Biomimetic Calcium Phosphates Derived from Marine and Land Bioresources

This chapter aims to establish the key factors for technological optimization of biogenic calcium phosphate synthesis from marine and land resources. Three natural calcium sources—marble, seashell and bovine bone—were considered as raw materials. The proposed materials are suitable candidates for the synthesis of bone substitutes similar to the inorganic bone component. The synthesis processes were developed based on the investigations of thermal phenomena (TGA-DSC analysis) that can occur during thermal treatments. By this method, we were able to determine the optimum routes and temperatures for the complete dissociation of calcium carbonate as well as risk-free deproteinization of bovine bone. An exhaustive characterization, performed with modern and complementary techniques such as morphology (SEM), composition (EDS, XRF) and structure (FT-IR, XRD), is presented for each precursor. The final chemical composition of ceramic products can be modulated through a careful control of the key parameters involved in the conversion, in order to create long-term performant biphasic apatite biomaterials, with broad medical applicability. Identifying the suitable strategies for this modulation contributes to an appreciable advance in orthopedic tissue engineering

Synthesis and characterization of jellified composites form bovine bone-derived hydroxyapatite and starch as precursors for robocasting

Hydroxyapatite–starch composites solidify rapidly via jellification, making them suitable candidates for robocasting. However, many aspects related to hydroxyapatite powder characteristics, hydroxyapatite–starch interaction, and composites composition and properties need to be aligned with robocasting requirements to achieve a notable improvement in the functionality of printed scaffolds intended for bone regeneration. This article presents a preliminary evaluation of hydroxyapatite–starch microcomposites. Thermal analysis of the starting powders was performed for predicting composites’ behavior during heat-induced densification. Also, morphology, mechanical properties, and hydroxyapatite–starch interaction were evaluated for the jellified composites and the porous bodies obtained after conventional sintering, for different starch additions, and for ceramic particle size distributions. The results indicate that starch could be used for hydroxyapatite consolidation in limited quantities, whereas the composites shall be processed under controlled temperature. Due to a different mechanical behavior induced by particle size and geometry, a wide particle size distribution of hydroxyapatite powder is recommended for further robocasting ink development

Structure Effects over Behavior of Graphite Gray Iron in Running

The work aims at emphasizing the structure changes of graphite gray iron, as a result of make-casting conditions and their effects over behavior in running of several cast items. Researches consisted of complex characterization of several gray iron specimens sampled from damaged items comparatively to other suitable ones. Chemical composition, crack aspect, tensile strength, structure, kind, micro hardness of structural constituent were analyzed. Laboratory researches made by optical and electronic microscopy emphasized the showing up of some unsuitable structures with fragile structural constituents and areas unpurified by exogenous inclusions as well as degenerated graphite. All of these steady structural changes had a powerful fragility effect over the material. This fact was confirmed by mechanical characteristics and analysis of cracking area. Results corroborating allowed finding the causes of graphite gray iron cast items damage as a result of a faulty make-casting technological management and incomplete heating treatment

EDX Analysis of Laser Cladding Layers With Ni – Cr – B – Fe – Al Alloy

Multilayer cladding by injection of powder with 8.9% Cr, 4.5% Fe, 5.1% B, 2.4% Al, 0.6% Cu, Ni rest as chemical composition, in melted bath by a continuous wave CO2laser connected to x-y-z coordinate table was tested in order to increase the wear and corrosion resistance of 0.45% C superficial steel layers. Layers made by different laser running were characterized by microstructure analysis, microhardness analysis and EDS microanalysis in order to establish the optimal deposit running

Facile synthesis and characterization of hydroxyapatite particles for high value nanocomposites and biomaterials

Lately Hydroxyapatite has gained a lot of research interest and intense focus due to its structural as well as compositional similarity to the components of human bone mineral. The conversion of calcium-rich precursors to hydroxyapatite could lead to the development of a new sustainable alternative with a valuable environmental and socio-economically impact. Still, current approaches faces lots of challenges in terms of synthesis parameters compatible to a reproducible route for calcium phosphates (hydroxyapatite included) synthesis. The optimization of Rathje synthesis route and characterization of biogenic derived calcium phosphates from dolomitic marble and Mytilus galloprovincialis seashells, constitutes the main goals of this study. The synthesized materials were characterized using FTIR, SEM coupled with EDS, and X-ray diffraction at all synthesis stages. Precursors were also subjected to thermal analysis and differential scanning calorimetry for thermal transformations investigations and dissociation temperature setting. This study suggests that acid quantity and magnetic stirring are the key-factors for Ca/P molar ratio adjustment, hence for the amount of naturally-derived hydroxyapatite. This research also contributes to the development of new strategies for further optimization of the conversion procedure and removal of residual components

Fundamentals and scopes of doped carbon nanotubes towards energy and biosensing applications

Since their first allusion, carbon nanotubes have attracted significant research interest, especially with respect to composite manufacturing as a filler material for enhancing their mechanical and electrical properties. Several methods have been developed for modifying the electrical properties of carbon nanotubes such as CNTs wall's carbon atoms substitution with other appropriate atoms including engineering of their outer surfaces by covalent and noncovalent molecules, such as CNTs channel filling and nano-chemical reactions therein. CNTs with tailored electrical conduction open large perspectives for their applicabilities in advanced technologies. Taking into consideration the innovative advantages of pure and hybrid CNTs, in this article we have comprehensively reviewed the latest state-of-art research developments in the direction of different synthesis strategies, structure-property relationships, and advanced applications towards energy storage, supercapacitors, electrodes, catalytic supports, as well as biosensing

Biomaterials and Implant Biocompatibility

The scientific advances in life sciences and engineering are constantly challenging, expanding, and redefining concepts related to the biocompatibility and safety of medical devices. New biomaterials, new products, and new testing regimes are being introduced t