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Andrea Knöller, Stefan Kilper, Achim Diem, Marc Widenmeyer, Tomce Runcevski, Robert E Dinnebier, Joachim Bill, Zaklina Burghard
The demand to outperform current technologies pushes scientists to develop novel strategies to enable fabricating materials with exceptional properties. Along this line, lightweight structural materials are of great interest due to their versatile applicability as sensors, catalysts, battery electrodes and acoustic or mechanical dampers. Here we report a strategy to design ultralight (ρ = 3 mg/cm3) and hierarchically structured ceramic scaffolds of macroscopic size. Such scaffolds exhibit mechanical reversibility comparable to that of microscopic metamaterials, leading to a macroscopically remarkable dynamic mechanical performance...
March 20, 2018: Nano Letters
Tomasz Tański, Wiktor Matysiak
The purpose of this paper was to produce SiO₂ and TiO₂ nanowires via the electrospinning process from a polyvinylpyrrolidone (PVP)/Tetraethyl orthosilicate (TEOS)/Titanium (IV) butoxide (TNBT)/dimethylformamide (DMF) and ethanol (EtOH) solution. The as-obtained nanofibers were calcined at temperatures ranging from 400 °C to 600 °C in order to remove the organic phase. The one-dimensional ceramic nanostructures were studied using a scanning electron microscope (SEM) and a transmission electron microscope (TEM) to analyze the influence of the used temperature on the morphology and structures of the obtained ceramic nanomaterials...
March 20, 2018: Nanomaterials
Nanako Sato, Koji Takahashi
The aim of this study was to clarify the effects of micro surface defects introduced by the focused ion beam (FIB) technique on the fracture strength of ceramics. Three-point bending tests on alumina-silicon carbide (Al₂O₃/SiC) ceramic composites containing crack-like surface defects introduced by FIB were carried out. A surface defect with area in the range 19 to 35 µm was introduced at the center of each specimen. Test results showed that the fracture strengths of the FIB-defect specimens depended on area...
March 20, 2018: Materials
Giorgio Gastaldi, Pietro Felice, Valeria Pistilli, Carlo Barausse, Daniela Rita Ippolito, Marco Esposito
PURPOSE: To evaluate whether 5.0 × 5.0 mm dental implants with a novel nanostructured calcium-incorporated titanium surface could be an alternative to implants of at least 10.0 mm long placed in bone augmented with bone substitutes in posterior atrophic jaws. MATERIALS AND METHODS: Forty patients with atrophic posterior (premolar and molar areas) mandibles with 5.0 mm to 7.0 mm bone height above the mandibular canal, and 40 patients with atrophic maxillas with 4...
2018: European Journal of Oral Implantology
Marco Esposito, Rubén Davó, Carlos Marti-Pages, Ada Ferrer-Fuertes, Carlo Barausse, Roberto Pistilli, Daniela Rita Ippolito, Pietro Felice
PURPOSE: To compare the clinical outcome of immediately loaded cross-arch maxillary prostheses supported by zygomatic implants vs conventional implants placed in augmented bone. MATERIALS AND METHODS: A total of 71 edentulous patients with severely atrophic maxillas, who did not have sufficient bone volume to place dental implants or when it was possible to place only two implants in the front area (minimal diameter 3.5 mm and length of 8 mm) and less than 4.0 mm of bone height subantrally, were randomised according to a parallel group design...
2018: European Journal of Oral Implantology
Cuijun Deng, Huiying Zhu, Jiayi Li, Chun Feng, Qingqiang Yao, Liming Wang, Jiang Chang, Chengtie Wu
The cartilage lesion resulting from osteoarthritis (OA) always extends into subchondral bone. It is of great importance for simultaneous regeneration of two tissues of cartilage and subchondral bone. 3D-printed Sr5 (PO4 )2 SiO4 (SPS) bioactive ceramic scaffolds may achieve the aim of regenerating both of cartilage and subchondral bone. We hypothesized that strontium (Sr) and silicon (Si) ions released from SPS scaffolds play a crucial role in osteochondral defect reconstruction. Methods: SPS bioactive ceramic scaffolds were fabricated by a 3D-printing method...
2018: Theranostics
Fei Li, Dabin Lin, Zibin Chen, Zhenxiang Cheng, Jianli Wang, ChunChun Li, Zhuo Xu, Qianwei Huang, Xiaozhou Liao, Long-Qing Chen, Thomas R Shrout, Shujun Zhang
Piezoelectric materials, which respond mechanically to applied electric field and vice versa, are essential for electromechanical transducers. Previous theoretical analyses have shown that high piezoelectricity in perovskite oxides is associated with a flat thermodynamic energy landscape connecting two or more ferroelectric phases. Here, guided by phenomenological theories and phase-field simulations, we propose an alternative design strategy to commonly used morphotropic phase boundaries to further flatten the energy landscape, by judiciously introducing local structural heterogeneity to manipulate interfacial energies (that is, extra interaction energies, such as electrostatic and elastic energies associated with the interfaces)...
March 19, 2018: Nature Materials
L Li, A J Fijneman, J A Kaandorp, J Aizenberg, W L Noorduin
Controlling nucleation and growth is crucial in biological and artificial mineralization and self-assembly processes. The nucleation barrier is determined by the chemistry of the interfaces at which crystallization occurs and local supersaturation. Although chemically tailored substrates and lattice mismatches are routinely used to modify energy landscape at the substrate/nucleus interface and thereby steer heterogeneous nucleation, strategies to combine this with control over local supersaturations have remained virtually unexplored...
March 19, 2018: Proceedings of the National Academy of Sciences of the United States of America
Antti Joonas Koivisto, Kirsten Inga Kling, Ana Sofia Fonseca, Anders Brostrøm Bluhme, Marcel Moreman, Mingzhou Yu, Anna Luisa Costa, Baldi Giovanni, Simona Ortelli, Wouter Fransman, Ulla Vogel, Keld Alstrup Jensen
Nanoscale TiO2 (nTiO2 ) is manufactured in high volumes and is of potential concern in occupational health. Here, we measured workers exposure levels while ceramic honeycombs were dip coated with liquid photoactive nanoparticle suspension and dried with an air blade. The measured nTiO2 concentration levels were used to assess process specific emission rates using a convolution theorem and to calculate inhalation dose rates of deposited nTiO2 particles. Dip coating did not result in detectable release of particles but air blade drying released fine-sized TiO2 and nTiO2 particles...
March 2, 2018: Science of the Total Environment
Majid Rezaei, Mohammad Farhadian, Ali Mohammad Rashidi, Mahshid Saeidipour, Maziar Manshaei, Masih Rezaee
Calcium phosphate bioceramics has recently experienced increased interest in bone reconstruction. Mimicking of natural structure of bone, like the use of nanomaterials, is an attractive approach for generating scaffolds for bone regeneration. The aim of present study was to evaluate the effect of nanonization on the biphasic calcium phosphate (BCP) ceramic in the repair of bone cavities in the canine mandible. A commercial BCP was dry-milled in a high energy planetary ball mill with zirconia balls and container...
March 16, 2018: Journal of Craniofacial Surgery
Weiwei Cao, Xiaoyan Yang, Fengqi Lu, Wenfeng Zhu, Laijun Liu, Xiaojun Kuang, Mathieu Allix
Isovalent substitution of Zr4+ for smaller Ti4+ was performed in the 8-layer twinned hexagonal perovskite (referred to as 8H) tantalate Ba8 Ti3 Ta4 O24 , which stabilizes a 10-layer twinned hexagonal perovskite (referred to as 10H). The formation of the 10H phase occurs at low substitution concentration ( x = 0.1) in Ba8 Zrx Ti3- x Ta4 O24 at 1300 °C and reverts back to the 8H phase upon heating at elevated temperatures. Such a 10H-to-8H phase transformation is suppressed at higher Zr-substitution contents ( x > 0...
March 19, 2018: Inorganic Chemistry
Sung-Hoon Kim, Chan-Jin Park, Lee-Ra Cho, Yoon-Hyuk Huh
STATEMENT OF PROBLEM: Little information is available for the strength of bonding between zirconia and lithium disilicate as affected by surface pretreatment methods. PURPOSE: The purpose of this in vitro study was to investigate the shear bond strength (SBS) between zirconia core and lithium disilicate (LS2 ) veneered ceramic after surface pretreatments. MATERIAL AND METHODS: Fully sintered yttrium oxide partially stabilized tetragonal zirconia (Y-TZP) disk specimens were fabricated from zirconia ceramic materials...
March 15, 2018: Journal of Prosthetic Dentistry
Gulce Alp, Meryem Gulce Subasi, William M Johnston, Burak Yilmaz
STATEMENT OF PROBLEM: The effects of surface treatments and coffee thermocycling on the color and relative translucency of a recently introduced computer-aided design and computer-aided manufacturing (CAD-CAM) monolithic glass-ceramic are unknown. PURPOSE: The purpose of this in vitro study was to evaluate the effect of coffee thermocycling on the color and relative translucency parameter (RTP) of CAD-CAM monolithic glass-ceramics after different surface treatments...
March 15, 2018: Journal of Prosthetic Dentistry
Jianfang Lv, Hongying Yang, Zhenan Jin, Minglei Zhao
In this study, a novel process was developed for extracting lead from the hazardous waste cathode ray tube (CRT) funnel glass and simultaneously producing glass-ceramics. CRT funnel glass was mixed with coal fly ash and subjected to carbon thermal reduction with the addition of CaO. The homogeneous glass melt and reduced metallic lead were quenched in water. Glass-ceramics were produced from the parent glass through an appropriate heat treatment. The optimum carbon loading amount (calculated as the molar ratio of C/PbO), CaO/SiO2 ratio, smelting temperature and holding time for lead recovery were 1...
March 14, 2018: Waste Management
Satoshi Sakoda, Noriko Nakao, Ikuya Watanabe
The aim was to investigate the effect of machining instruments on machinability of dental ceramics. Four dental ceramics, including two zirconia ceramics were machined by three types (SiC, diamond vitrified, and diamond sintered) of wheels with a hand-piece engine and two types (diamond and carbide) of burs with a high-speed air turbine. The machining conditions used were abrading speeds of 10,000 and 15,000 r.p.m. with abrading force of 100 gf for the hand-piece engine, and a pressure of 200 kPa and a cutting force of 80 gf for the air-turbine hand-piece...
March 16, 2018: Journal of Materials Science. Materials in Medicine
A Garbout, M Férid
Considering the features in changing the structure and properties of rare earth titanates pyrochlores, the substituted Dy2 Ti2 O7 may be very attractive for various applications. Effect of Sm and Y substitution on the structural properties of Dy2 Ti2 O7 ceramic was established. These ceramics were prepared by solid-state reaction and characterized by X-ray diffraction and Raman spectroscopy. Both analysis show that YDyTi2 O7 with the pyrochlore structure is obtained after heating at 1400°C, but SmDyTi2 O7 has already formed after sintering at 1200°C...
March 10, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Pinar Cevik, Oguz Eraslan, Kursat Eser, Suleyman Tekeli
PURPOSE: The aim of this study was to evaluate the effect of six different surface conditioning methods on the shear bond strength of ceramic brackets bonded to feldspathic porcelain. MATERIALS AND METHODS: A total of 60 feldspathic porcelain disks were fabricated and divided into six subgroups including 10 specimens in each. Specimens were first treated one of the following surface conditioning methods, namely, 37% phosphoric acid (G-H3PO4), 9.4% hydrofluoric acid (G-HF), grinding with diamond burs (G-Grinding), Nd:YAG laser (G-Nd:YAG), Airborne-particle abrasion (G-Abrasion)...
March 2018: International Journal of Artificial Organs
Daniel Rettenwander, Reinhard Wagner, Andreas Reyer, Maximilian Bonta, Lei Cheng, Marca M Doeff, Andreas Limbeck, Martin Wilkening, Georg Amthauer
The interface stability versus Li represents a major challenge in the development of next-generation all-solid-state batteries (ASSB), which take advantage of the inherently safe ceramic electrolytes. Cubic Li7 La3 Zr2 O12 garnets represent the most promising electrolytes for this technology. The high interfacial impedance versus Li is, however, still a bottleneck toward future devices. Herein, we studied the electrochemical performance of Fe3+ -stabilized Li7 La3 Zr2 O12 (LLZO:Fe) versus Li metal and found a very high total conductivity of 1...
February 22, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Morgane Dolhen, Masayuki Tanaka, Vincent Couderc, Sébastien Chenu, Gaëlle Delaizir, Tomokatsu Hayakawa, Julie Cornette, François Brisset, Maggy Colas, Philippe Thomas, Jean-René Duclère
We report on the laser emission of the polycrystalline ceramic obtained from the full and congruent crystallization of the parent glass 1Nd3+ :75TeO2 -12.5Bi2 O3 -12.5Nb2 O5 composition. In particular, the current work underlines the importance of carefully controlling the heat treatment in order to solely crystallize the Bi0.8 Nb0.8 Te2.4 O8 cubic phase and consequently avoid the formation of the BiNbTe2 O8 orthorhombic phase that would be detrimental for optical purpose. The structure, microstructure and photoluminescence properties of the resulting transparent tellurite ceramics are characterized...
March 15, 2018: Scientific Reports
Stefanie Amend, Roland Frankenberger, Susanne Lücker, Eugen Domann, Norbert Krämer
OBJECTIVES: The present study aimed to establish Lactobacillus casei in a completely automated Streptococcus mutans-based artificial mouth model and to investigate secondary caries inhibiting properties of glass ionomer cements / resin composite groups in vitro. METHODS: Sixty extracted, caries-free human third molars were used for preparation of standardized class-V-cavities. Specimens were restored with a resin-modified (Photac Fil; PF) as well as a conventional glass ionomer cement (Ketac Molar; KM) and one resin composite bonded with and without conduction of etch-and-rinse technique (Prime&Bond NT, Ceram X mono; C+ERT, C)...
March 12, 2018: Dental Materials: Official Publication of the Academy of Dental Materials
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