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Tungsten carbide

Joanna Janiszewska-Olszowska, Robert Tomkowski, Katarzyna Tandecka, Piotr Stepien, Tomasz Szatkiewicz, Katarzyna Sporniak-Tutak, Katarzyna Grocholewicz
BACKGROUND: Termination of fixed orthodontic treatment is associated with bracket debonding and residual adhesive removal. These procedures increase enamel roughness to a degree that should depend on the tool used. Enamel roughening may be associated with bacterial retention and staining. However, a very limited data exists on the alteration of 3D enamel roughness resulting from the use of different tools for orthodontic clean-up. AIMS: 1. To perform a precise assessment of 3D enamel surface roughness resulting from residual adhesive removal following orthodontic debonding molar tubes...
2016: PeerJ
Stephania Caroline Rodolfo Silva, Aion Mangino Messias, Filipe de Oliveira Abi-Rached, Raphael Freitas de Souza, José Maurício Dos Santos Nunes Reis
This study evaluated the accuracy of gypsum casts after different impression techniques and double pouring. Ten patients were selected and for each one it was obtained 5 partial putty/wash impressions with vinyl polysiloxane (VPS) material from teeth #13 to #16 with partial metal stock trays. The following techniques were performed: (1) one-step; two-step relief with: (2) PVC film; (3) slow-speed tungsten carbide bur and scalpel blade, (4) small movements of the tray and (5) without relief-negative control...
2016: PloS One
Gunseli Katirci, R Banu Ermis
BACKGROUND: The aim of this in vitro study was to evaluate the microindentation hardness and chemical composition of residual dentin left at the cavity bottom following removal of carious dentin using the Carisolv chemomechanical and Er:YAG laser caries excavation methods in comparison with the conventional tungsten-carbide bur excavation. METHODS: Sixty-nine extracted permanent teeth with occlusal dentin caries were assigned into three groups according to caries removal technique...
2016: SpringerPlus
Kun Wang, Yi Wang, Yexiang Tong, Zhangweihao Pan, Shuqin Song
Identifying non-precious-metal catalysts with desirable over-all performance for oxygen reduction reaction (ORR) in either acidic or basic media is still a bottleneck. Here, a hybrid material is reported, in which tungsten carbide (WC) and ferberite (FeWO4) are attached to the Fe and N dual-doped ordered mesoporous carbon (WC-FeWO4@FeN-OMC), as a superior performance catalyst for the ORR in either acidic or basic media. In comparison with the frequently used Pt/C ORR catalyst (20 wt.%), our hybrid materials exhibit comparable electrocatalytic activity mainly via a 4e ORR process, better stability, and totally tolerance to methanol in either acidic or basic media...
October 10, 2016: ACS Applied Materials & Interfaces
Alessandro Montedori, Iosief Abraha, Massimiliano Orso, Potito Giuseppe D'Errico, Stefano Pagano, Guido Lombardo
BACKGROUND: Despite considerable improvements in oral health, dental caries continue to be a public health issue. The most frequently used, and universally accepted technique, to remove caries is through mechanical ablation of decayed tissues by means of rotating drills (diamond or tungsten carbide, or both). In the past few decades, the introduction of adhesive filling materials (resin composites) has affected cavity filling procedures by reducing its retention needs, with advantages for dental tissue conservation...
September 26, 2016: Cochrane Database of Systematic Reviews
Klara Midander, Anneli Julander, Jolinde Kettelarij, Carola Lidén
Metal release from materials immersed in artificial sweat can function as a measure of potential skin exposure. Several artificial sweat models exist that, to various degree, mimic realistic conditions. Study objective was to evaluate metal release from previously examined and well characterized materials in two different artificial sweat solutions; a comprehensive sweat model intended for use within research, based on the composition of human sweat; and the artificial sweat, EN1811, intended for testing compliance with the nickel restriction in REACH...
September 21, 2016: Regulatory Toxicology and Pharmacology: RTP
Richard Petersen, Perng-Ru Liu
Three-dimensional (3D)-woven noncrimp fiber-reinforced composite (FRC) was tested for mechanical properties in the two principal directions of the main XY plane and compared to different Computer-Aided-Design/Computer-Aided-Machining (CAD/CAM) Dental Materials. The Dental Materials included ceramic with Vitablock Mark II®, ProCAD®, InCeram® Spinel, InCeram® Alumina and InCeram® Zirconia in addition to a resin-based 3M Corp. Paradigm® particulate-filled composite. Alternate material controls included Coors 300 Alumina Ceramic and a tungsten carbide 22% cobalt cermet...
May 2016: SAMPE Journal
Xingwei Liu, Xiaoyan Song, Haibin Wang, Chao Hou, Xuemei Liu, Xilong Wang
In contrast to the conventional method that obtains a high fracture strength of tungsten carbide-cobalt (WC-Co) cemented carbides by reducing WC grain size to near-nano or nanoscale, a new approach has been developed to achieve ultrahigh fracture strength by strengthening the WC grains through precipitate reinforcement. The cemented carbides were prepared by liquid-state sintering the in situ synthesized WC-Co composite powders with a little excess carbon and pre-milled Cr3C2 particles having different size scales...
October 14, 2016: Nanotechnology
Lei Han, Miao Xu, Yujie Han, You Yu, Shaojun Dong
It is highly desirable and remains a great challenge to develop alternative hydrogen evolution reaction (HER) electrocatalysts that are low-cost, highly efficient, and exhibit excellent stability. In this work, we report the synthesis of tungsten carbide nanocrystallites encapsulated within nitrogen-doped carbon (TCNC) spheres through in situ polymerization of dopamine with metatungstate followed by carburization under an inert atmosphere. During the in situ and confined carburization process, very small tungsten carbide nanocrystallites are obtained and uniformly dispersed in the simultaneously generated carbon matrix...
October 6, 2016: ChemSusChem
Saoirse Dervin, Dionysios D Dionysiou, Suresh C Pillai
Owing to their atomically thin structure, large surface area and mechanical strength, 2D nanoporous materials are considered to be suitable alternatives for existing desalination and water purification membrane materials. Recent progress in the development of nanoporous graphene based materials has generated enormous potential for water purification technologies. Progress in the development of nanoporous graphene and graphene oxide (GO) membranes, the mechanism of graphene molecular sieve action, structural design, hydrophilic nature, mechanical strength and antifouling properties and the principal challenges associated with nanopore generation are discussed in detail...
August 18, 2016: Nanoscale
Ivan A Brezovich, Richard A Popple, Jun Duan, Sui Shen, Xingen Wu, Sidi Benhabib, Mi Huang, Rex A Cardan
Stereotactic radiosurgery (SRS) places great demands on spatial accuracy. Steel BBs used as markers in quality assurance (QA) phantoms are clearly visible in MV and planar kV images, but artifacts compromise cone-beam CT (CBCT) isocenter localization. The purpose of this work was to develop a QA phantom for measuring with sub-mm accuracy isocenter congruence of planar kV, MV, and CBCT imaging systems and to design a practical QA procedure that includes daily Winston-Lutz (WL) tests and does not require computer aid...
2016: Journal of Applied Clinical Medical Physics
Laura Calvillo, Carlos Valero-Vidal, Stefano Agnoli, Hikmet Sezen, Celine Rüdiger, Julia Kunze-Liebhäuser, Gaetano Granozzi
Active and stable non-noble metal materials, able to substitute Pt as catalyst or to reduce the Pt amount, are vitally important for the extended commercialization of energy conversion technologies, such as fuel cells and electrolyzers. Here, we report a fundamental study of nonstoichiometric tungsten carbide (WxC) and its interaction with titanium oxycarbide (TiOxCy) under electrochemical working conditions. In particular, the electrochemical activity and stability of the WxC/TiOxCy system toward the ethanol electrooxidation reaction (EOR) and hydrogen evolution reaction (HER) are investigated...
August 3, 2016: ACS Applied Materials & Interfaces
Kazunori Umeo
A developed alternating current calorimeter for measuring the absolute value of specific heat C of a very small sample under a pressure up to 10 GPa and low temperature below 10 K is described. A Bridgman anvil cell made of tungsten carbide with a top diameter of 3 mm is used. A hollow at the top prevents expansion of the sample space over the anvil top. Two chip resistors, which act as a thermometer and a heater, are mounted on the outer part of a copper-beryllium gasket with a frying pan-like shape. Thus, the thermometer is not pressurized...
June 2016: Review of Scientific Instruments
Mickaël Duranteau, Tony Valier-Brasier, Jean-Marc Conoir, Régis Wunenburger
The effective velocity and attenuation of longitudinal waves through random dispersions of rigid, tungsten-carbide beads in an elastic matrix made of epoxy resin in the range of beads volume fraction 2%-10% are determined experimentally. The multiple scattering model proposed by Luppé, Conoir, and Norris [J. Acoust. Soc. Am. 131(2), 1113-1120 (2012)], which fully takes into account the elastic nature of the matrix and the associated mode conversions, accurately describes the measurements. Theoretical calculations show that the rigid particles display a local, dipolar resonance which shares several features with Minnaert resonance of bubbly liquids and with the dipolar resonance of core-shell particles...
June 2016: Journal of the Acoustical Society of America
Umut Cakan, Murat Cakan, Cagri Delilbasi
PURPOSE: The aim of this investigation was to measure the temperature increase due to heat transferred to the implant-bone interface when the abutment screw channel is accessed or a metal-ceramic crown is sectioned buccally with diamond or tungsten carbide bur using an air rotor, with or without irrigation. MATERIALS AND METHODS: Cobalt-chromium copings were cemented onto straight titanium abutments. The temperature changes during removal of the copings were recorded over a period of 1 minute...
May 2016: International Journal of Prosthodontics
Assem Hedayat, Nicole Nagy, Garnet Packota, Judy Monteith, Darcy Allen, Tomasz Wysokinski, Ning Zhu
Dental burs are used extensively in dentistry to mechanically prepare tooth structures for restorations (fillings), yet little has been reported on the bur debris left behind in the teeth, and whether it poses potential health risks to patients. Here it is aimed to image dental bur debris under dental fillings, and allude to the potential health hazards that can be caused by this debris when left in direct contact with the biological surroundings, specifically when the debris is made of a non-biocompatible material...
May 2016: Journal of Synchrotron Radiation
Tallita Foglietto da Silva, Murilo Pereira de Melo, Jefferson Ricardo Pereira, Wilton Mitsunari Takeshita, Bruno Mafra Ceribelli, Lilian Cristina Vessoni Iwaki
STATEMENT OF PROBLEM: Different instruments have been developed to improve crown finish lines after conventional preparation with diamond rotary instruments. However, more evidence on the effectiveness of these instruments is required. PURPOSE OF STUDY: The purpose of this in vitro study was to assess the effectiveness of 4 different instruments used for cervical margin finishing in regard to the external line angle (ELA). MATERIAL AND METHODS: Forty-eight freshly extracted third molar teeth with similar dimensions were conventionally prepared for crowns and randomly allocated into 4 groups (n=12) according to the finishing instrument: hand trimmer (HT), tungsten carbide bur (TCB), ultrasonic instrument (UI), and diamond rotary instrument (DRI) mounted in a contra angle handpiece with reduced speed...
September 2016: Journal of Prosthetic Dentistry
Alexandre Moser, Aristomenis Exadaktylos, Alexander Radke
Introduction. Destructive or nondestructive procedures may be used to remove rings from injured fingers. Because of their hardness, tungsten carbide rings present special problems. Case Presentation. The patient was a 33-year-old woman, two weeks before delivery, with a swollen and reddened ring finger. It was decided to remove a tungsten carbide ring from her ring finger. This was achieved by shattering the ring with locking pliers. The patient's ring finger recovered fully.
2016: Case Reports in Emergency Medicine
Andras Khoor, Anja C Roden, Thomas V Colby, Victor L Roggli, Mohamed Elrefaei, Francisco Alvarez, David B Erasmus, Jorge M Mallea, David L Murray, Cesar A Keller
Giant cell interstitial pneumonia is a rare lung disease and is considered pathognomonic for hard metal lung disease, although some cases with no apparent hard metal (tungsten carbide cobalt) exposure have been reported. We aimed to explore the association between giant cell interstitial pneumonia and hard metal exposure. Surgical pathology files from 2001 to 2004 were searched for explanted lungs with the histopathologic diagnosis of giant cell interstitial pneumonia, and we reviewed the associated clinical histories...
April 2016: Human Pathology
Thomas A Sporn, Victor L Roggli
Exposure to hard metal (tungsten carbide) dust is a rare cause of interstitial lung disease. Although most cases have a distinctive morphology known as giant cell interstitial pneumonitis, other patterns have been described as well. In such cases, the true nature of the interstitial process may be difficult to recognize. We present a case with unusual morphological features in which analytical scanning electron microscopy (SEM) was used to detect the presence of tungsten as well as other metallic particles...
May 2016: Ultrastructural Pathology
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