Computational mechanics has been advanced in every area of orthopedic biomechanics. The objective of this paper is to provide a general review of the computational models used in the analysis of the mechanical function of the knee joint in different loading and pathological conditions. Major review articles published in related areas are summarized first. The constitutive models for soft tissues of the knee are briefly discussed to facilitate understanding the joint modeling. A detailed review of the tibiofemoral joint models is presented thereafter. The geometry reconstruction procedures as well as some critical issues in finite element modeling are also discussed. Computational modeling can be a reliable and effective method for the study of mechanical behavior of the knee joint, if the model is constructed correctly. Single-phase material models have been used to predict the instantaneous load response for the healthy knees and repaired joints, such as total and partial meniscectomies, ACL and PCL reconstructions, and joint replacements. Recently, poromechanical models accounting for fluid pressurization in soft tissues have been proposed to study the viscoelastic response of the healthy and impaired knee joints. While the constitutive modeling has been considerably advanced at the tissue level, many challenges still exist in applying a good material model to three-dimensional joint simulations. A complete model validation at the joint level seems impossible presently, because only simple data can be obtained experimentally. Therefore, model validation may be concentrated on the constitutive laws using multiple mechanical tests of the tissues. Extensive model verifications at the joint level are still crucial for the accuracy of the modeling.

Rapid removal of noxious synthetic dyes from wastewater is of great concern in the scientific research field, this is due to the expansion of harmful effects of synthetic dyes traces in water streams on the environment and human health with the exponential rise in concentration of synthetic dye globally and demand in various industries that coincided with the implantation of more stringent water quality standards. Various technologies have been applied for the removal of synthetic dye from wastewater, including adsorption technology, which has a great potential in treating varieties of synthetic dyes. This article comprehensively reviews the latest progress in the development of carbon nanotubes (CNTs) and their applications for the removal of synthetic dyes from wastewater, including functionalized of CNTs and their researched counterparts. The emerging trends in the development of alternative adsorbents with different substrates, morphologies, and functional groups are also elucidated.

The magnetic NiFe2O4 nanoparticles have been synthesized and used as adsorbents for removal of an azo dye, Eriochrome black-T (EBT) from aqueous solution. The NiFe2O4 nanoparticles were characterized by scanning electron microscope (SEM), Transmission electron microscope (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectra (FTIR). The adsorption studies were carried out under various parameters, such as pH, adsorbent dosage, contact time and initial dye concentration. The experimental results show that the percentage of adsorption increases with an increase in the adsorbent dosage. The maximum adsorption occurred at the pH value of 6.0. The equilibrium uptake was increased with an increase in the initial dye concentration in solution. Adsorption kinetic data were properly fitted with the pseudo-second-order kinetic model. The experimental isotherms data were analyzed using Langmuir and Freundlich isotherm equations. The best fit was obtained by the Langmuir model with high correlation coefficients (R2 = 0.9733) with a maximum monolayer adsorption capacity of 47.0 m g/g.

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Magnetic nanoparticles iron oxide with average sizes of 6 nm were synthesized by a chemical coprecipitation method from mixtures of FeCl 2 Á4H 2 O and FeCl 3-6H 2 O. For preparation, multi-walled carbon nanotubes (MWCNTS) with outer diameter of 50 nm, wall thickness from 1 to 2 nm and length from 500-2,000 nm were used. Characterization of the MWCNT-Fe 3 O 4 by X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), thermo-gravimetric analysis (TGA) and magnetic characterization was conducted on a vibrating sample magnetometer (VSM).