[Role of aerodynamic parameters in voice function assessment].

OBJECTIVE: To investigate the application and significance of aerodynamic parameters in voice function assessment. METHODS: The phonatory aerodynamic system (PAS) was used to collect aerodynamic parameters from subjects with normal voice, vocal fold polyp, vocal fold cyst, and vocal fold immobility. Multivariate statistical analysis was used to compare measurements across groups. RESULTS: Phonation threshold flow (PTF), mean flow rate (MFR), maximum phonation time (MPT), and glottal resistance (GR) in one hundred normal subjects were significantly affected by sex (P < 0.05), while phonation threshold pressure (PTP), subglottal pressure (SGP), and vocal efficiency (VE) were not (P > 0.05). PTP, PTF, MFR, SGP, and MPT were significantly different between normal voice and voice disorders (P < 0.01), and there were no significant differences among the three disorders (P > 0.05). Receiver operating characteristic (ROC) analysis found that PTP, PTF, SGP, MFR, MPT, and VE in one hundred thirteen voice dis orders had similar diagnostic utility (P < 0.01), with PTP exhibiting the highest area under the curve. The aerodynamic parameters of the three degrees of voice dysfunction due to vocal cord polyps were compared and found to have no significant differences (P > 0.05). PTP, PTF, MFR, SGP and MPT in forty one patients with vocal polyps were significantly different after surgical resection of vocal cord polyps (P < 0.01). CONCLUSION: The aerodynamic parameters can objectively and effectively evaluate the variations of vocal function, and have good auxiliary diagnostic value.

Destruction of nitrotoluenes in wastewater by Electro-Fenton oxidation.

Electrolytic degradation of dinitrotoluenes (DNTs) and 2,4,6-trinitrotoluene (TNT) in wastewater was conducted by Electro-Fenton's reagents. The batch-wise experiments were carried out to elucidate the influence of various operating variables on the electrolytic behavior, including electrode potential, oxygen dosage, electrolytic temperature, acidity of wastewater and dosage of ferrous ions. It deserves to note that the nitrotoluenes contained could be completely decomposed by Electro-Fenton's reagents, wherein hydrogen peroxide was in situ generated from cathodic reduction of oxygen, supplied mainly by anodic oxidation of water. During the electrochemical process, the influence of electrolytic temperature on the degradation of nitrotoluenes is the most significant, followed by electrode potential, acidity of wastewater and oxygen dosage. Based on the spectra analyzed by gas chromatograph/mass spectrometer (GC/MS), it is proposed that initial denitration of 2,4-DNT and/or 2,6-DNT gives rise to formation of o-mononitrotoluene, which undergoes the cleavage of nitro group into toluene, followed by oxidation of methyl group to benzoic acid and subsequent decarboxylation. It is believed that the electrolytic method established is potentially applied to dispose wastewater from toluene nitration processes in practice.