Self-assembly of TiO2/ZIF-8 nanocomposites for varied photocatalytic CO2 reduction with H2O vapor induced by different synthetic methods.

Photoreduction of carbon dioxide (CO2) provides an effective perspective for solving the energy crisis and environmental problems. Herein, two types of composite photocatalysts (TiO2/ZIF-8) based on ZIF-8 and TiO2 have been designed and synthesized with the help of the grinding method and the solid-synthesis method. Both composite photocatalysts are employed for the photocatalytic reduction of CO2. In composite photocatalysts prepared by the grinding method, ZIF-8 particles are distributed on the surface of TiO2, and provide extra available spaces for storing CO2, which is beneficial for improving their photoreduction performances. As a result, an enhanced CO formation rate of 21.74 µmol g-1 h-1 with a high selectivity of 99% is obtained for this family of composite photocatalysts via the solid-gas mode without photosensitizers and sacrificial agents. For comparison, the other family of composite photocatalysts synthesized via the solid-synthesis method possesses structures similar to ZIF-8, where TiO2 is encapsulated inside the framework of ZIF-8. This structural feature obstructs the contact between the active sites of TiO2 and CO2, and leads to lower activities. The best CO formation rate of this family is only 10.67 µmol g-1 h-1 with 90% selectivity. Both the structural features of the two families of photocatalysts are described to explain their differences in photoreduction performances. The experimental finding reveals that different synthetic approaches indeed result in diversified structures and varied photocatalytic performances. This work affords a new scalable and efficient approach for the rational design of efficient photocatalysts in the area of artificial photosynthesis.

External electric field: a new catalytic strategy for the anti-Markovnikov hydrohydrazination of parent hydrazine.

The anti-Markovnikov hydroamination reaction is considered to be a particular challenge, and one of the reactants, parent hydrazine, is also regarded as a troubling reagent. In this study, we first studied the hydrohydrazination of parent hydrazine via an effective and green catalyst-external electric field (EEF). The calculation results demonstrated that the anti-Markovnikov and Markovnikov pathways are competitive when there was no catalyst. EEF oriented along the negative direction of the X axis (F x ) accelerated the anti-Markovnikov addition reaction. Moreover, it lowered the barrier height of the first step by 16.0 kcal mol-1 (from 27.8 to 11.8 kcal mol-1) when the field strength was 180 (×10-4) au. Under the same conditions, the Markovnikov reaction pathway was inhibited, which means that EEF achieved the specificity of hydrohydrazination. The solvents are favorable for the first step addition reaction, particularly the synergy between solvents and F x lowered the barrier heights by 8.3 (C6H6) and 10.7 (DMSO) kcal mol-1 for an F x = -60 (×10-4) au. Besides, the introduction of the electron-withdrawing substituent (trifluoromethyl) is also a good strategy to catalyze hydrohydrazination, while the electron-donating group (methoxy) is unfavorable.

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.

Synergetic effect of H+ adsorption and ethylene functional groups of covalent organic frameworks on the CO2 photoreduction in aqueous solution.

We prepare a novel COF for CO2 photoreduction with 99.9% CO selectivity in aqueous solution without a cocatalyst. DFT shows that the preferential adsorption of H+ on the COF results in increased CO2 adsorption energy providing an anchoring site of CO2, and with the cooperation of an ethylene group, CO2 reduction is triggered.

Polyoxometalate-based metallogels as anode materials for lithium ion batteries.

A series of polyoxometalate (POM)-based metallogels have been synthesized, which combine both the advantages of POMs and metallogels. Notably, POM-based metallogels are employed as anode materials for the first time, and the optimized sample exhibits high reversible capacity (658 mA h g-1), high rate capability, and good cycling stability.

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.

A new triazine-based covalent organic polymer for efficient photodegradation of both acidic and basic dyes under visible light.

A new triazine-based covalent organic polymer (named COP-NT), which showed high catalytic activities for the degradation of acidic and basic dyes, is synthesized. Its structure characteristics were fully investigated, which featured large specific surface area, homogeneous porosity, strong visible light absorption, excellent thermal stability and semiconductor performance. The as-prepared COP-NT exhibits good chemical stability both in acidic and alkaline aqueous solutions, which could be used as an efficient photocatalyst for the degradation of methyl orange (MO), rhodamine B (RhB) and methylene blue (MB). The Ea values for the degradation of MO, RhB or MB are 9.40 kJ mol-1, 30.94 kJ mol-1 or 17.54 kJ mol-1, respectively. Furthermore, COP-NT showed excellent reusability in degrading all the above dyes without obvious performance decay.

Multifunctional luminescent Zn(ii)-based metal-organic framework for high proton-conductivity and detection of Cr3+ ions in the presence of mixed metal ions.

A luminescent MOF with rectangular channels was synthesized and characterized. It is capable of showing a high proton conductivity up to 0.95 × 10-2 S cm-1 at 60 °C and 97% RH, and sensing metal ions (particularly Cr3+ ions), through fluorescence quenching in presence of mixed metal ions.

[Distribution and environmental function of glomalin-related soil protein: A review].

Glomalin-related soil protein (GRSP), a glycoprotein secreted by arbuscular mycorrhizal fungi (AMF), is abundant in soil. GRSP can be fractionated into total glomalin-related soil protein (TG), easily extracted glomalin-related soil protein (EEG), immunoreactive total glomalin (IRTG) and immunoreactive easily extracted glomalin (IREEG). The content of GRSP in soil differed with different soil use type, fertilization condition, AMF and host plant species, and environmental conditions. GRSP significantly positively correlates to the aggregate water stability. GRSP may reduce the release of CO2 in agro-ecosystem, benefit the soil carbon fixation, and reduce the bioavailability and plant toxicity of heavy metals in soil. The extraction and characterization of GRSP are of great importance to understanding the basic behaviors of GRSP in soil environments. Further studies are needed to clarify the molecular biology function of GRSP in agro-ecosystem based on the knowledge of proteins and related genes, and impacts of GRSP on the environmental behavior of organic pollutants in soil.

A visible light-driven photocatalyst of a stable metal-organic framework based on Cu4Cl clusters and TIPE spacers.

A 3D new metal-organic framework (MOF) [Cu4Cl(TIPE)3]·3Cl (1) has been synthesized and characterized. Compound 1 exhibits good chemical stability in aqueous solution with the pH ranging from 1 to 11. Interestingly, compound 1 shows high catalytic activities for the degradation of dyes (RhB, MB and MO) under LED and natural light irradiation. The Ea of 1 for RhB, MB and MO degradation is obtained to be 79.71, 66.14 and 87.26 kJ mol(-1), respectively. Furthermore, compound 1 can be reused in the catalytic process without the catalytic activity obviously decreasing.

Rational design of a highly sensitive and selective "turn-on" fluorescent sensor for PO4(3-) detection.

An efficient turn-on fluorescent sensor for PO4(3-) has been developed by rationally designing an in situ-generated iron(iii) complex with a 1,8-naphthalene-based Schiff base unit. The sensor exhibits high sensitivity and selectivity in both solution and solid-state film, even in the presence of other phosphate anions such as HPO4(2-) and H2PO4(-).

Identification of differentially expressed microRNAs between Bacillus thuringiensis Cry1Ab-resistant and -susceptible strains of Ostrinia furnacalis.

The Asian corn borer (ACB), Ostrinia furnacalis (Guenée), can develop strong resistance to Cry1Ab, the most widely commercialized Cry toxin for Bt maize worldwide. It is essential to understand the mechanism of resistance for management of this species, but information on the post-transcriptional regulation of Bt resistance in this target insect is limited. In the present study, RNA was extracted from the ACB in various larval stages (1-5 instar) from Cry1Ab-sensitive (ACB-BtS) and -resistant (ACB-AbR) strains, each of which included two biological replicates. Using Illumina sequencing, a total of 23,809,890 high-quality reads were collected from the four ACB libraries. The numbers of known microRNAs (miRNAs) were 302 and 395 for ACB-BtS and 268 and 287 for ACB-AbR. Using Mireap software, we identified 32 and 16 potential novel miRNAs for ACB-BtS and 18 and 22 for ACB-AbR. Among them, 21 known and 1 novel miRNAs had significantly different expression between ACB-BtS and ACB-AbR. Several miRNAs were observed to target potential Bt receptor genes, such as aminopeptidase N and cadherin-like protein. The glycosylphosphatidylinositol-anchor biosynthetic process and ABC transporters pathway were identified through Gene Ontology and KEGG pathway analysis of target genes of the differentially expressed miRNAs.

Heparanase mRNA expression and point mutation in hepatocellular carcinoma.

AIM: To explore the expression of heparanase mRNA and point mutation in hepatocellular carcinoma (HCC). METHODS: Reverse transcription polymerase chain reaction was used to measure the expression of heparanase mRNA in the primary tumor tissues and surrounding liver tissues of 33 HCC patients. T-A cloning and sequencing were used to detect whether there was any mutation in the amplified PCR products. RESULTS: The expression of heparanase mRNA was positive in 16 primary tumor tissues of HCC, and the positive rate was 48.5%, which was significantly higher than that in the surrounding liver parenchyma (P<0.01). The positive rate for heparanase gene in high-tendency to metastatic recurrence group (71.4%, 10/14) was obviously higher than that in low-tendency to metastatic recurrence group (31.6%, 6/19) (P = 0.023). The positive rate for heparanase gene in patients with metastatic recurrence during postoperative follow-up (78.6%, 11/14) was also significantly higher than that in those without metastatic recurrence (21.4%, 3/14) (P = 0.003). Sequence analysis of the HPA PCR products was made in 7 patients, and 2-point mutations were found in 4 patients, one of which was sense mutation, neither base insertion nor deletion was detected. The mutation rate was 57.1% (4/7). CONCLUSION: The expression rate of heparanase mRNA increases in HCC, and HPA mRNA may be one of the reliable markers for the metastatic activity gained by the liver tumor cells and could be used clinically in predicting metastatic recurrence of HCC. Point mutation may be one of the causes for enhanced heparanase mRNA expression.