Search results for "Note"
showing 10 items of 10709 documents
The effect of composite resin preheating on marginal adaptation of class II restorations
2020
Background One of the problems with a high filler content composite resins is gap formation at restorative material-tooth interface. The present study investigated the effect of preheating composite resins on the formation of marginal gap in Cl II restorations. Material and Methods In this in vitro study Sixty Cl II cavities were prepared on the mesial and distal surfaces of 30 extracted premolar teeth. The gingival floor of cavities was placed 1 m below the CEJ. The samples were randomly allocated to 4 groups for restoration placement: group 1, Filtek P60 composite resin at room temperature; group 2, Filtek P60 composite resin at 68°C; group 3, X-tra fil composite resin at room temperature…
On the Tail Risk of Cyberattacks in the Bitcoin Market
2020
In the era of digitalization, cryptocurrencies have become an alternative asset for both retail and institutional investors. While the new emerging digital ecosystem based on blockchain technology has been praised for offering plenty of advantages such as decentralization, discretion or increased efficiency in terms of faster settlements among others, investors need to be aware of new types of risks such as hacking incidents. In the 2011-2018 period, about 1.7 million unit of Bitcoin have been stolen corresponding to losses accumulating more than $655 million highlighting the societal impact of this criminal activity. The novel aspect of our study is that it employs a recently proposed appr…
Fine-tuning of the confined space in microporous metal–organic frameworks for efficient mercury removal
2017
Offsetting the impact of human activities on the biogeochemical cycle of mercury has become necessary for a sustainable planet. Herein, we report the development of a water-stable and eco-friendly metal–organic framework, which has the formula {Cu4II[(S,S)-methox]2}·5H2O (1), where methox is bis[(S)-methionine]oxalyl diamide. Its features include narrow functional channels decorated with thioalkyl chains, which are able to capture HgCl2 from aqueous media in an efficient, selective, and rapid manner. The conscious design effort in terms of size, shape, and reactivity of the channels results in extremely efficient immobilization of HgCl2 guest species in a very stable conformation, similar t…
Simulation of mid-IR amplification in Er3+-doped chalcogenide microstructured optical fiber
2009
International audience; This paper deals with the design of an erbium doped microstructured optical fiber (MOF) amplifier operating in the mid-infrared (mid-IR) wavelength range, more precisely around 4.5 µm wavelength. A homemade numerical code which solves the rate equations and the power propagation equations has been ad hoc developed to theoretically investigate the feasibility of mid-IR MOF amplifier. On the basis of the measured energy level transition parameters of a Er3+-doped Ga5Ge20Sb10S65 chalcogenide glass, the amplifier feasibility is demonstrated exhibiting high gain and low noise figure.
Abrupt elastic-to-plastic transition in pentagonal nanowires under bending
2019
MD modeling and calculations were supported by Russian Science Foundation project grant 18-19-00645 “Adhesion of polymer-based soft materials: from liquid to solid”; mechanical testing and FEM simulations were supported by Estonian Research Council projects PUT1689 and PUT1372.
Finite element method on fractional visco-elastic frames
2016
Viscoelastic behavior is defined by fractional operators.Quasi static FEM analysis of frames with fractional constitutive law is performed.FEM solution is decoupled into a set of fractional Kelvin Voigt elements.Proposed approach could be easily integrated in existing FEM codes. In this study the Finite Element Method (FEM) on viscoelastic frames is presented. It is assumed that the Creep function of the constituent material is of power law type, as a consequence the local constitutive law is ruled by fractional operators. The Euler Bernoulli beam and the FEM for the frames are introduced. It is shown that the whole system is ruled by a set of coupled fractional differential equations. In q…
Stiklveida ķermeņa apduļķojumu fāzes rekonstruēšana aberāciju klātbūtnē
2020
Maģistra darbs ir uzrakstīts latviešu valodā uz 45 lapaspusēm. Tas satur 34 attēlu, 4 tabulas, un 46 atsauces uz literatūras avotiem. Darba mērķis: Izvērtēt, kā optiskās sistēmas parametri ietekmē stiklveida ķermeņa apduļķojumu fāzes noteikšanu optiskās sistēmas aberāciju klātbūtnē. Metode: Aberāciju/apduļķojumu simulācijas, optisko parametru ietkmes izvērtēšana MATLAB vidē. Rezultāti un analīze: Apduļķojumi ir rekonstruējami aberāciju klātbūtnē. Ja trokšņa un fona amplitūda ir vienāda, fons kvalitāti pazemina vairāk. Bitu dziļuma pazemināšana samazina trokšņa un fona efektu. Datu ieguves biežuma palielināšana uzlabo rekonstrukcijas kvalitāti. Secinājumi: Troksnis, bitu dziļums, fons, datu …
Tool Wear and Damage
2008
This chapter provides comprehensive knowledge regarding tool wear mechanisms and characterizes their physical fundamentals. Adhesion, abrasion, diffusion and oxidation are selected as predominant mechanisms controlling tool wear, depending on the mechanical and thermal conditions at the rake and flank faces. The analytical models describing the wear rate and volumetric material loss for different wear mechanisms are provided. The tool wear indicators related to crater, flank and notch wear specified in ISO 3685 are presented for both flat-faced and grooved tools. Tool life is defined and corresponding models, including the influence of cutting speed, feed and the depth of cut, are derived. …
Design of Magnetic Coordination Polymers Built from Polyoxalamide Ligands: A Thirty Year Story
2018
International audience; The aim of this review is to pay tribute to the legacy of O. Kahn. Kahn's credo was to synthesize magnetic compounds with predictable structure and magnetic properties. This is illustrated herein with results obtained by Kahn's group during his Orsay period thirty years ago, but also on the basis of our recent results on the synthesis of coordination polymers with oxamate ligands. The first part of this review is devoted to a short description of the necessary knowledge in physics and theoretical chemistry that Kahn and his group have used to select oxamate ligands, the complex‐as‐ligand strategy and the synthesis of heterobimetallic systems. Then, we describe the st…
Layered Double Hydroxides
2020
The impact of layered double hydroxides (LDHs) within the multidisciplinary fields of materials sciences, physics, chemistry, and biology is rapidly growing, given their easiness of synthesis, flexibility in composition, tunable biocompatibility and morphology. LDHs constitute a versatile platform for the realization of new classes of functional systems, showing unique enhanced surface effects and unprecedented properties for application in very different fields, namely, surface chemistry and catalysis, storage and triggered release of functional anions, flame retardants, drug delivery and nanomedicine, remediation, energy storage and conversion. These systems can be synthesized as self-ass…