Effect of Al2O3-NbC nanopowder incorporation on the mechanical properties of 3Y-TZP/Al2O3-NbC nanocomposites obtained by conventional and spark plasma sintering

[EN] The incorporation of Al2O3-NbC-nanopowder reinforcement in a 3Y-TZP matrix, and its influence on the mechanical properties of 3YTZP/Al2O3-NbC nanocomposites, obtained by conventional and spark plasma sintering (SPS), was investigated. Nanometric powders of Al2O3-NbC were prepared by reactive high-energy milling, deagglomeration, and leaching with acid, and added to the 3Y-TZP matrix, at a proportion of 5 vol%. The final powders were dried under airflow, compacted, and sintered in the temperature range of 1300-1500 degrees C. The effects of the sintering technique and final temperature, on the microstructure and mechanical properties, such as hardness, toughness, and Young's modulus, were analysed. Fracture toughness of the material reinforced with Al2O3-NbC nanopowders, which is one of its most important properties, differed significantly from that of the 3Y-TZP monolith (5.2 MPa m(1/2)). The nanocomposites, sintered conventionally at 1450 degrees C, showed higher fracture toughness (8.7 MPa m(1/2)). Microstructure observations indicated that NbC nanoparticles were dispersed homogeneously within the 3Y-TZP matrix, and limited its grain growth. However, partial oxidation of the NbC on the nanocomposite surface, at the conventional sintering temperature of 1500 degrees C, caused a reduction in the fracture toughness.The authors acknowledge the Brazilian institutions CAPES-PVE (grant number 23038.009604/2013-12), FAPESP (grant number 2015/07319-8), Fundação Araucária (grant number 810/2014), European Union/Erasmus Mundus for doctorate mobility (grant number EB15DM1542), and the Spanish Ministry of Economy and Competitiveness (grant number IJCI-2014-19839).Salem, R.; Monteiro, R.; Gutierrez, CF.; Borrell Tomás, MA.; Salvador Moya, MD.; Chinelatto, AS.; Chinelatto, A.... (2018). Effect of Al2O3-NbC nanopowder incorporation on the mechanical properties of 3Y-TZP/Al2O3-NbC nanocomposites obtained by conventional and spark plasma sintering. Ceramics International. 44(2):2504-2509. https://doi.org/10.1016/j.ceramint.2017.10.235S2504250944

D* Production in Deep Inelastic Scattering at HERA

This paper presents measurements of D^{*\pm} production in deep inelastic scattering from collisions between 27.5 GeV positrons and 820 GeV protons. The data have been taken with the ZEUS detector at HERA. The decay channel $D^{*+}\to (D^0 \to K^- \pi^+) \pi^+$ (+ c.c.) has been used in the study. The $e^+p$ cross section for inclusive D^{*\pm} production with $5<Q^2<100 GeV^2$ and $y<0.7$ is 5.3 \pms 1.0 \pms 0.8 nb in the kinematic region {$1.3<p_T(D^{*\pm})<9.0$ GeV and $| \eta(D^{*\pm}) |<1.5$}. Differential cross sections as functions of p_T(D^{*\pm}), $\eta(D^{*\pm}), W$ and $Q^2$ are compared with next-to-leading order QCD calculations based on the photon-gluon fusion production mechanism. After an extrapolation of the cross section to the full kinematic region in p_T(D^{*\pm}) and $\eta$(D^{*\pm}), the charm contribution $F_2^{c\bar{c}}(x,Q^2)$ to the proton structure function is determined for Bjorken $x$ between 2 $\cdot$ 10$^{-4}$ and 5 $\cdot$ 10$^{-3}$.Comment: 17 pages including 4 figure

Observation of Scaling Violations in Scaled Momentum Distributions at HERA

Charged particle production has been measured in deep inelastic scattering (DIS) events over a large range of $x$ and $Q^2$ using the ZEUS detector. The evolution of the scaled momentum, $x_p$, with $Q^2,$ in the range 10 to 1280 $GeV^2$, has been investigated in the current fragmentation region of the Breit frame. The results show clear evidence, in a single experiment, for scaling violations in scaled momenta as a function of $Q^2$.Comment: 21 pages including 4 figures, to be published in Physics Letters B. Two references adde

A pilot study on the global practice of informed consent in paediatric dentistry

Background: Conducting oral treatment early in the disease course, is encouraged for better health outcomes. Obtaining informed consent is an essential part of medical practice, protecting the legal rights of patients and guiding the ethical practice of medicine. In practice, consent means different things in different contexts. Silver Diamine Fluoride (SDF) and Silver Fluoride (SF) is becoming popular and cost effective methods to manage carious lesions, however, cause black discolouration of lesions treated. Obtaining informed consent and assent is crucial for any dental treatment—and has specific relevance with SDF/ SF treatments. Methods: The aim of this paper is to describe informed consent regulations for dental care in a selection of countries, focusing on children and patients with special health care needs. An online survey was shared with a convenience sample of dental professionals from 13 countries. The information was explored and the processes of consent were compared. Results: Findings suggest that there are variations in terms of informed consent for medical practice. In Tanzania, South Africa, India, Kenya, Malaysia and Brazil age is the determining factor for competence and the ability to give self-consent. In other countries, other factors are considered alongside age. For example, in Singapore, the United Kingdom, and the United States the principle of Gillick Competence is applied. Many countries' laws and regulations do not specify when a dentist may overrule general consent to act in the “best interest” of the patient. Conclusion: It is recommended that it is clarified globally when a dentist may act in the “best interest” of the patient, and that guidance is produced to indicate what constitutes a dental emergency. The insights gathered provide insights on international practice of obtaining informed consent and to identify areas for change, to more efficient and ethical treatment for children and patients with special needs. A larger follow up study is recommended to include more or all countries

The state of the Martian climate

60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes

A simple proof of a primal affine scaling method

In this paper, we present a simpler proof of the result of Tsuchiya and Muramatsu on the convergence of the primal affine scaling method. We show that the primal sequence generated by the method converges to the interior of the optimum face and the dual sequence to the analytic center of the optimal dual face, when the step size implemented in the procedure is bounded by 2/3. We also prove the optimality of the limit of the primal sequence for a slightly larger step size of 2 q /(3 q −1), where q is the number of zero variables in the limit. We show this by proving the dual feasibility of a cluster point of the dual sequence.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44263/1/10479_2005_Article_BF02206821.pd