Despite the fact that soccer is one of the most popular sports in the world, little attention has been paid to this game scientifically which could otherwise provide a broad range of interesting outcomes. Sport equipment has a significant effect on how a game is played. Different features of the soccer ball such as its size, structure, weight and potential incoming pressure also affect the nature and quality of the game. Different models of soccer balls have been developed with the aim of increasing game quality and performance. Many scholars have investigated the displacements during typical soccer games caused by the ball impulse and the feet, but few studies have focused on the interaction between the ball and the feet. The aim of the present study is, thus, to investigate tension development and possible deformations caused by kicking the ball. Players who are well aware of soccer rules and have a little knowledge about soccer-induced injuries easily realize that the impulse of a non-standard ball considering its material, size or weight may severely damage the knees or other body parts. Due to the importance of the issue, to evaluate the impact of the soccer ball on the footballer’s feet, two finite element models of typical soccer balls have been studied with respect to the standard features of the real soccer ball in the three layers of leather, thread and rubber. The first model is proportional to the mass of the standard ball and the second incorporates a mass less than the standard level. Two models of bones are used in the present study: a single layer bone and a two-layer bone with cortical and cancellous tissues. For better understanding of the injuries resulting from the impulse from a non-standard ball, the used finite element software employs mechanic laws of sport biomechanics to provide better understanding of the details using mathematical modeling, computer simulation and experimental measurements. In this regard, this significant point is achieved through modeling the ball impulse to the feet which is quite complex and needs some simplification. As the soccer ball is flexible, most of the force is absorbed by the model’s flexibility. In the other model with a less flexible ball, the force absorbed by the bone is significantly more. تفاصيل المقالة

Nowadays, the placement of artificial prostheses in human skeleton, etc. is common due to different reasons such as fractures or deficiencies. Prostheses are structures that assist the performance of organs by reconstruction of some body parts through different methods to enable the organ to re-obtain its performance completely or partially and, since the use of external prostheses might lead to issues such as severe traumas, slow recovery and imposition of enormous hospital costs on the patient, therefore, use of internal prostheses can be an effective method for accelerating the process of improvement for the patient. By using CT-scan photos of a 54-year-old man weighing 60 kg and with a femur length of 36 centimeters, and also using a titanium prosthesis with diameters equaling 9 and 13 mm along with screws with diameters of 4 mm whose placement are with angles of ±4, ±4 and ±36 degrees, the geometry of the model has been provided and the model has been analyzed through the finite element method. Results indicated that in case of using the prosthesis with the diameter of 13 mm and screws of 4 mm with angle of +36, the least stress will be imposed on the bone and prosthesis. تفاصيل المقالة

Zirconium oxide has found extensive applications in various industries because
of its excellent properties such as high strength; high-temperature resistance;
extraordinary wearing resistance; ionic conductivity; and corrosion resistance. Also, some
Properties like high melting point, high mechanical and thermal strength, high dielectric
constant and low conductivity have introduced this material as a prominent candidate for
engineering applications. In this study, zirconium oxide (ZrO2) Nano fibers was
synthesized by calcination of propoxide zirconium oxide/polyvinyl alcohol using sol-gel
and electrospinning methods. The morphology of the Nano fibers was verified by
scanning electron microscopy (SEM) and its crystalline phase was investigated by x-ray
diffraction and energy-dispersive x-ray spectroscopy (EDS). The mean diameter of the
Nano fibers varied in the range of 70-200 nm. XRD patterns also indicated the presence
of monoclinic and tetragonal phases in the Nano fibers calcined at 700 ℃. Results also
revealed that this new precursor can be used in the electrospinning technique to obtain
ZrO2 Nano fibers with relatively high purity. تفاصيل المقالة