Search results for "Shit"

Galvanic deposition and characterization of brushite/hydroxyapatite coatings on 316L stainless steel

2016

In this work, brushite and brushite/hydroxyapatite (BS, CaHPO4·H2O; HA, Ca10(PO4)6(OH)2) coatings were deposited on 316L stainless steel (316LSS) from a solution containing Ca(NO3)2·4H2O and NH4H2PO4 by a displacement reaction based on a galvanic contact, where zinc acts as sacrificial anode. Driving force for the cementation reaction arises from the difference in the electrochemical standard potentials of two different metallic materials (316LSS and Zn) immersed in an electrolyte, so forming a galvanic contact leading to the deposition of BS/HA on nobler metal. We found that temperature and deposition time affect coating features (morphology, structure, and composition). Deposits were char…

Calcium phosphate/polyvinyl acetate coatings on SS304 via galvanic co-deposition for orthopedic implant applications

2021

Abstract In this work, the galvanic deposition method is used to deposit coatings of brushite/hydroxyapatite/polyvinyl acetate on 304 stainless steel. Coatings are obtained at different temperatures and with different sacrificial anodes, consisting of a mixture of brushite and hydroxyapatite. Samples are aged in a simulated body fluid (SBF), where a complete conversion of brushite into hydroxyapatite with a simultaneous change in morphology and wettability occurred. The corrosion tests show that, compared with bare 304, the coating shifts Ecorr to anodic values and reduces icorr Ecorr, and icorr has different values at different aging times due to chemical interactions at the solid/liquid i…

Is There a C-Function in 4D Quantum Einstein Gravity?

2016

We describe a functional renormalization group-based method to search for ‘C-like’ functions with properties similar to that in 2D conformal field theory. It exploits the mode counting properties of the effective average action and is particularly suited for theories including quantized gravity. The viability of the approach is demonstrated explicitly in a truncation of 4 dimensional Quantum Einstein Gravity, i.e. asymptotically safe metric gravity.

A field theoretic realization of a universal bundle for gravity

1992

Abstract Based upon a local vector supersymmetry algebra, we discuss the general structure of the quantum action for topological gravity theories in arbitrary dimensions. The precise form of the action depends on the particular dimension, and also on the moduli space of interest. We describe the general features by examining a theory of topological gravity in two dimensions, with a moduli space specified by vanishing curvature two-form. It is shown that these topological gravity models together with their observables provide a field theoretic realization of a universal bundle for gravity.

Focus on quantum Einstein gravity

2012

The gravitational asymptotic safety program summarizes the attempts to construct a consistent and predictive quantum theory of gravity within Wilson's generalized framework of renormalization. Its key ingredient is a non-Gaussian fixed point of the renormalization group flow which controls the behavior of the theory at trans-Planckian energies and renders gravity safe from unphysical divergences. Provided that the fixed point comes with a finite number of ultraviolet-attractive (relevant) directions, this construction gives rise to a consistent quantum field theory which is as predictive as an ordinary, perturbatively renormalizable one. This opens up the exciting possibility of establishin…

Quantum Einstein Gravity: Towards an Asymptotically Safe Field Theory of Gravity

2007

A min-max principle for non-differentiable functions with a weak compactness condition

2009

A general critical point result established by Ghoussoub is extended to the case of locally Lipschitz continuous functions satisfying a weak Palais-Smale hypothesis, which includes the so-called non-smooth Cerami condition. Some special cases are then pointed out.

Brushite/Hydroxyapatite Coatings obtained by galvanic deposition on 316L Stainless Steel

2016

Hydroxyapatite (HA, Ca10(PO4)6(OH)2) is a basic calcium phosphate mineral with chemical composition similar to that of bones and teeth. Owing to this peculiarity HA is a biocompatible material of high medical interest. Unfortunately, it possesses poor mechanical properties, because is brittle, has a low fracture resistance and a poor wear resistance. For these reasons, in the last years the research was been focused on the use of HA as a coating of another biomaterial that acts as support. The best choice is that to use a substrate that must be bionert and mechanically stable, such as 316L stainless steel (316LSS). This is useful for biomedical implants, because of its excellent biocompatib…

In vitro corrosion and biocompatibility of brushite/hydroxyapatite coatings obtained by galvanic deposition on 316LSS

2018

Corrosion behavior and cytotoxicity was reported for mixed brushite (BS)/hydroxyapatite (HA) coatings deposited on 316LSS substrate through a displacement reaction. Corrosion tests, carried out in a simulated body fluid, showed that in comparison with bare 316L, coating shifts Ecorrto anodic values and reduces icorreven if oscillations were observed, which were explained in terms of the chemical interactions at the solid/liquid interface. Cell biocompatibility of the coating was investigated through osteoblastic cell line MC3T3-E1, evidencing the absence of any cytotoxicity Taken together, the results show that galvanic deposition is a simple and cost-effective method for producing bioactiv…

Les interactiones de Casimir hors d'équilibre : effets dynamiques et thermiques

2016

In this thesis, after an introduction where we briefly present the general context of Casimir physics, we present the results obtained during the PhD. At first, we show our work about the van der Waals/Casimir-Polder interactions between two atoms in an out-of-equilibrium condition due to their uniformly accelerated motion. We study the system of two uniformly accelerated atoms in vacuum space, when they are in their ground-state and when they are in a correlated state (one excited and one ground-state atom). We analyze this system both with an heuristic semiclassical model and with a more rigorous method, based on a separation of radiation reaction and vacuum fluctuations contributions, th…