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CONTENTS
Volume 4, Number 1, March 2019
 

Abstract
The aim of this study was to investigate the effect of total polymer concentration on the chemical structure, morphology of pores, porosity, swelling ratio, degradation of gelatin-poly (vinyl alcohol) (Gel-PVA) cryogel scaffolds. Porous cryogels were prepared with cryogelation technique by using glutaraldehyde as a crosslinker. Functional group composition of cryogels after crosslinking was investigated by Fourier Transform Infrared (FTIR). The morphology of cryogels was characterized via scanning electron microscopy (SEM) and porosity analysis. All of the cryogels had a porous structure with an average pore size between 45.58

Key Words
gelatin; poly (vinyl alcohol); cryogel; scaffold; tissue engineering

Address
Seda Ceylan, Didem Demir, Gülşah Gül and Nimet Bölgen: Department of Chemical Engineering, Mersin University, Mersin, Turkey
Seda Ceylan: Department of Bioengineering, Adana Science and Technology University, Adana, Turkey

Abstract
Living beings are formed of advanced biological and mechanical systems which exist for millions of years. It is known that various animals and insects right from small ants to huge whales have different weight carrying capacities, which is generally expressed as a ratio of their own bodyweights i.e., Strength to Bodyweight Ratio (SBR). The puzzle is that when a rhinoceros beetle (scientific name: Dynastinae) can carry 850 times its own bodyweight, why a man cannot accomplish the same feat. There are intrinsic biological and mechanical reasons related to their capacities, as per biomechanics. Yet, there are underlining principles of engineering and structural mechanics which tend to solve this puzzle. The paper attempts to give a plausible answer for this puzzle through structural mechanics and experimental modeling techniques. It is based on the fact that smaller an animal or creature, it has larger value of weight lifting by self-weight ratio. The simple example of steel prism model discussed in this paper, show that smaller the physical model size, larger is its SBR value. To normalize this, the basic length of the model need to be considered and when multiplied with SBR, a constant is arrived. Hence, the aim of the research presented is to derive this constant on a pan-living being spectrum through size/scaling effect.

Key Words
animal behavior; strength to bodyweight ratio; load carrying capacity; biomechanics; structural mechanics; size/scaling effect

Address
Balamonica K: Department of Civil and Environmental Engineering, National University of Singapore, Singapore
T. Jothi Saravanan: Department of Civil Engineering, Yokohama National University, Japan
C. Bharathi Priya: CSIR-Structural Engineering Research Center, India
N. Gopalakrishnan: CSIR- Central Building Research Institute, Roorkee, India

Abstract
Eggshell is a waste material after the usage of egg. In this work, biowaste chicken eggshells were used for preparing carbonated hydroxyapatite (HA) nanoparticles of high purity through aqueous precipitation method at room temperature. The eggshell-derived HA will be a cost-effective bioceramics for biomedical applications and an effective material-recycling technology. Additionally, mulberry leaf extract was used as a template to regulate the morphology, size and crystallinity of HA, and the effects of pH value were also examined. Characterization of the samples was performed by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. Scanning electron microscopy (SEM) was used to determine the size, shape and morphology of HA. The results indicate that only one phase of HA were synthesized in the both absence and presence of mulberry leaf extract at pH of 7 and above, while DCPD or DCPA/DCPD phase was observed at pH 4 condition. The crystallite sizes of the HA samples obviously decreased when adding mulberry leaf extract as a template, while they decreased gradually as the solution pH levels increased. With increasing pH level from 7 to 14, the rod-like HA nanoparticles gradually changed to spherical shape at pH 14. Note that, the obtained product is Mg and Sr containing A- and B-type carbonate HA at alkaline pH and it can be a potential material for biomedical applications.

Key Words
eggshell; mulberry leaf extract; hydroxyapatite; precipitation method; pH value

Address
Shih-Ching Wu, Hsueh-Chuan Hsu, Shih-Kuang Hsu:Department of Dental Technology and Materials Science, Central Taiwan University of
Science and Technology, 666, Buzih Rd., Beitun District, Taichung 40601, Taiwan

Mei-Yi Liu and Wen-Fu Ho: Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung, 700 Kaohsiung University Rd., Nanzih District, Kaohsiung 81148, Taiwan

Abstract
This paper presents a novel structural composition for artificial bone scaffolds with an appropriate biocompatibility and biodegradability capability. To achieve this aim, carbon nanotubes, due to their prominent mechanical properties, high biocompatibility with the body and its structural similarities with the natural bone structure are selected in component of the artificial bone structure. Also, according to the piezoelectric properties of natural bone tissue, the barium titanate, which is one of the biocompatible material with body and has piezoelectric property, is used to create self-healing ability. Furthermore, due to the fact that, most of the bone tissue is consists of hydroxyapatite, this material is also added to the artificial bone structure. Finally, polycaprolactone is used in synthetic bone composition as a proper substrate for bone growth and repair. To demonstrate, performance of the presented composition, the mechanical behaviour of the bone scaffold is simulated using ANSYS Workbench software and three dimensional finite element modelling. The obtained results are compared with mechanical behaviour of the natural bone and the previous bone scaffold compositions. The results indicated that, the modulus of elasticity, strength and toughness of the proposed composition of bone scaffold is very close to the natural bone behaviour with respect to the previous bone scaffold compositions and this composition can be employed as an appropriate replacement for bone implants.

Key Words
artificial bone scaffold; carbon nanotube; hydroxyapatite; polycaprolactone; barium titanate; finite element analysis

Address
Department of Mechanical Engineering, Marvdasht Branch, Islamic Azad University, Marvdasht, Iran

Abstract
In the present article, the general wave propagation behavior of a single lamellae biological system was analyzed. The Lamellae is the main component of cortical bone. Its shape can be approximated by a cylindrical shell; so with using shell theories as displacement relations and the nonlocal strain gradient theory (NSGT) as constitutive relation was obtained the equation of motion. Using the NSGT leads to the effectiveness of scale parameter on equations of motion and the obtained results. The governing equations are derived by Hamilton\'s principles. The results are showing the variations of the overall trend of wave velocity toward wave vector have descending scheme and wave frequency against wave vector have ascending scheme; also were investigated effects of size and geometrical parameters on wave velocity and wave frequency. It was shown uptrend of types of wave velocities for wave vectors greater than 105.

Key Words
bone; lamellae, osteon; wave propagation; size effect

Address
Farzad Ebrahimi and Farin Zokaee: Faculty of engineering, Imam Khomeini International University, Qazvin, Iran
Vinyas Mahesh: Department of Mechanical Engineering, Nitte Meenakshi Institute of Technology, Bangalore, India


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