Latest ArticlesPolylactic acid (PLA) is one of the most suitable candidates for environmental pollution treatment because of its biodegradability which will not cause secondary pollution to the environment after application. However, there is still a lack of a green and facile way to prepare PLA oil-water separation materials. In this work, a water-assisted thermally induced phase separation method for the preparation of superhydrophobic PLA oil-water separation material with honeycomb-like structures is reported. The PLA material shows great ability in application and could adsorb 27.3 times oil to its own weight. In addition, it could also be applicated as a filter with excellent efficiency (50.9 m3 m-2 h-1).
A new star-shaped molecule StOF-Br3 containing oligofluorenes and halogen atoms (Bromine) has been synthesized and studied by Scanning Tunneling Microscopy (STM) at the highly oriented pyrolytic graphite (HOPG) surface. We have obtained the high-resolution self-assembled STM images, from which the highly ordered and closely packed non-porous arrangements of the StOF-Br3 molecular selfassemblies at the heptanoic acid/HOPG surface could be observed. The molecular models and selfassembled StOF-Br3 architectures have been given in the following text. Besides, we have also figured out the surface free energy by the density functional theory (DFT) calculation, which proved that the halogen···halogen interaction was strong enough to stabilize the ordered molecular self-assemblies. This work verifies the existence of bromine···bromine interactions, and meanwhile provides a kind of effective approach for quickly building ordered molecular nanoarchitectures with large areas and different geometries.
Surface chemical properties of supports have an important influence on active sites and their catalytic behavior. Here, we fabricated a series of cobalt-based catalysts supported by carbon layer-coated ordered mesoporous silica (OMS) composites for higher alcohol synthesis (HAS). The carbon layers were derived from different sources and uniformly coated on the porous surface of OMS. Combined with the characterization results of carbonized catalysts, it is demonstrated that the carbon layer-coated supports significantly enhanced the metal dispersion and increased the ratio of Co2+ to Co0 sites, which further increased the CO conversion and alcohols selectivity. Moreover, it is found that the catalytic activity changed in line with the amount of defects and surface oxygenic groups of carbon layers, which resulted from the different carbon sources. The highest space time yield of C2+OH was 27.5 mmol gcat-1 h-1) obtained by the catalyst coated with glucose-derived carbon layer. But the carbon source is not the key factor influencing the distribution of Co-Co2+ dual sites and shows little effect on selectivity in HAS. These results may guide for further design of carbon supported catalysts.
A seven-step total synthesis of α-cyclopiazonic acid is reported from a commercially available 4-bromoindole. Salient feature of the work is the rapid formation of tetracyclic skeleton via a bioinspired [3+2] annulation to form the C/D rings.
Two-dimensional mesoporous materials combing ultrathin nanosheet morphology with well-defined mesoporous structures, are now emerging and becoming increasingly important for their promising applications in energy storage, electronic devices, electrocatalysts and so on. Here, we synthesized a kind of polypyrrole-based two-dimensional mesoporous materials with uniform pore size, ultrathin thickness and high surface area. Serving for electrochemical NH3 sensor, they exhibited a fast response and high sensitivity. Therefore, our study would promote much interest in design of new materials for gas sensor applications.
Sulfamethazine (SMZ) is an important sulfonamide antibiotic. Although the concentration in the environment is small, it is harmful. The drug residues can be transferred, transformed or accumulated, affecting the growth of animals and plants. In this study, the integrated fixed-film activated sludge membrane bioreactor (IFAS-MBR) were constructed to investigate the performance and degradation mechanism of SMZ. The addition of SMZ had a significant impact on the removal of the chemical oxygen demand (COD) and ammonia nitrogen (NH4+-N). The optimal operating conditions were hydraulic retention time (HRT) at 10 h and solid retention time (SRT) at 80 d, respectively. On this basis, the effects of different SMZ concentrations on nutrient removal, degradation, and sludge characteristics were compared. The removal efficiency of SMZ increased with the increase of SMZ concentration. The maximum removal rate was as high as 87%. The SMZ dosage also had an obvious effect on sludge characteristics. As the SMZ concentration increased, the extracellular polymer substances (EPS) concentration and the membrane resistance both decreased, which were beneficial for the reduction of membrane fouling. Finally, seven kinds of SMZ biodegradation intermediates were identified, and the possible degradation pathways were speculated. The microbial community results showed that the microbial diversity and richness in the reactor decreased after adding SMZ to the influent. The relative abundance of Bacteroidetes, Actinobacteria, Saccharibacteria and Nitrospirae increased at the phylum level. Sphingobacteria and Betaproteobacteria became dominant species at the class level. The relative abundance of norankp-Saccharibacteria and Nitrospirae increased significantly, and norank-p-Saccharibacteria may be the dominant bacteria for SMZ degradation.
Kerogen is known as an important organic part for absorbing and forming shale gas whose absorption function, especially mechanical and tribological properties, has not been fully revealed. Here, we use Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis to reveal the chemical structure of kerogen. We report the first study of the adhesion and friction behavior of kerogen using atomic force microscope (AFM) Nanoman technology. Our finding reveals the friction of kerogen is decreased at higher pressure while is inhibited at increased temperature, and friction decreases logarithmically as the sliding speed increases. The weakened of Al-O linkage at high temperature have great influence on the decrease of friction forces between kerogen and alumina pellet. This finding lays the mechanism for understanding the dynamic adhesion behavior of kerogen in frictions, therefore attracting increasing interests from scientists, researchers, petroleum engineers and investors.
A quinine-derived thiourea-catalyzed inter-/intramolecular Michael cycloaddition of chromoneoxindole/benzofuranone synthons with 3-substituted methylenebenzofuranones has been established, which constructed enantiomerically pure bispiro[benzofuran-oxindole/benzofuran-chromanone]s bearing five consecutive stereocenters including two spiro quaternary carton centers in good yields (up to 93%) with high diastereoselectivities (up to >20:1 dr) and good enantioselectivities (up to >99% ee). Moreover, this is the first example of bifunctional chromone-benzofuranone synthon directed organocatalytic tandem reaction, and also the first example of the bispiro[benzofuran-oxindole] and bispirobenzofuranone, potentially useful in medicinal chemistry.
In order to optimize mass transportation and exchange, nature creates hierarchically porous networks which are composed of multi-level branches. Although bottom-up templating methods have succeeded in fabrication of these kinds of hierarchically porous networks, the templates have to be assembled/ packed in advance, therefore, driving the fabrication process too complex. In this report, we presented that the hierarchically porous networks could be fabricated through migration of templates, which was similar to formation of rivers. During thermal pyrolysis of Prussian blue cages, the in situly generated iron oxides nanoparticles diffused and aggregated together to grow larger, and eventually moved outside from the porous carbons. The moving routes of the iron oxides became hierarchical channels in the obtained carbon cages. By using the porous carbon cages as electrode for Na-ion battery, a pseudocapacitor-type ion storage was investigated.
Alkaline phosphatase (ALP) is one of essential biomarkers in mammalian tissue. Here we report a ratiometric probe for ALP, which is rationally designed and synthesized by employing ESIPT fluorophore N-(3-(benzo[d]thiazol-2-yl)-4-hydroxyphenyl)benzamide (BTHPB). The enzymatic dephosphorylation converts the probe to BTHPB, which exhibits a large spectral red-shift (120 nm), allowing extremely high sensitivity of ALP sensing at 0.004 mU/mL. The probe also shows excellent biocompatibility and has been applied for monitoring the endogenic ALP in living cells.
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