Sample records for glass ionomer ketac

  1. Thermal properties of glass ionomer cement.

    PubMed

    Inoue, T; Saitoh, M; Nishiyama, M

    1993-12-01

    Five currently available glass ionomer cements (BASE CEMENT, DENTIN CEMENT, HY-BOND GLAS IONOMER-F, KETAC CEM, TOKUSO IONOMER) were studied with regard to the relationship between thermal properties and powder-liquid ratio (P/L ratio). The experiments were performed using five different P/L ratio of 0.8, 0.9, 1.0, 1.1 and 1.2 (P/L = 1.0: manufacturer's instruction) and measured with a xenon flash thermal-constant measuring device. Thermal diffusivity of the glass ionomer cements ranged from 0.212 to 0.303 x 10(-2) cm2 s-1; it increased according to the increase in the P/L ratio. The specific thermal capacity of the glass ionomer cements ranged from 1.011 to 1.369 Jg-1 K-1; it decreased with the increase in the P/L ratio. Thermal conductivity of the glass ionomer cements ranged from 0.505 to 0.712 Wm-1 K-1; it increased according to the increase in the P/L ratio. PMID:8158286

  2. Thermal characterization of glass ionomer/vinyl IPN composites

    SciTech Connect

    Puckett, A.D.; Bennett, B.; Shelby, A. [Univ. of Mississippi Medical Center, Jackson, MS (United States)] Storey, R. [Univ. of Southern Mississippi, Hattiesburg, MS (United States)

    1993-12-31

    In and attempt to improve some of the disadvantages of the conventional glass ionomers such as Ketac-fil, two photocurable glass ionomer restoratives have been introduced to the dental profession. The initial objective of this study was to compare the thermal expansion coefficients on the new formulations, Vari-Glass and Fuji II ionomer to the conventional glass ionomer composites using thermal mechanical analysis and to determine the residual monomer contents after photopolymerization using differential scanning calorimetry. Results suggest that these materials exhibit multiphase morphologies. Conventional glass ionomers exhibit two distinct glass transition temperatures. While Fuji II exhibits many of the characteristics of a conventional glass ionomer, Vari-Glass behaves more as a glass-filled resin composite. Fuji II and Ketac-fil exhibit expansion coefficients which are compatible with tooth structure below body temperature, but may cause significant stress on the bond to tooth structure due to shrinkage of the materials at temperatures slightly above body temperature. In contrast, the Vari-Glass formulation exhibits an expansion coefficient which is over three times that of tooth structure and will result in significant stresses above or below body temperature.

  3. Push-out bond strength of fiber posts to root dentin using glass ionomer and resin modified glass ionomer cements

    PubMed Central

    PEREIRA, Jefferson Ricardo; da ROSA, Ricardo Abreu; SÓ, Marcus Vinícius Reis; AFONSO, Daniele; KUGA, Milton Carlos; HONÓRIO, Heitor Marques; do VALLE, Accácio Lins; VIDOTTI, Hugo Alberto

    2014-01-01

    Objective The purpose of this study was to assess the push-out bond strength of glass fiber posts to root dentin after cementation with glass ionomer (GICs) and resin-modified glass ionomer cements (RMGICs). Material and Methods Fifty human maxillary canines were transversally sectioned at 15 mm from the apex. Canals were prepared with a step back technique until the application of a #55 K-file and filled. Post spaces were prepared and specimens were divided into five groups according to the cement used for post cementation: Luting & Lining Cement; Fuji II LC Improved; RelyX Luting; Ketac Cem; and Ionoseal. After cementation of the glass fiber posts, all roots were stored at 100% humidity until testing. For push-out test, 1-mm thick slices were produced. The push-out test was performed in a universal testing machine at a crosshead speed of 0.5 mm/minute and the values (MPa) were analyzed by Kolmogorov-Smirnov and Levene's tests and by two-way ANOVA and Tukey's post hoc test at a significance level of 5%. Results Fiber posts cemented using Luting & Lining Cement, Fuji II LC Improved, and Ketac Cem presented the highest bond strength to root dentin, followed by RelyX Luting. Ionoseal presented the lowest bond strength values (P>0.05). The post level did not influence the bond strength of fiber posts to root dentin (P=0.148). The major cause of failure was cohesive at the cement for all GICs and RMGICs. Conclusions Except for Ionoseal, all cements provided satisfactory bond strength values. PMID:25004052

  4. Glass-ionomers: bioactive implant materials

    Microsoft Academic Search

    I. M. Brook; P. V. Hatton

    1998-01-01

    Glass-ionomer cements (GICs) originally designed for use as dental materials have a number of advantages over acrylic bone cements. These include lack of exotherm during setting, absence of monomer and improved release of incorporated therapeutic agents; this has resulted in the development of GICs for biomedical applications. Major landmarks in this history are the formulation of defined-composition ionomer glasses and

  5. Response to thermal stimuli of glass ionomer cements

    Microsoft Academic Search

    Zhuoqun Yan; Sharanbir K. Sidhu; Thomas E. Carrick; John F. McCabe

    Objectives. This study was designed to determine the dimensional changes of glass ionomers caused by thermal stimuli under both dry and wet conditions. Methods. Eight cylindrical specimens (6 mm × 4 mm) were made (using a stainless steel mold) of each of the following materials: a conventional luting glass ionomer, two high viscosity restorative glass ionomers, a resin-modified glass ionomer

  6. A review of glass-ionomers: From conventional glass-ionomer to bioactive glass-ionomer.

    PubMed

    Khoroushi, Maryam; Keshani, Fateme

    2013-07-01

    Materials used in the body, especially the materials used in various oral cavity regions should be stable and passive without any interactions with the body tissues or fluids. Dental amalgam, composite resins and dental cements are the materials of choice with such properties. The first attempts to produce active materials, which could interact with the human body tissues and fluids were prompted by the concept that fluoride-releasing materials exert useful effects in the body. The concept of using the "smart" materials in dentistry has attracted a lot of attention in recent years. Conventional glass-ionomer (GI) cements have a large number of applications in dentistry. They are biocompatible with the dental pulp to some extent. GI is predominantly used as cements in dentistry; however, they have some disadvantages, the most important of which is lack of adequate strength and toughness. In an attempt to improve the mechanical properties of the conventional GI, resin-modified glass-ionomers have been marketed, with hydrophilic monomers, such as hydroxyethyl methacrylated (HEMA). Some recent studies have evaluated GI with bioactive glass in its structure to validate the claims that such a combination will improve tooth bioactivity, regeneration capacity and restoration. There is ever-increasing interest in the application of bioactive materials in the dental field in an attempt to remineralize affected dentin. The aim of this review article is to evaluate these materials and their characteristics and applications. PMID:24130573

  7. Comparative wear resistance of reinforced glass ionomer restorative materials.

    PubMed

    Yap, A U; Teo, J C; Teoh, S H

    2001-01-01

    This study investigated the wear resistance of three restorative reinforced glass ionomer cements (Fuji IX GP FAST [FJ], Miracle Mix [MM] and Ketac Silver [KS]). Microfilled (Silux [SX]) and mini-filled (Z100 [ZO]) composites were used for comparison. Six specimens were made for each material. The specimens were conditioned for one week in distilled water at 37 degrees C and subjected to wear testing at 20 MPa contact stress against SS304 counterbodies using a reciprocal compression-sliding wear instrumentation. Distilled water was used as lubricant. Wear depth (microm) was measured using profilometry every 2,000 cycles up to 10,000 cycles. Results were analyzed using ANOVA/Scheffe's test (p<0.05). After 10,000 cycles of wear testing, ranking was as follows: KS>ZO>MM>FJ>SX. Wear ranged from 26.1 microm for SX to 71.5 microm for KS. The wear resistance of KS was significantly lower than FJ, MM and SX at all wear intervals. Although KS had significantly more wear than ZO at 2,000 to 6,000 cycles, no significant difference in wear was observed between these two materials at 8,000 and 10,000 cycles. Sintering of silver particles to glass ionomer cement (KS) did not appear to improve wear resistance. The simple addition of amalgam alloy to glass ionomer may improve wear resistance but results in poor aesthetics (silver-black color). FJ, which relies on improved chemistry instead of metal fillers, showed comparable wear resistance to the composites evaluated and is tooth-colored. It may serve as a potential substitute for composites in low-stress situations where fluoride release is desirable and aesthetic requirements are not high. PMID:11504433

  8. Glass-ionomer cements as adhesives

    Microsoft Academic Search

    A. O. Akinmade; J. W. Nicholson

    1993-01-01

    The literature on the clinical use of glass-ionomer cements is reviewed, and this shows that these materials are successful partly because of the good adhesion they exhibit towards a variety of substrates encountered in dentistry. The reasons for this good adhesion are identified as the good initial wetting of the surfaces met in clinical dentistry, the development of strong chemical

  9. Microleakage on Class V glass ionomer restorations after cavity preparation with aluminum oxide air abrasion.

    PubMed

    Corona, Silmara Aparecida Milori; Borsatto, Maria Cristina; Rocha, Renata Andréa Salvitti de Sá; Palma-Dibb, Regina Guenka

    2005-01-01

    This in vitro study assessed the marginal microleakage on class V cavities prepared with aluminum oxide air abrasion and restored with different glass ionomer cements. The cavities were prepared on the buccal and lingual surfaces of 15 sound third molars with an air- abrasion device (Kreativ Mach 4.1; New Image) using a 27.5-microm aluminum oxide particle stream, and were assigned to 3 groups of 10 cavities each. The restorative materials were: group I, a conventional glass ionomer cement (Ketac-Fil); groups II and III, resin-modified glass ionomer cements (Vitremer R and Fuji II LC, respectively). After placement of the restorations, the teeth were stored in distilled water at 37 degrees C for 24 h, polished and then submitted to a thermocycling regimen of 500 cycles, isolated, immersed in 0.2% Rhodamine B solution for 24 h, included and serially sectioned. Microleakage was assessed by viewing the specimens under an optical microscope connected to a color video camera and a computer. The images obtained were digitized and analyzed for microleakage using software that allows for a standard quantitative assessment of dye penetration in millimeters. Statistical analysis was done using the Kruskall-Wallis and Wilcoxon tests. Means of dye penetration (%) were: occlusal - I: 25.76 +/- 34.35, II: 20.00 +/- 42.16, III: 28.25 +/- 41.67; cervical - I: 23.72 +/- 41.84; II: 44.22 +/- 49.69, III: 39.27 +/- 50.74. No statistically significant differences (p>0.05) were observed among either the glass ionomer cements or the margins. In conclusion, class V cavities restored with either conventional or resin-modified glass ionomer cements after preparation with aluminum oxide air abrasion did not show complete sealing at the enamel and dentin/cementum margins. PMID:16113931

  10. Biaxial Flexural Strength of High-Viscosity Glass-Ionomer Cements Heat-Cured with an LED Lamp during Setting

    PubMed Central

    Fabián Molina, Gustavo; Cabral, Ricardo Juan; Mazzola, Ignacio; Brain Lascano, Laura; Frencken, Jo E.

    2013-01-01

    Adding heat to glass ionomers during setting might improve mechanical properties. The aim was to compare the biaxial flexural strength (BFS) between and within four glass ionomers, by time of exposure to a high-intensity LED light-curing unit. Materials and methods. Samples of Fuji 9 Gold Label, Ketac Molar Easymix, ChemFil Rock, and the EQUIA system were divided into three treatment groups (n = 30): without heating (Group 1), heated with LED lamp of 1400?mW/cm2 for 30?s while setting (Group 2), and heated with LED lamp of 1400?mW/cm2 for 60?s while setting (Group 3). Samples were stored for 48 hours in distilled water at 37°C until tested. BFS was tested, using a universal testing machine at a crosshead speed of 1?mm/min. Data were analyzed, using ANOVA test with the Bonferroni correction (? = 0.05). Heating the glass-ionomer cements with an LED curing light of 1400?mW/cm2 during setting for 30?s increased the BFS value of all GICs. No statistically significant difference in mean BFS scores was found between the EQUIA system and ChemFil Rock at 30?s and 60?s. The mean BFS value was statistically significantly higher for the EQUIA system and ChemFil Rock than for Fuji 9 Gold Label and Ketac Molar Easymix at all exposure times. PMID:23841095

  11. Comparative evaluation of microleakage of nano-filled resin-modified glass ionomer: An in vitro study

    PubMed Central

    Eronat, Nesrin; Yilmaz, Emir; Kara, Nazan; Topaloglu, Ak Asli

    2014-01-01

    Objective: This in vitro study evaluated the microleakage of a nano-filled resin-modified glass ionomer and a high viscosity glass-ionomer restorations in class V cavities. Materials and Methods: Thirty-two class V cavities prepared on the buccal and lingual surfaces of 16 sound, third molar teeth were randomly assigned into two groups and restored by one of the glass ionomer material; Group A: A high viscosity (Ketac Molar, 3M ESPE) Group B: A nano-filled resin-modified (Ketac N100, 3M ESPE) glass ionomer. One clinician prepared all the cavities. The materials were used according to the manufacturers’ recommendations. The restored teeth were then stored in distilled water at 37°C for 24 h, thermocycled at 5-55°C for 1000 cycles. The specimens were immersed in aqueous solution of Indian ink dye for 48 h at room temperature. They were embedded in resin polyester and sectioned longitudinally in a buccolingual direction. Microleakage was assessed according to the depth of dye penetration along the restoration. The extent of dye penetration at the occlusal and gingival margins was assessed using a stereo microscope. Randomly selected samples from each group were prepared for scanning electron microscope evaluation. The data were statistically analyzed with Friedman and Wilcoxon signed ranks tests. Results: There were statistically significant differences between the microleakage scores of the two groups for both occlusal and gingival scores (P = 0.001). Occlusal and gingival scores for high viscosity glass ionomer (P = 0.024) and nanoionomer (P = 0.021) using Wilcoxon signed ranks tests showed statistically significant differences. High viscosity glass ionomer showed significantly less microleakage compared to the nano-filled resin-modified glass-ionomer (RMGIs) at occlusal margin (P = 0.001). No significant differences were found between the groups at gingival margin (P = 0.0317). Conclusion: Within the limitations of this in vitro study, nano-filled RMGIs restorations did not perform better than high viscosity glass ionomer in class V cavities in terms of microleakage assessment. PMID:25512723

  12. The influence of microstructure on thermal response of glass ionomers

    Microsoft Academic Search

    Zhuoqun Yan; Sharanbir K. Sidhu; John F. McCabe

    2007-01-01

    This study was designed to determine the dimensional changes caused by thermal stimuli of glass ionomers with different glass\\/matrix\\u000a ratios. Four cylindrical specimens were made for each of four powder\\/liquid ratios (3:1, 2.5:1, 2:1 and 1.5:1) for a conventional\\u000a luting glass ionomer, two high viscosity restorative glass ionomers and a restorative resin-modified glass ionomer. The thermal\\u000a characteristics were determined using

  13. Glass ionomer as fissure sealant--a critical review.

    PubMed

    Simonsen, R J

    1996-01-01

    This paper presents a review of the literature on glass ionomer cements used as fissure sealants. An objective assessment of the presently available scientific literature on the use of glass ionomer materials as pit and fissure sealants is not encouraging in terms of retention, but appears somewhat more positive for caries prevention. At the time of this writing, the published literature indicates that retention for resin-based sealants is better than for glass ionomer sealants, but differences in caries prevention remain equivocal. Future research should concentrate on assessing the effects of fluoride-releasing, resin-modified, glass ionomer materials. PMID:8915960

  14. Influence of citric acid on the surface texture of glass ionomer restorative materials

    PubMed Central

    Reddy, Dappili Swami Ranga; Kumar, Ramachandran Anil; Venkatesan, Sokkalingam Mothilal; Narayan, Gopal Shankar; Duraivel, Dasarathan; Indra, Rajamani

    2014-01-01

    Aim: This study determined the effectiveness of G-coat plus surface protective agent over petroleum jelly on the surface texture of conventional Glass ionomer restorative materials. Materials and Methods: Three chemically cured conventional glass ionomer restorative materials type II, type IX and ketac molar were evaluated in this study. Sixty specimens were made for each restorative material. They were divided into two groups of thirty specimens each. Of the sixty specimens, thirty were coated with G-coat plus (a nano-filler coating) and the rest with petroleum jelly. Thirty samples of both protective coating agents were randomly divided into six groups of five specimens and conditioned in citric acid solutions of differing pH (pH 2, 3, 4, 5, 6 & 7). Each specimen was kept in citric acid for three hours a day, and the rest of time stored in salivary substitute. This procedure was repeated for 8 days. After conditioning, the surface roughness (Ra, ?m) of each specimen was measured using a surface profilometer (Taylor & Habson, UK). Data was analyzed using one-way analysis of variance (ANOVA) and Tukey's HSD test at a significance level of 0.05. Results: The surface textures of all the tested glass ionomer restorative materials protected with G-coat plus were not significantly affected by acids at low pH. The surface textures of all the tested glass ionomer restorative materials protected with petroleum jelly coating were significantly affected by acids at low pH. Conclusion: The effects of pH on the surface texture of glass ionomer restoratives are material dependent. Among all the materials tested the surface texture of Type II GIC (Group I) revealed marked deterioration when conditioned in solutions of low pH and was statistically significant. Hence, a protective coating either with G-coat plus or with light polymerized low viscosity unfilled resin adhesives is mandatory for all the glass ionomer restorations to increase the wear resistance of the restorative materials. PMID:25298643

  15. Devitrification of ionomer glass and its effect on the in vitro biocompatibility of glass-ionomer cements.

    PubMed

    Hurrell-Gillingham, K; Reaney, I M; Miller, C A; Crawford, A; Hatton, P V

    2003-08-01

    The effects of devitrification of an ionomer glass with a molar composition 4.5SiO(2).3Al(2)O(3).1.5P(2)O(5).3CaO.2CaF(2) on cement formation and in vitro biocompatibility were investigated. Differential thermal analysis was used to study the phase evolution in the glass, and to determine the heat treatments for production of glass-ceramics. X-ray diffraction patterns from glass frit heat-treated at 750 degrees C for 2h contained peaks corresponding to apatite (JCPDS 15-876), whereas for samples heat-treated at 950 degrees C for 2h apatite and mullite (JCPDS 15-776) were the major phases detected. Transmission electron microscopy (TEM) confirmed that apatite and apatite-mullite phases were present after heat treatments at 750 degrees C and 950 degrees C respectively. Glass and glass-ceramics were ground to prepare <45microm powders and glass ionomer cements were produced using a ratio of 1g powder: 0.2g PAA: 0.3g 10% m/v tartaric acid solution in water. In vitro biocompatibility was evaluated using cultured rat osteosarcoma (ROS) cells. Scanning electron microscopy (SEM) showed that cells colonised the surfaces of cements prepared using untreated ionomer glass and glass crystallised to form apatite (750 degrees C/2h). However, quantitative evaluation using MTT and total protein assays indicated that more cell growth occurred in the presence of cements prepared using ionomer glasses crystallised to apatite than cements prepared using untreated glass. The least cell growth and respiratory activity was observed on cements made with crystallised glass containing both apatite and mullite. It was concluded that the controlled devitrification of ionomer glasses could be used to produce GIC bone cements with improved biocompatibility. PMID:12895588

  16. Bonding ability of paste-paste glass ionomer systems to tooth structure: in vitro studies.

    PubMed

    Cook, N B; Feitosa, S A; Patel, A; Alfawaz, Y; Eckert, G J; Bottino, M C

    2015-01-01

    This study investigated the effect of nonrinse conditioners (ie, Ketac Nano Primer [KNP] and GC Self Conditioner [SC]) used as substrate pretreatment and their respective paste-paste resin-modified glass-ionomer cement (RMGIC) (ie, Ketac Nano [KN] and Fuji Filling LC [FF]) on microtensile bond strength to dentin and marginal sealing when compared with traditional RMGIC (ie, Photac Fil [PF] and Fuji II LC [FII]) used in association with polyacrylic acid (ie, Ketac Cavity Conditioner [KC] and GC Cavity Conditioner [CC]). A total of 192 extracted human molars were allocated into eight groups: KNP-KN, KC-KN, KNP-PF, KC-PF, SC-FF, CC-FF, SC-FII, and CC-FII. For microtensile bond strength, the teeth were sectioned to expose occlusal dentin and restored according to the group. After 24 hours the teeth were cut to yield nine beams per tooth (±0.8 mm(2)). Testing was done using a universal testing machine followed by failure mode classification. For microleakage testing, standardized cavity preparations were made on the buccal cementoenamel junction and restored according to the group. The teeth were thermocycled (500 cycles, 8°C to 48°C), sealed, immersed in methylene blue for 24 hours, and then assessed for microleakage using a stereomicroscope. Microtensile bond strengths in megapascals (mean±SE) were KNP-KN: 14.9 ± 1.6, KC-KN: 17.2 ± 1.5, KNP-PF: 31.2 ± 1.6, KC-PF: 26.2 ± 1.2, SC-FF: 23.6 ± 1.5, SC-FII: 31.2 ± 1.5, and CC-FII: 21.9 ± 1.5. Cervical margins showed more microleakage compared with occlusal margins. Overall, the use of nonrinse conditioners in association with traditional RMGICs demonstrated superior microtensile bond strengths to dentin when compared with the paste-paste RMGICs. Meanwhile, the association between polyacrylic acid (CC) and a traditional RMGIC (FII) led to the least microleakage for cervical locations when compared with all other groups. PMID:25535780

  17. Creep behavior of glass-ionomer restorative materials.

    PubMed

    Papadogiannis, Y; Helvatjoglou-Antoniadi, M; Lakes, R C; Sapountjis, M

    1991-01-01

    The creep of microspecimens of five glass-ionomer filling materials and one glass-ionomer-cermet cement was studied by means of a torsional creep apparatus. The glass-ionomer specimens were aged one week and conditioned in 37 degrees C water. Shear stress of 2.47 x 10(-4) N.m was maintained for three h, and recovery was followed for 50 h. Creep curves were obtained at 21, 37, and 50 degrees C. The effect of temperature increase was studied. All the glass ionomers exhibited linear visco-elastic behavior at low deformations. Their shear moduli and resistance to creep were similar to those of some composites measured by the same method. The increase of temperature influenced the creep behavior and moduli of the materials (i.e., increased creep and residual strains and decreased shear modulus). Although the applied torque was very small, there was permanent deformation, the result of viscous flow in all experiments which was more pronounced at 50 degrees C. PMID:1901812

  18. Advanced antibacterial glass ionomer cements for improved dental restoratives

    Microsoft Academic Search

    Yiming Weng

    2011-01-01

    Secondary caries that often occurs at the interface between the restoration and the cavity preparation is mainly caused by demineralization of tooth structure due to invasion of plaque bacteria (acid-producing bacteria) such as Streptococcus mutans (S. mutans) in the presence of fermentable carbohydrates. Although glass-ionomer cements (GICs) are found to be the most cariostatic and somehow antibacterial due to release

  19. Resin-modified glass ionomers for luting posterior ceramic restorations

    Microsoft Academic Search

    Birger Thonemann; Marianne Federlin; Gottfried Schmalz; Karl-Anton Hiller

    1995-01-01

    Objectives. Until recently, esthetic inlay restorations in posterior teeth have been limited to cavities surrounded by enamel. Dentin adhesive systems in combination with luting composites and light-cured resin-modified glass ionomer cements offer a possibility for bonding ceramic inlays to cavities when the cervical margin is in dentin. This study was designed to compare in vitro marginal integrity of ceramic inlays

  20. Microleakage of glass ionomer/composite laminate Class V restorations.

    PubMed

    McInnes, P; Perkins, E; Weinberg, R

    1990-02-01

    The aim of this investigation was to evaluate the effects on microleakage of pretreating dentin with polyacrylic acid (PAA), prior to placing a glass ionomer base/composite laminate restoration. Class V erosion-type lesions with the incisal margin on enamel and the cervical margin below the cemento-enamel junction (CEJ), were prepared in 50 sound extracted teeth. These teeth were divided into five dentin treatment groups: A) 10% PAA; B) 20% PAA; C) and D) 40% PAA; E) no dentin preconditioning. In groups A, B, C and E, a glass ionomer base was placed within 1 mm of the margins. In group D the glass ionomer base extended to the cervical margin. The glass ionomer base and the incisal enamel were etched with 37% phosphoric acid prior to placing a bonding agent and restoring with a composite. The restorations were finished and polished and the teeth were stored in distilled water at 37 degrees C for 7 days. They were thermocycled in 0.5% fuchsin dye for 500 cycles (5 degrees C to 60 degrees C), embedded in epoxy resin, and sectioned at 250 mu intervals through the restorations. The section of each tooth exhibiting the most severe dye penetration along the tooth/restoration interface was evaluated and scored both incisally and cervically: 0 = no leakage; 1 = leakage up to the glass ionomer base; 2 = leakage up to 1/2 the wall length; 3 = leakage exceeding 1/2 the wall length. Cervically, the median leakage for all groups was 3.0. Incisally, the median leakage for all the groups was 0.0.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2375848

  1. Evaluation on Shear Bond Strength of Different Glass Ionomer and Hydroxy Apatite Cements Used in Ossiculoplasty

    PubMed Central

    Kalc?o?lu, M. Tayyar; Uzun, ?smail Hakk?; Yalç?n, Muhammet; Malkoç, Meral Arslan; Ö?reten, Ay?e Tuba; Hanege, Fatih Mehmet

    2015-01-01

    Background: Glass ionomer cements (GIC) have been widely used in dentistry for many years. In recent years, GIC have also been used for ossiculoplasty. The bond strength of GIC used in ossiculoplasty and the way they may change over the years in the cementation area are being questioned. The bonding strength of the substance may be of importance for long-term outcomes. Aims: The aim of this study was to investigate the bond strength of different GIC on ossicles. Study Design: In vitro study. Methods: Twenty ossicles were obtained from patients who had undergone ear surgery. All specimens were randomly divided into four subgroups. All specimens were inserted into a specially designed apparatus for shear bond strength (SBS) testing. The tested materials [Aqua Meron (AM), Aqua Cem (AC), Ketac Cem (KC), and Otomimix CPB (OH)] were prepared and applied according to the manufacturer’s instructions. The SBS was tested using a universal testing machine at a crosshead speed of 0.5 mm/min. Results: The mean SBSs were found to be 13.28 MPa, 23.43 MPa, 8.51MPa, and 1.78 MPa for AM, AC, KC, and OH, respectively. AC had the highest SBS, which was statistically significantly different from that of KC and OH (p<0.05). Both AM and KC had higher SBS than OH (p<0.05). Conclusion: The results obtained in this study by investigating the bone-bonding strength of cements widely used in ossiculoplasty demonstrate that some of these substances have a greater ability to bond to ossicles compared to others. Further clinical investigations are needed to test different parameters. PMID:25759768

  2. Release of sodium fusidate from glass-ionomer dental cement.

    PubMed

    Mulla, Zoheb; Edwards, Mark; Nicholson, John W

    2010-06-01

    Restorative grade glass-ionomer cement has been studied for its potential as a controlled release material for the antimicrobial compound sodium fusidate. Sodium fusidate powder was incorporated into the cement at the mixing stage at levels of 1% and 5% by mass, and disc shaped specimens (6 mm diameter x 2 mm depth) prepared. After curing for 1 hour at 37 degrees C, specimens were placed in water and release of sodium fusidate at set time intervals determined using reverse-phase HPLC. Sets of five specimens were used in all experiments. Early release of sodium fusidate was shown to occur by diffusion for each level of addition, as shown by M(t)/M(infinity) being linear with respect to [square root]time in both cases. Diffusion coefficients were calculated as 4.4 x 10(-8) cm(2) s(-1) and 3.0 x 10(-8) cm(2) s(-1) for 1 and 5% respectively. These were an order of magnitude lower than had been found previously for water transport in glass-ionomer cements, a result that is attributed to the greater size of the sodium fusidate molecule compared with that of water. Cements released 20.4 and 22.8% respectively of the total sodium fusidate added after 2 weeks, values which were not significantly different from each other, and which exceeded total release previously reported for benzalkonium chloride and chlorhexidine. PMID:20376540

  3. Adhesive properties of modified glass-ionomer cements.

    PubMed

    Rusz, J E; Antonucci, J M; Eichmiller, F; Anderson, M H

    1992-01-01

    The incorporation of water-soluble polymers and/or vinyl monomers into glass-ionomer cements can yield toughened "hybrid cement-composites". This study compared a commercial water-hardening glass-ionomer cement and seven experimental hybrids in their bonding to both dentin and Silar composite. The cements were sanded and phosphoric-acid-etched or left with an unaltered matrix-formed surface when adhesion to composite was tested. The seven hybrids included: 15% 2-hydroxyethyl methacrylate (HEMA) with appropriate initiators/activators, 29% HEMA, 27% HEMA + 0.5% polyacrylic acid (PAA), 0.5% PAA, 1.5% PAA, 2.5% polyvinyl alcohol, and 2.5% gelatin. Acceptable bond strengths to applied composite and to dentin were observed for most of the modified hybrid cements. There were higher bond strengths with composite when the hybrids were left unetched. Bonding of some unetched, HEMA-containing cements achieved bond strengths (29% HEMA, 10.09 MPa) significantly higher than those of the unmodified cement (4.92 MPa). Resin-modified cements may promote better bonding by improved interaction and compatibility with the resin component of the composite. PMID:1387853

  4. A preliminary clinical trial using flowable glass-ionomer cement as a liner in proximal-ART restorations: The operator effect

    PubMed Central

    Hesse, Daniela; Bönecker, Marcelo; Van Loveren, Cor; Van Amerongen, W E.; Raggio, Daniela P.

    2013-01-01

    Objectives: This in vivo study was carried out to assess the influence of the operator experience on the survival rate of proximal-ART restorations using a two-layer technique to insert the glass-ionomer cement (GIC). Study Design: Forty five proximal cavities in primary molars were restored in a school setting according to the ART technique. The cavities were restored by two operators with Ketac Molar Easymix, and received a flowable layer of GIC prior to a second GIC layer with a regular consistency. The operators had different clinical experiences with ART (no experience or two years of experience), but both completed a one-week training to perform the restorations and the GIC mixing in this study. Results: After a 12-month follow-up, 74% of the restorations survived; the main reason for failure was bulk fracture or total loss of the restoration.There was no operator influence (log-rank test p=0.2) Conclusion: The results encourage future well designed controlled clinical trials using the two-layer technique for insertion of GIC in proximal-ART restorations, after training the operators. Key words:Atraumatic Restorative Treatment (ART), Glass-ionomer, proximal restorations. PMID:23524424

  5. Bonding of contemporary glass ionomer cements to different tooth substrates; microshear bond strength and scanning electron microscope study

    PubMed Central

    El Wakeel, Aliaa Mohamed; Elkassas, Dina Wafik; Yousry, Mai Mahmoud

    2015-01-01

    Objective: This study was conducted to evaluate the microshear bond strength (?SBS) and ultramorphological characterization of glass ionomer (GI) cements; conventional GI cement (Fuji IX, CGI), resin modified GI (Fuji II LC, RMGI) and nano-ionomer (Ketac N100, NI) to enamel, dentin and cementum substrates. Materials and Methods: Forty-five lower molars were sectioned above the cemento-enamel junction. The occlusal surfaces were ground flat to obtain enamel and dentin substrates, meanwhile the cervical one-third of the root portion were utilized to evaluate the bonding efficacy to cementum substrate. Each substrate received microcylinders from the three tested materials; which were applied according to manufacturer instructions. ?SBS was assessed using a universal testing machine. The data were analyzed using two-way analysis of variance (ANOVA) and Tukey's post-hoc test. Modes of failure were examined using stereomicroscope at ×25 magnification. Interfacial analysis of the bonded specimens was carried out using environmental field emission scanning electron microscope. Results: Two-way ANOVA revealed that materials, substrates and their interaction had a statistically significant effect on the mean ?SBS values at P values; ?0.0001, 0.0108 and 0.0037 respectively. RMGI showed statistically significant the highest ?SBS values to all examined tooth substrates. CGI and RMGI show substrate independent bonding efficiency, meanwhile; NI showed higher ?SBS values to dentin and cementum compared to enamel. Conclusion: Despite technological development of GI materials, mainly the nano-particles use, better results have not been achieved for both investigations, when compared to RMGI, independent of tooth substrate.

  6. In-vitro study of resin-modified glass ionomer cements for cementation of orthodontic bands. Isolation, surplus removal and humidity as factors influencing the bond strength between enamel, cement and metal.

    PubMed

    Liebmann, S M; Jost-Brinkmann, P G

    1999-01-01

    The aim of this in vitro study was to investigate different light-cured and chemically cured resin-modified glass ionomer cements used for the cementation of orthodontic bands and to analyze various factors influencing the adhesive strength between enamel, cement and stainless steel. Four resin-modified glass ionomers (Fuji Ortho LC/GC, Fuji Duet/GC, Unitek Multi-Cure Glass Ionomer Orthodontic Band Cement/3M Unitek, Vitremer/3M) and 1 compomer (Band-Lok/Reliance) were examined. Flattened and polished bovine teeth embedded in polyurethane resin were used as enamel specimens. Before cementation, 50% of the specimens were moistened with the aerosol of an inhalation device, while the rest were dried with compressed air. Stainless steel cylinders (CrNi 18 10) were perpendicularly bonded onto the polished enamel using a custom-made cementation device and immediately topped with a pressure of 0.25 MPa. The cement was isolated with either Ketac Glaze/ESPE, Fuji Coat/GC, Cacao Butter/GC, Dryfoil/Jalenko or Final Varnish/VOCO, or was left uncoated. Eight minutes after the beginning of mixing, either the surplus cement was removed with a scalpel or surplus removal was simulated with ultrasound. After 24 hours storage in a water bath at 37 degrees C and 1,000 thermocycles the shear bond strength was determined. Significant differences with respect to the shear bond strength were found among the following cements, ranking from highest to lowest: Fuji Duet, Unitek cement > Fuji Ortho LC > Vitremer > Band-Lok. The application of a barrier coating significantly increased the shear bond strength of all cements except Fuji Ortho LC. The light-cured resin Ketac Glaze proved to be the most effective barrier coating. A dry enamel surface increased the bond strength of all investigated cements except Unitek cement. The use of ultrasound led to no significant reduction in shear bond strength in comparison with surplus removal with a scalpel. PMID:10546417

  7. Fluoride release and bioactivity evaluation of glass ionomer: Forsterite nanocomposite

    PubMed Central

    Sayyedan, Fatemeh Sadat; Fathi, Mohammadhossein; Edris, Hossein; Doostmohammadi, Ali; Mortazavi, Vajihesadat; Shirani, Farzaneh

    2013-01-01

    Background: The most important limitation of glass ionomer cements (GICs) is the weak mechanical properties. Our previous research showed that higher mechanical properties could be achieved by addition of forsterite (Mg2SiO4) nanoparticles to ceramic part of GIC. The objective of the present study was to fabricate a glass ionomer- Mg2SiO4 nanocomposite and to evaluate the effect of addition of Mg2SiO4 nanoparticles on bioactivity and fluoride release behavior of prepared nanocomposite. Materials and Methods: Forsterite nanoparticles were made by sol-gel process. X-ray diffraction (XRD) technique was used in order to phase structure characterization and determination of grain size of Mg2SiO4 nanopowder. Nanocomposite was fabricated via adding 3wt.% of Mg2SiO4 nanoparticles to ceramic part of commercial GIC (Fuji II GC). Fluoride ion release and bioactivity of nanocomposite were measured using the artificial saliva and simulated body fluid (SBF), respectively. Bioactivity of specimens was investigated by Fourier transitioned-infrared spectroscopy (FTIR), scanning electronmicroscopy (SEM), Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and registration of the changes in pH of soaking solution at the soaking period. Statistical analysis was carried out by one Way analysis of variance and differences were considered significant if P < 0.05. Results: The results of XRD analysis confirmed that nanocrystalline and pure Mg2SiO4 powder was obtained. Fluoride ion release evaluation showed that the values of released fluoride ions from nanocomposite are somewhat less than Fuji II GC. SEM images, pH changes of the SBF and results of the ICP-OES and FTIR tests confirmed the bioactivity of the nanocomposite. Statistical analysis showed that the differences between the results of all groups were significant (P < 0.05). Conclusion: Glass ionomer- Mg2SiO4 nanocomposite could be a good candidate for dentistry and orthopedic applications, through of desirable fluoride ion release and bioactivity. PMID:24130579

  8. Therapeutic effect of glass-ionomers: an overview of evidence.

    PubMed

    Mickenautsch, S; Mount, G; Yengopal, V

    2011-03-01

    The requirements for an ideal restorative material include adhesion to tooth structure (enamel and dentine) and an ability to withstand the traumas of occlusion. However, some level of an anticaries effect is also desirable. After a long history of glass-ionomer cement (GIC) development, an evidence base in support of the therapeutic effect of GIC, particularly with regard to its anticaries effect, is emerging. This evidence is increasingly presented through systematic reviews of clinical GIC application and, to a certain extent, relates to a caries-preventive effect of the material itself. However, the strength of evidence supporting other aspects of GIC, such as a higher remineralizing effect, fluoride uptake in hard tooth tissue and fluoride release of GIC, is limited. Nevertheless, the results of these in situ and laboratory trials provide valuable insights into factors that facilitate understanding of the clinical efficacy of GIC. PMID:21332735

  9. Interaction of glass-ionomer cements with moist dentin.

    PubMed

    Yiu, C K Y; Tay, F R; King, N M; Pashley, D H; Sidhu, S K; Neo, J C L; Toledano, M; Wong, S L

    2004-04-01

    Glass-ionomer cements (GICs) are regarded as aqueous gels made up of polyalkenoic acid salts containing ion-leachable glass fillers. The consequence of water permeation across the GIC-dentin interface is unknown. This study used SEM, field-emission/environmental SEM (FE-ESEM), and TEM to examine the ultrastructure of GIC-bonded moist dentin. Dentin surfaces bonded with 6 auto-cured GICs were examined along the fractured GIC-dentin interfaces. Additional specimens fractured 3 mm away from the interfaces were used as controls. SEM revealed spherical bodies along GIC-dentin interfaces that resembled hollow eggshells. FE-SEM depicted similar bodies with additional solid cores. Energy-dispersive x-ray analysis and TEM showed that the spherical bodies consisted of a silicon-rich GIC phase that was absent from the air-voids in the controls. The GIC inclusions near dentin surfaces result from a continuation of the GI reaction, within air-voids of the original polyalkenoate matrix, that occurred upon water diffusion from moist dentin. PMID:15044500

  10. A novel antibacterial dental glass-ionomer cement.

    PubMed

    Weng, Yiming; Guo, Xia; Gregory, Richard; Xie, Dong

    2010-10-01

    This study reports the synthesis and evaluation of a novel non-leachable poly(quaternary ammonium salt) (PQAS)-containing antibacterial glass-ionomer cement. Fuji II LC cement was used for comparison. Compressive strength (CS) and Streptococcus mutans viability were used to evaluate strength and antibacterial activity, respectively. All specimens were conditioned in distilled water at 37 degrees C before testing. After the addition of 1-30% PQAS, both cements showed a reduction in CS, of 25-95% for Fuji II LC and 13-78% for the experimental cement, and a reduction in S. mutans viability, of 40-79% for Fuji II LC and 40-91% for the experimental cement. The experimental cement showed less CS reduction and higher antibacterial activity compared with Fuji II LC. The result also indicates that the cements are permanently antibacterial, with no leaching of PQAS. It appears that the experimental cement is a clinically attractive dental restorative that can be potentially used for longlasting restorations as a result of its high mechanical strength and permanent antibacterial function. PMID:20853548

  11. Assessment of coronal leakage in teeth root filled with gutta-percha and a glass of ionomer root canal sealer.

    PubMed

    Tidswell, H E; Saunders, E M; Saunders, W P

    1994-07-01

    The effect on coronal leakage of the use of either a single gutta-percha cone or cold lateral condensation of gutta-percha, with a glass ionomer sealer cement was studied. In addition, the effect of the removal of the smear layer was also determined. Eighty-eight single-rooted teeth were prepared chemomechanically using hand files, with the balanced force technique. Lubrication was provided by either Hibiscrub (maintaining the smear layer) or an EDTA-containing paste (to remove the smear layer). Copious irrigation was carried out with 2.2% sodium hypochlorite. The teeth were allocated randomly to four groups of 20 teeth each, the remaining eight teeth served as controls. Two groups of teeth, one with and one without smear layer, were obturated with either a single gutta-percha cone or cold laterally condensed gutta-percha, with Ketac Endo as the sealer. The teeth were stored for 6 weeks, thermocycled, and the extent of coronal leakage determined for each group after immersion in India ink for 90 h. The teeth were demineralized, dehydrated and immersed in methyl salicylate, which rendered them transparent. Linear measurement of maximum dye penetration was recorded. The mean depth (+SD) of leakage for the groups in which the smear layer was left intact was 1.68 mm (+0.38) for the single cone (A1) and 2.29 mm (+1.58) for lateral condensation (B1). When the smear layer was removed the mean depth of leakage for the single cone group (A2) was 2.04 mm (+0.73) and 2.37 mm (+1.70) for the laterally condensed group (B2). There was no significant difference in coronal leakage between the groups (P > 0.05). PMID:7814130

  12. Influence of endodontic materials on the bonding of glass ionomer cement to dentin.

    PubMed

    Capurro, M A; Herrera, C L; Macchi, R L

    1993-04-01

    We assessed the bond strength of a glass ionomer cement to dentin that had been in contact with different materials. Flat dentin surfaces in freshly extracted human teeth were covered for 48 h with a 1 mm layer of a variety of materials that are used for temporary filling or root canal sealing. The products were mechanically removed and a glass ionomer cement cylindrical specimen bonded to the dentin surface. After 7-days immersion in 37 degrees C water the tensile bond strength was tested. The results were compared with those on dentin surfaces not in contact with any endodontic material. The statistical analysis showed that none of the materials used interfered with the bonding of the glass ionomer to dentin. PMID:8404700

  13. Caries protection after orthodontic band cementation with glass ionomer.

    PubMed

    Marcushamer, M; Garcia-Godoy, F; Chan, D C

    1993-01-01

    This study evaluated the resistance of the enamel to an artificial caries challenge after removing orthodontic bands cemented with a glass ionomer cement (GIC). Ten extracted caries-free molars were cleaned with a slurry of pumice and randomly divided into 2 groups of 5 teeth each: Group 1: Cementation with GIC (Fuji) and Group 2: Cementation with a zinc phosphate cement (Mizzy). Both cements were handled according to manufacturer's instructions. Before cementing the bands, an area of S x S mm was masked with adhesive tape on the lingual surfaces of all teeth. The orthodontic bands were cemented over this adhesive tape. After band cementation, the occlusal and gingival margins of the band were delineated with a bur on the tooth surface. The teeth were thermocycled (200 cycles, 5-55 degrees C, 30-second dwell time) and stored in distilled water for 24 hours. Then, the bands and adhesive tape were removed and the teeth again stored in distilled water for a week, changing the water daily. The teeth were then varnished with the exception of a 5 x 5 mm window (including previously exposed and covered areas) on the buccal and lingual surfaces. All teeth were then placed in an acidified gel (pH 4.5) for 5 weeks to produce artificial caries. At least three sections from the exposed and covered areas were made from the buccal and lingual challenged areas. Sections were ground to approximately 100 microns. Polarized microscopy and image analysis were used to analyze the results.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8258573

  14. Ultrastructural study of a glass ionomer-based, all-in-one adhesive

    Microsoft Academic Search

    Franklin R. Tay; Hidehiko Sano; Junji Tagami; Masanori Hashimoto; Keith M. Moulding; Cynthia Yiu; David H. Pashley

    2001-01-01

    Objective: Reactmer Bond (Shofu Inc., Kyoto, Japan) is a glass ionomer (GI) based, tri-curable, all-in-one, filled adhesive. Both fluoroaluminosilicate glass (FASG) and fully pre-reacted glass (F-PRG) are used as fillers. This study examined the ultrastructure and elemental composition of resin–dentine interfaces that were treated with this adhesive.Methods: Dentine disks prepared from human third molars were abraded with either 600- or

  15. Initial Sliding Wear Kinetics of Two Types of Glass Ionomer Cement: A Tribological Study

    PubMed Central

    Ponthiaux, Pierre; Pradelle-Plasse, Nelly; Grosgogeat, Brigitte; Colon, Pierre

    2014-01-01

    The aim of this work was to characterize the initial wear kinetics of two different types of glass ionomer cement used in dentistry (the conventional glass ionomer cement and the resin-modified glass ionomer cement) under sliding friction after 28-day storing in distilled water or Ringer's solution. Sliding friction was applied through a pin-on-disk tribometer, in sphere-on-plane contact conditions, under 5 N normal load and 120 rotations per minute. The test lasted 7500 cycles and replicas were performed at 2500, 5000 and 7500 cycles. A profilometer was used to evaluate the wear volume. Data were analysed using Student's t-test at a significant level of 5%. There is no statistical significant difference between the results obtained for a given material with the maturation media (P > 0.05). However, for a given maturation medium, there are significant statistical differences between the data obtained for the two materials at each measurement (P < 0.0001). The wear rates of both materials decrease continuously during the running-in period between 0 and 2500 cycles. After 2500 cycles, the wear rate becomes constant and equal for both materials. The resin matrix contained in the resin-modified glass ionomer cement weakens the tribological behaviour of this material. PMID:25093185

  16. Effects of dentin surface treatments on shear bond strength of glass-ionomer cements

    PubMed Central

    Poggio, Claudio; Beltrami, Riccardo; Scribante, Andrea; Colombo, Marco; Lombardini, Marco

    2014-01-01

    Summary Aim The aim of this in vitro study was to evaluate the effect of different surface treatments on shear bond strength of a conventional glass-ionomer cement (GIC) and a resin-modified glass-ionomer cement (RMGIC) to dentin. Materials and methods 80 bovine permanent incisors were used. 40 cylindrical specimens of a GIC (Fuji IX GP Extra) and 40 cylindrical specimens of a RMGIC (Fuji II LC) were attached to the dentin. The teeth were then randomly assigned to 8 groups of equal size (n=10), 4 for every type of glass-ionomer cement, corresponding to type of dentin surface treatments. Group 1: GC Cavity Conditioner; Group 2: 37% phosphoric acid gel; Group 3: Clearfil SE Bond; Group 4: no dentin conditioning (control). The specimens were placed in a universal testing machine (Model 3343, Instron Corp., Canton, Mass., USA) and subsequently tested for shear bond strength (MPa). Results ANOVA showed the presence of significant differences among the various groups. Post hoc Tukey test showed different values of shear bond strength for Fuji IX GP Extra and for Fuji II LC. The different conditioners variably influence the adhesion of the glass-ionomer cements tested. Conclusions. RMGIC shear bond to dentin was higher than GIC. The use of a Self-etch adhesive system improved the shear bond strength values of RMGIC and lowered the shear bond strength values of GIC significantly. PMID:24753797

  17. Antibacterial effect of chlorhexidine- containing glass ionomer cement in vivo: a pilot study.

    PubMed

    Frencken, J E; Imazato, S; Toi, C; Mulder, J; Mickenautsch, S; Takahashi, Y; Ebisu, S

    2007-01-01

    This in vivo pilot study was carried out to test the antibacterial effect of glass ionomer containing chlorhexidine (test group) in comparison to conventional glass ionomer (control group). Fifty 6- to 11-year-old children with one occlusal lesion in a molar were randomly allocated to test and control groups in a parallel-group design. The cavity walls and one half of the floor were cleaned and restored with one of the materials without dentine conditioning. The restorations were removed after 7 days. Dentine samples were taken from the cleaned (affected dentine) and noncleaned area (infected dentine) at baseline and at day 7. Samples were anaerobically and aerobically cultivated for mutans streptococci, lactobacilli and total viable bacterial count (TVC) following common laboratory procedures. ANCOVA was used to test for treatment effects. Seven days after treatment, a significant decrease in anaerobic and aerobic bacterial counts (p = 0.0001) was shown. Lower numbers of anaerobic lactobacilli (p = 0.02), TVC (p = 0.008) and aerobic lactobacilli and TVC (p = 0.03), but not of mutans streptococci, were indicated in the test group compared to the control group. A significant reduction in aerobic lactobacilli from infected dentine treated with the glass ionomer containing chlorhexidine (p = 0.05) was observed whereas in affected dentine, anaerobic mutans streptococci, lactobacilli and TVC and aerobic TVC and mutans streptococci were significantly lower in the test group 7 days after treatment (p = 0.01). We conclude that the present pilot study revealed lower microorganism counts in chlorhexidine-containing glass ionomers than in conventional glass ionomers for both affected and infected dentine over a 7-day period. PMID:17284910

  18. Histological assessment of pulpal responses to resin modified glass ionomer cements in human teeth

    PubMed Central

    Eskandarizadeh, Ali; Parizi, Molook Torabi; Goroohi, Hossein; Badrian, Hamid; Asadi, Abbas; Khalighinejad, Navid

    2015-01-01

    Background: The biocompatibility of resin-modified glass ionomers (RMGIs) as a lining material is still under question. The present study evaluated the response of the pulp-dentin complex following application of resin-modified glass-ionomer cement, calcium hydroxide and conventional glass-ionomer in deep cavities prepared in human teeth. Materials and Methods: In this controlled clinical trial, 30 deep class V buccal cavities (3 mm × 2 mm × 2 mm) were prepared in human premolars treatment planned to be extracted for orthodontic reasons and divided into 3 groups. Groups were lined by a RMGI (Vivaglass), conventional glass Ionomer (Ionocid) and calcium hydroxide respectively. The cavities were subsequently filled with amalgam. Each group was then divided into two sub-groups according to time intervals 5 and 30 days. The patients were referred to Kerman Dental School and in accordance with orthodontic treatment plan; premolars were extracted and then prepared for histological assessment. The sections were stained with hematoxylin and eosin and periodic acid Schiff techniques. All of the samples were examined using a number of criteria including odontoblastic changes, inflammatory cells response, reactionary dentin formation and presence of microorganisms. The data were analyzed by Kruskal-Wallis and Mann-Whitney tests. P < 0.05 was considered as significant. Results: There was no significant difference among odontoblastic changes, reactionary dentin, presence of bacteria and inflammatory cells response of the groups (P > 0.05). Conclusion: Ionocid and Vivaglass resin-modified glass ionomers can be used as lining materials in human teeth. PMID:25878679

  19. Water-dependent Interfacial Transition Zone in Resin-modified Glass-ionomer Cement\\/Dentin Interfaces

    Microsoft Academic Search

    F. R. Tay; S. K. Sidhu; T. F. Watson; D. H. Pashley

    2004-01-01

    The function of the interfacial transition zone (absorption layer) in resin-modified glass-ionomer cements bonded to deep dentin remains obscure. This study tested the hypotheses that the absorption layer is formed only in the presence of water derived from hydrated dentin and allows for better bonding of resin-modified glass-ionomer cements to dentin. Ten percent polyacrylic acid-conditioned, hydrated, and dehydrated deep dentin

  20. How mobile are protons in the structure of dental glass ionomer cements?

    NASA Astrophysics Data System (ADS)

    Benetti, Ana R.; Jacobsen, Johan; Lehnhoff, Benedict; Momsen, Niels C. R.; Okhrimenko, Denis V.; Telling, Mark T. F.; Kardjilov, Nikolay; Strobl, Markus; Seydel, Tilo; Manke, Ingo; Bordallo, Heloisa N.

    2015-03-01

    The development of dental materials with improved properties and increased longevity can save costs and minimize discomfort for patients. Due to their good biocompatibility, glass ionomer cements are an interesting restorative option. However, these cements have limited mechanical strength to survive in the challenging oral environment. Therefore, a better understanding of the structure and hydration process of these cements can bring the necessary understanding to further developments. Neutrons and X-rays have been used to investigate the highly complex pore structure, as well as to assess the hydrogen mobility within these cements. Our findings suggest that the lower mechanical strength in glass ionomer cements results not only from the presence of pores, but also from the increased hydrogen mobility within the material. The relationship between microstructure, hydrogen mobility and strength brings insights into the material's durability, also demonstrating the need and opening the possibility for further research in these dental cements.

  1. How mobile are protons in the structure of dental glass ionomer cements?

    PubMed Central

    Benetti, Ana R.; Jacobsen, Johan; Lehnhoff, Benedict; Momsen, Niels C. R.; Okhrimenko, Denis V.; Telling, Mark T. F.; Kardjilov, Nikolay; Strobl, Markus; Seydel, Tilo; Manke, Ingo; Bordallo, Heloisa N.

    2015-01-01

    The development of dental materials with improved properties and increased longevity can save costs and minimize discomfort for patients. Due to their good biocompatibility, glass ionomer cements are an interesting restorative option. However, these cements have limited mechanical strength to survive in the challenging oral environment. Therefore, a better understanding of the structure and hydration process of these cements can bring the necessary understanding to further developments. Neutrons and X-rays have been used to investigate the highly complex pore structure, as well as to assess the hydrogen mobility within these cements. Our findings suggest that the lower mechanical strength in glass ionomer cements results not only from the presence of pores, but also from the increased hydrogen mobility within the material. The relationship between microstructure, hydrogen mobility and strength brings insights into the material's durability, also demonstrating the need and opening the possibility for further research in these dental cements. PMID:25754555

  2. In vivo study of the pulp reaction to Fuji IX, a glass ionomer cement

    Microsoft Academic Search

    J.-J. Lasfargues; M. Goldberg

    2000-01-01

    Objective: Our aims were to investigate the pulp biocompatibility of Fuji IX, a glass ionomer cement (GIC) used as a restorative material in cavities prepared in rat's upper molars, and to assess the value of this in vivo model for testing dental biomaterials.Method: Half-moon class V-like cavities were drilled on the mesial aspect of 26 rat upper first molars. Half

  3. Antimicrobial Effects of Dental Luting Glass Ionomer Cements on Streptococcus mutans

    PubMed Central

    Altenburger, Markus; Spitzmüller, Bettina; Anderson, Annette; Hellwig, Elmar

    2014-01-01

    Objective. To reduce secondary caries, glass ionomer luting cements are often used for cementing of indirect restorations. This is because of their well-known antimicrobial potential through the release of fluoride ions. The aim of this in vitro study was to investigate the antimicrobial effect of five dental luting cements which were based on glass ionomer cement technology. Methods. Five different glass ionomer based luting cements were tested for their antimicrobial effects on Streptococcus mutans in two different experimental setups: (i) determination of colony-forming units (CFUs) in a plate-counting assay; (ii) live/dead staining (LDS) and fluorescence microscopy. All experiments were conducted with or without prior treatment of the materials using sterilized human saliva. Antimicrobial effects were evaluated for adherent and planktonic bacteria. Bovine enamel slabs (BES) were used as negative control. BES covered with 0.2% chlorhexidine (CHX) served as positive control. Results. Each of the tested materials significantly reduced the number of initially adhered CFUs; this reduction was even more pronounced after prior incubation in saliva. Antimicrobial effects on adherent bacteria were confirmed by live-dead staining. Conclusion. All five luting cements showed an antimicrobial potential which was increased by prior incubation with human saliva, suggesting an enhanced effect in vivo. PMID:24795539

  4. COMPARISON OF TWO MINIMALLY INVASIVE METHODS ON THE LONGEVITY OF GLASS IONOMER CEMENT RESTORATIONS: SHORT-TERM RESULTS OF A PILOT STUDY

    PubMed Central

    Barata, Terezinha Jesus Esteves; Bresciani, Eduardo; Mattos, Maria Cecília Ribeiro; Lauris, José Roberto Pereira; Ericson, Dan; Navarro, Maria Fidela de Lima

    2008-01-01

    The purpose of this study was to evaluate the clinical performance of glass ionomer cement (GIC) restorations comparing two minimally invasive methods in permanent teeth after 12 months. Fifty pregnant women (second trimester of pregnancy), mean age 22 ± 5.30 years, were treated by two previously trained operators. The treatment approaches tested were: chemomechanical method (CarisolvTM; MediTeam) and atraumatic restorative treatment (ART). A split-mouth study design was used in which the two treatments were randomly placed in 50 matched pairs of permanent teeth. The chemomechanical method (CM) was the test group and the ART was the control group. The treatments were performed in Public Health Centers. The tested restorative material was a high-strength GIC (Ketac Molar; 3M/ESPE). The restorations were placed according to the ART guidelines. Two calibrated independent examiners evaluated the restorations in accordance with ART criteria. The interexaminer kappa was 0.97. Data were analyzed using 95% confidence interval on the binomial distribution and Fisher's exact test at 5% significance level. In a 12-month follow-up, 86% of the restorations were evaluated. In the test group (CM), 100% (CI=93.3-100%) of the restorations were considered successful. In the control group (ART) 97.6% (CI=87.4-99.9%) of the restorations were considered successful and 2.4% unsuccessful (marginal defect >0.5 mm). There was no statistically significant difference between the 12-mounth success rate for both groups (Fisher's exact test: P=0.49) and between the two operators (Fisher's exact test: P=1.00). Both minimally invasive methods, chemomechanical method and ART, showed a similar clinical performance after 12 months of follow up. PMID:19089209

  5. Effect of Self-etching Adhesives on the Bond Strength of Glass-Ionomer Cements

    PubMed Central

    Jaberi Ansari, Zahra; Panahandeh, Narges; Tabatabaei Shafiei, Zahra Sadat; Akbarzadeh Baghban, Alireza

    2014-01-01

    Objective: Statement of Problem: Adequate bond strength between glass ionomer cements and composite resin is necessary for the success of the sandwich technique. Purpose of Study: This study assessed the micro-shear bond strength of composite resin to glass-ionomer cements (GIC) using self-etch adhesives with different pH values. Materials and Methods: One hundred specimens (6×4×2 mm) were made using Fuji II and Fuji II LC GICs and treated with different adhesives as follows: Group 1:Fuji II+ Adper Prompt L-Pop, Group-2: Fuji II+SE bond, Group-3: Fuji II + AdheSE, Group-4:Fuji II+ Protect bond, Group-5: Fuji II + Single bond, Group-6:Fuji II LC+ Adper Prompt LPop, Group-7: Fuji II LC+SE bond, Group-8:Fuji II LC+ AdheSE, Group-9: Fuji II LC+ Protect bond, and Group-10: Fuji II LC+ Single bond. Each group consisted of 10 specimens. A cylinder of Z100 composite resin was placed on each sample and light cured. After 24 hours of water storage (37°C), the specimens were subjected to micro-shear bond strength tests (0.5 mm/min). Data were analyzed using two-way ANOVA and Tukey’s test. Results: The mean micro-shear bond strength of groups 1–10 was 11.66±1.79, 16.50±1.85, 18.47±1.77, 13.95±1.77, 15.27±1.49, 15.14±0.90, 20.03±1.19, 17.48±3.00, 16.24±1.98 and 16.03±1.49 MPa, respectively. There were significant differences between groups 1 and 7 (P<0.05). No significant difference was observed between other groups (P>0.05). Fuji II LC showed higher bond strength than Fuji II (P<0.05). Conclusion: Type of self-etch adhesive had no significant effect on micro-shear bond strength of glass-ionomer to composite resin. Resin modified glass ionomer cement (RMGIC) exhibited higher bond strength than the conventional GIC. PMID:25628698

  6. Translationally controlled tumor protein supplemented chitosan modified glass ionomer cement promotes osteoblast proliferation and function.

    PubMed

    Sangsuwan, Jiraporn; Wanichpakorn, Supreya; Kedjarune-Leggat, Ureporn

    2015-09-01

    The objective of this study was to evaluate the effect of translationally controlled tumor protein (TCTP) supplemented in a novel glass ionomer cement (BIO-GIC) on normal human osteoblasts (NHost cells). BIO-GIC was a glass ionomer cement (GIC) modified by adding chitosan and albumin to promote the release of TCTP. NHost cells were seeded on specimens of GIC, GIC+TCTP, BIO-GIC and BIO-GIC+TCTP. Cell proliferation was determined by BrdU assay. It was found that BIO-GIC+TCTP had significantly higher proliferation of cells than other specimens. Bone morphogenetic protein-2 (BMP-2) and osteopontin (OPN) gene expressions assessed by quantitative real time PCR and alkaline phosphatase (ALP) activity were used to determine cell differentiation. Bone cell function was investigated by calcium deposition using alizarin assay. Both BMP-2 and OPN gene expressions of cells cultured on specimens with added TCTP increased gradually up-regulation after day 1 and reached the highest on day 3 then down-regulation on day 7. The ALP activity of cells cultured on BIO-GIC+TCTP for 7days and calcium content after 14days were significantly higher than other groups. BIO-GIC+TCTP can promote osteoblast cells proliferation, differentiation and function. PMID:26046268

  7. Calcium polyphosphate as an additive to zinc-silicate glass ionomer cements.

    PubMed

    Valliant, Esther Mae; Gagnier, David; Dickey, Brett Thomas; Boyd, Daniel; Joseph Filiaggi, Mark

    2015-07-01

    Aluminum-free glass ionomer cements (GICs) are under development for orthopedic applications, but are limited by their insufficient handling properties. Here, the addition of calcium polyphosphate (CPP) was investigated as an additive to an experimental zinc-silicate glass ionomer cement. A 50% maximum increase in working time was observed with CPP addition, though this was not clinically significant due to the short working times of the starting zinc-silicate GIC. Surprisingly, CPP also improved the mechanical properties, especially the tensile strength which increased by ?33% after 30 days in TRIS buffer solution upon CPP addition up to 37.5?wt%. This strengthening may have been due to the formation of ionic crosslinks between the polyphosphate chains and polyacrylic acid. Thus, CPP is a potential additive to future GIC compositions as it has been shown to improve handling and mechanical properties. In addition, CPP may stimulate new bone growth and provide the ability for drug delivery, which are desirable modifications for an orthopedic cement. PMID:25627650

  8. Titanium and Glass-Ionomer Cement as Ossicular Replacement Materials: Biocompatibility Results after Implantation in the Rabbit

    Microsoft Academic Search

    Konrad Schwager; G. Geyer

    1998-01-01

    The middle ear poses unique challenges when finding suitable materials for ossicular reconstruction, primarily because of its link to the external environment via the eustachian tube, which leads to a greater potential for exposure to infectious agents. In this animal study, the biocompatibilities of titanium and glass-ionomer cement were assessed in the middle ear of the rabbit after being implanted

  9. Comparative Evaluation of Voids Present in Conventional and Capsulated Glass Ionomer Cements Using Two Different Conditioners: An In Vitro Study

    PubMed Central

    Sharma, Roshni; Reddy, Pallavi; Udameshi, Pooja; Vallakuruchi Jayabal, Narmatha

    2014-01-01

    This in vitro study evaluated the presence of voids in powder-liquid and capsulated glass ionomer cement. 40 cavities were prepared on root surfaces of maxillary incisors and divided into four groups. Cavities were conditioned with glass ionomer cement liquid (GC Corporation, Tokyo, Japan) in Groups 1 and 3 and with dentin conditioner (GC Corporation, Tokyo, Japan) in Groups 2 and 4. Conventional powder-liquid glass ionomer cement (GC Fuji II, GC Corporation, Tokyo, Japan) was used as a restorative material in Groups 1 and 2. Capsulated glass ionomer cement (GC Fuji II, GC Corporation, Tokyo, Japan) was used in Groups 3 and 4. Samples were sectioned and viewed under stereomicroscope to check for the presence of voids within the cement and at the cement-tooth junction. Data was analyzed using one-way ANOVA and Tukey's post hoc tests. Group 4 showed statistically significant results (P < 0.05) when compared to Groups 1 and 2 for voids within the cement. However, for voids at the margins, the results were statistically insignificant. PMID:25544842

  10. Influence of 2-hydroxyethyl methacrylate content on the optical properties of experimental 2-hydroxyethyl methacrylate-added dental glass ionomer

    Microsoft Academic Search

    Ho-Nam Lim; Bin Yu; Jin Ik Lim; Jin-Soo Ahn; Yong-Keun Lee

    2009-01-01

    The influence of 2-hydroxyethyl methacrylate (HEMA) on the properties of HEMA-added dental glass ionomer (HAGI) should be determined systematically to develop a smart restorative material. The purposes of this study were to determine the influence of incrementally added HEMA in experimental HAGIs on the color, translucency, opalescence, fluorescence and compressive strength, and to compare with those of commercial resin-modified glass

  11. The incorporation of nanoparticles into conventional glass-ionomer dental restorative cements.

    PubMed

    Gjorgievska, Elizabeta; Van Tendeloo, Gustaaf; Nicholson, John W; Coleman, Nichola J; Slipper, Ian J; Booth, Samantha

    2015-04-01

    Conventional glass-ionomer cements (GICs) are popular restorative materials, but their use is limited by their relatively low mechanical strength. This paper reports an attempt to improve these materials by incorporation of 10 wt% of three different types of nanoparticles, aluminum oxide, zirconium oxide, and titanium dioxide, into two commercial GICs (ChemFil® Rock and EQUIA™ Fil). The results indicate that the nanoparticles readily dispersed into the cement matrix by hand mixing and reduced the porosity of set cements by filling the empty spaces between the glass particles. Both cements showed no significant difference in compressive strength with added alumina, and ChemFil® Rock also showed no significant difference with zirconia. By contrast, ChemFil® Rock showed significantly higher compressive strength with added titania, and EQUIA™ Fil showed significantly higher compressive strength with both zirconia and titania. Fewer air voids were observed in all nanoparticle-containing cements and this, in turn, reduced the development of cracks within the matrix of the cements. These changes in microstructure provide a likely reason for the observed increases in compressive strength, and overall the addition of nanoparticles appears to be a promising strategy for improving the physical properties of GICs. PMID:25691120

  12. Effect of Nanoclay Dispersion on the Properties of a Commercial Glass Ionomer Cement

    PubMed Central

    Fareed, Muhammad A.; Stamboulis, Artemis

    2014-01-01

    Objective. The reinforcement effect of polymer-grade montmorillonite (PGV and PGN nanoclay) on Fuji-IX glass ionomer cement was investigated. Materials and Method. PGV and PGV nanoclays (2.0?wt%) were dispersed in the liquid portion of Fuji-IX. Fourier-transform infrared (FTIR) spectroscopy and gel permeation chromatography (GPC) were used to quantify acid-base reaction and the liquid portion of GIC. The mechanical properties (CS, DTS, FS, and Ef) of cements (n = 20) were measured at 1 hour, 1 day, and 1 month. The microstructure was examined by cryo-SEM and TEM. Results. FTIR shows that the setting reaction involves the neutralisation of PAA by the glass powder which was linked with the formation of calcium and aluminium salt-complexes. The experimental GICs (C-V and C-N) exhibited mechanical properties in compliance to ISO standard requirement have higher values than Fuji-IX cement. There was no significant correlation of mechanical properties was found between C-V and C-N. The average Mw of Fuji-IX was 15,700 and the refractive index chromatogram peak area was 33,800. TEM observation confirmed that nanoclays were mostly exfoliated and dispersed in the matrix of GIC. Conclusion. The reinforcement of nanoclays in GICs may potentially produce cements with better mechanical properties without compromising the nature of polyacid neutralisation. PMID:25210518

  13. Surface roughness of glass ionomer cements indicated for uncooperative patients according to surface protection treatment

    PubMed Central

    Pacifici, Edoardo; Bossù, Maurizio; Giovannetti, Agostino; La Torre, Giuseppe; Guerra, Fabrizio; Polimeni, Antonella

    2013-01-01

    Summary Background Even today, use of Glass Ionomer Cements (GIC) as restorative material is indicated for uncooperative patients. Aim The study aimed at estimating the surface roughness of different GICs using or not their proprietary surface coatings and at observing the interfaces between cement and coating through SEM. Materials and methods Forty specimens have been obtained and divided into 4 groups: Fuji IX (IX), Fuji IX/G-Coat Plus (IXC), Vitremer (V), Vitremer/Finishing Gloss (VFG). Samples were obtained using silicone moulds to simulate class I restorations. All specimens were processed for profilometric evaluation. The statistical differences of surface roughness between groups were assessed using One-Way Analysis of Variance (One-Way ANOVA) (p<0.05). The Two-Way Analysis of Variance (Two-Way ANOVA) was used to evaluate the influence of two factors: restoration material and presence of coating. Coated restoration specimens (IXC and VFG) were sectioned perpendicular to the restoration surface and processed for SEM evaluation. Results No statistical differences in roughness could be noticed between groups or factors. Following microscopic observation, interfaces between restoration material and coating were better for group IXC than for group VFG. Conclusions When specimens are obtained simulating normal clinical procedures, the presence of surface protection does not significantly improve the surface roughness of GICs. PMID:24611090

  14. Effect of saliva contamination on the bond of dentin to resin-modified glass-ionomer cement.

    PubMed

    Safar, J A; Davis, R D; Overton, J D

    1999-01-01

    This in vitro study compared the shear bond strength of a resin-modified glass-ionomer restorative material (Fuji II LC) bonded to saliva-contaminated dentin versus non-contaminated dentin. Seventy-five extracted human molar teeth were randomly divided into five groups of 15 samples each. The dentin was treated with 10% polyacrylic acid for 20 seconds, rinsed, and dried. The acid-treated dentin surfaces in Groups 1-4 were contaminated with saliva. In Group 1, the saliva was air thinned. In Groups 2-4, saliva was dried completely with compressed air. The saliva-contaminated dentin in Group 3 was rinsed and dried. The saliva-contaminated dentin in Group 4 was rinsed, dried, treated with 10% polyacrylic acid, and dried. Specimens in Group 5 received no contamination. The resin-modified glass-ionomer cement restorative material was mixed and applied to the dentin surfaces. Following placement of the restorative material and 7 days of storage, the specimens were thermo-cycled 300 times. Using the Instron Universal Testing Machine, a shear force was applied to the restorative material. Shear bond strength values were compared among the groups using a one-way ANOVA and Student-Neuman-Keuls Multiple Range Test (alpha = 0.05). The non-contaminated specimens (Group 5) were significantly stronger than the contaminated specimens (Groups 1-4). There were no significant differences in bond strength among the groups containing contaminated specimens. Salivary contamination occurring after dentin etching significantly reduced the bond strength of the resin-modified glass-ionomer restorative material to dentin. Neither rinsing nor rinsing and re-etching resulted in bond strengths as great as to non-contaminated dentin. PMID:10823084

  15. Development of a novel antimicrobial-releasing glass ionomer cement functionalized with chlorhexidine hexametaphosphate nanoparticles

    PubMed Central

    2014-01-01

    Background Glass ionomer cements (GICs) are a class of dental biomaterials. They have a wide range of uses including permanent restorations (fillings), cavity linings, fissure sealants and adhesives. One of the most common reasons for replacing a dental restoration is recurrent bacterial tooth decay around the margins of the biomaterial. Therefore, a dental biomaterial which creates a sustained antimicrobial environment around the restoration would be of considerable clinical benefit. In this manuscript, the formulation of a GIC containing novel antimicrobial nanoparticles composed of chlorhexidine hexametaphosphate at 1, 2, 5, 10 and 20% powder substitution by mass is reported. The aim is to create GICs which contain chlorhexidine-hexametaphosphate nanoparticles and characterize the nanoparticle size, morphology and charge and the release of chlorhexidine and fluoride, tensile strength and morphology of the GICs. Results The GICs released chlorhexidine, which is a broad spectrum antimicrobial agent effective against a wide range of oral bacteria, over the duration of the experiment in a dose-dependent manner. This was not at the expense of other properties; fluoride release was not significantly affected by the substitution of antimicrobial nanoparticles in most formulations and internal structure appeared unaffected up to and including 10% substitution. Diametral tensile strength decreased numerically with substitutions of 10 and 20% nanoparticles but this difference was not statistically significant. Conclusion A series of GICs functionalized with chlorhexidine-hexametaphosphate nanoparticles were created for the first time. These released chlorhexidine in a dose-dependent manner. These materials may find application in the development of a new generation of antimicrobial dental nanomaterials. PMID:24456793

  16. Research gaps identified during systematic reviews of clinical trials: glass-ionomer cements

    PubMed Central

    2012-01-01

    Background To report the results of an audit concerning research gaps in clinical trials that were accepted for appraisal in authored and published systematic reviews regarding the application of glass-ionomer cements (GIC) in dental practice Methods Information concerning research gaps in trial precision was extracted, following a framework that included classification of the research gap reasons: ‘imprecision of information (results)’, ‘biased information’, ‘inconsistency or unknown consistency’ and ‘not the right information’, as well as research gap characterization using PICOS elements: population (P), intervention (I), comparison (C), outcomes (O) and setting (S). Internal trial validity assessment was based on the understanding that successful control for systematic error cannot be assured on the basis of inclusion of adequate methods alone, but also requires empirical evidence about whether such attempt was successful. Results A comprehensive and interconnected coverage of GIC-related clinical topics was established. The most common reasons found for gaps in trial precision were lack of sufficient trials and lack of sufficient large sample size. Only a few research gaps were ascribed to ‘Lack of information’ caused by focus on mainly surrogate trial outcomes. According to the chosen assessment criteria, a lack of adequate randomisation, allocation concealment and blinding/masking in trials covering all reviewed GIC topics was noted (selection- and detection/performance bias risk). Trial results appear to be less affected by loss-to-follow-up (attrition bias risk). Conclusion This audit represents an adjunct of the systematic review articles it has covered. Its results do not change the systematic review’s conclusions but highlight existing research gaps concerning the precision and internal validity of reviewed trials in detail. These gaps should be addressed in future GIC-related clinical research. PMID:22747674

  17. Retention of a resin-based sealant and a glass ionomer used as a fissure sealant in children with special needs

    PubMed Central

    Nualart-Grollmus, Zacy-Carola

    2014-01-01

    Objectives: The aim of this research is to evaluate the retention of sealants of resin and resin-modified ionomeric glass pits and fissures, on first permanent molars of special patients. Material and Methods: The sample was comprised by 32 children. The ages were between 7 and 18 years. The sealing procedure was made with the relative isolation of the molars to be sealed, through the use of cotton rolls. Two molars were sealed with Clinpro Sealant 3M Dental and the others with Vitremer. Checking of the sealants was made after 3 and 6 months of their placement, evaluating with 3 values: TR: Totally Restrained; PR: Partially Restrained; and CL: Completely Lost. Results: 67.18% of the resinous sealants, and 70.31% of the glass ionomer sealants were successful after three months. After six months, 57.81% of the resin-based sealants and 51.56% of the glass ionomer sealants were successful. When performing the Chi-square statistical analysis (P<0.05) no statistical significance was observed after 6 months. Conclusions: The retention of the resin sealant was similar to that of the glass ionomer cement at the end of six months and the retention of sealants on maxillary teeth was higher than on mandibular teeth. Key words:Sealant, glass ionomer, retention, caries, special needs. PMID:25674325

  18. In Vitro Comparison of Coronal Microleakage between Resilon Alone and Gutta-Percha with a Glass-ionomer Intraorifice Barrier Using a Fluid Filtration Model

    Microsoft Academic Search

    Ryan M. Jack; Gary G. Goodell

    2008-01-01

    The prevention and control of coronal microleakage is critical for successful endodontic outcomes. The purpose of this study was to compare coronal microleakage between Resilon alone and gutta-percha with a glass ionomer intraorifice barrier using a fluid filtration model. Thirty-four extracted human teeth were decoronated, prepared to a standardized length of 16 mm, and instrumented to a .06 taper ISO

  19. Influence of powder/liquid ratio on the radiodensity and diametral tensile strength of glass ionomer cements

    PubMed Central

    FONSECA, Rodrigo Borges; BRANCO, Carolina Assaf; QUAGLIATTO, Paulo Sérgio; GONÇALVES, Luciano de Souza; SOARES, Carlos José; CARLO, Hugo Lemes; CORRER-SOBRINHO, Lourenço

    2010-01-01

    Objective To determine the influence of P/L ratio on the radiodensity and diametral tensile strength (DTS) of glass ionomer cements. Material and Methods There were 2 factors under study: P/L ratio (manufacturer's recommended P/L ratio and a 50% reduced P/L ratio), and materials (Vitro Molar, Vitro Fil, Vitro Cem conventional GICs and Vitro Fil LC, Ortho Glass LC RMGICs). Five 1-mm-thick samples of each material-P/L ratio were produced for radiodensity evaluation. Samples were x-ray exposed onto Digora phosphor plate and radiodensity was obtained using the software Digora for Windows 2.5 Rev 0. For DTS, five (4.0x8.0 mm) cylinder samples of each material were tested (0.5 mm/min). Data were subjected to one- and two-way ANOVA (5x2) followed by Tukey's HSD test, or Kruskal-Wallis and Dunn's method. For paired comparisons, t-test or Mann-Whitney test were used (a=0.05). Results There was a significant interaction (P=0.001) for the studied factors (materials vs. P/L ratio). Reduced P/L ratio resulted in significantly lower DTS for the RMGICs, but radiodensity was affected for all materials (P<0.05). Conclusions Reduced P/L ratio affected properties of the tested glass ionomer cements. RMGICs were more susceptible to lower values of DTS, but radiodensity decreased for all materials following P/L ratio reduction. PMID:21308288

  20. An in-vitro study to compare the microhardness of glass ionomer cement set conventionally versus set under ultrasonic waves

    PubMed Central

    Baloch, FA; Mirza, AJ; Baloch, D.

    2010-01-01

    Objective: To assess the difference of surface hardness of glass ionomer cement (GIC) set by conventional setting method and under ultrasonically energized method. Method: 20 cylindrical samples measuring 2.5mm (diameter) and 5mm (length) were prepared with type IX GIC. Ten of these samples were allowed to set by conventional setting method and other ten were set under ultrasonic excitation energy. After finishing and polishing of the samples, three indentations were made on each sample using Vicker’s hardness machine with a load of 300 gm for 15 seconds. The surface microhardness of the indents was calculated by Vicker’s hardness formula. Results: Surface microhardness of samples set by ultrasound setting method was significantly higher than samples set by conventional method. Conclusion: This can be beneficial for the dental patients as when used as a restorative material, it will have a long lasting effect and can also be used in posterior load bearing areas. PMID:21475553

  1. Comparative Assessment of ActiV GP\\/Glass Ionomer Sealer, Resilon\\/Epiphany, and Gutta-Percha\\/AH Plus Obturation: A Bacterial Leakage Study

    Microsoft Academic Search

    Joel N. Fransen; Jianing He; Gerald N. Glickman; Alejandro Rios; Jay D. Shulman; Allen Honeyman

    2008-01-01

    The objective of this study was to compare the sealing ability of ActiV GP\\/glass ionomer (GI) sealer (Brasseler USA, Savannah, GA), Resilon\\/Epiphany (Pentron Clinical Technologies, Wallingford, CT), and gutta-percha (GP)\\/AH Plus (Dentsply Maillefer, Tulsa, OK). Seventy-three human single-rooted teeth were randomly divided into three test groups (20 canals each) and two control groups (5 positive and 8 negative). Using Enterococcus

  2. Comparative evaluation of intracanal sealing ability of mineral trioxide aggregate and glass ionomer cement: An in vitro study

    PubMed Central

    Malik, Gauri; Bogra, Poonam; Singh, Simranjeet; Samra, Rupandeep K

    2013-01-01

    Aims: The purpose of this study was to compare the sealing ability of Mineral Trioxide Aggregate (MTA) and Glass Ionomer Cement (GIC) when used over gutta-percha as intracanal sealing materials. The study also evaluated the sealing ability of Zinc oxide eugenol (ZOE) cement and Acroseal sealer. Materials and Methods: Teeth were obturated with gutta-percha using sealer ZOE (group A, C, D) and Acroseal (group B). The groups were further divided into 2 subgroups (15 premolars each) on the basis of intracanal sealing material used: GIC subgroups (A1, B1) and MTA in subgroups (A2, B2). The clearing technique was used in this study for leakage evaluation. Seventy mandibular premolars were prepared using step-back technique and divided into experimental groups A and B (30 premolars each) and the positive and negative control groups C and D (5 premolars each). Statistical analysis used: Coronal microleakage was determined under stereomicroscope using 15X magnification. Data was statistically analyzed using one-way ANOVA followed by Post-Hoc Multiple comparison (Bonferroni). Results: MTA group leaked significantly less than GIC group (P < 0.05). Acroseal exhibited better sealing ability than ZOE sealer. Teeth with no intracanal barrier showed almost complete leakage. Conclusions: MTA may be preferred over GIC as an intracanal barrier. PMID:24347890

  3. Enhancing glass ionomer cement features by using the HA/YSZ nanocomposite: a feed forward neural network modelling.

    PubMed

    Rajabzadeh, Ghadir; Salehi, Sahar; Nemati, Ali; Tavakoli, Razeih; Solati Hashjin, Mehran

    2014-01-01

    Despite brilliant properties of glass ionomer cement (GIC), its weak mechanical property poses an obstacle for its use in medical applications. The present research aims to formulate hydroxyapatite/yttria-stabilized zirconia (HA/YSZ) in the composition of GIC to enhance mechanical properties and to improve fluoride release of GIC. HA/YSZ was synthesized via a sol-gel method and characterized by applying X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photo-emission spectroscopy (XPS) and simultaneous thermal analysis (STA) along with transmission electron microscopy (TEM) methods. The synthesized nanocomposite was mixed with GIC at a fixed composition of 5wt%. The effect of different weight percentages of YSZ:HA on GIC was investigated by measuring the compressive strength, diametral tensile strength, microhardness and fluoride release. The results showed that, after 1 and 7 days of setting, the 20wt% nanohydroxyapatite/80wt% stabilized zirconia cement exhibited higher compressive strength (1857-245MPa), higher diametral tensile strength (11-14MPa) and greater microhardness (104-106MPa) as compared with the pure GIC (65-88MPa in compressive strength, 5-9.5MPa in diametral tensile strength and 70-89MPa in microhardness). The reinforced cement, also, exhibited higher fluoride release compared with pure GIC. The artificial neural network (ANN) was trained for modeling the system. Results obtained by ANN have proved to be completely in accordance with expectations. PMID:24140732

  4. Caries-preventive effect of glass ionomer and resin-based fissure sealants on permanent teeth: a meta analysis.

    PubMed

    Yengopal, Veerasamy; Mickenautsch, Steffen; Bezerra, Ana C; Leal, Soraya C

    2009-09-01

    The purpose of this quantitative systematic review was to appraise the evidence on the caries-preventive effect of glass ionomer cement (GIC) in relation to resin-based fissure sealants. Nine English and two Portuguese databases were searched (15 January 2008). Randomized clinical trials and systematic reviews were considered for inclusion. Trial exclusion criteria were: drop-out rates > 33%; no randomization; baseline differences in groups not statistically adjusted; and no clinically important outcomes were presented. Two authors reviewed the articles independently. The outcome measure for the caries preventive effect was caries absence on sealed teeth. Of the 112 identified articles, 25 were selected for review. Of these, 14 were excluded and 11 accepted (8 trials; 3 systematic reviews). The accepted reviews provided no evidence of superiority of either sealant material. Six trials were included for meta-analysis. The pooled odds ratio was 0.96, 95% CI 0.62-1.49, indicating no difference in the caries-preventive effect of GIC and resin-based fissure sealant material. This systematic review with meta-analysis found no evidence that either material was superior to the other in the prevention of dental caries. Thus, both materials appear equally suitable for clinical application as a fissure sealant material. PMID:19776504

  5. Evaluation of antibacterial and antifungal activity of new calcium-based cement (Biodentine) compared to MTA and glass ionomer cement

    PubMed Central

    Bhavana, Vankayala; Chaitanya, Krishna Popuri; Gandi, Padma; Patil, Jayaprakash; Dola, Binoy; Reddy, Rahul B.

    2015-01-01

    Objective: To evaluate the antibacterial and antifungal properties of calcium-based cement, Biodentine (Ca3SiO2), compared to commercial glass ionomer cements (GICs) and mineral trioxide aggregate (MTA). Materials and Methods: Pellets of GICs, ProRoot MTA, and Biodentine were prepared to test the influence of these cements on the growth of four oral microbial strains: Streptococcus mutans, Enterococcus faecalis, Escherichia coli, and Candida albicans; using agar diffusion method. Wells were formed by removing the agar and the manipulated materials were immediately placed in the wells. The pellets were lodged in seeded plates and the growth inhibition diameter around the material was measured after 24-72 h incubation at 37°C. The data were analyzed using analysis of variance (ANOVA) test to compare the differences among the three cements at different concentrations. Results: Test indicates that the antimicrobial activity of Biodentine, on all the microorganisms tested, was very strong, showing a mean inhibition zone of 3.2 mm, which extends over time towards all the strains. For Biodentine, GIC, and MTA, the diameters of the inhibition zones for S. mutans were significantly larger than for E. faecalis, Candida, and E. coli (P < 0.05). Conclusion: All materials showed antimicrobial activity against the tested strains except for GIC on Candida. Largest inhibition zone was observed for Streptococcus group. Biodentine created larger inhibition zones than MTA and GIC. PMID:25657526

  6. Present and future of glass-ionomers and calcium-silicate cements as bioactive materials in dentistry: Biophotonics-based interfacial analyses in health and disease

    PubMed Central

    Watson, Timothy F.; Atmeh, Amre R.; Sajini, Shara; Cook, Richard J.; Festy, Frederic

    2014-01-01

    Objective Since their introduction, calcium silicate cements have primarily found use as endodontic sealers, due to long setting times. While similar in chemistry, recent variations such as constituent proportions, purities and manufacturing processes mandate a critical understanding of service behavior differences of the new coronal restorative material variants. Of particular relevance to minimally invasive philosophies is the potential for ion supply, from initial hydration to mature set in dental cements. They may be capable of supporting repair and remineralization of dentin left after decay and cavity preparation, following the concepts of ion exchange from glass ionomers. Methods This paper reviews the underlying chemistry and interactions of glass ionomer and calcium silicate cements, with dental tissues, concentrating on dentin–restoration interface reactions. We additionally demonstrate a new optical technique, based around high resolution deep tissue, two-photon fluorescence and lifetime imaging, which allows monitoring of undisturbed cement–dentin interface samples behavior over time. Results The local bioactivity of the calcium-silicate based materials has been shown to produce mineralization within the subjacent dentin substrate, extending deep within the tissues. This suggests that the local ion-rich alkaline environment may be more favorable to mineral repair and re-construction, compared with the acidic environs of comparable glass ionomer based materials. Significance The advantages of this potential re-mineralization phenomenon for minimally invasive management of carious dentin are self-evident. There is a clear need to improve the bioactivity of restorative dental materials and these calcium silicate cement systems offer exciting possibilities in realizing this goal. PMID:24113131

  7. BOND STRENGTH OF RESIN MODIFIED GLASS IONOMER CEMENT TO PRIMARY DENTIN AFTER CUTTING WITH DIFFERENT BUR TYPES AND DENTIN CONDITIONING

    PubMed Central

    Nicoló, Rebeca Di; Shintome, Luciana Keiko; Myaki, Silvio Issáo; Nagayassu, Marcos Paulo

    2007-01-01

    The aim of this in vitro study was to evaluate the effect of different bur types and acid etching protocols on the shear bond strength (SBS) of a resin modified glass ionomer cement (RM-GIC) to primary dentin. Forty-eight clinically sound human primary molars were selected and randomly assigned to four groups (n=12). In G1, the lingual surface of the teeth was cut with a carbide bur until a 2.0-mm-diameter dentin area was exposed, followed by the application of RM-GIC (Vitremer – 3M/ESPE) prepared according to the manufacturer’s instructions. The specimens of G2, received the same treatment of G1, however the dentin was conditioned with phosphoric acid. In groups G3 and G4 the same procedures of G1 and G2 were conducted respectively, nevertheless dentin cutting was made with a diamond bur. The specimens were stored in distilled water at 37°C for 24h, and then tested in a universal testing machine. SBS. data were submitted to 2-way ANOVA (= 5%) and indicated that SBS values of RM-GIC bonded to primary dentin cut with different burs were not statistically different, but the specimens that were conditioned with phosphoric acid presented SBS values significantly higher that those without conditioning. To observe micromorphologic characteristics of the effects of dentin surface cut by diamond or carbide rotary instruments and conditioners treatment, some specimens were examined by scanning electron microscopy. Smear layer was present in all specimens regardless of the type of rotary instrument used for dentin cutting, and specimens etched with phosphoric acid presented more effective removal of smear layer. It was concluded that SBS of a RM-GIC to primary dentin was affected by the acid conditioning but the bur type had no influence. PMID:19089179

  8. Absence of carious lesions at margins of glass-ionomer cement and amalgam restorations: An update of systematic review evidence

    PubMed Central

    2011-01-01

    Background This article aims to update the existing systematic review evidence elicited by Mickenautsch et al. up to 18 January 2008 (published in the European Journal of Paediatric Dentistry in 2009) and addressing the review question of whether, in the same dentition and same cavity class, glass-ionomer cement (GIC) restored cavities show less recurrent carious lesions on cavity margins than cavities restored with amalgam. Methods The systematic literature search was extended beyond the original search date and a further hand-search and reference check was done. The quality of accepted trials was assessed, using updated quality criteria, and the risk of bias was investigated in more depth than previously reported. In addition, the focus of quantitative synthesis was shifted to single datasets extracted from the accepted trials. Results The database search (up to 10 August 2010) identified 1 new trial, in addition to the 9 included in the original systematic review, and 11 further trials were included after a hand-search and reference check. Of these 21 trials, 11 were excluded and 10 were accepted for data extraction and quality assessment. Thirteen dichotomous datasets of primary outcomes and 4 datasets with secondary outcomes were extracted. Meta-analysis and cumulative meta-analysis were used in combining clinically homogenous datasets. The overall results of the computed datasets suggest that GIC has a higher caries-preventive effect than amalgam for restorations in permanent teeth. No difference was found for restorations in the primary dentition. Conclusion This outcome is in agreement with the conclusions of the original systematic review. Although the findings of the trials identified in this update may be considered to be less affected by attrition- and publication bias, their risk of selection- and detection/performance bias is high. Thus, verification of the currently available results requires further high-quality randomised control trials. PMID:21396097

  9. Marginal gap, cement thickness, and microleakage of 2 zirconia crown systems luted with glass ionomer and MDP-based cements.

    PubMed

    Sener, Isil; Turker, Begum; Valandro, Luiz Felipe; Ozcan, Mutlu

    2014-01-01

    This in vitro study evaluated the marginal gap, cement thickness, and microleakage of glass-ionomer cement (GIC) and phosphate monomer-containing resin cement (MDP-RC) under 2 zirconia crown systems (Cercon and DC-Zirkon). Forty human premolars were prepared for all-ceramic zirconia crowns with a 1 mm circumferential finish line and a 1.5 mm occlusal reduction. The crowns (n = 10 per group) from each zirconia system were randomly divided into 2 groups and cemented either with GIC (Vivaglass CEM) or MDP-RC (Panavia F 2.0) cement. The cemented crowns were thermocycled 5000 times (5°-55°C). The crowns were immersed in 0.5% basic fuchsine dye solution for 24 hours and sectioned buccolingually and mesiodistally. Specimens were examined under optical microscope (100X). Data were analyzed using Student t-test and chi-square tests (? = 0.05). Mean marginal gap values for Cercon (85 ± 11.4 ?m) were significantly higher than for DC-Zircon (75.3 ± 13.2 ?m) (P = 0.018). The mean cement thickness values of GIC (81.7 ± 13.9 ?m) and MDP-RC (78.5 ± 12.5 ?m) were not significantly different (P = 0.447). Microleakage scores did not demonstrate significant difference between GIC (P = 0.385) and MDP-RC (P = 0.631) under Cercon or DC-Zircon. Considering the cement thickness values and microleakage scores obtained, both zirconia crown systems could be cemented in combination with either GIC or MDP-RC. PMID:24598500

  10. Comparison of shear bond strength of resin-modified glass ionomer to conditioned and unconditioned mineral trioxide aggregate surface: An in vitro study

    PubMed Central

    Gulati, Shikha; Shenoy, Vanitha Umesh; Margasahayam, Sumanthini Venkatasubramanyam

    2014-01-01

    Introduction: The aim of this study was to compare the shear bond strength of resin modified glass ionomer cement to conditioned and unconditioned mineral trioxide aggregate surface. Materials and Method: White Mineral Trioxide Aggregate (WMTA) and Resin Modified Glass Ionomer Cement (RMGIC) were used for the study. 60 WMTA specimens were prepared and stored in an incubator at 37° C and 100% humidity for 72 hrs. The specimens were then divided into two groups- half of the specimens were conditioned and remaining half were left unconditioned, subsequent to which RMGIC was placed over MTA. The specimens were then stored in an incubator for 24 hrs at 37° C and 100% humidity. The shear bond strength value of RMGIC to conditioned and unconditioned WMTA was measured and compared using unpaired 't ?’ test. Results: The mean shear bond strength of value of RMGIC to conditioned and unconditioned WMTA was 6.59 MPa and 7.587 MPa respectively. Statistical analysis using unpaired t-test revealed that the difference between values of two groups was not statistically significant (P > 0.05). Conclusions: During clinical procedures like pulp capping and furcal repair, if RMGIC is placed as a base over MTA, then conditioning should be done to increase the bond strength between RMGIC and dentin and any inadvertent contact of conditioner with MTA will not significantly affect the shear bond strength value of RMGIC to MTA. PMID:25298644

  11. Comparative in vitro evaluation of internal adaptation of resin-modified glass ionomer, flowable composite and bonding agent applied as a liner under composite restoration: A scanning electron microscope study

    PubMed Central

    Soubhagya, M; Goud, K Mallikarjun; Deepak, B S; Thakur, Sophia; Nandini, T N; Arun, J

    2015-01-01

    Background: The use of resin-modified glass Ionomer cement in sandwich technique is widely practiced with the advent of various newer generation of composites the bond between resin-modified glass Ionomer and these resins should be validated. This study is done to evaluate the interfacial microgaps between different types of liners and dentin, liners and composite (Filtek p60 [FLp60]) using scanning electron microscope (SEM). Materials and Methods: Standardized Class V preparations were performed in buccal/lingual surfaces of 30 caries, crack and defect-free extracted human third molars. The prepared teeth were divided into three groups. Group I: Single bond (SB), Group II: SB + synergy flow, Group III: SB + vitrebond. They were restored with composite resin FLp60, according to the manufacturer instructions. The SB + vitrebond, cross-sectioned through the canter of the restoration. The specimens were fixed, dehydrated, polished, and processed for SEM. The internal adaptation of the materials to the axial wall was analyzed under SEM with ×1000 magnification. Results: The data obtained were analyzed with nonparametric tests (Kruskal–Wallis, P < 0.05). flowable composite or resin-modified glass ionomer applied in conjunction with adhesive resulted in statistically wider microgaps than occurred when the dentin was only hybridized prior to the restoration. Conclusion: Hybridization of dentin only provides superior sealing of the dentin-restoration interface than does flowable resin or resin-modified glass ionomer. PMID:25954067

  12. An in vitro study on the maturation of conventional glass ionomer cements and their interface to dentin.

    PubMed

    Zoergiebel, Julius; Ilie, Nicoleta

    2013-12-01

    The objective of the study was to investigate the influence of long-term storage (up to 1 year) and coating on the variation of micro-mechanical properties of four conventional restorative glass ionomer cements (GICs) within 3.5 mm deep class I cavities. Four commercially available GICs (Riva Self Cure (SDI), ChemFil Rock (Dentsply), Fuji IX Fast and Fuji IX GP Extra/Equia (GC)) were applied to 100 teeth. In each tooth, two similar 3.5 mm deep class I cavities were prepared and filled with the GICs, with and without resin coating. The samples were stored in artificial saliva at 37 °C for 1 week, 1 month, 3 months, 6 months and 1 year. The variation in mechanical properties (indentation modulus (E) and Vickers hardness (HV)) were determined in 100 ?m steps starting from the filling surface, through the intermediate layer in between dentine and GIC, and ending 100 ?m in dentin. HV and E were strongly influenced by the material (P<0.05, partial eta-squared ?P(2) = 0.31 and 0.23) but less by aging duration (P<0.05, ?P(2) = 0.02 and 0.12) and resin coating (P<0.05, ?P(2) = 0.02 and 0.03). The depth of measurement (0-2 mm) has no influence on HV (P = 0.789). HV shows a gentle increase over the 1 year storage period (P = 0.002). A ?300 ?m GIC zone at the areas close to dentin with weaker properties as those measured in dentin or GIC was identified in all fillings, irrespective of the presence of coating, and at all storage periods. The thickness of this zone is more strongly influenced by storage (P<0.05, ?P(2) = 0.081) than by material type (P<0.05, ?P(2) = 0.056), while coating showed no influence (P = 0.869). Filler morphology and dimension were similar to upper parts of the GIC filling; however, the amount of low cations was higher. We concluded that the development of an intermediate layer in between dentine and GIC with lower mechanical properties might be responsible for the bond quality of GIC to dentine. Moreover, class I GIC restorations are unlikely to feature constant mechanical properties throughout the cavity, regardless of conditions such as aging and coating. PMID:23954325

  13. Morphological analysis of ionomers

    SciTech Connect

    Not Available

    1991-01-01

    Anomalous small-angle x-ray scattering (SAXS) investigations were carried out on amorphous and semi-crystalline ionomers (Ni- neutralized sulfonated polystyrene ionomers, polyurethane ionomer). Ionomers with semicrystalline matrices (three-phase materials) were also studied with SAXS (poly(ethylene-co-methacrylic acid) ionomer). Ethylene oxide units were incorporated into the backbone of sulfonated polyurethane ionomers in an attempt to induce aggregate dissociation. Small-angle neutron scattering was used to study the effect of ionic aggregation on ionomer chain dimensions in telechelic and model polyurethane ionomers. Studies have been completed on carboxylated and sulfonated model polyurethane ionomers in order to determine the effect of the pendant ionic group on ionomer structure- property relationships (mechanical properties). (DLC)

  14. Fracture frequency and longevity of fractured resin composite, polyacid-modified resin composite, and resin-modified glass ionomer cement class IV restorations: an up to 14 years of follow-up

    Microsoft Academic Search

    Jan W. V. van Dijken; Ulla Pallesen

    2010-01-01

    The aim of this study was to evaluate the fracture frequency and longevity of fractured class IV resin composite (RC), polyacid-modified\\u000a resin composite (compomer; PMRC), and resin-modified glass ionomer cement (RMGIC) restorations in a longitudinal long-term\\u000a follow-up. Eighty-five class IV RC (43: Pekafil), PMRC (24: Dyract (D), Hytac (H)), and RMGIC (18: Fuji II LC (F), Photac\\u000a Fil (P)) restorations

  15. Methods and preliminary findings of a cost-effectiveness study of glass-ionomer-based and composite resin sealant materials after 2 yr.

    PubMed

    Goldman, Ann S; Chen, Xi; Fan, Mingwen; Frencken, Jo E

    2014-06-01

    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 on personnel time (measured with activity sampling), transportation, materials, instruments and equipment, and restoration costs for replacing failed sealants from a community trial involving 7- to 9-yr-old Chinese children. Cost data were standardized to reflect the placement of 1,000 sealants per group. Outcomes were the differences in the number of dentine caries lesions that developed between groups. The average sealant application time ranged from 5.40 min (for composite resin) to 8.09 min (for LED thermocured HVGIC), and the average cost per sealant for 1,000 performed per group (simulation sample) ranged from $US3.73 (for composite resin) to $US7.50 (for glass-carbomer). The incremental cost-effectiveness of LED thermocured HVGIC to prevent one additional caries lesion per 1,000 sealants performed was $US1,106 compared with composite resin. Sensitivity analyses showed that differences in the cost of materials across groups had minimal impact on the overall cost. Cost and effectiveness data enhance policymakers' ability to address issues of availability, access, and compliance associated with poor oral-health outcomes, particularly when large numbers of children are excluded from care, in economies where oral health services are still developing. PMID:24799118

  16. Effect of the CO2 laser on the microleakage of conventional and laser apicetomized teeth retrofilled with glass ionomer: in vitro study

    NASA Astrophysics Data System (ADS)

    Pinheiro, Antonio L. B.; Martorelli, Sergio B. F.

    2000-03-01

    There is a need for further improvement on the level of apical sealing. The use of lasers on apical surgery is still not fully understood, however some good results have been reported. The aim of this study was to assess the effect of the use of the CO2 laser following conventional apicoectomy and retrofilling with glass ionomer using different combinations of power and types of emission 'In Vitro.' Seventy extracted human upper anterior teeth were used on this study. The teeth after conventional apicoectomy were retrofilled with VitremerTM. The samples were randomized into seven groups of 10, Group I acted as negative control. Groups II, III and IV were lased on defocused mode with superpulsed CO2 laser on CW with power output of 0,5; 3 and 7 Watts during 5 seconds respectively. Groups V, VI e VII were lased on defocused mode with continuous emission on CW mode with power output of 1, 10 and 20 Watts during 5 seconds respectively. All specimens were immersed on 2% Methylene Blue solution during 48 h, washed in running tap water and longitudinally sectioned. Three calibrated examiners regarding apical infiltration graded the samples. The results showed difference between groups, where Group II showed smaller level of apical infiltration. It is concluded that improving on apical sealing is better achieved by using 0.5 W on superpulsed on CW.

  17. Absence of carious lesions at margins of glass-ionomer cement (GIC) and resin-modified GIC restorations: a systematic review.

    PubMed

    Mickenautsch, Steffen; Tyas, Martin J; Yengopal, Veerasamy; Oliveira, Luciana B; Bönecker, Marcelo

    2010-09-01

    This systematic review sought to quantitatively answer the question as to whether, in tooth cavities of the same size, type of dentition and follow-up period, resin-modified glass-ionomer (GIC) restorations, when compared to conventional GIC restorations, offer a significant caries preventive effect, as measured by the absence of caries lesions at the margin of restorations. Six databases were searched for articles in English, Portuguese or Spanish until 07 May 2009. Four articles were accepted and 22 separate datasets extracted. The difference between both types of material were computed as relative risk (RR) with 95% confidence interval (CI). No meta-analysis was undertaken due to aspects of clinical/methodological heterogeneity. The results of the extracted datasets ranged between RR 0.90 (95% CI 0.81-1.01) and 1.08 (95% CI 0.71-1.63; p > 0.05) indicating no difference in the caries preventive effect between both types of materials. Further high-quality randomized control trials are needed in order to confirm these results. PMID:21077424

  18. Influence of air-abrasion executed with polyacrylic acid-Bioglass 45S5 on the bonding performance of a resin-modified glass ionomer cement.

    PubMed

    Sauro, Salvatore; Watson, Timothy F; Thompson, Ian; Toledano, Manuel; Nucci, Cesare; Banerjee, Avijit

    2012-04-01

    The aim of this study was to test the microtensile bond strength (?TBS), after 6 months of storage in PBS, of a resin-modified glass ionomer cement (RMGIC) bonded to dentine pretreated with Bioglass 45S5 (BAG) using various etching and air-abrasion techniques. The RMGIC (GC Fuji II LC) was applied onto differently treated dentine surfaces followed by light curing for 30 s. The specimens were cut into matchsticks with cross-sectional areas of 0.9 mm(2). The ?TBS of the specimens was measured after 24 h or 6 months of storage in PBS and the results were statistically analysed using two-way anova and the Student-Newman-Keuls test (? = 0.05). Further RMCGIC-bonded dentine specimens were used for interfacial characterization, micropermeability, and nanoleakage analyses by confocal microscopy. The RMGIC-dentine interface layer showed no water absorption after 6 months of storage in PBS except for the interdiffusion layer of the silicon carbide (SiC)-abraded/polyacrylic acid (PAA)-etched bonded dentine. The RMGIC applied onto dentine air-abraded with BAG/H(2)O only or with BAG/PAA-fluid followed by etching procedures (10% PAA gel) showed no statistically significant reduction in ?TBS after 6 months of storage in PBS. The abrasion procedures performed using BAG in combination with PAA might be a suitable strategy to enhance the bonding durability and the healing ability of RMGIC bonded to dentine. PMID:22409224

  19. Comparison of Marginal Microleakage of Glass Ionomer Restorations in Primary Molars Prepared by Chemo-mechanical Caries Removal (CMCR), Erbium: Yttrium Aluminum-Garnet (Er:YAG) Laser and Atraumatic Restorative Technique (ART)

    PubMed Central

    Juntavee, Niwut; Peerapattana, Jomjai; Nualkaew, Nartsajee; Sutthisawat, Sitikorn

    2013-01-01

    ABSTRACT Background: It is important to emphasize that the aspects of pretreatment techniques, as well as the composition and mechanism of adhesion, may decisively influence the effectiveness of the restorative materials in sealing cavity margins and preventing marginal leakage. Aims: This study assessed the in vitro influence of surface preparation techniques on the microleakage of glass ionomer restorations in primary teeth. Materials and methods: The study groups were divided into three different techniques: (1) The chemomechanical caries removal (CMCR) method using the Apacaries gel, (2) the erbium:yttrium aluminum-garnet (Er:YAG) laser method and (3) the atraumatic restorative technique (ART). The teeth restored with a glass ionomer restorative material (Fuji IX GP capsule, GC Corporation, Tokyo, Japan). The dye penetration was measured in micrometers using a polarized light microscope and specific computer software. Results: The results showed that the mean microleakage level after was lowest with the CMCR method using Apacaries gel and highest with the Er:YAG laser. There was a statistically significant difference regarding the mean microleakage level between the group with the CMCR method using Apacaries gel and the Er:YAG laser. Conclusion: Marginal leakage was significantly higher with preparations made using the Er:YAG laser than with the CMCR method using Apacaries gel and spoon excavator (p < 0.05). How to cite this article: Juntavee A, Juntavee N, Peerapattana J, Nualkaew N, Sutthisawat S. Comparison of Marginal Microleakage of Glass Ionomer Restorations in Primary Molars Prepared by Chemomechanical Caries Removal (CMCR), Erbium: Yttrium Aluminum-Garnet (Er:YAG) Laser and Atraumatic Restorative Technique (ART). Int J Clin Pediatr Dent 2013;6(2):75-79. PMID:25206196

  20. Efficiency of Amorphous Calcium Phosphate–Containing Orthodontic Composite and Resin Modified Glass Ionomer on Demineralization Evaluated By a New Laser Fluorescence Device

    PubMed Central

    Uysal, Tancan; Amasyali, Mihri; Koyuturk, Alp Erdin; Sagdic, Deniz

    2009-01-01

    Objectives: The aim of this in vitro study was to compare the efficacy of Amorphous Calcium Phosphate (ACP)-containing orthodontic composite and resin-modified glass ionomer cement (RMGIC) on enamel demineralization adjacent to orthodontic brackets evaluated by a new laser fluorescence device. Methods: Sixty extracted maxillary premolars were used in the present study. Twenty orthodontic brackets were bonded with ACP-containing orthodontic adhesive (Aegis-Ortho), 20 were bonded with RMGIC (Fuji Ortho LC) and 20 were bonded with Transbond XT composite as the control. All samples were then cycled for 21 days through a daily procedure of demineralization for 6 hours and remineralization for 17 hours. After this procedure, demineralization evaluations were undertaken by a pen-type laser fluorescence device (DIAGNO-dent Pen). Analysis of variance (ANOVA) and Tukey test was used for statistical evaluation, at P<.05 level. Results: According to ANOVA, significant demineralization variations (?D) were determined among groups (F=6.650; P<.01). The ACP-containing composite showed the lowest (mean: 8.98±2.38) and the control composite showed the highest (mean:12.15±3.83) ?D, during 21 days demineralization process (P<.01). Significant difference was also observed between the ?D scores of the RMGIC (mean: 9.24±2.73) and control (P<.05). No significant differences was found in preventive effects of ACP-containing composite and RMGIC (P<.05) against demineralization. Conclusions: The use of both ACP-containing orthodontic composite and RMGIC should be recommended for any at-risk orthodontic patient to provide preventive actions and potentially remineralize subclinical enamel demineralization. PMID:19421393

  1. Evaluation of the Effect of Different Food Media on the Marginal Integrity of Class V Compomer, Conventional and Resin-Modified Glass-Ionomer Restorations: An In Vitro Study

    PubMed Central

    Dinakaran, Shiji

    2015-01-01

    Background: Cervical lesions of anterior and posterior teeth are a common finding in routine dental practice. They are of much concern to the patient, if present in esthetically sensitive regions. Adhesive tooth-colored restorative materials are generally recommended for treating such lesions. The aim of the present study was to evaluate and compare the effect of various food media (lime juice, tea, coffee, and Coca-Cola) on the marginal integrity of Class V compomer (Dyract®), conventional glass-ionomer (Fuji II) and resin-modified glass-ionomer (Fuji II LC improved) restorations along their cemental and enamel margins with saline as control media. Materials and Methods: After restoration of prepared Class V cavities in human premolars with the three different materials (n = 8), they were immersed in the test media for 7 days and then stained with methylene blue dye. Buccolingual sections were prepared and examined under stereomicroscope and scores (0-2) were given. Results: Data were analyzed statistically using one-way analysis of variance in SPSS version 16.0. P < 0.05 were considered statistically significant. Conclusions: Among the three tested materials Compomer (Dyract®) showed more marginal integrity than the other two. Micro leakage values of Fuji II and Fuji II LC improved were statistically significant in acidic media (lime juice and Coca-Cola) compared to saline. Enamel margins showed more marginal adaptation than cemental margins. PMID:25878480

  2. Do Laboratory Results Concerning High-Viscosity Glass-Ionomers versus Amalgam for Tooth Restorations Indicate Similar Effect Direction and Magnitude than that of Controlled Clinical Trials? - A Meta-Epidemiological Study

    PubMed Central

    Mickenautsch, Steffen; Yengopal, Veerasamy

    2015-01-01

    Background A large percentage of evidence concerning dental interventions is based on laboratory research. The apparent wealth of laboratory evidence is sometimes used as basis for clinical inference and recommendations for daily dental practice. In this study two null-hypotheses are tested: whether trial results from laboratory and controlled clinical trials concerning the comparison of high-viscosity glass-ionomer cements (HVGIC) to amalgam for restorations placed in permanent posterior teeth have: (i) similar effect direction and (ii) similar effect magnitude. Methods 7 electronic databases were searched, as well as reference lists. Odds ratios (OR) and Standardised Mean Differences (SMD) with 95% Confidence intervals were computed for extracted dichotomous and continuous data, respectively. Pooled effect estimates for laboratory and clinical data were computed to test for effect direction. Odds ratios were converted into SMDs. SMDs from laboratory and clinical data were statistically compared to test for differences in effect magnitude. The analysed results were further investigated within the context of potential influencing or confounding factors using a Directed acyclic graph. Results Of the accepted eight laboratory and nine clinical trials, 13 and 21 datasets could be extracted, respectively. The pooled results of the laboratory datasets were highly statistically significant in favor of amalgam. No statistically significant differences, between HVGICs and amalgam, were identified for clinical data. For effect magnitude, statistically significant differences between clinical and laboratory trial results were found. Both null-hypotheses were rejected. Conclusion Laboratory results concerning high-viscosity glass-ionomers versus amalgam for tooth restorations do not indicate similar effect direction and magnitude than that of controlled clinical trials. PMID:26168274

  3. An in vitro study of apical and coronal microleakage of laterally condensed gutta percha with Ketac-Endo and AH-26.

    PubMed

    Oliver, C M; Abbott, P V

    1998-08-01

    The purpose of this in vitro study was to compare both apical and coronal dye penetration when Ketac-Endo and AH-26 sealers were used with laterally condensed gutta percha. Crowns were removed from 28 teeth and the root canals were biomechanically prepared. The teeth were divided into two groups of 12-teeth each and a control group of 4 teeth. Root canals in the two experimental groups were filled with laterally condensed gutta percha and either Ketac-Endo or AH-26 sealer. The Ketac-Endo group had the coronal 3 mm of gutta percha and sealer removed and the resultant cavity was filled with Ketac-Endo alone. After the sealers had set, the root surfaces were coated with nail varnish except at the apex and at the coronal end. Positive controls had no root fillings and were coated with nail varnish in the same manner while the negative controls were sealed apically and coronally with Cavit prior to sealing the entire external root surface with nail varnish. Specimens were placed in 2% methylene blue dye in a vacuum of 660 mm of mercury for five minutes and then left immersed for a further two days. The roots were vertically sectioned to determine the following mean levels of dye penetration: Ketac-Endo, 1.08 mm apically and 6.29 mm coronally; AH-26, 0.75 mm apically and 6.67 mm coronally. Positive controls had total leakage and negative controls had no leakage. This study demonstrated that the apical and coronal seals obtained with Ketac-Endo and AH-26 were not significantly different although the apical seal obtained with each material was significantly better than the corresponding coronal seal. PMID:9775474

  4. Comparison of marginal adaptation of mineral trioxide aggregate, glass ionomer cement and intermediate restorative material as root-end filling materials, using scanning electron microscope: An in vitro study

    PubMed Central

    Gundam, Sirisha; Patil, Jayaprakash; Venigalla, Bhuvan Shome; Yadanaparti, Sravanthi; Maddu, Radhika; Gurram, Sindhura Reddy

    2014-01-01

    Aim: The present study compares the marginal adaption of Mineral Trioxide Aggregate (MTA), Glass Ionomer Cement (GIC) and Intermediate Restorative Material (IRM) as root-end filling materials in extracted human teeth using Scanning Electron Microscope (SEM). Materials and Methods: Thirty single rooted human teeth were obturated with Gutta-percha after cleaning and shaping. Apical 3 mm of roots were resected and retrofilled with MTA, GIC and IRM. One millimeter transverse section of the retrofilled area was used to study the marginal adaptation of the restorative material with the dentin. Mounted specimens were examined using SEM at approximately 15 Kv and 10-6 Torr under high vacuum condition. At 2000 X magnification, the gap size at the material-tooth interface was recorded at 2 points in microns. Statistical Analysis: One way ANOVA Analysis of the data from the experimental group was carried out with gap size as the dependent variable, and material as independent variable. Results: The lowest mean value of gap size was recorded in MTA group (0.722 ± 0.438 ?m) and the largest mean gap in GIC group (1.778 ± 0.697 ?m). Conclusion: MTA showed least gap size when compared to IRM and GIC suggesting a better marginal adaptation. PMID:25506146

  5. Counterion Diffusion in Ionomers

    NASA Astrophysics Data System (ADS)

    Walter, Russell; Winey, Karen; Kim, Joon-Seop; Composto, Russell

    2004-03-01

    Diffusion of Cs counterions to the air/ionomer film interface is followed using Rutherford backscattering spectrometry and results compared with the "sticky reptation" model[1]. The ionomer system is poly(styrene-ran-methacrylic acid) (Cs-SMAA) neutralized at 100% by Cs. The concentration profiles exhibit a surface excess, z*, of Cs followed by a depletion of Cs. The z* and depletion layer thickness grow as t1/2, consistent with diffusion limited growth. Annealing studies at 130 °C, 145 °C and 208 °C were used to extract the diffusion coefficient, D. In all cases, D is greater than that of the matrix chains. These results suggest that the diffusion rate is controlled by the fraction of counterions that disassociate from the acid groups and migrate through the matrix. Moreover, the "sticky reptation" model doesn't appear to predict the diffusion behavior in the Cs-SMAA system. [1] Leibler, L, Ludwick, L., Rubinstein, M., Colby, R.H., Macromolecules 24 (1991) 4701.

  6. Viscoelastic Behavior of Low Molecular Weight Sulfonated Polystyrene Ionomers

    NASA Astrophysics Data System (ADS)

    Zhao, Hongying

    Ionomers are those hydrophobic polymers having small amounts of bonded ionic groups. The introduction of the ionic groups into polymer chain produces large changes in the physical, mechanical and rheological properties of the parent polymer. Characterization of the effect of the ionic interactions on the rheology is complicated by the difficulty in separating effects due to molecular entanglements and the ionic interactions. In this study, low molecular weight (Mw=4000) sulfonated polystyrene (SPS) was used to study the dynamic and steady shear rheology of SPS ionomers. The polymer chain length used was far below the entanglement molecular weight of polystyrene and effects of molecular entanglements will be absent. Any polymer chain entanglements or lengthening behavior on the melt rheology should be due to the ionic interactions. Random SPS ionomers with two sulfonation levels were examined, 2.5 and 4.8 mol%, which corresponded, respectively, to one and two sulfonate groups per chain on average. The metal counterions was varied across the alkali metal series of the periodic table. Morphology of the ionomer was characterized by using small angle x-ray scattering (SAXS) analysis, and dynamic and steady shear measurements were performed to investigate rheological behavior of the ionomers. Glass transition temperatures of the ionomers increased with increasing ion concentration but were insensitive to cation used. The scattering peak in SAXS indicates the existence of the nanophase separated ionic clusters. The strong ionic nanophase persist up to very high temperatures and is not sensitive to the external stress. Time-temperature superposition (TTS) of G' worked reasonably well while TTS of G" failed for most ionomers. Ionic interactions increased the terminal relaxation time of the melts as much as seven orders of magnitude greater than the unentangled PS melt. The zero shear viscosity and first normal stress coefficients scaled with cq/a, where c was the concentration of the ionic groups, q was the charge of the cation, and a was the cation radius. The flow activation energy of the ionomers was similar to that of high molecular weight PS and the calculated molecular weight between "entanglements" (Me) of the SPS4.8 ionomers was the same as for PS. However, SPS2.5 ionomers contain more inactive chains that do not contribute to the melt elasticity and lead to the higher Me value. All ionomers exhibit Newtonian flow behavior at low shear rates and shear thinning behavior were observed for SPS2.5 ionomers. However, shear thickening were found for LiSPS2.5 and NaSPS2.5 under lower temperatures and up to some critical shear rate. The shear thickening is believed to be due to the mechanism that the interchain association of the chains increases as they are deformed in the shear flow. The larger complexes that formed at higher shear rates lead to higher viscosities.

  7. Proton exchange membranes based on the short-side-chain perfluorinated ionomer

    NASA Astrophysics Data System (ADS)

    Ghielmi, A.; Vaccarono, P.; Troglia, C.; Arcella, V.

    Due to the renovated availability of the base monomer for the synthesis of the short-side-chain (SSC) perfluorinated ionomer, fuel cell membrane development is being pursued using this well known ionomer structure, which was originally developed by Dow in the 1980s. The new membranes under development have the trade name Hyflon Ion. After briefly reviewing the literature on the Dow ionomer, new characterization data are reported on extruded Hyflon Ion membranes. The data are compared to those available in the literature on the Dow SSC ionomer and membranes. Comparison is made also with data obtained in this work or available in the literature on the long-side-chain (LSC) perfluorinated ionomer (Nafion). Thermal, visco-elastic, water absorption and mechanical properties of Hyflon Ion are studied. While the general behavior is similar to that shown in the past by the Dow membranes, slight differences are evident in the hydration behavior at equivalent weight (EW) < 900, probably due to different EW distributions. Measurements on dry membranes confirm that Hyflon Ion has a higher glass transition temperature compared to Nafion, which makes it a more promising material for high temperature proton exchange membrane (PEM) fuel cell operation ( T > 100 °C). Beginning of life fuel cell performance has also been confirmed to be higher than that given by a Nafion membrane of equal thickness.

  8. Multielement Analytical Spectroscopy in Plant Ionomics Research

    Microsoft Academic Search

    Rumyana Djingova; Veronika Mihaylova; Valentina Lyubomirova; Dimiter L. Tsalev

    2012-01-01

    The study of the ionome (ionomics) is defined as quantitative and simultaneous measurement of the element composition of living organisms and changes in this composition in response to physiological stimuli, development stage and genetic modifications (Salt et al. 2008). The necessity to understand the regulation processes of elements in the organisms demands determination of many elements in organism, tissue and cell

  9. Structural studies of polyurethane ionomer solutions

    NASA Astrophysics Data System (ADS)

    Nomula, Srinivas; Cooper, Stuart

    1996-03-01

    Except for a number of conductivity and viscometric measurements, structural studies of polyurethane ionomer solutions are lacking in literature. Polyurethane ionomers in polar solvents are shown to exhibit polyelectrolyte behavior. So these ionomer solutions also form model systems to investigate the characteristic behavior of salt free polyelectrolyte solutions. In this study, viscometry and light scattering experiments have been performed on model polyurethane ionomers, which have regularly positioned ionic groups. The model system is synthesized as a 1:1 copolymer of polytetramethylene oxide (PTMO) and 4-4'-diphenyl methane diisocyanate (MDI) which is subsequently ionized by abstraction with sodium hydride (NaH) and derivatization with 1,3 propane sultone. The separation distance between the ionic groups is varied by varying the molecular weight of PTMO. Viscometric measurements of these ionomers in a polar solvent, N,N-dimethyl acetamide (DMAc), have verified that they exhibit polyelectrolyte behavior. Static and Dynamic Light Scattering have been applied to these ionomer solutions to reveal important information about the structures in solution. The results of the analysis of the light scattering data will be presented.

  10. Oxygen reduction at platimun/ionomer interface: effects of phase separation of ionomer

    SciTech Connect

    Chlistunoff, Jerzy [Los Alamos National Laboratory

    2008-01-01

    Oxygen reduction reaction (ORR) at the interface between platinum and recast ionomers (Nafion EW 1100 and 950 and 6F-40) was studied at different temperatures (20--80{sup o}C) and humidities (10--100%) employing smooth Pt and Pt-black-covered ultramicroelectrodes. ORR was strongly inhibited on smooth electrodes. The inhibition increased with the reduction time, temperature and humidity, but was absent for Nafion EW 1100 in contact with liquid water. It was attributed to the hydrophobic component of ionomer blocking both active sites and oxygen transport. It was postulated that the dynamic changes in interfacial phase separation of ionomer are facilitated by the attractive interactions between the hydrophobic component of ionomer and bare platinum and between oxide-covered Pt and the hydrophilic component of ionomer. These interactions were also proposed to be responsible for the differences in ORR voltammetry for films prepared and equilibrated under different conditions. The decrease in ORR inhibition, Nafion EW 950> Nafion EW 1100> 6F-40, was correlated with physical and molecular properties of the ionomers. The lack of inhibition for Pt-black-covered electrodes was attributed to the more random distribution of ionomer chains and the high activation barriers for the ionomer restructuring at rough interfaces.

  11. Effect of Ion Content on Conductivity and Morphology of Single-Ion Conducting Ionomers

    NASA Astrophysics Data System (ADS)

    Wang, Jing-Han Helen; Colby, Ralph H.

    2013-03-01

    Ionomers based on short poly(ethylene oxide) side chains and sodium sulfonated styrene are synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization, to systematically study the effect of ion content and counterion species on ionic conductivity. Glass transition temperature increases gradually as ions are incorporated at low ion content then sharply as the ion content reaches 1:4 ions to ether oxygen (EO) ratio. Dielectric relaxation spectroscopy is used to measure the conductivity, dielectric constant and segmental relaxations in these ionomers. The ionomer with 1:80 ions to EO ratio shows highest room temperature conductivity that results from the best combination of number density of simultaneously conducting ions and their mobility, assessed by an electrode polarization model. The micro-phase separation that is anticipated in the ionomers with higher ion contents is probed by x-ray scattering. Sodium counterions are mostly trapped in ionic aggregates while larger counterions, such as tetramethylammonium, exhibit higher conductivity and conducting ion concentration.

  12. Molecular mobility, morphology, and ion conduction in ionomers for electroactive devices

    NASA Astrophysics Data System (ADS)

    Tudryn, Gregory J.

    A sequential study of ion-containing polymers capable of ion solvation with varied ion content, dielectric constant, and counterions is presented in this dissertation in order to compare ion transport properties in ionomers with various ionic interactions. Structure-property relationships in these ion containing polymers are defined using x-ray scattering, rheology and dielectric spectroscopy, enabling the quantification of ion transport dynamics. Poly(ethylene oxide), (PEO) based ionomers are investigated in order to probe the relation between ion conduction and segmental relaxation, and copolymers of PEO and Poly(tetramethylene oxide), (PTMO) further develop an understanding of the trade-off between ion solvation and segmental dynamics. Ionomers with ionic liquid counterions probe diffuse charge interactions and steric effects on ion transport, and incorporation of ionic liquids into ionomer membranes such as Nafion provides desirable thermal and ion conducting properties which extend the use of such membranes for electroactive devices. PEO ionomers exhibit a strong relation between ionic conductivity and segmental dynamics, providing insight that the glass transition temperature, Tg, dominates the ion conduction mechanism. Increasing temperature induces aggregation of ionic groups as evidenced by the static dielectric constant and X-ray scattering as a function of temperature, revealing the contribution of ionic dipoles in the measured dielectric constant. The trade-off between ion solvation and fast polymer segmental dynamics are quantified in copolymer ionomers of PEO and lower Tg PTMO. While conducting ion content remains nearly unchanged, conductivity is lowered upon incorporation of PTMO, because the vast majority of the PTMO microphase separates from the PEO-rich microdomain that remains continuous and contributes most of the ion conduction. Dielectric constants and X-ray scattering show consistent changes with temperature that suggest a cascading aggregation process in Na ionomers as ionic dipoles thermally randomize and lower the measured dielectric constant of the medium, leading to further aggregation. We observe amplified microphase-separation through ionic groups preferentially solvated by PEO chains, as seen in block copolymers with added salt. Even at 25%PEO / 75%PTMO the ionomers have VFT temperature dependence of conducting ion mobility, meaning that the 25% PEO/ion microphase is still continuous A model is developed to describe the frequency dependent storage and loss modulus and the delay in Rouse motion due to ion association lifetime, as functions of ion content and molecular weight for our low molecular weight ionomers. The ion rearrangement relaxation in dielectric spectroscopy is clearly the ion association lifetime that controls terminal dynamics in linear viscoelasticity, allowing a simple sticky Rouse model, using the most-probable distribution based on NMR Mn, to fully describe master curves of the frequency dependent storage and loss modulus. Using insight from ionic interaction strength, ionic liquids are used as counterions, effectively plasticizing the ionomers without added solvent. Ionic interactions were weakened with increasing counterion size, and with modification of cations using ether-oxygen, promoting self-solvation, which increases conducting ion density by an order of magnitude. Room temperature ionic liquids were subsequently used in combination with NafionRTM membranes as electroactive substrates to correlate ion transport to morphology as a function of volume fraction of ionic liquid. This study illuminated the critical volume uptake of ionic liquid in Nafion, identifying percolation of ionic pathways and a significant increase in dielectric constant at low frequencies, indicating an increase in the number density of ions capable of polarizing at the electrode surface. Consequently, the fundamental information obtained about the structure-property relations of ionomers can be used to predict and design advanced ion-containing polymers to be used in battery membranes and a v

  13. Fabrication technology to increase surface area of ionomer membrane material and its application towards high surface area electric double-layer capacitors

    NASA Astrophysics Data System (ADS)

    Chang, Alberto A.; Patel, Jasbir N.; Cordoba, Cristina; Kaminska, Bozena; Kavanagh, Karen

    2014-03-01

    An application friendly technique to increase the surface area of the ionomer membrane such as Aquivion™ has been developed. By utilizing existing micro-fabrication technologies, square pillars were fabricated onto glass and silicon substrates. In combination with a low cost heat press, the glass and silicon stamps were used to successfully hot emboss micro-features onto the ionomer membrane. Consequently, the surface area of the Aquivion™ membrane was drastically increased enabling potential improvement of sensing and energy storage technologies. Preliminary results show successful fabrication of devices with systematic higher surface area and an improved capacitance.

  14. Nanoscale Morphology of Sulfonated Polystyrene Ionomers

    NASA Astrophysics Data System (ADS)

    Zhou, Nancy C.; Winey, Karen I.

    2007-03-01

    We have applied our scanning transmission electron microscopy (STEM) methods to investigate the size, shape and spatial distribution of the ionic, nanoscale aggregates in poly(styrene-ran-styrene sulfonate) (P(S-SSx)) ionomers. This analytical electron microscopy method minimizes phase contrast that can obscure nano-scale features and accentuates differences in atomic number. We recently reported quantitative agreement between STEM and X-ray scattering results in a Cu-neutralized poly(styrene-ran-methacrylic acid) (SMAA) ionomer with respect to the size of the ionic aggregates and their number density. For this study, P(S-SSx) ionomers were prepared by solution neutralizing with metal acetates, solution casting, and annealing. Initial STEM results from P(S-SS0.019) fully neutralized with Zn indicate a uniform distribution of monodisperse spherical aggregates. Combining direct imaging and X-ray scattering of P(S-SSx) ionomers, we will investigate the effect of cation type and level of neutralization.

  15. Ionomer Dynamics: Insights from Broadband Dielectric Spectroscopy

    NASA Astrophysics Data System (ADS)

    Runt, James

    2015-03-01

    Ionomers (polymers containing ionic functionality) have been traditionally used as packaging materials and in molding applications, and are now of increasing interest as candidate single ion conductors for energy storage devices, in energy conversion, and for other electroactive materials applications. The focus of this presentation is on the insight that broadband dielectric (impedance) spectroscopy brings to our understanding of ion and polymer dynamics of this family of materials. As an example of our recent work on relatively conductive ionomers, the first portion of the presentation will focus on anion conducting polyphosphazene ionomers, in which polymer bound cations are quaternized with either short alkyl or short ether oxygen chains. The low Tg, amorphous nature, and cation-solvating backbone distinguish polyphosphazenes as promising materials for ion conduction, the iodide variants being of particular interest in solar cells. In the second part of this overview, the first findings on the molecular dynamics of linear precise polyethylene-based ionomers containing 1-methylimidazolium bromide pendants on exactly every 9th, 15th, or 21st carbon atom will be summarized. In order to develop a robust interpretation of the dynamics of these materials, it is imperative to develop a thorough understanding of microphase separation (e.g. ion aggregation), and each of the above studies is complimented by multiangle X-ray scattering experiments. Supported by the NSF Polymers Program and DOE Basic Energy Sciences.

  16. Morphological analysis of ionomers. Progress report, August 1, 1987--December 31, 1991

    SciTech Connect

    Not Available

    1991-12-31

    Anomalous small-angle x-ray scattering (SAXS) investigations were carried out on amorphous and semi-crystalline ionomers (Ni- neutralized sulfonated polystyrene ionomers, polyurethane ionomer). Ionomers with semicrystalline matrices (three-phase materials) were also studied with SAXS (poly(ethylene-co-methacrylic acid) ionomer). Ethylene oxide units were incorporated into the backbone of sulfonated polyurethane ionomers in an attempt to induce aggregate dissociation. Small-angle neutron scattering was used to study the effect of ionic aggregation on ionomer chain dimensions in telechelic and model polyurethane ionomers. Studies have been completed on carboxylated and sulfonated model polyurethane ionomers in order to determine the effect of the pendant ionic group on ionomer structure- property relationships (mechanical properties). (DLC)

  17. Phase transition in polymer blends and structure of ionomers

    SciTech Connect

    Chu, B.

    1989-01-01

    Progress is briefly reported on small angle x-ray scattering measurements (SAXS) of the following: solutions of polystyrene- polyisoprene AB block copolymer in aniline; gelatin; sulfonated polystyrene ionomers; and lead sulfides. 20 figs., 1 tab. (CBS)

  18. Enamel and Cementum Fluoride Uptake from a Glass Ionomer Cement

    Microsoft Academic Search

    D. H. Retief; E. L. Bradley; J. C. Denton; P. Switzer

    1984-01-01

    Class V cavities were prepared at the cemento-enamel junction on the facial surfaces of 45 extracted human central maxillary incisors. Enamel samples for analysis were obtained by means of perchloric acid etching from circular areas, 1 mm in diameter, positioned 1.5, 3.5, 5.5, and 7.5 mm from the incisal and apical margins of the restorations, respectively. The preparations were filled

  19. Novel polyurethane ionomer nanoparticles displayed a good biosensor effection

    Microsoft Academic Search

    Wenbo Zhao; Guohui Zhang; Lancao Jiang; Tianhong Lu; Xiaohua Huang; Jian Shen

    2011-01-01

    This study described the bioelectrochemistry property of hemoglobin (Hb) on biopolymer film of polyurethane ionomer nanoparticles (PUI-NPs) noncovalently functionalized with multiwall carbon nanotubes (MWCNTs). The polyurethane ionomer nanoparticles (PUI-NPs) were synthesized by emulsion polymerization, and could provide a good biocompatible microenvironment for Hb immobilization. The characteristic of (PUI-NPs)\\/MWCNTs and Hb\\/(PUI-NPs)\\/MWCNTs composite films were performed by using transmission electron microscopy (TEM),

  20. Proton exchange membranes based on the short-side-chain perfluorinated ionomer

    Microsoft Academic Search

    A. Ghielmi; P. Vaccarono; C. Troglia; V. Arcella

    2005-01-01

    Due to the renovated availability of the base monomer for the synthesis of the short-side-chain (SSC) perfluorinated ionomer, fuel cell membrane development is being pursued using this well known ionomer structure, which was originally developed by Dow in the 1980s. The new membranes under development have the trade name Hyflon Ion. After briefly reviewing the literature on the Dow ionomer,

  1. The Plant Ionome Revisited by the Nutrient Balance Concept

    PubMed Central

    Parent, Serge-Étienne; Parent, Léon Etienne; Egozcue, Juan José; Rozane, Danilo-Eduardo; Hernandes, Amanda; Lapointe, Line; Hébert-Gentile, Valérie; Naess, Kristine; Marchand, Sébastien; Lafond, Jean; Mattos, Dirceu; Barlow, Philip; Natale, William

    2013-01-01

    Tissue analysis is commonly used in ecology and agronomy to portray plant nutrient signatures. Nutrient concentration data, or ionomes, belong to the compositional data class, i.e., multivariate data that are proportions of some whole, hence carrying important numerical properties. Statistics computed across raw or ordinary log-transformed nutrient data are intrinsically biased, hence possibly leading to wrong inferences. Our objective was to present a sound and robust approach based on a novel nutrient balance concept to classify plant ionomes. We analyzed leaf N, P, K, Ca, and Mg of two wild and six domesticated fruit species from Canada, Brazil, and New Zealand sampled during reproductive stages. Nutrient concentrations were (1) analyzed without transformation, (2) ordinary log-transformed as commonly but incorrectly applied in practice, (3) additive log-ratio (alr) transformed as surrogate to stoichiometric rules, and (4) converted to isometric log-ratios (ilr) arranged as sound nutrient balance variables. Raw concentration and ordinary log transformation both led to biased multivariate analysis due to redundancy between interacting nutrients. The alr- and ilr-transformed data provided unbiased discriminant analyses of plant ionomes, where wild and domesticated species formed distinct groups and the ionomes of species and cultivars were differentiated without numerical bias. The ilr nutrient balance concept is preferable to alr, because the ilr technique projects the most important interactions between nutrients into a convenient Euclidean space. This novel numerical approach allows rectifying historical biases and supervising phenotypic plasticity in plant nutrition studies. PMID:23526060

  2. Self-Healing Behavior of Ethylene-Based Ionomers

    NASA Technical Reports Server (NTRS)

    Kalista, Stephen J., Jr.; Ward, Thomas C.; Oyetunji, Zainab

    2004-01-01

    The self-healing behavior of poly(ethylene-co-methacrylic acid) (EMAA)-based ionomers holds tremendous potential for use in a wide variety of unique applications. However, to effectively utilize this self-healing behavior and to design novel materials which possess this ability, the mechanism by which they heal must first be understood ionomers are a class of polymers that can be described as copolymers containing less than 15 mol% ionic content whereby the bulk properties are governed by ionic interactions within the polymer. These ionic groups aggregate into discrete regions known as multiplets which overlap forming clusters that act as physical cross-links profoundly influencing the bulk physical properties. These clusters possess an order-disorder transition (T(sub i)) where the clustered regions may rearrange themselves given time and stimuli. Recognizing the strong influence of these ionic regions on other well understood ionomer properties, their role in self-heating behavior will be assessed. The self-healing behavior is observed following projectile puncture. It has been suggested that during impact energy is passed to the ionomer material, heating it to the melt state. After penetration, it is proposed that the ionic regions maintain their attractions and flow together patching the hole. Thus, the importance of this ionic character and is unique interaction must be established. This will be accomplished through examination of materials with varying ionic content and through the analysis of the T(sub i). The specific ionomer systems examined include a number of ethylene-based materials. Materials of varying ionic content, including the non-ionic base copolymers, will be examined by peel tests, projectile impact and DSC analysis. The information will also be compared with some basic data on LDPE material.

  3. Simulation of Ionic Aggregation and Ion Dynamics in Model Ionomers

    NASA Astrophysics Data System (ADS)

    Frischknecht, Amalie L.

    2012-02-01

    Ionomers, polymers containing a small fraction of covalently bound ionic groups, are of interest as possible electrolytes in batteries. A single-ion conducting polymer electrolyte would be safer and have higher efficiency than the currently-used liquid electrolytes. However, to date ionomeric materials do not have sufficiently high conductivities for practical application. This is most likely because the ions tend to form aggregates, leading to slow ion transport. A key question is therefore how molecular structure affects the ionic aggregation and ion dynamics. To probe these structure-property relationships, we have performed molecular simulations of a set of recently synthesized poly(ethylene-co-acrylic acid) copolymers and ionomers, with a focus on the morphology of the ionic aggregates. The ionomers have a precise, constant spacing of charged groups, making them ideal for direct comparisons with simulations. Ab initio calculations give insight into the expected coordination of cations with fragments of the ionomers. All-atom molecular dynamics (MD) simulations of the ionomer melt show aggregation of the ionic groups into extended string-like clusters. An extensive set of coarse-grained molecular dynamics simulations extend the results to longer times and larger length scales. The structure factors calculated from the MD simulations compare favorably with x-ray scattering data. Furthermore, the simulations give a detailed picture of the sizes, shapes, and composition of the ionic aggregates, and how they depend on polymer architecture. Implications for ion transport will be discussed. [Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  4. Low equivalent weight short-side-chain perfluorosulfonic acid ionomers in fuel cell cathode catalyst layers

    Microsoft Academic Search

    Chao Lei; Dmitri Bessarabov; Siyu Ye; Zhong Xie; Steven Holdcroft; Titichai Navessin

    2011-01-01

    The morphology and fuel cell performance of cathode catalyst layers (CCLs) using low equivalent weight (EW) short-side-chain (SSC) perfluorosulfonic acid ionomers have been investigated in this work. The results were compared with those for a baseline CCL containing 30wt% of the conventional ionomer 1100 EW Nafion®. The CCLs fabricated with 10–20wt% of the Aquivion™ ionomer displayed a similar morphology to

  5. Blends of polyester ionomers with polar polymers: Interactions, reactions, and compatibilization

    NASA Astrophysics Data System (ADS)

    Boykin, Timothy Lamar

    The compatibility of amorphous and semicrystalline polyester ionomers with various polar polymers (i.e., polyesters and polyamides) has been investigated for their potential use as minor component compatibilizers. The degree of compatibility (i.e., ranging from incompatible to miscible) between the polyester ionomers and the polar polymers was determined by evaluating the effect of blend composition on the melting behavior and phase behavior of binary blends. In addition, the origin of compatibility and/or incompatibility for each of the binary blends (i.e., polyamide/ionomer and polyester/ionomer) was determined by evaluating blends prepared by both solution and melt mixed methods. Subsequent to investigation of the binary blends, the effect of polyester ionomer addition on the compatibility of polyamide/polyester blends was investigated by evaluating the mechanical properties and phase morphology of ionomer compatibilized polyamide/polyester blends. Polyester ionomers (amorphous and semicrystalline) were shown to exhibit a high degree of compatibility (even miscibility) with polyamides, such as nylon 6,6 (N66). Compatibility was attributed to specific interactions between the metal counterion of the polyester ionomer and the amide groups of N66. The degree of compatibility (or miscibility) was shown to be dependent on the counterion type of the ionomer, with the highest degree exhibited by blends containing the divalent form of the polyester ionomers. Although polyester ionomers were shown to exhibit incompatibility with both poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT), increasing the time of melt processing significantly enhanced the compatibility of the polyester ionomers with both PET and PBT. The observed enhancement in compatibility was attributed to ester-ester interchange between the polyester blend components, which was confirmed by NMR spectroscopy. The addition of polyester ionomers as a minor component compatibilizer (i.e., 2 to 5 wt%) resulted in significant enhancement in the impact strength and a dramatic improvement in the tensile properties compared to uncompatibilized blends of nylon 6,6 (N66) with poly(butylene terephthalate) (PBT). This behavior was attributed to an increase in the interfacial adhesion between the phase-separated domains due to strong interactions between the polyester ionomer and N66. The placement of the ionomer compatibilizer at the N66/PBT interface was facilitated by pre-extrusion of the polyester ionomer with PBT, prior to extrusion with N66.

  6. Control and characterization of textured, hydrophobic ionomer surfaces

    NASA Astrophysics Data System (ADS)

    Wang, Xueyuan

    Polymer thin films are of increasing interest in many industrial and technological applications. Superhydrophobic, self-cleaning surfaces have attracted a lot of attention for their application in self-cleaning, anti-sticking coatings, stain resistance, or anti-contamination surfaces in diverse technologies, including medical, transportation, textiles, electronics and paints. This thesis focuses on the preparation of nanometer to micrometer-size particle textured surfaces which are desirable for super water repellency. Textured surfaces consisting of nanometer to micrometer-sized lightly sulfonated polystyrene ionomer (SPS) particles were prepared by rapid evaporation of the solvent from a dilute polymer solution cast onto silica. The effect of the solvent used to spin coat the film, the molecular weight of the ionomer, and the rate of solvent evaporation were investigated. The nano-particle or micron-particle textured ionomer surfaces were prepared by either spin coating or solution casting ionomer solutions at controlled evaporation rates. The surface morphologies were consistent with a spinodal decomposition mechanism where the surface first existed as a percolated-like structure and then ripened into droplets if molecular mobility was retained for sufficient time. The SPS particles or particle aggregates were robust and resisted deformation even after annealing at 120°C for one week. The water contact angles on as-prepared surfaces were relatively low, ~ 90° since the polar groups in ionomer reduce the surface hydrophobicity. After chemical vapor deposition of 1H,1H,2H,2H-perfluorooctyltrichlorosilane, the surface contact angles increased to ~ 109° on smooth surfaces and ~140° on the textured surfaces. Water droplets stuck to these surfaces even when tilted 90 degrees. Superhydrophobic surfaces were prepared by spraying coating ionomer solutions and Chemical Vapor Deposition (CVD) of 1H,1H,2H,2H-perfluorooctyltrichlorosilane onto textured surfaces. The surfaces after CVD of silane exhibited water contact angle of 152° and the water droplet stuck to the surfaces without falling even when tilted upside down. This kind of sticky superhydrophobic surface would have potential applications in no-loss transport of liquid, and cleaning robots.

  7. Associations between Ionomic Profile and Metabolic Abnormalities in Human Population

    Microsoft Academic Search

    Liang Sun; Yu Yu; Tao Huang; Peng An; Danxia Yu; Zhijie Yu; Huaixing Li; Hongguang Sheng; Lu Cai; Jun Xue; Miao Jing; Yixue Li; Xu Lin; Fudi Wang

    2012-01-01

    BackgroundFew studies assessed effects of individual and multiple ions simultaneously on metabolic outcomes, due to methodological limitation.Methodology\\/Principal FindingsBy combining advanced ionomics and mutual information, a quantifying measurement for mutual dependence between two random variables, we investigated associations of ion modules\\/networks with overweight\\/obesity, metabolic syndrome (MetS) and type 2 diabetes (T2DM) in 976 middle-aged Chinese men and women. Fasting plasma ions

  8. High-performance alkaline ionomer for alkaline exchange membrane fuel cells L. Zeng, T.S. Zhao

    E-print Network

    Zhao, Tianshou

    High-performance alkaline ionomer for alkaline exchange membrane fuel cells L. Zeng, T.S. Zhao 2013 Keywords: Fuel cells Polysulfone Alkaline ionomer Cross-linking Diamine An alkaline ionomer the peak power density of H2/O2 alkaline exchange membrane fuel cells to 342 mW cm-2 . © 2013 Elsevier B

  9. Alkaline membrane fuel cells with in-situ cross-linked ionomers Yongjun Leng a

    E-print Network

    membranes (AEMs) as the solid polymer electrolyte to facilitate high pH cell operation have garnered recentAlkaline membrane fuel cells with in-situ cross-linked ionomers Yongjun Leng a , Lizhu Wang b membrane fuel cell (AMFC) in-situ cross-linking ionomer net water transport coefficient A B S T R A C

  10. Counterion Dynamics in Polyester-Sulfonate Ionomers with Ionic Liquid Counterions

    SciTech Connect

    Tudryn, Gregory J.; Liu, Wenjuan; Wang, Shih-Wa; Colby, Ralph H. (Penn)

    2012-04-02

    Conventional sodium cations (Na{sup +}) in sulfonated polyester ionomers were replaced with ammonium-based ionic liquid counterions. Counterion dynamics were measured by dielectric spectroscopy and linear viscoelastic response via oscillatory shear. Ion exchange from sodium counterions to ionic liquid counterions such as tetramethylammonium and tetrabutylammonium showed an order of 10{sup 4} increase in conductivity compared with sodium counterions, primarily attributed to weaker ionic interactions that lower the glass transition temperature. Electrode polarization was used in conjunction with the 1953 Macdonald model to determine the number density of conducting counterions and their mobility. Conductivity and mobility exhibit Vogel-Fulcher-Tammann (VFT) temperature dependences and both increased with counterion size. Conducting counterion concentrations showed Arrhenius temperature dependences, with activation energy reduced as counterion size increased. When ether-oxygen was incorporated into the mobile cation structure, self-solvating ability notably increased the conducting ion concentration. Weakened ion pairing interactions prove favorable for fundamental design of single-ion conductors for actuators, as ionic liquid counterions can provide both larger and faster strains, required by such electro-active devices.

  11. Purdue ionomics information management system. An integrated functional genomics platform.

    PubMed

    Baxter, Ivan; Ouzzani, Mourad; Orcun, Seza; Kennedy, Brad; Jandhyala, Shrinivas S; Salt, David E

    2007-02-01

    The advent of high-throughput phenotyping technologies has created a deluge of information that is difficult to deal with without the appropriate data management tools. These data management tools should integrate defined workflow controls for genomic-scale data acquisition and validation, data storage and retrieval, and data analysis, indexed around the genomic information of the organism of interest. To maximize the impact of these large datasets, it is critical that they are rapidly disseminated to the broader research community, allowing open access for data mining and discovery. We describe here a system that incorporates such functionalities developed around the Purdue University high-throughput ionomics phenotyping platform. The Purdue Ionomics Information Management System (PiiMS) provides integrated workflow control, data storage, and analysis to facilitate high-throughput data acquisition, along with integrated tools for data search, retrieval, and visualization for hypothesis development. PiiMS is deployed as a World Wide Web-enabled system, allowing for integration of distributed workflow processes and open access to raw data for analysis by numerous laboratories. PiiMS currently contains data on shoot concentrations of P, Ca, K, Mg, Cu, Fe, Zn, Mn, Co, Ni, B, Se, Mo, Na, As, and Cd in over 60,000 shoot tissue samples of Arabidopsis (Arabidopsis thaliana), including ethyl methanesulfonate, fast-neutron and defined T-DNA mutants, and natural accession and populations of recombinant inbred lines from over 800 separate experiments, representing over 1,000,000 fully quantitative elemental concentrations. PiiMS is accessible at www.purdue.edu/dp/ionomics. PMID:17189337

  12. Silk ionomers for encapsulation and differentiation of human MSCs.

    PubMed

    Calabrese, Rossella; Kaplan, David L

    2012-10-01

    The response of human bone marrow derived human mesenchymal stem cells (hMSCs) encapsulated in silk ionomer hydrogels was studied. Silk aqueous solutions with silk-poly-L-lysine or silk-poly-L-glutamate were formed into hydrogels via ultrasonication in situ with different net charges. hMSCs were encapsulated within the hydrogels and the impact of matrix charge was assessed over weeks in osteogenic, adipogenic and maintenance growth media. These modified silk charged polymers supported cell viability and proliferative potential, and the hMSCs were able to differentiate toward osteogenic or adipogenic lineages in the corresponding differentiation media. The silk/silk-poly-L-lysine hydrogels exhibited a positive effect on selective osteogenesis of hMSCs, inducing differentiation toward an osteogenic lineage even in the absence of osteogenic supplements, while also inhibiting adipogenesis. In contrast, silk/silk fibroin-poly-L-glutamate hydrogels supported both osteogenic and adipogenic differentiation of hMSCs when cultured under induction conditions. The results demonstrate the potential utility of silk-based ionomers in gel formats for hMSCs encapsulation and for directing hMSCs long term functional differentiation toward specific lineages. PMID:22824008

  13. [Phase transition in polymer blends and structure of ionomers and copolymers

    SciTech Connect

    Not Available

    1993-01-01

    The main thrust of the program in the past 3 years are summarized: SAXS instrumentation development; structure and dynamics of macro- and supra-molecules, phase transitions in polymer blends and solutions, structure of ionomers, and fractals and anisotropic systems.

  14. Solvent processible, high-performance partially fluorinated copoly(arylene ether) alkaline ionomers for alkaline electrodes

    NASA Astrophysics Data System (ADS)

    Zhou, Junfeng; Ünlü, Murat; Anestis-Richard, Irene; Kim, Hyea; Kohl, Paul A.

    2011-10-01

    A solvent processable, low water uptake, partially fluorinated copoly(arylene ether) functionalized with pendant quaternary ammonium groups (QAPAE) was synthesized and uses as the ionomer in alkaline electrodes on fuel cells. The quaternized polymers containing fluorinated biphenyl groups were synthesized via chloromethylation of copoly(arylene ether) followed by amination with trimethylamine. The resulting ionomers were very soluble in polar, aprotic solvents. Highly aminated ionomers had conductivities approaching 10 mS cm-1 at room temperature. Compared to previous ionomers based on quaternized poly(arylene ether sulfone) (QAPSF) with similar ion exchange capacity (IEC), the water uptake of QAPAE was significantly less due to the hydrophobic octafluoro-biphenyl groups in the backbone. The performance of the fuel cell electrodes made with the QAPAE ionomers was evaluated as the cathode on a hybrid AEM/PEM fuel cell. The QAPAE alkaline ionomer electrode with IEC = 1.22 meq g-1 had superior performance to the electrodes prepared with QAPSF, IEC = 1.21 meq g-1 at 25 and 60 °C in a H2/O2 fuel cell. The peak power densities at 60 °C were 315 mW cm-2 for QAPAE electrodes and 215 mW cm-2 for QAPSF electrodes.

  15. Synthesis of indium sulphide quantum dots in perfluoronated ionomer membrane

    SciTech Connect

    Sumi, R. [Centre for Nanotechnology Research, VIT University, Vellore (India); Warrier, Anita R.; Vijayan, C. [Department of Physics, Indian Institute of Technology, Chennai (India)

    2014-01-28

    In this paper, we demonstrate a simple and efficient method for synthesis of ?-indium sulphide (In{sub 2}S{sub 3}) nanoparticles embedded in an ionomer matrix (nafion membrane). The influence of reaction temperature on structural, compositional and optical properties of these films were analysed using X-Ray Diffraction, EDAX, UV-Vis absorption spectroscopy and photoluminescence studies. Average particle diameter was estimated using modified effective mass approximation method. Absorption spectra of In{sub 2}S{sub 3} nanoparticles show blue shift compared to bulk In{sub 2}S{sub 3}, indicating strong quantum size confinement effects. PL emission in the wavelength range 530–600 nm was recorded using a 488 nm line from an Ar{sup +} laser as the excitation source.

  16. Dynamics of Sulfonated Polystyrene Ionomers by Dielectric Relaxation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Castagna, Alicia; Wang, Wenqin; Winey, Karen; Runt, James

    2010-03-01

    Broadband dielectric spectroscopy was used to investigate the dynamics of sulfonated polystyrene (SPS) ionomers, in both the acid and neutralized form. This study seeks to elucidate the role of counter ion type (Zn, Na, and Cs), degree of sulfonation (9 and 6%), and ion cluster morphology on the relaxation phenomena of SPS. Degree of neutralization and ion type have been found to significantly impact the breadth and time scale of the segmental relaxation process. High temperature relaxation processes, tentatively proposed to arise from Maxwell-Wagner-Sillars interfacial polarization and a hydrogen bonding relaxation, have also been identified. Bands in the sulfonate stretching region of FTIR spectra reveal information about ion coordination in the local aggregate environment. A combination of scanning transmission electron microscopy imaging and X-ray scattering confirmed the presence of homogeneously distributed, nearly monodisperse spherical ionic aggregates in the polymer matrix.

  17. Synthesis of indium sulphide quantum dots in perfluoronated ionomer membrane

    NASA Astrophysics Data System (ADS)

    Sumi, R.; Warrier, Anita R.; Vijayan, C.

    2014-01-01

    In this paper, we demonstrate a simple and efficient method for synthesis of ?-indium sulphide (In2S3) nanoparticles embedded in an ionomer matrix (nafion membrane). The influence of reaction temperature on structural, compositional and optical properties of these films were analysed using X-Ray Diffraction, EDAX, UV-Vis absorption spectroscopy and photoluminescence studies. Average particle diameter was estimated using modified effective mass approximation method. Absorption spectra of In2S3 nanoparticles show blue shift compared to bulk In2S3, indicating strong quantum size confinement effects. PL emission in the wavelength range 530-600 nm was recorded using a 488 nm line from an Ar+ laser as the excitation source.

  18. Clinical evaluation of the ART approach and materials in peri-urban farm schools of the Johannesburg area.

    PubMed

    Mickenautsch, S; Kopsala, J; Rudolph, M J; Ogunbodede, E O

    2000-07-01

    In this study, 1,325 school children from 7 farm schools were examined. Their mean age (+/- SD) was 10.5 +/- 3.0 (range 6-11) years. At baseline, the mean DMFT score was 1.1 +/- 1.7 and 36.4% of the children had caries. The prevalence of fluorosis among the children was 12.6%. Curative treatment was offered to all the children. A total of 113 children (8.5%) with one-surface cavities on permanent teeth and without fluorosis were treated using the atraumatic restorative treatment (ART) approach. A total number of 163 cavities were included in the study, of which 82 were treated with Fuji IX glass-ionomer cement and 81 with Ketac-MOLAR (hand mix). One year after treatment, restoration and sealant parts of ART fillings were examined. Caries status was also determined. The placing of the ART fillings and their evaluation were performed by different practitioners. A total number of 108 restorations (58 with Fuji IX, 50 with Ketac-MOLAR) were evaluated. Results of ART fillings showed a survival rate of 93.1% with Fuji and 94.0% with Ketac-MOLAR. Retention of the sealant parts of ART fillings was observed in 81% of restorations with Fuji IX and 76% with Ketac-MOLAR, not connected to the filled cavity. Caries was absent on all teeth restored with Fuji IX and noted in only one tooth restored with Ketac-MOLAR, not connected to the filled cavity. The retention rate after a 12-month period was acceptable and ART approach proved to be an appropriate technique for restoring teeth in this population group. There were no statistically significant differences between the survival rates of the two glass-ionomer restorative materials (P > 0.05). PMID:12608196

  19. Tuning polymer glass formation with additives and ions

    NASA Astrophysics Data System (ADS)

    Simmons, David

    2015-03-01

    A polymer's glass transition and associated dynamic and mechanical properties are among the most important factors determining its performance in engineering applications. For this reason, decades of research have aimed to establish methods of tuning polymers' glass formation behavior. Here I describe molecular simulations providing new insight into two approaches to altering a polymer's glass formation behavior: introduction of small-molecule diluents; and introduction of charged moieties to form an ionomer. In the first case, we explore how diluent molecular properties control modifications to the host polymer's glass transition and mechanical response. Results indicate that diluents can induce a rich array of effects, necessitating development of an expanded classification beyond the usual plasticizer/antiplasticizer dichotomy. In the second case, simulations indicate that ionomer glass formation is indistinguishable from that in polymer nanocomposites, in contrast to the longstanding assumption that covalent grafting of chains to ionic aggregates in these systems leads to a qualitatively distinct effect. Taken together, these results provide new guidance towards the rational understanding and control of polymer glass-formation in a range of materials. In collaboration with Jayachandra Hari Mangalara and Dihui Ruan, The University of Akron. This material is based in part on work supported by the W.M. Keck Foundation.

  20. Effect of Equivalent Weight on Water Sorption, PTFE-Like Crystallinity, and Ionic Conductivity in Bis((Perfluoroalkyl)Sulfonyl) Imide Perfluorinated Ionomers

    Microsoft Academic Search

    J. R. Atkins; C. R. Sides; S. E. Creager; J. L. Harris; W. T. Pennington; B. H. Thomas; D. D. DesMarteau

    Measurements of water absorption and ionic conductivity as a function of relative humidity (RH) were carried out on membranes comprised of bis((perfluoroalkyl)sulfonyl) imide ionomers of equivalent weights 1470, 1200, and 1075 g equiv-1, and on a sample of the perfluorosulfonic ionomer Nafion™ ionomer of equivalent weight 1100 g equiv-1 for comparison. All of the ionomers exhibited decreased water absorption and

  1. Water sorption and expansion of an ionomer membrane constrained by fuel cell electrodes

    NASA Astrophysics Data System (ADS)

    Goulet, Marc-Antoni; Arbour, Spencer; Lauritzen, Michael; Kjeang, Erik

    2015-01-01

    This article reveals that catalyst coated membranes (CCM) and membrane electrode assemblies (MEA) expand and contract differently than pure ionomer membranes during hydration and dehydration. Pure membranes are shown to generate twice as much longitudinal peak and residual stress during dehydration than CCMs, reflecting the higher modulus of the pure ionomer material. Moreover, the stronger confinement imposed by the lamination of relatively stiff gas diffusion layers to the CCM prevents the ionomer membrane from expanding in the in-plane direction. This is shown to lead to a significant increase in the through-plane stress and strain during hydration of MEAs versus CCMs and pure ionomer membranes. Supplementary measurements indicate that the water sorption properties of the ionomer (at equilibrium) are not altered by the lamination of catalyst layers and gas diffusion layers; hence, the changes in expansion behavior in the MEA are attributed to the mechanical confinement provided by the other layers. These features should be captured by finite element modeling of fuel cell stacks for accurate cell design and may have important implications for fuel cell durability.

  2. Puncture-Healing Properties of Carbon Nanotube-Filled Ionomers

    NASA Technical Reports Server (NTRS)

    Ward, Thomas C.

    2003-01-01

    Ionomers are polymers that contain ionic groups in relatively low concentrations along the polymer backbone. These ionic groups, in the presence of oppositely charged ions, form aggregates that lead to novel physical properties of the polymer. React-A-Seal(trademark) and Surlyn(trademark) are poly(ethylene-co-methacrylic acid) (EMAA) ionomer-based materials and Nucrel(trademark) is the EMAA acid copolymer neutralized to produce Surlyn(trademark). React-A-Seal(trademark), Surlyn(trademark), and Nucrel(trademark) recover into their original shapes following a high impact puncture at velocities ranging from 300 to 1200 ft/s ('self-healing'). This self-healing process may be of great benefit in space applications where structures are exposed to matter impacts. A thermal IR camera indicated a temperature increase to 98 C for Nucrel(trademark) 925, Surlyn(trademark) 8940, React-A-Seal(trademark), and Surlyn(trademark) 8920 after initial penetration. To understand and generalize the observed phenomena, questions concerning the mechanism of the puncture resealing must be answered. One suggestion is that the elastic character of the melt created by the puncture drives the self-healing. This inference is based on the observed temperature rise of approx. 3 C above the melting temperature of the samples (approx. 95 C) during the impact. With the expectation of gaining additional insight into the self-healing phenomenon, a thermodynamic and viscoelastic investigation was conducted using primarily DSC and DMA. Surlyn(trademark) and React-A-Seal(trademark) showed the characteristic order-disorder transition at approx. 52 C that has been reported in literature. Master curves were constructed from the creep isotherms for the four EMAA samples. An aging study was performed to investigate the irreproducibility and "tailing effect" observed in the creep data. The aging study indicated that, with increased aging time and temperature, changes in the polyethylene matrix lead to complexities in morphology resulting in changes in the magnitude and shape of the creep curves.

  3. Predicted electric-field-induced hexatic structure in an ionomer membrane.

    PubMed

    Allahyarov, Elshad; Taylor, Philip L

    2009-08-01

    Coarse-grained molecular-dynamics simulations were used to study the morphological changes induced in a Nafion-like ionomer by the imposition of a strong electric field. We observe the formation of structures aligned along the direction of the applied field. The polar head groups of the ionomer sidechains aggregate into clusters, which then form rodlike formations which assemble into a hexatic array aligned with the direction of the field. Occasionally these lines of sulfonates and protons form a helical structure. Upon removal of the electric field, the hexatic array of rodlike structures persists and has a lower calculated free energy than the original isotropic morphology. PMID:19792066

  4. Nuclear magnetic resonance investigation of dynamics in poly(ethylene oxide)-based lithium polyether-ester-sulfonate ionomers

    DOE PAGESBeta

    Roach, David J.; Dou, Shichen; Colby, Ralph H.; Mueller, Karl T.

    2012-01-01

    Nuclear magnetic resonance (NMR) spectroscopy has been utilized to investigate the dynamics of poly(ethylene oxide)-based lithium sulfonate ionomer samples that have low glass transition temperatures. 1H and 7Li spin-lattice relaxation times (T1) of the bulk polymer and lithium ions, respectively, were measured and analyzed in samples with a range of ion contents. The temperature dependence of T1 values along with the presence of minima in T1 as a function of temperature enabled correlation times and activation energies to be obtained for both the segmental motion of the polymer backbone and the hopping motion of lithium cations. Similar activation energies formore »motion of both the polymer and lithium ions in the samples with lower ion content indicate that the polymer segmental motion and lithium ion hopping motion are correlated in these samples, even though their respective correlation times differ significantly. A divergent trend is observed for correlation times and activation energies of the highest ion content sample with 100% lithium sulfonation due to the presence of ionic aggregation. Details of the polymer and cation dynamics on the nanosecond timescale are discussed and complement the findings of X-ray scattering and Quasi Elastic Neutron Scattering experiments.« less

  5. Nuclear magnetic resonance investigation of dynamics in poly(ethylene oxide)-based lithium polyether-ester-sulfonate ionomers

    DOE PAGESBeta

    Roach, David J. [Pennsylvania State University, University Park, PA (United States); Dou, Shichen [Pennsylvania State University, University Park, PA (United States); Colby, Ralph H. [Pennsylvania State University, University Park, PA (United States); Mueller, Karl T. [Pacific Northwest Lab., Richland, WA (United States). Environmental Molecular Sciences Lab.

    2012-01-01

    Nuclear magnetic resonance (NMR) spectroscopy has been utilized to investigate the dynamics of poly(ethylene oxide)-based lithium sulfonate ionomer samples that have low glass transition temperatures. 1H and 7Li spin-lattice relaxation times (T1) of the bulk polymer and lithium ions, respectively, were measured and analyzed in samples with a range of ion contents. The temperature dependence of T1 values along with the presence of minima in T1 as a function of temperature enabled correlation times and activation energies to be obtained for both the segmental motion of the polymer backbone and the hopping motion of lithium cations. Similar activation energies for motion of both the polymer and lithium ions in the samples with lower ion content indicate that the polymer segmental motion and lithium ion hopping motion are correlated in these samples, even though their respective correlation times differ significantly. A divergent trend is observed for correlation times and activation energies of the highest ion content sample with 100% lithium sulfonation due to the presence of ionic aggregation. Details of the polymer and cation dynamics on the nanosecond timescale are discussed and complement the findings of X-ray scattering and Quasi Elastic Neutron Scattering experiments.

  6. Nuclear magnetic resonance investigation of dynamics in poly(ethylene oxide)-based lithium polyether-ester-sulfonate ionomers

    NASA Astrophysics Data System (ADS)

    Roach, David J.; Dou, Shichen; Colby, Ralph H.; Mueller, Karl T.

    2012-01-01

    Nuclear magnetic resonance spectroscopy has been utilized to investigate the dynamics of poly(ethylene oxide)-based lithium sulfonate ionomer samples that have low glass transition temperatures. 1H and 7Li spin-lattice relaxation times (T1) of the bulk polymer and lithium ions, respectively, were measured and analyzed in samples with a range of ion contents. The temperature dependence of T1 values along with the presence of minima in T1 as a function of temperature enabled correlation times and activation energies to be obtained for both the segmental motion of the polymer backbone and the hopping motion of lithium cations. Similar activation energies for motion of both the polymer and lithium ions in the samples with lower ion content indicate that the polymer segmental motion and lithium ion hopping motion are correlated in these samples, even though lithium hopping is about ten times slower than the segmental motion. A divergent trend is observed for correlation times and activation energies of the highest ion content sample with 100% lithium sulfonation due to the presence of ionic aggregation. Details of the polymer and cation dynamics on the nanosecond timescale are discussed and complement the findings of X-ray scattering and quasi-elastic neutron scattering experiments.

  7. Nuclear Magnetic Resonance Investigation of Dynamics in Poly(Ethylene Oxide) Based Lithium Polyether-ester-sulfonate Ionomers

    SciTech Connect

    Roach, David J.; Dou, Shichen; Colby, Ralph H.; Mueller, Karl T.

    2012-01-07

    Nuclear magnetic resonance (NMR) spectroscopy has been utilized to investigate the dynamics of poly(ethylene oxide)-based lithium sulfonate ionomer samples that have low glass transition temperatures. 1H and 7Li spin-lattice relaxation times (T1) of the bulk polymer and lithium ions, respectively, were analyzed in samples with a range of ion contents. The temperature dependence of T1 values along with the presence of minima in T1 enabled correlation times and activation energies to be obtained for both the segmental motion of the polymer backbone and the hopping motion of lithium cations. Similar activation energies of both the polymer and lithium ions in the lower ion content samples indicate that the polymer segmental motion and lithium ion hopping motion are correlated even though their respective correlation times differ significantly. A divergent trend is observed for correlation times and activation energies of the highest ion content sample due to the presence of ionic aggregation. Details about the polymer and cation dynamics on the nanosecond timescale are discussed and complement the findings of X-ray scattering and Quasi Elastic Neutron Scattering experiments.

  8. Microleakage of gold casting repairs with different materials as quantified by a helium gas system.

    PubMed

    Briseño Marroquin, B; Kremers, L; Willershausen-Zönchen, B; Mücke, A

    1995-01-01

    Inadequate adaptation of a filling material to a gold crown can promote the passage of bacteria; thus, recontamination of sound dentin and/or the pulp canal space is feasible. The aim of this study was to determine the marginal microleakage between two different amalgams (Tytin and Valiant PHD-XT), three different composites (Tetric, Charisma, and Polofil Molar), and one glass-ionomer cement (Ketac Silver) and gold cast crowns using a helium gas microleakage method. In order to standardize the research parameters, gold washers with standardized dimensions were used as study models together with a helium leakage testing device. Standardized cavities were filled according to the manufacturers' recommendations with the different materials. The amount of helium passing the marginal interface between the fillings and cavities was measured with a mass spectrometer 48 hours after the fillings were placed and 100, 1000, and 2000 thermocycles (5 degrees C-55 degrees C). The results showed that amalgam allowed the least microleakage. Ketac Silver showed the greatest microleakage. Statistically significant differences were found between the composites and both amalgams and Ketac Silver between the 48-hour and 100-thermocycling groups. Yet, Ketac Silver showed a significant ascending tendency when compared to the composites and amalgams after 100, 1000, and 2000 thermocycles. PMID:8710699

  9. Light and transmission electron microscopic studies following frontal sinus obliteration with ionomer cement in cats

    Microsoft Academic Search

    S. Dazert; W. H. Muss

    1995-01-01

    Osteoplastic frontal sinus surgery in combination with sinus obliteration can be performed for various indications, including chronic sinusitis, frontal sinus trauma and removal of osteomas. In an experimental study using cats, the mucous lining of the frontal sinus was removed, the nasofrontal duct sealed with semifluid ionomer cement and the cavity filled with Ionogran, a solid and porous bone substitute

  10. Rheology of water-in-water suspensions formed with lightly sulfonated ionomers

    Microsoft Academic Search

    D. G. Peiffer; R. D. Lundberg

    1985-01-01

    The formation and rheological properties of water-in-water suspensions formed by mixing a dilute nonaqueous solution containing a lightly sulfonated ionomer with an aqueous solution are described. The spheres formed via this process are composed of a very thin (approximately 2000 Å), ionically crosslinked gel membrane which separates the continuous aqueous phase from the encapsulated aqueous phase. The membrane itself is

  11. Carbon-13 nuclear magnetic resonance study on poly(ethylacrylate-co-sodium acrylate) ionomer

    NASA Astrophysics Data System (ADS)

    Lim, Ae Ran; Kwark, Young-Je; Kim, Joon-Seop

    2003-12-01

    The poly(ethylacrylate) (PEA) homopolymer and poly(ethylacrylate-co-sodium acrylate) ionomer that contain 8.4 mol % ionic groups (PEANa-8.4) were studied by 13C using cross polarization and magic angle spinning nuclear magnetic resonance (CP/MAS NMR). The 13C spin-lattice relaxation times in a rotating frame, T1?, were measured as functions of the temperature. Using these T1? spin-lattice relaxation times, we addressed the chain mobility, correlation time, and activation energy for carbon of the PEA homopolymer and the PEANa-8.4 ionomer. We found that the molecular motion in the PEA homopolymer needed a higher activation energy than that in the PEANa-8.4 ionomer. In addition, we observed that motion of the 1-methyl carbons in the PEANa-8.4 ionomer was distinctly different from that in the PEA homopolymer: the value of T1? for 1-methyl carbon is ascribed to stronger interactions between the polymer chains in the homopolymer.

  12. Natural Genetic Variation in Selected Populations of Arabidopsis thaliana Is Associated with Ionomic Differences

    Microsoft Academic Search

    Elizabeth Buescher; Tilman Achberger; Idris Amusan; Anthony Giannini; Cherie Ochsenfeld; Ana Rus; Brett Lahner; Owen Hoekenga; Elena Yakubova; Jeffrey F. Harper; Mary Lou Guerinot; Min Zhang; David E. Salt; Ivan R. Baxter; Pär K. Ingvarsson

    2010-01-01

    Controlling elemental composition is critical for plant growth and development as well as the nutrition of humans who utilize plants for food. Uncovering the genetic architecture underlying mineral ion homeostasis in plants is a critical first step towards understanding the biochemical networks that regulate a plant's elemental composition (ionome). Natural accessions of Arabidopsis thaliana provide a rich source of genetic

  13. Shape-Memory Polymers Based on Fatty Acid-Filled Elastomeric Ionomers

    Microsoft Academic Search

    Elise Izzo; Robert Weiss

    2009-01-01

    Shape memory polymers (SMPs) have applications as medical devices, actuators, sensors, artificial muscles, switches, smart textiles, and self-deployable structures. All previous design of SMPs has involved synthesizing new polymers or modifying existing polymers. This paper describes a new type of SMP based on blends of an elastomeric ionomer and low molar mass fatty acids or their salts (FAS). Shape memory

  14. An efficient Ag-ionomer interface for hydroxide exchange membrane fuel cells.

    PubMed

    Gu, Shuang; Sheng, Wenchao; Cai, Rui; Alia, Shaun M; Song, Shuqin; Jensen, Kurt O; Yan, Yushan

    2013-01-01

    An efficient Ag-phosphonium ionomer interface is discovered in HEMFCs, helping enhance oxygen reduction and improve mass transports simultaneously. As a result, a completely-precious-metal-free HEMFC has been fabricated, which shows a cost-normalized power much higher than that of a Pt-based PEMFC benchmark (117 vs. 7.7 W US$(-1)). PMID:23019567

  15. Molecular dynamics simulations of ionic aggregates in a coarse-grained ionomer melt

    NASA Astrophysics Data System (ADS)

    Hall, Lisa; Stevens, Mark; Frischknecht, Amalie

    2011-03-01

    Ionomers (polymers with a small fraction of covalently bound ionic groups) have potential application as solid battery electrolytes. Understanding ion transport is essential for such applications. A key question is how molecular properties affect ionic aggregation and counterion dynamics. Recent experimental advances allowed synthesis and extensive characterization of ionomers with a precise spacing of charged groups, which is ideal for comparison with simulations. We use coarse-grained molecular dynamics to simulate ionomers with charged beads placed periodically either in the polymer backbone or pendant to the backbone. The polymers, along with counterions, are simulated at melt densities. Pendant ions at low dielectric form roughly spherical aggregates with liquidlike interaggregate order, qualitatively different from the aggregate morphology of analogous linear ionomers. The effects of dielectric constant and backbone spacing of charged beads on ionic structure and diffusion will be discussed. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration, contract DE-AC04-94AL85000.

  16. IONOMICS:A NEW APPROACH IN BRIDGING THE GAPS BETWEEN GENOMES, ORGANISMS, AND

    E-print Network

    Fernández-Juricic, Esteban

    interest is to understand the function of the genes and gene networks that regulate the plant ionome involved in related work since his PhD (Liverpool University, UK, 1985­1988), working on the mechanisms of evolved copper tolerance in Mimulus gutattus (yellow monkey flower). He also has a BSc in Biochemistry

  17. Synthesis and characterization of polyurethane ionomers, blends and urethane-urea aerogel hybrids

    NASA Astrophysics Data System (ADS)

    Wang, Mingzhe

    The chemical and physical properties of alkali, alkaline metal and selected transition metal polyurethane ionomers were investigated. A new synthesis was developed for carboxylated polyurethane anionomers, and it was employed to synthesize a range of ionomers. Thus, a series of polyurethane ionomers was prepared in which the molecular weight of a constituent diol, the concentration of carboxylic acid sites, and the nature of the cations was varied. The analogous materials with equivalent nominal stoichiometries were synthesized by the standard method of preparing the acid-form polymer and of replacing the protons for metal ions. The novel synthesis employs a multiphase reaction between isocyanate-terminated prepolymers and solid, anhydrous microcrystalline metal salts of a carboxylic acid diol. This required the development of new synthesis of these starting materials. The materials studied are based on polyether diols, acid-containing diols and a saturated diisocyanate. The novel synthesis is more than twenty times as fast as the standard method under the same conditions. The spectroscopic and mechanical properties of the polyurethane ionomers synthesized in both ways were studied and contrasted. Those prepared by the new method have greater spatial homogeneity, resulting in lower scattering loss in the ultraviolet-visible range. They also exhibited values of E ' (the real elastic modulus) that are as much as an order of magnitude greater than those made by the standard method. In addition, the temperature dependence of Fin the -25 ˜ +75°C range is remarkably low. Studies of the structural properties by infrared spectroscopy, small angle x-ray scattering, thermal analysis, gel permeation chromatography and scanning electron microscopy were used to elucidate their molecular structures and intermolecular interactions. The rates of key synthetic reactions and the thermal stability of the metal containing polyurethane ionomers were studied by thermal analysis. The polyurethane ionomers synthesized in this work were combined with, sulfonated polystyrene, and poly(ethylene-co-acrylic or methacrylic acid) polymers, their partially neutralized ionomers, and thermoplastic polyurethanes. It was found that polyurethane anionomers synthesized by the new method were miscible with these polymers through the composition range. Several series of these blends were studied using mid- and far-infrared spectroscopy to investigate molecular interactions that lead to the miscibility. Isocyanate-containing molecules were reacted with chitosan silica aerogels. It was discovered that -NCO groups of the diisocyanate HMDI reacted selectively with amine groups in the presence of large excesses of -OH groups from alcohol, silica, and water. This study leads to the possibility of attaching nanoscale aerogel particles to substrates, to one another, and to additional molecules of interest.

  18. A polymethacrylate-based quaternary ammonium OH- ionomer binder for non-precious metal alkaline anion exchange membrane water electrolysers

    NASA Astrophysics Data System (ADS)

    Wu, Xu; Scott, Keith

    2012-09-01

    In order to develop the alkaline anion exchange membrane water electrolysers (AAEMWE), a quaternary OH- conductive ionomer binder based on polymethacrylate was synthesized by copolymerization of three kinds of methacrylate monomers, which was followed by quaternization. Tensile strength of this ionomer membrane was 7.629 MPa, with Young's modulus 0.229 GPa and elongation 45.8%. The conductivity of this ionomer could reach 0.059 S cm-1 at 50 °C. With this ionomer in catalyst layers of an AAEMWE, the voltage of 1.9 V gave a current density of 100 mA cm-2. Satisfactory stability of the membrane electrode assembly was observed from chronocoulometry.

  19. [Phase transition in polymer blends and structure of ionomers and copolymers]. [Annual report, April 1, 1989--June 30, 1993

    SciTech Connect

    Not Available

    1993-07-01

    The main thrust of the program in the past 3 years are summarized: SAXS instrumentation development; structure and dynamics of macro- and supra-molecules, phase transitions in polymer blends and solutions, structure of ionomers, and fractals and anisotropic systems.

  20. A Low-Temperature Thermoplastic Antibacterial Medical Orthotic Material Made of Shape Memory Polyurethane Ionomer: Influence of Ionic Group

    Microsoft Academic Search

    Qinghao Meng; Jinlian Hu; Baohua Liu; Yong Zhu

    2009-01-01

    PCL-based shape memory polyurethane ionomers with quaternarized pyridine moieties incorporated through molecular extension were synthesized. These polyurethanes were specifically designed as low-temperature thermoplastic anti-bacterial orthotic materials. A commercialized orthotic material was employed for comparison. The influence of ionic groups on the properties of orthotic materials was studied. The anti-bacterial properties and cytotoxicity of the polyurethane ionomer were tested. It was

  1. Interdiffusion of long alcohols into thin ionomer films; In situ Neutron Reflectivity study

    NASA Astrophysics Data System (ADS)

    Etampawala, Thusitha; Ratnaweera, Dilru; Shrestha, Umesh; Perahia, Dvora; Cornelius, Christopher; Majewski, Jaroslaw

    2010-03-01

    Transport of solvents and ions within ionic polymers controls their many current and potential applications from energy related to drug delivery systems. The transport is determined by the phase structure and the interaction of the diffusing species with the polymers, coupled with interfacial effects. The current work presents the kinetics of penetration of long chain alcohols diffusing into rigid ionomer thin films formed by a rigid polyphenylene sulfonated ionomer, using in situ neutron reflectivity. The penetration of deuterated n-octanol and n-hexanol into ˜20nm thick films was followed as a function of time for different sulfonation levels of the polymer. As for shorter molecules, the diffusion process consists of two stages, a relatively fast one in which the film thickness increases linearly with time followed by a slow phase in which structural changes take place. With increasing sulfonation levels, the diffusion first increases and then decreases; a trend that is attributed to hydrophilic/hydrophobic balance.

  2. Plant ionome diagnosis using sound balances: case study with mango (Mangifera Indica)

    PubMed Central

    Parent, Serge-Étienne; Parent, Léon E.; Rozane, Danilo Eduardo; Natale, William

    2013-01-01

    Plant ionomes and soil nutrients are commonly diagnosed in agronomy using concentration and nutrient ratio ranges. However, both diagnoses are biased by redundancy of information, subcompositional incoherence and non-normal distribution inherent to compositional data, potentially leading to conflicting results and wrong inferences. Our objective was to present an unbiased statistical approach of plant nutrient diagnosis using a balance concept and mango (Mangifera indica) as test crop. We collected foliar samples at flowering stage in 175 mango orchards. The ionomes comprised 11 nutrients (S, N, P, K, Ca, Mg, B, Cu, Zn, Mn, Fe). Traditional multivariate methods were found to be biased. Ionomes were thus represented by unbiased balances computed as isometric log ratios (ilr). Soil fertility attributes (pH and bioavailable nutrients) were transformed into balances to conduct discriminant analysis. The orchards differed more from genotype than soil nutrient signatures. A customized receiver operating characteristic (ROC) iterative procedure was developed to classify tissue ionomes between balanced/misbalanced and high/low-yielders. The ROC partitioning procedure showed that the critical Mahalanobis distance of 4.08 separating balanced from imbalanced specimens about yield cut-off of 128.5 kg fruit tree?1 proved to be a fairly informative test (area under curve = 0.84–0.92). The [P | N,S] and [Mn | Cu,Zn] balances were found to be potential sources of misbalance in the less productive orchards, and should thus be further investigated in field experiments. We propose using a coherent pan balance diagnostic method with median ilr values of top yielders centered at fulcrums of a mobile and the critical Mahalanobis distance as a guide for global nutrient balance. Nutrient concentrations in weighing pans assisted appreciating nutrients as relative shortage, adequacy or excess in balances. PMID:24273548

  3. Developments in Metal?Containing Polyurethanes, Co?polyurethanes and Polyurethane Ionomers

    Microsoft Academic Search

    R. Jayakumar; S. Nanjundan; M. Prabaharan

    2005-01-01

    The growth of science and technology of polyurethanes leads to the development of new materials with more desirable properties. Such kinds of materials include metal?containing polyurethanes, poly(urethane?urea)s, poly(urethane?ether)s, poly(urethane?ester)s, poly(urethane?ether?ester)s, poly(urethane?imide)s, and polyurethane ionomers with isocyanate structural units combining the properties of enhanced thermal stability, fire retardancy, flexibility, and solubility. Ionic diols containing metal salts are used as important starting

  4. Anionic polysulfone ionomers and membranes containing fluorenyl groups for anionic fuel cells

    Microsoft Academic Search

    Junfeng Zhou; Murat Unlu; Jose A. Vega; Paul A. Kohl

    2009-01-01

    Poly(arylene ether sulfone) ionomers containing fluorenyl groups and functionalized with benzyltrimethylammonium groups were synthesized through polycondensation, chloromethylation, and amination reactions. The resulting polymers were characterized by 1H NMR, FT-IR and TGA. Polymer membranes were solvent cast from DMF on Teflon plates to form clear, flexible anion exchange membranes (AEMs). Carbonate anions had conductivities in the AEMs up to 63.12mScm?1 at

  5. Dynamics and partitioning of the ionome in seeds and germinating seedlings of winter oilseed rape.

    PubMed

    Eggert, Kai; von Wirén, Nicolaus

    2013-09-01

    Germination and seedling establishment are among the most critical phases in the development of plants, and seed vigour has become an important trait for the selection of robust crop cultivars. Little is known about the potentially limiting role of mineral nutrients in early metabolic and developmental processes during germination. Therefore, we assessed the ionome and relative distribution of mineral elements in different seed and seedling tissues of oilseed rape (Brassica napus L.) and monitored the internal allocation of nutrients during germination. In seeds, cotyledons harboured the main pool of K, P, S, Mg, Fe, Mn and Zn, whereas the seed coat contained most of the Ca, Na, B, Cu and Mo. Although the early root and hypocotyl tissue expanded first, concentrations of most elements were initially low. Re-allocation of elements to the root/hypocotyl tissue from other pools set in two days after seed imbibition and was most rapid for K. Relative to the critical deficiency levels of vegetative tissues, seed tissues were particularly low in B, K and Fe. Further analyses of the ionome of seeds and seedlings, grouped according to their germination efficiency, indicated that in particular low S, Mg and Ca coincided with germination failure. This study documents highly dynamic changes in the ionome of seed and seedling tissues and provides evidence for potentially limiting elements during early germination and seedling establishment in rapeseed. PMID:23939714

  6. Shape-Memory Polymers Based on Fatty Acid-Filled Elastomeric Ionomers

    NASA Astrophysics Data System (ADS)

    Izzo, Elise; Weiss, Robert

    2009-03-01

    Shape memory polymers (SMPs) have applications as medical devices, actuators, sensors, artificial muscles, switches, smart textiles, and self-deployable structures. All previous design of SMPs has involved synthesizing new polymers or modifying existing polymers. This paper describes a new type of SMP based on blends of an elastomeric ionomer and low molar mass fatty acids or their salts (FAS). Shape memory elastomers were prepared from mixtures of a sulfonated EPDM ionomer and various amounts of a FAS (e.g., zinc stearate, zinc oleate, and various aliphalic acids). Nanophase separation of the metal sulfonate groups provided the ``permanent'' crosslinks, while sub-microscopic crystals of the low molecular weight FAS provided a physical crosslink needed for the temporary shape. The material was deformed above the melting point of the FAS and the new shape was fixed by cooling the material while under stress to below the melting point of the FAS. Polar interactions between the ionomer and the FAS stabilized the dispersion of the FAS in the polymer and provided the continuity between the phases that allowed the crystals of the FAS to provide a second network of physical crosslinks. The temporary shape was erased and the material returned to the primary shape by heating above the melting point of the FAS.

  7. Cusp Fracture Resistance of Maxillary Premolars Restored with the Bonded Amalgam Technique Using Various Luting Agents

    PubMed Central

    Marchan, Shivaughn M.; Coldero, Larry; White, Daniel; Smith, William A. J.; Rafeek, Reisha N.

    2009-01-01

    Objective. This in vitro study uses measurements of fracture resistance to compare maxillary premolars restored with the bonded amalgam technique using a new resin luting cement, glass ionomer, and resin-modified glass ionomer as the bonding agents. Materials. Eighty-five sound maxillary premolars were selected and randomly assigned to one of five test groups of 17 teeth each. One group of intact teeth served as the control. The remaining groups were prepared to a standard cavity form relative to the dimensions of the overall tooth and restored with amalgam alone or a bonded amalgam using one of three luting agents: RelyX Arc (a new resin luting cement), RelyX luting (a resin-modified glass ionomer), or Ketac-Cem ? (a glass ionomer) as the bonding agents. Each tooth was then subjected to compressive testing until catastrophic failure occurred. The mean loads at failure of each group were statistically compared using ANOVA with a post hoc Bonferroni test. Results. It was found that regardless of the luting cement used for the amalgam bonding technique, there was little effect on the fracture resistance of teeth. Conclusion. Cusp fracture resistance of premolars prepared with conservative MOD cavity preparations is not improved by using an amalgam-bonding technique compared to similar cavities restored with amalgam alone. PMID:20339450

  8. Phase inversion of ionomer-stabilized emulsions to form high internal phase emulsions (HIPEs).

    PubMed

    Zhang, Tao; Xu, Zhiguang; Cai, Zengxiao; Guo, Qipeng

    2015-06-28

    Herein, we report the phase inversion of ionomer-stabilized emulsions to form high internal phase emulsions (HIPEs) induced by salt concentration and pH changes. The ionomers are sulfonated polystyrenes (SPSs) with different sulfonation degrees. The emulsion types were determined by conductivity measurements, confocal microscopy and optical microscopy, and the formation of HIPE organogels was verified by the tube-inversion method and rheological measurements. SPSs with high sulfonation degrees (water-soluble) and low sulfonation degrees (water-insoluble) can stabilize oil-in-water emulsions; these emulsions were transformed into water-in-oil HIPEs by varying salt concentrations and/or changing the pH. SPS, with a sulfonation degree of 11.6%, is the most efficient, and as low as 0.2 (w/v)% of the organic phase is enough to stabilize the HIPEs. Phase inversion of the oil-in-water emulsions occurred to form water-in-oil HIPEs by increasing the salt concentration in the aqueous phase. Two phase inversion points from oil-in-water emulsions to water-in-oil HIPEs were observed at pH 1 and 13. Moreover, synergetic effects between the salt concentration and pH changes occurred upon the inversion of the emulsion type. The organic phase can be a variety of organic solvents, including toluene, xylene, chloroform, dichloroethane, dichloromethane and anisole, as well as monomers such as styrene, butyl acrylate, methyl methacrylate and ethylene glycol dimethacrylate. Poly(HIPEs) were successfully prepared by the polymerization of monomers as the continuous phase in the ionomer-stabilized HIPEs. PMID:26028420

  9. Block ionomer complex micelles with cross-linked cores for drug delivery

    Microsoft Academic Search

    Jong Oh Kim; Nataliya V. Nukolova; Hardeep S. Oberoi; Alexander V. Kabanov; Tatiana K. Bronich

    2009-01-01

    Soft polymeric nanomaterials were synthesized by template-assisted method involving condensation of the poly(ethylene oxide)-b-polycarboxylate\\u000a anions by metal ions into core-shell block ionomer complex micelles followed by chemical cross-linking of the polyion chains\\u000a in the micelle cores. The resulting materials represent nanogels and are capable of swelling in a pH-dependent manner. The\\u000a structural determinants that guide the self-assembly of the initial

  10. Glass recycling

    SciTech Connect

    Dalmijn, W.L.; Houwelingen, J.A. van [Delft Univ. of Technology (Netherlands). Faculty of Mining and Petroleum Engineering

    1995-12-31

    Glass recycling in the Netherlands has grown from 10,000 to 300,000 tonnes per annum. The various advantages and problems of the glass cycle with reference to the state of the art in the Netherlands is given. Special attention is given to new technologies for the automated sorting of cullet with detection systems. In Western Europe the recycling of glass has become a success story. Because of this, the percentage of glass cullet used in glass furnaces has increased. To meet the quality demands of the glass industry, automated sorting for the removal of stones, non-ferrous metals and other impurities had to be developed and incorporated in glass recycling plants. In Holland, Germany and other countries, the amount of glass collected has reached a level that color-sorting becomes necessary to avoid market saturation with mixed cullet. Recently, two systems for color-sorting have been developed and tested for the separation of bottles and cullet in the size range of 20--50 mm. With the increased capacity of the new glass recycling plants, 120,000--200,000 tpy, the quality systems have also to be improved and automated. These quality control systems are based on the automated sorting technology developed earlier for the glass recycling plants. The data obtained are automatically processed and printed. The sampling system and its relation to the theory of Gy will be described. Results of both developments in glass recycling plants will be described.

  11. High-resolution genome-wide scan of genes, gene-networks and cellular systems impacting the yeast ionome

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To balance the demand for uptake of essential elements with their potential toxicity living cells have complex regulatory mechanisms. Here, we describe a genome-wide screen to identify genes that impact the elemental composition (‘ionome’) of yeast Saccharomyces cerevisiae. Using inductively coupled...

  12. Shoot ionome to predict the synergism and antagonism between nutrients as affected by substrate and physiological status.

    PubMed

    Pii, Youry; Cesco, Stefano; Mimmo, Tanja

    2015-09-01

    The elemental composition of a tissue or organism is defined as ionome. However, the combined effects on the shoot ionome determined by the taxonomic character, the nutrient status and different substrates have not been investigated. This study tests the hypothesis that phylogenetic variation of monocots and dicots grown in iron deficiency can be distinguished by the shoot ionome. We analyzed 18 elements in barley, cucumber and tomato and in two substrates (hydroponic vs soil) with different nutritional regimes. Multivariate analysis evidenced a clear separation between the species. In hydroponic conditions the main drivers separating the species are non essential-nutrients as Ti, Al, Na and Li, which were positively correlated with macro- (P, K) and micronutrients (Fe, Zn, Mo, B). The separation between species is confirmed when plants are grown on soil, but the distribution is determined especially by macronutrients (S, P, K, Ca, Mg) and micronutrients (B). A number of macro (Mg, Ca, S, P, K) and micronutrients (Fe, Mn, Zn, Cu, Mo, B) contribute to plant growth and several other important physiological and metabolic plant activities. The results reported here confirmed that the synergism and antagonism between them and other non-essential elements (Ti, Al, Si, Na) define the plant taxonomic character. The ionome profile might thus be exploited as a tool for the diagnosis of plants physiological/nutritional status but also in defining biofortification strategies to optimize both mineral enrichment of staple food crops and the nutrient input as fertilizers. PMID:26004913

  13. Cluster-continuum quantum mechanical models to guide the choice of anions for Li{sup +}-conducting ionomers

    SciTech Connect

    Shiau, Huai-Suen; Janik, Michael J. [Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)] [Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Liu, Wenjuan; Colby, Ralph H. [Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)] [Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2013-11-28

    A quantum-mechanical investigation on Li poly(ethylene oxide)-based ionomers was performed in the cluster-continuum solvation model (CCM) that includes specific solvation in the first shell surrounding the cation, all surrounded by a polarizable continuum. A four-state model, including a free Li cation, Li{sup +}-anion pair, triple ion, and quadrupole was used to represent the states of Li{sup +} within the ionomer in the CCM. The relative energy of each state was calculated for Li{sup +} with various anions, with dimethyl ether representing the ether oxygen solvation. The population distribution of Li{sup +} ions among states was estimated by applying Boltzmann statistics to the CCM energies. Entropy difference estimates are needed for populations to better match the true ionomer system. The total entropy change is considered to consist of four contributions: translational, rotational, electrostatic, and solvent immobilization entropies. The population of ion states is reported as a function of Bjerrum length divided by ion-pair separation with/without entropy considered to investigate the transition between states. Predicted concentrations of Li{sup +}-conducting states (free Li{sup +} and positive triple ions) are compared among a series of anions to indicate favorable features for design of an optimal Li{sup +}-conducting ionomer; the perfluorotetraphenylborate anion maximizes the conducting positive triple ion population among the series of anions considered.

  14. Comparative metabolomic and ionomic approach for abundant fishes in estuarine environments of Japan

    PubMed Central

    Yoshida, Seiji; Date, Yasuhiro; Akama, Makiko; Kikuchi, Jun

    2014-01-01

    Environmental metabolomics or ionomics is widely used to characterize the effects of environmental stressors on the health of aquatic organisms. However, most studies have focused on liver and muscle tissues of fish, and little is known about how the other organs are affected by environmental perturbations and effects such as metal pollutants or eutrophication. We examined the metabolic and mineral profiles of three kinds of abundant fishes in estuarine ecosystem, yellowfin goby, urohaze-goby, and juvenile Japanese seabass sampled from Tsurumi River estuary, Japan. Multivariate analyses, including nuclear magnetic resonance-based metabolomics and inductively coupled plasma optical emission spectrometry-based ionomics approaches, revealed that the profiles were clustered according to differences among body tissues rather than differences in body size, sex, and species. The metabolic and mineral profiles of the muscle and fin tissues, respectively, suggest that these tissues are most appropriate for evaluating environmental perturbations. Such analyses will be highly useful in evaluating the environmental variation and diversity in aquatic ecosystems. PMID:25387575

  15. Poly(arylene ether sulfone)s ionomers containing quaternized triptycene groups for alkaline fuel cell

    NASA Astrophysics Data System (ADS)

    Zhao, Zhuo; Gong, Feixiang; Zhang, Suobo; Li, Shenghai

    2012-11-01

    A series of poly(arylene ether sulfone)s containing quaternized triptycene groups are synthesized through a chloromethylation reaction following a quaternization process. The resulting ionomers are soluble in polar aprotic solvents; thus, flexible, tough membranes could be prepared by solution casting. Novel anion exchange membranes based on these ionomers are obtained by anion exchange with hydroxide ions. All anion exchange membranes show conductivities above 10-2 S cm-1 at room temperature. The highest hydroxide conductivity is 7.2 × 10-2 S cm-1, which is achieved by the anion exchange membrane with ion exchange capacity (IEC) = 2.61 mmol g-1. Meanwhile, these anion exchange membranes have low water uptake and good dimensional stability even at high IEC values. For example, the membrane water uptake (IEC = 1.97 mmol g-1) is only 21% at room temperature, and the swelling ratio is 11%. The anion exchange membranes are stable in alkaline conditions. All the membranes have no significant change in 4 M NaOH solution at 25 °C after 30 days. All results suggest that these anion exchange membranes have potential application in alkaline fuel cells.

  16. glass ceramic

    NASA Astrophysics Data System (ADS)

    Hassaan, M. Y.; Salem, S. M.; Moustafa, M. G.; Kubuki, S.; Matsuda, K.; Nishida, T.

    2014-04-01

    Glass sample with a composition of Li1.3Nb0.3Fe1.7(PO4)3, prepared by a conventional melt-quenching method, was heat treated to obtain glass ceramics of NASICON type. Glass transition ( T g) and crystallization ( T c) temperatures of as-quenched glass sample were determined by differential thermal analysis (DTA). X-ray diffraction (XRD) patterns also confirmed the formation of glass sample. After heat treatment above T c, precipitation of crystalline particles with NASICON-type structure was confirmed by XRD. Valency and local structure of Fe atoms were investigated by Mössbauer spectroscopy at room temperature. DC-conductivity and impedance measurements of the glass ceramics proved the increased electrical conduction caused by heat treatment.

  17. Rainbow Glasses

    NSDL National Science Digital Library

    2012-06-26

    In this activity, learners explore light, color and rainbows by making their own rainbow glasses. Learners glue "rainbow optics paper" onto the glasses cutout, add decorations and attach pipe cleaner earpieces. Learners name the different colors they observe and notice that the colors always appear in the same order. This activity guide includes open-ended questions to help learners explore these topics further.

  18. Effect of Nafion ionomer and catalyst in cathode layers for the direct formic acid fuel cell with complex capacitance analysis on the ionic resistance

    Microsoft Academic Search

    Sunhyung Kim; Jonghee Han; Yongchai Kwon; Kug-Seung Lee; Tae-Hoon Lim; Suk Woo Nam; Jong Hyun Jang

    2011-01-01

    Using platinum (Pt) black and carbon-supported Pt (Pt\\/C) as cathode catalysts, membrane-electrode assemblies (MEAs) were fabricated with various Nafion ionomer content, and their direct formic acid fuel cell (DFAFC) performances were investigated. In MEAs incorporating Pt black catalysts, the current density at 0.6V was highest at ionomer\\/catalyst volume ratio of 1.0, which was consistent with the electrochemical active area (EAS)

  19. One-year clinical evaluation of a Glass Carbomer fissure sealant, a preliminary study.

    PubMed

    Gorseta, K; Glavina, D; Borzabadi-Farahani, A; Van Duinen, R N; Skrinjaric, I; Hill, R G; Lynch, E

    2014-06-01

    Glass Carbomer is a new generation of restorative material developed from glass-ionomer cements with possibility of gradual mineralization into fluorapatite. The aim of this clinical trial was to investigate the retention of Glass Carbomer fissure sealant after 12 months, in comparison to a commonly used conventional resin-based sealant. Forty-eight teeth in 24 patients [mean (SD) = 8 (2.3) years] with well-delineated fissure morphology were randomly divided into two equal groups and sealed with Bis-GMA resin-based Helioseal F (group A, Ivoclar Vivadent, Liechtenstein) and Glass Carbomer (group B, Glass Carbomer Sealant, Glass Carbomer Products, Leiden, Netherlands) using the split mouth design. Materials were placed and set according to the manufacturer's instructions using a polymerization unit Bluephase 16i (Vivadent, Liechtenstein). Complete sealant retentions in both groups were 100% and 75% after 6 and 12 months of clinical service, respectively. There were there were no secondary caries lesions in both groups after 6 months; two new carious lesions were detected in both groups after 12 months. The Mann-Whitney U test revealed no significant difference between the two groups at both evaluations points (P > 0.05). Glass Carbomer material showed a similar retention rate when compared with a resin-based sealant. Future studies are required to examine the long-term performance of Glass Carbomer sealants. PMID:25134364

  20. Morphological investigation of midblock-sulfonated block ionomers prepared from solvents differing in polarity.

    PubMed

    Mineart, Kenneth P; Jiang, Xi; Jinnai, Hiroshi; Takahara, Atsushi; Spontak, Richard J

    2015-03-01

    Recent developments regarding charged multiblock copolymers that can form physical networks and exhibit robust mechanical properties herald new and exciting opportunities for contemporary technologies requiring amphiphilic attributes. Due to the presence of strong interactions, however, control over the phase behavior of such materials remains challenging, especially since their morphologies can be solvent-templated. In this study, transmission electron microscopy and microtomography are employed to examine the morphological characteristics of midblock-sulfonated pentablock ionomers prepared from solvents differing in polarity. Resultant images confirm that discrete, spherical ion-rich microdomains form in films cast from a relatively nonpolar solvent, whereas an apparently mixed morphology with a continuous ion-rich pathway is generated when the casting solvent is more highly polar. Detailed 3D analysis of the morphological characteristics confirms the coexistence of hexagonally-packed nonpolar cylinders and lamellae, which facilitates the diffusion of ions and/or other polar species through the nanostructured medium. PMID:25537368

  1. Anion conductive aromatic ionomers containing a 1,2-dibenzoylbenzene moiety for alkaline fuel cell applications

    NASA Astrophysics Data System (ADS)

    Hossain, Md. Awlad; Lim, Young-Don; Jang, Ho-Hyoun; Jeon, Young-Tae; Lim, Jin-Sung; Lee, Soon-Ho; Kim, Whan-Gi; Jeon, Heung-Seok

    2013-11-01

    Novel anion-exchange membranes with high conductivities have been prepared for application to alkaline fuel cells. A quaternary ammonium poly(dibenzoylbenzene ether sulfone) membrane was synthesized by chloromethylation, followed by substitution with trimethylamine with an ion-exchange reaction. The quaternary ammonium groups were selectively substituted in the para-position of the pendant phenyl groups of the dibenzoylbenzene unit. The di-quaternary ammonium hydroxide polymers showed an elevated molecular weight and exhibited excellent solubility in polar aprotic solvents. Quaternization and the subsequent ion-exchange reactions were quantitative such that the obtained ionomer membranes had a high ion-exchange capacity (IEC) of up to 1.69 mmolg-1. The resultant polymer membranes were studied by 1H NMR, FT-IR, thermogravimetric analysis (TGA), IEC, water uptake analysis, and ion conductivity analysis.

  2. The room temperature annealing peak in ionomers: Ionic crystallites or water absorption

    SciTech Connect

    Goddard, R.J.; Grady, B.P.; Cooper, S.L. (Univ. of Wisconsin, Madison, WI (United States). Dept. of Chemical Engineering)

    1994-03-28

    A quaternized diol, 3-(trimethylammonio)-1,2-propanediol neutralized with either bromine or iodine, was used to produce a polyurethane cationomer with a poly(tetramethylene oxide) soft segment and a 4,4[prime]-diphenylmethane diisocyanate hard segment. If those cationomers were annealed at room temperature for a period of approximately 1 month in a desiccator filled with dry CaSO[sub 4], differential scanning calorimetry (DSC) studies showed an endotherm centered near 70 C which was not present in the unannealed polymer and did not reappear upon subsequent cooling and heating cycles in the DSC. Some authors have suggested that a very similar endotherm found in other ionomers, most notably ethylene-methacrylic acid (E-MAA) copolymer ionomers, was due to an order-disorder transition within the ionic aggregates, i.e. ionic crystallite melting. In order to isolate the origin of this endotherm, the local environment around the anion in compression molded bromine neutralized samples was measured using the extended X-ray absorption fine-structure (EXAFS) technique. By measuring the change in the local environment over the temperature range corresponding to the DSC endotherm, it has been shown that this endotherm corresponds to water leaving the bromine coordination shell, rather than ionic crystallite melting. Other studies which include thoroughly drying the material in a vacuum oven below the transition temperature to remove the water suggest that the endotherm is due to the energetic change associated with water leaving the coordination environment of the anion in combination with water vaporization.

  3. Photoactive glasses and glass ceramics

    NASA Astrophysics Data System (ADS)

    Ehrt, Doris

    2011-03-01

    Glass and its properties are subject to a variety of changes for many applications. In the last years systematic studies and developments were carried out in the fields of active Nd3+ (f3), Er3+ (f11), and Yb3+ (f13) laser and amplifier glasses. Fluoride and oxide glasses with high intrinsic UV transmission were doped with luminescent species of various electronic configurations, s2: As3+Sb3+Sn2+Pb2+; d0: Ti4+Nb5+Mo6+Ta5+W6+; d10: Zn2+Ag+Cu+; d5: Mn2+; fn: Ce3+(f1), Pr3+ (f2), Sm3+ (f5), Eu3+ (f6), Eu2+ (f7), Tb3+ (f8), Dy3+ (f9), Ho3+ (f10), Er3+ (f11) and Tm3+ (f12). Static and time resolved photoluminescence behavior in the ultraviolet and visible range was investigated depending on glass matrices and concentration of luminescent species. Also the luminescence of Bi-doped glasses was studied, where the kind of the luminescent Bi-species is still unknown. Some glasses were transformed in glass ceramics by thermal treatment. A change of coordination from 6 to 4 was detected for Zn2+ and Mn2+ in the ZnO-Al2O3-SiO2 system. Luminescence intensity can be increased or decreased depending on various conditions.

  4. Ira Glass 

    E-print Network

    Unknown

    2011-08-17

    -recovery tests at various stresses and temperatures are performed on E-glass/vinylester and Eglass/ polyester off-axis specimens. Analytical representation of a nonlinear single integral equation is applied to model the thermo-mechanical viscoelastic responses...

  5. Tempered glass

    SciTech Connect

    Bunnell, L.R.

    1991-11-01

    This document describes a demonstration for making tempered glass using minimal equipment. The demonstration is intended for a typical student of materials science, at the high school level or above. (JL)

  6. Poly(methyl acrylate- co-sodium methacrylate) ionomer studied by solid state 13C T1? NMR

    NASA Astrophysics Data System (ADS)

    Lim, A. R.; Kim, J.-S.

    2000-06-01

    The poly(methyl acrylate) (PMA) and poly(methyl acrylate- co-sodium methacrylate) containing 6.9 mol% of ionic groups (PMANa-6.9) were studied by 13C CP/MAS NMR. The 13C spin-lattice relaxation times in a rotating frame, T1?, have been measured as a function of temperature. Using these T1? spin-lattice relaxation times, we discuss the mobility, the correlation time, and activation energy for the PMA and PMANa-6.9, respectively. The molecular motion in the PMANa-6.9 needs higher activation energies than in PMA. It is worth noting that the motion of the 1-methyl carbons in the PMANa-6.9 ionomer distinctly differs from that in the PMA homopolymer. The slow side of the T1? minimum associated with the 1-methyl carbons is ascribed to stronger interactions between the polymer chains in the ionomer than in the homopolymer.

  7. Glass ionomer ART sealant and fluoride-releasing resin sealant in fissure caries prevention – results from a randomized clinical trial

    PubMed Central

    2014-01-01

    Background The relative performance of ART sealant and fluoride-releasing resin sealant in preventing fissure caries in permanent molars was compared in a randomized clinical trial conducted in southern China (ClinicalTrials.gov NCT01829334). Methods After obtaining ethical approval, healthy schoolchildren who had permanent first molars with occlusal fissures which were sound but deep or presented with only incipient caries were recruited for the study. Included molars were randomly allocated into one of four parallel study groups in units of left/right teeth per mouth. Two of the four groups adopted the methods of ART or fluoride-releasing resin sealant placement while the other two groups adopted the topical fluoride application methods. Fissure status of the molars in each group was evaluated every 6 months. Development of dentine caries and sealant retention over 24 months in the molars in the two sealant-using groups was compared in this report. Outcome on cost-effectiveness of all four groups over 36 months will be reported elsewhere. Results At baseline, a total of 280 children (383 molars) with mean age 7.8 years were involved for the two sealant groups. After 24 months, 261 children (357 molars) were followed. Proportions of molars with dentine caries were 7.3% and 3.9% in the ART sealant and fluoride-releasing resin sealant groups, respectively (chi-square test, p?=?0.171). Life-table survival analysis showed that sealant retention (full and partial) rate over 24 months for the resin sealant (73%) was significantly higher than that (50%) for the ART sealant (p?

  8. Effect of soft segment crystallization and hard segment physical crosslink on shape memory function in antibacterial segmented polyurethane ionomers.

    PubMed

    Zhu, Y; Hu, J; Yeung, K

    2009-11-01

    Shape memory polyurethane (SMPU) ionomers containing constant 75 wt.% soft segment content were synthesized using poly(epsilon-caprolactone)diol, 4,4'-diphenylmethane diisocyanate, 1,4-butanediol and/or N,N-bis(2-hydroxyethyl)-isonicotinamide. To introduce substrate bonding antibacterial activity, pyridinium was prepared through a neutralization reaction using 1-iodooctane as neutralization agent. For the SMPU ionomer film obtained, tensile testing at 70 degrees C and dynamic mechanical analysis suggests that, at temperatures>T(ms) (the melting point of soft segments), 6.72 and 29.55 mol.% pyridinium within hard segments significantly decreased the mechanical properties such as the stress at 100% elongation (70 degrees C), the initial modulus (70 degrees C) and the elastic modulus (75-110 degrees C). Cyclic tensile investigation demonstrated that the two factors, soft segment crystallization and hard segment physical crosslink, play a very important role in shape memory function in SMPU ionomers. For the each individual specimen, the fixity ratio increased, and the recovery ratio decreased with the extension of cooling time. After sufficient cooling time, the fixity ratio of all specimens can reach a high value (approximately 95%). Owing to the disrupted physical crosslink in the sample containing 29.55 mol.% pyridinium, the crystallization rate of soft segments has less effect on shape fixity. Therefore, a high fixity ratio (93.8%) can be achieved in a short cooling time (30 s). In the control sample, the fixity ratio is only 73.7% after 30 s cooling. In addition, the admirable substrate bonding antibacterial activity of prepared SMPU ionomers was verified using standards AACTT 147 and ASTM E2149 in comparison with the control sample. The antibacterial activity of SMPU ionomers on Gram-positive bacteria (Staphylococcus aureus) is significant, and the rate of reduction of bacteria is 100%; the antibacterial activity on Gram-negative bacteria (Klebsiella pneumoniae) increases from 83.6% to 90.7% with increase in pyridinium content from 6.72 to 29.55 mol.%. PMID:19460466

  9. Single-Kernel Ionomic Profiles Are Highly Heritable Indicators of Genetic and Environmental Influences on Elemental Accumulation in Maize Grain (Zea mays)

    PubMed Central

    Baxter, Ivan R.; Ziegler, Gregory; Lahner, Brett; Mickelbart, Michael V.; Foley, Rachel; Danku, John; Armstrong, Paul; Salt, David E.; Hoekenga, Owen A.

    2014-01-01

    The ionome, or elemental profile, of a maize kernel can be viewed in at least two distinct ways. First, the collection of elements within the kernel are food and feed for people and animals. Second, the ionome of the kernel represents a developmental end point that can summarize the life history of a plant, combining genetic programs and environmental interactions. We assert that single-kernel-based phenotyping of the ionome is an effective method of analysis, as it represents a reasonable compromise between precision, efficiency, and power. Here, we evaluate potential pitfalls of this sampling strategy using several field-grown maize sample sets. We demonstrate that there is enough genetically determined diversity in accumulation of many of the elements assayed to overcome potential artifacts. Further, we demonstrate that environmental signals are detectable through their influence on the kernel ionome. We conclude that using single kernels as the sampling unit is a valid approach for understanding genetic and environmental effects on the maize kernel ionome. PMID:24489944

  10. Ionizing radiation-induced copolymerization of 2-ethylhexyl acrylate and acrylic acid and ionomer formation

    NASA Astrophysics Data System (ADS)

    Weaver, Alia

    The ionizing radiation-induced polymerization of acrylate esters is a technique employed for the curing of such materials for a variety of adhesive, coating, ink, and lithographic applications. The work presented in this dissertation involves the synthesis of a copolymer composed of 2-ethylhexyl acrylate (2-EHA) and acrylic acid (AA) using pulsed electron beam and gamma irradiation. The structure and synthesis kinetics of this copolymer were investigated by 1H nuclear magnetic resonance (NMR), electron pulse radiolysis with kinetic spectroscopic detection (PR-KSD), and Fourier transform infrared spectroscopy (FTIR). The effects of total dose, dose rate, and acrylic acid content on the polymerization reaction were studied. The conversion of 2-EHA monomer into polymer at a given total dose was found to be enhanced at lower dose rates and higher concentrations of acrylic acid. The pulse radiolysis investigation of the polymerization of 2-EHA and AA was performed through studies of four different types of systems: (i) neat 2-EHA, (ii) 2-EHA/methanol (MeOH) solutions, (iii) mixtures of 2-EHA and AA, and (iv) 2-EHA/AA/MeOH solutions. The build-up of carbon-centered neutral 2-EHA free radicals in neat 2-EHA was found to obey a second order rate law with a rate coefficient of ((7 +/- 3) x 108)epsilon EHA·, whereas in 2-EHA/AA mixtures it was found to obey a pseudo-first order rate law with a rate coefficient of (1.5 +/- 0.3) x 10 10 mol-1 dm3 s-1. This phenomenon is suggested to originate in the increased H+ ion concentration in the presence of acrylic acid, which leads to a faster neutralization step of 2-EHA radical anions as they are transformed into neutral free radicals during the initiation step of the reaction. An investigation of the formation of ion-containing copolymers (known as ionomers) was performed using the radiation-synthesized poly(2-EHA-co-AA) and iron cations. Verification of successful incorporation of iron into the copolymer was identified by an asymmetric carboxylate stretch at 1600 cm -1 of the FTIR spectrum. TEM analysis of poly(2-EHA-co-AA)/Fe 2+ ionomers formed from formulated compositions involving a 2:1 mole ratio of ferrous acetate to acrylic acid exhibited ionic clusters of approximately 100 nm in diameter, which may include up to 350 ferrous cations.

  11. ELECTROSPRAYING OF GLASSES—PREPARATION OF GLASS COATINGS ON GLASS

    Microsoft Academic Search

    S. Rosenbaum; R. Clasen

    1999-01-01

    Glass coatings on ceramic or metallic substrates are prepared by two different methods. In a two-step process the glass powder is deposited on the glass substrate by methods such as airless spraying of enamel or glaze suspensions, dipping in enamel suspensions, electrospraying or electrophoretic deposition of enamel or glaze suspensions, and electrostatic powder spraying. The particle size of the glass

  12. Glass Transition

    Microsoft Academic Search

    Fumiko Yonezawa; Shoichi Sakamoto; Shuichi Nosé

    1990-01-01

    Computer simulations of melting, crystallization, glass transition, and annealing for a model system of 864 Lennard-Jones (LJ) atoms under a periodic boundary condition are carried out using constant-pressure molec ular dynamics techniques with temperature control. When an fcc crystal of LJ atoms is heated, melting occurs; however, an LJ liquid, when quenched slowly, crystallizes into layers with stacking faults. Each

  13. A Study of the Effect of Heat-Treatment on the Morphology of Nafion Ionomer Dispersion for Use in the Passive Direct Methanol Fuel Cell (DMFC)

    PubMed Central

    Yuan, Ting; Zhang, Haifeng; Zou, Zhiqing; Khatun, Sufia; Akins, Daniel; Adam, Yara; Suarez, Sophia

    2012-01-01

    Aggregation in heat-treated Nafion ionomer dispersion and 117 membrane are investigated by 1H and 19F Nuclear Magnetic Resonance (NMR) spectra, spin-lattice relaxation time, and self-diffusion coefficient measurements. Results demonstrate that heat-treatment affects the average Nafion particle size in aqueous dispersions. Measurements on heat-treated Nafion 117 membrane show changes in the 1H isotropic chemical shift and no significant changes in ionic conductivity. Scanning electron microscopy (SEM) analysis of prepared cathode catalyst layer containing the heat-treated dispersions reveals that the surface of the electrode with the catalyst ink that has been pretreated at ca. 80 °C exhibits a compact and uniform morphology. The decrease of Nafion ionomer’s size results in better contact between catalyst particles and electrolyte, higher electrochemically active surface area, as well as significant improvement in the DMFC’s performance, as verified by electrochemical analysis and single cell evaluation. PMID:24958431

  14. Simulation of ionomer membrane fatigue under mechanical and hygrothermal loading conditions

    NASA Astrophysics Data System (ADS)

    Khorasany, Ramin M. H.; Kjeang, Erik; Wang, G. G.; Rajapakse, R. K. N. D.

    2015-04-01

    Understanding the fatigue lifetime of common perfluorosulfonic acid (PFSA) ionomer membranes under fluctuating hygrothermal conditions is essential for the development of durable fuel cell technologies. For this purpose, a finite element based fatigue lifetime prediction model is developed based on an elastic-plastic constitutive model combined with a Smith-Watson-Topper (SWT) fatigue formulation. The model is validated against previously reported experimental results for a membrane under cyclic mechanical loadings. The validated model is then utilized to investigate the membrane fatigue lifetime in ex-situ applications under cyclic humidity and temperature conditions. The simulations suggest that the membrane fatigue lifetime is shorter under fluctuating humidity loadings than for temperature loadings. Additionally, the membrane fatigue lifetime is found to be more sensitive to the amplitude of the strain oscillations than to the mean strain under hygrothermal cycling. Most notably, the model predicts that simultaneous humidity and temperature cycling can exacerbate the fatigue process and reduce the fatigue lifetime by several orders of magnitude compared to isolated humidity or temperature cycling. The combination of measured mechanical fatigue data and the present numerical model provides a useful toolkit for analysis of membrane fatigue due to hygrothermal variations, which can be costly and time-consuming when addressed experimentally.

  15. Ab Initio Study of Hydration and Proton Dissociation in Ionomer Membranes

    SciTech Connect

    Idupulapati, Nagesh B.; Devanathan, Ramaswami; Dupuis, Michel

    2010-07-01

    We present a comparative study of proton dissociation in various functional acidic units that are promising candidates as building blocks for polymeric electrolyte membranes. Minimum energy structures for four acidic moieties with clusters of 1-6 water molecules were determined using density functional theory at the B3LYP/6-311G** level starting from chemically rational initial configurations. The perfluoro sulfonyl imide acid group (CF3CF2SO2NHSO2CF3) was observed to be the strongest acid, due to the substantial electron withdrawing effect of both fluorocarbon groups. The hydrophilic functional group (CH3OC6H3OCH3C6H4SO3H) of sulfonated polyetherether ketone (SPEEK) membrane was found to be the strongest base with the acidic proton dissociation requiring the addition of six water molecules and the hydrated proton being more tightly bound to the conjugate base. Even though both perfluoro sulfonyl imides and sulfonic acids (hydrophilic functional groups for sulfonyl imide and Nafion ionomers respectively) required only three water molecules to exhibit spontaneous proton dissociation, the largest possible solvent-separated hydronium ion was attained only for the sulfonyl imide moiety. These results provide a scientific basis for understanding the improved conductivity of perfluorinated sulfonyl imide-based membranes relative to that of the widely-used Nafion membrane.

  16. Static light scattering study of fluorocarbon-modified ampholytic acrylamide ionomers

    SciTech Connect

    Watterson, A.C.; Haralabakopoulos, A.; Salamone, J.C. [Univ. of Massachusetts, Lowell, MA (United States)

    1993-12-31

    A series of water-soluble acrylamide ionomers containing small amounts of ampholytic and hydrophobic sites were investigated in dilute aqueous and aqueous salt solutions via static light scattering methods. Elemental analysis verified the ampholytic nature of the polymers while the ion/hydrophobe content was found to be much lower than what was supplied in the feed. Both the molecular weight and radius of gyration exhibited increases with increasing comonomer content to maximum values at 2.5-3.0 mole%. Mw and Rg increased further in 1 M aqueous NaCl and dropped to previous levels in 3 M NaCl. The radius of gyration exhibited sizable increased at 45 and 70{degrees}C in aqueous solution, less so in 1 M NaCl. Dilute aqueous salt expanded the molecules through shielding of the ionic sites, while concentrated aqueous salt increased hydrophobic aggregation decreasing the size of the polymers. At higher temperatures salt ions failed to reach the ionic sites and fluorocarbon aggregation is thought to be responsible for the low radii of gyration.

  17. Oriented Morphology and Anisotropic Transport in Uniaxially Stretched Perfluorosulfonate Ionomer Membranes

    SciTech Connect

    J Park; J Li; G Divoux; L Madsen; R Moore

    2011-12-31

    Relations between morphology and transport sensitively govern proton conductivity in perfluorsulfonate ionomers (PFSIs) and thus determine useful properties of these technologically important materials. In order to understand such relations, we have conducted a broad systematic study of H{sup +}-form PFSI membranes over a range of uniaxial extensions and water uptakes. On the basis of small-angle X-ray scattering (SAXS) and {sup 2}H NMR spectroscopy, uniaxial deformation induces a strong alignment of ionic domains along the stretching direction. We correlate ionic domain orientation to transport using pulsed-field-gradient {sup 1}H NMR measurements of water diffusion coefficients along the three orthogonal membrane directions. Intriguingly, we observe that uniaxial deformation enhances water transport in one direction (parallel-to-draw direction) while reducing it in the other two directions (two orthogonal directions relative to the stretching direction). We evaluate another important transport parameter, proton conductivity, along two orthogonal in-plane directions. In agreement with water diffusion experiments, orientation of ionic channels increases proton conduction along the stretching direction while decreasing it in the perpendicular direction. These findings provide valuable fodder for optimal application of PFSI membranes as well as for the design of next generation polymer electrolyte membranes.

  18. Dynamics of Precise Ethylene-Acrylic Acid Copolymers and Ionomers Using Dielectric Spectroscopy

    NASA Astrophysics Data System (ADS)

    Runt, James; Choi, U. Hyeok; Masser, Hanqing; Buitrago, C. Francisco; Middleton, L. Robert; Winey, Karen; Cordaro, Joseph; Frischknecht, Amalie

    2014-03-01

    This investigation focuses on a molecular-level understanding of the dynamics of novel copolymers, consisting of monodisperse ethylene sequences between very precisely spaced acrylic acid or ionic functionality. Incorporating ions in precise acid copolymers(via neutralization of a portion of the acid functionality) results in significant changes in the association state of the acid and ionic groups, as well as polymer and ion dynamics. The dynamics of these materials were explored over a wide temperature and frequency range using dielectric spectroscopy. Acid copolymers exhibit two local relaxations in the glassy state and a segmental relaxation above Tg. In addition, two slower relaxations above Tg were observed in ionomers, and their origin will be discussed in the presentation. For example, the highest temperature process is assigned to Maxwell-Wagner-Sillars (MWS) interfacial polarization, associated with the microphase separated structure. A transition in the MWS relaxation frequency and strength is observed around the melting point of copolymers with sufficiently long ethylene sequences, suggesting that the MWS process in these materials is strongly correlated with crystallinity of the ethylene backbone. Supported by the National Science Foundation, Polymers Program.

  19. Children's Glasses

    NASA Astrophysics Data System (ADS)

    Akerskog, Gunnar; Soderlund, Jan

    1980-07-01

    There is a common opinion among eye specialists and opticians that children's glasses often are not shaped for optimal fitting. A fundamental reason for this is the lack of data for the shaping of the bows, with the result that most children's glasses are reduced copies of adult's glasses. This report describes a photogrammetric method for collection of primary data for manufac-turing bows for children. An ordinary amateur camera was equipped with a stereo-adapter. With a few arrangements, such as projecting a pattern on the face and keeping the hair away from the ears, 600 children were photographed. A calibration photograph was exposed at the beginning and end of each film or when the equipment had been transported or otherwise disturbed. The photographs were measured in a stereocomparator and the coordinates analytically corrected for distortion. After determination of model coordinates the requested geometric information, such as pupillar distance, eye-ear distance, location of the bridge of the nose etc, was calculated. The shapes of average noses were presented as profile plots.

  20. Microleakage of Class V Methacrylate and Silorane-based Composites and Nano-ionomer Restorations in Fluorosed Teeth

    PubMed Central

    Shafiei, Fereshteh; Abouheydari, Mohadese

    2015-01-01

    Statement of the Problem Enamel and dentin marginal sealing ability of the new adhesive materials could play an important role in successful restoration on fluorosed teeth. Purpose The aim of this in vitro study was to evaluate the marginal microleakage of low-shrinkage silorane-based composite, nano-ionomer, and methacrylate-based composite through self-etching approach or with enamel acid etching. Materials and Method Seventy-two extracted human molars with moderate fluorosed (according to Thylstrup and Fejerskov index, TFI= 4-6) were randomly divided into six groups (n=12). Class V cavities were prepared on the buccal surface at the cementoenamel junction and restored with Clearfil SE Bond/Clearfil AP-X (methacrylate composite), Silorane Adhesive System/Filtek P90 , and nano primer/nano-ionomer according to the manufacturer’s instructions (self-etching approach) or with additional selective enamel acid etching before primer application for each adhesive. After water storage and thermocycling, microleakages of the samples were assessed using dye-penetration technique at the enamel and dentin margins. Data were analyzed using non-parametric tests (? = 0.05).   Results There was a significant difference among the six groups at the enamel margin (p= 0.001), but not at the dentin margin (p= 0.7). For all the three adhesive materials, additional enamel etching resulted in significantly reduced microleakage at the enamel margin (p< 0.05). Conclusion Methacrylate- and silorane-based composites and nano-ionomer revealed a similar and good performance in terms of dentin marginal sealing, but not at the enamel margin. The additional selective enamel etching might improve enamel sealing for the three materials.

  1. A Comparative Ab Initio Study of the Primary Hydration and Proton Dissociation of Various Imide and Sulfonic Acid Ionomers

    SciTech Connect

    Clark II, Jeffrey K.; Paddison, Stephen J.; Eikerling, Michael; Dupuis, Michel; Zawodzinski, Jr., Thomas A.

    2012-03-29

    We compare the role of neighboring group substitutions on proton dissociation of hydrated acidic moieties suitable for proton exchange membranes through electronic structure calculations. Three pairs of ionomers containing similar electron withdrawing groups within the pair were chosen for the study: two fully fluorinated sulfonyl imides (CF3SO2NHSO2CF3 and CF3CF2SO2NHSO2CF3), two partially fluorinated sulfonyl imides (CH3SO2NHSO2CF3 and C6H5SO2NHSO2CF2CF3), and two aromatic sulfonic acid based material s (CH3C6H4SO3H and CH3 OC6 - H3OCH3C6H4SO3H). Fully optimized counterpoise (CP) corrected geometries were obtained for each ionomer fragment with the inclusion of water molecules at the B3LYP/6-311G** level of density functional theory. Spontaneous proton dissociation was observed upon addition of three water molecules in each system, and the transition to a solvent-separated ion pair occurred when four water molecules were introduced. No considerable quantitative or qualitative differences in proton dissociation, hydrogen bond networks formed, or water binding energies were found between systems containing similar electron withdrawing groups. Each of the sulfonyl imide ionomers exhibited qualitatively similar results regarding proton dissociation and separation. The fully fluorinated sulfonyl imides, however, showed a greater propensity to exist in dissociated and ion-pair separated states at low degrees of hydration than the partially fluorinated sulfonyl imides. This effect is due to the additional electron withdrawing groups providing charge stabilization as the dissociated proton migrates away from the imide anion.

  2. Proteomic and ionomic profiling reveals significant alterations of protein expression and calcium homeostasis in cystic fibrosis cells.

    PubMed

    Ciavardelli, Domenico; D'Orazio, Melania; Pieroni, Luisa; Consalvo, Ada; Rossi, Claudia; Sacchetta, Paolo; Di Ilio, Carmine; Battistoni, Andrea; Urbani, Andrea

    2013-06-01

    Cystic fibrosis (CF) is an autosomal recessive disorder associated with mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene and defective chloride transport across the epithelial cell membranes. Abnormal epithelial ion transport is the primary cause of persistent airway infections and chronic inflammation in CF patients. In order to gain further insight into the mechanisms of epithelial dysfunctions linked to CFTR mutations, we performed and integrated proteomic and ionomic analysis of human bronchial epithelial IB3-1 cells and compared them with a CFTR-complemented isogenic cell line (C38). Aside from changes that were consistent with known effects related to CFTR mutations, such as differences in glycolytic and gluconeogenic pathways and unfolded protein responses, differential proteomics highlighted significant alteration of protein expression and, in particular, of the 14-3-3 signalling pathway that is known to be involved in cellular calcium (Ca) homeostasis. Of note, restoring chloride efflux by acting on Ca cellular homeostasis has been shown to be a promising therapeutic intervention for CF. Ionomic analysis showed significant changes in the IB3-1 element profile compared with C38 cells and in particular we observed an increase of intracellular Ca that significantly correlates with intracellular zinc (Zn) levels, suggesting a synergistic role of Ca and Zn influx. This finding is particularly intriguing because Zn has been reported to be effective in CF treatment increasing Ca influx. Taken together, our proteomic and ionomic data reveal that CFTR mutation sets in motion endogenous mechanisms counteracting impaired chloride transport mainly acting on epithelial ion transport and increasing intracellular Ca, suggesting potential links between protein expression and this response. PMID:23609890

  3. Grafted ionomer complexes and their effect on protein adsorption on silica and polysulfone surfaces

    PubMed Central

    de Keizer, Arie; Detrembleur, Christophe; Cohen Stuart, Martien A.; Norde, Willem

    2010-01-01

    We have studied the formation and the stability of ionomer complexes from grafted copolymers (GICs) in solution and the influence of GIC coatings on the adsorption of the proteins ?-lactoglobulin (?-lac), bovine serum albumin (BSA), and lysozyme (Lsz) on silica and polysulfone. The GICs consist of the grafted copolymer PAA28-co-PAPEO22 {poly(acrylic acid)-co-poly[acrylate methoxy poly(ethylene oxide)]} with negatively charged AA and neutral APEO groups, and the positively charged homopolymers: P2MVPI43 [poly(N-methyl 2-vinyl pyridinium iodide)] and PAH?HCl160 [poly(allylamine hydrochloride)]. In solution, these aggregates are characterized by means of dynamic and static light scattering. They appear to be assemblies with hydrodynamic radii of 8 nm (GIC-PAPEO22/P2MVPI43) and 22 nm (GIC-PAPEO22/PAH?HCl160), respectively. The GICs partly disintegrate in solution at salt concentrations above 10 mM NaCl. Adsorption of GICs and proteins has been studied with fixed angle optical reflectometry at salt concentrations ranging from 1 to 50 mM NaCl. Adsorption of GICs results in high density PEO side chains on the surface. Higher densities were obtained for GICs consisting of PAH?HCl160 (1.6?÷?1.9 chains/nm2) than of P2MVPI43 (0.6?÷?1.5 chains/nm2). Both GIC coatings strongly suppress adsorption of all proteins on silica (>90%); however, reduction of protein adsorption on polysulfone depends on the composition of the coating and the type of protein. We observed a moderate reduction of ?-lac and Lsz adsorption (>60%). Adsorption of BSA on the GIC-PAPEO22/P2MVPI43 coating is moderately reduced, but on the GIC-PAPEO22/PAH?HCl160 coating it is enhanced. PMID:21125002

  4. Molecular modeling of proton transport in the short-side-chain perfluorosulfonic acid ionomer.

    PubMed

    Hristov, Iordan H; Paddison, Stephen J; Paul, Reginald

    2008-03-13

    An explanation for the superior proton conductivity of low equivalent weight (EW) short-side-chain (SSC) perfluorosulfonic acid membranes is pursued through the determination of hydrated morphology and hydronium ion diffusion coefficients using classical molecular dynamics (MD) simulations. A unique force field set for the SSC ionomer was derived from torsion profiles determined from ab initio electronic structure calculations of an oligomeric fragment consisting of two side chains. MD simulations were performed on a system consisting of a single macromolecule of the polymer (EW of 580) with the general formula F3C-[CF(OCF2CF2SO3H)-(CF2)7]40-CF3 at hydration levels corresponding to 3, 6, and 13 water molecules per sulfonic acid group. Examination of the hydrated morphology indicates the formation of hydrogen bond "bridges" between distant sulfonate groups without significant bending of the polytetrafluoroethylene backbone. Pair correlation functions of the system identify the presence of ion cages consisting of hydronium ions hydrogen-bonded to three sulfonate groups at the lowest water content. Such structures exhibit very low S-OH3+ separations, well below 4 A and severely inhibit vehicular diffusion of the protons. The number of sulfonate groups in the first solvation shell of a given hydronium ion correlates well with the differences between Nafion and the SSC polymer (Hyflon). The calculated hydronium ion diffusion coefficients of 2.84 x 10-7, 1.36 x 10-6, and 3.47 x 10-6 cm2/s for water contents of 3, 6, and 13, respectively, show only good agreement to experimentally measured values at the lowest water content, underscoring the increasing contribution of proton shuttling or hopping at the higher hydration levels. At the highest water content, the vehicular diffusion accounts for only about 1/5 of the total proton transport similar to that observed in Nafion. PMID:18281980

  5. Metal glasses

    NASA Astrophysics Data System (ADS)

    Belen'kii, Aleksei Iakovlevich

    1987-02-01

    Methods of producing amorphous alloys of various systems (e.g., Pd-Si, Fe-B, Ni-P, Ni-Nb, Ni-Ta, Co-Gd, Fe-Gd, Mg-Zn,and Ca-Al) are briefly discussed, and the atomic structure and properties of such alloys are examined. In particular, attention is given to anomalies in the low-temperature behavior of amorphous alloys, their electrical and magnetic properties, strength, ductility, and corosion stability. Some aplications of metal glasses are mentioned.

  6. Analysis of Arabidopsis thaliana atfer4-1, atfh and atfer4-1/atfh mutants uncovers frataxin and ferritin contributions to leaf ionome homeostasis.

    PubMed

    Murgia, Irene; Vigani, Gianpiero

    2015-09-01

    Ferritins are iron-storage proteins involved in the environmental and developmental control of the free iron pool within cells. Plant ferritins are targeted to mitochondria as well as to chloroplasts. AtFer4 is the Arabidopsis thaliana ferritin isoform that can be also targeted to mitochondria. Frataxin is a mitochondrial protein whose role is essential for plants; lack of AtFH frataxin causes early embryo-lethality in Arabidopsis. Because of that, the Arabidopsis atfh KO mutant is propagated in heterozygosis. For exploring the functional interaction between frataxin and ferritin, Arabidopsis double mutant atfer4-1/atfh was isolated and its physiological parameters were measured, as well as its ionome profile, together with those of both atfer4 and atfh single mutants, in different conditions of Fe supply. Impairment of both ferritin and frataxin did not lead to any effect on mitochondrial respiration. However, ionomics revealed that the content of macro- and microelements, occurring when the nutritional Fe supply changes, were altered in the mutants analysed. These results suggest that both ferritin and frataxin can contribute to the composition of the leaf ionome and also confirm ionomics as an excellent tool for detecting alterations in the plant's physiology. PMID:26042547

  7. Cathode catalyst layers with ionomer to carbon mass ratios in the range 0-2 studied by electrochemical impedance spectroscopy, cyclic voltammetry, and performance measurements

    NASA Astrophysics Data System (ADS)

    Modestov, Alexander D.; Kapustin, Alexander V.; Avakov, Veniamin B.; Landgraf, Igor K.; Tarasevich, Mikhail R.

    2014-12-01

    Characteristics of the cathode catalyst layers (CCL) containing HiSPEC 9100 Pt/C catalyst and ionomer (I) in ionomer to carbon mass ratio (I/C) range 0-2 were studied. Pt electrochemically active surface area (ECSA) and electrode low frequency capacitance were found to be independent of I/C value. Ionic resistance of CCL was found strongly dependent of I/C value. It reaches maximum value at I/C?0.3. Ionic resistance of CCL with I/C = 0.05 increased 7 fold with the shift of electrode potential (E) from 0.4 V to 1.05 vs. RHE. Ionic resistance of an imitating layer, which contained ionomer-free Ketjenblack EC-300J carbon, increased by a factor of 20 with the potential shift from 0.1 V to 1.05 V vs. RHE. Ionic conductivity in ionomer-free CCLs is ascribed to the presence of protons which originate from ionization of oxygen containing acidic surface groups of carbon support. Application to the CCL of potential positive relative to potential of zero charge of carbon support (pzc) draws protons to the counter electrode, decreasing the ionic conductivity of the CCL. Pt mass specific activity (Im) dependence on I/C mass ratio reaches maximum at I/C ? 1.

  8. Methodological approaches for using synchrotron X-ray fluorescence (SXRF) imaging as a tool in ionomics: Examples from Arabidopsis thaliana

    PubMed Central

    Hindt, Maria; Socha, Amanda L.; Zuber, Hélène

    2013-01-01

    Here we present approaches for using multi-elemental imaging (specifically synchrotron X-ray fluorescence microscopy, SXRF) in ionomics, with examples using the model plant Arabidopsis thaliana. The complexity of each approach depends on the amount of a priori information available for the gene and/or phenotype being studied. Three approaches are outlined, which apply to experimental situations where a gene of interest has been identified but has an unknown phenotype (Phenotyping), an unidentified gene is associated with a known phenotype (Gene Cloning) and finally, a Screening approach, where both gene and phenotype are unknown. These approaches make use of open-access, online databases with which plant molecular genetics researchers working in the model plant Arabidopsis will be familiar, in particular the Ionomics Hub and online transcriptomic databases such as the Arabidopsis eFP browser. The approaches and examples we describe are based on the assumption that altering the expression of ion transporters can result in changes in elemental distribution. We provide methodological details on using elemental imaging to aid or accelerate gene functional characterization by narrowing down the search for candidate genes to the tissues in which elemental distributions are altered. We use synchrotron X-ray microprobes as a technique of choice, which can now be used to image all parts of an Arabidopsis plant in a hydrated state. We present elemental images of leaves, stem, root, siliques and germinating hypocotyls. PMID:23912758

  9. Comparative ionomics and metabolomics in extremophile and glycophytic Lotus species under salt stress challenge the metabolic pre-adaptation hypothesis.

    PubMed

    Sanchez, Diego H; Pieckenstain, Fernando L; Escaray, Francisco; Erban, Alexander; Kraemer, Ute; Udvardi, Michael K; Kopka, Joachim

    2011-04-01

    The legume genus Lotus includes glycophytic forage crops and other species adapted to extreme environments, such as saline soils. Understanding salt tolerance mechanisms will contribute to the discovery of new traits which may enhance the breeding efforts towards improved performance of legumes in marginal agricultural environments. Here, we used a combination of ionomic and gas chromatography-mass spectrometry (GC-MS)-based metabolite profilings of complete shoots (pooling leaves, petioles and stems) to compare the extremophile Lotus creticus, adapted to highly saline coastal regions, and two cultivated glycophytic grassland forage species, Lotus corniculatus and Lotus tenuis. L. creticus exhibited better survival after exposure to long-term lethal salinity and was more efficient at excluding Cl? from the shoots than the glycophytes. In contrast, Na+ levels were higher in the extremophile under both control and salt stress, a trait often observed in halophytes. Ionomics demonstrated a differential rearrangement of shoot nutrient levels in the extremophile upon salt exposure. Metabolite profiling showed that responses to NaCl in L. creticus shoots were globally similar to those of the glycophytes, providing little evidence for metabolic pre-adaptation to salinity. This study is the first comparing salt acclimation responses between extremophile and non-extremophile legumes, and challenges the generalization of the metabolic salt pre-adaptation hypothesis. PMID:21251019

  10. Influence of the ionomer/carbon ratio for low-Pt loading catalyst layer prepared by reactive spray deposition technology

    NASA Astrophysics Data System (ADS)

    Yu, Haoran; Roller, Justin M.; Mustain, William E.; Maric, Radenka

    2015-06-01

    Proton exchange membrane fuel cell (PEMFC) catalyst layers (CLs) were fabricated by direct deposition of the catalyst onto Nafion® membranes using reactive spray deposition technique (RSDT) to reduce platinum (Pt) loading and reduce the number of catalyst synthesis and processing steps. Nitrogen adsorption, mercury porosimetry, and scanning electron microscopy (SEM) were used to investigate the effects of ionomer/carbon ratio (I/C) on the surface area, pore structure and morphology of the CLs; cyclic voltammetry and polarization curves were used to determine the electrochemically active area (ECSA) and PEMFC performance. The BET surface area and pore volume of the CLs decreased continuously with increasing I/C ratio regardless of the catalyst loading. Bimodal distribution of pores with diameters ranging from 1.7 to 10 nm and from 30 to 100 nm were observed from the pore-size distribution of the CLs. The catalyst-coated membrane (CCM) with an I/C ratio of 0.3 showed the highest ECSA of 62 m2 gPt-1 and the best performance at 0.6 V for oxygen (1400 mA cm-2) and air (650 mA cm-2) among all RSDT samples. The optimum I/C ratio is lower compared to ink-based methods, and Pt nanoparticles showed improved distribution on the carbon surface. The RSDT process shows promise in achieving better ionomer coverage and penetration in the CL microstructure, enhancing the performance of low Pt-loading PEMFCs.

  11. CRYSTALLIZATION IN MULTICOMPONENT GLASSES

    SciTech Connect

    KRUGER AA; HRMA PR

    2009-10-08

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  12. Impact Strength of Glass and Glass Ceramic

    NASA Astrophysics Data System (ADS)

    Bless, Stephan; Tolman, John

    2009-06-01

    Bar impact tests, using the techniques described elsewhere in this symposium, were used to measure compressive and tensile strengths of borosilicate glass, soda lime glass, and glass ceramic. The glass ceramic was 25% crystalline spinel, furnished by Corning, Inc. There are two measures of compressive strength: the peak stress that can be transmitted in unconfined compression and the steady-state strength. For both glasses, these values were similar, being about 1.8 and 1.5 GPa, respectively. The glass ceramic was almost 50% stronger. Tensile failure in the glass and glass ceramic takes places via surface flaws, and thus tensile strength is an extrinsic---as opposed to intrinsic---property.

  13. Impact Strength of Glass and Glass Ceramic

    NASA Astrophysics Data System (ADS)

    Bless, S.; Tolman, J.

    2009-12-01

    Strength of glass and glass ceramic was measured with a bar impact technique. High-speed movies show regions of tensile and compressive failure. The borosilicate glass had a compressive strength of at least 2.2 GPa, and the glass ceramic at least 4 GPa. However, the BSG was much stronger in tension than GC. In ballistic tests, the BSG was the superior armor.

  14. IMPACT STRENGTH OF GLASS AND GLASS CERAMIC

    SciTech Connect

    Bless, S.; Tolman, J. [Institute for Advanced Technology, University of Texas at Austin, Austin, TX 78759 (United States)

    2009-12-28

    Strength of glass and glass ceramic was measured with a bar impact technique. High-speed movies show regions of tensile and compressive failure. The borosilicate glass had a compressive strength of at least 2.2 GPa, and the glass ceramic at least 4 GPa. However, the BSG was much stronger in tension than GC. In ballistic tests, the BSG was the superior armor.

  15. Side chain flexibility in perfluorosulfonic acid ionomers: an ab initio study.

    PubMed

    Clark, Jeffrey K; Paddison, Stephen J

    2013-10-10

    Side chain flexibility in perfluorosulfonic acid (PFSA) ionomers has been explored through ab initio electronic structure calculations. Three different PFSA side chain fragments were considered with a CF3CFCF3 backbone representation: Nafion (-OCF2CF(CF3)O(CF2)2SO3H), Aquivion or the short side chain (SSC) (-O(CF2)2SO3H), and the 3M PFSA (-O(CF2)4SO3H). Rotational potential energy surfaces for each bond along the length of the side chains were obtained using density functional theory with the B3LYP and the dispersion-corrected B97D functionals with and without the inclusion of a solvation model. Solvent effects were found to have minimal effect on bond rotations close to the tetrafluoroethylene backbone but had greater impact near the terminal sulfonic acid group. The carbon-sulfur bond was found to be the most flexible portion of the side chain in each of the fragments which was further enhanced with the inclusion of the solvent. Complete rotation about either the O-CF2 or CF-O bond in the Nafion side chain resulted in fairly high energetic barriers, but significant portions of these rotational surfaces had energetic penalties less than 1.5 kcal/mol indicating substantial conformational freedom. Fully extended and folded conformations of the Nafion side chain exhibit considerable contraction in side chain end-to-end distance and were observed to be nearly isoenergetic using B3LYP, but the folded structures with the ether oxygen atoms in gauche conformations were ~1.5 kcal/mol lower in energy using B97D. Below the second ether linkage of the Nafion side chain, the rotational potential energy profiles were identical to that determined for the SSC side chain. The 3M side chain was generally found to be the most rigid with barriers for complete rotation about the central carbon-carbon bonds of approximately 7 kcal/mol. These results indicate that minor differences in side chain length and chemistry may have a pronounced effect on the rotational potential energy surfaces, particularly those involving rotation about different carbon-carbon bonds with distinctly different character. PMID:24041417

  16. Treating root-surface caries

    Microsoft Academic Search

    John O. Burgess; John R. Gallo

    2002-01-01

    Gingival recession associated with aging and periodontal therapy exposes root surfaces, which are then susceptible to root caries. Resin-modified glass ionomer, glass ionomer, compomer, composite resin, and amalgam restora- tive materials are frequently used to restore carious root lesions. Amalgam continues to be used successfully to restore root caries. Resin composites, compomers, glass ionomers, and resin-modified glass ionomers are increas-

  17. Prussian blue nanocontainers: selectively permeable hollow metal-organic capsules from block ionomer emulsion-induced assembly.

    PubMed

    Roy, Xavier; Hui, Joseph K-H; Rabnawaz, Muhammad; Liu, Guojun; MacLachlan, Mark J

    2011-06-01

    Hollow polymer-based particles are useful for the encapsulation, protection, and release of active compounds. Adding a metal-organic coordination framework shell to nanocontainers is an attractive goal because it should help control their stability and permeability while yielding new properties and functions. We have discovered that polymer capsules with a Prussian blue analogue inner shell can be synthesized by emulsion-induced assembly of a metal-containing amphiphilic block ionomer. The capsules are selectively permeable and were used as nanocontainers to encapsulate and release a model compound. Further, these nanomaterials are tunable in size and organize into 2-D close-packed arrays in the solid state. Potential applications for these materials include the encapsulation and nanopatterning of pharmaceutical, biological, and catalytic compounds. PMID:21557609

  18. Thermodynamic glass transitions in three dimensional glasses

    NASA Astrophysics Data System (ADS)

    Berthier, Ludovic

    2015-03-01

    The physics associated to the glass transition controls the dramatic evolution of transport coefficients in systems as diverse as dense liquids, polymers, colloids, but also granular particles and active matter. The experimental liquid-glass transition in equilibrium fluids is characterized by several phenomenological crossovers, but glasses can form without crossing any sharp singularity. I will present multiple evidences suggesting that the glass formation process is underlied by equilibrium phase transitions. Combining numerical tools developed to study ordinary phase transitions to recent theoretical analytical progress I will demonstrate that studies of the glass transition have entered a new phase, where the relevant order parameter, thermodynamic fluctuations and phase transformations can be directly analysed in finite dimensional model glasses.

  19. Picture Wall (Glass Structures)

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Photo shows a subway station in Toronto, Ontario, which is entirely glass-enclosed. The all-glass structure was made possible by a unique glazing concept developed by PPG Industries, Pittsburgh, Pennsylvania, one of the largest U.S. manufacturers of flat glass. In the TVS glazing system, transparent glass "fins" replace conventional vertical support members used to provide support for wind load resistance. For stiffening, silicone sealant bonds the fins to adjacent glass panels. At its glass research center near Pittsburgh, PPG Industries uses the NASTRAN computer program to analyze the stability of enclosures made entirely of glass. The company also uses NASTRAN to simulate stresses on large containers of molten glass and to analyze stress effects of solar heating on flat glass.

  20. Photoluminescence in glasses and glass ceramics

    NASA Astrophysics Data System (ADS)

    Ehrt, Doris

    2009-07-01

    Photoluminescence in the UV-VIS region is a very sensitive analytical method and also an important optical property of glasses and glass ceramics for different applications which depends strongly on active centers, surrounding host glass composition and their interactions. Fluoride, phosphate, and silicate glasses of high intrinsic UV transmission and high purity doped with active luminescent ions of different electronic configurations (s2: As3+, Sb3+, Sn2+, Pb2+; d0: Ti4+, Nb+, Mo6+, Ta5+, W6; d10: Zn2+, Ag+ and Cu+, d5: Mn2+, fn like Sm3+, Eu3+, Eu2+, Tb3+) were investigated. Some glasses were transformed in glass ceramics. Distribution of coordination and change in the case of Zn2+ and Mn2+ were detected. Mn2+ can substitute Zn2+ in glass and also in crystal phases, Zn2SiO4 (willemite) and ZnAl2O4 (gahnite). But the larger RE ions cannot do it. So, the luminescence can be increased or decreased by the transformation of glasses in glass ceramics. Blue, green and red photoluminescence emission with various lifetimes, ?e ~ 1 ?s to 25 ms, were registered.

  1. Melt crystallization of bisphenol A polycarbonate in PC/zinc sulfonated polystyrene ionomer blend

    NASA Astrophysics Data System (ADS)

    Xu, Liang

    The effects of zinc sulfonated polystyrene ionomer (ZnSPS) on the melt crystallization of bisphenol A polycarbonate (PC) were investigated. Melt crystallization of pure PC is extremely slow due to its rigid chain. In the blend of PC and ZnSPS (PC-ZnSPS), the melt crystallization rate of PC can be enhanced. DSC was used to study the crystallization kinetics of PC in PC-ZnSPS blend. The crystallization of PC at 190°C increased in both partially miscible and miscible blends with ZnSPS. For PC-ZnSPS blend with same PC composition as 80%, the crystallization rate was affected by the sulfonation level of ZnSPS. The induction time of crystallization for a partially miscible blend PC-ZnSPS9.98 (80/20) was 40 minutes, and the crystallization reaches 27% crystallinity within 14 hrs. The induction time for pure PC with the same thermal history was more than 24 hrs. The crystal structure of PC crystal formed in PC-ZnSPS blend was studied by WAXD, which showed no difference from the reported WAXD pattern for pure PC. Molecular weight change of PC was found during the thermal annealing of PC-ZnSPS blend at 190°C, but molecular weight alone cannot explain the change of crystallization rate of PC in PC-ZnSPS blend. Discussion was made to address the mechanisms that are responsible for the crystallization rate enhancement of PC in PC-ZnSPS blend. In order to understand and elucidate the reason for the molecular weight change of PC in PC-ZnSPS blend and its effect on the crystallization of PC, TG, GPC and GC-MS were used to investigate the stability of PC-ZnSPS blend and mixtures of PC with sodium tosylate (NaTS), zinc tosylate (ZnTS) and sodium benzoate (NaBZ). ZnSPS, NaTS and ZnTS undergo desulfonation of the sulfonate group at temperatures above 350°C. The desulfonation process can destabilize PC and lower the maximum mass loss rate temperature of PC for more than 70°C. NaTS, ZnTS and NaBZ have quite different effect on the thermal stability of PC at temperatures below 250°C. NaBZ can significantly degrade PC both at 190°C and 250°C. PC does not show any molecular weight (M w) change in the presence of NaTS at 250°C and 190°C for up to 1hr and 16 hrs respectively. ZnTS can also cause Mw change of PC at 250°C and 190°C, but the changing of Mw of PC in the presence of ZnTS is less than that in the presence of NaBZ. The reason for the molecular weight change of PC in PC-ZnSPS blend can be explained based on Davis's ionic ester exchange reaction mechanism.

  2. A proof of principle experiment: Structural transitions in self-healing poly (ethylene co-methacrylic acid) ionomers using acoustic and ultrasonic time dependent resonant spectroscopy

    NASA Astrophysics Data System (ADS)

    Pestka, K. A.; Kalista, S. J.; Ricci, A.

    2013-08-01

    We demonstrate a method for assessing structural transitions in self-healing poly (ethylene co-methacrylic acid) ionomers as a function of time, by observing the evolution of their acoustic and ultrasonic resonant spectra and associated quality factors during the post-damage healing phase. Two samples composed of EMAA-0.6Na and EMAA-0.3Na were scanned from 1 kHz to 2 MHz before and after a damage event. After damage, time varying resonances were discovered using time dependent resonant spectroscopy (TDRS), and several of these resonances continued to evolve after visible changes in the samples ceased. These time dependent resonances enable characterization of energy dissipation, relaxation and structural ordering in self-healing ionomers. In addition, TDRS may provide a method for isolating material properties that affect the healing process, such as ion content and their associated structures as well as the effect of sample aging, which may lead to improved structural models.

  3. Variations in interfacial properties during cell conditioning and influence of heat-treatment of ionomer on the characteristics of direct methanol fuel cells

    Microsoft Academic Search

    Fuqiang Liu; Chao-Yang Wang

    2005-01-01

    Variations in interfacial properties in the anode catalyst layer during cell conditioning were characterized, and influence of the heat-treatment of ionomer on the characteristics of direct methanol fuel cells was investigated in this work. The anode catalyst layer was made by mixing a solvent-substituted Nafion solution with unsupported Pt\\/Ru black and curing the mixture in an oven with an inert

  4. Evaluating chemical degradation of proton conducting perfluorosulfonic acid ionomers in a Fenton test by solid-state 19F NMR spectroscopy

    Microsoft Academic Search

    L. Ghassemzadeh; K. D. Kreuer; J. Maier; K. Müller

    2011-01-01

    Chemical degradation and stability of perfluorosulfonic acid (PFSA) ionomers against radical attack were investigated by an (ex situ) Fenton test. Solid-state and solution NMR as well as ATR-FTIR studies were performed on the samples before and after the Fenton reaction. By changing the concentration of the Fenton's solution it is found that the metallic catalyst (Fe2+) is a critical factor

  5. Glasses for Children

    MedlinePLUS

    ... especially when their child is an infant or toddler. The best answer is that most young children ... to help the child adjust to the glasses. Toddlers often may wear the glasses only when they ...

  6. Alice through Looking Glass after Looking Glass

    E-print Network

    Goodman, Roe

    Alice through Looking Glass after Looking Glass: The Mathematics of Mirrors and Kaleidoscopes Roe back in time for tea. #12;Alice's Kaleidoscope Problem: · Kaleidoscope: Arrangement of n mirrors (hyperplanes through 0) in n-dimensional Euclidean space · Kaleidoscope Condition: Multiple reflections

  7. Nanoparticle Stained Glass

    NSDL National Science Digital Library

    2014-06-18

    In this activity/demo, learners are introduced to the connection between medieval stained glass artisans and nanotechnology. Learners discover that the red and yellow colors in stained glass windows come from nanoparticles of gold and silver embedded in the glass. This activity/demo consists of two hands-on activities: making a collaborative stained glass window with pre-made nanoparticle solutions containing silver or gold and making a take-away card that contains a small piece of nanoparticle stained “glass."

  8. Radiation coloration resistant glass

    DOEpatents

    Tomozawa, Minoru (Troy, NY); Watson, E. Bruce (Troy, NY); Acocella, John (Troy, NY)

    1986-01-01

    A radiation coloration resistant glass is disclosed which is used in a radiation environment sufficient to cause coloration in most forms of glass. The coloration resistant glass includes higher proportions by weight of water and has been found to be extremely resistant to color change when exposed to such radiation levels. The coloration resistant glass is free of cerium oxide and has more than about 0.5% by weight water content. Even when exposed to gamma radiation of more than 10.sup.7 rad, the coloration resistant glass does not lose transparency.

  9. Radiation coloration resistant glass

    DOEpatents

    Tomozawa, M.; Watson, E.B.; Acocella, J.

    1986-11-04

    A radiation coloration resistant glass is disclosed which is used in a radiation environment sufficient to cause coloration in most forms of glass. The coloration resistant glass includes higher proportions by weight of water and has been found to be extremely resistant to color change when exposed to such radiation levels. The coloration resistant glass is free of cerium oxide and has more than about 0.5% by weight water content. Even when exposed to gamma radiation of more than 10[sup 7] rad, the coloration resistant glass does not lose transparency. 3 figs.

  10. Oxynitride glass production procedure

    DOEpatents

    Weidner, Jerry R. (Idaho Falls, ID); Schuetz, Stanley T. (Idaho Falls, ID); O'Brien, Michael H. (Idaho Falls, ID)

    1991-01-01

    The invention is a process for the preparation of high quality oxynitride glasses without resorting to high pressures. Nitrogen-containing compounds such as Si.sub.3 N.sub.4 are first encapsulated in a low melting temperature glass. Particles of the encapsulated nitrogen-containing compound are mixed with other oxide glass-formers and melted in an atmosphere of flowing nitrogen and in the presence of buffering gas to form the oxynitride glass. Glasses containing up to 15 at % nitrogen have been prepared by this method.

  11. Characterization of glass surfaces

    NASA Astrophysics Data System (ADS)

    Lee, C. T.; Clark, D. E.

    1985-02-01

    Significant advances have been made during the last 15 years in our understanding of glass surfaces and their environmental reactivity. The major reason for this advancement is the large array of surface analytical techniques that has been developed and applied to many industrial problems. One specific area of research where surface analysis has been proven valuable is glass corrosion. Until recently, the principal methods for studying degradation of glasses were weight loss measurements and solution analytical techniques. Neither of these provide information on surface alterations resulting from corrosion. Consequently, very little was known about the variety of mechanisms by which glass corrosion occurs. Currently, a multi-technique approach is being used in many laboratories around the world in order to achieve a better understanding of corrosion on glasses designed for immobilizing nuclear wastes. Similar approaches are being taken to solve problems related to conventional glass fabrication, glass preservation, and to new glass manufacturing processes based on sol-gel technology. In the present paper several techniques which are being routinely used to characterize glass surfaces are discussed. These include Fourier transform infrared reflection spectroscopy (FT-IRRS), secondary ion mass spectroscopy (SIMS), Auger electron spectroscopy coupled with ion milling (AES-IM) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS). Each of these techniques provide unique information about glass surfaces, and when used in combination can yield solutions to complex industrial and scientific problems.

  12. A macroscopic model of proton transport through the membrane-ionomer interface of a polymer electrolyte membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Kumar, Milan; Edwards, Brian J.; Paddison, Stephen J.

    2013-02-01

    The membrane-ionomer interface is the critical interlink of the electrodes and catalyst to the polymer electrolyte membrane (PEM); together forming the membrane electrode assembly in current state-of-the-art PEM fuel cells. In this paper, proton conduction through the interface is investigated to understand its effect on the performance of a PEM fuel cell. The water containing domains at this interface were modeled as cylindrical pores/channels with the anionic groups (i.e., -SO3-) assumed to be fixed on the pore wall. The interactions of each species with all other species and an applied external field were examined. Molecular-based interaction potential energies were computed in a small test element of the pore and were scaled up in terms of macroscopic variables. Evolution equations of the density and momentum of the species (water molecules and hydronium ions) were derived within a framework of nonequilibrium thermodynamics. The resulting evolution equations for the species were solved analytically using an order-of-magnitude analysis to obtain an expression for the proton conductivity. Results show that the conductivity increases with increasing water content and pore radius, and strongly depends on the separation distance between the sulfonate groups and their distribution on the pore wall. It was also determined that the conductivity of two similar pores of different radii in series is limited by the pore with the smaller radius.

  13. Cerium oxide nanoparticles alter the antioxidant capacity but do not impact tuber ionome in Raphanus sativus (L).

    PubMed

    Corral-Diaz, Baltazar; Peralta-Videa, Jose R; Alvarez-Parrilla, Emilio; Rodrigo-García, Joaquin; Morales, Maria Isabel; Osuna-Avila, Pedro; Niu, Genhua; Hernandez-Viezcas, Jose A; Gardea-Torresdey, Jorge L

    2014-11-01

    The effects of nCeO2 on food quality are not well known yet. This research was performed to determine the impact of nCeO2 on radish (Raphanus sativus L.). Plants were cultivated to full maturity in potting soil treated with nCeO2 at concentrations of 0, 62.5, 125, 250, and 500 mg/kg. Germination, growth, photosynthesis, ionome, and antioxidants were evaluated at different growth stages. Results showed that at 500 mg/kg, nCeO2 significantly retarded seed germination but did not reduce the number of germinated seeds. None of the treatments affected gas exchange, photosynthesis, growth, phenols, flavonoids, and nutrients' accumulation in tubers and leaves of adult plants. However, tubers' antioxidant capacity, expressed as FRAP, ABTS(•-) and DPPH, increased by 30%, 32%, and 85%, respectively, in plants treated with 250 mg nCeO2kg(-1) soil. In addition, cerium accumulation in tubers of plants treated with 250 and 500 mg/kg reached 72 and 142 mg/kg d wt, respectively. This suggests that nCeO2 could improve the radical scavenging potency of radish but it might introduce nCeO2 into the food chain with unknown consequences. PMID:25439500

  14. Nonequilibrium viscosity of glass

    NASA Astrophysics Data System (ADS)

    Mauro, John C.; Allan, Douglas C.; Potuzak, Marcel

    2009-09-01

    Since glass is a nonequilibrium material, its properties depend on both composition and thermal history. While most prior studies have focused on equilibrium liquid viscosity, an accurate description of nonequilibrium viscosity is essential for understanding the low temperature dynamics of glass. Departure from equilibrium occurs as a glass-forming system is cooled through the glass transition range. The glass transition involves a continuous breakdown of ergodicity as the system gradually becomes trapped in a subset of the available configurational phase space. At very low temperatures a glass is perfectly nonergodic (or “isostructural”), and the viscosity is described well by an Arrhenius form. However, the behavior of viscosity during the glass transition range itself is not yet understood. In this paper, we address the problem of glass viscosity using the enthalpy landscape model of Mauro and Loucks [Phys. Rev. B 76, 174202 (2007)] for selenium, an elemental glass former. To study a wide range of thermal histories, we compute nonequilibrium viscosity with cooling rates from 10-12 to 1012K/s . Based on these detailed landscape calculations, we propose a simplified phenomenological model capturing the essential physics of glass viscosity. The phenomenological model incorporates an ergodicity parameter that accounts for the continuous breakdown of ergodicity at the glass transition. We show a direct relationship between the nonequilibrium viscosity parameters and the fragility of the supercooled liquid. The nonequilibrium viscosity model is validated against experimental measurements of Corning EAGLE XG™ glass. The measurements are performed using a specially designed beam-bending apparatus capable of accurate nonequilibrium viscosity measurements up to 1016Pas . Using a common set of parameters, the phenomenological model provides an accurate description of EAGLE XG™ viscosity over the full range of measured temperatures and fictive temperatures.

  15. Diamond turning of glass

    SciTech Connect

    Blackley, W.S.; Scattergood, R.O.

    1988-12-01

    A new research initiative will be undertaken to investigate the critical cutting depth concepts for single point diamond turning of brittle, amorphous materials. Inorganic glasses and a brittle, thermoset polymer (organic glass) are the principal candidate materials. Interrupted cutting tests similar to those done in earlier research are Ge and Si crystals will be made to obtain critical depth values as a function of machining parameters. The results will provide systematic data with which to assess machining performance on glasses and amorphous materials

  16. Scintillating Fluorohafnate Glasses

    Microsoft Academic Search

    S. Kh. Batygov; M. N. Brekhovskikh; N. N. Vinogradova; L. N. Dmitruk; L. V. Moiseeva; V. A. Fedorov

    2002-01-01

    Data are presented on the roentgenoluminescence and gamma-radiation resistance of Ce3+-doped fluorohafnate glasses prepared under different redox conditions and containing different additions. The glasses are shown to contain several types of luminescence centers and radiation-induced color centers, whose concentrations are governed by the preparation conditions and the nature of the dopants. The radiation resistance and light output of the glasses

  17. Apollo 15 green glasses.

    NASA Technical Reports Server (NTRS)

    Ridley, W. I.; Reid, A. M.; Warner, J. L.; Brown, R. W.

    1973-01-01

    The samples analyzed include 28 spheres, portions of spheres, and angular fragments from soil 15101. Emerald green glasses from other soils are identical to those from 15101. The composition of the green glass is unlike that of any other major lunar glass group. The Fe content is comparable to that in mare basalts, but Ti is much lower. The Mg content is much higher than in most lunar materials analyzed to date, and the Cr content is also high. The low Al content is comparable to that of mare basalt glasses.

  18. Drugstore Reading Glasses

    NASA Astrophysics Data System (ADS)

    Erlichson, Herman

    2006-03-01

    The occasion for this paper was my reading of a paper in the February 2005 issue of TPT. As one gets older the near point of the eye begins to recede.2 This is called presbyopia.3 An alternative to purchasing glasses from an optometrist is to purchase an inexpensive pair of reading glasses in a pharmacy. The pharmacy has these glasses ordered by diopters corresponding to the strength of the lens needed for a particular presbyopic eye. The glasses are, of course, not available for myopic eyes.

  19. Fracture resistance of endodontically treated maxillary premolars restored by silorane-based composite with or without fiber or nano-ionomer

    PubMed Central

    Shafiei, Fereshteh; Ghahramani, Yasamin; Fattah, Zahra

    2014-01-01

    PURPOSE This in vitro study investigated the fracture resistance of endodontically treated premolars restored using silorane- or methacrylate-based composite along with or without fiber or nano-ionomer base. MATERIALS AND METHODS Ninety-six intact maxillary premolars were randomly divided into eight groups (n = 12). G1 (negative control) was the intact teeth. In Groups 2-8, root canal treatment with mesio-occlusodistal preparation was performed. G2 (positive control) was kept unrestored. The other groups were restored using composite resin as follows: G3, methacrylate-based composite (Z250); G4, methacrylate composite (Z250) with polyethylene fiber; G5 and G6, silorane-based composite (Filtek P90) without and with the fiber, respectively; G7 and G8, methacrylate- and silorane-based composite with nano-ionomer base, respectively. After aging period and thermocycling for 1000 cycles, fracture strength was tested and fracture patterns were inspected. The results were analyzed using ANOVA and Tukey HSD tests (?=0.05). RESULTS Mean fracture resistance for the eight groups (in Newton) were G1: 1200 ± 169a, G2: 360 ± 93b, G3: 632 ± 196c, G4: 692 ± 195c, G5: 917 ± 159d, G6: 1013 ± 125ad, G7: 959 ± 148d, G8: 947 ± 105d (different superscript letters revealed significant difference among groups). Most of the fractures in all the groups were restorable, except Group 3. CONCLUSION Silorane-based composite revealed significantly higher strength of the restored premolars compared to that of methacrylate one. Fiber insertion demonstrated no additional effect on the strength of both composite restorations; however, it increased the prevalence of restorable fracture of methacrylate-based composite restored teeth. Using nano-ionomer base under methacrylate-based composite had a positive effect on fracture resistance and pattern. Only fiber-reinforced silorane composite restoration resulted in a strength similar to that of the intact teeth. PMID:25006384

  20. Rare Earth Phosphate Glass and Glass-Ceramic Proton Conductors

    SciTech Connect

    De Jonghe, Lutgard C.; Ray, Hannah L.; Wang, Ruigang

    2008-12-03

    The structure and conductivity of cerium and lanthanum phosphate glasses and glass-ceramics were investigated. The effects of varying the metal to phosphate ratio in the glasses, doping LaP3O9 glasses with Ce, and recrystallization of CeP3O9 glasses, on the glasses' microstructure and total conductivity were investigated using XRD, SEM, and AC impedance techniques. Strong increases in conductivity occurred when the glasses were recrystallized: the conductivity of a cerium metaphosphate glass increased conductivity after recrystallization from 10-7.5 S/cm to 10-6 S/cm at 400oC.

  1. The effect of mechanical load cycling and polishing time on microleakage of class V glass-ionomer and composite restorations: A scanning electron microscopy evaluation

    PubMed Central

    Mirzaie, Mansoreh; Yasini, Esmail; Kermanshah, Hamid; Omidi, Baharan Ranjbar

    2014-01-01

    Background: Microleakage is one of the challenging concerns in direct filling restorations. Understanding of its related factors is important in clinical practice. The aim of this study was scanning electron microscopy (SEM) evaluation of marginal integrity in three types of tooth-colored restorative materials in class V cavity preparations and the effect of load cycling and polishing time on the microleakage. Materials and Methods: In this in vitro experimental study, class V cavity preparations were prepared on the buccal and lingual surfaces of 60 bovine incisors. The specimens were divided into three groups each containing 20 teeth: group 1: Filtek Z350, Group 2: Fuji IX/G Coat Plus, Group 3: Fuji II LC/GC varnish. In each group, 2 subgroups (n = 20) were established based on finishing time (immediate or delayed by 24 h). All specimens were thermocycled (×2,000, 5-50°C). In each sub groups, half of the teeth were load cycled. Epoxy resin replicas of 24 specimens were evaluated under field emission-SEM and interfacial gaps were measured. All teeth were then immersed in 0.5% basic fuchsin dye for 24 h, sectioned and observed under stereomicroscope. Data were analyzed with Kruskal-Wallis’ test and Mann-Whitney U test and a comparison between incisal and cervical microleakage was made with Wilcoxon test. P < 0.05 was considered as significant. Results: Load cycling and filling material had a significant effect on microleakage, but polishing time did not. Cervical microleakage in Z350/load cycle/immediate polish and Fuji IX/load cycle/immediate or delayed polish and Fuji IX/no load cycle/immediate polish were significantly higher than incisal microleakage. Conclusion: It was concluded that the cervical sealing ability of Fuji IX under load cycling was better than Fuji II LC. Under load cycling and immediate polishing Z350 showed better marginal integrity than both Fuji II LC and Fuji IX. The immediate polishing didn’t cause a statistically significant increase in microleakage of evaluated tooth-colored class V restorations. PMID:24688568

  2. Caries-preventive effect of glass ionomer and resin-based fissure sealants on permanent teeth: An update of systematic review evidence

    PubMed Central

    2011-01-01

    Background This article constitutes a partial update of the original systematic review evidence by Yengopal et al. from 15 January 2008 (published in the Journal of Oral Science in 2009) with primary focus on research quality in regard to bias risk in trials. Its aim is to update the existing systematic review evidence from the English literature as to whether caries occurrence on pits and fissures of teeth sealed with either GIC or resin is the same. Methods In addition to the 12 trials included during the original systematic review, 5 new trials were identified during the database search (up to 26 August 2010) and 2 further trials were included from a hand search and reference check. Of these, 3 trials were excluded and 16 were accepted for data extraction and quality assessment. The quality of accepted trials was assessed, using updated quality criteria, and the risk of bias was investigated in more depth than previously reported. In addition, the focus of quantitative synthesis was shifted to single datasets that were extracted from the accepted trials. Results Twenty-six dichotomous and 4 continuous datasets were extracted. Meta-analysis and cumulative meta-analysis were used in combining clinically homogenous datasets. The overall outcome of the computed datasets suggest no difference between the caries-preventive effects of GIC- and resin-based fissure sealants. Conclusions This overall outcome is in agreement with the conclusions of the original systematic review. Although the findings of the trials identified in this update may be considered to be less affected by attrition- and publication bias, their risk of selection- and detection-/performance bias is high. Thus, verification of the currently available results requires further high quality randomised control trials. PMID:21276215

  3. The modified Ottawa method to establish the update need of a systematic review: glass-ionomer versus resin sealants for caries prevention

    PubMed Central

    MICKENAUTSCH, Steffen; YENGOPAL, Veerasamy

    2013-01-01

    Objective To demonstrate the application of the modified Ottawa method by establishing the update need of a systematic review with focus on the caries preventive effect of GIC versus resin pit and fissure sealants; to answer the question as to whether the existing conclusions of this systematic review are still current; to establish whether a new update of this systematic review was needed. Methods: Application of the Modified Ottawa method. Application date: April/May 2012. Results Four signals aligned with the criteria of the modified Ottawa method were identified. The content of these signals suggest that higher precision of the current systematic review results might be achieved if an update of the current review were conducted at this point in time. However, these signals further indicate that such systematic review update, despite its higher precision, would only confirm the existing review conclusion that no statistically significant difference exists in the caries-preventive effect of GIC and resin-based fissure sealants. Conclusion In conclusion, this study demonstrated the modified Ottawa method as an effective tool in establishing the update need of the systematic review. In addition, it was established that the conclusions of the systematic review in relation to the caries preventive effect of GIC versus resin based fissure sealants are still current, and that no update of this systematic review was warranted at date of application. PMID:24212996

  4. Glasses containing lutetium fluoride

    Microsoft Academic Search

    Petr Melnikov; Gisele de Carvalho; Marcelo Nalin; Younes Messaddeq; Sydney J. Ribeiro

    1998-01-01

    Glasses containing lutetium fluoride have been prepare in the system BaF2 - SrF2 - ZnF2 - LuF3 - InF3. The composition of the phases crystallizing out of these glasses suggests octahedral pre-arrangement comprising (LuF6) and [Sr(Ba)F2] structural fragments.

  5. Indium fluoride glass fibers

    NASA Astrophysics Data System (ADS)

    Saad, Mohammed

    2012-03-01

    Fluoride glasses are the only material that transmit light from ultraviolet to mid-infrared and can be drawn into industrial optical fibers. The mechanical and optical properties of new indium fluoride glass fibers have been investigated. Multimode fiber 190 microns, has very high mechanical strength greater than 100 kpsi and optical loss as low as 45 dB/km between 2 and 4 microns. Unlike chalcogenide glass fibers, indium fluoride fiber has a wide transmission window from 0.3 to 5.5 microns without any absorption peak. Indium fluoride glass fibers are the technology of choice for all application requiring transmission up to 5 micron such as infrared contour measure (IRCM) and chemical sensing. Furthermore, Indium fluoride glasses have low phonon energy and can be heavily doped and co-doped whit rare-earth elements. Therefore they are very promising candidates for infrared fiber lasers.

  6. Glass leaching performance

    SciTech Connect

    Chick, L.A.; Turcotte, R.P.

    1983-05-01

    Current understanding of the leaching performance of high-level nuclear waste (HLW) glass is summarized. The empirical model of waste glass leaching behavior developed shows that at high water flow rates the glass leach rate is kinetically limited to a maximum value. At intermediate water flow rates, leaching is limited by the solution concentration of silica and decreases with decreasing water flow rates. Release of soluble elements is controlled by silica dissolution because silica forms the binding network of the glass. At low water flow rates, mass loss rates reach values controlled by formation rates of alteration minerals, or by diffusion of dissolution products through essentially stagnant water. The parameters reviewed with respect to their quantifiable influence on leaching behavior include temperature, pH, leachant composition, glass composition, thermal history, and radiation. Of these, temperature is most important since the rate of mass loss approximately doubles with each 10/sup 0/C increase in dilute solutions. The pH has small effects within the 4 to 10 range. The chemical composition of the leachant is most important with regard to its influence on alteration product formation. Glass composition exhibits the largest effects at high flow rates where improved glasses leach from ten to thirty times slower than glass 76 to 68. The effects of the thermal history (devitrification) of the glass are not likely to be significant. Radiation effects are important primarily in that radiolysis can potentially drive pH values to less than 4. Radiation damage to the glass causes insignificant changes in leaching performance.

  7. Sequential optimization of methotrexate encapsulation in micellar nano-networks of polyethyleneimine ionomer containing redox-sensitive cross-links.

    PubMed

    Abolmaali, Samira Sadat; Tamaddon, Ali; Yousefi, Gholamhossein; Javidnia, Katayoun; Dinarvand, Rasoul

    2014-01-01

    A functional polycation nanonetwork was developed for delivery of water soluble chemotherapeutic agents. The complexes of polyethyleneimine grafted methoxy polyethylene glycol (PEI-g-mPEG) and Zn(2+) were utilized as the micellar template for cross-linking with dithiodipropionic acid, followed by an acidic pH dialysis to remove the metal ion from the micellar template. The synthesis method was optimized according to pH, the molar ratio of Zn(2+), and the cross-link ratio. The atomic force microscopy showed soft, discrete, and uniform nano-networks. They were sensitive to the simulated reductive environment as determined by Ellman's assay. They showed few positive ? potential and an average hydrodynamic diameter of 162±10 nm, which decreased to 49±11 nm upon dehydration. The ionic character of the nano-networks allowed the achievement of a higher-loading capacity of methotrexate (MTX), approximately 57% weight per weight, depending on the cross-link and the drug feed ratios. The nano-networks actively loaded with MTX presented some suitable properties, such as the hydrodynamic size of 117±16 nm, polydispersity index of 0.22, and a prolonged swelling-controlled release profile over 24 hours that boosted following reductive activation of the nanonetwork biodegradation. Unlike the PEI ionomer, the nano-networks provided an acceptable cytotoxicity profile. The drug-loaded nano-networks exhibited more specific cytotoxicity against human hepatocellular carcinoma cells if compared to free MTX at concentrations above 1 ?M. The enhanced antitumor activity in vitro might be attributed to endocytic entry of MTX-loaded nano-networks that was found in the epifluorescence microscopy experiment for the fluorophore-labeled nano-networks. PMID:24944513

  8. Profiling the ionome of rice and its use in discriminating geographical origins at the regional scale, China.

    PubMed

    Li, Gang; Nunes, Luis; Wang, Yijie; Williams, Paul N; Zheng, Maozhong; Zhang, Qiufang; Zhu, Yongguan

    2013-01-01

    Element profile was investigated for their use to trace the geographical origin of rice (Oryza sativa L.) samples. The concentrations of 13 elements (calcium (Ca), potassium (K), magnesium (Mg), phosphorus (P), boron (B), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), arsenic (As), selenium (Se), molybdenum (Mo), and cadmium (Cd)) were determined in the rice samples by inductively coupled plasma optical emission and mass spectrometry. Most of the essential elements for human health in rice were within normal ranges except for Mo and Se. Mo concentrations were twice as high as those in rice from Vietnam and Spain. Meanwhile, Se concentrations were three times lower in the whole province compared to the Chinese average level of 0.088 mg/kg. About 12% of the rice samples failed the Chinese national food safety standard of 0.2 mg/kg for Cd. Combined with the multi-elemental profile in rice, the principal component analysis (PCA), discriminant function analysis (DFA) and Fibonacci index analysis (FIA) were applied to discriminate geographical origins of the samples. Results indicated that the FIA method could achieve a more effective geographical origin classification compared with PCA and DFA, due to its efficiency in making the grouping even when the elemental variability was so high that PCA and DFA showed little discriminatory power. Furthermore, some elements were identified as the most powerful indicators of geographical origin: Ca, Ni, Fe and Cd. This suggests that the newly established methodology of FIA based on the ionome profile can be applied to determine the geographical origin of rice. PMID:23586309

  9. Sequential optimization of methotrexate encapsulation in micellar nano-networks of polyethyleneimine ionomer containing redox-sensitive cross-links

    PubMed Central

    Abolmaali, Samira Sadat; Tamaddon, Ali; Yousefi, Gholamhossein; Javidnia, Katayoun; Dinarvand, Rasoul

    2014-01-01

    A functional polycation nanonetwork was developed for delivery of water soluble chemotherapeutic agents. The complexes of polyethyleneimine grafted methoxy polyethylene glycol (PEI-g-mPEG) and Zn2+ were utilized as the micellar template for cross-linking with dithiodipropionic acid, followed by an acidic pH dialysis to remove the metal ion from the micellar template. The synthesis method was optimized according to pH, the molar ratio of Zn2+, and the cross-link ratio. The atomic force microscopy showed soft, discrete, and uniform nano-networks. They were sensitive to the simulated reductive environment as determined by Ellman’s assay. They showed few positive ? potential and an average hydrodynamic diameter of 162±10 nm, which decreased to 49±11 nm upon dehydration. The ionic character of the nano-networks allowed the achievement of a higher-loading capacity of methotrexate (MTX), approximately 57% weight per weight, depending on the cross-link and the drug feed ratios. The nano-networks actively loaded with MTX presented some suitable properties, such as the hydrodynamic size of 117±16 nm, polydispersity index of 0.22, and a prolonged swelling-controlled release profile over 24 hours that boosted following reductive activation of the nanonetwork biodegradation. Unlike the PEI ionomer, the nano-networks provided an acceptable cytotoxicity profile. The drug-loaded nano-networks exhibited more specific cytotoxicity against human hepatocellular carcinoma cells if compared to free MTX at concentrations above 1 ?M. The enhanced antitumor activity in vitro might be attributed to endocytic entry of MTX-loaded nano-networks that was found in the epifluorescence microscopy experiment for the fluorophore-labeled nano-networks. PMID:24944513

  10. Nitrogen isotope analysis of ammonium in aqueous solutions using a perfluorosulfonated ionomer membrane for solid-phase microextraction.

    PubMed

    Norlin, Elin; Irgum, Knut; Ohlsson, K E Anders

    2003-01-01

    The use of custom-made solid-phase microextraction (SPME) fibers coated with a perfluorosulfonated ionomer, Nafion, was investigated for nitrogen isotopic analysis of ammonium in aqueous solutions. Aqueous ammonium was converted to ammonia by addition of a base, followed by absorption from the headspace, desorption in the injection port of a gas chromatograph, and analysis by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). Fibers coated with a Nafion tubing were chosen due to a higher fiber-gas distribution constant and a higher Nafion thickness than fibers coated with Nafion solution, both leading to a higher amount of ammonia absorbed at equilibrium. The Nafion membrane-coated fiber absorbed approximately 20 times more than a commercial polydimethylsiloxane (PDMS) fiber. The isotopic fractionation between fiber and gas was 1.0117 +/- 0.0009 (standard deviation, SD, of all measurements) at an initial ammonia gas concentration of 21-210 microM. At 390 microM initial gas concentration it was slightly lower. When sampling from liquid samples, an ammonium concentration of 10 mM was needed to obtain a sufficient amount of ammonia absorbed. Modeling of the absorption at different temperatures showed that the absorption was approximately constant in the temperature range suitable for SPME experiments. Absorption at room temperature was therefore used for simplicity. A pilot study was conducted in which absorption was achieved from a single 9 microL droplet of sample. The preliminary results showed that delta(15)N analysis was possible for only 0.4-0.5 micromol of ammonium with a SD of 0.8 per thousand (n = 5). PMID:12717766

  11. Evaluating chemical degradation of proton conducting perfluorosulfonic acid ionomers in a Fenton test by solid-state 19F NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Ghassemzadeh, L.; Kreuer, K. D.; Maier, J.; Müller, K.

    2011-03-01

    Chemical degradation and stability of perfluorosulfonic acid (PFSA) ionomers against radical attack were investigated by an (ex situ) Fenton test. Solid-state and solution NMR as well as ATR-FTIR studies were performed on the samples before and after the Fenton reaction. By changing the concentration of the Fenton's solution it is found that the metallic catalyst (Fe2+) is a critical factor which may affect the solid-state NMR results. After adjusting the experimental conditions, i.e., by reducing the Fe2+ concentration, it was possible to detect by solid-state 19F NMR spectroscopy the structural changes of the perfluorosulfonic acid ionomers during the ex situ Fenton test. A comparative study was made on the degradation of Nafion and Hyflon Ion membranes which differ in the length of the side chains. It is shown that the Hyflon Ion membrane with shorter side chains is more stable against side chain attack, most probably because of the absence of an additional tertiary carbon in the side chain. At the same time, there is evidence for enhanced main chain degradation in membranes with unprotected backbone chain ends.

  12. Polar glass ceramics

    Microsoft Academic Search

    A. Halliyal; A. S. Bhalla; R. E. Newnham; L. E. Cross

    1981-01-01

    Pyroelectric-piezoelecric glass ceramics of polar materials like Li2Si2O5, Ba2TiGe2O8, Ba2TiSi2O8, and Various compositions in the systems Li2O-B2O3, Li2O-SiO2-ZnO, Li2O-SiO2-B2O3 have been prepared by oriented recrystallization of the glasses under a strong temperature gradient, providing a simple inexpensive process for preparing piezoelectric and pyroelectric materials. High pyroelectric responses were observed in these glass-ceramics. Values of piezoelectric d33 coefficients, frequency constants, electromechanical

  13. Glass electrolyte composition

    DOEpatents

    Kucera, G.H.; Roche, M.F.

    1985-01-08

    An ionically conductive glass is disclosed for use as electrolyte in a high temperature electrochemical cell, particularly a cell with sodium anode and sulfur cathode. The glass includes the constituents Na/sub 2/O, ZrO/sub 2/, Al/sub 2/O/sub 3/ and SiO/sub 2/ in selected proportions to be a single phase solid solution substantially free of crystalline regions and undissolved constituents. Other advantageous properties are an ionic conductivity in excess of 2 x 10/sup -3/ (ohm-cm)/sup -1/ at 300/sup 0/C and a glass transition temperature in excess of 500/sup 0/C.

  14. Relaxations in spin glasses: similarities and differences from ordinary glasses

    SciTech Connect

    Ngai, K.L.; Rajagopal, A.K.; Huang, C.Y.

    1983-01-01

    Relaxation phenomena have become a major concern in the physics of spin glasses. There are certain resemblances of these relaxation properties to those of ordinary glasses. In this work, we compare the relaxation properties of spin glasses near the freezing temperature with those of glasses near the glass transition temperature. There are remarkable similarities between them and they both are in conformity with two coupled universality relations predicted by a recent model of relaxations in condensed matter.

  15. Baseline LAW Glass Formulation Testing

    SciTech Connect

    Kruger, Albert A. [USDOE Office of River Protection, Richland, WA (United States); Mooers, Cavin [The Catholic University of America, Washington, DC (United States). Vitreous State Lab.; Bazemore, Gina [The Catholic University of America, Washington, DC (United States). Vitreous State Lab; Pegg, Ian L. [The Catholic University of America, Washington, DC (United States). Vitreous State Lab; Hight, Kenneth [The Catholic University of America, Washington, DC (United States). Vitreous State Lab; Lai, Shan Tao [The Catholic University of America, Washington, DC (United States). Vitreous State Lab; Buechele, Andrew [The Catholic University of America, Washington, DC (United States). Vitreous State Lab; Rielley, Elizabeth [The Catholic University of America, Washington, DC (United States). Vitreous State Lab; Gan, Hao [The Catholic University of America, Washington, DC (United States). Vitreous State Lab; Muller, Isabelle S. [The Catholic University of America, Washington, DC (United States). Vitreous State Lab; Cecil, Richard [The Catholic University of America, Washington, DC (United States). Vitreous State Lab

    2013-06-13

    The major objective of the baseline glass formulation work was to develop and select glass formulations that are compliant with contractual and processing requirements for each of the LAW waste streams. Other objectives of the work included preparation and characterization of glasses with respect to the properties of interest, optimization of sulfate loading in the glasses, evaluation of ability to achieve waste loading limits, testing to demonstrate compatibility of glass melts with melter materials of construction, development of glass formulations to support ILAW qualification activities, and identification of glass formulation issues with respect to contract specifications and processing requirements.

  16. Whisker reinforced glass ceramic

    SciTech Connect

    Hirschfeld, D.A.; Brown, J.J. Jr.

    1996-06-03

    The process for making an in-situ whisker reinforced glass-ceramic that is up to 1.5 times as strong as conventional glass-ceramics was developed at Virginia Tech and patented in 1993. This technology has been identified as having commercial potential for use in high temperature heat exchanger applications for the electric power generation field by the National Center for Appropriate Technology (NCAT). This technology was licensed by MATVA, Inc., a small Virginia business, for further development. In particular, the goal of this project was to develop a property database and conduct initial testing of heat exchanger prototypes to demonstrate its potential application. This final report describes how the glass precursor was formed, physical properties of the glass-ceramic, techniques for making heat exchanger prototypes.

  17. Glasses and Contact Lenses

    MedlinePLUS

    ... together the way they should. But eyeglasses or contact lenses, also called corrective lenses, can help most ... trouble, it's often a refractive problem. Glasses or contact lenses work so well because they can correct ...

  18. Glass fiber insulation

    SciTech Connect

    Griffith, E.J.; Ngo, T.M.

    1993-06-29

    A composition for a glass fiber insulation is described comprising a loose mat of glass fibers having at least a portion of the surface coated with a water insoluble, non-hygroscopic, amorphous aluminum phosphate polymer having a molar ratio of Al[sub 2]O[sub 3] to P[sub 2]O[sub 5] of less than 1 and providing a substantial thermal resistance.

  19. Pyroelectric glass-ceramics

    Microsoft Academic Search

    G. J. Gardopee; R. E. Newnham; A. G. Halliyal; A. S. Bhalla

    1980-01-01

    Highly oriented surface layers of lithium disilicate crystals were grown by crystallizing glasses of composition Li2Si2O5 in a temperature gradient. The polar c axes of the crystallites were oriented parallel to the temperature gradient and perpendicular to the sample surface. The pyroelectric response of the glass-ceramic crystallized in a thermal gradient was approximately four times larger than that of a

  20. Ductile Bulk Metallic Glass

    Microsoft Academic Search

    Jan Schroers; William L. Johnson

    2004-01-01

    We report on experimental evidence of pronounced global plasticity measured in monolithic Pt57.5Cu14.7Ni5.3P22.5 bulk metallic glass under both bending and unconfined compression loading conditions. A plastic strain of 20% is measured, never before seen in metallic glasses. Also, permanent deformation and a strain exceeding 3% before failure is observed during bending of 4mm thick samples. To date, no monolithic metallic

  1. Metallic glass composition

    DOEpatents

    Kroeger, Donald M. (Knoxville, TN); Koch, Carl C. (Raleigh, NC)

    1986-01-01

    A metallic glass alloy that is either iron-based or nickel-based or based on a mixture of iron and nickel, containing lesser amounts of elements selected from the group boron, silicon carbon and phosphorous to which is added an amount of a ductility enhancing element selected from the group cerium, lanthanum, praseodymium and neodymium sufficient to increase ductility of the metallic glass upon annealing.

  2. 8.G Glasses

    NSDL National Science Digital Library

    2012-05-01

    This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: The diagram shows three glasses (not drawn to scale). The measurements are all in centimeters. The bowl of glass 1 is cylindrical. The inside diameter ...

  3. Volcanic Glasses: Construction Materials

    NASA Astrophysics Data System (ADS)

    Moskowitz, Samuel E.

    1998-01-01

    Natural glass is the product of rapidly cooled molten rock. Two natural sources of the melt are volcanic eruption and meteoritic impact. Pure glass is an amorphous aggregate. Volcanic glass is a material that could be utilized in the construction of extraterrestrial outposts. Pumice and perlite are volcanic glasses currently used in the building industry. Samples of natural volcanic glass found in the lunar regolith were returned to Earth as part of the Apollo and Luna programs. An alpha proton X-ray spectrometer onboard the Pathfinder recently examined martian rocks located in the vicinity of the lander craft. Preliminary results of chemical composition by weight of SiO2 50-55%, Al203 11-13%, K20 1-2%, Na20 2-5%, CaO 4-6%, MgO 3-7%, FeO 12-14%, S03 2-5%, and MnO <1% were given for two rocks. Parenthetically, the values for K and Mn were perhaps too high, and the analysis was based on X-ray data only. The appreciable amount of silica already found on Mars and empirical evidence to support the hypothesis that the planet once had water sufficient to rapidly cool magma imply the possibility of discovering natural glass of volcanic origin in subsequent missions.

  4. Porous silicon oxycarbide glasses

    SciTech Connect

    Singh, A.K.; Pantano, C.G. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering

    1996-10-01

    High-surface-area silicon oxycarbide gels and glasses were synthesized from mixtures of methyldimethoxysilane (MDMS) and tetraethoxysilane (TEOS) through acidic hydrolysis and condensation. A surface area of {approximately}275 m{sup 2}/g and an average pore size of {approximately}0 {angstrom} was obtained for a 50% MDMS-50% TEOS glass at 800 C under a flowing argon atmosphere. The average pore size was increased by aging the precursor gels in ammonium hydroxide. The increased average pore size and the higher strength of the mesoporous gel network enhanced the surface-area stability of the glasses: in this case, surface areas >200 m{sup 2}/g were retained at 1,200 C under an argon atmosphere. {sup 29}Si MAS NMR spectra revealed that an oxycarbide structure was established in the mesoporous glasses obtained after pyrolysis of the aged gels. The role of carbon was demonstrated by comparing the surface-area stability of the oxycarbide glasses with that of pure silica and that of oxycarbide glasses where all the carbon groups were removed through low-temperature plasma-oxidation treatments. In the absence of carbon, the thermal stability of the surface area decreased dramatically.

  5. Glass microsphere lubrication

    NASA Technical Reports Server (NTRS)

    Geiger, Michelle; Goode, Henry; Ohanlon, Sean; Pieloch, Stuart; Sorrells, Cindy; Willette, Chris

    1991-01-01

    The harsh lunar environment eliminated the consideration of most lubricants used on earth. Considering that the majority of the surface of the moon consists of sand, the elements that make up this mixture were analyzed. According to previous space missions, a large portion of the moon's surface is made up of fine grained crystalline rock, about 0.02 to 0.05 mm in size. These fine grained particles can be divided into four groups: lunar rock fragments, glasses, agglutinates (rock particles, crystals, or glasses), and fragments of meteorite material (rare). Analysis of the soil obtained from the missions has given chemical compositions of its materials. It is about 53 to 63 percent oxygen, 16 to 22 percent silicon, 10 to 16 percent sulfur, 5 to 9 percent aluminum, and has lesser amounts of magnesium, carbon, and sodium. To be self-supporting, the lubricant must utilize one or more of the above elements. Considering that the element must be easy to extract and readily manipulated, silicon or glass was the most logical choice. Being a ceramic, glass has a high strength and excellent resistance to temperature. The glass would also not contaminate the environment as it comes directly from it. If sand entered a bearing lubricated with grease, the lubricant would eventually fail and the shaft would bind, causing damage to the system. In a bearing lubricated with a solid glass lubricant, sand would be ground up and have little effect on the system. The next issue was what shape to form the glass in. Solid glass spheres was the only logical choice. The strength of the glass and its endurance would be optimal in this form. To behave as an effective lubricant, the diameter of the spheres would have to be very small, on the order of hundreds of microns or less. This would allow smaller clearances between the bearing and the shaft, and less material would be needed. The production of glass microspheres was divided into two parts, production and sorting. Production includes the manufacturing of the microspheres, while sorting entails deciphering the good microspheres from the bad ones. Each process is discussed in detail.

  6. Electrical properties of phosphate glasses

    NASA Astrophysics Data System (ADS)

    Mogus-Milankovic, A.; Santic, A.; Reis, S. T.; Day, D. E.

    2009-07-01

    Investigation of the electrical properties of phosphate glasses where transition metal oxide such as iron oxide is the network former and network modifier is presented. Phosphate glasses containing iron are electronically conducting glasses where the polaronic conduction is due to the electron hopping from low to high iron valence state. The identification of structural defects caused by ion/polaron migration, the analysis of dipolar states and electrical conductivity in iron phosphate glasses containing various alkali and mixed alkali ions was performed on the basis of the impedance spectroscopy (IS). The changes in electrical conductivity from as-quenched phosphate glass to fully crystallized glass (glass-ceramics) by IS are analyzed. A change in the characteristic features of IS follows the changes in glass and crystallized glass network. Using IS, the contribution of glass matrix, crystallized grains and grain boundary to the total electrical conductivity for iron phosphate glasses was analyzed. It was shown that decrease in conductivity is caused by discontinuities in the conduction pathways as a result of the disruption of crystalline network where two or more crystalline phases are formed. Also, phosphate-based glasses offer a unique range of biomaterials, as they form direct chemical bonding with hard/soft tissue. The surface charges of bioactive glasses are recognized to be the most important factors in determining biological responses. The improved bioactivity of the bioactive glasses as a result of the effects of the surface charges generated by electrical polarization is discussed.

  7. Sol-Gel Glasses

    NASA Technical Reports Server (NTRS)

    Mukherjee, S. P.

    1985-01-01

    Multicomponent homogeneous, ultrapure noncrystalline gels/gel derived glasses are promising batch materials for the containerless glass melting experiments in microgravity. Hence, ultrapure, homogeneous gel precursors could be used to: (1) investigate the effect of the container induced nucleation on the glass forming ability of marginally glass forming compositions; and (2) investigate the influence of gravity on the phase separation and coarsening behavior of gel derived glasses in the liquid-liquid immiscibility zone of the nonsilicate systems having a high density phase. The structure and crystallization behavior of gels in the SiO2-GeO2 as a function of gel chemistry and thermal treatment were investigated. As are the chemical principles involved in the distribution of a second network former in silica gel matrix being investigated. The procedures for synthesizing noncrystalline gels/gel-monoliths in the SiO2-GeO2, GeO2-PbO systems were developed. Preliminary investigations on the levitation and thermal treatment of germania silicate gel-monoliths in the Pressure Facility Acoustic Levitator were done.

  8. Jet penetration in glass

    SciTech Connect

    Moran, B.; Glenn, L.A.; Kusubov, A.

    1991-05-01

    We describe a phenomenological model which accounts for the mechanical response of glass to intense impulsive loading. An important aspect of this response is the dilatancy accompanying fracture. We have also conducted a number of experiments with 38.1-mm diameter precision shaped charges to establish the performance against various targets and to allow evaluation of our model. At 3 charge diameters standoff, the data indicate that both virgin and damaged glass offer better (Bernoulli-scaled) resistance to penetration than either of 4340 steel, or 6061-T6 aluminum alloy. Time-resolved measurements indicate two distinct phases of jet penetration in glass: An initial hydrodynamic phase, and a second phase characterized by a slower penetration velocity. Our calculations show that at early time, a crater is formed around the jet and only the tip of the undisturbed jet interacts with the glass. At late time the glass has collapsed on the jet and degraded penetration continues via a disturbed and fragmented jet.

  9. LEAD-CADMIUM OXYFLUORIDE GLASSES AND GLASS-CERAMICS

    Microsoft Academic Search

    M. A. P. Silva; V. Briois; M. Poulain; Y. Messaddeq; S. J. L. Ribeiro

    Glasses and glass-ceramics have been obtained in oxyfluoride systems involving lead and cadmium fluorides and one of the well-known glass former oxides SiO2, B2O3 and TeO2. Vitreous domains were established and a wide range of compositions including high heavy metal contents lead to stable glasses. Amorphous structures have been studied by short-range order spectroscopy techniques (Raman scattering and x-ray absorption)

  10. Connecting supramolecular bond lifetime and network mobility for scratch healing in poly(butyl acrylate) ionomers containing sodium, zinc and cobalt.

    PubMed

    Bose, Ranjita K; Hohlbein, Nico; Garcia, Santiago J; Schmidt, Annette M; van der Zwaag, Sybrand

    2015-01-21

    In this work, we correlate network dynamics, supramolecular reversibility and the macroscopic surface scratch healing behavior for a series of elastomeric ionomers based on an amorphous backbone with varying fractions of carboxylate pendant groups completely neutralized by Na(+), Zn(2+) or Co(2+) as the counter ions. Our results based on temperature dependent dynamic rheology with simultaneous FTIR analysis clearly indicate that the effective supramolecular bond lifetime (?(b)) is an important parameter to ascertain the ideal range of viscoelasticity for good macroscopic healing. The reversible coordination increased with higher valence metal ions and ionic content. Both rheological and spectroscopic analyses show a decrease in supramolecular assembly with temperature. The temperature dependent ?(b) was used to calculate the activation energy (Ea) of dissociation for the ionic clusters. According to self-healing experiments based on macroscale surface scratching, a supramolecular bond lifetime between 10 and 100 s results in samples with complete surface scratch healing and good mechanical robustness. PMID:25463031

  11. Transient nucleation in glasses

    NASA Technical Reports Server (NTRS)

    Kelton, K. F.

    1991-01-01

    Nucleation rates in condensed systems are frequently not at their steady state values. Such time dependent (or transient) nucleation is most clearly observed in devitrification studies of metallic and silicate glasses. The origin of transient nucleation and its role in the formation and stability of desired phases and microstructures are discussed. Numerical models of nucleation in isothermal and nonisothermal situations, based on the coupled differential equations describing cluster evolution within the classical theory, are presented. The importance of transient nucleation in glass formation and crystallization is discussed.

  12. Pyroelectric glass-ceramics

    NASA Astrophysics Data System (ADS)

    Gardopee, G. J.; Newnham, R. E.; Halliyal, A. G.; Bhalla, A. S.

    1980-05-01

    Highly oriented surface layers of lithium disilicate crystals were grown by crystallizing glasses of composition Li2Si2O5 in a temperature gradient. The polar c axes of the crystallites were oriented parallel to the temperature gradient and perpendicular to the sample surface. The pyroelectric response of the glass-ceramic crystallized in a thermal gradient was approximately four times larger than that of a touramaline crystal of similar dimensions. The time dependence of the pyroelectric signal obeys the thin-film equivalent circuit model developed by Chynoweth.

  13. Containerless processing of fluoride glass

    NASA Technical Reports Server (NTRS)

    Doremus, Robert H.

    1990-01-01

    Ground-based experiments on glass formation, crystallization, surface tension, vaporization, and chemical durability of a zirconium-barium-lanthanum (ZBL) fluoride glass are summarized. In a container large, columnar grains grew out from the container-glass interface during cooling. The main crystalline phase was alpha BaZrF6. A ZBL glass sphere was levitated acoustically during Shuttle flight STS-11. The glass was melted and then cooled while being levitated (containerless). Crystallization in the recovered sample was very fine and mainly beta BaZr2F10, showing the influence of the container on the nucleation and microstructure of crystallization in the glass. Glass formation should be easier for a containerless glass than in a container.

  14. Glass and ceramics. [lunar resources

    NASA Technical Reports Server (NTRS)

    Haskin, Larry A.

    1992-01-01

    A variety of glasses and ceramics can be produced from bulk lunar materials or from separated components. Glassy products include sintered regolith, quenched molten basalt, and transparent glass formed from fused plagioclase. No research has been carried out on lunar material or close simulants, so properties are not known in detail; however, common glass technologies such as molding and spinning seem feasible. Possible methods for producing glass and ceramic materials are discussed along with some potential uses of the resulting products.

  15. Spectroscopic studies of glass structure

    SciTech Connect

    Brow, R.K.

    1994-08-01

    Today`s understanding of the molecular-level structure of inorganic glasses has been transformed by the availability of a wide range of sensitive spectroscopic probes. Today we can relate glass composition to quantitative distributions of glass-forming cations and to changes in oxygen bonding and modifying cation geometries. Future spectroscopic studies will result in improved descriptions of anion and cation geometries and should provide glass scientists with the capability to optimize atomic arrangements for specific optical, electrical, and thermal properties.

  16. LOW-E GLASS TEMPERING

    Microsoft Academic Search

    Jorma Vitkala

    It is problematic to heat up Low-E glass in a traditional radiation type furnace, because the glass will bend during the heating cycle which leads to different problems such as viscoelastic changes, coating distortion, surface defects, uneven bending etc. If we add forced convection to radiation furnaces it becomes possible to temper Low-E glass with the current manufacturing methods on

  17. Glass for Solid State Devices

    NASA Technical Reports Server (NTRS)

    Bailey, R. F.

    1982-01-01

    Glass film has low intrinsic compressive stress for isolating active layers of magnetic-bubble and other solid-state devices. Solid-state device structure incorporates low-stress glasses as barrier and spacer layers. Glass layers mechanically isolate substrate, conductor, and nickel/iron layers.

  18. Barstow heliostat mirror glass characterization

    SciTech Connect

    Lind, M.A.; Buckwalter, C.Q.

    1980-09-01

    The technical analysis performed on the special run of low iron float glass procured from the Ford Glass Division for the ten megawatt solar thermal/electric pilot power plant to be constructed at Barstow, California is discussed. The topics that are addressed include the optical properties and the relative durability of the glass. Two optical parameters, solar transmittance and optical flatness, were measured as referenced in the specification and found to be better than the stated tolerances. The average solar transmittance exceeded 0.890 transmittance units. The glass also exhibited optical angular flatness deviations less than +-1.0 mrad as required. Both qualitative and quantitative accelerated weathering tests were performed on the glass in order to compare its durability to other soda lime float glass and alternate composition glasses of interest to the solar community. In both the quantitative leaching experiments and the more qualitative room temperature and elevated temperature water vapor exposure experiments the heliostat glass exhibited the same characteristics as the other soda-lime silicate float glasses. As a final test for mirroring compatability, selected samples of the production run of the glass were sent to four different commercial manufacturers for mirror coating. None of the manufacturers reported any difficulty silvering the glass. Based on the tests performed, the glass meets or exceeds all optical specifications for the Barstow heliostat field.

  19. Glass Ceramics as Composite Fillers

    Microsoft Academic Search

    G. Müller

    1974-01-01

    Glass ceramics are known that are transparent and colorless and have very low thermal expansions. Experiments are described to modify such glass ceramics by introduction of oxides of high atomic weight. Glass ceramics containing relatively large amounts of La 2O3 are promising as X-ray opaque filler materials with nearly zero thermal expansion.

  20. Yesterday's Trash Makes Tomorrow's "Glass"

    ERIC Educational Resources Information Center

    Wayne, Dale

    2010-01-01

    In this article, the author describes a glass art project inspired by Dale Chihuly. This project uses two-liter plastic soda bottles which are cut apart and trimmed. Applying heat using a hair dryer, the plastic curls and takes an uneven blown-glass quality. The "glass" is then painted using acrylic paint. (Contains 2 resources and 1 online…

  1. Electrostatic rotation of glass disc

    Microsoft Academic Search

    Roland Moser; Toshiro Higuchi

    2002-01-01

    This paper reports the successful electrostatic rotation of a glass disc of 65mm diameter. The realized electrostatic glass disc drive features high compactness and simplicity. The goal of the presented experimental work is to verify that the concept of the electrostatic glass motor can be applied to data storage devices, especially for disc drives with diameters <1in. The basic principle

  2. What Glass Ceiling?

    ERIC Educational Resources Information Center

    Lynch, Michael; Post, Katherine

    1996-01-01

    A recent study drawing on data from the Census Bureau and the Bureau of Labor Statistics suggests that the wage gap between men and women has virtually disappeared, and that the so-called "glass ceiling" results more from age and qualifications than from explicit discrimination. (SLD)

  3. Triad ''Metal – Enamel – Glass''

    NASA Astrophysics Data System (ADS)

    Mukhina, T.; Petrova, S.; Toporova, V.; Fedyaeva, T.

    2014-10-01

    This article shows how to change the color of metal and glass. Both these materials are self–sufficient, but sometimes used together. For example, enameling. In this case, the adhesion between metal substrate and stekloobraznae enamel layer, which was conducted on a stretching and a bend, was tested.

  4. Silicon and Glass Micromachining

    Microsoft Academic Search

    Edwin T. Carlen; Johan Bomer; Nieuwkasteele van Jan; Berg van den Albert; K. E. Herold; A. Rasooly

    2009-01-01

    The past two decades have seen rapid advancement of Lab on a Chip (LOC) systems with applications ranging from gas chromatography to capillary electrophoresis, and more recently to high-pressure chemistry and single cell analysis. For many applications in clinical medicine, biology and chemistry, silicon and glass may still be the preferred materials. The mechanical rigidity, chemical resistance, and low permeability

  5. "Stained Glass" Landscape Windows

    ERIC Educational Resources Information Center

    Vannata, Janine

    2008-01-01

    Both adults and children alike marvel at the grand vivid stained-glass windows created by American artist Louis Comfort Tiffany. Today he is commonly recognized as one of America's most influential designers and artists throughout the last nineteenth and early twentieth century. In the lesson described in this article, students created their own…

  6. Microexplosions in Tellurite Glasses

    SciTech Connect

    Sundaram, S. K.; Schaffer, C. B.; Mazur, E.

    2003-03-01

    Femtosecond laser pulses were used to initiate microexplosions in baseline, Al2O3-doped, and La2O3-doped sodium tellurite glasses. Single or multiple-shots were used in the experiments. Writing of simple structures (periodic array of voxels as well as lines) was demonstrated. The regions of microexplosion and writing were characterized using scanning electron microscopy (SEM, energy dispersive spectrometer (EDS), and atomic force microscopy (AFM) postmortem. Fingerprints of microexplosions, concentric lines within the region and a concentric ring outside the region due to shock wave generated during the microexplosions were evident. In the case of the baseline glass, no chemistry change was observed within the region of microexplosion. But, Al2O3-doped and La2O3-doped glasses showed depletion of the dopant from the edge to the center of the region of microexplosions, indicating chemistry gradient within the regions. Interrogation of the bulk and laser-treated regions using micro-Raman spectroscopy revealed no structural change due the microexplosions and writing within these glasses. These data were attributed to the localization of the effect to small regions due to tightly focused laser pulses used in the experiments.

  7. Volcanic glass as a natural analog for borosilicate waste glass

    SciTech Connect

    Morgenstein, M.E.; Shettel, D.L. [Geosciences Management Institute, Inc., Boulder City, NV (United States)

    1994-12-31

    Obsidian and basaltic glass are opposite end-members of natural volcanic glass compositions. Syngenetic and diagenetic tensile failure in basaltic glass (low silica glass) is pervasive and provides abundant alteration fronts deep into the glass structure. Perlitic fracturing in obsidian (high silica glass) limits the alteration zones to an {open_quotes}onion skin{close_quotes} geometry. Borosilicate waste glass behaves similarly to the natural analog of basaltic glass (sideromelane). During geologic time, established and tensile fracture networks form glass cells (a three-dimensional reticulated pattern) where the production of new fracture surfaces increases through time by geometric progression. This suggests that borosilicate glass monoliths will eventually become rubble. Rates of reaction appear to double for every 12C{degrees} of temperature increase. Published leach rates suggest that the entire inventory of certain radionuclides may be released during the 10,000 year regulatory time period. Steam alteration prior to liquid attack combined with pervasive deep tensile failure behavior may suggest that the glass waste form is not license defensible without a metallic- and/or ceramic-type composite barrier as an overpack.

  8. Water's second glass transition.

    PubMed

    Amann-Winkel, Katrin; Gainaru, Catalin; Handle, Philip H; Seidl, Markus; Nelson, Helge; Böhmer, Roland; Loerting, Thomas

    2013-10-29

    The glassy states of water are of common interest as the majority of H2O in space is in the glassy state and especially because a proper description of this phenomenon is considered to be the key to our understanding why liquid water shows exceptional properties, different from all other liquids. The occurrence of water's calorimetric glass transition of low-density amorphous ice at 136 K has been discussed controversially for many years because its calorimetric signature is very feeble. Here, we report that high-density amorphous ice at ambient pressure shows a distinct calorimetric glass transitions at 116 K and present evidence that this second glass transition involves liquid-like translational mobility of water molecules. This "double Tg scenario" is related to the coexistence of two liquid phases. The calorimetric signature of the second glass transition is much less feeble, with a heat capacity increase at Tg,2 about five times as large as at Tg,1. By using broadband-dielectric spectroscopy we resolve loss peaks yielding relaxation times near 100 s at 126 K for low-density amorphous ice and at 110 K for high-density amorphous ice as signatures of these two distinct glass transitions. Temperature-dependent dielectric data and heating-rate-dependent calorimetric data allow us to construct the relaxation map for the two distinct phases of water and to extract fragility indices m = 14 for the low-density and m = 20-25 for the high-density liquid. Thus, low-density liquid is classified as the strongest of all liquids known ("superstrong"), and also high-density liquid is classified as a strong liquid. PMID:24101518

  9. Production of glass or glass-ceramic to metal seals with the application of pressure

    DOEpatents

    Kelly, M.D.; Kramer, D.P.

    1985-01-04

    In a process for preparing a glass or glass-ceramic to metal seal comprising contacting the glass with the metal and heat-treating the glass and metal under conditions whereby the glass to metal seal is effected and, optionally, the glass is converted to a glass-ceramic, an improvement comprises carrying out the heat-treating step using hot isostatic pressing.

  10. Production of glass or glass-ceramic to metal seals with the application of pressure

    DOEpatents

    Kelly, Michael D. (West Alexandria, OH); Kramer, Daniel P. (Dayton, OH)

    1987-11-10

    In a process for preparing a glass or glass-ceramic to metal seal comprising contacting the glass with the metal and heat-treating the glass and metal under conditions whereby the glass to metal seal is effected and, optionally, the glass is converted to a glass-ceramic, an improvement comprises carrying out the heat-treating step using hot isostatic pressing.

  11. Nanostructure of glasses: experimental evidence

    NASA Astrophysics Data System (ADS)

    Maksimov, Leonid V.; Anan'ev, Anatolii V.; Bogdanov, Victor N.; Lipovskii, Andrey A.; Tagantsev, Dmitri K.; Yanush, Oleg V.

    2008-09-01

    Inorganic glass is material having nanoscaled physical and chemical inhomogeneities ad initio because glass inherits thermodynamic fluctuations of concentration, density and anisotropy of a glass forming melt. Combining light scattering and high temperature acoustics data allows to use the effect of internal immersion for designing multicomponent glasses with Rayleigh scattering losses lower than those of the silica glass. Non-random spatial distribution of dopants including rare-earth (RE) ions in a glass host (doped ion segregation) causes excessive Rayleigh scattering losses and enhancement of RE ion-ion interaction. Therefore, it opens the way to optimize operation parameters of laser and up-converting glasses by the proper choice of glass host composition. Results of Raman scattering spectra processing and characterization of electrooptical (EO) sensitivity of niobate glasses showed the existence of groups with stoichiometry of the well-known EO crystals and crystal-like orderliness (crystal motifs) in the glasses as the necessary condition of high EO sensitivity. It was found that EO sensitivity of glasses could be essentially increased by thermal treatment.

  12. Profiles in garbage glass containers

    SciTech Connect

    Miller, C. [Environmental Industry Associations, Washington, DC (United States)

    1997-09-01

    Glass containers are made from sand, limestone, soda ash, cullet (crushed bottles), and various additives, including those used to color brown, green, or blue bottles. Sixty percent of the glass used in the US is clear (flint) and one-fourth is brown (amber). Almost half of the green bottles are imported wind and beer bottles. Other glass products include flat glass such as windows; fiberglass insulation; and glassware. These products use different manufacturing processes and different additives than container glass. This profile covers only container glass. Glass bottles are commonly collected in curb-side programs. Losses due to breakage and the abrasiveness of glass during collection and processing offset their low collection and processing costs. Breakage solutions include installation of interior baffles or nets in the collection trucks, special glass-only truck compartments, and limiting the number of times glass is transferred after collection before final processing. Ten states require deposits on glass bottles for beer and soft drinks and related items.

  13. Clipped Random Wave Morphologies and the Analysis of the SAXS of an Ionomer Formed by Copolymerization of Tetrafluoroethylene and CF[subscript 2]=CFO(CF[subscript 2])[subscript 4]SO[subscript 3]H

    SciTech Connect

    Aieta, Niccolo V.; Stanis, Ronald J.; Horan, James L.; Yandrasits, Michael A.; Cookson, David J.; Ingham, Bridget; Toney, Michael F.; Hamrock, Steven J.; Herring, Andrew M.; (Ind. Research); (CSM); (Aust. Synch.); (SSRL); (3M Center)

    2009-09-15

    Using SAXS data, the microstructure of the ionomer formed by copolymerization of tetrafluoroethylene and CF{sub 2}=CFO(CF{sub 2}){sub 4}SO{sub 3}H films has been approached by two methods: a numerical method (the unified fit approach) utilizing a simple model of spherical scattering objects to determine the radius of gyration of different scattering features of the ionomer films and by a graphical method, the clipped random wave approach (CRW), using the scattering data and a porosity parameter to generate a random wave which is clipped to produce a real-space image of the microstructure. We studied films with EW of 733, 825, 900, and 1082 in both the as-cast and annealed 'dry' and boiled 'wet' states. The results of the two data analysis techniques are in good size agreement with each other. In addition, the CRW model show striking similarities to the structure proposed in a recent dissipative particle dynamic models. This has been the first time to our knowledge that the CRW technique has been applied to a PFSA type ionomer.

  14. Development of bioabsorbable glass fibres.

    PubMed

    Lin, S T; Krebs, S L; Kadiyala, S; Leong, K W; LaCourse, W C; Kumar, B

    1994-10-01

    Calcium-iron phosphate glasses with an iron oxide content ranging from 5 wt.% to 22 wt.% were prepared to investigate the effect of iron oxide on the properties of the glass. It was found that the dissolution rate, the fibre strength and the glass transition temperature were strongly affected by iron oxide. The glass dissolution rate exhibited a 50-fold reduction while the fibre strength doubled when the iron oxide content was increased from 5 wt.% to 22 wt.%. The phosphate glass containing 22 wt.% of iron oxide had a dissolution rate of about 5 micrograms/(cm2 day). The fibres drawn from this glass also exhibited the highest tensile strength over 1000 MPa. A cortical bone plug method was used to assess the biocompatibility of the glasses with the hard and soft tissues. The tissues surrounding the samples showed no inflammation at 9 wk. PMID:7888576

  15. Fluoride glass: Crystallization, surface tension

    NASA Technical Reports Server (NTRS)

    Doremus, R. H.

    1988-01-01

    Fluoride glass was levitated acoustically in the ACES apparatus on STS-11, and the recovered sample had a different microstructure from samples cooled in a container. Further experiments on levitated samples of fluoride glass are proposed. These include nucleation, crystallization, melting observations, measurement of surface tension of molten glass, and observation of bubbles in the glass. Ground experiments are required on sample preparation, outgassing, and surface reactions. The results should help in the development and evaluation of containerless processing, especially of glass, in the development of a contaminent-free method of measuring surface tensions of melts, in extending knowledge of gas and bubble behavior in fluoride glasses, and in increasing insight into the processing and properties of fluoride glasses.

  16. Glass matrix armor

    SciTech Connect

    Calkins, N.C.

    1991-09-03

    This patent describes an armor system which utilizes glass. A plurality of constraint cells are mounted on a surface of a substrate, which is metal armor plate or a similar tough material, such that the cells almost completely cover the surface of the substrate. Each constraint cell has a projectile receiving wall parallel to the substrate surface and has sides which are perpendicular to and surround the perimeter of the receiving wall. The cells are mounted such that, in one embodiment, the substrate surface serves as a sixth side or closure for each cell. Each cell has inside of it a plate, termed the front plate, which is parallel to and in contact with substantially all of the insides surface of the receiving wall. The balance of each cell is completely filled with a projectile-abrading material consisting of glass and a ceramic material and, in certain embodiments, a polymeric material.

  17. Laser Glass Frit Sealing for Encapsulation of Vacuum Insulation Glasses

    NASA Astrophysics Data System (ADS)

    Kind, H.; Gehlen, E.; Aden, M.; Olowinsky, A.; Gillner, A.

    Laser glass frit sealing is a joining method predestined in electronics for the sealing of engineered materials housings in dimensions of some 1 mm2 to several 10 mm2. The application field ranges from encapsulation of display panels to sensor housings. Laser glass frit sealing enables a hermetical closure excluding humidity and gas penetration. But the seam quality is also interesting for other applications requiring a hermetical sealing. One application is the encapsulation of vacuum insulation glass. The gap between two panes must be evacuated for reducing the thermal conductivity. Only an efficient encapsulating technique ensures durable tight joints of two panes for years. Laser glass frit sealing is an alternative joining method even though the material properties of soda lime glass like sensitivity to thermal stresses are much higher as known from engineered materials. An adapted thermal management of the process is necessary to prevent the thermal stresses within the pane to achieve crack free and tight glass frit seams.

  18. Cluster-assembled metallic glasses

    PubMed Central

    2013-01-01

    A bottom-up approach to nanofabricate metallic glasses from metal clusters as building blocks is presented. Considering metallic glasses as a subclass of cluster-assembled materials, the relation between the two lively fields of metal clusters and metallic glasses is pointed out. Deposition of selected clusters or collections of them, generated by state-of-the-art cluster beam sources, could lead to the production of a well-defined amorphous material. In contrast to rapidly quenched glasses where only the composition of the glass can be controlled, in cluster-assembled glasses, one can precisely control the structural building blocks. Comparing properties of glasses with similar compositions but differing in building blocks and therefore different in structure will facilitate the study of structure–property correlation in metallic glasses. This bottom-up method provides a novel alternative path to the synthesis of glassy alloys and will contribute to improving fundamental understanding in the field of metallic glasses. It may even permit the production of glassy materials for alloys that cannot be quenched rapidly enough to circumvent crystallization. Additionally, gaining deeper insight into the parameters governing the structure–property relation in metallic glasses can have a great impact on understanding and design of other cluster-assembled materials. PMID:23899019

  19. Bioactive glass in tissue engineering

    PubMed Central

    Rahaman, Mohamed N.; Day, Delbert E.; Bal, B. Sonny; Fu, Qiang; Jung, Steven B.; Bonewald, Lynda F.; Tomsia, Antoni P.

    2011-01-01

    This review focuses on recent advances in the development and use of bioactive glass for tissue engineering applications. Despite its inherent brittleness, bioactive glass has several appealing characteristics as a scaffold material for bone tissue engineering. New bioactive glasses based on borate and borosilicate compositions have shown the ability to enhance new bone formation when compared to silicate bioactive glass. Borate-based bioactive glasses also have controllable degradation rates, so the degradation of the bioactive glass implant can be more closely matched to the rate of new bone formation. Bioactive glasses can be doped with trace quantities of elements such as Cu, Zn and Sr, which are known to be beneficial for healthy bone growth. In addition to the new bioactive glasses, recent advances in biomaterials processing have resulted in the creation of scaffold architectures with a range of mechanical properties suitable for the substitution of loaded as well as non-loaded bone. While bioactive glass has been extensively investigated for bone repair, there has been relatively little research on the application of bioactive glass to the repair of soft tissues. However, recent work has shown the ability of bioactive glass to promote angiogenesis, which is critical to numerous applications in tissue regeneration, such as neovascularization for bone regeneration and the healing of soft tissue wounds. Bioactive glass has also been shown to enhance neocartilage formation during in vitro culture of chondrocyte-seeded hydrogels, and to serve as a subchondral substrate for tissue-engineered osteochondral constructs. Methods used to manipulate the structure and performance of bioactive glass in these tissue engineering applications are analyzed. PMID:21421084

  20. Fracture mechanics of cellular glass

    NASA Technical Reports Server (NTRS)

    Zwissler, J. G.; Adams, M. A.

    1981-01-01

    The fracture mechanics of cellular glasses (for the structural substrate of mirrored glass for solr concentrator reflecting panels) are discussed. Commercial and developmental cellular glasses were tested and analyzed using standard testing techniques and models developed from linear fracture mechanics. Two models describing the fracture behavior of these materials were developed. Slow crack growth behavior in cellular glass was found to be more complex than that encountered in dense glasses or ceramics. The crack velocity was found to be strongly dependent upon water vapor transport to the tip of the moving crack. The existence of a static fatigue limit was not conclusively established, however, it is speculated that slow crack growth behavior in Region 1 may be slower, by orders of magnitude, than that found in dense glasses.

  1. Waste product profile: Glass containers

    SciTech Connect

    Miller, C. [Environmental Industry Associations, Washington, DC (United States)

    1995-09-01

    In 1992, Waste Age initiated the Waste Product Profile series -- brief, factual listings of the solid waste management characteristics of materials in the solid waste stream. This popular series of profiles high-lighted a product, explained how it fit into integrated waste management systems, and provided current data on recycling and markets for the product. Glass containers are made from sand, limestone, soda ash, cullet (crushed bottles), and various additives, including those used to produce green, brown, and blue glass. Other glass products include flat glass, such as windows, and fiberglass products, such as insulation and glassware. These products are manufactured using different processes and different additives than container glass. This profile covers only glass containers.

  2. Performance rating of glass windows and glass windows with films in aspect of thermal comfort and heat transmission

    Microsoft Academic Search

    Somsak Chaiyapinunt; Bunyarit Phueakphongsuriya; Khemmachart Mongkornsaksit; Nopparat Khomporn

    2005-01-01

    This article is about a study on glass window and glass window with film of different types in aspect of thermal comfort and heat transmission. Different types of glass window, clear glass, tinted glass, reflective glass, double pane glass, and low-e glass were investigated. Films with different spectral optical properties were then adhered to the glass windows of different types

  3. Space processing of chalcogenide glass

    NASA Technical Reports Server (NTRS)

    Larsen, D. C.; Ali, M. I.

    1977-01-01

    The manner in which the weightless, containerless nature of in-space processing can be successfully utilized to improve the quality of infrared transmitting chalcogenide glasses is determined. The technique of space processing chalcogenide glass was developed, and the process and equipment necessary to do so was defined. Earthbound processing experiments with As2S3 and G28Sb12Se60 glasses were experimented with. Incorporated into these experiments is the use of an acoustic levitation device.

  4. A Turrent for Glass-Bending Furnaces

    Microsoft Academic Search

    Yu. N. Vavilov; V. I. Lashin; V. A. Malygin; I. Yu. Skobeleva

    2003-01-01

    A new design for a manipulator turrent intended for the fixation of large-size windshield glasses in bending is considered. The device allows for gripping a flat glass packet (glass + film + glass) before bending, as well as molded glass after bending, and placing it on a carrier car. The kinematic scheme and the layout of the device are presented.

  5. Method for heating a glass sheet

    DOEpatents

    Boaz, P.T.

    1998-07-21

    A method for heating a glass sheet includes the steps of heating a glass sheet to a first predetermined temperature and applying microwave energy to the glass sheet to heat the glass sheet to at least a second predetermined temperature to allow the glass sheet to be formed. 5 figs.

  6. Simulated strength-grain size study using a glass-glass-ceramic composite system

    Microsoft Academic Search

    Anil V. Virkar

    1981-01-01

    Strength studies have been conducted on composite specimens of a glass and a glass-ceramic. The composite system consists of a glass fillet on the surface of a bar-shaped glass-ceramic. Controlled surface flaws have been introduced into the glass fillet via indentation. Strength has been studied as a function of indent load and the size of the glass fillet. The glass-glass-ceramic

  7. Alternative substrates to glass mirrors

    NASA Astrophysics Data System (ADS)

    Ruch, Eric

    1993-10-01

    Traditionally glass represents the common choice for mirror substrates and the current development of new techniques such as glass ceramics, lightweighted blanks or honeycomb structures even increase the fields of application of glass mirrors. However, the research on alternative substrates for mirrors covers a large variety of materials: metals, silicon, silicon carbide, metal matrix, etc... This presentation concentrates on the machining, polishing and testing of aluminum mirrors to demonstrate that the optical performance of these substrates can be compared to the more classical glass mirrors.

  8. Glass corrosion in natural environments

    NASA Technical Reports Server (NTRS)

    Thorpe, Arthur N.; Barkatt, Aaron

    1992-01-01

    Experiments carried out during the progress period are summarized. Experiments carried out involving glass samples exposed to solutions of Tris have shown the appearance of 'spikes' upon monitoring glass dissolution as a function of time. The periodic 'spikes' observed in Tris-based media were interpreted in terms of cracking due to excessive stress in the surface region of the glass. Studies of the interactions of silicate glasses with metal ions in buffered media were extended to systems containing Al. Caps buffer was used to establish the pH. The procedures used are described and the results are given. Preliminary studies were initiated as to the feasibility of adding a slowly dissolving solid compound of the additive to the glass-water system to maintain a supply of dissolved additive. It appears that several magnesium compounds have a suitable combination of solubility and affinity towards silicate glass surfaces to have a pronounced retarding effect on the extraction of uranium from the glass. These preliminary findings raise the possibility that introducing a magnesium source into geologic repositories for nuclear waste glass in the form of a sparingly soluble Mg-based backfill material may cause a substantial reduction in the extent of long-term glass corrosion. The studies described also provide mechanistic understanding of the roles of various metal solutes in the leachant. Such understanding forms the basis for developing long-term predictions of nuclear waste glass durability under repository conditions. From what is known about natural highly reduced glasses such as tektites, it is clear that iron is dissolved as ferrous iron with little or no ferric iron. The reducing conditions were high enough to cause metallic iron to exsolve out of the glass in the form of submicroscopic spherules. As the nuclear waste glass is much less reduced, a study was initiated on other natural glasses in addition to the nuclear waste glass. Extensive measurements were carried out on these glasses in order to characterize their magnetic properties. Results of these studies are described.

  9. Glass corrosion in natural environment

    NASA Technical Reports Server (NTRS)

    Thorpe, Arthur N.

    1989-01-01

    A series of studies of the effects of solutes which appear in natural aqueous environments, specifically Mg and Al, under controlled conditions, permit characterization of the retardation of silicate glass leaching in water containing such solutes. In the case of Mg the interaction with the glass appears to consist of exchange with alkali ions present in the glass to a depth of several microns. The effect of Al can be observed at much lower levels, indicating that the mechanism in the case of Al involves irreversible formation of aluminosilicate species at the glass surface.

  10. Stable glasses from strong liquids

    NASA Astrophysics Data System (ADS)

    Chua, Yeong Zen; Ahrenberg, Mathias; Tylinski, Michael; Ediger, Mark D.; Schick, Christoph

    2015-03-01

    To date, only several materials have been observed to form ultra-stable glasses by vapor deposition. Some authors have suggested that fragility might be a controlling factor in the ability to form stable glasses by vapor deposition, with highly stable glasses only being possible for highly fragile liquids. Glasses of ethylcyclohexane, fragility index 56.5, and 1-pentene, a very small molecule, produced by physical vapor deposition have been characterized by in situ AC chip nanocalorimetry. Since the fragility index of 1-pentene was not available, it was determined as 52 from the calorimetric glass transition temperatures measured in the frequency range from 0.2 Hz to 4 kHz. Ethylcyclohexane and 1-pentene are both strong glass formers, for which possibility of stable glass formation has been questioned. On the contrary, we observed formation of highly stable glasses of ethylcyclohexane and 1-pentene. The results on ethylcyclohexane and 1-pentene will be presented and compared with literature data of other known glass formers.

  11. Phosphate base laser glasses

    SciTech Connect

    Izumitani, T.; Tsuru, M.

    1980-12-16

    A phosphate base laser glass comprising 55-70% P2O5, 1-15% Al2O3, 0-25% Li2O, 0-25% Na2O, 0-8% K2O, the total proportion of Li2O, Na2O, and K2O being 10-25%, 0-15% BaO, 0-15% ZnO, 0-15% CaO , 0-15%, sro, 0-15% MgO, the total proportion of BaO, ZnO, CaO, SrO, and MgO being 5-15%, 0-5% Y2O3, 0-5% La2O3, 0-5% GeO2, 0-5% CeO2, 0-3% Nb2O5, 0-3% MnO2, 0-2% Ta2O5, 0-1% Sb2O3, and 0.01-5% Nd2O3, all % being mole %. The phosphate base laser glass of this invention has a high induced emission cross section, a low non-linear refractive index coefficient, and excellent acid resistance and divitrification resistance. By replacing partially or wholely one or more of LiO2, Na2O, K2O, BaO, ZnO, CaO, SrO, MgO or Al2O3 by LiF, NaF, KF , BaF2ZnF2, CaF2, SrF2, MgF2 or AlF3, respectively, the above properties of the laser glass are further improved.

  12. Examination of glass-silicon and glass-glass bonding techniques for microfluidic systems

    SciTech Connect

    Raley, N.F.; Davidson, J.C.; Balch, J.W.

    1995-10-23

    We report here on the results of experiments concerning particular bonding processes potentially useful for ultimate miniaturization of microfluidic systems. Direct anodic bonding of continuous thin pyrex glass of 250 {mu}m thickness to silicon substrates gives multiple, large voids in the glass. Etchback of thick glass of 1200 {mu}m thickness bonded to silicon substrates gives thin continuous glass layers of 189 {mu}m thickness without voids over areas of 5 cm {times} 12 cm. Glass was also successfully bonded to glass by thermal bonding at 800{degrees}C over a 5 cm {times} 7 cm area. Anticipated applications include microfabricated DNA sequencing, flow injection analysis, and liquid and gas chromatography microinstruments.

  13. Halide laser glasses

    SciTech Connect

    Weber, M.J.

    1982-01-14

    Energy storage and energy extraction are of prime importance for efficient laser action and are affected by the line strengths and linewidths of optical transitions, excited-state lifetimes, nonradiative decay processes, spectroscopic inhomogeneities, nonlinear refractive index, and damage threshold. These properties are all host dependent. To illustrate this, the spectroscopic properties of Nd/sup 3 +/ have been measured in numerous oxide, oxyhalide, and halide glasses. A table summarizes the reported ranges of stimulated emission cross sections, peak wavelengths, linewidths, and radiative lifetimes associated with the /sup 4/F/sub 3/2/ ..-->.. /sup 4/I/sub 11/2/ lasing transition.

  14. 7.G Stained Glass

    NSDL National Science Digital Library

    This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: The students in Mr. Rivera's art class are designing a stained-glass window to hang in the school entryway. The window will be 2 feet tall and 5 feet w...

  15. Glass rupture disk

    DOEpatents

    Glass, S. Jill (Albuquerque, NM); Nicolaysen, Scott D. (Albuquerque, NM); Beauchamp, Edwin K. (Albuquerque, NM)

    2002-01-01

    A frangible rupture disk and mounting apparatus for use in blocking fluid flow, generally in a fluid conducting conduit such as a well casing, a well tubing string or other conduits within subterranean boreholes. The disk can also be utilized in above-surface pipes or tanks where temporary and controllable fluid blockage is required. The frangible rupture disk is made from a pre-stressed glass with controllable rupture properties wherein the strength distribution has a standard deviation less than approximately 5% from the mean strength. The frangible rupture disk has controllable operating pressures and rupture pressures.

  16. POROUS WALL, HOLLOW GLASS MICROSPHERES

    SciTech Connect

    Sexton, W.

    2012-06-30

    Hollow Glass Microspheres (HGM) is not a new technology. All one has to do is go to the internet and Google{trademark} HGM. Anyone can buy HGM and they have a wide variety of uses. HGM are usually between 1 to 100 microns in diameter, although their size can range from 100 nanometers to 5 millimeters in diameter. HGM are used as lightweight filler in composite materials such as syntactic foam and lightweight concrete. In 1968 a patent was issued to W. Beck of the 3M{trademark} Company for 'Glass Bubbles Prepared by Reheating Solid Glass Particles'. In 1983 P. Howell was issued a patent for 'Glass Bubbles of Increased Collapse Strength' and in 1988 H. Marshall was issued a patent for 'Glass Microbubbles'. Now Google{trademark}, Porous Wall, Hollow Glass Microspheres (PW-HGMs), the key words here are Porous Wall. Almost every article has its beginning with the research done at the Savannah River National Laboratory (SRNL). The Savannah River Site (SRS) where SRNL is located has a long and successful history of working with hydrogen and its isotopes for national security, energy, waste management and environmental remediation applications. This includes more than 30 years of experience developing, processing, and implementing special ceramics, including glasses for a variety of Department of Energy (DOE) missions. In the case of glasses, SRS and SRNL have been involved in both the science and engineering of vitreous or glass based systems. As a part of this glass experience and expertise, SRNL has developed a number of niches in the glass arena, one of which is the development of porous glass systems for a variety of applications. These porous glass systems include sol gel glasses, which include both xerogels and aerogels, as well as phase separated glass compositions, that can be subsequently treated to produce another unique type of porosity within the glass forms. The porous glasses can increase the surface area compared to 'normal glasses of a 1 to 2 order of magnitude, which can result in unique properties in areas such as hydrogen storage, gas transport, gas separations and purifications, sensors, global warming applications, new drug delivery systems and so on. One of the most interesting porous glass products that SRNL has developed and patented is Porous Wall, Hollow Glass Microspheres (PW-HGMs) that are being studied for many different applications. The European Patent Office (EPO) just recently notified SRS that the continuation-in-part patent application for the PW-HGMs has been accepted. The original patent, which was granted by the EPO on June 2, 2010, was validated in France, Germany and the United Kingdom. The microspheres produced are generally in the range of 2 to 100 microns, with a 1 to 2 micron wall. What makes the SRNL microspheres unique from all others is that the team in Figure 1 has found a way to induce and control porosity through the thin walls on a scale of 100 to 3000 {angstrom}. This is what makes the SRNL HW-HGMs one-of-a-kind, and is responsible for many of their unique properties and potential for various applications, including those in tritium storage, gas separations, H-storage for vehicles, and even a variety of new medical applications in the areas of drug delivery and MRI contrast agents. SRNL Hollow Glass Microspheres, and subsequent, Porous Wall, Hollow Glass Microspheres are fabricated using a flame former apparatus. Figure 2 is a schematic of the apparatus.

  17. Mechanical loss spectroscopy on inorganic glasses and glass ceramics

    Microsoft Academic Search

    B. Roling

    2001-01-01

    While the classical mechanical loss studies on ion conducting glasses and glass ceramics were done with the help of torsional pendulums with relatively narrow frequency windows, there has been effort in the last years to make use of commercially available instrumentation for dynamic mechanical thermal analysis (DMTA) in order to perform mechanical loss spectroscopy over broader frequency ranges. This opens

  18. Glass Ratio Glass Ratio pentane (tech) ethyl ether

    E-print Network

    Turro, Claudia

    Glass Ratio Glass Ratio pentane (tech) ethyl ether Petroleum Ether (30-60) 2-methyl-THF 2-methylpentane ethyl ether/isopentane 1:1, 1:2 3-methylpentane ethyl ether/methylcyclohexane 2:3 3-ethylpentane propyl ether/pentane 2:1 2,3-dimethylpentane EtOH 3-methylhexane glycerol 4-methylheptane 1-propanol 3

  19. Recent advances in phosphate glass fiber lasers

    Microsoft Academic Search

    A. Schulzgen; L. Li; X. Zhu; J. Albert; N. Peyghambarian

    2009-01-01

    Phosphate glasses are excellent host materials for lasers using rare-earth ion transitions. Combining highly-doped phosphate glasses and advanced fiber drawing techniques, we developed phosphate glass fiber lasers and will review recent advances in their performance.

  20. Aspects of the mechanics of metallic glasses

    E-print Network

    Henann, David Lee

    2011-01-01

    Metallic glasses are amorphous materials that possess unique mechanical properties, such as high tensile strengths and good fracture toughnesses. Also, since they are amorphous, metallic glasses exhibit a glass transition, ...

  1. Direct Analysis of the Ion-Hopping Process Associated with the [alpha]-Relaxation in Perfluorosulfonate Ionomers Using Quasielastic Neutron Scattering

    SciTech Connect

    Page, Kirt A.; Park, Jong Keun; Moore, Robert B.; Garcia Sakai, Victoria; (NIST); (VPI-SU)

    2009-06-12

    This work demonstrates the ability of quasielastic neutron scattering (QENS) to measure the dynamics associated with counterions in perfluorosulfonate ionomers (PFSIs). PFSI membranes were prepared by neutralizing with hydrogenated alkyl ammonium counterions. Counterion dynamics were measured using the High-Flux Backscattering Spectrometer at the National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR). Long-range mobility of the counterions was closely linked with the {alpha}-relaxation in these materials measured by dynamic mechanical analysis (DMA). The counterion motions in the membrane were found to follow a mechanism of random jump-diffusion within a confined spatial region with diffusion coefficients on the order of 10{sup -7} cm{sup 2} s{sup -1}. These data are presented along with variable temperature X-ray scattering investigations of the melting behavior of these materials. Altogether, the data presented here show the link between the onset of long-range counterion mobility and the mechanical properties of these materials. These data provide further fundamental understanding of the link between electrostatic interactions and dynamics in PFSI materials.

  2. The fate of arsenic, cadmium and lead in Typha latifolia: a case study on the applicability of micro-PIXE in plant ionomics.

    PubMed

    Lyubenova, Lyudmila; Pongrac, Paula; Vogel-Mikuš, Katarina; Mezek, Gašper Kukec; Vavpeti?, Primož; Grlj, Nataša; Regvar, Marjana; Pelicon, Primož; Schröder, Peter

    2013-03-15

    Understanding the uptake, accumulation and distribution of toxic elements in plants is crucial to the design of effective phytoremediation strategies, especially in the case of complex multi-element pollution. Using micro-proton induced X-ray emission, the spatial distribution of Na, Mg, Al, Si, P, S, Cl, K, Ca, Mn, Fe, Zn, As, Br, Rb, Sr, Cd and Pb have been quantitatively resolved in roots and rhizomes of an obligate wetland plant species, Typha latifolia, treated with a mixture of 100 ?M each of As, Cd and Pb, together. The highest concentrations of As, Cd and Pb were found in the roots of the T. latifolia, with tissue-specific distributions. The As was detected in the root rhizodermis, and in the rhizome the majority of the As was within the vascular tissues, which indicates the high mobility of As within T. latifolia. The Cd was detected in the root exodermis, and in the vascular bundle and epidermis of the rhizome. The highest Pb concentrations were detected in the root rhizodermis and exodermis, and in the epidermis of the rhizome. These data represent an essential step in the resolution of fundamental questions in plant ionomics. PMID:23416480

  3. Construction of a lithium ion transport network in cathode with lithiated bis(benzene sulfonyl)imide based single ion polymer ionomers

    NASA Astrophysics Data System (ADS)

    Pan, Qiyun; Zhang, Wenchao; Pan, Meize; Zhang, Baodan; Zeng, Danli; Sun, Yubao; Cheng, Hansong

    2015-06-01

    We demonstrate a novel method to construct a lithium ion transport network in cathode materials by replacing PVDF with lithiated poly(bis(4-carbonyl benzene sulfonyl)imide-co-bis(4-amino benzene sulfonyl)imide) as the binder. The single ion conducting polymer was synthesized via polycondensation of bis(4-carbonyl benzene sulfonyl)imide and bis(4-amino benzene sulfonyl)imide followed by lithium ion exchange. By blending the ionomers with LiFePO4 and acetylene carbon, the ionic network was well constructed, resulting in a maximum use of active cathode material inside the cathode. The membrane of the polymer electrolyte exhibits an ionic conductivity of 0.14 mS cm-1 at room temperature, a high ion transference number of 0.92 and a wide electrochemical window of 4.5 V (vs. Li+/Li). A lithium ion battery assembled with the single ion conducting polymer electrolyte delivers excellent performance at room temperature with various C-rates.

  4. Quinary metallic glass alloys

    DOEpatents

    Lin, Xianghong (Pasadena, CA); Johnson, William L. (Pasadena, CA)

    1998-01-01

    At least quinary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10.sup.3 K/s. Such alloys comprise zirconium and/or hafnium in the range of 45 to 65 atomic percent, titanium and/or niobium in the range of 4 to 7.5 atomic percent, and aluminum and/or zinc in the range of 5 to 15 atomic percent. The balance of the alloy compositions comprise copper, iron, and cobalt and/or nickel. The composition is constrained such that the atomic percentage of iron is less than 10 percent. Further, the ratio of copper to nickel and/or cobalt is in the range of from 1:2 to 2:1. The alloy composition formula is: (Zr,Hf).sub.a (Al,Zn).sub.b (Ti,Nb).sub.c (Cu.sub.x Fe.sub.y (Ni,Co).sub.z).sub.d wherein the constraints upon the formula are: a ranges from 45 to 65 atomic percent, b ranges from 5 to 15 atomic percent, c ranges from 4 to 7.5 atomic percent, d comprises the balance, d.multidot.y is less than 10 atomic percent, and x/z ranges from 0.5 to 2.

  5. Quinary metallic glass alloys

    DOEpatents

    Lin, X.; Johnson, W.L.

    1998-04-07

    At least quinary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10{sup 3}K/s. Such alloys comprise zirconium and/or hafnium in the range of 45 to 65 atomic percent, titanium and/or niobium in the range of 4 to 7.5 atomic percent, and aluminum and/or zinc in the range of 5 to 15 atomic percent. The balance of the alloy compositions comprise copper, iron, and cobalt and/or nickel. The composition is constrained such that the atomic percentage of iron is less than 10 percent. Further, the ratio of copper to nickel and/or cobalt is in the range of from 1:2 to 2:1. The alloy composition formula is: (Zr,Hf){sub a}(Al,Zn){sub b}(Ti,Nb){sub c}(Cu{sub x}Fe{sub y}(Ni,Co){sub z}){sub d} wherein the constraints upon the formula are: a ranges from 45 to 65 atomic percent, b ranges from 5 to 15 atomic percent, c ranges from 4 to 7.5 atomic percent, d comprises the balance, d{hor_ellipsis}y is less than 10 atomic percent, and x/z ranges from 0.5 to 2.

  6. Metallic glass velocity sensor

    NASA Astrophysics Data System (ADS)

    Butler, John L.; Butler, Stephen C.; Massa, Donald P.; Cavanagh, George H.

    1996-04-01

    A metallic glass accelerometer has been developed for use as an underwater sound velocity sensor. The device uses the metallic glass material Metglas 2605SC which has been processed to achieve a virgin coupling coefficient of 0.96. The mechanical to electrical conversion is based on the detection of the change in the inductance of the device as a result of bending motion. The detection method uses a carrier frequency signal which is amplitude modulated by the received signal. This scheme was originally described by Wun-Fogle, Savage and Clark [``Sensitive wide frequency range magnetostrictive strain gauge,'' Sensors and Actuators, 1_2_, 323-331 (1987)]. The bender is in the form of a three layered laminate with a closed magnetic path window frame structure. The theory of operation along with measured and calculated results are presented for a prototype element with approximate dimensions 1.5×1.0×0.1 inches. Calculated and measured results agree for a reduced effective coupling coefficient of 0.72 and operation with a carrier field intensity of 0.87 Oe and carrier frequency of 20 kHz.

  7. Metallic glass velocity sensor

    SciTech Connect

    Butler, J.L. [Image Acoustics, Inc., Cohasset, Massachusetts 02025 (United States); Butler, S.C. [Naval Undersea Warfare Cen., New London, Connecticut 06320 (United States); Massa, D.P.; Cavanagh, G.H. [Massa Products Corporation, Hingham, Massachusetts 02043 (United States)

    1996-04-01

    A metallic glass accelerometer has been developed for use as an underwater sound velocity sensor. The device uses the metallic glass material Metglas 2605SC which has been processed to achieve a virgin coupling coefficient of 0.96. The mechanical to electrical conversion is based on the detection of the change in the inductance of the device as a result of bending motion. The detection method uses a carrier frequency signal which is amplitude modulated by the received signal. This scheme was originally described by Wun-Fogle, Savage and Clark [{open_quote}{open_quote}Sensitive wide frequency range magnetostrictive strain gauge,{close_quote}{close_quote} Sensors and Actuators, 1{underscore}2{underscore}, 323{endash}331 (1987)]. The bender is in the form of a three layered laminate with a closed magnetic path window frame structure. The theory of operation along with measured and calculated results are presented for a prototype element with approximate dimensions 1.5{times}1.0{times}0.1 inches. Calculated and measured results agree for a reduced effective coupling coefficient of 0.72 and operation with a carrier field intensity of 0.87 Oe and carrier frequency of 20 kHz. {copyright} {ital 1996 American Institute of Physics.}

  8. Glass Ceramic Formulation Data Package

    Microsoft Academic Search

    Jarrod V. Crum; Carmen P. Rodriguez; John S. McCloy; John D. Vienna; Chul-Woo Chung

    2012-01-01

    A glass ceramic waste form is being developed for treatment of secondary waste streams generated by aqueous reprocessing of commercial used nuclear fuel (Crum et al. 2012b). The waste stream contains a mixture of transition metals, alkali, alkaline earths, and lanthanides, several of which exceed the solubility limits of a single phase borosilicate glass (Crum et al. 2009; Caurant et

  9. Space processing of chalcogenide glass

    NASA Technical Reports Server (NTRS)

    Firestone, R. F.; Schramm, S. W.

    1978-01-01

    A program was conducted to develop the technique of space processing for chalcogenide glass, and to define the process and equipment necessary. In the course of this program, successful long term levitation of objects in a 1-g environment was achieved. Glass beads 4 mm diameter were containerless melted and fused together.

  10. Refractory Glass Seals for SOFC

    SciTech Connect

    Chou, Y. S.; Stevenson, Jeffry W.

    2011-07-01

    One of the critical challenges facing planar solid oxide fuel cell (SOFC) technology is the need for reliable sealing technology. Seals must exhibit long-term stability and mechanical integrity in the high temperature SOFC environment during normal and transient operation. Several different approaches for sealing SOFC stacks are under development, including glass or glass-ceramic seals, metallic brazes, and compressive seals. Among glass seals, rigid glass-ceramics, self-healing glass, and composite glass approaches have been investigated under the SECA Core Technology Program. The U.S. Department of Energy's Pacific Northwest National Laboratory (PNNL) has developed the refractory glass approach in light of the fact that higher sealing temperatures (e.g., 930-1000 degrees C) may enhance the ultimate in-service bulk strength and electrical conductivity of contact materials, as well as the bonding strength between contact materials and adjacent SOFC components, such as interconnect coatings and electrodes. This report summarizes the thermal, chemical, mechanical, and electrical properties of the refractory sealing glass.

  11. Degradable borate glass polyalkenoate cements.

    PubMed

    Shen, L; Coughlan, A; Towler, M; Hall, M

    2014-04-01

    Glass polyalkenoate cements (GPCs) containing aluminum-free borate glasses having the general composition Ag2O-Na2O-CaO-SrO-ZnO-TiO2-B2O3 were evaluated in this work. An initial screening study of sixteen compositions was used to identify regions of glass formation and cement compositions with promising rheological properties. The results of the screening study were used to develop four model borate glass compositions for further study. A second round of rheological experiments was used to identify a preferred GPC formulation for each model glass composition. The model borate glasses containing higher levels of TiO2 (7.5 mol %) tended to have longer working times and shorter setting times. Dissolution behavior of the four model GPC formulations was evaluated by measuring ion release profiles as a function of time. All four GPC formulations showed evidence of incongruent dissolution behavior when considering the relative release profiles of sodium and boron, although the exact dissolution profile of the glass was presumably obscured by the polymeric cement matrix. Compression testing was undertaken to evaluate cement strength over time during immersion in water. The cements containing the borate glass with 7.5 mol % TiO2 had the highest initial compressive strength, ranging between 20 and 30 MPa. No beneficial aging effect was observed-instead, the strength of all four model GPC formulations was found to degrade with time. PMID:24435528

  12. Oxide glass processing in space

    NASA Technical Reports Server (NTRS)

    Happe, R. A.; Topol, L. E.

    1974-01-01

    The experimental work performed thus far has resulted in the preparation of new glass compositions not reported heretofore in the open literature. Recent experiments which have resulted in the formation of 1/4-inch-diameter glass samples from two compositions, suggest that containerless melting and cooling as envisioned for space operations is of real technological significance. To date studies of space glasses have by choice been confined to oxide glasses only. It is felt that the applications for such glasses are more readily predictable than for the other materials, and that many of the principles that will evolve from a study of oxide glasses, which can be melted in air, permit a more direct approach to non-oxide materials in the future. The compositions being studied are all very simple in terms of traditional glass practices, none of them containing more than three major constituents. Future efforts should be concerned with more complex compositions, both to cover a broader range of optical properties and to enhance glass-forming tendencies.

  13. Platinum in phosphate laser glasses

    Microsoft Academic Search

    Carol Ann Click

    2002-01-01

    The platinum concentration in phosphate laser glasses has been characterized as a function of composition, melting time and temperature. The highest measured ionic platinum concentration is 2042 ppmw in a potassium-alumino-metaphosphate glass after 24 hours of melting at 900°C. The maximum platinum concentration in a given composition decreases with increasing temperature. The time, temperature and composition dependent platinum concentration in

  14. Method of determining glass durability

    DOEpatents

    Jantzen, C.M.; Pickett, J.B.; Brown, K.G.; Edwards, T.B.

    1998-12-08

    A process is described for determining one or more leachate concentrations of one or more components of a glass composition in an aqueous solution of the glass composition by identifying the components of the glass composition, including associated oxides, determining a preliminary glass dissolution estimator, {Delta}G{sub p}, based upon the free energies of hydration for the component reactant species, determining an accelerated glass dissolution function, {Delta}G{sub a}, based upon the free energy associated with weak acid dissociation, {Delta}G{sub a}{sup WA}, and accelerated matrix dissolution at high pH, {Delta}G{sub a}{sup SB} associated with solution strong base formation, and determining a final hydration free energy, {Delta}G{sub f}. This final hydration free energy is then used to determine leachate concentrations for elements of interest using a regression analysis and the formula log{sub 10}(N C{sub i}(g/L))=a{sub i} + b{sub i}{Delta}G{sub f}. The present invention also includes a method to determine whether a particular glass to be produced will be homogeneous or phase separated. The present invention is also directed to methods of monitoring and controlling processes for making glass using these determinations to modify the feedstock materials until a desired glass durability and homogeneity is obtained. 4 figs.

  15. Silicate Glass Corrosion Mechanism revisited

    NASA Astrophysics Data System (ADS)

    Geisler, Thorsten; Lenting, Christoph; Dohmen, Lars

    2015-04-01

    Understanding the mechanism(s) of aqueous corrosion of nuclear waste borosilicate glasses is essential to predict their long-term aqueous durability in a geologic repository. Several observations have been made with compositionally different silicate glasses that cannot be explained by any of the established glass corrosion models. These models are based on diffusion-controlled ion exchange and subsequent structural reorganisation of a leached, hydrated residual glass, leaving behind a so-called gel layer. In fact, the common observation of lamellar to more complex pattern formation observed in experiment and nature, the porous structure of the corrosion layer, an atomically sharp boundary between the corrosion zone and the underlying pristine glass, as well as results of novel isotope tracer and in situ, real time experiments rather support an interface-coupled glass dissolution-silica reprecipitation model. In this model, the congruent dissolution of the glass is coupled in space and time to the precipitation and growth of amorphous silica at an inwardly moving reaction front. We suggest that these coupled processes have to be considered to realistically model the long-term performance of silicate glasses in aqueous environments.

  16. Glass science tutorial: Lecture No. 7, Waste glass technology for Hanford

    SciTech Connect

    Kruger, A.A.

    1995-07-01

    This paper presents the details of the waste glass tutorial session that was held to promote knowledge of waste glass technology and how this can be used at the Hanford Reservation. Topics discussed include: glass properties; statistical approach to glass development; processing properties of nuclear waste glass; glass composition and the effects of composition on durability; model comparisons of free energy of hydration; LLW glass structure; glass crystallization; amorphous phase separation; corrosion of refractories and electrodes in waste glass melters; and glass formulation for maximum waste loading.

  17. Energetics of glass fragmentation: Experiments on synthetic and natural glasses

    NASA Astrophysics Data System (ADS)

    Kolzenburg, S.; Russell, J. K.; Kennedy, L. A.

    2013-11-01

    Natural silicate glasses are an essential component of many volcanic rock types including coherent and pyroclastic rocks; they span a wide range of compositions, occur in diverse environments, and form under a variety of pressure-temperature conditions. In subsurface volcanic environments (e.g., conduits and feeders), melts intersect the thermodynamically defined glass transition temperature to form glasses at elevated confining pressures and under differential stresses. We present a series of room temperature experiments designed to explore the fundamental mechanical and fragmentation behavior of natural (obsidian) and synthetic glasses (Pyrex™) under confining pressures of 0.1-100 MPa. In each experiment, glass cores are driven to brittle failure under compressive triaxial stress. Analysis of the load-displacement response curves is used to quantify the storage of energy in samples prior to failure, the (brittle) release of elastic energy at failure, and the residual energy stored in the post-failure material. We then establish a relationship between the energy density within the sample at failure and the grain-size distributions (D-values) of the experimental products. The relationship between D-values and energy density for compressive fragmentation is significantly different from relationships established by previous workers for decompressive fragmentation. Compressive fragmentation is found to have lower fragmentation efficiency than fragmentation through decompression (i.e., a smaller change in D-value with increasing energy density). We further show that the stress storage capacity of natural glasses can be enhanced (approaching synthetic glasses) through heat treatment.

  18. Database and Interim Glass Property Models for Hanford HLW Glasses

    SciTech Connect

    Hrma, Pavel R; Piepel, Gregory F; Vienna, John D; Cooley, Scott K; Kim, Dong-Sang; Russell, Renee L

    2001-07-24

    The purpose of this report is to provide a methodology for an increase in the efficiency and a decrease in the cost of vitrifying high-level waste (HLW) by optimizing HLW glass formulation. This methodology consists in collecting and generating a database of glass properties that determine HLW glass processability and acceptability and relating these properties to glass composition. The report explains how the property-composition models are developed, fitted to data, used for glass formulation optimization, and continuously updated in response to changes in HLW composition estimates and changes in glass processing technology. Further, the report reviews the glass property-composition literature data and presents their preliminary critical evaluation and screening. Finally the report provides interim property-composition models for melt viscosity, for liquidus temperature (with spinel and zircon primary crystalline phases), and for the product consistency test normalized releases of B, Na, and Li. Models were fitted to a subset of the screened database deemed most relevant for the current HLW composition region.

  19. Strontium containing bioactive glasses: Glass structure and physical properties

    Microsoft Academic Search

    Yann C. Fredholm; Natalia Karpukhina; Robert V. Law; Robert G. Hill

    2010-01-01

    The influence of substituting strontium for calcium in the following glass series 49.46 SiO2–1.07 P2O5–(23.08-X) CaO–X SrO–26.38 Na2O was studied on the physical properties. Solid state nuclear magnetic resonance and vibrational spectroscopy showed that the glasses were predominantly composed of Q2 silicate chains. Addition of strontium did not result in any structural alteration of the glass network due to the

  20. Raman study of glass transition in iron phosphate glasses

    NASA Astrophysics Data System (ADS)

    Chakraborty, S.; Arora, A. K.

    2012-06-01

    Iron phosphate (Fe2O3: P2O5) glass with 40: 60 mol% composition having glass transition temperature, Tg at 782 K, was investigated between 81-873 K using Raman spectroscopy. The spectra were corrected for thermal population factor and the Raman mode frequencies were obtained from Lorentzian peak fits. Three characteristic modes of iron phosphate glass, corresponding to asymmetric stretching of Q0, Q1 and Q2 tetrahedral units, were analyzed for temperature dependences of the mode frequencies. All the modes are found to exhibit typical anharmonic behavior below Tg, while discontinuous changes are found near Tg, thereby suggesting structural relaxations.

  1. Containerless glass fiber processing

    NASA Technical Reports Server (NTRS)

    Ethridge, E. C.; Naumann, R. J.

    1986-01-01

    An acoustic levitation furnace system is described that was developed for testing the feasibility of containerless fiber pulling experiments. It is possible to levitate very dense materials such as platinum at room temperature. Levitation at elevated temperatures is much more difficult. Samples of dense heavy metal fluoride glass were levitated at 300 C. It is therefore possible that containerless fiber pulling experiments could be performed. Fiber pulling from the melt at 650 C is not possible at unit gravity but could be possible at reduced gravities. The Acoustic Levitation Furnace is described, including engineering parameters and processing information. It is illustrated that a shaped reflector greatly increases the levitation force aiding the levitation of more dense materials.

  2. Characterization and in vitro Bioactivity of Zinc-containing Bioactive Glass and Glass-ceramics

    Microsoft Academic Search

    Rui Lin Du; Jiang Chang; Si Yu Ni; Wan Yin Zhai; Jun Ying Wang

    2006-01-01

    Zinc-containing glass is prepared by the substitution of CaO in 58S bioactive glass with 0.5 and 4 wt% ZnO, and glass-ceramics are obtained by heat-treating the glass at 1200 C. The bending strength and in vitro bioactivity of the glass and glass-ceramics are evaluated. The results indicate that Zn promotes the crystallization of SiO2 and wollastonite in glass-ceramics, and proper

  3. Automated glass-fragmentation analysis

    NASA Astrophysics Data System (ADS)

    Gordon, Gaile G.

    1996-02-01

    This paper describes a novel automated inspection process for tempered safety glass. The system is geared toward the European Community (EC) import regulations which are based on fragment count and dimensions in a fractured glass sample. The automation of this test presents two key challenges: image acquisition, and robust particle segmentation. The image acquisition must perform well both for clear and opaque glass. Opaque regions of glass are common in the American auto industry due to painted styling or adhesives (e.g. defroster cables). The system presented uses a multiple light source, reflected light imaging technique, rather than transmitted light imaging which is often used in manual versions of this inspection test. Segmentation of the glass fragments in the resulting images must produce clean and completely connected crack lines in order to compute the correct particle count. Processing must therefore be robust with respect to noise in the imaging process such as dust and glint on the glass. The system presented takes advantage of mathematical morphology algorithms, in particular the watershed algorithm, to perform robust preprocessing and segmentation. Example images and image segmentation results are shown for tempered safety glass which has been painted on the outside edges for styling purposes.

  4. Fracture mechanics of cellular glass

    SciTech Connect

    Zwissler, J.G.; Adams, M.A.

    1981-02-01

    Cellular glasses are prime candidate materials for the structural substrate of mirrored glass for solar concentrator reflecting panels. These materials are brittle, however, and susceptible to mechanical failure from slow crack growth caused by a stress corrosion mechanism. The results are detailed of one part of a program established to develop improved cellular glasses and to characterize the behavior of these and commercially available materials. Commercial and developmental cellular glasses were tested and analyzed using standard testing techniques and models developed from linear fracture mechanics. Two models describing the fracture behavior of these materials are developed. Slow crack growth behavior in cellular glass was found to be more complex than that encountered in dense glasses or ceramics. The crack velocity was found to be strongly dependent upon water vapor transport to the tip of the moving crack. The existence of a static fatigue limit was not conclusively established, however, it is speculated that slow crack growth behavior in Region I may be slower, by orders of magnitude, than that found in dense glasses.

  5. Glass ceramic seals to inconel

    DOEpatents

    McCollister, Howard L. (Albuquerque, NM); Reed, Scott T. (Albuquerque, NM)

    1983-11-08

    A glass ceramic composition prepared by subjecting a glass composition comprising, by weight, 65-80% SiO.sub.2, 8-16%, Li.sub.2 O, 2-8% , Al.sub.2 O.sub.3, 1-8% K.sub.2 O, 1-5% P.sub.2 O.sub.5 and 1.5-7% B.sub.2 O.sub.3, to the following processing steps of heating the glass composition to a temperature sufficient to crystallize lithium metasilicate therein, holding the glass composition at a temperature and for a time period sufficient to dissolve the lithium metasilicate therein thereby creating cristobalite nucleii, cooling the glass composition and maintaining the composition at a temperature and for a time period sufficient to recrystallize lithium metasilicate therein, and thermally treating the glass composition at a temperature and for a time period sufficient to cause growth of cristobalite and further crystallization of lithium metasilicate producing a glass ceramic composition having a specific thermal expansion coefficient and products containing said composition.

  6. GLASS COMPOSITION-TCLP RESPONSE MODEL FOR WASTE GLASSES

    SciTech Connect

    Kim, Dong-Sang; Vienna, John D.

    2004-01-01

    A first-order property model for normalized Toxicity Characteristic Leaching Procedure (TCLP) release as a function of glass composition was developed using data collected from various studies. The normalized boron release is used to estimate the release of toxic elements based on the observation that the boron release represents the conservative release for those constituents of interest. The current TCLP model has two targeted application areas: (1) delisting of waste-glass product as radioactive (not mixed) waste and (2) designating the glass wastes generated from waste-glass research activities as hazardous or non-hazardous. This paper describes the data collection and model development for TCLP releases and discusses the issues related to the application of the model.

  7. Zirconia solubility in boroaluminosilicate glass

    SciTech Connect

    Raman, S.V.; Bopp, R.; Batcheller, T.A. [Lockheed Idaho Technologies Co., Idaho Falls, ID (United States); Yan, Q. [Univ. of Houston, TX (United States). Chemistry Dept.

    1995-12-31

    In the Idaho Chemical Processing Plant (ICPP) waste streams, zirconia is often the waste load limiting species. It modifies the glass network, enhances durability, increases viscosity and induces crystallization. The limits of its dissolution in boroaluminosilicate glass, with magnesia and soda additions were experimentally determined. A ternary compositional surface is evolved to present the isothermal regimes of liquid, liquid + zircon, liquid + forsterite, and liquid phase sintered ceramic. The potential of partitioning the transuranics, transition elements and solutes in these regimes is discussed. The visible Raman spectroscopic results are presented to elucidate the dependence among glass composition, structure and chemical durability.

  8. Zirconia solubility in boroaluminosilicate glass

    SciTech Connect

    Raman, S.V.; Bopp, R.; Batcheller, T.A. [Lockheed Idaho Technologies Co., Idaho Falls, ID (United States). Idaho National Engineering Lab.; Yan, Q. [Univ. of Houston, TX (United States). Chemistry Dept.

    1996-08-01

    In the Idaho Chemical Processing Plant (ICPP) waste streams, zirconia is often the waste load limiting species. It modifies the glass network, enhances durability, increases viscosity and induces crystallization. The limits of its dissolution in boroaluminosilicate glass, with magnesia and soda additions were experimentally determined. A ternary compositional surface is evolved to present the isothermal regimes of liquid, liquid+zircon, liquid+forsterite, and liquid phase sintered ceramic. The potential of partitioning the transuranics, transition elements and solutes in these regimes is discussed. The visible Raman spectroscopic results are presented to elucidate the dependence among glass composition, structure and chemical durability.

  9. Shock temperatures in anorthite glass

    NASA Technical Reports Server (NTRS)

    Boslough, M. B.; Ahrens, T. J.; Mitchell, A. C.

    1986-01-01

    Shock-temperature data and the high-pressure thermal behavior of anorthite glass are examined. Temperatures of anorthite glass shocked to pressures between 48-117 GPa were measured in the temperature range 2500-5600 K using optical pyrometry techniques. The time dependence observed in the emitted light of the glass is analyzed in terms of temperature dependence, emissivity dependences, and the time dependence of absorption or scattering of an intervening layer. The three phase transitions at pressures of about 55, 85, and 100 GPa and with transition energies of about 0.5 MJ/kg are studied.

  10. Recent developments in laser glasses

    SciTech Connect

    Weber, M.J.

    1983-01-10

    The past decade has witnessed a proliferation of new glass-forming compositions including oxides, halides, oxyhalides, and chalcogenides. Many of these glasses are applicable to lasers and have greatly expanded the range of optical properties and spectroscopic parameters available to the laser designer. Our knowledge and understanding of many properties of interest for laser action - transparency, linear and nonlinear refractive indices, and damage threshold of the host glass and the absorption spectrum, radiative and nonradiative transition probabilities, fluorescence wavelength, stimulated emission cross section, and spectroscopic inhomogeneities of the lasing ion Nd/sup 3 +/ - are reviewed.

  11. Mechanical relaxation in glasses and at the glass transition

    Microsoft Academic Search

    U. Buchenau

    2001-01-01

    The Gilroy-Phillips model of relaxational jumps in asymmetric double-well potentials, developed for the Arrhenius-type secondary relaxations of the glass phase, is extended to a formal description of the breakdown of the shear modulus at the glass transition, the alpha process. The extension requires the introduction of two separate parts of the barrier distribution function f(V), with a different temperature behavior

  12. Continuous Fibre Reinforced Glass and Glass-Ceramic Matrix Composites

    Microsoft Academic Search

    Aldo R. Boccaccini

    Glass and glass-ceramic matrix composites with continuous fibre reinforcement are considered in this Chapter, covering aspects\\u000a of their fabrication, microstructural characterisation, properties and applications. The great variety of composite systems\\u000a developed during the last 30 years is discussed and their outstanding thermomechanical properties and high technological potential\\u000a are highlighted. These composites constitute a new family of high-temperature capability, lightweight structural

  13. Studies on glass transition of lithium-iron phosphate glasses

    Microsoft Academic Search

    I. Gorzkowska; P. Jozwiak; J. E. Garbarczyk; M. Wasiucionek; C. M. Julien

    2008-01-01

    Amorphous analogs of lithium-iron phosphates (LFP) were prepared by standard press-quenching method and their thermal stabilities\\u000a as well as structural properties were studied for the first time. Glass transition temperature T\\u000a g determined by DTA method was observed at the temperature range 492–523°C, depending on the glass composition. The maxima\\u000a of crystallization peaks were observed in the 555–579°C range. In

  14. Spin glasses and fragile glasses: Statics, dynamics, and complexity

    PubMed Central

    Parisi, Giorgio

    2006-01-01

    In this paper I will briefly review some theoretical results that have been obtained in recent years for spin glasses and fragile glasses. I will concentrate my attention on the predictions coming from the so called broken replica symmetry approach and on their experimental verifications. I will also mention the relevance or these results for other fields, and in general for complex systems. PMID:16690744

  15. Glass-glass transition during aging of a colloidal clay.

    PubMed

    Angelini, Roberta; Zaccarelli, Emanuela; de Melo Marques, Flavio Augusto; Sztucki, Michael; Fluerasu, Andrei; Ruocco, Giancarlo; Ruzicka, Barbara

    2014-01-01

    Colloidal suspensions are characterized by a variety of microscopic interactions, which generate unconventional phase diagrams encompassing fluid, gel and glassy states and offer the possibility to study new phase and/or state transitions. Among these, glass-glass transitions are rare to be found, especially at ambient conditions. Here, through a combination of dilution experiments, X-ray photon correlation spectroscopy, small angle X-ray scattering, rheological measurements and Monte Carlo simulations, we provide evidence of a spontaneous glass-glass transition in a colloidal clay. Two different glassy states are distinguished with evolving waiting time: a first one, dominated by long-range screened Coulombic repulsion (Wigner glass) and a second one, stabilized by orientational attractions (Disconnected House of Cards glass), occurring after a much longer time. These findings may have implications for heterogeneously charged systems out-of-equilibrium and for applications where a fine control of the local order and/or long term stability of the amorphous materials are required. PMID:24887086

  16. Glass-glass transition during aging of a colloidal clay

    NASA Astrophysics Data System (ADS)

    Angelini, Roberta; Zaccarelli, Emanuela; de Melo Marques, Flavio Augusto; Sztucki, Michael; Fluerasu, Andrei; Ruocco, Giancarlo; Ruzicka, Barbara

    2014-06-01

    Colloidal suspensions are characterized by a variety of microscopic interactions, which generate unconventional phase diagrams encompassing fluid, gel and glassy states and offer the possibility to study new phase and/or state transitions. Among these, glass-glass transitions are rare to be found, especially at ambient conditions. Here, through a combination of dilution experiments, X-ray photon correlation spectroscopy, small angle X-ray scattering, rheological measurements and Monte Carlo simulations, we provide evidence of a spontaneous glass-glass transition in a colloidal clay. Two different glassy states are distinguished with evolving waiting time: a first one, dominated by long-range screened Coulombic repulsion (Wigner glass) and a second one, stabilized by orientational attractions (Disconnected House of Cards glass), occurring after a much longer time. These findings may have implications for heterogeneously charged systems out-of-equilibrium and for applications where a fine control of the local order and/or long term stability of the amorphous materials are required.

  17. Use of fine glass as ASR inhibitor in glass aggregate mortars

    Microsoft Academic Search

    Rachida Idir; Martin Cyr; Arezki Tagnit-Hamou

    2010-01-01

    Demand for recycled glass has considerably decreased in recent years, particularly for mixed glass. Glass is cheaper to store than to recycle, as conditioners require expenses for the recycling process. In order to provide a sustainable solution to glass storage, a potential and incentive way would be to reuse this type of glass in concretes. Depending on the size of

  18. Galactic Hearts of Glass

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Click on image for larger graph

    This artist's concept shows delicate greenish crystals sprinkled throughout the violent core of a pair of colliding galaxies. The white spots represent a thriving population of stars of all sizes and ages. NASA's Spitzer Space Telescope detected more than 20 bright and dusty galactic mergers like the one depicted here, all teeming with the tiny gem-like crystals.

    When galaxies collide, they trigger the birth of large numbers of massive stars. Astronomers believe these blazing hot stars act like furnaces to produce silicate crystals in the same way that glass is made from sand. The stars probably shed the crystals as they age, and as they blow apart in supernovae explosions.

    At the same time the crystals are being churned out, they are also being destroyed. Fast-moving particles from supernova blasts easily convert silicates crystals back to their amorphous, or shapeless, form.

    How is Spitzer seeing the crystals if they are rapidly disappearing? Astronomers say that, for a short period of time at the beginning of galactic mergers, massive stars might be producing silicate crystals faster than they are eliminating them. When our own galaxy merges with the Andromeda galaxy in a few billion years, a similar burst of massive stars and silicate crystals might occur.

    Crystal Storm in Distant Galaxy The graph (see inset above) of infrared data from NASA's Spitzer Space Telescope tells astronomers that a distant galaxy called IRAS 08752+3915 is experiencing a storm of tiny crystals made up of silicates. The crystals are similar to the glass-like grains of sand found on Earth's many beaches.

    The data were taken by Spitzer's infrared spectrograph, which splits light open to reveal its rainbow-like components. The resulting spectrum shown here reveals the signatures of both crystalline (green) and non-crystalline (brown) silicates.

    Spitzer detected the same crystals in 20 additional galaxies, all belonging to a class called ultraluminous infrared galaxies. These extremely bright and dusty galaxies usually consist of two galaxies in the process of smashing into each other. Astronomers believe massive stars at the hearts of the galaxies are churning out clouds of silicate crystals. This phenomenon may represent a short-lived phase in the evolution of galactic mergers.

  19. Surface reactions of natural glasses

    SciTech Connect

    White, A.F.

    1986-12-31

    Reactions at natural glass surfaces are important in studies involving nuclear waste transport due to chemical control on ground water in host rocks such as basalt and tuff, to potential diffusion into natural hydrated glass surfaces and as natural analogs for waste glass stability. Dissolution kinetics can be described by linear surface reaction coupled with cation interdiffusion with resulting rates similar to those of synthetic silicate glasses. Rates of Cs diffusion into hydrated obsidian surfaces between 25{sup 0} and 75{sup 0}C were determined by XPS depth profiles and loss rates from aqueous solutions. Calculated diffusion coefficients were ten others of magnitude more rapid than predicted from an Arrhenius extrapolation of high temperature tracer diffusion data due to surface hydration reactions.

  20. Ion implantation in silicate glasses

    SciTech Connect

    Arnold, G.W.

    1993-12-01

    This review examines the effects of ion implantation on the physical properties of silicate glasses, the compositional modifications that can be brought about, and the use of metal implants to form colloidal nanosize particles for increasing the nonlinear refractive index.

  1. High Tech Art: Chameleon Glass

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Dichroic Glass is a technology wherein extremely thin films of metal are vacuum deposited on a glass surface. The coated glass shields spacecraft instruments from cosmic radiation and protects human vision from unfiltered sunlight in space. Because the coating process allows some wavelengths of light and color to reflect and others to pass through, a chameleon effect is produced. Murray Schwartz, a former aerospace engineer, has based his business KROMA on this NASA optical technology. He produces dichroic stained glass windows, mobiles and jewelry. The technique involves deposition of super thin layers of metal oxides applied one layer at a time in a specific order and thickness for the desired effect. His product line is unique and has been very successful.

  2. Crystallization in TA-23 glass

    SciTech Connect

    Hellstrom, E.E.

    1986-01-01

    Pressed powder and solid preforms of TA-23 glass (for glass-to-metal seals) crystallize while being sealed into battery headers. Pressed powder preforms crystallize from 8 to 59 vol %. Some crystals have been observed in pressed powder preforms prior to sealing. Solid preforms typically crystallize only at glass to metal or glass to mold heterogeneous interfaces. Acoustic emission tests indicate that increased crystallinity in the pressed powder preforms before sealing leads to erratic failure pressures for the headers. Increasing the time the seal is at high temperature increases the degree of crystallinity in the seal and decreases the failure pressure of the header. The crystals have the structure of anorthite (CaAl/sub 2/Si/sub 2/O/sub 8/). Based on these results, we recommend that Sandia National Laboratories (SNL) use only solid preforms of TA-23 in headers for its ambient temperature Li batteries.

  3. Corrosion of Partially Crystallized Glasses

    SciTech Connect

    Hrma, Pavel R.; Riley, Brian J.; Vienna, John D.

    2002-05-21

    Using existing data on corrosion of partially crystallized, simulated, high-level waste glasses, coefficients were introduced to evaluate the cumulative influence of secondary effects, such as residual stresses or concentration gradients on product consistency test response. As compared to predictions based solely on residual glass composition effects, the results showed that cristobalite, eucryptite, and nepheline had a higher-than-predicted impact on glass corrosion, while the effects of baddeleyite, hematite, calcium-zirconium silicate, and zircon were close to those predicted. The effects of acmite and lithium silicate were opposite to those expected based on their compositions. The analysis revealed important limitations of the databases currently available. Better understanding of corrosion phenomena will require quantitative composition data, microscopic characterization of pristine and corroded surfaces, and long-term tests with glass coupons or monoliths.

  4. Crystallization of iron phosphate glasses

    Microsoft Academic Search

    J. Doupovec; J. Sitek; J. Kákoš

    1981-01-01

    Differential thermal analysis (DTA), thermogravimetric analysis (TG), X-ray diffraction and Mössbauer spectroscopy were employed in the investigation of crystalline products of FeOx-P2O5 glasses generated by various heat treatments. In glasses with a high value of ?=Fe2+\\/(Fe2+ + Fe3+), absorption of oxygen occurs in a broad temperature range identified by TG. Depending on the value of ?, two exotherms appear in

  5. Luminescence of powdered uranium glasses

    NASA Technical Reports Server (NTRS)

    Eubanks, A. G.; Mcgarrity, J. M.; Silverman, J.

    1974-01-01

    Measurement of cathodoluminescence and photoluminescence efficiencies in powdered borosilicate glasses having different particle size and different uranium content. Excitation with 100 to 350 keV electrons and with 253.7 nm light was found to produce identical absolute radiant exitance spectra in powdered samples. The most efficient glass was one containing 29.4 wt% B2O3, 58.8 wt% SiO2, 9.8 wt% Na2O and 2.0 wt% UO2.

  6. Fabrication of glass microspheres with conducting surfaces

    DOEpatents

    Elsholz, William E. (Acampo, CA)

    1984-01-01

    A method for making hollow glass microspheres with conducting surfaces by adding a conducting vapor to a region of the glass fabrication furnace. As droplets or particles of glass forming material pass through multiple zones of different temperature in a glass fabrication furnace, and are transformed into hollow glass microspheres, the microspheres pass through a region of conducting vapor, forming a conducting coating on the surface of the microspheres.

  7. Lithium conducting glass ceramic with Nasicon structure

    Microsoft Academic Search

    C. J Leo; B. V. R Chowdari; G. V. Subba Rao; J. L Souquet

    2002-01-01

    Lithium ion conducting glass and glass ceramic of the composition Li1.4[Al0.4Ge1.6(PO4)3], have been synthesized. The monolithic glass pieces on thermal treatment resulted in single-phase glass ceramic with the Nasicon structure. Experiments with different electrodes proved that the lithium electrodes provide accurate values for the ionic conductivity using impedance spectroscopy. ?ionic of the glass ceramic was found to be 3.8×10?5Scm?1 at

  8. Glass Membrane For Controlled Diffusion Of Gases

    DOEpatents

    Shelby, James E. (Alfred Station, NY); Kenyon, Brian E. (Pittsburgh, PA)

    2001-05-15

    A glass structure for controlled permeability of gases includes a glass vessel. The glass vessel has walls and a hollow center for receiving a gas. The glass vessel contains a metal oxide dopant formed with at least one metal selected from the group consisting of transition metals and rare earth metals for controlling diffusion of the gas through the walls of the glass vessel. The vessel releases the gas through its walls upon exposure to a radiation source.

  9. Space processing of chalcogenide glass

    NASA Technical Reports Server (NTRS)

    Ali, M. A.; Larsen, D. C.

    1976-01-01

    The manner in which the weightless, containerless nature of in-space processing can be successfully utilized to improve the quality of infrared transmitting chalcogenide glasses was investigated. The following conclusions were reached: (1) Laboratory experiments have established the techniques, processes and equipment necessary for the production of high purity chalcogenide glasses. (2) Processing techniques have been successfully adopted for Ge28Sb12Se60 glass in a 1-g environment. (3) The Ge28Sb12Se60 glasses that have been processed have optical transmission around 63% (5 mm thick). (4) Laboratory experiments have established that the use of precursor materials in powdered form increases the oxygen contamination of the processed glass. This indicates that high purity precursor materials in bar or pellet form should be used. (5) Modifications were made on the MSFC acoustic levitator in an attempt to improve levitation stability during long-time experiments. Room temperature experiments on As2S3 glasses and high temperature experiments on polystyrene were conducted.

  10. BNFL Report Glass Formers Characterization

    SciTech Connect

    Schumacher, R.F.

    2000-07-27

    The objective of this task was to obtain powder property data on candidate glass former materials, sufficient to guide conceptual design and estimate the cost of glass former handling facilities as requested under Part B1 of BNFL Technical and Development Support. Twenty-nine glass forming materials were selected and obtained from vendors for the characterization of their physical properties, durability in caustic solution, and powder flow characteristics. A glass former was selected based on the characterization for each of the ten oxide classes required for Envelope A, B, and C mixtures. Three blends (A, B, and C) were prepared based on formulations provided by Vitreous State Laboratory and evaluated with the same methods employed for the glass formers. The properties obtained are presented in a series of attached Tables. It was determined that five of the ten glass formers, (kyanite, iron oxide, titania, zircon, and zinc oxide) have the potential to cause some level of solids f low problems. The problems might include arching or ratholing in the silo/hopper. In addition, all of the blends may require consideration for their handling.

  11. BNFL Report Glass Formers Characterization

    SciTech Connect

    Schumacher, R.F.

    2000-07-27

    The objective of this task was to obtain powder property data on candidate glass former materials, sufficient to guide conceptual design and estimate the cost of glass former handling facilities as requested under Part B1 of BNFL Technical and Development Support. Twenty-nine glass forming materials were selected and obtained from vendors for the characterization of their physical properties, durability in caustic solution, and powder flow characteristics. A glass former was selected based on the characterization for each of the ten oxide classes required for Envelope A, B, and C mixtures. Three blends (A, B, and C) were prepared based on formulations provided by Vitreous State Laboratory and evaluated with the same methods employed for the glass formers. The properties obtained are presented in a series of attached Tables. It was determined that five of the ten glass formers, (kyanite, iron oxide, titania, zircon, and zinc oxide) have the potential to cause some level of solids f low problems. In addition, all of the blends may require consideration for their handling. A number of engineering considerations and recommendations were prepared based on the experimental findings, experience, and other process considerations. Recommendations for future testing are included. In conjunction with future work, it is recommended that a professional consultant be engaged to guide and assist with testing and design input.

  12. Antibacterial activity of silver inorganic agent YDA filler.

    PubMed

    Ohashi, S; Saku, S; Yamamoto, K

    2004-04-01

    YDA filler is an antibacterial agent that is currently in commercial dental use. In this study, we attempted to determine whether it exerts an antibacterial effect on human saliva bacteria, and to determine whether it can be used in dental materials. CFUs in 1 mL stimulated human saliva were examined using blood agar and mitis salivarius agar after immersion, with or without YDA filler. The antibacterial effect was compared with that of Ketac-Silver. Dental materials containing 5% wt YDA filler were prepared for in vitro testing on S. mutans and A. viscosus. Furthermore, we examined the in vitro cytotoxicity of experimental MMA resin containing YDA filler on HeLa cells. Human saliva bacteria and mutans streptococci showed reduced viability following exposure to YDA filler after 12 h. The concentration of silver ions released by YDA filler was below 1 ppm after 12 h. Two tested strains showed reduced viability following exposure to dental materials containing YDA filler. In another experiment, MMA resin containing YDA filler did not show cytotoxicity on HeLa cells after 24- and 48-h exposure. Thus, YDA filler may help in the development of antibacterial dental materials, such as composite resin, glass-ionomer or temporary cement. PMID:15089943

  13. HIGH-LEVEL WASTE GLASS FORMULATION MODEL SENSITIVITY STUDY 2009 GLASS FORMULATION MODEL VERSUS 1996 GLASS FORMULATION MODEL

    SciTech Connect

    BELSHER JD; MEINERT FL

    2009-12-07

    This document presents the differences between two HLW glass formulation models (GFM): The 1996 GFM and 2009 GFM. A glass formulation model is a collection of glass property correlations and associated limits, as well as model validity and solubility constraints; it uses the pretreated HLW feed composition to predict the amount and composition of glass forming additives necessary to produce acceptable HLW glass. The 2009 GFM presented in this report was constructed as a nonlinear optimization calculation based on updated glass property data and solubility limits described in PNNL-18501 (2009). Key mission drivers such as the total mass of HLW glass and waste oxide loading are compared between the two glass formulation models. In addition, a sensitivity study was performed within the 2009 GFM to determine the effect of relaxing various constraints on the predicted mass of the HLW glass.

  14. Natural analogues of nuclear waste glass corrosion.

    SciTech Connect

    Abrajano, T.A. Jr.; Ebert, W.L.; Luo, J.S.

    1999-01-06

    This report reviews and summarizes studies performed to characterize the products and processes involved in the corrosion of natural glasses. Studies are also reviewed and evaluated on how well the corrosion of natural glasses in natural environments serves as an analogue for the corrosion of high-level radioactive waste glasses in an engineered geologic disposal system. A wide range of natural and experimental corrosion studies has been performed on three major groups of natural glasses: tektite, obsidian, and basalt. Studies of the corrosion of natural glass attempt to characterize both the nature of alteration products and the reaction kinetics. Information available on natural glass was then compared to corresponding information on the corrosion of nuclear waste glasses, specifically to resolve two key questions: (1) whether one or more natural glasses behave similarly to nuclear waste glasses in laboratory tests, and (2) how these similarities can be used to support projections of the long-term corrosion of nuclear waste glasses. The corrosion behavior of basaltic glasses was most similar to that of nuclear waste glasses, but the corrosion of tektite and obsidian glasses involves certain processes that also occur during the corrosion of nuclear waste glasses. The reactions and processes that control basalt glass dissolution are similar to those that are important in nuclear waste glass dissolution. The key reaction of the overall corrosion mechanism is network hydrolysis, which eventually breaks down the glass network structure that remains after the initial ion-exchange and diffusion processes. This review also highlights some unresolved issues related to the application of an analogue approach to predicting long-term behavior of nuclear waste glass corrosion, such as discrepancies between experimental and field-based estimates of kinetic parameters for basaltic glasses.

  15. Systematic studies on Bi-Sr-Ca-Cu-O glasses and glass ceramics

    Microsoft Academic Search

    R. Singh; E. Zacharias

    1990-01-01

    Bi-Sr-Ca-Cu-O glasses and glass ceramics of various compositions have been synthesised. The glass transition temperature varies from 396 to 422 degrees C depending on the glass composition. DC electrical conductivity, measurements on these glasses show a sharp change in slope of the plot of logarithm of conductivity against reciprocal of temperature at a characteristic temperature that depends on the glass

  16. A Cosmic Magnifying Glass

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Scanning the heavens for the first time since the successful December 1999 servicing mission, NASA's Hubble Space Telescope imaged a giant, cosmic magnifying glass, a massive cluster of galaxies called Abell 2218. This 'hefty' cluster resides in the constellation Draco, some 2 billion light-years from Earth. The cluster is so massive that its enormous gravitational field deflects light rays passing through it, much as an optical lens bends light to form an image. This phenomenon, called gravitational lensing, magnifies, brightens, and distorts images from faraway objects. The cluster's magnifying powers provides a powerful 'zoom lens' for viewing distant galaxies that could not normally be observed with the largest telescopes. The picture is dominated by spiral and elliptical galaxies. Resembling a string of tree lights, the biggest and brightest galaxies are members of the foreground cluster. Researchers are intrigued by a tiny red dot just left of top center. This dot may be an extremely remote object made visible by the cluster's magnifying powers. Further investigation is needed to confirm the object's identity. The color picture already reveals several arc-shaped features that are embedded in the cluster and cannot be easily seen in the black-and- white image. The colors in this picture yield clues to the ages, distances, and temperatures of stars, the stuff of galaxies. Blue pinpoints hot young stars. The yellow-white color of several of the galaxies represents the combined light of many stars. Red identifies cool stars, old stars, and the glow of stars in distant galaxies. This view is only possible by combining Hubble's unique image quality with the rare lensing effect provided by the magnifying cluster.

  17. Characteristic length of glass transition

    NASA Astrophysics Data System (ADS)

    Donth, E.

    1996-03-01

    The characteristic length of the glass transition (? _? ) is based on the concept of cooperatively rearranging regions (CRR's) by Adam & Gibbs (1965): ? _? is the diameter of one CRR. In the theoretical part of the talk a formula is derived how this length can be calculated from calorimetric data of the transformation interval. The approach is based on fluctuations in natural functional subsystems. The corresponding thermodynamics is represented e.g. in a book of the author (E. Donth, Relaxation and Thermodynamics in Polymers. Glass Transition, Akademie-Verlag, Berlin 1992). A typical value for this length is 3 nanometers. In the experimental part several examples are reported to enlarge the experimental evidence for such a length: Squeezing the glass transition in the amorphous layers of partially crystallized PET (C. Schick, Rostock), glass transition of small-molecule glass formers in a series of nanoscaled pores of porous glasses (F. Kremer, Leipzig), comparison with a concentration fluctuation model in homogeneous polymer mixtures (E.W. Fischer, Mainz), and, from our laboratory, backscaling to ? _? across the main transition from the entanglement spacing in several amorphous polymers such as PVAC, PS, NR, and some polymer networks. Rouse backscaling was possible in the ? ? splitting region of several poly(n alkyl methacrylates) resulting in small characteristic lengths of order 1 nanometer near the onset of ? cooperativity. In a speculative outlook a dynamic density pattern is presented, having a cellular structure with higher density and lower mobility of the cell walls. It will be explained, with the aid of different thermal expansion of wall and clusters, how the clusters within the cells maintain a certain mobility far below the glass temperature.

  18. Investigation of Glass Transition Temperature of Binary Tellurite Glasses

    SciTech Connect

    Chippy, L.; Unnithan, C. Harikuttan [Solid State Physics Laboratory, D.B. College, Sasthamcotta, Kollam, Kerala-690 521 (India); Jayakumar, S. [MSM College, Kayamkulam, Kerala (India)

    2011-10-20

    Five series of binary Tellurite glass samples containing Sb{sub 2}O{sub 4}, WO{sub 3}, Fe{sub 2}O{sub 3}, Na{sub 2}O and ZnO{sub 2} are studied in terms of the variation of glass transition temperature (T{sub g}). It is seen that Tg increases as Tellurite concentration decreases in the case of glasses containing metal oxides Sb{sub 2}O{sub 4} WO{sub 3}, and Fe{sub 2}O{sub 3} while T{sub g} shows a decreasing trend with that of Na{sub 2}O and ZnO and the corresponding changes in the network structure are accounted to possible extent. The structural variations are analyzed using the concept of electronegativity.

  19. Mechanisms of Rhyolitic Glass Hydration Below the Glass Transition

    SciTech Connect

    Anovitz, Lawrence {Larry} M [ORNL; Cole, David R [ORNL; Fayek, Mostafa [University of Manitoba, Canada

    2008-01-01

    Although a great deal is known about the interaction between water and rhyolitic glasses and melts at temperatures above the glass transition, the nature of this interaction at lower temperatures is much more obscure. Comparisons between high- and low-temperature diffusion studies suggest that several factors play important roles under lower-temperature conditions that are not significant at higher temperatures. Water concentrations in rhyolitic glasses hydrated at low temperatures are significantly greater than in those hydrated at high temperatures and low pressures. Surface concentrations, which equilibrate quickly with the surrounding environment at high temperature, change far more slowly as temperature decreases, and may not equilibrate at room temperature for hundreds or thousands of years. Temperature extrapolations of high- and low-temperature diffusion data are not consistent, suggesting that a change in mechanism occurs. These differences may be due to the inability of "self-stress," caused by the in-diffusing species, to relax at lower temperature. Preliminary calculations suggest that the level of stress caused by glass-water interaction may be greater than the tensile strength of the glass. On a microstuctural scale, extrapolations of high-temperature Fourier transform infrared spectroscopy (FTIR) data to lower temperatures suggests that there should be little or no hydroxyl present in glasses hydrated at low temperature. Comparisons of low-temperature hydration results among SiO2, obsidian, and albite compositions show distinct differences, and features are present in the spectra that do not occur at high temperature. Analysis of H2O and D2O diffusion also suggest that mechanistic differences occur between low- and high-temperature diffusive processes.

  20. HLW Glass Studies: Development of Crystal-Tolerant HLW Glasses

    SciTech Connect

    Matyas, Josef; Huckleberry, Adam R.; Rodriguez, Carmen P.; Lang, Jesse B.; Owen, Antionette T.; Kruger, Albert A.

    2012-04-02

    In our study, a series of lab-scale crucible tests were performed on designed glasses of different compositions to further investigate and simulate the effect of Cr, Ni, Fe, Al, Li, and RuO2 on the accumulation rate of spinel crystals in the glass discharge riser of the HLW melter. The experimental data were used to expand the compositional region covered by an empirical model developed previously (Matyᚠet al. 2010b), improving its predictive performance. We also investigated the mechanism for agglomeration of particles and impact of agglomerates on accumulation rate. In addition, the TL was measured as a function of temperature and composition.

  1. Relaxation time dispersions in glass forming metallic liquids and glasses

    NASA Astrophysics Data System (ADS)

    Wang, Li-Min; Liu, Riping; Wang, Wei Hua

    2008-04-01

    Relaxation time dispersions in glass forming metallic liquids of diverse fragility characters were reviewed mainly based on mechanical relaxations. The compilation of the stretching exponents revealed the common nonexponential dynamic features among the metallic liquids. The time-temperature-superposition law of the relaxation profiles was identified with an average stretching exponent around 0.5 at low frequency regions near the glass transitions. No notable correlation of the stretching parameter with alloy composition was discerned. The construction of the frequency dependence of the stretching exponent across the whole range of liquid dynamics revealed a striking similarity of the nonexponential dynamics between metallic and fragile molecular liquids.

  2. Impedance spectroscopy studies of silicatitania glasses and glass-ceramics

    NASA Astrophysics Data System (ADS)

    Medina, Francelys A.

    Impedance spectroscopy measurements were performed on a series of silica (SiO2) and silica-titania (SiO2-TiO2) glasses over the frequency range 40 Hz-10 MHz and the temperature range 25-700°C in order to elucidate the origin of the dielectric properties of SiO 2-TiO2 glass-ceramics. This type of glass-ceramic was produced by controlled crystallization of a homogeneous SiO2-TiO2 glass at the eutectic composition. This process resulted in the formation of heterogeneous structures consisting of a very large number of tiny and randomly oriented prolate spheroid crystals of high permittivity and high conductivity TiO2, sparsely distributed in the low permittivity and low conductivity SiO2-rich matrix. The SiO2-TiO 2 glass-ceramics showed dielectric spectra caused by the heterogeneous microstructure. More specifically, the system exhibited a Debye-like dispersion resulting from the convolution of the interfacial polarization contributions of an even mixture of the TiO2 spheroids having their two principal axes randomly oriented along the applied electric field. Another Debye-type dispersion results from the intrinsic dielectric relaxation of the rutile-TiO 2 inclusions. The results are in agreement with Fricke's theory for two-phase suspensions exhibiting Maxwell-Wagner interfacial polarization. To distinguish interfacial polarization relaxations due to the presence of the TiO2 particles from other possible sources of dielectric relaxations in the SiO2-TiO2 glassceramics, the dielectric properties of various types of fused silica glasses were studied. It was found that the inherent dielectric relaxations in the SiO2-matrix are different from those observed in the SiO2-TiO2 glass-ceramics. These glasses exhibited one dielectric relaxation which originated at the surface of the specimens and was attributed to electrode polarization. A second dielectric relaxation at the lower frequencies originated from bulk effects and was ascribed to the conduction polarization. A novel theoretical model based on these assumptions was developed and successfully applied to the present experimental results. This model could be used to predict the effective concentration and mobility of charge carrier ions in silica glass. Impedance measurements were also carried out on glasses in the compositional series (1-x)SiO2--xTiO2 wt% below and above the eutectic composition of ~10.5 wt% for this system. As in the case of fused silica, the observed dielectric relaxation can be described in terms of electrode polarization and conduction polarization. Above the eutectic composition, the system is phase-separated and deviations from the typical behavior in homogeneous glasses could originate from the underlying microstructure.

  3. Space processing of chalcogenide glasses

    NASA Technical Reports Server (NTRS)

    Larsen, D. C.; Ali, M. A.

    1975-01-01

    Chalcogenide glasses are discussed as good infrared transmitters, possessing the strength, corrosion resistance, and scale-up potential necessary for large 10.6-micron windows. The disadvantage of earth-produced chalcogenide glasses is shown to be an infrared absorption coefficient which is unacceptably high relative to alkali halides. This coefficient is traced to optical nonhomogeneities resulting from environmental and container contamination. Space processing is considered as a means of improving the infrared transmission quality of chalcogenides and of eliminating the following problems: optical inhomogeneities caused by thermal currents and density fluctuation in the l-g earth environment; contamination from the earth-melting crucible by oxygen and other elements deleterious to infrared transmission; and, heterogeneous nucleation at the earth-melting crucible-glass interface.

  4. Disaster medicine through Google Glass.

    PubMed

    Carenzo, Luca; Barra, Federico Lorenzo; Ingrassia, Pier Luigi; Colombo, Davide; Costa, Alessandro; Della Corte, Francesco

    2015-06-01

    Nontechnical skills can make a difference in the management of disasters and mass casualty incidents and any tool helping providers in action might improve their ability to respond to such events. Google Glass, released by Google as a new personal communication device, could play a role in this field. We recently tested Google Glass during a full-scale exercise to perform visually guided augmented-reality Simple Triage and Rapid Treatment triage using a custom-made application and to identify casualties and collect georeferenced notes, photos, and videos to be incorporated into the debriefing. Despite some limitations (battery life and privacy concerns), Glass is a promising technology both for telemedicine applications and augmented-reality disaster response support to increase operators' performance, helping them to make better choices on the field; to optimize timings; and finally represents an excellent option to take professional education to a higher level. PMID:25460812

  5. Glasses for seeing beyond visible.

    PubMed

    Zhang, XiangHua; Bureau, Bruno; Lucas, Pierre; Boussard-Pledel, Catherine; Lucas, Jacques

    2008-01-01

    Conventional glasses based on oxides have a transparency limited by phonon absorption in the near IR region and have a limited interest for analyzing information located far beyond the visible. The IR spectral domain is nevertheless of prime interest, since it covers fundamental wavelength ranges used for thermal imaging as well as molecular vibrational signatures. Besides spectacular advances in the field of IR detectors, the main significant progresses are related to the development of IR glass optics, such as lenses or IR optical fibres. The field of IR glasses is almost totally dominated by glasses formed from heavy atoms such as the chalcogens S, Se and Te. Their transparency extends up to 12, 16 and 28 microm for sulfide-, selenide- and the new generation of telluride-based glasses, respectively. They cover the atmospheric transparency domains, 3-5 and 8-13 microm, respectively, at which the IR radiation can propagate allowing thermal imaging and night-vision operations through thick layers of atmosphere. The development of new glass compositions will be discussed on the basis of structural consideration with the objective of moulding low-cost lenses for IR cameras used, for instance, in car-driving assistance. Additionally, multimode, single-index, optical fibres operating in the 3 to 12 microm window developed for in situ remote evanescent-wave IR spectroscopy will also be mentioned. The detection of molecular IR signatures is applied to environmental monitoring for investigating the pollution of underground water with toxic molecules. The extension of this technique to the investigation of biomolecules in three different studies devoted to liver tissues analysis, bio-film formation, and cell metabolism will also be discussed. Finally we will mention the developments in the field of single-mode fibres operating around 10 mum for the Darwin space mission, which is aiming at discovering, signs of biological life in telluric earth-like exoplanets throughout the universe. PMID:18067106

  6. Manufacturing unique glasses in space

    NASA Technical Reports Server (NTRS)

    Happe, R. P.

    1976-01-01

    An air suspension melting technique is described for making glasses from substances which to date have been observed only in the crystalline condition. A laminar flow vertical wind tunnel was constructed for suspending oxide melts that were melted using the energy from a carbon dioxide laser beam. By this method it is possible to melt many high-melting-point materials without interaction between the melt and crucible material. In addition, space melting permits cooling to suppress crystal growth. If a sufficient amount of under cooling is accompanied by a sufficient increase in viscosity, crystallization will be avoided entirely and glass will result.

  7. Experimental studies of glass refining

    NASA Technical Reports Server (NTRS)

    Subramanian, R. S.; Cole, R.; Kondos, P.

    1984-01-01

    The basic components of the experimental apparatus were selected and acquired. Techniques were developed for the fabrication of the special crucibles necessary for the experiments. Arrangements were made for the analysis of glass and gas bubble samples for composition information. Donations of major equipment were received for this project from Owens, Illinois where a similar study had been conducted a few year ago. Decisions were made regarding the actual glass composition to be used, the gas to be used in the first experiments, and the temperatures at which the experiments should be conducted. A microcomputer was acquired, and work was begun on interfacing the video analyzer to it.

  8. Radiation resistance of foam glass

    Microsoft Academic Search

    S. M. Brekhovskikh; É. Z. Zhitomirskaya

    1963-01-01

    The radiation resistance of two types of foamed glass was studied. The ; first type was prepared from 90 to 95% alkali window glass (71.5% SiOâ, 1 ; to 1.5% AlâOâ, 7.5 to 8% CaO, 3 to 3.5% MgO, 15% NaâO) and 16 ; to 5% AlâOâ, TiOâ, or ZrOâ, with the addition of 6.5 to ; 1% SiC or

  9. Theories of glass formation and the glass transition.

    PubMed

    Langer, J S

    2014-04-01

    This key-issues review is a plea for a new focus on simpler and more realistic models of glass-forming fluids. It seems to me that we have too often been led astray by sophisticated mathematical models that beautifully capture some of the most intriguing features of glassy behavior, but are too unrealistic to provide bases for predictive theories. As illustrations of what I mean, the first part of this article is devoted to brief summaries of imaginative, sensible, but disparate and often contradictory ideas for solving glass problems. Almost all of these ideas remain alive today, with their own enthusiastic advocates. I then describe numerical simulations, mostly by H Tanaka and coworkers, in which it appears that very simple, polydisperse systems of hard disks and spheres develop long range, Ising-like, bond-orientational order as they approach glass transitions. Finally, I summarize my recent proposal that topologically ordered clusters of particles, in disordered environments, tend to become aligned with each other as if they were two-state systems, and thus produce the observed Ising-like behavior. Neither Tanaka's results nor my proposed interpretation of them fit comfortably within any of the currently popular glass theories. PMID:24646953

  10. Biomedical engineering analysis of glass impact injuries.

    PubMed

    Sances, Anthony; Carlin, Fred H; Kumaresan, Srirangam; Enz, Bruce

    2002-01-01

    This article outlines the history, development, and safety aspects of glass and its use in motor vehicles. It traces the manufacture and describes the characteristics of laminated and tempered glass. It further compares the differences in injuries caused by impact with laminated and tempered glass. The development, use, and results of high penetration resistance (HPR) laminated glass for windshields are examined. Head and neck injuries from impact with glass and glazing structures are delineated. Results of studies with laminated and tempered glass are presented. The probability and severity of injuries occurring secondary to partial or full ejection of vehicle occupants are discussed, and the differences between the performance of laminated and tempered glass are highlighted. Current research to quantify head and neck injury parameters caused by glass impact during rollover is described. The biomechanics of head and neck injury assessment and the development of injury prediction parameters and reference values, respectively, are reviewed. PMID:12739754

  11. Effects of glass composition on the liquidus surfaces of high zirconia containing waste glasses

    Microsoft Academic Search

    Sirithan Bulpakdi Jiemsirilers

    2000-01-01

    Waste glasses must meet a variety of requirements for processing and product performance. Processing property constraints such as liquidus temperature (TL) and viscosity, and the product performance constraints such as durability have to be considered when formulating glass for waste immobilization. In this study, TL, glass transition temperature (Tg, and chemical durability of borosilicate waste glasses containing ZrO 2 concentrations

  12. Draining our Glass: An Energy and Heat Characterization of Google Glass

    E-print Network

    Zhong, Lin

    Draining our Glass: An Energy and Heat Characterization of Google Glass Robert LiKamWa, Zhen Wang The Google Glass is a mobile device designed to be worn as eyeglasses. This form factor enables new use cases resources on a hands-free display. Recent interest has drawn to Google's spectacle- shaped device, Glass

  13. Alice through Looking Glass after Looking Glass: The Mathematics of Mirrors and Kaleidoscopes

    Microsoft Academic Search

    Roe Goodman

    2004-01-01

    1. ALICE AND THE MIRRORS. Let us imagine that Lewis Carroll stopped con- densing determinants long enough to write a third Alice book called Alice Through Looking Glass After Looking Glass. The book opens with Alice in her chamber in front of a peculiar cone-shaped arrangement of three looking glasses. She steps through one of the looking glasses and finds

  14. Similar behaviors of sulfide and selenide-based chalcogenide glasses to form glass ceramics

    Microsoft Academic Search

    Laurent Calvez; Changgui Lin; Mathieu Rozé; Yannick Ledemi; Erwan Guillevic; Bruno Bureau; Mathieu Allix; Xianghua Zhang

    2010-01-01

    In this paper, the strong influence of alkali halide in chalcogenide glasses is reminded, leading for the first time to highly transparent glasses from the visible range up to 11mum. The behavior of crystallization has been demonstrated to be similar in sulfide and selenide glasses containing gallium as well. The structural evolution of several glass compositions from the Ge-Ga-S or

  15. Crystallization of a barium-aluminosilicate glass

    NASA Technical Reports Server (NTRS)

    Drummond, C. H., III; Lee, W. E.; Bansal, N. P.; Hyatt, M. J.

    1989-01-01

    The crystallization of a celsian glass composition was investigated as a possible high-temperature ceramic matrix material. Heat treatments invariably resulted in crystallization of the hexaclesian phase unless a flux, such as lithia, was added or a nucleating agent used (e.g., celsian seeds). TEM analysis revealed complex microstructures. Glasses with Mo additions contained hexacelsian, mullite, and an Mo-rich glass. Li2O additions stabilized celsian but mullite and Mo-rich glass were still present.

  16. Glass-ceramic from sewage sludge ash

    Microsoft Academic Search

    S SUZUKI; M. TANAKA; T KANEKO

    1997-01-01

    Glass-ceramic was produced by adding limestone to sewage sludge incinerated ash. Black glass was produced by melting a blended\\u000a ash batch at 1450C. For nucleation, this glass was reheated at 800C for 1 h, and reheated at 1100C for 2 h to form glass-ceramic.\\u000a The main components of sewage sludge incinerated ash are SiO2 and Al2O3. Because small amounts of

  17. Lunar ultramafic glasses, chondrules and rocks.

    NASA Technical Reports Server (NTRS)

    Bunch, T. E.; Quaide, W.; Prinz, M.; Keil, K.; Dowty, E.

    1972-01-01

    Analysis of all samples returned by lunar missions before Apollo 15 has shown green glasses of ultramafic composition in soil and microbreccia samples. Ultramafic glasses in Apollos 11 and 14 and Luna 16 samples are rare and similar to each other in composition but different from any of the rocks collected at these sites. Details of work regarding Apollo 15 ultramafic green glasses are discussed together with questions of the origin of all green glasses.

  18. Optical properties of Dy3+ doped bismuth zinc borate glass and glass ceramics

    NASA Astrophysics Data System (ADS)

    Shanmugavelu, B.; Kanth Kumar, V. V. Ravi

    2012-06-01

    Dy3+ doped bismuth zinc borate transparent glasses were prepared by melt quenching technique and these glasses were used precursor to obtain transparent glass ceramics by heat treatment method. XRD pattern of the glass ceramic shows the formation of the ?-BiB3O6 and Bi2ZnOB2O6 phases. The visible emission intensity of the glass ceramics is stronger than the glass. This can be due to the formation of nano nonlinear optical crystallites in glass matrix.

  19. Heating-induced glass-glass and glass-liquid transformations in computer simulations of water.

    PubMed

    Chiu, Janet; Starr, Francis W; Giovambattista, Nicolas

    2014-03-21

    Water exists in at least two families of glassy states, broadly categorized as the low-density (LDA) and high-density amorphous ice (HDA). Remarkably, LDA and HDA can be reversibly interconverted via appropriate thermodynamic paths, such as isothermal compression and isobaric heating, exhibiting first-order-like phase transitions. We perform out-of-equilibrium molecular dynamics simulations of glassy water using the ST2 model to study the evolution of LDA and HDA upon isobaric heating. Depending on pressure, glass-to-glass, glass-to-crystal, glass-to-vapor, as well as glass-to-liquid transformations are found. Specifically, heating LDA results in the following transformations, with increasing heating pressures: (i) LDA-to-vapor (sublimation), (ii) LDA-to-liquid (glass transition), (iii) LDA-to-HDA-to-liquid, (iv) LDA-to-HDA-to-liquid-to-crystal, and (v) LDA-to-HDA-to-crystal. Similarly, heating HDA results in the following transformations, with decreasing heating pressures: (a) HDA-to-crystal, (b) HDA-to-liquid-to-crystal, (c) HDA-to-liquid (glass transition), (d) HDA-to-LDA-to-liquid, and (e) HDA-to-LDA-to-vapor. A more complex sequence may be possible using lower heating rates. For each of these transformations, we determine the corresponding transformation temperature as function of pressure, and provide a P-T "phase diagram" for glassy water based on isobaric heating. Our results for isobaric heating dovetail with the LDA-HDA transformations reported for ST2 glassy water based on isothermal compression/decompression processes [Chiu et al., J. Chem. Phys. 139, 184504 (2013)]. The resulting phase diagram is consistent with the liquid-liquid phase transition hypothesis. At the same time, the glass phase diagram is sensitive to sample preparation, such as heating or compression rates. Interestingly, at least for the rates explored, our results suggest that the LDA-to-liquid (HDA-to-liquid) and LDA-to-HDA (HDA-to-LDA) transformation lines on heating are related, both being associated with the limit of kinetic stability of LDA (HDA). PMID:24655190

  20. Modeling the glass forming ability of metals

    Microsoft Academic Search

    Justin Lee Cheney

    2007-01-01

    A design protocol for the discovery of novel metallic glass compositions has been developed using a multi-model approach. By using a series of modeling criteria, all aspects of vitrification in metals can be simultaneously analyzed, and optimum compositions for metallic glass formation can be accurately determined. The modeling tools used focus on three aspects common among good glass forming alloy:

  1. New horizons for glass formation and stability

    NASA Astrophysics Data System (ADS)

    Greer, A. Lindsay

    2015-06-01

    It has long been thought impossible for pure metals to form stable glasses. Recent work supports earlier evidence of glass formation in pure metals, shows the potential for devices based on rapid glass-crystal phase change, and highlights the lack of an adequate theory for fast crystal growth.

  2. The strength of glass, a nontransparent value

    Microsoft Academic Search

    F. A. Veer

    The tendency in modern architecture to use glass structurally means that we need to know the engineering properties of glass accurately. The most important of these is the failure strength of glass in bending. Although much work on this has been done and published there are still many questions. These deal mainly with the correct statistical description of the strength

  3. The Glass Family Product Demonstration Awards

    E-print Network

    Mountziaris, T. J.

    The Glass Family Product Demonstration Awards Program Overview The Glass Family Product Product Demonstration Awards are generously supported by The Robert and Sandra Glass Innovation Fund to submitting an application. Be sure to include your UMass IC Team Name and contact information in your

  4. Method for milling and drilling glass

    NASA Technical Reports Server (NTRS)

    Rice, S. H. (inventor)

    1980-01-01

    A process for machining glass by placing a rotating carbide working surface under minimum pressure against an area of glass to be worked is described. Concurrently the region between the working surface and the area of glass is wet with a lubricant consisting essentially of a petroleum carrier, a complex mixture of esters and a complex mixture of naturally occurring aromatic oils.

  5. Classification of oxide glasses: A polarizability approach

    SciTech Connect

    Dimitrov, Vesselin [Department of Silicate Technology, University of Chemical Technology and Metallurgy, 8 Kl. Ohridski Blvd., Sofia 1756 (Bulgaria); Komatsu, Takayuki [Department of Chemistry, The Nagaoka University of Technology, 1603-1 Kamitomioka-cho, Nagaoka-shi, Niigata-ken 940-2188 (Japan)]. E-mail: komatsu@chem.nagaokaut.ac.jp

    2005-03-15

    A classification of binary oxide glasses has been proposed taking into account the values obtained on their refractive index-based oxide ion polarizability {alpha}{sub O2-}(n{sub 0}), optical basicity {lambda}(n{sub 0}), metallization criterion M(n{sub 0}), interaction parameter A(n{sub 0}), and ion's effective charges as well as O1s and metal binding energies determined by XPS. Four groups of oxide glasses have been established: glasses formed by two glass-forming acidic oxides; glasses formed by glass-forming acidic oxide and modifier's basic oxide; glasses formed by glass-forming acidic and conditional glass-forming basic oxide; glasses formed by two basic oxides. The role of electronic ion polarizability in chemical bonding of oxide glasses has been also estimated. Good agreement has been found with the previous results concerning classification of simple oxides. The results obtained probably provide good basis for prediction of type of bonding in oxide glasses on the basis of refractive index as well as for prediction of new nonlinear optical materials.

  6. Nickel-iron spherules from aouelloul glass

    USGS Publications Warehouse

    Chao, E.C.T.; Dwornik, E.J.; Merrill, C.W.

    1966-01-01

    Nickel-iron spherules, ranging from less than 0.2 to 50 microns in diameter and containing 1.7 to 9.0 percent Ni by weight, occur in glass associated with the Aouelloul crater. They occur in discrete bands of siliceous glass enriched in dissolved iron. Their discovery is significant tangible evidence that both crater and glass originated from terrestrial impact.

  7. Heavy metal oxide glasses as active materials

    Microsoft Academic Search

    Douglas R. MacFarlane; Peter J. Newman; Ruth Plathe; David J. Booth

    1999-01-01

    The solubility of rare earths at a level of 0.5 mol% in traditional heavy metal oxide glasses based on bismuth, lead and gallium is limited to the largest cations Pr, Nd and Sm. Within the families of these oxide glasses, a higher level of doping was achieved in this work with a heavy metal oxide glass containing germanium as a

  8. Glass Transition Measurements of Ultrathin Polystyrene Films

    E-print Network

    1 Glass Transition Measurements of Ultrathin Polystyrene Films Cynthia Buenviaje, Franco Dinelli. Measurements taken on polystyrene surfaces of various film thickness provide insight into how the glass of polymers have been studied extensively, many properties of thin films, specifically the glass transition

  9. Waste Toolkit A-Z Glass Grundon

    E-print Network

    Melham, Tom

    Waste Toolkit A-Z Glass ­ Grundon How can I recycle glass? Departments can recycle small amounts of glass in the Grundon office recycling boxes (see Recycling in the Waste Toolkit A-Z). `Small amounts). When looking at the cost effectiveness of recycling versus waste to landfill, it's worth bearing

  10. Digimarc Discover on Google Glass

    NASA Astrophysics Data System (ADS)

    Rogers, Eliot; Rodriguez, Tony; Lord, John; Alattar, Adnan

    2015-03-01

    This paper reports on the implementation of the Digimarc® Discover platform on Google Glass, enabling the reading of a watermark embedded in a printed material or audio. The embedded watermark typically contains a unique code that identifies the containing media or object and a synchronization signal that allows the watermark to be read robustly. The Digimarc Discover smartphone application can read the watermark from a small portion of printed image presented at any orientation or reasonable distance. Likewise, Discover can read the recently introduced Digimarc Barcode to identify and manage consumer packaged goods in the retail channel. The Digimarc Barcode has several advantages over the traditional barcode and is expected to save the retail industry millions of dollars when deployed at scale. Discover can also read an audio watermark from ambient audio captured using a microphone. The Digimarc Discover platform has been widely deployed on the iPad, iPhone and many Android-based devices, but it has not yet been implemented on a head-worn wearable device, such as Google Glass. Implementing Discover on Google Glass is a challenging task due to the current hardware and software limitations of the device. This paper identifies the challenges encountered in porting Discover to the Google Glass and reports on the solutions created to deliver a prototype implementation.

  11. The development of design factors for heat-strengthened and tempered glass based on the glass failure prediction model 

    E-print Network

    Oakes, Timothy Andrew

    1991-01-01

    for Design Factors for Heat-Stregthened and Tempered Glass Purpose and Scope REVIEW OF MATERIALS, ASSUMPTIONS AND PROCEDURES OF CURRENT DESIGN PRACTICES 1 3 Properties of Glass Types of Glass Annealed Glass Heat-Strengthened and Tempered Glass... year recurrence basis in the U. S. 12 Figure 3 Maximum allowable area of glass: traditional method 14 Figure 4 PPG's annealed float glass thickness selection chart for 3/8 in. (10. 0 mm) glass 15 Figure 5 Flowchart representing the procedure...

  12. Chemical reaction of bioactive glass and glass-ceramics with a simulated body fluid

    Microsoft Academic Search

    T. Kokubo; H. Kushitani; C. Ohtsuki; S. Sakka; T. Yamamuro

    1992-01-01

    Glass-ceramic A-W containing crystalline apatite and wollastonite in an MgO-CaO-SiO2 glassy matrix bonds to living bone through an apatite layer which is formed on its surface in the body. The parent glass G of glass-ceramic A-W and glass-ceramic A, which has the same composition as glass-ceramic A-W but contains only the apatite, also bond to living bone through the surface

  13. Non-parametric analysis of infrared spectra for recognition of glass and glass ceramic fragments in recycling plants

    Microsoft Academic Search

    Alessio Farcomeni; Silvia Serranti; Giuseppe Bonifazi

    2008-01-01

    Glass ceramic detection in glass recycling plants represents a still unsolved problem, as glass ceramic material looks like normal glass and is usually detected only by specialized personnel. The presence of glass-like contaminants inside waste glass products, resulting from both industrial and differentiated urban waste collection, increases process production costs and reduces final product quality. In this paper an innovative

  14. Glass needs for a growing photovoltaics industry

    DOE PAGESBeta

    Burrows, Keith; Fthenakis, Vasilis

    2015-01-01

    With the projected growth in photovoltaics, the demand for glass for the solar industry will far exceed the current supply, and thousands of new float-glass plants will have to be built to meet its needs over the next 20 years. Such expansion will provide an opportunity for the solar industry to obtain products better suited to their needs, such as low-iron glass and borosilicate glass at the lowest possible price. While there are no significant technological hurdles that would prevent the flat glass industry from meeting the solar industry’s projected needs, to do so will require advance planning and substantialmore »investments.« less

  15. Major element composition of Luna 20 glasses.

    NASA Technical Reports Server (NTRS)

    Warner, J.; Reid, A. M.; Ridley, W. I.; Brown, R. W.

    1972-01-01

    Ten per cent of the 50 to 150-micron size fraction of Luna 20 soil is glass. A random suite of 270 of these glasses has been analyzed by electron microprobe techniques. The major glass type forms a strong cluster around a mean value corresponding to Highland basalt (anorthositic gabbro) with 70% normative feldspar. Minor glass groups have the compositions of mare basalts and of low-K Fra Mauro type basalts. The glass data indicate that Highland basalt is the major rock type in the highlands north of Mare Fecunditatis.

  16. Multiple Glasses in Asymmetric Binary Hard Spheres

    E-print Network

    Th. Voigtmann

    2010-10-03

    Multiple distinct glass states occur in binary hard-sphere mixtures with constituents of very disparate sizes according to the mode-coupling theory of the glass transition (MCT), distinguished by considering whether small particles remain mobile or not, and whether small particles contribute significantly to perturb the big-particle structure or not. In the idealized glass, the four different glasses are separated by sharp transitions that give rise to higher-order transition phenomena involving logarithmic decay laws, and to anomalous power-law-like diffusion. The phenomena are argued to be expected generally in glass-forming mixtures.

  17. Production of glass balloons for laser targets

    SciTech Connect

    Hendricks, C.D.; Dressler, J.L.

    1982-09-28

    An apparatus for producing small quantities of glass balloons for use as laser fusion targets is described. To produce precise quantities of the ingredients of one glass balloon, a jet of an aqueous solution of the glass constituents and a blowing agent is metered into uniformly sized drops by Rayleigh breakup. A small fraction of these uniform drops is then passed through an oven where the water is evaporated, the remaining solid material is fused into glass, and a blowing agent decomposes or water of hydration evolves as a vapor to blow the drop into a balloon. Photographs of the resulting glass balloons are presented.

  18. Photon Interaction Parameters for Some Borate Glasses

    SciTech Connect

    Mann, Nisha [Department of Applied Sciences, Samalkha Group of Institutions, Samalkha-132 101, Haryana (India); Kaur, Updesh; Singh, Tejbir; Sharma, J. K. [Department of Physics, Maharishi Markandeshwar University, Mullana-133 207, Haryana (India); Singh, Parjit S. [Department of Physics, Punjabi University, Patiala-147 002, Punjab (India)

    2010-11-06

    Some photon interaction parameters of dosimetric interest such as mass attenuation coefficients, effective atomic number, electron density and KERMA relative to air have been computed in the wide energy range from 1 keV to 100 GeV for some borate glasses viz. barium-lead borate, bismuth-borate, calcium-strontium borate, lead borate and zinc-borate glass. It has been observed that lead borate glass and barium-lead borate glass have maximum values of mass attenuation coefficient, effective atomic number and KERMA relative to air. Hence, these borate glasses are suitable as gamma ray shielding material, packing of radioactive sources etc.

  19. Photon Interaction Parameters for Some Borate Glasses

    NASA Astrophysics Data System (ADS)

    Mann, Nisha; Kaur, Updesh; Singh, Tejbir; Sharma, J. K.; Singh, Parjit S.

    2010-11-01

    Some photon interaction parameters of dosimetric interest such as mass attenuation coefficients, effective atomic number, electron density and KERMA relative to air have been computed in the wide energy range from 1 keV to 100 GeV for some borate glasses viz. barium-lead borate, bismuth-borate, calcium-strontium borate, lead borate and zinc-borate glass. It has been observed that lead borate glass and barium-lead borate glass have maximum values of mass attenuation coefficient, effective atomic number and KERMA relative to air. Hence, these borate glasses are suitable as gamma ray shielding material, packing of radioactive sources etc.

  20. Glass polarization induced drift in microelectromechanical capacitor

    NASA Astrophysics Data System (ADS)

    Haarahiltunen, A.; Varpula, A.; Leinvuo, J.; Siren, E.; Rytkönen, V.-P.; Savin, H.

    2012-05-01

    We present a quantitative physical model for glass substrate polarization and study the glass polarization by measuring the capacitance drift from microelectromechanical capacitor test structure. The model consists of mobile and immobile charge species, which are related to alkali metals and non-bridging oxygen in glass. The model explains consistently our results and the previously observed non-homogeneous charging effect in a radio-frequency switch fabricated on a glass substrate. The results indicate that the bulk properties of the glass layer itself can be a significant source of drift. The modeling allows estimation of the drift behavior of the several kinds of device structures.

  1. Thin glass processing with various laser sources

    NASA Astrophysics Data System (ADS)

    Collins, Adam R.; Milne, David; Prieto, Camilo; O'Connor, Gerard M.

    2015-03-01

    Laser processing of thin glass has proven problematic due to the inefficient coupling of optical energy into glass and the difficulty achieving an economical processing speed while maintaining cut quality. Laser glass processing is pertinent to touch screen display, microfluidic, microoptic and photovoltaic applications. The results of the laser scribing of 110 ?m thick alkali free glass with various laser sources are presented. The laser sources include a CO? laser, nanosecond UV laser and femtosecond IR laser. The contrasting absorption mechanisms are discussed. Cut quality and processing speed are characterised using SEM and optical microscopy techniques. Alternative laser techniques for thin glass processing are also considered.

  2. Glass needs for a growing photovoltaics industry

    DOE PAGESBeta

    Burrows, Keith [Columbia Univ., New York, NY (United States); Fthenakis, Vasilis [Columbia Univ., New York, NY (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-01-01

    With the projected growth in photovoltaics, the demand for glass for the solar industry will far exceed the current supply, and thousands of new float-glass plants will have to be built to meet its needs over the next 20 years. Such expansion will provide an opportunity for the solar industry to obtain products better suited to their needs, such as low-iron glass and borosilicate glass at the lowest possible price. While there are no significant technological hurdles that would prevent the flat glass industry from meeting the solar industry’s projected needs, to do so will require advance planning and substantial investments.

  3. Neutron diffraction studies of natural glasses

    SciTech Connect

    Wright, A.C.; Erwin Desa, J.A.; Weeks, R.A.; Sinclair, R.N.; Bailey, D.K.

    1983-08-01

    A neutron diffraction investigation has been carried out of the structures of several naturally occurring glasses, viz. Libyan Desert glass, a Fulgurite, Wabar glass, Lechatelierite from Canon Diablo, a Tektite, Obsidian (3 samples), and Macusani glass. Libyan Desert sand has also been examined, together with crystalline ..cap alpha..-quartz and ..cap alpha..-cristobalite. A comparison of data for the natural glasses and synthetic vitreous silica (Spectrosil B) in both reciprocal and real space allows a categorisation into Silicas, which closely resemble synthetic vitreous silica, and Silicates, for which the resemblance to silica is consistently less striking. The data support the view that Libyan Desert glass and sand have a common origin, while the Tektite has a structure similar to that of volcanic glasses.

  4. Characterization of Savannah River Plant waste glass

    SciTech Connect

    Plodinec, M J

    1985-01-01

    The objective of the glass characterization programs at the Savannah River Laboratory (SRL) is to ensure that glass containing Savannah River Plant high-level waste can be permanently stored in a federal repository, in an environmentally acceptable manner. To accomplish this objective, SRL is carrying out several experimental programs, including: fundamental studies of the reactions between waste glass and water, particularly repository groundwater; experiments in which candidate repository environments are simulated as accurately as possible; burial tests of simulated waste glass in candidate repository geologies; large-scale tests of glass durability; and determination of the effects of process conditions on glass quality. In this paper, the strategy and current status of each of these programs is discussed. The results indicate that waste packages containing SRP waste glass will satisfy emerging regulatory criteria.

  5. A universal description of ultraslow glass dynamics

    PubMed Central

    Martinez-Garcia, Julio Cesar; Rzoska, Sylwester J.; Drozd-Rzoska, Aleksandra; Martinez-Garcia, Jorge

    2013-01-01

    The dynamics of glass is of importance in materials science but its nature has not yet been fully understood. Here we report that a verification of the temperature dependencies of the primary relaxation time or viscosity in the ultraslowing/ultraviscous domain of glass-forming systems can be carried out via the analysis of the inverse of the Dyre–Olsen temperature index. The subsequent analysis of experimental data indicates the possibility of the self-consistent description of glass-forming low-molecular-weight liquids, polymers, liquid crystals, orientationally disordered crystals and Ising spin-glass-like systems, as well as the prevalence of equations associated with the ‘finite temperature divergence’. All these lead to a new formula for the configurational entropy in glass-forming systems. Furthermore, a link to the dominated local symmetry for a given glass former is identified here. Results obtained show a new relationship between the glass transition and critical phenomena. PMID:23652011

  6. Glasses, ceramics, and composites from lunar materials

    NASA Astrophysics Data System (ADS)

    Beall, George H.

    1992-02-01

    A variety of useful silicate materials can be synthesized from lunar rocks and soils. The simplest to manufacture are glasses and glass-ceramics. Glass fibers can be drawn from a variety of basaltic glasses. Glass articles formed from titania-rich basalts are capable of fine-grained internal crystallization, with resulting strength and abrasion resistance allowing their wide application in construction. Specialty glass-ceramics and fiber-reinforced composites would rely on chemical separation of magnesium silicates and aluminosilicates as well as oxides titania and alumina. Polycrystalline enstatite with induced lamellar twinning has high fracture toughness, while cordierite glass-ceramics combine excellent thermal shock resistance with high flexural strengths. If sapphire or rutile whiskers can be made, composites of even better mechanical properties are envisioned.

  7. Durability of Silicate Glasses: An Historical Approach

    SciTech Connect

    Farges, Francois; /Museum Natl. Hist. Natur. /Stanford U., Geo. Environ. Sci.; Etcheverry, Marie-Pierre; /Marne la Vallee U.; Haddi, Amine; /Marne la Valle U.; Trocellier,; /Saclay; Curti, Enzo; /PSI, Villigen; Brown, Gordon E., Jr.; /SLAC, SSRL

    2007-01-02

    We present a short review of current theories of glass weathering, including glass dissolution, and hydrolysis of nuclear waste glasses, and leaching of historical glasses from an XAFS perspective. The results of various laboratory leaching experiments at different timescales (30 days to 12 years) are compared with results for historical glasses that were weathered by atmospheric gases and soil waters over 500 to 3000 years. Good agreement is found between laboratory experiments and slowly leached historical glasses, with a strong enrichment of metals at the water/gel interface. Depending on the nature of the transition elements originally dissolved in the melt, increasing elemental distributions are expected to increase with time for a given glass durability context.

  8. Low-thermal expansion infrared glass ceramics

    NASA Astrophysics Data System (ADS)

    Lam, Philip

    2009-05-01

    L2 Tech, Inc. is in development of an innovative infrared-transparent glass ceramic material with low-thermal expansion (<0.5 ppm/°C) and high thermal-shock resistance to be used as windows and domes for high speed flight. The material is an inorganic, non-porous glass ceramic, characterized by crystalline phases of evenly distributed nano-crystals in a residual glass phase. The major crystalline phase is zirconium tungstate (ZrW2O8) which has Negative Thermal Expansion (NTE). The glass phase is the infrared-transparent germanate glass which has positive thermal expansion (PTE). Then glass ceramic material has a balanced thermal expansion of near zero. The crystal structure is cubic and the thermal expansion of the glass ceramic is isotropic or equal in all directions.

  9. Glass-ceramic fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Romaniuk, Ryszard S.; Stepien, Ryszard

    1991-03-01

    Optical fibers with layers of glass-ceramics are considered and tested with respect to their use in different environments as single- and multimode lightguides. Glass-ceramic optical fibers are tested that have different material compositions, cross-section topologies, and coefficients of thermal expansion (CTEs). Stress-induced optical phase-temperature effects can be studied with glass ceramics that have CTEs of around zero, and the glass ceramic sensors are compared to nontreated fibers to study the dependencies of the fibers' parameters on induced stress and temperature. The application of glass-ceramics with various values of linear CTE to the fibers is studied to scale the characteristics of a glass-ceramic fiber-optic thermometer for several temperature ranges. The sensor can be stabilized when the pure stress-temperature effect is isolated. These glass-ceramic optical fibers are shown to provide unique characteristics for the use of fiber-optic measuring devices in certain measurement environments.

  10. Matrix glass vs. intruded glass in lunar breccia 15286

    NASA Technical Reports Server (NTRS)

    Handwerker, C. A.; Klein, L. C.; Onorato, P. I. K.; Uhlmann, D. R.

    1977-01-01

    The viscous flow and crystallization behavior of the matrix composition of breccia 15286 have been determined in the 1159-1307 C and 644-770 C temperature ranges. The Shaw (1972) model and, to a slightly lesser extent, the semiempirical Bottinga and Weill (1972) model describe the variation of viscosity with temperature. The crystal growth rate has been determined over the temperature range 821-1185 C. Time-temperature-transformation, logarithmic cooling, and continuous cooling curves were constructed; a nucleation barrier of 60 kT at a relative undercooling of 0.2 is assumed. It is estimated that the matrix of 15286 breccia cooled at a rate greater than 80 K/min through the glass transition region. The increase in density that occurs when the matrix glass is annealed suggests that the breccia was formed by cooling from the molten state rather than by direct shock-induced transition from crystal to glass. Viscous sintering under continuous cooling and logarithmic cooling conditions is analyzed.

  11. Effects of glass composition on the liquidus surfaces of high zirconia containing waste glasses

    NASA Astrophysics Data System (ADS)

    Jiemsirilers, Sirithan Bulpakdi

    Waste glasses must meet a variety of requirements for processing and product performance. Processing property constraints such as liquidus temperature (TL) and viscosity, and the product performance constraints such as durability have to be considered when formulating glass for waste immobilization. In this study, TL, glass transition temperature (Tg, and chemical durability of borosilicate waste glasses containing ZrO 2 concentrations from 6--12 mole% were determined. The concentrations of SiO2, ZrO2, Al2O3, B2 O3, Li2O, Na2O, and CaO were varied using a modified extreme vertices approach. Fifty-three statistically designed glasses were hatched and fabricated. Of the 53 glasses, 19 were not fully characterized due to the presence of undissolved solids (i.e., inhomogeneous glass) although extremely high melt temperatures were utilized (>1500°C). Liquidus temperature, glass transition temperature, and durability of the remaining glasses were examined. Liquidus temperatures (TL) were measured using a series of isothermal heat treatments to narrow the TL to within +/-10°C. The primary crystalline phases were identified using optical microscopy and XRD. The three primary phase fields of Parakeldyshite (Na 2ZrSi2O7) Zircon (ZrSiO4), and Baddeleyite (ZrO2) were encountered for the glass composition region evaluated. Glasses with Parakeldyshite as a primary phase were found to have lower liquidus temperatures, than those glasses having, Zircon or Baddeleyite as the primary phase field. Glass transition temperatures and crystallization temperature were determined using DTA. Glass transition temperatures of glass compositions containing higher percentages of alkali were often lower than those with lower percentages of alkali. This is primary due to a reduction in the connectivity of the glass network. Chemical durability was determined using the Product Consistency Test. The most durable glasses were glasses with lower Na2O content and contained both Al2O3 and CaO. This study showed that the effects of oxide components on glass properties were extremely important for selecting a glass formulation with maximum waste loading. The principles of glass structure such as bridging and nonbridging oxygens and polarizability concept were used to understand the effects. Empirical models were developed based on measured data which related liquidus temperature, glass transition temperature, and durability to glass composition. The experimental data was compared to the predicted data of the model. The purpose of these models were to assist in selecting glasses that offer a maximum ZrO2 waste loading for nuclear waste glasses.

  12. CAD/CAM ZIRCONIA VS. SLIP-CAST GLASS-INFILTRATED ALUMINA/ZIRCONIA ALL-CERAMIC CROWNS: 2-YEAR RESULTS OF A RANDOMIZED CONTROLLED CLINICAL TRIAL

    PubMed Central

    Çehreli, Murat Cavit; Kökat, Ali Murat; Akça, Kivanç

    2009-01-01

    The aim of this randomized controlled clinical trial was to compare the early clinical outcome of slip-cast glass-infiltrated Alumina/Zirconia and CAD/CAM Zirconia all-ceramic crowns. A total of 30 InCeram® Zirconia and Cercon® Zirconia crowns were fabricated and cemented with a glass ionomer cement in 20 patients. At baseline, 6-month, 1-year, and 2-year recall appointments, Californian Dental Association (CDA) quality evaluation system was used to evaluate the prosthetic replacements, and plaque and gingival index scores were used to explore the periodontal outcome of the treatments. No clinical sign of marginal discoloration, persistent pain and secondary caries was detected in any of the restorations. All InCeram® Zirconia crowns survived during the 2-year period, although one nonvital tooth experienced root fracture coupled with the fracture of the veneering porcelain of the restoration. One Cercon® Zirconia restoration fractured and was replaced. According to the CDA criteria, marginal integrity was rated excellent for InCeram® Zirconia (73%) and Cercon® Zirconia (80%) restorations, respectively. Slight color mismatch rate was higher for InCeram® Zirconia restorations (66%) than Cercon® Zirconia (26%) restorations. Plaque and gingival index scores were mostly zero and almost constant over time. Time-dependent changes in plaque and gingival index scores within and between groups were statistically similar (p>0.05). This clinical study demonstrates that single-tooth InCeram® Zirconia and Cercon® Zirconia crowns have comparable early clinical outcome, both seem as acceptable treatment modalities, and most importantly, all-ceramic alumina crowns strengthened by 25% zirconia can sufficiently withstand functional load in the posterior zone. PMID:19148406

  13. Gold based bulk metallic glass

    SciTech Connect

    Schroers, Jan; Lohwongwatana, Boonrat; Johnson, William L.; Peker, Atakan [Keck Laboratory of Engineering Materials, California Institute of Technology, Pasadena, California 91125 and Liquidmetal Technologies, Lake Forest, California 92630 (United States); Keck Laboratory of Engineering Materials, California Institute of Technology, Pasadena, California 91125 (United States); Liquidmetal Technologies, Lake Forest, California 92630 (United States)

    2005-08-08

    Gold-based bulk metallic glass alloys based on Au-Cu-Si are introduced. The alloys exhibit a gold content comparable to 18-karat gold. They show very low liquidus temperature, large supercooled liquid region, and good processibility. The maximum casting thickness exceeds 5 mm in the best glassformer. Au{sub 49}Ag{sub 5.5}Pd{sub 2.3}Cu{sub 26.9}Si{sub 16.3} has a liquidus temperature of 644 K, a glass transition temperature of 401 K, and a supercooled liquid region of 58 K. The Vickers hardness of the alloys in this system is {approx}350 Hv, twice that of conventional 18-karat crystalline gold alloys. This combination of properties makes the alloys attractive for many applications including electronic, medical, dental, surface coating, and jewelry.

  14. Bare Bones of Bioactive Glass

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Paul Ducheyne, a principal investigator in the microgravity materials science program and head of the University of Pernsylvania's Center for Bioactive Materials and Tissue Engineering, is leading the trio as they use simulated microgravity to determine the optimal characteristics of tiny glass particles for growing bone tissue. The result could make possible a much broader range of synthetic bone-grafting applications. Bioactive glass particles (left) with a microporous surface (right) are widely accepted as a synthetic material for periodontal procedures. Using the particles to grow three-dimensional tissue cultures may one day result in developing an improved, more rugged bone tissue that may be used to correct skeletal disorders and bone defects. The work is sponsored by NASA's Office of Biological and Physical Research.

  15. Ionomics and the Study of the Plant Ionome

    E-print Network

    Kihara, Daisuke

    . . . . . . . . . . . . . . . . . . . . . 711 Inductively Coupled Plasma. . . . . . . 712 Optical Emission Spectroscopy. . . . 714 Inductively Coupled Plasma Mass Spectrometry . . . . . . . . . . . . . . . . . 714 X-Ray Fluorescence

  16. Structure of porous Vycor glass

    Microsoft Academic Search

    P. Wiltzius; F. S. Bates; S. B. Dierker; G. D. Wignall

    1987-01-01

    Small-angle neutron scattering experiments investigating the structure of porous Vycor glass are reported. The long-wave-length behavior (0.004 Å-1<=q<=0.025 Å-1) of the measured structure factor S(q) is in good agreement with Cahn's prediction for spinodal decomposition. The high-q data do not conclusively establish whether the internal surfaces are fractally rough over the length scales probed. Experiments on Vycor contrasted with protonated

  17. Structure of porous Vycor glass

    Microsoft Academic Search

    P. Wiltzius; F. S. Bates; S. B. Dierker; G. D. Wignall

    1987-01-01

    Small-angle neutron scattering experiments investigating the structure of porous Vycor glass are reported. The long-wave-length behavior (0.004 A⁻¹less than or equal toqless than or equal to0.025 A⁻¹) of the measured structure factor S(q) is in good agreement with Cahn's prediction for spinodal decomposition. The high-q data do not conclusively establish whether the internal surfaces are fractally rough over the length

  18. The crystallization of diabase glass

    Microsoft Academic Search

    V. Žnidarši?-Pongrac; D. Kolar

    1991-01-01

    The crystallization behaviour of diabase glass at elevated temperatures was studied in samples prepared by melting the diabase rock. DTA and X-ray analyses revealed the crystallization of diopside (CaO · MgO · 2SiO2) at 865 ‡C and anorthite (CaO · Al2O3 · 2SiO2) at 1060 ‡C. Further, the kinetics of crystallization of diopside were studied. The phenomenological Johnson-Mehl-Avrami equation was

  19. Cation coordination in oxychloride glasses

    Microsoft Academic Search

    J. A. Johnson; D. Holland; J. Bland; C. E. Johnson; M. F. Thomas

    2003-01-01

    Glasses containing mixtures of cations and anions of nominal compositions [Sb2O3]x - [ZnCl2]1-x where x = 0.25, 0.50, 0.75, and 1.00, have been studied by means of neutron diffraction and Raman and Mössbauer spectroscopy. There is preferential bonding within the system with the absence of Sb-Cl bonds. Antimony is found to be threefold coordinated to oxygen, and zinc fourfold coordinated.

  20. Cation coordination in oxychloride glasses

    Microsoft Academic Search

    J A Johnson; D Holland; J Bland; C E Johnson; M F Thomas

    2003-01-01

    Glasses containing mixtures of cations and anions of nominal compositions [Sb2O3]x – [ZnCl2]1?x where x = 0.25, 0.50, 0.75, and 1.00, have been studied by means of neutron diffraction and Raman and Mössbauer spectroscopy. There is preferential bonding within the system with the absence of Sb–Cl bonds. Antimony is found to be threefold coordinated to oxygen, and zinc fourfold coordinated.

  1. Passive Photonic Devices in Glass

    NASA Astrophysics Data System (ADS)

    Eaton, Shane M.; Herman, Peter R.

    Femtosecond laser microfabrication offers the potential for writing passive photonic circuits inside bulk glasses, for use in last-mile photonic networks, sensing, and lab-on-a-chip applications. In this chapter, the fabrication methods for writing low-loss optical waveguides along with waveguide and device characterization techniques are reviewed. The advantages and disadvantages of femtosecond laser writing are analyzed and compared with existing planar lithographic fabrication techniques.

  2. Method for heating, forming and tempering a glass sheet

    DOEpatents

    Boaz, P.T.; Sitzman, G.W.

    1998-10-27

    A method for heating, forming and tempering a glass sheet is disclosed including the steps of heating at least one glass sheet to at least a first predetermined temperature, applying microwave energy to the glass sheet to heat the glass sheet to at least a second predetermined temperature, forming the glass sheet to a predetermined configuration, and cooling an outer surface of the glass sheet to at least a third predetermined temperature to temper the glass sheet. 2 figs.

  3. Cluster glasses of ultrasoft particles

    E-print Network

    Daniele Coslovich; Marco Bernabei; Angel J. Moreno

    2012-09-07

    We present molecular dynamics (MD) simulations results for dense fluids of ultrasoft, fully-penetrable particles. These are a binary mixture and a polydisperse system of particles interacting via the generalized exponential model, which is known to yield cluster crystal phases for the corresponding monodisperse systems. Because of the dispersity in the particle size, the systems investigated in this work do not crystallize and form disordered cluster phases. The clustering transition appears as a smooth crossover to a regime in which particles are mostly located in clusters, isolated particles being infrequent. The analysis of the internal cluster structure reveals microsegregation of the big and small particles, with a strong homo-coordination in the binary mixture. Upon further lowering the temperature below the clustering transition, the motion of the clusters' centers-of-mass slows down dramatically, giving way to a cluster glass transition. In the cluster glass, the diffusivities remain finite and display an activated temperature dependence, indicating that relaxation in the cluster glass occurs via particle hopping in a nearly arrested matrix of clusters. Finally we discuss the influence of the microscopic dynamics on the transport properties by comparing the MD results with Monte Carlo simulations.

  4. Taylor impact of glass rods

    NASA Astrophysics Data System (ADS)

    Willmott, G. R.; Radford, D. D.

    2005-05-01

    The deformation and fracture behavior of soda-lime and borosilicate glass rods was examined during classic and symmetric Taylor impact experiments for impact pressures to 4 and 10GPa, respectively. High-speed photography and piezoresistive gauges were used to measure the failure front velocities in both glasses, and for impact pressures below ˜2GPa the failure front velocity increases rapidly with increasing pressure. As the pressure was increased above ˜3GPa, the failure front velocities asymptotically approached maximum values between the longitudinal and shear wave velocities of each material; at ˜4GPa, the average failure front velocities were 4.7±0.5 and 4.6±0.5mm?s-1 for the soda-lime and borosilicate specimens, respectively. The observed mechanism of failure in these experiments involved continuous pressure-dependent nucleation and growth of microcracks behind the incident wave. As the impact pressure was increased, there was a decrease in the time to failure. The density of cracks within the failed region was material dependent, with the more open-structured borosilicate glass showing a larger fracture density.

  5. Characterization of lithium borate–bismuth tungstate glasses and glass-ceramics by impedance spectroscopy

    Microsoft Academic Search

    G Senthil Murugan; K. B. R Varma

    2001-01-01

    Transparent glasses in the system (1?x)Li2B4O7–xBi2WO6 (0?x?0.35) were prepared via melt quenching technique. Differential thermal analysis was employed to characterize the as-quenched glasses. Glass-ceramics with high optical transparency were obtained by controlled heat-treatment of the glasses at 720 K for 6 h. The amorphous nature of the as-quenched glass and crystallinity of glass-ceramics were confirmed by X-ray powder diffraction studies.

  6. Reactive cluster model of metallic glasses

    SciTech Connect

    Jones, Travis E. [Molecular Theory Group, Colorado School of Mines, Golden, Colorado 80401 (United States) [Molecular Theory Group, Colorado School of Mines, Golden, Colorado 80401 (United States); School of Physics, The University of Sydney, Sydney, New South Wales 2006 (Australia); Miorelli, Jonathan; Eberhart, Mark E. [Molecular Theory Group, Colorado School of Mines, Golden, Colorado 80401 (United States)] [Molecular Theory Group, Colorado School of Mines, Golden, Colorado 80401 (United States)

    2014-02-28

    Though discovered more than a half century ago metallic glasses remain a scientific enigma. Unlike crystalline metals, characterized by short, medium, and long-range order, in metallic glasses short and medium-range order persist, though long-range order is absent. This fact has prompted research to develop structural descriptions of metallic glasses. Among these are cluster-based models that attribute amorphous structure to the existence of clusters that are incommensurate with crystalline periodicity. Not addressed, however, are the chemical factors stabilizing these clusters and promoting their interconnections. We have found that glass formers are characterized by a rich cluster chemistry that above the glass transformation temperature promotes exchange as well as static and vibronic sharing of atoms between clusters. The vibronic mechanism induces correlated motions between neighboring clusters and we hypothesize that the distance over which these motions are correlated mediates metallic glass stability and influences critical cooling rates.

  7. Zircon refractories for glass-melting (review)

    SciTech Connect

    Mel'nikova, I.G.; Nesterova, T.A.; Razdol'skaya, I.V.

    1986-03-01

    The compositions, some of the properties, and the field of application of zircon refractories produced for glass melting in the USSR and abroad are presented. The studies show that the zircon refractories of enhanced purity with a total concentration of coloring impurities of 0.3% are of particular interest in the melting of several grades of special glasses. Data on the glass resitance of zircon refractories to a series of special glasses are presented; the data were obtained using a dynamic method in a comparison with fused quartz. The degree of corrosion was evaluated from the change in the monitored volume of the specimens before and after contact with the glass. It is clear that the corrosion of the zircon refractories both pressed and also obtained by slip casting is significantly less than the corrosion of refractories made from fused quartz. The zircon refractories can reasonably be used for melting a series of glasses with a low concentration of alkalis.

  8. A spin glass that closely resembles the physical glass transition

    NASA Astrophysics Data System (ADS)

    Mansfield, Marc L.

    2003-03-01

    We modify the one-dimensional Ising model in an external field by making the higher-energy spin state P-fold degenerate. The model shows a transition at a finite temperature that becomes first order in the limit of infinite coupling constant. We assume that the model evolves dynamically by single spin flips with Metropolis bias, but with certain forbidden transitions. When the coupling constant is finite but large, the dynamical behavior of the model strongly resembles the physical glass transition, displaying the Kauzmann paradox, the Vogel law, and stretched-exponential relaxation.

  9. Glass Property Data and Models for Estimating High-Level Waste Glass Volume

    SciTech Connect

    Vienna, John D.; Fluegel, Alexander; Kim, Dong-Sang; Hrma, Pavel R.

    2009-10-05

    This report describes recent efforts to develop glass property models that can be used to help estimate the volume of high-level waste (HLW) glass that will result from vitrification of Hanford tank waste. The compositions of acceptable and processable HLW glasses need to be optimized to minimize the waste-form volume and, hence, to save cost. A database of properties and associated compositions for simulated waste glasses was collected for developing property-composition models. This database, although not comprehensive, represents a large fraction of data on waste-glass compositions and properties that were available at the time of this report. Glass property-composition models were fit to subsets of the database for several key glass properties. These models apply to a significantly broader composition space than those previously publised. These models should be considered for interim use in calculating properties of Hanford waste glasses.

  10. Sodium IonSelective Chalcogenide Glass Electrodes

    Microsoft Academic Search

    Yu. G. Vlasov; E. A. Bychkov

    1989-01-01

    Analytical characteristics and sensing mechanism of sodium ion-selective electrodes based on NaCl-Ga2S3-GeS2 glasses have been investigated. Chalcogenide glass electrodes containing 10 mol.% NaCl in the membrane showed near-Nernstian response in the concentration range from 10- to 1 M sodium nitrate solution. These sensors were superior to the conventional pNa oxide glass electrodes in selectivity in the presence of hydrogen ions

  11. Process for preparing improved silvered glass mirrors

    DOEpatents

    Buckwalter, C.Q. Jr.

    1980-01-28

    Glass mirrors having improved weathering properties are prepared by an improvement in the process for making the mirrors. The glass surface after it has been cleaned but before it is silvered, is contacted with a solution of lanthanide rare earths in addition to a sensitization solution of tin or palladium. The addition of the rare earths produces a mirror which has increased resistance to delamination of the silver from the glass surface in the presence of water.

  12. Functionalized glass substrate for microarray analysis

    Microsoft Academic Search

    Rebecca L. DeRosa; Jean A. Cardinale; Ashleigh Cooper

    2007-01-01

    A series of glass treatments were investigated to develop a miniaturized enzyme-linked immunosorbent assay microarray sensor with covalently immobilized antibody. Two glass compositions were photo-hydrolytically treated and functionalized with an amino- or mercapto-silane. Surface characterization was done using contact angle, X-ray photoelectron spectroscopy and atomic force microscopy data. Antibody binding efficiency was statistically compared between treatments and glass compositions.Photo-hydrolytic treatment

  13. Oxide glasses for mid-infrared lasers

    Microsoft Academic Search

    Billy D. O. Richards; Animesh Jha; Gin Jose; Xin Jiang

    2011-01-01

    We present an overview of rare-earth doped heavy metal oxide and oxy-fluoride glasses which show promise as host materials for lasers operating in the 2-5 mum spectral region for medical, military and sensing applications. By engineering glass composition and purity, tellurite and germanate glasses can support transmission up to and beyond 5 mum and can have favourable thermal, mechanical and

  14. Process for preparing improved silvered glass mirrors

    DOEpatents

    Buckwalter, Jr., Charles Q. (Benton, WA)

    1981-01-01

    Glass mirrors having improved weathering properties are prepared by an improvement in the process for making the mirrors. The glass surface after it has been cleaned but before it is silvered, is contacted with a solution of lanthanide rare earths in addition to a sensitization solution of tin or palladium. The addition of the rare earths produces a mirror which has increased resistance to delamination of the silver from the glass surface in the presence of water.

  15. Low-thermal expansion infrared glass ceramics

    Microsoft Academic Search

    Philip Lam

    2009-01-01

    L2 Tech, Inc. is in development of an innovative infrared-transparent glass ceramic material with low-thermal expansion (<0.5 ppm\\/°C) and high thermal-shock resistance to be used as windows and domes for high speed flight. The material is an inorganic, non-porous glass ceramic, characterized by crystalline phases of evenly distributed nano-crystals in a residual glass phase. The major crystalline phase is zirconium

  16. Impact of Phase Separation on Waste Glass Durability

    Microsoft Academic Search

    Jantzen

    1999-01-01

    Phase separation in nuclear waste glasses has an adverse effect on glass durability. Phase separation in glasses generally takes the form of two immiscible glass phases which differ in chemical composition, density, and surface tension. Usually one phase is more soluble than the other. Phase separation complicates modeling of glass durability as a function of composition because the composition of

  17. Impact of Phase Separation on Waste Glass Durability

    Microsoft Academic Search

    Jantzen

    1999-01-01

    Phase separation is shown to have an adverse and unpredictable effect on durability of borosilicate nuclear waste glasses. The glass chemistry and thermal history of the waste glass during solidification in a canister can impact the kinetics of phase separation and thus, the long term durability of a the glass. Although waste glasses contain 15-20 components, many of the components

  18. A EPR Study of Glass Forming Liquids and Liquid Crystals

    Microsoft Academic Search

    Johanan Isaac Spielberg

    1985-01-01

    This study has made use of electron paramagnetic resonance (EPR) probe techniques to explore the liquid phase, the supercooled liquid, the glass transition and the glass phase of isotropic and ordered liquid crystalline organic glass formers. Some surprising insights into supercooled liquid and glass state dynamics were discovered. Studies of an organic glass forming liquid, dibutyl phthalate, show a change

  19. The preparation and properties of glass powder reinforced epoxy resin

    Microsoft Academic Search

    Haifeng Wang; Wenjue Han; Haibing Tian; Yimin Wang

    2005-01-01

    A sealing composites were prepared by mixing superfine glass powder and epoxy resin. The effect of active agent (stearate) on glass powder size and size distribution and the effect of surface treatment of the glass powder on the microstructure and the mechanical properties of glass powder\\/epoxy composites were investigated. Glass powder size was measured using a laser particle size analyzer.

  20. Thermal Expansion and Glass Transition Temperature of Calcium Borate and Calcium Aluminoborate Glasses

    Microsoft Academic Search

    V. P. Klyuev; B. Z. Pevzner

    2003-01-01

    The thermal expansion (the temperature coefficients of linear expansion for solid glasses and the structural temperature coefficients of linear expansion) and the glass transition temperatures are studied for glasses in the CaO–B2O3 and CaO–B2O3–Al2O3 systems. The results obtained are compared with the available data for barium borate and barium aluminoborate glasses. The revealed dependences are interpreted within the concepts of

  1. Electrochromic switchable mirror glass with controllable reflectance

    NASA Astrophysics Data System (ADS)

    Tajima, Kazuki; Hotta, Hiromi; Yamada, Yasusei; Okada, Masahisa; Yoshimura, Kazuki

    2012-02-01

    An electrochromic switchable mirror glass with controllable reflectance was developed. The conditions for fabricating InGaZnO4 (IGZO) thin film, which serves as a transparent conductor, were investigated. The mirror glass with IGZO thin film exhibited multiple colors arising from interference between multilayers. The mirror glass with IGZO thin film fabricated at a working pressure of 0.4 Pa showed high transmittance (63%) in the transparent state and low reflectance (16%) in the reflective state at a wavelength of 670 nm. Moreover, the developed mirror glass had low glare in the reflective state because the reflection of direct, bright light was reduced.

  2. Energy Assessment Protocol for Glass Furnaces

    E-print Network

    Plodinec, M. J.; Kauffman, B. M.; Norton, O. P.; Richards, C.; Connors, J.; Wishnick, D.

    2005-01-01

    of the recommendations arising from use of the protocol are implemented, resulting in cost savings of greater than $200,000 per year. PROJECT OVERVIEW The glass industry is a major energy consumer. Depending on the market sector, a glass furnace heated by oxy...-fuel burners may use from 3.5 to 6 million Btu to melt and refine a ton of glass. The glass industry has generally aimed at achieving energy efficiency through furnace design (e.g., inclusion of heat recovery). However, little attention has been paid...

  3. High-Temperature Viscosity Of Commercial Glasses

    SciTech Connect

    Hrma, Pavel R.; See, Clem A.; Lam, Oanh P.; Minister, Kevin B.

    2005-01-01

    Viscosity was measured for six types of commercial glasses: low-expansion-borosilicate glasses, E glasses, fiberglass wool glasses, TV panel glasses, container glasses, and float glasses. Viscosity data were obtained with rotating spindle viscometers within the temperature range between 900°C and 1550°C; the viscosity varied from 1 Pa?s to 750 Pa?s. Arrhenius coefficients were calculated for individual glasses and linear models were applied to relate them to the mass fractions of 11 major components (SiO2, CaO, Na2O, Al2O3, B2O3, BaO, SrO, K2O, MgO, PbO, and ZrO2) and 12 minor components (Fe2O3, ZnO, Li2O, TiO2, CeO2, F, Sb2O3, Cr2O3, As2O3, MnO2, SO3, and Co3O4). The models are recommended for glasses containing 42 to 84 mass% SiO2 to estimate viscosities or temperatures at a constant viscosity for melts within both the temperature range from 1100°C to 1550°C and viscosity range from 10 to 400 Pa?s.

  4. Raman band intensities of tellurite glasses.

    PubMed

    Plotnichenko, V G; Sokolov, V O; Koltashev, V V; Dianov, E M; Grishin, I A; Churbanov, M F

    2005-05-15

    Raman spectra of TeO2-based glasses doped with WO3, ZnO, GeO2, TiO2, MoO3, and Sb2O3 are measured. The intensity of bands in the Raman spectra of MoO3-TeO2 and MoO3-WO3-TeO2 glasses is shown to be 80-95 times higher than that for silica glass. It is shown that these glasses can be considered as one of the most promising materials for Raman fiber amplifiers. PMID:15943298

  5. Dehydration Processes of Sugar Glasses and Crystals

    NASA Astrophysics Data System (ADS)

    Seo, Jeong-Ah; Kwon, Hyun-Joung; Kim, Hyung Kook; Hwang, Yoon-Hwae

    2006-05-01

    The dehydration processes of sugar glasses and sugar crystals were studied by using Thermogravimetry — Differential Thermal Analysis method. We used three monosaccharide sugars (fructose, galactose, and glucose) and three disaccharide sugars (sucrose, maltose and trehalose). It was found that a trehalose showed different dehydration process compared to the other sugars. The amount of mass reductions in sugar glasses is larger than that in sugar crystals. However, in the case of trehalose, the amount of mass reduction in trehalose glasses is smaller than that in trehalose crystals. It seems to be possible that this unique dehydration property of trehalose glasses maybe relate to the cell protection ability during an anhydrobiosis process.

  6. Research on graphite reinforced glass matrix composites

    NASA Technical Reports Server (NTRS)

    Bacon, J. F.; Prewo, K. M.

    1977-01-01

    The results of research for the origination of graphite-fiber reinforced glass matrix composites are presented. The method selected to form the composites consisted of pulling the graphite fiber through a slurry containing powdered glass, winding up the graphite fiber and the glass it picks up on a drum, drying, cutting into segments, loading the tape segment into a graphite die, and hot pressing. During the course of the work, composites were made with a variety of graphite fibers in a glass matrix.

  7. Nonlinear Optical Properties Of Lanthanum Gallogermanate Glasses

    NASA Astrophysics Data System (ADS)

    Harikuttan, C. Unnithan; Dhanya, I.; Predeep, P.; Jayakumar, S.

    2008-04-01

    The oxide glasses are of important class of materials, especially because of their high transparency in mid IR region. Lanthanum Gallogermanate glass is having greater interest for IR transmission applications due to their long IR cut off wave length in comparison with phosphate, borate or silicate glasses. Various optoelectronic parameters such as Nonlinear Refractive Index (N?), Polarisibity (P). Bandgap Energy(Eg), Susceptibility (?0)are determined for series I glass systems consist of x La2O3-GeO2-0.25 Ga2O3 with x = (0.2,0.25,0.33 & 0.5) and for series II glass systems with 0.25 La2O3-GeO2-x Ga2O3 with x = (0.2,0.25 & 0.5) using the available data. The values obtained are compared with pure 2 glass system. It is observed that with the addition of La2O3 in series I, enhance the non linearity in the glass system while with the addition of glass modifier Ga2O3 in Series II, rcduce the non linearity factor. With proper addition of dopants such as La2O3 or the conditional glass former like Ga2O3, in Lanthanum Gallogermate glassy network, the non linearity factor can be maximized, which will be useful in producing second harmonic generation leading to different optoelectronic applications such as optical modulation, optical rectification and frequency doubling.

  8. Optical properties of cerium doped oxyfluoroborate glass.

    PubMed

    Bahadur, A; Dwivedi, Y; Rai, S B

    2013-06-01

    Cerium doped oxyfluoroborate glasses have been prepared and its spectroscopic properties have been discussed. It is found that the absorption edge shifts towards the lower energy side for the higher concentration of cerium dopant. Optical band gap for these glasses have been calculated and it is found that the number of non-bridging oxygen increases with cerium content. The emission spectra of these glasses have been recorded using UV laser radiations (266 and 355 nm) and it is observed that these glasses show bright blue emission. On the basis of excitation and emission spectra we have reported the existence of at least two different emission centers of Ce(3+)ions. PMID:23583876

  9. Compliant Glass Seals for SOFC Stacks

    SciTech Connect

    Chou, Y. S.; Choi, Jung-Pyung; Xu, Wei; Stephens, Elizabeth V.; Koeppel, Brian J.; Stevenson, Jeffry W.; Lara-Curzio, Edgar

    2014-04-01

    This report summarizes results from experimental and modeling studies performed by participants in the Solid-State Energy Conversion Alliance (SECA) Core Technology Program, which indicate that compliant glass-based seals offer a number of potential advantages over conventional seals based on de-vitrifying glasses, including reduced stresses during stack operation and thermal cycling, and the ability to heal micro-damage induced during thermal cycling. The properties and composition of glasses developed and/or investigated in these studies are reported, along with results from long-term (up to 5,800h) evaluations of seals based on a compliant glass containing ceramic particles or ceramic fibers.

  10. Measurement of Internal Stress in Glass Articles

    SciTech Connect

    Shepard, Chester L.; Cannon, Bret D.; Khaleel, Mohammad A.

    2003-08-01

    We have developed a method for measurement of internal stress in glass articles. The method utilizes Rayleigh-scattered light from a properly polarized laser beam propagating through glass at an oblique angle. This light is imaged with an electronic focal plane array camera. The method is similar to earlier published methods except for the inclusion of an externally controlled phase retarder. The phase retarder allows for the success of the method. The method is suitable for use on flat or curved glass and is applicable over a broad range of residual stresses. Experimental results are provided showing the in-plane stress throughout the thickness of a television glass sample.

  11. Systems approach to nuclear waste glass development

    SciTech Connect

    Jantzen, C M

    1986-01-01

    Development of a host solid for the immobilization of nuclear waste has focused on various vitreous wasteforms. The systems approach requires that parameters affecting product performance and processing be considered simultaneously. Application of the systems approach indicates that borosilicate glasses are, overall, the most suitable glasses for the immobilization of nuclear waste. Phosphate glasses are highly durable; but the glass melts are highly corrosive and the glasses have poor thermal stability and low solubility for many waste components. High-silica glasses have good chemical durability, thermal stability, and mechanical stability, but the associated high melting temperatures increase volatilization of hazardous species in the waste. Borosilicate glasses are chemically durable and are stable both thermally and mechanically. The borosilicate melts are generally less corrosive than commercial glasses, and the melt temperature miimizes excessive volatility of hazardous species. Optimization of borosilicate waste glass formulations has led to their acceptance as the reference nuclear wasteform in the United States, United Kingdom, Belgium, Germany, France, Sweden, Switzerland, and Japan.

  12. Mechanically induced excess enthalpy in inorganic glasses

    NASA Astrophysics Data System (ADS)

    Martin, Birgit; Wondraczek, Lothar; Deubener, Joachim; Yue, Yuanzheng

    2005-03-01

    We show the effect of mechanical quenching on the thermodynamic state of an inorganic glass, i.e., calcium metaphosphate glass, measured using differential scanning calorimetry (DSC). The calcium metaphosphate glasses were isothermally stretched at a given stress; and then cooled slowly. Afterwards the glasses are subject to two runs of DSC scans. We observed a pronounced sub-Tg exotherm on the first up scan, which is due to the release of the mechanically induced excess enthalpy. The exotherm increases with increasing tensile stress.

  13. Rapid prototyping of glass microfluidic chips

    NASA Astrophysics Data System (ADS)

    Kotz, Frederik; Plewa, Klaus; Bauer, Werner; Hanemann, Thomas; Waldbaur, Ansgar; Wilhelm, Elisabeth; Neumann, Christiane; Rapp, Bastian E.

    2015-03-01

    In academia the rapid and flexible creation of microfluidic chips is of great importance for microfluidic research. Besides polymers glass is a very important material especially when high chemical and temperature resistance are required. However, glass structuring is a very hazardous process which is not accessible to most members of the microfluidic community. We therefore sought a new method for the rapid and simple creation of transparent microfluidic glass chips by structuring and sintering amorphous silica suspensions. The whole process from a digital mask layout to a microstructured glass sheet can be done within two days. In this paper we show the applicability of this process to fabricate capillary driven microfluidic systems.

  14. The mechanism of borosilicate glass corrosion revisited

    NASA Astrophysics Data System (ADS)

    Geisler, Thorsten; Nagel, Thorsten; Kilburn, Matt R.; Janssen, Arne; Icenhower, Jonathan P.; Fonseca, Raúl O. C.; Grange, Marion; Nemchin, Alexander A.

    2015-06-01

    Currently accepted mechanistic models describing aqueous corrosion of borosilicate glasses are based on diffusion-controlled hydrolysis, hydration, ion exchange reactions, and subsequent re-condensation of the hydrolyzed glass network, leaving behind a residual hydrated glass or gel layer. Here, we report results of novel oxygen and silicon isotope tracer experiments with ternary Na borosilicate glasses that can be better explained by a process that involves the congruent dissolution of the glass, which is spatially and temporally coupled to the precipitation and growth of an amorphous silica layer at an inwardly moving reaction interface. Such a process is thermodynamically driven by the solubility difference between the glass and amorphous silica, and kinetically controlled by glass dissolution reactions at the reaction front, which, in turn, are controlled by the transport of water and solute elements through the growing corrosion zone. Understanding the coupling of these reactions is the key to understand the formation of laminar or more complex structural and chemical patterns observed in natural corrosion zones of ancient glasses. We suggest that these coupled processes also have to be considered to realistically model the long-term performance of silicate glasses in aqueous environments.

  15. Development and mechanical properties of metal–particulate glass matrix composites from recycled glasses

    Microsoft Academic Search

    E. Bernardo; G. Scarinci; A. Maddalena; S. Hreglich

    2004-01-01

    The great number of glasses available from recycling activity and vitrification treatment of industrial wastes leads to the need for new applications, with the development of new materials, such as low-cost composite materials from a powder technology route. In the present work a variety of recycled glasses is investigated, in order to obtain aluminium reinforced glass matrix composites via cold-pressing

  16. Introduction and Motivation Structural Model for Laminated Glass Beams Conclusions and Outlook of Laminated Glass Structures

    E-print Network

    and Motivation Components of Thin Film Solar Modules back sheet or glass encapsulant electrical conductor thin film layer front glass Reference: Schulze, S.-H.; Pander, M.; Naumenko, K.; Altenbach, H.: AnalysisIntroduction and Motivation Structural Model for Laminated Glass Beams Conclusions and Outlook

  17. Visualization of high-speed fracture phenomena of glass container for effective glass recycling technology development

    Microsoft Academic Search

    H. Sakamoto; Y. Ohbuch; H. Kuramae; Y. Nakamura; E. Nakamachi; S. Itoh

    2011-01-01

    The glass bottle sare widely used as the container of drinks, foods, chemicals and medicines by characteristics of sealing up, storage stability and transparency. After use, many of these glass containers are mechanically crushed and melted in the recycling process. Authors paid attention to the crushing process in this glass recycle and propose a new effective crushing technique by using

  18. Analysis and Research on the Thermal Properties of Energy-efficient Building Glass: A Case Study in PVB Laminated Glass 

    E-print Network

    Chen, Z.; Meng, Q.

    2006-01-01

    A new kind of PVB-laminated glass is introduced as an energy-efficient building glass. Based on tests and calculations of the shading coefficients of flat glass, LOW-E coated glass and PVB-laminated glass with different thickness, their effects...

  19. Syntactic bulk metallic glass foam

    NASA Astrophysics Data System (ADS)

    Brothers, A. H.; Dunand, D. C.

    2004-02-01

    An amorphous metal foam with a bulk density of 3.4 g/cm3 is created by low-pressure melt infiltration of the bulk metallic glass-forming alloy Zr57Nb5Cu15.4Ni12.6Al10 into a bed of hollow carbon microspheres, followed by rapid quenching. The foam consists of a glassy metallic matrix containing ˜60 vol. % of homogenously distributed carbon microspheres, 25-50 ?m in diameter, with small amounts of ZrC at the interface. An amorphous foam with 5 mm diameter showed no measurable loss in thermal stability as compared to the amorphous alloy in bulk form.

  20. Cation coordination in oxychloride glasses

    NASA Astrophysics Data System (ADS)

    Johnson, J. A.; Holland, D.; Bland, J.; Johnson, C. E.; Thomas, M. F.

    2003-02-01

    Glasses containing mixtures of cations and anions of nominal compositions [Sb2O3]x - [ZnCl2]1-x where x = 0.25, 0.50, 0.75, and 1.00, have been studied by means of neutron diffraction and Raman and Mössbauer spectroscopy. There is preferential bonding within the system with the absence of Sb-Cl bonds. Antimony is found to be threefold coordinated to oxygen, and zinc fourfold coordinated. The main contributing species are of the form [Sb(OSb)2(OZn)] and [Zn(ClZn)2(OSb)2].

  1. Geochemistry of Henbury impact glass

    Microsoft Academic Search

    S. R. Taylor; P. Kolbe

    1965-01-01

    Glass due to meteorite impact, found north of the main crater at Henbury, Northern Territory, Australia (24° 35' S; 133° 09' E) has the following composition: SiO2 69.5%; Al2O3 11.37%; FeO 11.45%; MgO 2.18%; CaO 0.61%; Na2O 0.83%; K2O 2.98%; TiO2 0.82%. P 150 ppm; Cr 80 ppm; Li 35 ppm; Ni 3300 ppm; Co 300 ppm; Cu 42 ppm;

  2. Ferromagnetic behavior of metallic glasses

    Microsoft Academic Search

    R. C. Sherwood; E. M. Gyorgy; H. S. Chen; S. D. Ferris; G. Norman; H. J. Leamy

    1975-01-01

    Magnetic properties of metallic glasses in the system (Fe-Co-Ni) 0.75 (P-B-Al)0.25 have been investigated. Samples were made by the roller quenching technique in the form of ribbons 0.002 in. thick and about 0.125 in. wide. Room temperature saturation magnetization, 4piMs, ranged from a high value of 13,500 Gauss for Fe0.75P0.06Al0.03 to essentially zero for Ni0.75P0.16B0.06Al0.03 which exhibits only weak temperature

  3. Ferromagnetic behavior of metallic glasses

    Microsoft Academic Search

    R. C. Sherwood; E. M. Gyorgy; H. S. Chen; S. D. Ferris; G. Norman; H. J. Leamy

    1975-01-01

    Magnetic properties of metallic glasses in the system (Fe-Co-Ni) 0.75 (P-B-Al)0.25 have been investigated. Samples were made by the roller quenching technique in the form of ribbons 0.002 in. thick and about 0.125 in. wide. Room temperature saturation magnetization, 4?Ms, ranged from a high value of 13,500 Gauss for Fe0.75P0.06Al0.03 to essentially zero for Ni0.75P0.16B0.06Al0.03 which exhibits only weak temperature

  4. Dynamic fracture toughness of glass

    NASA Technical Reports Server (NTRS)

    Kobayashi, A. S.; Emery, A. F.; Liaw, B. M.

    1983-01-01

    Experimentally determined dynamic crack propagation histories in wedge-loaded, modified tapered, and rectangular double cantilever beam specimens were used to drive a dynamic finite element code in its generation phase. The resultant dynamic fracture toughness versus crack velocity relation, during the initial crack acceleration phase of these dynamic fracture specimens, was erratic but followed the standard Gamma-shaped curves of brittle polymers and metals during subsequent crack propagation at terminal velocity and crack deceleration phases. The distinct initiation phase of dynamic crack propagation, which was not observed in dynamic fracture of brittle polymer and metal specimens, is attributed to the lower stored energy in the glass specimen.

  5. Control of radioactive waste-glass melters

    SciTech Connect

    Bickford, D.F. (Westinghouse Savannah River Co., Aiken, SC (USA)); Hrma, P. (Case Western Reserve Univ., Cleveland, OH (USA)); Bowan, B.W. II (West Valley Nuclear Services Co., Inc., West Valley, NY (USA))

    1990-01-01

    Slurries of simulated high level radioactive waste and glass formers have been isothermally reacted and analyzed to identify the sequence of the major chemical reactions in waste vitrification, their effect on glass production rate, and the development of leach resistance. Melting rates of waste batches have been increased by the addition of reducing agents (formic acid, sucrose) and nitrates. The rate increases are attributable in part to exothermic reactions which occur at critical stages in the vitrification process. Nitrates must be balanced by adequate reducing agents to avoid the formation of persistent foam, which would destabilize the melting process. The effect of foaming on waste glass production rates is analyzed, and melt rate limitations defined for waste-glass melters, based upon measurable thermophysical properties. Minimum melter residence times required to homogenize glass and assure glass quality are much smaller than those used in current practice. Thus, melter size can be reduced without adversely affecting glass quality. Physical chemistry and localized heat transfer of the waste-glass melting process are examined, to refine the available models for predicting and assuring glass production rate. It is concluded that the size of replacement melters and future waste processing facilities can be significantly decreased if minimum heat transfer requirements for effective melting are met by mechanical agitation. A new class of waste glass melters has been designed, and proof of concept tests completed on simulated High Level Radioactive Waste slurry. Melt rates have exceeded 155 kg m{sup {minus}2} h{sup {minus}1} with slurry feeds (32 lb ft{sup {minus}2} h{sup {minus}1}), and 229 kg kg m{sup {minus}2} h{sup {minus}1} with dry feed (47 lb ft{sup {minus}2} h{sup {minus}1}). This is about 8 times the melt rate possible in conventional waste- glass melters of the same size. 39 refs., 5 figs., 9 tabs.

  6. 49 CFR 230.52 - Water glass valves.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    All water glasses shall be equipped with no more than two valves capable of isolating the water glass from the boiler. They shall also be equipped with a drain valve capable of evacuating the glass when it is so...

  7. Hydrothermal metallurgy for recycling of slag and glass

    NASA Astrophysics Data System (ADS)

    Tanaka, Toshihiro; Yoshikawa, Takeshi; Hirai, Nobumitsu; Katsuyama, Shigeru

    2009-05-01

    The authors have applied hydrothermal reactions to develop recycling processing of slag or glass. As an example, under hydrothermal conditions such as 200 300°C and 30 40MPa with H2O, powders made of glass can be sintered to become solidified glass materials containing about 10mass% H2O. When the glass containing H2O is heated again under normal pressure, the glass expands releasing H2O to make porous microstructure. H2O starts to emit just above the glass transition temperature. Therefore, when we have a glass with low glass transition temperature, we can make low temperature foaming glass. The SiO2-Na2O-B2O3 glass is a candidate to be such a foaming glass. In this paper, we describe our recent trial on the fabrication of the low temperature foaming glass by using hydrothermal reaction.

  8. THEORY OF SUPERCOOLED LIQUIDS AND GLASSES: ENERGY LANDSCAPE AND STATISTICAL

    E-print Network

    Stillinger, Frank

    THEORY OF SUPERCOOLED LIQUIDS AND GLASSES: ENERGY LANDSCAPE AND STATISTICAL GEOMETRY PERSPECTIVES stress and deformation under moderate perturbation. Glasses have played a central role in our dailylives and chemical transformations that take place in fluids. Glasses, moreover, being structurallyliquid

  9. Fiber glass reinforced structural materials for aerospace application

    NASA Technical Reports Server (NTRS)

    Bartlett, D. H.

    1968-01-01

    Evaluation of fiber glass reinforced plastic materials concludes that fiber glass construction is lighter than aluminum alloy construction. Low thermal conductivity and strength makes the fiber glass material useful in cryogenic tank supports.

  10. Glass shell manufacturing in space

    NASA Technical Reports Server (NTRS)

    Downs, R. L.; Ebner, M. A.; Nolen, R. L., Jr.

    1981-01-01

    Highly-uniform, hollow glass spheres (shells), which are used for inertial confinement fusion targets, were formed from metal-organic gel powder feedstock in a vertical furnace. As a result of the rapid pyrolysis caused by the furnace, the gel is transformed to a shell in five distinct stages: (a) surface closure of the porous gel; (b) generation of a closed-cell foam structure in the gel; (c) spheridization of the gel and further expansion of the foam; (d) coalescence of the closed-cell foam to a single-void shell; and (e) fining of the glass shell. The heat transfer from the furnace to the falling gel particle was modeled to determine the effective heating rate of the gel. The model predicts the temperature history for a particle as a function of mass, dimensions, specific heat, and absorptance as well as furnace temperature profile and thermal conductivity of the furnace gas. A model was developed that predicts the gravity-induced degradation of shell concentricity in falling molten shells as a function of shell characteristics and time.

  11. Liquid glass electrodes for nanofluidics

    PubMed Central

    Lee, Sanghyun; An, Ran; Hunt, Alan J.

    2010-01-01

    Nanofluidic devices exploit molecular-level forces and phenomena to increase their density, speed and accuracy1. However, fabrication is challenging because dissimilar materials need to be integrated in three dimensions with nanoscale precision. Here we report a three-dimensional nanoscale liquid glass electrode (NLGE) made from monolithic substrates without conductive materials by femtosecond laser nanomachining. The electrode consists of a nanochannel terminating at a nanoscale glass tip that becomes a conductor in the presence of high electric fields through dielectric breakdown, and returns to an insulator when this field is removed. This reversibility relies on control of nanoampere breakdown currents and extremely fast heat dissipation at nanoscale volumes. We use the NLGE to fabricate a nano-injector that includes an electrokinetic pump, 4 µm across with 0.6 µm channels, and capable of well-controlled flow rates below 1 fL/s. The electrode can be easily integrated into other nanodevices and fluidic systems, including actuators and sensors. PMID:20473300

  12. Bare Bones of Bioactive Glass

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Paul Ducheyne, a principal investigator in the microgravity materials science program and head of the University of Pernsylvania's Center for Bioactive Materials and Tissue Engineering, is leading the trio as they use simulated microgravity to determine the optimal characteristics of tiny glass particles for growing bone tissue. The result could make possible a much broader range of synthetic bone-grafting applications. Even in normal gravity, bioactive glass particles enhance bone growth in laboratory tests with flat tissue cultures. Ducheyne and his team believe that using the bioactive microcarriers in a rotating bioreactor in microgravity will produce improved, three-dimensional tissue cultures. The work is sponsored by NASA's Office of Biological and Physical Research. The bioreactor is managed by the Biotechnology Cell Science Program at NASA's Johnson Space Center (JSC). NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues being cultured in rotating bioreactors by investigators. Credit: NASA and University of Pennsylvania Center for Bioactive Materials and Tissue Engineering.

  13. -Sb Glasses at Low Temperatures

    NASA Astrophysics Data System (ADS)

    Souri, Dariush; Azizpour, Parvin; Zaliani, Hamideh

    2014-09-01

    Semiconducting glasses of the type 40TeO2-(60 - x) V2O5- xSb were prepared by rapid melt quenching and their dc electrical conductivity was measured in the temperature range 180-296 K. For these glassy samples, the dc electrical conductivity ranged from 2.26 × 10-7 S cm-1 to 1.11 × 10-5 S cm-1 at 296 K, indicating the conductivity is enhanced by increasing the V2O5 content. These experimental results could be explained on the basis of different mechanisms (based on polaron-hopping theory) in the different temperature regions. At temperatures above ? D/2 (where ? D is the Debye temperature), the non-adiabatic small polaron hopping (NASPH) model is consistent with the data, whereas at temperatures below ? D/2, a T -1/4 dependence of the conductivity indicative of the variable range hopping (VRH) mechanism is dominant. For all these glasses crossover from SPH to VRH conduction was observed at a characteristic temperature T R ? ? D/2. In this study, the hopping carrier density and carrier mobility were determined at different temperatures. N ( E F), the density of states at (or near) the Fermi level, was also determined from the Mott variables; the results were dependent on V2O5 content.

  14. Microwave evaluation of anisotropy in glass and reflection properties of glass fibers under static load

    SciTech Connect

    Frank, M.; Handjojo, L.; Qaddoumi, N.; Bois, K.; Zoughi, R. [Applied Microwave Nondestructive Testing Laboratory (amntl), Electrical and Computer Engineering Department, Colorado State University, Fort Collins, Colorado 80523-1373 (United States)

    1999-12-02

    Detection and evaluation of glass properties, such as the degree of anisotropy, is an important issue in glass making industry. In addition, a nondestructive means by which glass tensile strength may be correlated to some measurable parameter is also desirable. Microwave nondestructive material characterization techniques have shown great potential for evaluating glass properties. In this study these techniques have been utilized at S- and X-band to determine the potential of evaluating anisotropy and obtain some useful correlation to tensile strength in glass fibers.

  15. Microwave evaluation of anisotropy in glass and reflection properties of glass fibers under static load

    NASA Astrophysics Data System (ADS)

    Frank, M.; Handjojo, L.; Qaddoumi, N.; Bois, K.; Zoughi, R.

    1999-12-01

    Detection and evaluation of glass properties, such as the degree of anisotropy, is an important issue in glass making industry. In addition, a nondestructive means by which glass tensile strength may be correlated to some measurable parameter is also desirable. Microwave nondestructive material characterization techniques have shown great potential for evaluating glass properties. In this study these techniques have been utilized at S- and X-band to determine the potential of evaluating anisotropy and obtain some useful correlation to tensile strength in glass fibers.

  16. Method for heating and forming a glass sheet

    DOEpatents

    Boaz, P.T.

    1997-08-12

    A method for heating and forming a glass sheet includes the steps of heating a glass sheet to at least a first predetermined temperature, applying microwave energy to the glass sheet to heat the glass sheet to at least a second predetermined temperature, cooling an outer surface of the glass sheet to at least a third predetermined temperature and forming the glass sheet using forming rollers to a predetermined configuration. 5 figs.

  17. Direct conversion of halogen-containing wastes to borosilicate glass

    SciTech Connect

    Forsberg, C.W.; Beahm, E.C.; Rudolph, J.C.

    1996-12-09

    Glass has become a preferred waste form worldwide for radioactive wastes: however, there are limitations. Halogen-containing wastes can not be converted to glass because halogens form poor-quality waste glasses. Furthermore, halides in glass melters often form second phases that create operating problems. A new waste vitrification process, the Glass Material Oxidation and dissolution System (GMODS), removes these limitations by converting halogen-containing wastes into borosilicate glass and a secondary, clean, sodium-halide stream.

  18. Crack tip fracture toughness of base glasses for dental restoration glass-ceramics using crack opening displacements.

    PubMed

    Deubener, J; Höland, M; Höland, W; Janakiraman, N; Rheinberger, V M

    2011-10-01

    The critical stress intensity factor, also known as the crack tip toughness K(tip), was determined for three base glasses, which are used in the manufacture of glass-ceramics. The glasses included the base glass for a lithium disilicate glass-ceramic, the base glass for a fluoroapatite glass-ceramic and the base glass for a leucite glass-ceramic. These glass-ceramic are extensively used in the form of biomaterials in restorative dental medicine. The crack tip toughness was established by using crack opening displacement profiles under experimental conditions. The crack was produced by Vickers indentation. The crack tip toughness parameters determined for the three glass-ceramics differed quite significantly. The crack tip parameters of the lithium disilicate base glass and the leucite base glass were higher than that of the fluoroapatite base glass. This last material showed glass-in-glass phase separation. The discussion of the results clearly shows that the droplet glass phase is softer than the glass matrix. Therefore, the authors conclude that a direct relationship exists between the chemical nature of the glasses and the crack tip parameter. PMID:21783138

  19. Glasses Transparent to Ultra-violet Radiation

    Microsoft Academic Search

    A. R. Wood; M. N. Leathwood

    1929-01-01

    DURING the past few months an investigation has been carried out in this laboratory upon the transparency of various ultra-violet transmitting glasses under different conditions. In view of the conflicting statements that have been made concerning the behaviour of these glasses, the results are of considerable interest.

  20. Glass furnance project: April - September 1981

    Microsoft Academic Search

    K. Armstrong; L. M. Klingler

    1981-01-01

    The use of a joule-heated glass furnace, fitted with a Mound-developed offgas system, to reduce the volume of contaminated waste typical of that from nuclear power plants. Preparations, including completion of the offgas scrubbing system and installation of utilities were made for the receipt of the glass melter at Mound. The melter was delivered on September 22, 1981, and assembly

  1. An improved DSC glass sample container technique

    Microsoft Academic Search

    Ivan J. Goldfarb; Hongtu Feng; Jimmie C. Oxley

    1996-01-01

    A simple method has been developed for the use of glass capillaries in DSC. The metal block holder used by previous workers was found to be unnecessary. It was found that different positions of the glass capillary in the cell or long term use of the same baseline do not affect the DSC curves for the same samples. The experimental

  2. Sealing glasses for titanium and titanium alloys

    DOEpatents

    Brow, R.K.; Watkins, R.D.

    1988-01-21

    Glass compositions containing CaO, Al/sub 2/O/sub 3/, B/sub 2/O/sub 3/, SrO and BaO of various combinations of mole % are provided. These compositions are capable of forming stable glass-to-metal seals with titanium and titanium alloys, for use in components such as seals for battery headers.

  3. Testing machine for glass tubing and rod

    Microsoft Academic Search

    R F Proctor

    1927-01-01

    An apparatus is described for testing the strength of glass tubing or rod of ordinary dimensions. The maximum strain in the tube at the moment of fracture is used as a criterion of the strength of the glass. A bending moment is applied to the two ends of the specimen, and the breaking strain is derived from a determination of

  4. Optoacoustic detection of nonlinear absorption in glasses

    Microsoft Academic Search

    Q. Munir; E. Wintner; A. J. Schmidt

    1981-01-01

    We report what we believe to be the first measurement of two photon absorption in a solid using the optoacoustic effect. A number of different glasses were studied. The dispersion of the optoacoustic signal of holmium oxide doped glass is compared with the corresponding absorption spectrum at twice the frequency of the incident light.

  5. Erbium doped glasses for optical fiber amplifiers

    NASA Astrophysics Data System (ADS)

    Wójcik, Joanna; Dorosz, Dominik

    2008-01-01

    The optical and physical properties of three different glass systems were presented. The obtained glasses were doped with 1,75wt% erbium oxide (Er IIO 3). Transmission and luminescence spectra were measured. Absorption spectra were calculated on the basis of transmission spectra. Classic active optical fiber doped with 1,75wt% erbium oxide was fabricated. Attenuation of fabricated optical fiber was measured.

  6. Phase Stability Determinations of DWPF Waste Glasses

    SciTech Connect

    Marra, S.L.

    1999-10-22

    Liquid high-level nuclear waste will be immobilized at the Savannah River Site (SRS) by vitrification in borosilicate glass. To fulfill this requirement, glass samples were heat treated at various times and temperatures. These results will provide guidance to the repository program about conditions to be avoided during shipping, handling and storage of DWPF canistered waste forms.

  7. Combustion Synthesis of Aluminoborate Glass Matrices

    Microsoft Academic Search

    H. C. Yi; J. Y. Guigne; L. A. Whalen; J. J. Moore

    2000-01-01

    Combustion synthesis or self-propagating high-temperature synthesis (SHS) has been used for the first time to produce glass–ceramic materials. The materials produced by the technique have a glassy matrix (aluminoborate glass) and crystalline TiB2 particles, of about 0.5 µm. The combustion characteristics and microstructures of the synthesized materials are presented.

  8. Oxide glasses for mid-infrared lasers

    NASA Astrophysics Data System (ADS)

    Richards, Billy D. O.; Jha, Animesh; Jose, Gin; Jiang, Xin

    2011-06-01

    We present an overview of rare-earth doped heavy metal oxide and oxy-fluoride glasses which show promise as host materials for lasers operating in the 2-5 ?m spectral region for medical, military and sensing applications. By engineering glass composition and purity, tellurite and germanate glasses can support transmission up to and beyond 5 ?m and can have favourable thermal, mechanical and environmental stability compared to fluoride glasses. We discuss techniques for glass purification and water removal for enhanced infrared transmission. By comparing the material properties of the glass, and spectroscopic performance of selected rare-earth dopant ions we can identify promising compositions for fibre and bulk lasers in the mid-infrared. Tellurite glass has recently been demonstrated to be a suitable host material for efficient and compact lasers in the {2 ?m spectral region in fibre and bulk form and the next challenge is to extend the operating range further into the infrared region where silica fibre is not sufficiently transparent, and provide an alternative to fluoride glass and fibre.

  9. Thin transparent films formed from powdered glass

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Glass film less than five mils thick is formed from powdered glass dispersed in an organic liquid, deposited on a substrate, and fused into place. The thin films can be cut and shaped for contact lenses, optical filters and insulating layers.

  10. Chalcogenide glass hollow core photonic crystal fibers

    Microsoft Academic Search

    Frédéric Désévédavy; Gilles Renversez; Johann Troles; Patrick Houizot; Laurent Brilland; Ion Vasilief; Quentin Coulombier; Nicholas Traynor; Frédéric Smektala; Jean-Luc Adam

    2010-01-01

    We report the first hollow core photonic crystal fibers (HC PCF) in chalcogenide glass. To design the required HC PCF profiles for such high index glass, we use both band diagram analysis to define the required photonic bandgap and numerical simulations of finite size HC PCFs to compute the guiding losses. The material losses have also been taken into account

  11. Interpretation of the Thermal Conductivity of Glasses

    Microsoft Academic Search

    Charles Kittel

    1949-01-01

    The thermal conductivity of glasses decreases with decreasing temperature, while the conductivity of crystalline substances increases with decreasing temperature. The behavior of glasses is interpreted in terms of an approximately constant free path for the lattice phonons, so that the conductivity decreases roughly with the specific heat. The value of the phonon mean free path at room temperature is of

  12. The Glass Ceiling Initiative. A Report.

    ERIC Educational Resources Information Center

    Department of Labor, Washington, DC.

    While minorities and women have made considerable gains in entering the workforce in the last few decades, there remains a dearth of minorities and women at management levels. This phenomenon has come to be known as the "glass ceiling." The Department of Labor defines the glass ceiling as those artificial barriers based on attitudinal or…

  13. Rapid Glass Refiner Development Program, Final report

    SciTech Connect

    NONE

    1995-02-20

    A rapid glass refiner (RGR) technology which could be applied to both conventional and advanced class melting systems would significantly enhance the productivity and the competitiveness of the glass industry in the United States. Therefore, Vortec Corporation, with the support of the US Department of Energy (US DOE) under Cooperative Agreement No. DE-FC07-90ID12911, conducted a research and development program for a unique and innovative approach to rapid glass refining. To provide focus for this research effort, container glass was the primary target from among the principal glass types based on its market size and potential for significant energy savings. Container glass products represent the largest segment of the total glass industry accounting for 60% of the tonnage produced and over 40% of the annual energy consumption of 232 trillion Btu/yr. Projections of energy consumption and the market penetration of advanced melting and fining into the container glass industry yield a potential energy savings of 7.9 trillion Btu/yr by the year 2020.

  14. Monitoring and analyzing waste glass compositions

    DOEpatents

    Schumacher, R.F.

    1994-03-01

    A device and method are described for determining the viscosity of a fluid, preferably molten glass. The apparatus and method use the velocity of rising bubbles, preferably helium bubbles, within the molten glass to determine the viscosity of the molten glass. The bubbles are released from a tube positioned below the surface of the molten glass so that the bubbles pass successively between two sets of electrodes, one above the other, that are continuously monitoring the conductivity of the molten glass. The measured conductivity will change as a bubble passes between the electrodes enabling an accurate determination of when a bubble has passed between the electrodes. The velocity of rising bubbles can be determined from the time interval between a change in conductivity of the first electrode pair and the second, upper electrode pair. The velocity of the rise of the bubbles in the glass melt is used in conjunction with other physical characteristics, obtained by known methods, to determine the viscosity of the glass melt fluid and, hence, glass quality. 2 figures.

  15. Preparation of fullerene\\/glass composites

    Microsoft Academic Search

    Benjamin R. Mattes; Duncan W. McBranch; Jeanne M. Robinson; Aaron C. Koskelo; Steven P. Love

    1995-01-01

    Synthesis of fullerene\\/glass composites. A direct method for preparing solid solutions of C.sub.60 in silicon dioxide (SiO.sub.2) glass matrices by means of sol-gel chemistry is described. In order to produce highly concentrated fullerene-sol-gel-composites it is necessary to increase the solubility of these \\

  16. Viscous Glass Sealants for SOFC Applications

    SciTech Connect

    Scott Misture

    2012-09-30

    Two series of silicate glasses that contain gallium as the primary critical component have been identified and optimized for viscous sealing of solid oxide fuel cells operating from 650 to 850°C. Both series of glass sealants crystallize partially upon heat treatment and yield multiphase microstructures that allow viscous flow at temperatures as low as 650°C. A fully amorphous sealant was also developed by isolating, synthesizing and testing a silicate glass of the same composition as the remnant glassy phase in one of the two glass series. Of ~40 glasses tested for longer than 500 hours, a set of 5 glasses has been further tested for up to 1000h in air, wet hydrogen, and against both yttria-stabilized zirconia and aluminized stainless steel. In some cases the testing times reached 2000h. The reactivity testing has provided new insight into the effects of Y, Zr, and Al on bulk and surface crystallization in boro-gallio-silicate glasses, and demonstrated that at least 5 of the newly-developed glasses are viable viscous sealants.

  17. Computer Simulated Growth of Icosahedral Glass

    Microsoft Academic Search

    Y. A. J. Leino; M. M. Salomaa

    1990-01-01

    One possible model for materials displaying classically forbidden symmetry properties (apart from perfect quasicrystals) is the icosahedral glass model. We simulate the random growth of two types of two-dimensional icosahedral glasses consisting of the Penrose tiles, First we restrict the growth with the arrow rules, then we let the structure develop totally freely. The diffraction patterns have a clear five-fold

  18. Optical fiber drawing temperature of fluorogallate glasses

    Microsoft Academic Search

    S. Suriñach; E. Illekova; G. Zhang; M. Poulain; M. D. Baro

    1996-01-01

    The thermal properties and the crystallization behavior of fluorogallate-based glasses were analyzed. The kinetic nature of the glass transition was used to determine the temperature dependence of the viscosity and from it an estimation of the appropriate drawing temperature for an optical fiber was established. The crystallization kinetics were studied by using both isothermal and continuous heating regimes. The temperature

  19. Sealing glasses for titanium and titanium alloys

    DOEpatents

    Brow, Richard K. (Albuquerque, NM); Watkins, Randall D. (Albuquerque, NM)

    1992-01-01

    Glass compositions containing CaO, Al.sub.2 O.sub.3, B.sub.2 O.sub.3, SrO and BaO of various combinations of mole % are provided. These compositions are capable of forming stable glass-to-metal seals with titanium and titanium alloys, for use in components such as seals for battery headers.

  20. Quantitative risk assessment of durable glass fibers.

    PubMed

    Fayerweather, William E; Eastes, Walter; Cereghini, Francesco; Hadley, John G

    2002-06-01

    This article presents a quantitative risk assessment for the theoretical lifetime cancer risk from the manufacture and use of relatively durable synthetic glass fibers. More specifically, we estimate levels of exposure to respirable fibers or fiberlike structures of E-glass and C-glass that, assuming a working lifetime exposure, pose a theoretical lifetime cancer risk of not more than 1 per 100,000. For comparability with other risk assessments we define these levels as nonsignificant exposures. Nonsignificant exposure levels are estimated from (a) the Institute of Occupational Medicine (IOM) chronic rat inhalation bioassay of durable E-glass microfibers, and (b) the Research Consulting Company (RCC) chronic inhalation bioassay of durable refractory ceramic fibers (RCF). Best estimates of nonsignificant E-glass exposure exceed 0.05-0.13 fibers (or shards) per cubic centimeter (cm3) when calculated from the multistage nonthreshold model. Best estimates of nonsignificant C-glass exposure exceed 0.27-0.6 fibers/cm3. Estimates of nonsignificant exposure increase markedly for E- and C-glass when non-linear models are applied and rapidly exceed 1 fiber/cm3. Controlling durable fiber exposures to an 8-h time-weighted average of 0.05 fibers/cm3 will assure that the additional theoretical lifetime risk from working lifetime exposures to these durable fibers or shards is kept below the 1 per 100,000 level. Measured airborne exposures to respirable, durable glass fibers (or shards) in glass fiber manufacturing and fabrication operations were compared with the nonsignificant exposure estimates described. Sampling results for B-sized respirable E-glass fibers at facilities that manufacture or fabricate small-diameter continuous-filament products, from those that manufacture respirable E-glass shards from PERG (process to efficiently recycle glass), from milled fiber operations, and from respirable C-glass shards from Flakeglass operations indicate very low median exposures of 0, 0.0002, 0.007, 0.008, and 0.0025 fibers (or shards)/cm3, respectively using the NIOSH 7400 Method ("B" rules). Durable glass fiber exposures for various applications must be well characterized to ensure that they are kept below nonsignificant levels (e.g., 0.05 fibers/cm3) as defined in this risk assessment. PMID:12119068