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51.
Anisoara Cimpean Simona Popescu Cristina M. Ciofrangeanu Alain N. Gleizes 《Materials Chemistry and Physics》2011
We report on the in vitro response of human gingival fibroblasts (HGF-1 cell line) to various thin films of titanium dioxide (TiO2) deposited on titanium (Ti) substrates by low pressure metal-organic chemical vapor deposition (LP-MOCVD). The aim was to study the influence of film structural parameters on the cell behavior comparatively with a native-oxide covered titanium specimen, this objective being topical and interesting for materials applications in implantology. HGF-1 cells were cultured on three LP-MOCVD prepared thin films of TiO2 differentiated by their thickness, roughness, transversal morphology, allotropic composition and wettability, and on a native-oxide covered Ti substrate. Besides traditional tests of cell viability and morphology, the biocompatibility of these materials was evaluated by fibronectin immunostaining, assessment of cell proliferation status and the zymographic evaluation of gelatinolytic activities specific to matrix metalloproteinases secreted by cells grown in contact with studied specimens. The analyzed surfaces proved to influence fibronectin fibril assembly, cell proliferation and capacity to degrade extracellular matrix without considerably affecting cell viability and morphology. The MOCVD of TiO2 proved effective in positively modifying titanium surface for medical applications. Surface properties playing a crucial role for cell behavior were the wettability and, secondarily, the roughness, HGF-1 cells preferring a moderately rough and wettable TiO2 coating. 相似文献
52.
Rashid Hameed Alain Sellier Anaclet Turatsinze Fr��d��ric Duprat 《International Journal of Mechanics and Materials in Design》2011,7(1):83-97
This contribution presents an effective and practical three dimensional (3D) numerical model to predict the behaviour of concrete
matrix reinforced with sliding metallic fibers. Considering fiber-reinforced concrete (FRC) as two-phase composite, constitutive
behaviour laws of plain concrete and sliding metallic fibers were described first and then they were combined according to
anisotropic damage theory to predict the mechanical behaviour of FRC. The behaviour law used for the plain concrete is based
on damage and plasticity theories able to manage localized crack opening in 3D. The constitutive law of the action of sliding
metallic fibers in the matrix is based on the effective stress carried by the fibers. This effective stress depends on a damage
parameter related to on one hand, on the content and mechanical properties of fibers and on the other hand, on the fiber–matrix
bond which itself depends on the localized crack opening. The proposed model for FRC is easy to implement in most of the finite
element codes based on displacement formulation; it uses only measurable parameters like Young’s modulus, tensile and compressive
strengths, fracture energies and strains at peak stress in tension and compression. A comparison between the experimental
data and model results has been also provided in this paper. 相似文献
53.
Mathieu Herran Daniel Nélias Alain Combescure Hervé Chalons 《International journal for numerical methods in engineering》2011,86(3):301-315
The component mode synthesis (CMS) with fixed interface (denoted Craig–Bampton) method uses a combination of static and dynamic modes. The usual definition of this CMS leads to a coupling between static and dynamic modes which are not orthogonal with respect to the stiffness matrix. This type of basis is not well suited for dynamic explicit computations, because the resulting mass matrix is not diagonal. If one keeps the same basis mode set but uses an orthogonalization process with respect to the mass matrix, the quality of the reduced Craig–Bampton system is kept but the basis vectors are combined differently. The aim of this paper is to propose a new way to control the accuracy of the reduced dynamic system for a specific frequency domain. Thus a new CMS is defined in order to be accurate in the medium frequency range. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
54.
In this work a new approach to the control of simulated moving bed (SMB) chromatographic separation processes is presented. This approach is based on the combination of the wave theory and Multi-Model Predictive Control (MMPC). The wave theory provides the theoretical framework in which the control law is formulated whereas receding-horizon MPC is used for determining the appropriate controller parameters. As SMB plants are distributed parameter systems (DPS) with nonlinearity arising from the expression of the adsorption isotherms, classical numerical methods for the solution of DPS are computationally demanding for MPC purposes. Reduced-order models are therefore derived using the proper orthogonal decomposition (POD) technique. To ensure stability, the POD model is updated on-line, resulting in MMPC. 相似文献
55.
Mass customization (MC) has become a reality and cannot be neglected as one of the leading strategies in satisfying customers and assuring companies survival in today's markets. MC can be offered either via product variability or process variability. How this is achieved using both approaches is the main core of this article. After an overview of related works, the influence of design variability on the overall generated value of the product is studied via a metric approach. A case study of the shoe industry is also presented, based on the experience of a European project called Dorothy. 相似文献
56.
Isabella S. Romero Nathan P. Bradshaw Jesse D. Larson Sean Y. Severt Sandra J. Roberts Morgan L. Schiller Janelle M. Leger Amanda R. Murphy 《Advanced functional materials》2014,24(25):3866-3873
Single‐component, metal‐free, biocompatible, electromechanical actuator devices are fabricated using a composite material composed of silk fibroin and poly(pyrrole) (PPy). Chemical modification techniques are developed to produce free‐standing films with a bilayer‐type structure, with unmodified silk on one side and an interpenetrating network (IPN) of silk and PPy on the other. The IPN formed between the silk and PPy prohibits delamination, resulting in a durable and fully biocompatible device. The electrochemical stability of these materials is investigated through cyclic voltammetry, and redox sensitivity to the presence of different anions is noted. Free‐end bending actuation performance and force generation within silk‐PPy composite films during oxidation and reduction in a biologically relevant environment are investigated in detail. These silk–PPy composites are stable to repeated actuation, and are able to generate forces comparable with natural muscle (>0.1 MPa), making them ideal candidates for interfacing with biological tissues. 相似文献
57.
René Köppel Thomas Bucher Alain Meuwly Dominik Moor 《European Food Research and Technology》2014,239(2):347-355
According to the release of authorization, several new transgenic soy crops are expected to be present in the harvest of soy beans. In contrast to earlier times, methods for the detection of these transgenic crops are available already in advance. However, these methods are mainly still inefficient single real-time PCR methods. To increase the efficiency of product control, a multiplex quantitative real-time PCR system was developed and characterized for the four new transgenic soy traits DP-356043-5, DP-305423-1, MON 87701 and BPS-CV127-9. It showed amplification efficiency, correlation and sensitivity similar to the single PCR systems applied therein. To evaluate the robustness, an appropriate testing scheme was developed and applied for the first time on this multiplex real-time PCR system. It showed the robust amplification of all analytes also in case where conditions were varied. This system allows relative multiplex quantification and/or delta–delta Ct method quantification and proofed the applicability in routine. 相似文献
58.
Serafino Teseo Emmanuel Lecoutey Daniel J. C. Kronauer Abraham Hefetz Alain Lenoir Pierre Jaisson Nicolas Châline 《Journal of chemical ecology》2014,40(5):429-438
Although cuticular hydrocarbons (CHCs) have received much attention from biologists because of their important role in insect communication, few studies have addressed the chemical ecology of clonal species of eusocial insects. In this study we investigated whether and how differences in CHCs relate to the genetics and reproductive dynamics of the parthenogenetic ant Cerapachys biroi. We collected individuals of different ages and subcastes from several colonies belonging to four clonal lineages, and analyzed their cuticular chemical signature. CHCs varied according to colonies and clonal lineages in two independent data sets, and correlations were found between genetic and chemical distances between colonies. This supports the results of previous research showing that C. biroi workers discriminate between nestmates and non-nestmates, especially when they belong to different clonal lineages. In C. biroi, the production of individuals of a morphological subcaste specialized in reproduction is inversely proportional to colony-level fertility. As chemical signatures usually correlate with fertility and reproductive activity in social Hymenoptera, we asked whether CHCs could function as fertility-signaling primer pheromones determining larval subcaste fate in C. biroi. Interestingly, and contrary to findings for several other ant species, fertility and reproductive activity showed no correlation with chemical signatures, suggesting the absence of fertility related CHCs. This implies that other cues are responsible for subcaste differentiation in this species. 相似文献
59.
Olivier Tingaud Ghislain Montavon Alain Denoirjean Jean-François Coudert Vincent Rat Pierre Fauchais 《Journal of Thermal Spray Technology》2010,19(1-2):207-218
Suspension plasma spraying (SPS) is an alternative to conventional atmospheric plasma spraying (APS) aiming at manufacturing thinner layers (i.e., 10-100 μm) due to the specific size of the feedstock particles, from a few tens of nanometers to a few micrometers. The staking of lamellae and particles, which present a diameter ranging from 0.1 to 2.0 μm and an average thickness from 20 to 300 nm, permits to manufacture finely structured layers. Moreover, it appears as a versatile process able to manufacture different coating architectures according to the operating parameters (suspension properties, injection configuration, plasma properties, spray distance, torch scan velocity, scanning step, etc.). However, the different parameters controlling the properties of the coating, and their interdependences, are not yet fully identified. Thus, the aim of this paper is, on the one hand, to better understand the influence of operating parameters on the coating manufacturing mechanisms (in particular, the plasma gas mixture effect) and, on the other hand, to produce Al2O3-ZrO2 finely structured layers with large varieties of architectures. For this purpose, a simple theoretical model was used to describe the plasma torch operating conditions at the nozzle exit, based on experimental data (mass enthalpy, arc current intensity, thermophysical properties of plasma forming gases, etc.) and the influences of the spray parameters were determined by mean of the study of sizes and shapes of spray beads. The results enabled then to reach a better understanding of involved phenomena and their interactions on the final coating architectures permitting to manufacture several types of microstructures. 相似文献
60.
This article addresses the calculation of the effectiveness of a single-pass cross-flow heat exchanger where the two fluids are not mixed. The author proposes an exact formula which is more convenient than using infinite series expansions as has been proposed until now. 相似文献