Electrochemical and Antibacterial Performance of CoCrMo Alloy Coated with Hydroxyapatite or Silver Nanoparticles

This paper presents a comparative study of antimicrobial and electrochemical performance of CoCrMo alloy surface treated with hydroxyapatite coating or silver nanoparticles (nAg) in the presence/absence of albumin addition. Nanoparticles dimension was quantified using dynamic light scattering. Antibacterial activity was evaluated by a spread plate method, while electrochemical characterization of CoCrMo samples coated and uncoated was studied by open circuit potential and cyclic polarization experiments. Furthermore, all surface coatings characterization was investigated by transmission electron microscopy, scanning electron spectroscopy, and energy-dispersive x-ray spectroscopy. The highest corrosion rate in simulated body solution (SBF) is for untreated CoCrMo alloy, and the lowest value is for CoCrMo alloy treated with nAg after addition in SBF of 80 g/L albumin. Only the surface treated with nAg has antibacterial effect.     

Thermal and electrical properties of some carbon fibers

Two types of carbon materials were studied and their electrical and thermal properties in various conditions of utilisation were determined. Variation of properties was correlated with structure changes.     

Aspects relating to stability of modified passive stratum on TiO2 nanostructure

Two kinds of nanotube structures differing from the point of view of their dimensions were obtained using anodizing in two different fluoride electrolytes and these structures were investigated regarding stability. The nanotubes have diameters of around 100 and 65 nm, respectively, and the testing solutions were simulated body fluids (SBF) and NaCl 0.9%. As stability experiments, cyclic voltammetry was performed and ions release was measured. The quantity of released cations in time as a kinetic aspect of passive stratum behavior was followed with an inductively coupled plasma mass spectrometer (ICP-MS) and apatite forming in SBF was found with infrared spectra. This study led to a comparison between the modification and the behavior of passive stratum on nanotubes as a function of their diameters.     

The biocompatibility of titanium in a buffer solution: compared effects of a thin film of TiO<Subscript>2</Subscript> deposited by MOCVD and of collagen deposited from a gel

This study aims at evaluating the biocompatibility of titanium surfaces modified according two different ways: (i) deposition of a bio-inert, thin film of rutile TiO₂ by chemical vapour deposition (MOCVD), and (ii) biochemical treatment with collagen gel, in order to obtain a bio-interactive coating. Behind the comparison is the idea that either the bio-inert or the bio-active coating has specific advantages when applied to implant treatment, such as the low price of the collagen treatment for instance. The stability in buffer solution was evaluated by open circuit potential (OCP) for medium time and cyclic voltametry. The OCP stabilized after 5·10⁴ min for all the specimens except the collagen treated sample which presented a stable OCP from the first minutes. MOCVD treated samples stabilized to more electropositive values. Numeric results were statistically analysed to obtain the regression equations for long time predictable evolution. The corrosion parameters determined from cyclic curves revealed that the MOCVD treatment is an efficient way to improve corrosion resistance. Human dermal fibroblasts were selected for cell culture tests, taking into account that these cells are present in all bio-interfaces, being the main cellular type of connective tissue. The cells grew on either type of surface without phenotype modification. From the reduction of yellow, water-soluble 3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT cytotoxicity test), MOCVD treated samples offer better viability than mechanically polished Ti and collagen treated samples as well. Cell spreading, as evaluated from microscope images processed by the program Sigma Scan, showed also enhancement upon surface modification. Depending on the experimental conditions, MOCVD deposited TiO₂ exhibits different nanostructures that may influence biological behaviour. The results demonstrate the capacity of integration in simulated physiologic liquids for an implant pretreated by either method.     

Conduites abusives et négligentes envers les enfants: Réalités canadienne et américaine.

Conducted 2 studies in Montreal on the correlation between economic and social poverty of neighborhoods and the incidence rate of family violence and neglect against children. In the 1st study, an incidence rate of 4.95 per 1,000 families was computed. The best predictors of child maltreatment were the percentage of families under the poverty level in a given area and the percentage of families in which the woman was the only breadwinner. A 2nd study was conducted among 291 mothers living in equally poor neighborhoods that dramatically differed in their rates of child abuse and neglect. Mothers of high-rate neighborhoods described more centripetal, conflictual, and specialized social support networks than mothers of low-rate areas. Results confirm the strong association between economic deprivation and family suffering and underline the important role played by psychosocial, political, and cultural factors in parent–child relationships. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Polypyrrole film architectures influence on platinum nanoparticles efficiency in ethanol electrooxidation

The electrodeposition of polypyrrole films from aqueous surfactant solution through a two‐dimensional polystyrene template onto indium‐tin oxide substrate has been investigated. The polymer grows in the interstitial spaces of the self‐assembled polystyrene spheres, which were subsequently removed by dissolution in toluene. The new obtained surface was characterized by scanning electron microscopy and atomic force microscopy. Platinum nanoparticles were deposited onto the nanostructured polypyrrole electrode and used as a catalyst for the oxidation of ethanol for direct ethanol fuel cells. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41375.     

Mining hot calling contexts in small space

Calling context trees (CCTs) associate performance metrics with paths through a program's call graph, providing valuable information for program understanding and performance analysis. In real applications, however, CCTs might easily consist of tens of millions of nodes, making them difficult to analyze and also hurting execution times because of poor access locality. For performance analysis, accurately mining only hot calling contexts may be more useful than constructing an entire CCT with millions of uninteresting paths, because the distribution of context frequencies is typically very skewed. In this article, we show how to exploit this property to considerably reduce the CCT size, introducing a novel runtime data structure, called hot CCT (HCCT), in the spectrum of representations for interprocedural control flow. The HCCT includes only hot nodes and their ancestors in a CCT and can be constructed independently from it by using fast, space‐efficient algorithms for mining frequent items in data streams. With this approach, we can distinguish between hot and cold contexts on the fly while obtaining very accurate frequency counts. We show, both theoretically and experimentally, that the HCCT achieves a similar precision as the CCT in a space that is several orders of magnitude smaller and roughly proportional to the number of hot contexts. Our approach can be effectively combined with previous context‐sensitive profiling techniques, as we show for static bursting. We devise an implementation as a plug‐in for the gcc compiler that incurs a slowdown competitive with the gprof call‐graph profiler while collecting finer‐grained profiles. Copyright © 2015 John Wiley & Sons, Ltd.     

Thermal stability of copolymer acrylamide–maleic anhydride

The thermal degradation of copolymer acrylamide–maleic anhydride prepared in various solvents (benzene, dioxane, methylethyl ketone) and different monomer ratios was investigated. The techniques of thermogravimetry (TG and DTG) and differential scanning calorimetry (DSC) were used. The IR spectra of degraded copolymers are discussed.     

Study of the thermal degradation of acrylic copolymers

The thermal degradation of the following copolymers prepared by radical polymerization: acrylonitrile–butyl acrylate–vinylidene chloride, acrylonitrile–butyl acrylate–vinylidene chloride–styrene, and acrylonitrile–methacrylic acid–vinylidene chloride–styrene was investigated. The techniques of thermogravimetry and differential thermal analysis were used. The IR spectra of degradated copolymers are discussed.     

Corrosion and biocompatibility of PPy/PEG coating electrodeposited on Ti6Al7Nb alloy

This work aims to improve the corrosion rate of Ti6Al7Nb alloy and to increase its biocompatibility at the same time, obtaining polymer composite films based on polypyrrole/polyethylene glycol (PPy/PEG). The elaboration method was electrodeposition. FT‐IR analysis was performed in order to emphasize the formation of the PPy‐PEG composite film by incorporating PEG into the polymer structure. The paper is focussed on PEG (400 molecular weight) effect on the corrosion in bioliquids (as tested electrochemical bioliquid was chosen Hank's balanced salt solution) and on the biocompatibility properties. The PPy film significantly improves the biocompatibility of the Ti6Al7Nb alloy. The PEG presence in the polymerization solution leads to more stable composite polymer films on the titanium alloy surface with a better corrosion resistance and a more hydrophilic behaviour comparing with the PPy film. The increase of cell viability and proliferation potential as compared to the PPy film is not important.