Effect of carbon nitride synthesized by different modification strategies on the performance of carbon nitride/PVDF photocatalytic composite membranes.

Carbon nitride (CN)/polyvinylidene fluoride (PVDF) photocatalytic composite membrane (PCM) is considered as a promising candidate to improve the anti-fouling characteristic of conventional PVDF membrane and overcome the difficulty encountered during recovery of powder catalyst simultaneously. However, the effects of differently-modified CN on PCM and its mechanism are still unclear. In this study, bulk-CN (BCN), carbon defects CN (CCN), nitrogen defect CN (DCN), mesoporous CN (MCN), and nitrogen-rich CN (NCN) were incorporated into PVDF by phase inversion method. The influence of changes in the physical and chemical properties of CN, including hydrophilic groups, photocatalytic activity, and particle size, on the permeability, anti-fouling characteristic, and photocatalytic self-cleaning activity of CN/PVDF was systematically analyzed. The mechanism of excellent performance of PCM was revealed by experimental test and theoretical calculation. The flux of PCM was significantly improved by increasing the hydrophilic group on modified CN. However, the differences in particle size and interaction between different types of modified CN and PVDF chains endowed the CN/PVDF with different porosity. DCN/PVDF showed high porosity and hydrophilicity, leading to high water flux and rejection rate of 293.6 L (m2 h)-1 and 90.1%, respectively. Compared to pure PVDF, the flux recovery rate of DCN30/PVDF increased by 27.6%, and the irreversible fouling decreased from 36.9% to 9.2%. The modified CN/PVDF showed excellent photocatalytic activity for the removal of cefotaxime (CFX) and E. coli. Owing to the narrow band gap of DCN, large specific surface area, and low photogenerated carrier recombination rate, the CFX removal rate reached 99% in 2 h, and E. coli inactivation achieved 3.7 log within 4 h via DCN30/PVDF.

[Determination of the lung function by impulse oscillometry in 549 healthy children in Chengdu area].

OBJECTIVE: Impulse oscillometry (IOS) is a new method for determination of breathing mechanics, which features convenient operation, good repeatability and wider range analysis. As there is no standardized normal value in China at present, this study will provide a normal value of lung function determination by impulse oscillometry for children in Chengdu area. METHOD: Totally 549 children were chosen at random from Chengdu area, with 292 boys and 257 girls who were 4 to 14 years old. The subjects were assigned into 10 age groups according to their chronological age with one year difference between every two adjacent groups. The respiratory total impedance (Zrs), viscosity resistance (Rrs) and elastic resistance (Xrs) at various oscillation frequency were measured by the Master Screen IOS which was manufactured by German Jaeger Company. The measured data were treated with the linear stepwise multiple regression, and established the prediction equation. At the same time, paired comparison was carried out with the measured data and equation obtained from this study, Lechtenboerger equation and prediction equation obtained from Guangzhou area. RESULT: The total impedance and airway resistance were negatively correlated with the children's height and age. Zrs (male) = -0.756 + 189.586/height, r = -0.782, P < 0.001; Zrs (female) = -0.497 + 152.468/height, r = -0.726, P < 0.001. Rrs became the same in trend; while Xrs were proportional to the height, e.g. the values increased as the height increased. The difference of the airway resistance (R(5)-R(20)) was negatively correlated with the children's height: R(5)-R(20) (male) = 0.601 - 0.0034 x height, r = -0.677, P < 0.001; R(5)-R(20) (female) = 0.549 - 0.0031 x height, r = -0.658, P < 0.001. Among the relationships with many impulse oscillometry parameters, height ranked at first place; age at second. The multiple regression equation of IOS primary index was established. Both the measured data and the correlation coefficient of the study obtained equation were greater than the coefficient correlation of the Lechtenboerger equation, but had no significant difference compared with that of prediction equation in Guangzhou area. CONCLUSION: The normal value in impulse oscillometry in children in Chengdu area is different from the predicted parameters in other countries. The equation obtained from this study seems to be more suitable for the children in its local area. It is recommended to apply the predicted value from the corresponding population in the determination of the lung function by impulse oscillometry.

[Survey on prevalence of 1 526 children with sleep disturbances in age of 2 to 12 years old in Chengdu].

OBJECTIVE: To find out the prevalence of sleep disturbances for children aged 2 to 12 years old in Chengdu. METHODS: Totally 1 600 children aged 2-12 years old were selected from 5 districts in Chengdu and investigated by using questionnaire. RESULTS: All 1 526 survey papers were returned. The average time of every day sleep in each age group (infant group, pre-school age group and school age group) were 12.12 hours, 10.42 hours and 9.47 hours. The sleep time of the children in those three groups were much less than the standard one. The proportion of the prevalence of sleep disturbance was 37.88%. Among them, there were snoring in 5.57%, choke/gargling in 1.25%, sleep inquietude in 7.86%, mouth breathing in 4.59%, sweating in 21.36%, member spasm in 2.82%, molar teeth in 8.26%, night talking in 4.02%, somnambulate in 0.2%, bedwetting in 1.95%, and difficulty falling asleep in 10.75%. There were significant differences shown in different sexes and ages, and in incidence of symptoms of some sleep disturbances. The affecting factors were the co-sleeping, tonsillitis, bronchitis, pollen allergy and their parent's snore. CONCLUSION: The prevalence of sleep disturbances being higher and more severe than before might be due to the less sleeping time in Chengdu in children aged 2 to 12 years old. More attention should be paid by parents, the Ministry of Education and the children's doctors.

[Imbalanced T cell-specific transcription factors T-bet and GATA-3 contributes to type 2 T helper cell polarization in asthmatic patients].

OBJECTIVE: To identify the T helper cell predominant differentiation in asthmatic patients and to explore the modulation of T cell-specific transcription factors T-bet/GATA-3. METHODS: Thirty-two asthmatic patients were enrolled, among whom 18 were atopic defined by positive antigen skin test and 12 were children. Lymphocytes were isolated from peripheral blood and incubated with PHA (100 microg/ml) at 37 degrees C for 48 hours. INF-gamma and IL-4 concentrations in the supernatant were detected by ELISA. The T-bet and GATA-3 mRNA expression levels in lymphocytes were assayed by reverse transcription-polymerase chain reaction (RT-PCR) while the ratio of CCR3+ and CCR5+ cells in lymphocytes was counted by flow cytometry (FCM) after direct immunofluorescence staining. RESULTS: IL-4 concentration in the lymphocyte supernatant of the asthmatic group was (118 +/- 25) microg/L, which was significantly elevated compared to that of the healthy control group (75 +/- 12) microg/L (P < 0.01). When subgroups of asthmatic patients were compared, the results showed that atopic subjects had a higher IL-4 level than non-atopic subjects [(126 +/- 23) microg/L vs (107 +/- 26) microg/L, P < 0.01], but no significant difference was demonstrated between adults and children [(118 +/- 25) micro g/L vs (121 +/- 25) microg/L, P > 0.05]. Significantly lower concentration of INF-gamma in the asthmatic group was detected as compared to the control [(651 +/- 85) microg/L vs (1 179 +/- 332) microg/L, P < 0.001]. The concentration of INF-gamma was higher in atopic subjects than in non-atopic subjects [(618 +/- 89) micro g/L vs (680 +/- 83) microg/L, P < 0.01], but no difference was found between adults and children. The percentage of CCR3+ cells in lymphocytes was (9.4 +/- 5.8)% in the asthmatic group and (4.9 +/- 2.3)% in the control (P < 0.05), while the percentages of CCR5+ cells was (6 +/- 7)% and (13 +/- 7)%, respectively (P < 0.05). RT-PCR revealed that T-bet mRNA expression levels were as follows: 0.13 +/- 0.03 in the asthmatic group and 0.18 +/- 0.04 in the control (P < 0.01); 0.120 +/- 0.030 in atopic subjects and 0.140 +/- 0.010 in the non-atopic subjects (P < 0.05); 0.120 +/- 0.020 in children and 0.130 +/- 0.020 in adults (P > 0.05). The levels of GATA-3 mRNA expression were 0.43 +/- 0.07 in asthma and 0.29 +/- 0.09 in the control (P < 0.01), however, no differences were found between atopic and non-atopic, children and adults (0.50 +/- 0.12 vs 0.40 +/- 0.10, 0.44 +/- 0.09 vs 0.43 +/- 0.07, respectively, P > 0.05). A positive correlation was found between concentration of INF-gamma and T-bet mRNA level (r=0.663, P < 0.01), while no correlation with GATA-3 mRNA expression was found. The concentration of IL-4 was negatively correlated with T-bet mRNA level (r=-0.250, P < 0.05) and positively with GATA-3 mRNA level (r=0.72, P < 0.01). It was interesting that a closer relationship existed between the ratio of T-bet to GATA-3 and the ratio of INF-gamma to IL-4 (r=0.873, P < 0.01). CONCLUSIONS: In asthma there is a tendency of Th2 polarization with over-production of Th2-like cytokines in which T-bet deficiency may be a key factor. T-bet might direct T cells to Th1 differentiation while GATA-3 orientated Th2 maturation. Considering the fact that committed Th2 cells underwent re-differentiation induced by T-bet, this novel Th1-specific transcription factor is a fascinating target gene for modifying to restore the Th1 and Th2 balance.