This paper analyzes and simulates the effect of the air change rate per hour (ACH) on contamination diffusion airflow field in turbulent clean-room of hole-board ventilation by using CFD. The quality of Contaminant Removal Effectiveness (CRE) is compared with ACH ranging from 15 to 70. According to the simulation,it is the best condition of CRE in clean room when air change rate is 55 per hour,and the conclusion provides a theoretic basis for engineering design.

Objective To investigate the changes and predictive value of Omentin-1 levels in patients with type 2 diabetes mellitus(T2DM)under different bone metabolic status.Methods A total of 120 T2DM pa-tients admitted to a hospital from June 2021 to December 2022 were selected and divided into group A(normal bone mass,T-value-1.0,36 cases),Group B(bone loss,-2.5＜T-value＜-1.0,49 cases)and group C(osteoporosis,T-value-2.5,35 cases)according to different bone mineral density.Another 50 healthy sub-jects who underwent physical examination in a hospital during the same period were selected as the healthy control group.Basic data,serum Omentin-1 and bone metabolism levels of the 4 groups were compared,and the correlation between serum Omentin-1 and bone metabolism and blood glucose levels was analyzed by Pear-son correlation analysis.Multiple stepwise regression analysis was conducted to analyze the factors affecting bone mineral density in T2DM patients.Receiver operating characteristic(ROC)curve was drawn to analyze the predictive value of serum Omentin-1 level in T2DM with osteoporosis.Results The fasting blood glucose(FBG)level of groups A,B and C was higher than that of healthy control group,and the hemoglobin A1c(HbA1c)and homeostasis model assessment of insulin resistance(HOMA-IR)of healthy control group,group A and group B were lower than that of group C,with statistical significance(P＜0.05).Omentin-1,type Ⅰ procollagen N-terminal propeptide(P Ⅰ NP)and osteocalcin(BGP)in healthy control group,group A and group B were higher than those in group C,while the β-CTX sequence of type Ⅰ collagen in healthy con-trol group,group A and group B was lower than that in group C,and the difference was statistically signifi-cant(P＜0.05).Pearson correlation analysis showed that the serum Omentin-1 level in T2DM patients was negatively correlated with the levels of HbA1c,HOMA-IR and β-CTX(r=-0.770,-0.807,-0.759,P＜0.05),and positively correlated with the levels of P Ⅰ NP and BGP(r=0.868,0.879,P＜0.05),but no sig-nificant correlation with FBG level(r=-0.085,P=0.152).Omentin-1,P Ⅰ NP,β-CTX,BGP,HbA1c and HOMA-IR were independent influencing factors of BMD in T2DM patients(P＜0.05).ROC curve analysis showed that the area under the curve of serum Omentin-1 level predicting T2DM with osteoporosis was 0.835(95％CI:0.764-0.906),and when the cut-off value was 50.325 ng/mL,the sensitivity was 0.854,the speci-ficity was 0.801,and the Youden index was 0.655.Conclusion Serum Omentin-1 expression is low in T2DM patients,and its expression is closely related to bone mineral density,bone metabolism and insulin resistance in T2DM patients,and can effectively predict the occurrence of T2DM with osteoporosis.