Influence of the 316 L stainless steel interface on the stability and barrier properties of plasma fluorocarbon films

Coatings are known to be one of the more suited strategies to tailor the interface between medical devices and the surrounding cells and tissues once implanted. The development of coatings and the optimization of their adhesion and stability are of major importance. In this work, the influence of plasma etching of the substrate on a plasma fluorocarbon ultrathin coating has been investigated with the aim of improving the stability and the corrosion properties of coated medical devices. The 316 L stainless steel interface was subjected to two different etching sequences prior to the plasma deposition. These plasma etchings, with H(2) and C(2)F(6) as gas precursors, modified the chemical composition and the thickness of the oxide layer and influenced the subsequent polymerization. The coating properties were evaluated using flat substrates submitted to deformation, aging into aqueous medium and corrosion tests. X-ray photoelectron spectroscopy (XPS), time of flight-secondary ion mass spectrometry (ToF-SIMS), ellipsometry, and atomic force microscopy (AFM) were performed to determine the effects of the deformation and the aging on the chemistry and morphology of the coated samples. Analyses showed that plasma etchings were essential to promote reproducible polymerization and film growth. However, the oxide layer thinning due to the etching lowered the corrosion resistance of the substrate and affected the stability of the interface. Still, the deformed samples did not exhibited adhesion and cohesion failure before and after the aging.     

A texture discretization technique adapted to polycrystalline aggregates with non-uniform grain size

This paper presents a new procedure for the sampling of crystallographic textures into discrete lattice orientations. The method is, for example, useful in order to assign initial grain orientations in crystal-plasticity-based finite element simulation of forming processes. The discretization technique ensures that the orientation sampling is statistically representative of a known orientation distribution function (ODF). Contrary to previous discretization techniques, the new method is valid also when the model microstructure consists of grains with non-uniform size. The accuracy of the texture representation is assessed in the case of cold rolled IF steel. Crystal plasticity theory coupled to finite element modeling is used to predict mechanical planar anisotropy of the sheet. Comparison is made between model predictions assuming, respectively, a uniform or a heterogeneous grain-size distribution.     

Tracking individual kinesin motors in living cells using single quantum-dot imaging

We report a simple method using semiconductor quantum dots (QDs) to track the motion of intracellular proteins with a high sensitivity. We characterized the in vivo motion of individual QD-tagged kinesin motors in living HeLa cells. Single-molecule measurements provided important parameters of the motor, such as its velocity and processivity, as well as an estimate of the force necessary to carry a QD. Our measurements demonstrate the importance of single-molecule experiments in the investigation of intracellular transport as well as the potential of single quantum-dot imaging for the study of important processes such as cellular trafficking, cell polarization, and division.     

TEM observations and finite element modelling of channel deformation in pre-irradiated austenitic stainless steels - Interactions with free surfaces and grain boundaries

Transmission electron microscopy (TEM) observations show that dislocation channel deformation occurs in pre-irradiated austenitic stainless steels, even at low stress levels (∼175 MPa, 290 °C) in low neutron dose (∼0.16 dpa, 185 °C) material. The TEM observations are utilized to design finite element (FE) meshes that include one or two “soft” channels (i.e. low critical resolved shear stress (CRSS)) of particular aspect ratio (length divided by thickness) embedded at the free surface of a “hard” matrix (i.e. high CRSS). The CRSS are adjusted using experimental data and physically based models from the literature. For doses leading to hardening saturation, the computed surface slips are as high as 100% for an applied stress close to the yield stress, when the observed channel aspect ratio is used. Surface slips are much higher than the grain boundary slips because of matrix constraint effect. The matrix CRSS and the channel aspect ratio are the most influential model parameters. Predictions based on an analytical formula are compared with surface slips computed by the FE method. Predicted slips, either in surface or bulk channels, agree reasonably well with either atomic force microscopy measures reported in the literature or measures based on our TEM observations. Finally, it is shown that the induced surface slip and grain boundary stress concentrations strongly enhance the kinetics of the damage mechanisms possibly involved in IASCC.     

Work Extrinsic and Intrinsic Motivation Scale: Its value for organizational psychology research.

[Correction Notice: An erratum for this article was reported in Vol 42(1) of Canadian Journal of Behavioural Science/Revue canadienne des sciences du comportement (see record 2009-25142-008). In this article, line 2 of the second table was missing from the printed article. The correct table is reprinted in this correction.] The Work Extrinsic and Intrinsic Motivation Scale (WEIMS) is an 18-item measure of work motivation theoretically grounded in self-determination theory (Deci & Ryan, 2000). The purpose of the present research was twofold. First, the applicability of the WEIMS in different work environments was evaluated. Second, its factorial structure and psychometric properties were assessed. Two samples of workers (military: N = 465; civilians: N = 192) voluntarily completed questionnaires. Using the WEIMS’s 3 indexes (work self-determination index, work self-determined and nonself-determined motivation, respectively), results of regression analyses were supportive of its ability to predict positive and negative criteria in the workplace. Results also showed the adequacy of both its construct validity and internal consistency. Its factorial structure was also invariant across samples. Finally, its quasi-simplex pattern and relationships with psychological correlates further supported the self-determination continuum. Overall, these findings provide evidence for the applicability as well as the reliability and validity of the WEIMS in organisational settings. Results are discussed in regard to the applicability of self-determination theory to the workplace. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

神奇玉米屋

这是Archi〈20的一个获奖项目。借助7000欧元的项目预算,这座占地20m^2的住宅原型修建在法国东北部慕泰索尔斯村上的自然保护区内。它遵循简单的创成式外形设计——即一个能够观察到四周景观的圆圈。     

Acknowledgement of Referees

The management of land resources, particularly the role of planning regulations, is critical in defining what land can be used in urban development – and this throws up certain key questions: How can one best manage land resources available? How can one address future urban development needs on the basis of existing land from a sustainable perspective? In this article we propose to question the extent of planning theories in the light of concrete urban development using land availability information. By using comprehensive national data we explore the case of Luxembourg, a small European country facing exacerbated pressures for metropolitanization. We use scenarios that go from a lesser to a greater degree of sustainability in order to project and articulate different configurations of land consumption based on a critical literature review (Smart Growth, New Urbanism, and transit oriented development (TOD)). We explore how modelling might be used to help inform spatial planning for urban growth. This framework is intended as an approach that would be applicable to other urban settings by using data that can be found in any typical municipal authority along with implementation in a geographical information system (GIS). The results create a tool which is useful for planning, monitoring or forecasting land consumption. The results also clearly show the limited impact of planning practices in terms of sustainability using land availability.     

Consolidation by spark plasma sintering of polyimide and polyetheretherketone

This article presents two high‐temperature thermoplastic powders which were sintered by spark plasma sintering in order to get homogeneous mechanical properties. Dense polyimide (PI) and polyetheretherketone (PEEK) specimens were obtained at temperatures as low as 320°C for PI and 200°C for PEEK, respectively. Relative densities higher than 99% were reached for both materials. In order to characterize their properties, in situ measurements with compression and hardness tests were carried out on sintered samples. This method allowed to obtain polymeric materials with improved mechanical properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40783.     

Pressure drop measurements and modeling on SiC foams

Foam-structured beds are likely to be the next generation of catalyst supports due to their interesting specific properties (large exchange area, low pressure drop, easy control of external porosity, etc.). Nevertheless, chemical engineering parameters of this new catalyst support types are still not completely clear for the scientific community and many approaches are attempted to solve this problem. SiC foams offer the dual advantages of the interesting properties of structured beds and the intrinsic thermal and mechanical properties of silicon carbide as a catalytic support. In the present work, the problem of pressure drops along foam beds is studied with a new simplistic geometrical model as a first step in the understanding of the peculiar hydrodynamic behavior of SiC foams in chemical processes. The proposed model was successfully validated by experimental results on a relatively large range of parameters which fully confirm the validity of the model.     

Synthesis and Preliminary Tests of Suspension Plasma Spraying of Fine Hydroxyapatite Powder

The synthetic hydroxyapatite (HA, Ca₁₀(PO₄)₆(OH)₂) is a very useful biomaterial for numerous applications in medicine, such as e.g., fine powder for suspension plasma spraying. The powder was synthesized using aqueous solution of ammonium phosphate (H₂(PO₄)NH₄) and calcium nitrate (Ca(NO₃) · 4H₂O) in the carefully controlled experiments. The synthesized fine powder was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The powder was formulated into water and alcohol based suspension and used to carry out the initial tests of plasma spraying onto titanium substrate. The phase analysis of sprayed coating was made with the XRD.