Effects of Mg-Doping and of Reinforcing Multiwalled Carbon Nanotubes Content on the Structure and Properties of Hydroxyapatite Nanocomposite Ceramics

Surfactant-assisted hydrothermal synthesis of magnesium-doped hydroxyapatite (Ca10-xMgx(PO4)(6)(OH)(2)) with 0x1) was realized in aqueous solution at 90 degrees C. -TCP phase was formed in the Mg-0.6-HA sample after heat treatment at 1000 degrees C. Magnesium was found to degrade the sintering ability of Mg-x-HA ceramics. Flexural strength (sigma(f)) was found to decrease as a function of Mg-doped HA. The using of carbon nanotubes as reinforcing agents mitigated the strength loss of Mg-HA ceramics. The flexural strength of Mg-0.6-HA was then increased by nearly 20% from approximately 33 to 39MPa with an optimum addition of 3wt% of multi-walled nanotubes

Intermediate-range Casimir-Polder interaction probed by high-order slow atom diffraction

International audienceAt nanometer separation, the dominant interaction between an atom and a material surface is the fluctuation-induced Casimir-Polder potential. We demonstrate that slow atoms crossing a silicon nitride transmission nanograting are a remarkably sensitive probe for that potential. A 15% difference between nonretarded (van der Waals) and retarded Casimir-Polder potentials is discernible at distances smaller than 51 nm. We discuss the relative influence of various theoretical and experimental parameters on the potential in detail. Our work paves the way to high-precision measurement of the Casimir-Polder potential as a prerequisite for understanding fundamental physics and its relevance to applications in quantum-enhanced sensing

Fostering Hydroxyapatite Bioactivity and Mechanical Strength by Si-Doping and Reinforcing with Multiwall Carbon Nanotubes

The aim of the present study was to prepare resorbable hydroxyapatite (HA) based bone graft materials reinforced with carbon nanotubes as a way to cope with the inability of pure HA to resorb and its intrinsic brittleness and poor strength that restrict its clinical applications under load-bearing conditions. With this purpose, a Si-doped HA nanopowder (n-Si(0.8)HA) was prepared by chemical synthesis and used as composite matrix reinforced with different amounts of functionalized multiwall carbon nanotubes (MWCNTs). The effect of the added amounts of MWCNTs on the mechanical properties of nanocomposites and their in vitro biomineralization was assessed by bending strength measurements, immersing tests in simulated body fluid solution (SBF), scanning electron microscopy (SEM), and inductively coupled plasma atomic emission spectroscopy analysis (ICP-AES). The bioactivity and bending strength were enhanced, reaching maximum balanced values for an optimum addition of 3 wt.% f-MWCNTs. These results might contribute to broaden the potential applications of HA-based bone grafts

Hydrothermal Synthesis and Appraisal of Mg-Doped Hydroxyapatite Nanopowders

Nano rods of magnesium-doped hydroxyapatite, Ca10-xMgx(PO4)(6)(OH)(2)(Mg-x-HA, x = 0-1.0), were successfully synthesized through cetyltrimethyl ammonium bromide assisted hydrothermal synthesis method. X-ray diffraction, infrared spectroscopy, thermogravimetric analysis and transmission electron microscopy, provided experimental evidences about the effects of Mg-doping on the phase assemblage, crystallite size, morphology, specific surface area of Mg-doped hydroxyapatite nanopowders. The replacement Ca2+ ions by smaller Mg2+ ones caused lattice shrinkage and lattice strains that enhanced the solubility and the in vitro bio-mineralisation activity upon immersing sintered samples in simulated body fluid. The severity of these structural changes rose with increasing Mg-doping and enable tailoring the in vitro biological activity enabling selecting the most suitable material for bone grafts and tissue engineering applications

Integrated capture process for purification of plasmid DNA based on aqueous two phase separation

Facility systems may be vulnerable to a disaster, whether caused by intention, an accident, or by an act of nature. When disrupting events do occur, services may be degraded or even destroyed. This chapter addresses problems of disruption associated with facility based service systems. Three main questions often arise when dealing with a possible disaster: 1) how bad can it get? 2) is there a way in which we can protect our system from such an outcome? and 3) is there a way in which we can incorporate such issues in our future designs and plans? This chapter addresses each of these main questions with respect to several classic location problems. Specifically, it discusses recent location models under disaster events along three main streams of research: facility interdiction, facility protection, and resilient design