Degradation of azo dyes under visible light with stable MOF based on tetrastyrene imidazole ligand.

In the present work, a new 3D metal-organic framework (MOF) has been synthesized and characterized. The MOF exhibits good chemical stability in aqueous solutions with the pH scale ranging from 3 to 11. Interestingly, the MOF shows high catalytic activities for the degradation of azo dyes (MO, CR and CBR) under visible light without H2O2. The Ea values of the MOF for MO, CR and CBR degradation are obtained to be 23.49, 52.68 and 15.19 kJ mol-1, respectively. In addition, the MOF can be reused in the catalytic process without the catalytic activity decreasing obviously.

Improved Photoreduction of CO2 with Water by Tuning the Valence Band of Covalent Organic Frameworks.

Porous covalent organic frameworks (COFs), as an emerging material, have the characteristics of high stability, large series of components, easy synthesis, modification, and adjustable amplitude. They have the potential to become good catalysts. Bromine, as a halogen, has attracted intensive interest for the modification of photocatalysts for photocatalytic reactions. It is feasible to enhance the activity and selectivity of the material by facile functionalization of the reticular parent structure's electron-withdrawing groups. In addition, the conjugation effect of bromine, further delocalizing the electrons of the COF, is beneficial to the progress of many photocatalytic reactions. Reports on the modification of COFs by bromine functional groups to improve the catalytic performance have not been found so far. Here, TAPP [5,10,15,20-tetrakis(4-aminophenyl)porphyrin] and 2,5-dibromo-1,4-benzenedialdehyde instead of terephthalaldehyde were chosen to synthesize a porphyrin-based COF (TAPBB-COF) by the solvothermal method. As expected, the valence band (VB) of TAPBB-COF is thus adjusted to a more suitable position. Additionally, the CO production when using TAPBB-COF under full-wavelength light for 12 h was 295.2 µmol g-1 , which was three times that of COF-366, and the new material has good recycling stability and selectivity (95.6 %). Theoretical calculations indicate that the nitrogen of the porphyrin ring and the Schiff base, and the bromine in TAPBB-COF contribute greatly to the activation of H2 O and the conversion of CO2 in the photoreaction.

The preparation of new covalent organic framework embedded with silver nanoparticles and its applications in degradation of organic pollutants from waste water.

A covalent organic framework (COF) featuring a unique light porous structure and silver nanoparticles shows high efficiency in the degradation of environmental pollutants. However, the combination of a COF with silver nanoparticles has never been reported until now. Toward this end, 2,4,6-tris-(4-formylphenoxy)-1,3,5-triazine (TPT-CHO) and hydrazine hydrate were selected as the construction units of the COF material (TPHH-COF), which possesses rich nitrogen and oxygen sites. Then a new type of composite catalyst (Ag@TPHH-COF) was successfully obtained by solution infiltration. The obtained materials were also fully characterized by standard methods. The results showed that the silver nanoparticles (with diameters of 5 ± 3 nm) were uniformly dispersed on the surface and in the interlayer gaps of the TPHH-COF substrate. Catalytic studies showed that Ag@TPHH-COF could catalyze the reduction of the various nitroaromatic compounds (NACs) with high efficiency, such as 4-nitrophenol, 2-nitrophenol, 4-nitroaniline, nitrobenzene, 4-nitrotoluene and 1-butyl-4-nitrobenzene. Ag@TPHH-COF could also catalyze the reduction of organic dyes such as Rhodamine B (RhB), Methylene Blue (MB), Methyl Orange (MO) and Congo Red (CR). Moreover, Ag@TPHH-COF has good reusability and high recovery.

[The relationships between oxygenation index and prognosis in acute respiratory failure patients treated by invasive mechanical ventilation].

OBJECTIVE: To investigate the effect of oxygenation index (PaO(2)/FiO(2)) on patients' prognosis through comparative analyzing the monitoring indicators of acute respiratory failure patients treated by invasive mechanical ventilation. METHODS: Data from 91 acute respiratory failure patients treated by invasive mechanical ventilation in respiration intensive care unit (ICU) of the General Hospital of PLA of Lanzhou from November 2006 to August 2011 were retrospectively analyzed. Patients were divided into survival group (n=55) and death group (n=36) by the outcome, the critical severity scores of the diseases and changes in blood gas analysis during ventilation were compared, and their correlation with prognosis were analyzed. RESULTS: There were no significant differences in acute physiology and chronic health evaluationIII (APACHEIII) score, multiple organ dysfunction syndrome (MODS) score, acute lung injury (ALI) score between survival and death group before ventilation (62.77±22.92 vs. 74.62±25.77, 6.46±2.45 vs. 6.62±3.03, 1.90±0.57 vs. 2.10±0.73, all P>0.05). There was no significant difference in PaO(2)/FiO(2) between survival and death group on the first day of mechanical ventilation (132.18±67.29 mm Hg vs. 139.24±78.36 mm Hg, P>0.05). PaO(2)/FiO(2) in survival group were significantly higher than that in death group on the 3 days and 7 days of mechanical ventilation (3 days: 205.47±74.71 mm Hg vs. 149.76±70.38 mm Hg, 7 days: 225.37±67.20 mm Hg vs. 120.94±85.58 mm Hg, P<0.05 and P<0.01). CONCLUSIONS: The present study demonstrated that the level of PaO(2)/FiO(2) is related with the prognosis of acute respiratory failure patients treated by invasive mechanical ventilation. Continuously monitoring the changes in PaO(2)/FiO(2) can be used as an important reference index to evaluate the prognosis of critical patients.