The effect of surface treatments on the adhesion of electrochemically deposited hydroxyapatite coating to titanium and on its interaction with cells and bacteria

The effect of different mechanical and chemical pre-treatments on the adhesion strength of hydroxyapatite (HAp) coating on a commercially pure titanium (CP-Ti) substrate was studied by means of a standard tensile test followed by microscopic and chemical analysis to determine the locus of fracture. In addition, the effects of either these pre-treatments or post-treatment by low-energy electron irradiation, which allowed tuning the wettability of the surface, on both osteoblast progenitor attachment and S. aureus bacteria attachment were investigated. A dedicated program was developed for unambiguous identification and count of stained cells. A single-phase HAp coating was formed by electrodeposition. A series of surface pre-treatments consisted of grinding down to P1000, etching in HNO₃/HF solution, grit blast, soaking in NaOH and subsequent heat treatment provided the highest adhesion strength to the HAp coating. Osteoblast progenitors derived from rats may be attached preferentially to a hydrophilic surface (post-treatment to θ = 30°), while the bacteria seemed to be less attached to hydrophobic surfaces (post-treatment to θ = 105°). However, the results were not statistically different. The bacteria seemed to be less attached to the smoother, uncoated surfaces.     

Memory effects in the structure silicon single crystal-ferroelecltric film

The memory effects in the structure: (Ba Sr) TiO₃ film-silicon single crystal have been studied, It is shown that for explaining them it is necessary to take into account both the natural unipolarity of (Ba, Sr) TiO₃ film and the injection of carriers from Si. In terms of the results obtained a conclusion has been made on the possibility of using such structures as currentless cells memory for long-term storage of information.     

Differential theory of diffraction by finite cylindrical objects

We present a differential theory for solving Maxwell equations in cylindrical coordinates, projecting them onto a Fourier-Bessel basis. Numerical calculations require the truncation of that basis, so that correct rules of factorization have to be used. The convergence of the method is studied for different cases of dielectric and metallic cylinders of finite length. Applications of such a method are presented, with a special emphasis on the near-field map inside a hole pierced in a plane metallic film.     

The Formation of Mn-Ce Oxide Catalysts for CO Oxidation by Oxalate Route: The Role of Annealing Conditions

Catalysis Letters - A series of Mn-Ce oxide catalysts with Mn:Ce?=?1 was synthesized by oxalate route under different annealing conditions. The physicochemical properties were...     

Design of a packaging-friendly double-topology RF MEMS switch for space applications

Microsystem Technologies - This article presents the results of the research, design and a series of manufacturing steps of an RF-MEMS switch to be used in space communication systems. Design and...     

Strong and super tough: Layered ceramic‐polymer composites with bio‐inspired morphology

Bio‐inspired layered ceramic‐polymer composites with high strength and toughness were prepared from sintered aluminum oxide ceramic sheets and cationically curing epoxy resins toughened with poly(ε‐caprolactone) (PCL). The architecture of the composite is inspired by nacre but is arranged on a larger scale. Ceramic sheets with a nominal thickness of 250 μm were assembled into composite plates by adhesive layers with a nominal thickness of 20 μm. Before the manufacturing of the composites, the stress‐strain properties of the polymer component were tailored by the variation in the PCL content between 0 and 39 wt%. For composites with 4 and 15 ceramic layers, the bending strengths achieved 327 MPa and 376 MPa, which are higher than that of pure ceramic sheets. Moreover, composites with 15 ceramic layers show a 16 times higher toughness compared to that of the pure ceramic sheets. The results indicate that the toughness of the layered composites increases significantly with the number of layers. Inspired by the geometrical ratio of the natural sheet composite nacre, we have achieved a similar strength but a 2 times higher toughness than nacre by only adding up to 6 vol% of the polymer.     

Random laser action of ZnO@mesoporous silicas

ZnO@mesoporous silica nanocomposite was prepared by the impregnation method, and very efficient laser action was highlighted. As revealed by high-resolution transmission electron microscopy (HR-TEM), nanometric ZnO particles are confined inside the mesochannels of CMI-1 mesoporous silicas. Upon excitation at 3.6?eV of a femtosecond pulsed laser and at low pumping intensity, the ZnO@mesoporous silica showed a broad photoluminescence (PL) band corresponding to the excitonic recombination of ZnO. When the pumping intensity is increased up to a threshold (2.5?mJ?cm(-2)), the excitonic emission turns to stimulated emission through a mechanism which will be discussed. The same threshold value was obtained with another excitation source and nanocomposites with different ZnO loadings inside the CMI-1 mesoporous silica. These results allow a better understanding of the random laser effect in ZnO@mesoporous silica and, consequently, a model has been proposed to explain this phenomenon. Based on these new observations, many new applications can be considered since short-wavelength devices are required by industry to design new information storage supports.