Formation of Nano scale Bio imprints of Muscle Cells Using UV-Cured Spin-Coated Polymers

International Nuclear Information System (INIS)

Samsuri, F.; Alkaisi, M.M.; Mitchell, J.S.; Evans, J.J.

2009-01-01

We report a nano scale replication method suitable for biological specimens that has potential in single cell studies and in formation of 3D biocompatible scaffolds. Earlier studies using a heat-curable polydimethylsiloxane (PDMS) or a UV-curable elastomer introduced Bio imprint replication to facilitate cell imaging. However, the replicating conditions for thermal polymerization are known to cause cell dehydration during curing. In this study, a UV-cured methacrylate copolymer was developed for use in creating replicas of living cells and was tested on rat muscle cells. Bio imprints of muscle cells were formed by spin coating under UV irradiation. The polymer replicas were then separated from the muscle cells and were analyzed under an Atomic Force Microscope (AFM), in tapping mode, because it has low tip-sample forces and thus will not destroy the fine structures of the imprint. The new polymer is biocompatible with higher replication resolution and has a faster curing process than other types of silicon-based organic polymers such as PDMS. High resolution images of the muscle cell imprints showed the micro-and nano structures of the muscle cells, including cellular fibers and structures within the cell membranes. The AFM is able to image features at nano scale resolution with the potential for recognizing abnormalities on cell membranes at early stages of disease progression.

Radiation curing - a personal perspective

International Nuclear Information System (INIS)

Pappas, S.P.

1992-01-01

This chapter briefly introduces radiation curing from the personal perspective of the author. Topics covered in this chapter include characteristic features of radiation curing, photoinitiated polymerization -- ultraviolet (UV) curing, and general principles of electron beam (EB) curing. 57 refs., 2 tabs

Radiation curing of polymers

International Nuclear Information System (INIS)

Randell, D.R.

1987-01-01

The contents of this book are: Areas of Application of UV Curing; Areas of Application of EB Curing; Laser Curing of Acrylic Coatings; A User's View of the Application of Radiation Curable Materials; Radiation Curable Offset Inks: A Technical and Marketing Overview; and UV Curable Screen Printing Inks

Radiation curing in the eighties

International Nuclear Information System (INIS)

Vrancken, A.

1984-01-01

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

A flexible cure rate model with dependent censoring and a known cure threshold.

Science.gov (United States)

Bernhardt, Paul W

2016-11-10

We propose a flexible cure rate model that accommodates different censoring distributions for the cured and uncured groups and also allows for some individuals to be observed as cured when their survival time exceeds a known threshold. We model the survival times for the uncured group using an accelerated failure time model with errors distributed according to the seminonparametric distribution, potentially truncated at a known threshold. We suggest a straightforward extension of the usual expectation-maximization algorithm approach for obtaining estimates in cure rate models to accommodate the cure threshold and dependent censoring. We additionally suggest a likelihood ratio test for testing for the presence of dependent censoring in the proposed cure rate model. We show through numerical studies that our model has desirable properties and leads to approximately unbiased parameter estimates in a variety of scenarios. To demonstrate how our method performs in practice, we analyze data from a bone marrow transplantation study and a liver transplant study. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Relaxed Poisson cure rate models.

Science.gov (United States)

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

2016-03-01

The purpose of this article is to make the standard promotion cure rate model (Yakovlev and Tsodikov, ) more flexible by assuming that the number of lesions or altered cells after a treatment follows a fractional Poisson distribution (Laskin, ). It is proved that the well-known Mittag-Leffler relaxation function (Berberan-Santos, ) is a simple way to obtain a new cure rate model that is a compromise between the promotion and geometric cure rate models allowing for superdispersion. So, the relaxed cure rate model developed here can be considered as a natural and less restrictive extension of the popular Poisson cure rate model at the cost of an additional parameter, but a competitor to negative-binomial cure rate models (Rodrigues et al., ). Some mathematical properties of a proper relaxed Poisson density are explored. A simulation study and an illustration of the proposed cure rate model from the Bayesian point of view are finally presented. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Science.gov (United States)

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

1981-01-01

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

Surface modification of commercial seawater reverse osmosis membranes by grafting of hydrophilic monomer blended with carboxylated multiwalled carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Vatanpour, Vahid, E-mail: vahidvatanpour@khu.ac.ir; Zoqi, Naser

2017-02-28

Highlights: • A commercial PA RO membrane was modified by grafting of hydrophilic acrylic acid. • COOH-MWCNTs were mixed in grafting layer to increase permeability and antifouling. • However, more increase of CNTs caused in reduction of flux of the membranes. • Effect of acrylic acid amount, contact time and curing time was optimized. - Abstract: In this study, modification of commercial seawater reverse osmosis membranes was carried out with simultaneous use of surface grafting and nanoparticle incorporation. Membrane grafting with a hydrophilic acrylic acid monomer and thermal initiator was used to increase membrane surface hydrophilicity. The used nanomaterial was carboxylated multiwalled carbon nanotubes (MWCNTs), which were dispersed in the grafting solution and deposited on membrane surface to reduce fouling by creating polymer brushes and hydrodynamic resistance. Effectiveness of the grafting process (formation of graft layer on membrane surface) was proved by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses. Increase of membrane surface hydrophilicity was approved with contact angle test. First, the grafting was performed on the membrane surfaces with different monomer concentrations, various contact times and several membrane curing times (three variables for optimization). The modified membranes were tested by a cross-flow setup using saline solution for permeability and rejection tests, and bovine serum albumin (BSA) solution for fouling test. The results showed that the modified membranes with 0.75 M of monomer, 3 min contact time and 80 min curing time in an oven at 50 °C presented the highest flux and lowest rejection decline related to the commercial reverse osmosis membrane. In the next step, the optimum grafting condition was selected and the nanotubes with different weight percentages were dispersed in the acrylic acid monomer solution. The membrane containing 0.25 wt% COOH-MWCNTs showed the

Surface modification of commercial seawater reverse osmosis membranes by grafting of hydrophilic monomer blended with carboxylated multiwalled carbon nanotubes

International Nuclear Information System (INIS)

Vatanpour, Vahid; Zoqi, Naser

2017-01-01

Highlights: • A commercial PA RO membrane was modified by grafting of hydrophilic acrylic acid. • COOH-MWCNTs were mixed in grafting layer to increase permeability and antifouling. • However, more increase of CNTs caused in reduction of flux of the membranes. • Effect of acrylic acid amount, contact time and curing time was optimized. - Abstract: In this study, modification of commercial seawater reverse osmosis membranes was carried out with simultaneous use of surface grafting and nanoparticle incorporation. Membrane grafting with a hydrophilic acrylic acid monomer and thermal initiator was used to increase membrane surface hydrophilicity. The used nanomaterial was carboxylated multiwalled carbon nanotubes (MWCNTs), which were dispersed in the grafting solution and deposited on membrane surface to reduce fouling by creating polymer brushes and hydrodynamic resistance. Effectiveness of the grafting process (formation of graft layer on membrane surface) was proved by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses. Increase of membrane surface hydrophilicity was approved with contact angle test. First, the grafting was performed on the membrane surfaces with different monomer concentrations, various contact times and several membrane curing times (three variables for optimization). The modified membranes were tested by a cross-flow setup using saline solution for permeability and rejection tests, and bovine serum albumin (BSA) solution for fouling test. The results showed that the modified membranes with 0.75 M of monomer, 3 min contact time and 80 min curing time in an oven at 50 °C presented the highest flux and lowest rejection decline related to the commercial reverse osmosis membrane. In the next step, the optimum grafting condition was selected and the nanotubes with different weight percentages were dispersed in the acrylic acid monomer solution. The membrane containing 0.25 wt% COOH-MWCNTs showed the

Critical parameters for electron beam curing of cationic epoxies and property comparison of electron beam cured cationic epoxies versus thermal cured resins and composites

International Nuclear Information System (INIS)

Janke, C.J.; Norris, R.E.; Yarborough, K.; Lopata, V.J.

1997-01-01

Electron beam curing of composites is a nonthermal, nonautoclave curing process offering the following advantages compared to conventional thermal curing: substantially reduced manufacturing costs and curing times; improvements in part quality and performance; reduced environmental and health concerns; and improvements in material handling. In 1994 a Cooperative Research and Development Agreement (CRADA), sponsored by the Department of Energy Defense Programs and 10 industrial partners, was established to advance electron beam curing of composites. The CRADA has successfully developed hundreds of new toughened and untoughened resins, offering unlimited formulation and processing flexibility. Several patent applications have been filed for this work. Composites made from these easily processable, low shrinkage material match the performance of thermal cured composites and exhibit: low void contents comparable to autoclave cured composites (less than 1%); superb low water absorption values in the same range as cyanate esters (less than 1%); glass transition temperatures rivaling those of polyimides (greater than 390 C); mechanical properties comparable to high performance, autoclave cured composites; and excellent property retention after cryogenic and thermal cycling. These materials have been used to manufacture many composite parts using various fabrication processes including hand lay-up, tow placement, filament winding, resin transfer molding and vacuum assisted resin transfer molding

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

Science.gov (United States)

Steinhaus, Johannes; Hausnerova, Berenika; Haenel, Thomas; Großgarten, Mandy; Möginger, Bernhard

2014-03-01

During the curing process of light curing dental composites the mobility of molecules and molecule segments is reduced leading to a significant increase of the viscosity as well as the ion viscosity. Thus, the kinetics of the curing behavior of 6 different composites was derived from dielectric analysis (DEA) using especially redesigned flat sensors with interdigit comb electrodes allowing for irradiation at the top side and measuring the ion viscosity at the bottom side. As the ion viscosities of dental composites change 1-3 orders of magnitude during the curing process, DEA provides a sensitive approach to evaluate their curing behavior, especially in the phase of undisturbed chain growth. In order to determine quantitative kinetic parameters a kinetic model is presented and examined for the evaluation of the ion viscosity curves. From the obtained results it is seen that DEA might be employed in the investigation of the primary curing process, the quality assurance of ingredients as well as the control of processing stability of the light curing dental composites. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Influence of polyvinyl alcohol amount on producing in situ photo-crosslinked thioamide functionalized nanofiber membranes

Directory of Open Access Journals (Sweden)

Zeytuncu Bihter

2015-01-01

Full Text Available Poly(vinyl alcohol/maleic anhydride/acryloyl thioamide monomer (PVA/MA/ATM photo-cured nanofiber membranes and pure PVA nanofiber membranes were produced by electrospinning technique. In situ UV radiation was applied during the electrospinning in order to provide polymerization during the jet flight and promote crosslinking of ATM and MA with PVA. The cross-linking was examined by Fourier-transform infrared spectroscopy (FTIR. The morphology and thermal behavior of electrospun nanofiber were characterized by scanning electron microscope (SEM and thermogravimetric analysis (TGA, respectively. The surface area of nanofiber membranes was measured by Brunauer-Emmert-Teller (BET analysis. Furthermore, water durability test was examined. Water durability test demonstrated that in situ photo-cured PVA/MA/ATM nanofiber membrane had the least average mass loss. The surface areas of PVA/MA/ATM nanofiber membranes were 160-280 m2/g. The surface area and diameter of PVA/MA/ATM nanofibers decreased as the PVA content increased. The diameter of nanofibers was obtained less than 100 nm. The results showed that the water-insoluble nanofiber membranes with better chemical and thermal resistance were obtained. These nanofiber membranes may be a promising candidate for the usage of water treatment.

Pervaporation separation of ethanol-water mixtures using polyethylenimine composite membranes

Science.gov (United States)

Neidlinger, H.H.; Schissel, P.O.; Orth, R.A.

1985-06-19

Synthetic, organic, polymeric membranes were prepared from polyethylenimine for use with pervaporation apparatus in the separation of ethanol-water mixtures. The polymeric material was prepared in dilute aqueous solution and coated onto a polysulfone support film, from which excess polymeric material was subsequently removed. Cross-links were then generated by limited exposure to toluene-2,4-diisocyanate solution, after which the prepared membrane was heat-cured. The resulting membrane structures showed high selectivity in permeating ethanol or water over a wide range of feed concentrations. 2 tabs.

Residual Stress Developed During the Cure of Thermosetting Polymers: Optimizing Cure Schedule to Minimize Stress.

Energy Technology Data Exchange (ETDEWEB)

Kropka, Jamie Michael; Stavig, Mark E.; Jaramillo, Rex

2016-06-01

When thermosetting polymers are used to bond or encapsulate electrical, mechanical or optical assemblies, residual stress, which often affects the performance and/or reliability of these devices, develops within the structure. The Thin-Disk-on-Cylinder structural response test is demonstrated as a powerful tool to design epoxy encapsulant cure schedules to reduce residual stress, even when all the details of the material evolution during cure are not explicitly known. The test's ability to (1) distinguish between cohesive and adhesive failure modes and (2) demonstrate methodologies to eliminate failure and reduce residual stress, make choices of cure schedules that optimize stress in the encapsulant unambiguous. For the 828/DEA/GMB material in the Thin-Disk-on-Cylinder geometry, the stress associated with cure is significant and outweighs that associated with cool down from the final cure temperature to room temperature (for measured lid strain, Scure I > I I e+h erma * II) * The difference between the final cure temperature and 1 1 -- the temperature at which the material gels, Tf-T ge i, was demonstrated to be a primary factor in determining the residual stress associated with cure. Increasing T f -T ge i leads to a reduction in cure stress that is described as being associated with balancing some of the 828/DEA/GMB cure shrinkage with thermal expansion. The ability to tune residual stress associated with cure by controlling T f -T ge i would be anticipated to translate to other thermosetting encapsulation materials, but the times and temperatures appropriate for a given material may vary widely.

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

Directory of Open Access Journals (Sweden)

César Augusto Galvão Arrais

2010-06-01

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

Accelerated dry curing of hams.

Science.gov (United States)

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

1985-01-01

Uncured pork legs from the right side of 18 carcasses were treated with a Ross Tenderizer and the left side were controls. All 36 samples were dry-cured for 40, 56 or 70 days and evaluated for appearance traits, cure penetration characteristics, microbial load, Kramer Shear force and taste attributes. The tenderization treatment had no effect (P > 0·05) on visual color or cure penetration rate, weight loss before curing, percentage moisture, nitrate level, nitrite level, total plate count, anaerobic counts, psychrotrophic counts, objective and subjective tenderness measurements or juiciness. However, the higher values of salt suggested a possible acceleration of the dry cure penetration process among the tenderized samples. Cure time had no effect (P > 0·05) on percentage moisture, percentage salt, nitrate content, nitrite content, shear force and juiciness. Results suggest a limited effect of the mechanical tenderization process on certain traits related to dry curing and that total process time should be at least 70 days if color stability during cooking is desired. Copyright © 1985. Published by Elsevier Ltd.

Development situation of radiation curing materials

International Nuclear Information System (INIS)

He Songhua; Luo Junyi; Liu Zhen

2010-01-01

Due to fitting the '4E' principle, radiation curing technology, known as green technology, have shown its own superiority in many applications. It has been rapid developed in China and abroad in recent years, especially ultraviolet/electron beam (UV/EB) radiation curing technology. In order to let the researchers have a general understanding on the radiation curing materials and their development, in this paper a briefly introducing on the related radiation sources, chemical systems, curing mechanism, and the application, the common and difference of ultraviolet curing and electron beam curing has been made. A brief account of development of radiation-curable material in China and the outlook of the development of materials can be found in this paper. At last, we have proposed that the development of radiation curing technology will promote the development of the radiation curing material and benefit in the humanity. (authors)

Curing behavior and thermal properties of trifunctional epoxy resin cured by 4, 4’-diaminodiphenyl sulfone

Directory of Open Access Journals (Sweden)

2009-08-01

Full Text Available A novel trifunctional epoxy resin 4-(3, 3-dihydro-7-hydroxy-2, 4, 4-trimethyl-2H-1-benzopyran-2-yl-1, 3-benzenediol glycidyl (shorted as TMBPBTH-EPOXY was synthesized in our lab to improve thermal performance. Its curing behavior and performance were studied by using 4, 4′-diaminodiphenyl sulfone (DDS as hardener with the mass ratio of 100:41 of TMBPBTH-EPOXY and DDS. The curing activation energy was investigated by differential scanning calorimetry (DSC to be 64.0 kJ/mol estimated by Kissinger’s method and 68.7 kJ/mol estimated by Flynn-Wall-Ozawa method respectively. Thermogravimetric analyzer (TGA was used to investigate the thermal decomposition of cured compounds. It was found that when curing temperature was lower than 180°C, the thermal decomposition temperature increased with the rise of curing temperature and curing time. On the other hand, when the curing temperature was higher than 180°C, the thermal decomposition temperature went down instead with the increase of curing time that might be the over-crosslinking of TMBPBTH-EPOXY and DDS hardener. The glass transition temperature (Tg of cured TMBPBTH-EPOXY/DDS compound determined by dynamic mechanical thermal analysis (DMTA is 290.1°C.

Degree of conversion and surface hardness of resin cement cured with different curing units.

Science.gov (United States)

Ozturk, Nilgun; Usumez, Aslihan; Usumez, Serdar; Ozturk, Bora

2005-01-01

The aim of this study was to evaluate the degree of conversion and Vickers surface hardness of resin cement under a simulated ceramic restoration with 3 different curing units: a conventional halogen unit, a high-intensity halogen unit, and a light-emitting diode system. A conventional halogen curing unit (Hilux 550) (40 s), a high-intensity halogen curing unit used in conventional and ramp mode (Optilux 501) (10 s and 20 s, respectively), and a light-emitting diode system (Elipar FreeLight) (20 s, 40 s) were used in this study. The dual-curing resin cement (Variolink II) was cured under a simulated ceramic restoration (diameter 5 mm, height 2 mm), and the degree of conversion and Vickers surface hardness were measured. For degree of conversion measurement, 10 specimens were prepared for each group. The absorbance peaks were recorded using the diffuse-reflection mode of Fourier transformation infrared spectroscopy. For Vickers surface hardness measurement, 10 specimens were prepared for each group. A load of 200 N was applied for 15 seconds, and 3 evaluations of each of the samples were performed. Degree of conversion achieved with Optilux 501 (20 s) was significantly higher than those of Hilux, Optilux 501 (10 s), Elipar FreeLight (20 s), and Elipar FreeLight (40 s). For Vickers surface hardness measurement, Optilux 501 (20 s) produced the highest surface hardness value. No significant differences were found among the Hilux, Optilux 501 (10 s), Elipar FreeLight (20 s), and Elipar FreeLight (40 s). The high-intensity halogen curing unit used in ramp mode (20 s) produced harder resin cement surfaces than did the conventional halogen curing unit, high-intensity halogen curing unit used in conventional mode (10 s) and light-emitting diode system (20 s, 40 s), when cured through a simulated ceramic restoration.

Excimer UV curing in printing

International Nuclear Information System (INIS)

Mehnert, R.

1999-01-01

It is the aim of this study to investigate the potential of 308 run excimer UV curing in web and sheet fed offset printing and to discuss its present status. Using real-time FTIR-ATR and stationary or pulsed monochromatic (313 nm) irradiation chemical and physical factors affecting the curing speed of printing inks such as nature and concentration of photo-initiators, reactivity of the ink binding system, ink thickness and pigmentation, irradiance in the curing plane, oxygen concentration and nitrogen inerting, multiple pulse exposure, the photochemical dark reaction and temperature dependence were studied. The results were used to select optimum conditions for excimer UV curing in respect to ink reactivity, nitrogen inerting and UV exposure and to build an excimer UV curing unit consisting of two 50 W/cm 308 run excimer lamps, power supply, cooling and inerting unit. The excimer UV curing devices were tested under realistic conditions on a web offset press zirkon supra forte and a sheet fed press Heidelberg GTO 52. Maximum curing speeds of 300 m/min in web offset and 8000 sheets per hour in sheet fed offset were obtained

Electron curing of surface coatings

International Nuclear Information System (INIS)

Nablo, S.V.

1974-01-01

The technical development of electron curing of surface coatings has received great impetus since 1970 from dramatic changes in the economics of the conventional thermal process. The most important of these changes are reviewed, including: the Clear Air Act, increasing cost and restrictive allocation of energy, decreased availability and increased costs of solvents, competitive pressure for higher line productivity. The principles of free-radical initiated curing as they pertain to industrial coatings are reviewed. Although such electron initiated processes have been under active development for at least two decades, high volume production applications on an industrial scale have only recently appeared. These installations are surveyed with emphasis on the developments in machinery and coatings which have made this possible. The most significant economic advantages of electron curing are presented. In particular, the ability of electron curing to eliminate substrate damage and to eliminate the curing station (oven) as the pacing element for most industrial surface coating curing applications is discussed. Examples of several new processes of particular interest in the textile industry are reviewed, including the curing of transfer cast urethane films, flock adhesives, and graftable surface finishes

Composite cements benefit from light-curing.

Science.gov (United States)

Lührs, Anne-Katrin; De Munck, Jan; Geurtsen, Werner; Van Meerbeek, Bart

2014-03-01

To investigate the effect of curing of composite cements and a new ceramic silanization pre-treatment on the micro-tensile bond strength (μTBS). Feldspathic ceramic blocks were luted onto dentin using either Optibond XTR/Nexus 3 (XTR/NX3; Kerr), the silane-incorporated 'universal' adhesive Scotchbond Universal/RelyX Ultimate (SBU/RXU; 3M ESPE), or ED Primer II/Panavia F2.0 (ED/PAF; Kuraray Noritake). Besides 'composite cement', experimental variables were 'curing mode' ('AA': complete auto-cure at 21°C; 'AA*': complete auto-cure at 37°C; 'LA': light-curing of adhesive and auto-cure of cement; 'LL': complete light-curing) and 'ceramic surface pre-treatment' ('HF/S/HB': hydrofluoric acid ('HF': IPS Ceramic Etching Gel, Ivoclar-Vivadent), silanization ('S': Monobond Plus, Ivoclar-Vivadent) and application of an adhesive resin ('HB': Heliobond, Ivoclar-Vivadent); 'HF/SBU': 'HF' and application of the 'universal' adhesive Scotchbond Universal ('SBU'; 3M ESPE, only for SBU/RXU)). After water storage (7 days at 37°C), ceramic-dentin sticks were subjected to μTBS testing. Regarding the 'composite cement', the significantly lowest μTBSs were measured for ED/PAF. Regarding 'curing mode', the significantly highest μTBS was recorded when at least the adhesive was light-cured ('LA' and 'LL'). Complete auto-cure ('AA') revealed the significantly lowest μTBS. The higher auto-curing temperature ('AA*') increased the μTBS only for ED/PAF. Regarding 'ceramic surface pre-treatment', only for 'LA' the μTBS was significantly higher for 'HF/S/HB' than for 'HF/SBU'. Complete auto-cure led to inferior μTBS than when either the adhesive (on dentin) or both adhesive and composite cement were light-cured. The use of a silane-incorporated adhesive did not decrease luting effectiveness when also the composite cement was light-cured. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

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

Directory of Open Access Journals (Sweden)

Priyanka Verma

2016-01-01

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

Post-cure depth of cure of bulk fill dental resin-composites.

Science.gov (United States)

Alrahlah, A; Silikas, N; Watts, D C

2014-02-01

To determine the post-cure depth of cure of bulk fill resin composites through using Vickers hardness profiles (VHN). Five bulk fill composite materials were examined: Tetric EvoCeram(®) Bulk Fill, X-tra base, Venus(®) Bulk Fill, Filtek™ Bulk Fill, SonicFill™. Three specimens of each material type were prepared in stainless steel molds which contained a slot of dimensions (15 mm × 4 mm × 2 mm), and a top plate. The molds were irradiated from one end. All specimens were stored at 37°C for 24h, before measurement. The Vickers hardness was measured as a function of depth of material, at 0.3mm intervals. Data were analysed by one-way ANOVA using Tukey post hoc tests (α=0.05). The maximum VHN ranged from 37.8 to 77.4, whilst the VHN at 80% of max.VHN ranged from 30.4 to 61.9. The depth corresponding to 80% of max.VHN, ranged from 4.14 to 5.03 mm. One-way ANOVA showed statistically significant differences between materials for all parameters tested. SonicFill exhibited the highest VHN (pFill the lowest (p≤0.001). SonicFill and Tetric EvoCeram Bulk Fill had the greatest depth of cure (5.03 and 4.47 mm, respectively) and was significant's different from X-tra base, Venus Bulk Fill and Filtek Bulk Fill (p≤0.016). Linear regression confirmed a positive regression between max.VHN and filler loading (r(2)=0.94). Bulk fill resin composites can be cured to an acceptable post-cure depth, according to the manufacturers' claims. SonicFill and Tetric EvoCeram Bulk Fill had the greatest depth of cure among the composites examined. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Cure Schedule for Stycast 2651/Catalyst 11.

Energy Technology Data Exchange (ETDEWEB)

Kropka, Jamie Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); McCoy, John D. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States)

2017-11-01

The Henkel technical data sheet (TDS) for Stycast 2651/Catalyst 11 lists three alternate cure schedules for the material, each of which would result in a different state of reaction and different material properties. Here, a cure schedule that attains full reaction of the material is defined. The use of this cure schedule will eliminate variance in material properties due to changes in the cure state of the material, and the cure schedule will serve as the method to make material prior to characterizing properties. The following recommendation was motivated by (1) a desire to cure at a single temperature for ease of manufacture and (2) a desire to keep the cure temperature low (to minimize residual stress build-up associated with the cooldown from the cure temperature to room temperature) without excessively limiting the cure reaction due to vitrification (i.e., material glass transition temperature, T_g, exceeding cure temperature).

Properties of radiation cured coatings

International Nuclear Information System (INIS)

Larson, E.G.; Spencer, D.S.; Boettcher, T.E.; Melbauer, M.A.; Skarjune, R.P.

1987-01-01

Coatings were prepared from acrylate or methacrylate functionalized resins to study the effect of end group functionality on the physical properties of u.v. and electron beam cured coatings. Cure response was measured by solid state NMR and gel extraction, as expected, methacrylate resins cured much slower. Thermal Gravimetric Analysis (TGA) revealed acrylate coatings have greater thermal stability. Properties such as tensile strength and hardness showed little effect of end group functionality or curing method. The O 2 and H 2 O permeabilities of the coating were correlated with the processing conditions. (author)

The situation of radiation curing

International Nuclear Information System (INIS)

Chen Weixiu

1988-01-01

Radiation curing is a branch of radiation processing. It has developed significantly and its annual growth rate exceeds 10% in the nineteen eighties. Several products were manufactured by radiation curing, such as magnetic media, release coating, floor tile, printing flates, optical fiber, electronics, lithography and pressure sensitive adhesives etc. The chemistry of radiation curing is often considered ahead. The safe handling of UV/EB curable material, the regulation of industial and the patent protection for development in radiation curing were introduced. The equipment and processes of this field have got progress recently

Electron beam curing of coatings

International Nuclear Information System (INIS)

Schmidt, J.; Mai, H.

1986-01-01

Modern low-energy electron beam processors offer the possibility for high-speed curing of coatings on paper, plastics, wood and metal. Today the electron beam curing gets more importance due to the increasing environmental problems and the rising cost of energy. For an effective curing process low-energy electron beam processors as well as very reactive binders are necessary. Generally such binders consist of acrylic-modified unsaturated polyester resins, polyacrylates, urethane acrylates or epoxy acrylates and vinyl monomers, mostly multifunctional acrylates. First results on the production of EBC binders on the base of polyester resins and vinyl monomers are presented. The aim of our investigations is to obtain binders with curing doses ≤ 50 kGy. In order to reduce the curing dose we studied mixtures of resins and acrylates. (author)

Thermal Aging Behaviors of Rubber Vulcanizates Cured with Single and Binary Cure Systems

Energy Technology Data Exchange (ETDEWEB)

Choi, Sung Seen; Ha, Sung Ho [Sejong University, Seoul (Korea, Republic of); Woo, Chang Su [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

2006-03-15

In general, an accelerated sulfur cure system consists of elemental sulfur, one or two cure accelerators, and cure activators. Crosslink density of a rubber vulcanizate determines the physical properties. By increasing the crosslink density, the modulus, hardness, resilience, and abrasion resistance increase, whereas the elongation at break, heat build-up, and stress relaxation decrease. Sulfur linkages are composed of monosulfide, disulfide, and polysulfides. Sulfur linkages, especially polysulfides, are dissociated by heating and this brings about decrease of the crosslink density.

Strength of Geopolymer Cement Curing at Ambient Temperature by Non-Oven Curing Approaches: An Overview

Science.gov (United States)

Wattanachai, Pitiwat; Suwan, Teewara

2017-06-01

At the present day, a concept of environmentally friendly construction materials has been intensively studying to reduce the amount of releasing greenhouse gases. Geopolymer is one of the cementitious binders which can be produced by utilising pozzolanic wastes (e.g. fly ash or furnace slag) and also receiving much more attention as a low-CO2 emission material. However, to achieve excellent mechanical properties, heat curing process is needed to apply to geopolymer cement in a range of temperature around 40 to 90°C. To consume less oven-curing energy and be more convenience in practical work, the study on geopolymer curing at ambient temperature (around 20 to 25°C) is therefore widely investigated. In this paper, a core review of factors and approaches for non-oven curing geopolymer has been summarised. The performance, in term of strength, of each non-oven curing method, is also presented and analysed. The main aim of this review paper is to gather the latest study of ambient temperature curing geopolymer and to enlarge a feasibility of non-oven curing geopolymer development. Also, to extend the directions of research work, some approaches or techniques can be combined or applied to the specific properties for in-field applications and embankment stabilization by using soil-cement column.

A comparative evaluation of effect of modern-curing lights and curing modes on conventional and novel-resin monomers

Science.gov (United States)

Roy, Konda Karthik; Kumar, Kanumuru Pavan; John, Gijo; Sooraparaju, Sujatha Gopal; Nujella, Surya Kumari; Sowmya, Kyatham

2018-01-01

Aim: The aim of this study is to compare and to evaluate effect of curing light and curing modes on the nanohybrid composite resins with conventional Bis-GMA and novel tricyclodecane (TCD) monomers. Methodology: Two nanohybrid composites, IPS empress direct and charisma diamond were used in this study. Light-emitting diode (LED)-curing unit and quartz-tungsten-halogen (QTH)-curing unit which were operated into two different modes: continuous and soft start. Based on the composite resin, curing lights, and mode of curing used, the samples were divided into 8 groups. After polymerization, the samples were stored for 48 h in complete darkness at 37°C and 100% humidity. The Vickers hardness (VK) of the surface was determined with Vickers indenter by the application of 200 g for 15 s. Three VK readings were recorded for each sample surface both on top and bottom surfaces. For all the specimens, the three hardness values for each surface were averaged and reported as a single value. The mean VK and hardness ratio were calculated. The depth of cure was assessed based on the hardness ratio. Results: Comparison of mean hardness values and hardness ratios was done using ANOVA with post hoc Tukey's test. Conclusion: Both QTH- and LED-curing units had shown the adequate depth of cure. Soft-start-curing mode in both QTH- and LED-curing lights had effectively increased microhardness than the continuous mode of curing. TCD monomer had shown higher hardness values compared with conventional Bis-GMA-containing resin. PMID:29628651

An all-aromatic polypyridine: Monomer and polymer synthesis; Film formation and crosslinking; A candidate fuel cell membrane

Science.gov (United States)

Sikkema, Doetze J.; Versteegen, Ron M.; Pouderoijen, Maarten J.; Janssen, Henk M.; Boere, Ben; Brands, Ferry; Kemperman, GerJan; Rewinkel, Jos B. M.; Koeman, Menno

2018-03-01

2,6-di (3-pyridyl)phenol and the title polymer are synthesized at 1 kg scale. Polymer is processed and crosslinked without the introduction of non-aromatic moieties after shaping into membranes. Attractive proton conduction, at high temperature (140-180 °C: 300 mS cm-1) and at room temperature (60 mS cm-1) are recorded in the dry state (higher numbers at modest humidity) and excellent retention of properties after challenge by humidity (in contrast with state-of-the-art PBI membranes). Functional fuel cells are made and tested. In prolonged use the membrane is plasticized and this seems attributable to curing reversal at the hydrogen electrode. For high temperature fuel cell use, another curing scheme (again without the introduction of aliphatic character) must be found.

Dielectric Cure Monitoring of Thermosetting Matrix Composites

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyoung Geun [Agency for Defense Development, Daejeon (Korea, Republic of); Lee, Dae Gil [KAIST, Daejeon (Korea, Republic of)

2003-10-15

Cure monitoring can be used to improve the quality and productivity of thermosetting resin matrix composite products during their manufacturing process. In this work, the sensitivity of dielectrometry was improved by adequate separation the efforts of sensor and externals on the measured signal. A new algorithm to obtain the degree of cure during dielectric cure monitoring of glass/polyester and glass/epoxy composites was developed by employing a function of both temperature and dissipation factor, in which five cure monitoring parameters were used to calculate the degree of cure. The decreasing pattern of dissipation factor was compared with the relationships between the degree of cure and the resin viscosity. The developed algorithm might be employed for the in situ cure monitoring of thermosetting resin composites

Dielectric Cure Monitoring of Thermosetting Matrix Composites

International Nuclear Information System (INIS)

Kim, Hyoung Geun; Lee, Dae Gil

2003-01-01

Cure monitoring can be used to improve the quality and productivity of thermosetting resin matrix composite products during their manufacturing process. In this work, the sensitivity of dielectrometry was improved by adequate separation the efforts of sensor and externals on the measured signal. A new algorithm to obtain the degree of cure during dielectric cure monitoring of glass/polyester and glass/epoxy composites was developed by employing a function of both temperature and dissipation factor, in which five cure monitoring parameters were used to calculate the degree of cure. The decreasing pattern of dissipation factor was compared with the relationships between the degree of cure and the resin viscosity. The developed algorithm might be employed for the in situ cure monitoring of thermosetting resin composites

Effect of Amniotic Membrane Combined with Ciprofloxacin in Curing the Primary Stages of Pseudomonal Keratitis

Directory of Open Access Journals (Sweden)

Mohammad Kazem Sharifi Yazdi

2012-03-01

Full Text Available Background: Keratitis caused by Pseudomonas aeruginosa is often resulted in severe corneal ulcers and perforation, which leads to losses of vision. Human amniotic membrane (HAM forms the inner wall of the membranous sac which surrounds and protects the embryo during gestation. The purpose of this study was to evaluate the effectiveness of the amniotic membrane's healing in rabbits with pseudomonas keratitis.Methods: In total 14 rabbits divided in 2 groups of: 1 as Control and 2 as experimental amniotic membrane combined with ciprofloxacin. A 0.05 ml suspension of Pseudomonas aeruginosa ATCC 27853 was injected into rabbit’s corneal stroma, with no interference in control group. In the second group, the amniotic membrane in pieces of 1.5 × 1.5 cm transplanted to the entire corneal surface by eight interrupted 10.0 nylon sutures. In the first day ciprofloxacin drop was injected to the second group every 30 minutes and through second to seventh days every 2 hours. The results of perforation in cornea and the amount of infiltration were registered.Results: The results showed that amniotic membrane transplantation (AMT + ciprofloxacin group had 0% perforation and the control group 85.6%. Average infiltrations were 5 mm in AMT + ciprofloxacin groups and 23.75 mm in control.Conclusion: The use of amniotic membrane with ciprofloxacin was effective in prevention of cornea perforation and controlling the process of pseudomonal keratitis remission. The improvement of inflammation rapidly happened in ciprofloxacin + AMT group.

EB/UV curing market in Malaysia

Energy Technology Data Exchange (ETDEWEB)

Dahlan, Khairul Zaman; Nik Salleh, Nik Ghazali; Mahmood, Mohd Hilmi [Malaysian Inst. for Nuclear Technology Res. (MINT), Bangi (Malaysia)

1999-07-01

Radiation curing of coatings of wood based products is expanding and being used for curing of coatings of table tops, parquet, wood panel, furniture, curtain railing, etc. UV curing of over print varnish is still the main application of UV curing in printing industry. However, curing ofprinting ink has also been extended in the printing of CD and VCD in addition to other printing such as paper, magazine, label on bottles, metal-can, etc. In the electronic industry, the manufacturer of printed circuit board is still the main consumer of UV curable resins. On the other hand, low energy electron beam machine is used mainly for cross-linking of heat shrink films.

EB/UV curing market in Malaysia

International Nuclear Information System (INIS)

Khairul Zaman Dahlan; Nik Ghazali Nik Salleh; Mohd Hilmi Mahmood

1999-01-01

Radiation curing of coatings of wood based products is expanding and being used for curing of coatings of table tops, parquet, wood panel, furniture, curtain railing, etc. UV curing of over print varnish is still the main application of UV curing in printing industry. However, curing of printing ink has also been extended in the printing of CD and VCD in addition to other printing such as paper, magazine, label on bottles, metal-can, etc. In the electronic industry, the manufacturer of printed circuit board is still the main consumer of UV curable resins. On the other hand, low energy electron beam machine is used mainly for cross-linking of heat shrink films

Cure Behavior and Thermal Properties of Diepoxidized Cardanol Resin Cured by Electron Beam Process

International Nuclear Information System (INIS)

Cho, Donghwan; Cheon, Jinsil

2013-01-01

Thermal curing of epoxy resin requires high temperature, time-consuming process and the volatilization of hardener. It has known that electron beam curing of epoxy resin is a fast process and occurs at low or room temperature that help reduce residual mechanical stresses in thermosetting polymers. Diepoxidized cardanol (DEC) can be synthesized by an enzymatic method from cashew nut shell liquid (CNSL), that constitutes nearly one-third of the total nut weight. A large amount of CNSL can be formed as a byproduct of the mechanical processes used to render the cashew kerneledible and its total production approaches one million tons annually, which can be bio-degradable and replace the industrial thermosetting plastics. It is expected that DEC may be cured as in an epoxy resin, which was constituted on two epoxide group and long alkyl chain, and two-types of onium salts (cationic initiator) were used as a photo-initiator. The experimental variables of this study are type and concentration of photo-initiators and electron beam dosage. In this study, the effects of initiator type and concentration on the cure behavior and the thermal properties of DEC resin processed by using electron beam technology were studied using FT-IR, TGA, TMA, DSC, and DMA. Figure 1 is the FT-IR results, showing the change of chemical structure of pure DEC and electron beam cured DEC. The characteristic absorption peak of epoxide group appeared at 850cm -1 . The shape and the height were reduced when the sample was irradiated with electron beam. From this result, the epoxide groups is DEC were opened by electron beam and cured. After then, electron beam cured DEC was investigated the effect of forming 3-dimensional network

Cure Behavior and Thermal Properties of Diepoxidized Cardanol Resin Cured by Electron Beam Process

Energy Technology Data Exchange (ETDEWEB)

Cho, Donghwan; Cheon, Jinsil [Kumoh National Institute of Technology, Gumi (Korea, Republic of)

2013-07-01

Thermal curing of epoxy resin requires high temperature, time-consuming process and the volatilization of hardener. It has known that electron beam curing of epoxy resin is a fast process and occurs at low or room temperature that help reduce residual mechanical stresses in thermosetting polymers. Diepoxidized cardanol (DEC) can be synthesized by an enzymatic method from cashew nut shell liquid (CNSL), that constitutes nearly one-third of the total nut weight. A large amount of CNSL can be formed as a byproduct of the mechanical processes used to render the cashew kerneledible and its total production approaches one million tons annually, which can be bio-degradable and replace the industrial thermosetting plastics. It is expected that DEC may be cured as in an epoxy resin, which was constituted on two epoxide group and long alkyl chain, and two-types of onium salts (cationic initiator) were used as a photo-initiator. The experimental variables of this study are type and concentration of photo-initiators and electron beam dosage. In this study, the effects of initiator type and concentration on the cure behavior and the thermal properties of DEC resin processed by using electron beam technology were studied using FT-IR, TGA, TMA, DSC, and DMA. Figure 1 is the FT-IR results, showing the change of chemical structure of pure DEC and electron beam cured DEC. The characteristic absorption peak of epoxide group appeared at 850cm{sup -1}. The shape and the height were reduced when the sample was irradiated with electron beam. From this result, the epoxide groups is DEC were opened by electron beam and cured. After then, electron beam cured DEC was investigated the effect of forming 3-dimensional network.

7 CFR 30.12 - Fire-cure.

Science.gov (United States)

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Fire-cure. 30.12 Section 30.12 Agriculture Regulations... AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.12 Fire-cure. To cure tobacco under artificial atmospheric conditions by the use of open fires, the smoke and...

Radiation curing

International Nuclear Information System (INIS)

Wendrinsky, J.

1987-04-01

In the beginning of the seventies the two types of radiation sources applied in industrial processes, electron radiation and UV, had been given rather optimistic forecasts. While UV could succeed in the field of panel and film coating, electron radiation curing seems to gain success in quite new fields of manufacturing. The listing of the suggested applications of radiation curing and a comparison of both advantages and disadvantages of this technology are followed by a number of case studies emphasizing the features of these processes and giving some examplary calculations. The data used for the calculations should provide an easy calculation of individual manufacturing costs if special production parameters, investment or energy costs are employed. (Author)

Accounting for Cured Patients in Cost-Effectiveness Analysis.

Science.gov (United States)

Othus, Megan; Bansal, Aasthaa; Koepl, Lisel; Wagner, Samuel; Ramsey, Scott

2017-04-01

Economic evaluations often measure an intervention effect with mean overall survival (OS). Emerging types of cancer treatments offer the possibility of being "cured" in that patients can become long-term survivors whose risk of death is the same as that of a disease-free person. Describing cured and noncured patients with one shared mean value may provide a biased assessment of a therapy with a cured proportion. The purpose of this article is to explain how to incorporate the heterogeneity from cured patients into health economic evaluation. We analyzed clinical trial data from patients with advanced melanoma treated with ipilimumab (Ipi; n = 137) versus glycoprotein 100 (gp100; n = 136) with statistical methodology for mixture cure models. Both cured and noncured patients were subject to background mortality not related to cancer. When ignoring cured proportions, we found that patients treated with Ipi had an estimated mean OS that was 8 months longer than that of patients treated with gp100. Cure model analysis showed that the cured proportion drove this difference, with 21% cured on Ipi versus 6% cured on gp100. The mean OS among the noncured cohort patients was 10 and 9 months with Ipi and gp100, respectively. The mean OS among cured patients was 26 years on both arms. When ignoring cured proportions, we found that the incremental cost-effectiveness ratio (ICER) when comparing Ipi with gp100 was $324,000/quality-adjusted life-year (QALY) (95% confidence interval $254,000-$600,000). With a mixture cure model, the ICER when comparing Ipi with gp100 was $113,000/QALY (95% confidence interval $101,000-$154,000). This analysis supports using cure modeling in health economic evaluation in advanced melanoma. When a proportion of patients may be long-term survivors, using cure models may reduce bias in OS estimates and provide more accurate estimates of health economic measures, including QALYs and ICERs. Copyright © 2017 International Society for Pharmacoeconomics

Novel techniques for concrete curing

DEFF Research Database (Denmark)

Kovler, Konstantin; Jensen, Ole Mejlhede

2005-01-01

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

C-CURE

Data.gov (United States)

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

Gamma and electron beam curing of polymers and composites

International Nuclear Information System (INIS)

Saunders, C.B.; Dickson, L.W.; Singh, A.

1987-01-01

Radiation polymerization has helped us understand polymer chemistry, and is also playing an increasing role in the field of practical applications. Radiation curing has a present market share of about 5% of the total market for curing of polymers and composites and the annual growth rate of the radiation curing market is ≥20% per year. Advantages of radiation curing over thermal or chemical curing methods include: improved control of the curing rate, reduced curing times, curing at ambient temperatures, curing without the need for chemical initiators, and complete (100%) curing with minimal toxic chemical emissions. Radiation treatment may also be used to effect crosslinking and grafting of polymer and composite materials. The major advantage in these cases is the ability to process products in their final shape. Cable insulation, automotive and aircraft components, and improved construction materials are some of the current and near-future industrial applications of radiation curing and crosslinking. 19 refs

Cure Schedule for Stycast 2651/Catalyst 9.

Energy Technology Data Exchange (ETDEWEB)

Kropka, Jamie Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); McCoy, John D. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States)

2017-11-01

The Emerson & Cuming technical data sheet (TDS) for Stycast 2651/Catalyst 9 lists three alternate cure schedules for the material, each of which would result in a different state of reaction and different material properties. Here, a cure schedule that attains full reaction of the material is defined. The use of this cure schedule will eliminate variance in material properties due to changes in the cure state of the material, and the cure schedule will serve as the method to make material prior to characterizing properties. The following recommendation uses one of the schedules within the TDS and adds a “post cure” to obtain full reaction.

UV/EB curing market in Indonesia

International Nuclear Information System (INIS)

Hilmy, N.; Danu, S.

1999-01-01

The most application of UV curing of surface coating in Indonesia are on fancy plywood, furniture and wood flooring industry. Other application are on papers, printing ink/labelling, printed circuit board/PCB and dental materials. At present, application of EB curing coating is still in a pilot plant scale due to the high cost of production. Limited number of application of EB curing by using low energy electron beam machine are on wood panels, ceramics and marbles. This paper describes the market and the problem faced by the largest user of radiation curing systems such as the secondary process plywood, furniture and paper industries

Radiation curing of polymers II

International Nuclear Information System (INIS)

Randell, D.R.

1991-01-01

During the last decade radiation cured polymers have continued to grow in importance not only by expansion within existing coatings applications but also by extension into new fields of application such as ceramics, ink-jet inks and fibres. To provide a further update on the rapidly growing science and technology of radiation curing the Third International Symposium was held. Apart from providing an update on the application, chemistry and control aspects of the radiation curing the aim of the meeting was also to provide the newcomer with a basic insight into radiation curing applications. Accordingly the proceedings contained in this special publication which follow closely the format of the meeting, has five sections covering the background/trends, applications, initiator chemistry, substrate chemistry and analytical, physical chemical and health and safety aspects. There are twenty-five papers all told, three of which are indexed separately. (Author)

Curing reaction of bisphenol-A based benzoxazine with cyanate ester resin and the properties of the cured thermosetting resin

Directory of Open Access Journals (Sweden)

H. Kimura

2011-12-01

Full Text Available Curing reaction of bisphenol-A based benzoxazine with cyanate ester resin and the properties of the cured thermosetting resin were investigated. The cure behavior of benzoxazine with cyanate ester resin was monitored by model reaction using nuclear magnetic resonance (NMR. As a result of the model reaction, the ring opening reaction of benzoxazine ring and thermal self-cyclotrimerization of cyanate ester group occurred, and then the phenolic hydoroxyl group generated by the ring opening reaction of benzoxazine ring co-reacted with cyanate ester group. The properties of the cured thermosetting resin were estimated by mechanical properties, electrical resistivity, water resistance and heat resistance. The cured thermosetting resin from benzoxazine and cyanate ester resin showed good heat resistance, high electrical resistivity and high water resistance, compared with the cured thermosetting resin from benzoxazine and epoxy resin.

Effects of Chemical Curing Temperature and Time on the Properties of Liquefied Wood based As-cured Precursors and Carbon Fibers

Directory of Open Access Journals (Sweden)

Junbo Shang

2015-09-01

Full Text Available Liquefied wood based as-cured precursors and carbon fibers prepared by different chemical curing processes were carried out to investigate the effects of curing temperature and time on the thermostability and microstructure of liquefied wood based precursors, the tensile strength of carbon fibers as well. The primary fibers can be converted into precursors with high performance by directly heating at target curing temperature. With the temperature and duration increasing, the numbers of methylene bonds in precursors increased, resulting in the enhancement of cross-linkages among molecular chains and then the improvement of thermostability of precursors. Carbon fibers prepared from as-cured precursors (curing temperature 95 oC, curing time 3h had the minimum value of the average interlayer spacing (d002, it also showed the highest tensile strength, almost 800 MPa, which can be classified as fibers of general grade.

The irradiation curing of coatings

International Nuclear Information System (INIS)

Autio, T.

1974-01-01

The electron beam irradiation curing of coatings has been technically feasible for over a decade. A brief description of the process is presented. The progress in this field has been astonishingly slow in comparison with the use of UV lamps as radiation source. The primary reason for this has been the great advantage in terms of capital cost of the UV curing lines and their ready adaptability to low or high production rates. A literature survey is given concerning basic and applied research in the electron curing area, patents, economics and existing installations around the world. (author)

Study on the heat-resistant EB curing composites

International Nuclear Information System (INIS)

Bao Jianwen; Li Yang; Li Fengmei

2000-01-01

There are many advantages in the EB-curing process of composites. Heat-resistant EB-curing composites could substitute for polyimide composites used in aeronautical engine. The effects of catalyst and dose on the cured resin were investigated. The heat-resistance of the resin cured by EB was evaluated by dynamic mechanical thermal analysis (DMTA). The experiment result shows that the mechanical property of the composites cured by EB could meet the needs of the aeronautical engine in 250degC. (author)

A Stability Study of Alkali Doped PBI Membranes for Alkaline Electrolyzer Cells

DEFF Research Database (Denmark)

Jensen, Jens Oluf; Aili, David; Hansen, Martin Kalmar

2014-01-01

conductivity was similar to a commercial Zirfon membrane and suitable for a water electrolyzer. Some chemical degradation was seen during the aging period, but the crosslinked and the cured materials were both integral after 176 days of aging. A simplified electrolyzer test cell was operated successfully....

An emerging alternative to thermal curing: Electron curing of fiber-reinforced composites

International Nuclear Information System (INIS)

Singh, A.; Saunders, C.B.; Lopata, V.J.; Kremers, W.; Chung, M.

1995-01-01

Electron curing of fiber-reinforced composites to produce materials with good mechanical properties has been demonstrated by the authors' work, and by Aerospatiale. The attractions of this technology are the technical and processing advantages offered over thermal curing, and the projected cost benefits. Though the work so far has focused on the higher value composites for the aircraft and aerospace industries, the technology can also be used to produce composites for the higher volume industries, such as transportation and automotive

Radiation cured acrylonitrile--butadiene elastomers

International Nuclear Information System (INIS)

Eldred, R.J.

1976-01-01

In accordance with a preferred embodiment of this invention, the ultimate elongation of an electron beam radiation cured acrylonitrile-butadiene elastomer is significantly increased by the incorporation of a preferred noncrosslinking monomer, glycidyl methacrylate, in combination with the conventional crosslinking monomer, trimethylolpropanetrimethacrylate, prior to the radiation curing process

Techniques for internal water curing of concrete

DEFF Research Database (Denmark)

Jensen, Ole Mejlhede; Pietro, Lura

2003-01-01

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

A cure for HIV: is it in sight?

Science.gov (United States)

Pace, Matthew; Frater, John

2014-07-01

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

Effect of various infection-control methods for light-cure units on the cure of composite resins.

Science.gov (United States)

Chong, S L; Lam, Y K; Lee, F K; Ramalingam, L; Yeo, A C; Lim, C C

1998-01-01

This study (1) compared the curing-light intensity with various barrier infection-control methods used to prevent cross contamination, (2) compared the Knoop hardness value of cured composite resin when various barrier control methods were used, and (3) correlated the hardness of the composite resin with the light-intensity output when different infection-control methods were used. The light-cure unit tips were covered with barriers, such as cellophane wrap, plastic gloves, Steri-shields, and finger cots. The control group had no barrier. Composite resins were then cured for each of the five groups, and their Knoop hardness values recorded. The results showed that there was significant statistical difference in the light-intensity output among the five groups. However, there was no significant statistical difference in the Knoop hardness values among any of the groups. There was also no correlation between the Knoop hardness value of the composite resin with the light-intensity output and the different infection-control methods. Therefore, any of the five infection-control methods could be used as barriers for preventing cross-contamination of the light-cure unit tip, for the light-intensity output for all five groups exceeded the recommended value of 300 W/m2. However, to allow a greater margin of error in clinical situations, the authors recommend that the plastic glove or the cellophane wrap be used to wrap the light-cure tip, since these barriers allowed the highest light-intensity output.

Mechanical properties of self-curing concrete (SCUC

Directory of Open Access Journals (Sweden)

Magda I. Mousa

2015-12-01

Full Text Available The mechanical properties of concrete containing self-curing agents are investigated in this paper. In this study, two materials were selected as self-curing agents with different amounts, and the addition of silica fume was studied. The self-curing agents were, pre-soaked lightweight aggregate (Leca; 0.0%, 10%, 15%, and 20% of volume of sand; or polyethylene-glycol (Ch.; 1%, 2%, and 3% by weight of cement. To carry out this study the cement content of 300, 400, 500 kg/m3, water/cement ratio of 0.5, 0.4, 0.3 and 0.0%, 15% silica fume of weight of cement as an additive were used in concrete mixes. The mechanical properties were evaluated while the concrete specimens were subjected to air curing regime (in the laboratory environment with 25 °C, 65% R.H. during the experiment. The results show that, the use of self-curing agents in concrete effectively improved the mechanical properties. The concrete used polyethylene-glycol as self-curing agent, attained higher values of mechanical properties than concrete with saturated Leca. In all cases, either 2% Ch. or 15% Leca was the optimum ratio compared with the other ratios. Higher cement content and/or lower water/cement ratio lead(s to more efficient performance of self-curing agents in concrete. Incorporation of silica fume into self-curing concrete mixture enhanced all mechanical properties, not only due to its pozzolanic reaction, but also due to its ability to retain water inside concrete.

Radiation curing - twenty five years on

International Nuclear Information System (INIS)

Garnett, J.L.

1995-01-01

Progress in UV/EB curing during the past twenty five years is briefly reviewed. During this time developments in unique polymer chemistry, novel equipment design and the introduction of relevant educational programmes has enabled radiation curing to become an established technology with specific strengths in certain industries. Possible reasons for the emergence of the technology in these niche markets are discussed. Despite the worldwide recession, radiation curing is shown to be expanding at 5% per annum with the prospect of higher growth with improving economic conditions. (Author)

Silicone rubber curing by high intensity infrared radiation

International Nuclear Information System (INIS)

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

1994-01-01

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

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

Science.gov (United States)

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

2011-12-01

To evaluate the microtensile bond strength (μTBS) and acid-base resistant zone (ABRZ) of two dualcuring core systems to dentin using four curing modes. Sixty-four caries-free human molars were randomly divided into two groups according to two dual-curing resin core systems: (1) Clearfil DC Core Automix; (2) Estelite Core Quick. For each core system, four different curing modes were applied to the adhesive and core resin: (1) dual-cured and dual-cured (DD); (2) chemically cured and dual-cured (CD); (3) dual-cured and chemically cured (DC); (4) chemically cured and chemically cured (CC). The specimens were sectioned into sticks (n = 20 for each group) for the microtensile bond test. μTBS data were analyzed using two-way ANOVA and the Dunnett T3 test. Failure patterns were examined with scanning electron microscopy (SEM) to determine the proportion of each mode. Dentin sandwiches were produced and subjected to an acid-base challenge. After argon-ion etching, the ultrastructure of ABRZ was observed using SEM. For Clearfil DC Core Automix, the μTBS values in MPa were as follows: DD: 29.1 ± 5.4, CD: 21.6 ± 5.6, DC: 17.9 ± 2.8, CC: 11.5 ± 3.2. For Estelite Core Quick, they were: DD: 48.9 ±5.7, CD: 20.5 ± 4.7, DC: 41.4 ± 8.3, CC: 19.1 ± 6.0. The bond strength was affected by both material and curing mode, and the interaction of the two factors was significant (p < 0.001). Within both systems, there were significant differences among groups, and the DD group showed the highest μTBS (p < 0.05). ABRZ morphology was not affected by curing mode, but it was highly adhesive-material dependent. The curing mode of dual-curing core systems affects bond strength to dentin, but has no significant effect on the formation of ABRZ.

Experimental Study on the Curing Effect of Dredged Sediments with Three Types of Curing Agents

Directory of Open Access Journals (Sweden)

Yan Lei-Ming

2016-01-01

Full Text Available Sediment solidification technology is widely used to dispose dredged sediment, three types of curing agents were used in this study to solidified the dredged sediment from shallows in Nantong with three types of curing agents: JY, ZL and FJ. The results showed that the optimal additive amounts of these three curing agents were 140g JY, 16g ZL, 2.0g FJ per 1000g of the dredged sediment respectively, their 28d USC were up to 2.48 MPa, 2.96 MPa and 3.00 MPa. JY has obvious early strength effect, which of FJ is not that obvious, but the later-stage strength of sediment solidified by FJ are relatively higher.

Effect of curing methods, packaging and gamma irradiation on the weight loss and dry matter percent of garlic during curing and storage

International Nuclear Information System (INIS)

Mahmoud, A.A.; El-Oksh, I.I.; Farag, S.E.A.

1988-01-01

The Egyptian garlic plants, showed higher percent of weight loss at 17 or 27 days from curing compared to those of Chinese plants. The curing period of 17 days seemed satisfactory for the Egyptian cultivar, whereas, 27 days seemed to be enough for the Chinese garlic. No significant differences were observed between common and shaded curing methods in weight loss per cent. The Chinese garlic contained higher dry matter percentage than those of the Egyptian cultivar. Shaded cured plants of the two cultivars contained higher dry matter percent than those subjected to the common curing methods. Irradiation of garlic bulbs, shaded curing method and sack packaging decreased, in general the weight loss during storage in comparison with other treatments

Proceedings of workshop on surface finishing by radiation curing technology: radiation curing for better finishing

International Nuclear Information System (INIS)

1993-01-01

This book compiled the paper presented at this workshop. The papers discussed are 1. Introduction to radiation curing, 2. Radiation sources -ultraviolet and electron beams, 3. UV/EB curing of surface coating - wood and nonwood substrates, 4. Development of EPOLA (epoxidised palm oil products acrylate) and its application, 5. Development of radiation-curable resin based natural rubber

Proceedings of workshop on surface finishing by radiation curing technology: radiation curing for better finishing

Energy Technology Data Exchange (ETDEWEB)

NONE

1994-12-31

This book compiled the paper presented at this workshop. The papers discussed are 1. Introduction to radiation curing, 2. Radiation sources -ultraviolet and electron beams, 3. UV/EB curing of surface coating - wood and nonwood substrates, 4. Development of EPOLA (epoxidised palm oil products acrylate) and its application, 5. Development of radiation-curable resin based natural rubber.

New insight-guided approaches to detect, cure, prevent and eliminate malaria.

Science.gov (United States)

Kumar, Sushil; Kumari, Renu; Pandey, Richa

2015-05-01

New challenges posed by the development of resistance against artemisinin-based combination therapies (ACTs) as well as previous first-line therapies, and the continuing absence of vaccine, have given impetus to research in all areas of malaria control. This review portrays the ongoing progress in several directions of malaria research. The variants of RTS,S and apical membrane antigen 1 (AMA1) are being developed and test adapted as multicomponent and multistage malaria control vaccines, while many other vaccine candidates and methodologies to produce antigens are under experimentation. To track and prevent the spread of artemisinin resistance from Southeast Asia to other parts of the world, rolling circle-enhanced enzyme activity detection (REEAD), a time- and cost-effective malaria diagnosis in field conditions, and a DNA marker associated with artemisinin resistance have become available. Novel mosquito repellents and mosquito trapping and killing techniques much more effective than the prevalent ones are undergoing field testing. Mosquito lines stably infected with their symbiotic wild-type or genetically engineered bacteria that kill sympatric malaria parasites are being constructed and field tested for stopping malaria transmission. A complementary approach being pursued is the addition of ivermectin-like drug molecules to ACTs to cure malaria and kill mosquitoes. Experiments are in progress to eradicate malaria mosquito by making it genetically male sterile. High-throughput screening procedures are being developed and used to discover molecules that possess long in vivo half life and are active against liver and blood stages for the fast cure of malaria symptoms caused by simple or relapsing and drug-sensitive and drug-resistant types of varied malaria parasites, can stop gametocytogenesis and sporogony and could be given in one dose. Target-based antimalarial drug designing has begun. Some of the putative next-generation antimalarials that possess in their

Physical properties of self-curing concrete (SCUC

Directory of Open Access Journals (Sweden)

Magda I. Mousa

2015-08-01

The results show that the use of self-curing agent (Ch. in concrete effectively improves the physical properties compared with conventional concrete. On the other hand, up to 15% saturated leca was effective while 20% saturated leca was effective for permeability and mass loss but adversely affects the sorptivity and volumetric water absorption. Self-curing agent Ch. was more effective than self-curing agent leca. In all cases, both 2% Ch. and 15% leca were the optimum values. Higher cement content and/or lower water–cement ratio leads to more effective results of self-curing agents in concrete. Incorporation of silica fume into concrete mixtures enhances all physical properties.

Comparing depth-dependent curing radiant exposure and time of curing of regular and flow bulk-fill composites

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Jose Augusto RODRIGUES

2017-08-01

Full Text Available Abstract The effect of restoration depth on the curing time of a conventional and two bulk-fill composite resins by measuring microhardness and the respective radiosity of the bottom surface of the specimen was investigated. 1-, 3- and 5-mm thick washers were filled with Surefil SDR Flow–U (SDR, Tetric EvoCeram Bulk Fill-IVA (TEC or Esthet-X HD–B1 (EHD, and cured with Bluephase® G2 for 40s. Additional 1-mm washers were filled with SDR, TEC or EHD, placed above the light sensor of MARC®, stacked with pre-cured 1-, 3- or 5-mm washer of respective material, and cured for 2.5~60s to mimic 2-, 4- and 6-mm thick composite curing. The sensor measured the radiosity (EB at the bottom of specimen stacks. Vickers hardness (VH was measured immediately at 5 locations with triplicate specimens. Nonlinear regression of VH vs EB by VH=α[1-exp(-EB/β] with all thickness shows that the values of α, maximum hardness, are 21.6±1.0 kg/mm2 for SDR, 38.3±0.6 kg/mm2 for TEC and 45.3±2.6 kg/mm2 for EHD, and the values of β, rate parameter, are 0.40±0.06 J/cm2 for SDR, 0.77±0.04 J/cm2 for TEC and 0.58±0.09 J/cm2 for EHD. The radiosity of the bottom surface was calculated when the bottom surface of each material attained 80% of α of each material. The curing times for each material are in agreement with manufacturer recommendation for thickness. It is possible to estimate time needed to cure composite resin of known depth adequately by the radiosity and microhardness of the bottom surface.

Comparing depth-dependent curing radiant exposure and time of curing of regular and flow bulk-fill composites.

Science.gov (United States)

Rodrigues, Jose Augusto; Tenorio, Ilana Pais; Mello, Ginger Baranhuk Rabello de; Reis, André Figueiredo; Shen, Chiayi; Roulet, Jean-François

2017-08-21

The effect of restoration depth on the curing time of a conventional and two bulk-fill composite resins by measuring microhardness and the respective radiosity of the bottom surface of the specimen was investigated. 1-, 3- and 5-mm thick washers were filled with Surefil SDR Flow-U (SDR), Tetric EvoCeram Bulk Fill-IVA (TEC) or Esthet-X HD-B1 (EHD), and cured with Bluephase® G2 for 40s. Additional 1-mm washers were filled with SDR, TEC or EHD, placed above the light sensor of MARC®, stacked with pre-cured 1-, 3- or 5-mm washer of respective material, and cured for 2.5~60s to mimic 2-, 4- and 6-mm thick composite curing. The sensor measured the radiosity (EB) at the bottom of specimen stacks. Vickers hardness (VH) was measured immediately at 5 locations with triplicate specimens. Nonlinear regression of VH vs EB by VH=α[1-exp(-EB/β)] with all thickness shows that the values of α, maximum hardness, are 21.6±1.0 kg/mm2 for SDR, 38.3±0.6 kg/mm2 for TEC and 45.3±2.6 kg/mm2 for EHD, and the values of β, rate parameter, are 0.40±0.06 J/cm2 for SDR, 0.77±0.04 J/cm2 for TEC and 0.58±0.09 J/cm2 for EHD. The radiosity of the bottom surface was calculated when the bottom surface of each material attained 80% of α of each material. The curing times for each material are in agreement with manufacturer recommendation for thickness. It is possible to estimate time needed to cure composite resin of known depth adequately by the radiosity and microhardness of the bottom surface.

Electron beam curing of coating

International Nuclear Information System (INIS)

Fujioka, S.; Fujikawa, Z.

1974-01-01

Electron beam curing (EBC) method, by which hardened coating film is obtained by polymerizing and cross-linking paint with electron beam, has finally reached industrialized stage. While about seven items such as short curing time, high efficiency of energy consumption, and homogeneous curing are enumerated as the advantages of EBC method, it has limitations of the isolation requirement from air needing the injection of inert gas, and considerable amount of initial investment. In the electron accelerators employed in EBC method, the accelerating voltage is 250 to 750 kV, and the tube current is several tens of mA to 200 mA. As an example of EBC applications, EBC ''Erio'' steel sheet was developed by the cooperative research of Nippon Steel Corp., Dai-Nippon Printing Co. and Toray Industries, Inc. It is a high-class pre-coated metal product made from galvanized steel sheets, and the flat sheets with cured coating are sold, and final products are fabricated by being worked in various shapes in users. It seems necessary to develop the paint which enables to raise added value by adopting the EBC method. (Wakatsuki, Y.)

Accelerated production of dry cured hams.

Science.gov (United States)

Marriott, N G; Graham, P P; Shaffer, C K; Phelps, S K

1987-01-01

Ten uncured legs from the right side of the sampled pork carcasses (Study A) were vacuum tumbled with the cure adjuncts for 30 min (T) and 10 counterparts from the left side were tumbled 30 min, rested 30 min and tumbled an additional 30 min (TRT). Evaluations were conducted at 40 and 70 days after cure application for color, taste attributes, percentage moisture, percentage salt and NO(3)(-) and NO(2)(-) content. Study B was the same except that 18 legs were boned, tumbled and cured for 40, 56 and 70 days. The TRT samples (Study A) at 40 days sustained less color fading (P 0.05) existed among the uncooked hams. Increased cure time enhanced moisture loss and salt content (Study A) and color retention during cookery (Study B). The TRT samples had increased moisture loss and salt content (Study A). Copyright © 1987. Published by Elsevier Ltd.

Rubber curing chemistry governing the orientation of layered silicate

Directory of Open Access Journals (Sweden)

2007-11-01

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

Curing kinetics of alkyd/melamine resin mixtures

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Jovičić Mirjana C.

2009-01-01

Full Text Available Alkyd resins are the most popular and useful synthetic resins applied as the binder in protective coatings. Frequently they are not used alone but are modified with other synthetic resins in the manufacture of the coatings. An alkyd/melamine resin mixture is the usual composition for the preparation of coating called 'baking enamel' and it is cured through functional groups of resins at high temperatures. In this paper, curing kinetics of alkyd resins based on castor oil and dehydrated castor oil with melamine resin, has been studied by DSC method with programmed heating and in isothermal mode. The results determined from dynamic DSC curves were mathematically transformed using the Ozawa isoconversional method for obtaining the isothermal data. These results, degree of curing versus time, are in good agreement with those determined by the isothermal DSC experiments. By applying the Ozawa method it is possible to calculate the isothermal kinetic parameters for the alkyd/melamine resin mixtures curing using only calorimetric data obtained by dynamic DSC runs. Depending on the alkyd resin type and ratio in mixtures the values of activation energies of curing process of resin mixtures are from 51.3 to 114 kJ mol-1. The rate constant of curing increases with increasing the content of melamine resin in the mixture and with curing temperature. The reaction order varies from 1.12 to 1.37 for alkyd based on dehydrated castor oil/melamine resin mixtures and from 1.74 to 2.03 for mixtures with alkyd based on castor oil. Based on the results obtained, we propose that dehydrated castor oil alkyd/melamine resin mixtures can be used in practice (curing temperatures from 120 to 160°C.

Monitoring Prepregs As They Cure

Science.gov (United States)

Young, P. R.; Gleason, J. R.; Chang, A. C.

1986-01-01

Quality IR spectra obtained in dynamic heating environment. New technique obtains quality infrared spectra on graphite-fiber-reinforced, polymeric-matrix-resin prepregs as they cure. Technique resulted from modification of diffuse reflectance/Fourier transform infrared (DR/FTIR) technique previously used to analyze environmentally exposed cured graphite composites. Technique contribute to better understanding of prepreg chemistry/temperature relationships and development of more efficient processing cycles for advanced materials.

Catalyzed Synthesis and Characterization of a Novel Lignin-Based Curing Agent for the Curing of High-Performance Epoxy Resin

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Saeid Nikafshar

2017-07-01

Full Text Available In this study, lignin, an aromatic compound from the forestry industry, was used as a renewable material to synthesize a new aromatic amine curing agent for epoxy resin. Firstly, lignin was separated from black liquor and hydroxyl groups were converted to tosyl groups as leaving groups. Then, primary amination was conducted using an ammonia solution at high pressure and temperature, in the presence of a nano-alumina-based catalyst. The structure of the nanocatalyst was confirmed by FT-IR, ICP, SEM, and XPS analyses. According to the FT-IR spectra, a demethylation reaction, the substitution of hydroxyl groups with tosyl groups, and then an amination reaction were successfully performed on lignin, which was further confirmed by the 13C NMR and CHNS analyses. The active hydrogen equivalent of aminated lignin was determined and three samples with 9.9 wt %, 12.9 wt %, and 15.9 wt % of aminated lignin, as curing agents, were prepared for curing the diglycidyl ether of bisphenol A (DGEBA. The thermal characteristics of the curing process of these epoxy samples were determined by DSC and TGA analyses. Moreover, the mechanical performance of the cured epoxy systems, e.g., the tensile strength and Izod impact strength, were measured, showing that in the presence of 12.9 wt % aminated lignin, the mechanical properties of the aminated lignin-epoxy system exhibited the best performance, which was competitive, compared to the epoxy systems cured by commercial aromatic curing agents.

Translating Genomic Discoveries to Cure Ultrahypermutant ...

International Development Research Centre (IDRC) Digital Library (Canada)

Translating Genomic Discoveries to Cure Ultrahypermutant Mismatch Repair Deficient Brain Tumours. Malignant brain tumours are the most common cause of death among children with cancer, but there is no known cure. This project will advance research in this important field. Inherited mutations and childhood cancer.

Influence of curing time, overlay material and thickness on three light-curing composites used for luting indirect composite restorations.

Science.gov (United States)

D'Arcangelo, Camillo; De Angelis, Francesco; Vadini, Mirco; Carluccio, Fabio; Vitalone, Laura Merla; D'Amario, Maurizio

2012-08-01

To assess the microhardness of three resin composites employed in the adhesive luting of indirect composite restorations and examine the influence of the overlay material and thickness as well as the curing time on polymerization rate. Three commercially available resin composites were selected: Enamel Plus HRI (Micerium) (ENA), Saremco ELS (Saremco Dental) (SAR), Esthet-X HD (Dentsply/DeTrey) (EST-X). Post-polymerized cylinders of 6 different thicknesses were produced and used as overlays: 2 mm, 3 mm, 3.5 mm, 4 mm, 5 mm, and 6 mm. Two-mm-thick disks were produced and employed as underlays. A standardized amount of composite paste was placed between the underlay and the overlay surfaces which were maintained at a fixed distance of 0.5 mm. Light curing of the luting composite layer was performed through the overlays for 40, 80, or 120 s. For each specimen, the composite to be cured, the cured overlay, and the underlay were made out of the same batch of resin composite. All specimens were assigned to three experimental groups on the basis of the resin composite used, and to subgroups on the basis of the overlay thickness and the curing time, resulting in 54 experimental subgroups (n = 5). Forty-five additional specimens, 15 for each material under investigation, were produced and subjected to 40, 80, or 120 s of light curing using a microscope glass as an overlay; they were assigned to 9 control subgroups (n = 5). Three Vicker's hardness (VH) indentations were performed on each specimen. Means and standard deviations were calculated. Data were statistically analyzed using 3-way ANOVA. Within the same material, VH values lower than 55% of control were not considered acceptable. The used material, the overlay thickness, and the curing time significantly influenced VH values. In the ENA group, acceptable hardness values were achieved with 3.5-mm or thinner overlays after 120 or 80 s curing time (VH 41.75 and 39.32, respectively), and with 2-mm overlays after 40 s (VH 54

Radiation cured coating containing glitter particles and process therefor

International Nuclear Information System (INIS)

Sachs, P.R.; Sears, J.W.

1992-01-01

Radiation curable coatings for use on a variety of substrates and curable by exposure to ionizing irradiation of ultraviolet light are well known. The use of urethane type coatings cured with ultraviolet light to provide protective wear layers for wall or floor tile is for instance described in U.S. Pat. No. 4,180,615. U.S. Pat. No. 3,918,393 describes a method for obtaining a non-glossy coating on various substrates by curing radiation sensitive material with ionizing irradiation or ultraviolet light in two stages. In this process the coating is partially cured in an oxygen-containing atmosphere and the curing is completed in an inert atmosphere. U.S. Pat. No. 4,122,225 discloses a method and apparatus for coating tile which involves the application of one coat of radiation curable material to an entire substrate followed by partial curing and the subsequent application and curing of a second coat or radiation curable material only on high areas of the substrate which are subject to greater than average wear. Use of pigment in radiation cured coatings on products such as floor covering which are subject to wear during use has presented substantial difficulties. Incorporation of pigment, especially enough pigment to make the coating opaque, makes the coating hard to cure and substantially reduces the thicknesses of coating which can be cured relative to a clear coating cured under the same conditions

Accelerated Cure Project for Multiple Sclerosis

Science.gov (United States)

... questions and enable an era of optimized MS treatment. Read more... The Accelerated Cure Project for MS is a non-profit, 501(c)(3) tax-exempt organization whose mission is to accelerate efforts toward a cure for multiple sclerosis by rapidly advancing research that determines its causes ...

7 CFR 29.3002 - Air-cured.

Science.gov (United States)

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Air-cured. 29.3002 Section 29.3002 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...-cured tobacco should not carry the odor of smoke or fumes resulting from the application of artificial...

Microwave and thermal curing of an epoxy resin for microelectronic applications

Energy Technology Data Exchange (ETDEWEB)

Johnston, K. [Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Pavuluri, S.K.; Leonard, M.T.; Desmulliez, M.P.Y. [MIcroSystems Engineering Centre (MISEC), Institute of Signals, Sensors and Systems, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Arrighi, V., E-mail: v.arrighi@hw.ac.uk [Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom)

2015-09-20

Graphical abstract: - Highlights: • Thermal and microwave curing of a commercial epoxy resin EO1080 are compared. • Microwave curing increases cure rate and does not adversely affect properties. • The curing of EO1080 is generally autocatalytic but deviates at high conversion. • Microwave radiation has a more complex effect on curing kinetics. - Abstract: Microwave curing of thermosetting polymers has a number of advantages to natural or thermal oven curing and is considered a cost-effective alternative. Here we present a detailed study of a commercially available epoxy resin, EO1080. Samples that are thermally cured are compared to curing using a recently developed modular microwave processing system. For commercial purposes it is crucial to demonstrate that microwave curing does not adversely affect the thermal and chemical properties of the material. Therefore, the kinetics of cure and various post cure properties of the resin are investigated. Attenuated Total Reflectance Fourier-Transform Infrared (ATR-FTIR) analysis shows no significant difference between the conventionally and microwave cured samples. Differential scanning calorimetry (DSC) is used to monitor the kinetics of the curing reaction, as well as determine the thermal and ageing properties of the material. As expected, the rate of curing is higher when using microwave energy and we attempt to quantify differences compared to conventional thermal curing. No change in glass transition temperature (T{sub g}) is observed. For the first time, enthalpy relaxation measurements performed on conventional and microwave cured samples are reported and these indicate similar ageing properties at any given temperature under T{sub g}.

Microwave and thermal curing of an epoxy resin for microelectronic applications

International Nuclear Information System (INIS)

Johnston, K.; Pavuluri, S.K.; Leonard, M.T.; Desmulliez, M.P.Y.; Arrighi, V.

2015-01-01

Graphical abstract: - Highlights: • Thermal and microwave curing of a commercial epoxy resin EO1080 are compared. • Microwave curing increases cure rate and does not adversely affect properties. • The curing of EO1080 is generally autocatalytic but deviates at high conversion. • Microwave radiation has a more complex effect on curing kinetics. - Abstract: Microwave curing of thermosetting polymers has a number of advantages to natural or thermal oven curing and is considered a cost-effective alternative. Here we present a detailed study of a commercially available epoxy resin, EO1080. Samples that are thermally cured are compared to curing using a recently developed modular microwave processing system. For commercial purposes it is crucial to demonstrate that microwave curing does not adversely affect the thermal and chemical properties of the material. Therefore, the kinetics of cure and various post cure properties of the resin are investigated. Attenuated Total Reflectance Fourier-Transform Infrared (ATR-FTIR) analysis shows no significant difference between the conventionally and microwave cured samples. Differential scanning calorimetry (DSC) is used to monitor the kinetics of the curing reaction, as well as determine the thermal and ageing properties of the material. As expected, the rate of curing is higher when using microwave energy and we attempt to quantify differences compared to conventional thermal curing. No change in glass transition temperature (T g ) is observed. For the first time, enthalpy relaxation measurements performed on conventional and microwave cured samples are reported and these indicate similar ageing properties at any given temperature under T g

Financing cures in the United States.

Science.gov (United States)

Basu, Anirban

2015-02-01

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

Photoacoustic monitoring of inhomogeneous curing processes in polystyrene emulsions

International Nuclear Information System (INIS)

Vargas-Luna, M.; Gutierrez-Juarez, G.; Rodriguez-Vizcaino, J.M.; Varela-Nsjera, J.B.; Rodriguez-Palencia, J.M.; Bernal-Alvarado, J.; Sosa, M.; Alvarado-Gil, J.J.

2002-01-01

The time evolution of the inhomogeneous curing process of polystyrene emulsions is studied using a variant of the conventional photoacoustic (PA) technique. The thermal effusivity, as a function of time, is determined in order to monitor the sintering process of a styrene emulsion in different steps of the manufacturing procedure. PA measurements of thermal effusivity show a sigmoidal growth as a function of time during the curing process. The parameterization of these curves permits the determination of the characteristic curing time and velocity of the process. A decreasing of the curing time and an increasing curing velocity for the final steps of the manufacturing process are observed. The feasibility of our approach and its potentiality for the characterization of other curing process are discussed. (author)

7 CFR 29.1019 - Flue-cured.

Science.gov (United States)

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Flue-cured. 29.1019 Section 29.1019 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... tobacco; or tobacco cured by some other process which accomplishes the same results. [42 FR 21092, Apr. 25...

CURING OF POLYMERIC COMPOSITES USING MICROWAVE RESIN TRANSFER MOULDING (RTM

Directory of Open Access Journals (Sweden)

R. YUSOFF

2007-08-01

Full Text Available The main objective of this work is to compare the difference between microwave heating and conventional thermal heating in fabricating carbon/epoxy composites. Two types of epoxy resin systems were used as matrices, LY5052-HY5052 and DGEBA-HY917-DY073. All composite samples were fabricated using resin transfer moulding (RTM technique. The curing of the LY5052-HY5052-carbon and the DGEBA-HY917-DY073-carbon composite systems, were carried out at 100 °C and 120 °C, respectively. Microwave heating showed better temperature control than conventional heating, however, the heating rate of the microwave cured samples were slower than the conventionally cured samples. This was attributed to the lower power (250 W used when heating with microwaves compared to 2000 W used in conventional heating. Study of thermal characteristics as curing progressed showed that the polymerisation reaction occurred at a faster rate during microwave curing than in conventional curing for both the DGEBA and the LY/HY5052 carbon composite systems. The actual cure cycle was reduced from 60 minutes to 40 minutes when using microwaves for curing DGEBA-carbon composites. As for LY/HY5052-carbon composites, the actual cure cycle was reduced from 3 hours to 40 minutes. Both conventional and microwave heating yielded similar glass transition temperatures (120 °C for DGEBA systems and 130 °C for LY/HY5052 systems. Microwave cured composites had higher void contents than conventionally cured composites (2.2-2.8% and 1.8-2.4% for DGEBA and LY/HY5052 microwave cured composites, respectively, compared to 0.2-0.4% for both DGEBA and LY/HY5052 thermally cured composites. C-scan traces showed that all composites, regardless of methods of curing, had minimal defects.

Determinant of flexible Parametric Estimation of Mixture Cure ...

African Journals Online (AJOL)

AIC, mean time to cure), variance and cure fraction (c) were used to determine the flexible Parametric Cure Fraction Model among the considered models. Gastric Cancer data from 76 patients received adjuvant CRT and 125 receiving resection (surgery) alone were used to confirm the suitability of the models. The data was ...

Curing of Thick Thermoset Composite Laminates: Multiphysics Modeling and Experiments

Science.gov (United States)

Anandan, S.; Dhaliwal, G. S.; Huo, Z.; Chandrashekhara, K.; Apetre, N.; Iyyer, N.

2017-11-01

Fiber reinforced polymer composites are used in high-performance aerospace applications as they are resistant to fatigue, corrosion free and possess high specific strength. The mechanical properties of these composite components depend on the degree of cure and residual stresses developed during the curing process. While these parameters are difficult to determine experimentally in large and complex parts, they can be simulated using numerical models in a cost-effective manner. These simulations can be used to develop cure cycles and change processing parameters to obtain high-quality parts. In the current work, a numerical model was built in Comsol MultiPhysics to simulate the cure behavior of a carbon/epoxy prepreg system (IM7/Cycom 5320-1). A thermal spike was observed in thick laminates when the recommended cure cycle was used. The cure cycle was modified to reduce the thermal spike and maintain the degree of cure at the laminate center. A parametric study was performed to evaluate the effect of air flow in the oven, post cure cycles and cure temperatures on the thermal spike and the resultant degree of cure in the laminate.

Radiation curing--new technology of green industries facing 21st century

International Nuclear Information System (INIS)

Wang Jianguo; Teng Renrui

2000-01-01

The development of radiation curing was simply reviewed and the mechanism of UV curing and EB curing, the equipment and materials used in the radiation curing were also introduced. Compared with ordinary curing, the radiation curing has advantages of energy saving, high effectiveness and little pollution. It is a new technology of green industries facing the 21st century

Overview of UV and EB curing

International Nuclear Information System (INIS)

Garnett, J.L.

2000-01-01

Full text: UV and EB are complementary techniques in radiation curing. In the proposed paper, a brief review of both fields will be given. This will include principles of the process, the chemistry of the systems including monomers/oligomers/polymers used, additives required where necessary such as photoinitiators for UV, flow aids, adhesion promoters and the like. The types of equipment used in such processes will also be discussed including low energy electron beam utilisation and excimer curing. The advantages and disadvantages of both techniques will be examined. Mechanistic aspects of both curing systems will be discussed. Applications of the technology including developments in the banknote printing field will be summarised

A Comparison of Curing Process-Induced Residual Stresses and Cure Shrinkage in Micro-Scale Composite Structures with Different Constitutive Laws

Science.gov (United States)

Li, Dongna; Li, Xudong; Dai, Jianfeng; Xi, Shangbin

2018-02-01

In this paper, three kinds of constitutive laws, elastic, "cure hardening instantaneously linear elastic (CHILE)" and viscoelastic law, are used to predict curing process-induced residual stress for the thermoset polymer composites. A multi-physics coupling finite element analysis (FEA) model implementing the proposed three approaches is established in COMSOL Multiphysics-Version 4.3b. The evolution of thermo-physical properties with temperature and degree of cure (DOC), which improved the accuracy of numerical simulations, and cure shrinkage are taken into account for the three models. Subsequently, these three proposed constitutive models are implemented respectively in a 3D micro-scale composite laminate structure. Compared the differences between these three numerical results, it indicates that big error in residual stress and cure shrinkage generates by elastic model, but the results calculated by the modified CHILE model are in excellent agreement with those estimated by the viscoelastic model.

High Power UV LED Industrial Curing Systems

Energy Technology Data Exchange (ETDEWEB)

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

2012-05-14

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

Curing mechanism of flexible aqueous polymeric coatings.

Science.gov (United States)

Irfan, Muhammad; Ahmed, Abid Riaz; Kolter, Karl; Bodmeier, Roland; Dashevskiy, Andriy

2017-06-01

The objective of this study was to explain curing phenomena for pellets coated with a flexible polymeric coating based on poly(vinyl acetate) (Kollicoat® SR 30D) with regard to the effect of starter cores, thickness of drug layer, adhesion of coating to drug-layered-cores as well as coating properties. In addition, appropriate approaches to eliminate the curing effect were identified. Sugar or MCC cores were layered with the model drugs carbamazepine, theophylline, propranolol HCl, tramadol HCl and metoprolol HCl using HPMC (5 or 25% w/w, based on drug) as a binder. Drug-layered pellets were coated with Kollicoat® SR 30D in a fluidized bed coater using TEC (10% w/w) as plasticizer and talc (35-100% w/w) as anti-tacking agent. Drug release, pellet properties (morphology, water uptake-weight loss and osmolality) and adhesion of the coating to the drug layer were investigated as a function of curing at 60°C or 60°C/75% RH for 24h. The film formation of the aqueous dispersion of Kollicoat® SR 30D was complete, and therefore, a strong curing effect (decrease in drug release) at elevated temperature and humidity (60°C/75% RH) could not be explained by the well-known hydroplasticization and the further gradual coalescence of the colloidal polymer particles. According to the provided mechanistic explanation, the observed curing effect was associated with (1) high flexibility of coating, (2) adhesion between coating and drug layer, (3) water retaining properties of the drug layer, and (4) osmotically active cores. Unwanted curing effects could be minimized/eliminated by the addition of talc or/and pore-forming water soluble polymers in the coating, increasing binder amount or applying an intermediate coating, by increasing the thickness of drug layer or using non-osmotic cores. A new insight into curing phenomena mainly associated with the adhesion between drug layer and coating was provided. Appropriate approaches to avoid unwanted curing effect were identified

Proceedings of national executive management seminar on surface finishing by radiation curing technology: radiation curing for better finishing

Energy Technology Data Exchange (ETDEWEB)

NONE

1994-12-31

This book compiled the paper presented at this seminar. The papers discussed are 1. Incentives for investment in the manufacturing sector (in Malaysia) 2.Trends and prospect of surface finishing by radiation curing technology in Malaysia 3. Industrial application of radiation curing.

Proceedings of national executive management seminar on surface finishing by radiation curing technology: radiation curing for better finishing

International Nuclear Information System (INIS)

1993-01-01

This book compiled the paper presented at this seminar. The papers discussed are 1. Incentives for investment in the manufacturing sector (in Malaysia) 2.Trends and prospect of surface finishing by radiation curing technology in Malaysia 3. Industrial application of radiation curing

Additive effects in radiation grafting and curing

International Nuclear Information System (INIS)

Viengkhou, V.; Ng, L.

1996-01-01

Full text: Detailed studies on the accelerative effect of novel additives in radiation grafting and curing using acrylated monomer/oligomer systems have been performed in the presence of ionising radiation and UV as sources. Methyl methacrylate (MMA) is used as typical monomer for these grafting studies in the presence of the additives with model backbone polymers, cellulose and propropylene. Additives which have been found to accelerate these grafting processes are: mineral acid, occlusion compounds like urea, thermal initiators and photoinitiators as well as multifunctional monomers such as multifunctional acrylates. The results from irradiation with gamma rays have also been compared with irradiation from a 90W UV lamp. The role of the above additives in accelerating the analogous process of radiation curing has been investigated. Acrylated urethanes, epoxies and polyesters are used as oligomers together with acrylated monomers in this work with uv lamps of 300 watts/inch as radiation source. In the UV curing process bonding between film and substrate is usually due to physical forces. In the present work the presence of additives are shown to influence the occurrence of concurrent grafting during cure thus affecting the nature of the bonding of the cured film. The conditions under which concurrent grafting with UV can occur will be examined. A mechanism for accelerative effect of these additives in both grafting and curing processes has been proposed involving radiation effects and partitioning phenomena

Radiation sources EB and UV curing machines

Energy Technology Data Exchange (ETDEWEB)

Sasaki, Takashi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

1994-12-31

This paper describes electron beam processors and related technologies for curing applications to facilitate those industrial personals who are trying to understand and evaluate the applicability and benefits of radiation curing to their products. 4 tabs., 10 figs.

Radiation sources EB and UV curing machines

International Nuclear Information System (INIS)

Takashi Sasaki

1993-01-01

This paper describes electron beam processors and related technologies for curing applications to facilitate those industrial personals who are trying to understand and evaluate the applicability and benefits of radiation curing to their products. 4 tabs., 10 figs

What is radiation curing

International Nuclear Information System (INIS)

Kinstle, J.F.

1975-01-01

Radiation curing is a highly interdisciplinary and sophisticated field. Successful interplay between chemists and engineers of various disciplines is required. Throughout the research-development-applications cycle, two disciplines for which hybridization is extremely important are radiation chemistry and polymer chemistry. The molecular level effects caused by absorbed radiation depend strongly on the type and intensity of the radiation. Efficient utilization of the radiation to effect desired transformations in a monomer and/or polymer system, and maximization of final properties, depend on well-planned polymer synthesis and system formulation. The elementary basis of these two disciplines and the manner in which they necessarily coalesce in the field of radiation curing are reviewed

Modeling the curing process of thermosetting resin matrix composites

Science.gov (United States)

Loos, A. C.

1986-01-01

A model is presented for simulating the curing process of a thermosetting resin matrix composite. The model relates the cure temperature, the cure pressure, and the properties of the prepreg to the thermal, chemical, and rheological processes occurring in the composite during cure. The results calculated with the computer code developed on the basis of the model were compared with the experimental data obtained from autoclave-curved composite laminates. Good agreement between the two sets of results was obtained.

Excimer Laser Curing Of Polymer Coatings

Science.gov (United States)

Klick, David; Akerman, M. Alfred; Paul, George L.; Supurovic, Darko; Tsuda, Haruki

1988-12-01

The use of the excimer laser as a source of energy for photo-assisted curing of industrial polymeric coatings was investigated. Presently, UV lamps are sometimes used to excite a photoinitiating molecule mixed with the starting monomers and oligomers of a coating. The resulting polymeric chain reaction multiplies the effect of the initial photons, making economical use of the light source. The high cost of laser photons may thus be justifiable if lasers provide advantages over lamps. A series of visibly transparent 7 μm coatings (a typical thickness for 'slick' magazine coatings) with various photoinitiators, monomers, and oligomers was illuminated with excimer laser light of various wavelengths, fluences, and pulse repetition rates. For the optimum parameters, it was found that the laser had large advantages in curing speed over existing UV lamp processes, due to its monochromaticity. Pigmented coatings (20 μm TiO2 mixtures typical of appliance or automotive finishes) are not easily cured with UV lamps due to the inability of light to penetrate the absorbing and scattering pigmented layer. However, economically-viable cure rates were achieved with certain photoinitiators using a tunable excimer-pumped dye laser. A prototype of such a laser suitable for factory use was built and used to cure these coatings. Results are scaled to a factory situation, and costs are calculated to show the advantages of the laser method over currently used processes.

Bulk-Fill Composites: Effectiveness of Cure With Poly- and Monowave Curing Lights and Modes.

Science.gov (United States)

Gan, J K; Yap, A U; Cheong, J W; Arista, N; Tan, Cbk

This study compared the effectiveness of cure of bulk-fill composites using polywave light-emitting diode (LED; with various curing modes), monowave LED, and conventional halogen curing lights. The bulk-fill composites evaluated were Tetric N-Ceram bulk-fill (TNC), which contained a novel germanium photoinitiator (Ivocerin), and Smart Dentin Replacement (SDR). The composites were placed into black polyvinyl molds with cylindrical recesses of 4-mm height and 3-mm diameter and photopolymerized as follows: Bluephase N Polywave High (NH), 1200 mW/cm 2 (10 seconds); Bluephase N Polywave Low (NL), 650 mW/cm 2 (18.5 seconds); Bluephase N Polywave soft-start (NS), 0-650 mW/cm 2 (5 seconds) → 1200 mW/cm 2 (10 seconds); Bluephase N Monowave (NM), 800 mW/cm 2 (15 seconds); QHL75 (QH), 550 mW/cm 2 (21.8 seconds). Total energy output was fixed at 12,000 mJ/cm 2 for all lights/modes, with the exception of NS. The cured specimens were stored in a light-proof container at 37°C for 24 hours, and hardness (Knoop Hardness Number) of the top and bottom surfaces of the specimens was determined using a Knoop microhardness tester (n=6). Hardness data and bottom-to-top hardness ratios were subjected to statistical analysis using one-way analysis of variance/Scheffe's post hoc test at a significance level of 0.05. Hardness ratios ranged from 38.43% ± 5.19% to 49.25% ± 6.38% for TNC and 50.67% ± 1.54% to 67.62% ± 6.96% for SDR. For both bulk-fill composites, the highest hardness ratios were obtained with NM and lowest hardness ratios with NL. While no significant difference in hardness ratios was observed between curing lights/modes for TNC, the hardness ratio obtained with NM was significantly higher than the hardness ratio obtained for NL for SDR.

A Fourier transform Raman spectroscopy analysis of the degree of conversion of a universal hybrid resin composite cured with light-emitting diode curing units.

Science.gov (United States)

Lindberg, Anders; Emami, Nazanin; van Dijken, Jan W V

2005-01-01

The degree of conversion (DC), of a universal hybrid resin composite cured with LED curing units with low and high power densities and a 510 mW/cm2 quartz tungsten halogen unit, was investigated with Fourier Transform Raman spectroscopy. Three curing depths (0, 2, 4mm) and 0 and 7 mm light guide tip - resin composite (LT - RC) distances were tested. The DC of the LED units varied between 52.3% - 59.8% at the top surface and 46.4% - 57.0% at 4 mm depth. The DC of specimen cured with a 0 mm LT- RC distance at 4 mm depth varied between 50.8% - 57.0% and with 7 mm distance between 46.4% - 55.4%. The low power density LED unit showed a significantly lower DC for both distances at all depth levels compared to the other curing units (p units were only found at the 4 mm depth level cured from 7 mm distance (p units. It can be concluded that the improved LED curing units could cure the studied resin composite to the same DC as the control unit.

Cure kinetics and chemorheology of EPDM/graphene oxide nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Allahbakhsh, Ahmad [Department of Polymer Engineering, Islamic Azad University, South Tehran Branch, 17776-13651 Tehran (Iran, Islamic Republic of); Mazinani, Saeedeh, E-mail: s.mazinani@aut.ac.ir [Amirkabir Nanotechnology Research Institute (ANTRI), Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Kalaee, Mohammad Reza [Department of Polymer Engineering, Islamic Azad University, South Tehran Branch, 17776-13651 Tehran (Iran, Islamic Republic of); Sharif, Farhad [Department of Polymer Engineering and Color Technology, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

2013-07-10

Graphical abstract: - Highlights: • Graphene oxide content and dispersion as effective parameters on cure kinetics. • Graphene oxide as an effective controlling factor of crosslink density. • Interaction of graphene oxide with curing system (ZnO) during curing process. - Abstract: In this study, the effect of graphene oxide on cure behavior of ethylene–propylene–diene rubber (EPDM) nanocomposite is studied. In this regard, the cure kinetics of nanocomposite is studied employing different empirical methods. The required activation energy of nth-order cure process shows about 160 kJ/mol increments upon 5 phr graphene oxide loading compared to 1 phr graphene oxide loading. However, the required activation energy is significantly reduced followed by incorporation of graphene oxide in nanocomposites compared to neat EPDM sample. Furthermore, the effect of graphene oxide on structural properties of nanocomposites during the cure process is studied using X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectrometry techniques. As the results show, graphene oxide interestingly affects the structure of zinc oxide during the vulcanization process. This behavior could be probably related to high tendency of zinc oxide to react with oxidized surface of graphene oxide.

UV curing of a liquid based bismaleimide-containing polymer system

Directory of Open Access Journals (Sweden)

2007-06-01

Full Text Available A new liquid formulation of commercial bismaleimide and n-acryloylmorpholine was prepared that could be UV cured as an alternative to traditional thermal cure methods presently used for BMI in the industry. UV curing was shown to be an efficient method which promoted the reaction rate significantly and was able to achieve this at low temperatures (30–50°C. A free radical polymerization approach has been used to explain the cure mechanism and cure kinetics, using data elucidated from the DPC and FTIR. The cured thin film was shown to achieve very high thermal stability (~400°C, with the BMI shown to retard the thermal degradation temperature and rate.

Radiation curing: Science and technology

International Nuclear Information System (INIS)

Pappas, S.P.

1992-01-01

The science and technology of radiation curing have progressed substantially within the last 20 years. Nevertheless, radiation-curable compositions typically command relatively small shares in many of their competitive markets. This situation signifies that potential advantages of radiation curing are not generally perceived to overcome their limitations. An important objective of this book is to address this issue, within the scope of the subjects offered, by providing the present state of knowledge and by identifying the directions and challenges for future studies. The first chapter introduces radiation curing. Chapter 2 offers the first systematic presentation of inorganic and organometallic photoinitiators. Chapters 3 and 4 present the analytical techniques of photocalorimetry and real-time infrared spectroscopy, respectively. Recent advances in resin technology are offered in Chapters 5 and 6, which constitute the first comprehensive accounts of (meth)acrylated silicones and vinyl ethers, respectively. Radiation-curable coatings, printing inks, and adhesives are discussed in Chapters 7-9, respectively. Chapter 10 offers a discussion on photopolymer imaging systems

Techniques and materials for internal water curing of concrete

DEFF Research Database (Denmark)

Jensen, Ole Mejlhede; Lura, Pietro

2006-01-01

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

Factors affecting dry-cured ham consumer acceptability.

Science.gov (United States)

Morales, R; Guerrero, L; Aguiar, A P S; Guàrdia, M D; Gou, P

2013-11-01

The objectives of the present study were (1) to compare the relative importance of price, processing time, texture and intramuscular fat in purchase intention of dry-cured ham through conjoint analysis, (2) to evaluate the effect of dry-cured ham appearance on consumer expectations, and (3) to describe the consumer sensory preferences of dry-cured ham using external preference mapping. Texture and processing time influenced the consumer preferences in conjoint analysis. Red colour intensity, colour uniformity, external fat and white film presence/absence influenced consumer expectations. The consumer disliked hams with bitter and metallic flavour and with excessive saltiness and piquantness. Differences between expected and experienced acceptability were found, which indicates that the visual preference of consumers does not allow them to select a dry-cured ham that satisfies their sensory preferences of flavour and texture. Copyright © 2013 Elsevier Ltd. All rights reserved.

Steam-cured stabilised soil blocks for masonry construction

Energy Technology Data Exchange (ETDEWEB)

Venkatarama Reddy, B.V. [Indian Inst. of Science, Bangalore (India). Dept. of Civil Engineering; Lokras, S.S. [Indian Inst. of Science, Bangalore (India). ASTRA

1998-12-01

Energy-efficient, economical and durable building materials are essential for sustainable construction practices. The paper deals with production and properties of energy-efficient steam-cured stabilised soil blocks used for masonry construction. Problems of mixing expansive soil and lime, and production of blocks using soil-lime mixtures have been discussed briefly. Details of steam curing of stabilised soil blocks and properties of such blocks are given. A comparison of energy content of steam-cured soil blocks and burnt bricks is presented. It has been shown that energy-efficient steam cured soil blocks (consuming 35% less thermal energy compared to burnt clay bricks) having high compressive strength can be easily produced in a decentralised manner. (orig.)

UV/EB curing in Australia

International Nuclear Information System (INIS)

Woods, R.; Garnett, J.; Loo Teck Ng

1999-01-01

Progress in LTV/EB curing is reviewed in Australia. Generally the technology is used by those industries where curing is well developed in Europe and North America, however the scale is an order of magnitude lower due to the smaller market size. The Asian economic crisis does not appear to have affected expansion of the technology in Australia. EB continues to be successfully used in the packaging and foam fields whilst in UV, security devices, particularly banknotes are steadily expanding especially in export markets have been studied

Muscle individual phospholipid classes throughout the processing of dry-cured ham: influence of pre-cure freezing.

Science.gov (United States)

Pérez-Palacios, Trinidad; Ruiz, Jorge; Dewettinck, Koen; Le, Thien Trung; Antequera, Teresa

2010-03-01

This paper aims to study the profile of phospholipid (PL) classes of Iberian ham throughout its processing and the changes it underwent due to the influence of the pre-cure freezing treatment. The general profile of each PL class did not vary during the ripening stage. Phosphatidylcholine (PC) showed the highest proportion, followed by phosphatidyletanolamine (PE) and phosphatidylserine (PS) and phosphatidylinositol (PI) being the minor PL. The four PL classes were highly hydrolysed during the salting stage and their degradation continued during the rest of the processing. Pre-cure freezing of Iberian ham influenced the levels of the four PL classes at the initial stage, all of them being higher in refrigerated (R) than in pre-cure frozen (F) hams. Moreover, the pattern of hydrolysis was not the same in these two groups. Copyright 2009 Elsevier Ltd. All rights reserved.

Curing the queue

NARCIS (Netherlands)

Zonderland, Maartje Elisabeth

2012-01-01

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

Effect of curing time on microstructure and mechanical strength ...

Indian Academy of Sciences (India)

The aim of this paper is to study the influence of curing time on the microstructure and mechanical strength development of alkali activated binders based on vitreous calcium aluminosilicate (VCAS). Mechanical strength of alkali activated mortars cured at 65 °C was assessed for different curing times (4–168 h) using 10 ...

Curing potential of experimental resin composites with systematically varying amount of bioactive glass: Degree of conversion, light transmittance and depth of cure.

Science.gov (United States)

Par, Matej; Spanovic, Nika; Bjelovucic, Ruza; Skenderovic, Hrvoje; Gamulin, Ozren; Tarle, Zrinka

2018-06-17

The aim of this work was to investigate the curing potential of an experimental resin composite series with the systematically varying amount of bioactive glass 45S5 by evaluating the degree of conversion, light transmittance and depth of cure. Resin composites based on a Bis-GMA/TEGDMA resin with a total filler load of 70 wt% and a variable amount of bioactive glass (0-40 wt%) were prepared. The photoinitiator system was camphorquinone and ethyl-4-(dimethylamino) benzoate. The degree of conversion and light transmittance were measured by Raman spectroscopy and UV-vis spectroscopy, respectively. The depth of cure was evaluated according to the classical ISO 4049 test. The initial introduction of bioactive glass into the experimental series diminished the light transmittance while the further increase in the bioactive glass amount up to 40 wt% caused minor variations with no clear trend. The curing potential of the experimental composites was similar to or better than that of commercial resin composites. However, unsilanized bioactive glass fillers demonstrated the tendency to diminish both the maximum attainable conversion and the curing efficiency at depth. Experimental composite materials containing bioactive glass showed a clinically acceptable degree of conversion and depth of cure. The degree of conversion and depth of cure were diminished by bioactive glass fillers in a dose-dependent manner, although light transmittance was similar among all of the experimental composites containing 5-40 wt% of bioactive glass. Reduced curing potential caused by the bioactive glass has possible consequences on mechanical properties and biocompatibility. Copyright © 2018 Elsevier Ltd. All rights reserved.

Hard facts for radiation curing of elastomers

International Nuclear Information System (INIS)

Lyall, D.J.

1984-01-01

The subject is covered under the headings: introduction; outline of chemistry (differences between conventional and radiation curing); compounding; green strength; response of rubbers to electron beam treatment; electron beam cured applications:(a) wire and cable applications;(b) rubber tyre components;(c) heat shrinkable materials;(d) roofing materials. (U.K.)

Cure modeling in real-time prediction: How much does it help?

Science.gov (United States)

Ying, Gui-Shuang; Zhang, Qiang; Lan, Yu; Li, Yimei; Heitjan, Daniel F

2017-08-01

Various parametric and nonparametric modeling approaches exist for real-time prediction in time-to-event clinical trials. Recently, Chen (2016 BMC Biomedical Research Methodology 16) proposed a prediction method based on parametric cure-mixture modeling, intending to cover those situations where it appears that a non-negligible fraction of subjects is cured. In this article we apply a Weibull cure-mixture model to create predictions, demonstrating the approach in RTOG 0129, a randomized trial in head-and-neck cancer. We compare the ultimate realized data in RTOG 0129 to interim predictions from a Weibull cure-mixture model, a standard Weibull model without a cure component, and a nonparametric model based on the Bayesian bootstrap. The standard Weibull model predicted that events would occur earlier than the Weibull cure-mixture model, but the difference was unremarkable until late in the trial when evidence for a cure became clear. Nonparametric predictions often gave undefined predictions or infinite prediction intervals, particularly at early stages of the trial. Simulations suggest that cure modeling can yield better-calibrated prediction intervals when there is a cured component, or the appearance of a cured component, but at a substantial cost in the average width of the intervals. Copyright © 2017 Elsevier Inc. All rights reserved.

Electron Beam Curing of Polymer Matrix Composites - CRADA Final Report

Energy Technology Data Exchange (ETDEWEB)

Janke, C. J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Howell, Dave [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Norris, Robert E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

1997-05-01

The major cost driver in manufacturing polymer matrix composite (PMC) parts and structures, and one of the elements having the greatest effect on their quality and performance, is the standard thermal cure process. Thermal curing of PMCs requires long cure times and high energy consumption, creates residual thermal stresses in the part, produces volatile toxic by-products, and requires expensive tooling that is tolerant of the high cure temperatures.

UV curing by radical, cationic and concurrent radicalcationic polymerization

International Nuclear Information System (INIS)

Pappas, S.P.

1984-01-01

UV and EB curing represent complementary technologies with respective advantages and disadvantages. This paper deals with the design and evaluation of UV curable coatings to optimize cure rate and film properties. Topics included are state-of-the-art photoinitiator systems, light intensity effects, retardation of air-inhibition, adhesion, and amplification of photons for enhanced speed of cure

A robust and stretchable superhydrophobic PDMS/PVDF@KNFs membrane for oil/water separation and flame retardancy.

Science.gov (United States)

Li, Deke; Gou, Xuelian; Wu, Daheng; Guo, Zhiguang

2018-04-05

The wide application of superhydrophobic membranes has been limited due to their complicated preparation technology and weak durability. Inspired by the mechanical flexibility of nanofibrous biomaterials, nanofibrils have been successfully generated from Kevlar, which is one of the strongest synthetic fibers, by appropriate hydrothermal treatment. In this study, a robust superhydrophobic PDMS/PVDF@KNFs membrane is prepared via a simple one-step process and subsequent curing without combination with inorganic fillers. The as-prepared PDMS/PVDF@KNFs membrane not only shows efficient oil/water separation ability and oil absorption capacity but also has excellent superhydrophobicity stability after deformation. The resultant membrane shows stretchability, flexibility and flame retardance because of the reinforcing effect and the excellent flame retardancy of Kevlar. We believe that this simple fabrication of PDMS/PVDF@KNFs has promising applications in filtering membranes and wearable devices.

Study of oxygen inhibition effect on radiation curing

International Nuclear Information System (INIS)

Xiao Bin; Yang Xuemei; Zhao Pengji; Zeng Shuqing; Jiang Bo; Zhou Yong; Huang Wei; Zhou Youyi

1995-01-01

Michacl addition reaction product was used in the research of oxygen inhibition effect of radiation curing. The experimental results was measured by the content of gel and percentage of double bonds. It was proved that 9% of Michacl addition product could speed up 1.2 times of the radiation curing rate at 30 kGy of EB irradiation. This kind of formulation can withstand oxygen inhibition effect obviously, so it was the foundation of application for radiation curing in atmospheric condition

Curing and caring competences in the skills training of physiotherapy students.

Science.gov (United States)

Dahl-Michelsen, Tone

2015-01-01

This article explores the significance of curing and caring competences in physiotherapy education, as well as how curing and caring competences intersect within the professional training of physiotherapy students. The empirical data include participant observations and interviews with students attending skills training in the first year of a bachelor's degree program in Norway. Curing and caring are conceptualized as gender-coded competences. That is, curing and caring are viewed as historical and cultural constructions of masculinities and femininities within the physiotherapy profession, as well as performative actions. The findings illuminate the complexity of curing and caring competences in the skills training of physiotherapy students. Curing and caring are both binary and intertwined competences; however, whereas binary competences are mostly concerned with contextual frames, intertwined competences are mostly concerned with performative aspects. The findings also point to how female and male students attend to curing and caring competences in similar ways; thus, the possibilities of transcending traditional gender norms turn out to be significant in this context. The findings suggest that, although curing somehow remains hegemonic to caring, the future generation of physiotherapists seemingly will be able to use their skills for both caring and curing.

effect of curing methods on the compressive strength of concrete

African Journals Online (AJOL)

High curing temperature (up to 212◦F or. 100◦C) ... are affected by curing and application of the ... for concrete production, it is important to ... Concrete properties and durability are signif- ... Curing compounds are merely temporary coatings on.

7 CFR 30.36 - Class 1; flue-cured types and groups.

Science.gov (United States)

2010-01-01

...-cured, produced principally in the Piedmont sections of Virginia and North Carolina. (b) Type 11b. That... lying between the Piedmont and coastal plains regions of Virginia and North Carolina. (c) Type 12. That type of flue-cured tobacco commonly known as Eastern Flue-cured or Eastern Carolina Flue-cured...

Determinant of flexible Parametric Estimation of Mixture Cure ...

African Journals Online (AJOL)

PROF. OLIVER OSUAGWA

2015-12-01

Dec 1, 2015 ... Suitability of four parametric mixture cure models were considered namely; Log .... regression analysis which relies on the ... The parameter of mixture cure fraction model was ..... Stochastic Models of Tumor Latency and Their.

Effect of gamma-radiation on major aroma compounds and vanillin glucoside of cured vanilla beans (Vanilla planifolia)

International Nuclear Information System (INIS)

Salmah Moosa; Seri Chempaka Mohd Yusof; Ruzalina Bahrin; Maizatul Akmam Mohd Nasir

2014-01-01

Radiation processing of food materials by gamma-radiation is a well established method for microbial decontamination and insect disinfestation. Irradiation of spices at doses ranging from 10 to 30 kGy has been reported to result in complete elimination of microorganisms with negligible changes in the flavour quality. The effect of gamma-radiation on microflora and vanillin content of cured vanilla beans in the dose range of 5-50 kGy has been investigated, but its effect on other major aroma compounds and vanillin glucoside (vanillin aroma precursor) remaining after curing have not been studied so far. Vanillin (4-hydroxy-3-methoxybenzaldehyde) is one such compound used as a flavouring agent and as a dietary component. It is the major component of natural vanilla, which is one of the most widely used and important flavouring materials throughout the world. Vanillin is an antioxidant capable of protecting membrane against lipid peroxidation and DNA against strand breaks induced by reactive oxygen species. The present work was aimed to study the effect of gamma-radiation processing on the major aroma compounds of cured vanilla beans and also to investigate possible enhancement in vanillin content by the radiolytic breakdown of vanillin glucoside present already. Cured vanilla beans were irradiated (5, 10, 15, 20 and 30 kGy) and the vanillin content of control and irradiated samples were analysed, respectively for a possible enhancement of vanillin content by radiolysis of vanillin glucoside. Radiolytic breakdown of glycosidic precursors of aroma constituents and consequent release of free aroma was shown to result in the enhancement of aroma quality of these products. Since a considerable amount of vanillin exists as its glycosidic precursor in cured vanilla pods, a possible enhancement in yield of vanillin by radiation processing is thus expected. Hence the highly stable oxygen-carbon linkage between vanillin and glucose limits the possible enhancement of aroma

Year of progress for radiation curing

International Nuclear Information System (INIS)

Mesrobian, R.B.

1975-01-01

New developments in ultraviolet and electron beam curing of inks and coatings are reviewed. Current installations of radiation systems are noted. An assessment is presented on raw and intermediate materials availability. Current outlook on such problems as toxicity (FDA and OSHA), residual volatiles, materials cost, adhesion and flow-out of coatings is discussed. The future potential for radiation curing systems is contrasted with that of other systems, in view of EPA requirements

A novel reverse osmosis membrane modified by polyvinyl alcohol with maleic anhydride crosslinking

Science.gov (United States)

Samnani, Mohit; Rathod, Harshad; Raval, Hiren

2018-03-01

In the era of increasing energy crisis, it is inevitable to decrease process energy consumption to increase process viability and curtail green-house gas emission. The Reverse Osmosis plant requires significant energy to transfer water overcoming the osmotic pressure. This paper focuses on increasing the water flux for Thin Film Composite Reverse Osmosis (TFC RO) membrane without compromising salt rejection performance leading to the environmentally friendly and economically attractive process. The virgin TFC RO membrane was exposed to solution of sodium hypochlorite of concentration 2000 mg l-1 for 1 h to activate the surface of the membrane, followed by the treatment with the mixture of polyvinyl alcohol and maleic anhydride with varying concentrations for 1 h and curing in the oven at 80 °C temperature for 10 min. Out of all the treated membranes, the membrane treated with 2000 mg l-1 polyvinyl alcohol and 1000 mg l-1 maleic anhydride demonstrated the highest salt rejection of 96.83 % with 2% increase as compared to the virgin TFC RO membrane. The water flux of the membrane was around 44% higher than the virgin TFC RO membrane. The membrane samples were characterized by atomic force micrographs, ATR-FTIR, Nuclear magnetic resonance and Dynamic mechanical analysis.

Thermal analysis of bulk filled composite resin polymerization using various light curing modes according to the curing depth and approximation to the cavity wall

Directory of Open Access Journals (Sweden)

Hoon-Sang Chang

2013-07-01

Full Text Available OBJECTIVE: The purpose of this study was to investigate the polymerization temperature of a bulk filled composite resin light-activated with various light curing modes using infrared thermography according to the curing depth and approximation to the cavity wall. MATERIAL AND METHODS: Composite resin (AeliteFlo, Bisco, Schaumburg, IL, USA was inserted into a Class II cavity prepared in the Teflon blocks and was cured with a LED light curing unit (Dr's Light, GoodDoctors Co., Seoul, Korea using various light curing modes for 20 s. Polymerization temperature was measured with an infrared thermographic camera (Thermovision 900 SW/TE, Agema Infra-red Systems AB, Danderyd, Sweden for 40 s at measurement spots adjacent to the cavity wall and in the middle of the cavity from the surface to a 4 mm depth. Data were analyzed according to the light curing modes with one-way ANOVA, and according to curing depth and approximation to the cavity wall with two-way ANOVA. RESULTS: The peak polymerization temperature of the composite resin was not affected by the light curing modes. According to the curing depth, the peak polymerization temperature at the depth of 1 mm to 3 mm was significantly higher than that at the depth of 4 mm, and on the surface. The peak polymerization temperature of the spots in the middle of the cavity was higher than that measured in spots adjacent to the cavity wall. CONCLUSION: In the photopolymerization of the composite resin, the temperature was higher in the middle of the cavity compared to the outer surface or at the internal walls of the prepared cavity.

Monitoring cure of composite resins using frequency dependent electromagnetic sensing techniques

Science.gov (United States)

Kranbuehl, D. E.; Hoff, M. S.; Loos, A. C.; Freeman, W. T., Jr.; Eichinger, D. A.

1988-01-01

A nondestructive in situ measurement technique has been developed for monitoring and measuring the cure processing properties of composite resins. Frequency dependent electromagnetic sensors (FDEMS) were used to directly measure resin viscosity during cure. The effects of the cure cycle and resin aging on the viscosity during cure were investigated using the sensor. Viscosity measurements obtained using the sensor are compared with the viscosities calculated by the Loos-Springer cure process model. Good overall agreement was obtained except for the aged resin samples.

Mixture proportioning for internal curing

DEFF Research Database (Denmark)

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

2005-01-01

of additional internal water that is not part of the mixing water.” The additional internal water is typically supplied by using relatively small amounts of saturated, lightweight, fine aggregates (LWA) or superabsorbent polymer (SAP) particles in the concrete. Benefits of internal curing include increased...... less than that of bulk water, a hydrating cement paste will imbibe water (about 0.07 g water/g cement) from an available source. While in higher w/c concretes, this water can be, and often is, supplied by external (surface) curing, in low w/c concretes, the permeability of the concrete quickly becomes...

Simulation of curing of a slab of rubber

International Nuclear Information System (INIS)

Abhilash, P.M.; Kannan, K.; Varkey, Bijo

2010-01-01

The objective of the present work is to predict the degree of curing for a rectangular slab of rubber, which was subjected to non-uniform thermal history. As the thermal conductivity of rubber is very low, the temperature gradient across a slab is quite large, which leads to non-uniform vulcanization, and hence non-uniform mechanical properties-an inhomogeneous material. Since curing is an exothermic reaction, heat transfer and chemical reactions are solved in a coupled manner. The effect of heat generation on curing is also discussed.

Experimental observation of internal water curing of concrete

DEFF Research Database (Denmark)

Lura, Pietro; Jensen, Ole Mejlhede

2007-01-01

Internal water curing has a significant effect on concrete. In addition to affecting hydration and moisture distribution, it influences most concrete properties, such as strength, shrinkage, cracking, and durability. The following paper is an overview of experimental methods to study internal water...... curing of concrete and its consequences. The special techniques needed to study internal water curing are dealt with along with the consequences of this process. Examples of applications are given and new measuring techniques that may potentially be applied to this field are addressed....

Simulation of curing of a slab of rubber

Energy Technology Data Exchange (ETDEWEB)

Abhilash, P.M. [Department of Mechanical Engineering, IIT Madras, Chennai 600036 (India); Kannan, K., E-mail: krishnakannan@iitm.ac.i [Department of Mechanical Engineering, IIT Madras, Chennai 600036 (India); Varkey, Bijo [Advanced Design Department, MRF Ltd., Chennai 600019 (India)

2010-04-15

The objective of the present work is to predict the degree of curing for a rectangular slab of rubber, which was subjected to non-uniform thermal history. As the thermal conductivity of rubber is very low, the temperature gradient across a slab is quite large, which leads to non-uniform vulcanization, and hence non-uniform mechanical properties-an inhomogeneous material. Since curing is an exothermic reaction, heat transfer and chemical reactions are solved in a coupled manner. The effect of heat generation on curing is also discussed.

Effect of light-curing units on the thermal expansion of resin nanocomposites.

Science.gov (United States)

Park, Jeong-Kil; Hur, Bock; Ko, Ching-Chang; García-Godoy, Franklin; Kim, Hyung-Il; Kwon, Yong Hoon

2010-12-01

To examine the thermal expansion of resin nanocomposites after light-curing using different light-curing units. Four different resin nanocomposites and four different light-curing units [quartz-tungsten-halogen (QTH), light emitting diode (LED), laser, and plasma arc] were chosen. Metal dies were filled with resin to make specimens and light-cured. The light intensity and light-curing time of the QTH and LED light-curing units were 1000 mW/cm2 and 40 seconds, 700 mW/cm2 and 40 seconds for the laser, and 1600 mW/cm2 and 3 seconds for the plasma arc. The coefficient of thermal expansion (CTE) was evaluated using a thermomechanical analyzer (TMA) at temperatures ranging from 30-80 degrees C. The CTE of the resin nanocomposites tested ranged from 28.5 to 65.8 (x 10(-6)/ degrees C), depending on the product and type of light-curing unit used. Among the specimens, Grandio showed the lowest CTE. The specimens cured using the plasma arc unit (Apollo 95E) showed the highest CTE. There was a linear correlation between the CTE and filler content (vol%) (R: -0.94-0.99 depending on the light-curing unit). The results may suggest a careful selection of the light-curing unit because there was more expansion in the specimens cured using the plasma arc unit than those cured by the other units.

UV-cured polymer optics

Science.gov (United States)

Piñón, Victor; Santiago, Freddie; Vogelsberg, Ashten; Davenport, Amelia; Cramer, Neil

2017-10-01

Although many optical-quality glass materials are available for use in optical systems, the range of polymeric materials is limited. Polymeric materials have some advantages over glass when it comes to large-scale manufacturing and production. In smaller scale systems, they offer a reduction in weight when compared to glass counterparts. This is especially important when designing optical systems meant to be carried by hand. We aimed to expand the availability of polymeric materials by exploring both crown-like and flint-like polymers. In addition, rapid and facile production was also a goal. By using UV-cured thiolene-based polymers, we were able to produce optical materials within seconds. This enabled the rapid screening of a variety of polymers from which we down-selected to produce optical flats and lenses. We will discuss problems with production and mitigation strategies in using UV-cured polymers for optical components. Using UV-cured polymers present a different set of problems than traditional injection-molded polymers, and these issues are discussed in detail. Using these produced optics, we integrated them into a modified direct view optical system, with the end goal being the development of drop-in replacements for glass components. This optical production strategy shows promise for use in lab-scale systems, where low-cost methods and flexibility are of paramount importance.

Weak interfaces for UV cure nanoimprint lithography

Science.gov (United States)

Houle, Frances; Fornof, Ann; Simonyi, Eva; Miller, Dolores; Truong, Hoa

2008-03-01

Nanoimprint lithography using a photocurable organic resist provides a means of patterning substrates with a spatial resolution in the few nm range. The usefulness of the technique is limited by defect generation during template removal, which involves fracture at the interface between the template and the newly cured polymer. Although it is critical to have the lowest possible interfacial fracture toughness (Gc less than 0.1 Jm-2) to avoid cohesive failure in the polymer, there is little understanding on how to achieve this using reacting low viscosity resist fluids. Studies of debonding of a series of free-radical cured polyhedral silsesquioxane crosslinker formulations containing selected reactive diluents from fluorosilane-coated quartz template materials will be described. At constant diluent fraction the storage modulus of cured resists follows trends in initial reaction rate, not diluent Tg. Adhesion is uncorrelated with both Tg and storage modulus. XPS studies of near-interface compositions indicate that component segregation within the resist fluid on contact with the template, prior to cure, plays a significant role in controlling the fracture process.

Cure monitoring of epoxy resin by using fiber bragg grating sensor

Energy Technology Data Exchange (ETDEWEB)

Lee, Jin Hyuk [KEPCO, Naju (Korea, Republic of); Kim, Dae Hyun [Dept. of Mechanical and Automotive Engineering, Seoul National University of Science and Technology, Seoul (Korea, Republic of)

2016-06-15

In several industrial fields, epoxy resin is widely used as an adhesive for co-curing and manufacturing various structures. Controlling the manufacturing process is required for ensuring robust bonding performance and the stability of the structures. A fiber optic sensor is suitable for the cure monitoring of epoxy resin owing to the thready shape of the sensor. In this paper, a fiber Bragg grating (FBG) sensor was applied for the cure monitoring of epoxy resin. Based on the experimental results, it was demonstrated that the FBG sensor can monitor the status of epoxy resin curing by measuring the strain caused by volume shrinkage and considering the compensation of temperature. In addition, two types of epoxy resin were used for the cure-monitoring; moreover, when compared to each other, it was found that the two types of epoxy had different cure-processes in terms of the change of strain during the curing. Therefore, the study proved that the FBG sensor is very profitable for the cure-monitoring of epoxy resin.

Investigation of the cure behaviour of an epoxy polyester powder coating

International Nuclear Information System (INIS)

Ishrat, S.; Nadeem, M.

1993-01-01

The epoxy polyester based thermo sets make attractive matrix materials for many industrial and commercial applications because of their excellent performance properties. These properties for example, dimensional stability, adhesion, chemical resistance, and thermal stability arise primarily from the formation of crosslinks during cure. While many factors, such as the reactivity and stoichiometry of the reactants can influence the course of the crosslinking reaction, the cure temperature and cure time ultimately govern the end use performance of the thermosetting systems of powder coatings. The interrelationship between the network formation process and performance properties makes cure process studies critically important in product development. A products end use performance properties can be correlated with the processing conditions by monitoring specific polymeric properties such as gel points, glass transition temperature (TgS,) and the kinetics of the crosslinking reaction. By plotting the change in these properties against cure time and or cure temperature, a 'profile' or degree of cure (DOC) curve can be formed. These profiles illustrate the progress of the crosslinking reaction and can be used to optimize thermo set handling, processing and cure process. (author)

Status of radiation curing in South America

International Nuclear Information System (INIS)

Machado, L.D.B.; Rotta, A.C.; Petrie, I.

2007-01-01

In August 2006, an agreement between the Rad tech International North America and the ATBCR, the Brazillian Technical Association for Radiation cure, turns ATCBR into RadTech South America. This new institution starts with already 10 years of history and pioneering technical experience and achievements in UV and EB radiation cure. Both RadTech institutions have asserted a whole cooperation and information exchange to continue with the initial ATBCR compromise in promoting UV and EB curing technology and to make it available to professionals, enterprise and other organizations. The RadTech South America has it's headquarter at the Energy and Nuclear Research Institute, IPEN, in Sao Paulo, Brazil, from whom also gets sponsorship. (Author)

Amyloid protein unfolding and insertion kinetics on neuronal membrane mimics

Science.gov (United States)

Qiu, Liming; Buie, Creighton; Vaughn, Mark; Cheng, Kwan

2010-03-01

Atomistic details of beta-amyloid (Aβ ) protein unfolding and lipid interaction kinetics mediated by the neuronal membrane surface are important for developing new therapeutic strategies to prevent and cure Alzheimer's disease. Using all-atom MD simulations, we explored the early unfolding and insertion kinetics of 40 and 42 residue long Aβ in binary lipid mixtures with and without cholesterol that mimic the cholesterol-depleted and cholesterol-enriched lipid nanodomains of neurons. The protein conformational transition kinetics was evaluated from the secondary structure profile versus simulation time plot. The extent of membrane disruption was examined by the calculated order parameters of lipid acyl chains and cholesterol fused rings as well as the density profiles of water and lipid headgroups at defined regions across the lipid bilayer from our simulations. Our results revealed that both the cholesterol content and the length of the protein affect the protein-insertion and membrane stability in our model lipid bilayer systems.

A simple method for preparation of macroporous polydimethylsiloxane membrane for microfluidic chip-based isoelectric focusing applications

Energy Technology Data Exchange (ETDEWEB)

Ou Junjie [Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Ave West, Waterloo, Ontario, N2L 3G1 (Canada); Department of Chemistry, University of Waterloo, 200 University Ave West, Waterloo, Ontario, N2L 3G1 (Canada); Ren, Carolyn L., E-mail: c3ren@mecheng1.uwaterloo.ca [Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Ave West, Waterloo, Ontario, N2L 3G1 (Canada); Pawliszyn, Janusz [Department of Chemistry, University of Waterloo, 200 University Ave West, Waterloo, Ontario, N2L 3G1 (Canada)

2010-03-10

A new, simple method was reported to prepare PDMS membranes with micrometer size pores for microfluidic chip applications. The pores were formed by adding polystyrene and toluene into PDMS prepolymer solution prior to spin-coating and curing. The resulting PDMS membrane has a thickness of around 10 {mu}m and macropores with a diameter ranging from 1 to 2 {mu}m measured using scanning electron microscope (SEM) imaging. This PDMS membrane was validated by integrating it with PDMS microfluidic chips for protein separation using isoelectric focusing mechanism coupled with whole channel imaging detection (IEF-WCID). It has been shown that five standard pI markers and a mixture of two proteins, myoglobin and {beta}-lactoglobulin, can be separated using these chips. The results indicated that this macroporous PDMS membrane can replace the dialysis membrane in PDMS chips for the IEF-WCID technique. The preparation method of macroporous PDMS membrane may be potentially applied in other fields of microfluidic chips.

Anisotropic Dielectric Properties of Carbon Fiber Reinforced Polymer Composites during Microwave Curing

Science.gov (United States)

Zhang, Linglin; Li, Yingguang; Zhou, Jing

2018-01-01

Microwave cuing technology is a promising alternative to conventional autoclave curing technology in high efficient and energy saving processing of polymer composites. Dielectric properties of composites are key parameters related to the energy conversion efficiency during the microwave curing process. However, existing methods of dielectric measurement cannot be applied to the microwave curing process. This paper presented an offline test method to solve this problem. Firstly, a kinetics model of the polymer composites under microwave curing was established based on differential scanning calorimetry to describe the whole curing process. Then several specially designed samples of different feature cure degrees were prepared and used to reflect the dielectric properties of the composite during microwave curing. It was demonstrated to be a feasible plan for both test accuracy and efficiency through extensive experimental research. Based on this method, the anisotropic complex permittivity of a carbon fiber/epoxy composite during microwave curing was accurately determined. Statistical results indicated that both the dielectric constant and dielectric loss of the composite increased at the initial curing stage, peaked at the maximum reaction rate point and decreased finally during the microwave curing process. Corresponding mechanism has also been systematically investigated in this work.

Comparison of the heat generation of light curing units.

Science.gov (United States)

Bagis, Bora; Bagis, Yildirim; Ertas, Ertan; Ustaomer, Seda

2008-02-01

The aim of this study was to evaluate the heat generation of three different types of light curing units. Temperature increases were recorded from a distance of 1 mm from a thermocouple to the tip of three different types of light curing units including one quartz-tungsten halogen (QTH), one plasma arc (PAC), and one light emitting diode (LED) unit. An experimental model was designed to fix the 1 mm distance between the tip of the light curing units and the thermocouple wire. Temperature changes were recorded in 10 second intervals up to 40 seconds. (10, 20, 30, and 40 seconds). Temperature measurements were repeated three times for every light curing unit after a one hour standby period. Statistical analysis of the results was performed using the analysis of variance (ANOVA) and the Bonferroni Test. The highest temperature rises (54.4+/-1.65 degrees C) occurred during activation of a PAC light curing unit for every test period (pdamage to the pulp.

Photo-cured pH-responsive polyampholyte-coated membranes for controlled release of drugs with different molecular weights and charges

International Nuclear Information System (INIS)

Ng, Loo-Teck; Ng, Kheng-Seong

2008-01-01

Intelligent drug delivery membranes were synthesised by photocuring poly(acrylic acid) (PAA) or polyampholytes comprised of copolymers of acrylic acid (AA)/2-(diethylamino)ethyl methacrylate (DEAEMA) with varying monomeric compositions onto poly(2-hydroxyethyl methacrylate) (PHEMA) membranes, each with model drugs of different molecular weights and charges being incorporated. pH-responsive release behaviours of the model drugs which included methylene blue (cationic), metanil yellow (anionic) and caffeine (neutral) were studied. Only membranes with methylene blue and caffeine incorporated displayed clear pH-responsive releases though all coatings. This study demonstrates that drug diffusion through pH-responsive membranes depends to a large extent on the attractive interaction between the drug and the appropriate functional group/s in the coating

Influence of curing protocol on selected properties of light-curing polymers

DEFF Research Database (Denmark)

Dewaele, Magali; Asmussen, Erik; Peutzfeldt, Anne

2009-01-01

The purpose of this study was to investigate the effect of light-curing protocol on degree of conversion (DC), volume contraction (C), elastic modulus (E), and glass transition temperature (T(g)) as measured on a model polymer. It was a further aim to correlate the measured values with each other....

Effect of In-Situ Curing on Compressive Strength of Reactive Powder Concrete

Directory of Open Access Journals (Sweden)

Bali Ika

2016-01-01

Full Text Available A development of Reactive Powder Concrete (RPC currently is the use of quartz powder as a stabilizing agent with the content to cement ratio of 30% and steam curing method in an autoclave temperature of 250ºC which produced a high compressive strength of 180 MPa. That RPC can be generated due to one reason for using the technique of steam curing in an autoclave in the laboratory. This study proposes in-situ curing method in order the curing can be applied in the field and with a reasonable compressive strength results of RPC. As the benchmarks in this study are the curing methods in laboratory that are steam curing of 90°C for 8 hours (C1, and water curing for 28 days (C2. For the in-situ curing methods that are covering with tarpaulins and flowed steam of 3 hours per day for 7 days (C3, covering with wet sacks for 28 days (C4, and covering with wet sacks for 28 days for specimen with unwashed sand as fine aggregate (C5. The comparison of compressive strength of the specimens in this study showed compressive strength of RPC with in-situ steam curing (101.64 MPa close to the compressive strength of RPC with steam curing in the laboratory with 8.2% of different. While in-situ wet curing compared with the water curing in laboratory has the different of 3.4%. These results indicated that the proposed in-situ curing methods are reasonable good in term of the compressive strength that can be achieved.

Temperature rise produced by different light-curing units through dentin.

Science.gov (United States)

Yazici, A Rüya; Müftü, Ali; Kugel, Gerard

2007-11-01

This study investigated the temperature rise caused by different light curing units and the temperature increase in dentin of different thicknesses. Dentin discs of 1.0 and 2.0 mm thicknesses were prepared from extracted human mandibular molars. Temperatures were recorded directly at the surface of the light guide tip, under dentin discs with different thicknesses, and through a sandwich composed of 2 mm thick cured composite and dentin using a K-type thermocouple. The curing units used were two quartz-tungsten-halogen lights (Spectrum and Elipar Trilight-ET) and a light-emitting diode (LED). The highest temperature rise was observed under a Mylar strip using ET standard mode. Under 1 and 2 mm thick dentin barriers, the lowest temperature rise was measured for the LED curing light. Significant differences in temperature rise existed among all curing units except between the Spectrum and ET exponential modes under a 1 mm thick dentin barrier with cured composite. Temperature rises were insignificant between the Spectrum and ET exponential modes and between two modes of Trilight when the same experimental setup was used under a 2 mm thick dentin barrier. For all curing units, temperature elevation through 2 mm of dentin was less than for 1 mm of dentin thickness. The ET standard mode produced the highest and the LED produced the lowest temperature rise for all tested conditions. The thickness of dentin and light-curing unit might affect temperature transmission.

Monitoring the Cure State of Thermosetting Resins by Ultrasound.

Science.gov (United States)

Lionetto, Francesca; Maffezzoli, Alfonso

2013-09-05

The propagation of low intensity ultrasound in a curing resin, acting as a high frequency oscillatory excitation, has been recently proposed as an ultrasonic dynamic mechanical analysis (UDMA) for cure monitoring. The technique measures sound velocity and attenuation, which are very sensitive to changes in the viscoelastic characteristics of the curing resin, since the velocity is related to the resin storage modulus and density, while the attenuation is related to the energy dissipation and scattering in the curing resin. The paper reviews the results obtained by the authors' research group in the last decade by means of in-house made ultrasonic set-ups for both contact and air-coupled ultrasonic experiments. The basics of the ultrasonic wave propagation in polymers and examples of measurements of the time-evolution of ultrasonic longitudinal modulus and chemical conversion of different thermosetting resins are presented. The effect of temperature on the cure kinetics, the comparison with rheological, low frequency dynamic mechanical and calorimetric results, and the correlation between ultrasonic modulus and crosslinking density will be also discussed. The paper highlights the reliability of ultrasonic wave propagation for monitoring the physical changes taking place during curing and the potential for online monitoring during polymer and polymer matrix composite processing.

Monitoring the Cure State of Thermosetting Resins by Ultrasound

Directory of Open Access Journals (Sweden)

Alfonso Maffezzoli

2013-09-01

Full Text Available The propagation of low intensity ultrasound in a curing resin, acting as a high frequency oscillatory excitation, has been recently proposed as an ultrasonic dynamic mechanical analysis (UDMA for cure monitoring. The technique measures sound velocity and attenuation, which are very sensitive to changes in the viscoelastic characteristics of the curing resin, since the velocity is related to the resin storage modulus and density, while the attenuation is related to the energy dissipation and scattering in the curing resin. The paper reviews the results obtained by the authors’ research group in the last decade by means of in-house made ultrasonic set-ups for both contact and air-coupled ultrasonic experiments. The basics of the ultrasonic wave propagation in polymers and examples of measurements of the time-evolution of ultrasonic longitudinal modulus and chemical conversion of different thermosetting resins are presented. The effect of temperature on the cure kinetics, the comparison with rheological, low frequency dynamic mechanical and calorimetric results, and the correlation between ultrasonic modulus and crosslinking density will be also discussed. The paper highlights the reliability of ultrasonic wave propagation for monitoring the physical changes taking place during curing and the potential for online monitoring during polymer and polymer matrix composite processing.

Solid-state /sup 13/C NMR study of cured resorcinol-formaldehyde resins

Energy Technology Data Exchange (ETDEWEB)

Lippmaa, H.; Samoson, A.

1988-08-01

The curing process generally follows the pattern observed in the stage of prepolymer formation. Catalysts (NaOH, hexa, Mg(OCOCH/sub 3/)/sub 2/) that have no substantial influence on the isomeric composition of the resorcinol-formaldehyde prepolymers, do not affect the isomeric composition of the cured resins to any significant extent either. Isomeric composition of the cured resins depends mostly on the presence of water during the curing process, necessary for depolymerisation of the added paraformaldehyde. Curing in the melt leads to enhanced 2-substitution in the 1,3-dihydroxybenzene rings. In the /sup 13/C NMR spectra of cured powdered samples, the tendency of 5-methylresorcinol to form oligomers with a higher degree of 2-substitution than resorcinol is clearly apparent. Polycondensation process continues in the powdered resins after initial curing until complete consumption of all formaldehyde. Curing of phenol-formaldehyde resols proceeds through intermediate dimethylene ether formation.

Efficiency of light curing units in a government dental school.

Science.gov (United States)

Nassar, Hani M; Ajaj, Reem; Hasanain, Fatin

2018-01-01

The light intensity of a light-curing unit is a crucial factor that affects the clinical longevity of resin composites. This study aimed to investigate the efficiency of light-curing units in use at a local governmental dental school for curing conventional and bulk-fill resin materials. A total of 166 light-curing units at three locations were examined, and the brand, type, clinic location, diameter of curing tip, tip cleanliness (using a visual score), and the output (in mW/cm 2 using a digital radiometer) were recorded. Only 23.5% of the units examined had clean tips, with the graduate student clinical area containing the highest percentage of clean tips. Further, tips with poor cleanliness score values were associated with significantly lower output intensities. A small percentage (9.4%) of units was capable of producing intensities higher than 1,200 mW/cm 2 and lower than 600 mW/cm 2 (7.6%). The majority of the low intensity units were located in the undergraduate student area, which also contained the highest number of units with intensities between 900 and 1,200 mW/cm 2 . The output of all the units in service was satisfactory for curing conventional resin composites, and most units were capable of curing bulk-fill resin materials.

Pulp chamber temperature rise during curing of resin-based composites with different light-curing units.

Science.gov (United States)

Durey, Kathryn; Santini, Ario; Miletic, Vesna

2008-01-01

The purpose of the present study was to measure the intrapulpal temperature rise occurring during polymerisation of different shades of resin-based composites (RBCs), and two light-emitting diode (LED) units. Seventy non-carious permanent molars, that had been extracted for orthodontic purposes and stored in 2% thymol for not more than four months, were selected. Patient age range was 11-18 years. Standard cavity preparation with standardised remaining dentine thickness and placement of thermocouples (TCs) was prepared using a novel split-tooth technique. Cavities were filled with one of two shades of RBC (A2 and C4, Filtek Z250, 3M ESPE, Seefeld, Germany), and cured with two LED high-intensity units (Elipar Freelight2, 3M ESPE, Seefeld, Germany; Bluephase, Ivoclar Vivadent, Schaan, Liechtenstein) and a conventional halogen light-curing unit (LCU) (Prismetics Lite 2, Dentsply, Weybridge, Surrey, UK) as a control. Pulp temperature rises during bonding [A2 results: H;2.67/0.48:E;5.24/1.32;B;5.99/1.61] were always greater than during RBC curing [A2 results: 2.44/0.63;E3.34/0.70;B3.38/0.60], and these were significant for both LED lights but not for the halogen control, irrespective of shade (Mann-Whitney test: 95% confidence limits). Temperature rises were at times in excess of the values normally quoted as causing irreversible pulp damage. Pulp temperature rises during bonding were higher with the LED lights than with the halogen control. There was no significant difference in temperature rise between the two LED lights when bonding but there was a significant difference between the two LED lights and the halogen control LCUs (Kruskal-Wallis Test: 95% confidence limits). The results support the view that there is a potential risk for heat-induced pulpal injury when light-curing RBCs. The risk is greater during bonding and with high energy, as compared to low-energy output systems. As the extent of tolerable thermal trauma by the pulp tissues is unknown, care and

Electron beam-cured coating

International Nuclear Information System (INIS)

Kishi, Naoyuki

1976-01-01

The method for hardening coatings by the irradiation with electron beams is reviewed. The report is divided into seven parts, namely 1) general description and characteristics of electron beam-cured coating, 2) radiation sources of curing, 3) hardening conditions and reaction behaviour, 4) uses and advantages, 5) latest trends of the industry, 6) practice in the field of construction materials, and 7) economy. The primary characteristics of the electron beam hardening is that graft reaction takes place between base resin and coating to produce strong adhesive coating without any pretreatment. A variety of base resins are developed. High class esters of acrylic acid monomers and methacrylic acid monomers are mainly used as dilutants recently. At present, scanning type accelerators are used, but the practical application of the system producing electron beam of curtain type is expected. The dose rate dependence, the repetitive irradiation and the irradiation atmosphere are briefly described. The filed patent applications on the electron beam hardening were analyzed by the officer of Japan Patent Agency. The production lines for coatings by the electron beam hardening in the world are listed. In the electron beam-cured coating, fifty percent of given energy is consumed effectively for the electron beam hardening, and the solvents discharged from ovens and polluting atmosphere are not used, because the paints of high solid type is used. The running costs of the electron beam process are one sixth of the thermal oven process. (Iwakiri, K.)

Degree of conversion of resin-based materials cured with dual-peak or single-peak LED light-curing units.

Science.gov (United States)

Lucey, Siobhan M; Santini, Ario; Roebuck, Elizabeth M

2015-03-01

There is a lack of data on polymerization of resin-based materials (RBMs) used in paediatric dentistry, using dual-peak light-emitting diode (LED) light-curing units (LCUs). To evaluate the degree of conversion (DC) of RBMs cured with dual-peak or single-peak LED LCUs. Samples of Vit-l-escence (Ultradent) and Herculite XRV Ultra (Kerr) and fissure sealants Delton Clear and Delton Opaque (Dentsply) were prepared (n = 3 per group) and cured with either one of two dual-peak LCUs (bluephase(®) G2; Ivoclar Vivadent or Valo; Ultradent) or a single-peak (bluephase(®) ; Ivoclar Vivadent). High-performance liquid chromatography and nuclear magnetic resonance spectroscopy were used to confirm the presence or absence of initiators other than camphorquinone. The DC was determined using micro-Raman spectroscopy. Data were analysed using general linear model anova; α = 0.05. With Herculite XRV Ultra, the single-peak LCU gave higher DC values than either of the two dual-peak LCUs (P < 0.05). Both fissure sealants showed higher DC compared with the two RBMs (P < 0.05); the DC at the bottom of the clear sealant was greater than the opaque sealant, (P < 0.05). 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin(®) TPO) was found only in Vit-l-escence. Dual-peak LED LCUs may not be best suited for curing non-Lucirin(®) TPO-containing materials. A clear sealant showed a better cure throughout the material and may be more appropriate than opaque versions in deep fissures. © 2014 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Consumer satisfaction with dry-cured ham in five European countries.

Science.gov (United States)

Resano, H; Pérez-Cueto, F J A; Sanjuán, A I; de Barcellos, M D; Grunert, K G; Verbeke, W

2011-04-01

The objective is to investigate consumer satisfaction with dry-cured ham in five European countries. A logistic regression model has been fitted using data collected through a cross-sectional web-based survey carried out in Belgium, Germany, Denmark, Poland and Greece during January 2008 (n=2437 of which 2156 were dry-cured ham consumers). Satisfaction was evaluated as overall satisfaction, as well as specific satisfaction with healthfulness, price, convenience and taste. The findings show that the main determinant of overall satisfaction is taste satisfaction, hence, producers are recommended to focus on matching sensory acceptability of dry-cured ham. No significant between-country differences were found, reflecting the wide availability of this product in all countries. Consumer characteristics influenced their level of satisfaction. Men, older (age > 52 years) and frequent consumers of dry-cured ham consumption were more likely to be satisfied with dry-cured ham. Consumers trust the butcher's advice and they preferred purchasing dry-cured ham at a butcher shop rather than in a supermarket. © 2010 The American Meat Science Association. Published by Elsevier Ltd. All rights reserved.

Optimal cure cycle design of a resin-fiber composite laminate

Science.gov (United States)

Hou, Jean W.; Sheen, Jeenson

1987-01-01

A unified computed aided design method was studied for the cure cycle design that incorporates an optimal design technique with the analytical model of a composite cure process. The preliminary results of using this proposed method for optimal cure cycle design are reported and discussed. The cure process of interest is the compression molding of a polyester which is described by a diffusion reaction system. The finite element method is employed to convert the initial boundary value problem into a set of first order differential equations which are solved simultaneously by the DE program. The equations for thermal design sensitivities are derived by using the direct differentiation method and are solved by the DE program. A recursive quadratic programming algorithm with an active set strategy called a linearization method is used to optimally design the cure cycle, subjected to the given design performance requirements. The difficulty of casting the cure cycle design process into a proper mathematical form is recognized. Various optimal design problems are formulated to address theses aspects. The optimal solutions of these formulations are compared and discussed.

Evaluation of shear bond strength of orthodontic brackets using trans-illumination technique with different curing profiles of LED light-curing unit in posterior teeth.

Science.gov (United States)

Heravi, Farzin; Moazzami, Saied Mostafa; Ghaffari, Negin; Jalayer, Javad; Bozorgnia, Yasaman

2013-11-21

Although using light-cured composites for bonding orthodontic brackets has become increasingly popular, curing light cannot penetrate the metallic bulk of brackets and polymerization of composites is limited to the edges. Limited access and poor direct sight may be a problem in the posterior teeth. Meanwhile, effectiveness of the trans-illumination technique is questionable due to increased bucco-lingual thickness of the posterior teeth. Light-emitting diode (LED) light-curing units cause less temperature rise and lower risk to the pulpal tissue. The purpose of this study was to evaluate the clinical effectiveness of trans-illumination technique in bonding metallic brackets to premolars, using different light intensities and curing times of an LED light-curing unit. Sixty premolars were randomly divided into six groups. Bonding of brackets was done with 40- and 80-s light curing from the buccal or lingual aspect with different intensities. Shear bond strengths of brackets were measured using a universal testing machine. Data were analyzed by one-way analysis of variance test and Duncan's post hoc test. The highest shear bond belonged to group 2 (high intensity, 40 s, buccal) and the lowest belonged to group 3 (low intensity, 40 s, lingual). Bond strength means in control groups were significantly higher than those in experimental groups. In all experimental groups except group 6 (80 s, high intensity, lingual), shear bond strength was below the clinically accepted values. In clinical limitations where light curing from the same side of the bracket is not possible, doubling the curing time and increasing the light intensity during trans-illumination are recommended for achieving acceptable bond strengths.

Assessment of Salmonella survival in dry-cured Italian salami.

Science.gov (United States)

Bonardi, S; Bruini, I; Bolzoni, L; Cozzolino, P; Pierantoni, M; Brindani, F; Bellotti, P; Renzi, M; Pongolini, S

2017-12-04

The inactivation of Salmonella during curing of Italian traditional pork salami was investigated. A total of 150 batches of ground raw meat (GRM) used for salami manufacturing by four producers were tested for Salmonella by real-time PCR followed by ISO 6579 cultural confirmation and MPN enumeration. Salami produced with Salmonella positive GRMs were re-tested at the end of their curing period. Aw, pH and NaCl content were also measured. Detection of Salmonella was performed testing both 25 and 50g of the samples. By Real-Time PCR 37% of the GRMs resulted positive, but cultural detection of Salmonella was obtained in 14% of the samples only. Salmonella enumeration ranged from 31 MPN/g to Salmonella in 100% of all positive samples, vs. 62% of ISO-25g. Salami made of the contaminated GRMs were 29% Salmonella-positive, as most batches of salami produced with Salmonella-positive GRMs resulted negative after regular curing (20-48days). Overall, 13% of salami produced with Salmonella-contaminated GRMs were positive. They belonged to six batches, which turned out negative after prolonged curing ranging between 49 and 86days. Salmonella enumeration in salami ranged from 8.7 MPN/g to Salmonella in cured salami (p value: >0.05). The most common Salmonella serovars in GRMs were Derby (52%), Typhimurium monophasic variant 4, (Barbuti et al., 1993), 12:i:- (19%) and Stanley (10%). Salmonella Derby (56%), London, Branderup, Panama (13%, respectively) and Goldcoast (6%) were most frequent in cured salami. The study showed negative correlation between real-time CT values and cultural confirmation of Salmonella, as well as the importance of sample size for Salmonella detection. Among considered factors with possible effect on the occurrence of Salmonella in salami, statistical analysis revealed a role for aw in salami and for Salmonella load in GRMs, while pH and NaCl content did not significantly affect the probability of finding Salmonella in dry-cured salami in the context of

Process Formulations And Curing Conditions That Affect Saltstone Properties

Energy Technology Data Exchange (ETDEWEB)

Reigel, M. M.; Pickenheim, B. R.; Daniel, W. E.

2012-09-28

The first objective of this study was to analyze saltstone fresh properties to determine the feasibility of reducing the formulation water to premix (w/p) ratio while varying the amount of extra water and admixtures used during processing at the Saltstone Production Facility (SPF). The second part of this study was to provide information for understanding the impact of curing conditions (cure temperature, relative humidity (RH)) and processing formulation on the performance properties of cured saltstone.

Radiation curing technology progress and its industrial applications in Japan

International Nuclear Information System (INIS)

Ukachi, Takashi

2003-01-01

Optics, electronics and display industries are now the driving forces for the Japanese radiation curing technology. The purpose of this paper is to overview the newly developed radiation curing technology in Japan, in particular, its industrial applications, and to present the market figures in radiation curing applications, which were surveyed by RadTech Japan in 2002 afresh. (author)

Electron beam curing - taking good ideas to the manufacturing floor

International Nuclear Information System (INIS)

Saunders, C.; Lopata, V.; Barnard, J.; Stepanik, T.

2000-01-01

Acsion is exploiting several emerging electron beam EB applications ranging from composite curing and repair to viscose manufacturing. EB curing of composite structures offers several advantages: significantly reduced curing times; improvements in part quality and performance; reduced environmental and health concerns; improvements in material handling; and reduced overall manufacturing costs compared to thermal curing. The aerospace industry is developing EB technology in all of their market sectors, including military aviation and space products. Some specific products include cryogenic fuel tanks, improved canopy frames for jet aircraft, and the all-composite military aircraft. This paper discusses each of these opportunities. (author)

Variable selection for mixture and promotion time cure rate models.

Science.gov (United States)

Masud, Abdullah; Tu, Wanzhu; Yu, Zhangsheng

2016-11-16

Failure-time data with cured patients are common in clinical studies. Data from these studies are typically analyzed with cure rate models. Variable selection methods have not been well developed for cure rate models. In this research, we propose two least absolute shrinkage and selection operators based methods, for variable selection in mixture and promotion time cure models with parametric or nonparametric baseline hazards. We conduct an extensive simulation study to assess the operating characteristics of the proposed methods. We illustrate the use of the methods using data from a study of childhood wheezing. © The Author(s) 2016.

Nitrite-cured color and phosphate-mediated water binding of pork muscle proteins as affected by calcium in the curing solution.

Science.gov (United States)

Zhao, Jing; Xiong, Youling L

2012-07-01

Calcium is a mineral naturally present in water and may be included into meat products during processing thereby influencing meat quality. Phosphates improve myofibril swelling and meat water-holding capacity (WHC) but can be sensitive to calcium precipitation. In this study, pork shoulder meat was used to investigate the impact of calcium at 0, 250, and 500 ppm and phosphate type [sodium pyrophosphate (PP), tripolyphosphate (TPP), and hexametaphopshate (HMP)] at 10 mM on nitrite-cured protein extract color at various pH levels (5.5, 6.0, and 6.5) and crude myofibril WHC at pH 6.0. Neither calcium nor phosphates present in the curing brines significantly affected the cured color. Increasing the pH tended to promote the formation of metmyoglobin instead of nitrosylmyoglobin. The ability of PP to enhance myofibril WHC was hampered (P meat products. Although not affecting nitrite-cured color, calcium hampers the efficacy of phosphates to promote water binding by muscle proteins, underscoring the importance of water quality for brine-enhanced meat products. © 2012 Institute of Food Technologists®

Influence of curing rate of resin composite on the bond strength to dentin

DEFF Research Database (Denmark)

Benetti, Ana Raquel; Asmussen, E; Peutzfeldt, A

2007-01-01

@ 1000 mW/cm2) for all groups. A split Teflon mold was clamped to the treated dentin surface and filled with resin composite. The rate of cure was varied, using one of four LED-curing units of different power densities. The rate of cure was also varied using the continuous or pulse-delay mode....... In continuous curing mode, in order to give an energy density totaling 16 J/cm2, the power densities (1000, 720, 550, 200 mW/cm2) emitted by the various curing units were compensated for by the light curing period (16, 22, 29 or 80 seconds). In the pulse-delay curing mode, two seconds of light curing at one...... of the four power densities was followed by a one-minute interval, after which light cure was completed (14, 29, 27 or 78 seconds), likewise, giving a total energy density of 16 J/cm2. The specimens produced for each of the eight curing protocols and two resin composites (Tetric EvoCeram, Ivoclar Vivadent...

Study on curing reaction of 4-aminophenoxyphthalonitrile/bisphthalonitrile

Institute of Scientific and Technical Information of China (English)

Xiao

2010-01-01

A series of phthalonitrile blending resins were prepared from 4-aminophenoxyphthalonitrile (APN) and 4,4'-bis (3,4-dicyanophenoxy)biphenyl (BPH) by directly powder-mixing and copolymerization. Differential scanning calorimeter (DSC) and dynamic rheology were used to study the curing reaction behaviors of APN/BPH blends, and the results indicated that the introduction of APN accelerated the curing rate of BPH, and the existence of BPH decreased the curing temperature of APN/BPH systems. The thermal stability of postcured APN/BPH resins was investigated by thermogravimetric analysis (TGA), and the TGA results indicated that the crosslinked polymers of APN/BPH systems possessed good thermal stability.

The Effect of Rubber Mixing Process on The Curing Characteristics of Natural Rubber

Directory of Open Access Journals (Sweden)

Abu Hasan

2013-04-01

Full Text Available This research is aimed at studying the relationship between rubber mixing processes and curing characteristics of natural rubber. The curing characteristic analysis was carried out through a natural rubber formula having been masticated and mixed, followed by curing. As many as four mastication methods were finely applied; each respected four sequences of rubber mixing process. In the first method, rubber was masticated for 5 minutes and then rubber chemicals and carbon black N 330 were  simultaneously added. In the second and the third methods, rubber was masticated for 1 minute and then carbon blacks and rubber chemicals were also simultaneously added but using different type of fillers. In the fourth method, rubber was masticated for 3 minutes and then rubber chemicals and carbon black were subsequently added. The additions of rubber chemicals and carbon blacks to the masticated rubber were distinguished by the sequence and time allocated for each mixing process. The carbon blacks were added in two stages by which 10 phr was added first and the remaining 40 phr was added later along with oil. In another method, ratios of the carbon blacks addition (as done in the first  and the second stages were 20:30, 30:20, and 40:10. The examination results showed that rubber mixing process gave an impact on the changes of curing characteristics. They were much affected by the method of carbon black addition. The mixing temperature also had an effect on both curing time and curing rate in which the higher the mixing temperature, the lower the curing time and curing rate. Vulcanization temperature also affected the curing time and curing rate in which the higher the vulcanization temperature, the lower the curing time and the higher the curing rate. Lastly, particle size of carbon black also gave an impact on the curing time and curing rate in which the smaller the particle size, the lower the curing time and the higher the curing rate.

Method for curing polymers using variable-frequency microwave heating

Science.gov (United States)

Lauf, Robert J.; Bible, Don W.; Paulauskas, Felix L.

1998-01-01

A method for curing polymers (11) incorporating a variable frequency microwave furnace system (10) designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity (34). By varying the frequency of the microwave signal, non-uniformities within the cavity (34) are minimized, thereby achieving a more uniform cure throughout the workpiece (36). A directional coupler (24) is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter (30) is provided for measuring the power delivered to the microwave furnace (32). A second power meter (26) detects the magnitude of reflected power. The furnace cavity (34) may be adapted to be used to cure materials defining a continuous sheet or which require compressive forces during curing.

Effect of commercially available egg cures on the survival of juvenile salmonids.

Directory of Open Access Journals (Sweden)

Shaun Clements

Full Text Available There is some concern that incidental consumption of eggs cured with commercially available cures for the purpose of sport fishing causes mortality in juvenile salmon. We evaluated this by feeding juvenile spring Chinook (Oncorhynchus tshawytscha and steelhead (O. mykiss with eggs cured with one of five commercially available cures. We observed significant levels of mortality in both pre-smolts and smolts. Depending on the experiment, 2, 3, or 4 of the cures were associated with mortality. Mortality tended to be higher in the smolts than in the parr, but there was no clear species effect. The majority of mortality occurred within the first 10 d of feeding. Removal of sodium sulfite from the cure significantly reduced the level of mortality. Soaking the eggs prior to feeding did not reduce mortality. We observed a clear relationship between the amount of cured egg consumed each day and the survival time. We conclude that consumption of eggs cured with sodium sulfite has the potential to cause mortality in juvenile steelhead and Chinook salmon in the wild.

Effect of commercially available egg cures on the survival of juvenile salmonids

Science.gov (United States)

Clements, S.; Chitwood, R.; Schreck, C.B.

2011-01-01

There is some concern that incidental consumption of eggs cured with commercially available cures for the purpose of sport fishing causes mortality in juvenile salmon. We evaluated this by feeding juvenile spring Chinook (Oncorhynchus tshawytscha) and steelhead (O. mykiss) with eggs cured with one of five commercially available cures. We observed significant levels of mortality in both pre-smolts and smolts. Depending on the experiment, 2, 3, or 4 of the cures were associated with mortality. Mortality tended to be higher in the smolts than in the parr, but there was no clear species effect. The majority of mortality occurred within the first 10 d of feeding. Removal of sodium sulfite from the cure significantly reduced the level of mortality. Soaking the eggs prior to feeding did not reduce mortality. We observed a clear relationship between the amount of cured egg consumed each day and the survival time. We conclude that consumption of eggs cured with sodium sulfite has the potential to cause mortality in juvenile steelhead and Chinook salmon in the wild.

Dsc cure kinetics of an unsaturated polyester resin using empirical kinetic model

International Nuclear Information System (INIS)

Abdullah, I.

2015-01-01

In this paper, the kinetics of curing of unsaturated polyester resin initiated with benzoyl peroxide was studied. In case of unsaturated polyester (UP) resin, isothermal test alone could not predict correctly the curing time of UP resin. Therefore, isothermal kinetic analysis through isoconventional adjustment was used to correctly predict the curing time and temperature of UP resin. Isothermal kinetic analysis through isoconversional adjustment indicated that 97% of UP resin cures in 33 min at 120 degree C. Curing of UP resin through microwaves was also studied and found that 67% of UP resin cures in 1 min at 120 degree C. The crosslinking reaction of UP resin is so fast at 120 degree C that it becomes impossible to predict correctly the curing time of UP resin using isothermal test and the burial of C=C bonds in microgels makes it impossible to be fully cured by microwaves at 120 degree C. The rheological behaviour of unsaturated polyester resin was also studied to observe the change in viscosity with respect to time and temperature. (author)

Efficiency of Sodium Polyacrylate to Improve Durability of Concrete under Adverse Curing Condition

Directory of Open Access Journals (Sweden)

Tanvir Manzur

2015-01-01

Full Text Available The conventional external curing process requires supply of large amount of water in addition to mixing water as well as strict quality control protocol. However, in a developing country like Bangladesh, many local contractors do not have awareness and required knowledge on importance of curing which often results in weaker concrete with durability issues. Moreover, at times it is difficult to maintain proper external curing process due to nonavailability of water and skilled laborer. Internal curing can be adopted under such scenario since this method is simple and less quality intensive. Usually, naturally occurring porous light weight aggregates (LWA are used as internal curing agent. However, naturally occurring LWA are not available in many countries like Bangladesh. Under these circumstances, Super Absorbent Polymer (SAP can be utilized as an alternative internal curing agent. In this study, sodium polyacrylate (SP as SAP has been used to produce internally cured concrete. Desorption isotherm of SP has been developed to investigate its effectiveness as internal curing agent. Test results showed that internally cured concrete with SP performed better in terms of both strength and durability as compared to control samples when subjected to adverse curing conditions where supply of additional water for external curing was absent.

Warpage of QFN Package in Post Mold Cure Process of integrated circuit packaging

Science.gov (United States)

Sriwithoon, Nattha; Ugsornrat, Kessararat; Srisuwitthanon, Warayoot; Thonglor, Panakamon

2017-09-01

This research studied about warpage of QFN package in post mold cure process of integrated circuit (IC) packages using pre-plated (PPF) leadframe. For IC package, epoxy molding compound (EMC) are molded by cross linking of compound stiffness but incomplete crosslinked network and leading the fully cured thermoset by post mold cure (PMC) process. The cure temperature of PMC can change microstructure of EMC in term of stress inside the package and effect to warpage of the package due to coefficient of thermal expansion (CTE) between EMC and leadframe. In experiment, cure temperatures were varied to check the effect of internal stress due to different cure temperature after completed post mold cure for TDFN 2×3 8L. The cure temperature were varied with 180 °C, 170 °C, 160 °C, and 150°C with cure time 4 and 6 hours, respectively. For analysis, the TDFN 2×3 8L packages were analyzed the warpage by thickness gauge and scanning acoustic microscope (SAM) after take the test samples out from the oven cure. The results confirmed that effect of different CTE between EMC and leadframe due to different cure temperature resulting to warpage of the TDFN 2×3 8L packages.

Inkjet 3D printing of UV and thermal cure silicone elastomers for dielectric elastomer actuators

Science.gov (United States)

McCoul, David; Rosset, Samuel; Schlatter, Samuel; Shea, Herbert

2017-12-01

Dielectric elastomer actuators (DEAs) are an attractive form of electromechanical transducer, possessing high energy densities, an efficient design, mechanical compliance, high speed, and noiseless operation. They have been incorporated into a wide variety of devices, such as microfluidic systems, cell bioreactors, tunable optics, haptic displays, and actuators for soft robotics. Fabrication of DEA devices is complex, and the majority are inefficiently made by hand. 3D printing offers an automated and flexible manufacturing alternative that can fabricate complex, multi-material, integrated devices consistently and in high resolution. We present a novel additive manufacturing approach to DEA devices in which five commercially available, thermal and UV-cure DEA silicone rubber materials have been 3D printed with a drop-on-demand, piezoelectric inkjet system. Using this process, 3D structures and high-quality silicone dielectric elastomer membranes as thin as 2 μm have been printed that exhibit mechanical and actuation performance at least as good as conventionally blade-cast membranes. Printed silicone membranes exhibited maximum tensile strains of up to 727%, and DEAs with printed silicone dielectrics were actuated up to 6.1% area strain at a breakdown strength of 84 V μm-1 and also up to 130 V μm-1 at 2.4% strain. This approach holds great potential to manufacture reliable, high-performance DEA devices with high throughput.

Electron curing for high speed paper, film and foil converting

International Nuclear Information System (INIS)

Nablo, S.V.; Tripp, E.P.

1979-01-01

The status of self-shielded, compact electron processors for flexible web converting applications is reviewed. The uses of these units for a variety of laminating applications are described, with emphasis on the application techniques appropriate for low weight, (1 to 2 gm/m 2 ) 100% convertible adhesives. Performance data for electron cured adhesives with polyester/polyethylene systems is presented and compared with conventional urethane systems. The unique surface features of electron cured gravure coatings applied and cured at high speed are discussed, with reference to both paper and film substrates. An important advantage of electron curing of buried adhesive layers is the process quality control permitted by this 'all-electric' system. The performance characteristics of curing atmosphere control (inerting) for coatings are reviewed. Industrial experience with these processors has shown that effective inerting of coated flexible webs at speeds to 250 m/minute is both practical and economical. (author)

The effect of curing conditions on the durability of high performance concrete

Science.gov (United States)

Bumanis, G.; Bajare, D.

2017-10-01

This study researches compressive strength and durability of the high strength self-compacting concrete (SCC) impacted at early stage by the curing conditions. The mixture compositions of metakaolin containing waste and cenospheres as partial cement replacement (15 wt%) were compared to reference SCC with 100% cement. The specimens prepared in advance were demoulded 24h after casting of the SCC and the specific curing conditions were applied for up to 28 days: standard water curing at 20°C (i); indoor curing at 20°C, RH 60% (ii) and low temperature air curing (2°C) at RH 60% (iii). Results indicate that at early stage (14 days) indoor curing conditions increase compressive strength of the SCC whilst no strength loss has been detected even at a low temperature curing. The further strength gain has been substantially reduced for samples cured indoor and at a low temperature with significant variation observed for long term compressive strength (180 days). The metakaolin containing waste has proved to be an effective partial cement replacement and it has improved strength gain even at a low temperature curing. Meanwhile cenospheres have reduced the SCC strength and with no positive effect on strength observed within the standard term. Freeze-thaw durability and resistance to the chloride penetration have been improved for the SCC cured at low temperature. The SCC with metakaolin containing waste has proved to be the most durable thus demonstrating importance of effective micro filler use.

Thermal stabilities of various rubber vulcanization cured by sulfur, peroxide and gamma radiation

International Nuclear Information System (INIS)

Basfar, A.A.; Shamshad Ahmed; Abdel Aziz, M.M.

1999-01-01

Sulfur and peroxide-cured rubber vulcanizates of NR and EPDM were obtained by blending the elastomers with fillers, antioxidants and appropriate accelerators, followed by vulcanization at 150 - 160 degree C. Blends of the same elastomers with appropriate co-agents and additives were also cured by gamma radiation at 150 and 200 kGy. A comparison of the thermal stabilities of these vulcanizates prepared by different curing techniques has been made by thermogravimetric analysis (TGA), assessed on the basis of comparison of DTG peak maxima, temperature for loss of 50% mass and actual thermal curves. The comparison reveals that the sulfur-cured vulcanizates are less thermally stable than their peroxide-cured counterparts. This may be attributed to the presence of a stronger C-C bond in case of peroxide-cured vulcanizates compared to weaker C-S sub x-C bond in case of sulfur-cured vulcanizates. However, compared to peroxide-cured vulcanizates, radiation-cured formulations demonstrated much improved thermal stability. This may originate from the existence of more uniformly distributed crosslinks and the enhanced rate of crosslink formation in the radiation process as compared to peroxide curing. In all the formulations whether sulfur, peroxide or radiation-cured, the natural rubber vulcanizates were found to be thermally much inferior to the synthetic contender, EPDM. Influence of variation of the amount of co-agent and other additives on the thermal stabilities of formulations of radiation cured NR and EPDM vulcanizates was also investigated

Techno-economic benefits of radiation curing: a comparison studies

Energy Technology Data Exchange (ETDEWEB)

French, D [Universal Wood Inc., Lousville (United States)

1994-12-31

In comparing radiation cure versus conventional heat cure systems, the factors are considered in this studies i.e. environmental laws - includes the future regulations concerning volatile organic emissions and waste disposal may weigh heavily in the decision.

Electron Beam curing of intaglio inks

International Nuclear Information System (INIS)

O'Brien, T.

1984-01-01

Press trials conducted by the US Bureau of Engraving and Printing at the National Bank of Denmark in September 8-21, 1982, clearly indicated the feasibility of Electron Beam (EB) curing for web intaglio printing. These trials, some at continuous press runs of up to six hours, gave positive results for virtually all our requirements including: print quality, press speeds, ability to print both sides of the web on one pass through a press, acceptable ink curing at one megarad or less, and minimum substrate deterioration or loss of moisture. In addition, these trials demonstrated many advantages over thermal curing which is the only other alternative to two sided printing in one pass through the press. These advantages can be found in product quality, a cleaner environment, and in economics. This development program is still in progress with efforts now directed towards adapting EB ink technology to the latest developments in intaglio printing, i.e. aqueous cylinder wiping which requires EB inks to be water dispersable. Also the stability of materials in contact with EB inks is being investigated

Electron beam curing of intaglio inks

International Nuclear Information System (INIS)

O'Brien, T.

1985-01-01

Press trials conducted by the U.S. Bureau of Engraving and Printing at the National Bank of Denmark clearly indicated the feasibility of Electron Beam (E.B.) curing for web intaglio printing . These trials, some at continuous press runs of up to six hours, gave positive results for virtually all our requirements including: print quality, press speeds, ability to print both sides of the web on one pass through a press, acceptable ink curing at one megarad or less, and minimum substrate deterioration or loss of moisture. In addition, these trials demonstrated many advantages over thermal curing which is the only other alternative to two sided printing in one pass through the press. These advantages can be found in product quality, a cleaner environment, and in economics. This development program is still in progress with efforts now directed towards adapting E.B. ink technology to the latest developments in intaglio printing, i.e. aqueous cylinder wiping which requires E.B. inks to be water dispersable. Also the stability of materials in contact with E.B. inks is being investigated. (author)

Depth of cure of bulk-fill flowable composite resins.

Science.gov (United States)

Pedalino, Inaam; Hartup, Grant R; Vandewalle, Kraig S

2015-01-01

In recent years, manufacturers have introduced flowable composite resins that reportedly can be placed in increments of 4 mm or greater. The purpose of this study was to evaluate the depth of cure of bulk-fill flowable composite resins (SureFil SDR Flow, Grandio Flow, and Venus Bulk Fill) and a conventional flowable composite resin (Revolution Formula 2). Depth of cure was measured in terms of bottom-maximum Knoop hardness number (KHN) ratios and the International Organization for Standardization (ISO) 4049 scrape technique. Shades A2 and A3 of SureFil SDR Flow, Grandio Flow, and Revolution Formula 2 were tested. Venus Bulk Fill was tested in its only available shade (universal). Specimens in thicknesses of 2, 3, 4, 5, and 6 mm were polymerized for 20 or 40 seconds, and a hardness tester was used to determine the hardness ratios for each shade at each thickness. For the scraping technique, after specimens were exposed to the curing light, unpolymerized composite resin was removed with a plastic instrument, the polymerized composite was measured, and the length was divided by 2 per ISO guidelines. According to the KHN ratios and the scrape test, Venus Bulk Fill predictably exceeded the manufacturer's claim of a 4-mm depth of cure at both 20 and 40 seconds of curing time. The overall results for depth of cure showed that Venus Bulk Fill ≥ SureFil SDR Flow ≥ Grandio Flow ≥ Revolution Formula 2.

Recent advance and applications in radiation curing of coatings

International Nuclear Information System (INIS)

Kishi, Naoyuki

1976-01-01

The recent advance and application as well as the profitability of method of coating by curing with electron beam are reviewed. The acrylic prepolymers having two or more acryloyl radicals on side chains or at the end can be cured with electron beam, and have excellent characteristics. The technique to use acrylic esters and methacrylic esters as dilutant monomers has been developed. Mitsubishi Rayon Co., Ltd. is finishing asbestos slate boards and calcium silicate boards for prefabricated houses, utilizing an electron beam curing coating line. The line serves as a semicommercial production line having the capacity of continuously coating and curing boards of 1,200 mm by 2,400 mm. It is equipped with an electron beam accelerator of 500 kV x 65 mA (max. 100 mA), a conveyor running at speed of 5 to 100 m/min, and a curtain flow coater, a roller coater and the like. It can be cured rapidly at room temperature. The finished coatings have high cross-linking density and withstand particularly blocking, freezing and solvents. Its application to the coating of automotive parts by Suzuki Automobile Co. is briefly mentioned. (Iwakiri, K.)

Room-Temperature-Cured Copolymers for Lithium Battery Gel Electrolytes

Science.gov (United States)

Meador, Mary Ann B.; Tigelaar, Dean M.

2009-01-01

Polyimide-PEO copolymers (PEO signifies polyethylene oxide) that have branched rod-coil molecular structures and that can be cured into film form at room temperature have been invented for use as gel electrolytes for lithium-ion electric-power cells. These copolymers offer an alternative to previously patented branched rod-coil polyimides that have been considered for use as polymer electrolytes and that must be cured at a temperature of 200 C. In order to obtain sufficient conductivity for lithium ions in practical applications at and below room temperature, it is necessary to imbibe such a polymer with a suitable carbonate solvent or ionic liquid, but the high-temperature cure makes it impossible to incorporate and retain such a liquid within the polymer molecular framework. By eliminating the high-temperature cure, the present invention makes it possible to incorporate the required liquid.

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

Science.gov (United States)

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.

Effect of light-curing units, post-cured time and shade of resin cement on knoop hardness.

Science.gov (United States)

Reges, Rogério Vieira; Costa, Ana Rosa; Correr, Américo Bortolazzo; Piva, Evandro; Puppin-Rontani, Regina Maria; Sinhoreti, Mário Alexandre Coelho; Correr-Sobrinho, Lourenço

2009-01-01

The aim of this study was to evaluate the Knoop hardness after 15 min and 24 h of different shades of a dual-cured resin-based cement after indirect photoactivation (ceramic restoration) with 2 light-curing units (LCUs). The resin cement Variolink II (Ivoclar Vivadent) shade XL, A2, A3 and opaque were mixed with the catalyst paste and inserted into a black Teflon mold (5 mm diameter x 1 mm high). A transparent strip was placed over the mold and a ceramic disc (Duceram Plus, shade A3) was positioned over the resin cement. Light-activation was performed through the ceramic for 40 s using quartz-tungsten-halogen (QTH) (XL 2500; 3M ESPE) or light-emitting diode (LED) (Ultrablue Is, DMC) LCUs with power density of 615 and 610 mW/cm(2), respectively. The Koop hardness was measured using a microhardness tester HMV 2 (Shimadzu) after 15 min or 24 h. Four indentations were made in each specimen. Data were subjected to ANOVA and Tukey's test (alpha=0.05). The QTH LCU provided significantly higher (pcement showed lower Knoop hardness than the other shades for both LCUs and post-cure times.

Synthesis, Characterization and Curing Studies of Thermosetting Epoxy Resin with Amines

International Nuclear Information System (INIS)

Lakshmi, B.; Mahendra, K. N.; Shivananda, K. N.

2010-01-01

A new hybrid thermosetting maleimido epoxy compound 4-(N-maleimidophenyl) glycidylether (N-MPGE) is prepared by reacting N-(4-hydroxyphenyl) maleimide (HPM) with Epichlorohydrin by using benzyltrimethylammonium chloride as a catalyst. The resulting compound possesses both the oxirane ring and maleimide group. The curing reaction of these maleimidophenyl glycidylether epoxy compound (N-MPGE) with amines as curing agents such as ethylendiamine (EDA), diethylentriamine (DETA) and triethylenetetramine (TETA), aminoethylpiperazine (AEP) and isophoronediamine, IPDA), are studied. Incorporation of maleimide groups in the epichlorohydrin provides cyclic imide structure and high cross-linking density to the cured resins. The cured samples exhibited good thermal stability, excellent chemical (acid/alkali/solvent) and water absorption resistance. Morphological studies by the SEM technique further confirmed the phase homogeneity net work of the cured systems

Synthesis, Characterization and Curing Studies of Thermosetting Epoxy Resin with Amines

Energy Technology Data Exchange (ETDEWEB)

Lakshmi, B.; Mahendra, K. N. [Bangalore University, Bangalore (India); Shivananda, K. N. [Technion - Israel Institute of Technology, Haifa (Israel)

2010-08-15

A new hybrid thermosetting maleimido epoxy compound 4-(N-maleimidophenyl) glycidylether (N-MPGE) is prepared by reacting N-(4-hydroxyphenyl) maleimide (HPM) with Epichlorohydrin by using benzyltrimethylammonium chloride as a catalyst. The resulting compound possesses both the oxirane ring and maleimide group. The curing reaction of these maleimidophenyl glycidylether epoxy compound (N-MPGE) with amines as curing agents such as ethylendiamine (EDA), diethylentriamine (DETA) and triethylenetetramine (TETA), aminoethylpiperazine (AEP) and isophoronediamine, IPDA), are studied. Incorporation of maleimide groups in the epichlorohydrin provides cyclic imide structure and high cross-linking density to the cured resins. The cured samples exhibited good thermal stability, excellent chemical (acid/alkali/solvent) and water absorption resistance. Morphological studies by the SEM technique further confirmed the phase homogeneity net work of the cured systems.

Normal value collection in nuclear cardiological examination: The 'cured norm' concept

International Nuclear Information System (INIS)

Maul, F.D.; Standke, R.; Hoer, G.

1989-01-01

As a refence a standard of 'cured norm' is proposed. The patients who come under the 'cured norm' category are those without previous myocardial infarctions and who are free of symptoms after a successful transluminal coronary angioplasty (TCA) with a normalized exercise ECG. Global and sectorial parameters of radionuclide-vetriculography (RNV) and 201 Tl-myocardial-scintigraphy ( 201 Tl-MS) are in good accordance with the published data from other authors. An improvement is found after successful TCA but results are even better in the special 'cured norm' group indicating an additional normalization. Sensitivity and specificity based on the 'cured norm' is comparable with the results published by others. From these results we conclude that the 'cured norm' is suitable for clinical use. (orig.) [de

The curing behavior and properties of phthalonitrile resins using ionic liquids as a new class of curing agents

Directory of Open Access Journals (Sweden)

K. Cheng

2017-11-01

Full Text Available Binary blends composed of 1,3-bis (3,4-dicyanophenoxy benzene (3BOCN and ionic liquids (ILs with different molecular structures were prepared. The curing behavior of these 3BOCN/ILs blends were studied by thermogravimetric analysis (TGA, differential scanning calorimetry (DSC and rheological analysis. The study suggested that the blends possessed a wide processing window and the structures of ILs (anion, cation and alkyl chain length at cation had an effect on curing behavior. The 3BOCN/[EPy]BF4 resins were prepared at elevated temperature. IR spectra of the resins showed that there were triazine and isoindoline formed in curing process. The TGA and dynamic mechanical analysis (DMA revealed that the resins have excellent thermal stability together with high storage modulus and high glass transition temperature (Tg. Dielectric properties, long term oxidative aging and water uptake measurements of the resins suggested the IL brought some unique properties to the resins.

Distance to Cure

OpenAIRE

Capachi, Casey

2013-01-01

Distance to Cure A three-part television series by Casey Capachi www.distancetocure.com   Abstract   How far would you go for health care? This three-part television series, featuring two introductory segments between each piece, focuses on the physical, cultural, and political obstacles facing rural Native American patients and the potential of health technology to break down those barriers to care.   Part one,Telemedici...

Curing mode affects bond strength of adhesively luted composite CAD/CAM restorations to dentin.

Science.gov (United States)

Lührs, Anne-Katrin; Pongprueksa, Pong; De Munck, Jan; Geurtsen, Werner; Van Meerbeek, Bart

2014-03-01

To determine the effect of curing mode and restoration-surface pre-treatment on the micro-tensile bond strength (μTBS) to dentin. Sandblasted CAD/CAM composite blocks (LAVA Ultimate, 3M ESPE) were cemented to bur-cut dentin using either the etch & rinse composite cement Nexus 3 ('NX3', Kerr) with Optibond XTR ('XTR', Kerr), or the self-etch composite cement RelyX Ultimate ('RXU', 3M ESPE) with Scotchbond Universal ('SBU', 3M ESPE). All experimental groups included different 'curing modes' (light-curing of adhesive and cement ('LL'), light-curing of adhesive and auto-cure of cement ('LA'), co-cure of adhesive through light-curing of cement ('AL'), or complete auto-cure ('AA')) and different 'restoration-surface pre-treatments' of the composite block (NX3: either a silane primer (Kerr), or the XTR adhesive; RXU: either silane primer (RelyX Ceramic Primer, 3M ESPE) and SBU, or solely SBU). After water-storage (7 days, 37°C), the μTBS was measured. Additionally, the degree of conversion (DC) of both cements was measured after 10min and after 1 week, either auto-cured (21°C/37°C) or light-cured (directly/through 3-mm CAD/CAM composite). The linear mixed-effects model (α=0.05) revealed a significant influence of the factors 'curing mode' and 'composite cement', and a less significant effect of the factor 'restoration-surface pre-treatment'. Light-curing 'LL' revealed the highest μTBS, which decreased significantly for all other curing modes. For curing modes 'AA' and 'AL', the lowest μTBS and a high percentage of pre-testing failures were reported. Overall, DC increased with light-curing and incubation time. The curing mode is decisive for the bonding effectiveness of adhesively luted composite CAD/CAM restorations to dentin. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Polyurethane curing kinetics for polymer bonded explosives: HTPB/IPDI binder

Energy Technology Data Exchange (ETDEWEB)

Lee, Sangmook; Hong, In-Kwon [Dankook University, Yongin (Korea, Republic of); Choi, Chong Han; Lee, Jae Wook [Sogang University, Seoul (Korea, Republic of)

2015-08-15

The kinetics of polyurethane reaction and the effect of catalysts on the curing behavior were studied. The mixtures of hydroxyl terminated polybutadiene and isophorone diisocyanate with different reaction catalysts were dynamically cured in a differential scanning calorimeter. The activation energies were evaluated by the Kissinger and the Ozawa methods. The Chang plot was also used to determine reaction order and rate constant. The results showed that the activation energies were influenced remarkably by the choice of catalysts. The degree of cure and the cure time at given temperatures were calculated by direct integration of modified auto-catalytic kinetic model. It would give valuable information like pot-life estimation during manufacturing polymer-bonded explosives.

Nitrite, nitrite alternatives, and the control of Clostridium botulinum in cured meats.

Science.gov (United States)

Pierson, M D; Smoot, L A

1982-01-01

Historically, nitrite has been a component of meat-curing additives for several centuries. In recent years the safety of nitrite as an additive in cured meats has been questioned mainly because of the possible formation of carcinogenic nitrosamines. Nitrite has many important functions in meat curing including its role in color development, flavor, antioxidant properties, and antimicrobial activity. The inhibition of Clostridium botulinum growth and toxin production is an especially important antimicrobial property of nitrite. This review discusses the effects of processing, curing ingredients (especially nitrite), and storage of cured meats in relation to the control of C. botulinum. If nitrite is eliminated from cured meats or the level of usage decreased, then alternatives for the antibotulinal function of nitrite need to be considered. Several potential alternatives including sorbates, parabens, and biological acidulants are discussed.

Swelling of radiation-cured polymer precursor powder for silicon carbide by pyrolysis

Directory of Open Access Journals (Sweden)

Akinori Takeyama

2015-12-01

Full Text Available Ceramic yield, density, volume change and pore size distribution were measured for radiation- and thermally cured PCS powder when they were pyrolyzed in the temperature range of 673–973 K. Higher ceramic yield was obtained for radiation-cured powder due to smaller amount of evolved gas. Temperature dependence of volume change and the total pore volume show that the formation and disappearance of pores in the powders were determined by the volume shrinkage and evolution of decomposed gases. Volume shrinkage narrowed the pore size distribution for radiation-cured powder. For thermally cured powder, the narrowing of size distribution was disturbed by aggregated pores. Smaller amount of evolved gas from radiation-cured powder relative to thermally cured powder prevented the aggregation of pores and provided the narrow size distribution.

Fight fire with fire: Gene therapy strategies to cure HIV.

Science.gov (United States)

Huyghe, Jon; Magdalena, Sips; Vandekerckhove, Linos

2017-08-01

Human Immunodeficiency Virus (HIV) to date remains one of the most notorious viruses mankind has ever faced. Despite enormous investments in HIV research for more than 30 years an effective cure for HIV has been elusive. Areas covered: Combination antiretroviral therapy (cART) suppresses active viral replication, but is not able to eliminate the virus completely due to stable integration of HIV inside the host genome of infected cells and the establishment of a latent reservoir, that is insensitive to cART. Nevertheless, this latent HIV reservoir is fully capable to refuel viral replication when treatment is stopped, creating a major obstacle towards a cure for HIV. Several gene therapy approaches ranging from the generation of HIV resistant CD4 + T cells to the eradication of HIV infected cells by immune cell engineering are currently under pre-clinical and clinical investigation and may present a promising road to a cure. In this review, we focus on the status and the prospects of gene therapy strategies to cure/eradicate HIV. Expert commentary: Recent advances in gene therapy for oncology and infectious diseases indicate that gene therapy may be a feasible and very potent cure strategy, and therefore a potential game changer in the search for an effective HIV cure.

Talking Cure Models: A Framework of Analysis

Directory of Open Access Journals (Sweden)

Christopher Marx

2017-09-01

Full Text Available Psychotherapy is commonly described as a “talking cure,” a treatment method that operates through linguistic action and interaction. The operative specifics of therapeutic language use, however, are insufficiently understood, mainly due to a multitude of disparate approaches that advance different notions of what “talking” means and what “cure” implies in the respective context. Accordingly, a clarification of the basic theoretical structure of “talking cure models,” i.e., models that describe therapeutic processes with a focus on language use, is a desideratum of language-oriented psychotherapy research. Against this background the present paper suggests a theoretical framework of analysis which distinguishes four basic components of “talking cure models”: (1 a foundational theory (which suggests how linguistic activity can affect and transform human experience, (2 an experiential problem state (which defines the problem or pathology of the patient, (3 a curative linguistic activity (which defines linguistic activities that are supposed to effectuate a curative transformation of the experiential problem state, and (4 a change mechanism (which defines the processes and effects involved in such transformations. The purpose of the framework is to establish a terminological foundation that allows for systematically reconstructing basic properties and operative mechanisms of “talking cure models.” To demonstrate the applicability and utility of the framework, five distinct “talking cure models” which spell out the details of curative “talking” processes in terms of (1 catharsis, (2 symbolization, (3 narrative, (4 metaphor, and (5 neurocognitive inhibition are introduced and discussed in terms of the framework components. In summary, we hope that our framework will prove useful for the objective of clarifying the theoretical underpinnings of language-oriented psychotherapy research and help to establish a more

21 CFR 170.60 - Nitrites and/or nitrates in curing premixes.

Science.gov (United States)

2010-04-01

... premixes, may continue to be used under prior sanctions in the commercial curing of meat and meat products... that apply to meat curing preparations for the home curing of meat and meat products, including poultry and wild game. To assure safe use of such ingredients the labeling of the premixes shall bear...

Dewetting transition assisted clearance of (NFGAILS) amyloid fibrils from cell membranes by graphene

Energy Technology Data Exchange (ETDEWEB)

Liu, Jiajia; Yang, Zaixing; Gu, Zonglin [Institute of Quantitative Biology and Medicine, SRMP and RAD-X, Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, and Jiangsu Provincial Key Laboratory of Radiation Medicine and Protection, Soochow University, Suzhou 215123 (China); Li, Haotian [Bio-X Lab, Department of Physics, Zhejiang University, Hangzhou 310027 (China); Garate, Jose Antonio [IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Zhou, Ruhong, E-mail: ruhongz@us.ibm.com [Institute of Quantitative Biology and Medicine, SRMP and RAD-X, Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, and Jiangsu Provincial Key Laboratory of Radiation Medicine and Protection, Soochow University, Suzhou 215123 (China); IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Department of Chemistry, Columbia University, New York, New York 10027 (United States)

2014-12-14

Clearance of partially ordered oligomers and monomers deposited on cell membrane surfaces is believed to be an effective route to alleviate many potential protein conformational diseases (PCDs). With large-scale all-atom molecular dynamics simulations, here we show that graphene nanosheets can easily and quickly win a competitive adsorption of human islet amyloid polypeptides (hIAPP{sub 22-28}) NFGAILS and associated fibrils against cell membrane, due to graphene's unique two-dimensional, highly hydrophobic surface with its all-sp{sup 2} hybrid structure. A nanoscale dewetting transition was observed at the interfacial region between the fibril (originally deposited on the membrane) and the graphene nanosheet, which significantly assisted the adsorption of fibrils onto graphene from the membrane. The π–π stacking interaction between Phe23 and graphene played a crucial role, providing the driving force for the adsorption at the graphene surface. This study renders new insight towards the importance of water during the interactions between amyloid peptides, the phospholipidic membrane, and graphene, which might shed some light on future developments of graphene-based nanomedicine for preventing/curing PCDs like type II diabetes mellitus.

Dewetting transition assisted clearance of (NFGAILS) amyloid fibrils from cell membranes by graphene

International Nuclear Information System (INIS)

Liu, Jiajia; Yang, Zaixing; Gu, Zonglin; Li, Haotian; Garate, Jose Antonio; Zhou, Ruhong

2014-01-01

Clearance of partially ordered oligomers and monomers deposited on cell membrane surfaces is believed to be an effective route to alleviate many potential protein conformational diseases (PCDs). With large-scale all-atom molecular dynamics simulations, here we show that graphene nanosheets can easily and quickly win a competitive adsorption of human islet amyloid polypeptides (hIAPP 22-28 ) NFGAILS and associated fibrils against cell membrane, due to graphene's unique two-dimensional, highly hydrophobic surface with its all-sp 2 hybrid structure. A nanoscale dewetting transition was observed at the interfacial region between the fibril (originally deposited on the membrane) and the graphene nanosheet, which significantly assisted the adsorption of fibrils onto graphene from the membrane. The π–π stacking interaction between Phe23 and graphene played a crucial role, providing the driving force for the adsorption at the graphene surface. This study renders new insight towards the importance of water during the interactions between amyloid peptides, the phospholipidic membrane, and graphene, which might shed some light on future developments of graphene-based nanomedicine for preventing/curing PCDs like type II diabetes mellitus

Temperature and curing time affect composite sorption and solubility

Directory of Open Access Journals (Sweden)

Fabrício Luscino Alves de Castro

2013-04-01

Full Text Available Objective: This study evaluated the effect of temperature and curing time on composite sorption and solubility. Material and Methods: Seventy five specimens (8×2 mm were prepared using a commercial composite resin (ICE, SDI. Three temperatures (10°C, 25°C and 60°C and five curing times (5 s, 10 s, 20 s, 40 s and 60 s were evaluated. The specimens were weighed on an analytical balance three times: A: before storage (M1; B: 7 days after storage (M2; C: 7 days after storage plus 1 day of drying (M3. The storage solution consisted of 75% alcohol/25% water. Sorption and solubility were calculated using these three weights and specimen dimensions. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U Tests (α=5%. Results: The results showed that time, temperature and their interaction influenced the sorption and solubility of the composite (p0.05. The 60°C composite temperature led to lower values of sorption for all curing times when compared with the 10°C temperature (p0.05. Solubility was similar at 40 s and 60 s for all temperatures (p>0.05, but was higher at 10°C than at 60°C for all curing times (p0.05. Conclusions: In conclusion, higher temperatures or longer curing times led to lower sorption and solubility values for the composite tested; however, this trend was only significant in specific combinations of temperature and curing times.

Simulation of Injection Molding Process Including Mold Filling and Compound Curing

Directory of Open Access Journals (Sweden)

Mohamad Reza Erfanian

2012-12-01

Full Text Available The present work reports and discusses the results of a 3D simulation of the injection molding process of a rubber compound that includes the mold flling stage and  material curing, using the computer code is developed in “UDF” part of the Fluent 6.3 CAE software. The data obtained from a rheometer (MDR 2000 is used to characterize the rubber material in order to fnd the cure model parameters which exist in curing model. Because of non-newtonian behavior of rubber, in this work the non-newtonian model for viscosity was used and viscosity parameters were computed by mean of viscometry test by RPA. After calculation of the physical and curing properties, vulcanization process was simulated for a complex rubber article with non-uniform thickness by solving the continuity, momentum, energy and curing process equations. Predicted flling and curing time in a complex and 3D rubber part is compared with experimentally measured data which confrmed  the accuracy and applicability of the method.

Sensory and physicochemical characteristics of salamis added with vegetable-based curing ingredients

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Vicky Lilge Kawski

Full Text Available ABSTRACT: The aim of this study was to evaluate the sensory and physicochemical quality of colonial salamis added with vegetable-based curing ingredients as potential enhancers of quality products. Salamis were produced according to three treatments: (A Control: 0.1% curing salt; (B rosemary: 0.05% curing salt + 0.5% rosemary extract (RE; and (C RE+celery: 0.14% Veg 503 + 0.27% Veg 504 (sea salt plus celery, nitrate and nitrite supplies, respectively + 0.5% of RE. No significant differences were observed (P>0.05 among the three treatments for dry matter (DM, crude protein (CP, ash, ether extract (EE and gross energy (GE. Sensory analysis was performed by applying the preference test and multiple comparison between the three treatments. Salamis added with vegetable-based curing ingredients were sensory equivalent to conventional level of curing salts. Vegetable extracts allowed the development of the sensory features of salami and did not interfere in the fermentation process. Results suggested that the extracts can serve as effective natural curing ingredients for the ripening process and cured meat color as well as adequate shelf-life replacing the commercial curing salts in meat and meat products. After 30 days of ripening, salami from the control treatment (conventional levels of nitrite and nitrate and the treatments with added vegetable-based curing ingredients and low nitrite and nitrate content (RE and RE + celery were equivalent in sensory quality.

Free radical and thermal curing of terpyridine-modified terpolymers

NARCIS (Netherlands)

Hofmeier, H.; El-Ghayoury, A.; Schubert, U.S.

2004-01-01

Terpolymers bearing terpyridine as well as (meth)acrylates as free radical curable groups (UV-curing) or hydroxyl groups (thermal curing with bis-isocyanates) were synthesized and characterized using 1H NMR, IR and UV-vis spectroscopy as well as GPC. Subsequently, the ability of covalent

Correlation between the state of cure of thermosetting resins and their properties

International Nuclear Information System (INIS)

Haffane, N.; Benameur, T.; Granger, R.; Vergnaud, J.M.

1996-01-01

Thermosetting resins, in the same way as polymers, are more and more used for coating metal sheets, in order to bring various interesting properties. An important problem arises with the cure of the thermoset, the process of cure being complex with heating conduction and convection and the heat generated by the cure reaction. The kinetics of the heat evolved from the overall cure reaction is determined through calorimetry experiments in scanning mode. The state of cure at time t is expressed by the heat generated by reaction up to time t as a fraction of the total heat generated. A numerical model taking all the facts into account is able to evaluate the profile of the state of cure developed through the thickness of the thermoset. The state of cure which derives from a theoretical point of view is correlated with some properties of interest for the coating, such as the hardness and the resistance to liquids. The resistance to water and ethanol is evaluated by determining the kinetics of absorption which is controlled by diffusion. copyright 1996 American Institute of Physics

Comparison study of crosslink density determination in cured rubber

International Nuclear Information System (INIS)

El-sabbagh, S.H.; Yehia, A.A.

2005-01-01

The crosslink density is an important property affecting the major characteristics of cured rubber. The crosslink density can be determined by different methods such as: 1. Dynamic mechanical method using the data of stress-strain relationship. 2. Mooney-Rivlin equation 3. Swelling in organic solvents measurements using Flory-Rehner equation. The crosslink density calculated by the previous methods were discussed and compared with each other for cured NR, SBR and NBR. The obtained data showed that the dynamic-mechanical method can be considered as a simple and reliable method for determination of crosslink density for cured rubbers

The difference nanocomposite hardness level using LED photoactivation based on curing period variations

Directory of Open Access Journals (Sweden)

Hasiana Tatian

2011-03-01

Full Text Available Polimerizatian is the critical stage to determine the quality of composites resin, this involves isolated monomer carbon double bonds being converted to an extended network of single bonds. Physical and mechanical properties of composites are influenced by the level of conversion attained during polymerization. An adequate light intensity and light curing time are important to obtain the degree of polymerization. The objective of this study is to evaluate the difference of the hardness nanocomposites which activated by LED LCU based on the variation of curing times. This study is a true experimental research. The samples were made from nanocomposites material with cylinder form of 4 mm in depth, 6 mm in diameter. This samples divided into 3 groups of curing times. Group, I was cured for 20's curing time as a control due to manufactory recommended; Group II was cured for 30's, and Group III was cured for 40's and the hardness (Rebound hardness tester was determined using Rebound scale (RS and converted by Mohs scale (MS. There was a very significant level of hardness rate from each group using ANOVA test. The result of the study concludes that there were the differences on the nanocomposites hardness level cured under different curing times 20, 30 and 40 sec. The longer of curing times, the higher level of hardness.

Cycloaliphatic epoxide resins for cationic UV - cure

International Nuclear Information System (INIS)

Verschueren, K.; Balwant Kaur

1999-01-01

This paper introduces the cyclo - aliphatic epoxide resins used for the various applications of radiation curing and their comparison with acrylate chemistry. Radiation curable coatings and inks are pre - dominantly based on acrylate chemistry but over the last few years, cationic chemistry has emerged successfully with the unique properties inherent with cyclo - aliphatic epoxide ring structures. Wide variety of cationic resins and diluents, the formulation techniques to achieve the desired properties greatly contributes to the advancement of UV - curing technology

Radiation cured coatings for high performance products

International Nuclear Information System (INIS)

Parkins, J.C.; Teesdale, D.H.

1984-01-01

Development over the past ten years of radiation curable coating and lacquer systems and the means of curing them has led to new products in the packaging, flooring, furniture and other industries. Solventless lacquer systems formulated with acrylates and other resins enable high levels of durability, scuff resistance and gloss to be achieved. Ultra violet and electron beam radiation curing are used, the choice depending on the nature of the coating, the product and the scale of the operation. (author)

Heat transfer properties and thermal cure of glass-ionomer dental cements.

Science.gov (United States)

Gavic, Lidia; Gorseta, Kristina; Glavina, Domagoj; Czarnecka, Beata; Nicholson, John W

2015-10-01

Under clinical conditions, conventional glass-ionomer dental cements can be cured by application of heat from dental cure lamps, which causes acceleration in the setting. In order for this to be successful, such heat must be able to spread sufficiently through the cement to enhance cure, but not transmit heat so effectively that the underlying dental pulp of the tooth is damaged. The current study was aimed at measuring heat transfer properties of modern restorative glass-ionomers to determine the extent to which they meet these twin requirements. Three commercial glass ionomer cements (Ionofil Molar, Ketac Molar and Equia™ Fill) were used in association with three different light emitting diode cure lamps designed for clinical use. In addition, for each cement, one set of specimens was allowed to cure without application of a lamp. Temperature changes were measured at three different depths (2, 3 and 4 mm) after cure times of 20, 40 and 60 s. The difference among the tested groups was evaluated by ANOVA (P heat irradiation, but much greater temperature increases when exposed to the cure lamp. However, temperature rises did not exceed 12.9 °C. Application of the cure lamp led to the establishment of a temperature gradient throughout each specimen. Differences were typically significant (P heating effect. Because the thermal conductivity of glass-ionomers is low, temperature rises at 4 mm depths were much lower than at 2 mm. At no time did the temperature rise sufficiently to cause concern about potential damage to the pulp.

Radiation Supporting Synthezis and Curing of Composites Suitable for Practical Applications

International Nuclear Information System (INIS)

Przybytniak, G.; Antoniak, M.; Nowicki, A.; Mirkowski, K.; Walo, M.

2011-01-01

Epoxy resins (ER) due to favorable combination of superior mechanical and thermal properties with unusual radiation resistance play an important role in some nuclear and aerospace industries. They are also widely used as matrices of reinforced composites since the homogeneous dissipation of fillers in the non-cured material is uncomplicated and efficient. Curing procedure is a very important factor determining final features of the epoxy resin and its composite. It was confirmed that irradiation facilitates molecular mobility and decreases glass transition as a result of chain scission. On the other hand, the increase in local mobility accelerates crosslinking thus the total effect is dependent on the relation between these two processes. Larieva reported that the ratio between degradation and crosslinking is 0.43, thus under selected conditions yield of curing more than twice prevails over yield of decomposition. The nature of hardener and its radiosensitivity also significantly influence the radiation induced curing. During exposure to ionizing radiation the binders participate in the processes initiated both by radiation and by heating, as curing is highly exothermic and considerably increases temperature of the system. Application of radiation treatment lowers energy consumption, shortens curing time and decreases curing temperature enhancing dimensional stability. In the past some attempts were made to improve heat resistance and strength of epoxy resins by the incorporation of various particles, e.g. silica, carbon nanotubes, montmorillonite, etc, however the results were unambiguous. In the reported studies the effects of radiation and thermal curing were investigated for ER and its composites either in the presence of cationic initiator or amine hardener

Radiation Supporting Synthezis and Curing of Composites Suitable for Practical Applications

Energy Technology Data Exchange (ETDEWEB)

Przybytniak, G.; Antoniak, M.; Nowicki, A.; Mirkowski, K.; Walo, M. [Institute of Nuclear Chemistry and Technology, Dorodna 16 Str., 03-195 Warsaw (Poland)

2011-07-01

Epoxy resins (ER) due to favorable combination of superior mechanical and thermal properties with unusual radiation resistance play an important role in some nuclear and aerospace industries. They are also widely used as matrices of reinforced composites since the homogeneous dissipation of fillers in the non-cured material is uncomplicated and efficient. Curing procedure is a very important factor determining final features of the epoxy resin and its composite. It was confirmed that irradiation facilitates molecular mobility and decreases glass transition as a result of chain scission. On the other hand, the increase in local mobility accelerates crosslinking thus the total effect is dependent on the relation between these two processes. Larieva reported that the ratio between degradation and crosslinking is 0.43, thus under selected conditions yield of curing more than twice prevails over yield of decomposition. The nature of hardener and its radiosensitivity also significantly influence the radiation induced curing. During exposure to ionizing radiation the binders participate in the processes initiated both by radiation and by heating, as curing is highly exothermic and considerably increases temperature of the system. Application of radiation treatment lowers energy consumption, shortens curing time and decreases curing temperature enhancing dimensional stability. In the past some attempts were made to improve heat resistance and strength of epoxy resins by the incorporation of various particles, e.g. silica, carbon nanotubes, montmorillonite, etc, however the results were unambiguous. In the reported studies the effects of radiation and thermal curing were investigated for ER and its composites either in the presence of cationic initiator or amine hardener.

Evaluation of compatibility between different types of adhesives and dual-cured resin cement.

Science.gov (United States)

Franco, Eduardo B; Lopes, Lawrence G; D'alpino, Paulo H P; Pereira, José C; Mondelli, Rafael F L; Navarro, Maria F L

2002-01-01

The objective of this in vitro study was to evaluate the bonding compatibility between different adhesives and a dual-cured resin cement, using a conventional tensile bond test. The adhesives used were: Prime & Bond (PB) (Dentsply) (PB), Scotchbond Multi Purpose (SB) (3M), and the activator Self Cure (SC) (Dentsply). The dual-curing resin cement used was Enforce (EF) (Dentsply). Six groups with five specimens in each were tested: G1: EF/PB/EF (light cured); G2: EF/SB/EF (light cured); G3: EF/PB+SC/EF (light cured); G4: EF/PB+SC/EF (only chemically cured); G5: EF/EF (light cured); G6: EF/EF (only chemically cured). The resin cement was applied in two stainless steel molds with a cone-shaped perforation measuring 4 mm in diameter and 1 mm in thickness, and the adhesive was applied between them. Ten minutes after specimens were cured, the tensile strength was measured in a universal testing machine at a crosshead speed of 0.5 mm/min. The mean values (MPa) +/- SD obtained in each experimental group were: G1: 1.4 +/- 0.2; G2: 1.3 +/- 0.2; G3: 1.2 +/- 0.4; G4: 0.8 +/- 0.2; G5: 1.2 +/- 0.1; G6: 0.7 +/- 0.1. The results were statistically evaluated using nonparametric Kruskal-Wallis and Dunn tests (p adhesives used with dual-cured resin cement. The lowest tensile bond strength values occurred in the absence of photoactivation.

Electron beam curing — taking good ideas to the manufacturing floor

Science.gov (United States)

Saunders, C.; Lopata, V.; Barnard, J.; Stepanik, T.

2000-03-01

Acsion is exploiting several emerging electron beam EB applications ranging from composite curing and repair to viscose manufacturing. EB curing of composite structures offers several advantages: significantly reduced curing times; improvements in part quality and performance; reduced environmental and health concerns; improvements in material handling; and reduced overall manufacturing costs compared to thermal curing. The aerospace industry is developing EB technology in all of their market sectors, including military aviation and space products. Some specific products include cryogenic fuel tanks, improved canopy frames for jet aircraft, and the all-composite military aircraft. This paper discusses each of these opportunities.

Industrial application of radiation curing

Energy Technology Data Exchange (ETDEWEB)

Sasaki, Takashi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

1994-12-31

The contents are advantages of radiation processes - a solvent-free system, less energy consumative, higher production rate, processability at ambient temperature; electron beams vs. ultraviolet curing; applications -broad spectrum of markets use radiation curable materials.

Industrial application of radiation curing

International Nuclear Information System (INIS)

Takashi Sasaki

1993-01-01

The contents are advantages of radiation processes - a solvent-free system, less energy consumative, higher production rate, processability at ambient temperature; electron beams vs. ultraviolet curing; applications -broad spectrum of markets use radiation curable materials

Tools for Visualizing HIV in Cure Research.

Science.gov (United States)

Niessl, Julia; Baxter, Amy E; Kaufmann, Daniel E

2018-02-01

The long-lived HIV reservoir remains a major obstacle for an HIV cure. Current techniques to analyze this reservoir are generally population-based. We highlight recent developments in methods visualizing HIV, which offer a different, complementary view, and provide indispensable information for cure strategy development. Recent advances in fluorescence in situ hybridization techniques enabled key developments in reservoir visualization. Flow cytometric detection of HIV mRNAs, concurrently with proteins, provides a high-throughput approach to study the reservoir on a single-cell level. On a tissue level, key spatial information can be obtained detecting viral RNA and DNA in situ by fluorescence microscopy. At total-body level, advancements in non-invasive immuno-positron emission tomography (PET) detection of HIV proteins may allow an encompassing view of HIV reservoir sites. HIV imaging approaches provide important, complementary information regarding the size, phenotype, and localization of the HIV reservoir. Visualizing the reservoir may contribute to the design, assessment, and monitoring of HIV cure strategies in vitro and in vivo.

Industrial potential for application of radiation curing in Pakistan

International Nuclear Information System (INIS)

Ahmed, S.

1991-01-01

Potential applications of radiation curing of coating are in the field of wood and wood products, drying of printing inks, ceramics (roof and floor tiles) and textiles. Pakistan a 'timber deficit' country needs to improve her wood, plywood, hardboard and particle board to make for shortage of quality wood. Imports of wood and wood products are in excess of 3000 million rupees. Radiation curing can be applied and itexcels over heat treatment. Whereas costs of high energy units (500 KeV) with scanning type are rather high, low energy (100-175 KeV) flat beam self-shielded units costing 200,000 US$ are available. For developing countries ultraviolet (UV) curing is ideally suited because of its low price, flexibility and simplicity in handling. Alternately, multipurpose bunker type facility such as 500 KeV current mA can be utilized in carrying out heat-shrinkables production, irradiation of cable and wire and curing of coatings on wood and wood products. (author)

Studies on cationic UV curing of epoxidised palm oil (EPO) for surface coatings

International Nuclear Information System (INIS)

Mek Zah Salleh; Mohd Hilmi Mahmood; Wan Rosli Wan Daud; Kumar, R.N.

2000-01-01

Epoxidised palm oil (EPO) resin can be cured by ultraviolet (UV) radiation either by radical, cationic or hybrid system. Cationic curing system has been chosen in this study due to the fact that epoxy groups present in EPO can be utilised directly to form crosslinking. Curing was done by means of a 20 cm wide UV IST machine with the conditions of 7.5 A current and 4 m/min conveyor speed. Sulphonium and ferrocenium salts were used as cationic photoinitiator. A formulations study was performed on the selected grades of EPO with other materials. These include types and concentration of photoinitiator, monomers, concentration of EPO and post-cure. The properties of the cured film such as pendulum hardness, percentage of gel content and tensile strength were determined. It was found that triarylsulphonium hexafluorophosphate has a very low solubility in EPO. Addition of vinyl ether monomer to the formulation did not enhance pendulum hardness and gel content of the cured films. It is also found that the post cure temperature has no significant effect on the cured film

Application conditions for ester cured alkaline phenolic resin sand

Directory of Open Access Journals (Sweden)

Ren-he Huang

2016-07-01

Full Text Available Five organic esters with different curing speeds: propylene carbonate (i.e. high-speed ester A; 1, 4-butyrolactone; glycerol triacetate (i.e. medium-speed ester B; glycerol diacetate; dibasic ester (DBE (i.e. low-speed ester C, were chosen to react with alkaline phenolic resin to analyze the application conditions of ester cured alkaline phenolic resin. The relationships between the curing performances of the resin (including pH value, gel pH value, gel time of resin solution, heat release rate of the curing reaction and tensile strength of the resin sand and the amount of added organic ester and curing temperature were investigated. The results indicated the following: (1 The optimal added amount of organic ester should be 25wt.%-30wt.% of alkaline phenolic resin and it must be above 20wt.%-50 wt.% of the organic ester hydrolysis amount. (2 High-speed ester A (propylene carbonate has a higher curing speed than 1, 4-butyrolactone, and they were both used as high-speed esters. Glycerol diacetate is not a high-speed ester in alkaline phenolic resin although it was used as a high-speed ester in ester cured sodium silicate sand; glycerol diacetate and glycerol triacetate can be used as medium-speed esters in alkaline phenolic resin. (3 High-speed ester A, medium-speed ester B (glycerol triacetate and low-speed ester C (dibasic ester, i.e., DBE should be used below 15 ìC, 35 ìC and 50 ìC, respectively. High-speed ester A or low-speed ester C should not be used alone but mixed with medium-speed ester B to improve the strength of the resin sand. (4 There should be a suitable solid content (generally 45wt.%-65wt.% of resin, alkali content (generally 10wt.%-15wt.% of resin and viscosity of alkaline phenolic resin (generally 50-300 mPa≤s in the preparation of alkaline phenolic resin. Finally, the technique conditions of alkaline phenolic resin preparation and the application principles of organic ester were discussed.

A new UV-curing elastomeric substrate for rapid prototyping of microfluidic devices

Science.gov (United States)

Alvankarian, Jafar; Yeop Majlis, Burhanuddin

2012-03-01

Rapid prototyping in the design cycle of new microfluidic devices is very important for shortening time-to-market. Researchers are facing the challenge to explore new and suitable substrates with simple and efficient microfabrication techniques. In this paper, we introduce and characterize a UV-curing elastomeric polyurethane methacrylate (PUMA) for rapid prototyping of microfluidic devices. The swelling and solubility of PUMA in different chemicals is determined. Time-dependent measurements of water contact angle show that the native PUMA is hydrophilic without surface treatment. The current monitoring method is used for measurement of the electroosmotic flow mobility in the microchannels made from PUMA. The optical, physical, thermal and mechanical properties of PUMA are evaluated. The UV-lithography and molding process is used for making micropillars and deep channel microfluidic structures integrated to the supporting base layer. Spin coating is characterized for producing different layer thicknesses of PUMA resin. A device is fabricated and tested for examining the strength of different bonding techniques such as conformal, corona treating and semi-curing of two PUMA layers in microfluidic application and the results show that the bonding strengths are comparable to that of PDMS. We also report fabrication and testing of a three-layer multi inlet/outlet microfluidic device including a very effective fluidic interconnect for application demonstration of PUMA as a promising new substrate. A simple micro-device is developed and employed for observing the pressure deflection of membrane made from PUMA as a very effective elastomeric valve in microfluidic devices.

Ionizing radiation post-curing of objects produced by stereolithography and other methods

Science.gov (United States)

Howell, David H.; Eberle, Claude C.; Janke, Christopher J.

2000-01-01

An object comprised of a curable material and formed by stereolithography or another three-dimensional prototyping method, in which the object has undergone initial curing, is subjected to post-curing by ionizing radiation, such as an electron beam having a predetermined beam output energy, which is applied in a predetermined dosage and at a predetermined dose rate. The post-cured object exhibits a property profile which is superior to that which existed prior to the ionizing radiation post-curing.

Beam in on curing

International Nuclear Information System (INIS)

Holl, Dr.

1981-01-01

Electron beam curing of paints and allied materials is discussed. Examples of applications are: silicone papers; painting of metal; bonding of flake adhesives; bonding of grinding media (binders); paints for external uses; painting shaped parts; bi-reactive painting systems. An example is given of the calculation of the cost of irradiation. (U.K.)

An Evaluation of Fracture Toughness of Vinyl Ester Composites Cured under Microwave Conditions

Science.gov (United States)

Ku, H.; Chan, W. L.; Trada, M.; Baddeley, D.

2007-12-01

The shrinkage of vinyl ester particulate composites has been reduced by curing the resins under microwave conditions. The reduction in the shrinkage of the resins by microwaves will enable the manufacture of large vinyl ester composite items possible (H.S. Ku, G. Van Erp, J.A.R. Ball, and S. Ayers, Shrinkage Reduction of Thermoset Fibre Composites during Hardening using Microwaves Irradiation for Curing, Proceedings, Second World Engineering Congress, Kuching, Malaysia, 2002a, 22-25 July, p 177-182; H.S. Ku, Risks Involved in Curing Vinyl Ester Resins Using Microwaves Irradiation. J. Mater. Synth. Proces. 2002b, 10(2), p 97-106; S.H. Ku, Curing Vinyl Ester Particle Reinforced Composites Using Microwaves. J. Comp. Mater., (2003a), 37(22), p 2027-2042; S.H. Ku and E. Siores, Shrinkage Reduction of Thermoset Matrix Particle Reinforced Composites During Hardening Using Microwaves Irradiation, Trans. Hong Kong Inst. Eng., 2004, 11(3), p 29-34). In tensile tests, the yield strengths of samples cured under microwave conditions obtained are within 5% of those obtained by ambient curing; it is also found that with 180 W microwave power, the tensile strengths obtained for all duration of exposure to microwaves are also within the 5% of those obtained by ambient curing. While, with 360 W microwave power, the tensile strengths obtained for all duration of exposure to microwaves are 5% higher than those obtained by ambient curing. Whereas, with 540 W microwave power, the tensile strengths obtained for most samples are 5% below those obtained by ambient curing (H. Ku, V.C. Puttgunta, and M. Trada, Young’s Modulus of Vinyl Ester Composites Cured by Microwave Irradiation: Preliminary Results, J. Electromagnet. Waves Appl., 2007, 20(14), p. 1911-1924). This project, using 33% by weight fly ash reinforced vinyl ester composite [VE/FLYSH (33%)], is to further investigate the difference in fracture toughness between microwave cured vinyl ester particulate composites and those cured

Flexural behaviour of post-cured composites at oral-simulating temperatures.

Science.gov (United States)

Ho, C T; Vijayaraghavan, T V; Lee, S Y; Tsai, A; Huang, H M; Pan, L C

2001-07-01

Post-curing treatments have been known to improve the mechanical stability of visible light-cured composites. After individual post-curing treatment, the flexural strength (FS) of four commercial direct/indirect placement composite materials which differ greatly in composition [oligocarbonate dimethacrylate (OCDMA)-based Conquest C & B (CQT), Bisphenol-A glycidyl dimethacrylate (BisGMA)-based Charisma, urethane dimethacrylate (UDMA)-based Concept (CCT), and BisGMA/UDMA-based Dentacolor] was evaluated under water in the temperature range of 12-50 degrees C. A control series was tested in air at room temperature (25 +/- 1 degrees C). Data were analysed using ANOVA and Duncan's test. Flexural strengths overall decreased (20-40%, P OCDMA-based materials. Post-cured composites can be significantly affected by exposure to oral environments. Different composition determines the degree of influence.

Strontium binding to cement paste cured at different temperature

International Nuclear Information System (INIS)

Peterson, V.K.; Ray, A.

1999-01-01

Concentration - depth profiles were measured using Proton Induced X-ray Emission (PIXE). These results were used as a measure of the Sr 2+ retention abilities of each matrix. Ordinary Portland cement (OPC) and cemented clinoptilolite samples were cured at 25 deg C, 60 deg C and 150 deg C. As expected, the Sr 2+ penetration depth increased with increasing OPC cure temperature, caused by an increase in sample permeability. Surprisingly, the penetration depths of Sr 2+ increased with the addition of clinoptilolite to the OPC, also thought to be caused by an increase in sample permeability. However, the increase in penetration depth was reduced in samples cured at higher temperatures

Current and future market of UV/EB curing in Thailand

International Nuclear Information System (INIS)

Suda Kiatkamjornwong; Aran Hanseubsai

1999-01-01

Current status and future market of UV/EB curing in Thailand were presented. Included number of printing houses, export, main export market and the role of radiation curing in printing and packaging industries of Thailand

Effects of the different atmospheric steam curing processes on the ...

Indian Academy of Sciences (India)

hardness when exposed to different atmospheric steam curing temperatures. ... Use of self-compacting concretes (SCCs) lowered the noise level on the ... Although maximum temperature limit values in curing locations should be from 40 to ...

Promotion time cure rate model with nonparametric form of covariate effects.

Science.gov (United States)

Chen, Tianlei; Du, Pang

2018-05-10

Survival data with a cured portion are commonly seen in clinical trials. Motivated from a biological interpretation of cancer metastasis, promotion time cure model is a popular alternative to the mixture cure rate model for analyzing such data. The existing promotion cure models all assume a restrictive parametric form of covariate effects, which can be incorrectly specified especially at the exploratory stage. In this paper, we propose a nonparametric approach to modeling the covariate effects under the framework of promotion time cure model. The covariate effect function is estimated by smoothing splines via the optimization of a penalized profile likelihood. Point-wise interval estimates are also derived from the Bayesian interpretation of the penalized profile likelihood. Asymptotic convergence rates are established for the proposed estimates. Simulations show excellent performance of the proposed nonparametric method, which is then applied to a melanoma study. Copyright © 2018 John Wiley & Sons, Ltd.

Qualitative Beam Profiling of Light Curing Units for Resin Based Composites.

Science.gov (United States)

Haenel, Thomas; Hausnerová, Berenika; Steinhaus, Johannes; Moeginger, Ing Bernhard

2016-12-01

This study investigates two technically simple methods to determine the irradiance distribution of light curing units that governs the performance of a visible-light curing resin-based composites. Insufficient light irradiation leads to under-cured composites with poor mechanical properties and elution of residual monomers. The unknown irradiance distribution and its effect on the final restoration are the main critical issues requiring highly sophisticated experimental equipment. The study shows that irradiance distributions of LCUs can easily be determined qualitatively with generally available equipment. This significantly helps dentists in practices to be informed about the homogeneity of the curing lights. Copyright© 2016 Dennis Barber Ltd.

Steam Cured Self-Consolidating Concrete and the Effects of Limestone Filler

Science.gov (United States)

Aqel, Mohammad A.

The purpose of this thesis is to determine the effect and the mechanisms associated with replacing 15% of the cement by limestone filler on the mechanical properties and durability performance of self-consolidating concrete designed and cured for precast/prestressed applications. This study investigates the role of limestone filler on the hydration kinetics, mechanical properties (12 hours to 300 days), microstructural and durability performance (rapid chloride permeability, linear shrinkage, sulfate resistance, freeze-thaw resistance and salt scaling resistance) of various self-consolidating concrete mix designs containing 5% silica fume and steam cured at a maximum holding temperature of 55°C. This research also examines the resistance to delayed ettringite formation when the concrete is steam cured at 70°C and 82°C and its secondary consequences on the freeze-thaw resistance. The effect of several experimental variables related to the concrete mix design and also the curing conditions are examined, namely: limestone filler fineness, limestone filler content, cement type, steam curing duration and steam curing temperature. In general, the results reveal that self-consolidating concrete containing 15% limestone filler, steam cured at 55°C, 70°C and 82°C, exhibited similar or superior mechanical and transport properties as well as long term durability performance compared to similar concrete without limestone filler. When the concrete is steam cured at 55°C, the chemical reactivity of limestone filler has an important role in enhancing the mechanical properties at 16 hours (compared to the concrete without limestone filler) and compensating for the dilution effect at 28 days. Although, at 300 days, the expansion of all concrete mixes are below 0.05%, the corresponding freeze-thaw durability factors vary widely and are controlled by the steam curing temperature and the chemical composition of the cement. Overall, the material properties indicate that the use

Color and oxidative stability of nitrite-free cured meat after gamma irradiation

International Nuclear Information System (INIS)

Shahidi, F.; Pegg, R.B.; Shamsuzzaman, K.

1991-01-01

The effects of 5 and 10 kGy irradiation on the color and oxidative stability of meats treated with nitrite or a nitrite-free curing system were investigated. The nitrite-free curing system consisted of the preformed cooked cured-meat pigment, sodium ascorbate and sodium tripolyphosphate with or without sodium acid pyrophosphate. Irradiation had no detrimental effects on the color or flavor of either cured samples. Polyphosphates had a beneficial effect on oxidative stability but had a slight detrimental effect on color stability of irradiated samples

Evidence-based Nursing in the IED: From Caring to Curing?

Directory of Open Access Journals (Sweden)

Jette Ernst

2016-03-01

Full Text Available Danish hospitals are major sites of healthcare reform, and new public management accountability and performance management tools have been applied to improve the quality and efficiency of services. One consequence of this is that nurses’ work in hospitals is increasingly standardized through medical evidence. Using Bourdieu’s theory of practice in combination with an ethnographic field study, it is analyzed how the nurses of a Danish Integrated Emergency Department respond to the changing conditions of work. It is illuminated how two opposing approaches to nursing of humanistically and pluralistically oriented caring, and evidence-based scientifically oriented curing inform nursing in the department. The curing approach is however trumping the caring approach. Curing creates new nursing career pathways and is by some nurses embraced with enthusiasm. For others, the new situation creates tension and distress. It is illustrated how the nurses position their practice in relation to the changing working conditions taking sides for either curing or caring, or finding a way to maneuver in between the two. The article argues that the normative enforcement of the curing approach may carry unintended side effects to the goals of quality and efficiency enhancements.

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

International Nuclear Information System (INIS)

Sasaki, Takashi; Takeda, Satoe; Shiraishi, Katsutoshi.

1995-01-01

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

Stress and flow analyses of ultraviolet-curable resin during curing

Science.gov (United States)

Umezaki, Eisaku; Okano, Akira; Koyama, Hiroto

2014-06-01

The stress and flow generated in ultraviolet (UV)-curable resin during curing in molds were measured to investigate their relationship. The specimens were molds consisting of glass plates and acrylic bars, and UV-curable liquid resin. The specimens were illuminated from above with UV rays. Photoelastic and visual images were separately obtained at a constant time interval using cameras during curing. To help obtain the visual images, acrylic powder was mixed with the liquid resin. The stress was obtained from the photoelastic images by a digital photoelastic technique with phase stepping, and the flow was obtained from the visual images by a particle-tracking velocimetry technique. Results indicate that the stress generated in the UV-curable resin during curing depends on the degree of contact between the mold and the cured area of the resin, and is hardly related to the flow.

Advances in spot curing technology

International Nuclear Information System (INIS)

Burga, R.

1999-01-01

A brief review of spot curing technology was presented. The process which a spot of energy of a specific wavelength bandwidth and irradiance is used to cause a coating, encapsulant or adhesive to change from a liquid to a solid state

Effect of High-Irradiance Light-Curing on Micromechanical Properties of Resin Cements

Directory of Open Access Journals (Sweden)

Anne Peutzfeldt

2016-01-01

Full Text Available This study investigated the influence of light-curing at high irradiances on micromechanical properties of resin cements. Three dual-curing resin cements and a light-curing flowable resin composite were light-cured with an LED curing unit in Standard mode (SM, High Power mode (HPM, or Xtra Power mode (XPM. Maximum irradiances were determined using a MARC PS radiometer, and exposure duration was varied to obtain two or three levels of radiant exposure (SM: 13.2 and 27.2 J/cm2; HPM: 15.0 and 30.4 J/cm2; XPM: 9.5, 19.3, and 29.7 J/cm2 (n=17. Vickers hardness (HV and indentation modulus (EIT were measured at 15 min and 1 week. Data were analyzed with nonparametric ANOVA, Wilcoxon-Mann-Whitney tests, and Spearman correlation analyses (α=0.05. Irradiation protocol, resin-based material, and storage time and all interactions influenced HV and EIT significantly (p≤0.0001. Statistically significant correlations between radiant exposure and HV or EIT were found, indicating that high-irradiance light-curing has no detrimental effect on the polymerization of resin-based materials (p≤0.0021. However, one resin cement was sensitive to the combination of irradiance and exposure duration, with high-irradiance light-curing resulting in a 20% drop in micromechanical properties. The results highlight the importance of manufacturers issuing specific recommendations for the light-curing procedure of each resin cement.

Comparative Evaluation of Shear Bond Strength and Debonding Characteristics using Conventional Halogen Light Curing Unit and LED Light Curing Unit: An in vitro Study

Directory of Open Access Journals (Sweden)

Amit Bhardwaj

2013-01-01

Conclusion: The result of this study showed promise for the orthodontic application of LED as light curing units and 20 seconds of exposure time is adequate for both LED and Halogen light, since increasing the curing time to 40 seconds showed no significant difference.

CUREs in biochemistry?where we are and where we should go

OpenAIRE

Bell, Jessica K.; Eckdahl, Todd T.; Hecht, David A.; Killion, Patrick J.; Latzer, Joachim; Mans, Tamara L.; Provost, Joseph J.; Rakus, John F.; Siebrasse, Erica A.; Ellis Bell, J.

2016-01-01

Abstract Integration of research experience into classroom is an important and vital experience for all undergraduates. These course?based undergraduate research experiences (CUREs) have grown from independent instructor lead projects to large consortium driven experiences. The impact and importance of CUREs on students at all levels in biochemistry was the focus of a National Science Foundation funded think tank. The state of biochemistry CUREs and suggestions for moving biochemistry forward...

Electron beam curing of composites in North America

International Nuclear Information System (INIS)

Berejka, Anthony J.; Eberle, Cliff

2002-01-01

Electron beam curing of fiber-reinforced composites was explored over 30 years ago. Since then there have been developments in accelerator technology, in processes for handling materials presented to an accelerator, and in materials that can be used as matrix binders. In recent years in North America, Cooperative Research and Development Agreements (CRADAs) have been formed involving collaboration amongst materials suppliers, accelerator manufacturers and service providers, national laboratories, such as Oak Ridge National Laboratory, and interested potential users. The scope and status of these CRADAs are reviewed along with other recent developments in the electron beam curing of composites in North America. Innovative and proprietary materials technology has been developed and progress made toward implementing commercial practice. Significant market interest has developed in the military/aerospace industries that are finding the process and performance of electron beam cured composites to offer significant benefits

Preliminary study on solar-assisted tobacco curing in Thailand

Energy Technology Data Exchange (ETDEWEB)

Bamrungwong, S [Chiang Mai Univ.; Suchinda, B; Malila, D

1982-04-01

A solar heating system for assisting flue curing of Virginia tobacco leaf was studied. The equipment consisted of a brick and mortar tobacco curing barn of 3.6 m/sup 3/ volume. The solar air heater of 2.8 m/sup 2/ was a non-focus type, made from corrugated galvanized stel sheet coated with flat-black paint. The collector had a single glass cover on top and a 25 mm layer of styrofoam at the bottom. Electrical heating was utilized inside the bar to simulate the main heat source. The system under study had no thermal storage, therefore it was extremely difficult to regulate the temperature inside the barn precisely. Consequently, the solar assisting mode is not recommended during the yellowing stage of curing where very precise temperature control is required. Utilization of solar energy during other stages of curing showed a saving of the main conventional energy up to 33 to 15 percent. The average thermal efficiencies of the collector varied from 70 percent at high flow rate to 67 percent at low flow rate. 6 references.

A novel calorimetry technique for monitoring electron beam curing of polymer resins

International Nuclear Information System (INIS)

Chen, J.H.; Johnston, A.; Petrescue, L.; Hojjati, M.

2006-01-01

This paper describes the development of a calorimetry-based technique for monitoring of the curing of electron beam (EB) curable resins, including design of the calorimeter hardware and the development of an analytical model for calculating resin cure rates and radiation dose. Factors affecting the performance of the calorimeter were investigated. Experimental trials monitoring the curing of epoxy resin were conducted under single pass and multiple passes of EB irradiation. Results show that the developed calorimeter is a simple, inexpensive and reasonably accurate technique for monitoring the EB curing of cationic epoxies

Manufacturing prepainted steel sheet by electron beam curing

International Nuclear Information System (INIS)

Oka, Joji

1987-01-01

Several advantages are offered by electron beam curing. A formidably hard and stain resistant paint film which is difficult to obtain by heat curing paint is developed. As a result, a unique new prepainted steel is produced. Four technologies are involved: development high-quality paint, selection of optimum electron beam processor, technology to control electron beam processing atmosphere and secondary X-ray shield technology. These technologies are described in detail. (A.J.)

A combinaison of UV curing technology with ATL process

Science.gov (United States)

Balbzioui, I.; Hasiaoui, B.; Barbier, G.; L'hostis, G.; Laurent, F.; Ibrahim, A.; Durand, B.

2017-10-01

In order to reduce the time and the cost of manufacturing composite, UV curing technology combined with automated tape placement process (ATL) based on reverse approach by working with a fixed head was studied in this article. First, a brief description of the developed head placement is presented. Mechanical properties are then evaluated by varying process parameters, including compaction force and tape placement speed. Finally, a parametric study is carried out to identify suitable materials and process parameters to manufacture a photo composite material with high mechanical performances. The obtained results show that UV curing is a very good alternative for thermal polymerization because of its fast cure speed due to less dependency on temperature.

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

International Nuclear Information System (INIS)

Lopez de Vergara, Unai; Sarrionandia, Mariasun; Gondra, Koldo; Aurrekoetxea, Jon

2014-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-04-01

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

Cytotoxicity of Light-Cured Dental Materials according to Different Sample Preparation Methods

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Myung-Jin Lee

2017-03-01

Full Text Available Dental light-cured resins can undergo different degrees of polymerization when applied in vivo. When polymerization is incomplete, toxic monomers may be released into the oral cavity. The present study assessed the cytotoxicity of different materials, using sample preparation methods that mirror clinical conditions. Composite and bonding resins were used and divided into four groups according to sample preparation method: uncured; directly cured samples, which were cured after being placed on solidified agar; post-cured samples were polymerized before being placed on agar; and “removed unreacted layer” samples had their oxygen-inhibition layer removed after polymerization. Cytotoxicity was evaluated using an agar diffusion test, MTT assay, and confocal microscopy. Uncured samples were the most cytotoxic, while removed unreacted layer samples were the least cytotoxic (p < 0.05. In the MTT assay, cell viability increased significantly in every group as the concentration of the extracts decreased (p < 0.05. Extracts from post-cured and removed unreacted layer samples of bonding resin were less toxic than post-cured and removed unreacted layer samples of composite resin. Removal of the oxygen-inhibition layer resulted in the lowest cytotoxicity. Clinicians should remove unreacted monomers on the resin surface immediately after restoring teeth with light-curing resin to improve the restoration biocompatibility.

UV-LED Curing Efficiency of Wood Coatings

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Véronic Landry

2015-12-01

Full Text Available Ultraviolet light emitting diodes (UV-LEDs have attracted great interest in recent years. They can be used to polymerize coatings, such as those used for prefinished wood flooring. In this project, two lamps were compared for their suitability to be used on a wood flooring finishing line: a UV-microwave and a UV-LED lamp. Low heat emission was found for the UV-LED lamp compared to the UV-microwave one. This study also reveals that the 4 W/cm2 UV-LED lamp used is not powerful enough to cure UV high solids acrylate coatings while satisfactory results can be obtained for UV water-based formulations. In fact, conversion percentages were found to be low for the high solids coatings, leaving the coatings tacky. Higher conversion percentages were obtained for the UV water-based formulations. As a result, mass loss, hardness, and scratch resistance found for the samples cured by UV-LED were closed to the ones found for the samples cured using the UV microwave lamp.

Synthesis and curing of alkyd enamels based on ricinoleic acid

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Jovičić Mirjana C.

2010-01-01

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

Neem leaf extract as potential modifier of free radical interaction with RBC membrane

International Nuclear Information System (INIS)

Patil, Shilpa M.; Kulkarni, Satish G.; Rane, Charusheela

2004-01-01

Full text: Neem tree (Azadirachta indica) is well known as village pharmacy due to its multifaceted medicinal action in curing countless health problems. The leaf extract of Neem is known to purify blood by removing toxins and neutralizing free radicals. Using gamma irradiation as free radical generation process the efficacy of neem leaf extract in combating free radical attack on RBC membrane has been explored. The results narrating role of concentration and dose dependency in this radio modulation will be discussed

Effect of the Human Amniotic Membrane on Liver Regeneration in Rats

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Mesut Sipahi

2015-01-01

Full Text Available Introduction. Operations are performed for broader liver surgery indications for a better understanding of hepatic anatomy/physiology and developments in operation technology. Surgery can cure some patients with liver metastasis of some tumors. Nevertheless, postoperative liver failure is the most feared complication causing mortality in patients who have undergone excision of a large liver mass. The human amniotic membrane has regenerative effects. Thus, we investigated the effects of the human amniotic membrane on regeneration of the resected liver. Methods. Twenty female Wistar albino rats were divided into control and experimental groups and underwent a 70% hepatectomy. The human amniotic membrane was placed over the residual liver in the experimental group. Relative liver weight, histopathological features, and biochemical parameters were assessed on postoperative day 3. Results. Total protein and albumin levels were significantly lower in the experimental group than in the control group. No difference in relative liver weight was observed between the groups. Hepatocyte mitotic count was significantly higher in the experimental group than in the control group. Hepatic steatosis was detected in the experimental group. Conclusion. Applying the amniotic membrane to residual liver adversely affected liver regeneration. However, mesenchymal stem cell research has the potential to accelerate liver regeneration investigations.

Beliefs about the causes and cures of depression

OpenAIRE

Furnham, A.; Ritchie, W.; Lay, A.

2016-01-01

BACKGROUND: This study used attitude statement and vignette methodology to examine a mixed British sample’s belies about the causes and consequences of depression. AIMS: To test whether the group would recognise both vignettes with having depression and that the favoured cure would be Psychotherapy/Talking Cure. METHOD: In all, 320 adults completed a two-part questionnaire. In the first part, they were given two vignettes describing a 30-year-old female and a 45-year-old male...

Temperature rise induced by some light emitting diode and quartz-tungsten-halogen curing units.

Science.gov (United States)

Asmussen, Erik; Peutzfeldt, Anne

2005-02-01

Because of the risk of thermal damage to the pulp, the temperature rise induced by light-curing units should not be too high. LED (light emitting diode) curing units have the main part of their irradiation in the blue range and have been reported to generate less heat than QTH (quartz-tungsten-halogen) curing units. This study had two aims: first, to measure the temperature rise induced by ten LED and three QTH curing units; and, second, to relate the measured temperature rise to the power density of the curing units. The light-induced temperature rise was measured by means of a thermocouple embedded in a small cylinder of resin composite. The power density was measured by using a dental radiometer. For LED units, the temperature rise increased with increasing power density, in a statistically significant manner. Two of the three QTH curing units investigated resulted in a higher temperature rise than LED curing units of the same power density. Previous findings, that LED curing units induce less temperature rise than QTH units, does not hold true in general.

Radiation cured polyester compositions containing metal-properties

Science.gov (United States)

Szalińska, H.; Pietrzak, M.; Gonerski, A.

The subject of the studies was unsaturated polyester resin, Polimal-109 and its compositions containing acrylates of: sodium, potassium, calcium, magnesium, barium, manganese, iron, cobalt, copper and acrylic acid. Polyester resin modified with acrylic acid salts was cured with 60Co gamma radiation. Measurements of Vicat softening temperature, water absorption, creep current resistance, volume and surface resistivity, the tangent of dielectric loss angle and permittivity of radiation cured compositions were carried out. The results of the studies presented testify to the fact that the properties of cross-linked polymers alter after ionogenic compounds have been introduced into them.

Radiation cured polyester compositions containing metal-properties

International Nuclear Information System (INIS)

Szalinska, H.; Pietrzak, M.; Gonerski, A.

1987-01-01

The subject of the studies was unsaturated polyester resin, Polimal-109 and its compositions containing acrylates of: sodium, potassium, calcium, magnesium, barium, manganese, iron, cobalt, copper and acrylic acid. Polyester resin modified with acrylic acid salts was cured with 60 Co gamma radiation. Measurements of Vicat softening temperature, water absorption, creep current resistance, volume and surface resistivity, the tangent of dielectric loss angle and permittivity of radiation cured compositions were carried out. The results of the studies presented testify to the fact that the properties of cross-linked polymers alter after ionogenic compounds have been introduced into them. (author)

Radiation curing applications of palm oil acrylates

International Nuclear Information System (INIS)

Mohd Hilmi Mahmood; Khairul Zaman; Rida, Anak Tajau; Mek Zah Salleh; Rosley Che Ismail

2007-01-01

Various palm oil based urethan acrylate prepolymers (UP) were prepared from palm oil based polyols, diisocyanate compounds and hydroxyl terminated acrylate monomers by following procedure derived from established methods. The products were compared with each other in term of their molecular weights (MW), viscosities, curing speed by UV irradiation, gel contents and film hardness. The molecular structure of diisocyanate compounds and hydroxyl acrylate monomers were tend to determine the molecular weights and hence viscosities of the final products of urethan acrylate prepolymers (UP), whereas, the MW of the UP has no direct effects on the UV curing properties of the prepolymers. (author)

Compatibility of anhydride cured epoxies with hexanitroazobenzene (HNAB) and hexanitrostilbene (HNS)

International Nuclear Information System (INIS)

Massis, T.M.; Wischmann, K.B.

1985-01-01

The explosives HNAB (hexanitroazobenzene) and HNS (hexanitrostilbene) have compatibility problems with amine-cured epoxy systems. A program was instituted to find compatible polymeric substitutes for use with these explosives. These polymeric materials must have rigid structures after curing for both adhesive and encapsulant applications. A promising class of epoxy materials using anhydride curing agents with various catalysts to trigger the cure reaction were developed. These polymeric systems have very good compatibility with HNS. Of those tested with HNAB, the anhydride epoxy system that used uranyl nitrate as the catalyst was found to be marginally compatible while the others were incompatible. These results indicated further studies are needed. The CRT (chemical reactivity test) was used to evaluate the compatibility of these materials. 6 references, 2 figures, 5 tables

Effect of Resident Performance on Midurethral Sling Cure and Complication Rates

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Sabri Cavkaytar

2016-01-01

Full Text Available Aim: To evaluate the cure rates and complications of midurethral slings performed by residents under an experienced surgeon supervision. Material and Method: Between January 2013 and January 2014, one hundred forty-one midurethral slings performed in the urogynecology clinic of Ankara Zekai Tahir Burak Women%u2019s Health Research and Education Hospital were reviewed.Age, parity,body mass index,menopausal status, grade 2 preoperative pelvic organ prolapsus,concomitant vaginal surgery and intraoperative (bladder and bowel perforations,bleeding,vaginal laceration and early postoperative (urinary retention etc.complications were recorded.All women were re-examined at postoperative 6 th month and symptoms were questioned. The patients were classified as %u2018%u2019cured%u2019%u2019 if the stress test was negative , %u2018%u2019partially cured%u2019%u2019 if continence frequency decreased but still continued and %u2018%u2019unsatisfied%u2019%u2019 if there was no change in symptoms. Both TVT and TOT groups were compared in case of complications and cure rates. Results: Among 141 patients who had undergone midurethral sling due to urinary stress incontinence,50(35.5% were TOT , 91(64.5% were TVT. In the TVT group, 3 (3.3% patients had bleeding which requires transfusion and 5(5.5% patients had bladder perforations. But in the TOT group,there was no bladder perforation and bleeding that requires transfusion. In the early postoperative period, urinary retention was encountered in 7(14.0% patients in TOT group and in 17(18.7% patients in TVT group. There was no statistically significant difference between the groups in case of complications. At postoperative 6th month, in the TOT group 76% of patients were cured,18% were partially cured and 6% were unsatisfied. In the TVT group, 83.5% of patients were cured, 12.1% were partially cured and 4.4% were unsatisfied and there was no significant difference in cure rates between the groups. Discussion: The

Hardness measurements of silicon rubber and polyurethane rubber cured by ionizing radiation

International Nuclear Information System (INIS)

Basfar, A.A.

1995-01-01

This work investigates the hardness of both silicon rubber and polyurethane rubber cured by ionizing radiation. Shore A Hardness is used to characterize the subject elastomers in relation to the crosslinking process. Various formulations of both materials have been investigated in order to achieve the optimum cure conditions desired. A small amount of the curing agent has been incorporated in some formulations in order to reduce the required dose to achieve full cure conditions. Silicon rubber has shown improvements in hardness as absorbed dose is increased, whereas hardness remained constant over a range of absorbed doses for polyurethane rubber

Influence of site curing on bond properties of reinforced lightweight ...

African Journals Online (AJOL)

... the requirements for structural lightweight concrete. The developed compressive strength and pull-out strength under both site curing conditions were relatively lower than full water curing condition but still were higher than minimum requirement as per standard. Journal of Civil Engineering Research and Practice Vol.

Electron-beam curing of paints and varnishes on wood panels

International Nuclear Information System (INIS)

Grosmaire, P.R.

1977-01-01

An analysis is presented of the relative costs of curing polyester coated wood panels using (a) the conventional peroxide cure, (b) treatment with UV light, or (c) electron beams. Electron treatment is shown to compare very favourably with either of the other treatments. (U.K.)

Vanilla--its science of cultivation, curing, chemistry, and nutraceutical properties.

Science.gov (United States)

Anuradha, Krushnamurthy; Shyamala, Bellur Nanjundaiah; Naidu, Madeneni Madhava

2013-01-01

Vanilla is a tropical orchid belonging to the family Orchidaceae and it is mainly used in food, perfumery, and pharmaceutical preparations. The quality of the bean depends on the volatile constituent's, viz., the vanillin content, the species of the vine used, and the processing conditions adopted. Hence, proper pollination during flowering and curing by exercising utmost care are the important aspects of vanilla cultivation. There are different methods of curing, and each one is unique and named after the places of its origin like Mexican process and Bourbon process. Recently, Central Food Technological Research Institute, Mysore has developed know-how of improved curing process, where the green vanilla beans are cured immediately after harvest and this process takes only 32 days, which otherwise requires minimum of 150-180 days as reported in traditional curing methods. Vanillin is the most essential component of the 200 and odd such compounds present in vanilla beans. Vanillin as such has not shown any antioxidant properties, it is along with other compounds has got nutraceutical properties and therefore its wide usage. The medicinal future of vanilla may definitely lie in further research on basic science and clinical studies on the constituents and their mechanism of action.

The statistics of dose/cure relationships for irradiated tumours

International Nuclear Information System (INIS)

Porter, E.H.

1980-01-01

Consideration is given to the theoretical effects of different factors on the form of dose/cure relationships. Single-clonogen recurrences, dominant anoxic fractions, asymptotically straight survival curves, variable tumour sizes and variable radiation doses are all discussed. Statistical methods are then reviewed, and the conclusions are summarized in the form of advice to experimenters who are studying dose/cure relationships. (UK)

Evaluating the use of renewable fuel sources to heat flue-cured tobacco barns

OpenAIRE

Brown, Robert T

2018-01-01

Evaluating the use of renewable fuel sources to heat flue-cured tobacco barns Robert Taylor Brown ABSTRACT The curing of flue-cured tobacco (Nicotiana tabacum L.) is an energy intensive process and represents a significant portion of the overall cost of production. Given the goal of the industry to reduce the environmental footprint of tobacco production and the energy demand of curing, attention has been directed to explore options for the use of renewable fuels for heating to...

Development of a modified dry curing process for beef.

Science.gov (United States)

Hayes, J E; Kenny, T A; Ward, P; Kerry, J P

2007-11-01

The development of a dry curing process using physical treatments to promote the diffusion of the cure ingredients was studied. Vacuum pulsing with and without tumbling, continuous vacuum, and tumbling only treatments were compared with a conventional static dry cure control method on beef M. supraspinatus. Vacuum tumble and tumble only treatments gave highest core salt content after 7 days conditioning (3.3% and 3.1%, respectively). All test treatments resulted in higher colour uniformity and lower % cook loss in comparison to control (PCured beef slices were stored in modified atmosphere packs (MAP) (80%N(2):20%CO(2)) for up to 28 day at 4°C. Redness (a(∗), Pcured beef products with enhanced organoleptic quality and increased yields.

Application of electron beam curing technology for paper products

International Nuclear Information System (INIS)

Takaharu Miura

1999-01-01

The electron beam (EB) curing technology has rapidly advanced in recent years. However there were few examples applying this technology to paper products. One reason comes from the high price of EB equipment and the other comes from the difficulty of controlling the irradiation which gives damages to paper. In spite of these problems, the EB cured coating layer shows remarkable features, such as solvent-resistance, water-resistance, heat-resistance and high smoothness using the drum casting technique. Concentrating on application of this technology to paper, we have already developed some products. For example, paper for printings (Super Mirror PN) and for white boards (Super Mirror WB) have been manufactured. In this presentation, we are going to introduce this EB curing technique and the products

Mechanical and Thermal Properties of Dental Composites Cured with CAD/CAM Assisted Solid-State Laser

Directory of Open Access Journals (Sweden)

Roberto De Santis

2018-03-01

Full Text Available Over the last three decades, it has been frequently reported that the properties of dental restorative composites cured with argon laser are similar or superior to those achieved with conventional halogen and light emitting diode (LED curing units. Whereas laser curing is not dependent on the distance between the curing unit and the material, such distance represents a drawback for conventional curing units. However, a widespread clinical application of this kind of laser remains difficult due to cost, heavy weight, and bulky size. Recently, with regard to the radiation in the blue region of the spectrum, powerful solid-state lasers have been commercialized. In the current research, CAD (computer-aided design/CAM (computer-aided manufacturing assisted solid-state lasers were employed for curing of different dental restorative composites consisting of micro- and nanoparticle-reinforced materials based on acrylic resins. Commercial LED curing units were used as a control. Temperature rise during the photopolymerisation process and bending properties were measured. By providing similar light energy dose, no significant difference in temperature rise was observed when the two light sources provided similar intensity. In addition, after 7 days since curing, bending properties of composites cured with laser and LED were similar. The results suggested that this kind of laser would be suitable for curing dental composites, and the curing process does not suffer from the tip-to-tooth distance.

Mechanical and Thermal Properties of Dental Composites Cured with CAD/CAM Assisted Solid-State Laser

Science.gov (United States)

De Santis, Roberto; Gloria, Antonio; Maietta, Saverio; Martorelli, Massimo; De Luca, Alessandro; Spagnuolo, Gianrico; Riccitiello, Francesco; Rengo, Sandro

2018-01-01

Over the last three decades, it has been frequently reported that the properties of dental restorative composites cured with argon laser are similar or superior to those achieved with conventional halogen and light emitting diode (LED) curing units. Whereas laser curing is not dependent on the distance between the curing unit and the material, such distance represents a drawback for conventional curing units. However, a widespread clinical application of this kind of laser remains difficult due to cost, heavy weight, and bulky size. Recently, with regard to the radiation in the blue region of the spectrum, powerful solid-state lasers have been commercialized. In the current research, CAD (computer-aided design)/CAM (computer-aided manufacturing) assisted solid-state lasers were employed for curing of different dental restorative composites consisting of micro- and nanoparticle-reinforced materials based on acrylic resins. Commercial LED curing units were used as a control. Temperature rise during the photopolymerisation process and bending properties were measured. By providing similar light energy dose, no significant difference in temperature rise was observed when the two light sources provided similar intensity. In addition, after 7 days since curing, bending properties of composites cured with laser and LED were similar. The results suggested that this kind of laser would be suitable for curing dental composites, and the curing process does not suffer from the tip-to-tooth distance. PMID:29584683

Semiparametric accelerated failure time cure rate mixture models with competing risks.

Science.gov (United States)

Choi, Sangbum; Zhu, Liang; Huang, Xuelin

2018-01-15

Modern medical treatments have substantially improved survival rates for many chronic diseases and have generated considerable interest in developing cure fraction models for survival data with a non-ignorable cured proportion. Statistical analysis of such data may be further complicated by competing risks that involve multiple types of endpoints. Regression analysis of competing risks is typically undertaken via a proportional hazards model adapted on cause-specific hazard or subdistribution hazard. In this article, we propose an alternative approach that treats competing events as distinct outcomes in a mixture. We consider semiparametric accelerated failure time models for the cause-conditional survival function that are combined through a multinomial logistic model within the cure-mixture modeling framework. The cure-mixture approach to competing risks provides a means to determine the overall effect of a treatment and insights into how this treatment modifies the components of the mixture in the presence of a cure fraction. The regression and nonparametric parameters are estimated by a nonparametric kernel-based maximum likelihood estimation method. Variance estimation is achieved through resampling methods for the kernel-smoothed likelihood function. Simulation studies show that the procedures work well in practical settings. Application to a sarcoma study demonstrates the use of the proposed method for competing risk data with a cure fraction. Copyright © 2017 John Wiley & Sons, Ltd.

Growth on Octane Alters the Membrane Lipid Fatty Acids of Pseudomonas oleovorans due to the Induction of alkB and Synthesis of Octanol

NARCIS (Netherlands)

Chen, Qi; Janssen, Dick B.; Witholt, Bernard

1995-01-01

Growth of Pseudomonas oleovorans GPo1, which contains the OCT plasmid, on octane results in changes in the membrane phospholipid fatty acid composition. These changes were not found for GPo12, an OCT-plasmid-cured variant of GPo1, during growth in the presence or absence of octane, implying the

Predictive Modeling of Fast-Curing Thermosets in Nozzle-Based Extrusion

Science.gov (United States)

Xie, Jingjin; Randolph, Robert; Simmons, Gary; Hull, Patrick V.; Mazzeo, Aaron D.

2017-01-01

This work presents an approach to modeling the dynamic spreading and curing behavior of thermosets in nozzle-based extrusions. Thermosets cover a wide range of materials, some of which permit low-temperature processing with subsequent high-temperature and high-strength working properties. Extruding thermosets may overcome the limited working temperatures and strengths of conventional thermoplastic materials used in additive manufacturing. This project aims to produce technology for the fabrication of thermoset-based structures leveraging advances made in nozzle-based extrusion, such as fused deposition modeling (FDM), material jetting, and direct writing. Understanding the synergistic interactions between spreading and fast curing of extruded thermosetting materials will provide essential insights for applications that require accurate dimensional controls, such as additive manufacturing [1], [2] and centrifugal coating/forming [3]. Two types of thermally curing thermosets -- one being a soft silicone (Ecoflex 0050) and the other being a toughened epoxy (G/Flex) -- served as the test materials in this work to obtain models for cure kinetics and viscosity. The developed models align with extensive measurements made with differential scanning calorimetry (DSC) and rheology. DSC monitors the change in the heat of reaction, which reflects the rate and degree of cure at different crosslinking stages. Rheology measures the change in complex viscosity, shear moduli, yield stress, and other properties dictated by chemical composition. By combining DSC and rheological measurements, it is possible to establish a set of models profiling the cure kinetics and chemorheology without prior knowledge of chemical composition, which is usually necessary for sophisticated mechanistic modeling. In this work, we conducted both isothermal and dynamic measurements with both DSC and rheology. With the developed models, numerical simulations yielded predictions of diameter and height of

Compounds from silicones alter enzyme activity in curing barnacle glue and model enzymes.

Science.gov (United States)

Rittschof, Daniel; Orihuela, Beatriz; Harder, Tilmann; Stafslien, Shane; Chisholm, Bret; Dickinson, Gary H

2011-02-17

Attachment strength of fouling organisms on silicone coatings is low. We hypothesized that low attachment strength on silicones is, in part, due to the interaction of surface available components with natural glues. Components could alter curing of glues through bulk changes or specifically through altered enzyme activity. GC-MS analysis of silicone coatings showed surface-available siloxanes when the coatings were gently rubbed with a cotton swab for 15 seconds or given a 30 second rinse with methanol. Mixtures of compounds were found on 2 commercial and 8 model silicone coatings. The hypothesis that silicone components alter glue curing enzymes was tested with curing barnacle glue and with commercial enzymes. In our model, barnacle glue curing involves trypsin-like serine protease(s), which activate enzymes and structural proteins, and a transglutaminase which cross-links glue proteins. Transglutaminase activity was significantly altered upon exposure of curing glue from individual barnacles to silicone eluates. Activity of purified trypsin and, to a greater extent, transglutaminase was significantly altered by relevant concentrations of silicone polymer constituents. Surface-associated silicone compounds can disrupt glue curing and alter enzyme properties. Altered curing of natural glues has potential in fouling management.

Electron beam curing polyurethane acrylate oligomer in air

International Nuclear Information System (INIS)

Zhu, Zhenkang; Chen, Xing; Zhou, Jichun; Ma, Zue-Teh

1988-01-01

It has been found according to our synthesis that a novel kind of polyurethane acrylate oligomer can be cured by electron beam in the presence of oxygen, even at normal atomospheric levels, without any additives. Irradiation of the oligomer with substantially complete cure to a solid non-tacky state is quite remarkable. It has the same gel content (90 %) in air as in nitrogen at dose of 33 kGy. Double bond conversion of the oligomer is about 50 % by I.R. (author)

Influence of curing rate on softening in ethanol, degree of conversion, and wear of resin composite

DEFF Research Database (Denmark)

Benetti, Ana Raquel; Peutzfeldt, Anne; Asmussen, Erik

2011-01-01

PURPOSE: To investigate the effect of curing rate on softening in ethanol, degree of conversion, and wear of resin composites. METHOD: With a given energy density and for each of two different light-curing units (QTH or LED), the curing rate was reduced by modulating the curing mode. Thus......, the irradiation of resin composite specimens (Filtek Z250, Tetric Ceram, Esthet-X) was performed in a continuous curing mode and in a pulse-delay curing mode. Wallace hardness was used to determine the softening of resin composite after storage in ethanol. Degree of conversion was determined by infrared...... exposed to the pulse-delay curing mode were softer than resin composites exposed to continuous cure (Pconversion (P

Radiation cured silicone rubber articles

International Nuclear Information System (INIS)

DuPont, J.G.; Goodwin, P.A.

1984-01-01

A process for making radiation cured silicone rubber articles is disclosed wherein a hydroxyl-terminated polysilaxane having a molecular weight from about 50,000 to about 2,000,000, optionally modified by mixing with up to 85% of an end-stopped silicone rubber, is mixed with from about 10 to about 70 parts per hundred of rubber of a finely divided silica filler with a particle size in the reinforcing range and other inert fillers as determined by desired final properties; the composition so prepared is formed into the desired shape at room temperature; the article so formed is precured to improve the mechanical properties of the material with which it is made by exposure to ammonia gas, ammonium hydroxide, or to the vapors or solutions of a volatile amine at room temperature; and the precured article is irradiated with high energy electrons or gamma radiation to effect a permanent cure of the material from which the article is formed

E-Beam-Cured Layered-Silicate and Spherical Silica Epoxy Nanocomposites (Preprint)

National Research Council Canada - National Science Library

Chen, Chenggang; Anderson, David P

2007-01-01

.... The nanofillers can be two dimensional (layered-silicate) and zero dimensional (spherical silica). Both the spherical silica epoxy nanocomposite and the layered-silicate epoxy nanocomposite can be cured to a high degree of curing...

Influence of amine structure on the post-cured photo-yellowing of novel amine diacrylate terminated ultraviolet and electron beam cured coatings

International Nuclear Information System (INIS)

Allen, N.S.; Lo, D.

1990-01-01

The post ultraviolet (UV) and electron beam (EB) cured photo-yellowing of nine novel amine terminated diacrylate monomers has been compared with that of standard commercial diethylamine diacrylate monomer using second order derivative UV absorption spectroscopy. Whilst all the UV cured monomers exhibited an initial rapid growth in UV absorption followed by a rapid photo-bleaching, the EB cured monomers exhibited a very slow growth in absorption followed by a plateau and subsequent slow photo-bleaching. In the former case the residual benzophenone photo-initiator is sensitising the photo-yellowing reaction and its subsequent photo-bleaching. Differences in the rates may be determined by the nature of the exciplex between the terminal amine groups and the benzophenone initiator. With regard to the nature of the amine structure all the simple alkylamines exhibit the greatest degree of photo-yellowing whilst hydroxyl containing amines are generally lower. In the former case methylene hydrogen atoms alpha to the nitrogen atom are important for abstraction. Dicyclohexylamine provides the most stable monomer toward photo-yellowing due to the stability of the alpha methylene hydrogen atoms and steric hindrance by the two bulky cyclohexane rings towards the formation of conjugated chromophores. For the EB cured monomers the degree of photo-yellowing increases with increasing alkyl chain length of the amine group due to the increased possibility of the formation of conjugated chromophores. (author)

Effect of Light Curing Unit Characteristics on Light Intensity Output ...

African Journals Online (AJOL)

Background: Modern dental composite restorations are wholly dependent on the use of Visible Light Curing devices. The characteristics of these devices may influence the quality of composite resin restorations. Objective: To determine the characteristics of light curing units (LCUs) in dental clinics in Nairobi and their effect ...

Beam in on curing

International Nuclear Information System (INIS)

Holl, Dr.

1981-01-01

This third part of an article on the electron beam curing of paints covers the following aspects: inertising equipment; working without inert gas; increase in temperature when irradiating; irradiating plants; laboratory plants; plant operating from coil to coil; plant for shaped parts; possible applications; decorative films, paper, PVC; packaging material; metallisation of paper films; film bonding; strengthening of flock; coating; pressure sensitive adhesives. (U.K.)

Significance of grafting in radiation curing reactions. Comparison of ionising radiation and UV systems

International Nuclear Information System (INIS)

Zilic, E.; Ng, L.; Viengkhou, V.; Garnett, J.L.

1998-01-01

Full text: Radiation curing is now an accepted commercial technology where both ionising radiation (electron beam) and ultra violet light (UV) sources are used. Grafting is essentially the copolymerisation of a monomer/oligomer to a backbone polymer whereas curing is the rapid polymerisation of a monomer/oligomer mixture onto the surface of the substrate. There is no time scale theoretically associated with grafting processes which can occur in minutes or hours whereas curing reactions are usually very rapid, occurring within a fraction of a second. An important difference between grafting and curing is the nature of the bonding occurring in each process. In grafting covalent carbon-carbon bonds are formed, whereas in curing, bonding usually involves weaker Van der Waals or London dispersion forces. The bonding properties of the systems are important in determining their use commercially. Thus the possibility that concurrent grafting during curing could occur in a system is important since if present, grafting would not only minimise delamination of the coated product but could also, in some circumstances, render difficulties recycling of the finished product especially if it were cellulosic. Hence the conditions for observing the occurrence of concurrent grafting during radiation curing are important. In the present paper, this problem has been studied by examining the effect that the components used in radiation curing exert on a typical reaction. Instead of electron beam sources, the spent fuel element facility at Lucas Heights is used to simulate such ionising radiation sources. The model system utilised is the grafting of a typical methacrylate to cellulose. This is the generic chemistry used in curing systems. The effect of typical additives from curing systems including polyfunctional monomer and oligomers in the grafting reactions have been studied. The ionising radiation results have been compared with analogous data from UV experiments. The significance

Cure shrinkage in casting resins

Energy Technology Data Exchange (ETDEWEB)

Spencer, J. Brock [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-02-01

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

Are we eliminating cures with antibiotic abuse? A study among ...

African Journals Online (AJOL)

Context: The theme of “World Health Day 2011” is “combat drug resistance- No action today, No cure tomorrow” which is very pertinent. The present study emphatically demonstrates the current issues related to the overwhelming concerns regarding indiscriminate use of antibiotics, leading to a bleak tomorrow where cures ...

Beliefs about the causes and cures of depression

OpenAIRE

Furnham, Adrian; Ritchie, William; Lay, Alixe

2016-01-01

Aims: To test whether the group would recognise both vignettes with having depression and that the favoured cure would be Psychotherapy/Talking Cure. Method: In all, 320 adults completed a two-part questionnaire. In the first part, they were given two vignettes describing a 30-year-old female and a 45-year-old male both with depression. They were asked what they thought (if anything) was wrong with the person and how they could best be helped. In the second part, they completed two ...

Cure kinetics and mechanical interfacial characteristics of zeolite/DGEBA composites

International Nuclear Information System (INIS)

Park, Soo Jin; Kim, Young Mi; Shin, Jae Sup

2003-01-01

In this work, the zeolite/diglycidylether of bisphenol A(DGEBA) systems were investigated in terms of the cure kinetics and mechanical interfacial properties of the composites. The 4, 4-Diamino Diphenyl Methane(DDM) was used as a curing agent for epoxy. Two types of zeolite(PZ) were prepared with 15 and 35 wt% KOH treatments(15-BZ and 35-BZ, respectively) for 24 h, and their surface characteristics were studied by X-ray Photoelectron Spectroscopy (XPS) and X-Ray Diffraction (XRD). Cure kinetics of the composites were examined in the context of Differential Scanning Calorimetry(DSC), and mechanical interfacial properties were investigated in critical stress intensity factor(K IC ) and critical strain energy release rate(G IC ). In the results of XPS and XRD, sodium ion(Na) of zeolite was exchanged for potassium ion(K), resulting from the treatment of KOH. Also, Si 2p /A1 2p composition ratios of the treated zeolite were increased, which could be attributed to the weakening of A1-O bond in framework. Cure activation energy(E a ) of 15-BZ composites was decreased, whereas K IC and G IC were increased, compared with those of the pure zeolite/DGEBA composites. It was probably accounted that the acidity of zeolite was increased by surface treatments and the cure reaction between zeolite and epoxy was influenced on the increased acidity of zeolite

Additives in UV and ionising radiation grafting and curing processes

International Nuclear Information System (INIS)

Garnett, J.L.; Ng, L.T.; Viengkhou, V.

1998-01-01

Full text: Curing of polymers induced by both UV and ionising radiation are now established technologies. Currently both systems are predominantly based on acrylate chemistry. UV processes use photoinitiators to achieve fast polymerisation. In the proposed paper the significance of the occurrence of concurrent grafting with cure will be examined. particularly with respect to the recycling of finished product. Basic studies on grafting initiated by UV and ionising radiation will be discussed. Polar methyl methacrylate (MMA) and non-polar styrene will be used as representative monomers with cellulose and propylene typifying the backbone polymers. The additives chosen for examination in this study are predominantly components used in radiation curing formulations since grafting and curing are known to be mechanically related. The additives used were mineral acid, photoinitiators, vinyl ethers, oligomers, polyfunctional monomers including multifunctional acrylates (MFAs) and methacrylates (MFMAs). For the first time the use of charge transfer complexes in the Mulliken sense as additives in radiation grafting will be discussed. The CT complexes themselves, being monomers, have also been grafted to the above polymers. Recent developments with excimer laser sources for initiating these processes will be discussed, especially the use of non-acrylate chemistry. Excimer laser sources are shown to complement conventional UV and ionising radiation and are photoinitiator free. Mechanisms for the above grafting and curing processes will be outlined

Glass transition and degree of conversion of a light-cured orthodontic composite

Directory of Open Access Journals (Sweden)

Michela M. D. S. Sostena

2009-12-01

Full Text Available OBJECTIVE: This study evaluated the glass transition temperature (Tg and degree of conversion (DC of a light-cured (Fill Magic versus a chemically cured (Concise orthodontic composite. MATERIAL AND METHODS: Anelastic relaxation spectroscopy was used for the first time to determine the Tg of a dental composite, while the DC was evaluated by infrared spectroscopy. The light-cured composite specimens were irradiated with a commercial LED light-curing unit using different exposure times (40, 90 and 120 s. RESULTS: Fill Magic presented lower Tg than Concise (35-84ºC versus 135ºC, but reached a higher DC. CONCLUSIONS: The results of this study suggest that Fill Magic has lower Tg than Concise due to its higher organic phase content, and that when this light-cured composite is used to bond orthodontic brackets, a minimum energy density of 7.8 J/cm² is necessary to reach adequate conversion level and obtain satisfactory adhesion.

Expert incentives: cure versus prevention

NARCIS (Netherlands)

de Jaegher, K.

This paper distinguishes between two scenarios for the expert-client encounter. In the cure scenario, the client does not know whether a loss can be recovered. In the prevention scenario, the client faces a threat but does not know whether this threat is real enough to justify preventive action. The

Curing Characterisation of Spruce Tannin-based Foams using the Advanced Isoconversional Method

Directory of Open Access Journals (Sweden)

Matjaž Čop

2014-06-01

Full Text Available The curing kinetics of foam prepared from the tannin of spruce tree bark was investigated using differential scanning calorimetry (DSC and the advanced isoconversional method. An analysis of the formulations with differing amounts of components (furfuryl alcohol, glycerol, tannin, and a catalyst showed that curing was delayed with increasing proportions of glycerol or tannins. An optimum amount of the catalyst constituent was also found during the study. The curing of the foam system was accelerated with increasing temperatures. Finally, the advanced isoconversional method, based on the model-free kinetic algorithm developed by Vyazovkin, appeared to be an appropriate model for the characterisation of the curing kinetics of tannin-based foams.

Effect of rheological parameters on curing rate during NBR injection molding

Science.gov (United States)

Kyas, Kamil; Stanek, Michal; Manas, David; Skrobak, Adam

2013-04-01

In this work, non-isothermal injection molding process for NBR rubber mixture considering Isayev-Deng curing kinetic model, generalized Newtonian model with Carreau-WLF viscosity was modeled by using finite element method in order to understand the effect of volume flow rate, index of non-Newtonian behavior and relaxation time on the temperature profile and curing rate. It was found that for specific geometry and processing conditions, increase in relaxation time or in the index of non-Newtonian behavior increases the curing rate due to viscous dissipation taking place at the flow domain walls.

'Every disease has its cure': faith and HIV therapies in Islamic ...

African Journals Online (AJOL)

'Every disease has its cure': faith and HIV therapies in Islamic northern Nigeria. ... African Journal of AIDS Research ... a divine cure for HIV exists, many Muslim patients on ART, and the predominantly Muslim biomedical staff who treat them, ...

The influence of curing time on the shear strength of fluidized fly ash

Directory of Open Access Journals (Sweden)

Gruchot Andrzej

2015-06-01

Full Text Available The paper presents results of research on the influence of compaction and air and water curing on angle of internal friction and cohesion of fluidized fly ash from “Połaniec” Power Plant. It was stated that the increase in compaction resulted in an insignificant increase of the angle of internal friction and a quite significant increase of cohesion. While the type and time of curing had a great influence on the angle of internal friction and cohesion. The highest values of angle of internal friction were obtained in the air curing, and the lowest in the water curing whereas in case of cohesion there was an inverse relation. The rise of curing time resulted in largely increased cohesion and small changes of angle of internal friction.

7 CFR 29.6002 - Air-cured.

Science.gov (United States)

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Air-cured. 29.6002 Section 29.6002 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... resulting from the application of artificial heat. ...

The chemistry of UV and EB radiation curing

International Nuclear Information System (INIS)

Garnett, J.L.

1987-01-01

The application of photopolymerisation (UV) and electron beam (EB) technologies in radiation rapid cure (RRC) processing is discussed. The chemistry associated with such reactions and the mechanisms of the processes are treated. The occurrence of concurrent grafting to substrate with radiation curing of film is shown to be an advantage in enhancing the properties of certain finished products. The parameters influencing the optimum grafting yield in such RRC processes are discussed. In many applications, the chemistry of the process combined with the machine, expecially for EB, is shown a so-called ''turn-key'' operation. (author)

The chemistry of UV and BE radiation curing

International Nuclear Information System (INIS)

Garnett, J.L.

1991-01-01

The application of photopolymerisation (UV) and electron beams (EB) technologies in radiation rapid cure (PRC) processing is discussed. The chemistry associated with such reactions and the mechanisms of the processes are treated. The occurrence of concurrent grafting to substrate with radiation curing of films is shown to be an advantage in enhancing the properties of certain finished products. The parameters influencing the optimum grafting yield in such PRC processes are discussed. In many applications, the chemistry of such processes combined with the machine, specially for EB is shown. (author)

effect of light intensity on the cure characteristics of photo

African Journals Online (AJOL)

2012-05-05

May 5, 2012 ... Objective: To determine the light intensity emitted by light curing units (LCUs) and its effect on the cure characteristics of ... of carbon-carbon double bonds conversion (11-13). Additionally, the light intensity output of a ... increases within the unit and in the restoration. This heat not only contributes to the ...

Properties of ambient cured blended alkali activated cement concrete

Science.gov (United States)

Talha Junaid, M.

2017-11-01

This paper presents results of the development and strength properties of ambient-cured alkali activated geopolymer concrete (GPC). The study looks at the strength properties, such as compressive strength, splitting tensile strength, and elastic modulus of such concretes and its dependency on various parameters. The parameters studied in this work are the type and proportions of pre-cursor materials, type of activator and their respective ratios and the curing time. Two types of pre-cursor material; low calcium fly ash (FA) and ground granulated blast furnace slag (GGBFS) were activated using different proportions of sodium silicate and sodium hydroxide solutions. The results indicate that ambient cured geopolymer concrete can be manufactured to match strength properties of ordinary Portland cement concrete (OPC). The strength properties of GPC are dependent on the type and ratio of activator and the proportion of GGBFS used. Increasing the percentage of GGBFS increased the compressive and tensile strengths, while reducing the setting time of the mix. The effect of GGBFS on strength was more pronounced in mixes that contained sodium silicate as activator solution. Unlike OPC, ambient-cured GPC containing sodium silicate gain most of their strength in the first 7 days and there is no change in strength thereafter. However, GPC mixes not containing sodium silicate only achieve a fraction of their strength at 7 days and extended curing is required for such concretes to gain full strength. The results also indicate that the elastic modulus values of GPC mixes without sodium silicate are comparable to OPC while mixes with sodium silicate have elastic modulus values much lower than ordinary concrete.

Effect of Modified Natural Rubber on PVC-ENR Electrospun Membrane: Thermal and Morphological Studies

International Nuclear Information System (INIS)

Mahathir Mohamed; Dahlan Mohd; Ratnam, C.T.; Pairu Ibrahim

2016-01-01

Electrospun fibers membrane (EFM) based on modified epoxidized natural rubber (ENR) and polyvinyl chloride (PVC) was successfully prepared by electro spinning technique. Epoxidized natural rubber was firstly prepared in solution by using 5 L flask and exposed to high intensity UV lamp for degradation. The PVC/ ENR mixture solution concentration were about 16 wt% and blended for 5 hours for homogeneity. The PVC/ ENR mixture were electro spun to form fibers membrane. The sample of electro spun fibers membrane were cured by electron beam. The resulting membranes were characterized for thermal and morphological studies. Thermal decomposition behavior of EFM was analyzed by thermogravimetric analysis (TGA). Thermo gram from TGA showed two stages of degradation for all formulation (90:10, 80:20, 70:30 PVC/ ENR) from 240 to 265 degree Celsius and 400 to 410 degree Celsius, respectively. From the DSC thermo gram of PVC/ ENR electro spun fibers showed that the addition of ENR resulted in the shifting of glass transition temperature (Tg) towards lower temperatures. The morphology of electro spun fibers was examined using scanning electron microscopy and it showed a variety of fiber morphologies. (author)

Practical aspects of irradiance and energy in UV curing

International Nuclear Information System (INIS)

Stowe, R.W.

1999-01-01

The physical properties of UV-cured materials are substantially affected by the lamp systems used to cure them. The development of the intended properties, whether a varnish, an ink, or an adhesive, can depend on how well these lamp factors are designed and managed. The four key factors of UV exposure are: UV irradiance (or intensity), spectral distribution (wavelengths) of UV, effective energy (time-integrated UV irradiance), and infrared radiation. Inks and varnishes will exhibit very different response to peak irradiance or energy, as well as to different UV spectra. The ability to identify the various lamp characteristics and match them to the optical properties of the curable materials, widens the range in which UV curing is a faster, more efficient production process. This paper explores the reasons for clearly identifying these factors for process optimization

A study on the influence of curing on the strength of a standard grade concrete mix

OpenAIRE

Krishna Rao M.V.; Kumar Rathish P.; Khan Azhar M.

2010-01-01

Curing is essential if concrete is to perform the intended function over the design life of the structure while excessive curing time may lead to the escalation of the construction cost of the project and unnecessary delays. Where there is a scarcity of water and on sloping surfaces where curing with water is difficult and in cases where large areas like pavements have to be cured, the use of curing compound may be resorted to. The parameters of the study include the curing period [1, 3, 7, 1...

Sebastian Kneipp and the Natural Cure Movement of Germany: Between Naturalism and Modern Medicine

Directory of Open Access Journals (Sweden)

Youkyung KO

2016-12-01

Full Text Available This study discusses the historical significance of the Natural Cure Movement of Germany, centering on the Kneipp Cure, a form of hydrotherapy practiced by Father Sebastian Kneipp (1821-1897. The Kneipp Cure rested on five main tenets: hydrotherapy, exercise, nutrition, herbalism, and the balance of mind and body. This study illuminates the reception of the Kneipp Cure in the context of the trilateral relationship among the Kneipp Cure, the Natural Cure Movement in general, and modern medicine. The Natural Cure Movement was ideologically based on naturalism, criticizing industrialization and urbanization. There existed various theories and methods in it, yet they shared holism and vitalism as common factors. The Natural Cure Movement of Germany began in the early 19th century. During the late 19th century and the early 20th century, it became merged in the Lebensreformbewegung (life reform movement which campaigned for temperance, anti-tobacco, and anti-vaccination. The core of the Natural Cure Movement was to advocate the world view that nature should be respected and to recognize the natural healing powers of sunlight, air, water, etc. Among varied natural therapies, hydrotherapy spread out through the activities of some medical doctors and amateur healers such as Johann Siegmund Hahn and Vincenz Prie β nitz. Later, the supporters of hydrotherapy gathered together under the German Society of Naturopathy. Sebastian Kneipp, one of the forefathers of hydrotherapy, is distinguished from other proponents of natural therapies in two aspects. First, he did not refuse to employ vaccination and medication. Second, he sought to be recognized by the medical world through cooperating with medical doctors who supported his treatment. As a result, the Kneipp cure was able to be gradually accepted into the medical world despite the “quackery” controversy between modern medicine and the Natural Cure Movement. Nowadays, the name of Sebastian Kneipp

Influence of post pattern and resin cement curing mode on the retention of glass fibre posts.

Science.gov (United States)

Poskus, L T; Sgura, R; Paragó, F E M; Silva, E M; Guimarães, J G A

2010-04-01

To evaluate the influence of post design and roughness and cement system (dual- or self-cured) on the retention of glass fibre posts. Two tapered and smooth posts (Exacto Cônico No. 2 and White Post No. 1) and two parallel-sided and serrated posts (Fibrekor 1.25 mm and Reforpost No. 2) were adhesively luted with two different resin cements--a dual-cured (Rely-X ARC) and a self-cured (Cement Post)--in 40 single-rooted teeth. The teeth were divided into eight experimental groups (n = 5): PFD--Parallel-serrated-Fibrekor/dual-cured; PRD--Parallel-serrated-Reforpost/dual-cured; TED--Tapered-smooth-Exacto Cônico/dual-cured; TWD--Tapered-smooth-White Post/dual-cured; PFS--Parallel-serrated-Fibrekor/self-cured; PRS--Parallel-serrated-Reforpost/self-cured; TES--Tapered-smooth-Exacto Cônico/self-cured; TWS--Tapered-smooth-White Post/self-cured. The specimens were submitted to a pull-out test at a crosshead speed of 0.5 mm min(-1). Data were analysed using analysis of variance and Bonferroni's multiple comparison test (alpha = 0.05). Pull-out results (MPa) were: PFD = 8.13 (+/-1.71); PRD = 8.30 (+/-0.46); TED = 8.68 (+/-1.71); TWD = 9.35 (+/-1.99); PFS = 8.54 (+/-2.23); PRS = 7.09 (+/-1.96); TES = 8.27 (+/-3.92); TWS = 7.57 (+/-2.35). No statistical significant difference was detected for posts and cement factors and their interaction. The retention of glass fibre posts was not affected by post design or surface roughness nor by resin cement-curing mode. These results imply that the choice for serrated posts and self-cured cements is not related to an improvement in retention.

Response behavior of an epoxy resin/amine curing agent/carbon black composite film to various solvents

Energy Technology Data Exchange (ETDEWEB)

Luo Yanling [School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an 710062 (China)]. E-mail: luoyl0401@yahoo.com.cn; Li Zhanqing [School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an 710062 (China); Lan Wenxiang [School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an 710062 (China)

2007-04-25

A novel polymer based sensitive film was prepared from thermosetting epoxy resins (EP) filled with carbon blacks. The curing reaction of amine curing agents with epoxy resins and the response of the curing resultants to solvent vapors were dealt with. The influence of the types and content of carbon blacks and curing agents, and curing temperatures and time on curing reactions and response selectivity of the conductive films were investigated. The structural characterization was conducted on a Fourier transform infrared spectrophotometer (FTIR). The results indicated that the conductive films showed high response selectivity to polar solvent vapors, especially to chloroform vapor, while no response was observed in non-polar solvent vapors. The responsivity of the film increased with the decreased carbon black contents. The film filled with acetylene carbon black gave an optimal response, with responsivity of about 700 times. The response performances were improved with the amount of curing agents increased, and an optimal response appeared at the amount of the curing agent of 8%. The film's responsivity was remarkably enhanced, the reversibility property, however, rapidly declined in the order of diethyleneltriamine < triethylenetetramine < ethylenediamine. The curing reaction tended to complete with the curing temperature elevated and the curing time prolonged. But the response performance dropped because of over cross-linking as the temperature was too high or the time was too long.

Response behavior of an epoxy resin/amine curing agent/carbon black composite film to various solvents

International Nuclear Information System (INIS)

Luo Yanling; Li Zhanqing; Lan Wenxiang

2007-01-01

A novel polymer based sensitive film was prepared from thermosetting epoxy resins (EP) filled with carbon blacks. The curing reaction of amine curing agents with epoxy resins and the response of the curing resultants to solvent vapors were dealt with. The influence of the types and content of carbon blacks and curing agents, and curing temperatures and time on curing reactions and response selectivity of the conductive films were investigated. The structural characterization was conducted on a Fourier transform infrared spectrophotometer (FTIR). The results indicated that the conductive films showed high response selectivity to polar solvent vapors, especially to chloroform vapor, while no response was observed in non-polar solvent vapors. The responsivity of the film increased with the decreased carbon black contents. The film filled with acetylene carbon black gave an optimal response, with responsivity of about 700 times. The response performances were improved with the amount of curing agents increased, and an optimal response appeared at the amount of the curing agent of 8%. The film's responsivity was remarkably enhanced, the reversibility property, however, rapidly declined in the order of diethyleneltriamine < triethylenetetramine < ethylenediamine. The curing reaction tended to complete with the curing temperature elevated and the curing time prolonged. But the response performance dropped because of over cross-linking as the temperature was too high or the time was too long

Role of Oxides of Nitrogen in Tobacco-Specific Nitrosamine Formation in Flue-Cured Tobacco

Directory of Open Access Journals (Sweden)

Nestor TB

2014-12-01

Full Text Available Tobacco is known to contain a class of nitrosamines known as tobacco-specific nitrosamines or TSNA. Nitrosation of naturally occurring tobacco alkaloids is commonly accepted as the mechanism of TSNA formation in tobacco. Because green and freshly harvested tobaccos are virtually free of TSNA, formation and accumulation of TSNA are generally considered to occur during the curing process. Most recent hypotheses have focused on microbial reduction of nitrate to nitrite and other oxides of nitrogen (NOcompounds that react with tobacco alkaloids to form TSNA during curing. This natural microbial process remains the prevalent hypothesis for TSNA formation in burley and other air-cured tobaccos. However, a different mechanism for the formation of TSNA in flue-cured tobacco, independent of microbial activity, is documented in this paper. It is common practice to flue-cure Virginia or blonde tobacco in bulk barns that incorporate forced air ventilation and temperature control. For the last thirty-five years, many modern bulk barns in North America generally have used liquid propane gas (LPG with direct-fired burners that exhaust combustion gases directly into the barn where the tobacco is exposed to those gases. Our studies indicate that LPG combustion by-products in the exhaust stream, namely NO, react with naturally occurring tobacco alkaloids to form TSNA. Heat exchange curing methods preclude exposure of the tobacco to combustion gases and by-products, thereby eliminating this significant source of TSNA formation, without degrading leaf quality or smoking character. Research findings from 1998 and 1999 are presented to demonstrate the role of NOgases in TSNA formation and the significance of direct-fired curing as a primary source of TSNA formation in flue-cured tobacco. Also, data from an extensive barn conversion program in 2000, which resulted in a 94% average reduction in TSNA levels in cured flue-cured leaf, are presented.

Contribution for study on curing of organic coatings in papers, by electron beam

International Nuclear Information System (INIS)

Taqueda, M.H.S.

1986-01-01

The behaviour of national raw material is studied: paper, resins vamishes used on the surface finishing furniture, when subnitted to electron beam curing in an inert atmosphere. The dosimetric control of the irradiation system was made by using CTA films. The minimum cure dose obtained for the EBC 1650/3009 varnish(national polyester) was 2.4 Mrad and of 2.0 Mrad for the EBC 1650/3010 (imported polyester from Germany). The optimun cure dose for both was 3.0 Mrad. The papers impregnated with EBC varnish of with conventional varnish were measured mechanically for resistance in traction and an evaluation of resistance of the finished surfaces with the ebc varnishes was made. The coatings obtained with the EBC varnishes manufactured nationally were compared with the conventional vamishes of thermal cure and with paper samples impregnated and cured in Germany. (author) [pt

Efficient composite fabrication using electron-beam rapidly cured polymers engineered for several manufacturing processes

International Nuclear Information System (INIS)

Walton, T.C.; Crivello, J.V.

1995-01-01

Low cost, efficiently processed ultra high specific strength and stiffness graphite fiber reinforced polymeric composite materials are of great interest to commercial transportation, construction and aerospace industries for use in various components with enhanced degrees of weight reduction, corrosion/erosion resistance and fatigue resistance. 10 MeV Electron Beam cure processing has been found to increase the cure rate by an order of magnitude over thermally cured systems yet provide less molded in stresses and high T g s. However, a limited range of resins are available which are easily processed with low shrinkage and with performance properties equal or exceeding those of state of the art toughened epoxies and BMI's. The technology, introduced by an academia-industry partnership sparked by Langley Research Center utilizes a cost effective, rapid curing polymeric composite processing technique which effectively reduces the need for expensive tooling and energy inefficient autoclave processing and can cure the laminate in seconds (compared to hours for thermal curing) in ambient or sub-ambient conditions. The process is based on electron beam (E-Beam) curing of a new series of (65 to 1,000,000 cPs.) specially formulated resins that have been shown to exhibit excellent mechanical and physical properties once cured. Fabrication processes utilizing these specially formulated and newly commercialized resins, (e.g. including Vacuum Assist Resin Transfer molding (VARTM), vacuum bag prepreg layup, pultrusion and filament winding grades) are engineered to cure with low shrinkage, provide excellent mechanical properties, be processed solventless (environmentally friendly) and are inherently non toxic

How does duration of curing affect the radiopacity of dental materials?

Energy Technology Data Exchange (ETDEWEB)

Bejeh Mir, Arash Poorsattar [School of Dentistry, Babol University of Medical Sciences, Babol (Iran, Islamic Republic of); Bejeh Mir, Morvarid Poorsattar [Private Practice of Orthodontics, Montreal (Canada)

2012-06-15

Clinicians commonly encounter cases in which it is difficult to determine whether adjacent radiopacities are normal or pathologic. The ideal radiopacity of composite resin is equal to or higher than that of the same thickness of aluminum. We aimed to investigate the possible effects of different curing times on the post-24-hour radiopacity of composite resins on digital radiographs. One mm thick samples of Filtek P60 and Clearfil resin composites were prepared and cured with three regimens of continuous 400 mW/cm{sup 2} irradiance for 10, 20 and 30 seconds. Along with a 12-step aluminum step wedge, digital radiographs were captured and the radiopacities were transformed to the equivalent aluminum thicknesses. Data were compared by a general linear model and repeated-measures of ANOVA. Overall, the calculated equivalent aluminum thicknesses of composite resins were increased significantly by doubling and tripling the curing times (F(2,8)=8.94, p=0.002). Notably, Bonferroni post-hoc tests confirmed that the radiopacity of the cured Filtek P60 was significantly higher at 30 seconds compared with 10 seconds (p=0.04). Although the higher radiopacity was observed by increasing the time, other comparisons showed no statistical significance (p>0.05). These results supported the hypothesis that the radiopacity of resin composites might be related to the duration of light curing. In addition to the current standards for radiopacity of digital images, defining a standard protocol for curing of dental materials should be considered, and it is suggested that they should be added to the current requirements for dental material.

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

Science.gov (United States)

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.

How does duration of curing affect the radiopacity of dental materials?

International Nuclear Information System (INIS)

Bejeh Mir, Arash Poorsattar; Bejeh Mir, Morvarid Poorsattar

2012-01-01

Clinicians commonly encounter cases in which it is difficult to determine whether adjacent radiopacities are normal or pathologic. The ideal radiopacity of composite resin is equal to or higher than that of the same thickness of aluminum. We aimed to investigate the possible effects of different curing times on the post-24-hour radiopacity of composite resins on digital radiographs. One mm thick samples of Filtek P60 and Clearfil resin composites were prepared and cured with three regimens of continuous 400 mW/cm 2 irradiance for 10, 20 and 30 seconds. Along with a 12-step aluminum step wedge, digital radiographs were captured and the radiopacities were transformed to the equivalent aluminum thicknesses. Data were compared by a general linear model and repeated-measures of ANOVA. Overall, the calculated equivalent aluminum thicknesses of composite resins were increased significantly by doubling and tripling the curing times (F(2,8)=8.94, p=0.002). Notably, Bonferroni post-hoc tests confirmed that the radiopacity of the cured Filtek P60 was significantly higher at 30 seconds compared with 10 seconds (p=0.04). Although the higher radiopacity was observed by increasing the time, other comparisons showed no statistical significance (p>0.05). These results supported the hypothesis that the radiopacity of resin composites might be related to the duration of light curing. In addition to the current standards for radiopacity of digital images, defining a standard protocol for curing of dental materials should be considered, and it is suggested that they should be added to the current requirements for dental material.

Effect of bench time polymerization on depth of cure of dental composite resin

Science.gov (United States)

Harahap, K.; Yudhit, A.; Sari, F.

2017-07-01

The aim of this research was to investigate the effect of bench time before light cured polymerization on the depth of cure of dental composite resin. Nanofiller composite resin (Filtek Z350 XT,3M, ESPE,China) was used in this study. Sixty samples of nanofiller composite resin were made and divided into control and test groups with bench time for 0, 15, 30, 45, and 60 min. For the test group, composite resins were stored in refrigerator with 4°C temperatures. Meanwhile, for the control groups, the composite resin was stored at room temperature. The samples were prepared using metal mould with size diameter of 6 mm and 4 mm in thickness. Samples were cured for 20 s by using visible blue light curing unit. Part of samples that unpolymerized were removed by using a plastic spatula. The remaining parts of samples were measured by digital caliper and noted as depth of cure (mm). Data were analyzed to one-way ANOVA and LSD tests (p≤0.05). Results showed there was no significance differences between test groups (p=0.5). A 60 minutes bench time group showed the highest depth of cure value among test group, and it was almost similar with control group value. It can be concluded that longer bench time can increase the depth of cure of composite resin.

UV curing of teak veneers for decorative panel

International Nuclear Information System (INIS)

Gatot Trimulyadi Rekso; Darsono

1999-01-01

The radiation curing of surface coating of teak veneers for decorative panels has been conducted by using ultra violet (UV) as radiation source. In this experiment teak wood veneer was use as a substrate. Epoxy acrylate (import product,) and unsaturated polyester (locally product) were used as coating materials after being added with difunctional monomer TPGDA, and photo-initiator darocur 1173 or irgacure 184. Irradiation was conducted using 80 watt/cm LTV source at conveyor speed of 3,0 m/min. Parameters observed were viscosity of coating materials, hardness, adhesion, appearance, abrasion and chemical resistance of cured films. In general the results showed that viscosity of the formulations based on epoxy acrylate and unsaturated polyester resin were effected by the storage. Film cured by LTV made of epoxy acrylate and unsaturated polyester on the teak veneer wood have the same adhesion and abrasion resistant properties but the hardness and chemical resistant of epoxy acrylate are better than unsaturated polyester. From the experiment result it can be concluded the unsaturated polyester (locally product) can be used as radiation curable material for coating teak veneer panels

How far is cancer cured by radiation sensitization?

International Nuclear Information System (INIS)

Ando, Koichi; Sasaki, Takehito; Ikeda, Hiroshi

1990-01-01

Some types of cancer are not cured by radiation alone in view of histology, location, and size. In facing so-called radioresistant cancer, antineoplastic agents, hypoxic cell sensitizers, biological response modifiers, or hyperthermia are used in combination with radiation, with the aim of cancer cure. First of all, this chapter discusses the subject of 'what is tumor cure by radiation therapy'. Current conditions of the aforementioned combined modalities and the future perspectives are presented. The following subjects are covered: (1) tumor control - significance of the number of stem cells; (2) biological evaluation of chemo-radiotherapy with cisplatin; (3) clinical results and experience with combination of radiotherapy and radiosensitizers; (4) radiosensitization with hypoxic cell radiosensitizers - present status (5) hypoxic cell radiosensitizers - present status and problems from the viewpoint of clinical radiotherapy; (6) thermal radiosensitization in vitro and its implications for radiotherapy; (7) clinical assessment of thermoradiotherapy for breast cancer and cancer of the urinary bladder; (8) interactions of radiation and biological response modifiers in the treatment of malignant tumor; (9) improvement in the effects of radiation therapy with biological response modifiers. (N.K.)

Optimal temperature profiles for minimum residual stress in the cure process of polymer composites

CSIR Research Space (South Africa)

Gopal, AK

2000-01-01

Full Text Available include the minimum residual stresses, minimum cure cycle lime and full degree of cure. The development of residual stresses during the cure cycle is one of the most important problems as they affect the strength and the mechanical properties of the final...

Use of natural ingredients to control growth of Clostridium perfringens in naturally cured frankfurters and hams.

Science.gov (United States)

Jackson, Armitra L; Kulchaiyawat, Charlwit; Sullivan, Gary A; Sebranek, Joseph G; Dickson, James S

2011-03-01

A major concern for processed meats marketed as natural/organic is that they do not contain nitrite in concentrations known to be most effective for inhibiting foodborne pathogens. Supplemental treatments to increase the level and consistency of antimicrobial protection in these products may be important to provide consumers with the degree of safety that they have come to expect from conventionally cured meats. Therefore, the objective of this study was to identify and test ingredients that might improve processed meat product safety without altering their natural/organic status. Eight treatments of hams and frankfurters were prepared: (A) uncured control (typical ingredients except nitrite and nitrate); (B) conventionally cured control (erythorbate, nitrite, and a lactate-diacetate blend); (C) natural nitrate cure (including starter culture containing Staphylococcus carnosus); (D) natural nitrate cure (culture and natural antimicrobial A containing a vinegar, lemon, and cherry powder blend); (E) natural nitrate cure (culture and antimicrobial B containing a cultured sugar and vinegar blend); (F) natural nitrite cure without additional antimicrobials; (G) natural nitrite cure with natural antimicrobial A; and (H) natural nitrite cure with antimicrobial B. For the hams, treatments C, D, E, and H impacted growth of Clostridium perfringens to the same extent (P cured control (approximately 2 log less growth over time than uncured control). For frankfurters, treatments D, G, and H had an effect (approximately 1 log) on growth equivalent to that of the conventionally cured control (P cured meats have more potential for pathogen growth than conventionally cured products, but supplemental natural ingredients offer safety improvement.

Inkjet-printed silver tracks : low temperature curing and thermal stability investigation

NARCIS (Netherlands)

Perelaer, J.; Laat, de A.W.M.; Hendriks, C.E.; Schubert, U.S.

2008-01-01

In this contribution the curing behavior and conductivity development of several commercially available silver inks is discussed. In addition, the preparation and characterization of a silver particle ink that shows a curing temperature as low as 80 ÝC is described. Good to excellent conductivity

Low Temperature Cure Powder Coatings (LTCPC)

Science.gov (United States)

2010-10-01

Dr. Glen Merfeld, General Electric Global Research evaluated and optimized the formulation, and cure and performance parameters of candidate LTCPC...Unacceptable test result = Marginal test result = Acceptable test result 80 therefore suffer from brittleness at extremely low temperatures. NASA’s

Prospects of success of radon cures in patients with progressive sclerodermia

International Nuclear Information System (INIS)

Brenke, R.; Brenke, A.

1989-01-01

Physiotherapy and spa-therapy occupy a high value in the treatment of the progressive sclerodermia. On the basis of 59 radon cures at Bad Brambach in patients with this disease is shown that a success of the cure lasting for a long time is to be expected particularly in patients with a relatively bad initial situation. Above all an amelioration of the subjective condition as well as the movability of the joints is achieved. The necessity of repeated cures for selected patients at an interval of 1 to 2 years is discussed. There was no evidence concerning a possibly specific radon effect. (author)

CUREs in biochemistry—where we are and where we should go

Science.gov (United States)

Bell, Jessica K.; Eckdahl, Todd T.; Hecht, David A.; Killion, Patrick J.; Latzer, Joachim; Mans, Tamara L.; Rakus, John F.; Siebrasse, Erica A.; Ellis Bell, J.

2016-01-01

Abstract Integration of research experience into classroom is an important and vital experience for all undergraduates. These course‐based undergraduate research experiences (CUREs) have grown from independent instructor lead projects to large consortium driven experiences. The impact and importance of CUREs on students at all levels in biochemistry was the focus of a National Science Foundation funded think tank. The state of biochemistry CUREs and suggestions for moving biochemistry forward as well as a practical guide (supplementary material) are reported here. © 2016 by The International Union of Biochemistry and Molecular Biology, 45(1):7–12, 2017. PMID:27357379

The characteristics of epoxy resin cured by {gamma}-ray and E-beam

Energy Technology Data Exchange (ETDEWEB)

Nho, Y.C. E-mail: ycnho@kaeri.re.kr; Kang, Phil Hyun; Park, Jong Seok

2004-10-01

Epoxy resins are widely used as high-performance thermosetting resins for many industrial applications. In this study, the effect of an electron beam (E-beam) and {gamma}-ray irradiation on the curing of epoxy resins was investigated. Diglycidyl ether of bisphenol-A(DGEBA), diglycidyl ether of bisphenol-F(DGEBF) as epoxy resins, triarylsulfonium hexafluoroantimonate(TASHFA), and triarylsulfonium hexafluorophosphate(TASHFP) as initiators were used in this study. The chemical and mechanical characteristics of irradiated epoxy resins were compared after curing of E-beam and {gamma}-ray irradiation up to 50 kGy in N{sub 2} and air atmosphere. We ascertained the effect of oxygen on the radiation curing of epoxy resin. The thermal properties of cured epoxy were investigated using DMA and TGA. Mechanical properties such as flexural strength were measured. The chemical structures of cured epoxy were characterized by FT-NIR. The gel fraction and the stress at yield of epoxy resins irradiated by E-beam and {gamma}-ray in N{sub 2} atmosphere were also compared with those of epoxy resins irradiated by E-beam and {gamma}-ray in air.

Monitoring cure properties of out-of-autoclave BMI composites using IFPI sensor

Science.gov (United States)

Kaur, Amardeep; Anandan, Sudharshan; Yuan, Lei; Watkins, Steve E.; Chandrashekhara, K.; Xiao, Hai; Phan, Nam

2016-04-01

A non-destructive technique for inspection of a Bismaleimide (BMI) composite is presented using an optical fiber sensor. High performance BMI composites are used for Aerospace application for their mechanical strength. They are also used as an alternative to toughened epoxy resins. A femtosecond-laser-inscribed Intrinsic Fabry-Perot Interferometer (IFPI) sensor is used to perform real time cure monitoring of a BMI composite. The composite is cured using the out-of-autoclave (OOA) process. The IFPI sensor was used for in-situ monitoring; different curing stages are analyzed throughout the curing process. Temperature-induced-strain was measured to analyze the cure properties. The IFPI structure comprises of two reflecting mirrors inscribed on the core of the fiber using a femtosecond-laser manufacturing process. The manufacturing process makes the sensor thermally stable and robust for embedded applications. The sensor can withstand very high temperatures of up to 850 °C. The temperature and strain sensitivities of embedded IFPI sensor were measured to be 1.4 pm/μepsilon and 0.6 pm/μepsilon respectively.

The Effects of Different Curing Methods on the Compressive Strength of Terracrete

Directory of Open Access Journals (Sweden)

O. Alake

2009-01-01

Full Text Available This research evaluated the effects of different curing methods on the compressive strength of terracrete. Several tests that included sieve analysis were carried out on constituents of terracrete (granite and laterite to determine their particle size distribution and performance criteria tests to determine compressive strength of terracrete cubes for 7 to 35 days of curing. Sand, foam-soaked, tank and open methods of curing were used and the study was carried out under controlled temperature. Sixty cubes of 100 × 100 × 100mm sized cubes were cast using a mix ratio of 1 part of cement, 1½ part of latrite, and 3 part of coarse aggregate (granite proportioned by weight and water – cement ratio of 0.62. The result of the various compressive strengths of the cubes showed that out of the four curing methods, open method of curing was the best because the cubes gained the highest average compressive strength of 10.3N/mm2 by the 35th day.

Proton conductive membranes based on poly (styrene-co-allyl alcohol semi-IPN

Directory of Open Access Journals (Sweden)

Felipe Augusto Moro Loureiro

2014-01-01

Full Text Available The optimization of fuel cell materials, particularly polymer membranes, for PEMFC has driven the development of methods and alternatives to achieve systems with more adequate properties to this application. The sulfonation of poly (styrene-co-allyl alcohol (PSAA, using sulfonating agent:styrene ratios of 2:1, 1:1, 1:2, 1:4, 1:6, 1:8 and 1:10, was previously performed to obtain proton conductive polymer membranes. Most of those membranes exhibited solubility in water with increasing temperature and showed conductivity of approximately 10-5 S cm-1. In order to optimize the PSAA properties, especially decreasing its solubility, semi-IPN (SIPN membranes are proposed in the present study. These membranes were obtained from the diglycidyl ether of bisphenol A (DGEBA, curing reactions in presence of DDS (4,4-diaminodiphenyl sulfone and PSAA. Different DGEBA/PSAA weight ratios were employed, varying the PSAA concentration between 9 and 50% and keeping the mass ratio of DGEBA:DDS as 1:1. The samples were characterized by FTIR and by electrochemical impedance spectroscopy. Unperturbed bands of PSAA were observed in the FTIR spectra of membranes, suggesting that chemical integrity of the polymer is maintained during the synthesis. In particular, bands involving C-C stretching (1450 cm-1, C=C (aromatic, ~ 3030 cm-1 and C-H (2818 and 2928 cm-1 were observed, unchanged after the synthesis. The disappearance or reduction of the intensity of the band at 916 cm-1, attributed to the DGEBA epoxy ring, is evidenced for all samples, indicating the epoxy ring opening and the DGEBA crosslinking. Conductivity of H3PO4 doped membranes increases with temperature, reaching 10-4 S cm-1.

Light output from six battery operated dental curing lights

Energy Technology Data Exchange (ETDEWEB)

Shimokawa, Carlos Alberto Kenji, E-mail: carlos.shimokawa@usp.br [University of São Paulo, School of Dentistry, Restorative Dentistry, Avenida Professor Lineu Prestes, 2227, 05508-000, São Paulo, São Paulo (Brazil); Dalhousie University, Faculty of Dentistry, Dental Clinical Sciences, 5981 University Avenue, B3H 4R2, Halifax, Nova Scotia (Canada); Turbino, Míriam Lacalle, E-mail: miturbin@usp.br [University of São Paulo, School of Dentistry, Restorative Dentistry, Avenida Professor Lineu Prestes, 2227, 05508-000, São Paulo, São Paulo (Brazil); Harlow, Jessie Eudora, E-mail: jessie.harlow@dal.ca [Dalhousie University, Faculty of Dentistry, Dental Clinical Sciences, 5981 University Avenue, B3H 4R2, Halifax, Nova Scotia (Canada); Price, Hannah Louise, E-mail: hannlprice@gmail.com [Dalhousie University, Faculty of Dentistry, Dental Clinical Sciences, 5981 University Avenue, B3H 4R2, Halifax, Nova Scotia (Canada); Price, Richard Bengt, E-mail: richard.price@dal.ca [Dalhousie University, School of Biomedical Engineering and Faculty of Dentistry, 5981 University Avenue, B3H 4R2, Halifax, Nova Scotia (Canada)

2016-12-01

Light Curing Units (LCUs) are used daily in almost every dental office to photocure resins, but because the light is so bright, the user is unable to tell visually if there are any differences between different LCUs. This study evaluated the light output from six dental LCUs: Elipar Deep Cure-S (3M ESPE), Bluephase G2 (Ivoclar Vivadent), Translux 2Wave (Heraeus Kulzer), Optilight Prime (Gnatus), Slim Blast (First Medica) and Led.B (Guilin Woodpecker) with a fully charged battery, after 50, and again after 100, 20 second light exposures. For each situation, the radiant power was measured 10 times with a laboratory-grade power meter. Then, the emission spectrum was measured using a fiber-optic spectrometer followed by an analysis of the light beam profile. It was found there were significant differences in the LCU power and the irradiance values between the LCUs (p < 0.01). The Optilight Prime and Slim Blast LCUs showed a significant reduction in light output after a 50 and 100 exposures, while Bluephase G2 exhibited a significant reduction only after 100 exposures (p < 0.01). The Bluephase G2 and Translux 2 Wave delivered an emission spectrum that had two distinct wavelength emission peaks. Only the Elipar Deep Cure-S and Bluephase G2 LCUs displayed homogeneous light beam profiles, the other LCUs exhibited highly non-homogeneous light beam profiles. It was concluded that contemporary LCUs could have very different light output characteristics. Both manufacturers and researchers should provide more information about the light output from LCUs. - Highlights: • The six LCUs delivered significantly different light output characteristics. • The use of a single irradiance value does not adequately describe the light output from a curing light. • Small differences in the tip area, or how it is defined, will have a large effect on the calculated irradiance. • In some cases there were large portions of the light tip that emitted less than 400 mW/cm². • The radiant

Light output from six battery operated dental curing lights

International Nuclear Information System (INIS)

Shimokawa, Carlos Alberto Kenji; Turbino, Míriam Lacalle; Harlow, Jessie Eudora; Price, Hannah Louise; Price, Richard Bengt

2016-01-01

Light Curing Units (LCUs) are used daily in almost every dental office to photocure resins, but because the light is so bright, the user is unable to tell visually if there are any differences between different LCUs. This study evaluated the light output from six dental LCUs: Elipar Deep Cure-S (3M ESPE), Bluephase G2 (Ivoclar Vivadent), Translux 2Wave (Heraeus Kulzer), Optilight Prime (Gnatus), Slim Blast (First Medica) and Led.B (Guilin Woodpecker) with a fully charged battery, after 50, and again after 100, 20 second light exposures. For each situation, the radiant power was measured 10 times with a laboratory-grade power meter. Then, the emission spectrum was measured using a fiber-optic spectrometer followed by an analysis of the light beam profile. It was found there were significant differences in the LCU power and the irradiance values between the LCUs (p < 0.01). The Optilight Prime and Slim Blast LCUs showed a significant reduction in light output after a 50 and 100 exposures, while Bluephase G2 exhibited a significant reduction only after 100 exposures (p < 0.01). The Bluephase G2 and Translux 2 Wave delivered an emission spectrum that had two distinct wavelength emission peaks. Only the Elipar Deep Cure-S and Bluephase G2 LCUs displayed homogeneous light beam profiles, the other LCUs exhibited highly non-homogeneous light beam profiles. It was concluded that contemporary LCUs could have very different light output characteristics. Both manufacturers and researchers should provide more information about the light output from LCUs. - Highlights: • The six LCUs delivered significantly different light output characteristics. • The use of a single irradiance value does not adequately describe the light output from a curing light. • Small differences in the tip area, or how it is defined, will have a large effect on the calculated irradiance. • In some cases there were large portions of the light tip that emitted less than 400 mW/cm². • The radiant

Strength development of concrete made with recycled glass aggregates subjected to frost curing conditions

OpenAIRE

Poutos, Konstantinos; Nwaubani, Sunny

2013-01-01

An experimental investigation was undertaken to study whether the strength behavior of concrete made with glass aggregate differed significantly from that made with natural aggregates when concretes cured in low temperatures. The aim of the research work presented is to examine the strength behavior of glass concrete when cured under freezing conditions at -15°C and -10°C. The results showed that when glass concrete is cured at low curing temperature, the 28 day compressive strength is higher...

Development of greenhouse solar systems for bulk tobacco curing and plant production

Energy Technology Data Exchange (ETDEWEB)

Huang, B.K.; Bowers, C.G. Jr.

1986-12-01

Among many farm crops, bright leaf tobacco is the most energy- and labor-intensive crop. The greenhouse solar system (solar bulk-curing/greenhouse system, or solar barn) was developed to provide multiple-use facilities for year-round solar energy utilization to save fossil fuels in tobacco curing and plant production and to facilitate the total mechanization of tobacco culture. Two types of full-size greenhouse solar systems, the load-supporting wall design and the shell design, both utilizing the thermal envelope concept, were designed and constructed for solar bulk-curing of tobacco, growing transplants and horticultural crops under controlled environment, and aiding automation of transplanting operations. Full-scale field tests of solar bulk curing showed that the fuel savings were consistantly improved from 37% in 1975 to 51% in 1978 for this solar bulk-curing system as compared with a conventional bulk-curing barn as a control. The feasibility of the system to save energy by using solar energy as a first priority source was significantly demonstrated. Three-year greenhouse and field tests showed that high germination rate of 95-97% with excellent emergence frequency was obtained for tobacco seeds under the controlled environment provided by the greenhouse solar system. In general, the containerized transplants from greenhouse solar system significantly exceeded the conventional bare-root transplants in growth, leaf-quality and yield. 9 figs., 3 tabs., 10 refs.

Patients cured of acromegaly do not experience improvement of their skull deformities.

Science.gov (United States)

Rick, Jonathan W; Jahangiri, Arman; Flanigan, Patrick M; Aghi, Manish K

2017-04-01

Acromegaly is a rare disease that is associated with many co-morbidities. This condition also causes progressive deformity of the skull which includes frontal bossing and cranial thickening. Surgical and/or medical management can cure this condition in many patients, but it is not understood if patients cured of acromegaly experience regression of their skull deformities. We performed a retrospective analysis on patients treated at our dedicated pituitary center from 2009 to 2014. We looked at all MRI images taken during the treatment of these patients and recorded measurements on eight skull dimensions. We then analyzed these measurements for changes over time. 29 patients underwent curative treatment for acromegaly within our timeframe. The mean age for this population was 45.0 years old (range 19-70) and 55.2 % (n = 16) were female. All of these patients were treated with a transsphenoidal resection for a somatotropic pituitary adenoma. 9 (31.1%) of these patients required further medical therapy to be cured. We found statically significant variation in the coronal width of the sella turcica after therapy, which is likely attributable to changes from transsphenoidal surgery. None of the other dimensions had significant variation over time after cure. Patients cured of acromegaly should not expect natural regression of their skull deformities. Our study suggests that both frontal bossing and cranial thickening do not return to normal after cure.

Preparation of carbon quantum dots based high photostability luminescent membranes.

Science.gov (United States)

Zhao, Jinxing; Liu, Cui; Li, Yunchuan; Liang, Jiyuan; Liu, Jiyan; Qian, Tonghui; Ding, Jianjun; Cao, Yuan-Cheng

2017-06-01

Urethane acrylate (UA) was used to prepare carbon quantum dots (C-dots) luminescent membranes and the resultants were examined with FT-IR, mechanical strength, scanning electron microscope (SEM) and quantum yields (QYs). FT-IR results showed the polyurethane acrylate (PUA) prepolymer -C = C-vibration at 1101 cm -1 disappeared but there was strong vibration at1687cm -1 which was contributed from the-C = O groups in cross-linking PUA. Mechanical strength results showed that the different quantity of C-dots loadings and UV-curing time affect the strength. SEM observations on the cross-sections of the membranes are uniform and have no structural defects, which prove that the C-dots are compatible with the water-soluble PUA resin. The C-dot loading was increased from 0 to 1 g, the maximum tensile stress was nearly 2.67 MPa, but the tensile strain was decreased from 23.4% to 15.1% and 7.2% respectively. QYs results showed that the C-dots in the membrane were stable after 120 h continuous irradiation. Therefore, the C-dots photoluminescent film is the promising material for the flexible devices in the future applications. Copyright © 2016 John Wiley & Sons, Ltd.

Isothermal and non-isothermal cure of a tri-functional epoxy resin (TGAP): a stochastic TMDSC study

OpenAIRE

Hutchinson, John M.; Shiravand, Fatemeh; Calventus Solé, Yolanda; Fraga Rivas, Iria

2012-01-01

The isothermal cure of a highly reactive tri-functional epoxy resin, tri-glycidyl para-amino phenol (TGAP), with diamino diphenyl sulphone (DDS), at two different cure temperatures Tc has been studied by both conventional differential scanning calorimetry (DSC) and by a stochastic temperature modulated DSC technique, TOPEM. From a series of isothermal cure experiments for increasing cure times, the glass transition temperature Tg as a function of isothermal cure time is determined by co...

Microporous polyurethane-acrylamide film cured by electron beam irradiation

International Nuclear Information System (INIS)

Ando, Masayuki; Goto, Takakazu; Tsuchiya, Mitsuru; Uryu, Toshiyuki

1988-01-01

The morphology and aggregation structure of electron beam (EB)-cured microporous polyurethane-acrylamide film was investigated. The urethane-acrylamide prepolymer was synthesized by the reaction of poly(butylene adipate)diol, diphenylmethane diisocyanate, and N-(hydroxymethyl)acrylamide. It was found from scanning electron microscopy that the urethane-acrylamide film, which was prepared by using a methyl ethyl ketone and dimethylformamide (3:1 v/v) mixture as casting solvent, had a microporous structure with pore size of several micrometers, and that the morphology was fixed by EB irradiation. The pore volume of the EB-cured microporous film was determined to be about 460 mm 3 g -1 by mercury porosimetry. The micropores were not destroyed even after immersing in solvent, possibly because the cured film had high crystallinity and dense crosslinking. Moreover, it was found by X-ray photelectron spectroscopy that terminal portions of urethane-acrylamide were localized at the film surface. (author)

The use of atmospheric pressure plasma as a curing process for canned ground ham.

Science.gov (United States)

Lee, Juri; Jo, Kyung; Lim, Yubong; Jeon, Hee Joon; Choe, Jun Ho; Jo, Cheorun; Jung, Samooel

2018-02-01

This study investigated the potential use of atmospheric pressure plasma (APP) treatment as a curing process for canned ground ham. APP treatment for 60min while mixing increased the nitrite content in the meat batters from 0.64 to 60.50mgkg -1 while the pH and the total content of aerobic bacteria in the meat batters were unchanged. The canned ground hams cured by the APP treatment for 30min displayed no difference in their physicochemical qualities, such as nitrosyl hemochrome, color, residual nitrite, texture, lipid oxidation, and protein oxidation, compared with those of canned ground hams cured with sodium nitrite or celery powder at 42mgkg -1 of nitrite. The canned ground hams cured by the APP treatment received a higher score in taste and overall acceptability than those cured with sodium nitrite. Canned ground ham can be cured by the APP treatment without nitrite additives. Copyright © 2017 Elsevier Ltd. All rights reserved.

About the cure kinetics in natural rubber/styrene Butadiene rubber blends at 433 K

International Nuclear Information System (INIS)

Mansilla, M.A.; Marzocca, A.J.

2012-01-01

Vulcanized blends of elastomers are employed in several goods mainly to improve physical properties and reduce costs. One of the most used blends of this kind is that composed by natural rubber (NR) and styrene butadiene rubber (SBR). The cure kinetic of these blends depends mainly on the compound formulation and the cure temperature and time. The preparation method of the blends can influence the mechanical properties of the vulcanized compounds. In this work the cure kinetic at 433 K of NR/SBR blends vulcanized with the system sulfur/TBBS (N-t-butyl-2-benzothiazole sulfenamide) is analyzed in samples prepared by mechanical mixing and solution blending. The two methods produce elastomer domains of NR and SBR, which present different microstructure due to the cure level attained during vulcanization. The cure kinetics is studied by means of rheometer tests and the model proposed by Kamal and Sourour. The analysis of the cure rate is presented and is related to the structure obtained during the vulcanization process.

About the cure kinetics in natural rubber/styrene Butadiene rubber blends at 433 K

Energy Technology Data Exchange (ETDEWEB)

Mansilla, M.A., E-mail: mmansilla@df.uba.ar [Laboratorio de Polimeros y Materiales Compuestos, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon 1, C1428EGA Buenos Aires (Argentina); Marzocca, A.J. [Laboratorio de Polimeros y Materiales Compuestos, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon 1, C1428EGA Buenos Aires (Argentina)

2012-08-15

Vulcanized blends of elastomers are employed in several goods mainly to improve physical properties and reduce costs. One of the most used blends of this kind is that composed by natural rubber (NR) and styrene butadiene rubber (SBR). The cure kinetic of these blends depends mainly on the compound formulation and the cure temperature and time. The preparation method of the blends can influence the mechanical properties of the vulcanized compounds. In this work the cure kinetic at 433 K of NR/SBR blends vulcanized with the system sulfur/TBBS (N-t-butyl-2-benzothiazole sulfenamide) is analyzed in samples prepared by mechanical mixing and solution blending. The two methods produce elastomer domains of NR and SBR, which present different microstructure due to the cure level attained during vulcanization. The cure kinetics is studied by means of rheometer tests and the model proposed by Kamal and Sourour. The analysis of the cure rate is presented and is related to the structure obtained during the vulcanization process.

Influence of curing conditions on the sorptivity and weight change characteristics of self-compacting concrete

International Nuclear Information System (INIS)

Caliskan, S.

2006-01-01

This paper reports on a study carried out to investigate the influence of curing conditions on the capillary water absorption and weight change characteristics of self compacting concrete (SCC). Specimens were prepared using three types of concrete (SCC, Portland cement (PC), Fly ash (FA) concretes) and were cured under three different curing conditions (20C water and 20C and 40C air cure) for 28 days. Weight gain (water intake) in water curing and weight loss (water loss) in 20C and 40C air curing were recorded throughout the curing period. Compressive strength, water absorption and capillary water absorption tests were carried out at 28 days. The results indicated that FA concrete gained about 0.5% whilst PC and self-compacting concretes gained about 1.0% of the initial weight. This indicates that due to the slower reaction process more free water remains within FA concrete avoiding further water intake. In the weight loss study, FA concrete lost about 4.0% and 6.0% of the initial weight at 20C and 40C air curing, respectively; whereas SCC and PC concretes (both had almost identical values) lost about 3.2 and 5.2% at 20C and 40C, respectively. The absorption test results indicated that SCC gave the lowest captivity coefficient values followed by PC and FA concretes in all curing conditions. (author)

Economic evaluation of five curing processes for wood coatings

International Nuclear Information System (INIS)

Martinez M, I.

1996-01-01

In this work we study the economic feasibility of five methods for curing coatings over sheet wood products. Each year, Mexico is producing more than 40 millions of square meters of wood panels, but the demand is of the range of 58 millions of square meters of this product. Two millions are expended after they are coated, and 38 millions without coating, they are coated artisanilly when they are used to make pieces of furniture. The technical characteristics and the costs involved in each one of five methods of curing, are described. Investments involved with each method are processed to establish: fixed costs, variable costs, equilibrium point, and others. Initial investment, coasts and revenues are processed to determine the income statement pro-form, the projected statement of change in financial position, the projected working capital, the projected balance sheet, the cash-flow, and some economical and financial indicators for each one of the five curing methods. With this information, the internal rate of return (IRR) is determined, and used to compare the economic worth of each of the five methods. The five methods are profitable, because all they have a IRR greater than the opportunity cost of capital (15%) of projects with similar characteristics. Despite, with each one of the five methods, the capital invested is recoverable, and profits can be obtained; curing by ultraviolet light or by electron beam, let recover the investment in less than two years, require fewer dollars for investment, and have a IRR of 135% and 111% respectively. Besides ultraviolet light or electron beam curing processes, pollute less with volatile solvents, use the energy efficiently, have greater production rate, and the coating obtained have better quality than with the other three methods. (Author)

Cure4Kids for Kids: school-based cancer education outreach.

Science.gov (United States)

Van Kirk Villalobos, Aubrey; Quintana, Yuri; Ribeiro, Raul C

2012-01-01

In 2006, St. Jude Children's Research Hospital created Cure4Kids for Kids, a school-based outreach program. The objectives of this community education program are to teach about cancer and healthy lifestyles and to inspire an interest in science and health-related careers. A multidisciplinary team of St. Jude and outside experts developed and pilot tested age-appropriate educational materials and activities with 4th grade students. Eight schools and more than 800 children have participated in the program since 2006. Teachers and students have demonstrated a very positive response to the program for it being both fun and educational. Cure4Kids for Kids resources have been collected into a teacher's kit and are now freely available online at www.cure4kids.org/kids.

Sensory and physicochemical characteristics of salamis added with vegetable-based curing ingredients

OpenAIRE

Kawski, Vicky Lilge; Bertol, Teresinha Marisa; Santos, Maria José Honorato dos; Sawitzki, Maristela Cortez; Fiorentini, Angela Maria; Coldebella, Arlei; Agnes, Ingrid Beatriz Lermen

2017-01-01

ABSTRACT: The aim of this study was to evaluate the sensory and physicochemical quality of colonial salamis added with vegetable-based curing ingredients as potential enhancers of quality products. Salamis were produced according to three treatments: (A) Control: 0.1% curing salt; (B) rosemary: 0.05% curing salt + 0.5% rosemary extract (RE); and (C) RE+celery: 0.14% Veg 503 + 0.27% Veg 504 (sea salt plus celery, nitrate and nitrite supplies, respectively) + 0.5% of RE. No significant differe...

Non-isothermal cure and exfoliation of tri-functional epoxy-clay nanocomposites

Directory of Open Access Journals (Sweden)

F. Shiravand

2015-08-01

Full Text Available The non-isothermal cure kinetics of polymer silicate layered nanocomposites based on a tri-functional epoxy resin has been investigated by differential scanning calorimetry. From an analysis of the kinetics as a function of the clay content, it can be concluded that the non-isothermal cure reaction can be considered to consist of four different processes: the reaction of epoxy groups with the diamine curing agent; an intra-gallery homopolymerisation reaction which occurs concurrently with the epoxy-amine reaction; and two extra-gallery homopolymerisation reactions, catalysed by the onium ion of the organically modified clay and by the tertiary amines resulting from the epoxy-amine reaction. The final nanostructure displays a similar quality of exfoliation as that observed for the isothermal cure of the same nanocomposite system. This implies that the intra-gallery reaction, which is responsible for the exfoliation, is not significantly inhibited by the extra-gallery epoxy-amine cross-linking reaction.

Viral hepatitis B and C. Cure or treatment?

Directory of Open Access Journals (Sweden)

Dimitrios A. Kountouras

2014-12-01

Full Text Available HBV and HCV infections are among the most important global health problems; both represent also the leading cause of cirrhosis and HCC worldwide. HBV treatment cannot be considered cure but effective viral suppression can be achieved and remains the current principal goal of therapy. Talking about HCV treatment today equals to talking about total cure of the patient, with treatments of very high SVR rates, shorter if not shortest duration, minimal risk for resistance, pangenotypic and practically with no serious adverse events, no fibrosis or previous treatment status limitations, but also with a very high cost.

DSC and curing kinetics study of epoxy grouting diluted with furfural -acetone slurry

Science.gov (United States)

Yin, H.; Sun, D. W.; Li, B.; Liu, Y. T.; Ran, Q. P.; Liu, J. P.

2016-07-01

The use of furfural-acetone slurry as active diluents of Bisphenol-A epoxy resin (DGEBA) groutings has been studied by dynamic and non-isothermal DSC for the first time. Curing kinetics study was investigated by non-isothermal differential scanning calorimetries at different heating rates. Activation enery (Ea) was calculated based on Kissinger and Ozawa Methods, and the results showed that Ea increased from 58.87 to 71.13KJ/mol after the diluents were added. The furfural-acetone epoxy matrix could cure completely at the theoretical curing temperature of 365.8K and the curing time of 139mins, which were determined by the kinetic model parameters.

An Enhanced Vacuum Cure Technique for On-Aircraft Repair of Carbon-Bismaleimide Composites

Science.gov (United States)

Rider, Andrew N.; Baker, Alan A.; Wang, Chun H.; Smith, Graeme

2011-06-01

Carbon/bismaleimide (BMI) composite is increasingly employed in critical load carrying aircraft structures designed to operate at temperatures approaching 180°C. The high post-cure temperature (above 220°C) required to fully react the BMI resin, however, renders existing on-aircraft prepreg or wet layup repair methods invalid. This paper presents a new on-aircraft repair technique for carbon/BMI composites. The composite prepregs are first warm-staged to improve the ability to evacuate entrapped air. Then the patch is cured in the scarf cavity using the vacuum bag technique, followed by off-aircraft post-cure. The fully cured patch then can be bonded using a structural adhesive.

Cure Kinetics of Benzoxazine/Cycloaliphatic Epoxy Resin by Differential Scanning Calorimetry

Science.gov (United States)

Gouni, Sreeja Reddy

Understanding the curing kinetics of a thermoset resin has a significant importance in developing and optimizing curing cycles in various industrial manufacturing processes. This can assist in improving the quality of final product and minimizing the manufacturing-associated costs. One approach towards developing such an understanding is to formulate kinetic models that can be used to optimize curing time and temperature to reach a full cure state or to determine time to apply pressure in an autoclave process. Various phenomenological reaction models have been used in the literature to successfully predict the kinetic behavior of a thermoset system. The current research work was designed to investigate the cure kinetics of Bisphenol-A based Benzoxazine (BZ-a) and Cycloaliphatic epoxy resin (CER) system under isothermal and nonisothermal conditions by Differential Scanning Calorimetry (DSC). The cure characteristics of BZ-a/CER copolymer systems with 75/25 wt% and 50/50 wt% have been studied and compared to that of pure benzoxazine under nonisothermal conditions. The DSC thermograms exhibited by these BZ-a/CER copolymer systems showed a single exothermic peak, indicating that the reactions between benzoxazine-benzoxazine monomers and benzoxazine-cycloaliphatic epoxy resin were interactive and occurred simultaneously. The Kissinger method and isoconversional methods including Ozawa-Flynn-Wall and Freidman were employed to obtain the activation energy values and determine the nature of the reaction. The cure behavior and the kinetic parameters were determined by adopting a single step autocatalytic model based on Kamal and Sourour phenomenological reaction model. The model was found to suitably describe the cure kinetics of copolymer system prior to the diffusion-control reaction. Analyzing and understanding the thermoset resin system under isothermal conditions is also important since it is the most common practice in the industry. The BZ-a/CER copolymer system with

7 CFR 30.38 - Class 3; air-cured types and groups.

Science.gov (United States)

2010-01-01

... known as Burley, produced principally in Kentucky, Tennessee, Virginia, North Carolina, Ohio, Indiana, West Virginia, and Missouri. Groups applicable to type 31: X—Flyings. C—Lugs or Cutters. B—Leaf. T—Tips... Green River, Green River Air-cured, or Dark Air-cured of the Henderson and Owensboro Districts, and...

A Call to Develop Course-Based Undergraduate Research Experiences (CUREs) for Nonmajors Courses.

Science.gov (United States)

Ballen, Cissy J; Blum, Jessamina E; Brownell, Sara; Hebert, Sadie; Hewlett, James; Klein, Joanna R; McDonald, Erik A; Monti, Denise L; Nold, Stephen C; Slemmons, Krista E; Soneral, Paula A G; Cotner, Sehoya

2017-01-01

Course-based undergraduate research experiences (CUREs) for non-science majors (nonmajors) are potentially distinct from CUREs for developing scientists in their goals, learning objectives, and assessment strategies. While national calls to improve science, technology, engineering, and mathematics education have led to an increase in research revealing the positive effects of CUREs for science majors, less work has specifically examined whether nonmajors are impacted in the same way. To address this gap in our understanding, a working group focused on nonmajors CUREs was convened to discuss the following questions: 1) What are our laboratory-learning goals for nonmajors? 2) What are our research priorities to determine best practices for nonmajors CUREs? 3) How can we collaborate to define and disseminate best practices for nonmajors in CUREs? We defined three broad student outcomes of prime importance to the nonmajors CURE: improvement of scientific literacy skills, proscience attitudes, and evidence-based decision making. We evaluated the state of knowledge of best practices for nonmajors, and identified research priorities for the future. The report that follows is a summary of the conclusions and future directions from our discussion. © 2017 C. J. Ballen et al. CBE—Life Sciences Education © 2017 The American Society for Cell Biology. This article is distributed by The American Society for Cell Biology under license from the author(s). It is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Cushing's syndrome: aftermath of the cure.

Science.gov (United States)

Pivonello, Rosario; De Martino, Maria Cristina; De Leo, Monica; Tauchmanovà, Libuse; Faggiano, Antongiulio; Lombardi, Gaetano; Colao, Annamaria

2007-11-01

Cushing's syndrome (CS) is a chronic and systemic disease caused by endogenous or exogenous hypercortisolism, associated with an increase of mortality rate due to the clinical consequences of glucocorticoid excess, especially cardiovascular diseases. After cure, usually obtained by the surgical removal of the tumor responsible for the disease, the normalization of cortisol secretion is not constantly followed by the recovery of the clinical complications developed during the active disease, and it is often followed by the development of novel clinical manifestations induced by the fall of cortisol levels. These evidences were mostly documented in patients with pituitary-dependent CS, after surgical resection of the pituitary tumor. Indeed, despite an improvement of the mortality rate, metabolic syndrome and the consequent cardiovascular risk have been found to partially persist after disease remission, strictly correlated to the insulin resistance. Skeletal diseases, mainly osteoporosis, improve after normalization of cortisol levels but require a long period of time or the use of specific treatment, mainly bisphosphonates, to reach the normalization of bone mass. A relevant improvement or resolution of mental disturbances has been described in patients cured from CS, although in several cases, cognitive decline persisted and psychological or psychiatric improvement was erratic, delayed, or incomplete. On the other hand, development or exacerbation of autoimmune disorders, mainly thyroid autoimmune diseases, was documented in predisposed patients with CS after disease remission. The totality of these complications persisting or occurring after successful treatment contribute to the impairment of quality of life registered in patients with CS after disease cure.

Optimization of preparation conditions of polyamide thin film composite membrane for organic solvent nanofiltration

International Nuclear Information System (INIS)

Namvar-Mahboub, Mahdieh; Pakizeh, Majid

2014-01-01

Separation performance of polyamide composite membranes is affected by several parameters during formation of thin upper layer via interfacial polymerization. We investigated the effect of various polyamide synthesis conditions on the performance of organic solvent resistant polyamide composite membranes through the model equations designed by 2-level fractional factorial design. The dewaxing solvent recovery was selected as separation process. Five factors were changed in two level includin; TMC concentration (0.05-0.1%), MPD concentration (1-2%), support immersion time in organic solution (2-4 min), support immersion time in aqueous solution (1-2 min), and curing temperature (70-80 .deg. C). The resultant equations showed 93.48% and 94.82% of the variability (R 2 adj ) in data used to fit oil rejection and permeate flux models, respectively. The analysis of variance revealed that both models were high significant. It was also observed that TMC concentration, MPD concentration and immersion time in TMC have more pronounced effect on the oil rejection and permeate flux than other factors and interactions. Optimal polyamide preparation conditions were obtained using multiple response method for 94% oil rejection as target value. According to the results, the best value of permeate flux (8.86 l/(m 2 ·h)) was found at TMC concentration of 0.1%, MPD concentration of 1.94%, immersion time in TMC of 3.88 min, immersion time in MPD of 1.95 min and curing temperature of 71.96 .deg. C with desirability factor of 1

NONA Cure of Prepreg Structures, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — CRG's no-oven, no-autoclave (NONA) cure of OoA or autoclave prepreg materials allows the manufacture of large composite structures without the expensive and...

Low-temperature technique for thick film resist stabilization and curing

Science.gov (United States)

Minter, Jason P.; Wong, Selmer S.; Marlowe, Trey; Ross, Matthew F.; Narcy, Mark E.; Livesay, William R.

1999-06-01

For a range of thick film photoresist applications, including MeV ion implant processing, thin film head manufacturing, and microelectromechanical systems processing, there is a need for a low-temperature method for resist stabilization and curing. Traditional methods of stabilizing or curing resist films have relied on thermal cycling, which may not be desirable due to device temperature limitations or thermally-induced distortion of the resist features.

Radiation curing of mixtures of diallylphthalate prepolymer and vinyl monomer, 9

International Nuclear Information System (INIS)

Gotoda, Masao; Kitada, Yoshinori.

1975-01-01

Radiation curing, mainly by electron beams was studied with mixtures of low molecular weight diallylphthalate prepolymer (DAPsub(p).L) and vinyl monomers with special reference to their workability. Among the vinyl monomers, acrylonitrile gave a solution of low viscosity and methyl acrylate gave a solution of low dose curing. Radiation curing of DAPsub(p).L/vinyl monomer mixtures impregnated in wood was also tried. To obtain uniform wood-polymer composites, γ-irradiation after impregnation at 10 kg/cm 2 was found to be required for thick plate (110 mm), while electron beam irradiation after impregnation at normal pressure was sufficient for thin plate. (author)

Development of high-performance shielding material by heat curing method

Energy Technology Data Exchange (ETDEWEB)

Miura, Toshimasa; Hirao, Yoshihiro; Hayashi, Takayuki; Okuno, Koichi; Sato, Osamu [National Maritime Research Institute, Ibaraki (Japan)

2002-07-01

A high-performance shielding material is developed by a heat curing method. It is mainly made of a thermosetting resin, lead powder, and a boron compound. To make the resin, a single functional monomer stearyl methacrylate (SMA) is used. To get good dispersion of lead and the boron compound in the resin, the viscosity of the SMA is increased by adding a small amount of a peroxide into the liquid monomer and heating up to the temperature of 100 .deg. C. Next, a peroxide, lead powder, a boron compound, a three functional monomer, and a curing accelerator are mixed into the viscous SMA. The mixture is cured in an atmosphere of nitrogen after removing bubbles using a vacuum pump. Measured properties of the cured material are as follows. The curing rate of SMA is 97 %. The density is kept 2.35 g/cm{sub 3} in the range from room temperature to 150 .deg. C. The weight-change measured by a thermogravimetry is 0.16 % in the range from room temperature to 200 .deg. C. Details of fragments in the gas released from the material is analyzed by a gas chromatography and a mass spectrometry. The hydrogen content of the material is 6.04x10 {sub 22} /cm{sub 3} . The shielding effect is calculated for a fission source by an Sn code ANISN. The shielding effect of the curing material is excellent. For example, concrete shield of a certain thickness can be replaced by the material having a thickness less than a half of concrete. Several samples of the material are irradiated at an irradiation equipment of the research reactor JRR-4 installed at Japan Atomic Energy Research Institute. At the 14{sub th} day after irradiating with the thermal neutron fluence of 6.6x10{sub 15} /cm{sub 2} , the radioactivity is less than one tenth of 75 Bq/g above which materials are regulated as the radioactive substance in Japan.

Cure of Helicobacter pylori-associated ulcer disease through eradication.

Science.gov (United States)

Malfertheiner, P; Leodolter, A; Peitz, U

2000-02-01

The eradication of Helicobacter pylori (H. pylori) infection has led to a dramatic benefit for patients with gastroduodenal ulcer disease, as the majority of these patients receive a lifelong cure. Relapses after successful H. pylori cure may be caused by either recrudescence or reinfection, both rare events nowadays, or be attributed to non-steroidal anti-inflammatory drugs or aspirin intake. In certain geographical areas, H. pylori-negative relapses are proposed as a new, pathophysiological and not yet elucidated entity. The cure of H. pylori infection in uncomplicated duodenal ulcer diseases consists of 7 days of proton pump inhibitor (PPI) based triple therapy, containing two antibiotics from clarithromycin, amoxicillin and metronidazole. In gastric ulcer, it is recommended that the PPI is continued for a further 3 weeks as these ulcers have a prolonged healing time. Rescue therapies after failure need to take into consideration the resistance pattern of the micro-organism and are offered in the form of quadruple therapy or a high-dose PPI with amoxicillin.

Use of 'eradication' in HIV cure-related research: a public health debate.

Science.gov (United States)

Dubé, Karine; Luter, Stuart; Lesnar, Breanne; Newton, Luke; Galea, Jerome; Brown, Brandon; Gianella, Sara

2018-02-13

The landscape of Human Immunodeficiency Virus (HIV) research has changed drastically over the past three decades. With the remarkable success of antiretroviral treatment (ART) in decreasing AIDS-related mortality, some researchers have shifted their HIV research focus from treatment to cure research. The HIV cure research community often uses the term eradication to describe the science, and talks about eradicating the virus from the body. In public discourse, the term eradication could be conflated with disease eradication at the population level. In this paper, we call for a reframing of HIV cure research as control, as it is a more accurate descriptor and achievable goal in the foreseeable future. The properties of HIV are discordant with eradicability standards at both the individual level (as a clinical concept), and at the population level (as a public health concept). At the individual level, true eradication would necessitate absolute elimination of all latent HIV reservoirs from the body. Current HIV cure-related research strategies have proven unsuccessful at accurately quantifying, let alone eliminating these reservoirs. At the population level, eradication implies the permanent global reduction of HIV to zero new cases and to zero risk for future cases. Given the absence of an efficacious HIV vaccine and the impracticality and unethicality of eliminating animal reservoirs, global eradication of HIV is highly implausible. From a public health perspective, HIV eradication remains an elusive goal. The term 'eradication' is a misleading description of current HIV cure-related research. Instead, we call for the use of more realistic expressions such as 'sustained virologic HIV suppression (or control)' or 'management of HIV persistence' to describe HIV cure-related research. Using these terms reorients what HIV cure science can potentially achieve in the near future and avoids creating unrealistic expectations, particularly among the millions of people

Highlights from the HIV Cure and Reservoir Symposium, 11-12 September 2017, Ghent, Belgium.

Science.gov (United States)

Kint, Sam; Van Hecke, Clarissa; Cole, Basiel; Vandekerckhove, Linos; Sips, Magdalena

2018-01-01

For the second time, the HIV Cure Research Center (HCRC) at Ghent University organised the HIV Cure and Reservoir Symposium, in Ghent, Belgium, where in this two-day conference, virologists, molecular biologists, immunologists and clinicians presented the most recent achievements in the field of HIV cure, including data on therapeutic vaccines, HIV remission strategies such as 'shock and kill' or 'block and lock', benefits of early ART and potential of haematopoietic stem cell transplant in achieving cure. Furthermore, methods to characterise and quantify the HIV reservoir were discussed along with HIV reservoir characterisation in different body parts, including the central nervous system. An HIV activist and representative of a patients' agency also presented the patients' perspective on HIV cure. This report is a summary of all topics discussed during this symposium.

Performance of super-absorbent polymer as an internal curing agent for self-compacting concrete

Directory of Open Access Journals (Sweden)

Al-Hubboubi Suhair

2018-01-01

Full Text Available Internal curing agent by using super-absorbent polymer was present in this study, its effect on the properties of self-compacting concrete was evaluated .The SAP content in the concrete mix was 0.5 % by weight of cement. Three procedures for curing were adopted; curing in water, curing in water and air and curing in polyethylene sealed bags. Fresh concrete tests conducted to assess the self-compactability of the produced concrete. Moreover, compressive and splitting strength tests were carried out. The testing program had been extended to the age of 90 days.The use of super-absorbent polymer did not affect the fresh state characteristics of the studied SCC and achieved an increase in both compressive and tensile strengths as compared to the reference concrete mix.

The effect of cure conditions on the stability of cement waste forms after immersion in water

International Nuclear Information System (INIS)

Siskind, B.; Adams, J.W.; Clinton, J.H.; Piciulo, P.L.; McDaniel, K.

1988-01-01

We investigated the effects of curing conditions on the stability of cement-solidified ion-exchange resins after immersion in water. The test specimens consisted of partially depleted mixed-bed bead resins solidified in one of three vendor-supplied Portland I cement formulations, in a reference cement formulation, or in a gypsum-based binder formulation. We cured samples prepared using each formulation in sealed containers for periods of 7, 14, or 28 days as well as in air or with an accelerated heat cure prior to 90-day immersion in water. Two cement formulations exhibited apparent Portland-cement-like behavior, i.e., compressive strength increased or stabilized with increasing cure time. Two cement formulations exhibited behavior apparently unlike that of Portland cement, i.e., compressive strength decreased with increasing cure time. Such non-Portland-cement-like behavior is correlated with higher waste loadings. The gypsum-based formulation exhibited approximately constant compressive strength with cure time. Accelerated heat cures may not give compressive strengths representative of real-time cures. Some physical deterioration (cracking, spalling) of the waste form occurs during immersion

The effect of cure conditions on the stability of cement waste forms after immersion in water

International Nuclear Information System (INIS)

Siskind, B.; Adams, J.W.; Clinton, J.H.; Piciulo, P.L.

1988-01-01

The authors investigated the effects of curing conditions on the stability of cement-solidified ion-exchange resins after immersion in water. The test specimens consisted of partially depleted mixed-bed bead resins solidified in one of three vendor-supplied Portland I cement formulations, in a reference cement formulation, or in a gypsum-based binder formulation. They cured samples prepared using each formulation in sealed containers for periods of 7, 14, or 28 days as well as in air or with an accelerated heat cure prior to 90-day immersion in water. Two cement formulations exhibited apparent Portland-cement-like behavior, i.e., compressive strength increased or stabilized with increasing cure time. Two cement formulations exhibited behavior apparently unlike that of Portland cement, i.e. compressive strength decreased with increasing cure time. Such non-Portland-cement-like behavior is correlated with higher waste loadings. The gypsum-based formulation exhibited approximately constant compressive strength with cure time. Accelerated heat cures may not give compressive strengths representative of real-time cures. Some physical deterioration (cracking, spalling) of the waste form occurs during immersion

Cost analysis of low energy electron accelerator for film curing

International Nuclear Information System (INIS)

Ochi, Masafumi

2003-01-01

Low energy electron accelerators are recognized as one of the advanced curing means of converting processes for films and papers. In the last three years the price of the accelerator equipment has been greatly reduced. The targeted application areas are mainly processes of curing inks, coatings, and adhesives to make packaging materials. The operating cost analyses were made for electron beam (EB) processes over the conventional ones without EB. Then three new proposals for cost reduction of EB processes are introduced. Also being developed are new EB chemistries such as coatings, laminating adhesives and inks. EB processes give instantaneous cure and EB chemistries are basically non solvent causing less VOC emission to the environment. These developments of both equipment and chemistries might have a potential to change conventional packaging film industries. (author)

Preparation of low viscosity epoxy acrylic acid photopolymer prepolymer in light curing system

Science.gov (United States)

Li, P.; Huang, J. Y.; Liu, G. Z.

2018-01-01

With the integration and development of materials engineering, applied mechanics, automatic control and bionics, light cured composite has become one of the most favourite research topics in the field of materials and engineering at home and abroad. In the UV curing system, the prepolymer and the reactive diluent form the backbone of the cured material together. And they account for more than 90% of the total mass. The basic properties of the cured product are mainly determined by the prepolymer. A low viscosity epoxy acrylate photosensitive prepolymer with a viscosity of 6800 mPa • s (25 °C ) was obtained by esterification of 5 hours with bisphenol A epoxy resin with high epoxy value and low viscosity.

Effect of microwave cured acrylic resin on candidal growth in complete denture

International Nuclear Information System (INIS)

Rasmy, A.H.M.

2009-01-01

This study was conducted to evaluate the effect of heat-cured acrylic resin denture base and microwave-cured acrylic resin denture base on candidal growth . Seven completely edentulous male patients with on history of denture wearing participated in this study. all the selected patients were re-habilitated by mucosa supported complete dentures .The dentures were constructed from conventional heat-cured acrylic resin denture base following monoplane concept of occlusion. Before dismissing the patients and one month after denture insertion, salivary samples were collected according to oral rinse technique. one month resting period was allowed so as candidal count can reach to normal, then dentures were re based using microwave-cured acrylic denture base, before denture insertion and one month after denture insertion, salivary sample were collected before and one month following the same oral rinse technique.

Radiation curing of inks and coatings. Annual report 1 Oct 81-30 Sep 82

International Nuclear Information System (INIS)

Senich, G.A.; Florin, R.E.

1983-06-01

The science and technology of curing organic materials with radiation is reviewed. Electron beam, ultraviolet, infrared, microwave, and high frequency radiation sources and the resin systems suitable for use with these sources are considered. Equipment necessary to affect a radiation cure is discussed and some practical problems unique to each radiation method are indicated. The application of radiation curing to industrial processes which employ inks and coatings is covered, with particular emphasis given to printing with radiation curable formulations. Included are discussions of the advantages and disadvantages of radiation curing inks, some typical ink components and formulations, the specialized machinery required, and the influence of parameters unique to radiation curing methods on the printing process. Other nonprinting but related industrial operations utilizing radiation for treating thin films and coatings are also considered. Some costs, examples, and market statistics are given for these commercial procedures. New nonconventional, but also nonradiation, alternative curing methods are discussed briefly. A bibliography of recommended further reading and a list of over two hundred fifty references are included

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

Science.gov (United States)

Bilyeu, Bryan

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

Obtaining membranes for alternative treatment hydrogels of cutaneous leishmaniasis

International Nuclear Information System (INIS)

Oliveira, Maria Jose Alves de

2013-01-01

Polymeric Hydrogels formed by crosslinked polymeric chains were obtained by ionizing radiation process according to Rosiak technique. In the last 40 years the use of hydrogels has been investigated for various applications as curatives. In this work hydrogel membranes were synthesized with poly (N-2-pyrrolidone) (PVP), poly (vinyl alcohol) (PVA), chitosan and laponita clay for use as a vehicle for controlled glucantime release on the surface of skin tissues injured by leishmaniasis. Leishmaniasis is a disease caused by a protozoan parasite of the genus Leishmania transmitted by the bite of phlebotomies sandfly. The traditional treatment of patients infected by these parasites is done with pentavalent antimony in injectable form. However, these antimonates are highly toxic and cause side effects in these patients. In addition, patients with heart and kidney disease can not use this treatment. In treatment with drug delivery hydrogel membrane applied on the surface of leishmaniasis injured tissues the drug is released directly to the wound in a controlled manner, reducing the side effects. Membranes prepared in this study were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG), swelling, gel fraction, infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The characterizations of cytotoxicity and drug release were made 'in vitro' and 'in vivo' with functional test according to ethical protocol of the Division of Infectious and Parasitic Diseases at the Hospital of Clinics, Sao Paulo University-School of Medicine, University. The 'in vivo' test of these membranes proved to be effective in controlled release of drugs directly into leishmaniasis damaged tissues. Results of 'in vivo' tests using PVP/PVAl / clay 1,5% and glucantime membrane showed remarkable contribution to wound reduction and cure in clinical therapy. (author)

Self-curing concrete types; water retention and durability

Directory of Open Access Journals (Sweden)

Magda I. Mousa

2015-09-01

This study was carried out to compare among concretes without or with silica fume (SF along with chemical type of shrinkage reducing admixture, polyethylene-glycol (Ch, and leca as self-curing agents for water retention even at elevated temperature (50 °C and their durability. The cement content of 400 kg/m3, silica fume of 15% by weight of cement, polyethylene-glycol of 2% by weight of cement, pre-saturated lightweight aggregate (leca 15% by volume of sand and water with Ch/binder ratio of 0.4 were selected in this study. Some of the physical and mechanical properties were determined periodically up to 28 days in case of exposure to air curing in temperature of (25 °C and (50 °C while up to 6 months of exposure to 5% of carbon dioxide and wet/dry cycles in 8% of sodium chloride for durability study. The concrete mass loss and the volumetric water absorption were measured, to evaluate the water retention of the investigated concretes. Silica fume concrete either without or with Ch gave the best results under all curing regimes; significant water retention and good durability properties.

Standardized Cloning and Curing of Plasmids

DEFF Research Database (Denmark)

Lauritsen, Ida; Kim, Se Hyeuk; Porse, Andreas

2018-01-01

and exchange of genetic parts in the Standard European Vectors Architecture (SEVA) vector system. Additionally, to facilitate rapid testing and iterative bioengineering using different vector designs, we provide a one-step protocol for a universal CRISPR-Cas9-based plasmid curing system (pFREE) and demonstrate...

Nitrate reductase activity of Staphylococcus carnosus affecting the color formation in cured raw ham.

Science.gov (United States)

Bosse Née Danz, Ramona; Gibis, Monika; Schmidt, Herbert; Weiss, Jochen

2016-07-01

The influence of the nitrate reductase activity of two Staphylococcus carnosus strains used as starter cultures on the formation of nitrate, nitrite and color pigments in cured raw ham was investigated. In this context, microbiological, chemical and multivariate image analyses were carried out on cured raw hams, which were injected with different brines containing either nitrite or nitrate, with or without the S. carnosus starter cultures. During processing and storage, the viable counts of staphylococci remained constant at 6.5logcfu/g in the hams inoculated with starter cultures, while the background microbiota of the hams processed without the starter cultures developed after 14days. Those cured hams inoculated with S. carnosus LTH 7036 (high nitrate reductase activity) showed the highest decrease in nitrate and high nitrite concentrations in the end product, but were still in the range of the legal European level. The hams cured with nitrate and without starter culture or with the other strain, S. carnosus LTH 3838 (low nitrate reductase activity) showed higher residual nitrate levels and a lower nitrite content in the end product. The multivariate image analysis identified spatial and temporal differences in the meat pigment profiles of the differently cured hams. The cured hams inoculated with S. carnosus LTH 3838 showed an uncured core due to a delay in pigment formation. Therefore, the selection of starter cultures based on their nitrate reductase activity is a key point in the formation of curing compounds and color pigments in cured raw ham manufacture. Copyright © 2016 Elsevier Ltd. All rights reserved.

Differences in the curing of [PSI+] prion by various methods of Hsp104 inactivation.

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Yang-Nim Park

Full Text Available [PSI(+] yeast, containing the misfolded amyloid conformation of Sup35 prion, is cured by inactivation of Hsp104. There has been controversy as to whether inactivation of Hsp104 by guanidine treatment or by overexpression of the dominant negative Hsp104 mutant, Hsp104-2KT, cures [PSI(+] by the same mechanism- inhibition of the severing of the prion seeds. Using live cell imaging of Sup35-GFP, overexpression of Hsp104-2KT caused the foci to increase in size, then decrease in number, and finally disappear when the cells were cured, similar to that observed in cells cured by depletion of Hsp104. In contrast, guanidine initially caused an increase in foci size but then the foci disappeared before the cells were cured. By starving the yeast to make the foci visible in cells grown with guanidine, the number of cells with foci was found to correlate exactly with the number of [PSI(+] cells, regardless of the curing method. Therefore, the fluorescent foci are the prion seeds required for maintenance of [PSI(+] and inactivation of Hsp104 cures [PSI(+] by preventing severing of the prion seeds. During curing with guanidine, the reduction in seed size is an Hsp104-dependent effect that cannot be explained by limited severing of the seeds. Instead, in the presence of guanidine, Hsp104 retains an activity that trims or reduces the size of the prion seeds by releasing Sup35 molecules that are unable to form new prion seeds. This Hsp104 activity may also occur in propagating yeast.

Effect of light dispersion of LED curing lights on resin composite polymerization.

Science.gov (United States)

Vandewalle, Kraig S; Roberts, Howard W; Andrus, Jeffrey L; Dunn, William J

2005-01-01

This study evaluated the effect of light dispersion of halogen and LED curing lights on resin composite polymerization. One halogen (Optilux 501, SDS/Kerr, Orange, CA, USA) and five light-emitting diode (LED) curing lights (SmartLite iQ, Dentsply Caulk, Milford, DE, USA; LEDemetron 1, SDS/Kerr; FLASHlite 1001, Discus Dental, Culver City, CA, USA; UltraLume LED 5, Ultradent Products, South Jordan, UT, USA; Allegro, Den-Mat, Santa Maria, CA, USA) were used in this study. Specimens (8 mm diameter by 2 mm thick) were made in polytetrafluoroethylene molds using hybrid (Z100, 3M ESPE, St. Paul, MN, USA) and microfill (A110, 3M ESPE) composite resins. The top surface was polymerized for 5 seconds with the curing light guide tip positioned at a distance of 1 and 5 mm. Degree of conversion (DC) of the composite specimens was analyzed on the bottom surface using micro-Fourier Transform Infrared (FTIR) spectroscopy (Perkin-Elmer FTIR Spectrometer, Wellesley, PA, USA) 10 minutes after light activation. DC at the bottom of the 2 mm specimen was expressed as a percentage of the mean maximum DC. Five specimens were created per curing light and composite type (n=5). Percent mean DC ratios and SDs were calculated for each light under each testing condition. Data were analyzed by analysis of variance (ANOVA)/Tukey's test (alpha = .05). A beam analyzer (LBA-700, Spiricon, Logan, UT, USA) was used to record the emitted light from the curing lights at 0 and 5 mm distances (n=5). A Top Hat factor was used to compare the quality of the emitted beam profile (LBA/PC, Spiricon). The divergence angle from vertical was also determined in the x- and y-axes (LBA/PC). Mean values and SDs were calculated for each light under each testing condition (0 and 5 mm, x- and y-axes) and analyzed by a two-way ANOVA/Tukey's test (alpha = .05). For DC ratios, significant differences were found based on curing light and curing distance (p < .05). At 1 mm, Optilux 501 and FLASHlite 1001 produced significantly

Isothermal and non-isothermal cure of a tri-functional epoxy resin (TGAP): A stochastic TMDSC study

International Nuclear Information System (INIS)

Hutchinson, John M.; Shiravand, Fatemeh; Calventus, Yolanda; Fraga, Iria

2012-01-01

Highlights: ► First evaluation of T g of tri-functional epoxy resin TGAP by DSC. ► Clearly shows advantages of TOPEM for isothermal and non-isothermal cure analysis. ► Evidence of highly non-linear enthalpy relaxation in partially cured TGAP system. - Abstract: The isothermal cure of a highly reactive tri-functional epoxy resin, tri-glycidyl para-amino phenol (TGAP), with diamino diphenyl sulphone (DDS), at two different cure temperatures T c has been studied by both conventional differential scanning calorimetry (DSC) and by a stochastic temperature modulated DSC technique, TOPEM. From a series of isothermal cure experiments for increasing cure times, the glass transition temperature T g as a function of isothermal cure time is determined by conventional DSC from a second (non-isothermal) scan, and the vitrification time t v is obtained as the time at which T g = T c . In parallel, TOPEM experiments at the same T c lead directly to the determination of t v from the sigmoidal change in the quasi-static heat capacity. It is not possible to identify the glass transition temperature of the fully cured system, T g∞ , in a third scan by conventional DSC. In contrast, with TOPEM a second (non-isothermal) scan at 2 K/min after the isothermal cure gives rise to three separate transitions: devitrification of the partially cured and vitrified material; almost immediate vitrification as the T g of the system again rises; finally another devitrification, at a temperature approximating closely to T g∞ . Thus with TOPEM it is possible to obtain a calorimetric measure of the glass transition temperature of this fully cured system.

Out-of-Autoclave Cure Composites

Science.gov (United States)

Hayes, Brian S.

2015-01-01

As the size of aerospace composite parts exceeds that of even the largest autoclaves, the development of new out-of-autoclave processes and materials is necessary to ensure quality and performance. Many out-of-autoclave prepreg systems can produce high-quality composites initially; however, due to long layup times, the resin advancement commonly causes high void content and variations in fiber volume. Applied Poleramic, Inc. (API), developed an aerospace-grade benzoxazine matrix composite prepreg material that offers more than a year out-time at ambient conditions and provides exceptionally low void content when out-of-autoclave cured. When compared with aerospace epoxy prepreg systems, API's innovation offers significant improvements in terms of out-time at ambient temperature and the corresponding tack retention. The carbon fiber composites developed with the optimized matrix technology have significantly better mechanical performance in terms of hot-wet retention and compression when compared with aerospace epoxy matrices. These composites also offer an excellent overall balance of properties. This matrix system imparts very low cure shrinkage, low coefficient of thermal expansion, and low density when compared with most aerospace epoxy prepreg materials.

Handling and Curing Characteristics of Cut-Strip Tobacco. Part 2: Effect of Yellowing Time and Drying Potential

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Johnson WH

2014-12-01

Full Text Available This paper presents Part 2 of a study on comparative handling and curing characteristics of cut-strip vs. whole leaf tobacco. Part 1 considered the effect of leaf size (cut-strip size vs. whole leaf, packing density and mode of leaf orientation on cured leaf chemistry and leaf quality; whereas, the present study considers further the effect of leaf form, two yellowing times and two drying potentials during yellowing. Results showed that leaf chemistry and quality were quite similar for cut-strip (15.2 × 22.9 cm and whole leaf. Insignificant differences were noted for cured leaf starch and sugars, although slightly lower levels of alkaloids (significant at the 0.01 level were observed for cut strip. Curing treatments significantly affected leaf chemistry. Increased yellowing time resulted in lower levels of starch and higher levels of sugar. Sugars were also higher for tobacco yellowed under the higher drying potential. The two forms of leaf responded similarly to different curing schedules (i.e. no interaction of leaf form with schedule. Also, government grade and price data were essentially unaffected by leaf form or curing schedule over the range of variables tested. Cured leaf starch was abnormally high on the average for both leaf forms. Interestingly, starch levels were lower when intact tobacco was bulk-cured in racks rather than box cured (6.35% vs. 9.02%. Since curing schedules were similar, air velocity in the two curing methods might be a factor. Also the cured leaf starch content was about 56% lower for tobacco produced at the Oxford Tobacco Research Station (in a secondary study than at the Central Crops Research Station. It is postulated that carbohydrate and nitrogen metabolism during growth and maturation might be affected by excess rainfall events and/or nitrogen availability, with subsequent effects on starch-to-sugar conversion during curing.

Effect of different curing modes on the degree of conversion and the microhardness of different composite restorations

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Reem Ali Ajaj

2015-01-01

Full Text Available Introduction: This study aims to evaluate the effects of different curing units and modes on the degree of conversion (DC and microhardness (MH of two different resin composites [ESTELITE ∑ QUICK (EQ, and Z350 XT (Z3]. Materials and Methods: One hundred (100 discs of each tested material were made and divided into two subgroups (n = 50 according to the discs′ dimensions: 5 mm diameter × 2 mm thickness, and 2 mm diameter × 2 mm thickness. Each subgroup was further subdivided into the following five classes (n = 10: I cured with halogen light curing-unit; II cured with light-emitting diode (LED unit; III cured with argon laser; IV cured with halogen light-curing unit for 5 s, 10 s rest followed by 20 s curing; and V cured with halogen light-curing unit for 10 s, then 10 s rest, followed by 10 s curing. The first subgroup was tested for MH using the Vickers Microhardness tester and the second subgroup was tested for DC using Fourier transform infrared spectroscopy (FTIR. Data were statistically analyzed using two-way analysis of variance (ANOVA and Tukey′s post hoc test P < 0.05. Results: Specimens in class IV showed the highest mean DC and MH, followed by class III, then class II. Class I showed significantly lower mean values for both DC and MH. On the other hand, Z3 showed statistically significantly higher mean DC and MH than EQ. Conclusion: Although the two tested composites did not perform similarly under the test conditions, curing with halogen unit for 5 s, then 10 s rest, followed by 10 s curing improved the DC and the MH of both the tested materials.

Inorganic polymers from alkali activation of metakaolin: Effect of setting and curing on structure

Energy Technology Data Exchange (ETDEWEB)

Lancellotti, Isabella, E-mail: isabella.lancellotti@unimore.it [Deparment of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Via Vignolese 905/A, Modena I-41125 (Italy); Catauro, Michelina [Department of Aerospace and Mechanical Engineering, Second University of Naples, Via Roma 29, Aversa (CE) I-81031 (Italy); Ponzoni, Chiara [Deparment of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Via Vignolese 905/A, Modena I-41125 (Italy); Bollino, Flavia [Department of Aerospace and Mechanical Engineering, Second University of Naples, Via Roma 29, Aversa (CE) I-81031 (Italy); Leonelli, Cristina [Deparment of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Via Vignolese 905/A, Modena I-41125 (Italy)

2013-04-15

Geopolymers, obtained by chemical reaction between aluminosilicate oxides and silicates under highly alkaline conditions, are studied in this paper. The proposed mechanism of geopolymer setting and hardening or curing consists of a dissolution, a transportation or an orientation, as well as a polycondensation step. The aim of this paper is to investigate the influence of the curing time and temperature, the relative humidity and the reagents temperature on the geopolymerization process in order to obtain a resistant matrix usable for inertization of hazardous wastes. The evolution of the process from the precursors dissolution to final geopolymer matrix hardening has been followed by FTIR spectroscopy, X-ray diffractometry, SEM/EDS and leaching tests. The results show the significant influence of both curing temperature in the curing stage and of the mould materials on the matrix stability. The easy-to-run preparation procedure for a chemically stable metakaolin geopolymer individuated can be summarized as reagents setting and curing at room temperature and material mould which permits moisture level around 40%. - Graphical abstract: Chemical stability as a function of curing conditions. Highlights: ► Metakaolin in highly alkaline solutions produced solid materials at room temperature. ► Curing time and temperature, relative humidity, reagents temperature were optimized. ► Leaching tests were used to confirm final hardening. ► FTIR spectroscopy, SEM analysis and X-ray diffractometry were used to interpret matrix stability.

Inorganic polymers from alkali activation of metakaolin: Effect of setting and curing on structure

International Nuclear Information System (INIS)

Lancellotti, Isabella; Catauro, Michelina; Ponzoni, Chiara; Bollino, Flavia; Leonelli, Cristina

2013-01-01

Geopolymers, obtained by chemical reaction between aluminosilicate oxides and silicates under highly alkaline conditions, are studied in this paper. The proposed mechanism of geopolymer setting and hardening or curing consists of a dissolution, a transportation or an orientation, as well as a polycondensation step. The aim of this paper is to investigate the influence of the curing time and temperature, the relative humidity and the reagents temperature on the geopolymerization process in order to obtain a resistant matrix usable for inertization of hazardous wastes. The evolution of the process from the precursors dissolution to final geopolymer matrix hardening has been followed by FTIR spectroscopy, X-ray diffractometry, SEM/EDS and leaching tests. The results show the significant influence of both curing temperature in the curing stage and of the mould materials on the matrix stability. The easy-to-run preparation procedure for a chemically stable metakaolin geopolymer individuated can be summarized as reagents setting and curing at room temperature and material mould which permits moisture level around 40%. - Graphical abstract: Chemical stability as a function of curing conditions. Highlights: ► Metakaolin in highly alkaline solutions produced solid materials at room temperature. ► Curing time and temperature, relative humidity, reagents temperature were optimized. ► Leaching tests were used to confirm final hardening. ► FTIR spectroscopy, SEM analysis and X-ray diffractometry were used to interpret matrix stability

Late-Age Properties of Concrete with Different Binders Cured under 45°C at Early Ages

Directory of Open Access Journals (Sweden)

Hu Jin

2017-01-01

Full Text Available It is commonly accepted that high curing temperature (near 60°C or above results in reduced mechanical properties and durability of concrete compared to normal curing temperature. The internal temperature of concrete structures at early ages is not so high as 60°C in many circumstances. In this paper, concretes were cured at 45°C at early ages and their late-age properties were studied. The concrete cured at 20°C was employed as the reference sample. Four different concretes were used: plain cement concrete, concrete containing fly ash, concrete containing ground granulate blast furnace slag (GGBS, and concrete containing silica fume. The results show that, for each concrete, high-temperature curing after precuring does not have any adverse effect on the nonevaporable water content, compressive strength, permeability to chloride ions, and the connected porosity of concrete at late ages compared with standard curing. Additionally, high-temperature curing improves the late-age properties of concrete containing fly ash and GGBS.

Radiation cured coatings for fiber optics

International Nuclear Information System (INIS)

Ketley, A.D.; Morgan, C.R.

1978-01-01

A continuous protective coating is formed on a fiber optic by coating the fiber optic in a bath of a liquid radiation curable composition at a temperature up to 90 0 C and exposing the coated conductor to ultraviolet or high energy ionizing radiation to cure the coating

X-ray diffractometry of steam cured ordinary Portland and blast-furnace-slag cements

International Nuclear Information System (INIS)

Camarini, G.; Djanikian, J.G.

1994-01-01

This work studies some aspects of the phases produced by hydration of ordinary and blast-furnace-slag cements, at normal conditions and steam cured (60 and 95 0 C), using an X-ray diffraction technique. The blast-furnace-slag cement was a mixture of 50% of ordinary Portland cement and 50% of blast-furnace-slag (separately grinding). After curing the X-ray diffraction reveals that, in relation to ordinary Portland cement, the main phases in blast-furnace-slag cement are hydrated silicates and aluminates, hydro garnet, etringitte and mono sulphate. After steam curing the hydration of blast-furnace-slag cement proceeds. This is a result of the slag activation by the curing temperature. (author). 8 refs., 3 figs., 1 tab

Color Developing Capacity of Plasma-treated Water as a Source of Nitrite for Meat Curing.

Science.gov (United States)

Jung, Samooel; Kim, Hyun Joo; Park, Sanghoo; Yong, Hae In; Choe, Jun Ho; Jeon, Hee-Joon; Choe, Wonho; Jo, Cheorun

2015-01-01

The interaction of plasma with liquid generates nitrogen species including nitrite (NO(-) 2). Therefore, the color developing capacity of plasma-treated water (PTW) as a nitrite source for meat curing was investigated in this study. PTW, which is generated by surface dielectric barrier discharge in air, and the increase of plasma treatment time resulted in increase of nitrite concentration in PTW. The PTW used in this study contains 46 ppm nitrite after plasma treatment for 30 min. To evaluate the effect of PTW on the cured meat color, meat batters were prepared under three different conditions (control, non-cured meat batter; PTW, meat batter cured with PTW; Sodium nitrite, meat batter cured with sodium nitrite). The meat batters were vacuum-packaged and cooked in a water-bath at 80℃ for 30 min. The typical color of cured meat developed in cooked meat batter treated with sodium nitrite or PTW. The lightness (L*) and yellowness (b*) values were similar in all conditions, whereas, the redness (a*) values of cooked meat batter with PTW and sodium nitrite (pnitrite source in the curing process of meat without addition of other nitrite sources.

New-generation curing units and short irradiation time: the degree of conversion of microhybrid composite resin.

Science.gov (United States)

Scotti, Nicolla; Venturello, Alberto; Migliaretti, Giuseppe; Pera, Francesco; Pasqualini, Damiano; Geobaldo, Francesco; Berutti, Elio

2011-09-01

This in vitro study investigated the depth of cure of a microhybrid composite resin when cured with reduced times of exposure to three commercially available curing lights. Different sample thicknesses (1, 2, and 3 mm) were light cured in high intensity polymerization mode (2,400 mW/cm² for 5, 10, 15, and 20 seconds; 1,100 mW/cm² for 10, 20, 30, and 40 seconds; and 1,100 mW/cm² for 10, 20, 30, and 40 seconds, respectively). The degree of conversion (%) at the bottom of each sample was measured by Attenuated Total Reflection Fourier Transform Infrared (ATR F-TIR) analysis after each polymerization step. Data were analyzed by ANOVA for repeated measures, showing the degree of conversion was not influenced by the curing light employed (P = .622) but was significantly influenced by the thickness of composite resin (P conversion vs the shorter irradiation time permitted (T1) were not significant among different lamps but were significant among different thicknesses. The depth of cure of microhybrid composite resin appears not to be influenced by the curing light employed. Increased irradiation time significantly increases the degree of conversion. Thickness strongly influences depth of cure.

Curing of polymer thermosets via click reactions and on demand processes

Science.gov (United States)

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

Studies on curing effect of phosphite monomer by EB radiation in the air

International Nuclear Information System (INIS)

Xiao, B.; Zhou, Y.; Li, S.; Luo, M.; Wang, X.; Zhao, P.

2000-01-01

A new type phosphite active monomer was synthesized. The resisting oxygen inhibition effect of this monomer and the effects of irradiation dose and concentration of phosphite active monomer on curing were studied. At the same time, curing results were analysed, through gel content and IR spectrum. The excellent resisting oxygen inhibition result of this phosphite active monomer was shown by experiments. EB radiation curing in the air was successfully carried out by the phosphite active monomer. (author)

Electron beam curing of EPDM

International Nuclear Information System (INIS)

Vroomen, G.L.M.; Visser, G.W.; Gehring, J.

1991-01-01

Normally EPDM rubbers are vulcanized by systems based on sulphur, resin or peroxide. The common feature of these systems is that they all require activator energy in the form of heat. The (extremely) high temperatures (approximately 180C) have the disadvantage that the final properties of the finished product may be affected in one way or another by a variety of uncontrolled side reactions which may occur. Radiation curing, on the other hand, is a process which differs from those mentioned above in that the final curing is carried out at about 20C under closely controlled conditions (such as radiation dose, penetration depth, etc.), and this form of curing ultimately results in a more well-defined end product. In the rubber industry, this technique is used by large rubber processors (for example, in roof sheeting and cable production). Its widespread use is, however, impeded by the high investment costs. One way of avoiding these high costs is to arrange for the products to be irradiated by contractors. The optimum radiation dose for EPDM is determined by the required pattern of properties. From this study it may be concluded that the network is primarily built up at a radiation dose of up to approximately 100 kGy. The degree to which it is built up depends partly on the coactivator used and the EPDM type used. In choosing the coactivator, allowance has to be made for its solubility in EPDM. The type of oil chosen and any stabilizer additions will affect the crosslinking efficiency. Contrary to studies published earlier, in this study it was found that when EDMA is used as a coactivator, no difference can be detected between a DCPD type (4%) and an ENB type (4%), provided both have an identical molecular weight distribution. Increasing the ENB content has less effect on the final crosslink density than using a type having a broader molecular weight distribution

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

Science.gov (United States)

Keeratitham, Waralee; Somwangthanaroj, Anongnat

2016-03-01

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

The effect of steam curing on chloride penetration in geopolymer concrete

Directory of Open Access Journals (Sweden)

Jaya Ekaputri Januarti

2017-01-01

Full Text Available In this paper, we present the result of our study on the effect of steam curing to chloride ion penetration in geopolymer concrete. Class F fly ash was activated using sodium hydroxide (NaOH and sodium silicate (Na2SiO3. The concrete specimens were then steam-cured at 40°C, 60°C, 80°C and room temperature at 24 hours. The treatment was followed by wet curing for 28 days, and then followed by immersion of all specimens in salt water for the durations of 30, 60, and 90 days. Cylindrical specimens were then prepared for compressive strength, chloride ion penetration, pH, and porosity tests. A 16 mm-steel bar was fixed at the center of the specimen concrete blocks (specimen size: 10cm × 10cm × 15cm. Corrosion probability was determined by conducting Half Cell Potential test. Our result showed that increasing the curing temperature to 80°C induced chloride ion penetration into the concrete’s effective pores, despite improvements in compressive strength. We also found that chloride ingress on the geopolymer concrete increases commensurately with the increase of the curing temperature. The corrosion potential measurement of geopolymer concrete was higher than OPC concrete even if corrosion was not observed in reinforcing. Based on our result, we suggest that the corrosion categorization for geopolymer concretes needs to be adjusted.

Virulence factor genotypes of Helicobacter pylori affect cure rates of eradication therapy.

Science.gov (United States)

Sugimoto, Mitsushige; Yamaoka, Yoshio

2009-01-01

The cure rates of Helicobacter pylori infection by using a combination of a proton pump inhibitor (PPI) and antimicrobial agents are mainly influenced by bacterial susceptibility to antimicrobial agents and the magnitude of acid inhibition during the treatment. Currently used empirical triple therapies do not reliably produce a > or =80% cure rate on an intention-to-treat basis. Therefore, tailored regimens based on relevant microbiological findings and pharmacogenomics are recommended for attaining an acceptable > or =95% cure rate. Recently, virulence factors of H. pylori, such as cagA and vacA, are reported to be major factors determining the cure rates. Individuals infected with strains with cagA-negative and vacA s2 genotypes have significantly increased risk of eradication failure of H. pylori infection. These virulence factors enhance gastric mucosal inflammation and are associated with the development of peptic ulcer and gastric cancer. H. pylori virulence factors induce proinflammatory cytokines, such as interleukin (IL)-1, IL-8, and tumor necrosis factor (TNF)- which influence mucosal inflammation and/or gastric acid secretion. When physicians select an H. pylori eradication regimen with an acceptable cure rate, they might need to consider H. pylori virulence factors, especially cagA and vacA.

Elastic properties, reaction kinetics, and structural relaxation of an epoxy resin polymer during cure

Science.gov (United States)

Heili, Manon; Bielawski, Andrew; Kieffer, John

The cure kinetics of a DGEBA/DETA epoxy is investigated using concurrent Raman and Brillouin light scattering. Raman scattering allows us to monitor the in-situ reaction and quantitatively assess the degree of cure. Brillouin scattering yields the elastic properties of the system, providing a measure of network connectivity. We show that the adiabatic modulus evolves non-uniquely as a function of cure degree, depending on the cure temperature and the molar ratio of the epoxy. Two mechanisms contribute to the increase in the elastic modulus of the material during curing. First, there is the formation of covalent bonds in the network during the curing process. Second, following bond formation, the epoxy undergoes structural relaxation toward an optimally packed network configuration, enhancing non-bonded interactions. We investigate to what extent the non-bonded interaction contribution to structural rigidity in cross-linked polymers is reversible, and to what extent it corresponds to the difference between adiabatic and isothermal moduli obtained from static tensile, i.e. the so-called relaxational modulus. To this end, we simultaneously measure the adiabatic and isothermal elastic moduli as a function of applied strain and deformation rate.

Microbiological quality and sensory evaluation of new cured products obtained from sheep and goat meat

OpenAIRE

Tolentino, Georgina Santos; Estevinho, Leticia M.; Pascoal, Ananias; Rodrigues, Sandra; Teixeira, A.

2017-01-01

The present work aims to study the effect of species and seasoning time on the physicochemical, microbiological and sensory characteristics of cured legs of sheep and goats. Three cure periods were used: two for sheep and one for goat legs. Legs of lamb were cured for 7 and 8 months whereas legs of goat were cured for 8 months only. Samples were evaluated regarding pH, water activity and indicators of food microbial q uality and safety. A trained panel carried out the sensory analysis, with a...

Comparison of temperature rise in the pulp chamber with different light curing units: An in-vitro study.

Science.gov (United States)

Rajesh Ebenezar, A V; Anilkumar, R; Indira, R; Ramachandran, S; Srinivasan, M R

2010-07-01

This in vitro study was designed to measure and compare the temperature rise in the pulp chamber with different light curing units. The study was done in two settings-in-vitro and in-vivo simulation. In in-vitro setting, 3mm and 6mm acrylic spacers with 4mm tip diameter thermocouple was used and six groups were formed according to the light curing source- 3 Quartz-Tungsten-Halogen (QTH) units and 3 Light-Emitting-Diode (LED) units. For the LED units, three modes of curing like pulse-cure mode, fast mode and ramp mode were used. For in-vivo simulation, 12 caries free human third molar tooth with fused root were used. K-type thermocouple with 1 mm tip diameter was used. Occlusal cavity was prepared, etched, rinsed with water and blot dried; bonding agent was applied and incremental curing of composite was done. Thermal emission for each light curing agent was noted. Temperature rise was very minimal in LED light cure units than in QTH light cure units in both the settings. Temperature rise was minimal at 6mm distance when compared to 3 mm distance. Among the various modes, fast mode produces the less temperature rise. Temperature rise in all the light curing units was well within the normal range of pulpal physiology. Temperature rise caused due to light curing units does not result in irreversible pulpal damage.

Leprosy: eradication or cure?

Science.gov (United States)

Kakar, S

1995-01-01

The National Leprosy Eradication Program (NLEP), launched in 1986, has brought medicine for leprosy to more people than ever before, covering 200 of India's 455 districts. Since 1988, the number of leprosy patients discharged as cured each year has been greater than the number of newly detected, thus moving the country closer to its goal of eradicating leprosy from India. A substantial number of the 3 million people with leprosy in India are likely to come under the coverage of the NLEP. The author, however, argues that the fight against leprosy and the NLEP should be considered in their historical context. Leprosy is therefore used to illustrate how the perhaps interchangeable terms eradication and cure are charged with history and custom. Historically, the focus on eradicating leprosy has had terrible consequences for the patient. In England, perceptions about leprosy are relevant to the situation India, for colonial policy on leprosy was largely derivative. In the 1880s, especially, leprosy excited the public imagination. Asylums adopted segregation and confinement during this period for people with leprosy and the colonial government in India supported that approach from 1882. The author concludes that while the NLEP is laudable, the program must not focus upon eradicating leprosy. It should instead focus upon the leprosy patient, who has for so long been denied and discriminated against. The individual must be placed at the center of any program. Some steps in this direction have been taken.

Towards Multidisciplinary HIV-Cure Research: Integrating Social Science with Biomedical Research.

Science.gov (United States)

Grossman, Cynthia I; Ross, Anna Laura; Auerbach, Judith D; Ananworanich, Jintanat; Dubé, Karine; Tucker, Joseph D; Noseda, Veronica; Possas, Cristina; Rausch, Dianne M

2016-01-01

The quest for a cure for HIV remains a timely and key challenge for the HIV research community. Despite significant scientific advances, current HIV therapy regimens do not completely eliminate the negative impact of HIV on the immune system; and the economic impact of treating all people infected with HIV globally, for the duration of their lifetimes, presents significant challenges. This article discusses, from a multidisciplinary approach, critical social, behavioral, ethical, and economic issues permeating the HIV-cure research agenda. As part of a search for an HIV cure, both the perspective of patients/participants and clinical researchers should be taken into account. In addition, continued efforts should be made to involve and educate the broader community. Published by Elsevier Ltd.

CUREs in biochemistry-where we are and where we should go.

Science.gov (United States)

Bell, Jessica K; Eckdahl, Todd T; Hecht, David A; Killion, Patrick J; Latzer, Joachim; Mans, Tamara L; Provost, Joseph J; Rakus, John F; Siebrasse, Erica A; Ellis Bell, J

2017-01-02

Integration of research experience into classroom is an important and vital experience for all undergraduates. These course-based undergraduate research experiences (CUREs) have grown from independent instructor lead projects to large consortium driven experiences. The impact and importance of CUREs on students at all levels in biochemistry was the focus of a National Science Foundation funded think tank. The state of biochemistry CUREs and suggestions for moving biochemistry forward as well as a practical guide (supplementary material) are reported here. © 2016 by The International Union of Biochemistry and Molecular Biology, 45(1):7-12, 2017. © 2016 The Authors Biochemistry and Molecular Biology Education published by Wiley Periodicals, Inc. on behalf of International Union of Biochemistry and Molecular Biology.

Microstructure aspects of radiation-cured networks: Cationically polymerized aromatic epoxy resins

Science.gov (United States)

Kowandy, Christelle; Ranoux, Guillaume; Walo, Marta; Vissouvanadin, Bertrand; Teyssedre, Gilbert; Laurent, Christian; Berquand, Alexandre; Molinari, Michaël; Coqueret, Xavier

2018-02-01

The thermo-mechanical properties and nanostructural features of epoxy aromatic resins cationically cured by UV-visible or electron beam radiation have been studied by FT-NIR spectroscopy, dynamic mechanical analysis (DMA), dielectric spectroscopy (DS), and atomic force microscopy (AFM). The influence of formulation (nature and content of onium salt) and of curing parameters (doses, thermal treatment) on the thermophysical have been investigated. The presence of several relaxation domains observed by DMA and DS analysis confirms the presence of heterogeneities in the cured materials. Network formation is described by the percolation of glassy nanoclusters which are evidenced by AFM analyses. AFM probing by quantitative nanomechanical measurements confirms the gradual build-up of the local Young's modulus in good agreement with the macroscopic value.

Environmental and conservation considerations for electron curing

International Nuclear Information System (INIS)

Nablo, S.V.; Fletcher, P.M.

1992-01-01

This paper reviews the more important features of electron curing pertaining to environmental protection and conservation. The high electrical conversion efficiencies of these devices measured at output power levels to 200 kilowatts are reviewed with attention to energy transport to the product. The comparative energetics of free radical initiated addition chemistry with that of the more conventional condensation polymerized systems are presented. Some details of recent studies of the repulpability and de-inkability of electron cured products are presented with mill scale trials showing successful recycling with up to 75 % EB processed material in the waste. The ability of energetic electrons to effectively replace toxic chemicals such as H 2 O 2 and ethylene oxide in product sterilization will be presented with a discussion of the regulatory aspects of this process for medical device applications. (author)

Effect of dual-cure composite resin as restorative material on marginal adaptation of class 2 restorations.

Science.gov (United States)

Bortolotto, Tissiana; Melian, Karla; Krejci, Ivo

2013-10-01

The present study attempted to find a simple direct adhesive restorative technique for the restoration of Class 2 cavities. A self-etch adhesive system with a dual-cured core buildup composite resin (paste 1 + paste 2) was evaluated in its ability to restore proximo-occlusal cavities with margins located on enamel and dentin. The groups were: A, cavity filling (cf) with paste 1 (light-curing component) by using a layering technique; B, cf by mixing both pastes, bulk insertion, and dual curing; and C, cf by mixing both pastes, bulk insertion, and chemical curing. Two control groups (D, negative, bulk; and E, positive, layering technique) were included by restoring cavities with a classic three-step etch-and-rinse adhesive and a universal restorative composite resin. SEM margin analysis was performed before and after thermomechanical loading in a chewing simulator. Percentages (mean ± SD) of "continuous margins" were improved by applying the material in bulk and letting it self cure (54 ± 6) or dual cure (59 ± 9), and no significant differences were observed between these two groups and the positive control (44 ± 19). The present study showed that the dual-cured composite resin tested has the potential to be used as bulk filling material for Class 2 restorations. When used as filling materials, dual-cure composite resins placed in bulk can provide marginal adaptation similar to light-cured composites applied with a complex stratification technique.

Internal curing with lightweight aggregate produced from biomass-derived waste

International Nuclear Information System (INIS)

Lura, Pietro; Wyrzykowski, Mateusz; Tang, Clarence; Lehmann, Eberhard

2014-01-01

Shrinkage of concrete may lead to cracking and ultimately to a reduction of the service life of concrete structures. Among known methods for shrinkage mitigation, internal curing with porous aggregates was successfully utilized in the last couple of decades for decreasing autogenous and drying shrinkage. In this paper, the internal curing performance of pre-saturated lightweight aggregates produced from biomass-derived waste (bio-LWA) was studied. In the first part of this paper, the microstructure of the bio-LWA is investigated, with special focus on their pore structure and on their water absorption and desorption behavior. The bio-LWA has large porosity and coarse pore structure, which allows them to release the entrained water at early age and counteract self-desiccation and autogenous shrinkage. In the second part, the efficiency of internal curing in mortars incorporating the bio-LWA is examined by neutron tomography, internal relative humidity and autogenous deformation measurements

Internal curing with lightweight aggregate produced from biomass-derived waste

Energy Technology Data Exchange (ETDEWEB)

Lura, Pietro, E-mail: pietro.lura@empa.ch [Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf (Switzerland); Institute for Building Materials (IfB), ETH Zürich (Switzerland); Wyrzykowski, Mateusz [Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf (Switzerland); Department of Building Physics and Building Materials, Lodz University of Technology (Poland); Tang, Clarence [Siam Research and Innovation, SCG Cement–Building Materials, Saraburi (Thailand); Lehmann, Eberhard [Paul Scherrer Institut, 5232 Villigen PSI (Switzerland)

2014-05-01

Shrinkage of concrete may lead to cracking and ultimately to a reduction of the service life of concrete structures. Among known methods for shrinkage mitigation, internal curing with porous aggregates was successfully utilized in the last couple of decades for decreasing autogenous and drying shrinkage. In this paper, the internal curing performance of pre-saturated lightweight aggregates produced from biomass-derived waste (bio-LWA) was studied. In the first part of this paper, the microstructure of the bio-LWA is investigated, with special focus on their pore structure and on their water absorption and desorption behavior. The bio-LWA has large porosity and coarse pore structure, which allows them to release the entrained water at early age and counteract self-desiccation and autogenous shrinkage. In the second part, the efficiency of internal curing in mortars incorporating the bio-LWA is examined by neutron tomography, internal relative humidity and autogenous deformation measurements.

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

Science.gov (United States)

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.

Effect of Particular Breed on the Chemical Composition, Texture, Color, and Sensorial Characteristics of Dry-cured Ham

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Pil Nam Seong

2014-08-01

Full Text Available The present study demonstrates the impact of specific breed on the characteristics of dry-cured ham. Eighty thighs from Korean native pig (KNP, crossbreed (Landrace×Yorkshire♀×Duroc♂ (LYD, Berkshire (Ber, and Duroc (Du pig breeds (n = 10 for each breed were used for processing of dry-cured ham. The thighs were salted with 6% NaCl (w/w and 100 ppm NaNO2, and total processing time was 413 days. The effects of breed on the physicochemical composition, texture, color and sensory characteristics were assessed on the biceps femoris muscle of the hams. The results revealed that the highest weight loss was found in the dry-cured ham of LYD breed and the lowest weight loss was found in Ber dry-cured ham. The KNP dry-cured ham contain higher intramuscular fat level than other breed hams (p<0.05. It was observed that the dry-cured ham made from KNP breed had the lowest water activity value and highest salt content, while the LYD dry-cure ham had higher total volatile basic nitrogen content than the Ber and Du hams (p<0.05. Zinc, iron and total monounsaturated fatty acids levels were higher in KNP ham while polyunsaturated fatty acids levels were higher in Du ham when compared to other breed hams (p<0.05. Additionally, the KNP dry-cured ham possessed higher Commission International de l’Eclairage (CIE a* value, while the Du dry-cured ham had higher L*, CIE b* and hue angle values (p<0.05. Furthermore, breed significantly affected the sensory attributes of dry-cured hams with higher scores for color, aroma and taste found in KNP dry-cured ham as compared to other breed hams (p<0.05. The overall outcome of the study is that the breed has a potential effect on the specific chemical composition, texture, color and sensorial properties of dry-cured hams. These data could be useful for meat processors to select the suitable breeds for economical manufacturing of high quality dry-cured hams.

Radtech Asia'95 radiation curing conference proceedings

International Nuclear Information System (INIS)

1995-01-01

The Radtech Asia'95 Radiation Curing Conference was held in November, 20-24, 1995 in Guilin, China. The subjects include chemistry, application, Measurement and Equipment, and Material modification. Out of 86 titles, some 30 papers are in INIS scope

Is There a Cure for Cushing's Syndrome?

Science.gov (United States)

... Pinterest Email Print Is there a cure for Cushing syndrome? Untreated Cushing syndrome can be life-threatening—fortunately, most people with ... their previous strength. People who no longer have Cushing syndrome might be more likely to develop diabetes, high ...

Effects of the curing pressure on the torsional fatigue characteristics of adhesively bonded joints

International Nuclear Information System (INIS)

Hwang, Hui Yun; Kim, Byung Jung; Lee, Dai Gil

2004-01-01

Adhesive joints have been widely used for fastening thin adherends because they can distribute the load over a larger area than mechanical joints, require no hole, add very little weight to the structure and have superior fatigue resistance. However, the fatigue characteristics of adhesive joints are much affected by applied pressure during curing operation because actual curing temperature is changed by applied pressure and the adhesion characteristics of adhesives are very sensitive to manufacturing conditions. In this study, cure monitoring and torsional fatigue tests of adhesive joints with an epoxy adhesive were performed in order to investigate the effects of the applied pressure during curing operation. From the experiments, it was found that the actual curing temperature increased as the applied pressure increased, which increased residual thermal stress in the adhesive layer. Therefore, the fatigue life decreased as the applied pressure increased because the mean stress during fatigue tests increased due to the residual thermal stress

Investigation of synthesis, thermal properties and curing kinetics of fluorene diamine-based benzoxazine by using two curing kinetic methods

International Nuclear Information System (INIS)

He, Xuan-yu; Wang, Jun; Ramdani, Noureddine; Liu, Wen-bin; Liu, Li-jia; Yang, Lei

2013-01-01

Graphical abstract: - Highlights: • A novel diamine-based benzoxazine monomer containing aryl ether and bulky fluorene groups (BEF-p) is synthesized. • Kinetic parameters can be calculated by Starink-LSR method and direct LSR method. • Cure reaction could be successfully described with the autocatalytic model. • The poly(BEF-p) exhibits high T g and superior thermal stability. • Aryl ether linkages had little influence on the thermal stability. - Abstract: A novel diamine-based benzoxazine monomer containing aryl ether and bulky fluorene groups (BEF-p) was prepared from the reaction of 9,9-bis-[4-(p-aminophenoxy)-phenyl]fluorene with paraformaldehyde and phenol. The chemical structure of monomer was confirmed by Fourier-transform infrared (FTIR) and 1 H and 13 C nuclear magnetic resonance spectroscopy ( 1 H and 13 C NMR). The polymerization behavior of monomer was analyzed by differential scanning calorimetry (DSC) and FTIR. The curing kinetics was studied by non-isothermal DSC, and the kinetic parameters were determined. The autocatalytic model based on two kinetic methods (Starink-LSR method and direct LSR method) showed good agreement with experimental results. The thermal and mechanical properties of poly(BEF-p) were evaluated with DSC, dynamic mechanical thermal analysis (DMTA), and thermogravimetric analysis (TGA). The results showed that the cured polymer exhibited higher glass transition temperature (T g ) and better thermal stability compared with diaminodiphenylmethane-based benzoxazine(P-ddm), and was slightly lower than those of fluorene diamine-phenol-based polybenzoxazine (poly(BF-p))

Effect of Using Porcelanite as Partial Replacement of Fine Aggregate on Roller Compacted Concrete with Different Curing Methods

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Abeer Abdulqader Salih

2016-09-01

Full Text Available Roller-Compacted Concrete is a no-slump concrete, with no reinforcing steel, no forms, no finishing and wet enough to support compaction by vibratory rollers. Due to the effect of curing on properties and durability of concrete, the main purpose of this research is to study the effect of various curing methods (air curing, 7 days water curing, and permanent water curing and porcelanite (local material used as an Internal Curing agent with different replacement percentages of fine aggregate (volumetric replacement on some properties of Roller-Compacted Concrete and to explore the possibility of introducing practical Roller-Compacted Concrete for road pavement with minimum requirement of curing. Specimens were sawed from slabs of (380*380*100 mm for determination of Ultrasonic Pulse Velocity (UPV and Voids volume. Results show that using (5 % porcelanite improved the results of UPV and Voids volume of Roller-Compacted Concrete (with air curing as compared with reference Roller-Compacted Concrete (with permanent water curing by percentages ranging from(3.6 to 28.9% and (-8 to -15.5% respectively.

Structural and mechanical properties of a giomer-based bulk fill restorative in different curing conditions

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Mustafa Sarp Kaya

2018-01-01

Full Text Available ABSTRACT Objective: The main goal of this study was to compare the polymerization degree of bulk-fill giomer resin cured with three different light-curing units (LCUs: a polywave third-generation (Valo; a monowave (DemiUltra: DU; and a second-generation LED (Optima 10: Opt LCUs by using structural and mechanical properties. Material and methods: Giomer samples of 2 and 4 mm cured with three LCUs were employed in vitro analysis. The degree of curing (DC% was determined with Fourier-Transform Infrared Spectroscopy (FTIR. Microstructural features were observed with scanning electron microscopy (SEM. Flexural strength (FS, compression strength (CS, elastic modulus and fracturing strain were determined for mechanical properties. Surface microhardness (SMH values were also measured. Oneway ANOVA, two-way analysis of variance and Tukey multiple comparison tests were used for statistically analyzing the FS and SMH. Results: DC% values were 58.2, 47.6, and 39.7 for the 2 mm samples cured with DU, Opt., and Valo LCUs, respectively. DC% values of the 4 mm samples were 50.4, 44.6, and 38.2 for DU, Opt, and Valo, respectively. SMH values were Valo, Optcured with Opt and DU exhibited higher FS values than Valo. CS values were similar but compressive modulus and fracturing strain (% varied depending on the curing protocol. Conclusions: Based on the results, it can be concluded that curing device and protocol strongly affect crosslinking reactions and thus DC%, SMH, compressive modulus and strain at break values. Consequently, it can be deduced that curing protocol is possibly the most important parameter for microstructure formation of highly-filled composite restoratives because it may bring some structural defects and physical frailties on restorations due to lower degree of polymerization.

Cure and mechanical properties of carboxylated nitrile rubber (XNBR) vulcanized by alkaline earth metal compounds

Science.gov (United States)

Tulyapitak, Tulyapong

Compounds of carboxylated nitrile rubber (XNBR) with alkaline metal oxides and hydroxide were prepared, and their cure and mechanical properties were investigated. Magnesium oxide (MgO) with different specific surface areas (45, 65, and 140 m2/g) was used. Increased specific surface area and concentration of MgO resulted in higher cure rate. Optimum stiffness, tensile strength, and ultimate strain required an equimolar amount of acidity and MgO. The effect of specific surface area on tensile properties was not significant. Crosslink density of XNBR-MgO vulcanizates increased with increased amounts of MgO. ATR-IR spectroscopy showed that neutralization occurs in two steps: (1) During mixing and storage, MgO reacts with carboxyl groups (RCOOH) to give RCOOMgOH. (2) Upon curing, these react bimolecularly to form RCOOMgOOCR and Mg(OH)2. Dynamic mechanical thermal analysis revealed an ionic transition at higher temperature, in addition to the glass transition. The ionic transition shifts to higher temperature with increasing MgO concentration. Like MgO-XNBR systems, cure rates of XNBR-calcium hydroxide (Ca(OH)2) and XNBR-barium oxide (BaO) compounds increased with increased content of curing agents. Curing by these two agents resulted in ionic crosslinks. To ensure optimum tensile properties, equimolar amounts of carboxyl groups and curing agents were required. Dynamic mechanical analysis revealed the ionic transition in these two systems. It shifted to higher temperature with increased amounts of curing agents. In contrast to MgO, Ca(OH)2, and BaO, calcium oxide (CaO) gave results similar to those for thermally cured samples. No ionic transition was observed in XNBR-CaO systems. Tensile strength of XNBR depended on the strength of ionic crosslinks, which was dependent on the size of the alkaline metal ions.

Coil measurement data acquisition and curing press control system for SSC dipole magnet coils

International Nuclear Information System (INIS)

Dickey, C.E.

1989-03-01

A coil matching program, similar in theory to the methods used to match Tevatron coils, is being developed at Fermilab. Modulus of elasticity and absolute coil size will be determined at 18-inch intervals along the coils while in the coil curing press immediately following the curing process. A data acquisition system is under construction to automatically acquire and manage the large quantities of data that result. Data files will be transferred to Fermilab's VAX Cluster for long-term storage and actual coil matching. The data acquisition system will also provide the control algorithm for the curing press hydraulic system. A description of the SSC Curing Press Data Acquisition and Controls System will be reported. 20 figs

Effect of Relining Methods (Cold & Heat Cure On the Accuracy of Posterior

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Nafiseh AsadzadehOghadaee

2013-01-01

Full Text Available Introduction: The posterior palatal area is the most important area for retention of maxillary dentures and must be considered carefully during and after the reline. The purpose of this in vitro study was to compare the posterior palatal seal in relined complete dentures with two different methods.Materials & Methods: An average size of edentulous maxillary acrylic arch without undercuts was selected in this in vitro study. The alginate impression was made of this model ten times and was poured with a type IV gypsum product, and the casts of control groups were prepared. Then 10 definitive bases were created for each cast. For the experimental groups, one relief wax layer with a thickness of 2mm was put in post-dam area for relining processes. Then, 20 alginate impressions were made of this model. On definitive base, clear heat-cured acrylic bases were fabricated. In experimental groups, bases were divided into 2 groups of 10: first group was relined with heat-cured acrylic resin and another one was relined with cold cured acrylic resin. All of the bases were put in distilled water for two weeks and then each of them was placed on the definitive base. One code was considered for each model. The gap in posterior area between acrylic bases and arch was measured in five points (a-b-c-d-e: mid line, two points in hamular notch, and two points between midline and hamular notch by two practicers in two different times (during two weeks with light B×60 microscope. The data were analyzed by Tukey and Kruskal Wallis tests.Results: The results of this study indicated that there was a statistically significant difference in the amount of gap at point A between control (bases without reline and experimental groups (P=0.047. At point D there was no significant difference between experimental groups, but a significant difference was detected between control group and bases relined with cold cure acryl (P<0.05.Conclusion: The results of this laboratory study

Polyurethane acrylate networks including cellulose nanocrystals: a comparison between UV and EB- curing

International Nuclear Information System (INIS)

Furtak-Wrona, K.; Kozik-Ostrówka, P.; Jadwiszczak, K.; Maigret, J.E.; Aguié-Béghin, V.; Coqueret, X.

2018-01-01

A water-based polyurethane (PUR) acrylate water emulsion was selected as a radiation curable matrix for preparing nanocomposites including cellulose nanocrystals (CNC) prepared by controlled hydrolysis of Ramie fibers. Cross-linking polymerization of samples prepared in the form of films or of 1 mm-thick bars was either initiated by exposure to the 395 nm light of a high intensity LED lamp or by treatment with low energy electron beam (EB). The conversion level of acrylate functions in samples submitted to increasing radiation doses was monitored by Fourier Transform Infrared Spectroscopy (FTIR). Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) were used to characterize changes in the glass transition temperature of the PUR-CNC nanocomposites as a function of acrylate conversion and of CNC content. Micromechanical testing indicates the positive effect of 1 wt% CNC on Young's modulus and on the tensile strength at break (σ) of cured nanocomposites. The presence of CNC in the PUR acrylate matrix was shown to double the σ value of the nanocomposite cured to an acrylate conversion level of 85% by treatment with a 25 kGy dose under EB, whereas no increase of σ was observed in UV-cured samples exhibiting the same acrylate conversion level. The occurrence of grafting reactions inducing covalent linkages between the polysaccharide nanofiller and the PUR acrylate matrix during the EB treatment is advanced as an explanation to account for the improvement observed in samples cured under ionizing radiation. - Highlights: • Nanocomposites were prepared from o/w PUR acrylate emulsion and CNC suspension. • Nanocomposite and reference materials were cured to the same conversion by UV or EB. • Introducing 1 wt% CNC in EB-cured composites doubles the tensile strength. • UV-cured nanocomposites did not show significant improvement in tensile strength.

'Every disease has its cure': faith and HIV therapies in Islamic northern Nigeria.

Science.gov (United States)

Tocco, Jack Ume

2010-12-01

Northern Nigeria has one of the highest levels of HIV prevalence among societies that are predominantly Muslim. In the last decade the region has experienced marked expansion of religiously-oriented healing practices following the formal adoption of Islamic sharia law. Since 2005, international funding has also made antiretroviral therapy (ART) more widely available throughout Nigeria. This study uses ethnographic data collected in Kano, northern Nigeria's largest city, to examine Muslims' perspectives on HIV treatment in the context of popular health beliefs and expanding therapeutic options. The research found that passages from classical Islamic texts are regularly cited by both HIV/AIDS practitioners and patients, especially when talking about the supposition that Allah sends a cure to humankind for every disease. Some religious scholar-practitioners (malamai) working in the Islamic traditions of prophetic medicine insist that HIV can be completely cured given sufficient faith in the supernatural power of the Quran; others claim that the natural ingredients prescribed in Islamic texts can cure HIV. Such assertions contradict the mainstream biomedical position that, with the proper therapeutic regimen, infection with HIV can be managed as a chronic illness, although not cured. Thus, these assertions constitute a challenge to the increasing therapeutic hegemony of antiretroviralbased care in Nigeria. Without falsifying the proposition that a divine cure for HIV exists, many Muslim patients on ART, and the predominantly Muslim biomedical staff who treat them, express scepticism about whether the cure has yet to be revealed to humans. These findings suggest that despite recent efforts in Nigeria to assert a unified Islamic perspective on HIV and AIDS, substantive disagreements persist over the causes, treatments and curability of the disease. The healing systems in which practitioners and patients operate influence how they interpret Islamic texts concerning the

Effect of disposable infection control barriers on light output from dental curing lights.

Science.gov (United States)

Scott, Barbara A; Felix, Corey A; Price, Richard B T

2004-02-01

To prevent contamination of the light guide on a dental curing light, barriers such as disposable plastic wrap or covers may be used. This study compared the effect of 3 disposable barriers on the spectral output and power density from a curing light. The hypothesis was that none of the barriers would have a significant clinical effect on the spectral output or the power density from the curing light. Three disposable barriers were tested against a control (no barrier). The spectra and power from the curing light were measured with a spectrometer attached to an integrating sphere. The measurements were repeated on 10 separate occasions in a random sequence for each barrier. Analysis of variance (ANOVA) followed by Fisher's protected least significant difference test showed that the power density was significantly less than control (by 2.4% to 6.1%) when 2 commercially available disposable barriers were used (p 0.05). The effect of each of the barriers on the power output was small and probably clinically insignificant. ANOVA comparisons of mean peak wavelength values indicated that none of the barriers produced a significant shift in the spectral output relative to the control ( p > 0.05). Two of the 3 disposable barriers produced a significant reduction in power density from the curing light. This drop in power was small and would probably not adversely affect the curing of composite resin. None of the barriers acted as light filters.

An exponential chemorheological model for viscosity dependence on degree-of-cure of a polyfurfuryl alcohol resin during the post-gel curing stage

DEFF Research Database (Denmark)

Dominguez, J.C.; Oliet, M.; Alonso, María Virginia

2016-01-01

of modeling the evolution of the complex viscosity using a widely used chemorheological model such as the Arrhenius model for each tested temperature, the change of the complex viscosity as a function of the degree-of-cure was predicted using a new exponential type model. In this model, the logarithm...... of the normalized degree-of-cure is used to predict the behavior of the logarithm of the normalized complex viscosity. The model shows good quality of fitting with the experimental data for 4 and 6 wt % amounts of catalyst. For the 2 wt % amount of catalyst, scattered data leads to a slightly lower quality...

Curing kinetics, mechanism and chemorheological behavior of methanol etherified amino/novolac epoxy systems

Directory of Open Access Journals (Sweden)

S. F. Zhao

2014-02-01

Full Text Available The curing kinetics and mechanism of epoxy novolac resin (DEN and modified epoxy novolac resin (MDEN with methanol etherified amino resin were studied by means of differential scanning calorimetry (DSC, Fourier transforminfrared (FT-IR spectroscopy and chemorheological analysis. Their kinetics parameters and models of the curing were examined utilizing isoconversional methods, Flynn-Wall-Ozawa and Friedman methods. For the DEN mixture, its average activation energy (Ea was 71.05 kJ/mol and the autocatalytic model was established to describe the curing reaction. The MDEN mixture exhibited three dominant curing processes, termed as reaction 1, reaction 2 and reaction 3; and their Ea were 70.05, 106.55 and 101.91 kJ/mol, respectively. Besides, Ea of reaction 1 was similar to that of DEN mixture, while Ea of reactions 2 and 3 corresponded to that of the etherification reaction between hydroxyl and epoxide group. Moreover, these three dominant reactions were nth order in nature. Furthermore, their curing mechanisms were proposed from the results of DSC and FTIR. The chemorheological behavior was also investigated to obtain better plastics products via optimizing the processing schedules.

Hsp104 Overexpression Cures Saccharomyces cerevisiae [PSI+] by Causing Dissolution of the Prion Seeds

Science.gov (United States)

Park, Yang-Nim; Zhao, Xiaohong; Yim, Yang-In; Todor, Horia; Ellerbrock, Robyn; Reidy, Michael; Eisenberg, Evan; Masison, Daniel C.

2014-01-01

The [PSI+] yeast prion is formed when Sup35 misfolds into amyloid aggregates. [PSI+], like other yeast prions, is dependent on the molecular chaperone Hsp104, which severs the prion seeds so that they pass on as the yeast cells divide. Surprisingly, however, overexpression of Hsp104 also cures [PSI+]. Several models have been proposed to explain this effect: inhibition of severing, asymmetric segregation of the seeds between mother and daughter cells, and dissolution of the prion seeds. First, we found that neither the kinetics of curing nor the heterogeneity in the distribution of the green fluorescent protein (GFP)-labeled Sup35 foci in partially cured yeast cells is compatible with Hsp104 overexpression curing [PSI+] by inhibiting severing. Second, we ruled out the asymmetric segregation model by showing that the extent of curing was essentially the same in mother and daughter cells and that the fluorescent foci did not distribute asymmetrically, but rather, there was marked loss of foci in both mother and daughter cells. These results suggest that Hsp104 overexpression cures [PSI+] by dissolution of the prion seeds in a two-step process. First, trimming of the prion seeds by Hsp104 reduces their size, and second, their amyloid core is eliminated, most likely by proteolysis. PMID:24632242

Hsp104 overexpression cures Saccharomyces cerevisiae [PSI+] by causing dissolution of the prion seeds.

Science.gov (United States)

Park, Yang-Nim; Zhao, Xiaohong; Yim, Yang-In; Todor, Horia; Ellerbrock, Robyn; Reidy, Michael; Eisenberg, Evan; Masison, Daniel C; Greene, Lois E

2014-05-01

The [PSI(+)] yeast prion is formed when Sup35 misfolds into amyloid aggregates. [PSI(+)], like other yeast prions, is dependent on the molecular chaperone Hsp104, which severs the prion seeds so that they pass on as the yeast cells divide. Surprisingly, however, overexpression of Hsp104 also cures [PSI(+)]. Several models have been proposed to explain this effect: inhibition of severing, asymmetric segregation of the seeds between mother and daughter cells, and dissolution of the prion seeds. First, we found that neither the kinetics of curing nor the heterogeneity in the distribution of the green fluorescent protein (GFP)-labeled Sup35 foci in partially cured yeast cells is compatible with Hsp104 overexpression curing [PSI(+)] by inhibiting severing. Second, we ruled out the asymmetric segregation model by showing that the extent of curing was essentially the same in mother and daughter cells and that the fluorescent foci did not distribute asymmetrically, but rather, there was marked loss of foci in both mother and daughter cells. These results suggest that Hsp104 overexpression cures [PSI(+)] by dissolution of the prion seeds in a two-step process. First, trimming of the prion seeds by Hsp104 reduces their size, and second, their amyloid core is eliminated, most likely by proteolysis.

Thermographic analysis of the effect of composite type, layering method, and curing light on the temperature rise of photo-cured composites in tooth cavities.

Science.gov (United States)

Kim, Min-Jung; Kim, Ryan Jin-Young; Ferracane, Jack; Lee, In-Bog

2017-10-01

The purpose of this study was to investigate temperature rise in the composite and dentin of a class I cavity in extracted human molars under different restoration conditions, including the use of different composite types, layering methods, and curing lights. Open occlusal cavities were prepared on 28 extracted human molars. A conventional (Filtek Z250) and a bulk-fill (Filtek Bulk Fill Posterior; BFP) composite were used to restore the preparations. BFP was incrementally layered or bulk-filled. Bulk-filled BFP was cured with two different lights, the Elipar S10 and the BeLite. Each layer was illuminated for 20s, while thermograms of the specimens were recorded for 100s using an infrared thermal camera. Temperature changes on the composite and dentin surfaces were obtained at points of interest (POI) pertaining to successive incremental distances of 0.75mm from the top of the cavity to the pulp. The polymerization kinetics of each composite was determined using photo-differential scanning calorimetry. The greatest temperature rise was observed 0.75mm apical from the top of the cavity. All groups showed over 6°C maximum temperature rise (ΔT max ) at the pulpal side of the dentin. Upon curing, Z250 reached ΔT=5°C faster than BFP; however, ΔT max of the two composites were comparable at any POI. Bulk filling showed greater ΔT max than incremental filling at 0.75mm apical from the top and in the middle of the cavity. The Elipar S10 light generated faster temperature changes in the curing composite at all recorded positions throughout the depth of the cavity and greater ΔT max in all POIs compared to BeLite. Real-time thermographic analysis demonstrated that the composite type and layering method did not influence the temperature rise at the pulpal side of dentin during composite restoration of an occlusal preparation in a tooth. The amount and initial rate of temperature increase was most affected by the radiant exposure of the light curing unit. Within the

CURE: Clean use of reactor energy

International Nuclear Information System (INIS)

1990-05-01

This paper presents the results of a joint Westinghouse Hanford Company (Westinghouse Hanford)-Pacific Northwest Laboratory (PNL) study that considered the feasibility of treating radioactive waste before disposal to reduce the inventory of long-lived radionuclides, making the waste more suitable for geologic disposal. The treatment considered here is one in which waste would be chemically separated so that long-lived radionuclides can be treated using specific processes appropriate for the nuclide. The technical feasibility of enhancing repository performance by this type of treatment is considered in this report. A joint Westinghouse Hanford-PNL study group developed a concept called the Clean Use of Reactor Energy (CURE), and evaluated the potential of current technology to reduce the long-lived radionuclide content in waste from the nuclear power industry. The CURE process consists of three components: chemical separation of elements that have significant quantities of long-lived radioisotopes in the waste, exposure in a neutron flux to transmute the radioisotopes to stable nuclides, and packaging of radionuclides that cannot be transmuted easily for storage or geologic disposal. 76 refs., 32 figs., 24 tabs

Electron Beam Curing of Coil Coatings

Energy Technology Data Exchange (ETDEWEB)

Morganstern, K. H. [Radiation Dynamics, Inc., Westbury, NY (United States)

1969-12-15

The application of electron accelerators for the rapid curing of coatings on coil processing of steel and aluminium appears to have many practical and economic advantages. This paper discusses this particular application, but in the general framework of electron beam application by industry. Although industry has investigated radiation application for two decades, there have been few applications to date. The reasons for this are discussed as well as the shift in attitude now taking place, indicating a more ready acceptance of radiation processing by industry. This shift is apparent particularly in the coatings field, where the benefits of radiation processing are quite evident. In order to pinpoint these benefits a specific coatings application - coil coating - has been chosen. A typical conventional coil coating line is discussed and compared to a line employing a radiation source. Specific engineering information on the types of electron accelerators suitable for this application; the relative economics of radiation vs. heat curing; and a number of other peripheral advantages of radiation are discussed. (author)

Improved ozone resistance of styrene-butadiene rubber cured by a combination of sulfur and ionizing radiation

International Nuclear Information System (INIS)

Basfar, A.A.; Silverman, J.

1995-01-01

Fourier Transform (FTIR) studies performed in this work indicate that high ozone resistance of Styrene-Butadiene Rubber (SBR) formulations cured by a combination of sulfur and ionizing radiation is associated with unusually high vinyl concentration. On the other hand, sulfur cured SBR formulations with low vinyl concentration have poor ozone resistance. Curing with peroxides which involves chemistry similar to that of radiation curing, also leads to high vinyl concentration (relative to sulfur curing) and high ozone resistance. Increasing the absorbed dose in sulfur-radiation cured samples decreased the high vinyl content to a point where the ozone resistance declined greatly. Carbon black was shown to reduce the absorption of both the transvinylene and the vinyl unsaturation groups, but not to the same extent in all formulations. Also, the carbon black seems to play a greater role in the absorption of the unsaturation as sulfur increases. (Author)

Improved ozone resistance of styrene-butadiene rubber cured by a combination of sulfur and ionizing radiation

International Nuclear Information System (INIS)

Basfar, A.A.; Silverman, Joseph

1995-01-01

Fourier Transform Infrared (FTIR) studies performed in this work indicate that high ozone resistance of Styrene-Butadiene Rubber (SBR) formulations cured by a combination of sulfur and ionizing radiation is associated with unusually high vinyl concentration. On the other hand, sulfur cured SBR formulations with low vinyl concentration have poor ozone resistance. Curing with peroxides which involves chemistry similar to that of radiation curing, also leads to high vinyl concentration (relative to sulfur curing) and high ozone resistance. Increasing the absorbed dose in sulfur-radiation cured samples decreased the high vinyl content to a point where the ozone resistance declined greatly. Carbon black was shown to reduce the absorption of both the transvinylene and the vinyl unsaturation groups, but not to the same extent in all formulations. Also, the carbon black seems to play a greater role in the absorption of the unsaturation as sulfur increases. (Author)

Exploring consumer satisfaction with dry-cured ham in five European countries

DEFF Research Database (Denmark)

Resano, Helena; Perez-Cueto, Federico J. A.; Sanjuán, Ana

2011-01-01

This papers' objective is to investigate consumer satisfaction with dry-cured ham in five European countries. A logistic regression model has been fitted using data collected through a crosssectional web-based survey carried out in Belgium, Germany, Denmark, Poland and Greece during January 2008 (n......=2437 of which 2156 were dry-cured ham consumers). Satisfaction was evaluated as overall satisfaction, as well as specific satisfaction with healthfulness, price, convenience and taste. The findings show that the main determinant of overall satisfaction is taste satisfaction, hence, producers...... are recommended to focus on matching sensory acceptability of dry-cured ham. No significant between-country differences were found, reflecting the wide availability of this product in all countries. Consumer characteristics influenced their level of satisfaction. Men, older (age >52 years) and frequent consumers...

Highly Conductive Carbon Fiber Reinforced Concrete for Icing Prevention and Curing.

Science.gov (United States)

Galao, Oscar; Bañón, Luis; Baeza, Francisco Javier; Carmona, Jesús; Garcés, Pedro

2016-04-12

This paper aims to study the feasibility of highly conductive carbon fiber reinforced concrete (CFRC) as a self-heating material for ice formation prevention and curing in pavements. Tests were carried out in lab ambient conditions at different fixed voltages and then introduced in a freezer at -15 °C. The specimens inside the freezer were exposed to different fixed voltages when reaching +5 °C for prevention of icing and when reaching the temperature inside the freezer, i.e. , -15 °C, for curing of icing. Results show that this concrete could act as a heating element in pavements with risk of ice formation, consuming a reasonable amount of energy for both anti-icing (prevention) and deicing (curing), which could turn into an environmentally friendly and cost-effective deicing method.

Development of a Fully Automated Guided Wave System for In-Process Cure Monitoring of CFRP Composite Laminates

Science.gov (United States)

Hudson, Tyler B.; Hou, Tan-Hung; Grimsley, Brian W.; Yaun, Fuh-Gwo

2016-01-01

A guided wave-based in-process cure monitoring technique for carbon fiber reinforced polymer (CFRP) composites was investigated at NASA Langley Research Center. A key cure transition point (vitrification) was identified and the degree of cure was monitored using metrics such as amplitude and time of arrival (TOA) of guided waves. Using an automated system preliminarily developed in this work, high-temperature piezoelectric transducers were utilized to interrogate a twenty-four ply unidirectional composite panel fabricated from Hexcel (Registered Trademark) IM7/8552 prepreg during cure. It was shown that the amplitude of the guided wave increased sharply around vitrification and the TOA curve possessed an inverse relationship with degree of cure. The work is a first step in demonstrating the feasibility of transitioning the technique to perform in-process cure monitoring in an autoclave, defect detection during cure, and ultimately a closed-loop process control to maximize composite part quality and consistency.

Development and engineering application of rotating drum acid-curing equipment in uranium mills

International Nuclear Information System (INIS)

Liu Wenhua

2006-01-01

The development and engineering application of rotating drum acid-curing equipment for 'strong acid-curing and ferri-trickle leaching' process are introduced, including the design of main structure, problems appeared in the development and engineering application, and methods solved. (authors)

Enhanced microactuation with magnetic field curing of ...

Indian Academy of Sciences (India)

ples have been enhanced by two times when compared with that of zero field cured samples. The effect of .... Gauge of wire ... electrolitic-300 mesh (84.67 µm) LR, Product No. ... be in the body centered cubic phase with a lattice parameter.

Effect of Fermented Spinach as Sources of Pre-Converted Nitrite on Color Development of Cured Pork Loin

Science.gov (United States)

Hwang, Ko-Eun

2017-01-01

The effect of fermented spinach extracts on color development in cured meats was investigated in this study. The pH values of raw cured meats without addition of fermented spinach extract or nitrite (negative control) were higher (pmeats in treatment groups were decreased with increasing addition levels of fermented spinach extract. The lightness and yellowness values of raw cured meats formulated with fermented spinach extract were higher (pmeats were increased with increasing fermented spinach extract levels, whereas the yellowness values of cooked cured meats were decreased with increasing levels of fermented spinach extract. The lowest volatile basic nitrogen (VBN) and thiobarbituric acid reactive substances (TBARS) values were observed in the positive control group with addition of nitrite. TBARS values of cured meats added with fermented spinach extract were decreased with increasing levels of fermented spinach extract and VBN values of curing meat with 30% fermented spinach extract was lower than the other treatments. Total viable bacterial counts in cured meats added with fermented spinach extract ranged from 0.34-1.01 Log CFU/g. E. coli and coliform bacteria were not observed in any of the cured meats treated with fermented spinach extracts or nitrite. Residual nitrite contents in treatment groups were increased with increasing levels of fermented spinach extract added. These results demonstrated that fermented spinach could be added to meat products to improve own curing characteristics. PMID:28316477

Photoacoustic study of curing time by UV laser radiation of a photoresin with different thickness

Energy Technology Data Exchange (ETDEWEB)

Pincel, P. Vieyra [UPIITA IPN, Avenida Instituto Politécnico Nacional, No. 2580, Col. Barrio la Laguna Ticomán, Delegación Gustavo A. Madero, C.P. 07340 México, D.F. (Mexico); Jiménez-Pérez, J.L., E-mail: jimenezp@fis.cinvestav.mx [UPIITA IPN, Avenida Instituto Politécnico Nacional, No. 2580, Col. Barrio la Laguna Ticomán, Delegación Gustavo A. Madero, C.P. 07340 México, D.F. (Mexico); Cruz-Orea, A. [Departamento de Física, CINVESTAV-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, C.P. 07360 México, D.F. (Mexico); Correa-Pacheco, Z.N. [Instituto Politécnico Nacional-Centro de Desarrollo de Productos Bióticos (CEPROBI). Carr. Yautepec–Jojutla, km 6. San Isidro, C.P. 62730 Yautepec, Morelos (Mexico); Rosas, J. Hernández [UPIITA IPN, Avenida Instituto Politécnico Nacional, No. 2580, Col. Barrio la Laguna Ticomán, Delegación Gustavo A. Madero, C.P. 07340 México, D.F. (Mexico)

2015-04-20

Highlights: • The curing of a resin in the presence of a UV laser radiation was studied. • Open photoacoustic cell technique was used to characterize the curing of the resin. • The curing of the resin as a function of time was studied. • A parabolic behavior of the resin thickness, as a function of time was observed. • UV–vis and FTIR spectroscopy were employed to characterize the resin. - Abstract: This paper deals with the study of the cure of a resin in the presence of a UV laser radiation used as the excitation source, operated at λ = 405 nm, with an output power of 20 mW. The open photoacoustic cell (OPC) technique was used to study the curing of the resins as a function of time. The curing characteristic time values were τ = 10.43, 20.99, 30.18, 45.84, 67.59 and 89.55 s for the resin thicknesses of 1000, 2000, 3000, 4000, 5000 and 6000 μm, respectively. A parabolic behavior of the resin thickness, as a function of the curing characteristic time, was obtained. UV–vis spectroscopy and infrared Fourier transform spectroscopy (FTIR) techniques were employed to characterize the resin in order to study the optical absorption and the chemical bonds, respectively. Our work has applications in the manufacture of 3D printing parts for applications, among others, in medicine.

Photoacoustic study of curing time by UV laser radiation of a photoresin with different thickness

International Nuclear Information System (INIS)

Pincel, P. Vieyra; Jiménez-Pérez, J.L.; Cruz-Orea, A.; Correa-Pacheco, Z.N.; Rosas, J. Hernández

2015-01-01

Highlights: • The curing of a resin in the presence of a UV laser radiation was studied. • Open photoacoustic cell technique was used to characterize the curing of the resin. • The curing of the resin as a function of time was studied. • A parabolic behavior of the resin thickness, as a function of time was observed. • UV–vis and FTIR spectroscopy were employed to characterize the resin. - Abstract: This paper deals with the study of the cure of a resin in the presence of a UV laser radiation used as the excitation source, operated at λ = 405 nm, with an output power of 20 mW. The open photoacoustic cell (OPC) technique was used to study the curing of the resins as a function of time. The curing characteristic time values were τ = 10.43, 20.99, 30.18, 45.84, 67.59 and 89.55 s for the resin thicknesses of 1000, 2000, 3000, 4000, 5000 and 6000 μm, respectively. A parabolic behavior of the resin thickness, as a function of the curing characteristic time, was obtained. UV–vis spectroscopy and infrared Fourier transform spectroscopy (FTIR) techniques were employed to characterize the resin in order to study the optical absorption and the chemical bonds, respectively. Our work has applications in the manufacture of 3D printing parts for applications, among others, in medicine

Effect of water curing duration on strength behaviour of portland composite cement (PCC) mortar

Science.gov (United States)

Caronge, M. A.; Tjaronge, M. W.; Hamada, H.; Irmawaty, R.

2017-11-01

Cement manufacturing of Indonesia has been introduced Portland Composite Cement (PCC) to minimize the rising production cost of cement which contains 80% clinker and 20% mineral admixture. A proper curing is very important when the cement contains mineral admixture materials. This paper reports the results of an experimental study conducted to evaluate the effect of water curing duration on strength behaviour of PCC mortar. Mortar specimens with water to cement ratio of (W/C) 0.5 were casted. Compressive strength, flexural strength and concrete resistance were tested at 7, 28 and 91 days cured water. The results indicated that water curing duration is essential to continue the pozzolanic reaction in mortar which contributes to the development of strength of mortar made with PCC.

Evaluation of parameters associated with UV/EB cured clearcoats degradation used in outdoor environment

International Nuclear Information System (INIS)

Ruiz, Carmen Silvia Bentivoglio

2003-01-01

The materials curable by ultraviolet (UV) or electron beam (EB) radiation such as inks, adhesives and coatings are reactive compounds made up of resin, monomer, photoinitiator and additives which undergo polymerization and crosslinking under irradiation producing thermoset products. This technology has been used in a great variety of industrial applications, replacing the conventional curing process in the development of new products. One of the challenging applications has been to design weatherable radiation cured coating which maintain their desirable physical properties and aesthetic appearance. This research reports information about the behavior of four UV and EB curable clear coatings -with or without light stabilizer additives- under accelerated weathering. Thermogravimetry, differential scanning calorimetry, differential photo calorimetry, infrared and ultraviolet spectroscopy and tensile properties were used to evaluate these formulations. Clear coating 50 mum thick films were cured with UV and EB radiation at different doses. The UV curing process was carried out at room temperature using an UV tunnel, with a medium pressure mercury lamp and a transport belt with variable speed. The ultraviolet radiation doses were in the range of 50 to 1500 mJ cm -2 . The EB curing process was performed under N 2 atmosphere, with doses in the range from 1,6 to 300 kGy using the IPEN-CNEN/SP Dynamitron electron beam accelerator with energy of 1.5 MeV. The cure degree was determined by means of the residual reaction heat of the under cured samples obtained from photo-DSC or DSC measurements. The accelerated aging tests were carried out using a Weather-Ometer chamber with exposition times in the range of 100 to 3000 hours. The experimental data obtained from the photo-aged samples were evaluated and correlated to the formulation composition, type of radiation - UV or EB, radiation dose and residence time in the aging chamber. The results have shown that the EB cured films

Effects of Curing and Humidity on the Storage Stability of Yams (D ...

African Journals Online (AJOL)

An experimental study was made of the hygroscopic characteristics as well as the response of yam (D.SPP) tuber to a curing treatment prior to storage. The results indicate that the yam tuber possesses a sigmoidal isotherm dominated by the local isotherm LI – II. The yam tissue responds favorably to proper curing ...

Preparations and applications in UV curing coatings of epoxy acrylates containing carboxyl

International Nuclear Information System (INIS)

Wu Yu Min

1999-01-01

This paper introduces preparations of epoxy acrylates containing carboxyl through the reactions of epoxy acrylates with butanedioic anhydride, pentanedioic anhydride, cis-butenedioic anhydride, phthalic anhydride, tetrabromophthalic anhydride and -tetrahydrophthalic anhydride. These epoxy acrylates containing carboxyl have been applied to UV-curing coatings and their effects on properties of UV-curing coatings have been studied

A perspective on "cure" for Rett syndrome.

Science.gov (United States)

Clarke, Angus John; Abdala Sheikh, Ana Paula

2018-04-02

The reversal of the Rett syndrome disease process in the Mecp2 mouse model of Guy et al. (2007) has motivated families and researchers to work on this condition. The reversibility in adult mice suggests that there is potentially much to be gained from rational treatments applied to patients of any age. However, it may be difficult to strike the right balance between enthusiasm on the one hand and realism on the other. One effect of this has been a fragmentation of the "Rett syndrome community" with some groups giving priority to work aimed at a cure while fewer resources are devoted to medical or therapy-based interventions to enhance the quality of life of affected patients or provide support for their families.Several possible therapeutic approaches are under development that, it is claimed and hoped, may lead to a "cure" for patients with Rett syndrome. While all have a rationale, there are potential obstacles to each being both safe and effective. Furthermore, any strategy that succeeded in restoring normal levels of MECP2 gene expression throughout the brain carries potential pitfalls, so that it will be of crucial importance to introduce any clinical trials of such therapies with great care.Expectations of families for a radical, rational treatment should not be inflated beyond a cautious optimism. This is particularly because affected patients with us now may not be able to reap the full benefits of a "cure". Thus, interventions aimed at enhancing the quality of life of affected patients should not be forgone and their importance should not be minimised.

Electron beam curing of polymer matrix composites

International Nuclear Information System (INIS)

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

1998-01-01

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

Use of sodium dodecyl sulfate pretreatment and 2-stage curing for improved quality of salted duck eggs.

Science.gov (United States)

Lian, Zixuan; Qiao, Longshan; Zhu, Guanghong; Deng, Yun; Qian, Bingjun; Yue, Jin; Zhao, Yanyun

2014-03-01

The effects of use of sodium dodecyl sulfate (SDS) pretreatment and 2-stage curing on the microbial, physicochemical, and microstructural qualities of salted duck eggs were studied. After pretreatment in 0.5% (w/v) SDS solution at room conditions for 15 min, no discolorations were observed and no microorganisms were detected on the egg shells. In the 2-stage curing process, 25% (w/v) and 30% (w/v) saline solutions were evaluated in the 1st step (Stage I, approximately 18 d), whereas 4% (w/v) saline solution was applied in the 2nd step (Stage II, approximately 15 d). Along with increased curing time, water content decreased and NaCl content increased in the egg yolks from approximately 0.40% to 0.86%, whereas the water content of egg albumen remained at approximately 85% during the 2-stage curing. More importantly, the NaCl content of albumen maintained at approximately 4.0% at Stage II curing. Yolk index as a sign of maturity for salted duck eggs reached 1 at the end of Stage I (18 d) and retained the same value during Stage II curing regardless of the NaCl concentration in the Stage I saline solution. Oil exudation in egg yolks increased as the time of curing increased. As seen from scanning electron microscopy, oil was released from yolk granules. This study indicated that SDS pretreatment is effective to reduce microbial load on the shells of fresh duck eggs and the 2-stage curing can improve physicochemical qualities of the salted duck eggs and shortened curing time to about 7 to 17 d as compared to the traditional 1-step curing method. Spoiled saline solution and uneven distribution of salt are the 2 major problems in producing salted duck eggs. Sodium dodecyl sulfate (SDS) pretreatment and 2-stage curing process have shown effective to solve these problems, respectively. The SDS pretreatment was able to remove microorganisms and soil from the surface of fresh egg shells, thus preventing the spoilage of the saline solution. The 2-stage curing process

The mycobiota of three dry-cured meat products from Slovenia

DEFF Research Database (Denmark)

Sonjak, Silva; Ličen, Mia; Frisvad, Jens Christian

2011-01-01

“milanense” was isolated from 21 items. The other penicillia were rarely isolated. Of the isolated and identified species, those that can produce mycotoxins are: A. versicolor, Penicillium brevicompactum, Penicillium chrysogenum, P. nordicum, and Penicillium polonicum. Their growth on dry-cured meat products......The surface mycobiota of three types of Slovenian dry-cured meat products were isolated from a total of 75 items of product that were sampled periodically during the drying/ripening stage of processing. The predominant filamentous fungal genus isolated was Penicillium. Eurotium spp., Aspergillus...

Penicillium salamii, a new species occurring during seasoning of dry-cured meat

DEFF Research Database (Denmark)

Perrone, Giancarlo; Samson, Robert A.; Frisvad, Jens Christian

2015-01-01

Fungi have an important role in the production of dry-cured meat products, especially during the seasoning period. In general, both industrially and handmade salami are quickly colonized by a composite mycobiota during seasoning, often with a strong predominance of Penicillium species. These spec......Fungi have an important role in the production of dry-cured meat products, especially during the seasoning period. In general, both industrially and handmade salami are quickly colonized by a composite mycobiota during seasoning, often with a strong predominance of Penicillium species...... "Penicillium milanense" isolated in Denmark and Slovenia on cured meats. The taxonomic position of these strains in Penicillium was investigated using calmodulin, β tubulin and ITS sequences, phenotypic characters and extrolite patterns, and resulted in the discovery of a new Penicillium species, described...... here as P. salamii. A literature search showed that this species occurs on (cured) meat products worldwide. In our study, P. salamii predominated the salami and capocollo surface in levels similar to the commonly known starter culture P. nalgiovense, irrespective of the room or age of seasoning...

Research on curing behavior of concrete with anti-frost admixtures at subzero temperature

Science.gov (United States)

Ionov, Yulian; Kramar, Ludmila; Kirsanova, Alena; Kolegova, Irina

2017-01-01

The purpose of this paper is research on curing behavior of cold-weather concrete with anti-frost admixtures. During the study derivative thermal and X-ray phase analyses were performed and tests were carried out according to the standard GOST technique. The research results obtained reveal the peculiarities of cement hydration and concrete curing at subzero temperatures. The influence of subzero temperatures and anti-frost admixtures on hydrated phases of hardened cement paste and concrete strength formation was studied. It is found that cold-weather concrete does not cure at subzero temperatures, but when defrosting it attains 80 to 85% of its grade strength by the 28th day. Concrete achieves its grade strength when curing in normal conditions in 60 days only. Freezing concrete with anti-frost admixtures results in increase of calcium hydroxide content in hardened cement paste immediately when produced and has increased tendency of concrete to carbonation.

7 CFR 319.56-11 - Importation of dried, cured, or processed fruits, vegetables, nuts, and legumes.

Science.gov (United States)

2010-01-01

... QUARANTINE NOTICES Fruits and Vegetables § 319.56-11 Importation of dried, cured, or processed fruits, vegetables, nuts, and legumes. (a) Dried, cured, or processed fruits and vegetables (except frozen fruits and... 7 Agriculture 5 2010-01-01 2010-01-01 false Importation of dried, cured, or processed fruits...

CURING AND MECHANICAL PROPERTIES OF CHLOROSULPHONATED POLYETHYLENE RUBBER BLEND

Directory of Open Access Journals (Sweden)

Jaroslava Budinski-Simendić

2011-09-01

Full Text Available In this paper, the curing and mechanical properties of two series of prepared blends, i.e., chlorosulphonated polyethylene (CSM/isobutylene-co-isoprene (IIR rubber blends and chlorosulphonated polyethylene (CSM/chlorinated isobutylene-co-isoprene (CIIR rubber blends were carried out. Blends were prepared using a two-roll mill at a temperature of 40-50 °C. The curing was assessed using a Monsanto oscillating disc rheometer R-100. The process of vulcanization accelerated sulfur of pure rubbers and their blends was carried out in an electrically heated laboratory hydraulic press under a pressure of about 4 MPa and 160 °C. The stress-strain experiments were performed using a tensile tester machine (Zwick 1425. Results indicate that the scorch time, ts2, and optimum cure time, tc90, increase with increasing CSM content in both blends. The value of modulus at 100 and 300% elongation and tensile strength increases with increasing CSM content, whereas elongation at break shows a decreasing trend. The enhancement in mechanical properties was supported by data of crosslink density in these samples obtained from swelling measurement and scanning electron microscopy studies of the rubber blends fractured surfaces

Effect of cementitious permanent formwork on moisture field of internal-cured concrete under drying

Science.gov (United States)

Wang, Jiahe; Zhang, Jun; Ding, Xiaoping; Zhang, Jiajia

2018-02-01

Drying shrinkage of concrete may still be the main source of cracking in concrete structures, even though the autogenous shrinkage of concrete can be effectively reduced by using internal curing. In the present paper, the effect of internal curing with pre-soaked lightweight aggregate and engineered cementitious composite permanent formwork (ECC-PF) on a moisture distribution in three kinds of concrete in a drying environment are investigated from both aspects of experiments and theoretical modeling. The test results show that the combination use of ECC-PF and internal curing can well maintain the humidity at a relatively high level not only at a place far from drying surface, but also at a place close to the drying surfaces. The developed model can well catch the characteristics of the moisture distribution in concrete under drying and the impacts of internal curing and ECC-PF can well be reflected as well. The model can be used for the design of concrete structures with combination use of internal curing and permanent formwork.

The electron beam cure of epoxy paste adhesives

International Nuclear Information System (INIS)

Farmer, J.D.; Janke, C.J.; Lopata, V.J.

1998-01-01

Recently developed epoxy paste adhesives were electron beam cured and experimentally explored to determine their suitability for use in an aerospace-quality aircraft component. There were two major goals for this program. The first was to determine whether the electron beam-curable past adhesives were capable of meeting the requirements of the US Air Force T-38 supersonic jet trainer composite windshield frame. The T-38 windshield frame's arch is currently manufactured by bonding thin stainless steel plies using an aerospace-grade thermally-cured epoxy film adhesive. The second goal was to develop the lowest cost hand layup and debulk process that could be used to produce laminated steel plies with acceptable properties. The laminate properties examined to determine adhesive suitability include laminate mechanical and physical properties at room, adhesive tack, out-time capability, and the debulk requirements needed to achieve these properties. Eighteen past adhesives and four scrim cloths were experimentally examined using this criteria. One paste adhesive was found to have suitable characteristics in each of these categories and was later chosen for the manufacture of the T-38 windshield frame. This experimental study shows that by using low-cost debulk and layup processes, the electron beam-cured past adhesive mechanical and physical properties meet the specifications of the T-38 composite windshield frame

Use of alternative curing salts for processing salamis

Directory of Open Access Journals (Sweden)

Dong-Gyun Yim

2018-01-01