Exploration of tortoise shell structure mechanical characteristics

As one of the oldest creatures on the earth, the tortoises have formed a nearly perfect shell structure after millions of years of evolution In this paper, Chinese tortoise shell is studied. Firstly, the scanning model of the tortoise shell is established by means of computer tomography （CT） scanning technology and MIMICS software. Secondly, the solid model of three-dimensional structure of the tortoise shell is constructed by using geomagic studio reverse engineering software. Afterwards, the compression numerical simulation of the tortoise shell structure under low strain rate is conducted with the help of finite element software LS-DYNA. Finally, load-bearing characteristics of the tortoise shell structure and dome-shaped structure are compared and analyzed. The results show that compared withthe dome-shaped structure with the same volume, tortoise shell structure has a higher structural rigidity and can withstand higher pressure. Therefore, tortoise shell structure provide some reference to the design of armored vehicles, sheltersand other types of thin shell structures.

Differentiating Trachemys scripta elegans Shell Glue from Chinemys reevesii Shell Glue by UPLC-QTOF/MS Coupled with Binary Compare Tool of UNIFI

Objective This study was conducted to develop an method for identification of Trachemys scripta elegans(Ba Xi Gui,巴西龟)shell glue from Chinemys reevesii(Zhong Hua Cao Gui,中华草龟)shell glue.Methods In this research,an ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry(UPLC-QTOF/MS)method coupled with Binary Compare tool of UNIFI software was validated to differentiate Trachemys scripta elegans(Ba Xi Gui,巴西龟)shell glue from Chinemys reevesii(Zhong Hua Cao Gui,中华草龟)shell glue.The gelatins were digested enzymatically into peptides using trypsin.The UPLC-QTOF/MS data of the trypsin digested samples was subjected to Binary Compare of UNIFI software in order to screen out the unique peptides.PEAKS■Studio software was utilized to identify the sequence of the marker peptides.Results It was found that m/z 641.3 was the marker peptide in samples of Trachemys scripta elegans(Ba Xi Gui,巴西龟)shell glue,and m/z 649.3 was the marker peptide in samples of Chinemys reevesii(Zhong Hua Cao Gui,中华草龟)shell glue,with possible amino acid sequence of GEAGPSGPAGPTGAR and GESGPSGPAGPTGAR respectively.Conclusions The results will be helpful for the differentiating between these 2 gelatins,and it can be also used for quality control of Tortoise shell glue(Gui Jia Jiao,龟甲胶).