With the growing demands for bone implant therapy, titanium (Ti) and its alloys are considered as appropriate choices for the load-bearing bone implant substitutes. However, the interaction of bare Ti-based implants with the tissues is critical to the success of the implants for long-term stability. Thus, surface modifications of Ti implants with biocompatible hydroxyapatite (HAp) coatings before implantation is important and gained interest. Sol-gel is a potential technique for deposition the biocompatible HAp and has many advantages over other methods. Therefore, this review strives to provide widespread overview on the recent development of sol-gel HAp deposition on Ti. This study shows that sol-gel technique was able to produce uniform and homogenous HAp coatings and identified the role of surface pretreatment of Ti substrate, optimizing the sol-gel parameters, substitution, and reinforcement of HAp on improving the coating properties. Critical factors that influence on the characteristics of the deposited sol-gel HAp films as corrosion resistance, adhesion to substrate, bioactivity, morphological, and structural properties are discussed. The review also highlights the critical issues, the most significant challenges, and the areas requiring further research.

Molecularly imprinted polymers have emerged as cost-effective and rugged artificial selective sorbents for combination with different sensors. In this study, quaternary ammonium cations, as functional monomers, were systematically evaluated to design imprinted polymers for glyphosate as an important model compound for electrically charged and highly water-soluble chemical compounds. To this aim, a small pool of monomers were used including (3-acrylamidopropyl)trimethylammonium chloride, [2-(acryloyloxy)ethyl]trimethylammonium chloride, and diallyldimethylammonium chloride. The simultaneous interactions between three positively charged monomers and glyphosate were preliminary evaluated using statistical design of the experiment method. Afterwards, different polymers were synthesized at the gold surface of the quartz crystal microbalance sensor using optimized and not optimized glyphosate-monomers ratios. All synthesized polymers were characterized using atomic force microscopy, contact angle, Fourier-transform infrared, and X-ray photoelectron spectroscopy. Evaluated functional monomers showed promise as highly efficient functional monomers, when they are used together and at the optimized ratio, as predicted by the statistical method. Obtained results from the modified sensors were used to develop a simple model describing the binding characteristics at the surface of the different synthesized polymers. This model helps to develop new synthesis strategies for rational design of the highly selective imprinted polymers and to use as a sensing platform for water soluble and polar targets.

Copper-graphite composite is one of the most important copper based composites, which is used, widely in electrical applications due to its excellent conductivity and high wear resistant. In this work, an attempt has been made to improve the multi-performance characteristics of copper graphite composite prepared by powder metallurgy and increase its expected life by optimizing the manufacturing process of this composite using statistical method. The experiments were carried out under various conditions of compacting pressure, sintering temperature and graphite content based on L9 orthogonal array. The experimental results indicated that multi-performance characteristics of the prepared composite such as electrical conductivity, densification and wear rate are influenced significantly by the studied parameters and the optimal process parameters level for optimum multi-performance characteristics was obtained in a compaction pressure of 750 MPa, sintering temperature of 950 °C and 10 Vol.-% of graphite content.

Recently, closed cell aluminum foam gained increasing attention in many industries due to its high stiffness compared with its very low density. The development of manufacturing foamed parts is very important for both industrial and scientific purposes. In this work, an attempt to enhance the essential characteristics of aluminum foam i.e., compressive strength and porosity level was carried out by optimizing the manufacturing parameters using statistical techniques. The aluminum foam was prepared under various conditions of calcium carbonate content, alumina content, foaming temperature and stirring time based on Screening experimental design. Analysis of variances was performed to evaluate the roles of each factor in influencing on foam properties and identifying their optimized values. In addition, Mathematical models based on quadratic regression model were developed to predict the responses. The results revealed that all selected parameters are significant, however, calcium carbonate content is the most effective factor in the process. The optimization results showed the ability to produce high quality aluminum foams with 2.86 MPa compressive strength and 80.4% porosity level by using the optimized fabrication parameters and these results have a permissible error percentage compared with the experimental results.

The alloy of nickel aluminum bronze (NAB) presents superior properties such as highstrength, excellent wear resistance and corrosion resistance, so it’s used in a wide range ofengineering applications. Usually, this material undergo to a series of machining processesto achieve the final shape. In this paper, NAB alloy reinforced with cubic boron nitride(CBN) particles was fabricated by powder metallurgy route. Design of experiments has beenused to study the effect of main turning parameters on the main cutting force for NAB-CBNcomposite. Numerical modelling was developed to predict the main cutting force requiredduring turning process under different machining conditions. The results of numerical modelshowed that the maximum error comparing with the experiment results is not exceed13.86%, which suggests that the developed model are reasonable. Optimization ofmachining process parameters was done using response surface method.

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