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Quantitative prenatal growth of the cervical sympathetic trunk components in sheep (Ovis arise) during the foetal period

100%

Bamohabat S. , Nourinezhad J. , Mazaheri Y.

Folia Morphologica

2018

tom 77

nr 3

Background: Six liner measurements of constant cranial cervical ganglion (CCG), three inconstant main, first, second middle cervical ganglia (MG, MG1, MG2), and interganglionic branch (IGB) were taken to determine normal foetal growth rates and patterns of cervical sympathetic trunk (CST) components in different gestational ages. Materials and methods: Forty sheep foetuses of both sexes aged from 60 to 140 days were divided into four groups and 80 sides of foetuses were examined under a stereomicroscope using a digital calliper. Results: Following findings were obtained: 1) There was no significant difference for the values between sex and body side among all age groups, although sex and laterality differences in CST length and laterality differences in IGB total length and MG1 width were found regardless of age groups. 2) Correlations between dimensions of CST components and crown-rump length (CRL) were always positive during foetal period and decreased with increasing foetal age. 3) The highest growth rate in CST components in foetal sheep took place in the youngest age group because of rapid growth rates in lengths of IGB and CCG. Conclusions: Based on these detailed findings, comparative prenatal growth rates and patterns of animal organs and body, embryological and histological data as well as neurovertebral relationships among cervical parts of sympathetic trunk, spinal cord, and vertebral column were discussed and compared with previous studies. Although allometric growth of CST in relation to CRL was constant between foetal sheep and pig, there were specific characteristics in prenatal growth of CST components in foetal sheep which were different from those of foetal pig. It seems that only growth pattern in length of CST in sheep during foetal period follows the same growth pattern of CRL, body weight, and length of cervical parts of spinal cord and vertebral column. (Folia Morphol 2018; 77, 3: 456–463)

Production and investigation of mechanical properties and electrical resistivity of cement-matrix nanocomposites with graphene oxide and carbon nanotube reinforcements

88%

Najafishad S. , Manesh H. D. , Zebarjad S. M. , Hataf N. , Mazaheri Y.

Archives of Civil and Mechanical Engineering

2020

tom Vol. 20, no. 2

397--409

In this study, two groups of the cement-matrix nanocomposites (CMNC) were produced. The first group was reinforced with either carbon nanotubes (CNT) or graphene oxide (GO), where the equivalent weight% of cement equaled 0.05, 0.1, and 0.15. The second group was reinforced with the hybrid CNT–GO, where the equivalent weight% of cement equaled 0.05 CNT–0.1 GO and 0.1 CNT–0.05 GO. Before producing nanocomposites, the distribution of the nanoreinforcement in water had been investigated using spectrophotometric analysis, scanning electron microscopy, and transmission electron microscopy. The physical and mechanical behaviors of different samples of the produced nanocomposites were evaluated by electrical resistivity and compressive strength tests. The effects of the types and the percentages of the nanoreinforcements on the electrical and mechanical properties of the produced nanocomposites were measured. The results showed that the electrical resistivity of the produced composites decreased with increasing the percentage of CNT, whereas the compressive strength of the cement paste initially increased and then decreased. Also, with increasing the percentage of GO, the compressive strength of the produced composites increased, while the electrical resistivity decreased. Moreover, in comparison with the composites reinforced with either CNT or GO, by using the hybrid reinforcement (CNT/GO), the compression strength increased, while the electrical resistivity decreased.