derivatization of residues to render analytes stable and more volatile is explored to achieve this goal. Results show that on-matrix derivatizations of nerve agent hydrolysis products (monoalkyl methylphosphonic acids and methylphosphonic acid [MPA]) with diazomethane were successful on glass and painted wallboard (at the 10-µg level). It also was successful on the more difficult concrete (at the 500-µg level) and carpet (at the 20-µg level) substrates that cannot be successfully sampled using swipe techniques.more » Analysis of additional chemical warfare (CW)-associated residues can be approached by on-matrix derivatization with trifluoroacetic anhydride (TFAA). For example, amines (used as stabilizers or present as decomposition products of the nerve agent VX) or thiodiglycol (hydrolysis product of sulfur mustard) could be sampled as their TFAA derivatives from glass, painted wallboard, and concrete (at the 40-µg level), as well as carpet (at the 80-µg level) surfaces. Although the amine and thiodiglycol are semi-volatile and could be sampled directly, derivatization improves the recovery and chromatographic behavior of these analytes.« less

On-matrix derivatization for dynamic headspace sampling of nonvolatile surface residues.

PubMed

Harvey, Scott D; Wahl, Jon H

2012-09-21

The goal of this study is to extend sampling by the field and laboratory emission cell (FLEC) dynamic headspace technique to applications that target nonvolatile residues. On-matrix derivatization of residues to render analytes stable and more volatile is explored to achieve this goal. Results show that on-matrix derivatizations of nerve agent hydrolysis products (monoalkyl methylphosphonic acids and methylphosphonic acid [MPA]) with diazomethane were successful on glass and painted wallboard (at the 10-μg level). It also was successful on the more difficult concrete (at the 500-μg level) and carpet (at the 20-μg level), substrates that cannot be successfully sampled using swipe techniques. Analysis of additional chemical warfare (CW)-associated residues can be approached by on-matrix derivatization with trifluoroacetic anhydride (TFAA). For example, amines (used as stabilizers or present as decomposition products of the nerve agent VX) or thiodiglycol (hydrolysis product of sulfur mustard) could be sampled as their TFAA derivatives from glass, painted wallboard, and concrete (at the 40-μg level), as well as carpet (at the 80-μg level) surfaces. Although the amine and thiodiglycol are semi-volatile and could be sampled directly, derivatization improves the recovery and chromatographic behavior of these analytes. Copyright © 2012 Elsevier B.V. All rights reserved.

C 3-symmetric opioid scaffolds are pH-responsive DNA condensation agents.

PubMed

McStay, Natasha; Molphy, Zara; Coughlan, Alan; Cafolla, Attilio; McKee, Vickie; Gathergood, Nicholas; Kellett, Andrew

2017-01-25

Herein we report the synthesis of tripodal C 3 -symmetric opioid scaffolds as high-affinity condensation agents of duplex DNA. Condensation was achieved on both supercoiled and canonical B-DNA structures and identified by agarose electrophoresis, viscosity, turbidity and atomic force microscopy (AFM) measurements. Structurally, the requirement of a tris-opioid scaffold for condensation is demonstrated as both di- (C 2 -symmetric) and mono-substituted (C 1 -symmetric) mesitylene-linked opioid derivatives poorly coordinate dsDNA. Condensation, observed by toroidal and globule AFM aggregation, arises from surface-binding ionic interactions between protonated, cationic, tertiary amine groups on the opioid skeleton and the phosphate nucleic acid backbone. Indeed, by converting the 6-hydroxyl group of C 3 -morphine ( MC3: ) to methoxy substituents in C 3 -heterocodeine ( HC3: ) and C 3 -oripavine ( OC3: ) molecules, dsDNA compaction is retained thus negating the possibility of phosphate-hydroxyl surface-binding. Tripodal opioid condensation was identified as pH dependent and strongly influenced by ionic strength with further evidence of cationic amine-phosphate backbone coordination arising from thermal melting analysis and circular dichroism spectroscopy, with compaction also witnessed on synthetic dsDNA co-polymers poly[d(A-T) 2 ] and poly[d(G-C) 2 ]. On-chip microfluidic analysis of DNA condensed by C 3 -agents provided concentration-dependent protection (inhibition) to site-selective excision by type II restriction enzymes: BamHI, HindIII, SalI and EcoRI, but not to the endonuclease DNase I. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

Probing the effect of charge transfer enhancement in off resonance mode SERS via conjugation of the probe dye between silver nanoparticles and metal substrates.

PubMed

Selvakannan, Pr; Ramanathan, Rajesh; Plowman, Blake J; Sabri, Ylias M; Daima, Hemant K; O'Mullane, Anthony P; Bansal, Vipul; Bhargava, Suresh K

2013-08-21

The charge transfer-mediated surface enhanced Raman scattering (SERS) of crystal violet (CV) molecules that were chemically conjugated between partially polarized silver nanoparticles and optically smooth gold and silver substrates has been studied under off-resonant conditions. Tyrosine molecules were used as a reducing agent to convert silver ions into silver nanoparticles where oxidised tyrosine caps the silver nanoparticle surface with its semiquinone group. This binding through the quinone group facilitates charge transfer and results in partially oxidised silver. This establishes a chemical link between the silver nanoparticles and the CV molecules, where the positively charged central carbon of CV molecules can bind to the terminal carboxylate anion of the oxidised tyrosine molecules. After drop casting Ag nanoparticles bound with CV molecules it was found that the free terminal amine groups tend to bind with the underlying substrates. Significantly, only those CV molecules that were chemically conjugated between the partially polarised silver nanoparticles and the underlying gold or silver substrates were found to show SERS under off-resonant conditions. The importance of partial charge transfer at the nanoparticle/capping agent interface and the resultant conjugation of CV molecules to off resonant SERS effects was confirmed by using gold nanoparticles prepared in a similar manner. In this case the capping agent binds to the nanoparticle through the amine group which does not facilitate charge transfer from the gold nanoparticle and under these conditions SERS enhancement in the sandwich configuration was not observed.

Psychopharmacology of Autism Spectrum Disorders: A Selective Review

ERIC Educational Resources Information Center

Mohiuddin, Sarah; Ghaziuddin, Mohammad

2013-01-01

While there is no cure for autism spectrum disorder, psychopharmacologic agents are often used with behavioral and educational approaches to treat its comorbid symptoms of hyperactivity, irritability, and aggression. Studies suggest that at least 50% of persons with autism spectrum disorder receive psychotropic medications during their life span.…

Evaluation of Flexural Strength of Polymethyl Methacrylate modified with Silver Colloidal Nanoparticles subjected to Two Different Curing Cycles: An in vitro Study.

PubMed

Munikamaiah, Ranganath L; Jain, Saket K; Pal, Kapil S; Gaikwad, Ajay

2018-03-01

Silver colloidal nanoparticles have been incorporated into acrylic resins to induce antimicrobial properties. However, as additives, they can influence the mechanical properties of the final product. Mechanical properties are also dependent on different curing cycles. The aim of this study was to evaluate flexural strength of a denture base resin incorporated with different concentrations of silver colloidal nanoparticles subjected to two different curing cycles. Lucitone 199 denture base resin was used into which silver colloidal nanoparticles were incorporated at 0.5 and 5% by polymer mass. Specimens devoid of nanoparticles were used as controls. A total of 60 specimens were fabricated and divided into two groups. Each group was divided into three subgroups consisting of 10 specimens each. The specimens were fabricated according to American Dental Association (ADA) specification No. 12 and tested for flexural strength using universal testing machine. Silver colloidal nanoparticle incorporation at 0.5% concentration increased the mean flexural strength in both curing cycles by 7.5 and 4.4%, respectively, when compared with the control group. The study suggested that the mean flexural strength value of 0.5% silver colloidal nanoparticles in denture base resin was above the value of the control group both in short and long curing cycles, which makes it clinically suitable as a denture base material. However, at 5% concentration, the statistically significant amount of decrease in flexural strength compared with the value of control group both in short and long curing cycles gives it a questionable prognosis. The specimens incorporated with the antimicrobial agent 0.5% silver colloidal nanoparticles and processed by long curing cycles showed significant increase in its flexural strength compared with the control group, which makes it clinically suitable as a denture base material.

Design of Fucoidan Functionalized - Iron Oxide Nanoparticles for Biomedical Applications.

PubMed

Tran, Khanh Nghia; Tran, Phuong Ha-Lien; Vo, Toi Van; Tran, Thao Truong-Dinh

2016-01-01

This research aims to develop an iron oxide nanoparticle drug delivery system utilizing a recent material discovered from ocean, fucoidan. The material has drawn much interest due to many biomedical functions that have been proven for human health. One interesting point herein is that fucoidan is not only a sulfated polysaccharide, a polymer for stabilization of iron oxide nanoparticles, but plays a role of an anticancer agent also. Various approaches were investigated to optimize the high loading efficiency and explain the mechanism of nanoparticle formations. Fucoidan was functionalized on iron oxide nanoparticles by a direct coating or via amine groups. Also, a hydrophobic part of oleic acid was conjugated to the amine groups for a more favorable loading of poorly water-soluble anticancer drugs. This study proposed a novel system and an efficient method to functionalize fucoidan on iron oxide nanoparticle systems which will lead to a facilitation of a double strength treatment of cancer.

In Vitro Anti-Toxoplasma gondii and Antimicrobial Activity of Amides Derived from Cinnamic Acid.

PubMed

Silveira, Graziela Rangel; Campelo, Karoline Azerêdo; Lima, Gleice Rangel Silveira; Carvalho, Lais Pessanha; Samarão, Solange Silva; Vieira-da-Motta, Olney; Mathias, Leda; Matos, Carlos Roberto Ribeiro; Vieira, Ivo José Curcino; Melo, Edesio José Tenório de; Maria, Edmilson José

2018-03-28

Most cinnamic acids, their esters, amides, aldehydes, and alcohols present several therapeutic actions through anti-inflammatory, antitumor, and inhibitory activity against a great variety of microorganisms. In this work, eight amines derived from cinnamic acid were synthesized and tested against host cells infected with Toxoplasma gondii and the bacteria Escherichia coli, Pseudomonas aeruginosa, Staphylococcus epidermidis, and three strains of Staphylococcus aureus . Compounds 3 and 4 showed the best result against intracellular T. gondii , presenting antiparasitic activity at low concentrations (0.38 and 0.77 mM). The antibacterial activity of these compounds was also evaluated by the agar microdilution method, and amides 2 and 5 had a minimum inhibitory concentration of 250 µg mL -1 against two strains of S. aureus (ATCC 25923 and bovine strain LSA 88). These also showed synergistic action along with a variety of antibiotics, demonstrating that amines derived from cinnamic acid have potential as pharmacological agents.

Synthesis of Photocrosslinkable and Amine Containing Multifunctional Nanoparticles via Polymerization-Induced Self-Assembly.

PubMed

Huang, Jianbing; Li, Decai; Liang, Hui; Lu, Jiang

2017-08-01

Photo-crosslinkable and amine-containing block copolymer nanoparticles are synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization-induced self-assembly of a multifunctional core-forming monomer, 2-((3-(4-(diethylamino)phenyl)acryloyl)oxy)ethyl methacrylate (DEMA), using poly(2-hydroxypropyl methacrylate) macromolecular chain transfer agent as a steric stabilizer in methanol at 65 °C. By tuning the chain length of PDEMA, a range of nanoparticle morphologies (sphere, worm, and vesicle) can be obtained. Since cinnamate groups can easily undergo a [2 + 2] cycloaddition of the carbon-carbon double bonds upon UV irradiation, the as-prepared block copolymer nanoparticles are readily stabilized by photo-crosslinking to produce anisotropic nanoparticles. The crosslinked block copolymer nanoparticles can be used as templates for in situ formation polymer/gold hybrid nanoparticles. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

1H NMR analysis of complexation of hydrotropic agents nicotinamide and caffeine with aromatic biologically active molecules in aqueous solution

NASA Astrophysics Data System (ADS)

Lantushenko, Anastasia O.; Mukhina, Yulia V.; Veselkov, Kyrill A.; Davies, David B.; Veselkov, Alexei N.

2004-07-01

NMR spectroscopy has been used to elucidate the molecular mechanism of solubilization action of hydrotropic agents nicotinamide (NA) and caffeine (CAF). Hetero-association of NA with riboflavine-mononucleotide (FMN) and CAF with low soluble in aqueous solution synthetic analogue of antibiotic actinomycin D, actinocyl-bis-(3-dimethylaminopropyl) amine (Actill), has been investigated by 500 MHz 1H NMR spectroscopy. Concentration and temperature dependences of proton chemical shifts have been analysed in terms of a statistical-thermodynamic model of indefinite self- and heteroassociation of aromatic molecules. The obtained results enable to conclude that NA-FMN and CAF-Actill intermolecular complexes are mainly stabilized by the stacking interactions of the aromatic chromophores. Hetero-association of the investigated molecules plays an important role in solubilization of aromatic drugs by hydrotropic agents nicotinamide and caffeine.

Development of tough, moisture resistant laminating resins

NASA Technical Reports Server (NTRS)

Brand, R. A.; Harrison, E. S.

1982-01-01

Tough, moisture resistant laminating resins for employment with graphite fibers were developed. The new laminating resins exhibited cost, handleability and processing characteristics equivalent to 394K (250 F) curing epoxies. The laminating resins were based on bisphenol A dicyanate and monofunctional cyanates with hydrophobic substituents. These resins sorb only small quantities of moisture at equilibrium (0.5% or less) with minimal glass transition temperature depression and represent an improvement over epoxies which sorb around 2% moisture at equilibrium. Toughening was accomplished by the precipitation of small diameter particles of butadiene nitrile rubber throughout the resin matrix. The rubber domains act as microcrack termini and energy dissipation sites, allowing increased stress accommodation prior to catastrophic failure. A unique blend of amine terminated butadiene nitrile elastomer (MW 2,000) and a high nitrile content butadiene nitrile rubber yielded the desired resin morphology.

Oxygen plasma resistant phosphine oxide containing imide/arylene copolymers

NASA Technical Reports Server (NTRS)

Jensen, Brian J.

1993-01-01

A series of oxygen plasma resistant imide/arylene ether copolymers were prepared by reacting anhydride-terminated poly(amide acids) and amine-terminated polyarylene ethers containing phosphine oxide units. Inherent viscosities for these copolymers ranged from 0.42 to 0.80 dL/g. After curing, the resulting copolymers had glass transition temperatures ranging from 224 C to 228 C. Solution cast films of the block copolymers were tough and flexible with tensile strength, tensile moduli, and elongation at break up to 16.1 ksi, 439 ksi, and 23 percent, respectively at 25 C and 9.1 ksi, 308 ksi and 97 percent, respectively at 150 C. The copolymers show a significant improvement in resistance to oxygen plasma when compared to the commercial polyimide Kapton. The imide/arylene ether copolymers containing phosphine oxide units are suitable as coatings, films, adhesives, and composite matrices.

[Therapeutic regimens for treating bacterial vaginosis in pregnant women].

PubMed

Borisov, I; Dimitrova, V; Mazneĭkova, V; Shopova, E

1999-01-01

The study comprises 128 pregnant women examined at different gestational weeks. The diagnosis of bacterial vaginosis was made using: a) the complex clinical criteria--vaginal discharge, vaginal pH, amine test and "clue cells" b) Nugent scoring system c) Spiegel criteria. Two therapeutic regimens were compared--intravaginal 2% clindamycin creme (Dalacin V) 5 g three consecutive days and intravaginal metronidazole (Flagyl) 500 mg once daily for 5 consecutive days. Control examination was carried out 5-7 days after completion of therapy using the same protocol. 28 women from the first group and 31 women from the second group had the control examination. Bacterial vaginosis was eradicated in 93% of women using intravaginal clindamycin and in 87% of women using intravaginal metronidazole. Both regimes were more effective compared to treatment with oral ampicillin for 7 days, where the cure rate was 62%.

Critical role of surfactants in the formation of digestively-ripened, ultra-small (r<2 nm) copper oxide quantum dots

NASA Astrophysics Data System (ADS)

Talluri, Bhusankar; Prasad, Edamana; Thomas, Tiju

2018-04-01

Synthesis of ultra-small (r < 2 nm) and monodispersed semiconductor quantum dots (QDs) have gained considerable attention due to their wide range of applications, ranging from photovoltaics to sensing. Digestive ripening (DR), a method for preparing uniformly-sized particles is critically influenced by nature and concentrations of the starting materials, solvent, and surfactant. To better understand the DR process there is a need to study the effect of each synthetic parameter. In this work, we investigate the effect of surfactant on a ceramic-DR process, with copper oxide as the chosen material. To study the influence of surfactant; aminoalcohols (triethanolamine, diethanolamine, monoethanolamine), alkylamines (ethyl amine) and aqua ligands are chosen. Digestively ripened quantum dots (QDs) are formed in case of all surfactants except ethyl amine and water. Aminoalchols based surfactants which contain both hydroxyl and amine moieties are efficient ligands (due to their chelation ability) for achieving DR. With the increase of denticity of the ligand, average size of QDs do not vary; however the variance in size does. QDs formed using aminoalchols are more monodispersed when compared to alkyl amine and aqua ligand systems. Furthermore, absorption and photoluminescence spectra suggest that choice of surfactant is important for achieving DR in ceramic nanostructures (when compared to other parameters). Hard-soft-acid-base-interactions between surfactant and copper oxide seem primarily responsible for the observed DR in copper oxide QDs. The absorption and photoluminescence spectra indicate that the energy migration and relaxation pathways taking place in DR QDs depend on the type of capping agent used.

Design, synthesis and screening studies of potent thiazol-2-amine derivatives as fibroblast growth factor receptor 1 inhibitors.

PubMed

Kumar, B V S Suneel; Lakshmi, Narasu; Kumar, M Ravi; Rambabu, Gundla; Manjashetty, Thimmappa H; Arunasree, Kalle M; Sriram, Dharmarajan; Ramkumar, Kavya; Neamati, Nouri; Dayam, Raveendra; Sarma, J A R P

2014-01-01

Fibroblast growth factor receptor 1 (FGFR1) a tyrosine kinase receptor, plays important roles in angiogenesis, embryonic development, cell proliferation, cell differentiation, and wound healing. The FGFR isoforms and their receptors (FGFRs) considered as a potential targets and under intense research to design potential anticancer agents. Fibroblast growth factors (FGF's) and its growth factor receptors (FGFR) plays vital role in one of the critical pathway in monitoring angiogenesis. In the current study, quantitative pharmacophore models were generated and validated using known FGFR1 inhibitors. The pharmacophore models were generated using a set of 28 compounds (training). The top pharmacophore model was selected and validated using a set of 126 compounds (test set) and also using external validation. The validated pharmacophore was considered as a virtual screening query to screen a database of 400,000 virtual molecules and pharmacophore model retrieved 2800 hits. The retrieved hits were subsequently filtered based on the fit value. The selected hits were subjected for docking studies to observe the binding modes of the retrieved hits and also to reduce the false positives. One of the potential hits (thiazole-2-amine derivative) was selected based the pharmacophore fit value, dock score, and synthetic feasibility. A few analogues of the thiazole-2-amine derivative were synthesized. These compounds were screened for FGFR1 activity and anti-proliferative studies. The top active compound showed 56.87% inhibition of FGFR1 activity at 50 µM and also showed good cellular activity. Further optimization of thiazole-2-amine derivatives is in progress.

Solvent-based self-healing approaches for fiber-reinforced composites

NASA Astrophysics Data System (ADS)

Jones, Amanda R.

Damage in composite materials spans many length scales and is often difficult to detect or costly to repair. The incorporation of self-healing functionality in composite materials has the potential to greatly extend material lifetime and reliability. Although there has been remarkable progress in self-healing polymers over the past decade, self-repair in fiber-reinforced composite materials presents significant technical challenges due to stringent manufacturing and performance requirements. For high performance, fiber-reinforced composites, the self-healing components need to survive high temperature processing, reside in matrix interstitial regions to retain a high fiber volume fraction, and have minimal impact on the mechanical properties of the host material. This dissertation explores several microencapsulated solvent-based self-healing approaches for fiber-reinforced composites at the fiber/ matrix interface size scale as well as matrix cracking. Systems are initially developed for room temperature cured epoxies/ glass fiber interfaces and successfully transitioned to carbon fibers and high temperature-cured, thermoplastic-toughened matrices. Full recovery of interfacial bond strength after complete fiber/matrix debonding is achieved with a microencapsulated solvent-based healing chemistry. The surface of a glass fiber is functionalized with microcapsules containing varying concentrations of reactive epoxy resin and ethyl phenyl acetate (EPA) solvent. Microbond specimens consisting of a single fiber and a microdroplet of epoxy are cured at 35°C, tested, and the interfacial shear strengths (IFSS) during the initial (virgin) debonding and subsequent healing events are measured. Debonding of the fiber/matrix interface ruptures the capsules, releasing resin and solvent into the crack plane. The solvent swells the matrix, initiating transport of residual amine functionality for further curing with the epoxy resin delivered to the crack plane. Using a resin-solvent ratio of 3:97, a maximum of 100% IFSS recovery is achieved-- a significant enhancement over prior work that reported 44% average recovery of IFSS with microencapsulated dicyclopentadiene (DCPD) monomer and Grubbs' 1st Generation catalyst healing agents. The effects of capsule coverage, resin-solvent ratio, and capsule size on recovery of IFSS are also determined, providing guidelines for integration of this healing system into high fiber volume fraction structural composites. High healing efficiencies are achieved with capsules as small as 0.6 mum average diameter. The resin-solvent healing system is then extended to repair of a carbon fiber/epoxy interfacial bond. A binder is necessary to improve the retention of capsules on the carbon fiber surface. Two different methods for applying a binder to a carbon fiber surface are investigated. Healing efficiency is assessed by recovery of IFSS of a single functionalized fiber embedded in an epoxy microbond specimen. The two binder protocols produce comparable results, both yielding higher recovery of IFSS than samples prepared without a binder. A maximum of 91% recovery of IFSS is achieved. In the next study, the resin-solvent healing system is applied to both interfacial damage and matrix cracking in a model composite specimen, consisting of discrete fiber tows embedded in a room temperature cured epoxy. Glass fiber tows are precisely placed in a compact tension specimen for controlled crack growth. The progression of matrix cracking and fiber debonding is observed optically during testing. Healing potential is assessed by injection of the healing agents into reference specimens (no capsules). The area under the load-displacement curve recovered during the healing event serves as a metric for evaluation of healing performance. Though full recovery is achieved in neat epoxy specimens, healing efficiency in multi-tow specimens is limited to 50%, due to the larger crack separations and energy lost during fiber fracture. In the case of only a singular embedded fiber tow, healing efficiency increases to an average of 83% recovery with full recovery in several samples. Additionally, microcapsules are incorporated into the compact tension specimen and along the fiber tow interface to evaluate in situ healing. Several strategies to improve microcapsule thermal stability are investigated in order to transition solvent-based healing to high temperature cured material systems. A double shell wall technique is adopted for several different size scales of microcapsules. First, the effect of the inner polyurethane (PU) shell wall thickness on thermal stability is evaluated. Though high thermal stability at 180°C is achieved for large (ca. 150 mum in diameter) capsules, smaller capsules (> 2 mum in diameter) suffer from increased core loss. The addition of certain core thickeners improves thermal stability for small capsules (ca. 20% increase in core retention) when compared to capsules with solvent alone. However, an additional poly(dopamine) coating leads to the greatest improvement in thermal stability, with nearly full retention of the core solvent for all capsule size scales. Finally, a thermoplastic resin poly(bisphenol A-co-epichlorohydrin), PBAE, is blended with a high glass transition temperature (Tg) epoxy matrix to simultaneously toughen and act as a healing agent in combination with encapsulated solvents. Microcapsules are coated with poly(dopamine) to improve the thermal stability and retain the core solvent during a cure cycle at 180°C. The fracture toughness of the high Tg epoxy (EPON 828: diamino diphenyl sulfone) is doubled by the addition of 20 wt % PBAE alone and tripled by the addition of both microcapsules and the thermoplastic phase. Self-healing is achieved with up to 57% recovery of fracture toughness of the toughened epoxy. Healing performance and fracture toughness of the microcapsule containing material remain stable after aging 30 days. The relative amounts of thermoplastic phase and the presence of solvent-filled microcapsules influence the storage modulus, Tg, and healing performance of the polymer.

Study on compressive strength of self compacting mortar cubes under normal & electric oven curing methods

NASA Astrophysics Data System (ADS)

Prasanna Venkatesh, G. J.; Vivek, S. S.; Dhinakaran, G.

2017-07-01

In the majority of civil engineering applications, the basic building blocks were the masonry units. Those masonry units were developed as a monolithic structure by plastering process with the help of binding agents namely mud, lime, cement and their combinations. In recent advancements, the mortar study plays an important role in crack repairs, structural rehabilitation, retrofitting, pointing and plastering operations. The rheology of mortar includes flowable, passing and filling properties which were analogous with the behaviour of self compacting concrete. In self compacting (SC) mortar cubes, the cement was replaced by mineral admixtures namely silica fume (SF) from 5% to 20% (with an increment of 5%), metakaolin (MK) from 10% to 30% (with an increment of 10%) and ground granulated blast furnace slag (GGBS) from 25% to 75% (with an increment of 25%). The ratio between cement and fine aggregate was kept constant as 1: 2 for all normal and self compacting mortar mixes. The accelerated curing namely electric oven curing with the differential temperature of 128°C for the period of 4 hours was adopted. It was found that the compressive strength obtained from the normal and electric oven method of curing was higher for self compacting mortar cubes than normal mortar cube. The cement replacement by 15% SF, 20% MK and 25%GGBS obtained higher strength under both curing conditions.

Collective antibiotic treatment of trachoma

PubMed Central

Reinhards, J.; Weber, A.; Maxwell-Lyons, F.

1959-01-01

By the early 1950's, it was clear from numerous independent reports that certain of the broad-spectrum antibiotics were effective against the agent of trachoma. It seemed, however, that treatment had to be continued over long periods to effect a cure of the average case. With the assistance of WHO, comparative trials on a scale hitherto unprecedented in the disease—involving more than 9000 schoolchildren with active trachoma—have been conducted in Morocco since 1953 in order to assess the value of local treatment of trachoma with chlortetracycline and to develop simple and economic methods of treatment, for which there was a pressing need. Local application of 1% chlortetracycline ointment two or three times daily for 60 days gave almost 80% cures under reasonably favourable conditions and nearly 100% cures after re-treatment of cases not cured by the first course. Equally good results followed intermittent short-term treatment over longer periods. Relapse and reinfection rates were low. Collective mass treatment with antibiotics is clearly a valuable method of trachoma control. The use of intermittent treatment allows for a great economy both in antibiotics and in staff and other campaign expenses and makes possible the wide expansion of mass treatment programmes. PMID:14437176

Flexural properties of denture base polymers reinforced with a glass cloth-urethane polymer composite.

PubMed

Kanie, Takahito; Arikawa, Hiroyuki; Fujii, Koichi; Ban, Seiji

2004-10-01

A newly designed light-cured reinforcement made from urethanemethacrylate oligomer and woven glass cloth has orthotropic anisotropy. This is produced for incorporation into the outermost position under the greatest tension in denture base resins. In this study, the flexural properties of self-, heat-, and light-curing reinforced resins were determined. The silanized glass cloth was soaked in urethanemethacrylate oligomer containing camphorquinone and 2-(dimethylamino)ethylmethacrylate. It was sandwiched between two pieces of polyethylene film and pressed to form a reinforcement sheet 0.3 mm in thickness, which was light-cured and prepared using four different surface conditions: with or without the polyethylene film and with or without a bonding agent. The reinforcement sheet was fixed in a fluorocarbon resin mold 3 mm in thickness, which was filled with self-, heat-, or light-curing resin and cured. The cured laminated plate was cut for flexural testing (40 x 7 x 3 mm3). A three-point flexural test was carried out at a crosshead speed of 2 mm/min and a span length of 30 mm. In this study, the glass fiber content was measured at percentages by weight because it was not possible to determine accurately the volume of the various polymers. The baseline flexural strengths of the self-, heat-, and light-curing resins were 76.2, 68.6, and 55.6 MPa, respectively, and these values were increased to 271.7, 216.4, and 266.5 MPa by the reinforcement sheet. The baseline flexural moduli of self-, heat-, and light-curing resins were 2.0, 2.4, and 2.1 GPa, respectively. These values were increased to 7.2, 5.1, and 6.6 GPa by the reinforcement sheet. SEM photographs revealed good impregnation of the glass fiber within the polymer matrix. The differences in the flexural strengths and flexural moduli of the control and reinforced specimens were significant (p < 0.01).

Synthesis of a new hardener agent for self-healing epoxy resins

NASA Astrophysics Data System (ADS)

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

2014-05-01

Actually, the development of smart composites capable of self-repair in aeronautical structures is still at the planning stage owing to complex issues to overcome. One of the critical points in the development of self-healing epoxy resin is related to the impossibility to employ primary amines as hardeners. In this paper, the synthesis of a new hardener for self-healing resins is shown together with applicability conditions/ranges.

Easy and Fast Method for the Determination of Biogenic Amines in Fish and Fish Products with Liquid Chromatography Coupled to Orbitrap Tandem Mass Spectrometry.

PubMed

Kaufmann, Anton; Maden, Kathryn

2018-03-01

A quantitative method for the determination of biogenic amines was developed. The method is characterized by the virtual absence of sample cleanup and does not require a derivatization reaction. Diluted extracts are centrifuged, filtrated, and directly injected into an ultra-HPLC column, which is coupled to a single-stage high-resolution mass spectrometer (Orbitrap). The chromatography is based on a reversed-phase column and an eluent containing an ion-pairing agent (heptafluorobutyric acid). The high sensitivity of the instrument permits the injection of very diluted extracts, which ensures stable retention times and the virtual absence of signal suppression effects. In addition, the quantification of histamine (a regulated compound) is further aided by the use of an isotopically labeled internal standard. The method was validated for three fish-based matrixes. Both the sample processing and the analytical measurement are very fast; hence, the methodology is ideal for high-throughput work. In addition, the method is significantly more selective than conventional methods (i.e., derivatization followed by LC with UV/fluorescence (FL) detection) for biogenic amines. A comparison showed that LC-UV/FL methods can produce false-positive findings due to coeluting matrix compounds.

On-column nitrosation of amines observed in liquid chromatography impurity separations employing ammonium hydroxide and acetonitrile as mobile phase.

PubMed

Myers, David P; Hetrick, Evan M; Liang, Zhongming; Hadden, Chad E; Bandy, Steven; Kemp, Craig A; Harris, Thomas M; Baertschi, Steven W

2013-12-06

The availability of high performance liquid chromatography (HPLC) columns capable of operation at pH values up to 12 has allowed a greater selectivity space to be explored for method development in pharmaceutical analysis. Ammonium hydroxide is of particular value in the mobile phase because it is compatible with direct interfacing to electrospray mass spectrometers. This paper reports an unexpected N-nitrosation reaction that occurs with analytes containing primary and secondary amines when ammonium hydroxide is used to achieve the high pH and acetonitrile is used as the organic modifier. The nitrosation reaction has generality. It has been observed on multiple columns from different vendors and with multiple amine-containing analytes. Ammonia was established to be the source of the nitroso nitrogen. The stainless steel column frit and metal ablated from the frit have been shown to be the sites of the reactions. The process is initiated by removal of the chromium oxide protective film from the stainless steel by acetonitrile. It is hypothesized that the highly active, freshly exposed metals catalyze room temperature oxidation of ammonia to NO but that the actual nitrosating agent is likely N(2)O(3). Copyright © 2013 Elsevier B.V. All rights reserved.

Carbon dioxide capture by activated methyl diethanol amine impregnated mesoporous carbon

NASA Astrophysics Data System (ADS)

Ardhyarini, N.; Krisnandi, Y. K.

2017-07-01

Activated Methyl Diethanol Amine (aMDEA) were impregnated onto the surface of the mesoporous carbon to increase carbon dioxide (CO2) adsorption capacity. The mesoporous carbon was synthesized through soft template method with phloroglucinol as carbon precursor and triblock copolymer (Pluronic F127) as structure directing agent. These activated MDEA impregnated mesoporous carbon (aMDEA-MC) were characterized using various solid characterization techniques. CO2 adsorption was investigated using autoclaved-reactor in the batch system. The FTIR spectrum of aMDEA-MC had absorption peaks at 3395 cm-1 and 1031 cm-1 which are characteristic for O-H stretch and amine C-N stretch in MDEA. The elemental analyzer showed that nitrogen content on the mesoporous carbon increased after impregnation by 23 wt.%. The BET surface area and total pore volume of mesoporous carbon decreased after impregnation, 43 wt.% and 50 wt.%, respectively. The maximum CO2 adsorption capacity of aMDEA43-MC was 2.63 mmol/g (298 K, 5 psi and pure CO2). This is 64 % and 35 % higher compared to the CO2 adsorption capacity of the starting MC and also commercially available activated carbon with higher surface area. All the results suggest that MDEA-MC is a promising adsorbent for CO2 capture.

Effectiveness and safety of nitrofurantoin in outpatient male veterans.

PubMed

Ingalsbe, Michelle L; Wojciechowski, Amy L; Smith, Kelly A; Mergenhagen, Kari A

2015-08-01

The aim of the study was to assess both the safety and the effectiveness of nitrofurantoin in male veterans treated for urinary tract infections (UTIs) with varying degrees of renal impairment in the outpatient setting. Nitrofurantoin is an important oral option for treating UTIs given increasing resistance to commonly used agents. Nitrofurantoin is currently contraindicated in patients with a creatinine clearance (CrCl) of < 60 ml/min, but the reason for this threshold has not been well documented. Data were collected through a retrospective chart review from January 2004 to July 2013 of men who had received nitrofurantoin. Bivariate analyses followed by multivariate analyses were performed between patients experiencing clinical cure and those who did not, to determine factors significantly impacting effectiveness. The Gram stain of the organism causing the UTI and CrCl were significant factors impacting effectiveness. For every 1 ml/min increase in CrCl, the odds of clinical cure increased by 1.3%. Patients with Gram-negative UTIs predictably had 80% cure rates with CrCl around 60 ml/min. Patients with Gram-positive UTIs required higher CrCl, nearing 100 ml/min, to establish an 80% cure rate. Adverse effects did not vary with CrCl. The odds of clinical cure varied with CrCl and with the type of organism causing the UTI, while adverse events did not differ based on renal function. A minimum CrCl of 60 ml/min is suggested for men to achieve an 80% cure rate for UTIs with the most common urinary pathogens.

Travelers with cutaneous leishmaniasis cured without systemic therapy.

PubMed

Morizot, G; Kendjo, E; Mouri, O; Thellier, M; Pérignon, A; Foulet, F; Cordoliani, F; Bourrat, E; Laffitte, E; Alcaraz, I; Bodak, N; Ravel, C; Vray, M; Grogl, M; Mazier, D; Caumes, E; Lachaud, L; Buffet, P A

2013-08-01

Cutaneous leishmaniasis (CL) is a disfiguring but not life-threatening disease. Because antileishmanial drugs are potentially toxic, the World Health Organization (WHO) recommends simple wound care or local therapy as first-line treatment, followed or replaced by systemic therapy if local therapy fails or cannot be performed. To determine the feasibility and impact of the recommended approach, we analyzed the results of a centralized referral treatment program in 135 patients with parasitologically proven CL. Infections involved 10 Leishmania species and were contracted in 29 different countries. Eighty-four of 135 patients (62%) were initially treated without systemic therapy. Of 109 patients with evaluable charts, 23 of 25 (92%) treated with simple wound care and 37 of 47 (79%) treated with local antileishmanial therapy were cured by days 42-60. In 37 patients with large or complex lesions, or preexisting morbidities, or who had not been cured with local therapy, the cure rate with systemic antileishmanial agents was 60%. Systemic adverse events were observed in 15 patients, all receiving systemic therapy. In this population of CL patients displaying variable degrees of complexity and severity, almost two-thirds of patients could be initially managed without systemic therapy. Of these, 60 were cured before day 60. The WHO-recommended stepwise approach favoring initial local therapy therefore resulted in at least 44% of all patients being cured without exposure to the risk of systemic adverse events. Efforts are needed to further simplify local therapy of CL and to improve the management of patients with complex lesions and/or preexisting comorbidities.

Influence of Different Types of Resin Luting Agents on Color Stability of Ceramic Laminate Veneers Subjected to Accelerated Artificial Aging.

PubMed

Silami, Francisca Daniele Jardilino; Tonani, Rafaella; Alandia-Román, Carla Cecilia; Pires-de-Souza, Fernanda de Carvalho Panzeri

2016-01-01

The aim of this study was to evaluate the influence of accelerated aging (AAA) on the color stability of resin cements for bonding ceramic laminate veneers of different thicknesses. The occlusal surfaces of 80 healthy human molars were flattened. Ceramic laminate veneers (IPS e-max Ceram) of two thicknesses (0.5 and 1.0 mm) were bonded with three types of luting agents: light-cured, conventional dual and self-adhesive dual cement. Teeth without restorations and cement samples (0.5 mm) were used as control. After initial color evaluations, the samples were subjected to AAA for 580 h. After this, new color readouts were made, and the color stability (ΔE) and luminosity (ΔL) data were analyzed. The greatest color changes (p<0.05) occurred when 0.5 mm veneers were fixed with light-cured cement and the lowest when 1.0 mm veneers were fixed with conventional dual cement. There was no influence of the restoration thickness when the self-adhesive dual cement was used. When veneers were compared with the control groups, it was verified that the cement samples presented the greatest alterations (p<0.05) in comparison with both substrates and restored teeth. Therefore, it was concluded that the thickness of the restoration influences color and luminosity changes for conventional dual and light-cured cements. The changes in self-adhesive cement do not depend on restoration thickness.

Fabrication of low density ceramic material

DOEpatents

Meek, T.T.; Blake, R.D.; Sheinberg, H.

1985-01-01

A precursor mixture and a method of making a low-density ceramic structural material are disclosed. The precursor mixture includes hollow microballoons, typically made of glass, together with a cementing agent capable of being cured by microwave irradiation. A preferred cementing agent is liquid hydrated potassium silicate, which is mixed with the glass microballoons to form a slurry. Upon irradiation the potassium silicate is dehydrated to form a solid porous matrix in which the microballoons are evenly distributed. Ground glass or other filling agents may be included in the slurry to enhance the properties of the final product. Low-density structural ceramics having densities on the order of 0.1 to 0.3 are obtained.