[Impact of sinonasal anatomic changes after endoscopic anterior skull base surgery on nasal airflow and air conditioning: a computational fluid dynamics study]

Objective: To analyze the impact of the sinonasal anatomic changes after endonasal endoscopic anterior skull base surgery on the nasal airflow and heating and humidification by computational fluid dynamics (CFD), and to explore the correlation between the postoperative CFD parameters and the subjective symptoms of the patients. Methods: The clinical data in the Rhinology Department of the First Affiliated Hospital of Zhengzhou University from 2016 to 2021 were retrospectively analyzed. The patients received the endoscopic resection of the anterior skull base tumor were selected as the case group, and the adults whose CT scans had no sinonasal abnormalities were chosen as the control group. The CFD simulation was performed on the sinonasal models after reconstructed from the patients' sinus CT images during the post-surgical follow-up. All the patients were asked to complete the Empty Nose Syndrome 6-Item Questionnaire (ENS6Q) to assess the subjective symptoms. The comparison between two independent groups and the correlation analysis were carried out by using the Mann-Whitney U test and the Spearman correlation test in the SPSS 26.0 software. Results: Nineteen patients (including 8 males and 11 females, from 22 to 67 years old) in the case group and 2 patients (a male of 38 years old and a female of 45 years old) in the control group were enrolled in this study. After the anterior skull base surgery, the high-speed airflow moved to the upper part of the nasal cavity, and the lowest temperature shifted upwards on the choana. Comparing with the control group, the ratio of nasal mucosal surface area to nasal ventilation volume in the case group decreased [0.41 (0.40, 0.41) mm^-1 vs 0.32 (0.30, 0.38) mm^-1; Z=-2.04, P=0.041], the air flow in the upper and middle part of the nasal cavity increased [61.14 (59.78, 62.51)% vs 78.07 (76.22, 94.43)%; Z=-2.28, P=0.023], the nasal resistance decreased [0.024 (0.022, 0.026) Pa·s/ml vs 0.016 (0.009, 0.018) Pa·s/ml; Z=-2.29, P=0.022], the lowest temperature in the middle of the nasal cavity decreased [28.29 (27.23, 29.35)℃ vs 25.06 (24.07, 25.50)℃; Z=-2.28, P=0.023], the nasal heating efficiency decreased [98.74 (97.95, 99.52)% vs 82.16 (80.24, 86.91)%; Z=-2.28, P=0.023], the lowest relative humidity decreased [(79.62 (76.55, 82.69)% vs 73.28 (71.27, 75.05)%; Z=-2.28, P=0.023], and the nasal humidification efficiency decreased [99.50 (97.69, 101.30)% vs 86.09 (79.33, 87.16)%; Z=-2.28, P=0.023]. The ENS6Q total scores of all patients in the case group were less than 11 points. There was a moderate negative correlation between the proportion of the inferior airflow in the post-surgical nasal cavity negatively and the ENS6Q total scores (r_s=-0.50, P=0.029). Conclusions: The sinonasal anatomic changes after the endoscopic anterior skull base surgery alter the nasal airflow patterns, reducing the efficiency of nasal heating and humidification. However, the post-surgical occurrence tendency of the empty nose syndrome is weak.

Local structure of NiAl compounds investigated by extended X-ray absorption fine-structure spectroscopy

The local structures of pure NiAl and Ti-, Co-doped NiAl compounds have been obtained utilizing extended X-ray absorption fine-structure (EXAFS) spectroscopy. The results provide experimental evidence that Ni antisite defects exist in the Ni-rich NiAl compounds. The site preference of Ti and Co has been confirmed. Ti occupies the Al sublattice, while Co occupies the Ni sublattice. The structure parameters obtained by EXAFS were consistent with the X-ray diffraction results. Owing to the precipitation of α-Cr, the local structure of NiAl-Cr has not been obtained, making the site preference of Cr unclear.

Removal of phosphorus and nitrogen from domestic wastewater using a mineralized refuse-based bioreactor

Municipal solid waste used for landfill becomes stabilized, or aged, some years after placement, and can be safely excavated; the term 'mineralized refuse' is used in this study. The adsorptions of phosphorus, and the nitrification of the mineralized refuse and clay, were investigated by batch incubation. The variation of phosphorus adsorption in the mineralized refuse was fitted to the Freundlich adsorption isotherm equation, giving a maximum phosphorus adsorption capacity of 2310 mg kg(-1). Based on the Langmuir isotherm equation, maximum phosphorus adsorption capacity was calculated to be 1976 mg kg(-1), almost twice that of the clay. The equations for both the mineralized refuse and clay were fitted to zero-order kinetics (R2 > 0.98, P < 0.01, n = 11), giving concentrations of phosphorus as phosphates less than 250 mg L(-1). The K value for the mineralized refuse was about 3.5 times higher than for the clay. The production of nitrogen as nitrates in both the mineralized refuse and the clay after 120 h incubation yielded a first-order reaction kinetics value of 100 mg kg(-1) NH4(+)-N from the initial concentration. The calculated net nitrification as nitrates for the mineralized refuse was 6.3 times higher than for the clay. Domestic wastewater was then treated in a mineralized refuse-based bioreactor for 30 days. The removal rates of COD(cr), total nitrogen and total phosphorus were 73.77 +/- 8.10%, 61.01 +/- 6.75%, and 69.14 +/- 9.25%, respectively. Large accumulations of nitrates occurred in the mineralized refuse-based bioreactor. For the full-scale design, a high column of mineralized refuse is recommended for the denitrification.