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Sample records for resin die materials

  1. Comparative evaluation of few physical properties of epoxy resin, resin-modified gypsum and conventional type IV gypsum die materials: an in vitro study.

    Science.gov (United States)

    Gujjarlapudi, Manmohan Choudary; Reddy, S Varalakshmi; Madineni, Praveen Kumar; Ealla, Kranti Kiran Reddy; Nunna, Venkata Narayana; Manne, Sanjay Dutt

    2012-01-01

    To compare and evaluate few physical properties of epoxy resin, resin-modified gypsum and conventional type-IV gypsum die material. In the present study, dimensional accuracy, surface detail reproduction and transverse strength of three die materials like epoxy resin (Diemet-E), resin-modified gypsum (Synarock) and conventional type-IV gypsum (Ultrarock) are analyzed. For dimensional accuracy, master die (Bailey's die) is used and calibrations were made with digital microscope. For surface detail reproduction and transverse strength, rectangular stainless steel master die (Duke's die) was used and calibrations were made with Toolmaker's microscope and Instron universal testing machine respectively. One-way analysis of variance (ANOVA) was performed on the means and standard deviation for groups of each test. The results of the study showed statistically significant difference among these materials in dimensional accuracy, surface detail reproduction and transverse strength. Epoxy resin exhibited superiority in dimensional accuracy, surface detail reproduction and transverse strength and is nearest to the standards of accurate die material.

  2. Materials on dies for pressure die casting

    Directory of Open Access Journals (Sweden)

    E. Ragan

    2012-01-01

    Full Text Available In the contribution the stress of die materials of thermal fatigue is defi ned and material life is derived theoretically and compared with the measured values. The important properties of the die materials as thermal conductivity, coeffi cient of thermal expansivity, modulus of elasticity and mechanical properties are described. Binding to it single die materials as carbon steels and chrome-tungsten steels are analyzed. As the perspective die material for pressure die casting of ferrous metals appears molybdenum with regard to advantageous properties.

  3. Enhancement of adhesion between resin coating materials and resin cements.

    Science.gov (United States)

    Udo, Tomoaki; Nikaido, Toru; Ikeda, Masaomi; Weerasinghe, Dinesh S; Harada, Naoko; Foxton, Richard M; Tagami, Junji

    2007-07-01

    Resin coating technique is a unique method that improves the dentin bond strength of resin cements in indirect restorations. However, the weak link of a specimen bonded using the resin coating technique was reported to be the bonded interface between the resin coating material and resin cement. The purpose of this study, therefore, was to enhance the bonding performance between a resin coating material and a resin cement. Two light-cured flowable composites, Protect Liner F and Clearfil Flow FX, were used as coating materials, and two dual-cure composite materials, Panavia F 2.0 and Clearfil DC Core Automix, were used as resin cements. The ultimate tensile strength of each material and the microtensile bond strengths of the bonded specimens of resin coating material and resin cement were measured using a crosshead speed of 1.0 mm/min. Three-way ANOVA (p=0.05) revealed that the highest microtensile bond strength was obtained using a combination of Clearfil Flow FX and Clearfil DC Core Automix, and when the surface of the coating material was treated with ED Primer II. It was strongly suggested that materials with a higher ultimate tensile strength, when used in both resin coating and cementation, could enhance the bond strength between the two.

  4. Comparison of the Effect of Addition of Cyanoacrylate, Epoxy Resin, and Gum Arabic on Surface Hardness of Die Stone.

    Science.gov (United States)

    Tripathi, Arvind; Gupta, Ashutosh; Bagchi, Soumyojeet; Mishra, Lallan; Gautam, Abhina; Madhok, Riti

    2016-04-01

    To observe the effects of incorporating cyanoacrylate, epoxy resins, and gum arabic on the abrasion resistance of type IV gypsum die materials. Forty specimens were prepared and divided into four groups (10 specimens in each group), namely group A (control), group B (die stone mixed with cyanoacrylate), group C (die stone mixed with epoxy resin), group D (die stone mixed with gum arabic). All the specimens were subjected to abrasion testing, wear volume analysis, Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscope (SEM) analysis. Abrasion testing showed maximum wear in the control group and minimum wear in the gum arabic group. Intergroup differences were statistically significant (p Epoxy resins are powerful adhesives, but they attain their full efficiency when cured with heat. Cyanoacrylate and epoxy resin displayed poor physical bonding, primarily because of inhomogeneity. © 2015 by the American College of Prosthodontists.

  5. Geopolymer resin materials, geopolymer materials, and materials produced thereby

    Science.gov (United States)

    Seo, Dong-Kyun; Medpelli, Dinesh; Ladd, Danielle; Mesgar, Milad

    2016-03-29

    A product formed from a first material including a geopolymer resin material, a geopolymer resin, or a combination thereof by contacting the first material with a fluid and removing at least some of the fluid to yield a product. The first material may be formed by heating and/or aging an initial geopolymer resin material to yield the first material before contacting the first material with the fluid. In some cases, contacting the first material with the fluid breaks up or disintegrates the first material (e.g., in response to contact with the fluid and in the absence of external mechanical stress), thereby forming particles having an external dimension in a range between 1 nm and 2 cm.

  6. Geopolymer resin materials, geopolymer materials, and materials produced thereby

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Dong-Kyun; Medpelli, Dinesh; Ladd, Danielle; Mesgar, Milad

    2018-01-09

    A product formed from a first material including a geopolymer resin material, a geopolymer material, or a combination thereof by contacting the first material with a fluid and removing at least some of the fluid to yield a product. The first material may be formed by heating and/or aging an initial geopolymer resin material to yield the first material before contacting the first material with the fluid. In some cases, contacting the first material with the fluid breaks up or disintegrates the first material (e.g., in response to contact with the fluid and in the absence of external mechanical stress), thereby forming particles having an external dimension in a range between 1 nm and 2 cm.

  7. Physical Properties of Synthetic Resin Materials

    Science.gov (United States)

    Fishbein, Meyer

    1939-01-01

    A study was made to determine the physical properties of synthetic resins having paper, canvas, and linen reinforcements, and of laminated wood impregnated with a resin varnish. The results show that commercial resins have moduli of elasticity that are too low for structural considerations. Nevertheless, there do exist plastics that have favorable mechanical properties and, with further development, it should be possible to produce resin products that compare favorably with the light-metal alloys. The results obtained from tests on Compound 1840, resin-impregnated wood, show that this material can stand on its own merit by virtue of a compressive strength four times that of the natural wood. This increase in compressive strength was accomplished with an increase of density to a value slightly below three times the normal value and corrected one of the most serious defects of the natural product.

  8. Homogenity of Die Casting and Returning Material

    Directory of Open Access Journals (Sweden)

    J. Malik

    2012-04-01

    Full Text Available Homogeneity of die castings is influenced by wide range of technological parameters as piston velocity in filling chamber of die casting machine, filling time of mould cavity, temperature of cast alloy, temperature of the mould, temperature of filling chamber, surface pressure on alloy during mould filling, final pressure and others. Based on stated parameters it is clear, that main parameters of die casting are filling time of die mould cavity and velocity of the melt in the ingates. Filling time must ensure the complete filling of the mould cavity before solidification process can negatively influence it. Among technological parameters also belong the returning material, which ratio in charge must be constrained according to requirement on final homogeneity of die castings. With the ratio of returning material influenced are the mechanical properties of castings, inner homogeneity and chemical composition.

  9. The strengthening of resin cemented dental ceramic materials

    OpenAIRE

    Hooi, Paul

    2013-01-01

    The aim of the current investigation was to advance the understanding of the mechanism of resin-strengthening conferred to dental ceramic materials by resin-based composite materials. The investigation is presented as a series of manuscripts. In the first study (Manuscript 3.1), dental porcelain disc-shaped specimens were resin-coated with three resin-based composite materials with different flexural moduli at discrete resin thicknesses. The discs were loaded to failure in a biaxial flexure t...

  10. 21 CFR 872.3690 - Tooth shade resin material.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Tooth shade resin material. 872.3690 Section 872...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3690 Tooth shade resin material. (a) Identification. Tooth shade resin material is a device composed of materials such as bisphenol-A glycidyl...

  11. 21 CFR 872.3670 - Resin impression tray material.

    Science.gov (United States)

    2010-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3670 Resin impression tray material. (a) Identification. Resin impression tray material is a device intended for use in a two-step dental mold fabricating... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Resin impression tray material. 872.3670 Section...

  12. 21 CFR 872.3310 - Coating material for resin fillings.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Coating material for resin fillings. 872.3310... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3310 Coating material for resin fillings. (a) Identification. A coating material for resin fillings is a device intended to be applied to the...

  13. The interaction between lining materials and composite resin restorative materials.

    Science.gov (United States)

    Lingard, G L; Davies, E H; Von Fraunhofer, J A

    1981-03-01

    The effects of four lining materials, Dycal, Procal, Cavitec and Poly F cement on Adaptic and Concise have been investigated in vitro. The parameters studied were surface roughness, hardness and colour both with and without an intermediate (or bonding) resin being present between the restorative material and the liner. The effects of the four liners on the composites varied both between the lining materials themselves and with the composite resin. Two materials, Procal and Dycal, had little interaction with the composites, provided an intermediate resin was used with the latter. Cavitec appeared to have an adverse reaction with the composites and Poly F, whilst having no effect on the colour of the composites, did increase surface roughness. The adverse effects of linig materials were ascribed to minor constituents, particularly methyl salicylate, present in the formulation.

  14. FDI report on adverse reactions to resin-based materials.

    Science.gov (United States)

    Fan, P L; Meyer, D M

    2007-02-01

    Resin-based restorative materials are considered safe for the vast majority of dental patients. Although constituent chemicals such as monomers, accelerators and initiators can potentially leach out of cured resin-based materials after placement, adverse reactions to these chemicals are rare and reaction symptoms commonly subside after removal of the materials. Dentists should be aware of the rare possibility that patients could have adverse reactions to constituents of resin-based materials and be vigilant in observing any adverse reactions after restoration placement. Dentists should also be cognisant of patient complaints about adverse reactions that may result from components of resin-based materials. To minimise monomer leaching and any potential risk of dermatological reactions, resin-based materials should be adequately cured. Dental health care workers should avoid direct skin contact with uncured resin-based materials. Latex and vinyl gloves do not provide adequate barrier protection to the monomers in resin-based materials.

  15. Dental repair material: a resin-modified glass-ionomer bioactive ionic resin-based composite.

    Science.gov (United States)

    Croll, Theodore P; Berg, Joel H; Donly, Kevin J

    2015-01-01

    This report documents treatment and repair of three carious teeth that were restored with a new dental repair material that features the characteristics of both resin-modified glass-ionomer restorative cement (RMGI) and resin-based composite (RBC). The restorative products presented are reported by the manufacturer to be the first bioactive dental materials with an ionic resin matrix, a shock-absorbing resin component, and bioactive fillers that mimic the physical and chemical properties of natural teeth. The restorative material and base/liner, which feature three hardening mechanisms, could prove to be a notable advancement in the adhesive dentistry restorative materials continuum.

  16. Method of treating tool steel die materials

    International Nuclear Information System (INIS)

    Cook, C.S.; Damon, S.

    1981-01-01

    In a method of hardening pilger dies to provide a hard case containing residual compressive stresses and tough body, the tool steel die is heated to the austenitizing temperature range, followed by selectively removing heat from the die at a predetermined faster rate in the direction of the desired case than the rate of heat removal from the balance of the die, and thereafter tempering the die. The invention provides a fully hardened and tempered case on the working surface of the die and a tough body in the balance of the die, usually of lower hardness. (author)

  17. A comparative evaluation of the marginal adaptation of a thermoplastic resin, a light cured wax and an inlay casting wax on stone dies: Anin vitrostudy.

    Science.gov (United States)

    Gopalan, Reji P; Nair, Vivek V; Harshakumar, K; Ravichandran, R; Lylajam, S; Viswambaran, Prasanth

    2018-01-01

    Different pattern materials do not produce copings with satisfactory, marginal accuracy when used on stone dies at varying time intervals. The purpose of this study was to evaluate and compare the vertical marginal accuracy of patterns formed from three materials, namely, thermoplastic resin, light cured wax and inlay casting wax at three-time intervals of 1, 12, and 24 h. A master die (zirconia abutment mimicking a prepared permanent maxillary central incisor) and metal sleeve (direct metal laser sintering crown #11) were fabricated. A total of 30 stone dies were obtained from the master die. Ten patterns were made each from the three materials and stored off the die at room temperature. The vertical marginal gaps were measured using digital microscope at 1, 12, and 24 h after reseating with gentle finger pressure. The results revealed a significant statistical difference in the marginal adaptation of three materials at all the three-time intervals. Light cured wax was found to be most accurate at all time intervals, followed by thermoplastic resin and inlay casting wax. Furthermore, there was a significant difference between all pairs of materials. The change in vertical marginal gap from 1 to 24 h between thermoplastic resin and light cured wax was not statistically significant. The marginal adaptation of all the three materials used, was well within the acceptable range of 25-70 μm. The resin pattern materials studied revealed significantly less dimensional change than inlay casting wax on storage at 1, 12, and 24 h time intervals. They may be employed in situations where high precision and delayed investing is expected.

  18. Radiopacity Of Glass-ionomer/composite Resin Hybrid Materials.

    OpenAIRE

    Hara A.T.; Serra M.C.; Rodrigues Junior A.L.

    2001-01-01

    This study visually compared the radiopacity of seven restorative materials (3 resin-modified glass-ionomer cements, 3 polyacid-modified composite resins, and 1 conventional glass-ionomer cement) to a sound tooth structure sample, and an aluminium stepwedge. All hybrid materials were more radiopaque, except for one resin-modified glass-ionomer cement, than both the tooth structure and conventional glass-ionomer cement.

  19. Die Materials for Critical Applications and Increased Production Rates

    Energy Technology Data Exchange (ETDEWEB)

    David Schwam; John Wallace; Sebastian Birceanu

    2002-11-30

    Die materials for aluminum die-casting need to be resistant to heat checking, and have good resistance to washout and to soldering in a fast flow of molten aluminum. To resist heat checking, die materials should have a low coefficient of thermal expansion, high thermal conductivity, high hot yield strength, good temper softening resistance, high creep strength, and adequate ductility. To resist the washout and soldering, die materials should have high hot hardness, good temper resistance, low solubility in molten aluminum and good oxidation resistance. It is difficult for one material to satisfy with all above requirements. In practice, H13 steel is the most popular material for aluminum die casting dies. While it is not an ideal choice, it is substantially less expensive to use than alternative materials. However, in very demanding applications, it is sometimes necessary to use alternative materials to ensure a reasonable die life. Copper-base, nickel-base alloys and superalloys, titanium-,molybdenum-, tungsten-base alloys, and to some extent yttrium and niobium alloys, have all been considered as potential materials for demanding die casting applications. Most of these alloys exhibit superior thermal fatigue resistance, but suffer from other shortcomings.

  20. Influence of the casting material on the dimensional accuracy of dental dies

    Directory of Open Access Journals (Sweden)

    Daher Antonio Queiroz

    2011-08-01

    Full Text Available The purpose of this study was to evaluate the dimensional accuracy of different materials used in the confection of dies. Two stainless steel standard models were confected. One of the models, which was 2 mm larger than the other model, was used to provide a uniform relief for the two-step putty-wash impression technique. Thirty impressions were obtained using a polyvinyl siloxane impression material and randomly divided into three groups (n = 10 according to the type of casting material: type IV dental stone, commercially available epoxy resin (Tri-Epoxy, and industrial epoxy resin (Sikadur. After the setting/polymerization of the casting material, the dimensional stability was measured in terms of the height, diameter of the base and diameter of the top from the obtained dies and from the standard metal model using a profile projector. Results were analyzed by ANOVA and Dunnet test (α = 0.05. In the height values, no significant difference was observed between the groups, except for Sikadur casts, which showed lower mean values. The Tri-Epoxi group showed statistically lower mean base diameter values, compared with the other groups, and both epoxy resin groups showed statistically lower mean top diameter values, compared with that for the type IV dental stone group. We concluded that type IV gypsum and the commercially available epoxy resin showed similar behavior in most areas. The industrial epoxy resin did not show the same characteristics, although the diameter of the base obtained with it was similar to that obtained with type IV dental stone.

  1. Radiation processed composite materials of wood and elastic polyester resins

    International Nuclear Information System (INIS)

    Tapolcai, I.; Czvikovszky, T.

    1983-01-01

    The radiation polymerization of multifunctional unsaturated polyester-monomer mixtures in wood forms interpenetrating network system. The mechanical resistance (compression, abrasion, hardness, etc.) of these composite materials are generally well over the original wood, however the impact strength is almost the same or even reduced, in comparison to the wood itself. An attempt is made using elastic polyester resins to produced wood-polyester composite materials with improved modulus of elasticity and impact properties. For the impregnation of European beech wood two types of elastic unsaturated polyester resins were used. The exothermic effect of radiation copolymerization of these resins in wood has been measured and the dose rate effects as well as hardening dose was determined. Felxural strength and impact properties were examined. Elastic unsaturated polyester resins improved the impact strength of wood composite materials. (author)

  2. Degradation, Fatigue, and Failure of Resin Dental Composite Materials

    Energy Technology Data Exchange (ETDEWEB)

    Drummond, J.L. (UIC)

    2008-11-03

    The intent of this article is to review the numerous factors that affect the mechanical properties of particle- or fiber-filler-containing indirect dental resin composite materials. The focus will be on the effects of degradation due to aging in different media, mainly water and water and ethanol, cyclic loading, and mixed-mode loading on flexure strength and fracture toughness. Several selected papers will be examined in detail with respect to mixed and cyclic loading, and 3D tomography with multi-axial compression specimens. The main cause of failure, for most dental resin composites, is the breakdown of the resin matrix and/or the interface between the filler and the resin matrix. In clinical studies, it appears that failure in the first 5 years is a restoration issue (technique or material selection); after that time period, failure most often results from secondary decay.

  3. Preparation and Characterizations of Composite Material Based on Carbon Fiber and Two Thermoset Resins

    OpenAIRE

    Fouda Hany; Guo Lin; Elsharkawy Karim

    2017-01-01

    In the present investigation, we used two types of thermoset resins (epoxy resin and phenol formaldehyde resin) with carbon fiber (CF) to produce composite materials. CF/epoxy resin composite and CF/phenolformaldhyde resin composite were fabricated and compared between their mechanical properties as compression, tension and flexural. it was found that mechanical properties of CF/epoxy composite higher than mechanical properties of CF/phenolformaldhyde resin composite such as flexural strength...

  4. Preparation and Characterizations of Composite Material Based on Carbon Fiber and Two Thermoset Resins

    Directory of Open Access Journals (Sweden)

    Fouda Hany

    2017-01-01

    Full Text Available In the present investigation, we used two types of thermoset resins (epoxy resin and phenol formaldehyde resin with carbon fiber (CF to produce composite materials. CF/epoxy resin composite and CF/phenolformaldhyde resin composite were fabricated and compared between their mechanical properties as compression, tension and flexural. it was found that mechanical properties of CF/epoxy composite higher than mechanical properties of CF/phenolformaldhyde resin composite such as flexural strength of CF/epoxy resin composite increased by 30 % than flexural strength of CF/phenolformaldhyde resin composite, tensile strength of CF/epoxy resin composite increased by 11.4 % than flexural strength of CF/phenolformaldhyde resin and axial compression strength of CF/epoxy resin composite increased by 14.5 % than flexural strength of CF/phenolformaldhyde resin.

  5. Characterization of selected LDEF polymer matrix resin composite materials

    Science.gov (United States)

    Young, Philip R.; Slemp, Wayne S.; Witte, William G., Jr.; Shen, James Y.

    1991-01-01

    The characterization of selected graphite fiber reinforced epoxy (934 and 5208) and polysulfone (P1700) matrix resin composite materials which received 5 years and 10 months of exposure to the LEO environment on the Long Duration Exposure Facility is reported. Resin loss and a decrease in mechanical performance as well as dramatic visual effects were observed. However, chemical characterization including infrared, thermal, and selected solution property measurements showed that the molecular structure of the polymeric matrix had not changed significantly in response to this exposure. The potential effect of a silicon-containing molecular contamination of these specimens is addressed.

  6. Nonlinear Inelastic Mechanical Behavior Of Epoxy Resin Polymeric Materials

    Science.gov (United States)

    Yekani Fard, Masoud

    Polymer and polymer matrix composites (PMCs) materials are being used extensively in different civil and mechanical engineering applications. The behavior of the epoxy resin polymers under different types of loading conditions has to be understood before the mechanical behavior of Polymer Matrix Composites (PMCs) can be accurately predicted. In many structural applications, PMC structures are subjected to large flexural loadings, examples include repair of structures against earthquake and engine fan cases. Therefore it is important to characterize and model the flexural mechanical behavior of epoxy resin materials. In this thesis, a comprehensive research effort was undertaken combining experiments and theoretical modeling to investigate the mechanical behavior of epoxy resins subject to different loading conditions. Epoxy resin E 863 was tested at different strain rates. Samples with dog-bone geometry were used in the tension tests. Small sized cubic, prismatic, and cylindrical samples were used in compression tests. Flexural tests were conducted on samples with different sizes and loading conditions. Strains were measured using the digital image correlation (DIC) technique, extensometers, strain gauges, and actuators. Effects of triaxiality state of stress were studied. Cubic, prismatic, and cylindrical compression samples undergo stress drop at yield, but it was found that only cubic samples experience strain hardening before failure. Characteristic points of tensile and compressive stress strain relation and load deflection curve in flexure were measured and their variations with strain rate studied. Two different stress strain models were used to investigate the effect of out-of-plane loading on the uniaxial stress strain response of the epoxy resin material. The first model is a strain softening with plastic flow for tension and compression. The influence of softening localization on material behavior was investigated using the DIC system. It was found that

  7. Fissure sealant materials: Wear resistance of flowable composite resins.

    Science.gov (United States)

    Asefi, Sohrab; Eskandarion, Solmaz; Hamidiaval, Shadi

    2016-01-01

    Background. Wear resistance of pit and fissure sealant materials can influence their retention. Wear characteristics of sealant materials may determine scheduling of check-up visits. The aim of this study was to compare wear resistance of two flowable composite resins with that of posterior composite resin materials. Methods. Thirty-five disk-shaped specimens were prepared in 5 groups, including two flowable composite resins (Estelite Flow Quick and Estelite Flow Quick High Flow), Filtek P90 and Filtek P60 and Tetric N-Ceram. The disk-shaped samples were prepared in 25-mm diameter by packing them into a two-piece aluminum mold and then light-cured. All the specimens were polished for 1minute using 600-grit sand paper. The samples were stored in distilled water at room temperature for 1 week and then worn by two-body abrasion test using "pin-on-disk" method (with distilled water under a 15-Nload at 0.05 m/s, for a distance of 100 meter with Steatite ceramic balls antagonists). A Profilometer was used for evaluating the surface wear. Data were analyzed with the one-way ANOVA. Results. Estelite Flow Quick exhibited 2708.9 ± 578.1 μm(2) and Estelite Flow Quick High Flow exhibited 3206 ± 2445.1 μm(2)of wear but there were no significant differences between the groups. They demonstrated similar wear properties. Conclusion. Estelite flowable composite resins have wear resistance similar to nano- and micro-filled and micro-hybrid composite resins. Therefore, they can be recommended as pit and fissure sealant materials in the posterior region with appropriate mechanical characteristics.

  8. Fissure sealant materials: Wear resistance of flowable composite resins

    Directory of Open Access Journals (Sweden)

    Sohrab Asefi

    2016-08-01

    Full Text Available Background. Wear resistance of pit and fissure sealant materials can influence their retention. Wear characteristics of sealant materials may determine scheduling of check-up visits. The aim of this study was to compare wear resistance of two flowable composite resins with that of posterior composite resin materials. Methods. Thirty-five disk-shaped specimens were prepared in 5 groups, including two flowable composite resins (Estelite Flow Quick and Estelite Flow Quick High Flow, Filtek P90 and Filtek P60 and Tetric N-Ceram. The disk-shaped samples were prepared in 25-mm diameter by packing them into a two-piece aluminum mold and then light-cured. All the specimens were polished for 1minute using 600-grit sand paper. The samples were stored in distilled water at room temperature for 1 week and then worn by two-body abrasion test using "pin-on-disk" method (with distilled water under a 15-Nload at 0.05 m/s, for a distance of 100 meter with Steatite ceramic balls antagonists. A Profilometer was used for evaluating the surface wear. Data were analyzed with the one-way ANOVA. Results. Estelite Flow Quick exhibited 2708.9 ± 578.1 μm2 and Estelite Flow Quick High Flow exhibited 3206 ± 2445.1 μm2of wear but there were no significant differences between the groups. They demonstrated similar wear properties. Conclusion. Estelite flowable composite resins have wear resistance similar to nano- and micro-filled and micro-hybrid composite resins. Therefore, they can be recommended as pit and fissure sealant materials in the posterior region with appropriate mechanical characteristics.

  9. Development of epoxy resin-type neutron shielding materials (I)

    International Nuclear Information System (INIS)

    Cho, Soo Haeng; Kim, Ik Soo; Shin, Young Joon; Do, Jae Bum; Ro, Seung Gy.

    1997-12-01

    Because the exposure to radiation in the nuclear facilities can be fatal to human, it is important to reduce the radiation dose level to a tolerable level. The purpose of this study is to develop highly effective neutron shielding materials for the shipping and storage cask of radioactive materials or in the nuclear /radiation facilities. On this study, we developed epoxy resin based neutron shielding materials and their various materials properties, including neutron shielding ability, fire resistance, combustion characteristics, radiation resistance, thermal and mechanical properties were evaluated experimentally. (author). 31 refs., 22 tabs., 17 figs

  10. Interpenetrating network ceramic-resin composite dental restorative materials.

    Science.gov (United States)

    Swain, M V; Coldea, A; Bilkhair, A; Guess, P C

    2016-01-01

    This paper investigates the structure and some properties of resin infiltrated ceramic network structure materials suitable for CAD/CAM dental restorative applications. Initially the basis of interpenetrating network materials is defined along with placing them into a materials science perspective. This involves identifying potential advantages of such structures beyond that of the individual materials or simple mixing of the components. Observations from a number of recently published papers on this class of materials are summarized. These include the strength, fracture toughness, hardness and damage tolerance, namely to pointed and blunt (spherical) indentation as well as to burr adjustment. In addition a summary of recent results of crowns subjected to simulated clinical conditions using a chewing simulator are presented. These results are rationalized on the basis of existing theoretical considerations. The currently available ceramic-resin IPN material for clinical application is softer, exhibits comparable strength and fracture toughness but with substantial R-curve behavior, has lower E modulus and is more damage tolerant than existing glass-ceramic materials. Chewing simulation observations with crowns of this material indicate that it appears to be more resistant to sliding/impact induced cracking although its overall contact induced breakage load is modest. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  11. Selecting the Best Materials Compositions of Resin Based Bioasphalt

    Science.gov (United States)

    Setyawan, Ary; Widiharjo, Budi; Djumari

    2017-07-01

    Damar asphalt is one type of bioaspal which is a mixture with the main ingredient is a resin as a binder and cooking oil as a solvent. One major drawback of this damar asphalt is the low ductility. To improve the ductility values, then use the added material Filler. Filler serves as a divider between the impurities with damar asphalt, increases ductility and increase the ability of cohesion or bonding between the particles of material damar asphalt. The purpose of this study was to determine damar asphalt modifications to the properties in accordance with the properties of damar asphalt test specifications based on the value of penetration. This method uses some variant on material such as powder bricks and fly ash as a binder. Solvent in constituent used oil and used cooking oil. It also added the polymer latex up to 10% at intervals of 2%. The best composition of damar asphalt materials were obtained with gum rosin, Fly Ash, Oil and Latex. Damar asphalt modification damar asphalt optimum mix of resin (100g pure resin or resin chunk + 350g powder), Fly Ash powder (150g), cooking oil (205g), and latex 4%, ductility increased from 63.5 cm to 119.5 cm, the value of the flash point was originally at temperature of 240 °C to 260 °C, damar asphalt penetration of 68.2 dmm to 43 dmm, and the value of density decreases from 1.01 g / cm3 to 0.99 g / cm3. Damar asphalt at these modifications meet the specifications in terms of solubility in trichlore ethylene is equal to 99.5%, and also meet the affinity of damar asphalt at 99%. With the optimum value, damar asphalt could be categorized as bitumen 40/60 penetration.

  12. Diffusion through composite materials made with thermosetting resins

    International Nuclear Information System (INIS)

    Morin, Bruno.

    1981-08-01

    Medium and low-level radioactive wastes may be coated in a solid matrix mainly made with thermosetting resins: the study of water and cesium migration through composite materials made with thermosetting resins is usefull to compare the water tightness of different coatings. Disks with a thickness of two millimeters were used to measure the water absorption. Diffusion cells including a plane membrane the thickness of which was at least 70μ were used to measure the diffusion of cesium 137. The diffusion coefficient of water in pure thermosetting resins, polyester or epoxyde, is about 10 -9 cm 2 .s -1 ; the diffusion coefficients of cesium in the same materials are about 10 -12 cm 2 .s -1 ; the introduction of solid particles in these polymers generally induces an acceleration of the diffusion process: the diffusion coefficient may reach 10 -8 cm 2 .s -1 . This lost of water-tightness may be reduced either by rendering insoluble the filler mixed to the polymer, or by diminushing the porosity of the interfacial zones by improving the bonding between the polymer and the filler [fr

  13. Linear dimensional changes in plaster die models using different elastomeric materials

    Directory of Open Access Journals (Sweden)

    Jefferson Ricardo Pereira

    2010-09-01

    Full Text Available Dental impression is an important step in the preparation of prostheses since it provides the reproduction of anatomic and surface details of teeth and adjacent structures. The objective of this study was to evaluate the linear dimensional alterations in gypsum dies obtained with different elastomeric materials, using a resin coping impression technique with individual shells. A master cast made of stainless steel with fixed prosthesis characteristics with two prepared abutment teeth was used to obtain the impressions. References points (A, B, C, D, E and F were recorded on the occlusal and buccal surfaces of abutments to register the distances. The impressions were obtained using the following materials: polyether, mercaptan-polysulfide, addition silicone, and condensation silicone. The transfer impressions were made with custom trays and an irreversible hydrocolloid material and were poured with type IV gypsum. The distances between identified points in gypsum dies were measured using an optical microscope and the results were statistically analyzed by ANOVA (p < 0.05 and Tukey's test. The mean of the distances were registered as follows: addition silicone (AB = 13.6 µm, CD=15.0 µm, EF = 14.6 µm, GH=15.2 µm, mercaptan-polysulfide (AB = 36.0 µm, CD = 36.0 µm, EF = 39.6 µm, GH = 40.6 µm, polyether (AB = 35.2 µm, CD = 35.6 µm, EF = 39.4 µm, GH = 41.4 µm and condensation silicone (AB = 69.2 µm, CD = 71.0 µm, EF = 80.6 µm, GH = 81.2 µm. All of the measurements found in gypsum dies were compared to those of a master cast. The results demonstrated that the addition silicone provides the best stability of the compounds tested, followed by polyether, polysulfide and condensation silicone. No statistical differences were obtained between polyether and mercaptan-polysulfide materials.

  14. Neutron shielding material based on colemanite and epoxy resin.

    Science.gov (United States)

    Okuno, Koichi

    2005-01-01

    In recent years, there has been a need for compact shielding design such as self-shielding of a PET cyclotron or upgradation of radiation machinery in existing facilities. In these cases, high performance shielding materials are needed. Concrete or polyethylene have been used for a neutron shield. However, for compact shielding, they fall short in terms of performance or durability. Therefore, a new type of neutron shielding material based on epoxy resin and colemanite has been developed. Slab attenuation experiments up to 40 cm for the new shielding material were carried out using a 252Cf neutron source. Measurement was carried out using a REM-counter, and compared with calculation. The results show that the shielding performance is better than concrete and polyethylene mixed with 10 wt% boron oxide. From the result, we confirmed that the performance of the new material is suitable for practical use.

  15. Chairside resin-based provisional restorative materials for fixed prosthodontics.

    Science.gov (United States)

    Strassler, Howard E; Lowe, Robert A

    2011-01-01

    Provisional restorations are vital to fixed prosthodontics treatment, providing an important diagnostic function while in place. In addition to protecting the prepared teeth, provisionalization enables clinicians to refine biologic and biomechanical issues before the final restoration is fabricated. Adjustments can be made in the provisional restoration to achieve both the clinician's and patient's desired results. The fabrication of temporary restorations requires that clinicians be proficient with a variety of materials and techniques that can be used to make well-adapted and functional provisionals. There are many material choices available to temporize a single crown as well as multi-unit fixed partial dentures, and the selection of provisional materials should be made based on a case-by-case evaluation. This article provides a review of polymeric resin provisional materials.

  16. Microhardness of resin composite materials light-cured through fiber reinforced composite.

    NARCIS (Netherlands)

    Fennis, W.M.M.; Ray, N.J.; Creugers, N.H.J.; Kreulen, C.M.

    2009-01-01

    OBJECTIVES: To compare polymerization efficiency of resin composite basing materials when light-cured through resin composite and fiber reinforced composite (FRC) by testing microhardness. METHODS: Simulated indirect restorations were prepared by application of resin composite (Clearfil AP-X) or FRC

  17. Fracture Resistance of Endodontically Treated Teeth Restored with Biodentine, Resin Modified GIC and Hybrid Composite Resin as a Core Material.

    Science.gov (United States)

    Subash, Dayalan; Shoba, Krishnamma; Aman, Shibu; Bharkavi, Srinivasan Kumar Indu; Nimmi, Vijayan; Abhilash, Radhakrishnan

    2017-09-01

    The restoration of a severely damaged tooth usually needs a post and core as a part of treatment procedure to provide a corono - radicular stabilization. Biodentine is a class of dental material which possess high mechanical properties with excellent biocompatibility and bioactive behaviour. The sealing ability coupled with optimum physical properties could make Biodentine an excellent option as a core material. The aim of the study was to determine the fracture resistance of Biodentine as a core material in comparison with resin modified glass ionomer and composite resin. Freshly extracted 30 human permanent maxillary central incisors were selected. After endodontic treatment followed by post space preparation and luting of Glass fibre post (Reforpost, Angelus), the samples were divided in to three groups based on the type of core material. The core build-up used in Group I was Biodentine (Septodont, France), Group II was Resin-Modified Glass Ionomer Cement (GC, Japan) and Group III was Hybrid Composite Resin (TeEconom plus, Ivoclar vivadent). The specimens were subjected to fracture toughness using Universal testing machine (1474, Zwick/Roell, Germany) and results were compared using One-way analysis of variance with Tukey's Post hoc test. The results showed that there was significant difference between groups in terms of fracture load. Also, composite resin exhibited highest mean fracture load (1039.9 N), whereas teeth restored with Biodentine demonstrated the lowest mean fracture load (176.66 N). Resin modified glass ionomer exhibited intermediate fracture load (612.07 N). The primary mode of failure in Group I and Group II was favourable (100%) while unfavourable fracture was seen in Group III (30%). Biodentine, does not satisfy the requirements to be used as an ideal core material. The uses of RMGIC's as a core build-up material should be limited to non-stress bearing areas. Composite resin is still the best core build-up material owing to its high fracture

  18. Effect of silver nanoparticles incorporation on viscoelastic properties of acrylic resin denture base material

    OpenAIRE

    Mahross, Hamada Zaki; Baroudi, Kusai

    2015-01-01

    Objective: The objective was to investigate the effect of silver nanoparticles (AgNPs) incorporation on viscoelastic properties of acrylic resin denture base material. Materials and Methods: A total of 20 specimens (60 ? 10 ? 2 mm) of heat cured acrylic resin were constructed and divided into four groups (five for each), according to the concentration of AgNPs (1%, 2%, and 5% vol.) which incorporated into the liquid of acrylic resin material and one group without additives (control group). Th...

  19. Microtensile bond strength of indirect resin composite to resin-coated dentin: interaction between diamond bur roughness and coating material.

    Science.gov (United States)

    Kameyama, Atsushi; Oishi, Takumi; Sugawara, Toyotarou; Hirai, Yoshito

    2009-02-01

    This aim of this study was to determine the effect of type of bur and resin-coating material on microtensile bond strength (microTBS) of indirect composite to dentin. Dentin surfaces were first ground with two types of diamond bur and resin-coated using UniFil Bond (UB) or Adper Single Bond (SB), and then bonded to a resin composite disc for indirect restoration with adhesive resin cement. After storage for 24 hr in distilled water at 37 degrees C, microTBS was measured (crosshead speed 1 mm/min). When UB was applied to dentin prepared using the regular-grit diamond bur, microTBS was significantly lower than that in dentin prepared using the superfine-grit bur. In contrast, no significant difference was found between regular-grit and superfine-grit bur with SB. However, more than half of the superfine-grit specimens failed before microTBS testing. These results indicate that selection of bur type is important in improving the bond strength of adhesive resin cement between indirect resin composite and resin-coated dentin.

  20. 49 CFR 173.173 - Paint, paint-related material, adhesives, ink and resins.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Paint, paint-related material, adhesives, ink and... Than Class 1 and Class 7 § 173.173 Paint, paint-related material, adhesives, ink and resins. (a) When..., paint-related material, adhesives, ink and resins must be packaged as follows: (1) As prescribed in...

  1. Acoustic Performance of Resilient Materials Using Acrylic Polymer Emulsion Resin

    Directory of Open Access Journals (Sweden)

    Haseog Kim

    2016-07-01

    Full Text Available There have been frequent cases of civil complaints and disputes in relation to floor impact noises over the years. To solve these issues, a substantial amount of sound resilient material is installed between the concrete slab and the foamed concrete during construction. A new place-type resilient material is made from cement, silica powder, sodium sulfate, expanded-polystyrene, anhydrite, fly ash, and acrylic polymer emulsion resin. Its physical characteristics such as density, compressive strength, dynamic stiffness, and remanent strain are analyzed to assess the acoustic performance of the material. The experimental results showed the density and the dynamic stiffness of the proposed resilient material is increased with proportional to the use of cement and silica powder due to the high contents of the raw materials. The remanent strain, related to the serviceability of a structure, is found to be inversely proportional to the density and strength. The amount of reduction in the heavyweight impact noise is significant in a material with high density, high strength, and low remanent strain. Finally, specimen no. R4, having the reduction level of 3 dB for impact ball and 1 dB for bang machine in the single number quantity level, respectively, is the best product to obtain overall acoustic performance.

  2. Acoustic Performance of Resilient Materials Using Acrylic Polymer Emulsion Resin.

    Science.gov (United States)

    Kim, Haseog; Park, Sangki; Lee, Seahyun

    2016-07-19

    There have been frequent cases of civil complaints and disputes in relation to floor impact noises over the years. To solve these issues, a substantial amount of sound resilient material is installed between the concrete slab and the foamed concrete during construction. A new place-type resilient material is made from cement, silica powder, sodium sulfate, expanded-polystyrene, anhydrite, fly ash, and acrylic polymer emulsion resin. Its physical characteristics such as density, compressive strength, dynamic stiffness, and remanent strain are analyzed to assess the acoustic performance of the material. The experimental results showed the density and the dynamic stiffness of the proposed resilient material is increased with proportional to the use of cement and silica powder due to the high contents of the raw materials. The remanent strain, related to the serviceability of a structure, is found to be inversely proportional to the density and strength. The amount of reduction in the heavyweight impact noise is significant in a material with high density, high strength, and low remanent strain. Finally, specimen no. R4, having the reduction level of 3 dB for impact ball and 1 dB for bang machine in the single number quantity level, respectively, is the best product to obtain overall acoustic performance.

  3. Immobilisation Of Spent Ion Exchange Resins Using Portland Cement Blending With Organic Material

    International Nuclear Information System (INIS)

    Zalina Laili; Mohd Abdul Wahab; Nur Azna Mahmud

    2014-01-01

    Immobilisation of spent ion exchange resins (spent resins) using Portland cement blending with organic material for example bio char was investigated. The performance of cement-bio char matrix for immobilisation of spent ion exchange resins was evaluated based on their compression strength and leachability under different experimental conditions. The results showed that the amount of bio char and spent resins loading effect the compressive strength of the waste form. Several factors affecting the leaching behaviour of immobilised spent resins in cement-bio char matrix. (author)

  4. The bond of different post materials to a resin composite cement and a resin composite core material.

    Science.gov (United States)

    Stewardson, D; Shortall, A; Marquis, P

    2012-01-01

    To investigate the bond of endodontic post materials, with and without grit blasting, to a resin composite cement and a core material using push-out bond strength tests. Fiber-reinforced composite (FRC) posts containing carbon (C) or glass (A) fiber and a steel (S) post were cemented into cylinders of polymerized restorative composite without surface treatment (as controls) and after grit blasting for 8, 16, and 32 seconds. Additional steel post samples were sputter-coated with gold before cementation to prevent chemical interaction with the cement. Cylindrical composite cores were bonded to other samples. After sectioning into discs, bond strengths were determined using push-out testing. Profilometry and electron microscopy were used to assess the effect of grit blasting on surface topography. Mean (standard deviation) bond strength values (MPa) for untreated posts to resin cement were 8.41 (2.80) for C, 9.61(1.88) for A, and 19.90 (3.61) for S. Prolonged grit blasting increased bond strength for FRC posts but produced only a minimal increase for S. After 32 seconds, mean values were 20.65 (4.91) for C, 20.41 (2.93) for A, and 22.97 (2.87) for S. Gold-coated steel samples produced the lowest bond strength value, 7.84 (1.40). Mean bond strengths for untreated posts bonded to composite cores were 6.19 (0.95) for C, 13.22 (1.61) for A, and 8.82 (1.18) for S, and after 32 seconds of grit blasting the values were 17.30 (2.02) for C, 26.47 (3.09) for A, and 20.61 (2.67) for S. FRC materials recorded higher roughness values before and after grit blasting than S. With prolonged grit blasting, roughness increased for A and C, but not for S. There was no evidence of significant bonding to untreated FRC posts, but significant bonding occurred between untreated steel posts and the resin cement. Increases in the roughness of FRC samples were material dependent and roughening significantly increased bond strength values (ptested FRC posts is required for effective bonding.

  5. Composite materials based on modified epoxy resin and carbon fiber

    OpenAIRE

    Gonçalez, Viviane; Barcia, Fabio L.; Soares, Bluma G.

    2006-01-01

    Epoxy resin networks have been modified with block copolymer of polybutadiene and bisphenol A diglycidyl ether (DGEBA)-based on epoxy resin. The epoxy resin modified with carboxyl-terminated polybutadiene presented improved impact resistance and outstanding mechanical performance in terms of flexural and tensile properties because of the presence of rubber particles homogeneously dispersed inside the epoxy matrix. This modified system also resulted in an improvement of mechanical properties o...

  6. Color of bulk-fill composite resin restorative materials.

    Science.gov (United States)

    Barutcigil, Çağatay; Barutcigil, Kubilay; Özarslan, Mehmet Mustafa; Dündar, Ayşe; Yilmaz, Burak

    2017-09-28

    To evaluate the color stability of novel bulk-fill composite resins. Color measurements of a nanohybrid composite resin (Z550) and 3 bulk-fill composite resins (BLK, AFX, XTF; n = 45) were performed before polymerization. After polymerization, color measurements were repeated and specimens were immersed in distilled water or red wine, or coffee. Color change [CIEDE2000 (ΔE 00 )] was calculated after 24 h, 1 and 3 weeks. Data were analyzed with Kruskal-Wallis, Mann-Whitney U and Wilcoxon tests (α = 0.05). Color changes observed after polymerization were significant for all groups. Color changes observed in distilled water for Z550 and AFX were significant. Color changes after stored in red wine and coffee were significant for all groups. Bulk-fill composite resin color change increased over time for all groups in red wine and coffee (P composite resin and bulk-fill composite resins. AFX had the highest color change in distilled water. The color of tested bulk-fill composite resins significantly changed after immersion in beverages and over time. Color change observed with the nanohybrid composite resin after 1 week was stable. Clinicians should keep in mind that tested composite resins may change color when exposed to water and significantly change color immediately after they are polymerized. In addition, the color change continues over time should the patient is a coffee and/or red wine consumer. © 2017 Wiley Periodicals, Inc.

  7. Diametral tensile strength of four composite resin core materials with and without centered fiber dowels.

    Science.gov (United States)

    Driessen, Cornel H; Ji, Donatta Y-J; Rizkalla, Amin S; Santos, Gildo C

    2011-01-01

    This study evaluated the diametral tensile strength of composite resin core materials with and without fiber dowels. Eight groups were established (n = 20), four with composite resins and four with fiber dowels. Samples were tested using a universal testing machine and evaluated using scanning electron microscopy. One-way ANOVA and a Tukey B-rank order test (P = 0.05) indicated that the tensile values of two of the four composite resins decreased significantly when their matching fiber dowels were introduced.

  8. Effect of adhesive resin cements on bond strength of ceramic core materials to dentin.

    Science.gov (United States)

    Gundogdu, M; Aladag, L I

    2018-03-01

    The aim of the present study was to evaluate the effects of self-etch and self-adhesive resin cements on the shear bond strength of ceramic core materials bonded to dentin. Extracted, caries-free, human central maxillary incisor teeth were selected, and the vestibule surfaces were cut flat to obtain dentin surfaces. Ceramic core materials (IPS e.max Press and Prettau Zirconia) were luted to the dentin surfaces using three self-etch adhesive systems (Duo-Link, Panavia F 2.0, and RelyX Ultimate Clicker) and two self-adhesive resin systems (RelyX U200 Automix and Maxcem Elite). A shear bond strength test was performed using a universal testing machine. Failure modes were observed under a stereomicroscope, and bonding interfaces between the adhesive resin cements and the teeth were evaluated with a scanning electron microscope. Data were analyzed with Student's t-test and one-way analysis of variance followed by Tukey's test (α = 0.05). The type of adhesive resin cement significantly affected the shear bond strengths of ceramic core materials bonded to dentin (P materials when the specimens were luted with self-adhesive resin cements (P resin cements exhibited better shear bond strength than the self-adhesive resin cements, except for Panavia cement in the IPS e.max Press group. However, shear bond strengths of the self-adhesive resin cements were dependent on the nature of the ceramic core materials.

  9. Solidification of radioactive waste resins using cement mixed with organic material

    International Nuclear Information System (INIS)

    Laili, Zalina; Yasir, Muhamad Samudi; Wahab, Mohd Abdul

    2015-01-01

    Solidification of radioactive waste resins using cement mixed with organic material i.e. biochar is described in this paper. Different percentage of biochar (0%, 5%, 8%, 11%, 14% and 18%) was investigated in this study. The characteristics such as compressive strength and leaching behavior were examined in order to evaluate the performance of solidified radioactive waste resins. The results showed that the amount of biochar affect the compressive strength of the solidified resins. Based on the data obtained for the leaching experiments performed, only one formulation showed the leached of Cs-134 from the solidified radioactive waste resins

  10. Solidification of radioactive waste resins using cement mixed with organic material

    Energy Technology Data Exchange (ETDEWEB)

    Laili, Zalina, E-mail: liena@nm.gov.my [Nuclear Science Programme, School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), Bangi, 43600, Selangor Malaysia (Malaysia); Waste and Environmental Technology Division, Malaysian Nuclear Agency (Nuclear Malaysia), Bangi, 43000 Kajang, Selangor (Malaysia); Yasir, Muhamad Samudi [Nuclear Science Programme, School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), Bangi, 43600, Selangor Malaysia (Malaysia); Wahab, Mohd Abdul [Waste and Environmental Technology Division, Malaysian Nuclear Agency (Nuclear Malaysia), Bangi, 43000 Kajang, Selangor (Malaysia)

    2015-04-29

    Solidification of radioactive waste resins using cement mixed with organic material i.e. biochar is described in this paper. Different percentage of biochar (0%, 5%, 8%, 11%, 14% and 18%) was investigated in this study. The characteristics such as compressive strength and leaching behavior were examined in order to evaluate the performance of solidified radioactive waste resins. The results showed that the amount of biochar affect the compressive strength of the solidified resins. Based on the data obtained for the leaching experiments performed, only one formulation showed the leached of Cs-134 from the solidified radioactive waste resins.

  11. The application of methacrylate resin and the derivation as restorative material of damaged tooth tissue

    Directory of Open Access Journals (Sweden)

    Adioro Soetojo

    2007-12-01

    Full Text Available The application of methacrylate resin and the derivation (composite resin and dentin bonding in clinical conservative dentistry has been widely developed. This material could be used to restore class I-V cavity with good aesthetic due to the compatible color with tooth. Composite resin adhesion hydrophobically in enamel that is due to mechanic retention in the form of resin tags which penetrates into enamel porosity. Meanwhile hydrophilic dentin bonding adhesion due to the chemical reaction between functional groups of amino collagen with carbonyl in dentin bonding forming amide binding. In addition mechanical retention in which dentin bonding penetrating into nano inter fibrilar cavity then polymerized. The success of methacrylate resin adhesion restoration is decided by enamel porosity, wetting character of resin, wetting contact angle, good etching acid, optimal humidity of tooth surface, the accuracy of dentist during filling is done etc.

  12. Synthesis and Characterization of Bio-Oil Phenol Formaldehyde Resin Used to Fabricate Phenolic Based Materials.

    Science.gov (United States)

    Cui, Yong; Hou, Xiaopeng; Wang, Wenliang; Chang, Jianmin

    2017-06-18

    In this study, bio-oil from the fast pyrolysis of renewable biomass was used as the raw material to synthesize bio-oil phenol formaldehyde (BPF) resin-a desirable resin for fabricating phenolic-based material. During the synthesis process, paraformaldehyde was used to achieve the requirement of high solid content and low viscosity. The properties of BPF resins were tested. Results indicated that BPF resin with the bio-oil addition of 20% had good performance on oxygen index and bending strength, indicating that adding bio-oil could modify the fire resistance and brittleness of PF resin. The thermal curing behavior and heat resistance of BPF resins were investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Results showed that adding bio-oil had an impact on curing characteristics and thermal degradation process of PF resin, but the influence was insignificant when the addition was relatively low. The chemical structure and surface characteristics of BPF resins were determined by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The analysis demonstrated that adding bio-oil in the amount of 20% was able to improve the crosslinking degree and form more hydrocarbon chains in PF resin.

  13. Surface Hardness of Resin Cement Polymerized under Different Ceramic Materials

    OpenAIRE

    Kesrak, Pimmada; Leevailoj, Chalermpol

    2012-01-01

    Objectives. To evaluate the surface hardness of two light-cured resin cements polymerized under different ceramic discs. Methods. 40 experimental groups of 2 light-cured resin cement specimens (Variolink Veneer and NX3) were prepared and polymerized under 5 different ceramic discs (IPS e.max Press HT, LT, MO, HO, and Cercon) of 4 thicknesses (0.5, 1.0, 1.5, and 2.0 mm), Those directly activated of both resin cements were used as control. After light activation and 3 7 ∘ C storage in an incuba...

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

    OpenAIRE

    Nurcan Ozakar Ilday; Yusuf Ziya Bayindir; Funda Bayindir; Aysel Gurpinar

    2013-01-01

    Background/purpose: Several factors may affects microhardness of resin cement under veneering materials. The aim of this study was to evaluate the effect of different veneering materials, light-curing units and curing times (20/3, 40/6) on the microhardness of dual-cured resin cement. Materials and methods: We pressed dual-cured resin cement specimens (Clearfil SA cement, 5 mm diameter, 1 mm thick) between two microscopic glass slides covered with transparent polystyrene matrix strips to r...

  15. Honeycomb core material for sandwich construction - with common hexagonal walls bonded by thermoplastic resin and free walls carrying layer of resin and masking agent

    NARCIS (Netherlands)

    Undetermined, U.

    1991-01-01

    Abstract of NL 8902116 (A) In a honeycomb core material for a sandwich construction, the common hexagonal walls are bonded together by a thermoplastic resin, and the free hexagonal walls carry a layer of the same resin and also a masking agent. - A number of plates of raw material are given strips

  16. Flexural Strength of Cold and Heat Cure Acrylic Resins Reinforced with Different Materials.

    Science.gov (United States)

    Heidari, Bijan; Firouz, Farnaz; Izadi, Alireza; Ahmadvand, Shahbaz; Radan, Pegah

    2015-05-01

    Heat-polymerized acrylic resin has been the most commonly used denture base material for over 60 years. However, the mechanical strength of acrylic resin is not adequate for long-term clinical performance of dentures. Consequently, fracture is a common clinical occurrence, which often develops in the midline of the denture base. This study aimed to evaluate the efficacy of cold-cure and heat-cure acrylic resins, reinforced with glass fibers, polyethylene fibers, and metal wire for denture base repair. Ninety specimens were prepared and allocated to nine groups. Ten specimens were considered as controls, and 80 were divided into 8 experimental groups. In the experimental groups, the specimens were sectioned into two halves from the middle, and were then divided into two main groups: one group was repaired with heat cure acrylic resin, and the other with cold cure acrylic resin. Each group was divided into 4 subgroups: unreinforced, reinforced with glass fibers, polyethylene fibers, and metal wire. All specimens were subjected to a 3-point bending test, and the flexural strength was calculated. The group repaired with heat cure acrylic resin and reinforced with glass fiber showed the highest flexural strength; however, the group repaired with cold cure acrylic resin and reinforced with polyethylene fibers had the lowest flexural strength. There was no significant difference between the groups repaired with heat cure and cold cure acrylic resins without reinforcement. Repairing denture base with heat cure acrylic resin, reinforced with glass fibers increases the flexural strength of denture base.

  17. Synthesis and Characterization of Bio-Oil Phenol Formaldehyde Resin Used to Fabricate Phenolic Based Materials

    Directory of Open Access Journals (Sweden)

    Yong Cui

    2017-06-01

    Full Text Available In this study, bio-oil from the fast pyrolysis of renewable biomass was used as the raw material to synthesize bio-oil phenol formaldehyde (BPF resin—a desirable resin for fabricating phenolic-based material. During the synthesis process, paraformaldehyde was used to achieve the requirement of high solid content and low viscosity. The properties of BPF resins were tested. Results indicated that BPF resin with the bio-oil addition of 20% had good performance on oxygen index and bending strength, indicating that adding bio-oil could modify the fire resistance and brittleness of PF resin. The thermal curing behavior and heat resistance of BPF resins were investigated by differential scanning calorimetry (DSC and thermal gravimetric analysis (TGA. Results showed that adding bio-oil had an impact on curing characteristics and thermal degradation process of PF resin, but the influence was insignificant when the addition was relatively low. The chemical structure and surface characteristics of BPF resins were determined by Fourier transform infrared (FTIR spectroscopy and scanning electron microscopy (SEM. The analysis demonstrated that adding bio-oil in the amount of 20% was able to improve the crosslinking degree and form more hydrocarbon chains in PF resin.

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

    Directory of Open Access Journals (Sweden)

    Nurcan Ozakar Ilday

    2013-06-01

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

  19. Investigate the Possibility of Tekcast Methods Used for Casting Polymeric Resin Materials

    Directory of Open Access Journals (Sweden)

    Mäsiar H.

    2014-06-01

    Full Text Available Contribution gives an overview of knowledge about the method of centrifugal casting with orientate on Tekcast system. Company Tekcast Industries has developed a device for centrifugal casting, extending the area of production of castings or prototyping of metal or plastic. Materials suitable for the centrifugal casting with flexible operating parameters may include non-ferrous metal alloy based on zinc or aluminum or non-metallic materials such as polyester resins, polyurethane resins, epoxy resins, waxes and the like. The casting process is particularly suitable for a wide range of commercial castings and decorative objects.

  20. Synthesis and Characterization of Bio-Oil Phenol Formaldehyde Resin Used to Fabricate Phenolic Based Materials

    OpenAIRE

    Cui, Yong; Hou, Xiaopeng; Wang, Wenliang; Chang, Jianmin

    2017-01-01

    In this study, bio-oil from the fast pyrolysis of renewable biomass was used as the raw material to synthesize bio-oil phenol formaldehyde (BPF) resin—a desirable resin for fabricating phenolic-based material. During the synthesis process, paraformaldehyde was used to achieve the requirement of high solid content and low viscosity. The properties of BPF resins were tested. Results indicated that BPF resin with the bio-oil addition of 20% had good performance on oxygen index and bending streng...

  1. Influence of the material for preformed moulds on the polymerization temperature of resin materials for temporary FPDs.

    Science.gov (United States)

    Pott, Philipp-Cornelius; Schmitz-Wätjen, Hans; Stiesch, Meike; Eisenburger, Michael

    2017-08-01

    Temperature increase of 5.5 ℃ can cause damage or necrosis of the pulp. Increasing temperature can be caused not only by mechanical factors, e.g. grinding, but also by exothermic polymerization reactions of resin materials. The aim of this study was to evaluate influences of the form material on the intrapulpal temperature during the polymerization of different self-curing resin materials for temporary restorations. 30 provisonal bridges were made of 5 resin materials: Prevision Temp (Pre), Protemp 4 (Pro), Luxatemp Star (Lux), Structure 3 (Str) and an experimental material (Exp). Moulds made of alginate (A) and of silicone (S) and vacuum formed moulds (V) were used to build 10 bridges each on a special experimental setup. The intrapulpal temperatures of three abutment teeth (a canine, a premolar, and a molar,) were measured during the polymerization every second under isothermal conditions. Comparisons of the maximum temperature (T Max ) and the time until the maximum temperature (t TMax ) were performed using ANOVA and Tukey Test. Using alginate as the mould material resulted in a cooling effect for every resin material. Using the vacuum formed mould, T Max increased significantly compared to alginate ( P material on t TMax . All of the mould materials are suitable for clinical use if the intraoral application time does not exceed the manufacturer's instructions for the resin materials.

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

    Science.gov (United States)

    Lee, Jung-Won; Cha, Hyun-Suk

    2011-01-01

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

  3. Repair bond strength of dual-cured resin composite core buildup materials.

    Science.gov (United States)

    El-Deeb, Heba A; Ghalab, Radwa M; Elsayed Akah, Mai M; Mobarak, Enas H

    2016-03-01

    The reparability of dual-cured resin composite core buildup materials using a light-cured one following one week or three months storage, prior to repair was evaluated. Two different dual-cured resin composites; Cosmecore™ DC automix and Clearfil™ DC automix core buildup materials and a light-cured nanofilled resin composite; Filtek™ Z350 XT were used. Substrate specimens were prepared (n = 12/each substrate material) and stored in artificial saliva at 37 °C either for one week or three months. Afterward, all specimens were ground flat, etched using Scotchbond™ phosphoric acid etchant and received Single Bond Universal adhesive system according to the manufacturers' instructions. The light-cured nanofilled resin composite (Filtek™ Z350 XT) was used as a repair material buildup. To determine the cohesive strength of each solid substrate material, additional specimens from each core material (n = 12) were prepared and stored for the same periods. Five sticks (0.8 ± 0.01 mm(2)) were obtained from each specimen (30 sticks/group) for microtensile bond strength (μTBS) testing. Modes of failure were also determined. Two-way ANOVA revealed a significant effect for the core materials but not for the storage periods or their interaction. After one week, dual-cured resin composite core buildup materials (Cosmecore™ DC and Clearfil™ DC) achieved significantly higher repair μTBS than the light-cured nanofilled resin composite (Filtek™ Z350 XT). However, Clearfil™ DC revealed the highest value, then Cosmecore™ DC and Filtek™ Z350 XT, following storage for 3-month. Repair strength values recovered 64-86% of the cohesive strengths of solid substrate materials. The predominant mode of failure was the mixed type. Dual-cured resin composite core buildup materials revealed acceptable repair bond strength values even after 3-month storage.

  4. Diffusion in composite materials made of thermosetting resins

    International Nuclear Information System (INIS)

    Morin, Bruno.

    1981-03-01

    The embedding process of low and medium level radioactive wastes in thermosetting resins allows their containment in a solid matrix. During storage the risk of circulation of water is possible. The aim of this containment process is to prevent radionuclide migration in environment. Ion migration through membranes of thermosetting resins alone or filler added were measured to evaluate released radioactivity by embedded blocks with time and to compare the different embedding formulas. Water influence on diffusion was taken into account considering that radioactive wastes dispersion is faster in a wet medium than in a dry one [fr

  5. Mechanical and antibacterial properties of benzothiazole-based dental resin materials.

    Science.gov (United States)

    Zhu, Wenbin; Lao, Chonghui; Luo, Shuzhen; Liu, Fang; Huang, Qiting; He, Jingwei; Lin, Zhengmei

    2018-04-01

    A synthesized benzothiazole containing mono-methacrylate monomer BTTMA was incorporated into Bis-GMA/TEGDMA dental resin system with a series of mass concentration from 5 to 30 wt.% as an antibacterial agent. The influence of BTTMA on physicochemical properties of dental resin system, such as double bond conversion (DC), volumetric shrinkage (VS), flexural strength (FS) and modulus (FM), water sorption (WS) and solubility (SL) were investigated. Direct contact testing and agar diffusion testing were used to evaluate the antibacterial activity of BTTMA containing dental resin. The results showed that BTTMA could endow dental resin with significant antibacterial activity when its concentration reached a certain amount (20 wt.%), and the antibacterial activity of BTTMA containing dental resin was mainly attributed to the immobilized BTTMA instead of the unreacted leachable BTTMA. BTTMA had no negative effect on physicochemical properties of dental resin, and even some BTTMA containing dental resins had advantages like higher DC, lower VS and WS when compared with control resin. Therefore, BTTMA could be considered as a suitable antibacterial agent in dental material, but much more researches concerned about biocompatibility should be done in future to prove whether it could be applied in clinic.

  6. Factors affecting the bond strength of denture base and reline acrylic resins to base metal materials

    Directory of Open Access Journals (Sweden)

    Naomi Tanoue

    2013-07-01

    Full Text Available OBJECTIVE: The shear bond strengths of two hard chairside reline resin materials and an auto-polymerizing denture base resin material to cast Ti and a Co-Cr alloy treated using four conditioning methods were investigated. MATERIAL AND METHODS: Disk specimens (diameter 10 mm and thickness 2.5 mm were cast from pure Ti and Co-Cr alloy. The specimens were wet-ground to a final surface finish of 600 grit, air-dried, and treated with the following bonding systems: 1 air-abraded with 50-70-µm grain alumina (CON; 2 1 + conditioned with a primer, including an acidic phosphonoacetate monomer (MHPA; 3 1 + conditioned with a primer including a diphosphate monomer (MDP; 4 treated with a tribochemical system. Three resin materials were applied to each metal specimen. Shear bond strengths were determined before and after 10,000 thermocycles. RESULTS: The strengths decreased after thermocycling for all combinations. Among the resin materials assessed, the denture base material showed significantly (p<0.05 greater shear bond strengths than the two reline materials, except for the CON condition. After 10,000 thermocycles, the bond strengths of two reline materials decreased to less than 10 MPa for both metals. The bond strengths of the denture base material with MDP were sufficient: 34.56 MPa for cast Ti and 38.30 for Co-Cr alloy. CONCLUSION: Bonding of reline resin materials to metals assessed was clinically insufficient, regardless of metal type, surface treatment, and resin composition. For the relining of metal denture frameworks, a denture base material should be used.

  7. Effect of silver nanoparticles incorporation on viscoelastic properties of acrylic resin denture base material.

    Science.gov (United States)

    Mahross, Hamada Zaki; Baroudi, Kusai

    2015-01-01

    The objective was to investigate the effect of silver nanoparticles (AgNPs) incorporation on viscoelastic properties of acrylic resin denture base material. A total of 20 specimens (60 × 10 × 2 mm) of heat cured acrylic resin were constructed and divided into four groups (five for each), according to the concentration of AgNPs (1%, 2%, and 5% vol.) which incorporated into the liquid of acrylic resin material and one group without additives (control group). The dynamic viscoelastic test for the test specimens was performed using the computerized material testing system. The resulting deflection curves were analyzed by material testing software NEXYGEN MT. The 5% nanoparticles of silver (NAg) had significantly highest mean storage modulus E' and loss tangent Tan δ values followed by 2% NAg (P 0.05). The AgNPs incorporation within the acrylic denture base material can improve its viscoelastic properties.

  8. Cashew nut shell liquid resin used as matrix for compound materials

    International Nuclear Information System (INIS)

    Abreu, Hamilton Ferreira Gomes de; Nogueira, Ricardo Emilio Ferreira Quevedo

    1996-01-01

    Cashew nut shell liquid resin a by product of cashew processing industry is a naturally occurring phenol of low cost and are used in Brazil as fuel in the industrial production of cashew nut or as a structural material when associated with coconut fiber or rice shell. A high measured Tg points to noble applications. This paper presents some properties of LCC resin and concludes that it has good perspectives as a composite matrice to work at elevated temperatures. (author)

  9. Flexural Strength of Cold and Heat Cure Acrylic Resins Reinforced with Different Materials

    Science.gov (United States)

    Heidari, Bijan; Firouz, Farnaz; Izadi, Alireza; Ahmadvand, Shahbaz

    2015-01-01

    Objectives: Heat-polymerized acrylic resin has been the most commonly used denture base material for over 60 years. However, the mechanical strength of acrylic resin is not adequate for long-term clinical performance of dentures. Consequently, fracture is a common clinical occurrence, which often develops in the midline of the denture base. This study aimed to evaluate the efficacy of cold-cure and heat-cure acrylic resins, reinforced with glass fibers, polyethylene fibers, and metal wire for denture base repair. Materials and Methods: Ninety specimens were prepared and allocated to nine groups. Ten specimens were considered as controls, and 80 were divided into 8 experimental groups. In the experimental groups, the specimens were sectioned into two halves from the middle, and were then divided into two main groups: one group was repaired with heat cure acrylic resin, and the other with cold cure acrylic resin. Each group was divided into 4 subgroups: unreinforced, reinforced with glass fibers, polyethylene fibers, and metal wire. All specimens were subjected to a 3-point bending test, and the flexural strength was calculated. Results: The group repaired with heat cure acrylic resin and reinforced with glass fiber showed the highest flexural strength; however, the group repaired with cold cure acrylic resin and reinforced with polyethylene fibers had the lowest flexural strength. There was no significant difference between the groups repaired with heat cure and cold cure acrylic resins without reinforcement. Conclusion: Repairing denture base with heat cure acrylic resin, reinforced with glass fibers increases the flexural strength of denture base. PMID:26877726

  10. Flexural Strength of Cold and Heat Cure Acrylic Resins Reinforced with Different Materials

    Directory of Open Access Journals (Sweden)

    Bijan Heidari

    2015-10-01

    Full Text Available Objectives: Heat-polymerized acrylic resin has been the most commonly used denture base material for over 60 years. However, the mechanical strength of acrylic resin is not adequate for long-term clinical performance of dentures. Consequently, fracture is a com- mon clinical occurrence, which often occurs in the midline of denture base.This study aimed to evaluate the efficacy of cold cure and heat cure acrylic resins, rein- forced with glass fibers, polyethylene fibers, and metal wire for denture base repair.Materials and Methods: Ninety specimens were prepared and allocated to nine groups. Ten specimens were included in the control group, and 80 were allocated to 8 experi- mental groups. In the experimental groups, the specimens were sectioned into two halves from the middle, and were then divided into two main groups: one group was repaired with heat cure acrylic resin, and the other with cold cure acrylic resin. Each group was di- vided into 4 subgroups: unreinforced, reinforced with glass fibers, polyethylene fibers, and metal wire. All specimens were then subjected to a 3-point bending test, and the flexural strength was calculated.Results: The group repaired with heat cure acrylic resin and reinforced with glass fiber showed the highest flexural strength; however, the group repaired with cold cure acrylic resin and reinforced with polyethylene fibers had the lowest flexural strength. There was no significant difference between the groups repaired with heat cure and cold cure acrylic resins without reinforcement.Conclusion: Repairing denture base with heat cure acrylic resin, reinforced with glass fi- bers increases the flexural strength of denture base.

  11. Fabrication of Closed Hollow Bulb Obturator Using Thermoplastic Resin Material

    Directory of Open Access Journals (Sweden)

    Bidhan Shrestha

    2015-01-01

    Full Text Available Purpose. Closed hollow bulb obturators are used for the rehabilitation of postmaxillectomy patients. However, the time consuming process, complexity of fabrication, water leakage, and discoloration are notable disadvantages of this technique. This paper describes a clinical report of fabricating closed hollow bulb obturator using a single flask and one time processing method for an acquired maxillary defect. Hard thermoplastic resin sheet has been used for the fabrication of hollow bulb part of the obturator. Method. After fabrication of master cast conventionally, bulb and lid part of the defect were formed separately and joined by autopolymerizing acrylic resin to form one sized smaller hollow body. During packing procedure, the defect area was loaded with heat polymerizing acrylic resin and then previously fabricated smaller hollow body was adapted over it. The whole area was then loaded with heat cure acrylic. Further processes were carried out conventionally. Conclusion. This technique uses single flask which reduces laboratory time and makes the procedure simple. The thickness of hollow bulb can be controlled and light weight closed hollow bulb prosthesis can be fabricated. It also minimizes the disadvantages of closed hollow bulb obturator such as water leakage, bacterial infection, and discoloration.

  12. A comparative evaluation of the marginal adaptation of a thermoplastic resin, a light cured wax and an inlay casting wax on stone dies: An in vitro study

    Directory of Open Access Journals (Sweden)

    Reji P Gopalan

    2018-01-01

    Conclusion: The marginal adaptation of all the three materials used, was well within the acceptable range of 25–70 μm. The resin pattern materials studied revealed significantly less dimensional change than inlay casting wax on storage at 1, 12, and 24 h time intervals. They may be employed in situations where high precision and delayed investing is expected.

  13. Electronically and ionically conductive porous material and method for manufacture of resin wafers therefrom

    Energy Technology Data Exchange (ETDEWEB)

    Lin, YuPo J [Naperville, IL; Henry, Michael P [Batavia, IL; Snyder, Seth W [Lincolnwood, IL

    2008-11-18

    An electrically and ionically conductive porous material including a thermoplastic binder and one or more of anion exchange moieties or cation exchange moieties or mixtures thereof and/or one or more of a protein capture resin and an electrically conductive material. The thermoplastic binder immobilizes the moieties with respect to each other but does not substantially coat the moieties and forms the electrically conductive porous material. A wafer of the material and a method of making the material and wafer are disclosed.

  14. Electronically and ionically conductive porous material and method for manufacture of resin wafers therefrom

    Science.gov (United States)

    Lin, YuPo J [Naperville, IL; Henry, Michael P [Batavia, IL; Snyder, Seth W [Lincolnwood, IL

    2011-07-12

    An electrically and ionically conductive porous material including a thermoplastic binder and one or more of anion exchange moieties or cation exchange moieties or mixtures thereof and/or one or more of a protein capture resin and an electrically conductive material. The thermoplastic binder immobilizes the moieties with respect to each other but does not substantially coat the moieties and forms the electrically conductive porous material. A wafer of the material and a method of making the material and wafer are disclosed.

  15. Nanostructured composites based on carbon nanotubes and epoxy resin for use as radar absorbing materials

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Valdirene Aparecida [Instituto Tecnologico de Aeronautica (ITA), Sao Jose dos Campos, SP (Brazil); Folgueras, Luiza de Castro; Candido, Geraldo Mauricio; Paula, Adriano Luiz de; Rezende, Mirabel Cerqueira, E-mail: mirabelmcr@iae.cta.br [Instituto de Aeronautica e Espaco (IAE), Sao Jose dos Campos, SP (Brazil). Div. de Materiais; Costa, Michelle Leali [Universidade Estadual Paulista Julio de Mesquita Filho (DMT/UNESP), Guaratingueta, SP (Brazil). Dept. de Materiais e Tecnologia

    2013-07-01

    Nanostructured polymer composites have opened up new perspectives for multifunctional materials. In particular, carbon nanotubes (CNTs) present potential applications in order to improve mechanical and electrical performance in composites with aerospace application. The combination of epoxy resin with multi walled carbon nanotubes results in a new functional material with enhanced electromagnetic properties. The objective of this work was the processing of radar absorbing materials based on formulations containing different quantities of carbon nanotubes in an epoxy resin matrix. To reach this objective the adequate concentration of CNTs in the resin matrix was determined. The processed structures were characterized by scanning electron microscopy, rheology, thermal and reflectivity in the frequency range of 8.2 to 12.4 GHz analyses. The microwave attenuation was up to 99.7%, using only 0.5% (w/w) of CNT, showing that these materials present advantages in performance associated with low additive concentrations (author)

  16. Nanostructured composites based on carbon nanotubes and epoxy resin for use as radar absorbing materials

    International Nuclear Information System (INIS)

    Silva, Valdirene Aparecida; Folgueras, Luiza de Castro; Candido, Geraldo Mauricio; Paula, Adriano Luiz de; Rezende, Mirabel Cerqueira; Costa, Michelle Leali

    2013-01-01

    Nanostructured polymer composites have opened up new perspectives for multifunctional materials. In particular, carbon nanotubes (CNTs) present potential applications in order to improve mechanical and electrical performance in composites with aerospace application. The combination of epoxy resin with multi walled carbon nanotubes results in a new functional material with enhanced electromagnetic properties. The objective of this work was the processing of radar absorbing materials based on formulations containing different quantities of carbon nanotubes in an epoxy resin matrix. To reach this objective the adequate concentration of CNTs in the resin matrix was determined. The processed structures were characterized by scanning electron microscopy, rheology, thermal and reflectivity in the frequency range of 8.2 to 12.4 GHz analyses. The microwave attenuation was up to 99.7%, using only 0.5% (w/w) of CNT, showing that these materials present advantages in performance associated with low additive concentrations (author)

  17. Application of High-Temperature Mold Materials to Die Cast Copper Motor Rotor for Improved Efficiency

    Energy Technology Data Exchange (ETDEWEB)

    John G. Cowie; Edwin F. Brush, Jr.; Dale T. Peters; Stephen P. Midson; Darryl J. Van Son

    2003-05-01

    The objective of the study, Application of High-Temperature Mold Materials to Die Cast Copper Motor Rotor for Improved Efficiency, was to support the Copper Development Association (CDA) in its effort to design, fabricate and demonstrate mold technologies designed to withstand the copper motor rotor die casting environment for an economically acceptable life. The anticipated result from the compiled data and tests were to: (1) identify materials suitable for die casting copper, (2) fabricate motor rotor molds and (3) supply copper rotor motors for testing in actual compressor systems. Compressor manufacturers can apply the results to assess the technical and economical viability of copper rotor motors.

  18. A study on the radiopacity of cavity lining materials for posterior composite resin restoration

    International Nuclear Information System (INIS)

    Moon, Joo Hoon; Choi, Eui Hwan

    2000-01-01

    The aim of this study was to determine the relative radiopacities of cavity lining materials (Resin-modified Glass Ionomer cement, Compomer and Flowable resin) for posterior composite resin restoration. Resin-modified glass ionomer cement (Fuji II LC, Vitrebond (TM)), Compomers (Dyract , Compoglass, F2000, Dyract(R) flow Compoglass Flow) and Flowable resins (Tetric (R) flow, Aeliteflo (TM) Revolution (TM)) were used. Five specimens of 5 mm in diameter and 2 mm thick were fabricated with each material. Human molars were horizontally sectioned 2 mm thick to include both enamel and dentin. The radiopacities of enamel, dentin, cavity lining materials, aluminum step wedge were obtained from conventional radiograph and NIH image program. All the tested lining materials showed levels of radiopacity the same as or greater than that of dentin. All compomer tested (Dyract (R), Compoglass, F2000, Dyract (R) flow, Compoglass Flow) and Vitrebond (TM), Tetric (R) flow were more radiopaque than enamel. The radiopacities of Fuji II LC and Revolution (TM) were between enamel and dentin and resin-modified glass ionomer cement, Compomer and Tetric (R) flow were greater than those of Revolution (TM), Aeliteflo (TM) or dentin. The level of radiopacity of the tested materials was variable; those with low radiopacity should be avoided in class II restorations, where a clear determination of recurrent caries by the examining clinician could be compromised. Clinician should be able to distinguish these cavity lining materials radiographically from recurrent decay, voids, gaps, or other defects that lead to clinical failure. Utilization of materials ranked more radiopaque than enamel would enable clinicians to distinguish the lining material from tooth structure.

  19. A study on the radiopacity of cavity lining materials for posterior composite resin restoration

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Joo Hoon [Dept. of Oral and Maxillofacial Radiology, College of Dentistry, Chosun University, Kwangju (Korea, Republic of); Choi, Eui Hwan [Dept. of Conservative Dentistry, College of Dentistry, Chosun University, Kwangju (Korea, Republic of)

    2000-12-15

    The aim of this study was to determine the relative radiopacities of cavity lining materials (Resin-modified Glass Ionomer cement, Compomer and Flowable resin) for posterior composite resin restoration. Resin-modified glass ionomer cement (Fuji II LC, Vitrebond (TM)), Compomers (Dyract , Compoglass, F2000, Dyract(R) flow Compoglass Flow) and Flowable resins (Tetric (R) flow, Aeliteflo (TM) Revolution (TM)) were used. Five specimens of 5 mm in diameter and 2 mm thick were fabricated with each material. Human molars were horizontally sectioned 2 mm thick to include both enamel and dentin. The radiopacities of enamel, dentin, cavity lining materials, aluminum step wedge were obtained from conventional radiograph and NIH image program. All the tested lining materials showed levels of radiopacity the same as or greater than that of dentin. All compomer tested (Dyract (R), Compoglass, F2000, Dyract (R) flow, Compoglass Flow) and Vitrebond (TM), Tetric (R) flow were more radiopaque than enamel. The radiopacities of Fuji II LC and Revolution (TM) were between enamel and dentin and resin-modified glass ionomer cement, Compomer and Tetric (R) flow were greater than those of Revolution (TM), Aeliteflo (TM) or dentin. The level of radiopacity of the tested materials was variable; those with low radiopacity should be avoided in class II restorations, where a clear determination of recurrent caries by the examining clinician could be compromised. Clinician should be able to distinguish these cavity lining materials radiographically from recurrent decay, voids, gaps, or other defects that lead to clinical failure. Utilization of materials ranked more radiopaque than enamel would enable clinicians to distinguish the lining material from tooth structure.

  20. Investigation into the Depth of Cure of Resin-Modified Glass-Ionomer Restorative Materials

    Science.gov (United States)

    2006-08-01

    glass - ionomer restorative dental materials. Samples of different thicknesses using...attempt at delineating the depth of cure of resin-modified glass - ionomer restorative dental materials. Samples of different thicknesses using Vitremer... glass ionomers liners. Dent Mater 1993:9:198-203. 16. Culbertson BM. Glass - ionomer dental restoratives . Prog Polym Sci 2001 ;26:577-604. 17. Fuji II

  1. A long-term laboratory test on staining susceptibility of esthetic composite resin materials

    NARCIS (Netherlands)

    Ardu, S.; Braut, V.; Gutemberg, D.; Krejci, I.; Dietschi, D.; Feilzer, A.J.

    2010-01-01

    Objective: To evaluate the color stability of composite resin types designed for esthetic anterior restorations when continuously exposed to various staining agents. Method and Materials: Thirty-six disk-shaped specimens were made of each of 12 composite materials (1 microfilled and 11 hybrid

  2. Effect of polishing systems on stain susceptibility and surface roughness of nanocomposite resin material.

    Science.gov (United States)

    Barakah, Haifa M; Taher, Nadia M

    2014-09-01

    Different polishing systems vary in their effect on reducing surface roughness and stain susceptibility of dental composite resin materials. The purpose of this study was to compare the effect of 3 polishing systems on the stain susceptibility and surface roughness of 2 nanocomposite resins and a microhybrid composite resin. Forty-five disks (2×10 mm) each were fabricated of 2 nanocomposite resins (Filtek Supreme XT and Tetric EvoCeram) and 1 microhybrid composite resin (Z250). Both sides of the disks were wet finished, and 1 side was polished with PoGo, Astropol, or Hi-Shine (n=5). Unpolished surfaces served as controls. The average roughness (Ra, μm) was measured with a profilometer, and the baseline color was recorded with a spectrophotometer. All specimens were incubated while soaking in a staining solution of coffee, green tea, and berry juice for 3 weeks. The color was recorded again, and the data were analyzed with 2-way ANOVA at α=.05 and Tukey multiple comparison tests. All polishing systems improved the staining resistance of Filtek Supreme XT and Z250 but did not affect that of Tetric EvoCeram. The surface color of Filtek Supreme XT was changed significantly and was the smoothest after polishing with PoGo, whereas Hi-Shine produced significantly rougher surfaces but with the lowest color change. Hi-Shine produced the highest color change in Z250. The surface roughness did not differ significantly between the other polishing systems. Tetric EvoCeram showed no significant differences in color change or surface roughness. Staining susceptibility and surface roughness depend mainly on material composition and on the polishing procedures. Polishing improves the staining resistance of composite resins. Nanocomposite resins did not exhibit better staining resistance or surface roughness than microhybrid composite resin. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  3. Physical Property Investigation of Two Recently Marketed Resin Composite Restorative Materials

    Science.gov (United States)

    2015-06-18

    Huysmans  MCDNJM.  12-­‐year   Survival  of   Composite  vs.   Amalgam  Restorations.  J  Dent  Res  2010;  89:1063-­‐   1067...Marketed Resin Composite Restorative Materials 7. Intended publication/meeting: International Association of Dental Research Annual Meeting 8...Marketed Resin Composite Restorative Materials Major Marcus P. Kropf APPROVED; Colo71 Howard W. Roberts Date APPROVED: Col Drew W. Fallis Dean, Air

  4. The influence of powder liquid ratio on the flexural strength of fibre reinforced acrylic resin material.

    Science.gov (United States)

    Geerts, G A V M; du Rand, M

    2009-04-01

    Often the powder liquid (P/L) ratio of polymethyl methacrylate (PMMA) resins is changed to modify the handling properties of the material. While it is known that this may influence the mechanical properties of unreinforced PMMA resin, little is known about its effect on fibre reinforced resin. The purpose of this study was to determine how different P/L ratios influence the flexural strength (FS) of a glass fibre reinforced autopolymerizing PMMA resin used for fabricating fixed partial dentures. Two main groups of PMMA resin, 1 unreinforced and 1 reinforced with glass fibre, had 3 subgroups (n=21) each representing a different P/L ratio. The manufacturer's recommended ratio served as control. The specimens were prepared for a 3-point bending test. Using a universal testing machine, maximum force was recorded and the FS was calculated. Median FS values were compared by means of non-parametric analysis of variance (Kruskal-Wallis). A p-value of less than 0.05 was considered significant. FS values of all reinforced subgroups were significantly higher than the values of the unreinforced subgroups (p0.05). Within the reinforced group there was a significant difference between the control group, which had a higher median FS value than the two other subgroups (presin with glass fibre, it is important to use the recommended P/L ratio. For unreinforced PMMA resin the P/L ratio can be changed within limits without adverse effects on the FS.

  5. Aspects of bonding between resin luting cements and glass ceramic materials.

    Science.gov (United States)

    Tian, Tian; Tsoi, James Kit-Hon; Matinlinna, Jukka P; Burrow, Michael F

    2014-07-01

    The bonding interface of glass ceramics and resin luting cements plays an important role in the long-term durability of ceramic restorations. The purpose of this systematic review is to discuss the various factors involved with the bond between glass ceramics and resin luting cements. An electronic Pubmed, Medline and Embase search was conducted to obtain laboratory studies on resin-ceramic bonding published in English and Chinese between 1972 and 2012. Eighty-three articles were included in this review. Various factors that have a possible impact on the bond between glass ceramics and resin cements were discussed, including ceramic type, ceramic crystal structure, resin luting cements, light curing, surface treatments, and laboratory test methodology. Resin-ceramic bonding has been improved substantially in the past few years. Hydrofluoric acid (HF) etching followed by silanizaiton has become the most widely accepted surface treatment for glass ceramics. However, further studies need to be undertaken to improve surface preparations without HF because of its toxicity. Laboratory test methods are also required to better simulate the actual oral environment for more clinically compatible testing. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  6. Studi Eksperimental Laju Keausan Material Gigi Tiruan dari Resin Akrilik Berpenguat Fiberglass dengan Variasi Susunan Serat Penguat

    OpenAIRE

    Kristasari, Prastika; Kaelani, Yusuf

    2016-01-01

    Resin akrilik adalah salah satu material yang mulai banyak digunakan sebagai salah satu material untuk pembuatan gigi tiruan. Penelitian sebelumnya tentang analisis pengujian laju keausan resin akrilik berpenguat serat pada dental prosthesis pada kondisi dry sliding menunjukkan hasil nilai laju keausan berkurang dengan adanya penambahan serat[1]. Saat ini belum ada kajian mengenai laju keausan resin akrilik berpenguat serat pada kondisi wet sliding dengan variasi pola susunan serat yang berbe...

  7. Development of a new neutron shielding material, TN trademark Resin Vyal for transport/storage casks for radioactive materials

    International Nuclear Information System (INIS)

    Abadie, P.

    2004-01-01

    TN trademark Resin Vyal, a patent pending composite, is a new neutron shielding material developed by COGEMA LOGISTICS for transport/storage casks of radioactive materials (spent fuel, reprocessed fuel,..). This material is composed of a thermosetting resin (vinylester resin in solution of styrene) and two mineral fillers (alumine hydrate and zinc borate). Its shielding ability for neutron radiation is related to a high hydrogen content (for slowing down neutrons) and a high boron content (for absorbing neutrons). Source of hydrogen is organic matrix (resin) and alumine hydrate; source of boron is zinc borate. Atomic concentrations are equal to 5.10 22 at/cm 3 for hydrogen and 9.10 20 at/cm 3 for boron. Due to the flame retardant character of components, the final material has a good fire resistance (it is auto-extinguishable). Its density is equal to 1,8. The manufacturing process of these material is easy: it consists in mixing the fillers and pouring in-situ (in cask); so, the curing of this composite, which leads to a three-dimensional structure, takes place at ambient temperature. Temperature resistance of this material was evaluated by performing exposition tests of samples at different temperatures (150 C to 170 C). According to tests results, its maximal temperature of use was confirmed equal to 160 C

  8. Effect of 180 days of water storage on the transverse strength of acetal resin denture base material.

    Science.gov (United States)

    Arikan, Ayla; Ozkan, Yasemin Kulak; Arda, Tugberk; Akalin, Buket

    2010-01-01

    Acetal resin has been used as an alternative denture base and clasp material since 1986. The manufacturers claim that acetal resin has superior physical properties when compared to conventional denture base acrylic resins. Limited information is available about transverse strengths of acetal resin. The purpose of this investigation was to compare transverse strengths of pink and white acetal resins to transverse strengths of conventional heat-polymerized polymethylmethacrylate (PMMA) resin in increasing durations of water storage. A transverse strength test was performed in accordance with International Standards Organization (ISO) specification No 1567. Twenty 65 x 10 x 2.5 mm(3) specimens of each resin were prepared; five specimens of each resin group were subjected to three-point bending test after 50 hours, 30 days, 60 days, and 180 days of water storage in distilled water at 37 degrees C. Experimental groups' transverse strengths were compared by three-way ANOVA and Duncan's multiple range tests. Transverse strength of PMMA denture base material was found to be in accordance with the requirements of ISO specification No 1567. Transverse strengths of white and pink acetal resin could not be calculated in this study, as white and pink acetal resin specimens did not break at the maximum applied force in the three-point bending test. Flexural strength of acetal resin was found to be within the ISO specification limits. As the water storage time increased, the deflection values of PMMA showed no significant difference (p > 0.05). Both the white and pink acetal resin showed significant increase in deflection as the water storage time was increased from 50 hours to 180 days (p resin suffered from permanent deformation, but did not break in the three-point bending test. Acetal resin showed significant increase in deflection as the water storage time was increased from 50 hours to 180 days. All materials tested demonstrated deflection values in compliance with ISO

  9. Development of highly effective neutron shielding material made of phenol-novolac type epoxy resin

    International Nuclear Information System (INIS)

    Cho, Soo Haeng; Jeong, Myeong Soo; Hong, Sun Seok; Lee, Won Kyoung; Kim, Ik Soo; Shin, Young Joon; Do, Jae Bum; Ro, Seung Gy; Oh, Seok Jin

    1998-06-01

    Because the exposure to radiation in the nuclear facilities can be fatal to human, it is important to reduce the radiation dose level to a tolerable level. The purpose of this study is to develop highly effective neutron shielding materials for the shipping and storage cask of radioactive materials or in the nuclear/radiation facilities. On this study, we developed epoxy resin based neutron shielding materials and their various material properties, including neutron shielding ability, fire resistance, combustion characteristics, radiation resistance, thermal and mechanical properties were evaluated experimentally. Especially we developed phenol-novolac type epoxy resin based neutron shielding materials and their characteristics were also evaluated. (author). 22 refs., 11 tabs., 21 figs

  10. Radiopacity of bulk fill flowable resin composite materials | Yildirim ...

    African Journals Online (AJOL)

    Objectives: The purpose of this study was to evaluate the radiopacity of currently marketed bulk fill flowable dental composite materials (Beautifil Bulk Flowable, SDR Flow, Filtek Bulk Fill Flow, and x‑tra Base Bulk Fill). Materials and Methods: Six specimens of each material with a thickness of 1 mm were prepared, and ...

  11. Radiopacity of bulk fill flowable resin composite materials

    African Journals Online (AJOL)

    2015-08-23

    Aug 23, 2015 ... Objectives: The purpose of this study was to evaluate the radiopacity of currently marketed bulk fill flowable dental composite materials (Beautifil Bulk Flowable, SDR Flow, Filtek Bulk Fill Flow, and x‑tra Base Bulk Fill). Materials and Methods: Six specimens of each material with a thickness of 1 mm were ...

  12. Preliminary guidelines and recommendations for the development of material and process specifications for carbon fiber-reinforced liquid resin molded materials.

    Science.gov (United States)

    2007-05-01

    This document recommends guidance and criteria for the development of material and process specifications and material acceptance documents for liquid resins and continuous carbon fiber reinforcement materials used in liquid molding processes to manu...

  13. Resin bond to indirect composite and new ceramic/polymer materials: a review of the literature.

    Science.gov (United States)

    Spitznagel, Frank A; Horvath, Sebastian D; Guess, Petra C; Blatz, Markus B

    2014-01-01

    Resin bonding is essential for clinical longevity of indirect restorations. Especially in light of the increasing popularity of computer-aided design/computer-aided manufacturing-fabricated indirect restorations, there is a need to assess optimal bonding protocols for new ceramic/polymer materials and indirect composites. The aim of this article was to review and assess the current scientific evidence on the resin bond to indirect composite and new ceramic/polymer materials. An electronic PubMed database search was conducted from 1966 to September 2013 for in vitro studies pertaining the resin bond to indirect composite and new ceramic/polymer materials. The search revealed 198 titles. Full-text screening was carried out for 43 studies, yielding 18 relevant articles that complied with inclusion criteria. No relevant studies could be identified regarding new ceramic/polymer materials. Most common surface treatments are aluminum-oxide air-abrasion, silane treatment, and hydrofluoric acid-etching for indirect composite restoration. Self-adhesive cements achieve lower bond strengths in comparison with etch-and-rinse systems. Thermocycling has a greater impact on bonding behavior than water storage. Air-particle abrasion and additional silane treatment should be applied to enhance the resin bond to laboratory-processed composites. However, there is an urgent need for in vitro studies that evaluate the bond strength to new ceramic/polymer materials. This article reviews the available dental literature on resin bond of laboratory composites and gives scientifically based guidance for their successful placement. Furthermore, this review demonstrated that future research for new ceramic/polymer materials is required. © 2014 Wiley Periodicals, Inc.

  14. Performance of three resin-based materials for treating uranium-contaminated groundwater within a PRB

    International Nuclear Information System (INIS)

    Barton, Catherine S.; Stewart, Douglas I.; Morris, Katherine; Bryant, David E.

    2004-01-01

    Three materials that are designed to treat uranium-contaminated water were investigated. These are a cation exchange resin, IRN 77; an anion exchange resin, Varion AP; and a recently developed material called PANSIL (quartz sand coated with 2% amidoxime resin by weight). The reaction rate, capacity, and effective pH range of the three materials are reported. The capacity and conditional distribution coefficient in neutral, uranyl-contaminated synthetic groundwater containing carbonate are also reported. The suitability of each material for treating uranium-contaminated groundwater using a permeable reactive barrier (PRB) approach is then discussed. All three materials react rapidly in the pH range 5-7, reaching equilibrium in less than 4 h at ∼23 deg. C. The unconditioned cation exchange resin removed 8 g UO 2 2+ per kg of resin from neutral synthetic groundwater containing 30 mg/l of UO 2 2+ , but a lower capacity is anticipated in groundwater with either higher ionic strength or lower UO 2 2+ concentrations. It operates by first acidifying the solution, then sorbing UO 2 2+ , and can release UO 2 2+ when its buffering capacity has been exhausted. The anion exchange resin is very effective at removing anionic uranyl carbonate species from solutions with a pH above 5, with good specificity. Up to 50 g/kg of uranium is removed from contaminated groundwater at neutral pH. PANSIL is effective at sequestering cationic and neutral uranyl species from solutions in the pH range 4.5-7.5, with very good specificity. The capacity of PANSIL is pH-dependent, increasing from about 0.4 g/kg at pH 4.5, to about 1 g/kg at pH 6, and 1.5 g/kg around pH 7.5. In neutral groundwater containing carbonate, both the anion exchange resin and PANSIL exhibit conditional distribution coefficients exceeding 1470 ml/g, which is about an order of magnitude higher than comparable reactive barrier materials reported in the literature

  15. Epoxy resin synthesis using low molecular weight lignin separated from various lignocellulosic materials.

    Science.gov (United States)

    Asada, Chikako; Basnet, Sunita; Otsuka, Masaya; Sasaki, Chizuru; Nakamura, Yoshitoshi

    2015-03-01

    A low molecular weight lignin from various lignocellulosic materials was used for the synthesis of bio-based epoxy resins. The lignin extracted with methanol from steam-exploded samples (steaming time of 5 min at steam pressure of 3.5 MPa) from different biomasses (i.e., cedar, eucalyptus, and bamboo) were functionalized by the reaction with epichlorohydrin, catalyzed by a water-soluble phase transfer catalyst tetramethylammonium chloride, which was further reacted with 30 wt% aqueous NaOH for ring closure using methyl ethyl ketone as a solvent. The glycidylated products of the lignin with good yields were cured to epoxy polymer networks with bio-based curing agents i.e., lignin itself and a commercial curing agent TD2131. Relatively good thermal properties of the bio-based epoxy network was obtained and thermal decomposition temperature at 5% weight loss (Td5) of cedar-derived epoxy resin was higher than that derived from eucalyptus and bamboo. The bio-based resin satisfies the stability requirement of epoxy resin applicable for electric circuit boards. The methanol-insoluble residues were enzymatically hydrolyzed to produce glucose. This study indicated that the biomass-derived methanol-soluble lignin may be a promising candidate to be used as a substitute for petroleum-based epoxy resin derived from bisphenol A, while insoluble residues may be processed to give a bioethanol precursor i.e., glucose. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Two-photon polymerization of an epoxy-acrylate resin material system

    International Nuclear Information System (INIS)

    Winfield, R.J.; O'Brien, S.

    2011-01-01

    Improved material systems are of great interest in the development of two-photon polymerization techniques for the fabrication of three dimensional micro- and nano-structures. The properties of the photosensitive resin are important in the realisation of structures with submicron dimensions. In this study investigation of a custom organic resin, cross-linked by a two-photon induced process, using a femtosecond Ti:sapphire laser, is described. A structural, optical and mechanical analysis of the optimised material is presented. The influence of both material system and laser processing parameters on achievable micro-structure and size is presented as are representative structures. Parameters include: laser power, photo-initiator concentration and material composition.

  17. Study on polyethylene glycol/epoxy resin composite as a form-stable phase change material

    International Nuclear Information System (INIS)

    Fang Yutang; Kang Huiying; Wang Weilong; Liu Hong; Gao Xuenong

    2010-01-01

    Form-stable polyethylene glycol (PEG)/epoxy resin (EP) composite as a novel phase change material (PCM) was prepared using casting molding method. In this new material, PEG acts as the latent heat storage material and EP polymer serves as the supporting material, which provides structural strength and prevents the leakage of the melted PEG. The structure and morphology of the novel composite were observed using Fourier transformation infrared spectroscope (FTIR) and scanning electronic microscope (SEM). The thermo-mechanical property and transition behavior were characterized by polarizing optical microscope (POM), static thermo-mechanical analysis (TMA) and differential scanning calorimeter (DSC). The experimental results show that, as a result of the physical tangled function of the epoxy resin carrier to the PEG segment, the composite macroscopically presents the solid-solid phase change characteristic.

  18. Shear bond strength of four resin cements used to lute ceramic core material to human dentin.

    Science.gov (United States)

    Altintas, Subutayhan; Eldeniz, Ayçe Unverdi; Usumez, Aslihan

    2008-12-01

    This study evaluated the effect of four resin cements on the shear bond strength of a ceramic core material to dentin. One hundred twenty molar teeth were embedded in a self-curing acrylic resin. The occlusal third of the crowns were sectioned under water cooling. All specimens were randomly divided into four groups of 30 teeth each according to the resin cement used. One hundred twenty cylindrical-shaped, 2.7-mm wide, 3-mm high ceramic core materials were heat-pressed. The core cylinders were then luted with one of the four resin systems to dentin (Super-Bond C&B, Chemiace II, Variolink II, and Panavia F). Half of the specimens (n = 15) were tested after 24 hours; the other half (n = 15) were stored in distilled water at 37 degrees C for 1 day and then thermocycled 1000 times between 5 degrees C and 55 degrees C prior to testing. Shear bond strength of each specimen was measured using a universal testing machine at a crosshead speed of 1 mm/min. The bond strength values were calculated in MPa, and the results were statistically analyzed using a two-way analysis of variance (ANOVA) and Tukey HSD tests. The shear bond strength varied significantly depending on the resin cement used (p 0.05). Significant interactions were present between resin cement and thermocycling (p 0.05). The increase in the shear bond strength values in the Panavia F (4.5 +/- 0.7 MPa) and Variolink II (5.5 +/- 2.1 MPa) groups after thermocycling was also not statistically significant (p > 0.05). Variolink II and Panavia F systems showed higher shear bond strength values than Chemiace II and Super-Bond C&B. They can be recommended for luting ceramic cores to dentin surfaces.

  19. Radiometric determinations of linear mass, resin levels and density of composite materials

    International Nuclear Information System (INIS)

    Boutaine, J.L.; Pintena, J.; Tanguy, J.C.

    1978-01-01

    A description is given of the principle, characteristics and performances of a gamma back-scattering gauge developed in cooperation between the CEA and SNPE. This instrument allows for on-line inspection of the linear mass and resin level of strips of composite materials whilst being produced. The industrial application involved boron, carbon and 'Kevlar' fibres. The performance of beta and gamma transmission gauges are also given for inspecting the density of panels and dense composite materials [fr

  20. In vitro evaluation of the bond strength of composite resin foundation materials to dentin.

    Science.gov (United States)

    Al-Ansari, Asim; Al-Harbi, Fahad; Baba, Nadim Z

    2015-10-01

    Achieving adequate bonding of composite resin foundation materials to dentin can be a challenge. Bonding can be affected by the type of bonding material and method used. The purpose of this in vitro study was to test the bond strengths of selected dual-polymerizing composite resin foundation materials to dentin using light, chemical, or dual-polymerized adhesive systems. Eighty freshly extracted human third molars were sectioned vertically into mesial and distal halves and embedded in acrylic resin using a copper cylinder. Specimens were divided into 16 groups. Each group received a resin foundation that was bonded to dentin according to each manufacturer's instructions. All tested foundations were dual polymerized except Tetric Ceram, which was light polymerized. BisCore, Build-it, CompCore, CoreRestore, and FluoroCore resin foundation materials were bonded to dentin with the use of the corresponding adhesives in 3 different bonding methods: adhesive was light polymerized; adhesive was chemically polymerized; and adhesive was dual polymerized. Each specimen was seated in a custom shear test device, and a load was applied with the descending rod of the jig from a mechanical testing machine with a perpendicular force to the dentin-adhesive interface. Statistical analysis was performed using 2-way ANOVA and post hoc pairwise comparison with Tukey test when statistically significant differences were found (α=.05). Resin foundation materials bonded to dentin with light-polymerized adhesives produced significantly higher bond strengths than when bonded with chemically or dual-polymerized adhesives. No significant difference was found between the single-component and multiple-components adhesives used with Tetric Ceram and BisCore foundations (P=.083). However, BisCore used with All-Bond 2 adhesive (multiple components) produced significantly lower bond strengths than when used with One-Step (P=.024). Adhesive failure was the most common failure location. Cohesive

  1. In vitro wear of resin-based materials--simultaneous corrosive and abrasive wear.

    Science.gov (United States)

    Correr, Gisele Maria; Bruschi Alonso, Roberta Caroline; Correr Sobrinho, Lourenço; Puppin-Rontani, Regina Maria; Ferracane, Jack Liborio

    2006-07-01

    The aim of this study was to evaluate the wear of resin-based materials caused by the association of abrasive and corrosive processes. Twenty specimens were prepared for each material, cast in epoxy in acrylic rings, polished, and profiled with an MTS 3D Profiler. Antagonists were made from deciduous molars. Specimens were distributed into eight groups (n = 10), according to the material (Filtek Supreme, Point 4, Dyract AP, and Fuji II LC) and the type of slurry (neutral and acidic), and then cycled 100,000 times in the OHSU oral wear simulator. The specimens were cleaned and reprofiled. Volume loss and maximum depth were determined. ANOVA and Tukey's test were used for data analysis (p wear facet on the antagonist was also measured. Composites displayed less wear than the compomer and the resin-modified glass ionomer. Significant differences also were found for cusp wear, with a significant positive correlation shown between cusp and material wear. The acidic slurry significantly increased the wear of the materials compared to the neutral slurry. Exposure to acidic slurry accelerated the wear of resin-based materials.

  2. Effectiveness of resin-based materials against erosive and abrasive enamel wear.

    Science.gov (United States)

    Zhao, Xiaoyi; Pan, Jie; Zhang, Songmei; Malmstrom, Hans S; Ren, Yan-Fang

    2017-01-01

    The objective of this study was to test the effectiveness of resin-based materials against erosive enamel wear under erosive and abrasive challenges by orange juice and tooth brushing. Fifty enamel specimens from third molars were assigned to five groups: ICON resin infiltration with no etching (ICON-NE), ICON resin infiltration with 15 % HCl etching (ICON-AE), Seal & Protect sealant (S&P), Tetric EvoFlow (TEF), and control. Erosive lesions were first created on enamel, then treated with resin-based materials. Erosive and abrasive challenges by orange juice and tooth brushing were repeated after treatments. Erosive wear of the treated areas was measured with 3D scanning microscopy, and data were analyzed using ANOVA and paired t tests. Treatments with ICON, S&P, and TEF created a protective material coating of 4.5 ± 1.9 μm, 44.3 ± 8.1 μm, and 84.6 ± 15.7 μm in thickness on the lesion surfaces, respectively. After 15 cycles of erosive and abrasive challenges, enamel or material losses were 21.9 ± 2.3 μm for control, 24.5 ± 4.0 μm for ICON-NE, 24.6 ± 7.4 μm for ICON-AE, 11.2 ± 4.1 μm for S&P, and 3.9 ± 1.9 μm for TEF, respectively. The protective coatings were completely lost in the ICON infiltration groups but remained intact in both the S&P and TEF groups after erosive and abrasive challenges. In contrast to a resin sealant and a flowable composite, ICON infiltration resin was not effective in protecting enamel surfaces from erosive and abrasive wear. Sealant and flowable composite resin may create protective coatings on eroded enamel surfaces and prevent further tissue loss.

  3. Fracture resistance of endodontically treated teeth restored with a bulkfill flowable material and a resin composite.

    Science.gov (United States)

    Isufi, Almira; Plotino, Gianluca; Grande, Nicola Maria; Ioppolo, Pietro; Testarelli, Luca; Bedini, Rossella; Al-Sudani, Dina; Gambarini, Gianluca

    2016-01-01

    To determine and compare the fracture resistance of endodontically treated teeth restored with a bulk fill flowable material (SDR) and a traditional resin composite. Thirty maxillary and 30 mandibular first molars were selected based on similar dimensions. After cleaning, shaping and filling of the root canals and adhesive procedures, specimens were assigned to 3 subgroups for each tooth type (n=10): Group A: control group, including intact teeth; Group B: access cavities were restored with a traditional resin composite (EsthetX; Dentsply-Italy, Rome, Italy); Group C: access cavities were restored with a bulk fill flowable composite (SDR; Dentsply-Italy), except 1.5 mm layer of the occlusal surface that was restored with the same resin composite as Group B. The specimens were subjected to compressive force in a material static-testing machine until fracture occurred, the maximum fracture load of the specimens was measured (N) and the type of fracture was recorded as favorable or unfavorable. Data were statistically analyzed with one-way analysis of variance (ANOVA) and Bonferroni tests (Presin composite and with a bulk fill flowable composite (SDR) was similar in both maxillary and mandibular molars and showed no significant decrease in fracture resistance compared to intact specimens. No significant difference was observed in the mechanical fracture resistance of endodontically treated molars restored with traditional resin composite restorations compared to bulk fill flowable composite restorations.

  4. Antibacterial properties of amalgam and composite resin materials used as cores under crowns.

    Science.gov (United States)

    Al Ghadban, A; Al Shaarani, F

    2012-06-01

    The Aim of this Study was to compare the bacterial growth in the bulk of both amalgam and fluoridated composite resin materials used as cores under crowns at core's surface (in the superficial area of the bulk) and depth levels. With 24 lower premolars, 12 of them were restored with metal posts and amalgam cores (group 1). The rest were restored with glass Fiber-reinforced Composite (FRC) posts and fluoridated composite resin cores (group 2). All specimens were covered with aluminium crowns cemented with resin cement, and then they were soaked in natural saliva for three months. Excoriations abraded from the superficial and the depth areas of the core materials were cultured under aerobic conditions on blood agar plates. After incubation for 2 days, colonies formed on the plates were identified, and the CFU mg(-1) counts were recorded accordingly. Statistical analysis was performed using an independent sample T test. The mean values of CFU mg(-1) counts in group 2 excoriations (surface 39.75, and depth 9.75) were higher than the group 1 excoriations (surface 1.67, and depth 0.42). This study supports the use of amalgam for building up cores due to its antibacterial properties. Composite resin, however, enhanced sizable bacterial growth despite the presence of fluoride.

  5. Rubber-like materials derived from biosourced phenolic resins

    Science.gov (United States)

    Amaral-Labat, G.; Grishechko, L. I.; Silva, G. F. B. Lenz e.; Kuznetsov, B. N.; Fierro, V.; Pizzi, A.; Celzard, A.

    2017-07-01

    The present work describes new gels derived from cheap, abundant and non-toxic wood bark extracts of phenolic nature, behaving like elastomers. Especially, we show that these materials might be used as rubber springs. Such amazing properties were obtained by a quite simple synthesis based on the autocondensation of flavonoid tannins in water at low pH in the presence of a plasticizer. After gelation and drying, the materials presented elastic properties that could be tuned from hard and brittle to quite soft and deformable, depending on the amount of plasticizer in the starting formulation. Not only the materials containing the relevant amount of plasticizer had stress-strain characteristics in quasi-static and cyclic compression similar to most commercial rubber springs, but they presented outstanding fire retardance, surviving 5 min in a flame at 1000°C in air. Neither flame propagation nor drips were noticed during the fire test, and the materials were auto-extinguishable. These excellent features make these materials potential substitutes to usual organic elastomers.

  6. Resole resin products derived from fractionated organic and aqueous condensates made by fast-pyrolysis of biomass materials

    Science.gov (United States)

    Chum, H.L.; Black, S.K.; Diebold, J.P.; Kreibich, R.E.

    1993-08-10

    A process for preparing phenol-formaldehyde resole resins by fractionating organic and aqueous condensates made by fast-pyrolysis of biomass materials while using a carrier gas to move feed into a reactor to produce phenolic-containing/neutrals in which portions of the phenol normally contained in said resins are replaced by a phenolic/neutral fractions extract obtained by fractionation.

  7. Radiopacity of different shades of resin-based restorative materials compared to human and bovine teeth.

    Science.gov (United States)

    Pekkan, Gurel; Ozcan, Mutlu

    2012-01-01

    This study evaluated the radiopacity of different shades of resin-based restorative materials and compared the results to human and bovine dental hard tissues. Disk specimens 6 mm in diameter and 1 mm thick (N = 220, n = 10) were prepared from the following restorative materials: · eight shades of nanofilled composite (Aelite Aesthetic Enamel), · seven shades of nanohybrid composite (Grandio Universal), · six shades of photopolymerized polyacid modified compomer (Glasiosite), and · one shade of hybrid composite (X-tra fil U). Human canine dentin (n = 10), bovine enamel (n = 10), and an aluminum (Al) step wedge were used as references. The optical density values of each material were measured from radiographic images using a transmission densitometer. Al step wedge thickness and optical density values were plotted, and equivalent Al thickness (eq Al) values were determined for radiopacity measurements of each material. The data were analyzed using a non-parametric one-way ANOVA (Kruskal-Wallis), and multiple comparisons were made with a Student-Newman-Keuls post hoc test (a = 0.05). Different shades of resin-based restorative materials tested did not reveal statistically significant differences within each material group (p > 0.05). Radiopacity values of the resin-based restorative materials investigated varied depending on their types; however, within different shades of one material type, radiopacity values were comparable. Every shade of nanocomposite material other than Aelite Aesthetic Enamel Incisal LT Gray showed comparable radiopacity to human dentin. Other materials tested demonstrated higher radiopacity compared to human dentin and bovine enamel.

  8. INFLUENCE OF ENVIRONMENTAL CONDITIONS ON PROPERTIES OF IONOMERIC AND RESIN SEALANT MATERIALS

    Science.gov (United States)

    Kantovitz, Kamila Rosamilia; Pascon, Fernanda Miori; Correr, Gisele Maria; Alonso, Roberta Caroline Bruschi; Rodrigues, Lidiany Karla Azevedo; Alves, Marcelo Correa; Puppin-Rontani, Regina Maria

    2009-01-01

    Objectives: The aim of this study was to determine the effect of environmental conditions on the degradation of ionomeric and resin sealant materials. Material and Methods: FluroShield, Vitremer, and Ketac Molar disc-shaped specimens (n=18/material) were prepared, polished, subjected to initial hardness and roughness readings. Six discs of each material were randomly assigned to one of three different storage solutions: 0.3% citric acid (CA), demineralization solution (DE), and remineralization solution (RE). The specimens were individually immersed in 3 mL of the test solutions, which were daily changed. After 15 days of storage, new surface roughness and hardness readings were done. Fluoride release in the solutions was measured within 15 days. Data were analyzed by ANOVA and Tukey's and Contrast tests (α=0.05). Results: The storage in CA increased the roughness of Vitremer and Ketac Molar. A significant reduction in hardness was observed for all materials after storage in all solutions. For all materials, the greatest amounts of fluoride release occurred during the 1st day. FluroShield presented the same patterns of fluoride release in all solutions. Ketac Molar and Vitremer released the highest amounts of fluoride in the CA solution. Conclusions: Ionomeric materials are more susceptible to degradation than resin-based materials under acidic conditions. Acidic conditions lead to a higher fluoride release from ionomeric materials. PMID:19668988

  9. Stickiness of dental resin composite materials to steel, dentin and bonded dentin.

    Science.gov (United States)

    Ertl, Kathrin; Graf, Alexandra; Watts, David; Schedle, Andreas

    2010-01-01

    Stickiness is a vital rheological parameter for the clinical handling behavior of unset resin composite restoratives. The aim of this study was to investigate the stickiness of three different resin composites at 23 degrees C and 37 degrees C tested on steel, dentin and dentin covered with different bonding agents. The stickiness instrument, used in this study consists of a vertical cylindrical stainless steel rod, with a flat circular end, and a platform with a cylindrical mold (diameter: 6.1mm, depth: 2.2mm). The test-material surface temperature and the speed of the rod can be modified. It moves slowly into the prepared mold which is filled with unset composite materials. The degree of stickiness is deducted from the height of the "elevation" the material forms when the plunger is withdrawn from the mold until the steelhead detaches itself from the composite. In this study, stickiness was tested directly to the steel plunger and to dentin slices (uncovered or covered with two different bonding agents) fixed to the plunger rod with a clamp. The coefficients of variation (CVs) were generally less than 0.10, indicating that the stickiness instrument offers an adequately reproducible way of testing stickiness. The tested composite materials varied significantly in stickiness. For all investigated materials a decrease of peak heights with increasing speed was found (for all three materials: psteel and least on bonded dentin. The order of stickiness of composites was not affected by testing the stickiness on the different materials. This method allows the characterization of composite resin materials stickiness to steel, as equivalent to dental steel instruments, and to bonded dentin as equivalent to the tooth cavity after preparation. An ideal material should have a sufficient difference between stickiness on steel and dentin so that it remains in the cavity and is not pulled back by the steel instrument.

  10. Method of extruding and packaging a thin sample of reactive material including forming the extrusion die

    International Nuclear Information System (INIS)

    Lewandowski, E.F.; Peterson, L.L.

    1985-01-01

    This invention teaches a method of cutting a narrow slot in an extrusion die with an electrical discharge machine by first drilling spaced holes at the ends of where the slot will be, whereby the oil can flow through the holes and slot to flush the material eroded away as the slot is being cut. The invention further teaches a method of extruding a very thin ribbon of solid highly reactive material such as lithium or sodium through the die in an inert atmosphere of nitrogen, argon or the like as in a glovebox. The invention further teaches a method of stamping out sample discs from the ribbon and of packaging each disc by sandwiching it between two aluminum sheets and cold welding the sheets together along an annular seam beyond the outer periphery of the disc. This provides a sample of high purity reactive material that can have a long shelf life

  11. Thermal conductivity of 2D nano-structured graphitic materials and their composites with epoxy resins

    OpenAIRE

    Mu, Mulan; Wan, Chaoying; McNally, Tony

    2017-01-01

    Abstract The outstanding thermal conductivity (λ) of graphene and its derivatives offers a potential route to enhance the thermal conductivity of epoxy resins. Key challenges still need to be overcome to ensure effective dispersion and distribution of 2D graphitic fillers throughout the epoxy matrix. 2D filler type, morphology, surface chemistry and dimensions are all important factors in determining filler thermal conductivity and de facto the thermal conductivity of the composite material. ...

  12. Biological Effects of Provisional Resin Materials on Human Dental Pulp Stem Cells.

    Science.gov (United States)

    Jun, S-K; Mahapatra, C; Lee, H-H; Kim, H-W; Lee, J-H

    This study investigated the in vitro cytotoxicity as well as the proinflammatory cytokine expression of provisional resin materials on primary cultured human dental pulp stem cells (hDPSCs). Five commercially available provisional resin materials were chosen (SNAP [SN], Luxatemp [LT], Jet [JE], Revotek LC [RL], and Vipi block [VB]). Eluates that were either polymerizing or already set were added to hDPSCs under serially diluted conditions divided into three different setting times (25% set, 50% set, and 100% set) and incubated for 24 hours with 2× concentrated culture media. Cell cytotoxicity tests were performed by LDH assay and live and dead confocal microscope images. The expression of proinflammatory cytokines in SN and VB was measured using cytokine antibody arrays. Data were analyzed using repeated measures analysis of variance (ANOVA) or ANOVA followed by the Tukey post hoc test at a significance level of pprovisional resin materials during polymerization (SN, LT, and JE) were cytotoxic to hDPSCs and may adversely affect pulp tissue.

  13. Properties of Two Carbon Composite Materials Using LTM25 Epoxy Resin

    Science.gov (United States)

    Cruz, Juan R.; Shah, C. H.; Postyn, A. S.

    1996-01-01

    In this report, the properties of two carbon-epoxy prepreg materials are presented. The epoxy resin used in these two materials can yield lower manufacturing costs due to its low initial cure temperature, and the capability of being cured using vacuum pressure only. The two materials selected for this study are MR50/LTM25, and CFS003/LTM25 with Amoco T300 fiber; both prepregs are manufactured by The Advanced Composites Group. MR50/LTM25 is a unidirectional prepreg tape using Mitsubishi MR50 carbon fiber impregnated with LTM25 epoxy resin. CRS003/LTM25 is a 2 by 2 twill fabric using Amoco T300 fiber and impregnated with LTM25 epoxy resin. Among the properties presented in this report are strength, stiffness, bolt bearing, and damage tolerance. Many of these properties were obtained at three environmental conditions: cold temperature/dry (CTD), room temperature/dry (RTD), and elevated temperature/wet (ETW). A few properties were obtained at room temperature/wet (RTW), and elevated temperature/dry (ETD). The cold and elevated temperatures used for testing were -125 F and 180 F, respectively. In addition, several properties related to processing are presented.

  14. Silicon carbide, a ceramic material for the pump technology?; Siliciumcarbid - eine Keramik fuer die Pumpentechnologie

    Energy Technology Data Exchange (ETDEWEB)

    Vitzthum, E. [CeramTec AG, Lauf (Germany). Marketing und Customer Service

    2000-12-01

    Pumping of gases and liquids makes extreme demands on sliding bearings and their seals, especially if the material to be pumped is corrosive or contains abrasive constituents. Wear and corrosion are important economic factors. They shorten the life of machines and systems and cause standstill times and repair cost. All this decides the profitability of pumps and the competitive strength of products. In view of all this, it becomes clear why optimal materials selection is a crucial points in pumps and pumping systems. [German] Beim Foerdern von Gasen und Fluessigkeiten werden extrem hohe Anforderungen an Gleitlager und Gleitringdichtungen in Pumpen gestellt, die im direkten Kontakt mit dem zu foerdernden Medium sind, besonders dann, wenn das Medium korrosiv ist oder abrasive Bestandteile enthaelt. Verschleiss und Korrosion sind wesentliche Wirtschaftsfaktoren. Sie bestimmen die Standzeit von Maschinen und Anlagen, verursachen Betriebsstillstandszeiten und Reparaturkosten. Diese entscheiden ueber die Rentabilitaet von Prozessen und die Wettbewerbsfaehigkeit von Produkten, was eine optimale Auswahl des Werkstoffs auch in Pumpen und Pumpenanlagen unerlaesslich macht. (orig.)

  15. Influence of Curing Light Attenuation Caused by Aesthetic Indirect Restorative Materials on Resin Cement Polymerization

    Science.gov (United States)

    Pick, Bárbara; Gonzaga, Carla Castiglia; Junior, Washington Steagall; Kawano, Yoshio; Braga, Roberto Ruggiero; Cardoso, Paulo Eduardo Capel

    2010-01-01

    Objectives: To verify the effect of interposing different indirect restorative materials on degree of conversion (DC), hardness, and flexural strength of a dual-cure resin cement. Methods: Discs (2 mm-thick, n=5) of four indirect restorative materials were manufactured: a layered glass-ceramic (GC); a heat-pressed lithium disilicate-based glass-ceramic veneered with the layered glass-ceramic (LD); a micro-hybrid (MH); and a micro-filled (MF) indirect composite resin. The light transmittance of these materials was determined using a double-beam spectrophotometer with an integrating sphere. Bar-shaped specimens of a dual-cure resin cement (Nexus 2/SDS Kerr), with (dual-cure mode) and without the catalyst paste (light-cure mode), were photoactivated through the discs using either a quartz-tungsten-halogen (QTH) or a light-emitting diode (LED) unit. As a control, specimens were photoactivated without the interposed discs. Specimens were stored at 37ºC for 24h before being submitted to FT-Raman spectrometry (n=3), Knoop microhardness (n=6) and three-point bending (n=6) tests. Data were analyzed by ANOVA/Tukey’s test (α=0.05). Results: MH presented the highest transmittance. The DC was lower in light-cure mode than in dual-cure mode. All restorative materials reduced the cement microhardness in light-cure mode. GC and LD with QTH and GC with LED decreased the strength of the cement for both activation modes compared to the controls. Curing units did not affect DC or microhardness, except when the dual-cure cement was photoactivated through LD (LED>QTH). Flexural strength was higher with QTH compared to LED. Conclusions: Differences in transmittance among the restorative materials significantly influenced cement DC and flexural strength, regardless of the activation mode, as well as the microhardness of the resin cement tested in light-cure mode. Microhardness was not impaired by the interposed materials when the resin cement was used in dual-cure mode. PMID:20613921

  16. A comparison of the accuracy of patterns processed from an inlay casting wax, an auto-polymerized resin and a light-cured resin pattern material

    Directory of Open Access Journals (Sweden)

    Praveen Rajagopal

    2012-01-01

    Conclusion: The resin pattern materials studied, undergo a significantly less dimensional change than the inlay waxes on prolonged storage. They would possibly be a better alternative to inlay wax in situations requiring high precision or when delayed investment (more than 1 h of patterns can be expected.

  17. Trends in material choice for posterior restorations in an Israeli dental school: composite resin versus amalgam.

    Science.gov (United States)

    Ben-Gal, Gilad; Weiss, Ervin I

    2011-12-01

    According to a recent American Dental Association survey, posterior composite resin restorations now outnumber amalgam restorations in the United States. Dental schools around the world vary considerably in the extent to which they teach the use of composite resins. We aimed to determine if there has been an increase in the placement of posterior composite restorations in an Israeli dental school and if faculty experience affects the type of posterior restoration placed. In this retrospective study, we recorded and analyzed all the restorations performed by undergraduate students in the last five academic years at the Hebrew University Hadassah School of Dental Medicine in Jerusalem. All clinical records of student treatments between 2004 and 2009 were screened, and direct restorations were registered. Out of 6,094 posterior restorations performed during the study period, 42.3 percent were made of composite resin, increasing from 36.8 percent in 2004-05 to 48.5 percent in 2008-09, an increase of 11.7 percent. When clinical instructors were asked to state their preference if they themselves were to undergo posterior restoration, similar results were obtained. Instructors with less than ten years' experience preferred posterior composite resin restorations in 54.8 percent of the hypothetical situations, compared with 37.2 percent preferred by instructors with ten years of experience or more. It appears that the use of composite resin was influenced mainly by the prevailing trend and was not based on scientific evidence. Dental faculties should define criteria, based on up-to-date clinical studies, for using new materials, taking into consideration differences among instructors regarding treatment concept.

  18. Influence of light-curing units and restorative materials on the micro hardness of resin cements

    Directory of Open Access Journals (Sweden)

    Kuguimiya Rosiane

    2010-01-01

    Full Text Available Aim: The aim of this study was to evaluate the effect of indirect restorative materials (IRMs and light-curing units (LCUs on the micro hardness of dual-cured resin cement. Materials and Methods: A total of 36 cylindrical samples (2 mm thick were prepared with dual-cured resin cement (Relyx ARC photo-activated with either a QTH (Optilight Plus for 40s or a LED (Radii light-curing unit for 65s. Photo-activation was performed through the 2-mm- thick IRMs and the samples were divided into six groups (n=6 according to the combination of veneering materials (without, ceramic and indirect resin and LCUs (QTH and LED. In the control group, the samples were light-cured with a QTH unit without the interposition of any restorative material. Vickers micro hardness test was performed on the top and bottom surfaces of each sample (load of 50 g for 15 secs. The data were statistically analyzed using a three-way ANOVA followed by Tukey x s post-hoc test ( P < 0.05. Results: There were no statistically significant differences on the top surface between the light curing-units ( P > 0.05; however, the LED provided greater hardness on the bottom surface when a ceramic material was used ( P < 0.05. The mean hardness in photo-activated samples, in which there was no interposition of indirect materials, was significantly greater ( P < 0.01. Conclusions: It may be concluded that the interposition of the restorative material decreased the micro hardness in the deeper cement layer. Such decrease, however, was lower when the ceramic was interposed and the cement light-cured with LED.

  19. New Anion-Exchange Resins for Improved Separations of Nuclear Materials

    International Nuclear Information System (INIS)

    Bartsch, Richard A.; Barr, Mary E.

    2001-01-01

    Improved separations of nuclear materials will have a significant impact upon a broad range of DOE activities. DOE-EM Focus Areas and Crosscutting Programs have identified improved methods for the extraction and recovery of radioactive metal ions from process, waste, and environmental waters as critical needs for the coming years. We propose to develop multifunctional anion-exchange resins that facilitate anion uptake by carefully controlling the structure of the anion receptor site. Our new ion-exchange resins interface the field of ion-specific chelating ligands with robust, commercial ion-exchange technology to provide materials which exhibit superior selectivity and kinetics of sorption and desorption. The following Focus Areas and Crosscutting Programs have described needs that would be favorably impacted by the new material: Efficient Separations and Processing - radionuclide removal from aqueous phases; Plutonium - Pu, Am or total alpha removal to meet regulatory requirement s before discharge to the environment; Plumes - U and Tc in groundwater, U, Pu, Am, and Tc in soils; Mixed Waste - radionuclide partitioning; High-Level Tank Waste - actinide and Tc removal from supernatants and/or sludges. The basic scientific issues which need to be addressed are actinide complex speciation along with modeling of metal complex/functional site interactions in order to determine optimal binding-site characteristics. Synthesis of multifunctionalized extractants and ion-exchange materials that implement key features of the optimized binding site, and testing of these materials, will provide feedback to the modeling and design activities. Resin materials which actively facilitate the uptake of actinide complexes from solution should display both improved selectivity and kinetic properties. The long-range implications of this research, however, go far beyond the nuclear complex. This new methodology of ''facilitated uptake'' could revolutionize ion-exchange technology

  20. Development of microwave absorbing materials prepared from a polymer binder including Japanese lacquer and epoxy resin

    Science.gov (United States)

    Iwamaru, T.; Katsumata, H.; Uekusa, S.; Ooyagi, H.; Ishimura, T.; Miyakoshi, T.

    Microwave absorption composites were synthesized from a poly urushiol epoxy resin (PUE) mixed with one of microwave absorbing materials; Ni-Zn ferrite, Soot, Black lead, and carbon nano tube (CNT) to investigate their microwave absorption properties. PUE binders were specially made from Japanese lacquer and epoxy resin, where Japanese lacquer has been traditionally used for bond and paint because it has excellent beauty. Japanese lacquer solidifies with oxygen contained in air's moisture, which has difficulty in making composite, but we improved Japanese lacquer's solidification properties by use of epoxy resin. We made 10 mm thickness composite samples and cut them into toroidal shape to measure permittivity, permeability, and reflection loss in frequencies ranging from 50 Hz to 20 GHz. Electric magnetic absorber's composites synthesized from a PUE binders mixed either with Soot or CNT showed significantly higher wave absorption over -27 dB than the others at frequencies around 18 GHz, although Japanese lacquer itself doesn't affect absorption. This means Japanese lacquer can be used as binder materials for microwave absorbers.

  1. [Color stability of ceromer of different thicknesses and resin adhesive materials of different types after accelerated aging].

    Science.gov (United States)

    Likai, Wang; Yanan, Liu; Yan, Zheng; Pingping, Li

    2015-04-01

    This study aims to investigate the color stability of ceromer with different thicknesses and different types of resin adhesive materials after accelerated aging and provide references for clinical application and selections. Nine groups of experimental samples were used, and each group contained five samples. We made joint samples with ceromer having three different thicknesses (1.00, 0.75, 0.50 mm) combined with three different resin adhesive materials (RelyX Veneer, RelyX Unicem, Filtek Z350 Flow), respectively. All samples were placed into Xenon Lamp Aging Instrument to implement accelerated aging. Spectrophotometer was used to measure the lightness (L*), red green color value (a*), and blue yellow color value (b*) of all samples before and after accelerated aging. The change of lightness (ΔL), red green color value (Δa), blue yellow color value (Δb), and color variation (ΔE) were also calculated. We investigated the influence of ceromer veneer thicknesses and resin adhesive material types on color variation by two-factor analysis of variance. The thickness and type factors showed significant influence on ΔE values, and exhibited interactions (P Ceromer veneer thickness and resin adhesive material types could affect the color stability of ceromer veneer and resin adhesive materials. The changes in lightness and color in ceromer veneer and resin adhesive materials are considered clinically acceptable after accelerated aging.

  2. Effects of LDEF flight exposure on selected polymer matrix resin composite materials

    Science.gov (United States)

    Slemp, Wayne S.; Young, Philip R.; Witte, William G., Jr.; Shen, James Y.

    1992-01-01

    The characterization of selected graphite fiber reinforced epoxy (934 and 5208) and polysulfone (P1700) matrix resin composites materials which received over five years and nine months of exposure to the low earth orbit (LEO) environment in experiment AO134 on the Long Duration Exposure Facility is reported. The changes in mechanical properties of ultimate tensile strength and tensile modulus for exposed flight specimens are compared to the three sets of control specimens. Marked changes in surface appearance are discussed, and resin loss is reported. The chemical characterization including infrared, thermal, and selected solution property measurements showed that the molecular structure of the polymetric matrix had not changed significantly in response to this exposure.

  3. Compilation of radiation damage test data. Pt. 2. Thermoset and thermoplastic resins, composite materials

    International Nuclear Information System (INIS)

    Tavlet, M.; Fontaine, A.; Schoenbacher, H.

    1998-01-01

    This catalogue summarizes radiation damage test data on thermoplastic and thermoset resins and composites. Most of them are epoxy resins used as insulator for magnet coils. Many results are also given for new engineering thermoplastics which can be used either for their electrical properties or for their mechanical properties. The materials have been irradiated either in a 60 Co source, up to integrated absorbed doses between 200 kGy and a few megagrays, at dose rates of the order of 1 Gy/s, or in a nuclear reactor at dose rates of the order of 50 Gy/s, up to doses of 100 MGy. The flexural strength, the deformation and the modulus of elasticity have been measured on irradiated and non-irradiated samples, according to the recommendations of the International Electrotechnical Commissions. The results are presented in the form of tables and graphs to show the effect of the absorbed dose on the measured properties. (orig.)

  4. Processes and materials for photovoltaic applications. Workshop; Verfahren und Materialien fuer die Photovoltaik. Workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    Solar energy will surely continue to be the most important renewable energy source. Since 1985, solar cell production has doubled every five years while the per unit price decreased continuously. This trend is expected to continue. Germany made important contributions both in the construction of new solar cell production plants and in the development of new PV materials and material combinations, as well as in technology and PV plant construction. The states of Thuringia and Saxony were significant contributors. In Thuringia, two solar cell production plants were constructed, while Saxon vacuum coating technology was used in nearly all new German production plants. This workshop presented the activities in Thuringia in Saxony. Contacts were to be established between partners from industry and research, joint projects were to be initiated, and society and politicians were to be informed on the success and new chances achieved. The workshop was held on the occasion of the termination of construction and the starting of experimental production of the ANTEC Solar GmbH factory at Rudisleben. [German] Im Mix der erneuerbaren Energien spielt die Solarenergie kuenftig wohl die wichtigste Rolle. Seit 1985 verdoppelt sich die Solarzellenproduktion in jeweils fuenf Jahren, gleichzeitig sank der Preis pro Leistungseinheit kontinuierlich. Dieser Trend wird weiter anhalten. Deutschland leistete in den letzten Jahren wichtige Beitraege zu dieser Entwicklung, sowohl beim Aufbau neuer Fertigungskapazitaeten fuer Solarzellen, als auch bei der Entwicklung neuer Photovoltaik-Materialien bzw. -Materialkombinationen und auf den Gebieten der Technologie und des Anlagenbaus. Der Anteil Thueringens und Sachsens an dieser positiven Entwicklung ist groesser als generell vermutet. In Thueringen entstanden zwei Unternehmen fuer die Solarzellenproduktion, der saechsische Vakuumbeschichtungs-Anlagenbau war am Aufbau fast aller neuen deutschen Fertigungsstaetten beteiligt. Auf dem Workshop werden

  5. Optical absorption of epoxy resin and its role in the laser ultrasonic generation mechanism in composite materials

    International Nuclear Information System (INIS)

    Stratoudaki, T.; Edwards, C.; Dixon, S.; Palmer, S.B.

    2003-01-01

    Epoxy resins are used in various applications and are essential to the fabrication of carbon fibre reinforced composite materials (CFRCs). This paper investigates laser generated ultrasound in epoxy resins using three different lasers, a TEA CO2, a Nd:YAG and a XeCl excimer. In these partially transparent materials the ultrasonic generation mechanism is directly related to the optical absorption depth which can therefore be measured directly from the ultrasonic waveforms using for example a Michelson interferometer as detector. The present work aims firstly to relate the observed amplitude of the longitudinal wave to the optical absorption depth of the epoxy and secondly to evaluate the role of the epoxy resin to the generation of the ultrasound in CFRCs. For the latter, comparative results of generation efficiency between the three wavelengths are presented and an attempt is made to understand the way that the resin matrix influences the generation mechanism of ultrasound in composite materials

  6. Color stability of denture acrylic resins and a soft lining material against tea, coffee, and nicotine.

    Science.gov (United States)

    Imirzalioglu, Pervin; Karacaer, Ozgul; Yilmaz, Burak; Ozmen Msc, Ilknur

    2010-02-01

    The purpose of this study was to investigate the effect of four solutions [saliva (control group), saliva+tea, saliva+coffee, saliva+nicotine] on the color of different denture base acrylic resins (heat-polymerized, injection-molded, autopolymerized) and a soft denture liner. Twenty specimens from each type of test material were prepared (2.5 mm diameter, 2 mm thickness). Five specimens from each test material (heat-polymerized, chemically polymerized, injection-molded acrylic resin, soft denture reliner) were stored in each solution in 37 degrees C in a dark environment. Colorimetric measurements were done on the 1st, 7th, and 30th days. Color differences among specimens immersed in saliva (control group), and staining solutions were evaluated over time. Data were statistically analyzed with one-way analysis of variance (ANOVA) (alpha= 0.05). ANOVA was followed by Tukey test to find which groups differed from each other. Significant color shifts occurred in heat-polymerized and injection-molded acrylic resins in coffee and in soft liner in nicotine over time (p 1). The color shift of soft liner in nicotine was significantly different than that of the remainder of the test materials in nicotine (p 0.05). The effect of staining solutions on the color of each test material in each session was perceivable by the human eye (DeltaE > 1); however, the color shifts of all test materials were clinically acceptable (DeltaE < 3.7) except for soft liner in nicotine, which was not clinically acceptable over time. Therefore, minimizing drinking of such beverages and use of tobacco, particularly when soft liner is applied, may be advantageous for denture wearers for long-term color stability.

  7. [Research on bond durability among different core materials and zirconia ceramic cemented by self-adhesive resin cements].

    Science.gov (United States)

    Xinyu, Luo; Xiangfeng, Meng

    2017-02-01

    This research estimated shear bond durability of zirconia and different substrates cemented by two self-adhesive resin cements (Clearfil SA Luting and RelyX U100) before and after aging conditioning. Machined zirconia ceramic discs were cemented with four kinds of core material (cobalt-chromium alloy, flowable composite resin core material, packable composite resin, and dentin) with two self-adhesive resin cements (Clearfil SA Luting and RelyX U100). All specimens were divided into eight test groups, and each test group was divided into two subgroups. Each subgroup was subjected to shear test before and after 10 000 thermal cycles. All factors (core materials, cements, and thermal cycle) significantly influenced bond durability of zirconia ceramic (P0.05); observed shear bond strength was significantly higher than those of other substrates (Presin core material, and packable composite resin than that of RelyX U100 (P0.05). Different core materials and self-adhesive resin cements can significantly affect bond durability of zirconia ceramic. 
.

  8. Edge chipping resistance and flexural strength of polymer infiltrated ceramic network and resin nanoceramic restorative materials.

    Science.gov (United States)

    Argyrou, Renos; Thompson, Geoffrey A; Cho, Seok-Hwan; Berzins, David W

    2016-09-01

    Two novel restorative materials, a polymer infiltrated ceramic network (PICN) and a resin nanoceramic (RNC), for computer-assisted design and computer-assisted manufacturing (CAD-CAM) applications have recently become commercially available. Little independent evidence regarding their mechanical properties exists to facilitate material selection. The purpose of this in vitro study was to measure the edge chipping resistance and flexural strength of the PICN and RNC materials and compare them with 2 commonly used feldspathic ceramic (FC) and leucite reinforced glass-ceramic (LRGC) CAD-CAM materials that share the same clinical indications. PICN, RNC, FC, and LRGC material specimens were obtained by sectioning commercially available CAD-CAM blocks. Edge chipping test specimens (n=20/material) were adhesively attached to a resin substrate before testing. Edge chips were produced using a 120-degree, sharp, conical diamond indenter mounted on a universal testing machine and positioned 0.1 to 0.7 mm horizontally from the specimen's edge. The chipping force was plotted against distance to the edge, and the data were fitted to linear and quadratic equations. One-way ANOVA determined intergroup differences (α=.05) in edge chipping toughness. Beam specimens (n=22/material) were tested for determining flexural strength using a 3-point bend test. Weibull statistics determined intergroup differences (α=.05). Flexural modulus and work of fracture were also calculated, and 1-way ANOVA determined intergroup differences (α=.05) RESULTS: Significant (Pmaterials for the 4 mechanical properties. Specifically, the material rankings were edge chipping toughness: RNC>LRGC=FC>PICN; flexural strength: RNC=LRGC>PICN>FC; flexural modulus: RNCLRGC=PICN>FC. The RNC material demonstrated superior performance for the mechanical properties tested compared with the other 3 materials. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All

  9. How much do resin-based dental materials release? A meta-analytical approach.

    Science.gov (United States)

    Van Landuyt, K L; Nawrot, Tim; Geebelen, B; De Munck, J; Snauwaert, J; Yoshihara, K; Scheers, Hans; Godderis, Lode; Hoet, P; Van Meerbeek, B

    2011-08-01

    Resin-based dental materials are not inert in the oral environment, and may release components, initially due to incomplete polymerization, and later due to degradation. Since there are concerns regarding potential toxicity, more precise knowledge of the actual quantity of released eluates is necessary. However, due to a great variety in analytical methodology employed in different studies and in the presentation of the results, it is still unclear to which quantities of components a patient may be exposed. The objective of this meta-analytical study was to review the literature on the short- and long-term release of components from resin-based dental materials, and to determine how much (order of magnitude) of those components may leach out in the oral cavity. Out of an initial set of 71 studies, 22 were included. In spite of the large statistical incertitude due to the great variety in methodology and lack of complete information (detection limits were seldom mentioned), a meta-analytical mean for the evaluated eluates was calculated. To relate the amount of potentially released material components with the size of restorations, the mean size of standard composite restorations was estimated using a 3D graphical program. While the release of monomers was analyzed in many studies, that of additives, such as initiators, inhibitors and stabilizers, was seldom investigated. Significantly more components were found to be released in organic than in water-based media. Resin-based dental materials might account for the total burden of orally ingested bisphenol A, but they may release even higher amounts of monomers, such as HEMA, TEGDMA, BisGMA and UDMA. Compared to these monomers, similar or even higher amounts of additives may elute, even though composites generally only contain very small amounts of additives. A positive correlation was found between the total quantity of released eluates and the volume of extraction solution. There is a clear need for more accurate

  10. New anion-exchange resins for improved separations of nuclear materials

    International Nuclear Information System (INIS)

    Barr, M.E.; Bartsch, R.A.

    1998-01-01

    'The overall objective of this research is to develop a predictive capability which allows the facile design and implementation of multi-functionalized anion-exchange materials which selectively sorb metal complexes of interest from targeted process, waste, and environmental streams. The basic scientific issues addressed are actinide complex speciation along with modeling of the metal complex/functional-site interactions in order to determine optimal binding-site characteristics. The new ion-exchange resins interface the rapidly developing field of ion-specific chelating ligands with robust, commercial ion-exchange technology. Various Focus Areas and Crosscutting Programs have described needs that would be favorably impacted by the new materials: Efficient Separations and Processing; Plutonium; Plumes; Mixed Waste; High-Level Tank Waste. Sites within the DOE complex which would benefit from the improved anion-exchange technology include Hanford, INEL, Los Alamos, Oak Ridge, and Savannah River. As of April 1998, this report summarizes work after 1.6 years of a 3-year project. The authors technical approach combines empirical testing with theoretical modeling (applied in an iterative mode) in order to determine optimal binding-site characteristics. They determine actinide-complex speciation in specific media, then develop models for the metal complex/functional-site interactions Synthesis and evaluation of multi-functionalized extractants and ion-exchange materials that implement key features of the optimized binding site provide feedback to the modeling and design activities. Resin materials which actively facilitate the uptake of actinide complexes from solution should display both improved selectivity and kinetic properties. The implementation of the bifunctionality concept involves N-derivatization of pyridinium units from a base poly(4-vinylpyridine) resin with a second cationic site such that the two anion-exchange sites are linked by spacer arms of varying

  11. Thermal conductivity of 2D nano-structured graphitic materials and their composites with epoxy resins

    Science.gov (United States)

    Mu, Mulan; Wan, Chaoying; McNally, Tony

    2017-12-01

    The outstanding thermal conductivity (λ) of graphene and its derivatives offers a potential route to enhance the thermal conductivity of epoxy resins. Key challenges still need to be overcome to ensure effective dispersion and distribution of 2D graphitic fillers throughout the epoxy matrix. 2D filler type, morphology, surface chemistry and dimensions are all important factors in determining filler thermal conductivity and de facto the thermal conductivity of the composite material. To achieve significant enhancement in the thermal conductivity of epoxy composites, different strategies are required to minimise phonon scattering at the interface between the nano-filler and epoxy matrix, including chemical functionalisation of the filler surfaces such that interactions between filler and matrix are promoted and interfacial thermal resistance (ITR) reduced. The combination of graphitic fillers with dimensions on different length scales can potentially form an interconnected multi-dimensional filler network and, thus contribute to enhanced thermal conduction. In this review, we describe the relevant properties of different 2D nano-structured graphitic materials and the factors which determine the translation of the intrinsic thermal conductivity of these 2D materials to epoxy resins. The key challenges and perspectives with regard achieving epoxy composites with significantly enhanced thermal conductivity on addition of 2D graphitic materials are presented.

  12. Bonding of resin to dentin. Interactions between materials, substrate and operators.

    Science.gov (United States)

    Jacobsen, Thomas

    2003-01-01

    The general aim of this thesis was to identify and study factors that affect bonding between resin and dentin, including operator variability. Bonding sites were generated in vivo and in vitro and compared using SEM. The effects of experimental water- or acetone-based primers on shear bond strength to dentin were studied in vitro. Fourier transform infrared spectroscopy was used to establish any detrimental effects from water on polymerization by determining the degree of conversion of thin films of resin. The interaction between phosphoric acid and dentin was analyzed by measuring calcium leaching by use of atomic absorption spectroscopy. Bond strength of composite resin was measured to dentin with various degrees of demineralization. Gap formation adjacent to composite restorations in standardized dentin cavities was studied in vitro by confocal microscopy. A similar morphological appearance was found for bonding sites generated in vitro vs. in vivo. An acetone-based primer was more dependent on a moist bonding technique than was a water-based system. However, water might influence bonding by interfering with the polymerization of the resin. Calcium leaching from dentin can be predicted by use of a solubility phase diagram. No correlation could be established between calcium leaching and bond strength. Gap formation was more dependent on the operator than the choice of material. A simplified all-in-one adhesive showed less operator variability compared to more complex bonding systems. In vitro bond testing may well indicate the outcome of in vivo trials. The solvents used in bonding agents will influence the performance and, presumably, technique sensitivity. Water rinse time after etching might be a more important consideration than etch time. In spite of the relative importance of the results presented above, the outcome of the multi-operator trial could not be predicted.

  13. Technologies of bearings systems production from composite materials by polyester resin injection into the closed mold

    Directory of Open Access Journals (Sweden)

    Аnatoliy M. Turenko

    2014-12-01

    Full Text Available An analysis of modern technologies for manufacturing components and bearing systems made of composite materials has been conducted. These technologies are based on the polyester resin injection method and do not require high financial costs in manufacturing. The proposed method, due to the low cost of tooling, is convenient to produce a wide range of items made of composite materials, both in large-scale and single-piece production. Composite materials are intensively used in automotive industry, especially for motor racing vehicles’ parts. These technologies allow to solve the problem of creating ultra-light assemblies for modern car bodies, energy-absorbing passive safety elements and other high-loaded parts. They provide better strength and weight characteristics and better specific energy-output ratio of passive safety elements, as compared to conventional materials (metals and plastics. Considering the above, the most appropriate technology for the automotive industry has been assessed with that choice substantiation.

  14. Optimal Composite Material for Low Cost Fabrication of Large Composite Aerospace Structures using NASA Resins or POSS Nanoparticle Modifications

    Science.gov (United States)

    Lamontia, Mark A.; Gruber, Mark B.; Jensen, Brian J.

    2006-01-01

    Thermoplastic laminates in situ consolidated via tape or tow placement require full mechanical properties. Realizing full properties requires resin crystallinity to be controlled - partial crystallinity leads to unacceptably low laminate compression properties. There are two approaches: utilize an amorphous matrix resin; or place material made from a semi-crystalline resin featuring kinetics faster than the process. In this paper, a matrix resin evaluation and trade study was completed with commercial and NASA amorphous polyimides on the one hand, and with PEKK mixed with POSS nanoparticles for accelerated crystallinity growth on the other. A new thermoplastic impregnated material, 6 mm wide (0.25-in) AS-4 carbon/LaRC(TradeMark)8515 dry polyimide tow, was fabricated. Since LaRC(TradeMark)8515 is fully amorphous, it attains full properties following in situ consolidation, with no post processing required to build crystallinity. The tow in situ processing was demonstrated via in situ thermoplastic filament winding it into rings.

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

    Science.gov (United States)

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

    2015-10-01

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

  16. Are linear elastic material properties relevant predictors of the cyclic fatigue resistance of dental resin composites?

    Science.gov (United States)

    Belli, Renan; Petschelt, Anselm; Lohbauer, Ulrich

    2014-04-01

    The aim of this study was to measure the linear elastic material properties of direct dental resin composites and correlate them with their fatigue strength under cyclic loading. Bar specimens of twelve resin composites were produced according to ISO 4049 and tested for elastic modulus (Emod) in 3-point bending (n=10), flexural strength (FS) (n=15) and single-edge-notch-beam fracture toughness (FT) (n=15), both in 4-point bending. Using the same specimen geometry, the flexural fatigue strength (FFS) was determined using the staircase approach after 10(4) cycles at 0.5 Hz in 4-point bending (n=25). The observation of the fracture surface and fracture profiles was conducted using a scanning electron microscope in order to evaluate the respective fracture mechanisms according to the two different loading conditions. Materials were ranked differently according to the tested parameters. Only weak correlations were found between any of the initial properties and FFS or strength loss. The best correlation to FFS was found to be the Emod (r(2)=0.679), although only slightly. Crack path in both loading conditions was mainly interparticle, with the crack propagating mainly within the matrix phase for fatigued specimens and eventually through the filler/matrix interface for statically loaded specimens. Fracture of large particles or prepolymerized fillers was only observed in specimens of FS and FT. Initial properties were better associated with microstructural features, whereas the fatigue resistance showed to be more dependent on aspects relating to the matrix phase. Our results show that linear elastic properties such as elastic modulus, flexural strength and fracture toughness are not good descriptors of the fatigue resistance of dental resin composite under cyclic bending, and may therefore have limited clinical relevance. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  17. Removal of radioactive materials and heavy metals from water using magnetic resin

    Science.gov (United States)

    Kochen, Robert L.; Navratil, James D.

    1997-01-21

    Magnetic polymer resins capable of efficient removal of actinides and heavy metals from contaminated water are disclosed together with methods for making, using, and regenerating them. The resins comprise polyamine-epichlorohydrin resin beads with ferrites attached to the surfaces of the beads. Markedly improved water decontamination is demonstrated using these magnetic polymer resins of the invention in the presence of a magnetic field, as compared with water decontamination methods employing ordinary ion exchange resins or ferrites taken separately.

  18. Mechanical and Physical Properties of Two Different Resin-based Materials: A Comparative Study.

    Science.gov (United States)

    Baeshen, Hosam; Alturki, Basem N; Albishi, Wjoud W; Alsadi, Fahad M; El-Tubaigy, Khaled M

    2017-10-01

    The purpose of this study was to evaluate the degree of conversion (DC) of two different resin-based composite materials (nanofill composite and ormocer) and correlate it with some mechanical properties of these two restorative materials. Two different resin-based materials (Filtek Supreme XT and Admira) were tested. A total of 30 samples of each type of selected composite were prepared. Specimens were immersed in distilled water for 24 hours. Then, the specimens were subjected to DC, hardness, and diametral tensile strength (DTS) measurements. The data obtained were tabulated for statistical analysis. The t-test was used to detect the significant difference among the variables tested in this study. Furthermore, the interrelationship between the studied parameters was investigated using a simple correlation coefficient statistical test. Statistically significant differences were observed regarding DC, hardness, and DTS. Filtek Supreme XT presented the highest values. There was a positive correlation between DC and hardness. Also there was a correlation between DC and DTS, but it was not significant. Under the tested experimental conditions, the DC of Filtek Supreme XT was higher than that of ormocer. Accordingly, Filtek Supreme XT showed better mechanical properties. Filtek Supreme XT showed superior mechanical properties. Therefore, orthodontic bracket-based composite combinations may also be expected to perform well clinically over the lifetime of a bonded orthodontic appliance.

  19. A Study of Resin as Master Jewellery Material, Surface Quality and Machining Time Improvement by Implementing Appropriate Cutting Strategy

    Directory of Open Access Journals (Sweden)

    Puspaputra Paryana

    2017-01-01

    Full Text Available This paper deals with a research about art and jewellery product machining that focused in the selection of appropriate material for jewellery master which is machined by CNC. CNC is used for better surface finish for no undercut design and more complex ornament. The need of production speed requires minimum process without reducing the quality of detail ornament significantly. Problems occur when high surface quality is required. In that condition high speed spindle is used with low feeding speed, as a result is high temperature in cutter-material area will melt the resin and build the build-up edge (BUE. Due to the existence of BUE, the cutting tool will no longer cut the resin, as a result the resin will then melt due to friction and the melt resin will then stuck on the relief and surface finish become worst and rework should be done. When required surface is achieved problem also occur in next going process, that is silicon mould making. Due to galvanization process for silicon at about 170°C, resin material may be broken or cracked. Research is then conducted to select appropriate resin type suitable for all production steps.

  20. Pressure transmission area and maximum pressure transmission of different thermoplastic resin denture base materials under impact load.

    Science.gov (United States)

    Nasution, Hubban; Kamonkhantikul, Krid; Arksornnukit, Mansuang; Takahashi, Hidekazu

    2018-01-01

    The purposes of the present study were to examine the pressure transmission area and maximum pressure transmission of thermoplastic resin denture base materials under an impact load, and to evaluate the modulus of elasticity and nanohardness of thermoplastic resin denture base. Three injection-molded thermoplastic resin denture base materials [polycarbonate (Basis PC), ethylene propylene (Duraflex), and polyamide (Valplast)] and one conventional heat-polymerized acrylic resin (PMMA, SR Triplex Hot) denture base, all with a mandibular first molar acrylic resin denture tooth set in were evaluated (n=6). Pressure transmission area and maximum pressure transmission of the specimens under an impact load were observed by using pressure-sensitive sheets. The modulus of elasticity and nanohardness of each denture base (n=10) were measured on 15×15×15×3mm 3 specimen by using an ultramicroindentation system. The pressure transmission area, modulus of elasticity, and nanohardness data were statistically analyzed with 1-way ANOVA, followed by Tamhane or Tukey HSD post hoc test (α=.05). The maximum pressure transmission data were statistically analyzed with Kruskal-Wallis H test, followed by Mann-Whitney U test (α=.05). Polymethyl methacrylate showed significantly larger pressure transmission area and higher maximum pressure transmission than the other groups (Pdenture bases (Pthermoplastic resin denture base materials. Differences in the modulus of elasticity and nanohardness of each type of denture base were demonstrated. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  1. Studi Eksperimental Laju Keausan Material Gigi Tiruan dari Resin Akrilik Berpenguat Fiberglass dengan Variasi Susunan Serat Penguat

    Directory of Open Access Journals (Sweden)

    Prastika Kristasari

    2017-01-01

    Full Text Available Resin akrilik adalah salah satu material yang mulai banyak digunakan sebagai salah satu material untuk pembuatan gigi tiruan. Penelitian sebelumnya tentang analisis pengujian laju keausan resin akrilik berpenguat serat pada dental prosthesis pada kondisi dry sliding menunjukkan hasil nilai laju keausan berkurang dengan adanya penambahan serat[1]. Saat ini belum ada kajian mengenai laju keausan resin akrilik berpenguat serat pada kondisi wet sliding dengan variasi pola susunan serat yang berbeda dengan kondisi terendam cairan saliva buatan. Metode pengujian ekperimental ini menggunakan alat uji keausan tribometer tipe pin on disk.  Material untuk pin dan disk menggunakan material dari resin akrilik berpenguat serat. Disk diputar dan bergesekan dengan pin. Variabel tetap pengujian ini yaitu panjang lintasan sejauh 505,92 m, beban sebesar 2 kg, dan sliding speed sebesar 0,07 m/s. Perlakuan gesekan dilakukan pada resin akrilik berpenguat serat dengan variasi susunan serat 0%, 7% berpola 6 mm serat acak, dan 7% berpola 6 mm serat teratur. Spesimen direndam dahulu dan saat pengujian keausan dikondisikan terendam dalam cairan saliva buatan. Kemudian, spesimen tersebut dianalisis laju keausannya dan diamati gambar mikro dari permukaan spesimen. Hasil dari penelitian adalah data pengujian berupa nilai laju keausan spesifik terbesar sebesar 0.0126 mm3/Nm yang terdapat pada material resin akrilik tanpa penguat serat dan nilai laju keausan yang terkecil yaitu pada material resin akrilik berpenguat 7% serat berpola teratur sebesar 0.0006 mm3/Nm. Hasil foto mikro menunjukkan bahwa mekanisme keausan yang paling dominan terjadi adalah keausan abrasif dan keausan fatigue.

  2. Rheological analysis of the phenolic and furfuryl resins used in the carbon materials processing

    Directory of Open Access Journals (Sweden)

    Edson Cocchieri Botelho

    2000-04-01

    Full Text Available Carbon materials processing is an advanced technology due to its aerospace and medical applications. In the aerospace area one can mention the carbon/carbon composites used in rockets and aeronautical brakes; in the medical area one can mention the intrabody implant tools such as heart and hydrocephalic valves and pacemaker electrode tips. The highly sophisticated purpose of its application requires a very tight processing control, which defines the microstructure the mechanical, thermal and electrical characteristics of the final material. The objective of this study is to correlate rheological, chromatographic and thermal analysis of phenolic and furfuryl resins, aiming their use as raw materials in carbon/carbon composite and glassy carbon processing. The obtained results are correlated and used directly in the establishment of the adequate parameters for carbon reinforcement impregnation and to prepare glassy carbon samples with controlled porosity.

  3. Are flowable resin-based composites a reliable material for metal orthodontic bracket bonding?

    Science.gov (United States)

    Pick, Bárbara; Rosa, Vinícius; Azeredo, Tatiana Rocha; Cruz Filho, Eduardo Augusto Mascarenhas; Miranda, Walter Gomes

    2010-07-01

    To compare the tensile bond strength (TBS) and adhesive remnant index (ARI) of three flowable resin-based composites and three orthodontic adhesive systems for metal bracket bonding. Sixty bovine incisors were randomly divided into six groups. Enamel surfaces were etched with 37 percent phosphoric acid for 30 seconds and stainless steel orthodontic brackets were bonded using either flowable resin-based composites (3M Flow, FL; Tetric Flow, TF; and Wave, WA) or orthodontic bonding systems (Transbond XT, TX; Concise Orthodontic, CO; Fill Magic Ortodôntico, FM). All specimens were thermal cycled and stored in distilled water at 37°C for 24 hours, after which they were subsequently tested for TBS using a universal testing machine. ARI scores were determined after the failure of brackets. TBS and ARI data were submitted to ANOVA, Tukey, and Kruskal-Wallis tests (p=0.05), respectively. Rankings of the resin-based composites based on TBS means (MPa) were TX (6.4 ± 2.1), followed by CO (4.5 ± 2.7), FM (3.7 ± 1.2), FL (3.6 ± 1.2), TF (3.3 ± 1.2), and WA (2.4 ± 0.6). CO exhibited the lowest ARI mean score (0.9 ± 1.2) which was significantly different from the other five materials: TX (2.8 ± 0.42), FM (2.8 ± 0.42), FL (2.9 ± 0.32), TF (2.9 ± 0.32), and WA (3.0 ± 0.01). However, there were no statistically significant differences among the other groups with mean scores of 2.8-3.0. A score of 3.0 indicated that all the resin remained bonded to the tooth surface. The flowable resin-based composites tested (Fl, TF, and WA) used to bond metal orthodontic brackets to bovine enamel had low mean TBS values but acceptable ARI mean scores. Flowable composites may not be appropriate for bracket bonding, unless the teeth to be bonded are not subjected to higher orthodontic stresses, such as those without an antagonist.

  4. A practice-based evaluation of the handling of a new self-adhesive universal resin luting material.

    Science.gov (United States)

    Burke, F J Trevor; Crisp, Russell J; Richter, B

    2006-06-01

    Ease of handling of materials may be considered helpful to achieving good results. The handling properties of a new self-adhesive universal resin luting material were tested in clinical use. Thirteen practitioners were selected at random from the Product Research and Evaluation by Practitioners (PREP) Panel, a United Kingdom-based group of dental practitioners prepared to complete evaluations of new materials and techniques in the practice environment. Explanatory letters, questionnaires and packs of the luting material were sent to the evaluators. The practitioners were asked to use the material and return the questionnaire. 144 restorations were placed using the new self-adhesive resin luting material, which was rated higher by the evaluators for ease of use (4.7 on a visual analogue scale where 5 represented easy to use and 1 represented difficult to use) than both the pre-trial resin-based and 'conventional' luting materials (rated 3.7 and 4.4 respectively on the same scale). The presentation, instructions, convenience of dispensing and handling and viscosity also received high ratings. The new material achieved ratings for ease of use superior to the pre-study resin-based and conventional luting materials in the dental practices of 13 UK dental practitioners.

  5. High irradiance curing and anomalies of exposure reciprocity law in resin-based materials.

    Science.gov (United States)

    Hadis, M; Leprince, J G; Shortall, A C; Devaux, J; Leloup, G; Palin, W M

    2011-08-01

    The aim of this work was to investigate the effect of high irradiance curing on resultant degree of conversion of 'flowable' resin composites and their counterpart higher viscosity paste materials. Five commercial flowable materials (Venus; Heraeus Kulzer, Synergy D6; Coltene, Premise; Kerr, Grandio; Voco and Gradia; GC Corp) and their counterpart higher viscosity restorative versions were tested. Specimens were cured with a halogen Swiss Master Light (EMS, Switzerland) using five different curing protocols with similar radiant exposure (18J/cm(2)): 400mW/cm(2) for 45s, 900mW/cm(2) for 20s, 1500mW/cm(2) for 12s, 2000mW/cm(2) for 9s and 3000mW/cm(2) for 6s. Degree of conversion (DC) was measured in real time by Fourier transform near infrared spectroscopy (FT-NIRS). Three- and subsequent two way ANOVA testing revealed significant differences (p≤0.02) with respect to "composite type" and "cure protocol" for DC for all 5 product comparisons. Supplementary one-way ANOVA also revealed significant differences between curing protocols (pGrandio (41±0.36 and 62±1.15%, respectively) and Venus (44±0.44 and 67±0.44%, respectively). Conversely, other flowable materials exhibited little or no significant differences between curing modes. Generally, a higher degree of conversion was observed for flowables compared with their more viscous counterpart, except at high irradiance for those materials where a reciprocal relationship with exposure time was not observed. The validity of exposure reciprocity law and final degree of conversion depends on several factors, amongst which resin viscosity and filler content were important. Practitioners should be aware of the importance of resin composite constituents and irradiation protocols. Information on material composition and appropriate radiation sources by manufacturers may assist practitioners with the selection of appropriate curing protocols for specific material/light curing unit combinations with the aim of reducing the

  6. Evaluation of ABS resin disk certified reference materials for heavy metal analysis by x-ray fluorescence analysis

    International Nuclear Information System (INIS)

    Ohata, Masaki; Kidokoro, Toshihiro; Kurahashi, Masayasu; Hioki, Akiharu

    2010-01-01

    ABS resin disk certified reference materials (CRMs) for heavy-metal analysis (NMIJ CRM 8105-a, NMIJ CRM 8106-a, NMIJ CRM 8115-a and NMIJ CRM 8116-a) were evaluated using an energy dispersive X-ray fluorescence (ED-XRF) analysis. The homogeneities of elements for both among-disks and within-disk were evaluated by ED-XRF analysis without any sample pre-treatment, which were similar to those evaluated by ICP-MS analysis after a sample digenstion procedure. The normalized XRF sensitivities for Cd, Cr and Pb in different ABS resin disk CRMs were compared, and the differences among them for those ABS resin disks that have similar matrices were observed. Moreover, Hg in those ABS resin disk CRMs was stable for long-term X-ray irradiation during ED-XRF analysis. (author)

  7. Use of Resin-Based Provisional Material to Create the Posterior Palatal Seal in Complete Denture Definitive Impressions.

    Science.gov (United States)

    de Souza Batista, Victor Eduardo; Vechiato-Filho, Aljomar José; Pellizzer, Eduardo Piza; Verri, Fellippo Ramos

    2017-11-17

    The purpose of this article was to present an alternative procedure using resin-based provisional material to create the posterior palatal seal (PPS). This method offers more practicality in clinical routine and increased control for addition of material to create the PPS when compared to traditional techniques such as the use of impression wax. © 2017 by the American College of Prosthodontists.

  8. The impact of resin-coating on sub-critical crack extension in a porcelain laminate veneer material.

    Science.gov (United States)

    Cao, Xu; Fleming, Garry J P; Addison, Owen

    2017-05-01

    Characterisation of the interaction between crack extension, crack stabilisation and stress/strain relaxation in the polymeric matrix, the interplay between stress corrosion cracking and the mechanical response of a resin-based luting adhesive within a surface defect population could extend PLV restoration longevity by optimising cementation protocols. The aim was to investigate the influence of stress corrosion cracking and the viscoelastic behaviour of a resin-based luting adhesive independently by controlling the environmental conditions operative during test specimen fabrication. The effects of stress corrosion at ceramic crack tips and potential viscoelastic responses to loading of the resin-coated impregnating cracks were isolated. Resin-coated feldspathic ceramic test specimens were fabricated in ambient humidity or following moisture exclusion. Bi-axial flexure strengths of groups (n = 20) were determined at constant loading rates of 2.5, 10, 40, 160 or 640 N/min and data was compared with uncoated controls. Fractographic analyses were performed on all fractured test specimens. Resin-cement coating resulted in significant ceramic strengthening in all conditions tested (p resin- coating significantly increased mean BFS (ptests identified that moisture exclusion resulted in significant increases in BFS values only at intermediate loading rates with no significant differences observed at either the fastest or slowest loading rates (640 and 2.5 N/min, respectively). Mechanical reinforcement of PLV materials by resin-cement systems is yet to be optimized. The viscoelastic behavior of the resin-cement itself can influence the magnitude of reinforcement observed and sub-critical crack growth. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  9. Low Temperature Mechanical Testing of Carbon-Fiber/Epoxy-Resin Composite Materials

    Science.gov (United States)

    Nettles, Alan T.; Biss, Emily J.

    1996-01-01

    The use of cryogenic fuels (liquid oxygen and liquid hydrogen) in current space transportation vehicles, in combination with the proposed use of composite materials in such applications, requires an understanding of how such materials behave at cryogenic temperatures. In this investigation, tensile intralaminar shear tests were performed at room, dry ice, and liquid nitrogen temperatures to evaluate the effect of temperature on the mechanical response of the IM7/8551-7 carbon-fiber/epoxy-resin system. Quasi-isotropic lay-ups were also tested to represent a more realistic lay-up. It was found that the matrix became both increasingly resistant to microcracking and stiffer with decreasing temperature. A marginal increase in matrix shear strength with decreasing temperature was also observed. Temperature did not appear to affect the integrity of the fiber-matrix bond.

  10. Mechanical properties of resin-ceramic CAD-CAM materials after accelerated aging.

    Science.gov (United States)

    Blackburn, Caleb; Rask, Hailee; Awada, Abdallah

    2017-11-29

    The development of polymer-based computer-aided design and computer-aided manufacturing (CAD-CAM) milling bocks and the limited availability of independent studies on these materials make it pertinent to evaluate changes in their mechanical properties after simulated aging to identify strengths and limitations. The purpose of this in vitro study was to measure the effect of thermocycling on the flexural properties of ceramic, resin, and resin-ceramic CAD-CAM materials. Studied materials included Lava Ultimate Restorative (LVU; 3M ESPE), Enamic (ENA; VITA Zahnfabrik), Vitablocs Mark II (VM2; VITA Zahnfabrik), and Paradigm MZ100 (MZ1; 3M ESPE). Polished 4×1.2×14 mm bars (n=45 per material) were prepared from standard-size milling blocks. The 2 distilled water baths of the thermocycling apparatus were set to 5°C and 55°C, with a specimen immersion time of 15 seconds and transfer time of 4 seconds. Fifteen specimens from each material group were subjected to a 3-point flexural test at 3 different thermocycling intervals: 0 (control), 5000, and 10 000 cycles. The flexural test was performed over a 12-mm span with a crosshead speed of 0.5 mm/min. Data were subjected to multiple analyses of variance and the Tukey HSD post hoc tests (α=.05). Mean flexural strength values for 0, 5000, and 10 000 cycles were 133, 130, and 128 MPa for VM2; 175, 139, and 134 MPa for LVU; 154, 144, and 138 MPa for MZ1; and 149, 136, and 132 MPa for ENA. Mean flexural modulus values were 51, 52, and 54 GPa for VM2; 14, 13, and 13 GPa for LVU; 16, 15, and 15 GPa for MZ1; and 31, 30, and 31 GPa for ENA. Mean modulus of resilience values were 0.17, 0.16, and 0.15 MPa for VM2; 10.1, 0.76, and 0.72 MPa for LVU; 0.77, 0.69, and 0.62 MPa for MZ1; and 0.42, 0.31, and 0.28 MPa for ENA. A significant difference was found among the materials in the mean change of flexural strength (P<.001) and modulus of resilience (P<.05) after thermocycling. No significant difference was found among the

  11. Mechanical properties of resin-ceramic CAD/CAM restorative materials.

    Science.gov (United States)

    Awada, Abdallah; Nathanson, Dan

    2015-10-01

    The recent development of polymer-based computer-aided design and computer-aided manufactured (CAD/CAM) milling blocks and the limited availability of independent studies on these materials make it pertinent to evaluate their properties and identify potential strengths and limitations. The purpose of this in vitro study was to determine and compare mechanical properties (flexural strength, flexural modulus, modulus of resilience) and compare the margin edge quality of recently introduced polymer-based CAD/CAM materials with some of their commercially available composite resin and ceramic counterparts. The materials studied were Lava Ultimate Restorative (LVU; 3M ESPE), Enamic (ENA; Vita Zahnfabrik), Cerasmart (CES; GC Dental Products), IPS Empress CAD (EMP; Ivoclar Vivadent AG), Vitablocs Mark II (VM2; Vita Zahnfabrik), and Paradigm MZ100 Block (MZ1; 3M ESPE). Polished 4×1×13.5 mm bars (n=25) were prepared from standard-sized milling blocks of each tested material. The bars were subjected to a 3-point flexural test on a 10-mm span with a crosshead speed of 0.5 mm/min. In addition, 42 conventional monolithic crowns (7 per material) were milled. Margin edge quality was observed by means of macrophotography and optical microscopy, providing a qualitative visual assessment and a measurement of existing roughness. The results were analyzed by ANOVA followed by the Tukey HSD test (α=.05). The mean flexural strength of the tested materials ranged from 105 ±9 MPa (VM2) to 219 ±20 MPa (CES). The mean flexural modulus ranged from 8 ±0.25 GPa (CES) to 32 ±1.9 GPa (EMP). The mean modulus of resilience ranged from 0.21 ±0.02 MPa (VM2) to 3.07 ±0.45 MPa (CES). The qualitative assessment of margin edge roughness revealed visible differences among the tested materials, with mean roughness measurements ranging from 60 ±16 μm (CES) to 190 ±15 μm (EMP). The material factor had a significant effect on the mean flexural strength (Pmaterials tested in this study exhibited

  12. [Determination of major expansion properties of refractory die material compatible with slip casting core of sintered titanium powder].

    Science.gov (United States)

    Chao, Y; Kuang, X; Liao, Y; Wang, H

    1999-02-01

    To determinate major expansion properties of refractory die material. The setting expansion ratio of refractory die material for slip casting core of sintered titanium powder at room temperature was performed, as well as thermal expansion ratio from room temperature to 800 degrees C. The maximum setting expansion ratio in 2 hours reached 0.3407%; The final setting expansion ratio in 24 hours was 0.3117%; The mean thermal expansion coefficient was mainly in range of 8 x 10(-6)-11 x 10(-6)/degree C; The expansion property seemed very stable after sintering repeatedly and the small shrinkage after sintering could be compensated with the die spacer and setting expansion. The expansion properties of the refractory die material that we synthesized can fulfil the application requirements of slip casting core of sintered titanium powder.

  13. Aerospace Composite Materials Delivery Order 0003: Nanocomposite Polymeric Resin Enhancements for Improved Composite Performance

    National Research Council Canada - National Science Library

    Chen, Chenggang

    2002-01-01

    .... The addition of clays does not significantly alter the viscosity or cure kinetics so that the modified resin will still be suitable for liquid composite molding techniques such as resin transfer molding...

  14. Simulating Resin Infusion through Textile Reinforcement Materials for the Manufacture of Complex Composite Structures

    Directory of Open Access Journals (Sweden)

    Robert S. Pierce

    2017-10-01

    Full Text Available Increasing demand for weight reduction and greater fuel efficiency continues to spur the use of composite materials in commercial aircraft structures. Subsequently, as composite aerostructures become larger and more complex, traditional autoclave manufacturing methods are becoming prohibitively expensive. This has prompted renewed interest in out-of-autoclave processing techniques in which resins are introduced into a reinforcing preform. However, the success of these resin infusion methods is highly dependent upon operator skill and experience, particularly in the development of new manufacturing strategies for complex parts. Process modeling, as a predictive computational tool, aims to address the issues of reliability and waste that result from traditional trial-and-error approaches. Basic modeling attempts, many of which are still used in industry, generally focus on simulating fluid flow through an isotropic porous reinforcement material. However, recent efforts are beginning to account for the multiscale and multidisciplinary complexity of woven materials, in simulations that can provide greater fidelity. In particular, new multi-physics process models are able to better predict the infusion behavior through textiles by considering the effect of fabric deformation on permeability and porosity properties within the reinforcing material. In addition to reviewing previous research related to process modeling and the current state of the art, this paper highlights the recent validation of a multi-physics process model against the experimental infusion of a complex double dome component. By accounting for deformation-dependent flow behavior, the multi-physics process model was able to predict realistic flow behavior, demonstrating considerable improvement over basic isotropic permeability models.

  15. Numerical modeling of the thickness dependence of zinc die-cast materials

    Science.gov (United States)

    Page, Maria Angeles Martinez; Ruf, Matthias; Hartmann, Stefan

    2017-11-01

    Zinc die casting alloys show varying material properties over the thickness in their final solid state, which causes a change in the mechanical response for specimens with different thicknesses. In this article, we propose a modeling concept to account for the varying porosity in the constitutive modeling. The material properties are effectively incorporated by combining a partial differential equation describing the distribution of the pores by a structural parameter with the Mori-Tanaka approach for linear elasticity. The distribution of the porosity is determined by polished cut images, for which the procedure is explained in detail. Finite element simulations of the coupled system incorporating the thickness dependence show the applicability of this approach.

  16. Flame retardant materials based on BDM/DBA resin and organic-inorganic additives

    OpenAIRE

    Wang, Zheng

    2017-01-01

    2,2’-diallyl bisphenol A (DBA) modified bismaleimide resins (BDM) are widely used as polymer matrix of high-performance composites in the field of aerospace, transportation, machinery, and electronics. This kind of resin has excellent properties, including good thermal stability, good processing performance, high mechanical strength, excellent dielectric properties, etc. However, as for most organic resins, the flame retardancy of the BMI resins is not so good. In order to expand the use of t...

  17. Effect of light sources on the bond strength of resin material to thin-walled roots.

    Science.gov (United States)

    Machado, Rosângela Paniago; Chaves, Carolina de Andrade Lima; Rached-Junior, Fuad Jacob Abi; de Souza, Cassio José; Messias, Danielle Cristine; Silva-Sousa, Yara Corrêa

    2014-01-01

    The aim of this study was to evaluate the bond strength to the dentin of an adhesive material used for root reinforcement light activated with different sources. Roots were divided into 4 groups (n=15) according to the light source used to activate the resin reinforcement: GI, non-weakened roots (control); GII, halogen light (H) 600 mW/cm²; GIII, LED 800 mW/cm² and GIV, LED 1500 mW/cm². The reinforcement was done with adhesive, composite resin and fiberglass posts. After 24 h, the specimens were sectioned and the first slice of each post region was used in the push out test in a universal testing machine with a crosshead speed of 0.5 mm/min. Failure modes of the debonded specimens were examined. Data (MPa) were analyzed by ANOVA and Holm-Sidak test (α=0.05). The second slice from each region was analyzed by scanning electron microscopy (SEM). LED-1500 (4.69 ± 1.74) provided bond strength similar to the control group (5.05 ± 2.63) and statistically different from H-600 (1.96 ± 0.94) and LED-800 (2.75 ± 1.90), which were similar to each other (presin reinforcement to the dentin.

  18. Bacterial colonization of resin composite cements: influence of material composition and surface roughness.

    Science.gov (United States)

    Glauser, Stephanie; Astasov-Frauenhoffer, Monika; Müller, Johannes A; Fischer, Jens; Waltimo, Tuomas; Rohr, Nadja

    2017-08-01

    So-called secondary caries may develop in the cement gap between the tooth and the bonded restoration. Cement materials with a low susceptibility to biofilm formation are therefore desirable. In the present study, the adhesion of Strepococcus mutans onto three adhesive (Multilink Automix, RelyX Ultimate, and Panavia V5) and three self-adhesive (Multilink Speed Cem, RelyX Unicem 2 Automix, and Panavia SA plus) resin composite cements was evaluated. Previous studies have failed to evaluate concomitantly the effect of both the composition of the cements and their surface roughness on biofilm formation. The presence of S. mutans on cement surfaces with differing degrees of roughness was therefore recorded using fluorescence microscopy and crystal violet staining, and the composition of the cements was analyzed using energy-dispersive X-ray spectroscopy mapping. Biofilm formation on resin composite cements was found to be higher on rougher surfaces, implying that adequate polishing of the cement gap is essential. The use of copper-containing cements (Multilink Automix, Panavia V5, and Panavia SA plus) significantly reduced biofilm formation. © 2017 Eur J Oral Sci.

  19. Randomized clinical trial of two resin-modified glass ionomer materials: 1-year results.

    Science.gov (United States)

    Perdigão, J; Dutra-Corrêa, M; Saraceni, S H C; Ciaramicoli, M T; Kiyan, V H

    2012-01-01

    With institutional review board approval, 33 patients who needed restoration of noncarious cervical lesions (NCCL) were enrolled in this study. A total of 92 NCCL were selected and randomly assigned to three groups: (1) Ambar (FGM), a two-step etch-and-rinse adhesive (control), combined with the nanofilled composite resin Filtek Supreme Plus (FSP; 3M ESPE); (2) Fuji II LC (GC America), a traditional resin-modified glass ionomer (RMGIC) restorative material; (3) Ketac Nano (3M ESPE), a nanofilled RMGIC restorative material. Restorations were evaluated at six months and one year using modified United States Public Health Service parameters. At six months after initial placement, 84 restorations (a 91.3% recall rate) were evaluated. At one year, 78 restorations (a 84.8% recall rate) were available for evaluation. The six month and one year overall retention rates were 93.1% and 92.6%, respectively, for Ambar/FSP; 100% and 100%, respectively, for Fuji II LC; and 100% and 100%, respectively, for Ketac Nano with no statistical difference between any pair of groups at each recall. Sensitivity to air decreased for all three adhesive materials from the preoperative to the postoperative stage, but the difference was not statistically significant. For Ambar/FSP, there were no statistical differences for any of the parameters from baseline to six months and from baseline to one year. For Fuji II LC, surface texture worsened significantly from baseline to six months and from baseline to one year. For Ketac Nano, enamel marginal staining increased significantly from baseline to one year and from six months to one year. Marginal adaptation was statistically worse at one year compared with baseline only for Ketac Nano. When parameters were compared for materials at each recall, Ketac Nano resulted in significantly worse color match than any of the other two materials at any evaluation period. At one year, Ketac Nano resulted in significantly worse marginal adaptation than the

  20. Effect of Aging Regimens on Resin Nanoceramic Chairside CAD/CAM Material.

    Science.gov (United States)

    Al-Harbi, Fahad A; Ayad, Neveen M; ArRejaie, Aws S; Bahgat, Hala A; Baba, Nadim Z

    2017-07-01

    To evaluate the effect of cyclic mechanical loading, thermal cycling, and storage in water on a resin nanoceramic chairside computer-aided designed/computer-aided manufactured (CAD/CAM) material compared to a control leucite-reinforced glass-ceramic material. One hundred twenty specimens (18 × 4 × 3 mm) were milled from two chairside CAD/CAM materials' blocks (Lava Ultimate: LU; Vitablock Mark II: VM). Each group included four subgroups (A: n = 20 control; B: n = 20 cyclic loading [105 cycles, 80 N]; C: n = 20 thermal cycling [5 to 55°C]; D: n = 60 water storage [20: 3 months; 20: 6 months; 20: 9 months at 37°C]). Each subgroup included 10 specimens tested for flexure strength using three-point bending in a universal testing machine. The other 10 specimens were tested for surface roughness using an automated profiler followed by testing for surface hardness using a microhardness tester. LU displayed higher flexure strength than VM before and after all the aging conditions. The surface roughness for VM was lower than LU for the control, but both materials showed comparable values and significant increases after 9 months storage in water. After cyclic loading, only VM displayed a significant increase in the surface roughness value (p CAD/CAM material. © 2015 by the American College of Prosthodontists.

  1. Light-curing considerations for resin-based composite materials: a review. Part II.

    Science.gov (United States)

    Malhotra, Neeraj; Mala, Kundabala

    2010-10-01

    As discussed in Part I, the type of curing light and curing mode impact the polymerization kinetics of resin-based composite (RBC) materials. Major changes in light-curing units and curing modes have occurred. The type of curing light and mode employed affects the polymerization shrinkage and associated stresses, microhardness, depth of cure, degree of conversion, and color change of RBCs. These factors also may influence the microleakage in an RBC restoration. Apart from the type of unit and mode used, the polymerization of RBCs is also affected by how a light-curing unit is used and handled, as well as the aspects associated with RBCs and the environment. Part II discusses the various clinical issues that should be considered while curing RBC restorations in order to achieve the best possible outcome.

  2. Field Trial of Resin-Based Composite Materials for the Treatment of Surface Collapses Associated with Former Shallow Coal Mining

    OpenAIRE

    Philip T. Broughton; Mark P. Bettney; Isla L. Smail

    2016-01-01

    Effective treatment of ground instability is essential when managing the impacts associated with historic mining. A field trial was undertaken by the Coal Authority to investigate the geotechnical performance and potential use of composite materials comprising resin and fill or stone to safely treat surface collapses, such as crown-holes, associated with shallow mining. Test pits were loosely filled with various granular fill materials. The fill material was injected with commercially availab...

  3. Restoration of endodontically treated anterior teeth: an evaluation of coronal microleakage of glass ionomer and composite resin materials.

    Science.gov (United States)

    Diaz-Arnold, A M; Wilcox, L R

    1990-12-01

    A glass ionomer material was evaluated for coronal microleakage in permanent lingual access restorations of endodontically treated anterior teeth. The material was tested as a restoration, placed over a zinc oxide-eugenol base, and as a base with an acid-etched composite resin veneer and a dentinal bonding agent. Restored teeth were thermocycled, immersed in silver nitrate, developed, and sectioned to assess microleakage. Significant coronal leakage was observed with all materials used.

  4. Effect of toothbrushing abrasion on weight and surface roughness of pH-cycled resin cements and indirect restorative materials.

    Science.gov (United States)

    Prakki, Anuradha; Cilli, Renato; de Araújo, Paulo Amarante; Navarro, Maria Fidela de Lima; Mondelli, José; Mondelli, Rafael Francisco Lia

    2007-10-01

    To evaluate wear resistance, by weight loss and roughness changes, of resin cements and indirect restorative materials to toothbrushing and toothbrushing associated with pH-challenge simulation. The following materials were studied: Enforce resin cement (Dentsply), Rely X resin cement (3M ESPE), Variolink II resin cement (Ivoclar/Vivadent), Artglass indirect resin composite (Heraeus Kulzer), and Duceram Plus porcelain (Degussa). Twenty cylindrical specimens were prepared for each material for a total of 10 groups (n = 10). After finishing and polishing, the specimens were subjected to toothbrushing. One group of each material was pH cycled before abrasion. For toothbrushing, a machine containing soft-bristle tips, dentifrice, and water was used. One hundred thousand brushing cycles were performed. Weight loss was determined as the percentage difference between initial (before brushing) and final (after brushing) measurements. Roughness changes were evaluated by the difference between initial and final measurements. Data were analyzed with the paired t test, 2-way ANOVA, and Tukey test (alpha = 0.05). Paired t test showed significant differences in weight loss and roughness after toothbrushing (P <.01). Statistically significant differences were found among materials for both weight loss, which ranged from 0.34% (Duceram Plus) to 1.85% (Enforce/pH), and roughness changes, which ranged from -0.03 microm (Duceram Plus) to 0.29 microm (Rely X/pH). Among cements, Variolink II exhibited the least weight loss and roughness increase. Of all materials, Duceram Plus porcelain presented the lowest weight loss and became smoother after abrasion. pH cycling had no influence on material weight or roughness changes after abrasion.

  5. Effect of storage in water and thermocycling on hardness and roughness of resin materials for temporary restorations

    Directory of Open Access Journals (Sweden)

    Jerusa Cleci de Oliveira

    2010-09-01

    Full Text Available PURPOSE: This study evaluated the effect of storage in water and thermocycling on hardness and roughness of resin materials for temporary restorations. MATERIAL AND METHODS: Three acrylic resins (Dencor-De, Duralay-Du, and Vipi Cor-VC were selected and one composite resin (Opallis-Op was used as a parameter for comparison. The materials were prepared according to the manufacturers' instructions and were placed in stainless steel moulds (20 mm in diameter and 5 mm thick. Thirty samples of each resin were made and divided into three groups (n = 10 according to the moment of Vickers hardness (VHN and roughness (Ra analyses: C (control group: immediately after specimen preparation; Sw: after storage in distilled water at 37 °C for 24 hours; Tc: after thermocycling (3000 cycles; 5-55 °C, 30 seconds dwell time. Data were submitted to 2-way ANOVA followed by Tukey's test (α = 0.05. RESULTS: Op resin had higher surface hardness values (p 0.05 in roughness among materials (De = 0.31 ± 0.07; Du = 0.51 ± 0.20; VC = 0.41 ± 0.15; Op = 0.42 ± 0.18. Storage in water did not change hardness and roughness of the tested materials (p > 0.05. There was a significant increase in roughness after thermocycling (p < 0.05, except for material Du, which showed no significant change in roughness in any evaluated period (p = 0.99. CONCLUSION: Thermocycling increased the roughness in most tested materials without affecting hardness, while storage in water had no significant effect in the evaluated properties.

  6. Do Dental Resin Composites Accumulate More Oral Biofilms and Plaque than Amalgam and Glass Ionomer Materials?

    Science.gov (United States)

    Zhang, Ning; Melo, Mary A.S.; Weir, Michael D.; Reynolds, Mark A.; Bai, Yuxing; Xu, Hockin H.K.

    2016-01-01

    A long-time drawback of dental composites is that they accumulate more biofilms and plaques than amalgam and glass ionomer restorative materials. It would be highly desirable to develop a new composite with reduced biofilm growth, while avoiding the non-esthetics of amalgam and low strength of glass ionomer. The objectives of this study were to: (1) develop a protein-repellent composite with reduced biofilms matching amalgam and glass ionomer for the first time; and (2) investigate their protein adsorption, biofilms, and mechanical properties. Five materials were tested: A new composite containing 3% of protein-repellent 2-methacryloyloxyethyl phosphorylcholine (MPC); the composite with 0% MPC as control; commercial composite control; dental amalgam; resin-modified glass ionomer (RMGI). A dental plaque microcosm biofilm model with human saliva as inoculum was used to investigate metabolic activity, colony-forming units (CFU), and lactic acid production. Composite with 3% MPC had flexural strength similar to those with 0% MPC and commercial composite control (p > 0.1), and much greater than RMGI (p control composites (p control composites (p 0.1). In conclusion, a new protein-repellent dental resin composite reduced oral biofilm growth and acid production to the low levels of non-esthetic amalgam and RMGI for the first time. The long-held conclusion that dental composites accumulate more biofilms than amalgam and glass ionomer is no longer true. The novel composite is promising to finally overcome the major biofilm-accumulation drawback of dental composites in order to reduce biofilm acids and secondary caries. PMID:28774007

  7. Do Dental Resin Composites Accumulate More Oral Biofilms and Plaque than Amalgam and Glass Ionomer Materials?

    Science.gov (United States)

    Zhang, Ning; Melo, Mary A S; Weir, Michael D; Reynolds, Mark A; Bai, Yuxing; Xu, Hockin H K

    2016-11-01

    A long-time drawback of dental composites is that they accumulate more biofilms and plaques than amalgam and glass ionomer restorative materials. It would be highly desirable to develop a new composite with reduced biofilm growth, while avoiding the non-esthetics of amalgam and low strength of glass ionomer. The objectives of this study were to: (1) develop a protein-repellent composite with reduced biofilms matching amalgam and glass ionomer for the first time; and (2) investigate their protein adsorption, biofilms, and mechanical properties. Five materials were tested: A new composite containing 3% of protein-repellent 2-methacryloyloxyethyl phosphorylcholine (MPC); the composite with 0% MPC as control; commercial composite control; dental amalgam; resin-modified glass ionomer (RMGI). A dental plaque microcosm biofilm model with human saliva as inoculum was used to investigate metabolic activity, colony-forming units (CFU), and lactic acid production. Composite with 3% MPC had flexural strength similar to those with 0% MPC and commercial composite control ( p > 0.1), and much greater than RMGI ( p biofilm CFU and lactic acid much lower than control composites ( p Biofilm growth, metabolic activity and lactic acid on the new composite with 3% MPC were reduced to the low level of amalgam and RMGI ( p > 0.1). In conclusion, a new protein-repellent dental resin composite reduced oral biofilm growth and acid production to the low levels of non-esthetic amalgam and RMGI for the first time. The long-held conclusion that dental composites accumulate more biofilms than amalgam and glass ionomer is no longer true. The novel composite is promising to finally overcome the major biofilm-accumulation drawback of dental composites in order to reduce biofilm acids and secondary caries.

  8. Do Dental Resin Composites Accumulate More Oral Biofilms and Plaque than Amalgam and Glass Ionomer Materials?

    Directory of Open Access Journals (Sweden)

    Ning Zhang

    2016-11-01

    Full Text Available A long-time drawback of dental composites is that they accumulate more biofilms and plaques than amalgam and glass ionomer restorative materials. It would be highly desirable to develop a new composite with reduced biofilm growth, while avoiding the non-esthetics of amalgam and low strength of glass ionomer. The objectives of this study were to: (1 develop a protein-repellent composite with reduced biofilms matching amalgam and glass ionomer for the first time; and (2 investigate their protein adsorption, biofilms, and mechanical properties. Five materials were tested: A new composite containing 3% of protein-repellent 2-methacryloyloxyethyl phosphorylcholine (MPC; the composite with 0% MPC as control; commercial composite control; dental amalgam; resin-modified glass ionomer (RMGI. A dental plaque microcosm biofilm model with human saliva as inoculum was used to investigate metabolic activity, colony-forming units (CFU, and lactic acid production. Composite with 3% MPC had flexural strength similar to those with 0% MPC and commercial composite control (p > 0.1, and much greater than RMGI (p < 0.05. Composite with 3% MPC had protein adsorption that was only 1/10 that of control composites (p < 0.05. Composite with 3% MPC had biofilm CFU and lactic acid much lower than control composites (p < 0.05. Biofilm growth, metabolic activity and lactic acid on the new composite with 3% MPC were reduced to the low level of amalgam and RMGI (p > 0.1. In conclusion, a new protein-repellent dental resin composite reduced oral biofilm growth and acid production to the low levels of non-esthetic amalgam and RMGI for the first time. The long-held conclusion that dental composites accumulate more biofilms than amalgam and glass ionomer is no longer true. The novel composite is promising to finally overcome the major biofilm-accumulation drawback of dental composites in order to reduce biofilm acids and secondary caries.

  9. Resin-Impregnated Carbon Ablator: A New Ablative Material for Hyperbolic Entry Speeds

    Science.gov (United States)

    Esper, Jaime; Lengowski, Michael

    2012-01-01

    Ablative materials are required to protect a space vehicle from the extreme temperatures encountered during the most demanding (hyperbolic) atmospheric entry velocities, either for probes launched toward other celestial bodies, or coming back to Earth from deep space missions. To that effect, the resin-impregnated carbon ablator (RICA) is a high-temperature carbon/phenolic ablative thermal protection system (TPS) material designed to use modern and commercially viable components in its manufacture. Heritage carbon/phenolic ablators intended for this use rely on materials that are no longer in production (i.e., Galileo, Pioneer Venus); hence the development of alternatives such as RICA is necessary for future NASA planetary entry and Earth re-entry missions. RICA s capabilities were initially measured in air for Earth re-entry applications, where it was exposed to a heat flux of 14 MW/sq m for 22 seconds. Methane tests were also carried out for potential application in Saturn s moon Titan, with a nominal heat flux of 1.4 MW/sq m for up to 478 seconds. Three slightly different material formulations were manufactured and subsequently tested at the Plasma Wind Tunnel of the University of Stuttgart in Germany (PWK1) in the summer and fall of 2010. The TPS integrity was well preserved in most cases, and results show great promise.

  10. Effect of Rake Angle During Machining of Micro Grooves on Electroless Nickel Plated Die Materials

    International Nuclear Information System (INIS)

    Rezaur Rahman, K.M.; Rahman, M.

    2005-01-01

    This study attempts to evaluate the performance of two single crystal diamond tools with different rake angle (0 0 and -15 0 ) during micro grooving on electroless nickel plated die materials. It was found that the 0 0 rake diamond tool has superior performance compared to the -15 0 rake angle tool. The negative rake tool experienced very high thrust force, and severe chipping on the flank face was evident after a short cutting distance of 3.13 km. On the other hand, the 0 0 rake tool machined satisfactorily up to 50 km without any significant tool wear. While machining with the -15 0 rake tool, significant change in surface roughness with spindle speed was observed compared to the 0 0 rake tool. With increasing infeed rate variation in surface roughness was evident only with the -15 0 rake tool. Steep change in roughness with machining distance was also observed while machining with the negative rake tool. (authors)

  11. Coupled analysis of material flow and die deflection in direct aluminum extrusion

    NARCIS (Netherlands)

    Assaad, W.; Geijselaers, Hubertus J.M.

    2010-01-01

    The design of extrusion dies depends on the experience of the designer. After the die has been manufactured, it is tested during an extrusion trial and machined several times until it works properly. The die is designed by a trial and error method which is an expensive process in terms of time and

  12. Influence of Custom Trays, Dual-Arch Passive, Flexed Trays and Viscosities of Elastomeric Impression Materials on Working Dies.

    Science.gov (United States)

    Arora, Mansi; Kohli, Shivani; Kalsi, Rupali

    2016-05-01

    Dual arch impression technique signifies an essential improvement in fixed prosthodontics and has numerous benefits over conventional impression techniques. The accuracy of working dies fabricated from dual arch impression technique remains in question because there is little information available in the literature. This study was conducted to compare the accuracy of working dies fabricated from impressions made from two different viscosities of impression materials using metal, plastic dual arch trays and custom made acrylic trays. The study samples were grouped into two groups based on the viscosity of impression material used i.e. Group I (monophase), whereas Group II consisted of Dual Mix technique using a combination of light and heavy body material. These were further divided into three subgroups A, B and C depending on the type of impression tray used (metal dual arch tray, plastic dual arch tray and custom made tray). Measurements of the master cast were made using profile projector. Descriptive statistics like mean, Standard Deviation (SD) were calculated for all the groups. One way analysis of variance (ANOVA) was used for multiple group comparisons. A p-value of 0.05 or less was considered statistically significant. The gypsum dies obtained with the three types of impression trays using two groups of impression materials were smaller than the master models in dimensions. The plastic dual arch trays produced dies which were the least accurate of the three groups. There was no significant difference in the die dimensions obtained using the two viscosities of impression materials.

  13. Preparation of polymer nanocomposite materials based on unsaturated polyester resin and nanosilica A200. Part II - Structural and properties of polymer nanocomposite materials based on unsaturated polyester resin and nanosilica A200 with coupling agent

    International Nuclear Information System (INIS)

    Trinh Minh Dat; Bui Chuong; Bach Trong Phuc; Dinh Van Kai; Luu Van Khue

    2012-01-01

    Effects of coupling agent on the structures and properties of nanocomposite materials based on unsaturated polyester resin and A200 silica nanoparticles were investigated. The viscosity of the resin/A200 silica mixtures increased with increasing coupling agent content because of forming core-shell structures and the mechanical properties of polymer nanocomposites generally were better than those without coupling agent and appeared a maximum in mechanical properties at 4.0 wt% coupling agent content. IR analyze indicated that the coupling agent had reacted with unsaturated polyester resin and A200 silica nanoparticles. SEM, Fe-SEM and TG-SDC demonstrated more homogeneous dispersion of A200 silica nanoparticles in the polymer matrix and accompanied by lower glass transition temperature and melt temperature. Furthermore, it was also found that the best dispersion route involved a methanol dispersion technique. (author)

  14. Solidification of spent ion exchange resin using new cementitious material, (1)

    International Nuclear Information System (INIS)

    Matsuda, Masami; Nishi, Takashi; Chino, Koichi; Kikuchi, Makoto

    1992-01-01

    Cement solidification is a conventional technique to solidify spent ion exchange resin. Swelling property of the ion exchange resin was investigated theoretically and experimentally, as the first step to improve resin content in a cement package. Swelling pressure of the resin was first formulated based on Gregor's swelling model. It was shown that the pressure depended on such factors as ion exchange capacity, type of functional group, crosslinkage and water content. Subsequently, swelling pressures for over forty properties of cation exchange resin (DIAION SK-series) with different exchange capacities, water contents and others were experimentally evaluated using an originally developed method. The pressure changed over a range of 0 ∼ 60 MPa, depending on properties of the ion exchange resin. These results were in close agreement with values calculated by Gregor's model, indicating that the swelling pressure could be evaluated without resorting to experiments. (author)

  15. Characterization of multiwalled carbon nanotube-polymethyl methacrylate composite resins as denture base materials.

    Science.gov (United States)

    Wang, Russell; Tao, Junliang; Yu, Bill; Dai, Liming

    2014-04-01

    Most fractures of dentures occur during function, primarily because of the flexural fatigue of denture resins. The purpose of this study was to evaluate a polymethyl methacrylate denture base material modified with multiwalled carbon nanotubes in terms of fatigue resistance, flexural strength, and resilience. Denture resin specimens were fabricated: control, 0.5 wt%, 1 wt%, and 2 wt% of multiwalled carbon nanotubes. Multiwalled carbon nanotubes were dispersed by sonication. Thermogravimetric analysis was used to determine quantitative dispersions of multiwalled carbon nanotubes in polymethyl methacrylate. Raman spectroscopic analyses were used to evaluate interfacial reactions between the multiwalled carbon nanotubes and the polymethyl methacrylate matrix. Groups with and without multiwalled carbon nanotubes were subjected to a 3-point-bending test for flexural strength. Resilience was derived from a stress and/or strain curve. Fatigue resistance was conducted by a 4-point bending test. Fractured surfaces were analyzed by scanning electron microscopy. One-way ANOVA and the Duncan tests were used to identify any statistical differences (α=.05). Thermogravimetric analysis verified the accurate amounts of multiwalled carbon nanotubes dispersed in the polymethyl methacrylate resin. Raman spectroscopy showed an interfacial reaction between the multiwalled carbon nanotubes and the polymethyl methacrylate matrix. Statistical analyses revealed significant differences in static and dynamic loadings among the groups. The worst mechanical properties were in the 2 wt% multiwalled carbon nanotubes (Ppolymethyl methacrylate groups showed poor fatigue resistance. The scanning electron microscopy results indicated more agglomerations in the 2% multiwalled carbon nanotubes. Multiwalled carbon nanotubes-polymethyl methacrylate groups (0.5% and 1%) performed better than the control group during the static flexural test. The results indicated that 2 wt% multiwalled carbon nanotubes

  16. Experimental Investigation on the Specific Heat of Carbonized Phenolic Resin-Based Ablative Materials

    Science.gov (United States)

    Zhao, Te; Ye, Hong; Zhang, Lisong; Cai, Qilin

    2017-10-01

    As typical phenolic resin-based ablative materials, the high silica/phenolic and carbon/phenolic composites are widely used in aerospace field. The specific heat of the carbonized ablators after ablation is an important thermophysical parameter in the process of heat transfer, but it is rarely reported. In this investigation, the carbonized samples of the high silica/phenolic and carbon/phenolic were obtained through carbonization experiments, and the specific heat of the carbonized samples was determined by a 3D DSC from 150 °C to 970 °C. Structural and compositional characterizations were performed to determine the mass fractions of the fiber and the carbonized product of phenolic which are the two constituents of the carbonized samples, while the specific heat of each constituent was also measured by 3D DSC. The masses of the carbonized samples were reduced when heated to a high temperature in the specific heat measurements, due to the thermal degradation of the carbonized product of phenolic resin in the carbonized samples. The raw experimental specific heat of the two carbonized samples and the carbonized product of phenolic resin was modified according to the quality changes of the carbonized samples presented by TGA results. Based on the mass fraction and the specific heat of each constituent, a weighted average method was adopted to obtain the calculated results of the carbonized samples. Due to the unconsolidated property of the fiber samples which impacts the reliability of the DSC measurement, there is a certain deviation between the experimental and calculated results of the carbonized samples. Considering the similarity of composition and structure, the data of quartz glass and graphite were used to substitute the specific heat of the high silica fiber and carbon fiber, respectively, resulting in better agreements with the experimental ones. Furthermore, the accurate specific heat of the high silica fiber and carbon fiber bundles was obtained by

  17. Tribological Investigations of Hard-Faced Layers and Base Materials of Forging Dies with Different Kinds of Lubricants Applied

    Directory of Open Access Journals (Sweden)

    V. Lazić

    2010-12-01

    Full Text Available This paper gives a procedure for choosing the right technology for reparative hard facing of damaged forging dies. Since they are subject to impact loads and cyclic temperature elevations, forging dies should be made of steel that is able to withstand great impact loads, maintain good mechanical properties at elevated temperatures and that is resistant to wear and thermal fatigue. For these reasons, forging dies are made of conditionally weldable alloy tool steels; however it makes hard facing of damaged tools even more difficult. In this paper, wear resistance of base materials, hard-faced layers and heat-affected zones are tribologically investigated when two different lubricants - pure synthetical oil LM 76 and LM 76 with 6% molybdenum disulfide (MoS2 are applied. Tribological investigations have shown that the wear resistance of the hard faced layers is considerably greater than the wear resistance of the base material. However, the base material has better properties concerning friction.

  18. Effect of surface treatments on the bond strength of soft denture lining materials to an acrylic resin denture base.

    Science.gov (United States)

    Gundogdu, Mustafa; Yesil Duymus, Zeynep; Alkurt, Murat

    2014-10-01

    Adhesive failure between acrylic resin and resilient liner material is commonly encountered in clinical practice. The purpose of this study was to evaluate the effect of different surface treatments on the bond strength of 2 different resilient lining materials to an acrylic resin denture base. Ninety-six dumbbell-shaped specimens were fabricated from heat-polymerized acrylic resin, and 3 mm of the material was cut from the thin midsection. The specimens were divided into 6 groups according to their surface treatments: no surface treatment (control group), 36% phosphoric acid etching (acid group), erbium:yttrium-aluminum-garnet (Er:YAG) laser (laser group), airborne-particle abrasion with 50-μm Al2O3 particles (abrasion group), an acid+laser group, and an abrasion+laser group. The specimens in each group were divided into 2 subgroups according to the resilient lining material used: heat-polymerized silicone based resilient liner (Molloplast B) and autopolymerized silicone-based resilient liner (Ufi Gel P). After all of the specimens had been polymerized, they were stored in distilled water at 37°C for 1 week. A tensile bond strength test was then performed. Data were analyzed with a 2-way ANOVA, and the Sidak multiple comparison test was used to identify significant differences (α=.05). The effects of the surface treatments and resilient lining materials on the surface of the denture base resin were examined with scanning electron microscopy. The tensile bond strength was significantly different between Molloplast B and Ufi Gel P (Presin. Molloplast B exhibited significantly higher bond strength than Ufi Gel P. Altering the surface of the acrylic resin denture base with 36% phosphoric acid etching increased bond strength. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  19. Effect of reline material and denture base surface treatment on the impact strength of a denture base acrylic resin.

    Science.gov (United States)

    da Cruz Perez, Luciano Elias; Machado, Ana Lucia; Canevarolo, Sebastião Vicente; Vergani, Carlos Eduardo; Giampaolo, Eunice Teresinha; Pavarina, Ana Cláudia

    2010-03-01

    In this study, the effect of relining and surface treatment on the impact strength (IS) of a heat-polymerising denture base acrylic resin (Lucitone 550-L) was evaluated. Rectangular bars of L were made (60 x 6 x 2 mm) and relined (2 mm) with the relining resins Ufi Gel Hard (UH) and Tokuso Rebase Fast (TR). Specimens relined with L and intact L, TR and UH specimens were also made (60 x 6 x 4 mm), for comparison. Before relining, the L surface was left untreated or wetted with methyl methacrylate monomer and/or the bonding agents (BA) supplied by manufacturers of the reline resins. V-notches were machined at the midpoint of the length of all specimens. The notches were made either across the width (Nw) or across the thickness of the specimens (Nth). The Charpy impact test was performed using a 0.5-J pendulum, which had been specially designed and constructed. Data were analysed separately for each notch position using one-way analysis of variance and Tukey honestly significant difference post-hoc test (p = 0.05). The IS of L was similar to that of L/L. For the Nw notch, treating the denture base L with TR BA and relining with TR reline material produced the highest IS. The IS of specimens made from heat polymerising acrylic resin Lucitone 550 was increased after relining using the hard chairside reline resin TR with its proprietary BA.

  20. Determining the dimensional stability, fracture toughness and flexural strength of light-cured acrylic resin custom tray material.

    Science.gov (United States)

    Khan, S B; Geerts, G

    2009-06-01

    Light-cured acrylic resin custom tray material is used in commercial dental laboratories but little evidence-based scientific information on its physical properties is available. This study investigates the dimensional stability of light-cured acrylic resin custom tray material and compares its fracture toughness and flexural strength to a chemically-cured acrylic material. For dimensional stability, 20 light-cured specimens were fabricated and measured 3 times at regular time intervals over 48 hours. Mean shrinkage was calculated for each time interval and the mean values were compared to the standard using the Wilcoxon Rank Sum test. A p-value of materials with a single-edge notch were subjected to a compressive load using the 3-point bending technique. For flexural strength, 1 group (n=20) of each material was subjected to a compressive load using 3-point bending. The highest load before failure was used to calculate the fracture toughness and flexural strength. Differences in fracture toughness and flexural strength values between the 2 groups were compared using ANOVA testing. A p-value of 0.05). The fracture toughness and flexural strength were significantly higher for the light-cured material. Trays made from light-cured acrylic resin can be used immediately following polymerization. The light-cured material is more resistant to bending and crack propagation than the chemically-cured type.

  1. The Effect of Finishing and Polishing Techniques on the Surface Roughness and the Color of Nanocomposite Resin Restorative Materials.

    Science.gov (United States)

    Avsar, Aysun; Yuzbasioglu, Emir; Sarac, Duygu

    2015-01-01

    Rough, poorly polished surfaces contribute to staining, plaque accumulation, gingival irritation and recurrent caries. Finishing and polishing techniques are critical factors contributing to the longevity of the direct composite resin restorations. The aim of this in vitro study was to evaluate the effects of finishing and polishing systems on surface roughness of six nanocomposite restorative resins. Thirty specimens of each restorative material (n=180) were placed in a teflon mould (6 mm in diameter and 3 mm in depth) and cured with a LED curing unit. Six specimens from each of restorative material were randomly assigned to four groups for finishing and polishing (carbide burs, diamond burs, aluminium oxide discs, silicon rubber polisher) techniques. Mylar strip formed specimens were served as control group. After finishing and polishing procedures surface roughness was evaluated by a profilometer. The data was analyzed by 2-way analysis of variance and the Tukey HSD test (α=0.05). Significant differences were found between the groups in terms roughness (prestorative materials. Although mylar matrix strip formed surfaces presents lower surface roughness values, recountouring and polishing of resin restorations are often required in clinical situations. Aluminium oxide discs and carbide finishing burs are suitable for finishing and polishing procedures for nanocomposite restorative resins.

  2. Micro-shear bond strength of different resin cements to ceramic/glass-polymer CAD-CAM block materials.

    Science.gov (United States)

    Cekic-Nagas, Isil; Ergun, Gulfem; Egilmez, Ferhan; Vallittu, Pekka Kalevi; Lassila, Lippo Veli Juhana

    2016-10-01

    The aim of this study was to evaluate the effects of hydrofluoric acid treatment on bond strength of resin cements to three different types of ceramic/glass containing CAD-CAM block composite materials. CAD-CAM block materials of polymer infiltrated (Vita Enamic), resin nanoceramic (Lava Ultimate) and nanoceramic (Cerasmart) with a thickness of 1.5mm were randomly divided into two groups according to the surface treatment performed. In Group 1, specimens were wet-ground with silicon carbide abrasive papers up to no. 1000. In Group 2, 9.6% hydrofluoric acid gel was applied to ceramics. Three different resin cements (RelyX, Variolink Esthetic and G-CEM LinkAce) were applied to the tubes in 1.2-mm thick increments and light-cured for 40s using LED light curing unit. Half of the specimens (n=10) were submitted to thermal cycling (5000 cycles, 5-55°C). The strength measurements were accomplished with a universal testing machine (Lloyd Instruments) at a cross-head speed of 0.5mm/min until the failure occurs. Failure modes were examined using a stereomicroscope and scanning electron microscope. The data were analyzed with multivariate analysis of variance (MANOVA) and Tukey's post hoc tests (α=0.05). There were significant differences between ceramics and resin cements (pceramics (pceramic/glass-polymer materials might promote the bonding capacity of these systems. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  3. Resin-Powder Dispenser

    Science.gov (United States)

    Standfield, Clarence E.

    1994-01-01

    Resin-powder dispenser used at NASA's Langley Research Center for processing of composite-material prepregs. Dispenser evenly distributes powder (resin polymer and other matrix materials in powder form) onto wet uncured prepregs. Provides versatility in distribution of solid resin in prepreg operation. Used wherever there is requirement for even, continuous distribution of small amount of powder.

  4. Characteristics of novel root-end filling material using epoxy resin and Portland cement.

    Science.gov (United States)

    Lee, Sang-Jin; Chung, Jin; Na, Hee-Sam; Park, Eun-Joo; Jeon, Hyo-Jin; Kim, Hyeon-Cheol

    2013-04-01

    The aim of this study was to evaluate the physical properties and cytotoxicity of a novel root-end filling material (EPC) which is made from epoxy resin and Portland cement as a mineral trioxide aggregate (MTA) substitute. EPC, developed as a root-end filling material, was compared with MTA and a mixture of AH Plus sealer and MTA (AMTA) with regard to the setting time, radio-opacity, and microleakage. Setting times were evaluated using Vicat apparatus. Digital radiographs were taken to evaluate the aluminium equivalent radio-opacity using an aluminium step wedge. Extracted single-rooted teeth were used for leakage test using methylene blue dye. After canal shaping and obturation, the apical 3-mm root was resected, and a root-end cavity with a depth of 3 mm was prepared. The root-end cavities were filled with MTA, AMTA, and EPC for 15 specimens in each of three groups. After setting in humid conditions for 24 h, the specimens were tested for apical leakage. For evaluation of the biocompatibility of EPC, cell (human gingival fibroblast) viability was compared for MTA and Portland cement by MTT assay, and cell morphological changes were compared for MTA and AH Plus by fluorescence microscopy using DAPI and F-actin staining. The setting time, radio-opacity, and microleakage were compared using one-way ANOVA and Scheffe's post hoc comparison, and the cytotoxicity was compared using the nonparametric Kruskal-Wallis rank sum test. Statistical significance was set at 95%. EPC had a shorter setting time and less microleakage compared with MTA (p Portland cement, was found to be a useful material for root-end filling, with favourable radio-opacity, short setting time, low microleakage, and clinically acceptable low cytotoxicity. The novel root-end filling material would be a potentially useful material for a surgical endodontic procedure with favourable properties.

  5. Production and characterization of composite material based on ablative phenolic resin and carbon fibers

    International Nuclear Information System (INIS)

    Srebrenkoska, Vineta

    2002-01-01

    The optimisation of technology for production of moulding compound based on short carbon fibers and ablative phenolic resin is carried out. The characterisation of the starting raw materials is performed and moulding compounds With different fiber/matrix ratios and different fiber lengths are prepared. From the different samples, mouldings are produced by thermal compression. All physical, mechanical and thermal properties of the composites are tested. From the obtained results the optimal fiber/matrix ratio, for high temperature moulding compounds production are determined. Also, in order to meet the request for high thermal and mechanics properties of the composite, optimization is carded out on the moulding process itself. The optimization is fulfilled by a planned experiment. The full factorial experimental design is applied in which the following parameters are varied: fiber length, temperature and time of the press cycle. Regression equations for the influence of the parameters to the impact resistance, compression strength, flexural strength and the modulus of elasticity of the molding, are obtained. The obtained mechanical properties of the composite rate this material for potential application in the automotive, leisure, military and other industries.(Author)

  6. Development of Functionally Graded Materials for Manufacturing Tools and Dies and Industrial Processing Equipment

    Energy Technology Data Exchange (ETDEWEB)

    Lherbier, Louis, W.; Novotnak, David, J.; Herling, Darrell, R.; Sears, James, W.

    2009-03-23

    Hot forming processes such as forging, die casting and glass forming require tooling that is subjected to high temperatures during the manufacturing of components. Current tooling is adversely affected by prolonged exposure at high temperatures. Initial studies were conducted to determine the root cause of tool failures in a number of applications. Results show that tool failures vary and depend on the operating environment under which they are used. Major root cause failures include (1) thermal softening, (2) fatigue and (3) tool erosion, all of which are affected by process boundary conditions such as lubrication, cooling, process speed, etc. While thermal management is a key to addressing tooling failures, it was clear that new tooling materials with superior high temperature strength could provide improved manufacturing efficiencies. These efficiencies are based on the use of functionally graded materials (FGM), a new subset of hybrid tools with customizable properties that can be fabricated using advanced powder metallurgy manufacturing technologies. Modeling studies of the various hot forming processes helped identify the effect of key variables such as stress, temperature and cooling rate and aid in the selection of tooling materials for specific applications. To address the problem of high temperature strength, several advanced powder metallurgy nickel and cobalt based alloys were selected for evaluation. These materials were manufactured into tooling using two relatively new consolidation processes. One process involved laser powder deposition (LPD) and the second involved a solid state dynamic powder consolidation (SSDPC) process. These processes made possible functionally graded materials (FGM) that resulted in shaped tooling that was monolithic, bi-metallic or substrate coated. Manufacturing of tooling with these processes was determined to be robust and consistent for a variety of materials. Prototype and production testing of FGM tooling showed the

  7. Material characterization of a polyester resin system for the pultrusion process

    DEFF Research Database (Denmark)

    Baran, Ismet; Akkerman, Remko; Hattel, Jesper Henri

    2014-01-01

    to develop a cure kinetics model which accurately predicts the cure rate evolutions and describes the curing behaviour of the resin over a wide range of different processing conditions. The viscosity of the resin is subsequently obtained from rheological experiments using a rheometer. Based on this, a resin....... The temperature- and curedependent elastic modulus of the resin system is determined using a dynamic mechanical analyzer (DMA) in tension mode. A cure hardening and thermal softening model is developed and a least squares non-linear regression analysis is performed. The variation in elastic modulus...... with temperature and phase transition is captured for a fully cured resin sample. © 2014 Elsevier Ltd. All rights reserved....

  8. Effect Of Fly Ash Filler To Dielectric Properties Of The Insulator Material Of Silicone Rubber And Epoxy Resin

    Directory of Open Access Journals (Sweden)

    Ikhlas Kitta

    2015-08-01

    Full Text Available Currently many operated the coal fired power plant to meet the energy needs of the worlds electricity. But the coal fired power plant produces waste that can pollute the environment such as fly ash and bottom ash so requires management to not cause environmental problems because coal fly ash classified as a hazardous waste. Fly ash has a particle size that is very smooth and of some literature research done previously fly ash coal containing silica SiO2 alumina Al2O3 titanium dioxide TiO2 magnesium oxide MgO and zinc oxide ZnO are potentially as filler that are likely to be used as a mixture of silicone rubber and epoxy resin for electrical insulators. So this research theme was engineering insulation materials by utilizing waste coal fly ash. The purpose of this study was to obtain performance characteristics of waste coal fly ash as filler in silicon rubber and epoxy resin. To achieve these objectives the activities that have been done is examined the effects of the use of fly ash as filler in silicone rubber material and epoxy resin. Parameters measured were dielectric strength and relative permittivity. The result of this research is the dielectric strength of silicone rubber rose with increasing quantity of fly ash. Conversely in epoxy resin dielectric strength decreases with increasing quantity of fly ash. Furthermore the measurement results relative permittivity where the value of the relative permittivity of silicon rubber swell if it is filled with fly ash as well as epoxy resin which has a value of permittivity relative to the concentration of fly ash filler material is linear.

  9. Clinical application of removable partial dentures using thermoplastic resin. Part II: Material properties and clinical features of non-metal clasp dentures.

    Science.gov (United States)

    Fueki, Kenji; Ohkubo, Chikahiro; Yatabe, Masaru; Arakawa, Ichiro; Arita, Masahiro; Ino, Satoshi; Kanamori, Toshikazu; Kawai, Yasuhiko; Kawara, Misao; Komiyama, Osamu; Suzuki, Tetsuya; Nagata, Kazuhiro; Hosoki, Maki; Masumi, Shin-ichi; Yamauchi, Mutsuo; Aita, Hideki; Ono, Takahiro; Kondo, Hisatomo; Tamaki, Katsushi; Matsuka, Yoshizo; Tsukasaki, Hiroaki; Fujisawa, Masanori; Baba, Kazuyoshi; Koyano, Kiyoshi; Yatani, Hirofumi

    2014-04-01

    This position paper reviews physical and mechanical properties of thermoplastic resin used for non-metal clasp dentures, and describes feature of each thermoplastic resin in clinical application of non-metal clasp dentures and complications based on clinical experience of expert panels. Since products of thermoplastic resin have great variability in physical and mechanical properties, clinicians should utilize them with careful consideration of the specific properties of each product. In general, thermoplastic resin has lower color-stability and higher risk for fracture than polymethyl methacrylate. Additionally, the surface of thermoplastic resin becomes roughened more easily than polymethyl methacrylate. Studies related to material properties of thermoplastic resin, treatment efficacy and follow-up are insufficient to provide definitive conclusions at this time. Therefore, this position paper should be revised based on future studies and a clinical guideline should be provided. Copyright © 2014 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  10. Effect of chemical disinfectants and repair materials on the transverse strength of repaired heat-polymerized acrylic resin.

    Science.gov (United States)

    Ellakwa, Ayman E; El-Sheikh, Ali M

    2006-01-01

    The purpose of this study was to evaluate both the effects of immersion in different chemical disinfectant solutions and the type of repair material on the transverse strength of repaired heat-polymerized acrylic resin. A total of 110 rectangular specimens (65 x 10 x 3 mm) of heat-polymerized acrylic resin (Triplex) were fabricated. After polymerization, the specimens were polished, then stored in distilled water at 37 degrees C for 1 week. The specimens were divided into 11 groups (n = 10) coded A to K. Specimens of Group A remained intact (control). The specimens of Groups C to F and Groups H to K were immersed in the following chemical disinfectant solutions (1%, 2.5%, and 5.25% sodium hypochlorite and 2% glutaraldehyde, respectively) for 10 minutes. The specimens of all groups except those of Group A were sectioned in the middle to create 10 mm gaps and repaired with the same resin (Groups B to F) and autopolymerizing acrylic resin (Groups G to K). The specimens of Groups C to F and Groups H to K were again immersed in the disinfectant solutions in the same sequence. The transverse strength (N/mm(2)) was tested for failure in a universal testing machine, at a crosshead speed of 5 mm/min. Two-way analysis of variance (ANOVA) was performed to evaluate the effects of both the disinfectant solutions and repair materials on the transverse strength of repaired specimens. All data were statistically analyzed using one-way analysis of variance followed by Tukey's test at 95% confidence level. The repaired specimens treated with/without disinfectant solutions showed similar (p > 0.05) transverse strength values. No differences (p > 0.05) were detected among the repaired specimens either with heat-polymerized or autopolymerizing acrylic resins. The intact specimens showed transverse strength values (86.9 +/- 11.8) significantly higher (p disinfectants for the immersion period tested (10 min). The repair material, either heat-polymerized or autopolymerizing acrylic resin

  11. Tribological behavior of CrN-coated Cr-Mo-V steels used as die materials

    Science.gov (United States)

    Çelik, Gülşah Aktaş; Polat, Şeyda; Atapek, Ş. Hakan

    2017-12-01

    DIN 1.2343 and 1.2367 steels are commonly used as die materials in aluminum extrusion, and single/duplex/multi-coatings enhance their surface properties. The design of an appropriate substrate/coating system is important for improving the tribological performance of these steels under service conditions because the load-carrying capacity of the system can be increased by decreasing the plastic deformation of the substrate. In this study, the tribological behavior of CrN-coated Cr-Mo-V steels (DIN 1.2343, 1.2367, and 1.2999 grades) was investigated using different setups and tribological pairs at room and elevated temperatures. The aim of this study was to reveal the wear resistance of a suggested system (1.2999/CrN) not yet studied and to understand both the wear and the failure characteristics of coated systems. The results showed that (i) among the steels studied, the DIN 1.2999 grade steel exhibited the lowest friction coefficient because it had the highest load-carrying capacity as a result of secondary hardening at elevated temperatures; (ii) at room temperature, both abrasive tracks and adhesive layers were observed on the worn surfaces; and (iii) a combination of chemical reactions and progressive oxidation caused aluminum adhesion on the worn surface, and the detachment of droplets and microcracking were the characteristic damage mechanisms at high temperatures.

  12. Structural materialization of stainless steel molds and dies by the low temperature high density plasma nitriding

    Directory of Open Access Journals (Sweden)

    Aizawa Tatsuhiko

    2015-01-01

    Full Text Available Various kinds of stainless steels have been widely utilized as a mold substrate material for injection molding and as a die for mold-stamping and direct stamping processes. Since they suffered from high temperature transients and thermal cycles in practice, they must be surface-treated by dry and wet coatings, or, by plasma nitriding. Martensitic stainless steel mold was first wet plated by the nickel phosphate (NiP, which was unstable at the high temperature stamping condition; and, was easy to crystalize or to fracture by itself. This issue of nuisance significantly lowered the productivity in fabrication of optical elements at present. In the present paper, the stainless steel mold was surface-treated by the low-temperature plasma nitriding. The nitrided layer by this surface modification had higher nitrogen solute content than 4 mass%; the maximum solid-solubility of nitrogen is usually 0.1 mass% in the equilibrium phase diagram. Owing to this solid-solution with high nitrogen concentration, the nitrided layer had high hardness of 1400 Hv within its thickness of 40 μm without any formation of nitrides after 14.4 ks plasma nitriding at 693 K. This nitrogen solid-solution treated stainless steel had thermal resistivity even at the mold-stamping conditions up to 900 K.

  13. Method development for the analysis of resinous materials with MALDI-FT-ICR-MS: novel internal standards and a new matrix material for negative ion mode.

    Science.gov (United States)

    Teearu, A; Vahur, S; Rodima, T; Herodes, K; Bonrath, W; Netscher, T; Tshepelevitsh, S; Trummal, A; Lõkov, M; Leito, I

    2017-09-01

    Matrix-assisted laser desorption/ionization (MALDI) is a mass spectrometry (MS) ionization technique suitable for a wide variety of sample types including highly complex ones such as natural resinous materials. Coupled with Fourier transform ion cyclotron resonance (FT-ICR) mass analyser, which provides mass spectra with high resolution and accuracy, the method gives a wealth of information about the composition of the sample. One of the key aspects in MALDI-MS is the right choice of matrix compound. We have previously demonstrated that 2,5-dihydroxybenzoic acid is suitable for the positive ion mode analysis of resinous samples. However, 2,5-dihydroxybenzoic acid was found to be unsuitable for the analysis of these samples in the negative ion mode. The second problem addressed was the limited choice of calibration standards offering a flexible selection of m/z values under m/z 1000. This study presents a modified MALDI-FT-ICR-MS method for the analysis of resinous materials, which incorporates a novel matrix compound, 2-aminoacridine for the negative ion mode analysis and extends the selection of internal standards with m/z negative (anions of four fluorine-rich sulpho-compounds) ion mode. The novel internal calibration compounds and matrix material were tested for the analysis of various natural resins and real-life varnish samples taken from cultural heritage objects. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  14. Effect of an adhesive resin luting agent on the dowel-head retention of three different core materials.

    Science.gov (United States)

    Aksoy, Gokhan; Cotert, H Serdar; Korkut, Levent

    2005-05-01

    A dowel-and-core restoration may fail due to failure at either the dowel-tooth or dowel head-core material interface. Long-term clinical success of a dowel-and-core restoration depends on retention of both the dowel to the tooth and the dowel head to the core material. Thus, strengthening of the dowel head-core interface is important. This study evaluated the retention between a prefabricated dowel and 3 different core materials with or without a dual-polymerized adhesive resin luting agent. Sixty prefabricated dowels (Gold Plated Anchorage Post) were divided into 3 groups (n=20) consisting of 1 of 3 core materials, amalgam (Standalloy F), light-polymerized resin composite (Clearfil Ray), or glass ionomer (Chelon-Silver). Each core group was divided into 2 subgroups (n=10), and a dual-polymerized adhesive resin luting agent (Panavia F) was applied to the dowel heads of 1 of these subgroups before application of the core material. The manufacturing procedure was standardized by using a plastic index (4.5-mm internal diameter and 5-mm height) and a custom-made dowel holder, which held the dowel head. Prepared specimens were stored in water at room temperature for 3 months and then loaded to fracture in a universal testing machine with a crosshead speed of 0.05 mm/min until failure. Bond strengths were recorded (MPa). Data were analyzed with 2-way analysis of variance (ANOVA) in a 2 x 3 factorial randomized design (alpha=.05). Afterward, core material differences were computed with 1-way ANOVA for both of the bonded and nonbonded groups. Post hoc multiple comparisons were made with the Dunnett C multiple range test. Dowel-head retention values (MPa) of the tested core materials (mean +/- SD) from the highest to the lowest were as follows: bonded amalgam core, 296.1 +/- 108; bonded composite core, 284.3 +/- 38.3; nonbonded composite core, 177.0 +/- 53.7; nonbonded amalgam core, 128.5 +/- 35.0; bonded glass-ionomer core (GIC), 128.0 +/- 24.5; nonbonded GIC, 61.8 +/- 13

  15. Effect of the properties of natural resin binder in a high friction composite material

    Directory of Open Access Journals (Sweden)

    S. Stephen Bernard

    2014-01-01

    Full Text Available In this paper, a high-friction composite material based on the combination of binder, friction modifiers, fibers and fillers is investigated. In the binder, up to 20% of phenol are replaced by cardanol with various weight ratios of 100/0, 95/5, 90/10, 85/15, 80/20. Cardanol may react both through the phenolic group and the double bond of the side chain yielding addition, condensation and polymerisation reactions that allow the synthesis of tailor-made products and polymers of high value. In the present work, mechanical, thermal and wear characteristics of cardanol based phenolic resin with organic ingredients were manufactured and tested. An analysis of microstructure characteristics of composites was carried out using scanning electron microscope. The effect of environment on the composite was investigated in water, salty water and oil. The results showed that the addition of cardanol reduces the wear resistance and increases the compressibility which reduces the noise propensity.

  16. In-office bleaching efficacy on stain removal from CAD/CAM and direct resin composite materials.

    Science.gov (United States)

    Alharbi, Amal; Ardu, Stefano; Bortolotto, Tissiana; Krejci, Ivo

    2018-01-01

    To evaluate the efficacy of in-office bleaching on stain removal from stained resin composite and ceramic computer-assisted design/computer-assisted manufacturing (CAD/CAM) blocks and direct resin composites. Forty disk-shaped samples were fabricated from each of nine materials: six CAD/CAM (VITABLOCS Mark II, Paradigm MZ100, Exp Vita Hybrid Ceramic, VITA ENAMIC, Exp Kerr, and LAVA Ultimate) and three direct resin composites (Filtek Supreme, Venus Diamond, and Filtek Silorane). Samples were randomly divided into five groups (n = 8), each stained with a particular staining solution. Using a calibrated spectrophotometer and a black background, L*a*b* values were assessed before and after 120 days of staining. Samples were subjected to in-office bleaching using 40% hydrogen peroxide gel for one hour. At subsequent assessment, color change (ΔE) was calculated as the difference between L*a*b* values. Both ANOVA and the Duncan test were used to identify differences between groups (α = 0.05). Bleaching resulted in significant differences in ΔE values for all materials (P < .001). Bleaching efficacy was highly influenced by material composition and staining solution. Residual color values after bleaching for ceramic and hybrid ceramics ranged from -0.49 to 2.35, within the clinically acceptable maximum of 3.3. Values after bleaching for resin-based CAD/CAM ranged from -0.7 to 7.08 while direct resin composites values ranged from -1.47 to 25.13. Coffee left the greatest residual color on all materials. Based on material nature, 40% hydrogen peroxide bleaching can remove staining. The new resin-based CAD/CAM blocks showed promising results in terms of color stability. Bleaching using 40% hydrogen peroxide can be an effective method to remove stains from dental restorations. In this way, restoration replacement as a result of discoloration may no longer be necessary. © 2017 Wiley Periodicals, Inc.

  17. Evaluation of Flexural Strength of Thermocycled Interim Resin Materials Used in Prosthetic Rehabilitation- An In-vitro Study

    Science.gov (United States)

    Kadiyala, Krishna Kishore; Anne, Gopinadh; Anche, Sampath Chowdary; Chiramana, Sandeep; Muvva, Suresh Babu; Zakkula, Srujana; Jyothula, Ravi Rakesh Dev

    2016-01-01

    Introduction Provisional restoration is an analytical component of fixed prosthodontics serving as a ground plan for the design of fixed dental prosthesis. Flexural strength is critical in case of long standing fixed dental prosthesis, to appreciate success of full mouth rehabilitation cases and temporomandibular joint dysfunction therapies. Aim The present study was to evaluate the flexural strength of different provisional restorative resins used for prosthetic rehabilitation. Materials and Methods Forty identical samples (n=10 for each material) measuring 25mm×2mm×2mm according to ADA/ANSI specification no. 27 were fabricated using autopolymerizing Poly Methyl Methacrylate (PMMA) (Group A); heat activated PMMA (Group B); autopolymerizing Bis-GMA composite resin (Group C) and light activated Urethane Dimethacrylate Resin (UDMA) (Group D). For 14 days all these samples were stored in artificial saliva. Ten samples from each material were subjected to thermal cycling for 2500 cycles (5°C to 55°C). Later, a standard three point bending test was conducted on all the specimens with a universal testing machine at a crosshead speed of 0.75mm/min. Statistical analysis used included Kruskal-Wallis and Mann-Whitney U test. Results The mean flexural strength of specimens confirmed higher flexural strength for Group C (102.98 Mpa) followed by Group B (91.86 Mpa), Group A (79.13 Mpa) and Group D (60.01 Mpa). There were significant differences between any two materials tested (p treatment. PMID:27790588

  18. Cell death effects of resin-based dental material compounds and mercurials in human gingival fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    Reichl, Franz-Xaver [Walther-Straub-Institute of Pharmacology and Toxicology, Munich (Germany); Ludwig-Maximilians-University, Department of Operative Dentistry and Periodontology, Munich (Germany); Esters, Magali; Simon, Sabine; Seiss, Mario [Walther-Straub-Institute of Pharmacology and Toxicology, Munich (Germany); Kehe, Kai [Bundeswehr Institute of Pharmacology and Toxicology, Munich (Germany); Kleinsasser, Norbert [University of Regensburg, Head and Neck Surgery, Department of Otolaryngology, Regensburg (Germany); Folwaczny, Matthias; Glas, Juergen; Hickel, Reinhard [Ludwig-Maximilians-University, Department of Operative Dentistry and Periodontology, Munich (Germany)

    2006-06-15

    In order to test the hypothesis that released dental restorative materials can reach toxic levels in human oral tissues, the cytotoxicities of the resin-based dental (co)monomers hydroxyethylmethacrylate (HEMA), triethyleneglycoldimethacrylate (TEGDMA), urethanedimethacrylate (UDMA), and bisglycidylmethacrylate (BisGMA) compared with methyl mercury chloride (MeHgCl) and the amalgam component mercuric chloride (HgCl{sub 2}) were investigated on human gingival fibroblasts (HGF) using two different test systems: (1) the modified XTT-test and (2) the modified H 33342 staining assay. The HGF were exposed to various concentrations of the test-substances in all test systems for 24 h. All tested (co)monomers and mercury compounds significantly (P<0.05) decreased the formazan formation in the XTT-test. EC{sub 50} values in the XTT assay were obtained as half-maximum-effect concentrations from fitted curves. Following EC{sub 50} values were found (mean [mmol/l]; s.e.m. in parentheses; n=12; * significantly different to HEMA): HEMA 11.530 (0.600); TEGDMA* 3.460 (0.200); UDMA* 0.106 (0.005); BisGMA* 0.087 (0.001); HgCl{sub 2}* 0.013 (0.001); MeHgCl* 0.005 (0.001). Following relative toxicities were found: HEMA 1; TEGDMA 3; UDMA 109; BisGMA 133; HgCl{sub 2} 887; MeHgCl 2306. A significant (P<0.05) increase of the toxicity of (co)monomers and mercurials was found in the XTT-test in the following order: HEMA < TEGDMA < UDMA < BisGMA < HgCl{sub 2} < MeHgCl. TEGDMA and MeHgCl induced mainly apoptotic cell death. HEMA, UDMA, BisGMA, and HgCl{sub 2} induced mainly necrotic cell death. The results of this study indicate that resin composite components have a lower toxicity than mercury from amalgam in HGF. HEMA, BisGMA, UDMA, and HgCl{sub 2} induced mainly necrosis, but it is rather unlikely that eluted substances (solely) can reach concentrations, which might induce necrotic cell death in the human physiological situation, indicating that other (additional) factors may be involved in

  19. A new approach to influence contact angle and surface free energy of resin-based dental restorative materials.

    Science.gov (United States)

    Rüttermann, Stefan; Trellenkamp, Taina; Bergmann, Nora; Raab, Wolfgang H-M; Ritter, Helmut; Janda, Ralf

    2011-03-01

    The purpose of the present study was to identify novel delivery systems and active agents which increase the water contact angle and reduce the surface free energy when added to resin-based dental restorative materials. Two delivery systems based on zeolite or novel polymeric hollow beads (Poly-Pore), loaded with two low surface tension active agents (hydroxy functional polydimethylsiloxane and polydimethylsiloxane) or a polymerizable active agent (silicone polyether acrylate) were used to modify commonly formulated experimental dental resin composites. The non-modified resin was used as a standard (ST). Flexural strength, flexural modulus, water sorption, solubility, polymerization shrinkage, surface roughness Ra, contact angle θ, total surface free energy γS, and the apolar γSLW, polar γSAB, Lewis acid γS+ and base γS- components, and the active agents surface tensions γL were determined (Ptension active agents were found not to influence the physical properties but to significantly increase the water contact angle and thus reduce surface free energy of dental resin composites. Copyright © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  20. Contact angle and surface free energy of experimental resin-based dental restorative materials after chewing simulation.

    Science.gov (United States)

    Rüttermann, Stefan; Beikler, Thomas; Janda, Ralf

    2014-06-01

    To investigate contact angle and surface free energy of experimental dental resin composites containing novel delivery systems of polymeric hollow beads and low-surface tension agents after chewing simulation test. A delivery system of novel polymeric hollow beads differently loaded with two low-surface tension agents was used in different amounts to modify commonly formulated experimental dental resin composites. The non-modified resin was used as standard. Surface roughness Ra, contact angle Θ, total surface free energy γS, its apolar γS(LW), polar γS(AB), Lewis acid γS(+) and base γS(-) terms were determined and the results prior to and after chewing simulation test were compared. Significance was phollow beads highly loaded with low-surface tension agents were found to significantly increase contact angle and thus to reduce surface free energy of experimental dental resin composites prior to and after chewing simulation test. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  1. [Determination of normal temperature properties of refractory die material compatible with slip casting core of sintered titanium powder].

    Science.gov (United States)

    Kuang, X; Liao, Y; Chao, Y; Wang, H

    1999-05-01

    The refractory die is the precondition for developing slip casting core of sintered powder. This study is to determine the normal temperature properties of the refractory die material compatible with slip casting core. to mix the die material at five different ratios (8/1, 7.5/1, 7/1, 6.5/1, and 6/1) and measure their solidification time with self-manufactured Vicker's needle; to prepare five cylindrical specimens (phi 10 x 15 mm) in different drying time for determining their compressive strength, and then to let another five specimens fire at 1000 degrees C four times for measuring the residual compressive strength at room temperature. The setting time was 16.25 minutes (7.5/1), and the lower the powder-liquid ratio, the longer the setting time. The normal compressive strength was 25.32 MPa (drying 24 hours), while the longer the drying time, the higher the compressive strength achieved (P die material meet the demand of slip casting core of sintered powder.

  2. Method for removing contaminants from plastic resin

    Science.gov (United States)

    Bohnert, George W [Harrisonville, MO; Hand, Thomas E [Lee's Summit, MO; DeLaurentiis, Gary M [Jamestown, CA

    2008-12-09

    A resin recycling method that produces essentially contaminant-free synthetic resin material in an environmentally safe and economical manner. The method includes receiving the resin in container form. The containers are then ground into resin particles. The particles are exposed to a solvent, the solvent contacting the resin particles and substantially removing contaminants on the resin particles. After separating the particles and the resin, a solvent removing agent is used to remove any residual solvent remaining on the resin particles after separation.

  3. Evaluation of adhesive bonding of lithium disilicate ceramic material with duel cured resin luting agents.

    Science.gov (United States)

    Lambade, Dipti Pravin; Gundawar, Sham M; Radke, Usha M

    2015-02-01

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

  4. Physical Properties of a New Sonically Placed Composite Resin Restorative Material

    Science.gov (United States)

    2013-06-06

    microleakage with resulting pulpal sensitivity, staining , and recurrent caries.10 Additionally, incomplete curing of composite resins is associated...minimal stress.10 However, increased demand has led to greater use on posterior teeth , where considerable mechanical challenges occur under function...was placed on a plastic-strip-covered glass slide on a standard white background. The composite resin was injected into the mold and a plastic strip

  5. Substitute materials of furfuryl alcohol in furan resin used for foundry and their technical properties

    Directory of Open Access Journals (Sweden)

    Li Yingmin

    2009-11-01

    Full Text Available Based on a special synthesis process of furan resin, the furfuryl alcohol (FA, the main component of typical no-bake furan resins is substituted by ethanol and xylitol mother liquor which is relatively low price and chemically active. Through orthogonal test, the optimal amount of xylitol liquor, ethanol and modifi er has been determined. Finally, the test results on technical properties show that the performance can meet the production requirement well, which indicate a success in this substituting attempt.

  6. Thermal expansion and swelling of cured epoxy resin used in graphite/epoxy composite materials

    Science.gov (United States)

    Adamson, M. J.

    1980-01-01

    The paper presents results of experiments in which the thermal expansion and swelling behavior of an epoxy resin system and two graphite/epoxy composite systems exposed to water were measured. It was found that the cured epoxy resin swells by an amount slightly less than the volume of the absorbed water and that the swelling efficiency of the water varies with the moisture content of the polymer. Additionally, the thermal expansion of cured epoxy resin that is saturated with water is observed to be more than twice that of dry resin. Results also indicate that cured resin that is saturated with 7.1% water at 95 C will rapidly increase in moisture content to 8.5% when placed in 1 C water. The mechanism for this phenomenon, termed reverse thermal effect, is described in terms of a slightly modified free-volume theory in conjunction with the theory of polar molecule interaction. Nearly identical behavior was observed in two graphite/epoxy composite systems, thus establishing that this behavior may be common to all cured epoxy resins.

  7. Microleakage of conventional, resin-modified, and nano-ionomer glass ionomer cement as primary teeth filling material

    Directory of Open Access Journals (Sweden)

    Dita Madyarani

    2014-12-01

    Full Text Available Background: Glass ionomer cements are one of many dental materials that widely used in pediatric dentistry due to their advantage of fluoride release and chemical bond to tooth structure. Adherence of the filling material to the cavity walls is one of the most important characteristic that need to be examined its effect on microleakage. Purpose: This study was conducted to examine the microleakage of nano-ionomer glass ionomer cement compared with the conventional and resin-modified glass ionomer cements. Methods: Standard class V cavities sized 3 mm x 2 mm x 2 mm were made on a total of 21 extracted maxillary primary canine teeth and restored with the conventional, resin-modified, dan nano-ionomer glass ionomer cements. All the teeth were immersed in a 2% methylene blue dye for 4 hours. The depth of dye penetration was assessed using digital microscope after sectioning the teeth labio-palatally. The results were statistically analyzed using Kruskal-Wallis test. Results: All type of glass ionomer material showed microleakage. Conventional glass ionomer cement demonstrated the least microleakage with mean score 1.29. the resin-modified glass ionomer cements (mean score 1.57 and nano-ionomer glass ionomer cement (mean score 2.57. Conclusion: The conventional glassionomer, resin modified glassionomer, and nano-ionomer glassionomer showed micro leakage as filling material in primary teeth cavity. The micro leakage among three types was not significant difference. All three material were comparable in performance and can be used for filling material but still needs a coating material to fill the microleakage.Latar belakang: Semen ionomer kaca adalah salah satu dari banyak bahan gigi yang banyak digunakan dalam praktek kedokteran gigi anak karena bahan tersebut merilis fluoride dan berikatan kimia dengan struktur gigi. Perlekatan bahan tumpatan pada dinding kavitas adalah salah satu karakteristik paling penting yang perlu diteliti efeknya terhadap

  8. Bond strength of novel CAD/CAM restorative materials to self-adhesive resin cement: the effect of surface treatments.

    Science.gov (United States)

    Elsaka, Shaymaa E

    2014-12-01

    To evaluate the effect of different surface treatments on the microtensile bond strength (μTBS) of novel CAD/CAM restorative materials to self-adhesive resin cement. Two types of CAD/CAM restorative materials (Vita Enamic [VE] and Lava Ultimate [LU]) were used. The specimens were divided into five groups in each test according to the surface treatment performed; Gr 1 (control; no treatment), Gr 2 (sandblasted [SB]), Gr 3 (SB+silane [S]), Gr 4 (hydrofluoric acid [HF]), and Gr 5 (HF+S). A dual-curing self-adhesive resin cement (Bifix SE [BF]) was applied to each group for testing the adhesion after 24 h of storage in distilled water or after 30 days using the μTBS test. Following fracture testing, specimens were examined with a stereomicroscope and SEM. Surface roughness and morphology of the CAD/CAM restorative materials were characterized after treatment. Data were analyzed using ANOVA and Tukey's test. The surface treatment, type of CAD/CAM restorative material, and water storage periods showed a significant effect on the μTBS (p0.05). On the other hand, for the VE/BF system, surface treatment with HF+S showed higher bond strength values compared with SB and HF surface treatments (pmaterials was modified after treatments. The effect of surface treatments on the bond strength of novel CAD/CAM restorative materials to resin cement is material dependent. The VE/BF CAD/CAM material provided higher bond strength values compared with the LU/BF CAD/CAM material.

  9. The impact of three strains of oral bacteria on the surface and mechanical properties of a dental resin material.

    Science.gov (United States)

    Gregson, Karen S; Shih, Han; Gregory, Richard L

    2012-08-01

    The purpose of this study was to determine if three strains of bacteria could impact the mechanical or surface properties of a dental resin material. Resin material specimens were incubated at 37°C in sterile saline, tryptic soy broth supplemented with sucrose (TSBS), or TSBS inoculated with Streptococcus mutans, Streptococcus gordonii, or Streptococcus sanguis. The specimens were subjected to Fourier transform infrared spectroscopy before and after incubation. The flexural strength test was performed once a week for 6 weeks. Microhardness and scanning electron microscopy (SEM) was performed on specimens at 1 and 6 weeks. Differences in the area under the carbonyl peak were statistically significant for the specimens incubated in the media inoculated with either S. mutans or S. gordonii. To determine why S. sanguis did not produce changes as the other bacteria did, triethylene glycol dimethacrylate, methacrylic acid, and triethylene glycol were added to bacterial cultures at increasing concentrations. Both methacrylic acid and triethylene glycol reduced the number of colony-forming units of S. sanguis. Specimens incubated in TSBS, saline or in culture with S. sanguis demonstrated a decrease in peak stress in week 1 of the flexure strength test. SEM demonstrated that surface topology changed for those specimens incubated in culture with S. mutans or S. gordonii. The changes in surface topology demonstrated here could contribute to the secondary caries and changes in esthetic properties seen clinically with the use of resin materials in dental restorations.

  10. Current status of visible light activation units and the curing of light-activated resin-based composite materials.

    Science.gov (United States)

    Santini, Ario

    2010-05-01

    Light activation units are standard items of equipment in dental practice. It is essential to understand the many factors which affect the polymerization of light-activated resin composite materials and the choice of a light curing unit. In this respect, the development of high-intensity halogen and light-emitting diode (LED) light curing units (LCUs), many with multiple curing modes, has revolutionized light curing techniques. This article reviews visible light activation unit design and development. Factors influencing the effective use of LCUs and polymerization of resin-based composite materials are discussed, as are the steps which should be taken to maintain the efficiency of units in clinical use. Many LCUs produce lower output intensities than stated by the manufacturer. Newer high power LEDs may present as much of a heat problem as high power quartz tungsten halogen lamps (QTHs).The manufacturer's data should be followed to ensure that the emission spectra of the unit is compatible with the photo-initiator in the resin-based composite material.

  11. Resin-modified glass-ionomer cements versus resin-based materials as fissure sealants: a meta-analysis of clinical trials.

    Science.gov (United States)

    Yengopal, V; Mickenautsch, S

    2010-02-01

    To appraise quantitatively current evidence regarding the caries-preventing effect of resin-modified glass-ionomer cement (RM-GIC) fissure sealants in comparison to that of resin-based fissure sealants. Systematic review with meta-analysis. 8 Anglophone databases and 2 Lusophone databases were searched until 15 April 2009, using a pre-determined search strategy. Clinical trials were considered for inclusion if their titles/abstracts were relevant to the topic, published in English, Portuguese or Spanish and had a two-arm longitudinal study design. The outcome measure of the caries-preventive effect was caries absence on sealed teeth. Two reviewers independently extracted data from the accepted articles in order to complete a 2x2 table for meta-analysis. The unit of interest was the tooth, and the number of caries-free teeth (n) at the end of each time interval (6, 12 and 24 months) was compared against the total number of evaluated teeth (N). Datasets were assessed for their clinical and methodological heterogeneity, following Cochrane guidelines, and only homogeneous datasets were combined for meta-analysis, using a random effects model (RevMan 4.2). Differences in the caries-preventive effect were computed on the basis of the combined Relative Risk (RR) with 95% confidence interval (CI). Of the 212 articles identified, only 6 trials were included. From these, 19 separate datasets were extracted. For the pooled data, equivalent caries-preventive effects were observed at 6 months (RR= 0.98, 95% CI 0.95- 1.00; p = 0.08); 12 months (RR=1.00, 95% CI 0.96-1.04, p = 0.99) and 24 months (RR=1.01, 95% CI 0.84-1.21, p = 0.91). The 36-month data (not pooled) favoured resin-based sealants (RR 0.93, 95% CI 0.88-0.97, p = 0.002). This meta-analysis found no conclusive evidence that either material was superior to the other in preventing dental caries.

  12. In vitro toothbrushing abrasion of dental resin composites: packable, microhybrid, nanohybrid and microfilled materials

    Directory of Open Access Journals (Sweden)

    Rafael Ratto de Moraes

    2008-06-01

    Full Text Available This study evaluated weight loss and surface roughening after toothbrushing of different resin composites: one packable (Solitaire 2, Heraeus Kulzer, one microhybrid (Charisma, Heraeus Kulzer, one nanohybrid (Simile, Pentron and one microfilled (Durafill VS, Heraeus Kulzer. Cylindrical specimens (n = 20 were prepared. Half of the samples were submitted to 60,000 strokes, at 4 Hz, with a dentifrice-water slurry. Control samples (n = 10 remained stored at 37°C. Pre- and post-abrasion parameters for weight (mg and surface roughness (Ra, µm were determined on an analytical balance and a surface profilometer. Data were separately submitted to Repeated Measures ANOVA and Tukey's test (a = 0.05. Percentages of weight loss were analyzed by ANOVA and Tukey's test (a = 0.05. The relationship between both evaluations was assessed by Pearson's test (a = 0.05. The means (% for weight loss (standard deviation were 0.65(0.2, 0.93(0.2, 1.25(0.6 and 1.25(0.4 for Simile, Durafill, Charisma and Solitaire, respectively. Baseline roughness means ranged from 0.065(0.01, 0.071(0.01, 0.066(0.02 and 0.074(0.01 for Simile, Durafill, Charisma and Solitaire, respectively, to 0.105(0.04, 0.117(0.03, 0.161(0.03 and 0.214(0.07 after testing. The composites with larger fillers presented higher weight loss and roughening than the finer materials (p < 0.05. For both evaluations, control specimens showed no significant alteration. No significant relationship between loss of weight and roughness alteration was detected (r = 0.322, p = 0.429.

  13. Effect of LED-LCU light irradiance distribution on mechanical properties of resin based materials

    Energy Technology Data Exchange (ETDEWEB)

    Magalhães Filho, T.R.; Weig, K.M. [Faculdade de Odontologia, Universidade Federal Fluminense, Rua São Paulo 28, CEP 24020-150 Niterói (Brazil); Engenharia Metalúrgica e de Materiais (COPPE), Universidade Federal do Rio de Janeiro, CP 68505, CEP: 21941-972 Rio de Janeiro (Brazil); Costa, M.F. [Engenharia Metalúrgica e de Materiais (COPPE), Universidade Federal do Rio de Janeiro, CP 68505, CEP: 21941-972 Rio de Janeiro (Brazil); Werneck, M.M. [Engenharia Elétrica (COPPE), Universidade Federal do Rio de Janeiro, CP 68504, CEP: 21941-972 Rio de Janeiro (Brazil); Barthem, R.B. [Instituto de Física, Universidade Federal do Rio de Janeiro, CP 68528, CEP: 21941-972 Rio de Janeiro (Brazil); Costa Neto, C.A., E-mail: celio@metalmat.ufrj.br [Engenharia Metalúrgica e de Materiais (COPPE), Universidade Federal do Rio de Janeiro, CP 68505, CEP: 21941-972 Rio de Janeiro (Brazil)

    2016-06-01

    The objective of this study is to analyze the light power distribution along the tip end of the light guide of three LED-LCUs (Light Curing Units) and to evaluate its effect on the mechanical properties of a polymer based dental composite. Firstly, the light power distribution over the whole area of LED-LCU light guide surface was analyzed by three methods: visual projection observation, spectral measurement and optical spectral analysis (OSA). The light power distribution and the total irradiance were different for the three LEDs used, but the wavelength was within the camphorquinone absorption spectrum. The use of a blank sheet was quite on hand to make a qualitative analysis of a beam, and it is costless. Secondly, specimens of a hybrid composite with approximately 8 mm diameter and 2 mm thickness were produced and polymerized by 20 s exposition time to each LED-LCU. Thirdly, the elastic modulus (E) and hardness (HV) were measured throughout the irradiated area by instrumented micro-indentation test (IIT), allowing to correlate localized power and mechanical properties. Both E and HV showed to be very sensitive to local power and wavelength dependent, but they followed the beam power profile. It was also shown that the mechanical properties could be directly correlated to the curing process. Very steep differences in mechanical properties over very short distances may impair the material performance, since residual stresses can easily be built over it. - Highlights: • A resin based composite (RBC) was polymerized by three different Light Emitting Diodes. • Each LED had its beam profile visually, wavelength and power analyzed. • The effective polymerization power (EPP) varied from 28% to 52% of the total beam power. • Wavelength seems to be as relevant as power in the light curing process. • Mechanical properties depend on the simultaneous effect of wavelength and power.

  14. Influence of different surface treatments on bond strength of novel CAD/CAM restorative materials to resin cement.

    Science.gov (United States)

    Kömürcüoğlu, Meltem Bektaş; Sağırkaya, Elçin; Tulga, Ayça

    2017-12-01

    To evaluate the effects of different surface treatments on the bond strength of novel CAD/CAM restorative materials to resin cement by four point bending test. The CAD/CAM materials under investigation were e.max CAD, Mark II, Lava Ultimate, and Enamic. A total of 400 bar specimens (4×1.2×12 mm) (n=10) milled from the CAD/CAM blocks underwent various pretreatments (no pretreatment (C), hydrofluoric acid (A), hydrofluoric acid + universal adhesive (Scotchbond) (AS), sandblasting (Sb), and sandblasting + universal adhesive (SbS)). The bars were luted end-to-end on the prepared surfaces with a dual curing adhesive resin cement (Variolink N, Ivoclar Vivadent) on the custom-made stainless steel mold. Ten test specimens for each treatment and material combination were performed with four point bending test method. Data were analyzed using ANOVA and Tukey's test. The surface treatment and type of CAD/CAM restorative material showed a significant effect on the four point bending strength (FPBS) ( P CAD/CAM restorative materials was modified after treatments. The surface treatment of sandblasting or HF acid etching in combination with a universal adhesive containing MDP can be suggested for the adhesive cementation of the novel CAD/CAM restorative materials.

  15. Characteristics of low polymerization shrinkage flowable resin composites in newly-developed cavity base materials for bulk filling technique.

    Science.gov (United States)

    Nitta, Keiko; Nomoto, Rie; Tsubota, Yuji; Tsuchikawa, Masuji; Hayakawa, Tohru

    2017-11-29

    The purpose of this study was to evaluate polymerization shrinkage and other physical properties of newly-developed cavity base materials for bulk filling technique, with the brand name BULK BASE (BBS). Polymerization shrinkage was measured according to ISO/FDIS 17304. BBS showed the significantly lowest polymerization shrinkage and significantly higher depth of cure than conventional flowable resin composites (p<0.05). The Knoop hardness, flexural strength and elastic modulus of that were significantly lower than conventional flowable resin composites (p<0.05). BBS had the significantly greatest filler content (p<0.05). SEM images of the surface showed failure of fillers. The lowest polymerization shrinkage was due to the incorporation of a new type of low shrinkage monomer, which has urethane moieties. There were no clear correlations between inorganic filler contents and polymerization shrinkage, flexural strength and elastic modulus. In conclusion, the low polymerization shrinkage of BBS will be useful for cavity treatment in dental clinics.

  16. Temperature changes under demineralized dentin during polymerization of three resin-based restorative materials using QTH and LED units

    Directory of Open Access Journals (Sweden)

    Sayed-Mostafa Mousavinasab

    2014-08-01

    Full Text Available Objectives Light-curing of resin-based materials (RBMs increases the pulp chamber temperature, with detrimental effects on the vital pulp. This in vitro study compared the temperature rise under demineralized human tooth dentin during light-curing and the degrees of conversion (DCs of three different RBMs using quartz tungsten halogen (QTH and light-emitting diode (LED units (LCUs. Materials and Methods Demineralized and non-demineralized dentin disks were prepared from 120 extracted human mandibular molars. The temperature rise under the dentin disks (n = 12 during the light-curing of three RBMs, i.e. an Ormocer-based composite resin (Ceram. X, Dentsply DeTrey, a low-shrinkage silorane-based composite (Filtek P90, 3M ESPE, and a giomer (Beautifil II, Shofu GmbH, was measured with a K-type thermocouple wire. The DCs of the materials were investigated using Fourier transform infrared spectroscopy. Results The temperature rise under the demineralized dentin disks was higher than that under the non-demineralized dentin disks during the polymerization of all restorative materials (p 0.05. Conclusions Although there were no significant differences in the DCs, the temperature rise under demineralized dentin disks for the silorane-based composite was higher than that for dimethacrylate-based restorative materials, particularly with QTH LCU.

  17. Metallurgical aspects of welding. Ferrous and nonferrous materials. 4. new rev. ed.; Die Metallurgie des Schweissens. Eisenwerkstoffe - nichteisenmetallische Werkstoffe

    Energy Technology Data Exchange (ETDEWEB)

    Schulze, Guenter

    2010-07-01

    This is the fourth edition of the standard work on welding metallurgy. The various problems of ferrous and nonferrous materials in the welding process are presented in great detail. In order to prevent corrosion of welded constructions, metallurgical properties and problems of all important technical materials are discussed, i.e. alloyed and unalloyed steels, cast iron materials, and the most relevant nonferrous materials. At the end of each chapter, the interested reader will find exercises for self-studies. Some of these can be solved using the material presented in the book while others are intended for deepening and further training. Easy examples (with solutions) are found all over the book; they are helpful because they provide information on underlying mechanisms and interdependences that are not obvious at first glance. The information was adapted to new EURO standards and international standards (up to March 2009) as far as these are relevant to Germany. New information is provided, e.g., on new steel standards (constructional steels according to DIN EN 10025), heat-treatable steels according to DIN EN 10025-6 and DIN EN 10083, high-alloy steels according to DIN EN 10088, and filler materials for steel welding according to DIN EN ISO 2560. The systematics of the ''law of cohabitation'' was applied to welding engineering for the first time here. (orig.) [German] Das in vierter Auflage erscheinende Buch widmet sich der Schweissmetallurgie mit ihren Besonderheiten. Die vielfaeltigen Probleme der Eisenwerkstoffe und der nichteisenmetallischen Werkstoffe bei ihrer schweisstechnischen Verarbeitung werden ausfuehrlich dargestellt. Um Korrosionsschaeden an geschweissten Konstruktionen vorzubeugen, wird die Metallurgie aller technisch bedeutsamen Werkstoffe, wie unlegierte und legierte Staehle, Eisen-Gusswerkstoffe, die wichtigsten NE-Metalle, ausfuehrlich besprochen. An den Kapitelenden findet der interessierte Leser Aufgaben, von denen ein

  18. Die wese van die geloof.

    Directory of Open Access Journals (Sweden)

    P. J. S. De Klerk

    1957-03-01

    Full Text Available Waar ons op 31 Oktober weer dink aan die werk van die Hervorining, daar is dit nodig dat ons weer die aandag vestig op die geloofsworsteling van die manne van die Hervorming. Om daardie geloofsworsteling te verstaan is dit nodig om te let op die wese van die geloof.En om die wese van die geloof te verstaan is dit nodig om eers te let op die geloofsopvatting van Rome.

  19. GC/MS analytical procedure for the characterization of glycerolipids, natural waxes, terpenoid resins, proteinaceous and polysaccharide materials in the same paint microsample avoiding interferences from inorganic media.

    Science.gov (United States)

    Lluveras, Anna; Bonaduce, Ilaria; Andreotti, Alessia; Colombini, Maria Perla

    2010-01-01

    An innovative GC/MS procedure for the characterization of organic materials in samples from works of art was developed. It is based on a multistep chemical pretreatment of the samples based on the ammonia extraction of proteins and polysaccharide materials, in order to separate them from lipid and resinous materials. The extraction is then followed by the separation and purification of proteinaceous and polysaccharide materials before hydrolysis, based on the use of monolithic sorbent tip technology with a C4 stationary phase. Lipids and resins are saponified/salified separately. Three fractions are generated and analyzed separately by GC/MS, thus enabling a quantitative analysis to be performed on aldoses and uronic acids, amino acids, mono- and dicarboxylic aliphatic acids, to determine polysaccharide, proteinaceous, and glycerolipid materials and molecular pattern recognition for the natural resin and wax components. With this analytical procedure, for the first time, glycerolipids, natural waxes, and proteinaceous, resinous, and polysaccharide materials can be simultaneously characterized in the same microsample from painted works of art. This new analytical approach prevents any analytical difficulties arising when the sample is divided into several different aliquots to be chemically processed separately, in order to characterize the various classes of organic materials. The procedure was successfully applied to samples from paintings from the Bamiyan Buddhas and a panel painting from the 15th century, highlighting the occurrence of glycerolipids, animal and plant resins, proteinaceous and polysaccharide materials.

  20. Shear bond strength of a denture base acrylic resin and gingiva-colored indirect composite material to zirconia ceramics.

    Science.gov (United States)

    Kubochi, Kei; Komine, Futoshi; Fushiki, Ryosuke; Yagawa, Shogo; Mori, Serina; Matsumura, Hideo

    2017-04-01

    To evaluate the shear bond strengths of two gingiva-colored materials (an indirect composite material and a denture base acrylic resin) to zirconia ceramics and determine the effects of surface treatment with various priming agents. A gingiva-colored indirect composite material (CER) or denture base acrylic resin (PAL) was bonded to zirconia disks with unpriming (UP) or one of seven priming agents (n=11 each), namely, Alloy Primer (ALP), Clearfil Photo Bond (CPB), Clearfil Photo Bond with Clearfil Porcelain Bond Activator (CPB+Act), Metal Link (MEL), Meta Fast Bonding Liner (MFB), MR. bond (MRB), and V-Primer (VPR). Shear bond strength was determined before and after 5000 thermocycles. The data were analyzed with the Kruskal-Wallis test and Steel-Dwass test. The mean pre-/post-thermalcycling bond strengths were 1.0-14.1MPa/0.1-12.1MPa for the CER specimen and 0.9-30.2MPa/0.1-11.1MPa for the PAL specimen. For the CER specimen, the ALP, CPB, and CPB+Act groups had significantly higher bond strengths among the eight groups, at both 0 and 5000 thermocycles. For the PAL specimen, shear bond strength was significantly lower after thermalcycling in all groups tested. After 5000 thermocycles, bond strengths were significantly higher in the CPB and CPB+Act groups than in the other groups. For the PAL specimens, bond strengths were significantly lower after thermalcycling in all groups tested. The MDP functional monomer improved bonding of a gingiva-colored indirect composite material and denture base acrylic resin to zirconia ceramics. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  1. Influence of surface pretreatment on the short-term bond strength of resin composite to a zirconia-based material.

    Science.gov (United States)

    Fazi, Giovanni; Vichi, Alessandro; Ferrari, Marco

    2012-04-01

    To evaluate the influence of airborne-particle abrasion of zirconia before and after sintering, on the bond strength between a zirconia core and an indirect resin composite material. 9 disks of Y-TZP zirconia core were prepared and divided into three equal groups. In Group 1 pre-sintered Y-TZP zirconia was airborne-particle abraded with 120 microm alumina oxide. In Group 2 sintered Y-TZP zirconia was airborne-particle abraded with 120 microm alumina oxide. In Group 3 sintered Y-TZP zirconia was not treated and thus served as the control group. A 10-methacryloylooxydecyldihydrogenphosphate (MDP) containing bonding agent and silane coupling agent mixture was applied to the disks in all three experimental groups. Resin composite for indirect restorations was incrementally layered in a plastic mold to a final thickness of 3 mm. Specimens were sectioned under water cooling to obtain microsticks 6 x 1 x 1 mm in dimension. 30 microsticks per experimental group were generated. Microtensile bond strength test was conducted with a universal testing machine. Fractured microsticks and sections from each group were also examined under an optical microscope and a scanning electron microscope to evaluate respectively the mode of failure and the zirconia-composite interface. T-test for independent samples was selected to analyze the data. The level of significance was set at P resin composite bond. Airborne-particle abrasion performed before sintering zirconia did not produce any significant differences.

  2. Temperature changes under demineralized dentin during polymerization of three resin-based restorative materials using QTH and LED units.

    Science.gov (United States)

    Mousavinasab, Sayed-Mostafa; Khoroushi, Maryam; Moharreri, Mohammadreza; Atai, Mohammad

    2014-08-01

    Light-curing of resin-based materials (RBMs) increases the pulp chamber temperature, with detrimental effects on the vital pulp. This in vitro study compared the temperature rise under demineralized human tooth dentin during light-curing and the degrees of conversion (DCs) of three different RBMs using quartz tungsten halogen (QTH) and light-emitting diode (LED) units (LCUs). Demineralized and non-demineralized dentin disks were prepared from 120 extracted human mandibular molars. The temperature rise under the dentin disks (n = 12) during the light-curing of three RBMs, i.e. an Ormocer-based composite resin (Ceram. X, Dentsply DeTrey), a low-shrinkage silorane-based composite (Filtek P90, 3M ESPE), and a giomer (Beautifil II, Shofu GmbH), was measured with a K-type thermocouple wire. The DCs of the materials were investigated using Fourier transform infrared spectroscopy. The temperature rise under the demineralized dentin disks was higher than that under the non-demineralized dentin disks during the polymerization of all restorative materials (p 0.05). Although there were no significant differences in the DCs, the temperature rise under demineralized dentin disks for the silorane-based composite was higher than that for dimethacrylate-based restorative materials, particularly with QTH LCU.

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

    Science.gov (United States)

    Pearce, E.; Lin, S. C.

    1981-01-01

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

  4. Resin composite repair: Quantitative microleakage evaluation of resin-resin and resin-tooth interfaces with different surface treatments

    OpenAIRE

    Celik, Cigdem; Cehreli, Sevi Burcak; Arhun, Neslihan

    2015-01-01

    Objective: The aim was to evaluate the effect of different adhesive systems and surface treatments on the integrity of resin-resin and resin-tooth interfaces after partial removal of preexisting resin composites using quantitative image analysis for microleakage testing protocol. Materials and Methods: A total of 80 human molar teeth were restored with either of the resin composites (Filtek Z250/GrandioSO) occlusally. The teeth were thermocycled (1000?). Mesial and distal 1/3 parts of the res...

  5. Modeling and Simulating Material Behavior during Hot Blank - Cold Die (HB-CD) Stamping of Aluminium Alloy Sheets

    Science.gov (United States)

    Zhang, Nan; Abu-Farha, Fadi

    2016-08-01

    Hot blank - cold die (HB-CD) stamping, non-isothermal hot stamping, of aluminium alloy sheets offers great opportunities for high production rates at low cost, while overcoming limited material formability issues. Yet developing an accurate model that can describe the complex material behavior over the wide ranging conditions of HB-CD stamping (temperatures ranging between 25 and 350 °C) is challenging. Moreover, validation of the developed models under transient conditions is problematic. This work presents he results of a comprehensive characterization, material modeling, FE simulation and experimental validation effort to capture the behavior of an aluminium alloy sheet during HB-CD stamping. In particular, we highlight the integration between temperature measurements (thermography) and strain measurements (digital image correlation) for the accurate validation of model predictions of non-isothermal material deformation.

  6. Influence of the base and diluent monomer on network characteristics and mechanical properties of neat resin and composite materials.

    Science.gov (United States)

    Fróes-Salgado, Nívea Regina de Godoy; Gajewski, Vinícius; Ornaghi, Bárbara Pick; Pfeifer, Carmem Silvia Costa; Meier, Marcia Margarete; Xavier, Tathy Aparecida; Braga, Roberto Ruggiero

    2015-05-01

    This study evaluated the effect of the combination of two dimethacrylate-based monomers [bisphenol A diglycidyl dimethacrylate (BisGMA) or bisphenol A ethoxylated dimethacrylate (BisEMA)] with diluents either derived from ethylene glycol dimethacrylate (ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate) or 1,10-decanediol dimethacrylate (D3MA) on network characteristics and mechanical properties of neat resin and composite materials. The degree of conversion, maximum rate of polymerization and water sorption/solubility of unfilled resins and the flexural strength and microhardness of composites (after 24 h storage in water and 3 months storage in a 75 vol% ethanol aqueous solution) were evaluated. Data were analyzed with two-way ANOVA and Tukey's test (α = 0.05). The higher conversion and lower water sorption presented by BisEMA co-polymers resulted in greater resistance to degradation in ethanol compared with BisGMA-based materials. In general, conversion and mechanical properties were optimized with the use of long-chain dimethacrylate derivatives of ethylene glycol. D3MA rendered more hydrophobic materials, but with relatively low conversion and mechanical properties.

  7. Influence of different surface treatments on bond strength of novel CAD/CAM restorative materials to resin cement

    Science.gov (United States)

    Kömürcüoğlu, Meltem Bektaş; Sağırkaya, Elçin

    2017-01-01

    PURPOSE To evaluate the effects of different surface treatments on the bond strength of novel CAD/CAM restorative materials to resin cement by four point bending test. MATERIALS AND METHODS The CAD/CAM materials under investigation were e.max CAD, Mark II, Lava Ultimate, and Enamic. A total of 400 bar specimens (4×1.2×12 mm) (n=10) milled from the CAD/CAM blocks underwent various pretreatments (no pretreatment (C), hydrofluoric acid (A), hydrofluoric acid + universal adhesive (Scotchbond) (AS), sandblasting (Sb), and sandblasting + universal adhesive (SbS)). The bars were luted end-to-end on the prepared surfaces with a dual curing adhesive resin cement (Variolink N, Ivoclar Vivadent) on the custom-made stainless steel mold. Ten test specimens for each treatment and material combination were performed with four point bending test method. Data were analyzed using ANOVA and Tukey's test. RESULTS The surface treatment and type of CAD/CAM restorative material showed a significant effect on the four point bending strength (FPBS) (P<.001). For LDC, AS surface treatment showed the highest FPBS results (100.31 ± 10.7 MPa) and the lowest values were obtained in RNC (23.63 ± 9.0 MPa) for control group. SEM analyses showed that the surface topography of CAD/CAM restorative materials was modified after treatments. CONCLUSION The surface treatment of sandblasting or HF acid etching in combination with a universal adhesive containing MDP can be suggested for the adhesive cementation of the novel CAD/CAM restorative materials. PMID:29279763

  8. Correlative imaging of fluorescent proteins in resin-embedded plant material.

    Science.gov (United States)

    Bell, Karen; Mitchell, Steve; Paultre, Danae; Posch, Markus; Oparka, Karl

    2013-04-01

    Fluorescent proteins (FPs) were developed for live-cell imaging and have revolutionized cell biology. However, not all plant tissues are accessible to live imaging using confocal microscopy, necessitating alternative approaches for protein localization. An example is the phloem, a tissue embedded deep within plant organs and sensitive to damage. To facilitate accurate localization of FPs within recalcitrant tissues, we developed a simple method for retaining FPs after resin embedding. This method is based on low-temperature fixation and dehydration, followed by embedding in London Resin White, and avoids the need for cryosections. We show that a palette of FPs can be localized in plant tissues while retaining good structural cell preservation, and that the polymerized block face can be counterstained with cell wall probes. Using this method we have been able to image green fluorescent protein-labeled plasmodesmata to a depth of more than 40 μm beneath the resin surface. Using correlative light and electron microscopy of the phloem, we were able to locate the same FP-labeled sieve elements in semithin and ultrathin sections. Sections were amenable to antibody labeling, and allowed a combination of confocal and superresolution imaging (three-dimensional-structured illumination microscopy) on the same cells. These correlative imaging methods should find several uses in plant cell biology.

  9. Academy of Dental Materials guidance-Resin composites: Part II-Technique sensitivity (handling, polymerization, dimensional changes).

    Science.gov (United States)

    Ferracane, J L; Hilton, T J; Stansbury, J W; Watts, D C; Silikas, N; Ilie, N; Heintze, S; Cadenaro, M; Hickel, R

    2017-11-01

    The objective of this work, commissioned by the Academy of Dental Materials, was to review and critically appraise test methods to characterize properties related to critical issues for dental resin composites, including technique sensitivity and handling, polymerization, and dimensional stability, in order to provide specific guidance to investigators planning studies of these properties. The properties that relate to each of the main clinical issues identified were ranked in terms of their priority for testing, and the specific test methods within each property were ranked. An attempt was made to focus on the tests and methods likely to be the most useful, applicable, and supported by the literature, and where possible, those showing a correlation with clinical outcomes. Certain methods are only briefly mentioned to be all-inclusive. When a standard test method exists, whether from dentistry or another field, this test has been identified. Specific examples from the literature are included for each test method. The properties for evaluating resin composites were ranked in the priority of measurement as follows: (1) porosity, radiopacity, sensitivity to ambient light, degree of conversion, polymerization kinetics, depth of cure, polymerization shrinkage and rate, polymerization stress, and hygroscopic expansion; (2) stickiness, slump resistance, and viscosity; and (3) thermal expansion. The following guidance is meant to aid the researcher in choosing the most appropriate test methods when planning studies designed to assess certain key properties and characteristics of dental resin composites, specifically technique sensitivity and handling during placement, polymerization, and dimensional stability. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  10. A resin composite material containing an eugenol derivative for intracanal post cementation and core build-up restoration.

    Science.gov (United States)

    Almaroof, A; Rojo, L; Mannocci, F; Deb, S

    2016-02-01

    To formulate and evaluate new dual cured resin composite based on the inclusion of eugenyl methacrylate monomer (EgMA) with Bis-GMA/TEGDMA resin systems for intracanal post cementation and core build-up restoration of endodontically treated teeth. EgMA was synthesized and incorporated at 5% (BTEg5) or 10% (BTEg10) into dual-cure formulations. Curing properties, viscosity, Tg, radiopacity, static and dynamic mechanical properties of the composites were determined and compared with Clearfil™DC Core-Plus, a commercial dual-cure, two-component composite. Statistical analysis of the data was performed with ANOVA and the Tukey's post-hoc test. The experimental composites were successfully prepared, which exhibited excellent curing depths of 4.9, 4.7 and 4.2 mm for BTEg0, BTEg5 and BTEg10 respectively, which were significantly higher than Clearfil™DC. However, the inclusion of EgMA initially led to a lower degree of cure, which increased when measured at 24 h with values comparable to formulations without EgMA, indicating post-curing. The inclusion of EgMA also lowered the polymerization exotherm thereby reducing the potential of thermal damage to host tissue. Both thermal and viscoelastic analyses confirmed the ability of the monomer to reduce the stiffness of the composites by forming a branched network. The compressive strength of BTEg5 was significantly higher than the control whilst flexural strength increased significantly from 95.9 to 114.8 MPa (BTEg5) and 121.9 MPa (BTEg10). Radiopacity of the composites was equivalent to ∼3 mm Al allowing efficient diagnosis. The incorporation of EgMA within polymerizable formulations provides a novel approach to prepare reinforced resin composite material for intracanal post cementation and core build-up and the potential to impart antibacterial properties of eugenol to endodontic restorations. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  11. Die instelling van die doop

    Directory of Open Access Journals (Sweden)

    J. L. Venter

    1989-05-01

    Full Text Available Die eerste plek in die evangeliebeskrywings waar daar van die doop as ’n opdrag van Jesus Christus gepraat word en waar die betekenis die duidelikste uitkristalliseer, staan in Matteus 28 : 16 - 20. Heilshistories gesien, is dit die begin van kerklike inlywing van die wat gehoor het hoedat Jesus sy koninkryk proklameer, die evangelie aanvaar en tot bekering kom. Vir die doel van hierdie artikel word hierdie gedeelte ondersoek om te sien hoe die instelling geskied het, wat die plek en betekenis van die Christelike doop is.

  12. Die Region braucht die Kultur - die Kultur braucht die Region

    OpenAIRE

    Klemm, Ulrich

    1995-01-01

    Die Region braucht die Kultur - die Kultur braucht die Region. - In: Region in Aktion - oder: Region im Abseits? - Boxberg-Wölchingen : Eigenständige Regionalentwicklung Baden-Württemberg, 1995. - S. 25 f.

  13. Efficacy of ceramic repair material on the bond strength of composite resin to zirconia ceramic.

    Science.gov (United States)

    Kirmali, Omer; Kapdan, Alper; Harorli, Osman Tolga; Barutcugil, Cagatay; Ozarslan, Mehmet Mustafa

    2015-01-01

    The aim of this study was to evaluate the shear bond strength of composite resin in five different repair systems. Sixty specimens (7 mm in diameter and 3 mm in height) of zirconia ceramic were fabricated. All specimen surfaces were prepared with a 30 µm fine diamond rotary cutting instrument with water irrigation for 10 s and dried with oil-free air. Specimens were then randomly divided into six groups for the following different intra-oral repair systems (n = 10): Group 1, control group; Group 2, Cojet system (3M ESPE, Seefeld, Germany); Group 3, Cimara® System (Voco, Cuxhaven, Germany); Group 4, Z-Prime Plus System (Bisco Inc., Schaumburg, IL); Group 5, Clearfil™ System (Kuraray, Osaka, Japan); and Group 6, Z-Bond System (Danville, CA). After surface conditioning, a composite resin Grandio (Voco, Cuxhaven, Germany) was applied to the zirconia surface using a cylindrical mold (5 mm in diameter and 3 mm in length) and incrementally filled up, according to the manufacturer's instructions of each intra-oral system. Each specimen was subjected to a shear load at a crosshead speed of 1 mm/min until fracture. One-way analysis of variance (ANOVA) and Tukey post-hoc tests were used to analyze the bond strength values. There were significant differences between Groups 2-6 and Group 1. The highest bond strength values were obtained with Group 2 (17.26 ± 3.22) and Group 3 (17.31 ± 3.62), while the lowest values were observed with Group 1 (8.96 ± 1.62) and Group 6 (12.85 ± 3.95). All repair systems tested increased the bond strength values between zirconia and composite resin that used surface grinding with a diamond bur.

  14. Improved resins and novel materials and methods for solid phase extraction and high performance liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Freeze, Ronald [Iowa State Univ., Ames, IA (United States)

    1997-10-08

    Solid-phase extraction (SPE) has grown to be one of the most widely used methods for isolation and preconcentration of a vast range of compounds from aqueous solutions. By modifying polymeric SPE resins with chelating functional groups, the selective uptake of metals was accomplished. The resin, along with adsorbed metals, was vaporized in the ICP and detection of the metals was then possible using either mass or emission spectroscopy. Drug analyses in biological fluids have received heightened attention as drug testing is on the increase both in sports and in the work environment. By using a direct-injection technique, biological fluids can be injected directly into the liquid chromatographic system with no pretreatment. A new surfactant, a sulfonated form of Brij-30 (Brij-S) is shown to prevent the uptake of serum proteins on commercial HPLC columns by forming a thin coating on the silica C18 surface. Excellent separations of eight or more drugs with a wide range of retention times were obtained. The separations had sharper peaks and lower retention times than similar separations performed with the surfactant sodium dodecylsulfate (SDS). Quantitative recovery of a number of drugs with limits of detection near 1 ppm with a 5 μl injection volume were obtained. Finally, a method for solid-phase extraction in a syringe is introduced. The system greatly reduced the volume of solvent required to elute adsorbed analytes from the SPE bed while providing a semi-automated setup. SPE in a syringe consists of a very small bed of resin-loaded membrane packed into a GC or HPLC syringe. After extraction, elution was performed with just a few μl of solvent. This small elution volume allowed injection of the eluent directly from the syringe into the chromatographic system, eliminating the handling problems associated with such small volumes.

  15. Die sideboard

    African Journals Online (AJOL)

    Owner

    man wat vir die De Bruins werk en Stella. Figland, 'n onderwyseres en Abraham se latere vrou. Abraham is op die punt om die grond waarop hulle boer, te koop wanneer die groot slag kom. In afwagting van die nuwe plant- seisoen word hierdie pastorale gemoedelik- heid waar Miena die Venters se eerste kleinkind.

  16. Efficiency of dual-cured resin cement polymerization induced by high-intensity LED curing units through ceramic material.

    Science.gov (United States)

    Watanabe, H; Kazama, Re; Asai, T; Kanaya, F; Ishizaki, H; Fukushima, M; Okiji, T

    2015-01-01

    This study aimed to evaluate the ability of high-intensity light-emitting diode (LED) and other curing units to cure dual-cured resin cement through ceramic material. A halogen curing unit (Jetlite 3000, Morita), a second-generation LED curing unit (Demi, Kerr), and two high-intensity LED curing units (PenCure 2000, Morita; Valo, Ultradent) were tested. Feldspathic ceramic plates (VITABLOCS Mark II, A3; Vita Zahnfabrik) with thicknesses of 1.0, 2.0, and 3.0 mm were prepared. Dual-cured resin cement samples (Clearfil Esthetic Cement, Kuraray Noritake Dental) were irradiated directly or through one of the ceramic plates for different periods (5, 10, 15, or 20 seconds for the high-intensity LED units and 20, 40, 60, or 80 seconds for the others). The Knoop hardness test was used to determine the level of photopolymerization that had been induced in the resin cement. Data were analyzed by one-way analysis of variance and Dunnett's post-hoc test to identify test-control (maximum irradiation without a ceramic plate) differences for each curing unit (presin cement through a ceramic plate resulted in decreased KHN values compared with direct irradiation. When the irradiation period was extended, only the LED units were able to achieve similar KHN values to those observed under direct irradiation in the presence of plates ≥2.0-mm thick. High-intensity LED units require a shorter irradiation period than halogen and second-generation LED curing units to obtain KHN values similar to those observed during direct irradiation.

  17. Interlocking multi-material components made of structured steel sheets and high-pressure die cast aluminium

    Science.gov (United States)

    Senge, S.; Brachmann, J.; Hirt, G.; Bührig-Polaczek, A.

    2017-10-01

    Lightweight design is a major driving force of innovation, especially in the automotive industry. Using hybrid components made of two or more different materials is one approach to reduce the vehicles weight and decrease fuel consumption. As a possible way to increase the stiffness of multi-material components, this paper presents a process chain to produce such components made of steel sheets and high-pressure die cast aluminium. Prior to the casting sequence the steel sheets are structured in a modified rolling process which enables continuous interlocking with the aluminium. Two structures manufactured by this rolling process are tested. The first one is a channel like structure and the second one is a channel like structure with undercuts. These undercuts enable the formation of small anchors when the molten aluminium fills them. The correlation between thickness reduction during rolling and the shape of the resulting structure was evaluated for both structures. It can be stated that channels with a depth of up to 0.5 mm and a width of 1 mm could be created. Undercuts with different size depending on the thickness reduction could be realised. Subsequent aluminium high-pressure die casting experiments were performed to determine if the surface structure can be filled gap-free with molten aluminium during the casting sequence and if a gap-free connection can be achieved after contraction of the aluminium. The casting experiments showed that both structures could be filled during the high-pressure die casting. The channel like structure results in a gap between steel and aluminium after contraction of the cast metal whereas the structure with undercuts leads to a good interlocking resulting in a gap-free connection.

  18. System for removing contaminants from plastic resin

    Science.gov (United States)

    Bohnert, George W.; Hand, Thomas E.; DeLaurentiis, Gary M.

    2010-11-23

    A resin recycling system that produces essentially contaminant-free synthetic resin material in an environmentally safe and economical manner. The system includes receiving the resin in container form. A grinder grinds the containers into resin particles. The particles are exposed to a solvent in one or more solvent wash vessels, the solvent contacting the resin particles and substantially removing contaminants on the resin particles. A separator is used to separate the resin particles and the solvent. The resin particles are then placed in solvent removing element where they are exposed to a solvent removing agent which removes any residual solvent remaining on the resin particles after separation.

  19. Microleakage of composite resin and amalgam core material under complete cast crowns.

    Science.gov (United States)

    Larson, T D; Jensen, J R

    1980-07-01

    Ninety extracted human teeth were used to compare the microleakage of composite resin over, amalgam core, and regular crown preparations under a complete cast gold crown cemented with zinc phosphate cement as determined by 2% fluorescein dye solution. Specimens were compared with and without aging after cementation in a thermal bath by cycling some of them between 4 degrees C and 60 degrees C in a 2% fluorescein dye bath and others in a similar bath held at 37 degrees C. Fluorescein dye (under ultraviolet light) demonstrated microleakage of the specimens between the crown-tooth interface and the core-tooth interface. There were no significant differences in the microleakage due to aging. The specimens held at 37 degrees C in the fluorescein dye bath showed no significant differences between the core preparations and the regular crown preparations. However, when specimens were thermally cycled between 4 degrees C and 60 degrees C, there were significant differences. With thermal cycling, the regular crown preparations were better able to resist microleakage at the crown-tooth interface than either the composite resin core or the amalgam core preparations. The results of this investigation seem to indicate a need for further evaluation of core build-ups under cemented complete gold crowns.

  20. Physicochemical properties and cytotoxicity of an experimental resin-based pulp capping material containing the quaternary ammonium salt and Portland cement.

    Science.gov (United States)

    Yang, Y W; Yu, F; Zhang, H C; Dong, Y; Qiu, Y N; Jiao, Y; Xing, X D; Tian, M; Huang, L; Chen, J H

    2018-01-01

    To evaluate in vitro the physicochemical properties, cytotoxicity and calcium phosphate nucleation of an experimental light-curable pulp capping material composed of a resin with antibacterial monomer (MAE-DB) and Portland cement (PC). The experimental material was prepared by mixing PC with a resin containing MAE-DB at a 2 : 1 ratio. Cured pure resin containing MAE-DB served as control resin. ProRoot MTA and Dycal served as commercial controls. The depth of cure, degree of monomer conversion, water absorption and solubility of dry samples, calcium release, alkalinizing activity, calcium phosphate nucleation and the cytotoxicity of materials were evaluated. Statistical analysis was carried out using anova followed by Tukey's HSD test (equal variance assumed) or Tamhane test (equal variance not assumed) and independent-samples t-tests. The experimental material had a cure depth of 1.19 mm, and the mean degree of monomer conversion was 70.93% immediately post-cure and 88.75% at 24 h post-cure. The water absorption of the experimental material was between those of MTA and Dycal, and its solubility was significantly less (P material exhibited continuous calcium release and an alkalinizing power between those of MTA and Dycal throughout the test period. Freshly set experimental material, control resin and all 24-h set materials had acceptable cytotoxicity. The experimental material, MTA and Dycal all exhibited the formation of apatite precipitates after immersion in phosphate-buffered saline. The experimental material possessed adequate physicochemical properties, low cytotoxicity and good calcium phosphate nucleation. © 2017 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  1. Addition of glass fibers and titanium dioxide nanoparticles to the acrylic resin denture base material: comparative study with the conventional and high impact types.

    Science.gov (United States)

    Hamouda, Ibrahim M; Beyari, Mohammed M

    2014-03-01

    The aim of this study was to clarify the effect of addition of glass fibers and titanium dioxide nanoparticles to the conventional acrylic resin. The tested parameters were monomer release, deflection at fracture, flexural strength, flexural modulus, and toughness. The modified acrylic resin groups were compared to the conventional unmodified and high impact types. The correlation between the tested material properties was also evaluated. The materials used were conventional unmodified and high impact acrylic resins. The conventional acrylic resin was modified using 5% glass fibers and 5% titanium dioxide nanoparticles. Specimens were prepared according to the manufacturer's instructions and American Dental Association Specification No. 12. Monomer release was measured using isocratic high-performance liquid chromatography. Deflection at fracture, flexural strength, and flexural modulus were measured using three point-bending test with a universal testing machine. The toughness was related to the total area under the load-deflection curve up to the breaking point. The correlation between the tested properties was clarified. All materials released monomer with varying values. The tested materials exhibited comparable values of deflection at fracture. Specimens modified with glass-fibers showed improved flexural strength and toughness similar to that of the high impact acrylic resin. Specimens modified with titanium dioxide nanoparticles exhibited reduction in the flexural properties and toughness. No significant changes were observed in the flexural modulus. There were positive correlations between the flexural strength, flexural modulus and toughness. On the contrary, there was negative correlation between deflection at fracture and flexural modulus. The most commercially successful method for reinforcement to date is the rubber toughening. The conventional acrylic resin denture base material could be reinforced by glass fibers while titanium dioxide nanoparticles

  2. Experimental and Numerical Studies on the Formability of Materials in Hot Stamping and Cold Die Quenching Processes

    Science.gov (United States)

    Li, N.; Mohamed, M. S.; Cai, J.; Lin, J.; Balint, D.; Dean, T. A.

    2011-05-01

    Formability of steel and aluminium alloys in hot stamping and cold die quenching processes is studied in this research. Viscoplastic-damage constitutive equations are developed and determined from experimental data for the prediction of viscoplastic flow and ductility of the materials. The determined unified constitutive equations are then implemented into the commercial Finite Element code Abaqus/Explicit via a user defined subroutine, VUMAT. An FE process simulation model and numerical procedures are established for the modeling of hot stamping processes for a spherical part with a central hole. Different failure modes (failure takes place either near the central hole or in the mid span of the part) are obtained. To validate the simulation results, a test programme is developed, a test die set has been designed and manufactured, and tests have been carried out for the materials with different forming rates. It has been found that very close agreements between experimental and numerical process simulation results are obtained for the ranges of temperatures and forming rates carried out.

  3. Experimental and Numerical Studies on the Formability of Materials in Hot Stamping and Cold Die Quenching Processes

    International Nuclear Information System (INIS)

    Li, N.; Mohamed, M. S.; Cai, J.; Lin, J.; Balint, D.; Dean, T. A.

    2011-01-01

    Formability of steel and aluminium alloys in hot stamping and cold die quenching processes is studied in this research. Viscoplastic-damage constitutive equations are developed and determined from experimental data for the prediction of viscoplastic flow and ductility of the materials. The determined unified constitutive equations are then implemented into the commercial Finite Element code Abaqus/Explicit via a user defined subroutine, VUMAT. An FE process simulation model and numerical procedures are established for the modeling of hot stamping processes for a spherical part with a central hole. Different failure modes (failure takes place either near the central hole or in the mid span of the part) are obtained. To validate the simulation results, a test programme is developed, a test die set has been designed and manufactured, and tests have been carried out for the materials with different forming rates. It has been found that very close agreements between experimental and numerical process simulation results are obtained for the ranges of temperatures and forming rates carried out.

  4. In field application of differential Die-Away time technique for detecting gram quantities of fissile materials

    Science.gov (United States)

    Remetti, Romolo; Gandolfo, Giada; Lepore, Luigi; Cherubini, Nadia

    2017-10-01

    In the frame of Chemical, Biological, Radiological, and Nuclear defense European activities, the ENEA, the Italian National Agency for New Technologies, Energy and Sustainable Economic Development, is proposing the Neutron Active Interrogation system (NAI), a device designed to find transuranic-based Radioactive Dispersal Devices hidden inside suspected packages. It is based on Differential Die-Away time Analysis, an active neutron technique targeted in revealing the presence of fissile material through detection of induced fission neutrons. Several Monte Carlo simulations, carried out by MCNPX code, and the development of ad-hoc design methods, have led to the realization of a first prototype based on a 14 MeV d-t neutron generator coupled with a tailored moderating structure, and an array of helium-3 neutron detectors. The complete system is characterized by easy transportability, light weight, and real-time response. First results have shown device's capability to detect gram quantities of fissile materials.

  5. Multi-wall carbon nanotubes/epoxy resin composites characterization of the starting materials and evaluation of thermal and electrical conductivity

    International Nuclear Information System (INIS)

    Silva, Wellington Marcos da

    2009-01-01

    In this study we investigate the electrical and thermal properties of I) composite materials fabricated with O, I, 0,5 and I wt% of concentric multi-wall carbon nanotubes/epoxy resin (MWNT) dispersed randomly in the resin; 2) MWNT buckypaper/resin composite materials; 3) and neat MWNT buckypaper. Initially, we use the techniques of thermogravimetry, infrared spectroscopy, nuclear magnetic resonance, energy dispersive spectroscopy, x-ray fluorescence, scanning and transmission electron microscopy for a broadening characterization of the starting materials, to evaluate its morphology, purity, chemical composition and structure, in order to optimize the properties of crosslinked resin and, consequently, of the composite systems. Important parameters such as the average molecular mass and the equivalent weight of epoxy resin (DGEBA) were determined by 1 H-NMR analysis and, after that, resin/curing agent relations with Phr 10, 15, 20 and 53,2 were elaborated and investigated by thermogravimetry, the resin/curing agent relation with Phr 10 showed to be the most thermally stable. This stoichiometric relation was used to elaborate the composites. We have evaluated that the effect of adding 10 wt% of the solvent acetone to the epoxy resin preparation does not alter its properties so we have adopted two routes to fabricate the composites. In the first route we used 10 wt% of acetone and, in the second the MWNT were dispersed in the matrix without using the solvent. However, no significant difference was observed for the dispersion of the bundle tubes in both systems. The electrical conductivity of the composites and buckypapers was evaluated by impedance spectroscopy and the thermal conductivity by the flash laser flash method. Only the buckypapers presented high values for electrical conductivity (10 3 S.m -1 ). The composite systems presented values of 10 -3 S.m -1 , only a bit different from the value of the crosslinked resin. For thermal conductivity, the values for the

  6. Effect of light-curing method and indirect veneering materials on the Knoop hardness of a resin cement

    Directory of Open Access Journals (Sweden)

    Nelson Tetsu Iriyama

    2009-06-01

    Full Text Available This study evaluated the Knoop hardness of a dual-cured resin cement (Rely-X ARC activated solely by chemical reaction (control group or by chemical / physical mode, light-cured through a 1.5 mm thick ceramic (HeraCeram or composite (Artglass disc. Light curing was carried out using conventional halogen light (XL2500 for 40 s (QTH; light emitting diodes (Ultrablue Is for 40 s (LED; and Xenon plasma arc (Apollo 95E for 3 s (PAC. Bovine incisors had their buccal face flattened and hybridized. On this surface a rubber mold (5 mm in diameter and 1 mm in height was bulk filled with the resin cement. A polyester strip was seated for direct light curing or through the discs of veneering materials. After dry storage in the dark (24 h 37°C, the samples (n = 5 were sectioned for hardness (KHN measurements, taken in a microhardness tester (50 gF load 15 s. The data were statistically analyzed by ANOVA and Tukey's test (α = 0.05. The cement presented higher Knoop hardness values with Artglass for QTH and LED, compared to HeraCeram. The control group and the PAC/Artglass group showed lower hardness values compared to the groups light-cured with QTH and LED. PAC/HeraCeram resulted in the worst combination for cement hardness values.

  7. Raw materials for the energy supply of the future. Geology, markets, environmental influences; Rohstoffe fuer die Energieversorgung der Zukunft. Geologie, Maerkte, Umwelteinfluesse

    Energy Technology Data Exchange (ETDEWEB)

    Hagelueken, Christian [Umicore, Hanau-Wolfgang (Germany); Thauer, Rudolf K. [Max-Planck-Institut fuer Terrestrische Mikrobiologie, Marburg (Germany); Buchholz, Peter [Bundesanstalt fuer Geowissenschaften und Rohstoffe, Hannover (Germany). Deutsche Rohstoffagentur; Herzig, Peter [GEOMAR Helmholtz-Zentrum fuer Ozeanforschung Kiel (Germany); Gutzmer, Jens [Technische Univ. Bergakademie Freiberg (Germany); Helmholtz-Institut Freiberg fuer Ressourcentechnologie (Germany); Littke, Ralf [Rheinisch-Westfaelische Technische Hochschule (RWTH), Aachen (Germany); Angerer, Gerhard; Wellmer, Friedrich-Wilhelm

    2015-11-15

    More and more metals are needed to expand modern energy technologies, but we can not completely dispense with fossil raw materials and biomass in the near future either. Are the incidence of the conversion of energy sources sufficient? The analysis of the academy project ''Energy Systems of the Future'' (ESYS) comes to the conclusion that geologically enough raw materials are available. The challenge, however, is to make the supply safe, affordable and environmentally and socially compatible. The analysis explains the mechanisms of action on the global commodity markets and identifies supply risks. These include, for example, sudden demand on the international markets as well as the unequal distribution of the world's raw material reserves. This is followed by the analysis approaches, in order to recognize warning signals for potential raw material bottlenecks in time, to develop evasive strategies and to secure the raw material supply for the energy turnarounds. For example, the expansion of recycling can help to reduce the dependence on metal imports. In mining, on the other hand, innovative technologies have to be developed in order to improve the exploration and utilization of the deposits. By establishing binding environmental and social standards, the extraction of raw materials could also become more sustainable. The analysis also highlights the importance of bioenergy and fossil raw materials, such as oil and natural gas, for energy generation. The authors describe the advantages and disadvantages of these energy carriers and the measures that can be used to reduce environmental pollution such as greenhouse gas emissions. [German] Fuer den Ausbau moderner Energietechnologien werden immer mehr Metalle benoetigt, doch auch auf fossile Rohstoffe und Biomasse koennen wir in naher Zukunft nicht vollstaendig verzichten. Reichen die Vorkommen zur Umsetzung der Energiewende aus? Die Analyse des Akademienprojekts &apos

  8. Measurement of paint-on die spacers used for casting relief.

    Science.gov (United States)

    Campagni, W V; Preston, J D; Reisbick, M H

    1982-06-01

    Three paints used for die spacing were measured for film thickness. Two of the materials are marketed as die spacers, and the third is sold as a model airplane paint. The materials were applied to stone dies in multiple coats. They were embedded in resin, sectioned, and measured photographically through a microscope. The three die spacing materials were capable of achieving clinically acceptable relief in the range of 20 to 40 mu by using a variable number of coats. Different paints produced different thicknesses. The two paints sold specifically for die spacing gave 11 to 13 mu per coat. The hobby shop paint had the smallest film thickness per coat, yielding approximately 5 mu per layer. It also had the smallest standard deviation. This control plus the relative low cost and availabilty make it attractive for this purpose.

  9. Six-month evaluation of a resin/dentin interface created by methacrylate and silorane-based materials

    Science.gov (United States)

    SAMPAIO, Renata Kirita Doi; WANG, Linda; de CARVALHO, Rodrigo Varella; GARCIA, Eugenio José; de ANDRADE, Andréa Mello; KLEIN-JÚNIOR, Celso Afonso; GRANDE, Rosa Helena Miranda; MOURA, Sandra Kiss

    2013-01-01

    Objectives: This study aimed to compare the micro-tensile bond strength of methacrylate resin systems to a silorane-based restorative system on dentin after 24 hours and six months water storage. Material and Methods: The restorative systems Adper Single Bond 2/Filtek Z350 (ASB), Clearfil SE Bond/Z350 (CF), Adper SE Plus/Z350 (ASEP) and P90 Adhesive System/Filtek P90 (P90) were applied on flat dentin surfaces of 20 third molars (n=5). The restored teeth were sectioned perpendicularly to the bonding interface to obtain sticks (0.8 mm2) to be tested after 24 hours (24 h) and 6 months (6 m) of water storage, in a universal testing machine at 0.5 mm/min. The data was analyzed via two-way Analysis of Variance/Bonferroni post hoc tests at 5% global significance. Results: Overall outcomes did not indicate a statistical difference for the resin systems (p=0.26) nor time (p=0.62). No interaction between material x time was detected (p=0.28). Mean standard-deviation in MPa at 24 h and 6 m were: ASB 31.38 (4.53) and 30.06 (1.95), CF 34.26 (3.47) and 32.75 (4.18), ASEP 29.54 (4.14) and 33.47 (2.47), P90 30.27 (2.03) and 31.34 (2.19). Conclusions: The silorane-based system showed a similar performance to methacrylate-based materials on dentin. All systems were stable in terms of bond strength up to 6 month of water storage. PMID:23559117

  10. Six-month evaluation of a resin/dentin interface created by methacrylate and silorane-based materials

    Directory of Open Access Journals (Sweden)

    Renata Kirita Doi SAMPAIO

    2013-01-01

    Full Text Available Objectives This study aimed to compare the micro-tensile bond strength of methacrylate resin systems to a silorane-based restorative system on dentin after 24 hours and six months water storage. Material and Methods The restorative systems Adper Single Bond 2/Filtek Z350 (ASB, Clearfil SE Bond/Z350 (CF, Adper SE Plus/Z350 (ASEP and P90 Adhesive System/Filtek P90 (P90 were applied on flat dentin surfaces of 20 third molars (n=5. The restored teeth were sectioned perpendicularly to the bonding interface to obtain sticks (0.8 mm2 to be tested after 24 hours (24 h and 6 months (6 m of water storage, in a universal testing machine at 0.5 mm/min. The data was analyzed via two-way Analysis of Variance/Bonferroni post hoc tests at 5% global significance. Results Overall outcomes did not indicate a statistical difference for the resin systems (p=0.26 nor time (p=0.62. No interaction between material × time was detected (p=0.28. Mean standard-deviation in MPa at 24 h and 6 m were: ASB 31.38 (4.53 and 30.06 (1.95, CF 34.26 (3.47 and 32.75 (4.18, ASEP 29.54 (4.14 and 33.47 (2.47, P90 30.27 (2.03 and 31.34 (2.19. Conclusions The silorane-based system showed a similar performance to methacrylate-based materials on dentin. All systems were stable in terms of bond strength up to 6 month of water storage.

  11. Die nabyheid van die Koninkryk

    Directory of Open Access Journals (Sweden)

    W.J. Snyman

    1963-03-01

    Full Text Available Vanweë die belangrikheid daarvan volg hier ’n breër bespreking van die proefskrif van dr. Tjaart van der Walt oor die nabyheid van die Koninkryk as wat in ’n gewone resensie kan geskied. Die vraagstuk wat onder oë gesien word is so oud as die kerk en die teologie, soms minder en soms meer op die voorgrond. Tans kan gesê word, staan dit in die middelpunt. Daarby is dit nie maar ’n akademiese vraagstuk nie, maar ’n vraagstuk waarvoor elke nadenkende leser van die Skrif te staan kom.

  12. Perubahan warna lempeng resin akrilik yang direndam dalam larutan desinfektan sodium hipoklorit dan klorhexidin (The color changes of acrylic resins denture base material which are immersed in Sodium hypochlorite and chlorhexidine

    Directory of Open Access Journals (Sweden)

    David David

    2006-03-01

    Full Text Available One of the acrylic resins properties is the water absorption including color fluids and chemically fluids that affect on the color changes of the acrylic resins. This laboratory experiments studied sodium hypochlorite and chlorhexidine effect on the color changes of acrylic denture base resins material. The study was conducted by immersing heat cured acrylic plate samples of 26 mm of diameter and 0.4 mm of thickness in sodium hypochlorite for 10; 70 and 140 minutes and chlorhexidine for 15; 105 and 210 minutes. Seven samples were used for each experiment. An optical spectrometer BPX-47 type photo cell and a digital microvoltage were used for the color changes observation. The statistical test used were t-test, One-way ANOVA and LSD with 0.05 significance degree level. The results of the studied showed that the color of acrylic resins denture base plate changed after immersion in sodium hypochlorite for 70 and 140 minutes and chlorhexidine for 105 and 210 minute of immersion.

  13. Comparative evaluation of shear bond strength of three resin based dual-cure core build-up materials: An In-vitro study

    OpenAIRE

    Jain, Gaurav; Narad, Aditi; Boruah, Lalit C.; Rajkumar, Balakrishnan

    2015-01-01

    Aim: The in-vitro study compared the shear bond strength (SBS) of three recently introduced dual-cure resin based core build-up materials namely ParaCore, FluoroCore, and MultiCore. Materials and Methods: One hundred twenty extracted permanent human mandibular molar teeth were taken and sectioned horizontally beneath the dentinoenamel junction to expose the coronal dentin. The specimens obtained were divided into three main groups based on the materials used and then further divided into ...

  14. In vitro antibacterial activity of a novel resin-based pulp capping material containing the quaternary ammonium salt MAE-DB and Portland cement.

    Science.gov (United States)

    Yang, Yanwei; Huang, Li; Dong, Yan; Zhang, Hongchen; Zhou, Wei; Ban, Jinghao; Wei, Jingjing; Liu, Yan; Gao, Jing; Chen, Jihua

    2014-01-01

    Vital pulp preservation in the treatment of deep caries is challenging due to bacterial infection. The objectives of this study were to synthesize a novel, light-cured composite material containing bioactive calcium-silicate (Portland cement, PC) and the antimicrobial quaternary ammonium salt monomer 2-methacryloxylethyl dodecyl methyl ammonium bromide (MAE-DB) and to evaluate its effects on Streptococcus mutans growth in vitro. The experimental material was prepared from a 2 : 1 ratio of PC mixed with a resin of 2-hydroxyethylmethacrylate, bisphenol glycerolate dimethacrylate, and triethylene glycol dimethacrylate (4 : 3 : 1) containing 5 wt% MAE-DB. Cured resin containing 5% MAE-DB without PC served as the positive control material, and resin without MAE-DB or PC served as the negative control material. Mineral trioxide aggregate (MTA) and calcium hydroxide (Dycal) served as commercial controls. S. mutans biofilm formation on material surfaces and growth in the culture medium were tested according to colony-forming units (CFUs) and metabolic activity after 24 h incubation over freshly prepared samples or samples aged in water for 6 months. Biofilm formation was also assessed by Live/Dead staining and scanning electron microscopy. S. mutans biofilm formation on the experimental material was significantly inhibited, with CFU counts, metabolic activity, viability staining, and morphology similar to those of biofilms on the positive control material. None of the materials affected bacterial growth in solution. Contact-inhibition of biofilm formation was retained by the aged experimental material. Significant biofilm formation was observed on MTA and Dycal. The synthesized material containing HEMA-BisGMA-TEGDMA resin with MAE-DB as the antimicrobial agent and PC to support mineralized tissue formation inhibited S. mutans biofilm formation even after aging in water for 6 months, but had no inhibitory effect on bacteria in solution. Therefore, this material shows

  15. Die aktualisering van die gemeenskap van die gelowiges binne die ...

    African Journals Online (AJOL)

    The youth experiences the pubHc service in the Neder- duitsch Hervormde Church of Africa as cold and dead. ... the public service, and the actualising of the believers. 1. RELEVANSIE VAN DIE TEMA ..... die erediens lean inrig sodat die volledige implikasie en appél van die Goddelike, vertikale indikatief na die horisontale ...

  16. Effect of priming agents on shear bond strengths of resin-based luting agents to a translucent zirconia material.

    Science.gov (United States)

    Yagawa, Shogo; Komine, Futoshi; Fushiki, Ryosuke; Kubochi, Kei; Kimura, Fumiaki; Matsumura, Hideo

    2017-09-19

    The purpose of the present study was to evaluate the effect of priming agents and artificial aging with thermocycling on shear bond strengths of two resin-based luting agents to a translucent zirconia material. A total of 308 pairs of translucent zirconia disk specimens were divided into seven treatment groups: Alloy Primer (ALP), Clearfil Ceramic Primer Plus (CCP), Meta Fast Bonding Liner (MFB), MR. bond (MRB), Super-Bond PZ Primer Liquid B (PZB), V-Primer (VPR), and an unprimed group (UP). The specimens in each group were bonded with Panavia V5 Universal (UNI) and Opaque shade (OPA). Shear bond strengths (n=11 each) were tested before and after 5000 thermocycles. The data were analyzed with the Kruskal-Wallis test and the Steel-Dwass test. For both 0 and 5000 thermocycles, the ALP (47.8 and 41.5MPa, respectively) and CCP (45.8 and 42.3MPa, respectively) groups showed significantly higher bond strengths than other groups in the UNI luting agent. For the OPA luting agent, CCP group (45.8MPa) exhibited the highest pre-thermocycling bond strength in all groups. The ALP (32.4MPa) and CCP (36.5MPa) groups had significantly higher post-thermocycling shear bond strengths than other groups. In several groups, the shear bond strengths of the UNI luting agent were significantly higher than those of the OPA luting agent before and after thermocycling. Application of priming agents containing hydrophobic phosphate monomer (MDP) yielded the durable bond strengths of resin-based luting agents to a translucent zirconia material. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  17. Packaged die heater

    Science.gov (United States)

    Spielberger, Richard; Ohme, Bruce Walker; Jensen, Ronald J.

    2011-06-21

    A heater for heating packaged die for burn-in and heat testing is described. The heater may be a ceramic-type heater with a metal filament. The heater may be incorporated into the integrated circuit package as an additional ceramic layer of the package, or may be an external heater placed in contact with the package to heat the die. Many different types of integrated circuit packages may be accommodated. The method provides increased energy efficiency for heating the die while reducing temperature stresses on testing equipment. The method allows the use of multiple heaters to heat die to different temperatures. Faulty die may be heated to weaken die attach material to facilitate removal of the die. The heater filament or a separate temperature thermistor located in the package may be used to accurately measure die temperature.

  18. Fracture Resistance of Endodontically Treated Teeth Restored with 2 Different Fiber-reinforced Composite and 2 Conventional Composite Resin Core Buildup Materials: An In Vitro Study.

    Science.gov (United States)

    Eapen, Ashly Mary; Amirtharaj, L Vijay; Sanjeev, Kavitha; Mahalaxmi, Sekar

    2017-09-01

    The purpose of this in vitro study was to comparatively evaluate the fracture resistance of endodontically treated teeth restored with 2 fiber-reinforced composite resins and 2 conventional composite resin core buildup materials. Sixty noncarious unrestored human maxillary premolars were collected, endodontically treated (except group 1, negative control), and randomly divided into 5 groups (n = 10). Group 2 was the positive control. The remaining 40 prepared teeth were restored with various direct core buildup materials as follows: group 3 teeth were restored with dual-cure composite resin, group 4 with posterior composite resin, group 5 with fiber-reinforced composite resin, and group 6 with short fiber-reinforced composite resin. Fracture strength testing was performed using a universal testing machine. The results were statistically analyzed by 1-way analysis of variance and the post hoc Tukey test. Fracture patterns for each sample were also examined under a light microscope to determine the level of fractures. The mean fracture resistance values (in newtons) were obtained as group 1 > group 6 > group 4 > group 3 > group 5 > group 2. Group 6 showed the highest mean fracture resistance value, which was significantly higher than the other experimental groups, and all the fractures occurred at the level of enamel. Within the limitations of this study, a short fiber-reinforced composite can be used as a direct core buildup material that can effectively resist heavy occlusal forces against fracture and may reinforce the remaining tooth structure in endodontically treated teeth. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  19. Die topkwark

    Directory of Open Access Journals (Sweden)

    R. Tegen

    1998-07-01

    Full Text Available ’n Oorsig van die belangrikheid van die onlangs ontdekte topkwark by Fermilab in Chicago word gegee. Daar word aangetnon dat die topkwark belangrik is in fisika van die Oerknal, oftewel "Big Bang", en in die Standaard Model van Elementêredeeltjie-fisika. Toepaslike literatuur vir verdere studie kan van die lys van verwysings in hierdie kort, nietegniese artikel, nagegaan word.

  20. Biosurfactants prevent in vitro Candida albicans biofilm formation on resins and silicon materials for prosthetic devices.

    Science.gov (United States)

    Cochis, Andrea; Fracchia, Letizia; Martinotti, Maria Giovanna; Rimondini, Lia

    2012-06-01

    The aim of this study was to evaluate in vitro the preventive antiadhesion activity of biosurfactants against Candida albicans biofilm. Disks of silicon and acrylic resin for denture prostheses were precoated with increasing concentrations of biosurfactants obtained from endophyte biofilms selected from Robinia pseudoacacia and from Nerium oleander, and afterward infected with C. albicans cells. The number of biofilm cells were detected by colony-forming unit (CFU) counting, cell viability was established by the 2,3-bis(2-methoxy-4-nitro-5-sulphophenyl)-5-[(phenyl amino)carbonyl]-2H-tetrazolium hydroxide (XTT) assay, and biosurfactant cytotoxicity was evaluated by the [3-(4,5-dimethyliazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulphophenyl)-2H-tetrazolium] (MTT) assay. Chlorhexidine was used as control. Precoating with biosurfactants caused a greater reduction (P biosurfactants was observed at low concentrations (78.12 μg/mL and 156.12 μg/mL) which were noncytotoxic. This study demonstrated the preventive antiadhesion activity of biosurfactants against C. albicans biofilm. These agents are amphiphilic, interfere with microbial adhesion, and demonstrate cycompatibility with epithelial cells and fibroblasts. Copyright © 2012 Elsevier Inc. All rights reserved.

  1. Influence of different luting protocols on shear bond strength of computer aided design/computer aided manufacturing resin nanoceramic material to dentin.

    Science.gov (United States)

    Poggio, Claudio; Pigozzo, Marco; Ceci, Matteo; Scribante, Andrea; Beltrami, Riccardo; Chiesa, Marco

    2016-01-01

    The purpose of this study was to evaluate the influence of three different luting protocols on shear bond strength of computer aided design/computer aided manufacturing (CAD/CAM) resin nanoceramic (RNC) material to dentin. In this in vitro study, 30 disks were milled from RNC blocks (Lava Ultimate/3M ESPE) with CAD/CAM technology. The disks were subsequently cemented to the exposed dentin of 30 recently extracted bovine permanent mandibular incisors. The specimens were randomly assigned into 3 groups of 10 teeth each. In Group 1, disks were cemented using a total-etch protocol (Scotchbond™ Universal Etchant phosphoric acid + Scotchbond Universal Adhesive + RelyX™ Ultimate conventional resin cement); in Group 2, disks were cemented using a self-etch protocol (Scotchbond Universal Adhesive + RelyX™ Ultimate conventional resin cement); in Group 3, disks were cemented using a self-adhesive protocol (RelyX™ Unicem 2 Automix self-adhesive resin cement). All cemented specimens were placed in a universal testing machine (Instron Universal Testing Machine 3343) and submitted to a shear bond strength test to check the strength of adhesion between the two substrates, dentin, and RNC disks. Specimens were stressed at a crosshead speed of 1 mm/min. Data were analyzed with analysis of variance and post-hoc Tukey's test at a level of significance of 0.05. Post-hoc Tukey testing showed that the highest shear strength values (P resin cements (coupled with etch and rinse or self-etch adhesives) showed better shear strength values compared to self-adhesive resin cements. Furthermore, conventional resin cements used together with a self-etch adhesive reported the highest values of adhesion.

  2. Cashew nut shell liquid resin used as matrix for compound materials; O LCC (Liquido da castanha do caju) como matriz em materiais compostos

    Energy Technology Data Exchange (ETDEWEB)

    Abreu, Hamilton Ferreira Gomes de; Nogueira, Ricardo Emilio Ferreira Quevedo [Ceara Univ., Fortaleza, CE (Brazil). Dept. de Engenharia Mecanica

    1996-12-31

    Cashew nut shell liquid resin a by product of cashew processing industry is a naturally occurring phenol of low cost and are used in Brazil as fuel in the industrial production of cashew nut or as a structural material when associated with coconut fiber or rice shell. A high measured Tg points to noble applications. This paper presents some properties of LCC resin and concludes that it has good perspectives as a composite matrice to work at elevated temperatures. (author) 5 refs., 4 figs., 2 tabs.

  3. Color stability of nano-filled, micro-hybrid, and silorane-based dental composite resin materials

    Directory of Open Access Journals (Sweden)

    Mohsen Saud M ALShetili

    2016-01-01

    Full Text Available Aim: The purpose of this study was to investigate the color stability of nano-hybrid, micro-hybrid, and silorane-based composite resin restorative materials upon exposure to staining agents. Materials and Methods: One hundred twenty composites samples were prepared, 40 from each composite material (Filtek ® Z350, Filtek ® P90, and Filtek ® Z250. The specimens were randomly divided into four groups (10 of each sample. The specimens were incubated for 24 h in distilled water and then for 72 h in corresponding mediums (distilled water, red grape juice, green tea, coffee. The color of all the specimens was assessed before and after exposure with a spectrophotometer and total color change (ΔE was calculated using ΔEFNx01 = [(ΔLFNx012 + (ΔaFNx012 + (ΔbFNx012]1/2. The data were analyzed with one-way analysis of variance (ANOVA and Kolmogorov-Smirnov and the means of the solutions were compared by Tukey′s honestly significant difference (HSD (P 0.05 discoloration compared with other media. Conclusions: Within the limitations of this study, it may be concluded that silorane-based composites are more resistant to discoloration than bis-GMA-based composites and coffee had the highest effect on composite discoloration compared to other media.

  4. Effect of various dentin disinfection protocols on the bond strength of resin modified glass ionomer restorative material.

    Science.gov (United States)

    Sekhar, Anand; Anil, Akansha; Thomas, Manuel S; Ginjupalli, Kishore

    2017-07-01

    Disinfection of dentin surface prior to any restorative therapy is important for the longevity of the treatment rendered. However, these dentin disinfection methods should itself not interfere with the adhesion of the restorative material. Therefore the aim of this study was to determine the effect of various dentin disinfection protocols on the shear bond strength (SBS) of resin modified glass ionomer cement (RMGIC). The occlusal surface of 40 extracted premolars were trimmed to obtain a flat dentinal surface and was randomly divided into four groups. CTRL was the control group; NaOCl was 1% sodium hypochlorite disinfection group; CHX was 2% chlorhexidine disinfection group; and PAD was the photo-activated disinfection group. Then a predetermined dimension of RMGIC was bonded to the pre-treated dentin surfaces. Following this, each sample was tested for SBS using universal testing machine at a crosshead speed of 0.5mm/min. Among the test groups, CHX showed the least reduction in SBS and NaOCl the highest reduction in SBS as compared to the control group. PAD on the other hand showed significantly lower SBS than CTRL and CHX groups, but the values were higher than the NaOCl group. Thus, it could be concluded from the present study that use of chlorhexidine based dentin disinfection does interfere with the adhesion of RMGIC. However, photo-activated disinfection should be done with caution. Moreover, sodium hypochlorite based disinfectants should be avoided prior to the use of RMGIC. Key words: Chlorhexidine, Dentin disinfection, Photo-activated disinfection, Resin modified glass ionomer cement, Shear bond strength, Sodium hypochlorite.

  5. Comparison of retention rates of fissure sealants using two flowable restorative materials and a conventional resin sealant: two-year follow-up.

    Science.gov (United States)

    Oba, Aylin Akbay; Sönmez, Işıl Şaroğlu; Ercan, Ertuğrul; Dülgergil, Türksel

    2012-01-01

    The purpose of this clinical study was to compare the retention rates of two flowable restorative systems (Admira Flow and Grandio Flow) with that of a conventional resin-based sealant (Fissurit F). The study was planned as a clinical trial with a split-mouth design. A total of 122 sealants (38 Admira Flow, 41 Grandio Flow, 43 Fissurit F) were randomly applied to completely erupted permanent molars in 35 patients aged 9-20 years and followed up for 24 months. Data were analyzed using Pearson's χ(2) and multiple comparison tests. At the end of the follow-up period, Fissurit F had higher retention rates (81.0%) than both Admira Flow (60.5%) and Grandio Flow (57.1%), with p 0.05). The two flowable composite resin materials used as fissure sealant were less retentive than the conventional resin sealant. Copyright © 2011 S. Karger AG, Basel.

  6. Radiopacity and microhardness changes and effect of X-ray operating voltage in resin-based materials before and after the expiration date

    Directory of Open Access Journals (Sweden)

    Tirapelli Camila

    2004-01-01

    Full Text Available This study observed alteration in the radiopacity and microhardness of expired resin-based materials compared to non-expired materials and the operating characteristics of the X-ray source used. Five 2 mm-thick cured specimens were prepared for each material: composite resins (P60®, Z100®, and a compomer (Dyract AP®. Radiopacity of the specimens was evaluated comparing the density of the resin-based material to an equivalent (mm density of a 99.5% pure aluminum step wedge using a transmission densitometer. Surface microhardness measurements were carried out using a calibrated Vickers indenter on three different points of the same surface. ANOVA and Tukey tests (pre-set alpha = 0.05 revealed that expired materials showed no significant change in radiopacity. One material (Filtek P60 demonstrated lower radiopacity with lower KVp. Change in microhardness wa s statistically significant for Z100: for this material, the microhardness after expiration was significantly lower than before the expiration date.

  7. [Determination of high temperature compressive strength and refractory degree of die material compatible with slip casting core of sintered titanium powder].

    Science.gov (United States)

    Kuang, X; Liao, Y; Chao, Y; Meng, Y

    1999-05-01

    The refractory die is the precondition for developing slip casting core of sintered powder. This study is to determine the high temperature properties of the refractory die material compatible with slip casting core. To prepare three cylindrical specimens (phi 10 x 15 mm) and determine their compressive strength at 1000 degrees C: to make four specimens in flat-topped cone for determining the practical refractory degree by decreasing the pressing temperatures in a sequence of 1420, 1400, 1350 and 1100 degrees C. The compressive strength of this material was 17.8 MPa at 1000 degrees C. Its practical refractory degree was higher than 1100 degrees C. The high temperature properties of the refractory die material that we developed meet the demand of slip casting core of sintered powder.

  8. Influence of mechanical and chemical degradation on surface gloss of resin composite materials

    NARCIS (Netherlands)

    Ardu, S.; Braut, V.; Uhac, I.; Benbachir, N.; Feilzer, A.J.; Krejci, I.

    2009-01-01

    Purpose: To determine the changes in surface gloss of different composite materials after simulation of mechanical and chemical aging mechanisms. Methods: 36 specimens were fabricated for each material and polished with 120-, 220-, 500-, 1200-, 2400- and 4000- grit SiC abrasive paper, respectively.

  9. Influence of different luting protocols on shear bond strength of computer aided design/computer aided manufacturing resin nanoceramic material to dentin

    OpenAIRE

    Claudio Poggio; Marco Pigozzo; Matteo Ceci; Andrea Scribante; Riccardo Beltrami; Marco Chiesa

    2016-01-01

    Background: The purpose of this study was to evaluate the influence of three different luting protocols on shear bond strength of computer aided design/computer aided manufacturing (CAD/CAM) resin nanoceramic (RNC) material to dentin. Materials and Methods: In this in vitro study, 30 disks were milled from RNC blocks (Lava Ultimate/3M ESPE) with CAD/CAM technology. The disks were subsequently cemented to the exposed dentin of 30 recently extracted bovine permanent mandibular incisors. The...

  10. Influence of Curing Units and Indirect Restorative Materials on the Hardness of Two Dual-curing Resin Cements Evaluated by the Nanoindentation Test.

    Science.gov (United States)

    Kuguimiya, Rosiane Noqueira; Rode, Kátia Martins; Carneiro, Paula Mendes Acatauassú; Aranha, Ana Cecilia Corrêa; Turbino, Miriam Lacalle

    2015-06-01

    To evaluate the hardness of a dual-curing self-adhesive resin cement (RelyX U200) and a conventional dual-curing resin cement (RelyX ARC) cured with different light curing units of different wavelengths (Elipar Freelight 2 LED [430 to 480 nm, conventional], Bluephase LED [380 to 515 nm, polywave], AccuCure 3000 Laser [488 nm]) by means of the nanoindentation test. Bovine incisors were cleaned and then sectioned at the cementoenamel junction to remove the crown. After embedding in acrylic, dentin surfaces of the specimens were exposed and ground flat to standardize the surfaces. To simulate clinically placing indirect restorations, ceramic (IPS e.maxPress/Ivoclar Vivadent) or indirect composite resin (SR Adoro/Ivoclar Vivadent) slabs were cemented on dentin surfaces. The specimens were sectioned longitudinally at low speed under constant irrigation and then polished. In the positive control group, the cement was light cured without the interposition of indirect restorative material; in the negative control group, after the indirect restorative material was cemented, no light curing was performed, allowing only chemical polymerization of the cement. All specimens were stored in distilled water at 37°C for 7 days. Nanoindentadion hardness of the cement layer was measured under a 100-mN load. Data were statistically analyzed using ANOVA and Tukey's test (p resin cements evaluated was negatively influenced by the interposition of an indirect restorative material; only the LEDs were able to maintain the same degree of cement polymerization when an indirect restorative material was used. The photoactivation step is required during the cementation of indirect restorations to ensure adequate polymerization of dual-curing resin cements.

  11. Implications of resin-based composite (RBC) restoration on cuspal deflection and microleakage score in molar teeth: Placement protocol and restorative material.

    Science.gov (United States)

    McHugh, Lauren E J; Politi, Ioanna; Al-Fodeh, Rami S; Fleming, Garry J P

    2017-09-01

    To assess the cuspal deflection of standardised large mesio-occluso-distal (MOD) cavities in third molar teeth restored using conventional resin-based composite (RBC) or their bulk fill restorative counterparts compared with the unbound condition using a twin channel deflection measuring gauge. Following thermocycling, the cervical microleakage of the restored teeth was assessed to determine marginal integrity. Standardised MOD cavities were prepared in forty-eight sound third molar teeth and randomly allocated to six groups. Restorations were placed in conjunction with (and without) a universal bonding system and resin restorative materials were irradiated with a light-emitting-diode light-curing-unit. The dependent variable was the restoration protocol, eight oblique increments for conventional RBCs or two horizontal increments for the bulk fill resin restoratives. The cumulative buccal and palatal cuspal deflections from a twin channel deflection measuring gauge were summed, the restored teeth thermally fatigued, immersed in 0.2% basic fuchsin dye for 24h, sectioned and examined for cervical microleakage score. The one-way analysis of variance (ANOVA) identified third molar teeth restored using conventional RBC materials had significantly higher mean total cuspal deflection values compared with bulk fill resin restorative restoration (all prestored teeth had significantly the lowest microleakage scores compared with Tetric EvoCeram Bulk Fill (bonded and non-bonded) teeth (all prestoratives behave in a similar manner when used to restore standardised MOD cavities in third molar teeth. It would appear that light irradiation of individual conventional RBCs or bulk fill resin restoratives may be problematic such that material selection is vital in the absence of clinical data. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  12. Effect of asphaltene and resin oils on the viscosity of bituminous petroleum materials to be used as asphalt primers

    Directory of Open Access Journals (Sweden)

    Bencomo, M. R.

    2006-03-01

    Full Text Available The bituminous crude from the Machete, Venezuela, area, which has such a fluid consistency that it falls outside the normal scope of the A5TM D-5 (1 penetration test exceeding the 3D-mm ceiling specified in that standard and can be used as an asphalt primer: Like other asphalt products, these materials are -chemically speaking- a mix of numerous naphthenic, paraffinic and aromatic hydrocarbons and heterocyclic compounds containing sulphur, nitrogen, oxygen and so on. They have a dense and a malthene oil phase which, along with the natural hydrocarbons additives used in these products acts as a volatile fluidizer. The former is described as a mix of asphaltenes: complex high molecular weight substances that are insoluble in paraffinic hydrocarbons and soluble in aromatic compounds such as benzene. The malthene oil phase, in turn, consists in a mix of resins and hydrocarbons and together the two constitute a colloidal system. The experiments discussed in the present paper were conducted to determine the effect of the proportion of asphaltenes and resin oils on the viscosity of such bituminous crude emulsions/ with a view to their use as primers. These experiments were run in a Parr batch reactor in a nitrogen atmosphere using n-heptane as a solvent. The resins were separated after the asphaltenes precipitated from the samples and subsequently from the malthene fraction obtained. The results showed that the asphaltenes account for the structural characteristics and consistency of the medium and the resin oils for its cohesive properties/,the malthene oils act as solvents.Los crudos extrapesados procedentes del área Machete (Venezuela son materiales de consistencia blanda o fluida, por lo que se salen del campo en el que normalmente se aplica el ensayo de penetración a productos asfálticos según el método ASTM D-5 (1, cuyo límite máximo es 30 mm, y pueden ser utilizados como pinturas asfálticas de imprimación. Al igual que otros productos

  13. Drying time of tray adhesive for adequate tensile bond strength between polyvinylsiloxane impression and tray resin material.

    Science.gov (United States)

    Yi, Myong-Hee; Shim, Joon-Sung; Lee, Keun-Woo; Chung, Moon-Kyu

    2009-07-01

    Use of custom tray and tray adhesive is clinically recommended for elastomeric impression material. However there is not clear mention of drying time of tray adhesive in achieving appropriate bonding strength of tray material and impression material. This study is to investigate an appropriate drying time of tray adhesives by evaluating tensile bonding strength between two types of polyvinylsiloxane impression materials and resin tray, according to various drying time intervals of tray adhesives, and with different manufacturing company combination of impression material and tray adhesive. Adhesives used in this study were Silfix (Dentsply Caulk, Milford, Del, USA) and VPS Tray Adhesive (3M ESPE, Seefeld, Germany) and impression materials were Aquasil Ultra (monophase regular set, Dentsply Caulk, Milford, Del, USA) and Imprint II Garant (regular body, 3M ESPE, Seefeld, Germany). They were used combinations from the same manufacture and exchanged combinations of the two. The drying time was designed to air dry, 5 minutes, 10 minutes, 15 minutes, 20 minutes, and 25 minutes. Total 240 of test specimens were prepared by auto-polymerizing tray material (Instant Tray Mix, Lang, Wheeling, Il, USA) with 10 specimens in each group. The specimens were placed in the Universal Testing machine (Instron, model 3366, Instron Corp, University avenue, Nowood, MA, USA) to perform the tensile test (cross head speed 5 mm/min). The statistically efficient drying time was evaluated through ANOVA and Scheffe test. All the tests were performed at 95% confidence level. The results revealed that at least 10 minutes is needed for Silfix-Aquasil, and 15 minutes for VPS Tray Adhesive-Imprint II, to attain an appropriate tensile bonding strength. VPS Tray Adhesive-Imprint II had a superior tensile bonding strength when compared to Silfix-Aquasil over 15 minutes. Silfix-Aquasil had a superior bonding strength to VPS Tray Adhesive-Aquasil, and VPS Tray Adhesive-Imprint II had a superior tensile

  14. Penetration of a resin-based filling material into lateral root canals and quality of obturation by different techniques.

    Science.gov (United States)

    Michelotto, André Luiz da Costa; Moura-Netto, Cacio; Araki, Angela Toshie; Akisue, Eduardo; Sydney, Gilson Blitzkow

    2015-01-01

    The aim of this study was to evaluate the penetration of a resin/polyester polymer-based material (Resilon Real Seal; SybronEndo Corp., Orange, USA) into simulated lateral canals, and the quality of obturations by different techniques. A total of 30 standardized simulated canals were divided into three groups according to the technique of obturation used: MS (McSpadden), SB (SystemB/Obtura II), and LC (Lateral Condensation). To analyze the penetration of the filling material, the simulated canals were digitalized and the images were analyzed using the Leica QWIN Pro v2.3 software. The data of the middle and apical thirds were separately submitted to analysis of variance (ANOVA), followed by the Tukey's test for the comparison of the techniques. Results showed a significant difference (p test on interexaminer agreement and the nonparametric Kruskal-Wallis test indicated no significant difference between filling techniques. It was concluded that Resilon achieves greater levels of penetration when associated with thermoplastic obturation techniques.

  15. [Contact allergy to epoxy resins plastics based on materials collected by the Nofer Institute of Occupational Medicine].

    Science.gov (United States)

    Kieć-Swierczyńska, Marta; Krecisz, Beata

    2003-01-01

    Of the 5604 patients examined in 1984-2001 for suspected occupational dermatitis, 160 persons (2.8%) showed allergy to epoxy resins plastics. Allergy was more frequent in men (4.9%) than in women (1.2%); in 154 persons, allergy was of occupational etiology (in a group of 160 patients with allergy to epoxy resins, the following proportions were observed: bricklayers, platelayers--17.5%; fitters, turners, machinist millers--13.8%; plastics molders--13.1%; laminators--11.3%; electrical equipment assemblers--10.6%; painters--10.0%). Having compared the frequency of allergy to components of epoxy resins in the years 1984-1993 and 1994-2001, it was found that allergy to resin, reactive diluents and plasticizers was on increase, whereas allergy to amines and acid anhydrides hardeners was on decrease. In a group of 13 chemical compounds entering into the composition of epoxy resins, epoxy resin contributed to the largest number of positive patch tests (77.5% of epoxy-allergic persons). This was followed by triethylenetetramine (23.1%), ethylenediamine (13.1%), phthalic anhydride (8.1%), diethylenetetramine (6.9%) and phenylglycidylether (6.2%). In addition, three patients reacted to both epoxy resin and cycloaliphatic resin.

  16. Surface tridimensional topography analysis of materials and finishing procedures after resinous infiltration of subsurface bovine enamel lesions.

    Science.gov (United States)

    Mueller, Jan; Yang, Fan; Neumann, Konrad; Kielbassa, Andrej M

    2011-02-01

    To evaluate the effects of materials and finishing procedures on the surface roughness of infiltrated subsurface bovine enamel lesions. Eighty enamel specimens were prepared from 80 bovine incisors and partially varnished (control). The nonvarnished areas were demineralized (pH 4.95, 28 days) and etched with phosphoric acid gel (20%, 5 seconds). Specimens were randomly divided into two groups, which were each split into four subgroups (each n = 10): E1/E2 (Excite, Ivoclar Vivadent), F1/F2 (Fortify, Bisco), G1/G2 (Glaze and Bond, DMG), and I1/I2 (Icon, DMG). In group 1, resin materials were polymerized and polished using finishing strips by means of a polishing device; in group 2, excess material was removed with a rubber cup before polymerization (without polishing). The surface roughness (Sa) of control, demineralized, and treated surfaces were evaluated topometrically using a focus variation 3D scanning microscope. Demineralized surfaces were significantly rougher than sound enamel (P < .0005, t test). Etching increased Sa significantly to more than 450% of demineralization values (P < .0005). Surfaces of nonpolished infiltrated lesions were significantly rougher than demineralized enamel (P < .0005), while no significant differences could be found among infiltrated subgroups (P = .067), nor between polished and nonpolished groups (P = .359). Application of Glaze and Bond (G2) appeared to reduce Sa values of etched lesions (P < .0005), while with all other subgroups Sa values improved only marginally. Regarding surface roughness, the use of finishing strips after infiltration of subsurface lesions does not seem to be advantageous. Excess material should be removed before light curing, but surface quality of nonprocessed infiltrants seems to be perfectible.

  17. A Comparative Evaluation of Accuracy of the Dies Affected by Tray Type, Material Viscosity, and Pouring Sequence of Dual and Single Arch Impressions- An In vitro Study.

    Science.gov (United States)

    Kulkarni, Poonam R; Kulkarni, Rahul S; Shah, Rupal J; Chhajlani, Rahul; Saklecha, Bhuwan; Maru, Kavita

    2017-04-01

    The clinician's skill, impression techniques, and materials play a very important role in recording fine details in an impression for accuracy of fixed partial denture prosthesis. Impression of prepared teeth and of the opposing arch can be recorded simultaneously by dual-arch trays, while the full arch metal trays are used for impressions of prepared teeth in one arch. To measure and compare the accuracy of working dies made from impressions with metal and plastic dual arch trays and metal full arch trays, for two viscosities of impression material and by changing the sequence of pour of working and non-working sides. A balanced design with independent samples was used to study the three variables (tray type, impression material viscosity, and pouring sequence). An impression made by dual arch trays and single arch trays were divided in to three groups (Group A-plastic dual arch tray, Group B-metal dual arch tray, Group C-full arch metal stock tray). Out of these three groups, two groups (Group A and B) were subdivided in to four subgroups each and one group (Group C) was subdivided in to two subgroups. A sample size of 30 was used in each subgroup yielding a total 300 impressions in three groups or ten subgroups. Impressions were made of a machined circular stainless steel die. All three dimensions (Occlusogingival, Mesiodistal, and Buccolingual) of the working dies as well as stainless steel standard die were measured three times, and the mean was used for the three standard sample values to which all working dies means were compared. Statistical analysis used for this study was a 3-factor analysis of variance with hypothesis testing at α =0.05. With respect to the selection of impression material viscosity statistically significant differences were found in the dies for the buccolingual and mesiodistal dimensions. Metal dual arch trays were slightly more accurate in the mesiodistal dimension in comparison to the plastic trays in reference of tray selection and

  18. Novel nano-particles as fillers for an experimental resin-based restorative material.

    Science.gov (United States)

    Rüttermann, S; Wandrey, C; Raab, W H-M; Janda, R

    2008-11-01

    The purpose of this study is to compare the properties of two experimental materials, nano-material (Nano) and Microhybrid, and two trade products, Clearfil AP-X and Filtek Supreme XT. The flexural strength and modulus after 24h water storage and 5000 thermocycles, water sorption, solubility and X-ray opacity were determined according to ISO 4049. The volumetric behavior (DeltaV) after curing and after water storage was investigated with the Archimedes principle. ANOVA was calculated with p<0.05. Clearfil AP-X showed the highest flexural strength (154+/-14 MPa) and flexural modulus (11,600+/-550 MPa) prior to and after thermocycling (117+/-14 MPa and 13,000+/-300 MPa). The flexural strength of all materials decreased after thermocycling, but the flexural modulus decreased only for Filtek Supreme XT. After thermocycling, there were no significant differences in flexural strength and modulus between Filtek Supreme XT, Microhybrid and Nano. Clearfil AP-X had the lowest water sorption (22+/-1.1 microg mm(-3)) and Nano had the highest water sorption (82+/-2.6 microg mm(-3)) and solubility (27+/-2.9 microg mm(-3)) of all the materials. No significant differences occurred between the solubility of Clearfil AP-X, Filtek Supreme XT and Microhybrid. Microhybrid and Nano provided the highest X-ray opacity. Owing to the lower filler content, Nano showed higher shrinkage than the commercial materials. Nano had the highest expansion after water storage. After thermocycling, Nano performed as well as Filtek Supreme XT for flexural strength, even better for X-ray opacity but significantly worse for flexural modulus, water sorption and solubility. The performances of microhybrids were superior to those of the nano-materials.

  19. Physical Property Investigation of Contemporary Glass lonomer and Resin Modified Glass lonomer Restorative Materials

    Science.gov (United States)

    2016-05-24

    Innovation in Direct Restorative Materials. Adv Dent Res 2013;25:8-17. 4. Wilson AD, Kent BE. The glass-ionomer cement , a new translucent dental filling...material. J Appl Chem 1971;21:313. 5. Wilson AD, Batchelor RF. Dental silicate cements I. The chemistry of erosion. J Dent Res 1967;46:1078-85. 6...modlfied glass-ionomer dental cements . Biomater 2002;23: 3289-3295. 42. Young A, Sherpa G, Pearson B, Schottlander, Waters DN. Use of Raman Spectroscopy

  20. Clinical evaluation of a new art material: Nanoparticulated resin-modified glass ionomer cement

    Science.gov (United States)

    Konde, S.; Raj, S.; Jaiswal, D.

    2012-01-01

    Context: The success of atraumatic restorative treatment (ART) technique depends on the restorative material; hence, clinical studies with various materials are necessary. Aim: The aim of the present study was to clinically evaluate and compare the nanoionomer and high-viscosity glass ionomer using United States Public Health Services (USPHS) Modified Cvar/Ryge Criteria with ART approach. Materials and Methods: Two primary molars in 50 healthy children aged between 5 and 8 years were selected for the study. The teeth were treated with ART and divided into two groups. The group 1 teeth were restored with nanoionomer (Ketac Nano 100 3M ESPE) and group 2 with high-viscosity glass ionomer cement (HVGIC), (Fuji IX GC). Each restoration was evaluated using the USPHS Modified Cvar/Ryge Criteria at baseline and 6 months’ and 12 months’ time interval. Statistical analysis used: Chi-squared (χ2) test. Results: Nanoionomer was significantly better than HVGIC with respect to color match at baseline, 6 months, and 12 months (P0.05), but at 12 months, nanoionomer was statistically better than HVGIC (P0.05). Conclusion: The results indicate that nanoionomer can be a successful alternative restorative material for use with ART technique. PMID:24478966

  1. Microtensile Bond Strength of New Ceramic/Polymer Materials Repaired with Composite Resin

    Science.gov (United States)

    2015-06-30

    surface texture due to larger filler particles 4 and greater wear of the composite matrix material. The aforementioned study reported that...DVA, Corona , CA). Each bar specimen was loaded to failure, at a cross-head speed of 1mm/min on a universal testing machine (Model 5943, Instron

  2. Method of removing contaminants from plastic resins

    Energy Technology Data Exchange (ETDEWEB)

    Bohnert, George W. (Harrisonville, MO); Hand, Thomas E. (Lee' s Summit, MO); DeLaurentiis, Gary M. (Jamestown, CA)

    2008-11-18

    A method for removing contaminants from synthetic resin material containers using a first organic solvent system and a second carbon dioxide system. The organic solvent is utilized for removing the contaminants from the synthetic resin material and the carbon dioxide is used to separate any residual organic solvent from the synthetic resin material.

  3. Method of removing contaminants from plastic resins

    Energy Technology Data Exchange (ETDEWEB)

    Bohnert,George W. (Harrisonville, MO); Hand,Thomas E. (Lee' s Summit, MO); Delaurentiis,Gary M. (Jamestown, CA)

    2007-08-07

    A method for removing contaminants from synthetic resin material containers using a first organic solvent system and a second carbon dioxide system. The organic solvent is utilized for removing the contaminants from the synthetic resin material and the carbon dioxide is used to separate any residual organic solvent from the synthetic resin material.

  4. Method for removing contaminants from plastic resin

    Science.gov (United States)

    Bohnert, George W.; Hand, Thomas E.; DeLaurentiis, Gary M.

    2008-12-30

    A method for removing contaminants from synthetic resin material containers using a first organic solvent system and a second carbon dioxide system. The organic solvent is utilized for removing the contaminants from the synthetic resin material and the carbon dioxide is used to separate any residual organic solvent from the synthetic resin material.

  5. Green material composites from renewable resources: Polymorphic transitions and phase diagram of beeswax/rosin resin

    Energy Technology Data Exchange (ETDEWEB)

    Gaillard, Yves [Mines-ParisTech., CEMEF, UMR CNRS 7635, 1 rue Claude Daunesse 06904 Sophia Antipolis cedex (France); Mija, Alice [University of Nice-Sophia Antipolis, Thermokinetic Group, Laboratory of Chemistry of Organic and Metallic Materials C.M.O.M., 06108 Nice Cedex 2 (France); Burr, Alain; Darque-Ceretti, Evelyne; Felder, Eric [Mines-ParisTech., CEMEF, UMR CNRS 7635, 1 rue Claude Daunesse 06904 Sophia Antipolis cedex (France); Sbirrazzuoli, Nicolas, E-mail: sbirrazz@unice.fr [University of Nice-Sophia Antipolis, Thermokinetic Group, Laboratory of Chemistry of Organic and Metallic Materials C.M.O.M., 06108 Nice Cedex 2 (France)

    2011-07-10

    Highlights: {yields} Blends of Rosin and beeswax are studied by DSC, XRD, and optical microscopy. {yields} The first phase diagram beeswax/rosin is established. {yields} Polymorphic transitions are identified and appear to be highly related to rosin content. - Abstract: Rosin and beeswax are two complex natural materials presenting numerous applications in paints, adhesives, varnishes or inks. Melted, they are particularly interesting for their adhesion properties. This paper establishes the first phase diagram beeswax/rosin blends. A systematic approach using X-ray diffraction (XRD), differential scanning calorimetry (DSC) and polarised optical microscopy (POM) has been performed in order to describe the crystallographic structure and the thermal properties of two materials, beeswax and rosin, and their blends. Indeed, melting, softening and crystallisation temperatures, polymorphic transitions but also crystalline index has been investigated. The resulting phase diagram reveals a complex behaviour in terms of phase transformation and time-dependent phenomenon mainly representative of the complex composition of beeswax.

  6. Effects of air abrasion with alumina or glass beads on surface characteristics of CAD/CAM composite materials and the bond strength of resin cements

    Directory of Open Access Journals (Sweden)

    ARAO Nobuaki

    2015-12-01

    Full Text Available ABSTRACT Objective The study aimed to evaluate effects of air abrasion with alumina or glass beads on bond strengths of resin cements to CAD/CAM composite materials. Material and Methods CAD/CAM composite block materials [Cerasmart (CS and Block HC (BHC] were pretreated as follows: (a no treatment (None, (b application of a ceramic primer (CP, (c alumina-blasting at 0.2 MPa (AB, (d AB followed by CP (AB+CP, and (e glass-beads blasting at 0.4 MPa (GBB followed by CP (GBB+CP. The composite specimens were bonded to resin composite disks using resin cements [G-CEM Cerasmart (GCCS and ResiCem (RC]. The bond strengths after 24 h (TC 0 and after thermal cycling (TC 10,000 at 4–60°C were measured by shear tests. Three-way ANOVA and the Tukey compromise post hoc tests were used to analyze statistically significant differences between groups (α=0.05. Results For both CAD/CAM composite materials, the None group exhibited a significant decrease in bond strength after TC 10,000 (p0.05. The AB+CP group showed a significantly higher bond strength after TC 10,000 than did the AB group for RC (p<0.05, but not for GCCS. The GBB+CP group showed the highest bond strength for both thermal cyclings (p<0.05. Conclusions Air abrasion with glass beads was more effective in increasing bond durability between the resin cements and CAD/CAM composite materials than was using an alumina powder and a CP.

  7. Adhesion of resin materials to S2-glass unidirectional and E-glass multidirectional fiber reinforced composites: effect of polymerization sequence protocols.

    Science.gov (United States)

    Polacek, Petr; Pavelka, Vladimir; Ozcan, Mutlu

    2013-12-01

    To evaluate the effect of different polymerization sequences employed during application of bis-GMAbased particulate filler composites (PFC) or a flowable resin (FR) on fiber-reinforced composite (FRC). Unidirectional, pre-impregnated S2-glass fibers (Dentapreg) and multidirectional preimpregnated E-glass fibers (Dentapreg) (length: 40 mm; thickness: 0.5 mm) were obtained (N = 144, n = 12 per group) and embedded in translucent silicone material with the adhesion surface exposed. The resulting specimens were randomly divided into 12 groups for the following application sequences: a) FRC+PFC (photopolymerized in one step), b) FRC+FR (photopolymerized in one step), c) FRC+PFC (photopolymerized individually), d) FRC+FR (photopolymerized individually), e) FRC (photopolymerized)+intermediate adhesive resin and PFC (photopolymerized in one step), f) FRC (photopolymerized)+intermediate adhesive resin and FR (photopolymerized in one step). The sequences of unidirectional (groups a to f) were repeated for multidirectional (groups g to l) FRCs. PFCs were debonded from the FRC surfaces using the shear bond test in a universal testing machine (1 mm/min). On additional specimens from each FRC type, thermogravimetric analysis (TGA) was performed to characterize the fiber weight content (Wf) (N = 6, n = 3 per group). After debonding, all specimens were analyzed using SEM to categorize the failure modes. The data were statistically analyzed using 3-way ANOVA and Tukey's tests (α = 0.05). Significant effects of the FRC type (S2 or E-glass) (p resin type (PFC or FR) (p TGA revealed 55 ± 3 wt% fiber content for multidirectional and 60 ± 3 wt% for unidirectional FRCs tested. Multidirectional pre-impregnated E-glass fibers cannot be recommended in combination with the PFC and FR materials tested in this study. Application of an intermediate adhesive resin layer increases the adhesion of both PFC and FR to unidirectional FRC. FRC and FR can be polymerized in one step, but FRC and PFC

  8. Effect of gamma irradiation on fluoride release and antibacterial activity of resin dental materials

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Fabiola Galbiatti de; Fucio, Suzana Beatriz Portugal de; Correr-Sobrinho, Lourenco [Universidade Estadual de Campinas (UNICAMP), Piracicaba, SP (Brazil). Piracicaba Dental School. Dept. of Dental Materials; Pascon, Fernanda Miori; Kantovitz, Kamila Rosamilia; Puppin-Rontani, Regina Maria [Universidade Estadual de Campinas (UNICAMP), Piracicaba, SP (Brazil). Piracicaba Dental School. Dept. of Pedriatric Dentistry], e-mail: rmpuppin@fop.unicamp.br

    2009-07-01

    This study evaluated the effect of gamma irradiation on fluoride release and antibacterial activity of FluroShield (FS) and Clearfil Protect Bond (CPB). Four groups were formed: G1-FS + gamma; G2-FS without gamma; G3-CPB + gamma; G4-CPB without gamma. For fluoride release analysis, 12 disks of each material were prepared and covered with nail polish, except for one side (50.4 mm{sup 2} area). G1 and G3 were sterilized with a 14.5 KGy dose at 27 deg C for 24 h, while G2 and G4 (controls) were not sterilized and were maintained under the same time and temperature conditions. Fluoride release measurements were made in duplicate (n=6) by an ion specific electrode. The antibacterial activity of the CPB and FS against Streptococcus mutans after gamma sterilization was evaluated by the agar-disc diffusion method. The diameter of the zones of microbial growth inhibition was recorded after 48 h. Data were analyzed statistically by ANOVA and Tukey's test (alpha=5%). Gamma sterilization decreased the fluoride release of FS by approximately 50%, while CPB was not affected. There was no statistically significant difference (p>0.05) in the antibacterial effect of CPB between gamma and non-gamma sterilization groups. FS presented no antibacterial activity. Gamma irradiation decreased the fluoride release of FS, but did not affect the antibacterial activity of the studied materials. (author)

  9. Effect of gamma irradiation on fluoride release and antibacterial activity of resin dental materials

    International Nuclear Information System (INIS)

    Carvalho, Fabiola Galbiatti de; Fucio, Suzana Beatriz Portugal de; Correr-Sobrinho, Lourenco; Pascon, Fernanda Miori; Kantovitz, Kamila Rosamilia; Puppin-Rontani, Regina Maria

    2009-01-01

    This study evaluated the effect of gamma irradiation on fluoride release and antibacterial activity of FluroShield (FS) and Clearfil Protect Bond (CPB). Four groups were formed: G1-FS + gamma; G2-FS without gamma; G3-CPB + gamma; G4-CPB without gamma. For fluoride release analysis, 12 disks of each material were prepared and covered with nail polish, except for one side (50.4 mm 2 area). G1 and G3 were sterilized with a 14.5 KGy dose at 27 deg C for 24 h, while G2 and G4 (controls) were not sterilized and were maintained under the same time and temperature conditions. Fluoride release measurements were made in duplicate (n=6) by an ion specific electrode. The antibacterial activity of the CPB and FS against Streptococcus mutans after gamma sterilization was evaluated by the agar-disc diffusion method. The diameter of the zones of microbial growth inhibition was recorded after 48 h. Data were analyzed statistically by ANOVA and Tukey's test (alpha=5%). Gamma sterilization decreased the fluoride release of FS by approximately 50%, while CPB was not affected. There was no statistically significant difference (p>0.05) in the antibacterial effect of CPB between gamma and non-gamma sterilization groups. FS presented no antibacterial activity. Gamma irradiation decreased the fluoride release of FS, but did not affect the antibacterial activity of the studied materials. (author)

  10. Amalgam or composite resin? Factors influencing the choice of restorative material.

    Science.gov (United States)

    Correa, M B; Peres, M A; Peres, K G; Horta, B L; Barros, A D; Demarco, F F

    2012-09-01

    This study aimed to investigate the patient and tooth factors associated with selection of restorative material in direct posterior restorations in young adults from a population-based birth cohort. A representative sample (n=720) of all 5914 births occurring in Pelotas in 1982 were prospectively investigated, and posterior restorations were assessed in 2006, when the patients were 24 years old. Tooth-related variables (individual level) included restorative material (amalgam or composite), type of tooth, size of cavity, and estimated time in mouth. Data regarding demographic and socio-economic characteristics, oral health, and service utilization patterns during the life course were also assessed (contextual level). Logistic Regression Multilevel models showed that individuals who have accessed dental services by private insurance by age 15 [odds ratio (OR)=1.66 (0.93-2.95)] and who had a higher dental caries index at age 15 (high DMFT tertile) [OR 2.89 (1.59-5.27)] presented more amalgam restorations in the posterior teeth. From tooth-level variables, the frequency of amalgams decreases with increasing number of surfaces enrolled in the cavity preparation (pcomposite or amalgam in posterior direct restorations, showing that, independently of socioeconomic and demographic characteristics, type of payment of dental services and clinical factors are associated with this choice. Copyright © 2012. Published by Elsevier Ltd.

  11. Die belangrikste kenmerk van die diereproduksie- bedrywe oor die ...

    African Journals Online (AJOL)

    Die belangrikste kenmerk van die diereproduksie- bedrywe oor die afgelope paar dekades was die neiging tot die reorganisasie van die produksiestelsels. Hoewel dit die verste gevorder het in die geval van pluimvee-, vark· en beesproduksiestelsels is daar by die tradisioneel eksten- siewe skaapbedryf ook duidelike ...

  12. Radiation resistance of the carbon fiber reinforced composite material with PEEK as the matrix resin

    International Nuclear Information System (INIS)

    Sasuga, Tsuneo; Seguchi, Tadao; Sakai, Hideo; Nakakura, Toshiyuki; Masutani, Masahiro.

    1987-01-01

    In the fast breeder reactor etc. the structural materials are exposed to various environment, i.e., repeated high and low temperature, stress, etc. Irradiation effect (electron radiation) in the mechanical characteristic at low and high temperature has been studied in the PEEK-CF, polyarylether · ether · ketone - carbon fiber composite. Following are the results. (1) Radiation resistance of PEEK-CF is higher than that of PEEK-PES-CF, PEEK - polyethersulfone surface treated CF composite. In PEEK-PES-CF, PES is deteriorated by irradiation so the adhesive power lowers. (2) In the unirradiated PEEK-CF, its mechanical characteristic decreases beyond 140 deg C. With increase of the radiation dose, however, the characteristic rises. (3) Mechanical characteristic of PEEK-CF thus little drops by the heat treatment after the irradiation. (Mori, K.)

  13. die rol van die unieverdedigingsmag in die onderdrukking van die ...

    African Journals Online (AJOL)

    reik, terwyl ander weer te min kampeeruitrusting ontvang het. In sommige gebiede moes heelwat voorrade ook inderhaas uit plaaslike bronne aangevul word. Daar is ook gevind dat daar nie genoeg gewere in die Unie beskikbaar was nie. Gevolglik is daar reelings met die Britse regering getref vir die verskaffing daarvan.

  14. Bio-active glass air-abrasion has the potential to remove resin composite restorative material selectively

    International Nuclear Information System (INIS)

    Milly, Hussam; Andiappan, Manoharan; Thompson, Ian; Banerjee, Avijit

    2014-01-01

    The aims of this study were to assess: (a) the chemistry, morphology and bioactivity of bio-active glass (BAG) air-abrasive powder, (b) the effect of three air-abrasion operating parameters: air pressure, powder flow rate (PFR) and the abrasive powder itself, on the selective removal of resin composite and (c) the required “time taken”. BAG abrasive particles were characterised using scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX) and Fourier-transform infrared spectroscopy (FTIR). Standardised resin composite restorations created within an enamel analogue block (Macor™) in vitro, were removed using air-abrasion undersimulated clinical conditions. 90 standardised cavities were scanned before and after resin composite removal using laser profilometry and the volume of the resulting 3D images calculated. Multilevel linear model was used to identify the significant factors affecting Macor™ removal. BAG powder removed resin composite more selectively than conventional air-abrasion alumina powder using the same operating parameters (p < 0.001) and the effect of altering the unit's operating parameters was significant (p < 0.001). In conclusion, BAG powder is more efficient than alumina in the selective removal of resin composite particularly under specific operating parameters, and therefore may be recommended clinically as a method of preserving sound enamel structure when repairing and removing defective resin composite restorations.

  15. Bio-active glass air-abrasion has the potential to remove resin composite restorative material selectively

    Energy Technology Data Exchange (ETDEWEB)

    Milly, Hussam [Biomaterials, Biomimetics and Biophotonics Research Group, Kings College London Dental Institute at Guy' s Hospital, King' s Health Partners, London (United Kingdom); Andiappan, Manoharan [Unit of Dental Public Health, Kings College London Dental Institute at Guy' s Hospital, King' s Health Partners, London (United Kingdom); Thompson, Ian [Biomaterials, Biomimetics and Biophotonics Research Group, Kings College London Dental Institute at Guy' s Hospital, King' s Health Partners, London (United Kingdom); Banerjee, Avijit, E-mail: avijit.banerjee@kcl.ac.uk [Biomaterials, Biomimetics and Biophotonics Research Group, Kings College London Dental Institute at Guy' s Hospital, King' s Health Partners, London (United Kingdom); Unit of Conservative Dentistry, King' s College London Dental Institute at Guy' s Hospital, King' s Health Partners, London (United Kingdom)

    2014-06-01

    The aims of this study were to assess: (a) the chemistry, morphology and bioactivity of bio-active glass (BAG) air-abrasive powder, (b) the effect of three air-abrasion operating parameters: air pressure, powder flow rate (PFR) and the abrasive powder itself, on the selective removal of resin composite and (c) the required “time taken”. BAG abrasive particles were characterised using scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX) and Fourier-transform infrared spectroscopy (FTIR). Standardised resin composite restorations created within an enamel analogue block (Macor™) in vitro, were removed using air-abrasion undersimulated clinical conditions. 90 standardised cavities were scanned before and after resin composite removal using laser profilometry and the volume of the resulting 3D images calculated. Multilevel linear model was used to identify the significant factors affecting Macor™ removal. BAG powder removed resin composite more selectively than conventional air-abrasion alumina powder using the same operating parameters (p < 0.001) and the effect of altering the unit's operating parameters was significant (p < 0.001). In conclusion, BAG powder is more efficient than alumina in the selective removal of resin composite particularly under specific operating parameters, and therefore may be recommended clinically as a method of preserving sound enamel structure when repairing and removing defective resin composite restorations.

  16. Preparation and characterization of hybrid materials of epoxy resin type bisphenol a with silicon and titanium oxides by sol-gel process

    International Nuclear Information System (INIS)

    Carrillo C, A.; Osuna A, J. G.

    2011-01-01

    Hybrid materials were synthesized from epoxy resins as a result bisphenol type A-silicon oxide and epoxy resin bisphenol type A-titanium oxide were obtained. The synthesis was done by sol-gel process using tetraethyl orthosilicate (Teos) and titanium isopropoxide (I Ti) as inorganic precursors. The molar ratio of bisphenol A to the inorganic precursors was the studied variable. The materials were characterized by thermal analysis, infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The hybrid nature of the materials was demonstrated through thermal analysis and infrared spectroscopy. In both systems, as the amount of alkoxide increased, the bands described above were more defined. This behavior indicates the interactions between the resin and the alkoxides. Hybrids with Teos showed a smoother and homogeneous surface in its entirety, without irregularities. Hybrids with titanium isopropoxide had low roughness. Both Teos and I Ti hybrids showed a decrease on the atomic weight percentage of carbon due to a slight reduction of the organic part on the surface. (Author)

  17. Preparation and characterization of hybrid materials of epoxy resin type bisphenol a with silicon and titanium oxides by sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Carrillo C, A.; Osuna A, J. G., E-mail: acc.carrillo@gmail.com [Universidad Autonoma de Coahuila, Facultad de Ciencias Quimicas, Blvd. Venustiano Carranza y Jose Cardenas Valdes, 25000 Saltillo, Coahuila (Mexico)

    2011-07-01

    Hybrid materials were synthesized from epoxy resins as a result bisphenol type A-silicon oxide and epoxy resin bisphenol type A-titanium oxide were obtained. The synthesis was done by sol-gel process using tetraethyl orthosilicate (Teos) and titanium isopropoxide (I Ti) as inorganic precursors. The molar ratio of bisphenol A to the inorganic precursors was the studied variable. The materials were characterized by thermal analysis, infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The hybrid nature of the materials was demonstrated through thermal analysis and infrared spectroscopy. In both systems, as the amount of alkoxide increased, the bands described above were more defined. This behavior indicates the interactions between the resin and the alkoxides. Hybrids with Teos showed a smoother and homogeneous surface in its entirety, without irregularities. Hybrids with titanium isopropoxide had low roughness. Both Teos and I Ti hybrids showed a decrease on the atomic weight percentage of carbon due to a slight reduction of the organic part on the surface. (Author)

  18. Effect of LED-LCU light irradiance distribution on mechanical properties of resin based materials.

    Science.gov (United States)

    Magalhães Filho, T R; Weig, K M; Costa, M F; Werneck, M M; Barthem, R B; Costa Neto, C A

    2016-06-01

    The objective of this study is to analyze the light power distribution along the tip end of the light guide of three LED-LCUs (Light Curing Units) and to evaluate its effect on the mechanical properties of a polymer based dental composite. Firstly, the light power distribution over the whole area of LED-LCU light guide surface was analyzed by three methods: visual projection observation, spectral measurement and optical spectral analysis (OSA). The light power distribution and the total irradiance were different for the three LEDs used, but the wavelength was within the camphorquinone absorption spectrum. The use of a blank sheet was quite on hand to make a qualitative analysis of a beam, and it is costless. Secondly, specimens of a hybrid composite with approximately 8mm diameter and 2mm thickness were produced and polymerized by 20s exposition time to each LED-LCU. Thirdly, the elastic modulus (E) and hardness (HV) were measured throughout the irradiated area by instrumented micro-indentation test (IIT), allowing to correlate localized power and mechanical properties. Both E and HV showed to be very sensitive to local power and wavelength dependent, but they followed the beam power profile. It was also shown that the mechanical properties could be directly correlated to the curing process. Very steep differences in mechanical properties over very short distances may impair the material performance, since residual stresses can easily be built over it. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Preparation of CMC-modified melamine resin spherical nano-phase change energy storage materials.

    Science.gov (United States)

    Hu, Xiaofeng; Huang, Zhanhua; Zhang, Yanhua

    2014-01-30

    A novel carboxymethyl cellulose (CMC)-modified melamine-formaldehyde (MF) phase change capsule with excellent encapsulation was prepared by in situ polymerization. Effects of CMC on the properties of the capsules were studied by Fourier transformation infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electronic microscopy (SEM), X-ray diffractometry (XRD), and thermogravimetric analysis (TGA). The results showed that the CMC-modified capsules had an average diameter of about 50nm and good uniformity. The phase change enthalpy of the capsules was increased and the cracking ratio decreased by incorporating a suitable amount of CMC. The optimum phase change enthalpy of the nanocapsules was 83.46J/g, and their paraffin content was 63.1%. The heat resistance of the capsule shells decreased after CMC modification. In addition, the nanocapsule cracking ratio of the nanocapsules was 11.0%, which is highly attractive for their application as nano phase change materials. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. In vitro shear bond strength of Y-TZP ceramics to different core materials with the use of three primer/resin cement systems.

    Science.gov (United States)

    Al-Harbi, Fahad A; Ayad, Neveen M; Khan, Zahid A; Mahrous, Amr A; Morgano, Steven M

    2016-01-01

    Durability of the bond between different core materials and zirconia retainers is an important predictor of the success of a dental prosthesis. Nevertheless, because of its polycrystalline structure, zirconia cannot be etched and bonded to a conventional resin cement. The purpose of this in vitro study was to compare the effects of 3 metal primer/resin cement systems on the shear bond strength (SBS) of 3 core materials bonded to yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramic retainers. Zirconia ceramic (Cercon) disks (5×3 mm) were airborne-particle abraded, rinsed, and air-dried. Disk-shaped core specimens (7×7 mm) that were prepared of composite resin, Ni-Cr, and zirconia were bonded to the zirconia ceramic disks by using one of 3 metal primer/cement systems: (Z-Prime Plus/BisCem, Zirconia Primer/Multilink Automix, or Clearfil Ceramic Primer/Clearfil SA). SBS was tested in a universal testing machine. Stereomicroscopy was used to evaluate the failure mode of debonded specimens. Data were analyzed using 2-way ANOVA and post hoc analysis using the Scheffe procedure (α=.05). Clearfil SA/Clearfil Ceramic Primer system with an Ni-Cr core yielded the highest SBS value (19.03 MPa), whereas the lowest SBS value was obtained when Multilink Automix/Zirconia Primer system was used with the zirconia core group (4.09 MPa). Differences in mean SBS values among the cement/primer groups were statistically significant, except for Clearfil SA and BisCem with both composite resin and zirconia cores. Differences in mean SBS values among the core subgroups were not statistically significant, except for zirconia core with BisCem, Multilink, and Clearfil SA. The predominant failure mode was adhesive, except for Clearfil SA and BisCem luting agents with composite resin cores, which displayed cohesive failure, and Multilink Automix with a composite resin, core as well as Clearfil SA with Ni-Cr cores, where the debonded specimens of each group displayed a mixed

  1. Die funksie van die belydenis in die struktuur van die kerk en die ...

    African Journals Online (AJOL)

    Ter wille van die argument wat in hierdie voordrag na vore gebring word, word vier sodanige konstituerende elemente van die kerklike struktuur onderskei, te wete die belydenis, die teologie, die verkondi- ging (meer bepaald die prediking) en die kerkorde (kerkwet volgens ons terminologie). Ons gaan nou elkeen hiervan ...

  2. Modeling of ultrasonic wave propagation in composite materials obtained by the resin transfer molding process; Modelisation de la propagation ultrasonore dans les materiaux composites obtenus par le procede de fabrication RTM (Resin Transfer Molding)

    Energy Technology Data Exchange (ETDEWEB)

    Lonne, S.

    2003-11-01

    The Resin Transfer Molding process for manufacturing composite materials is used to produce parts of complex shape. During the ultrasonic examination of such parts, attenuation is measured to characterize possible porosity content (a potential defect in this material). However, strong variation of attenuation is observed including on sound plates. The present study aims at explaining this by developing a model for ultrasonic propagation and attenuation in such parts which complex microstructure exhibits a multiple-scale aspect. An original model has been developed to predict attenuation at the elementary scale of an unidirectional layer of carbon fibers in an epoxy matrix. It couples multiple scattering by fibers and viscoelastic losses phenomena. It has been experimentally validated and applies to arbitrary two-phase fiber reinforced composites whatever the fiber volume fraction. At the upper scale of a ply made of several elementary layers of various orientations, the anisotropic behavior of ultrasonic waves and their attenuation are obtained by a homogenization procedure. An actual plate is made of several plies separated by pure resin layers. Plies and layers thicknesses are highly variable. A statistical study has been conducted to evaluate the influence of these geometrical variations on the ultrasonic transmission predicted by a model derived from Thomson-Haskell formalism. Ultrasonic attenuation variability practically observed is quantitatively reproduced and explained as resulting from the geometrical irregularity of the microstructure. (author)

  3. Die Elementarkonstanten und die Mathematik

    Science.gov (United States)

    Rompe, Robert; Treder, Hans-Jürgen

    Die Elementarkonstanten im Sinne von Max Planck sind von ähnlicher Bedeutung wie die reinen Zahlen der Mathematik. Die Newtonschen Prinzipien und die Elementarkonstanten zusammen sind der Grundbau der physikalischen Theoriebildung.Translated AbstractThe Elementary Constants and the MathematicThe elementary constants in the sense of Max Planck are of analogous meaning as the pure numbers in mathematics. The Newtonian principles together with the elementary constants are the basis for creating physical theories.

  4. Effect of bulk-fill base material on fracture strength of root-filled teeth restored with laminate resin composite restorations.

    Science.gov (United States)

    Taha, N A; Maghaireh, G A; Ghannam, A S; Palamara, J E

    2017-08-01

    To evaluate the effect of using a bulk-fill flowable base material on fracture strength and fracture patterns of root-filled maxillary premolars with MOD preparations restored with laminate restorations. Fifty extracted maxillary premolars were selected for the study. Standardized MOD cavities with endodontic treatment were prepared for all teeth, except for intact control. The teeth were divided randomly into five groups (n=10); (Group 1) sound teeth, (Group 2) unrestored teeth; (Group 3) MOD cavities with Vitrebond base and resin-based composite (Ceram. X One Universal); (Group 4) MOD cavities with 2mm GIC base (Fuji IX GP) and resin-based composite (Ceram. X One Universal) open laminate, (Group 5) MOD cavities were restored with 4mm of bulk-fill flowable base material (SDR) and resin-based composite (Ceram. X One Universal). All teeth were thermocycled and subjected to a 45° ramped oblique load in a universal testing machine. Fracture load and fracture patterns were recorded. Data were analyzed using one-way ANOVA and Dunnett's T3 test. Restoration in general increased the fracture strength compared to unrestored teeth. The fracture strength of group 5 (bulk-fill) was significantly higher than the fracture strength of the GIC laminate groups and not significantly different from the intact teeth (355±112N, P=0.118). The type of failure was unfavorable for most of the groups, with the majority being mixed failures. The use of a bulk-fill flowable base material significantly increased the fracture strength of extracted root-filled teeth with MOD cavities; however it did not improve fracture patterns to more favorable ones. Investigating restorative techniques that may improve the longevity of root-filled premolar teeth restored with direct resin restorations. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. The SEWD guideline on the security of other radioactive materials. What are the consequences for radiography?; Die SEWD-Richtlinie zur Sicherung von sonstigen radioaktiven Stoffen. Was bedeutet dies fuer die Radiographie?

    Energy Technology Data Exchange (ETDEWEB)

    Kosbadt, Oliver [Ministerium fuer Umwelt, Klima und Energiewirtschaft, Stuttgart (Germany)

    2017-08-01

    The situation of an aggravated international terroristic threat since the attacks in 2001 has invoked the consideration of abusive use of radioactive materials. In Germany the SEWD guideline for requirements concerning ''other'' radioactive materials including the evaluation of the hazard potential of radioactive materials, security categories, safety requirements and related security measures for different applications. The nondestructive materials testing will be concerned by this guideline due to the application of radioactive sources with high activity. The contribution discusses the most important aspects.

  6. Effects of Er:YAG laser and air abrasion on the microleakage of a resin-based fissure sealant material.

    Science.gov (United States)

    Sancakli, Hande Sar; Erdemir, Ugur; Yildiz, Esra

    2011-07-01

    The aim of the present study was to evaluate the effects of different surface pre-treatment techniques on the microleakage of a resin-based fissure sealant material. Thirty-five molars were divided into the following seven groups based on the surface pre-treatment technique used: (a) Erbium: Yttrium Aluminium Garnet (Er:YAG) laser (7 W); (b) Er:YAG laser (7 W)+acid etching (with 37% phosphoric acid); (c) Er:YAG laser (5.5 W); (d) Er:YAG laser (5.5 W)+acid etching; (e) air abrasion+acid etching; (f) air abrasion; and (g) conventional acid etching. The sealant was placed according to the manufacturers' instructions and light-cured for 20 sec. The sealed teeth were thermocycled for 10,000 cycles (5°-55°C), then immersed in 5% methylene blue for 24 h and sectioned mesiodistally. Each section was analyzed and photographed using a light microscope. Microleakage was assessed quantitatively by the degree of dye penetration and also qualitatively, scored on a three-point rating scale. Data were analyzed by one-way analysis of variance (ANOVA) and the Kruskal-Wallis test. The level of significance was set at p laser irradiation exhibited significantly higher microleakage than those conditioned with air abrasion followed by acid etching, and those conditioned with conventional acid etching (p Air abrasion followed by acid etching, as well as conventional acid etching, provided a sufficient seal, whereas laser irradiation alone or in combination with acid etching exhibited higher microleakage than did the other groups. Conventional acid etching remains the most effective and the simplest technique.

  7. Development of a novel resin-based dental material with dual biocidal modes and sustained release of Ag+ ions based on photocurable core-shell AgBr/cationic polymer nanocomposites.

    Science.gov (United States)

    Cao, Weiwei; Zhang, Yu; Wang, Xi; Chen, Yinyan; Li, Qiang; Xing, Xiaodong; Xiao, Yuhong; Peng, Xuefeng; Ye, Zhiwen

    2017-07-01

    Research on the incorporation of cutting-edge nano-antibacterial agent for designing dental materials with potent and long-lasting antibacterial property is demanding and provoking work. In this study, a novel resin-based dental material containing photocurable core-shell AgBr/cationic polymer nanocomposite (AgBr/BHPVP) was designed and developed. The shell of polymerizable cationic polymer not only provided non-releasing antibacterial capability for dental resins, but also had the potential to polymerize with other methacrylate monomers and prevented nanoparticles from aggregating in the resin matrix. As a result, incorporation of AgBr/BHPVP nanocomposites did not adversely affect the flexural strength and modulus but greatly increased the Vicker's hardness of resin disks. By continuing to release Ag + ions without the impact of anaerobic environment, resins containing AgBr/BHPVP nanoparticles are particularly suitable to combat anaerobic cariogenic bacteria. By reason of the combined bactericidal effect of the contact-killing cationic polymers and the releasing-killing Ag + ions, AgBr/BHPVP-containing resin disks had potent bactericidal activity against S. mutans. The long-lasting antibacterial activity was also achieved through the sustained release of Ag + ions due to the core-shell structure of the nanocomposites. The results of macrophage cytotoxicity showed that the cell viability of dental resins loading less than 1.0 wt% AgBr/BHPVP was close to that of neat resins. The AgBr/BHPVP-containing dental resin with dual bactericidal capability and long term antimicrobial effect is a promising material aimed at preventing second caries and prolonging the longevity of resin composite restorations.

  8. Die teologie in gesprek met die ekonomie

    African Journals Online (AJOL)

    diktaat van die regte rede' is en John Locke (1632-1704), wie se rasionalisering van die samelewing die beste daarin slaag om uitdrukking te gee aan die wese van die opkomende Britse liberalisme van die sewentiende eeu. 2^ 'n Samelewing waarin die ekonomie die bepalende posisie inneem. Die samelewing wat ...

  9. DIE GEESTESSTRUKTUUR VAN DIE ONGELOOF In die studie van ...

    African Journals Online (AJOL)

    Test

    BACON (1561-1626), oor die algemeen erken as die vader van die empirisme, het met sy idole-leer 'n geweldige invloed uitgeoefen. Die idole-leer neem aan dat die werklikheid deur die mens se verstand geken kan word en wel op grond van die natuurlike vermoë van die verstand. Daar is egter allerlei hindernisse in ons ...

  10. Shear bond strength of a new self-adhering flowable composite resin for lithium disilicate-reinforced CAD/CAM ceramic material

    Science.gov (United States)

    Sancakli, Hande Sar; Sancakli, Erkan; Eren, Meltem Mert; Ozel, Sevda; Yucel, Taner; Yildiz, Esra

    2014-01-01

    PURPOSE The purpose of this study was to evaluate and compare the effects of different surface pretreatment techniques on the surface roughness and shear bond strength of a new self-adhering flowable composite resin for use with lithium disilicate-reinforced CAD/CAM ceramic material. MATERIALS AND METHODS A total of one hundred thirty lithium disilicate CAD/CAM ceramic plates with dimensions of 6 mm × 4 mm and 3 mm thick were prepared. Specimens were then assigned into five groups (n=26) as follows: untreated control, coating with 30 µm silica oxide particles (Cojet™ Sand), 9.6% hydrofluoric acid etching, Er:YAG laser irradiation, and grinding with a high-speed fine diamond bur. A self-adhering flowable composite resin (Vertise Flow) was applied onto the pre-treated ceramic plates using the Ultradent shear bond Teflon mold system. Surface roughness was measured by atomic force microscopy. Shear bond strength test were performed using a universal testing machine at a crosshead speed of 1 mm/min. Surface roughness data were analyzed by one-way ANOVA and the Tukey HSD tests. Shear bond strength test values were analyzed by Kruskal-Wallis and Mann-Whitney U tests at α=.05. RESULTS Hydrofluoric acid etching and grinding with high-speed fine diamond bur produced significantly higher surface roughness than the other pretreatment groups (Presin used as repair composite resin exhibited very low bond strength irrespective of the surface pretreatments used. PMID:25551002

  11. Die posisie van die Helper in die sending

    Directory of Open Access Journals (Sweden)

    I. J. van der Walt

    1972-05-01

    Full Text Available Gedurende die aanvangsjare van die sending het die helper ’n onmisbare funksie vervul. Hulle het die onherbergsame binnelande geken, waardevolle kontakpunte vir die sendelinge geopen en hulle mense geestelik help voorlig en voorberei.

  12. Biokompatibilitas Gelas Ionomer Modifikasi Resin

    OpenAIRE

    Rotua Lestari M

    2008-01-01

    Saat ini banyak berkembang material baru dalam dunia kedokteran gigi diantaranya adalah Gelas ionomer modifikasi resin yang dikembangkan untuk mengatasi kekurangan-kekurangan dari gelas ionomer konvensional. Adanya penambahan monomer resin daIam bentuk 2-hydroxyethylmetacylate (HEMA) telah meningkatkan kekuatan dari bahan ini. Gelas ionomer modifikasi resin mempunyai sifat-sifat fisis dan mekanis yang lebih baik dibandingkan dengan gelas ionomer konvensional. Gelas ionomer modifikasi ...

  13. Light Transmission of Novel CAD/CAM Materials and Their Influence on the Degree of Conversion of a Dual-curing Resin Cement.

    Science.gov (United States)

    Egilmez, Ferhan; Ergun, Gulfem; Cekic-Nagas, Isil; Vallittu, Pekka K; Lassila, Lippo V J

    To evaluate the light transmission characteristics of different types, shades, and thicknesses of novel CAD/CAM materials and their effect on the degree of conversion (DC) of a dual-curing resin cement. Square specimens (12 × 12 mm2) of three CAD/CAM materials - GC Cerasmart, Lava Ultimate, Vita Enamic - of different thicknesses (1.00, 1.50, and 2.00 mm, n = 5 per thickness) were irradiated with an LED unit. The amount of transmitted light was quantified. Thereafter, the DC% of the dual-curing resin cement (RelyX Ultimate) was recorded after 15 min using Fourier transform infrared spectroscopy. Statistical analysis was performed using two-way ANOVA followed by the Tukey's HSD post-hoc test at a significance level of p light irradiation (p  0.05). Conversely, material thickness significantly affected light transmission (p light irradiation; p = 0.637 for DC). Linear regression analysis showed a correlation between delivered energy and DC% results of the Vita Enamic (R² = 0.4169, p light transmission in 2-mm-thick specimens of all CAD/CAM materials indicates that proper curing of the cement beneath CAD/CAM materials should be ensured.

  14. Sputtered protective coatings for die casting dies

    Science.gov (United States)

    Mirtich, M. J.; Nieh, C.-Y.; Wallace, J. F.

    1981-01-01

    Three experimental research designs investigating candidate materials and processes involved in protective die surface coating procedures by sputter deposition, using ion beam technologies, are discussed. Various pre-test results show that none of the coatings remained completely intact for 15,000 test cycles. The longest lifetime was observed for coatings such as tungsten, platinum, and molybdenum which reduced thermal fatigue, but exhibited oxidation and suppressed crack initiation only as long as the coating did not fracture. Final test results confirmed earlier findings and coatings with Pt and W proved to be the candidate materials to be used on a die surface to increase die life. In the W-coated specimens, which remained intact on the surface after thermal fatigue testing, no oxidation was found under the coating, although a few cracks formed on the surface where the coating broke down. Further research is planned.

  15. The effect of Er,Cr:YSGG laser application on the micropush-out bond strength of fiber posts to resin core material.

    Science.gov (United States)

    Kurtulmus-Yilmaz, Sevcan; Cengiz, Esra; Ozan, Oguz; Ramoglu, Serhat; Yilmaz, Hasan Guney

    2014-10-01

    The aim of this study was to compare the effects of erbium, chromium: yttrium, scandium, gallium, and garnet (Er,Cr:YSGG) laser application to different surface treatments on the micropush-out bond strengths between glass and quartz fiber posts and composite resin core material. Different types of lasers have been used as an alternative to airborne particle abrasion and other surface treatment methods to enhance the bond strength of dental materials. However, there is no study regarding the use of Er,Cr:YSGG laser as a surface treatment method for fiber posts in order to improve the bond strength. Ninety-six quartz and 96 glass fiber posts with a coronal diameter of 1.8 mm were randomly divided into eight groups according the surface treatments applied. Gr 1 (control, no surface treatment), Gr 2 (sandblasting with 50 μm Al2O3), Gr 3 (9 % hydrofluoric acid for 1 min), Gr 4 (24% H2O2 for 1 min), Gr 5 (CH2Cl2 for 1 min), Gr 6 (1 W), Gr 7 (1.5 W), and Gr 8 (2 W) Er,Cr:YSGG laser irradiation. The resin core material was applied to each group, and then 1 mm thick discs (n=12) were obtained for the micropush-out test. Data were statistically analyzed. For the quartz fiber post group, all surface treatments showed significantly higher micropush-out bond strengths than the control group (pmaterial. However, the hydroflouric acid group showed the lowest bond strength values. The type of post and surface treatment might affect the bond strength between fiber posts and resin core material; 1 W and 1.5 W Er,Cr:YSGG laser application improved adhesion at the post/core interface.

  16. Influence of halogen irradiance on short- and long-term wear resistance of resin-based composite materials.

    LENUS (Irish Health Repository)

    Bhamra, Gurcharn S

    2009-02-01

    The Oregon Health Science University (OHSU) four-chamber oral wear simulator was used to examine the impact of halogen irradiance on the short- and long-term wear behavior of four-methacrylate resin-based composites (RBCs). The hypothesis proposed was that exacerbated wear would occur following the long-term wear of RBCs irradiated under non-optimized irradiance conditions.

  17. Autoclave processing for composite material fabrication. 1: An analysis of resin flows and fiber compactions for thin laminate

    Science.gov (United States)

    Hou, T. H.

    1985-01-01

    High quality long fiber reinforced composites, such as those used in aerospace and industrial applications, are commonly processed in autoclaves. An adequate resin flow model for the entire system (laminate/bleeder/breather), which provides a description of the time-dependent laminate consolidation process, is useful in predicting the loss of resin, heat transfer characteristics, fiber volume fraction and part dimension, etc., under a specified set of processing conditions. This could be accomplished by properly analyzing the flow patterns and pressure profiles inside the laminate during processing. A newly formulated resin flow model for composite prepreg lamination process is reported. This model considers viscous resin flows in both directions perpendicular and parallel to the composite plane. In the horizontal direction, a squeezing flow between two nonporous parallel plates is analyzed, while in the vertical direction, a poiseuille type pressure flow through porous media is assumed. Proper force and mass balances have been made and solved for the whole system. The effects of fiber-fiber interactions during lamination are included as well. The unique features of this analysis are: (1) the pressure gradient inside the laminate is assumed to be generated from squeezing action between two adjacent approaching fiber layers, and (2) the behavior of fiber bundles is simulated by a Finitely Extendable Nonlinear Elastic (FENE) spring.

  18. Analysis of Capillary Coating Die Flow in an Optical Fiber Coating Applicator

    OpenAIRE

    Kyoungjin Kim

    2011-01-01

    Viscous heating becomes significant in the high speed resin coating process of glass fibers for optical fiber manufacturing. This study focuses on the coating resin flows inside the capillary coating die of optical fiber coating applicator and they are numerically simulated to examine the effects of viscous heating and subsequent temperature increase in coating resin. Resin flows are driven by fast moving glass fiber and the pressurization at the coating die inlet, while ...

  19. Shear bond strength of a new self-adhering flowable composite resin for lithium disilicate-reinforced CAD/CAM ceramic material.

    Science.gov (United States)

    Erdemir, Ugur; Sancakli, Hande Sar; Sancakli, Erkan; Eren, Meltem Mert; Ozel, Sevda; Yucel, Taner; Yildiz, Esra

    2014-12-01

    The purpose of this study was to evaluate and compare the effects of different surface pretreatment techniques on the surface roughness and shear bond strength of a new self-adhering flowable composite resin for use with lithium disilicate-reinforced CAD/CAM ceramic material. A total of one hundred thirty lithium disilicate CAD/CAM ceramic plates with dimensions of 6 mm × 4 mm and 3 mm thick were prepared. Specimens were then assigned into five groups (n=26) as follows: untreated control, coating with 30 µm silica oxide particles (Cojet™ Sand), 9.6% hydrofluoric acid etching, Er:YAG laser irradiation, and grinding with a high-speed fine diamond bur. A self-adhering flowable composite resin (Vertise Flow) was applied onto the pre-treated ceramic plates using the Ultradent shear bond Teflon mold system. Surface roughness was measured by atomic force microscopy. Shear bond strength test were performed using a universal testing machine at a crosshead speed of 1 mm/min. Surface roughness data were analyzed by one-way ANOVA and the Tukey HSD tests. Shear bond strength test values were analyzed by Kruskal-Wallis and Mann-Whitney U tests at α=.05. Hydrofluoric acid etching and grinding with high-speed fine diamond bur produced significantly higher surface roughness than the other pretreatment groups (Presin used as repair composite resin exhibited very low bond strength irrespective of the surface pretreatments used.

  20. A novel specimen-preparing method using epoxy resin as binding material for LIBS analysis of powder samples.

    Science.gov (United States)

    Shi, Linli; Lin, Qingyu; Duan, Yixiang

    2015-11-01

    In view of the inevitable preprocessing of powder samples for LIBS detection, epoxy resin glue was investigated for the first time as a binder of powder samples due to its superior property of improved performance in laser induced breakdown spectroscopy (LIBS) technique as a quantitative analytical tool. For comparative studies of the epoxy resin and traditional polyethylene (PE) pellets in soil, sample detection, the signal intensities of Fe (I) at 404.58 nm, Ca (I) at 443.57 nm, and Cr (I) at 453.52 nm, were studied and subsequently, the calibration curves for these elements were constructed using the standard samples with variable concentrations. The signal intensities of epoxy resin samples were, on average, about 2 times greater than those obtained with the traditional PE pellet samples. Meanwhile, the resin samples showed better R square values of 0.981, 0.985 and 0.979 for curves of Fe (I) 404.58 nm, Ca (I) 443.57 nm, and Cr (I) 453.52 nm, compared to the 0.974, 0.950 and 0.934, of the PE pellet samples. Furthermore, the former represented lower limits of detection (LOD) for Fe, Ca and Cr. These experimental results indicated that this proposed novel method based on epoxy resin can attach samples of properties of high homogeneity, cohesiveness, smoothness and hardness, which are conducive to system stability, testing accuracy and signal enhancement. This method can make LIBS more practical in powder sample analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. die rol van die eerste suid- afrikaanse infanteriedivisie tydens die ...

    African Journals Online (AJOL)

    Teen die einde van Julie 1942 het 'n tydelike skaakmatsituasie in die oorlog in Noord-Afrika ontstaan. Genl. C.J.E.. Auchinleck, gesamentlik in bevel van die Britsemagte in die Midde Ooste en die 8ste Leer in Egipte, het laasge- noemde by EIAlamein tot die verde- diging loot oorgaan en die oppo- nerende magte het begin ...

  2. Effect of silver-supported materials on the mechanical and antibacterial properties of reinforced acrylic resin composites

    International Nuclear Information System (INIS)

    Han, Zhihui; Zhu, Bangshang; Chen, Rongrong; Huang, Zhuoli; Zhu, Cailian; Zhang, Xiuyin

    2015-01-01

    Highlights: • The novel Novaron-nano-ZrO 2 –ABW/PMMA composites was synthesized. • Nano-ZrO 2 and ABWs could increase the mechanical behavior of this composites. • Novaron had synergistic effect to improve the composites mechanical property and the 4 wt% was the optimal proportion. • Novaron could improve the antibacterial properties through their direct contact with the bacteria. • The composites did not have an adverse affect on cell viability. - Abstract: The aim of this study was to investigate the effect of silver-supported material (Novaron (N)) in acrylic resin (poly(methyl methacrylate) (PMMA)) composites, which reinforced with zirconium dioxide nanoparticles (nano-ZrO 2 ) and aluminum borate whiskers (ABWs), on the mechanical behavior, antibacterial properties and cytotoxicity. Silanized ABWs (4 wt%) and nano-ZrO 2 (2 wt%) were mixed with PMMA powder to obtain nano-ZrO 2 –ABW/PMMA matrices. Various amounts of Novaron particles were incorporated into the matrices and the pure PMMA to test the flexural strength. In addition, Streptococcus mutans (S. mutans) and Canidia albicans (C. albicans) biofilms on the specimen surface and in the culture medium were investigated for metabolic activity and colony-forming units (CFUs). Extracts taken in the cell culture medium of the specimens were used to evaluate cell viability. Results showed that the silanized nano-ZrO 2 and ABWs could improve the flexural strength of composites compared with the pure PMMA. Novaron itself had no mechanical function for composites while it had synergistic effect when it mixed with silanized nano-ZrO 2 and ABWs. And when 4 wt% (N-4) Novaron mixed in nano-ZrO 2 –ABW/PMMA composites, flexural strength achieved an increase of 44%, getting the maximum value. For the antibacterial properties, the values of MTT and CFUs of S. mutans and C. albicans biofilms on the composites surface were greatly reduced (p < 0.05) with the higher proportion of Novaron, and no significant

  3. In vitro evaluation of topical fluoride pH and their effect on surface hardness of composite resin-based restorative materials.

    Science.gov (United States)

    Mujeeb, Abdul; Mansuri, Samir; Hussain, Seema Abid; Ramaswamy, Kausar

    2014-03-01

    The aim of the study was to correlate the pH and fluoride ion uptake with surface hardness of composite resin based restorative materials after topical fluoride application. Forty disks of each of test materials Composite (Filtek Z350XT, 3M ESPE, St Paul, MN, USA), Resin modified glass ionomer (Vitremer) and Compomer (Dyract AP) were made and ten disks of each material were placed in different test solutions - 1.23% APF gel, Sodium fluoride mouth rinse, 0.9% neutral fluoride and distilled water (Control group). After 36 hours of immersion, specimens were subjected to microhardness testing machine for evaluation of surface hardness. The greater hardness deterioration for all materials resulted with 1.23% APF gel when compared to the control group. Composite (Filtek Z350XT, 3M ESPE, St Paul, MN, USA) showed 17.13 VHN (control group 59.11 VHN). Vitremer showed 9.71 VHN (control group 37.71 VHN). Compomer showed 19.22 VHN (control group 36.78 VHN). 1.23% ApF gel significantly decreased hardness of composite, Vitremer and Compomer. Hardness deterioration associated with sodium fluoride mouth rinse and 0.9% neutral fluoride was less compared to 1.23% ApF gel.

  4. Comparative evaluation of shear bond strength of three resin based dual-cure core build-up materials: An In-vitro study.

    Science.gov (United States)

    Jain, Gaurav; Narad, Aditi; Boruah, Lalit C; Rajkumar, Balakrishnan

    2015-01-01

    The in-vitro study compared the shear bond strength (SBS) of three recently introduced dual-cure resin based core build-up materials namely ParaCore, FluoroCore, and MultiCore. One hundred twenty extracted permanent human mandibular molar teeth were taken and sectioned horizontally beneath the dentinoenamel junction to expose the coronal dentin. The specimens obtained were divided into three main groups based on the materials used and then further divided into four sub-groups based on time interval with ten samples each. The dentin surface was treated with the respective adhesives of the groups and then bulk filled with core build-up materials. The attained samples were than subjected to shear loading in Instron Universal Testing Machine. The data were tabulated and statistically analyzed using analysis of variance (ANOVA), Tukey's HSD, and Levene's test. The mean SBS was highest in MultiCore at all time periods as compared to FluoroCore and ParaCore and was also higher at 48 h thermocycling in all three groups studied. MultiCore dual-cure resin based core build-up material showed the highest mean SBS as compared to FluoroCore and ParaCore. SBS was not negatively affected by thermocycling.

  5. In Vitro Solubility and Wear Rates of Silorane and Dimethacrylate Resin Based Composite Restorative Materials under Different pH Conditions

    Science.gov (United States)

    Soliman, Tarek A; Tubaigy, Khalid M; Raffat, Eman M; Al-Agha, Ebaa I

    2015-01-01

    Background: The purpose of this study was to evaluate the effect of different pH solutions on the solubility and wear resistance of Silorane and dimethacrylate resin based composite restorative materials. Materials and Methods: Two different resin based restorative materials (Filtek Silorane P90 and hybrid composite Z100) were tested. Different pH solutions (2.5 and 5) also were used. A total of 60 samples of each type of selected composite were prepared. Specimens were immersed in each type of pH solutions (2.5 and 5) and distilled water as a control group for 24 h then the specimens was subjected to the required mechanical tests. Results: Significant statistical differences were observed regarding water solubility and wear values in different pH solutions. Filtek Silorane presented the smallest values of water solubility and wear values. Conclusion: Under tested experimental conditions, the pH solutions used in this study showed pronounced effect on water solubility and wear values of both two restorative materials. Finally, within the limitation of this study we recommended to use Filtek Silorane (P90) instead of hybrid (Z100) due to its low solubility values under different pH solutions. PMID:26225097

  6. Raw materials and energy - effects of globalization on the safety of German's supply sufficiency; Rohstoffe und Energie. Auswirkungen der Globalisierung auf die Versorgungssicherheit Deutschlands

    Energy Technology Data Exchange (ETDEWEB)

    Wellmer, F.W. [Technische Univ. Berlin (Germany)

    2001-07-01

    Raw material deposits are not mobile, so globalisation has always been an important element of raw materials production and trade. Raw materials production and transport should be regarded as a large-scale system. Lower freight rates have made overseas transport possible even for bulk raw materials. If we look at Germany's raw materials supply, we find that we are customers buying from the whole world. [German] Da Lagerstaetten ortsgebunden sind, ist Globalisierung seit jeher ein wesentliches Element von Rohstoffgewinnung und handel. Rohstoffgewinnung und Transportmoeglichkeiten muessen als Grosssystem betrachtet werden. Nicht zuletzt wegen der gesunkenen Frachtraten ist der ueberseeische Transport heute selbst fuer Massenrohstoffe moeglich geworden. Betrachtet man die Rohstoffversorgung Deutschlands, wird deutlich, dass wir Kunde der ganzen Welt sind. (orig.)

  7. The influence of resin flexural modulus on the magnitude of ceramic strengthening.

    LENUS (Irish Health Repository)

    Fleming, Garry J P

    2012-07-01

    The aim was to determine the magnitude of ceramic resin-strengthening with resin-based materials with varying flexural moduli using a regression technique to assess the theoretical strengthening at a \\'zero\\' resin-coating thickness. The hypothesis tested was that experimentally, increasing resin flexural modulus results in increased resin-strengthening observed at a theoretical \\'zero\\' resin-coating thickness.

  8. Surface hardness evaluation of different composite resin materials: influence of sports and energy drinks immersion after a short-term period

    Directory of Open Access Journals (Sweden)

    Ugur Erdemir

    2013-04-01

    Full Text Available Objectives: This study evaluated the effect of sports and energy drinks on the surface hardness of different composite resin restorative materials over a 1-month period. Material and Methods: A total of 168 specimens: Compoglass F, Filtek Z250, Filtek Supreme, and Premise were prepared using a customized cylindrical metal mould and they were divided into six groups (N=42; n=7 per group. For the control groups, the specimens were stored in distilled water for 24 hours at 37°C and the water was renewed daily. For the experimental groups, the specimens were immersed in 5 mL of one of the following test solutions: Powerade, Gatorade, X-IR, Burn, and Red Bull, for two minutes daily for up to a 1-month test period and all the solutions were refreshed daily. Surface hardness was measured using a Vickers hardness measuring instrument at baseline, after 1-week and 1-month. Data were statistically analyzed using Multivariate repeated measure ANOVA and Bonferroni's multiple comparison tests (α=0.05. Results: Multivariate repeated measures ANOVA revealed that there were statistically significant differences in the hardness of the restorative materials in different immersion times (p<0.001 in different solutions (p<0.001. The effect of different solutions on the surface hardness values of the restorative materials was tested using Bonferroni's multiple comparison tests, and it was observed that specimens stored in distilled water demonstrated statistically significant lower mean surface hardness reductions when compared to the specimens immersed in sports and energy drinks after a 1-month evaluation period (p<0.001. The compomer was the most affected by an acidic environment, whereas the composite resin materials were the least affected materials. Conclusions: The effect of sports and energy drinks on the surface hardness of a restorative material depends on the duration of exposure time, and the composition of the material.

  9. A new technology for separation and recovery of materials from waste printed circuit boards by dissolving bromine epoxy resins using ionic liquid

    International Nuclear Information System (INIS)

    Zhu, P.; Chen, Y.; Wang, L.Y.; Qian, G.Y.; Zhou, M.; Zhou, J.

    2012-01-01

    Highlights: ► WPCBs were heated in [EMIM + ][BF 4 − ] for recovering solider at 240 °C. ► The bromine epoxy resins in WPCBs were all dissolved in [EMIM + ][BF 4 − ] at 260 °C. ► Used [EMIM + ][BF 4 − ] is treated by water to obtain regeneration. - Abstract: Recovery of valuable materials from waste printed circuit boards (WPCBs) is quite difficult because WPCBs is a heterogeneous mixture of polymer materials, glass fibers, and metals. In this study, WPCBs was treated using ionic liquid (1-ethyl-3-methylimizadolium tetrafluoroborate [EMIM + ][BF 4 − ]). Experimental results showed that the separation of the solders went to completion, and electronic components (ECs) were removed in WPCBs when [EMIM + ][BF 4 − ] solution containing WPCBs was heated to 240 °C. Meanwhile, metallographic observations verified that the WPCBs had an initial delamination. When the temperature increased to 260 °C, the separation of the WPCBs went to completion, and coppers and glass fibers were obtained. The used [EMIM + ][BF 4 − ] was treated by water to generate a solid–liquid suspension, which was separated completely to obtain solid residues by filtration. Thermal analyses combined with infrared ray spectra (IR) observed that the solid residues were bromine epoxy resins. NMR (nuclear magnetic resonance) showed that hydrogen bond played an important role for [EMIM + ][BF 4 − ] dissolving bromine epoxy resins. This clean and non-polluting technology offers a new way to recycle valuable materials from WPCBs and prevent environmental pollution from WPCBs effectively.

  10. A new technology for separation and recovery of materials from waste printed circuit boards by dissolving bromine epoxy resins using ionic liquid.

    Science.gov (United States)

    Zhu, P; Chen, Y; Wang, L Y; Qian, G Y; Zhou, M; Zhou, J

    2012-11-15

    Recovery of valuable materials from waste printed circuit boards (WPCBs) is quite difficult because WPCBs is a heterogeneous mixture of polymer materials, glass fibers, and metals. In this study, WPCBs was treated using ionic liquid (1-ethyl-3-methylimizadolium tetrafluoroborate [EMIM+][BF4-]). Experimental results showed that the separation of the solders went to completion, and electronic components (ECs) were removed in WPCBs when [EMIM+][BF4-] solution containing WPCBs was heated to 240 °C. Meanwhile, metallographic observations verified that the WPCBs had an initial delamination. When the temperature increased to 260 °C, the separation of the WPCBs went to completion, and coppers and glass fibers were obtained. The used [EMIM+][BF4-] was treated by water to generate a solid-liquid suspension, which was separated completely to obtain solid residues by filtration. Thermal analyses combined with infrared ray spectra (IR) observed that the solid residues were bromine epoxy resins. NMR (nuclear magnetic resonance) showed that hydrogen bond played an important role for [EMIM+][BF4-] dissolving bromine epoxy resins. This clean and non-polluting technology offers a new way to recycle valuable materials from WPCBs and prevent environmental pollution from WPCBs effectively. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

  11. Development of in-situ observation system of dynamic contact interface between dies and materials during microforming operation

    Directory of Open Access Journals (Sweden)

    Shimizu Tetsuhide

    2015-01-01

    Full Text Available Application of diamond like carbon (DLC films are reported in several microforming processes, in view of its great tribological performance owe to the low friction and the high chemical stability. However, due to its high internal residual stress, the film properties with the low adhesion strength and the high wear rate under severe tribological conditions are still remain as technical issues. However, since the dynamic variation of the contact state cannot be observed during the forming operation, it is difficult to recognize the origin and the influential tribological factors of tool life for DLC coated microforming die. Therefore, the appropriate DLC film properties for the contact state in microforming operation have not been clarified. To observe the dynamic variation of the contact state during the microforming operation, present study developed a novel microforming die assembly installed the in-situ observation system with silica glass die and high speed recording camera. By using this system, the dynamic delamination behaviour of DLC films during the progressive micro-bending process was successfully demonstrated. The influential factors for the durability of DLC coated microdies were discussed.

  12. Cumulative effect of microwave sterilization on the physical properties of microwave polymerized and conventional heat-polymerized acrylic resin

    Directory of Open Access Journals (Sweden)

    S Mohammed Shafeeq

    2016-01-01

    Full Text Available Aims: To evaluate and compare the flexural strength and impact strength of conventional and microwave cured denture base resins before and after repeated sterilization using microwave energy to consider microwave curing as an alternative to the conventional method of sterilization. Materials and Methods: The conventional heat cure acrylic resin (DPI heat cure material Group A and microwave-polymerized acrylic resin (Vipi Wave Acrylic resin Group B were used to fabricate 100 acrylic resins samples using a standard metal die of (86 mm × 11 mm × 3 mm dimensions. The criterion was flexural strength and impact strength testing which had Group A and Group B samples; 50 samples for flexural strength and 50 samples for impact strength measurement. For each criterion, five control samples were taken for Group A and Group B. The samples were stored in water before experimenting. The test samples were subject to four cycles of microwave sterilization; followed by flexural strength testing with a 3-point flexural test in universal testing machine (UNITEK 94100 and impact strength testing with impact testing machine (ENKAY Pr09/E1/16. Results: The physical properties had significant changes for conventionally cured denture base resins, whereas no changes found for microwave-cured resins after repeated sterilization cycles.

  13. Polymerization shrinkage stress of resin-based dental materials: A systematic review and meta-analyses of technique protocol and photo-activation strategies.

    Science.gov (United States)

    Münchow, Eliseu Aldrighi; Meereis, Carine Tais Welter; de Oliveira da Rosa, Wellington Luiz; da Silva, Adriana Fernandes; Piva, Evandro

    2018-03-08

    A systematic review was conducted to determine whether there were any alternative technique or additional step strategies available to reduce and control polymerization shrinkage stress development in dental resin-based restorative materials. This report followed the PRISMA Statement. A total of 36 studies were included in this review. Two reviewers performed a literature search up to December 2016, without restriction of the year of publication, in seven databases: PubMed, Web of Science, Scopus, SciELO, LILACS, IBECS, and BBO. Only in vitro studies that evaluated polymerization shrinkage stress by direct testing were included. Pilot studies, reviews and in vitro studies that evaluated polymerization shrinkage stress by indirect methods (e.g., microleakage or cuspal deflection measurements), finite elemental analysis or mathematical models were excluded. Of the 6.113 eligible articles, 36 studies were included in the qualitative analysis, and the meta-analysis was performed with 25 studies. A global comparison was performed with random-effects models (α = 0.05). The strategies were subdivided as follows: the use of an alternative technique protocol of placing the material inside the tooth cavity; the modification of the irradiation intensity or total energy delivered to the material; the use of an alternative light-curing source; or the use of an alternative photo-activation mode. All alternative strategies showed statistically significant differences when compared with their respective controls (p material by means of an alternative technique protocol or by modifying the irradiant intensity or total energy delivered to the material during photo-activation. Moreover, the use of an alternative photo-activation mode (intermittent light, exponential, soft-start or pulse delay modes) was shown to be an effective strategy for reducing and controlling stress development in resin-based dental materials. Copyright © 2018 Elsevier Ltd. All rights reserved.

  14. Effect of ceramic material and resin cement systems on the color stability of laminate veneers after accelerated aging.

    Science.gov (United States)

    Lee, Seong-Min; Choi, Yu-Sung

    2018-01-05

    Laminate veneers are susceptible to color change during clinical service. Studies that compare the effects of different ceramic and resin cement systems on color stability are lacking. The purpose of this in vitro study was to evaluate the color stability of laminate veneers after accelerated aging using different ceramic and resin cement systems. Ceramic specimens (N=168; shade A1; thickness, 0.50 ±0.05 mm; diameter, 10.00 ±0.10 mm) were prepared using nanofluorapatite and lithium disilicate (high translucency [HT] to low translucency [LT]) ceramics. Light-polymerizing (LP) cements were classified by brightness (high or low). Dual-polymerizing cements were classified by composition (base-only [DB] or base-catalyst [DC]) for comparison of color stability on the basis of polymerization type. DB cement was light-polymerizing, whereas DC cement was dual-polymerizing. They were further classified by shade (transparent, white, or yellow [n=7, each]). Color difference (ΔE) values were obtained by spectrophotometric quantification of L* (lightness), a* (green-red), and b* (blue-yellow) values before and after aging. The Kruskal-Wallis, Mann-Whitney U, Wilcoxon signed rank, and Bonferroni post hoc tests were used for statistical analysis. After specimens were subjected to accelerated aging, HT ceramic specimens luted with yellow-shade DC cement exhibited the greatest color change (ΔE=2.11), whereas HT and LT ceramic specimens luted with low-brightness LP cement exhibited the least color change (ΔE=1.37). In HT ceramic specimens, which exhibited the greatest color change of the 3 ceramic types, transparent shade cement exhibited significantly lower ΔE values than the other shades with DB (Pceramics. The ΔE values of DB cement were not always lower than those of DC cement. For all specimens, the aging of laminate veneers decreased the L* values and increased the a* and b* values. Ceramic and resin-cement systems affected the color stability of laminate veneers

  15. Die funksie van die skeppingstradisie in die boek Jeremia

    African Journals Online (AJOL)

    gedeeites voor wat sterk ooreenkomste toon met die beskrywings van die skep pingsgebeure in die boek Jeremia. • Volgpns Von Rad (1957:144-146) het daar wel 'n groep bestaan wat belange ge- had liet by die oorlewering van die skeppingstradisies. Dit was waarskynlik die. Sadokitiese priesters wat om twee redes aan ...

  16. Die persoonlikheidsamestelling van die beskeie leerder in die ...

    African Journals Online (AJOL)

    Erna Kinsey

    Die goedaangepaste persoonlikheid vorm die basis van geestes- gesondheid en stel die mens in staat tot selfaktualisering. Selfaktua- lisering, wat volgens Maslow die hoogste vorm van menslike behoef- tes is, dui op die motivering van die mens om tot sy beste moontlike potensiaal te ontwikkel (Santrock, 2000:372; Smith, ...

  17. Evaluation of the color durability of acrylic resin veneer materials after immersion in common beverages at different time intervals: A spectrophotometric study

    Directory of Open Access Journals (Sweden)

    Shivani Kohli

    2015-06-01

    Full Text Available Background: Proper function, esthetics, and cost are the prime factors to be considered while selecting bridge veneering materials. The purpose of the study is to evaluate color durability of acrylic veneer materials after immersion in common beverages at different time intervals. Methods: Spectrophotometer was used for taking color measurements based on the transmission of light through the specimens made of the selected materials which were Tooth moulding powder (DPI and Acrylux (Ruthinium. Thirty specimens of standardized dimensions were prepared from each material. The specimens were divided into three groups of 10 each. One group of each material was immersed in tea (TajMahal and another group of each material in cola (Pepsi as the staining solutions. The remaining group of 10 from each material served as control and was stored in distilled water. Color measurements were obtained pre-immersion, and after 1, 15, and 30 days of immersion. Results: Tooth moulding powder displayed better color durability than Acrylux over the 1 month immersion period in both staining solutions. Tea resulted in more discoloration compared to cola (Pepsi. Conclusion: The difference in the color durability of Acrylux and Tooth moulding powder may be attributed to the differences in the composition of tested resin veneering materials, i.e. their polar properties, which contribute to the absorption of staining solution, and the different brands and the strengths of the solutions.

  18. Investigation of porous graphitic carbon for triterpenoids and natural resinous materials analysis by high performance liquid chromatography hyphenated to mass spectrometry.

    Science.gov (United States)

    Rhourri-Frih, B; Chaimbault, P; Dequeral, D; André, P; Lafosse, M

    2012-06-01

    Natural resinous materials are mainly composed of pentacyclic triterpenes which exhibit a large number of interesting medicinal activities. However, the presence of numerous isomers within the active substances makes their screening by HPLC very challenging. Porous graphitic carbon was investigated as stationary phase to achieve triterpenes isomers separation. The influence of various parameters (temperature, formic acid concentration and mobile phase composition) on the retention was considered. A usual decrease of the retention of triterpenes was observed with the increase of the temperature. Therefore, separation in resinous materials was performed at 25°C. Acetonitrile-isopropanol mixture was chosen as mobile phase in gradient elution and leads to the best compromise between efficiency and high resolution. The lack of chromophore groups in the pentacyclic triterpenes structures required the use of mass spectrometry detection. Moreover, atmospheric pressure photo-ionisation mass spectrometry prevents compounds fragmentation which was helpful for spectra interpretation and compounds identification. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Die regsposisie van die gemolesteerde kind 1

    Directory of Open Access Journals (Sweden)

    P.J. Schabort

    1991-03-01

    Full Text Available Hoe reik die reg uit na die seksueel gemolesteerde kind? As na die reg in wye verband gekyk word, sou dit alie wetgewing en alle gemeneregsbeginsels en alle regsprosedures insluit waardeur die Staat poog om molestering te voorkom en die gemolesteerde kind in beskerming te neem. Dit le baie wyd en sou byvoorbeeld die maatreels insluit van die Kindenvet 33 van 1960; die Wet op Egskeiding 70 van 1979; die Wet op Kindersorg 74 van 1983; die Wet op die Status van Kinders 82 van 1987 en die Wet op Bemiddeling in Sekere Egskeidingsaangeleenthede 24 van 1987. Eersdaags sal dit moontlik ook ’n Manifes vir die Regte van Kinders insluit wat vermoedelik geskoei sal wees op die W O se Konvensie vir die Regte van die Kind (1989 w a arv an die RSA tan s nog nie ’n ondertekenaar is nie.

  20. Potentiometric Sensors for Pr(III Based on N-N᾽o-Phenylene-bis(salicylideneimine Using Epoxy Resin and PVC as Binding Materials

    Directory of Open Access Journals (Sweden)

    K. Sharma Harish

    2011-01-01

    Full Text Available Praseodymium(III ion selective electrodes have been prepared using N-N᾽o-phenylene-bis(salicylideneimine as a suitable electro-active material. Several membranes comprising of varying compositions of electro-active material with epoxy resin and polyvinylchloride (PVC as binding materials were prepared. However the one with composition 50% Schiff᾽s base and 50% binder was found to exhibit best performance. The sensor with epoxy resin as binder presents a linear dynamic range of 1.0×10-6 to 1.0×10-1 M with a Nernstian slope of 19.9 mV/decade. The sensor has a quick response time. (less than 10 s. The reproducibility of the electrode is about 6 months without any considerable, noticeable potential divergence. The sensor is effective in pH range of 3.00-8.62. In case of PVC as binding material; the results are compared for same composition of electro-active material. The sensor presents a linear dynamic range of 1.0×10-6 to 1.0×10-1 M with a slope of 14.0 mV/decade. The response time of the sensor is found to be 20s with a reproducibility of 4 months. The sensor is effective in pH range of 2.97-8.90. Effect of internal solution was studied and both the electrodes could satisfactorily be used in partially non-aqueous medium. Selectivity coefficients for both the electrodes have been determined by FIM (fixed interference method with respect to many rare earth metal ions, alkali & alkaline earth metal ions and some transition metal ions. Both the electrodes were successfully employed as indicator electrode in the potentiometric titration of Pr(III ions with oxalic acid and EDTA.

  1. Influence of different surface treatments on the short-term bond strength and durability between a zirconia post and a composite resin core material.

    Science.gov (United States)

    Akgungor, Gokhan; Sen, Deniz; Aydin, Murat

    2008-05-01

    Reliable bonding between zirconia posts and composite resin core materials is difficult to achieve because of the smooth surface texture and lack of silica content of zirconia posts. The purpose of this study was to evaluate the effect of different surface treatments on the short-term bond strength and durability between a zirconia post and a composite resin core material. Eighty zirconia posts were divided into 4 groups (n=20). Specimens received 1 of 4 different surface treatments: group AIRB, airborne-particle abrasion; group TSC-SIL, tribochemical silica coating (CoJet system) and silanization (ESPE Sil); group AIRB-BSIL, airborne-particle abrasion and MDP-containing primer (Clearfil SE Bond Primer)/silane coupling agent (Clearfil Porcelain Bond Activator) mixture application; and group TSC-BSIL, tribochemical silica coating and MDP-containing primer/silane coupling agent mixture application. Average surface roughness (Ra) of zirconia posts produced by airborne-particle abrasion or silica coating was measured using an optical profilometer. Composite resin core foundations (Build-it FR) were formed using transparent acrylic resin tubes (12mm in length and 7mm in diameter). Each group was further divided into 2 subgroups of 10 specimens and stored in distilled water at 37 degrees C, either for 24 hours or for 150 days with 37,500 thermal cycles between 5 degrees C and 55 degrees C, with a dwell time of 30 seconds. Following water storage, the specimens were sectioned perpendicular to the bonded interface into 2-mm-thick post-and-core specimens under water cooling. Push-out tests were performed with a universal testing machine at a crosshead speed of 0.5mm/min. Debonded post surfaces were examined with SEM. Data were analyzed with 1- and 2-way ANOVA and Tukey multiple comparison tests (alpha=0.05). No significant differences were detected between the Ra values of airborne-particle-abraded and silica-coated specimens (P=.781). The short-term mean bond strengths for

  2. Application of resin lining system for countermeasures for preventing leakage from openings in low temperature materials storage; Teion busshitsu chozoji no ekimore oyobi reiki more taisaku toshite no kobunshikei zairyo no tekiyosei

    Energy Technology Data Exchange (ETDEWEB)

    Inada, Y. [Ehime Univ., Ehime (Japan). Faculty of Engineering; Seki, S.

    1996-12-21

    Recently, many of the low temperature materials such as LNG and LPG used as an energy substitution for petroleum were stored in the reclaimed land of the sea side district, however, it is necessary for those storage methods to enlarge sites. Therefore, it was considered to directly store the low temperature materials in openings excavated in the rock mountains. However, countermeasures for leakage of liquid and cold gas from cracks in openings would be an important subject. In this study, as a countermeasure for leakage of liquid and cold gas in the case in which low temperature materials were stored in openings in the rock mountains, the lining of resin materials on the surface of openings was proposed. Characteristics of strength and deformation and values of the thermal physical properties for the resin materials at the low temperature were obtained by experiments. This material was compared with granite supposed as a parent rock, and the thermal property of the resin materials was understood. Next, an analysis was conducted in the case of using the resin materials as a lining, the behavior of the surrounding rocks of the openings and the stability of the lining were investigated. 17 refs., 25 figs., 2 tabs.

  3. Color management of porcelain veneers: influence of dentin and resin cement colors.

    Science.gov (United States)

    Dozic, Alma; Tsagkari, Maria; Khashayar, Ghazal; Aboushelib, Moustafa

    2010-01-01

    Porcelain veneers have become an interesting treatment option to correct the shape and color of anterior teeth. Because of their limited thickness and high translucency, achieving a good color match is influenced by several variables. The aim of this work was to investigate the influence of natural dentin and resin cement colors on final color match of porcelain veneers. A preselected shade tab (A1) was chosen as the target color for a maxillary central incisor, and its color parameters (L*a*b*) were measured using a digital spectrophotometer (SpectroShade, MHT). Nine natural dentin colors (Natural Die Material, Ivoclar Vivadent) representing a wide range of tooth colors were used to prepare resin replicas of the maxillary central incisor with a standard preparation for porcelain veneers. The prepared porcelain veneers (IPS Empress Esthetic, A1, 0.6 mm thick, Ivoclar Vivadent) were cemented on the resin dies (nine groups of natural dentin colors) using seven shades of resin cement (Variolink Veneers, Ivoclar Vivadent). The L*a*b* values of the cemented veneers were measured, and DE values were calculated against the preselected target color (A1). DE greater than 3.3 was considered as a significant color mismatch detectable by the human eye. The seven shades of resin cement had no significant influence on the final color of the veneers, as the measured DE values were almost identical for every test group. On the other hand, the color of natural dentin was a significant factor that influenced final color match. None of the 63 tested combinations (nine natural dentin colors and seven resin cement colors) produced an acceptable color match. Thin porcelain veneers cannot mask underlying tooth color even when different shades of resin cement are used. Incorporation of opaque porcelain (high chroma) may improve final color match.

  4. Influence of 2% chlorhexidine on pH, calcium release and setting time of a resinous MTA-based root-end filling material.

    Science.gov (United States)

    Jacinto, Rogério Castilho; Linhares-Farina, Giane; Sposito, Otávio da Silva; Zanchi, César Henrique; Cenci, Maximiliano Sérgio

    2015-01-01

    The addition of chlorhexidine (CHX) to a resinous experimental Mineral Trioxide Aggregate (E-MTA) based root-end filling material is an alternative to boost its antimicrobial activity. However, the influence of chlorhexidine on the properties of this material is unclear. The aim of this study was to evaluate the influence of 2% chlorhexidine on the pH, calcium ion release and setting time of a Bisphenol A Ethoxylate Dimethacrylate/Mineral Trioxide Aggregate (Bis-EMA/MTA) based dual-cure experimental root-end filling material (E-MTA), in comparison with E-MTA without the addition of CHX and with conventional white MTA (W-MTA). The materials were placed in polyethylene tubes, and immersed in deionized water to determine pH (digital pH meter) and calcium ion release (atomic absorption spectrometry technique). The setting time of each material was analyzed using Gilmore needles. The data were statistically analyzed at a significance level of 5%. E-MTA + CHX showed an alkaline pH in the 3 h period of evaluation, the alkalinity of which decreased but remained as such for 15 days. The pH of E-MTA + CHX was higher than the other two materials after 7 days, and lower after 30 days (p pH and calcium ion release. However, it also prevented setting of the material.

  5. Die toksikologiese telefoniese konsultasies gerig aan die ...

    African Journals Online (AJOL)

    Die toksikologiese telefoniese konsultasies gerig aan die Departement Farmakologie van die Universiteit van die Vrystaat gedurende 1998/ The toxicology telephonic consultations directed to the department of pharmacology of the University of the Free State during 1998.

  6. Analysis of resin-dentin interface morphology and bond strength evaluation of core materials for one stage post-endodontic restorations.

    Directory of Open Access Journals (Sweden)

    Kerstin Bitter

    Full Text Available PURPOSE: Restoration of endodontically treated teeth using fiber posts in a one-stage procedure gains more popularity and aims to create a secondary monoblock. Data of detailed analyses of so called "post-and-core-systems" with respect to morphological characteristics of the resin-dentin interface in combination with bond strength measurements of fiber posts luted with these materials are scarce. The present study aimed to analyze four different post-and-core-systems with two different adhesive approaches (self-etch and etch-and-rinse. MATERIALS AND METHODS: Human anterior teeth (n = 80 were endodontically treated and post space preparations and post placement were performed using the following systems: Rebilda Post/Rebilda DC/Futurabond DC (Voco (RB, Luxapost/Luxacore Z/Luxabond Prebond and Luxabond A+B (DMG (LC, X Post/Core X Flow/XP Bond and Self Cure Activator (Dentsply DeTrey (CX, FRC Postec/MultiCore Flow/AdheSE DC (Ivoclar Vivadent (MC. Adhesive systems and core materials of 10 specimens per group were labeled using fluorescent dyes and resin-dentin interfaces were analyzed using Confocal Laser Scanning Microscopy (CLSM. Bond strengths were evaluated using a push-out test. Data were analyzed using repeated measurement ANOVA and following post-hoc test. RESULTS: CLSM analyses revealed significant differences between groups with respect to the factors hybrid layer thickness (p<0.0005 and number of resin tags (p = 0.02; ANOVA. Bond strength was significantly affected by core material (p = 0.001, location inside the root canal (p<0.0005 and incorporation of fluorescent dyes (p = 0.036; ANOVA. CX [7.7 (4.4 MPa] demonstrated significantly lower bond strength compared to LC [14.2 (8.7 MPa] and RB [13.3 (3.7 MPa] (p<0.05; Tukey HSD but did not differ significantly from MC [11.5 (3.5 MPa]. CONCLUSION: It can be concluded that bond strengths inside the root canal were not affected by the adhesive approach of the post-and-core-system. All systems

  7. Tensile and shear bond strength of hard and soft denture relining materials to the conventional heat cured acrylic denture base resin: An In-vitro study.

    Science.gov (United States)

    Lau, Mayank; Amarnath, G S; Muddugangadhar, B C; Swetha, M U; Das, Kopal Anshuraj Ashok Kumar

    2014-04-01

    The condition of the denture bearing tissues may be adversely affected by high stress concentration during function. Chairside Denture (Hard and Soft) reliners are used to distribute forces applied to soft tissues during function. Tensile and shear bond strength has been shown to be dependent on their chemical composition. A weak bond could harbor bacteria, promote staining and delamination of the lining material. To investigate tensile and shear bond strength of 4 different commercially available denture relining materials to conventional heat cured acrylic denture base resin. 4 mm sections in the middle of 160 Acrylic cylindrical specimens (20 mm x 8 mm) were removed, packed with test materials (Mollosil, G C Reline Soft, G C Reline Hard (Kooliner) and Ufi Gel Hard and polymerized. Specimens were divided into 8 groups of 20 each. Tensile and shear bond strength to the conventional heat cured acrylic denture base resin were examined by Instron Universal Tensile Testing Machine using the equation F=N/A (F-maximum force exerted on the specimen (Newton) and A-bonding area= 50.24 mm2). One-way ANOVA was used for multiple group comparisons followed by Bonferroni Test and Hsu's MCB for multiple pairwise comparisons to asses any significant differences between the groups. The highest mean Tensile bond strength value was obtained for Ufi Gel Hard (6.49+0.08 MPa) and lowest for G C Reline Soft (0.52+0.01 MPa). The highest mean Shear bond strength value was obtained for Ufi Gel Hard (16.19+0.1 MPa) and lowest for Mollosil (0.59+0.05 MPa). The Benferroni test showed a significant difference in the mean tensile bond strength and the mean shear bond strength when the two denture soft liners were compared as well as when the two denture hard liners were compared. Hsu's MCB implied that Ufi gel hard is better than its other closest competitors. The Tensile and Shear bond strength values of denture soft reliners were significantly lower than denture hard reliners. How to cite the

  8. Thermal Response and Stability Characteristics of Bistable Composite Laminates by Considering Temperature Dependent Material Properties and Resin Layers

    Science.gov (United States)

    Moore, M.; Ziaei-Rad, S.; Salehi, H.

    2013-02-01

    In this study, the stability characteristics and thermal response of a bistable composite plate with different asymmetric composition were considered. The non-linear finite element method (FEM) was utilized to determine the response of the laminate. Attention was focused on the temperature dependency of laminate mechanical properties, especially on the thermal expansion coefficients of the composite graphite-epoxy plate. Also the effect of including the resin layers on the stability characteristics of the laminate was investigated. The effect of the temperature on the laminate cured configurations in the range of 25°C to 180°C and -60°C to 40°C was examined. The results indicate that the coefficient of thermal expansions has a major effect on the cured shapes. Next, optical microscopy was used to characterize the laminate composition and for the first time the effect of including the resin layers on the actuation loads that causes snapping behavior between two stable shapes was studied. The results obtained from the finite element simulations were compared with experimental results and a good correlation was obtained. Finally, the stability characteristics of a tapered composite panel were investigated for using in a sample winglet as a candidate application of bistable structures.

  9. Die moedertaal van Jesus*

    Directory of Open Access Journals (Sweden)

    S.J. du Plessis

    1963-03-01

    Full Text Available Anderhalf eeu lank het geleerdes aangeneem dat die enigste taal wat deur die bree volkslae in Palestina gepraat is in die tyd van Jesus, Aramees was. In 1817 het De Wette onder andere geskrywe: „Die benaming Hebreeus kom vir die eerste keer in die Apokriewe Boeke voor. Maar daar beteken dit die heersende volkstaal Aramees, wat teen daardie tyd (die tyd toe die Apokriewe ontstaan het reeds die plek van die ou Hebreeus ingeneem het”.

  10. Die redaksionele geskiedenis van die boek Hosea

    African Journals Online (AJOL)

    tuur kom rá' gewoonlik voor as antoniem van sdq. Op grond van die voorafgaande kan die hipotese gestel word dat die redaktor uit die wysheidskringe wat die profesieë van Hosea van 'n inleiding en slot voorsien het, dit nie as los aanhangsels gedoen het nie, maar dat dit bedoel was as integrale deel van die boek.

  11. DIE ONTSTAAN EN ONTWIKKELING VAN DIE VLOOT

    African Journals Online (AJOL)

    1 Feb 1980 ... ter See (See- ward Defence Force - SDF) as die eerste per- manente vlooteenheid in Suid-Afrika in te stel. Die SDF is op 15 Januarie. 1940 formeel gekonstitueer. Die lede van die SANS is outoma- ties daarna oorgeplaas, maar die RNVR (SA) het onafhanklik bly voortfunksioneer. Die SDF het aanvanklik.

  12. Evalueringskriteria en die interaksie tussen die leksikografieteorie ...

    African Journals Online (AJOL)

    user

    Opsomming: Die samestellers van die verskillende dele van die WAT kon steun op die insette van verskeie medewerkers, waarvan woordeboekresensente 'n belangrike groep is. Een van die algemene probleme met die evaluering van woordeboeke van allerlei soorte (sien Nielsen 2006,. 2009 en Swanepoel 2008, 2013 ...

  13. Plastic casting resin poisoning

    Science.gov (United States)

    Epoxy poisoning; Resin poisoning ... Epoxy and resin can be poisonous if they are swallowed or their fumes are breathed in. ... Plastic casting resins are found in various plastic casting resin products.

  14. Influence of different luting protocols on shear bond strength of computer aided design/computer aided manufacturing resin nanoceramic material to dentin

    Directory of Open Access Journals (Sweden)

    Claudio Poggio

    2016-01-01

    Conclusion: Within the limitations of this in vitro study, conventional resin cements (coupled with etch and rinse or self-etch adhesives showed better shear strength values compared to self-adhesive resin cements. Furthermore, conventional resin cements used together with a self-etch adhesive reported the highest values of adhesion.

  15. Recycling of plastic group composite materials. 3. ; Current situation in recycling of thermosetting resin composite materials in Japan, Europe and America. Plastic ki fukugo zairyo no recycle. 3. ; Netsukokasei jushi fukugo zairyo no recycle no Nichiobei no genjo

    Energy Technology Data Exchange (ETDEWEB)

    Iimori, H. (Mitsui Toatsu Chemicals, Inc., Tokyo (Japan))

    1993-07-15

    This paper describes the current situation in Japan, Europe and America on recycling of thermosetting resin composite materials, and material treatment and resource re-utilization with emphasis on FRP. Land reclamation would become impossible eventually as a result of difficulty in land procurement, soil contamination, and residents' objection. Pulverization consists of a flow comprising disassembling, cutting, crushing, pulverization, and classification. Pyrolysis heats materials in steam, oxygen-free or low-oxygen atmosphere to recover combustible gases, oils, and resin material solids. Incineration requires incinerator designs that take into account incinerator damages due to black smoke and molten glassfibers. Japan, Europe, and America which have common environmental and legislative regulation issues have begun researches simultaneously. Europe has advanced with pulverization systems in reaching practical use levels, and North America has been using the systems practically. The pyrolytic means are in a feasibility study phase. The issue of the car scrapping law in Germany is inevitable to become a common problem for the EC countries. The automobile industries in North America have been working on technical development under joint investments. Treatment technologies in Japan have nearly reached the levels in Europe and America. Responses to structural change requirements from consumption type to environmental protection type are required. 14 refs., 8 figs., 7 tabs.

  16. . , , die Boesmans

    African Journals Online (AJOL)

    "made captive in early boyhood, with other children of a Bushman. Kraal, in one of the frequent incursions or commandos" (Pereira &. Chapman, 1989:157). Dit eindig met Pangóla wat sterf in 'n soortgelyke ongelyke geveg tussen berede boere en omsingelde Boesmans - gewere teen pyl-en-boë: "I die in arms against the ...

  17. Resin composites

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Peutzfeldt, Anne; Lussi, Adrian

    2014-01-01

    OBJECTIVE: To investigate how the modulus of elasticity of resin composites influences marginal quality in restorations submitted to thermocyclic and mechanical loading. METHODS: Charisma, Filtek Supreme XTE and Grandio were selected as they were found to possess different moduli of elasticity...... of resin composite (p=0.81) on the quality of dentine margins was observed, before or after loading. Deterioration of all margins was evident after loading (p....008). CONCLUSIONS: The resin composite with the highest modulus of elasticity resulted in the highest number of gap-free enamel margins but with an increased incidence of paramarginal enamel fractures. CLINICAL SIGNIFICANCE: The results from this study suggest that the marginal quality of restorations can...

  18. The effects of silane-SiO2 nanocomposite films on Candida albicans adhesion and the surface and physical properties of acrylic resin denture base material.

    Science.gov (United States)

    Yodmongkol, Sirasa; Chantarachindawong, Rojcharin; Thaweboon, Sroisiri; Thaweboon, Boonyanit; Amornsakchai, Taweechai; Srikhirin, Toemsak

    2014-12-01

    Polysiloxane has been used as a coupling material in restorative dental materials for several decades. However, few studies are available on the application of polysiloxane in other dental prosthesis functions. The purpose of this study was to investigate the effects of silane-SiO2 nanocomposite films on Candida albicans adhesion and the surface and physical properties of acrylic resin denture base materials. Specimens were separated into 2 groups, uncoated and coated. They were coated with a film by using the dip-coating method. Specimens were incubated with Candida albicans 10(7) cells/mL for 1 hour, and the adherent cells were counted under an optical microscope. The following surface properties were measured: surface chemical composition with Fourier-transform infrared spectrometry, surface roughness with a surface profiler, surface energy with the sessile drop method, and surface hardness with a microhardness tester. The physical properties, including water sorption, water solubility, ultimate flexural strength, and flexural modulus, were evaluated according to International Organization for Standardization 20795-1 requirements. The adhesion of Candida albicans and the surface properties of the specimens were investigated after cleaning with effervescent tablets and brushing. An MTT assay was used to evaluate the coated specimens. The results were statistically analyzed with the Mann-Whitney U test (α=.05). A significant reduction in Candida albicans adhesion (P=.002) was observed before cleaning. In addition, the surface energy was comparable (P=.100), the surface hardness increased significantly (P=.008), and the surface roughness remained unchanged (P=.310). After cleaning with effervescent tablets, a significant decrease in Candida albicans adhesion (P=.002) and in surface roughness (P=.008) was observed; however, similar surface energies were measured (P=.100). After cleaning with a toothbrush, the adhesion of Candida albicans was significantly higher on

  19. Die woord vra kontak

    African Journals Online (AJOL)

    dit belangrik dat die redaksionele stelsel en die taalkundige gegewens wat in woordeboeke gehanteer word, in pas moet wees met die heersende gedag- terigtings in die taalkunde. Dit kan die maklikste bewerkstelling word indien die oop gesprek tussen die leksikograaf en die taalkundige voortdurend gesti- muleer word.

  20. Influence of 2% chlorhexidine on pH, calcium release and setting time of a resinous MTA-based root-end filling material

    Directory of Open Access Journals (Sweden)

    Rogério Castilho JACINTO

    2015-01-01

    Full Text Available The addition of chlorhexidine (CHX to a resinous experimental Mineral Trioxide Aggregate (E-MTA based root-end filling material is an alternative to boost its antimicrobial activity. However, the influence of chlorhexidine on the properties of this material is unclear. The aim of this study was to evaluate the influence of 2% chlorhexidine on the pH, calcium ion release and setting time of a Bisphenol A Ethoxylate Dimethacrylate/Mineral Trioxide Aggregate (Bis-EMA/MTA based dual-cure experimental root-end filling material (E-MTA, in comparison with E-MTA without the addition of CHX and with conventional white MTA (W-MTA. The materials were placed in polyethylene tubes, and immersed in deionized water to determine pH (digital pH meter and calcium ion release (atomic absorption spectrometry technique. The setting time of each material was analyzed using Gilmore needles. The data were statistically analyzed at a significance level of 5%. E-MTA + CHX showed an alkaline pH in the 3 h period of evaluation, the alkalinity of which decreased but remained as such for 15 days. The pH of E-MTA + CHX was higher than the other two materials after 7 days, and lower after 30 days (p < 0.05. All of the materials were found to release calcium ions throughout the 30 days of the study. The addition of CHX increased the calcium ion release of E-MTA to levels statistically similar to W-MTA. E-MTA showed shorter initial and final setting time, compared with W-MTA (p < 0.05. The addition of 2% CHX to MTA prevented setting of the material. The addition of CHX to E-MTA increased its pH and calcium ion release. However, it also prevented setting of the material.

  1. Opportunities offered by the raw material boom to German mining machinery manufacturers; Chancen des Rohstoffbooms fuer die deutschen Bergbaumaschinenhersteller

    Energy Technology Data Exchange (ETDEWEB)

    Stoeckmann, K. [Verband Deutscher Maschinen- und Anlagenbau e.V. (VDMA), Frankfurt am Main (Germany). Fachverband Bergbaumaschinen

    2008-05-13

    Since the beginning of the raw material boom four years ago the positive trend in the mining machinery branch in Germany has accelerated. The globalisation of the branch was assisted by the good national and international network between manufacturers of mining equipment, associations, consultants, financial institutions and politicians. The branch is currently well established internationally with an export share of 86%. This puts it into a position to continue to utilise the opportunities offered by the raw material boom. (orig.)

  2. Modeling the Residual Stresses in Reactive Resins-Based Materials: a Case Study of Photo-Sensitive Composites for Dental Applications

    Science.gov (United States)

    Grassia, Luigi; D'Amore, Alberto

    2010-06-01

    Residual stresses in reactive resins-based composites are associated to the net volumetric contraction (shrinkage) arising during the cross-linking reactions. Depending on the restoration geometry (the ratio of the free surface area to the volume of the cavity) the frozen-in stresses can be as high as the strength of the dental composites. This is the main reason why the effectiveness and then the durability of restorations with composites remains quite lower than those realized with metal alloys based materials. In this paper we first explore the possibility to circumvent the mathematical complexity arising from the determination of residual stresses in reactive systems three-dimensionally constrained. Then, the results of our modeling approach are applied to a series of commercially available composites showing that almost all samples develop residual stresses such that the restoration undergoes failure as soon as it is realized.

  3. Modeling the Residual Stresses in Reactive Resins-Based Materials: a Case Study of Photo-Sensitive Composites for Dental Applications

    International Nuclear Information System (INIS)

    Grassia, Luigi; D'Amore, Alberto

    2010-01-01

    Residual stresses in reactive resins-based composites are associated to the net volumetric contraction (shrinkage) arising during the cross-linking reactions. Depending on the restoration geometry (the ratio of the free surface area to the volume of the cavity) the frozen-in stresses can be as high as the strength of the dental composites. This is the main reason why the effectiveness and then the durability of restorations with composites remains quite lower than those realized with metal alloys based materials. In this paper we first explore the possibility to circumvent the mathematical complexity arising from the determination of residual stresses in reactive systems three-dimensionally constrained. Then, the results of our modeling approach are applied to a series of commercially available composites showing that almost all samples develop residual stresses such that the restoration undergoes failure as soon as it is realized.

  4. Evaluation of the bond strength of different adhesive agents to a resin-modified calcium silicate material (TheraCal LC).

    Science.gov (United States)

    Karadas, Muhammed; Cantekin, Kenan; Gumus, Husniye; Ateş, Sabit Melih; Duymuş, Zeynep Yesil

    2016-09-01

    This study evaluated the bond strength of different adhesive agents to TheraCal LC and mineral trioxide aggregate (MTA) and examined the morphologic changes of these materials with different surface treatments. A total of 120 specimens, 60 of MTA Angelus (AMTA), and 60 of TheraCal LC, were prepared and divided into six subgroups according to the adhesive agent used; these agents included Scotchbond Multipurpose, Clearfil SE Bond, Clearfil Protect Bond, Clearfil S 3 Bond, OptiBond All-in-One, and G-aenial Bond. After application of adhesive agents, Filtek Z250 composite resin was placed onto the specimens. Shear bond strengths were measured using a universal testing machine, followed by examination of the fractured surfaces. The surface changes of the specimens were observed using scanning electron microscopy. Data were compared by two-way analysis of variance. Although no significant differences were found among the bond strengths of different adhesives to AMTA (p = 0.69), a significant difference was found in terms of bond strengths of different adhesives to the TheraCal LC surface (p TheraCal LC compared to the bond with other adhesives. TheraCal LC bonded significantly more strongly than AMTA regardless of the adhesive agents tested. Resin-modified calcium silicate showed higher bond strength than AMTA in terms of the composite bond to these materials with different bonding systems. On the other hand, the highest shear bond-strength values were found for composite bonds with the combination of TheraCal LC and the total-etch adhesive system. SCANNING 38:403-411, 2016. © 2015 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

  5. Surface hardness evaluation of different composite resin materials: influence of sports and energy drinks immersion after a short-term period.

    Science.gov (United States)

    Erdemir, Ugur; Yildiz, Esra; Eren, Meltem Mert; Ozel, Sevda

    2013-01-01

    This study evaluated the effect of sports and energy drinks on the surface hardness of different composite resin restorative materials over a 1-month period. A total of 168 specimens: Compoglass F, Filtek Z250, Filtek Supreme, and Premise were prepared using a customized cylindrical metal mould and they were divided into six groups (N=42; n=7 per group). For the control groups, the specimens were stored in distilled water for 24 hours at 37°C and the water was renewed daily. For the experimental groups, the specimens were immersed in 5 mL of one of the following test solutions: Powerade, Gatorade, X-IR, Burn, and Red Bull, for two minutes daily for up to a 1-month test period and all the solutions were refreshed daily. Surface hardness was measured using a Vickers hardness measuring instrument at baseline, after 1-week and 1-month. Data were statistically analyzed using Multivariate repeated measure ANOVA and Bonferroni's multiple comparison tests (α=0.05). Multivariate repeated measures ANOVA revealed that there were statistically significant differences in the hardness of the restorative materials in different immersion times (psports and energy drinks after a 1-month evaluation period (psports and energy drinks on the surface hardness of a restorative material depends on the duration of exposure time, and the composition of the material.

  6. Bulk-Fill Resin Composites

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Havndrup-Pedersen, Cæcilie; Honoré, Daniel

    2015-01-01

    the restorative procedure. The aim of this study, therefore, was to compare the depth of cure, polymerization contraction, and gap formation in bulk-fill resin composites with those of a conventional resin composite. To achieve this, the depth of cure was assessed in accordance with the International Organization...... for Standardization 4049 standard, and the polymerization contraction was determined using the bonded-disc method. The gap formation was measured at the dentin margin of Class II cavities. Five bulk-fill resin composites were investigated: two high-viscosity (Tetric EvoCeram Bulk Fill, SonicFill) and three low......-viscosity (x-tra base, Venus Bulk Fill, SDR) materials. Compared with the conventional resin composite, the high-viscosity bulk-fill materials exhibited only a small increase (but significant for Tetric EvoCeram Bulk Fill) in depth of cure and polymerization contraction, whereas the low-viscosity bulk...

  7. Die doop in die Gereformeerde Kerkorde

    Directory of Open Access Journals (Sweden)

    C. J. Smit

    1989-05-01

    Full Text Available Dit is veelseggend dat die klassiek geworde Gereformeerde Doopformulier aan ’n kerkorde ontleen is. Hierdie kerkorde is die van die Palts wat in opdrag van die keurvors Frederik die Vrome opgestel en in 1563 ingevoer is.

  8. DIE ONTWIKKELING VAN DIE VROU AS SOLDAAT

    African Journals Online (AJOL)

    Foto: 'Women in Battle' deur John. Laffin. Die Enge/se vrou was spoedig reeds by die verdediging van haar land betrokke. So vroeg as. 1761 het die Jaarlikse Register aangetoon dat. Engelse vroue wat hulle mans op die slagveld gevolg het deur 'n uniform aan te trek, uitgevind is.5. Die. Amerikaanse. Vryheidsoorlog.

  9. Die universiteit en die goeie lewensorde

    African Journals Online (AJOL)

    op Hippocrates, Galenus en Avicenna, lettere op Aristoteles, en ná die. Reformasie sou Luther, Melanchton en Calvyn vir Petrus Lombardus aan dié universiteite vervang wat vir die Reformasie gekies het, maar sou die ander fakulteite in hoofsaak onaangeraak bly. Die universiteit het sy tradisie binne die voile stroom van ...

  10. Evaluation of permanent die coatings to improve the wear resistance of die casting dies. Final project report, January 1, 1995--April 30, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Shivpuri, R.

    1997-09-18

    Die Casting dies are subject to severe service conditions during the die casting operation. While these severe conditions are necessary to achieve high production rates, they cause the dies which are commonly made of H13 die steel, to suffer frequent failures. The major die failure mechanisms are erosion or washout, Heat checking, soldering and corrosion. Due to their geometrical complexity, die casting dies are very expensive (some dies cost over a million dollars), and thus a large number of parts have to be produced by a die, to justify this cost and leverage the advantages of the die casting process (high production rates, low manpower costs). A potential increase in the die service life, thus has a significant impact on the economics of the die; casting operation. There are many ways to extend die life: developing new wear resistant die materials, developing new surface treatments including coatings, improving heat treatment of existing H13 dies, using better lubricants that can protect the die material, or modifying the die geometry and process parameters to reduce the intensity of wear. Of these the use of coatings to improve the wear resistance of the die surface has shown a lot of promise. Consequently, use of coatings in the die casting industry and their wide use to decrease die wear can improve significantly the productivity of shop operations resulting in large savings in material and energy usage.

  11. A comprehensive study of soft magnetic materials based on FeSi spheres and polymeric resin modified by silica nanorods

    Czech Academy of Sciences Publication Activity Database

    Strečková, M.; Füzer, J.; Kobera, Libor; Brus, Jiří; Fáberová, M.; Bureš, R.; Kollár, P.; Lauda, M.; Medvecký, L.; Girman, V.; Hadraba, Hynek; Baťková, M.; Baťko, I.

    2014-01-01

    Roč. 147, č. 3 (2014), s. 649-660 ISSN 0254-0584 Institutional support: RVO:61389013 ; RVO:68081723 Keywords : composite materials * magnetic materials * chemical synthesis Subject RIV: CD - Macromolecular Chemistry; JH - Ceramics, Fire-Resistant Materials and Glass (UFM-A) Impact factor: 2.259, year: 2014

  12. Nanosilica Modification of Elastomer-Modified VARTM Epoxy Resins for Improved Resin and Composite Toughness

    National Research Council Canada - National Science Library

    Robinette, Jason; Bujanda, Andres; DeSchepper, Daniel; Dibelka, Jessica; Costanzo, Philip; Jensen, Robert; McKnight, Steven

    2007-01-01

    Recent publications have reported a synergy between rubber and silica in modified epoxy resins that results in significantly improved fracture toughness without reductions in other material properties...

  13. Numerical optimization of die geometry in open die forging

    DEFF Research Database (Denmark)

    Christiansen, Peter; Hattel, Jesper Henri; Bay, Niels

    2013-01-01

    This paper deals with numerical optimization of open die forging of large metallic ingots made by casting implying risk of defects, e.g. central pores. Different material hardening properties and die geometries are combined in order to investigate, which geometry gives rise to maximum closure...... of a centreline hole in a single compression operation. Friction is also taken into account. The numerical analysis indicates that a lower die angle of approximately 140o results in the largest centreline hole closure for a wide range of material hardening. The value of optimum die angle is not influenced...... by friction, which was found only to change the degree of centreline porosity closure in case of small lower die angle....

  14. A novel and facile strategy for highly flame retardant polymer foam composite materials: Transforming silicone resin coating into silica self-extinguishing layer.

    Science.gov (United States)

    Wu, Qian; Zhang, Qian; Zhao, Li; Li, Shi-Neng; Wu, Lian-Bin; Jiang, Jian-Xiong; Tang, Long-Cheng

    2017-08-15

    In this study, a novel strategy was developed to fabricate highly flame retardant polymer foam composite materials coated by synthesized silicone resin (SiR) polymer via a facile dip-coating processing. Applying the SiR polymer coating, the mechanical property and thermal stability of SiR-coated polymer foam (PSiR) composites are greatly enhanced without significantly altering their structure and morphology. The minimum oxygen concentration to support the combustion of foam materials is greatly increased, i.e. from LOI 14.6% for pure foam to LOI 26-29% for the PSiR composites studied. Especially, adjusting pendant group to SiOSi group ratio (R/Si ratio) of SiRs produces highly flame retardant PSiR composites with low smoke toxicity. Cone calorimetry results demonstrate that 44-68% reduction in the peak heat release rate for the PSiR composites containing different R/Si ratios over pure foam is achieved by the presence of appropriate SiR coating. Digital and SEM images of post-burn chars indicate that the SiR polymer coating can be transformed into silica self-extinguishing porous layer as effective inorganic barrier effect, thus preserving the polymer foam structure from fire. Our results show that the SiR dip-coating technique is a promising strategy for producing flame retardant polymer foam composite materials with improved mechanical properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Surface hardness evaluation of different composite resin materials: influence of sports and energy drinks immersion after a short-term period

    Science.gov (United States)

    ERDEMİR, Ugur; YİLDİZ, Esra; EREN, Meltem Mert; OZEL, Sevda

    2013-01-01

    Objectives: This study evaluated the effect of sports and energy drinks on the surface hardness of different composite resin restorative materials over a 1-month period. Material and Methods: A total of 168 specimens: Compoglass F, Filtek Z250, Filtek Supreme, and Premise were prepared using a customized cylindrical metal mould and they were divided into six groups (N=42; n=7 per group). For the control groups, the specimens were stored in distilled water for 24 hours at 37º C and the water was renewed daily. For the experimental groups, the specimens were immersed in 5 mL of one of the following test solutions: Powerade, Gatorade, X-IR, Burn, and Red Bull, for two minutes daily for up to a 1-month test period and all the solutions were refreshed daily. Surface hardness was measured using a Vickers hardness measuring instrument at baseline, after 1-week and 1-month. Data were statistically analyzed using Multivariate repeated measure ANOVA and Bonferroni's multiple comparison tests (α=0.05). Results: Multivariate repeated measures ANOVA revealed that there were statistically significant differences in the hardness of the restorative materials in different immersion times (phardness values of the restorative materials was tested using Bonferroni's multiple comparison tests, and it was observed that specimens stored in distilled water demonstrated statistically significant lower mean surface hardness reductions when compared to the specimens immersed in sports and energy drinks after a 1-month evaluation period (phardness of a restorative material depends on the duration of exposure time, and the composition of the material. PMID:23739850

  16. Color stability, water sorption and cytotoxicity of thermoplastic acrylic resin for non metal clasp denture

    OpenAIRE

    Jang, Dae-Eun; Lee, Ji-Young; Jang, Hyun-Seon; Lee, Jang-Jae; Son, Mee-Kyoung

    2015-01-01

    PURPOSE The aim of this study was to compare the color stability, water sorption and cytotoxicity of thermoplastic acrylic resin for the non-metal clasp dentures to those of thermoplastic polyamide and conventional heat-polymerized denture base resins. MATERIALS AND METHODS Three types of denture base resin, which are conventional heat-polymerized acrylic resin (Paladent 20), thermoplastic polyamide resin (Bio Tone), thermoplastic acrylic resin (Acrytone) were used as materials for this study...

  17. Die ouderling en die regeervergaderings in die Nederduitsch ...

    African Journals Online (AJOL)

    Nederduitsch Hervormde Kerk van Afrika 1%1. Notule van die Algemene Kerk- vergadering 1961. Argief van die Nerderduitsch Hervormde Kerk, Pretoria. — 1979. Notule van die Algemene Kerkvergadering 1979. Argief van die Neder duitsch Hervormde Kerk, Pretoria. — 1989a. Kerkwet en Bepalings. Pretoria: Gutenberg.

  18. Die hervertolking van die paradigma in verband met die ...

    African Journals Online (AJOL)

    sal hom ook nie aan die dink sit nie. Om een van sy woorde te gebruik, ek het dit. 'gepleeg' omdat hy my geleer en aan die dink gesit het. KoUcgUlismc. 2. INLEIDING. In sy lofwaardige poging om die negentiende-eeuse Hervormde Kerk van Nederland te reformeer, het Abraham Kuyper die dwaling van hierdie kerk onder ...

  19. Die hervertolking van die paradigma in verband met die ...

    African Journals Online (AJOL)

    Die hervertolking van die paradigma in verband met die Kollegialisme om die. Afrikaanse kerke kerkregtelik te verstaan. E Brown. Universiteit van Stellenbosch. Abstract. Reinterpreting the paradigm concerning 'Kollegialisme' in order to understand the Afrikaans churches accoring to church law. The Afrikaans term ...

  20. Die belangrikste kenmerk van die diereproduksie- bedrywe oor die ...

    African Journals Online (AJOL)

    digdhede teen 1980 uit 'n kudde van 30 rnilj.skape ge- produseer moet word. Tweedens sal die faktore bespreek word wat betrokke is by die winsgewendheid van inten- siewe afronding van vroeggespeende lammers in voerkrale. Dit word algemeen aanvaar dat die bevolking van die Republiek van Suid-Mrika teen 1980 ...

  1. Die kerkregtelike posisie van die ouderling en diaken in die ...

    African Journals Online (AJOL)

    ... drie dekades die Kerkreg gevestig as 'n selfstandige vak in die teologiese curriculum, maar ook 'n baie groot rol gespeel daarin dat die beginsels van die kerk like reg beter begryp word. Naas sy wetenskaplike bydrae word met eweveel genoegdoening gedink aan sy bcsondere persoonlikheid, sy werkvermoe, sy humor-.

  2. Clinical application of removable partial dentures using thermoplastic resin. Part II: Material properties and clinical features of non-metal clasp dentures

    OpenAIRE

    Fueki, Kenji; Ohkubo, Chikahiro; Yatabe, Masaru; Arakawa, Ichiro; Arita, Masahiro; Ino, Satoshi; Kanamori, Toshikazu; Kawai, Yasuhiko; Kawara, Misao; Komiyama, Osamu; Suzuki, Tetsuya; Nagata, Kazuhiro; Hosoki, Maki; Masumi, Shin-ichi; Yamauchi, Mutsuo

    2014-01-01

    This position paper reviews physical and mechanical properties of thermoplastic resin usedfor non-metal clasp dentures, and describes feature of each thermoplastic resin in clinicalapplication of non-metal clasp dentures and complications based on clinical experience ofexpert panels. Since products of thermoplastic resin have great variability in physical andmechanical properties, clinicians should utilize them with careful consideration of thespecific properties of each product. In general, ...

  3. Die kritiese taak van die literator

    Directory of Open Access Journals (Sweden)

    A. L. Combrink

    1981-05-01

    Full Text Available Die beoefening van die literêre kritiek was aanvanklik slegs ’n deeltydse aktiwiteit. Die vroegste literêre kritici was nie as sodanig kritici nie maar het as deel van hulle totale intellektuele aktiwiteit hulle ook uitgelaat oor die letterkunde. Die motivering wat hulle hiertoe gehad het sou in ons dag heeltemal verdag voorkom: ’n uitgesproke didaktiese of moraliserende houding was die reel.

  4. Die gesigte van die neo-marxisme

    Directory of Open Access Journals (Sweden)

    M. C. Boshoff

    1979-05-01

    Full Text Available Ons weet nie sondermeer wat die voorsetsel ‘NEO’ beteken nie. Het Marx in ons tyd herleef of ’n ombuiging, hersiening, aanvulling of selfs ’n korrektief op die oorspronklike visie van Marx gekom? Wat hou die naam, doelstellings en gees van Karl Marx lewendig en dreig om die Westerse lewenswyse en die Christelike godsdiens te vernietig met ’n leefwyse wat die Christelike geloof op sy kardinale punte aanval?

  5. The effects of material loading and flow rate on the disinfection of pathogenic microorganisms using cation resin-silver nanoparticle filter system

    Science.gov (United States)

    Mpenyana-Monyatsi, L.; Mthombeni, N. H.; Onyango, M. S.; Momba, M. N. B.

    2017-08-01

    Waterborne diseases have a negative impact on public health in instances where the available drinking water is of a poor quality. Decentralised systems are needed to provide safe drinking water to rural communities. Therefore, the present study aimed to develop and investigate the point-of-use (POU) water treatment filter packed with resin-coated silver nanoparticles. The filter performance was evaluated by investigating the effects of various bed masses (10 g, 15 g, 20 g) and flow rates (2 mL/min, 5 mL/min, 10 mL/min) by means of breakthrough curves for the removal efficiency of presumptive Escherichia coli, Shigella dysenteriae, Salmonella typhimurium and Vibrio cholerae from spiked groundwater samples. The results revealed that, as the bed mass increases the breakthrough time also increases with regards to all targeted microorganisms. However, when the flow rate increases the breakthrough time decreased. These tests demonstrated that resin-coated silver nanoparticle can be an effective material in removing all targeted microorganisms at 100% removal efficiency before breakthrough points are achieved. Moreover the filter system demonstrated that it is capable of producing 15 L/day of treated water at an operating condition of 10 mL/min flow rate and 15 g bed mass, which is sufficient to provide for seven individuals in the household if they consume 2 L/person/day for drinking purpose. Therefore, the bed mass of the filter system should be increased in order for it to produce sufficient water that will conform to the daily needs of an individual.

  6. Paramagnetic epoxy resin

    Directory of Open Access Journals (Sweden)

    E. C. Vazquez Barreiro

    2017-01-01

    Full Text Available This work illustrates that macrocycles can be used as crosslinking agents for curing epoxy resins, provided that they have appropriate organic functionalities. As macrocycles can complex metal ions in their structure, this curing reaction allows for the introduction of that metal ion into the resin network. As a result, some characteristic physical properties of the metallomacrocycle could be transferred to the new material. The bisphenol A diglycidyl ether (BADGE, n = 0 and hemin (a protoporphyrin IX containing the Fe(III ion, and an additional chloride ligand have been chosen. The new material has been characterized by differential scanning calorimetry (DSC, thermogravimetric analysis (TGA, Fourier Transform Infrared (FT-IR, Nuclear Magnetic Resonance (NMR, Transmission Electron Microscopy (TEM, and magnetic susceptibility measurements. Fe(III remains in the high-spin state during the curing process and, consequently, the final material exhibits the magnetic characteristics of hemin. The loss of the chlorine atom ligand during the cure of the resin allows that Fe(III can act as Lewis acid, catalyzing the crosslinking reactions. At high BADGE n = 0/hemin ratios, the formation of ether and ester bonds occurs simultaneously during the process.

  7. Standard test method for non-destructive assay of nuclear material in waste by passive and active neutron counting using a differential Die-away system

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This test method covers a system that performs nondestructive assay (NDA) of uranium or plutonium, or both, using the active, differential die-away technique (DDT), and passive neutron coincidence counting. Results from the active and passive measurements are combined to determine the total amount of fissile and spontaneously-fissioning material in drums of scrap or waste. Corrections are made to the measurements for the effects of neutron moderation and absorption, assuming that the effects are averaged over the volume of the drum and that no significant lumps of nuclear material are present. These systems are most widely used to assay low-level and transuranic waste, but may also be used for the measurement of scrap materials. The examples given within this test method are specific to the second-generation Los Alamos National Laboratory (LANL) passive-active neutron assay system. 1.1.1 In the active mode, the system measures fissile isotopes such as 235U and 239Pu. The neutrons from a pulsed, 14-MeV ne...

  8. Raw material availability - with a focus on fossil energy resources; Die Verfuegbarkeit von Rohstoffen - insbesondere von fossilen Energietraegern

    Energy Technology Data Exchange (ETDEWEB)

    Gerling, J.P.; Wellmer, F.W. [Bundesanstalt fuer Geowissenschaften und Rohstoffe, Hannover (Germany)

    2004-08-01

    As we speak, the availability of oil has re-emerged in the public debate, driven, among other things, by the barrel price, which peaked at over US dollar 42 in new York last May, for example. Although it does appear that Europe has been able to benefit from a relatively wide spectrum of energies since the 1980s, with domestic oil and coal, nuclear energy programmes in certain countries, and the advances made by natural gas on the heating and electricity markets, the future certainly looks less rosy. In its Green Paper, the EU describes, e.g., future changes on the oil market in a Europe of 30: The decline in domestic production - specifically in the North Sea - must be juxtaposed with a continuously growing demand to more than 900 million tonnes (mt), so that dependence on imports will increase to nearly 80% in 2030. Quite apart from this specific scarcity of domestic raw materials, we also have to consider the phase-out of nuclear energy in some EU states and the extra consumption of fossil energy sources due to climate policy (keyword: lower efficiency as a result of emission-free power generation). Comparable scenarios can be produced both for other raw materials and for other regions on the world market. The resulting question of the availability of raw materials can be broken down - with account taken of an uneven global distribution - to an availability chain with the following elements: - geological availability, - technical availability, - availability of transportation. These specific links in the chain are discussed in the following remarks - in reverse order - focusing on selected aspects. (orig.)

  9. Karakteristik Komposit Resin Berkemampuan Mengalir

    Directory of Open Access Journals (Sweden)

    Bambang Irawan

    2015-10-01

    Full Text Available The use of resin composites as posterior restoratives has markedly increased over the past decade. The patients demand for better esthetics, concerns related to possible mercury toxicity from amalgam and improvements in resin composite materials have significantly contributed the popularity of these materials. Early problems related to composites included excessive wear, less of anatomic form, post operative sensitivity, secondary caries and marginal leakage. Marginal adaptation still remains an unavoidable problem for composite restoration, especially at the gingival wall of cervical or Class II restoration. In an attempt to improve marginal sealing, many techniques and lining materials have been designed. To reduce stress generated by polymerization shrinkage, applying and curing of resin composites in layers is often recommended. Using a thick adhesive layer or low-viscosity resin may, due to its elastic properties, serve as a flexible intermediate layer and compensate for the polymerization stress created in resin composite. Flowable composites were created by retaining the same small particle size of traditional hybrid composite but reducing the filler content and allowing the increased resin to reduce the viscosity of the mixture. Flowable composites were introduced in 1996 as liners, fissure sealants and also in tunnel preparations. They have been suggested for Class I, II, III and V cavity restorations, preventive resin restorations and composite, porcelain and amalgam repairing. Their usage as a liner under high filled resins in posterior restorations has been shown to improve the adaptation of composites and effectively achieve clinically acceptable results. This article attempts to give a broad characteristics of different types of flowable composites. 

  10. Five-year evaluation of a low-shrinkage Silorane resin composite material: A randomized clinical trial

    DEFF Research Database (Denmark)

    Schmidt, Malene; Dige, Irene; Kirkevang, Lise-Lotte

    2015-01-01

    Objectives The aim of the present study was to investigate the clinical performance of a low-shrinkage silorane-based composite material (Filtek™ Silorane, 3 M-Espe) by comparing it with a methacrylate-based composite material (Ceram•X™, Dentsply DeTrey). Material and methods A number of 72patients...... caries was found in two teeth (Filtek™ Silorane). One tooth showed hypersensitivity (Ceram•X™). Conclusion Restorations of both materials were clinically acceptable after 5 years. This study did not find any advantage of the silorane-based composite over the methacrylate-based composite, which indicates...... that the low-shrinkage of Filtek™ Silorane may not be a determinant factor for clinical success in class II cavities. Clinical relevance This paper is the first to evaluate the 5-year clinical performance of a low-shrinkage composite material....

  11. 76 FR 8774 - Granular Polytetrafluoroethylene Resin From Japan

    Science.gov (United States)

    2011-02-15

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Granular Polytetrafluoroethylene Resin From Japan AGENCY: United States International Trade... polytetrafluoroethylene resin from Japan would be likely to lead to continuation or recurrence of material injury. On...

  12. Ultra Fast and Parsimonious Materials Screening for Polymer Solar Cells Using Differentially Pumped Slot-Die Coating

    DEFF Research Database (Denmark)

    Alstrup, Jan; Jørgensen, Mikkel; Medford, Andrew James

    2010-01-01

    the optimum donor−acceptor ratio and device film thickness can be determined with improved accuracy by varying the composition in small steps. We give as an example P3HT-PCBM devices and vary the composition between P3HT and PCBM in steps of 0.5−1% giving 100−200 individual solar cells. The coating experiment...... itself takes less than 4−8 min and requires 15−30 mg each of donor and acceptor material. The optimum donor−acceptor composition of P3HT and PCBM was found to be a broad maximum centered on a 1:1 ratio. We demonstrate how the optimal thickness of the active layer can be found by the same method...

  13. Porous carbon materials for Li-S batteries based on resorcinol-formaldehyde resin with inverse opal structure

    Science.gov (United States)

    Agrawal, Mukesh; Choudhury, Soumyadip; Gruber, Katharina; Simon, Frank; Fischer, Dieter; Albrecht, Victoria; Göbel, Michael; Koller, Stefan; Stamm, Manfred; Ionov, Leonid

    2014-09-01

    This study reports on a novel approach to fabrication of carbon-sulfur composite material and demonstrates its application as cathode for Li-S batteries. Firstly, highly porous carbon material has been prepared by exploiting PMMA colloidal crystal arrays as sacrificial template and subsequently mixing with elemental sulfur at 155 °C. The resulting carbon-sulfur composite cathode material possess very high intrinsic surface area, conductivity and has been found to demonstrate as high as 1600 mAh g-1 capacity in 1st discharge cycle and about 300-400 mAh g-1 in 50th discharge cycle.

  14. Die Kernmethode Wertstromdesign

    OpenAIRE

    Schöllhammer, Oliver

    2014-01-01

    Anhand eines Fallbeispiels wird die Methode des Administrativen Wertstromdesigns vorgestellt. Kern Themen sind die Vorbereitung, die Ist-Analyse und die Definition eines Soll-Zustandes. Diese werden Schritt für Schritt detailliert beschrieben.

  15. Effect of two fluoride varnishes on the color stability of three resin-based restorative materials: an in vitro study.

    Science.gov (United States)

    Tafaroji, Raha; Biria, Mina; Ameri, Farhad; Torabzadeh, Hassan; Qahari, Pasha; Akbarzadeh Baghban, Alireza

    2016-11-01

    The aim of the present study was to evaluate the effect of two fluoride varnishes on color stability of three resin-based restorative materials. Fifty-four discs (14.5 × 1.7 mm) were fabricated from A2 and A3 shades of a compomer (F2000), a flowable composite (Z350), and a hybrid composite (Z250), and incubated at 37°C for 48 h. Dura Shield (colored) and Fluor Protector (colorless) fluoride varnishes were applied onto the discs. The coating was cleaned using a low-speed handpiece and nylon bristle brush after 24 h of storage in distilled water. A second coating was then applied. A control group with no coating was immersed in distilled water and used. The CIE L*a*b* color scale was measured before the treatments and following each cleaning utilizing a spectrophotometer. The colored fluoride varnish exhibited the highest overall color change (∆E) after the first and the second cleaning procedures in all the materials. Among these, the greatest color change was observed in the A3 shade of F2000, followed by the A3 shade of Z-250. The ∆E was less than 3.3 in all groups, and was therefore clinically acceptable. Color changes following the application of fluoride varnishes were found to be clinically acceptable in all groups. © 2015 Wiley Publishing Asia Pty Ltd.

  16. Activation of Magnesium Lignosulfonate and Kraft Lignin: Influence on the Properties of Phenolic Resin-Based Composites for Potential Applications in Abrasive Materials

    Directory of Open Access Journals (Sweden)

    Lukasz Klapiszewski

    2017-06-01

    Full Text Available Magnesium lignosulfonate and kraft lignin were activated by different oxidizing agents for use in phenolic resin composites used for the production of abrasive components. The physicochemical properties of the oxidized materials were analyzed by Fourier transform infrared spectroscopy (FTIR, X-ray photoelectron spectroscopy (XPS, dynamic mechanical-thermal analysis (DMTA and inverse gas chromatography (IGC. The homogeneity of the model abrasive composites containing the studied products was assessed based on observations obtained using a scanning electron microscope (SEM. FTIR and XPS analysis of the oxidized products indicated that the activation process leads mainly to the formation of carbonyl groups. The IGC technique was used to assess changes in the surface energy and the acid–base properties of the studied biopolymers. The changes in the acid–base properties suggest that more groups acting as electron donors appear on the oxidized surface of the materials. DMTA studies showed that the model composites with 5% magnesium lignosulfonate oxidized by H2O2 had the best thermomechanical properties. Based on the results it was possible to propose a hypothetical mechanism of the oxidation of the natural polymers. The use of such oxidized products may improve the thermomechanical properties of abrasive articles.

  17. Bending characteristics of resin concretes

    Directory of Open Access Journals (Sweden)

    Ribeiro Maria Cristina Santos

    2003-01-01

    Full Text Available In this research work the influence of composition and curing conditions in bending strength of polyester and epoxy concrete is analyzed. Various mixtures of resin and aggregates were considered in view of an optimal combination. The Taguchi methodology was applied in order to reduce the number of tests, and in order to evaluate the influence of various parameters in concrete properties. This methodology is very useful for the planning of experiments. Test results, analyzed by this methodology, shown that the most significant factors affecting bending strength properties of resin concretes are the type of resin, resin content and charge content. An optimal formulation leading to a maximum bending strength was achieved in terms of material parameters.

  18. Optimal Composite Materials using NASA Resins or POSS Nanoparticle Modifications for Low Cost Fabrication of Large Composite Aerospace Structures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Reduced mass composite materials are crucial to the success of aerospace systems, but their adoption is inhibited because they require autoclave consolidation, a...

  19. EDF specifications on nuclear grade resins

    International Nuclear Information System (INIS)

    Mascarenhas, Darren; Gressier, Frederic; Taunier, Stephane; Le-Calvar, Marc; Ranchoux, Gilles; Marteau, Herve; Labed, Veronique

    2012-09-01

    Ion exchange resins are widely used across EDF, especially within the nuclear division for the purification of water. Important applications include primary circuit, secondary circuit and effluent treatment, which require high quality nuclear grade resins to retain the dissolved species, some of which may be radioactive. There is a need for more and more efficient purification in order to decrease worker dose during maintenance but also to decrease volumes of radioactive resin waste. Resin performance is subject to several forms of degradation, including physical, chemical, thermal and radioactive, therefore appropriate resin properties have to be selected to reduce such effects. Work has been done with research institutes, manufacturers and on EDF sites to select these properties, create specifications and to continuously improve on these specifications. An interesting example of research regarding resin performance is the resin degradation under irradiation. Resins used in the CVCS circuit of EDF nuclear power plants are subject to irradiation over their lifetime. A study was carried out on the effects of total integrated doses of 0.1, 1 and 10 MGy on typically used EDF mixed bed resins in a 'mini-CVCS' apparatus to simultaneously test actual primary circuit fluid. The tests confirmed that the resins still perform efficiently after a typical CVCS radiation dose. Certain resins also need additional specifications in order to maintain the integrity of the particular circuits they are used in. Recently, EDF has updated its requirements on these high purity nuclear grade resins, produced generic doctrines for all products and materials used on site which include resins of all grades, and as a result have also updated a guide on recommended resin usage for the French fleet of reactors. An overview of the evolutions will be presented. (authors)

  20. DIE SLAG VAN BLOEDRIVIER~

    African Journals Online (AJOL)

    cast iron blown over with bronze stands today. ... deur 'n moerasagtige pan effens noord van die noordel ike drif. Ook hierdeur is die laer in 'n mate gedek. Meer na die suidweste het die bree. Gelato-kop, na die Slag 'Vechtkop' genoem, oor die laer getroon. HOGOsptl'nr. 'i'OSRASACT IGE: PAN. BLOEDRIVI3R. S'S.

  1. STUDI BANDING PELAPISAN MATERIAL SKD11 DENGAN METODE PHYSICAL VAPOUR DEPOSITION DAN THERMAL DIFUSION PADA KOMPONEN INSERT DIES MESIN STAMPING PRESS

    Directory of Open Access Journals (Sweden)

    Robertus Suryo Bisono

    2017-02-01

    Full Text Available Telah dilakukan pelapisan menggunakan Titanium Alumunium Nitrid (TIAlN dengan metode PVD Coating (Physical Vapour Diposition dan TD (Thermal Difusion  untuk perlakuan permukaan baja perkakas SKD11 sebagai material Insert Die komponen mesin Stamping Press setelah perlakuan hardening. Perlakuan permukaan dimaksudkan untuk meningkatkan kualitas permukaan khususnya kekerasan dan perubahan struktur mikro yang terjadi. Untuk mengetahui tingkat keberhasilan dari perlakuan permukaan tersebut dilakukan dengan memvariasi waktu proses, masing masing 2 sample diproses pada 4 jam, 5 jam dan 6 jam dengan temperatur  proses masing-masing  400ᴼ C. Kemudian satu dari tiap variable sample tersebut di panaskan pada suhu 1000ᴼ C selama 1 jam, pendinginan dilalukan dengan udara bebas tanpa proses quenching Untuk mengetahui hasilnya dilakukan uji kekerasan mikro Vickers, pengamatan struktur mikro Scanning Eectron Microscope (SEM, dan pengujian komposisi dengan Energy Defersif Sepectroscopy (EDS untuk mengetahui tingkat penyerapan material terdifusi. Hasil menunjukan bahwa SKD11 yang dilapisi TiAlN dengan metode PVD selama 6 jam menghasilkan lapisan yang paling keras yaitu 1363 HV dengan ketebalan lapisan 5,3µm. Proses pemanasan 1000⁰C selama 1 jam pada sample mengakibatkan penurunan kekerasan sample dan lapisan permukaan sample menjadi lebih tebal hingga 50µm. Penambahan lapisan diakibatkan oleh terdifusinya atom atom yang menyusun lapisan TiAlN ke dalam substrat serta keluarnya atom atom penyusun lapisan hingga membentuk lapisan kompleks.

  2. Die agogiese moment in die pastoraat

    Directory of Open Access Journals (Sweden)

    A. P. C. Duvenage

    1972-06-01

    Full Text Available Die verwarring wat daar vandag in die diakonologiese groep vakke heers, word ten dele weerspieël in die verskeie uitdrukkings en woorde wat gebruik word. By verskillende mense het dit heeltemal verskillende inhoude. Daarom dink ek is dit nodig om te begin met ’n begripsbepaling, om dan later oor die saak te praat.

  3. Review: Resin Composite Filling

    OpenAIRE

    Desmond Ng; Jimmy C. M. Hsiao; Keith C. T. Tong; Harry Kim; Yanjie Mai; Keith H. S. Chan

    2010-01-01

    The leading cause of oral pain and tooth loss is from caries and their treatment include restoration using amalgam, resin, porcelain and gold, endodontic therapy and extraction. Resin composite restorations have grown popular over the last half a century because it can take shades more similar to enamel. Here, we discuss the history and use of resin, comparison between amalgam and resin, clinical procedures involved and finishing and polishing techniques for resin restoration. Although resin ...

  4. Epoxy Resins in Electron Microscopy

    Science.gov (United States)

    Finck, Henry

    1960-01-01

    A method of embedding biological specimens in araldite 502 (Ciba) has been developed for materials available in the United States. Araldite-embedded tissues are suitable for electron microscopy, but the cutting qualities of the resin necessitates more than routine attention during microtomy. The rather high viscosity of araldite 502 also seems to be an unnecessary handicap. The less viscous epoxy epon 812 (Shell) produces specimens with improved cutting qualities, and has several features—low shrinkage and absence of specimen damage during cure, minimal compression of sections, relative absence of electron beam-induced section damage, etc.—which recommends it as a routine embedding material. The hardness of the cured resin can be easily adjusted by several methods to suit the materials embedded in it. Several problems and advantages of working with sections of epoxy resins are also discussed. PMID:13822825

  5. Resin Characterization

    Science.gov (United States)

    2015-06-01

    to see plastic deformation of the surface. 8.1.4.3 Density: Density using the Archimedes principle (ASTM D 792). 8.1.4.4 Density as a Function of...the cure and postcure, quickly cool the sample to 0 °C or lower the temperature to quench the reaction, and then ramp the temperature at 5 °C/min to...prepared by pouring 10 g of resin into a 30-mL screw-cap scintillation vial and adding appropriate amounts of initiator, catalyst, and inhibitor

  6. Effective properties of linear random materials: application to Al/SiC and resin/glass composites

    Science.gov (United States)

    Dumont, Serge; Lebon, Frédéric

    2008-10-01

    Here we present a statistical study on the effective linear properties of random materials, i.e., microstructures which are random lattices described by a stochastic process. The local numerical procedure associated with the homogenization methods used here was based on a wavelet-element method. The resulting numerical results are compared with those obtained using classical theories. A new approach was developed in order to determine the effective properties in cases where the characteristics of the microstructure are not known.

  7. die sinodale verband van die nederduitse gereformeerde kerk in die

    African Journals Online (AJOL)

    Liezel

    daartoe gelei dat daar na dié hofsaak verskillende sinodale verbande in ver- skillende state of kolonies in ... Grootrivier gebring moet word, aldus Van de Wall, maar die kerk kon nie deur staatsgrense beperk word nie. .... Op die punt van lidmaatskap wou die Sinode, trou aan sy gereformeerde gesindheid, nie sondermeer ...

  8. DIE ROL VAN DIE TAALWETENSKAP IN DIE ONTWIKKELING VAN ...

    African Journals Online (AJOL)

    aanslag op die sogenaamde "Intentional Fallacy", heelwat verder. n. Mens sou hier eintlik ook op die invloed van Lacan se toepassing van. De Sacs sure op Freud moet wys, en op Macherey se Theory of Literary. Production. Barthes is naamlik besig om repressie teen te werk, en die teks as produksieproses in stede van ...

  9. Wat is die reg en die vryheid van die eksegeet?

    African Journals Online (AJOL)

    voorgestaan terwyl die Antiocheense skool (Joh Chrysostemos en. Theodorus van Mopsuesta) weer as eksegese gesien het 'n meer letterlike verklaring van die Bybel. Augustinus en Hieronimus het probeer om die twee metodes te kombineer, terwyl Petrus. Lombardus, Alexander van Hailes en Thomas Aquinas 'n vier-.

  10. In Situ Carbon Coated LiNi0.5Mn1.5O4 Cathode Material Prepared by Prepolymer of Melamine Formaldehyde Resin Assisted Method

    Directory of Open Access Journals (Sweden)

    Wei Yang

    2016-01-01

    Full Text Available Carbon coated spinel LiNi0.5Mn1.5O4 were prepared by spray-drying using prepolymer of melamine formaldehyde resin (PMF as carbon source of carbon coating layer. The PMF carbon coated LiNi0.5Mn1.5O4 was characterized by XRD, SEM, and other electrochemical measurements. The as-prepared lithium nickel manganese oxide has the cubic face-centered spinel structure with a space group of Fd3m. It showed good electrochemical performance as a cathode material for lithium ion battery. After 100 discharge and charge cycles at 0.5 C rate, the specific discharge capacity of carbon coated LiNi0.5Mn1.5O4 was 130 mAh·g−1, and the corresponding capacity retention was 98.8%. The 100th cycle specific discharge capacity at 10 C rate of carbon coated LiNi0.5Mn1.5O4 was 105.4 mAh·g−1, and even the corresponding capacity retention was 95.2%.

  11. Effect of different palatal vault shapes on the dimensional stability of glass fiber-reinforced heat-polymerized acrylic resin denture base material.

    Science.gov (United States)

    Dalkiz, Mehmet; Arslan, Demet; Tuncdemir, Ali Riza; Bilgin, M Selim; Aykul, Halil

    2012-01-01

    The aim of this study was to determine the effect of different palatal vault shapes on the dimensional stability of a glass fiber reinforced heat polymerized acrylic resin denture base material. Three edentulous maxilla with shallow, deep and medium shaped palatal vaults were selected and elastomeric impressions were obtained. A maxillary cast with four reference points (A, B, C, and D) was prepared to serve as control. Point (A) was marked in the anterior midline of the edentulous ridge in the incisive papillary region, points (B) and (C) were marked in the right and left posterior midlines of the edentulous ridge in the second molar regions, and point (D) was marked in the posterior palatal midline near the fovea palatina media (Figure 2). To determine linear dimensional changes, distances between four reference points (A-B, A-C, A-D and B-C) were initially measured with a metal gauge accurate within 0.1 mm under a binocular stereo light microscope and data (mm) were recorded. No significant difference of interfacial distance was found in sagittal and frontal sections measured 24 h after polymerization and after 30 days of water storage in any of experimental groups (P>.05). Significant difference of linear dimension were found in all experimental groups (Pbases did not affect the magnitude of interfacial gaps between the bases and the stone cast surfaces.

  12. Material Properties of a Tricalcium Silicate-containing, a Mineral Trioxide Aggregate-containing, and an Epoxy Resin-based Root Canal Sealer.

    Science.gov (United States)

    Prüllage, Raquel-Kathrin; Urban, Kent; Schäfer, Edgar; Dammaschke, Till

    2016-12-01

    The aim was to compare the solubility, radiopacity, and setting times of a tricalcium silicate-containing (BioRoot RCS; Septodont, St Maur-des-Fossés, France) and a mineral trioxide aggregate-containing sealer (MTA Fillapex; Angelus, Londrina, Brazil) with an epoxy resin-based sealer (AH Plus; Dentsply DeTrey, Konstanz, Germany). Solubility in distilled water, radiopacity, and setting time were evaluated in accordance with ISO 6876:2012. The solubility was also measured after soaking the materials in phosphate-buffered saline buffer (PBS). All data were analyzed using 1-way analysis of variance and the Student-Newman-Keuls test. After immersion for 1 minute in distilled water, BioRoot RCS was significantly less soluble than AH Plus and MTA Fillapex (P  .05). The final setting time was 324 (±1) minutes for BioRoot RCS and 612 (±4) minutes for AH Plus. The difference was statistically significant (P < .05). MTA Fillapex did not set completely even after 1 week. The solubility and radiopacity of the sealers were in accordance with ISO 6876:2012. PBS decreased the solubility of BioRoot RCS. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  13. National Metal Casting Research Institute final report. Volume 2, Die casting research

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, D. [University of Northern Iowa, Cedar Falls, IA (United States). Dept. of Industrial Technology] [comp.

    1994-06-01

    Four subprojects were completed: development and evaluation of die coatings, accelerated die life characterization of die materials, evaluation of fluid flow and solidification modeling programs, selection and characterization of Al-based die casting alloys, and influence of die materials and coatings on die casting quality.

  14. In vitro two-body wear of inlay-onlay composite resin restoratives.

    Science.gov (United States)

    Burgoyne, A R; Nicholls, J I; Brudvik, J S

    1991-02-01

    Inlay-onlay composite resin restorations have been introduced to the profession as alternatives to amalgam and direct composite resins. Two-body wear testing was performed on three inlay-onlay resins and one direct composite resins using a machine designed to produce sliding wear. The composite resins were opposed by human enamel, type III gold alloy, and porcelain. Of the investigated materials, the homogeneously microfilled inlay-onlay material showed significantly less wear. The direct composite resin showed significantly the greatest wear. The hybrid inlay-onlay resins showed intermediate wear. The hybrid inlay-onlay resins and the direct composite (small particle, heavily filled) resin created wear tracks in the opposing surfaces while the homogeneous microfill inlay-onlay resin did not. The depth of the observed wear tracks in the opposing surface was sufficiently substantial to warrant further investigation into the wear of materials that oppose composite resin restorations.

  15. Material Removal Rate, Electrode Wear Rate, and Surface Roughness Evaluation in Die Sinking EDM with Hollow Tool through Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Teepu Sultan

    2014-01-01

    Full Text Available Electrical discharge machining is one of the earliest nontraditional machining, extensively used in industry for processing of parts having unusual profiles with reasonable precision. In the present work, an attempt has been made to model material removal rate, electrode wear rate, and surface roughness through response surface methodology in a die sinking EDM process. The optimization was performed in two steps using one factor at a time for preliminary evaluation and a Box-Behnken design involving three variables with three levels for determination of the critical experimental conditions. Pulse on time, pulse off time, and peak current were changed during the tests, while a copper electrode having tubular cross section was employed to machine through holes on EN 353 steel alloy workpiece. The results of analysis of variance indicated that the proposed mathematical models obtained can adequately describe the performances within the limits of factors being studied. The experimental and predicted values were in a good agreement. Surface topography is revealed with the help of scanning electron microscope micrographs.

  16. Microstructure, Mechanical and Surface Morphological Properties of Al5Ti5Cr Master Alloy as Friction Material Prepared by Stir Die Casting

    Science.gov (United States)

    Ahmed, Syed Faisal; Srivastava, Sanjay; Agarwal, Alka Bani

    2017-06-01

    Metal matrix composite offers outstanding properties for better performance of disc brakes. In the present study, the composite of AlTiCr master alloy was prepared by stir die casting method. The developed material was reinforced with (0-10 wt%) silicon carbide (SiC) and boron carbide (B4C). The effects of SiC reinforcement from 0 to 10 wt% on mechanical, microstructure and surface morphological properties of Al MMC was investigated and compared with B4C reinforcement. Physical properties like density and micro Vickers hardness number show an increasing trend with an increase in the percentage of SiC and B4C reinforcement. Mechanical properties viz. UTS, yield strength and percentage of elongation are improved with increasing the fraction of reinforcement. The surface morphology and phase were identified from scanning electron microscopy (SEM) and X-ray diffraction analysis and the oxidized product formed during the casting was investigated by Fourier transformation infrared spectroscopy. This confirms the presence of crystallization of corundum (α-Al2O3) in small traces as one of the alumina phases, within casting sample. Micro-structural characterization by SEM depicted that the particles tend to be more agglomerated more and more with the percentage of the reinforcement. The AFM results reveal that the surface roughness value shows a decreasing trend with SiC reinforcement while roughness increases with increase the percentage of B4C.

  17. Comparative evaluation of compressive strength and flexural strength of conventional core materials with nanohybrid composite resin core material an in vitro study.

    Science.gov (United States)

    Jayanthi, Narasimha; Vinod, V

    2013-09-01

    Several dental materials have been used for core build-up procedures. Most of these materials were not specifically developed for this purpose, but as a consequence of their properties, have found application in core build-up procedures. Improvements in composites and the development of nanocomposites have led to their use as a core build up material due to their superior mechanical properties, optical properties and ease of handling. However it is not clear if they have better mechanical properties than the conventional core build up materials like amalgam, GIC and dual cure composite core build up material. The strength of the core material is very important and this study was undertaken to compare the mechanical properties of materials used for direct core foundations. The differences between the compressive strength and flexural strength of Filtek Z350 nanocomposite with conventional core build up materials like Amalgam, Vitremer GIC and Fluorocore were tested. Cylindrical plexi glass split molds of dimension 6 ± 1 mm [height] x4 ± 1 mm [diameter] were used to fabricate 15 samples of each core material for testing the compressive strength and rectangular plexi glass split molds of dimension 25 ± 1 mm [length] x 2 ± 1 mm[height] x2 ± 1 mm [width] used for fabricating samples for flexural strength. The samples were stored a water bath at 250 °C for 24 h before testing. The samples were tested using a Universal Instron testing machine. The results of the study showed that Fluorocore had the highest compressive strength and flexural strength followed by Filtek Z350 [nanocomposite] Amalgam had the least flexural strength and Vitremer GIC had the least compressive strength. Thus flurocore and nanocomposite are stronger than other core build up materials and hence should be preferred over other conventional core build up materials in extensively damaged teeth.

  18. Changes in the surface of four calcium silicate-containing endodontic materials and an epoxy resin-based sealer after a solubility test.

    Science.gov (United States)

    Borges, R P; Sousa-Neto, M D; Versiani, M A; Rached-Júnior, F A; De-Deus, G; Miranda, C E S; Pécora, J D

    2012-05-01

    To compare the changes in the surface structure and elemental distribution, as well as the percentage of ion release, of four calcium silicate-containing endodontic materials with a well-established epoxy resin-based sealer, submitted to a solubility test. Solubility of AH Plus, iRoot SP, MTA Fillapex, Sealapex and MTA-Angelus (MTA-A) was tested according to ANSI/ADA Specification 57. The deionized water used in the solubility test was submitted to atomic absorption spectrophotometry to determine and quantify Ca(2+), Na(+), K(+), Zn(2+), Ni(2+) and Pb(2+) ions release. In addition, the outer and inner surfaces of nonsubmitted and submitted samples of each material to the solubility test were analysed by means of scanning electron microscopy and energy-dispersive spectroscopy (SEM/EDX). Statistical analysis was performed by using one-way anova and Tukey's post hoc tests (α = 0.05). Solubility results, in percentage, sorted in an increasing order were -1.24 ± 0.19 (MTA-A), 0.28 ± 0.08 (AH Plus), 5.65 ± 0.80 (Sealapex), 14.89 ± 0.73 (MTA Fillapex) and 20.64 ± 1.42 (iRoot SP). AH Plus and MTA-A were statistically similar (P > 0.05), but different from the other materials (P filler particles were more distinguishable. EDX analysis displayed high levels of calcium and carbon at the surface of Sealapex, MTA Fillapex and iRoot SP. AH Plus and MTA-A were in accordance with ANSI/ADA's requirements regarding solubility whilst iRoot SP, MTA Fillapex and Sealapex did not fulfil ANSI/ADA's protocols. High levels of Ca(2+) ion release were observed in all materials except AH Plus. SEM/EDX analysis revealed that all samples had morphological changes in both outer and inner surfaces after the solubility test. High levels of calcium and carbon were also observed at the surface of all materials except AH Plus and MTA-A. © 2011 International Endodontic Journal.

  19. Immobilization of spent resin with epoxy resin

    International Nuclear Information System (INIS)

    Gultom, O.; Suryanto; Sayogo; Ramdan

    1997-01-01

    immobilization of spent resin using epoxy resin has been conducted. The spent resin was mixtured with epoxy resin in variation of concentration, i.e., 30, 40, 50, 60, 70 weight percent of spent resin. The mixture were pour into the plastic tube, with a diameter of 40 mm and height of 40 mm. The density, compressive strength and leaching rate were respectively measured by quanta chrome, paul weber apparatus and gamma spectrometer. The results showed that the increasing of waste concentration would be decreased the compressive strength, and increased density by immobilized waste. The leaching rate of 137 Cs from waste product was not detected in experiment (author)

  20. 75 FR 67105 - Granular Polytetrafluoroethylene Resin From Italy and Japan

    Science.gov (United States)

    2010-11-01

    ... COMMISSION Granular Polytetrafluoroethylene Resin From Italy and Japan AGENCY: United States International... granular polytetrafluoroethylene resin from Italy and Japan. SUMMARY: The Commission hereby gives notice... polytetrafluoroethylene resin from Italy and Japan would be likely to lead to continuation or recurrence of material...

  1. Treatment of White Spot Lesions with Icon (Resin Infiltration)

    Science.gov (United States)

    2017-03-23

    FROM: 59 MDW/SGVU SUBJECT: Professional Presentation Approval 8 MAR2017 1. Your paper, entitled T reatment of White Spot Lesions with Icon ( Resin ... Resin Infiltration) 6. TITLE OF MATERIAL TO BE PUBLISHED OR PRESENTED: Treatment of White Spot lesions with Icon ( Resin In filtration) 7. FUNDING

  2. 21 CFR 872.3200 - Resin tooth bonding agent.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Resin tooth bonding agent. 872.3200 Section 872...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3200 Resin tooth bonding agent. (a) Identification. A resin tooth bonding agent is a device material, such as methylmethacrylate, intended to be painted...

  3. 21 CFR 872.3820 - Root canal filling resin.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Root canal filling resin. 872.3820 Section 872...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3820 Root canal filling resin. (a) Identification. A root canal filling resin is a device composed of material, such as methylmethacrylate, intended...

  4. Halfkrone vir die Nagmaal

    African Journals Online (AJOL)

    Owner

    die omgewing van Velddrif en Laaiplek, ook noordwaarts verby Lambertsbaai tot by. Doringbaai en Strandfontein. “Haar seeverhale is Sussie (Kotze) se belangrikste bydrae tot die Afrikaanse letterkunde”, sê Kotzé-Myburgh in die voorwoord van die versamelbundel. Die leser word herinner aan Kotze se debuutroman, ...

  5. die ontstaan en die ontwikkeling van die skoolkadette-stelsel in die rsa

    African Journals Online (AJOL)

    higiene ook verpligtend was. 42. In die Goewerment Gazette van 4 Mei 1934 word die verantwoordelikheid vir die opstel van leerplanne vir kadette asook vir die inhou van kursusse aan die Direkteur van Militere Opera- sies en Opleiding opgedra. Volgens hierdie Ga- zette was elke seun verplig om 30 uur per jaar opleiding ...

  6. Effect of placement of calcium sulphate when used for the repair of furcation perforations on the seal produced by a resin-based material.

    Science.gov (United States)

    Zou, L; Liu, J; Yin, S-H; Tan, J; Wang, F-M; Li, W; Xue, J

    2007-02-01

    To evaluate the sealing ability of calcium sulphate when used under composite resin for the repair of furcation perforations having different diameters. Perforations of different diameter were created in the floors of pulp chambers in 60 extracted human molar teeth with either a number 3 (1 mm diameter) or 5 (1.5 mm diameter) round bur. The specimens of each group were divided into four sub-groups which were repaired with composite resin either alone or in combination with calcium sulphate that created an artificial floor (15 teeth group(-1)). Eight teeth without furcation perforations served as negative controls. In the leakage detection device, 1 mol L(-1) glucose solution was forced under a pressure of 1.5 KPa from the crown towards the pulp chamber floor. The concentration of leaked glucose was measured at 1, 2, 4, 7, 10, 15 and 20 days using a glucose oxidase method and the data evaluated using the rank sum test. The specimens with larger perforations repaired with composite resin alone had significantly more leakage (P resin, leakage in smaller perforations was markedly lower than that in larger ones (P resin alone (P > 0.05). Calcium sulphate significantly improved the sealing ability of 1 mm perforations repaired with composite resin but not for 1.5 mm perforations.

  7. ,,Die kleur-krisis en die Weste"

    Directory of Open Access Journals (Sweden)

    J. H. Coetzee

    1953-03-01

    Full Text Available Wie vandag onbevange en met ’n opregte begeerte na die volle waarheid oor die sogenaamde „kleurvraagstuk” in Suid-Afrika wil skryf, moet voorwaard bid dat hom die deel van Esegiël te beurt mag val: „Jou voorhoof maak ek hard soos ’n diamant, harder as ’n rots . . . ."

  8. DIE PERSOON VAN VREDE IN DIE SENDING

    African Journals Online (AJOL)

    aan dat 'n lewe onder die gesag van God tot volle vrede lei: “In coming under the rule of Yahweh, moreover, life was made whole and safe.” Dit is spesifiek in die tempel waar die volheid van God se vrede ondervind word (1997:662):. The temple is indeed the place where Israel entered into Yahweh's full zone of shalom.

  9. Die funksie van ruimte in die narratologie

    African Journals Online (AJOL)

    Venter (1985: 20 vv) is van mening dat hierdie negatiewe beoorde- ling van ruimte as blote 'vulling' (Venter 1985: 20) die beginsel was waarvolgens Plato in die ouer literêre paradigma byvoorbeeld die Ilias van Homerus so beskryf het dat alle ruimtelike gegewens sover moont- lik weggelaat is. Hiervolgens kon ruimte te ...

  10. Resin technologies: construction and staining of resin TMA's.

    Science.gov (United States)

    Howat, William J; Wilson, Susan J

    2010-01-01

    The traditional formaldehyde-fixed paraffin-embedded tissue, and therefore the tissue microarrays created from it, provide good morphology but with a compromised antigenicity when compared to frozen tissue. In contrast, while solving the issue of antigenicity, frozen tissue suffers from a lack of morphology. We have demonstrated that tissue microarrays constructed in glycol methacrylate resin, when combined with a cold acetone fixation step, have been able to combine the superior morphology of resin-embedded sections with the superior antigenicity of frozen tissue for prospectively collected material.

  11. KERKWEES IN DIE

    African Journals Online (AJOL)

    KERKWEES IN DIE BRANDING: DIE NEDERDUITSE GEREFORMEERDE. KERK IN ALGEMENE SINODALE VERBAND. 1994-2011. ACTA THEOLOGICA. Supplementum 18. 2013. INHOUD. HOOFSTUK 1 Verantwoording. 1. HOOFSTUK 2 Die Sinode van versoening? 4. HOOFSTUK 3 Bestendiging in 'n nuwe bedeling.

  12. Microbiological study of water-softener resins.

    Science.gov (United States)

    Stamm, J M; Engelhard, W E; Parsons, J E

    1969-09-01

    Microbial identification using effluents backflushed from exhausted urban and rural tank resins and cleaned resins containing the sulfonated copolymer of styrene and divinylbenzene (SDB) were completed, along with microbial assessment of the concentrated stock salt brine. Forty-four different bacterial and fungal genera were identified. Extensive biochemical and animal virulence tests completed on one of the six bacterial salt brine isolates indicated a pathogenic staphylococcal strain. The retention of Staphylococcus aureus, a Flavobacterium sp, and Escherichia coli B bacteriophage was demonstrated both by using the nonexhausted sodium-regenerated resin and by using the same resin exchanged with different mono-, di-, and trivalent cations. Effluent counts completed after bacterial seepage through the resins indicated the Pb(++) exchanged resin removed 55% of the bacteria; Na(+), Fe(++), and Al(+++) removed 31 to 36% and Ca(++) and Cu(++) removed about 10 to 15%. Seventy per cent or more of the bacteriophage was removed by Fe(++), Cu(++), and Al(+++), whereas the Ca(++) and Na(++) cations removed 25 to 31%. Over a 77-day period, nonsterile tap water was passed through bacterial seeded and uninoculated SDB (Na) resin columns. Effluent and resin elution counts demonstrated the growth and survival of 2 different bacteria per column. Increased bacterial retention, survival, and multiplication occurred concomitantly with accumulation of organic and inorganic materials and the Ca(++) and Mg(++) cations from the tap water. Furthermore, microbial elution from resin particles taken from column depths of 1, 8, and 16 cm indicated a bacterial diminution with increasing depths.

  13. Survival of resin infiltrated ceramics under influence of fatigue.

    Science.gov (United States)

    Aboushelib, Moustafa N; Elsafi, Mohamed H

    2016-04-01

    to evaluate influence of cyclic fatigue on two resin infiltrated ceramics and three all-ceramic crowns manufactured using CAD/CAM technology. CAD/CAM anatomically shaped crowns were manufactured using two resin infiltrated ceramics (Lava Ultimate and Vita Enamic), two reinforced glass ceramic milling blocks ((IPS)Empress CAD and (IPS)e.max CAD) and a veneered zirconia core ((IPS)Zir CAD). (IPS)e.max CAD and (IPS)Zir CAD were milled into 0.5mm thick anatomically shaped core structure which received standardized press-on veneer ceramic. The manufactured crowns were cemented on standardized resin dies using a resin adhesive (Panavia F2.0). Initial fracture strength of half of the specimens was calculated using one cycle load to failure in a universal testing machine. The remaining crowns were subjected to 3.7 million chewing cycles (load range 50-200N at 3s interval) in a custom made pneumatic fatigue tester. Survival statistics were calculated and Weibull modulus was measured from fitted load-cycle-failure diagrams. Scanning electron microscopy was performed to fractographically analyze fractured surfaces. Data were analyzed using two way analysis of variance and Bonferroni post hoc tests (α=0.05). Dynamic fatigue resulted in significant reduction (F=7.54, Pceramics and (IPS)Empress demonstrated the highest percent of fracture incidences under the influence of fatigue (35-45% splitting). None of the tested veneered zirconia restorations were fractured during testing, however, chipping of the veneer ceramics was observed in 6 crowns. The lowest percent of failure was observed for (IPS)e.max crowns manifested as 3 cases of minor chipping in addition to two complete fracture incidences. SEM images demonstrated the internal structure of the tested materials and detected location and size of the critical crack. The internal structure of the tested materials significantly influenced their fatigue behavior. Resin infiltrated ceramics were least influenced by fatigue while

  14. Die skepping as gelykenis: 'n Beoordeling van die skeppingsleer ...

    African Journals Online (AJOL)

    en nie met 'n ontologie te doen nie. Die analogia relationis dra, in teenstelling met die vorige, nie die werklikheid oor nie, maar die moontlikheid. Barth vergelyk die teen stelling werklikheid-moontlikheid met die twee bome van die tuin; die van werklikheid (lewe) en die van moontlikheid (kennis) (KD III/l,. 291-295). Hierdie is ...

  15. Die betroubaarheid van die Nuwe Testament vanuit 'n tekskritiese ...

    African Journals Online (AJOL)

    die oud-Latynse manuskripte was een van die redes waarom die. Vulgaat, 'n standaarduitgawe van die Latynse teks, sy beslag gekry het. (vgl Metzger 1968a: 76). Hoewel die betroubaarheid van die teks van die Nuwe Testament dus lank voor die uitvinding van die boekdrukkuns 'n erkende pro bleem was, was dit egter ...

  16. Die funksie van die ^danksegging(s)' in 1 Tessalonisense

    African Journals Online (AJOL)

    53 Die ooiredingsmiddele gebruik ter ondersteuning van die argument. Die verskillende oorredingsmiddele wat in die antieice retorieic aangewend is (kyk. Aristoteles, Ars Rhetorica 1.1), sluit onder meer die volgende in: ethos, pathos en logos. Die oortuigingsmiddel pathos dien die doel om die karakter van die impiisiete.

  17. 21 CFR 177.1380 - Fluorocarbon resins.

    Science.gov (United States)

    2010-04-01

    ...) Chlorotrifluoroethylene-1,1-difluoroethylene-tetrafluoroethylene co-polymer resins produced by copolymerization of..., Extrusion, and Coating Materials,” which is incorporated by reference in accordance with 5 U.S.C. 552(a) and...

  18. Collaborative study for the quality control of trace element determinations in paint coatings. Part 2. Certification of alkyd resin paint reference materials for the migratable contents of trace elements (CRMs 620 and 623).

    Science.gov (United States)

    Roper, P; Walker, R; Quevauviller, P

    2000-02-01

    This paper describes the preparation, homogeneity studies and certification of a series of two paint reference materials (mild steel coated with alkyd resin paint, CRM620, and comminuted paint from alkyd resin paint, CRM623) which have been produced in support of the EU Toy Safety Directive (88/378/EEC). The reference materials have been certified for levels of toxic element migration using the method specified in European Standard EN71-3:1994 published by the European Committee for Standardization. As such, the certified values, indicative values and range data quoted for the reference materials in this paper are method specific and relate only to European Standard EN71-3:1994. The paper summarizes the analytical work carried out and gives a description of the analytical methods used to measure As, Ba, Cd, Cr, Hg, Pb, Sb and Se, the 8 toxic elements specified in European Standard EN71-3:1994, in the sample extracts. Descriptions of the reference materials, certified values, indicative values together with their associated uncertainties or range of laboratory means as appropriate are given. The preparation of a (not certified) reference material (beechwood coated with nitrocellulose paint, RM621) is also described and assigned values for As, Ba, Cd and Se are given. The Hg content could not be certified in any of the reference materials, owing to a high dispersion of results.

  19. Hydrogen in aluminium die castings - formation of hydrides and their effects on base material, heat treatability and weldability; Wasserstoff in Aluminium-Druckgussteilen. Hydridbildung und deren Auswirkungen auf Werkstoffkennwerte, Waermebehandel- und Schweissbarkeit

    Energy Technology Data Exchange (ETDEWEB)

    Wiesner, S.; Rethmeier, M.; Ruge, J. [TU Braunschweig (Germany). Inst. fuer Schweisstechnik

    2001-03-01

    The alloys AB-Al Si9Mg (Silafont 36), AB-Al Mg5Si2Mn (Magsimal 59), AB-Al Mg2.5Mn (Magsimal 22), AB-Al Si11Mg (Calypso 61D), AB-Al Si9 (Calypso 49R) and AB-AlSi8Cu3 (226) were investigated to examine the influence of hydride forming elements on base material, heat treatability and weldability. Experiments with the alloys AB-Al Si11Mg and AB-Al Si8Cu3 with a higher titanium content completed the investigations. The determination of concentration-pressure isotherms on die castings of the alloy AB-Al Si8Cu3 shows a capacity for absorption of hydrogen up to one weight percent. This high factor proves again the chemical binding of hydrogen in aluminium die casting alloys. The tensile strength and elongation of not heat treated die castings were independent of the hydrogen contents. The results show an improvement of the heat treatability and a deterioration of the weldability when the contents of hydride forming elements in the aluminium alloy become higher. (orig.) [German] Die Legierungen AB-Al Si9Mg (Silafont 36), AB-Al Mg5Si2Mn (Magsimal 59), AB-Al Mg2,5Mn (Magsimal 22), AB-Al Si11Mg (Calypso 61D), AB-Al Si9 (Calypso 49R) und AB-AlSi8Cu3 (226) wurden untersucht, um den Einfluss von hydridbildenden Begleitelementen auf Werkstoffkennwerte, Waermebehandel- und Schweissbarkeit zu ermitteln. Versuche an den Legierungen AB-Al Si11Mg und AB-Al Si8Cu3 mit erhoehtem Titangehalt ergaenzten die Untersuchungen. Die Bestimmung der Konzentrations-Druck-Isothermen an Druckgussteilen der Legierung AB-Al Si8Cu3 zeigte eine Wasserstoffaufnahmekapazitaet von bis zu einem Gewichtsprozent. Dieser hohe Wert beweist erneut die chemische Bindung von Wasserstoff in Aluminium-Druckgusslegierungen. Die Werkstoffkennwerte von Zugproben in nicht waermebehandelten Druckgussteilen zeigten keine Abhaengigkeit vom Wasserstoffgehalt. Die Versuchsergebnisse weisen auf eine Verbesserung der Waermebehandelbarkeit und eine Verschlechterung der Schweissbarkeit mit zunehmendem Anteil von hydridbildenden

  20. Evaluation of Resin-Resin Interface in Direct Composite Restoration Repair

    Science.gov (United States)

    Stoleriu, S.; Andrian, S.; Pancu, G.; Nica, I.; Iovan, G.

    2017-06-01

    The aim of this study was to evaluate the resin-resin interface when a universal bonding agent was used in two different strategies in direct restoration repair. Two composite resins (a micro-filled hybrid and a nano-filled hybrid) as old restorations that have to be repair, a universal bonding agent and a micro-filled hybrid composite resin (different then that aged) as new material for repair were chosen for the study. Non-aged samples were used as control and aged samples were used as study groups. The universal bonding agent was applied in etch-and-rinse and in self-etch strategies. The interface between old and new composite resins was evaluated by SEM and the microleakage was assessed by scoring the dye penetration. Very good adaptation of the two different composite resins placed in direct contact in non-aged samples was recorded. No gaps or defects were visible and strong resin-resin contact was observed. After aging, enlargement of resin-resin junction were observed in most of the samples and a increased dye penetration was recorded irrespective of the strategy (etch-and-rinse or self-etch) used for bonding agent application.

  1. Emission and Mechanical Evaluations of Vinyl-Ester Resin Systems

    National Research Council Canada - National Science Library

    Sands, James

    2003-01-01

    Vinyl-ester resins (VE) are frequently used in liquid molding of composite materials for several applications including naval and army structures, commercial boat manufacturing, and building construction...

  2. Review: Resin Composite Filling

    Directory of Open Access Journals (Sweden)

    Desmond Ng

    2010-02-01

    Full Text Available The leading cause of oral pain and tooth loss is from caries and their treatment include restoration using amalgam, resin, porcelain and gold, endodontic therapy and extraction. Resin composite restorations have grown popular over the last half a century because it can take shades more similar to enamel. Here, we discuss the history and use of resin, comparison between amalgam and resin, clinical procedures involved and finishing and polishing techniques for resin restoration. Although resin composite has aesthetic advantages over amalgam, one of the major disadvantage include polymerization shrinkage and future research is needed on reaction kinetics and viscoelastic behaviour to minimize shrinkage stress.

  3. Review: Resin Composite Filling

    Science.gov (United States)

    Chan, Keith H. S.; Mai, Yanjie; Kim, Harry; Tong, Keith C. T.; Ng, Desmond; Hsiao, Jimmy C. M.

    2010-01-01

    The leading cause of oral pain and tooth loss is from caries and their treatment include restoration using amalgam, resin, porcelain and gold, endodontic therapy and extraction. Resin composite restorations have grown popular over the last half a century because it can take shades more similar to enamel. Here, we discuss the history and use of resin, comparison between amalgam and resin, clinical procedures involved and finishing and polishing techniques for resin restoration. Although resin composite has aesthetic advantages over amalgam, one of the major disadvantage include polymerization shrinkage and future research is needed on reaction kinetics and viscoelastic behaviour to minimize shrinkage stress.

  4. Die vrede van Münster / Westfale en die betekenis daarvan vir die ...

    African Journals Online (AJOL)

    In die Suid-Afrikaanse kerkgeskiedenis egter is die Vrede van Münster as epogmakende gebeure tot dusver nie net in die algemeen verwaarloos nie, maar boonop is die direkte verband tussen hierdie sentrale historiese baken aan die een kant en aan die ander kant die vestiging van die VOC se verversingspos aan die ...

  5. A. Selms DIE TEOLOGIE VAN DIE WOORD EN DIE FIGUUR VAN ...

    African Journals Online (AJOL)

    Test

    verhouding tussen God en mens van God af bepaal, maar die terminologie waarmee hy uitdrukking gee aan sy opvatting is die van die Axistoteliese metafisika, en met die terminologie dra hy die ontologiese grondgedagte van Aristoteles in die teologie in. Die sisteem van Aristoteles waarin die absolute en die relatiewe, ...

  6. Comparison of Cashew Nut Shell Liquid (CNS) Resin with Polyester ...

    African Journals Online (AJOL)

    Akorede

    glass fibres, to produce hard and strong structural materials. The use of carbon fibre to reinforce epoxide resin is a fairly recent development. Carbon reinforced epoxy resins are extremely strong materials with a very high value of Young's. Modulus, compared with other plastic materials, and they are finding applications in ...

  7. Metal foam - a material for heat engineering. Porous structures increase the efficiency of heat exchangers and cooling elements; Metallschaum - ein Werkstoff fuer die Waermetechnik. Offenporige Strukturen steigern die Effizienz von Waermeuebertragern und Kuehlelementen

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Franz

    2016-11-01

    Metal foams are increasingly developing into materials with diverse uses. While metal foams with closed pores have already become established as rigid and strong lightweight materials, the open-cell variant is suitable for thermal engineering applications. Until now, the material has been rarely used in heat exchangers or coolers because the production is expensive and its application little tested. Researchers at the Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM in Dresden now want to change this. Together with industry partners, they are further developing the production method, are characterising different metal foams and are testing them in practice.

  8. Kinders in die erediens

    African Journals Online (AJOL)

    Roux neem in hierdie verband sterk standpunt in teen Jean Piaget en Ronald Goldman se teorieë oor kinderontwikkeling. Piaget oordeel dat kenmer- kende aspekte wat die kind se denke op 'n bepaalde stadium vertoon, die norm moet wees vir die bantering van die kind. Hy kategoriseer kinders volgens hulle intellektuele ...

  9. DIE SLAG VAN DOORNKRAAL

    African Journals Online (AJOL)

    Die slag van Doornkraal moet gesien word teen die agtergrond van die ..... saddled and tied to a food wagon. Steyn galloped off, leaving ..... great habit of his. He was proceeding to inspect the position, when he was shot through the neck. "64). Met sy aankoms op Doornkraal, het It kol De Lisle hom gehaas na die "rooi huis" ...

  10. Die Q gemeenskap as een van die grondtipes van die kerk in die ...

    African Journals Online (AJOL)

    p1243322

    sal veral aandag gee aan die term “koninkryk van God” (basileia tou theou) as moontlike aanduiding van “Christelike” denke, of anders gestel: aanduiding van die Q1 gemeenskap se simboliese universum (vgl hier onder), aangesien dit ook die enigste term in Q1 is waarmee die geloofsgemeenskap aangedui word.

  11. GODSBEELDE IN DIE LITURGIE

    African Journals Online (AJOL)

    15 Mei 2010 ... Biezeveld, de Boer, Brümmer, Muis. 2001; Brown 2006; Durand 2007). ... Wanneer sal hy weer in God se teenwoordigheid verskyn (vers 3)? Dié vraag is vol onsekerheid. (Schuman 2004:8). Sy onsekerheid ... God se volk en die enkeling in die geskiedenis het al die trou van God ervaar waarop die digter ...

  12. Die ontwikkeling van die bestuursmotiveringsvraelys (BMV

    Directory of Open Access Journals (Sweden)

    A. S. Engelbrecht

    1991-06-01

    Full Text Available The development of the Managerial Motivation Questionnaire (MMQ: Several criticisms of the psychometric suitability of existing measures of managerial motivation are reported in the literature. This study aimed at developing a new psychometrically sound instrument, the Managerial Motivation Questionnaire (MMQ. This was done on the basis of a comprehensive study of the literature on managerial motivation and the role-motivation theory. The preliminary MMQ was systematically shortened and refined until the final MMQ of 98 items was composed. This was based on social desirability and semantic appraisal, item analysis and factor analysis of the questionnaire. The results indicate that it was possible to develop a final MMQ that was relatively free of social desirability. It further demonstrated satsifactory internal consistencies on two samples (a = 0/90, N = 360; a = 0/91, N = 535, where all subscale items were found to be relatively pure measures of the isolated factors. Although some evidence was found providing support for the reliability of the MMQ, a need for further research on the construct validity of managerial motivation still exists. Opsomming In die literatuur word verskeie punte van kritiek teen die psigometriese geskiktheid van bestaande meetinstrumente van bestuursmotivering gerapporteer. Die doelstelling van hierdie studie was dus om aan die hand van die konseptuele omiyning van bestuursmotivering, en die rolmotiveringsteorie as algemene verwysingsraamwerk, 'n nuwe psigometries aanvaarbare meetinstrument, die Bestuursmotiveringsvraelys (BMV, te ontwikkel. Op grond van sosiale wenslikheids- en semantiese beoordeling, itemontleding en faktorontleding van die voorlopige BMV is die vraelys stelselmatig verkort en verfyn totdat die finale BMV van 98 items saamgestel is. Die resultate dui daarop dat hierdie studie wel daarin geslaag het om 'n finale BMV te ontwikkel wat relatief vry van sosiale wenslikheid is, bevredigende interne

  13. Die Universiteit en beroepsopleidng

    Directory of Open Access Journals (Sweden)

    J. G. Garbers

    1980-03-01

    Full Text Available By elke gradedag is daar by die betrokkenes die neiging om terug te dink aan die pad wat hul bekroning voorafgegaan het. Diegene wat hulle met die volwassewording besig hou, weet maar al te goed aan hoeveel voorwaardes oor baie jare voldoen moes word om ’n jongmens by hier­ die mylpaal te kon bring. Aan baie kwaliteitseise in die opvoeding moes voldoen word. Veel meer as voeding, versorging en die voorsien van middele deur die ouers was nodig. Ook ’n bepaalde kwaliteit kontak en gesprekvoering met mekaar en wedersydse aanvaarding en positiewe verwagtings van mekaar was nodig. Ge- leenthede moes voorsien en benut word, selfstandigheid moes deur die ouers toe- gelaat en deur die kinders verdien word, ens.

  14. Thomas Erastus oor die struktuur van die gemeenskap'^

    African Journals Online (AJOL)

    staan sonder die wil of bevel van die vors nie. In die Zurichse hervorming het Zwingli, die onafhanklike tydgenoot van Luther, grotendeels dieselfde opvattings gehuldig en word die hele gemeenskap, onder die leiding van die burgerlike owerheid, as civitas. Dei waardeer. In 'n sekere sin kan gesê word dat by Zwingli die.

  15. e .Kuraioriufn. DIE W ETENSKAPLIKE BETEKENIS VAN DIE W ERK

    African Journals Online (AJOL)

    Test

    ENGELBRECHT ver antwoordelik vir die Ou-Testamentiese vakke en Hebreeus. Die aan stelling van 'n derde professor het noodsaaklik geword, want dit sou. 85 .... De .Spreuken ran 5a/o?no omvat die nuwe vertaling en die ekse gese van die eerste 24 hoofstukke van die Spreukeboek. Die geskoold- heid in die Semitiese ...

  16. Prediking aan die hand van die metafoor van fiksieskryf

    African Journals Online (AJOL)

    p1243322

    HTS 64(3) 2008 siening van die self en waarheid. In die pre-moderne paradigma kan die dominante metafoor verstaan word aan die hand van 'n spieël wat die lig uit 'n transendente oorsprong weerkaats, terwyl die moderne paradigma uitgedruk word met die metafoor van 'n lamp wat 'n eie, oorspronklike lig binne die self.

  17. Die sestienpersoonlikheidsfaktorvraelys as hulpmiddel by die takseersentrum

    Directory of Open Access Journals (Sweden)

    J. C. D. Augustyn

    1988-05-01

    Full Text Available The 16PF Personality Test as an aid to the assessment centre Assessment centres still remains costly and thime consuming. This study investigates the reduction of time and costs by the use of the 16 PF Personality Test as a method for measuring management dimensions. Promising results were obtained with a relatively small sample for the prediction of initiative and perseverance. Significant multiple correlations were also found for three criteria of management success. Further research may establish the use of the 16 PF as an aid to management assessment and thereby reduce the costs and time involved in assessment centres. Opsomming Takseersentrums se grootste probleem is gelee in die koste en tyd wat dit behels. Hierdie studie ondersoek die moontlikheid om beide te verminder deur die aanwending van die 16 PF Persoonlikheidsvraelys vir die meting van bestuursdimensies. Belowende resultate is met 'n relatiewe klein steekproef bevind ten opsigte van die voorspelling van inisiatiefen deursettingsvermoe. Beduidende meervoudige korrelasies is ook ten opsigte van drie kriteria van bestuursukses bevind. Verdere navorsing kan die gebruik van die 16 PF as hulpmiddel by bestuursevaluering vestig en sodoende die tydsduur en koste van takseersentrums verminder.

  18. Methods and preliminary findings of a cost-effectiveness study of glass-ionomer-based and composite resin sealant materials after 2 yr

    NARCIS (Netherlands)

    Goldman, A.S.; Chen, X.; Fan, M.; Frencken, J.E.F.M.

    2014-01-01

    The cost-effectiveness of glass-carbomer, conventional high-viscosity glass-ionomer cement (HVGIC) [without or with heat (light-emitting diode (LED) thermocuring) application], and composite resin sealants were compared after 2 yr in function. Estimated net costs per sealant were obtained from data

  19. Post-irradiation hardness of resin-modified glass ionomer cements and a polyacid-modified composite resin

    International Nuclear Information System (INIS)

    Yap, A.U.J.

    1997-01-01

    This study examined the post-irradiation hardness of resin-modified glass ionomer cements and a polyacid-modified composite resin using a digital microhardness tester. Change in hardness of these materials over a period of 6 months was compared to that of conventional glass ionomer cements and a composite resin. With the exception of the composite resin, all materials showed a significant increase in hardness over 24 h after their initial set. Dual-cure resin-modified glass ionomer cements showed decreased hardness with increased storage time in saline at 37 o C. Results suggest that the addition of resins to glass ionomer cements does not improve initial hardness and does not negate the acid-base reaction of conventional cements. Resin addition may, however, lead to increased water sorption and decreased hardness. (author)

  20. Die ontwikkeling van menslike potensiaal in die Republiek van Suid ...

    African Journals Online (AJOL)

    Erna Kinsey

    Dit het dus ook te doen met lewenstandaard, aangesien lewenstandaard `n bepalende faktor is met betrekking tot die optimale ontwikkeling van menslike potensiaal. Ander minder materiële aspekte van menslike potensiaal het te doen met menslike vryheid, waaronder vryheid van spraak, beweging en keuse ter sake is.

  1. Die kerk: 'n Verenigende of verdelende faktor in die ontwikkeling ...

    African Journals Online (AJOL)

    As 'n mens in die spieël kyk, sien hy iets wat 'n watjie méér is as die engele, bes moontlik 'n god. En dis waar die kerk in die spel kom. 1. DIE TAAK VAN DIE KERK. Sedert die dae van die Ou Testament is dit een van die mees basiese take van die. 'kerk' om aan mense te verkondig dat daar net één God is, dat hulle self ...

  2. DIE GRONDSTEENLEGGING VAN DIE TWEEDE TEMPEL. 1. D:e ...

    African Journals Online (AJOL)

    Test

    In die boek van die profesieë van Sagaria is daar twee perikope wat oor die tempelbou handel, H. 4:6b-10a en H. 8:9-13. Die eersge- noemde gedeelte is 'n onderbreking van die vyfde naggesig, dié van die. ') Die vertrek uit Babei het waarskynlik in die voorjaar, omstreej^ April plaasgevind, die aankoms in Palestina in die ...

  3. Evaluation of the Luting Cement Space for Provisional Restoration by using Various Coats of Die Spacer Materials-An Invitro Study.

    Science.gov (United States)

    Chiramana, Sandeep; Siddineni, Krishna Chaitanya; Jyothula, Ravi Rakesh Dev; Gade, Phani Krishna; Bhupathi, Deepthi; Kondaka, Sudheer; Hussain, Zakir; Paluri, Geetha Bhavani

    2014-09-01

    The present study was to evaluate the space provided for the temporary luting cement, after the application of various coats of die spacers, during the fabrication of provisional crowns and bridges. A total of 50 specimens of dental stone with provisional crowns on all these samples were prepared and were divided into five groups based on the application of various coats of different die spacers. Later these specimens were sectioned buccolingually and were observed using a stereomicroscope under 100X magnification. The images thus obtained were evaluated and noted for the amount of space between the inner surface of the provisional crown and the specimens at five different locations using Image Pro 6.0 Express software and the values were subjected to one-way ANOVA test, and unpaired t-test. There was a significant increase of luting space thickness with various die spacer applications than the specimens of control group. Specimens of double coat applications of silver and gold die spacers showed higher luting cement space than the separating media application specimens.

  4. Nanostructured films of inorganic-organic hybrid materials for application in photovoltaics; Nanostrukturierte Filme aus anorganisch-organischen Hybridmaterialien fuer die Photovoltaik

    Energy Technology Data Exchange (ETDEWEB)

    Perlich, Jan

    2009-06-25

    Nanostructured thin films of crystalline TiO{sub 2} for applications in photovoltaics were studied. The fabrication of the thin films is based on a hybrid approach. The anorganic metal oxide prepared via a sol-gel synthesis is structurated by the template properties of the applied organic block-copolymer. Via the film epitaxy by means of centrifugal coating first hybrid films (polymer-nanocomposite films) were fabricated, which were changed by calcination into crystalline TiO{sub 2} films with taylored morphology. The successful development of novel preparation approaches to the adaption to consisting conditions in the application field of photovoltaics contains a route to the fine-tuning of the morphology as well as the fabrication of hierarchical morphologies in different configurations. The structural study of the single nanostructurated TiO{sub 2} films up to the functional multilayer arrangement as photovoltaic demonstration cell was performed with conventionally imaging methods, as for instance scanning force microscopy and electron microscopy as well as the special small-angle X-ray scattering method under rigid incident angle (GISAXS). [German] Es wurden nanostrukturierte duenne Filme aus kristallinem TiO{sub 2} fuer Anwendungen in der Photovoltaik untersucht. Die Herstellung der duennen Filme basiert auf einem Hybridansatz. Das ueber eine Sol-Gel-Synthese bereitgestellte anorganische Metalloxid wird durch die Template-Eigenschaften des eingesetzten organischen Block-Copolymers strukturiert. Ueber die Filmaufbringung mittels Schleuderbeschichtung wurden zunaechst Hybridfilme (Polymer-Nanokompositfilme) hergestellt, die durch Kalzinierung in kristalline TiO{sub 2}-Filme mit massgeschneiderter Morphologie umgewandelt werden. Die erfolgreiche Entwicklung von neuartigen Praeparationsansaetzen zur Adaption an bestehende Gegebenheiten im Anwendungsgebiet der Photovoltaik beinhaltet eine Route zur Feineinstellung der Morphologie sowie die Herstellung von

  5. Die etiek van Luther

    Directory of Open Access Journals (Sweden)

    J. H. van Wyk

    1983-06-01

    Full Text Available Dink ons aan die etiek van Luther dan spring onmiddellik ’n paar boeiende uitsprake van hom na vore soos o.a. dat Christene vanuit die gemeenskap met Christus nuwe dekaloë moet maak wat helderder as die van Moses kan wees, of dat ons in bepaalde sin vir ons naaste ’n Christus moet word. Die bydrae van Luther 'tot die Christelike etiek is sonder twyfel van groot betekenis en die bestudering daarvan die moeite werd. Luther is geprys as rewolusionêr en verguis as konserwatis, hy is geëer as iemand wat weer die ware be­tekenis van godsdiens ontdek het toe die lewe vervloei het in etiek. Of dit egter korrek is om sy etiek as konserwatief te tipeer, soos White doen, moet betwyfel word.

  6. DIE OUTESTAMENTIESE LEER AANGAANDE DIE MENS AS ...

    African Journals Online (AJOL)

    Test

    verdwyn s o o s rook". Meer voorbeetde gee die genoemde grammatikas. ') Hierdie opvatting van be vind ons bv. in die Leidsche Vertaling 1899, by JoH. H EH N , Zum TermiïiMS ,,BiM Qottes" in Festschrift Sachau, 1915, BÖ H L in TeÍMt en Uitieg,.

  7. Evalueringskriteria en die interaksie tussen die leksikografieteorie ...

    African Journals Online (AJOL)

    Ten slotte word hierdie probleem toegelig aan die hand van die ontwerpkenmerke van WAT Deel XIV. ... Nielsen 2006, 2009 and Swanepoel 2008, 2013) is that reviews only provide an analysis and description of the design features of dictionaries and not also an evaluation based on a set of clearly formulated and ...

  8. die pers as bron oor die geskiedenis van die eerste vrydeidsoorlog

    African Journals Online (AJOL)

    Die doel van hierdie artikel is om die redes vir die publikasie van verdraaiings in die koerante van destyds te ondersoek en vervolgens aan Ie dui waarom die pers nie as enigste bron gebruik kan word om die geskiedenis van die Eerste. Vryheidsoorlog te boekstaaf nie. Dit is nie moontlik om al die koerante wat gedurende ...

  9. Synthesis and characterizations of melamine-based epoxy resins.

    Science.gov (United States)

    Ricciotti, Laura; Roviello, Giuseppina; Tarallo, Oreste; Borbone, Fabio; Ferone, Claudio; Colangelo, Francesco; Catauro, Michelina; Cioffi, Raffaele

    2013-09-05

    A new, easy and cost-effective synthetic procedure for the preparation of thermosetting melamine-based epoxy resins is reported. By this innovative synthetic method, different kinds of resins can be obtained just by mixing the reagents in the presence of a catalyst without solvent and with mild curing conditions. Two types of resins were synthesized using melamine and a glycidyl derivative (resins I) or by adding a silane derivative (resin II). The resins were characterized by means of chemical-physical and thermal techniques. Experimental results show that all the prepared resins have a good thermal stability, but differ for their mechanical properties: resin I exhibits remarkable stiffness with a storage modulus value up to 830 MPa at room temperature, while lower storage moduli were found for resin II, indicating that the presence of silane groups could enhance the flexibility of these materials. The resins show a pot life higher than 30 min, which makes these resins good candidates for practical applications. The functionalization with silane terminations can be exploited in the formulation of hybrid organic-inorganic composite materials.

  10. Liquid Resins-Based Additive Manufacturing

    Science.gov (United States)

    Wang, Fei; Wang, Fuke

    In this review, additive manufacturing technologies using liquid resins as materials are reviewed from the perspective of printing technologies and materials. Most importantly, recent progress of new printing technologies and printers as well as novel printing materials and their applications are summarized, based on which potential future research directions are discussed at the end of this review.

  11. Evaluating the effect of in-process material on the binding mechanisms of surrogate viral particles to a multi-modal anion exchange resin.

    Science.gov (United States)

    Brown, Matthew R; Burnham, Michael S; Johnson, Sarah A; Lute, Scott C; Brorson, Kurt A; Roush, David J

    2018-02-10

    Bacteriophage binding mechanisms to multi-modal anion exchange resin may include both anion exchange and hydrophobic interactions, or the mechanism can be dominated by a single moiety. However, previous studies have reported binding mechanisms defined for simple solutions containing only buffer and a surrogate viral spike (i.e. bacteriophage ΦX174, PR772, and PP7). We employed phage spiked in-process monoclonal antibody (mAb) pools to model binding under bioprocessing conditions. These experiments allow the individual contributions of the mAb, in-process impurities, and buffer composition on mechanistic removal of phages to be studied. PP7 and PR772 use synergetic binding by the positively charged quaternary amine and the hydrophobic aromatic phenyl group to bind multi-modal resin. ΦX174's binding mechanism remains inconclusive due to operating conditions. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. die self-sny fenomeen onder jongmense: perspektiewe vanuit die ...

    African Journals Online (AJOL)

    word eerstens gefokus op redes vir die toename van die fenomeen van self- sny. Daarna kom die belangrikheid van emosies, die dinamika van die proses self asook 'n behandelingsprogram aan die orde. Ten slotte word 'n aantal pastorale perspektiewe aan die orde gestel asook riglyne ten einde 'n terugval te voorkom.

  13. Die plek van Empedokles in die metafisies-mistieke tradisie

    African Journals Online (AJOL)

    p1243322

    bodhisatva-, miskien selfs buddha-begrip. Die verskille tussen die twee stelsels is ewe opvallend. 'n Interessante vergelykingspunt met spesifiek die Boeddhisme is byvoorbeeld die relasie tussen liefde en twis (haat). By die vroeë Boeddhisme draai die konvensionele mikro-kosmiese (menslike) lewensproses om die drie ...

  14. DIE KONINGSBEDE AS ELEMENT IN DIE KRONINGSRITUEEL. By ...

    African Journals Online (AJOL)

    Test

    3:5 en II Kron. 1 :7. Wat die rede is, waarom die Afrikaanse vertalers hier 'n ander woord gebruik het as in Kon. en Kron., bly onduidelik; die werkwoord sya'af word op sestien verskillende maniere deur hulle weergegee. Die inhoud van die koningsbede, waarop Ps. 2:8 sinspeel is die opperheerskappy oor die omwonende ...

  15. die suid-afrikaanse oorlogsekonomie gedurende die tweede ...

    African Journals Online (AJOL)

    Amerikaanse leer in Europa teen die einde van die jaar en die begin van 1945. Die Amerikaanse veldtog in die Stille Oseaan het geweldige laai- ruimte in beslag geneem. 'n Aansienlike kwota was ook voortdurend betrokke by die vervoer van noodsaaklike voorrade na Brittanje. Tot die tweede helfte van 1941, dws vir ...

  16. P. J. N. Smal, Die Universalisme in die Psalms. Academisch ...

    African Journals Online (AJOL)

    Test

    dat die historiese element in Israel se Godsopenbaring en daarmee die insig in sy betekenis te kort gedoen word. Die betekenis van die studie vir die historia revelationis is daardeur gering; as duidelike „tydlose” sistematisering van Outestamentiese gegewens oor die betrokke onder- werpe, soos die laaste hoofstuk, bl.

  17. Patristiek en die studie van die Nuwe Testament

    African Journals Online (AJOL)

    Die titel van die reeks is Biblia Patristica. Die eerste volume dek die patristiese literatuur tot by Tertullianus en Klemens van Aleksan- drië. Dit bevat 28 000 verwysings. Die tweede volume bevat 22 000 verwysings en dek die derde eeu, uitgesonderd Origenes. Die omvang- rykheid van hierdie projek word duidelik wanneer ...

  18. Navorsing op die gebied van die sosiale wetenskappe*

    Directory of Open Access Journals (Sweden)

    P. M. Robbertse

    1958-03-01

    Full Text Available In Hollands is die woord scientia vertaal met wetenskap, wat sowel die natuur- as die geesteswetenskappe insluit, waardeur die woordsy oorspronklike betekenis behou. Die neiging bestaan om die Engels science met wetenskap in Afrikaans te vertaal, waarmee dan eintlik die natuurwetenskap bedoel word.

  19. Die geskiedenis van die saw gedenkteken te Fort Klapperkop ...

    African Journals Online (AJOL)

    Die SAW Gedenkteken se lotgevalle is nou verbonde aan die van die. Militere Museum Fort Klapperkop aangesien die Gedenkteken op die terrein van Fort Klapperkop opgerig is. Weens rasionalisasie is die voortbestaan van Fort Klapperkop Museum onseker. Dit plaas ongetwyfeld dan ook 'n vraagteken agter die ...

  20. Influence of ``short`` cracks on fracture mechanics material characteristics - methods of determination and their effects; Einfluss ``kurzer`` Risse auf die bruchmechanischen Werkstoffkennwerte - Bestimmungsmethoden und ihre Auswirkungen

    Energy Technology Data Exchange (ETDEWEB)

    Roos, E.; Silcher, H.; Eisele, U. [Stuttgart Univ. (Germany). Staatliche Materialpruefungsanstalt

    1998-11-01

    The methods applicable to determining fracture mechanics characteristics of the threshold toughness, published in various recommendations and draft standards, are compared and evaluated. The methods are put to the test and comparatively analysed using compact tensile specimens (CT), standardized three-point bending specimens (TPB), and TPB specimens with short cracks. It is shown that only the physical crack initiation value J{sub i} yields results that can be applied for comparative evaluations. (orig./CB) [Deutsch] Die fuer das Uebergangsgebiet der Zaehigkeit in verschiedenen Pruefempfehlungen und Normvorschlaegen veroeffentlichten Verfahren zur Bestimmung bruchmechanischer Kennwerte werden gegenuebergestellt und bewertet. Anhand von Kompaktzugproben (CT), Standard Drei-Punkt-Biegeproben (TPB) und TPB-Proben mit kurzen Rissen werden diese Verfahren angewandt und die Ergebnisse verglichen. Es zeigt sich, dass nur der physikalische Risseinleitungswert J{sub i} fuer alle untersuchten Probenformen vergleichbare und uebertragbare Ergebnisse liefert. (orig.)

  1. DIE ONSTERFLIKHEID VAN DIE MENSLIKE SIEL') Daar is geen ...

    African Journals Online (AJOL)

    Test

    die mag van die Bose wat dit as 'n usurpator wederregtelik hom toegeëien het. Christus sê dan ook in Johannes 6 vers 47 dat wie in. Hom glo, d.w.s. wie in Hom ingewortel en ingeplant is, het die ewige lewe, besit die onsterflikheid. Die dood is die gevolg van die wegbreking van God, en die ewige lewe is die gevolg van ...

  2. Die radio in Afrika

    Directory of Open Access Journals (Sweden)

    S. de Villiers

    1966-03-01

    Full Text Available Omvang van radio-uitsendings in en na Afrika. — Redes vir die versnelde tempo van uitbreiding. — Radio as die geskikste massa-kommunikasiemiddel vir Afrika. — Faktore wat die verspreiding bemoeilik. — Skouspelagtige toename in luistertalle.Toe Plinius, wat in die jaar 79 oorlede is, in sy „Historia Naturalis” verklaar het dat daar altyd iets nuuts uit Afrika afkomstig is, kon hy nouliks voorsien het dat die „iets" negentien eeue later in die lug sou setel wat hierdie reuse-vasteland oorspan — ’n Babelse spraakverwarring en ’n ongekende, verbete woorde-oorlog in die etergolwe, onder meer daarop bereken om die harte en hoofde van derduisendes te verower.

  3. Die Bedeutung des Internet

    OpenAIRE

    Picot, Arnold; Neuburger, Rahild; Prinz, Aloys; Esser, Josef; Hoeren, Thomas

    2000-01-01

    Gegenwärtig vollzieht sich eine Wandlung von Wirtschaft und Gesellschaft durch das Internet. Sind die hohen Erwartungen, die von vielen an das Internet geknüpft werden, berechtigt? Was vermag das Internet zu leisten?

  4. Mechanistic understanding of fouling of protein A chromatography resin.

    Science.gov (United States)

    Pathak, Mili; Rathore, Anurag S

    2016-08-12

    This paper aims to provide a thorough understanding of how fouling of Protein A resin takes place. Binding and mass transport properties of widely used agarose-based Protein A resin, MabSelect SuRe™, have been examined to understand the mechanism of resin fouling. There could be various factors that impact resin fouling. These include product/impurity build-up due to components in the feed material and ligand degradation due to the use of harsh buffers. To unravel their contributions, cycling studies were performed with and without product loading. The results presented in this paper provide a lucid understanding of the causative factors that limit Protein A chromatographic resin lifetime. The capacity fall for protein A resin at the end of 100th cycle due to use of feed material was found to be five times greater than that without using feed material. Compared to the fresh resin, the cycled resin samples shows 24% reduction in particle porosity and 51% reduction in pore mass transfer coefficient. Transmission electron microscopy (TEM) was used to qualitatively monitor accumulation of foulants on the cycled resin. Fouled resin sample contained a dense residue in the interior and exterior of resin particle both as a film at the bead surface and as granules. The surface activation energy increased five times in the case of fouled resin sample. The major event in fouling was identified as the non-specific adsorption of the feed material components on resin, signaling that pore diffusion is the rate limiting step. It is anticipated that these findings will assist in development of a more robust and economical downstream manufacturing process for monoclonal antibody purification. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Cyanate Ester-Based Encapsulation Material for High-Temperature Applications

    Science.gov (United States)

    Chidambaram, Vivek; Rong, Eric Phua Jian; Lip, Gan Chee; Daniel, Rhee Min Woo

    2013-09-01

    Cyanate ester resin-based composite materials have been proposed as potential encapsulants for high-temperature applications. The objective of this study is to develop a cyanate ester-based encapsulant, which can also serve as a flip-chip underfill as well as for traditional encapsulation. Two different materials, quartz and alumina fillers, have been studied. The impact of shapes and sizes of the fillers on the overall thermomechanical properties has been investigated. The adhesion strengths of the materials to the ceramic substrate, Kovar lid, and silicon die have also been characterized. The modulus of the resin and the shape of the fillers play a pivotal role in minimizing thermal stress, generated by coefficient of thermal expansion mismatches. Smaller filler particles were found to have better adhesion to the cyanate ester resin. The high-temperature performance of the cyanate ester-based encapsulants was evaluated by thermal aging at 300°C for up to 500 h.

  6. Die Tempelrolle und die Struktureigenschaften des Kollagens

    OpenAIRE

    Schütz, Roman

    2016-01-01

    Die „Schriftrollen vom Toten Meer“ stoßen seit ihrer Entdeckung Mitte des letzten Jahrhunderts bei den Religionshistorikern und in der breiten Öffentlichkeit auf großes Interesse. Sie stammen aus der Zeit der Zweiten Tempelperiode - der Wiege des Christentums und dem Vorabend der Zerstörung des Tempels von Jerusalem durch die Römer. Diese Ereignisse haben den weiteren Verlauf der Menschheitsgeschichte entscheidend mitgeprägt. Dem Text der Rollen hat die Forschung sehr viel Aufmerksamkeit ...

  7. Die humanistiese mensbeeld

    African Journals Online (AJOL)

    Liberalisme-kapitalisme vanuit die denke van Adam Smith (1723-. 1790), demokratiese-sosialisme vanuit die denke van Jean Jacques Rousseau (1712-. 1778), en Marxisme-kommunisme vanuit die denke van Karl Marx (1818-1883). In elkeen van hierdie ideologiese strominge bestaan 'n mensbeeld soos dit bepaal.

  8. Die gebruik van parallelplaatreologie vir die bepaling van die intrinsieke viskositeit van poli-etileentereftalaat

    Directory of Open Access Journals (Sweden)

    O. C. Vorster

    2005-09-01

    Full Text Available Die bepaling van die intrinsieke viskositeit van poli-etileentereftalaat word bemoeilik deur die feit dat daar tans slegs twee metodes in gebruik is. In die eerste metode word die bepaling deur middel van oplossingsviskometrie gedoen, maar die toksisiteit van die oplosmiddel, asook die tydperk wat dit neem om die bepaling te doen, is ’n probleem. Die tweede metode word beperk deur die kompleksiteit en beskikbaarheid van die apparatuur in Suid-Afrika. In hierdie studie word ’n alternatiewe metode, gebaseer op parallelplaatreologie, voorgestel wat albei hierdie probleme oorkom en die resultate sodoende verkry, word vergelyk met dié wat met bestaande metodes verkry is.

  9. Die invloed van die neo-marxistiese kultuuranalise op die Wêreldraad van Kerke en die Gereformeerde Kerke van Nederland

    Directory of Open Access Journals (Sweden)

    J. M. Vorster

    1979-05-01

    Full Text Available Toe die studente dwarsoor die VSA en Europa in die laat sestigerjare ’n plotselinge en radikale verset openbaar het teen die bestaande orde, het hulle die deur geopen vir ’n nuwe mededinger om die hart van die Westerse kultuur. Dit is die nou reeds bekende neo-Marxisme. Sedertdien het hierdie jongeling sy voetspore op vele vlakke van die Westerse kultuur gelaat.

  10. Prediction of Part Distortion in Die Casting

    Energy Technology Data Exchange (ETDEWEB)

    R. Allen Miller

    2005-03-30

    The die casting process is one of the net shape manufacturing techniques and is widely used to produce high production castings with tight tolerances for many industries. An understanding of the stress distribution and the deformation pattern of parts produced by die casting will result in less deviation from the part design specification, a better die design and eventually more productivity and cost savings. This report presents methods that can be used to simulate the die casting process in order to predict the deformation and stresses in the produced part and assesses the degree to which distortion modeling is practical for die casting at the current time. A coupled thermal-mechanical finite elements model was used to simulate the die casting process. The simulation models the effect of thermal and mechanical interaction between the casting and the die. It also includes the temperature dependant material properties of the casting. Based on a designed experiment, a sensitivity analysis was conducted on the model to investigate the effect of key factors. These factors include the casting material model, material properties and thermal interaction between casting and dies. To verify the casting distortion predictions, it was compared against the measured dimensions of produced parts. The comparison included dimensions along and across the parting plane and the flatness of one surface.

  11. · Los of vas geskryf: die leksikograaf, die spelreels en die ...

    African Journals Online (AJOL)

    die verskyning van die 1991-uitgawe van die Afriknanse Woordelys en Spelreels het die spelreels en die taalwerklikheid nader aan mekaar ... onder KROM I 1a en b: Die definisie verskyn by die los vorm ... bloot om ortografiese verskille, anders as in gevalle soos geel perske/geel- perske en groot mens/grootmens waar ...

  12. Verskuiwing in die moraal?

    Directory of Open Access Journals (Sweden)

    S.P. van der Walt

    1974-03-01

    Full Text Available Modewoorde het ons deesdae oorgenoeg in die Christelike sedeleer en hulle kan nogal verwarring stig. U moet my vergun om met u te spreek oor een so ’n modewoord nl „verskuiwing’’ in die moraal. Dis nogal ’n mooi woord, wat so dikwels gebruik word op baie terreine en tog meer wil aandui as maar net ’n veranderde sienswyse, ’n wysiging in opvattinge of nuwe riglyne wat al gangbaar geword het in die praktyk. Die begrip wil eintlik die ewolusionêre gang beklemtoon, want dit is dan eintlik net die ou norme wat effens anders bekyk word of nie meer so nou geneem of dik onderstreep word nie. Die verskuiwing beteken dan dat alles nog dieselfde bly, net die posisie of plek het verander. Verskuiwing beteken tog plekverandering of plekwisseling en dan sekerlik nie in die sin dat die plekke ver uitmekaar lê nie. Verskuiwing beteken net maar vlak langs die vorige te staan kom. As dit dan ’n beter plek is, is dit ewolusie, ontwikkeling, verbetering.

  13. Petroleum Resins: Separation, Character, and Role in Petroleum

    DEFF Research Database (Denmark)

    Andersen, Simon Ivar; Speight, James

    2001-01-01

    In petroleum science, the term resin generally implies material that has been eluted from various solid adsorbents, whereas the term maltenes (or petrolenes) indicates a mixture of the resins and oils obtained as filtrates from the asphaltene precipitation. Thus, after the asphaltenes are precipi......In petroleum science, the term resin generally implies material that has been eluted from various solid adsorbents, whereas the term maltenes (or petrolenes) indicates a mixture of the resins and oils obtained as filtrates from the asphaltene precipitation. Thus, after the asphaltenes...... are precipitated, adsorbents are added to the n-pentane solutions of the resins and oils, by which process the resins are adsorbed and subsequently recovered by the use of a more polar solvent, and the oils remain in solution. The resin fraction plays an important role in the stability of petroleum and prevents...... of the fact that the resin fraction is extremely important to the stability of petroleum, there is surprisingly little work reported on the characteristics of the resins. This article summarizes the work that has been carried out in determining the character and properties of the resin constituents...

  14. Posterior bulk-filled resin composite restorations.

    DEFF Research Database (Denmark)

    van Dijken, Jan WV; Pallesen, Ulla

    2016-01-01

    Purpose/aim: To evaluate in a randomized controlled study the 5-year clinical durability of a flowable resin composite bulk-fill technique in Class I and Class II restorations. Materials and methods: 38 pairs Class I and 62 pairs Class II restorations were placed in 44 male and 42 female (mean age...... 52.4 years). Each patient received at least two, as similar as possible, extended Class I or Class II restorations. In all cavities, a 1-step self-etch adhesive (Xeno V+) was applied. Randomized, one of the cavities of each pair received the flowable bulk-filled resin composite (SDR), in increments...... up to 4mm as needed to fill the cavity 2mm short of the occlusal cavosurface. The occlusal part was completed with the nano-hybrid resin composite (Ceram X mono+). In the other cavity, the resin composite-only (Ceram X mono+) was placed in 2mm increments. The restorations were evaluated using...

  15. Die 'verleentheid' van die teoloog voor die teodiseeprobleem

    African Journals Online (AJOL)

    Moltmann 1976: 138-147 en Jiingel 1978: 55—138) waarmee gewoonlik bedoel word dat God of irrelevant of apaties of magteloos is, word gekenmerk deur 'n verskraalde Godsbegrip. God was nie by Auschwitz nie en is nie in die kankersale van Bloemfontein afwesig nie. Hy is nie magteloos nie en hy is nie liefdeloos nie.

  16. Die Nuwe Testament en mitologie: Die probleem van die ...

    African Journals Online (AJOL)

    29 Mei 2015 ... Die aarde as leefwêreld van mense is oop vir invloede van bo of onder: God en sy engele kan ingryp in .... aanvaar) is om oop te wees vir God se toekoms. Geloof is daarom ook gehoorsaamheid ..... James Dunn stel dit so: 'The dialectic of demythologising is the language of living faith'. (Dunn 1977:301).

  17. Double-layer optical fiber coating analysis using viscoelastic Sisko fluid as a coating material in a pressure-type coating die

    Science.gov (United States)

    Khan, Zeeshan; Islam, Saeed; Shah, Rehan Ali; Siddiqui, Nasir; Ullah, Murad; Khan, Wahab

    2017-11-01

    Double-layer optical fiber coating is performed using a melt polymer satisfying a Sisko fluid model in a pressure-type die. For this purpose, wet-on-wet coating process is applied. The assumption of fully developed flow of a Sisko fluid model, two-layer liquid flows of an immiscible fluid is modeled in an annular die of length L, where the bare glass fiber is dragged at a higher speed. The nonlinear governing equations are modeled and then solved by utilizing optimal homotopy asymptotic method (OHAM). The convergence of series solution is established. The convergence of OHAM is also verified by the Adomian decomposition method. In addition, the shear-thinning and shear-thickening characteristics of the non-Newtonian Sisko fluid are examined, and a comparison is made with the Newtonian fluid. At the end, the present work is also compared with the experimental results already available in the literature by taking the non-Newtonian parameter that tends to zero.

  18. Versatile composite resins simplifying the practice of restorative dentistry.

    Science.gov (United States)

    Margeas, Robert

    2014-01-01

    After decades of technical development and refinement, composite resins continue to simplify the practice of restorative dentistry, offering clinicians versatility, predictability, and enhanced physical properties. With a wide range of products available today, composite resins are a reliable, conservative, multi-functional restorative material option. As manufacturers strive to improve such properties as compression strength, flexural strength, elastic modulus, coefficient of thermal expansion, water sorption, and wear resistance, several classification systems of composite resins have been developed.

  19. Ultrasonic cleaning reduces the residual monomer in acrylic resins

    OpenAIRE

    Charasseangpaisarn, Taksid; Wiwatwarrapan, Chairat; Leklerssiriwong, Nonthida

    2016-01-01

    Background/purpose: The residual monomer remaining in acrylic resin can cause an allergic reaction and is toxic to oral soft tissue. This study determined the effect of the duration of ultrasonic cleaning on the amount of residual methyl methacrylate monomer in one heat-polymerized acrylic resin, Meliodent, and three autopolymerized acrylic resins, Unifast Trad Ivory, Unifast Trad Pink, and Unifast III. Materials and methods: Thirty-six disc-shaped specimens of each brand were prepared and...

  20. Die monopolievorming in die diamantontginningsnywerheid van Suid-Afrika

    Directory of Open Access Journals (Sweden)

    D. J. Viljoen

    1957-03-01

    Full Text Available Die diamantontginningsnywerheid is een van Suid-Afrika se oudste mynbouvertakkinge. Sedert die eerste diamant in 1867 aan die suidelike oewer van die Oranjerivier in die distrik Hopetown ontdek is, het ’n tydperk van ongeveer 91 jaar verloop, en gedurende hierdie tydperk het die diamantnywerheid baie veranderinge ondergaan.