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glass ceramic

D Li, X C Li, Z Z Zhang, S F Zhang, L He
Post-crystallization annealing above the Tg was applied to a lithium disilicate glass-ceramic with microstructure consisting of glassy matrix and rod-like lithium disilicate crystals, effect of the annealing on the mechanical behavior was investigated. Flexural strength and VIF toughness of the glass-ceramic unexpectedly decreased after the annealing. The mechanical behavior variation was understood based on residual micro-stress analysis. Coefficient of thermal expansion for the glassy matrix presented a tendency to increase after the annealing, which would enlarge the thermal expansion mismatch between the glassy matrix and the lithium disilicate crystals...
November 3, 2017: Journal of the Mechanical Behavior of Biomedical Materials
Pietro Ausiello, Stefano Ciaramella, Massimo Martorelli, Antonio Lanzotti, Antonio Gloria, David C Watts
OBJECTIVES: To investigate the influence of specific resin-composite, glass ceramic and glass ionomer cement (GIC) material combinations in a "multi-layer" technique to replace enamel and dentin in class II mesio-occlusal-distal (MOD) dental restorations using 3D-Finite Element Analysis (FEA). METHODS: Four 3D-FE models (A-D) of teeth, adhesively restored with different filling materials, were created and analyzed in comparison with a 3D model (E) of a sound lower molar...
November 8, 2017: Dental Materials: Official Publication of the Academy of Dental Materials
Qunhuo Liu, Ying Tian, Caizhi Wang, Feifei Huang, Xufeng Jing, Junjie Zhang, Xianghua Zhang, Shiqing Xu
Transparent oxyfluoride glass and glass ceramics doped with 0.5% Ho(3+) and 1.0% Yb(3+) ions have been prepared. X-ray diffraction and transmission electron microscopy demonstrated the formation of NaYF4 nanocrystals during the heat treatment process. Raman spectra indicated the variation of glass structure brought about by the formation of NaYF4 nanocrystals. XRD curves and Judd-Ofelt intensity parameters confirmed the incorporation of Ho(3+) into NaYF4 nanocrystals. Significantly enhanced visible upconversion and 2...
November 6, 2017: Physical Chemistry Chemical Physics: PCCP
Kwiyong Kim, Seung Jong Lee, Dong-Yeon Kim, Chung-Yul Yoo, Jang Wook Choi, Jong-Nam Kim, Youngmin Woo, Hyung Chul Yoon, Jong-In Han
Lithium-mediated reduction of dinitrogen is a promising way to evade electron-stealing hydrogen evolution, a critical challenge which limits faradaic efficiency (FE) and thus hinders the success of traditional protic solvent-based ammonia electro-synthesis. In this study, we propose a viable illustration to realize the lithium-mediated pathway using lithium-ion conducting glass ceramic, which can be divided into three successive steps: (i) lithium deposition, (ii) nitridation, and (iii) ammonia formation. Ammonia was successfully synthesized from molecular nitrogen and water, yielding a maximum FE of 52...
November 3, 2017: ChemSusChem
Michal Šyc, Aneta Krausová, Petra Kameníková, Radovan Šomplák, Martin Pavlas, Boleslav Zach, Michael Pohořelý, Karel Svoboda, Miroslav Punčochář
Bottom ash (BA) from waste-to-energy (WtE) plants contains valuable components, particularly ferrous (Fe) and non-ferrous (NFe) metals, which can be recovered. To assess the resource recovery potential of BA in the Czech Republic, it was necessary to obtain its detailed material composition. This paper presents the material composition of BA samples from all three Czech WtE plants. It was found that the BA contained 9.2-22.7% glass, 1.8-5.1% ceramics and porcelain, 0.2-1.0% unburnt organic matter, 10.2-16.3% magnetic fraction, 6...
November 2, 2017: Waste Management
Mohamed Hassan, Ahmed S Afify, Mohamed Ataalla, Daniel Milanese, Jean-Marc Tulliani
In this study, a glass ceramic with a nominal composition 58ZnO:4Bi₂O₃:4WO₃:33.3B₂O₃ was synthesized by melt quenching technique. A gas sensor was then manufactured using a ZnO sol-gel phase as a permanent binder of the glass-ceramic to an alumina substrate having interdigitated electrodes. The film sensitivity towards humidity, NH₃, H₂ and NO₂ was studied at different temperatures. X-ray diffraction technique (XRD), field emission- scanning electron microscopy (FE-SEM) and differential thermal analysis (DTA) were used to characterize the prepared material...
November 3, 2017: Sensors
Lucia K Zaugg, Simon Meyer, Nadja Rohr, Isabella Zehnder, Nicola U Zitzmann
OBJECTIVES: To investigate the fracture behavior and marginal gap region of CAD/CAM fabricated lithium disilicate (L) and zirconium dioxide (Z) crowns using palatal venting (PV), pre-cementation with custom analogs (CA), or conventional cementation technique (SP) with adhesive cement (A) or resin-modified glass ionomer cement (B). MATERIAL AND METHODS: Twelve groups (n = 6) were set according to material (L, Z), cement (A, B), and technique (PV, CA, SP). Specimens were thermo-mechanical aged (TML), loaded until fracture (LF) and fracture patterns recorded...
October 31, 2017: Clinical Oral Implants Research
Mohammed Abu Helal, Zhigang Wang
PURPOSE: To compare equivalent and contact stresses in a mandibular molar restored by all-ceramic crowns through two methods: ceramic endocrowns and ceramic crowns supported by fiber-reinforced composite (FRC) posts and core, by using 3D finite element analysis during normal masticatory load. MATERIALS AND METHODS: Three 3D models of a mandibular first molar were made and labeled as such: intact molar with no restoration (A); ceramic endocrown-restored molar (B); ceramic crown supported by FRC posts and core restored molar (C)...
October 25, 2017: Journal of Prosthodontics: Official Journal of the American College of Prosthodontists
Monika Machoy, Julia Seeliger, Liliana Szyszka-Sommerfeld, Robert Koprowski, Tomasz Gedrange, Krzysztof Woźniak
Optical coherence tomography provides sections of tissues in a noncontact and noninvasive manner. The device measures the time delay and intensity of the light scattered or reflected from biological tissues, which results in tomographic imaging of their internal structure. This is achieved by scanning tissues at a resolution ranging from 1 to 15 μm. OCT enables real-time in situ imaging of tissues without the need for biopsy, histological procedures, or the use of X-rays, so it can be used in many fields of medicine...
2017: Journal of Healthcare Engineering
Dragoljub Vrankovic, Magdalena Graczyk-Zajac, Constanze Kalcher, Jochen Rohrer, Malin Becker, Christina Stabler, Grzegorz Trykowski, Karsten Albe, Ralf Riedel
We demonstrate a cost-effective synthesis route that provides Si-based anode materials with capacities between 2000 and 3000 mAh·gSi(-1) (400 and 600 mAh·gcomposite(-1)), Coulombic efficiencies above 99.5%, and almost 100% capacity retention over more than 100 cycles. The Si-based composite is prepared from highly porous silicon (obtained by reduction of silica) by encapsulation in an organic carbon and polymer-derived silicon oxycarbide (C/SiOC) matrix. Molecular dynamics simulations show that the highly porous silicon morphology delivers free volume for the accommodation of strain leading to no macroscopic changes during initial Li-Si alloying...
October 27, 2017: ACS Nano
Tamer A Hamza, Rana M Sherif
PURPOSE: To compare the fracture resistance of monolithic reinforced glass-ceramic restorations with bilayer zirconia-based restorations. MATERIALS AND METHODS: Fifteen ceramic crowns were fabricated on epoxy dies duplicated from a stainless steel master die. They were divided into 3 equal groups (n = 5) according to the type of ceramic material used: group I, monolithic lithium disilicate (IPS e.max CAD), group V, monolithic zirconia-reinforced lithium silicate (Vita Suprinity), and group B (bilayered zirconia substructure with veneering ceramic)...
October 18, 2017: Journal of Prosthodontics: Official Journal of the American College of Prosthodontists
Lucia K Zaugg, Isabella Zehnder, Nadja Rohr, Jens Fischer, Nicola U Zitzmann
OBJECTIVES: The purpose of this study was to analyze the cement excess produced when cementing CAD/CAM-fabricated lithium disilicate (L) or zirconium dioxide (Z) crowns using adhesive cement (A) or resin-modified glass ionomer cement (B). Three different cementation techniques were applied: palatal venting (PV), pre-cementation with custom analogs (CA), and conventional standard procedure (SP). MATERIALS AND METHODS: Seventy-two crowns (36 each material) were assigned to 12 experimental groups depending on the restoration material (L, Z), type of cement (A, B), and cementation technique (PV, CA, SP)...
October 17, 2017: Clinical Oral Implants Research
Isao Ito, Alissa Silva, Takuma Nakamura, Yohei Kobayashi
We describe a CW laser stabilized to a low thermal expansion ceramic cavity which has a lower frequency drift rate than cavities based on ultralow-expansion glass (ULE), which are widely used as optical references. Two identical optical cavities with spacers of different material, ceramic and ULE, were assembled and the optical frequencies locked to each of these cavities were compared. The optical frequency drifts of both CW lasers were measured to within a precision of 10(-11) in one second over the course of one year...
October 16, 2017: Optics Express
Juan Carlos Forero, Eduardo Roa, Juan G Reyes, Cristian Acevedo, Nelson Osses
Ceramic and metallic nanoparticles can improve the mechanical and biological properties of polymeric scaffolds for bone tissue engineering (BTE). In this work, nanohydroxyapatite (nHAp) and nano-copper-zinc alloy (nCuZn) were added to a chitosan/gelatin (Ch/G) scaffold in order to investigate the effects on morphological, physical, and biocompatibility properties. Scaffolds were fabricated by a freeze-drying technique using different pre-freezing temperatures. Microstructure and morphology were studied by scanning electron microscopy (SEM), glass transition (Tg) was studied using differential scanning calorimetry (DSC), cell growth was estimated by MTT assay, and biocompatibility was examined in vitro and in vivo by histochemistry analyses...
October 17, 2017: Materials
Y Zhang, B R Lawn
Zirconias, the strongest of the dental ceramics, are increasingly being fabricated in monolithic form for a range of clinical applications. Y-TZP (yttria-stabilized tetragonal zirconia polycrystal) is the most widely used variant. However, current Y-TZP ceramics on the market lack the aesthetics of competitive glass-ceramics and are therefore somewhat restricted in the anterior region. This article reviews the progressive development of currently available and next-generation zirconias, representing a concerted drive toward greater translucency while preserving adequate strength and toughness...
October 1, 2017: Journal of Dental Research
Dmitrii A Burdin, Nikolai A Ekonomov, Dmitrii V Chashin, Leonid Y Fetisov, Yuri K Fetisov, Mikhail Shamonin
The dependence of the resonant direct magnetoelectric effect on temperature is studied experimentally in planar composite structures. Samples of rectangular shapes with dimensions of 5 mm × 20 mm employed ferromagnetic layers of either an amorphous (metallic glass) alloy or nickel with a thickness of 20-200 μm and piezoelectric layers of single crystalline langatate material or lead zirconate titanate piezoelectric ceramics with a thickness of 500 μm. The temperature of the samples was varied in a range between 120 and 390 K by blowing a gaseous nitrogen stream around them...
October 16, 2017: Materials
Paul de Kok, Gabriel K R Pereira, Sara Fraga, Niek de Jager, Andressa B Venturini, Cornelis J Kleverlaan
OBJECTIVE: To evaluate the effect of internal roughness and bonding on the load to failure and structural reliability (Weibull analysis) of a lithium disilicate-based glass ceramic under different testing scenarios. METHODS: IPS e.max CAD blocks (Ivoclar Vivadent AG) were shaped into cylinders (N=100), crystalized according to the manufacturer's instructions, and randomly assigned into two surface conditions: (1) polished surface (600-grit SiC polish papers), and (2) a roughened surface (air-abrasion with 50μm Al2O3)...
October 9, 2017: Dental Materials: Official Publication of the Academy of Dental Materials
K L Hon, C K Fung, A Kc Leung
Childhood lead poisoning is a major public health concern in many countries. In 2015, the Hong Kong SAR Government and its citizens faced a major public health crisis due to the presence of lead in the drinking water of a number of public housing estates. Fortunately, no child was diagnosed with lead poisoning that required treatment with chelation. Lead is a ubiquitous, naturally occurring material that exists in air, dust, soil, and water. It is also widely present in industrial products including petrol, paints, ceramics, food cans, candies, cosmetics, traditional remedies, batteries, solder, stained glass, crystal vessels, ammunition, ceramic glazes, jewelry, and toys...
October 13, 2017: Hong Kong Medical Journal, Xianggang Yi Xue za Zhi
Minh D Nguyen, Evert P Houwman, Guus Rijnders
Thin films of PbZr0.52Ti0.48O3 (PZT) with largely detached columnar grains, deposited by pulsed laser deposition (PLD) on amorphous glass substrates covered with Ca2Nb3O10 nanosheets as growth template and using LaNiO3 electrode layers, are shown to exhibit very high unipolar piezoelectric strain and ultra-low strain hysteresis. The observed increase of the piezoelectric coefficient with increasing film thickness is attributed to the reduction of clamping, because of the increasingly less dense columnar microstructure (more separation between the grains) with across the film thickness...
October 10, 2017: Scientific Reports
Renan Belli, Michael Wendler, Anselm Petschelt, Ulrich Lohbauer
Here we use the 3-point bending with eccentric notch test (3-PBEN) to investigate the fracture behavior of a pressable and a CAD/CAM lithium disilicate (LS2) glass-ceramics under combined mode-I and mode-II loading. The effect of the bulk texturization in the beams of the pressable LS2 is made visible through the fracture trajectory following the most energetically favorable path dictated by the crystallite alignment. The CAD/CAM LS2 shows an isotropic fracture mode but increasing fracture energy with mode-II contribution, similar to the pressable variant...
October 7, 2017: Dental Materials: Official Publication of the Academy of Dental Materials
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