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Tungsten carbide

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https://www.readbyqxmd.com/read/29735199/a-pilot-study-on-the-effects-of-direct-contact-of-two-different-surgical-burs-on-the-cadaveric-lingual-nerve
#1
S M Al-Amery, W C Ngeow, P Nambiar, M Naidu
The lingual guttering technique for third molar surgery carries the risk of injury to the lingual nerve if the surgical bur comes into direct contact with it. This study investigated the extent of nerve injury caused by two different burs, a tungsten carbide bur and the Dentium implant bur; the latter is designed to be soft tissue friendly. This study also examined whether ultrasound and magnetic resonance imaging are able to detect any injury inflicted. This cadaveric research involved subjecting 12 lingual nerves to the drilling effect of two different burs at two different speeds...
May 4, 2018: International Journal of Oral and Maxillofacial Surgery
https://www.readbyqxmd.com/read/29721226/enamel-evaluation-by-scanning-electron-microscopy-after-debonding-brackets-and-removal-of-adhesive-remnants
#2
Dikson Claudino, Milton-Carlos Kuga, Lauriê Belizário, Jefferson-Ricardo Pereira
Background: The bonding of accessories in the dental crown during the orthodontic treatment creates microporosities, thus promoting micromechanical retention of the adhesive to the enamel structure. After debonding brackets, at the end of the active orthodontic treatment, a certain amount of adhesive remnants must be mechanically removed from the enamel. The objective of this study was to compare, by means of scanning electron microscopy, three different methods to remove the adhesive remnants after orthodontic bracket removal...
March 2018: Journal of Clinical and Experimental Dentistry
https://www.readbyqxmd.com/read/29700538/highly-negative-poisson-s-ratio-in-a-flexible-two-dimensional-tungsten-carbide-monolayer
#3
Donghai Wu, Shuaiwei Wang, Shouren Zhang, Jinyun Yuan, Baocheng Yang, Houyang Chen
Auxetic materials have numerous promising engineering applications such as fracture resistance and energy storage due to their negative Poisson's ratios (NPRs). However, compared to materials possessing positive Poisson's ratios (PPRs), auxetic materials are rare. In this paper, by employing first principles calculations, we found a high NPR two-dimensional (2D) material, tungsten carbide (W2C), in the transition metal carbides (MXenes). Our results of the relatively moderate Young's modulus and fracture strength as well as the critical strain showed that the 2D monolayer W2C is an extraordinary flexible material...
April 27, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29696445/resistance-to-vertical-root-fracture-of-apicoected-teeth-using-different-devices-during-two-root-canal-irrigation-procedures
#4
Ferhat Ayrancı, Leyla Benan Ayrancı, Alper Özdoğan, Serkan Özkan, Mutlunur Önder Peker, Mutan Hamdi Aras
The aim of the present work was to measure the fracture resistance of endodontically treated teeth that were apicoected with different procedures. Seventy-two extracted human maxillary anterior teeth were included in this study. The specimens were randomly assigned to three main groups according to the apical surgery procedures and then two subgroups according to the irrigation protocols during root canal treatment and total of six groups were obtained (n = 12). Group 1: served as a control and apical surgery process was not performed in this group...
April 26, 2018: Lasers in Medical Science
https://www.readbyqxmd.com/read/29691663/tooth-sectioning-for-coronectomy-how-to-perform
#5
József Szalma, László Vajta, Lajos Olasz, Edina Lempel
OBJECTIVES: The aim of this study was to determine the increase in heat production, preparation time, and cutting surface quality of conventional, high-speed rotating instruments and piezoelectric preparation for coronectomy procedures. MATERIALS AND METHODS: One hundred intact extracted molars were sectioned horizontally, sub-totally, 1 mm under the cemento-enamel line with five methods: (1) tungsten carbide torpedo (TcT), (2) round (TcR) drills using a conventional speed surgical straight handpiece (< 40,000 min-1 ), (3) tungsten carbide fissure (TcF), (4) diamond torpedo (DT) drills using a surgical high-speed, contra-angle handpiece (~ 120,000 min-1 ), or (5) a saw-like piezoelectric tip (PT)...
April 24, 2018: Clinical Oral Investigations
https://www.readbyqxmd.com/read/29669483/study-of-lung-toxicity-in-rats-exposed-to-silica-powder-with-different-hard-metal-constituents
#6
Zhansai Zhang, Yanfang Zhao, Gang Chen, Ruoming Li, Jun Yang, Daoyuan Sun
The objective of this study was to assess the lung toxicity induced by the inhalation of different hard metal constituents and silica powder and screen for potential toxicity biomarkers. Rats were randomly divided into saline, cobalt, tungsten carbide, silica, and hard metal (HM) groups and were administered a single 10-mg dose of the respective treatments. After 8 weeks, the lung tissue structure in the HM group was deformed, numerous nucleated giant and epithelial-like cells appeared in the stroma, and the computed tomography scanning images appeared abnormal...
January 1, 2018: Toxicology and Industrial Health
https://www.readbyqxmd.com/read/29668800/activity-and-stability-of-dispersed-multi-metallic-pt-based-catalysts-for-co-tolerance-in-proton-exchange-membrane-fuel-cell-anodes
#7
Ayaz Hassan, Edson A Ticianelli
Studies aiming at improving the activity and stability of dispersed W and Mo containing Pt catalysts for the CO tolerance in proton exchange membrane fuel cell (PEMFC) anodes are revised for the following catalyst systems: (1) a carbon supported PtMo electrocatalyst submitted to heat treatments; (2) Pt and PtMo nanoparticles deposited on carbon-supported molybdenum carbides (Mo2C/C); (3) ternary and quaternary materials formed by PtMoFe/C, PtMoRu/C and PtMoRuFe/C and; (4) Pt nanoparticles supported on tungsten carbide/carbon catalysts and its parallel evaluation with carbon supported PtW catalyst...
April 16, 2018: Anais da Academia Brasileira de Ciências
https://www.readbyqxmd.com/read/29657525/effect-of-different-surface-finishing-polishing-procedures-on-color-stability-of-esthetic-restorative-materials-a-spectrophotometric-evaluation
#8
Riccardo Beltrami, Matteo Ceci, Gabriele De Pani, Lodovico Vialba, Ricaldone Federico, Claudio Poggio, Marco Colombo
Objective: To evaluate the color stability of different esthetic restorative materials after surface finishing/polishing with different procedures. Materials and Methods: All materials were polymerized into silicone rubber rings to obtain specimens identical in size. Samples were randomly assigned into four groups (10 specimens of each composite for each group), and they were finished with different procedures: Control group (Group 1), three or two polishers interspersed with diamond grit (Groups 3 and 2, respectively), and one tungsten carbide bur + one polisher interspersed with diamond grit (Group 4)...
January 2018: European Journal of Dentistry
https://www.readbyqxmd.com/read/29652569/efficacy-of-various-pretreatments-on-the-bond-strength-of-denture-teeth-to-denture-base-resins
#9
Fatih Sari, Ozlem Ustun, Omer Kirmali
OBJECTIVE: This in vitro study evaluated the shear bond strength (SBS) of heat-cured denture base resin (PMMA) to acrylic resin teeth treated with different pretreatments, especially laser irradiation of different powers (1-4 W). MATERIALS AND METHODS: The acrylic resin teeth were separated into seven groups (n = 10) for the following different pretreatments: control group (no surface treatment) (G1), grinding with a tungsten carbide bur (G2), sandblasting (G3), and erbium, chromium: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) laser irradiation at 1 W, 2 W, 3 W, 4 W output powers in (G4-7), respectively...
April 2018: Photomedicine and Laser Surgery
https://www.readbyqxmd.com/read/29614395/on-the-detection-of-multiple-events-in-atom-probe-tomography
#10
Zirong Peng, Francois Vurpillot, Pyuck-Pa Choi, Yujiao Li, Dierk Raabe, Baptiste Gault
In atom probe tomography (APT), multiple events can arise as a consequence of e.g. correlated field evaporation and molecular ion dissociation. They represent challenging cases for single-particle detectors and can cause compositional as well as spatial inaccuracies. Here, two state-of-the-art atom probe microscopes (Cameca LEAP 5000 XS and 5000 XR) were used to investigate cemented tungsten carbide, which exhibits high amounts of multiple events. By advanced data analysis methods, the natural character of the multiple events, as well as the performance of the APT detectors, are assessed...
March 26, 2018: Ultramicroscopy
https://www.readbyqxmd.com/read/29604733/stress-distribution-and-pressure-bearing-capacity-of-a-high-pressure-split-cylinder-die-with-prism-cavity
#11
Liang Zhao, Mingzhe Li, Liyan Wang, Erhu Qu, Zhuo Yi
A novel high-pressure belt-type die with a split-type cylinder is investigated with respect to extending its lifetime and improving its pressure bearing capacity. Specifically, a tungsten carbide cylinder is split into several parts along the radial direction with a prism-type cavity. In this paper, the cylinders with different split numbers are chosen to study the stress distribution and compare them with the traditional belt-type die. The simulation results indicate that the split cylinder has much smaller stress than those in the belt-type cylinder, and the statistical analysis reveals that the split-pressure cylinder is able to bear higher pressure...
March 2018: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29596959/two-efficient-methods-for-isolation-of-high-quality-genomic-dna-from-entomopathogenic-fungi
#12
María G Serna-Domínguez, Gilda Y Andrade-Michel, Hugo C Arredondo-Bernal, Gallou Adrien
Conventional and commercial methods for isolation of nucleic acids are available for fungal samples including entomopathogenic fungi (EPF). However, there is not a unique optimal method for all organisms. The cell wall structure and the wide range of secondary metabolites of EPF can broadly interfere with the efficiency of the DNA extraction protocol. This study compares three commercial protocols: DNeasy® Plant Mini Kit (Qiagen), Wizard® Genomic DNA Purification Kit (Promega), and Axygen™ Multisource Genomic DNA Miniprep Kit (Axygen) and three conventional methods based on different buffers: SDS, CTAB/PVPP, and CTAB/β-mercaptoethanol versus three cell lysis procedures: liquid nitrogen homogenization and two bead-beating materials (i...
March 26, 2018: Journal of Microbiological Methods
https://www.readbyqxmd.com/read/29522437/interfaces-between-model-co-w-c-alloys-with-various-carbon-contents-and-tungsten-carbide
#13
Igor Konyashin, Alexander Zaitsev, Alexander Meledin, Joachim Mayer, Pavel Loginov, Evgeny Levashov, Bernd Ries
Interfaces between alloys simulating binders in WC-Co cemented carbides and tungsten carbide were examined on the micro-, nano-, and atomic-scale. The precipitation of fine WC grains and η-phase occurs at the interface of the alloy with the low carbon content. The precipitation of such grains almost does not occur in the alloy with the medium-low carbon content and does not take place in the alloy with the high carbon content. The formation of Co nanoparticles in the binder alloy with the medium-low carbon content was established...
March 9, 2018: Materials
https://www.readbyqxmd.com/read/29500361/nitrogen-doped-tungsten-carbide-nanoarray-as-an-efficient-bifunctional-electrocatalyst-for-water-splitting-in-acid
#14
Nana Han, Ke R Yang, Zhiyi Lu, Yingjie Li, Wenwen Xu, Tengfei Gao, Zhao Cai, Ying Zhang, Victor S Batista, Wen Liu, Xiaoming Sun
Tungsten carbide is one of the most promising electrocatalysts for the hydrogen evolution reaction, although it exhibits sluggish kinetics due to a strong tungsten-hydrogen bond. In addition, tungsten carbide's catalytic activity toward the oxygen evolution reaction has yet to be reported. Here, we introduce a superaerophobic nitrogen-doped tungsten carbide nanoarray electrode exhibiting high stability and activity toward hydrogen evolution reaction as well as driving oxygen evolution efficiently in acid. Nitrogen-doping and nanoarray structure accelerate hydrogen gas release from the electrode, realizing a current density of -200 mA cm-2 at the potential of -190 mV vs...
March 2, 2018: Nature Communications
https://www.readbyqxmd.com/read/29464838/transformation-dissolution-characterization-of-tungsten-and-tungsten-compounds-for-aquatic-hazard-classification
#15
Philippa Huntsman, Jim Skeaff, Marcin Pawlak, Robert Beaudoin
The transformation/dissolution protocol (T/DP) for metals and sparingly soluble metal compounds was applied to determine the transformation/dissolution (T/D) characteristics of yellow tungsten trioxide, WO3 ; blue tungsten oxide, WOx, x taken as 2.9; tungsten disulphide, WS2 ; tungsten metal, W; 3 samples of tungsten carbide, WC; sodium tungstate, Na2 WO4  · 2H2 O; ammonium paratungstate (APT), (NH4 )10 (H2 W12 O42 ) · 4H2 O; and ammonium metatungstate (AMT) (NH4 )6 (H2 W12 O40 ) · 3H2 O. The T/D data were used to derive aquatic hazard classification outcomes under the United Nations Globally Harmonized System of Classification and Labelling of Chemicals (UN GHS) and European Union Classification, Labelling and Packaging of Substances and Mixtures (EU CLP) schemes by comparing the data with selected acute and chronic ecotoxicity reference values (ERVs) of 31 and 3...
February 21, 2018: Integrated Environmental Assessment and Management
https://www.readbyqxmd.com/read/29448559/thermally-deposited-palladium-tungsten-carbide-and-platinum-tungsten-carbide-counter-electrodes-for-a-high-performance-dye-sensitized-solar-cell-based-on-organic-t-t%C3%A2-electrolyte
#16
Madsakorn Towannang, Anongnad Thiangkaew, Wasan Maiaugree, Kunthaya Ratchaphonsaenwong, Wirat Jarernboon, Samuk Pimanpang, Vittaya Amornkitbamrung
Tungsten carbide (WC) particles (~1 μm) were dispersed in DI water and dropped onto conductive glass. The resulting WC films were used as dye-sensitized solar cell (DSSC) counter electrodes. The performance of the WC DSSC based on the organic thiolate/disulfide (T-/T2) electrolyte was ~0.78%. The cell efficiency was greatly improved after decorating palladium (Pd) or platinum (Pt) nanoparticles on WC particles with a promising efficiency of ~2.15% for Pd-WC DSSC and ~4.62% for Pt-WC DSSC. The efficiency improvement of the composited (Pd-WC and Pt-WC) cells is attributed to co-functioning catalysts, the large electrode interfacial area and a low charge-transfer resistance at the electrolyte/counter electrode interface...
February 1, 2018: Journal of Nanoscience and Nanotechnology
https://www.readbyqxmd.com/read/29411833/drag-crisis-moderation-by-thin-air-layers-sustained-on-superhydrophobic-spheres-falling-in-water
#17
Aditya Jetly, Ivan U Vakarelski, Sigurdur T Thoroddsen
We investigate the effect of thin air layers naturally sustained on superhydrophobic surfaces on the terminal velocity and drag force of metallic spheres free falling in water. The surface of 20 mm to 60 mm steel or tungsten-carbide spheres is rendered superhydrophobic by a simple coating process that uses a commercially available hydrophobic agent. By comparing the free fall of unmodified spheres and superhydrophobic spheres in a 2.5 meter tall water tank, it is demonstrated that even a very thin air layer (∼1-2 μm) that covers the freshly dipped superhydrophobic sphere can reduce the drag force on the spheres by up to 80%, at Reynolds numbers from 105 to 3 × 105 , owing to an early drag crisis transition...
February 28, 2018: Soft Matter
https://www.readbyqxmd.com/read/29360492/a-randomised-controlled-study-on-the-use-of-finishing-and-polishing-systems-on-different-resin-composites-using-3d-contact-optical-profilometry-and-scanning-electron-microscopy
#18
Alaa Daud, Gordon Gray, Christopher D Lynch, Nairn H F Wilson, Igor R Blum
OBJECTIVES: The aim of this study was to evaluate theeffects of different finishing and polishing techniques on the surface roughness of microhybrid and nanofilled resin composites. METHODS: The resin composites included were Filtek Z250 (a universal microhybrid resin composite) and Filtek Supreme XTE (a universal nanofill resin composite). Ninety cylindrical-shaped specimens were prepared for each composite resin material. The polishing methods used included tungsten carbide bur (TC); diamond bur (Db); Sof-Lex discs (S); Enhance PoGo discs (PG); TC + S; Db + S; TC + PG; Db + PG...
April 2018: Journal of Dentistry
https://www.readbyqxmd.com/read/29334298/long-term-effects-of-tungsten-carbide-wc-nanoparticles-in-pelagic-and-benthic-aquatic-ecosystems
#19
Mikael T Ekvall, Jonas Hedberg, Inger Odnevall Wallinder, Lars-Anders Hansson, Tommy Cedervall
As the production and usage of nanomaterials are increasing so are the concerns related to the release of the material into nature. Tungsten carbide (WC) is widely used for its hard metal properties, although its use, in for instance tyre studs, may result in nano-sized particles ending up in nature. Here, we evaluate the potential long-term exposure effects of WC nanoparticles on a pelagic (Daphnia magna) and a benthic (Asellus aquaticus) organism. No long-term effects were observed in the benthic system with respect to population dynamics or ecosystem services...
February 2018: Nanotoxicology
https://www.readbyqxmd.com/read/29316102/selective-production-of-renewable-para-xylene-by-tungsten-carbide-catalyzed-atom-economic-cascade-reactions
#20
Tao Dai, Changzhi Li, Lin Li, Zongbao Kent Zhao, Bo Zhang, Yu Cong, Aiqin Wang
Tungsten carbide was employed as the catalyst in an atom-economic and renewable synthesis of para-xylene with excellent selectivity and yield from 4-methyl-3-cyclohexene-1-carbonylaldehyde (4-MCHCA). This intermediate is the product of the Diels-Alder reaction between the two readily available bio-based building blocks acrolein and isoprene. Our results suggest that 4-MCHCA undergoes a novel dehydroaromatization-hydrodeoxygenation cascade process by intramolecular hydrogen transfer that does not involve an external hydrogen source, and that the hydrodeoxygenation occurs through the direct dissociation of the C=O bond on the W2 C surface...
February 12, 2018: Angewandte Chemie
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