Statistical analysis
SPSS 21.0 software was used for statistical analysis. If the measurement data conforms to the normal distribution, the mean ± standard deviation is used to describe it, and the t test is used. If it does not conform to the normal distribution, the rank sum test is used. The count data were described by frequency (composition ratio). The one-way ordered data were compared by rank sum test, and the disordered data were tested by χ2 test. P < 0.05 was considered statistically significant.