RESUMO
In this work, the growth of extended tri-s-triazine units (melem units) on g-C3N4 (CN) by hydrothermal treatment and its effect on the photodegradation efficiency of tetracycline hydrochloride (TC) is investigated. The CN-180-x and CN-200-6 samples were prepared using different hydrolysis times and temperatures, and they were characterized by multiple physicochemical techniques. In addition, their photodegradation performance was evaluated under visible light irradiation. Compared to the CN, CN-180-6 possesses remarkable photocatalytic degradation efficiency at 97.17% towards TC removal in an aqueous solution. The high visible-light-induced photo-reactivity of CN-180-6 directly correlates to charge transfer efficiency, numerous structural defects with a high specific surface area (75.0 m2 g-1), and sufficient O-functional groups over g-C3N4. However, hydrothermal treatment at a higher temperature or during a longer time additionally induces the growth of extended melem units on the surface of g-C3N4, resulting in the inhibition of the charge transfer. In addition, the superoxide radical is proven to be generated from photoexcited reaction and plays a key role in the TC degradation.
RESUMO
In this study, we synthesized Pt/g-C3N4 photocatalysts modified by a solvent etching process where ethanol (Pt/CN0), water (Pt/CN100), and a 50:50 mixture (Pt/CN50) were used as a solvent, and investigated the optimal properties of g-C3N4 to prepare the best Pt/g-C3N4 for photocatalytic hydrogen evolution. From diverse characterizations, water was proven to be a stronger solvent agent, resulting in not only the introduction of more O-functional groups onto the g-C3N4 surface, but also the degradation of a regular array of tri-s-triazine units in the g-C3N4 structure. While the addition of O-functional groups positively influenced the oxidation state of the Pt cocatalyst and the hydrogen production rate, the changes to g-C3N4 structure retarded charge transfer on its surface, inducing negative effects such as fast recombination and less oxidized Pt species. Pt/CN50 that was synthesized with the 50:50 solvent mixture exhibited the highest hydrogen production rate of 590.9 µmol g-1h-1, while the hydrogen production rates of Pt/CN0 (with pure ethanol solvent) and Pt/CN100 (with pure water solvent) were 462.7, and 367.3 µmol g-1h-1, respectively.
RESUMO
OBJECTIVE: The study aimed to obtain nasalance scores for Vietnamese-speaking patients with repaired cleft palate with or without cleft lip. METHODS: A total of 29 children with cleft palate with or without cleft lip (4-18 years old, mean age 7.9±3.5 years old) were included in this study. Speech material was designed specifically for the Vietnamese language. The speech material consisted of oral stimuli (19 oral words and 18 oral sentences), oro-nasal stimuli (eight sentences), and nasal stimuli (seven sentences). The patients repeated the stimuli after the examiner. The Nasometer II (model 6450) was used to compute nasalance scores. RESULTS: The mean nasalance scores were 27.1% for oral stimuli, 40.2% for oro-nasal stimuli, and 57.5% for nasal stimuli. Hypernasality was detected in 41.4% of the patients. CONCLUSION: Vietnamese-speaking patients with repaired cleft palate with or without cleft lip who did not undergo speech therapy had poor speech outcomes.
Assuntos
Fenda Labial , Fissura Palatina , Adolescente , Povo Asiático , Criança , Pré-Escolar , Fenda Labial/complicações , Fissura Palatina/complicações , Humanos , Idioma , FalaRESUMO
OBJECTIVE: The Nasometer is increasingly being used to complement auditory perceptual assessment of nasality. Nasalance scores which are obtained from the Nasometer vary across languages. Normative nasalance scores have been established for many languages but not for the Vietnamese language. The objective of this study was to obtain the normative nasalance scores for Vietnamese-speaking children. PARTICIPANTS: In this study, 102 healthy Vietnamese children speaking in the central regional dialect aged from 7 to 9 years (45 boys, 57 girls; mean age = 7.5 years) at a primary school in Hue, Vietnam participated. PROCEDURES: Three speech stimuli, which were specific for the Vietnamese language, were designed: oral stimuli (19 words and 18 sentences), oro-nasal stimuli (eight sentences) and nasal stimuli (seven sentences). The children were asked to repeat these stimuli after the examiner. The Nasometer II (model 6450) was used to obtain the nasalance scores. The procedure took about 10 minutes for each child. RESULTS: The mean nasalance scores and the standard deviation of each stimulus were: 13.1 ± 5.8 (oral stimuli), 30.7 ± 6.6 (oro-nasal stimuli) and 56.9 ± 9.2 (nasal stimuli). No significant differences between the genders were found. CONCLUSIONS: The normative nasalance scores provide essential reference information for clinicians who deal with nasalance disorders, especially patients with cleft palate. The nasalance scores in this study were established for Vietnamese children speaking in the central regional dialect and can be applied to both genders.