BACKGROUND:The siphon of internal carotid artery is a complex of bending and surrounding structure, which has become a research hot in the field of medical imaging and regional anatomy. There is little research on the hemodynamics of internal carotid artery. Finite element analysis provides the basis for the related dynamics research. OBJECTIVE:To explicit the hemodynamic characteristics of the normal and stenosis internal carotid artery, and to explore the relevant influential factors. METHODS:Finite element model of the siphon of internal carotid artery was built based on 64-slice spiral CT data, and then, three-dimensional models were constructed using Mimics 10.01 software. There were simulations of the normal and post-stenosis blood flows with ANSYS 13.0 CFX software, to observe the changes of hemodynamics, and to analyze their characteristics and differences. RESULTS AND CONCLUSION:The normal blood flow at the siphon of internal carotid artery was in a laminar state, but rotation and turbulent flow formed at the two angle regions. The velocity of external bending zone was slower than that of the internal. The slower was the velocity, the more obvious was the turbulence. The wal shear force decreased at the angle regions, and the wal shear force of external bending zone was smal er than that of the internal. At the region of arterial stenosis, the blood flow was sped, and at the downstream, turbulent flow and low zone of wal shear force were formed. With the increase of stenosis severity, the turbulent flow and low wal shear force area were expanded. Central stenosis showed more obvious effects than the eccentric one. The degree of stenosis and bending at the siphon of internal carotid artery can directly influence the formation of turbulent flow and low wal shear force area, which are more obvious at the external bending zone and central stenosis.

Objective:To analyze the differences in whole blood selenium (Se), zinc (Zn), copper (Cu), magnesium (Mg), calcium (Ca), and iron (Fe) levels of rural older adults among areas with different soil selenium levels, and explore the main factors associated with the six nutrient elements status, so as to provide a basis for further evaluating the health risks of people in areas with different soil selenium levels.Methods:Four administrative villages were randomly selected from the Se-deficient (soil Se content < 0.175 mg/kg), Se-sufficient (soil Se content 0.175 - < 0.400 mg/kg), Se-rich (soil Se content 0.400 - < 3.000 mg/kg) and Se-excessive (soil Se content ≥3.000 mg/kg) areas, respectively, in Enshi Tujia and Miao Autonomous Prefecture (Enshi Prefecture) of Hubei Province in 2017 - 2018. And 100 elderly people aged 60 years or older (half male and half female) were randomly selected as the survey subjects in each servey site. The basic information such as general demography and lifestyle was collected through face-to-face questionnaires. Physical examination was performed and fasting venous blood was collected in the morning. The contents of blood Se, Zn, Cu, Mg, Ca, and Fe were determined by inductively coupled plasma mass spectrometry. The main factors associated with the six nutrient elements status were analyzed.Results:A total of 416 subjects were included, including 208 males and 208 females, whose average age was (72.43 ± 5.25) years, and body mass index (BMI) was (22.67 ± 3.49) kg/m 2. There were significant differences of blood Se, Zn, Cu, Mg, Ca and Fe levels between the areas with different Se levels ( Z/F = 288.30, 3.24, 14.81, 29.14, 131.28, 3.37, P < 0.05). Compared with Se-deficient and Se-sufficient areas, blood Se level was higher in Se-rich and Se-excessive areas and blood Zn level was lower in Se-excessive area ( P < 0.05); compared with Se-sufficient area, blood Cu level was lower in Se-deficient, Se-rich and Se-excessive areas, but blood Mg and Ca levels were higher ( P < 0.05), and the blood Fe level was lower in Se-excessive area ( P < 0.05). There were significant differences in the deficiency rates of Se, Zn, Cu, Mg, Ca and Fe among the elderly in different Se level areas (χ 2 = 140.83, 15.39, 31.90, 17.49, 157.60, 30.33, P < 0.01). There were significant differences in blood Zn, Cu, Ca and Fe levels between two gender groups ( P < 0.05); the blood Zn and Fe levels of the smokers were higher than those of the non-smokers, and the blood Cu level was lower than that of the non-smokers ( P < 0.05); the blood Zn and Fe levels of the drinkers were higher than those of the non-drinkers ( P < 0.05). Conclusions:The levels of six nutrient elements in the whole blood of the elderly in areas with different soil Se levels are different. To assess the health risks of the population in areas with different soil Se levels, it is necessary to consider the levels of multiple nutrient elements at the same time.