Role of Functional Groups in Tuning Luminescence Signature of Solution-Processed Graphene Quantum Dots: Experimental and Theoretical Insights.

Zero-dimensional graphene quantum dots (GQDs) present unique optoelectronic properties in the large-spectrum range from UV to visible. However, the origin of luminescence in GQDs is still a debatable question. Therefore, the present work investigates the features of trap-mediated and edge-state-functionalized group-associated luminescence enhancement of GQDs. The attached functional groups' involvement in the upsurge of photoluminescence has been discussed theoretically as well as experimentally. In addition, the role of the aromatic ring, the functional group attached, and their positions of attachment to the aromatic ring to tune the emission wavelength and Raman modes have been elucidated theoretically as well as experimentally. We found that in the case of the -OH group attached outside of the aromatic ring, the long-range π hybridization dominates, which suggests that the emission from this model can be dictated by long-range π hybridization. In particular, we found that oxygen-containing functional groups attached outside of the aromatic ring are the main source of the luminescence signature in GQDs. Furthermore, density functional theory (DFT) indicates that the -OH functional group attached outside of the aromatic ring perfectly matched with our experimental results, as the experimental bandgap (2.407 eV) is comparable with the theoretical simulated bandgap (2.399 eV) of the -OH group attached outside of the aromatic ring.

Knowledge, attitudes and practices towards community-acquired pneumonia and COVID-19 among general population: a cross-sectional study.

BACKGROUND: This study aimed to assess the knowledge, attitudes, and practices (KAP) of the general population to community-acquired pneumonia (CAP) and COVID-19. METHODS: A cross-sectional study was conducted between September 2022 and February 2023, involving the general population from Ningbo Municipal Hospital of Traditional Chinese Medicine with a self-developed questionnaire. RESULTS: A total of 637 valid questionnaires were collected, with the majority of participants being female (62.48%). The mean score for knowledge, attitudes, and practices were 7.60 ± 2.39 (possible range: 0-12), 43.20 ± 4.57 (possible range: 11-55), and 34.57 ± 4.95 (possible range: 10-50), respectively. Multivariate logistic regression analysis indicated that master's degree or above (OR = 6.04, 95% CI: 1.80-20.31, P = 0.004) and occupation in business or service careers (OR = 0.28, 95% CI: 0.17-0.48, P < 0.001) were independent associated with knowledge. The knowledge (OR = 1.32, 95%CI: 1.20-1.44, P < 0.001) and female gender (OR = 1.48, 95%CI: 1.03-2.14, P = 0.036) were independently associated with positive attitudes. Attitudes (OR = 1.34, 95%CI: 1.26-1.43, P < 0.001) and a monthly household income greater than 20,000 RMB (OR = 0.31, 95%CI: 0.15-0.64, P = 0.001) were independent associated with practices. Pearson correlation analysis revealed that knowledge positively correlated with attitude scores (r = 0.348, P < 0.001) and practice scores (r = 0.259, P < 0.001), and attitude and practice scores were also positively correlated (r = 0.563, P < 0.001). Structural equation modeling showed that knowledge predicted attitudes (ß = 0.67, P < 0.001) and practices (ß = 0.17, P = 0.017), while attitudes predicted practices (ß = 0.58, P < 0.001). CONCLUSION: General population had moderate knowledge, positive attitudes and average practices towards CAP and COVID-19.

[Determination of urea in canned foods by high performance liquid chromatography-fluorescence detection coupled with precolumn derivatization].

A method for the determination of urea residue in canned foods by high performance liquid chromatography-fluorescence detection (HPLC-FLD) coupled with precolumn derivatization was established. The sample (5.0 g), including canned edible fungi, fruit, vegetable, fish, and meat was extracted with 20 mL 1% (v/v) acetic acid solution. The extract was centrifuged, filtrated, and then derivatized with xanthydrol. The analysis was completed with HPLC-FLD. A good linear relationship was obtained in the range of 0.1-500 mg/L with the correlation coefficients more than 0.9995. The average recoveries of urea spiked at 0.001-30 g/kg levels in five kinds of canned foods ranged from 80.2% to 109.7% with the RSDs of 2.05%-6.53%. The limit of detection (LOD) was 0.5 mg/kg, and the limit of quantitation (LOQ) was 1.0 mg/kg. The proposed procedure was then applied to the analysis of 168 real samples collected from Xiamen, Fujian Province, China. The existence of urea was found in three pork cans with contents of 10.6, 62.1 and 2.6 mg/kg, respectively. The method is stable, reliable, simple and suitable for the determination of urea in canned foods, and has great potential for routine analysis in foodstuffs.