Metal Variance in Multivariate Metal-Organic Frameworks for Boosting Catalytic Conversion of CO2.

Developing efficient, low-cost, MOF catalysts for CO2 conversion at low CO2 concentrations under mild conditions is particularly interesting but remains highly challenging. Herein, we prepared an isostructural series of two-dimensional (2D) multivariate metal-organic frameworks (MTV-MOFs) containing copper- and/or silver-based cyclic trinuclear complexes (Cu-CTC and Ag-CTC). These MTV-MOFs can be used as efficient and reusable heterogeneous catalysts for the cyclization of propargylamine with CO2. The catalytic performance of these MTV-MOFs can be engineered by fine-tuning the Ag/Cu ratio in the framework. Interestingly, the induction of 10% Ag remarkably improved the catalytic efficiency with a turnover frequency (TOF) of 243 h-1, which is 20-fold higher than that of 100% Cu-based MOF (i.e., TOF = 10.8 h-1). More impressively, such a bimetallic MOF still exhibited high catalytic activity even for simulated flue gas with 10% CO2 concentration. Furthermore, the reaction mechanism has been examined through the employment of NMR monitoring experiments and DFT calculations.

Tuning the Catalytic Activity of Covalent Metal-Organic Frameworks for CO2 Cycloaddition Reactions.

The development of efficient, recyclable and low-cost heterogeneous catalysts for conversion of carbon dioxide (CO2 ) into epoxides is highly desired, yet remain a challenge. Herein, we have prepared three two-dimensional (2D) copper(I) cyclic trinuclear units (Cu(I)-CTUs) based covalent metal-organic frameworks (CMOFs), namely JNM-13, JNM-14, and JNM-15, via a one-pot reaction by combination of coordination and dynamic covalent chemistry. Among them, JNM-15 contained the highest density of copper catalytic sites, and exhibited the highest capacity for adsorption of CO2 . More interestingly, JNM-15 delivered the highest catalytic activity for cycloaddition of CO2 to epoxides with good yields (up to 99 %), good substrate compatibility (11 examples) and reusability (four catalytic cycles) under mild condition.

Health risk assessment of heavy metals in Cyprinus carpio (Cyprinidae) from the upper Mekong River.

The purposes of this research are to quantify the concentration of heavy metals (Zn, Cu, As, Pb, Cd, and Hg) in the water and fish tissues of common carp (Cyprinus carpio) in the upper Mekong River and to thereby elucidate the potential dietary health risks from fish consumption of local residents. Surface water and fish tissues (gill, muscle, liver, and intestine) from four representative sample areas (influence by a cascade of four dams) along the river were analyzed for heavy metal concentrations. Results revealed that the levels of heavy metals in fish were tissue-dependent. The highest Cu and As levels were found in the liver; the highest Zn and Pb levels occurred in the intestine, and the highest Hg level was found in the muscle. The total target hazard quotient (THQ) value for residents is > 1 for long-term fish consumption, and local residents are, therefore, exposed to a significant health risk. Results from the current study provide an overall understanding of the spatial and tissue distribution of heavy metals in water and fish body along the upper Mekong River under the influence of cascade dams and highlight the potential health risk of As for the local residents of long-term fish consumption.

DNA methylation level of promoter region of activating transcription factor 5 in glioma.

Transcription factors, which represent an important class of proteins that play key roles in controlling cellular proliferation and cell cycle modulation, are attractive targets for cancer therapy. Previous researches have shown that the expression level of activating transcription factor 5 (ATF5) was frequently increased in glioma and its acetylation level was related to glioma. The purposes of this study were to explore the methylation level of ATF5 in clinical glioma tissues and to explore the effect of ATF5 methylation on the expression of ATF5 in glioma. Methylation of the promoter region of ATF5 was assayed by bisulfite-specific polymerase chain reaction (PCR) sequencing analysis in 35 cases of glioma and 5 normal tissues. Quantitative real-time PCR (qRT-PCR) was also performed to detect ATF5 mRNA expression in 35 cases of glioma and 5 normal tissues. Clinical data were collected from the patients and analyzed. The percentages of methylation of the ATF5 gene in the promoter region in healthy control, patients with well-differentiated glioma, and those with poorly differentiated glioma were 87.78%, 73.89%, and 47.70%, respectively. Analysis of the methylation status of the promoter region of the ATF5 gene showed a gradually decreased methylation level in poorly differentiated glioma, well-differentiated glioma, and normal tissues (P<0.05). There was also a significant difference between well-differentiated glioma and poorly differentiated glioma (P<0.05). ATF5 mRNA expression in glioma was significantly higher than that in the normal tissues (P<0.05). This study provides the first evidence that the methylation level of ATF5 decreased, and its mRNA expression was evidently up-regulated in glioma.