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Tungsten carbide

Amy Porter, Regina Irwin, Josselyn Miller, Daniel J Horan, Alexander G Robling, Laura R McCabe
We have developed a straightforward method that uses paraffin-embedded bone for undemineralized thin sectioning, which is amenable to subsequent dynamic bone formation measurements. Bone has stiffer material properties than paraffin, and therefore has hereforto usually been embedded in plastic blocks, cured and sectioned with a tungsten carbide knife to obtain mineralized bone sections for dynamic bone formation measures. This process is expensive and requires special equipment, experienced personnel, and time for the plastic to penetrate the bone and cure...
February 15, 2017: Scientific Reports
Yolanda S Hedberg, Jonas F Hedberg, Sara Isaksson, Nanxuan Mei, Eva Blomberg, Susanna Wold, Inger Odnevall Wallinder
Studded tyres made of tungsten carbide cobalt (WC-Co) are in the Northern countries commonly used during the winter time. Tungsten (W)-containing nano- and micron-sized particles have been detected close to busy roads in several European countries. Other typical traffic wear particles consist of copper (Cu). The aims of this study were to investigate particle stability and transformation/dissolution properties of nanoparticles (NPs) of WC-Co compared with NPs of tungsten carbide (WC), cobalt (Co), and Cu. Their physicochemical characteristics (primarily surface oxide and charge) are compared with their extent of sedimentation and metal release in synthetic surface water (SW) with and without two different model organic molecules, 2,3- and 3,4-dihydroxybenzoic acid (DHBA) mimicking certain sorption sites of humic substances, for time periods up to 22 days...
February 11, 2017: Environmental Pollution
Alexandre Antonio Ribeiro, Layene Figueiredo Almeida, Lidia Parsekian Martins, Renato Parsekian Martins
INTRODUCTION: Our objective was to assess the amounts of adhesive remnant and enamel damage when removing composite under conventional lighting and ultraviolet (UV) light. METHODS: Thirty-eight premolars were divided into 2 groups according to the lighting used for adhesive removal. A multifluted tungsten-carbide bur at low speed was used for this process in both groups. The UV group received conventional lighting associated with UV light, and the conventional group received conventional lighting only...
February 2017: American Journal of Orthodontics and Dentofacial Orthopedics
Zirong Peng, Pyuck-Pa Choi, Baptiste Gault, Dierk Raabe
Cemented tungsten carbide has been analyzed using laser-pulsed atom probe tomography (APT). The influence of experimental parameters, including laser pulse energy, pulse repetition rate, and specimen base temperature, on the acquired data were evaluated from different aspects, such as mass spectrum, chemical composition, noise-to-signal ratio, and multiple events. Within all the applied analysis conditions, only 1 MHz pulse repetition rate led to a strong detector saturation effect, resulting in a largely biased chemical composition...
January 17, 2017: Microscopy and Microanalysis
Li Song, Tao Wang, Yilin Wang, Hairong Xue, Xiaoli Fan, Hu Guo, Wei Xia, Hao Gong, Jianping He
We synthesized a novel nonprecious metal electrocatalyst by pyrolysis of a colloid mixture consisting of a tungsten source and phenolic resin, with the simultaneous addition of ferric salt. The rationally designed electrocatalyst has a unique structure, with nanosized WC and Fe3W3C uniformly dispersed in a three-dimensional porous carbon framework. WC, which was thought difficult to produce, is successfully prepared at a relatively low temperature of about 750 °C at an inert atmosphere. XRD studies demonstrate the self-assisted effect of Fe, which accelerates the formation of WC, getting around the pathway of direct carbonaceous reduction of tungsten by carbon...
February 1, 2017: ACS Applied Materials & Interfaces
Richard A Secco, Wenjun Yong
A new custom-designed system for a 3000 ton multi-anvil press has been developed to reach temperatures below room temperature at high pressures. The system was designed to remove heat selectively and conductively from the sample volume through six of the eight tungsten carbide (WC) cubes in direct contact with the octahedral pressure cell. The key components of the system include Cu cooling fins sandwiched between neighboring cube faces and the connected Cu heat exchange chamber through which liquid nitrogen flows...
December 2016: Review of Scientific Instruments
Etienne Medioni, Jean-Paul Rocca, Carlo Fornaini, Elisabetta Merigo
A number of concepts and devices have been proposed for caries removal. Among these, the Er:YAG laser is a potential alternative to conventional mechanical treatment. This study compared the effectiveness of the Er:YAG laser with that of low-speed rotary instruments for removal of carious tissue in 26 extracted human molars and premolars with severe decay (i.e., large occlusal or proximal decay but no pulpal contact). The teeth were divided into three groups of eight teeth, and two teeth were used as controls...
2016: Journal of Oral Science
Niklas Renner, Hartwig Steckel, Nora Urbanetz, Regina Scherließ
The present study investigates the effect of different carrier surface modifications on the aerosolisation performance and on the effective carrier payload of interactive blends for inhalation. Two different active pharmaceutical ingredients (APIs) were used: Formoterol fumarate dihydrate (FF) and budesonide (BUD). Blends were prepared with glass beads as model carriers which have been subjected to mechanical surface modifications in order to introduce surface roughness via treatment with hydrofluoric acid (HF) and/or milling with tungsten carbide (TC)...
December 23, 2016: International Journal of Pharmaceutics
Ehsan Monazami, John B McClimon, James Rondinelli, Petra Reinke
The understanding and control of molecule-metal interfaces is critical to the performance of molecular electronics and photovoltaics devices. We present a study of the interface between C60 and W, which is a carbide-forming transition metal. The complex solid-state reaction at the interface can be exploited to adjust the electronic properties of the molecule layer. Scanning tunneling microscopy/spectroscopy measurements demonstrate the progression of this reaction from wide band gap (>2.5 eV) to metallic molecular surface during annealing from 300 to 800 K...
December 21, 2016: ACS Applied Materials & Interfaces
Andrea L Armstead, Bingyun Li
As the number of commercial and consumer products containing engineered nanomaterials (ENMs) continually rises, the increased use and production of these ENMs presents an important toxicological concern. Although ENMs offer a number of advantages over traditional materials, their extremely small size and associated characteristics may also greatly enhance their toxic potentials. ENM exposure can occur in various consumer and industrial settings through inhalation, ingestion, or dermal routes. Although the importance of accurate ENM characterization, effective dosage metrics, and selection of appropriate cell or animal-based models are universally agreed upon as important factors in ENM research, at present, there is no "standardized" approach used to assess ENM toxicity in the research community...
2016: International Journal of Nanomedicine
Ming Ma, Shijie You, Wei Wang, Guoshuai Liu, Dianpeng Qi, Xiaodong Chen, Jiuhui Qu, Nanqi Ren
The oxygen-reduction reaction (ORR) draws an extensive attention in many applications, and there is a growing interest to develop effective ORR electrocatalysts. Iron carbide (Fe3C) is a promising alternative to noble metals (e.g., platinum), but its performances need further improvement, and the real role of the Fe3C phase remains unclear. In this study, we synthesize Fe3C/tungsten carbide/graphitic carbon (Fe3C/WC/GC) nanocomposites, with waste biomass (i.e., pomelo peel) serving as carbon source, using a facile, one-step carbon thermal-reduction method...
November 30, 2016: ACS Applied Materials & Interfaces
Li Song, Tao Wang, Yiou Ma, Hairong Xue, Hu Guo, Xiaoli Fan, Wei Xia, Hao Gong, Jianping He
The scarcity, high cost and poor stability of precious metal-based electrocatalysts have stimulated the development of novel non-precious metal catalysts to oxygen reduction reaction (ORR) for the use in fuel cells and metal-air batteries. Here, we in-situ fabricated a hybrid material (Co-W-C/N) with functional species (tungsten carbide and cobalt nanoparticles) encapsulated in N-doped porous carbon framework, through a facile multi-constituents co-assembly method combined with subsequent annealing treatment...
December 7, 2016: Chemistry: a European Journal
Andrea L Armstead, Bingyun Li
Identifying the toxicity of nanoparticles (NPs) is an important area of research as the number of nanomaterial-based consumer and industrial products continually rises. In addition, the potential inflammatory effects resulting from pulmonary NP exposure are emerging as an important aspect of nanotoxicity. In this study, the toxicity and inflammatory state resulting from tungsten carbide-cobalt (WC-Co) NP exposure in macrophages and a coculture (CC) of lung epithelial cells (BEAS-2B) and macrophages (THP-1) at a 3:1 ratio were examined...
2016: International Journal of Nanomedicine
Bruno Alessandro Silva Guedes de Lima, Rodinei Medeiros Gomes, Severino Jackson Guedes de Lima, Diana Dragoe, Marie-Geneviève Barthes-Labrousse, Richard Kouitat-Njiwa, Jean-Marie Dubois
After gas atomization, a quasicrystalline powder based on aluminium was used to prepare a thick coating by high-velocity oxygen-fuel flame torch spraying. This layer was deposited on top of a bond-coat layer on a steel plate. A post-spraying annealing treatment turned the two layers to their stable state, a γ-brass crystal and an icosahedral quasicrystal, respectively. The projection parameters were selected in such a way that the coating behaved like a self-lubricating material, which offered very good wear resistance (duration of pin-on-disk tests superior to 5 km with negligible material loss) and low friction (µ ≤ 6% against sintered tungsten carbide), in contrast to the state of the art...
2016: Science and Technology of Advanced Materials
Jun Kang, Hye-Min Kim, Nagahiro Saito, Myeong-Hoon Lee
Co nanoparticles (Co NPs) and nanoscale tungsten carbide (WC) are successfully synthesized simultaneously with mesoporous structured carbon black (C) using an innovative simple method, which is known as solution plasma processing (SPP), and NPs are also loaded onto carbon black at the same time by SPP. The introduction of Co NPs led to not only superior oxygen reduction reaction (ORR) activity in terms of onset potential and peak potential, but also to a more efficient electron transfer process compared to that of pure WC...
2016: Science and Technology of Advanced Materials
Michael Dawson, Valeria Soro, David Dymock, Robert Price, Helen Griffiths, Tom Dudding, Jonathan R Sandy, Anthony J Ireland
INTRODUCTION: The aims of this study were to describe bacterial load and diversity of the aerosol created during enamel cleanup after the removal of fixed orthodontic appliances and to assess the effect of a preprocedural mouth rinse. METHODS: The study involved the sampling of ambient air adjacent to the patient's mouth during adhesive removal using a slow-speed handpiece and a spiral fluted tungsten carbide bur without water irrigation. Sampling was carried out during enamel cleanup with or without a preprocedural mouth rinse of either sterile water or chlorhexidine...
November 2016: American Journal of Orthodontics and Dentofacial Orthopedics
Haiwei Guo, Bo Zhang, Zaojuan Qi, Changzhi Li, Jianwei Ji, Tao Dai, Aiqin Wang, Tao Zhang
Lignins isolated from representative hardwood, softwood, and grass materials were effectively hydrocracked to aromatics catalyzed by tungsten carbide over activated carbon (W2 C/AC). The effects of botanical species and fractionation methods on lignin structure and the activity of W2 C/AC were studied in detail. Gas permeation chromatography (GPC), FTIR, elemental analysis, and 2 D HSQC NMR showed that all the extracted samples shared the basic skeleton of lignin, whereas the fractionation method significantly affected the structure...
November 10, 2016: ChemSusChem
Xinping Zhang, Haibin Wang, Meng Wang, Yuanhai Lin, Xiaoyan Song
Ultrafast optical excitation induced transient modification on the energy-band structures in tungsten, which resulted in the expansion and shift toward the Fermi-level of d-band. This process led to enhanced interband transitions at reduced photon energies. Meanwhile, enhanced interband excitation led to increased electron density above the Fermi level, resulting in enhanced optical scattering by localized surface plasmon resonance (LSPR). These mechanisms are responsible for balancing the direct heating of bulk electrons by optical pulses...
October 3, 2016: Optics Express
Grant E Johnson, Trevor Moser, Mark Engelhard, Nigel D Browning, Julia Laskin
About 40 years ago, it was shown that tungsten carbide exhibits similar catalytic behavior to Pt for certain commercially relevant reactions, thereby suggesting the possibility of cheaper and earth-abundant substitutes for costly and rare precious metal catalysts. In this work, reactive magnetron sputtering of Ta in the presence of three model hydrocarbons (2-butanol, heptane, and m-xylene) combined with gas aggregation and ion soft landing was employed to prepare organic-inorganic hybrid nanoparticles (NPs) on surfaces for evaluation of catalytic activity and durability...
November 7, 2016: Journal of Chemical Physics
Haiwei Guo, Bo Zhang, Changzhi Li, Chang Peng, Tao Dai, Haibo Xie, Aiqin Wang, Tao Zhang
A remarkably effective method for the chemoselective cleavage of the C-O bonds of typical β-O-4 model compounds and the deconstruction of lignin feedstock was developed by using tungsten carbide as the catalyst. High yields of C-O cleavage products (up to 96.8 %) from model compounds and liquid oils (up to 70.7 %) from lignin feedstock were obtained under low hydrogen pressure (0.69 MPa) in methanol. The conversion efficiency was determined to a large extent by solvent effects and was also affected by both the electronic and steric effects of the lignin model compounds...
November 23, 2016: ChemSusChem
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