Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences
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A mixed-valent Cu-I/Cu-II metal-organic framework with selective chemical sensing properties
No full textA novel 3D mixed-valent Cu-I/Cu-II metal-organic framework has been solvothermally synthesized and characterized by single-crystal X-ray diffraction, photoluminescence spectroscopy, thermal gravimetric analysis, and powder X-ray diffraction. The structure possesses a 3D open framework constructed from the linkages of 1D [Cu-I(4,4'-bipy)](n) chains with [Cu-II(oda)(2)](2-) cationic subunits. The chemical sensing properties of this MOF have been studied by the quartz crystal microbalance technique. The framework exhibits good selectivity and sensitivity to water with respect to other organic solvents in view of chemical sensing applications
Paper reinforced with regenerated cellulose: a sustainable and fascinating material with good mechanical performance, barrier properties and shape retention in water
No full textCellulosic materials are becoming more and more important in our daily life. However, if cellulose in its natural form such as paper is to be applied in advanced applications, it should exhibit unique characters in mechanical performance, barrier properties, etc. This paper describes a new method to design and fabricate a pure cellulosic composite with excellent mechanical and barrier properties via simple coating and cross-linking between original paper and regenerated cellulose. The cellulosic composite overcomes the shortcomings of the low mechanical and barrier performance of original paper. This material had an ultrahigh tensile strength, a high elongation and toughness at break of 76 MPa, 12% and 7 MJ m(-1), and 13 MPa, 11% and 0.75 MJ m(-3) under wet conditions, which were greater than those of original paper (dry: 20 MPa, 2.8%, 0.3 MJ m(-3); wet: 1.08 MPa, 2.8%, 0.028 MJ m(-3)). Besides, the composite papers showed good barrier properties for small molecules such as polar molecules (H2O) and non-polar molecules (O-2). Interestingly, the as-synthesized material exhibited shape-retention when the material was wetted with water
Thin-Film Transformation of NH4PbI3 to CH3NH3PbI3 Perovskite: A Methylamine-Induced Conversion-Healing Process
No full textMethylamine-induced thin-film transformation at room-temperature is discovered, where a porous, rough, polycrystalline NH4PbI3 non-perovskite thin film converts stepwise into a dense, ultrasmooth, textured CH3NH3PbI3 perovskite thin film. Owing to the beneficial phase/structural development of the thin film, its photovoltaic properties undergo dramatic enhancement during this NH4PbI3-to-CH3NH3PbI3 transformation process. The chemical origins of this transformation are studied at various length scales
Resonance assignments of a VapC family toxin from Clostridium thermocellum
No full textToxin-antitoxin (TA) systems widely exist in bacterial plasmids, phages, and chromosomes and play important roles in growth persistence and host-pathogen interaction. Virulence associated protein BC (VapBC) family TAs are the most abundant TAs in bacteria and many pathogens contain a large number of vapBC loci in the genome which have been extensively studied. Clostridium thermocellum, a cellulolytic anaerobic gram-positive bacterium with promising applications in biofuel production, also contains a VapBC TA in the genome. Despite the structures of several VapBC family TAs have been determined, the toxin and anti-toxin components of C. thermocellum VapBC have very low sequence identity to the proteins in PDB. Therefore, the structure and functional mechanism of this TA is largely unknown. Here we reported the NMR resonance assignments of the VapC toxin from C. thermocellum as a basis for further structural and functional studies
Carbonate-linked poly(ethylene oxide) polymer electrolytes towards high performance solid state lithium batteries
No full textThe classic poly(ethylene oxide) (PEO) based solid polymer electrolyte suffers from poor ionic conductivity of ambient temperature, low lithium ion transference number and relatively narrow electrochemical window (< 4.0 V vs. Li+/Li). Herein, the carbonate-linked PEO solid polymer such as poly (diethylene glycol carbonate) (PDEC) and poly(triethylene glycol carbonate) (PTEC) were explored to find out the feasibility of resolving above issues. It was proven that the optimized ionic conductivity of PTEC based electrolyte reached up to 1.12 x 10(-5) S cm(-1) at 25 degrees C with a decent lithium ion transference number of 0.39 and a wide electrochemical window about 4.5 V vs. Li+/Li. In addition, the PTEC based Li/LiFePO4 cell could be reversibly charged and discharged at 0.05 C-rates at ambient temperature. Moreover, the higher voltage Li/LiFe0.2Mn0.8PO4 cell (cutoff voltage 4.35 V) possessed considerable rate capability and excellent cycling performance even at ambient temperature. Therefore, these carbonate-linked PEO electrolytes were demonstrated to be fascinating candidates for the next generation solid state lithium batteries simultaneously with high energy and high safety. (C) 2016 Elsevier Ltd. All rights reserved
Eluent Tolerance and Enantioseparation Recovery of Chiral Packing Materials Based on Chitosan Bis(Phenylcarbamate)-(n-Octyl Urea)s for High Performance Liquid Chromatography
No full textThe goal of the present work was to study the influence of the swelling of chitosan derivatives on the enantioseparation and the separation performance recovery of chiral stationary phases (CSPs) based on these derivatives. Therefore, six chitosan bis(phenylcarbamate)-(n-octyl urea)s were synthesized, which were coated on macroporous 3-aminopropyl silica gel affording new CSPs. Most of the CSPs demonstrated strong enantioseparation capability for the tested chiral compounds. The swelling capacity of the chitosan bis(phenylcarbamate)-(n-octyl urea) s in ethyl acetate, acetone and tetrahydrofuran (THF) was evaluated. Among the chitosan derivatives, the chitosan bis(3,5-dichlorophenylcarbamate)-(n-octyl urea) polymer showed the highest swelling capacity in ethyl acetate and THF. The polymer-based CSPs could be utilized with pure ethyl acetate and a normal phase containing 70% THF, but was damaged by pure THF. On the other hand, the separation performance of the damaged CSP could be recovered after it was allowed to stand for a period of time. The observations are important for the development and application of polysaccharide derivative-based CSPs
Antibiofilm and Anti-Infection of a Marine Bacterial Exopolysaccharide Against Pseudomonas aeruginosa
No full textPseudomonas aeruginosa is a well-known pathogenic bacterium that forms biofilms and produces virulence factors, thus leading to major problems in many fields, such as clinical infection, food contamination, and marine biofouling. In this study, we report the purification and characterization of an exopolysaccharide EPS273 from the culture supernatant of marine bacterium P. stutzeri 273. The exopolysaccharide EPS273 not only effectively inhibits biofilm formation but also disperses preformed biofilm of P aeruginosa PAO1. High performance liquid chromatography traces of the hydrolyzed polysaccharides shows that EPS273 primarily consists of glucosamine, rhamnose, glucose and mannose. Further investigation demonstrates that EPS273 reduces the production of the virulence factors pyocyanin, exoprotease, and rhamnolipid, and the virulence of P aeruginosa PAO1 to human lung cells A549 and zebrafish embryos is also obviously attenuated by EPS273. In addition, EPS273 also greatly reduces the production of hydrogen peroxide (H2O2) and extracellular DNA (eDNA), which are important factors for biofilm formation. Furthermore, EPS273 exhibits strong antioxidant potential by quenching hydroxyl and superoxide anion radicals. Notably, the antibiofouling activity of EPS273 is observed in the marine environment up to 2 weeks according to the amounts of bacteria and diatoms in the glass slides submerged in the ocean. Taken together, the properties of EPS273 indicate that it has a promising prospect in combating bacterial biofilm-associated infection, food-processing contamination and marine biofouling
Impacts of microaeration on the anaerobic digestion of corn straw and the microbial community structure
No full textConventionally, oxygen is considered as inhibit factor of anaerobic digestion (AD). However, recent studies have demonstrated that AD performance could be enhanced by introducing limited amounts of oxygen (or air) directly into the anaerobic digester or during pretreatment step. In this study, impacts of microaeration on the anaerobic digestion of corn straw and the microbial community structure were investigated. Results showed that limited air introduced into fermentation system could improve the methane yield of corn straw. Maximum cumulative methane yield of 216.8 ml/g VSsubstrate and maximum VS removal efficiency of 54.3% were simultaneously obtained under microaerobic condition with the air load of 12.5 ml/L-R per day, which were 16.5% and 10.3% higher than those of sample under anaerobic condition, respectively. Compared to anaerobic condition, the relative abundances of phylum Firmicutes, class Clostridia and order Clostridiales, which associated with hydrolysis process of AD were raised under microaerobic condition. In addition, the relative abundances of oxytolerant Methanosarcina and Methanobacterium were both doubled under microaerobic condition. Accordingly, specific methanogenic activity (SMA) under microaerobic condition improved slightly. The microbial community shift might be the reason for improved AD performance under microaerobic condition. (C) 2015 Elsevier B.V. All rights reserved
Size-dependent activity of unsupported Co-Mo sulfide catalysts for the hydrodesulfurization of dibenzothiophene
No full textA series of CoMoO4 hydrates composed of nanorods have been synthesized with different alcohol-water solvent systems, and the corresponding Co-Mo sulfides are obtained after sequential calcination and sulfurization. The characterization results show the change in solvent system can efficiently adjust the particle size of the Co-Mo precursors, while cannot affect their components and morphologies. Because of the different particle size, the specific surface areas (SSA) of the final Co-Mo sulfides are different. The particles with small size can lead to a high SSA that benefits the exposure and dispersion of active components, and further promote the incorporation of MoS2 slabs with Co atoms to form "Co-Mo-S" structures on the surface of the sulfides. More "Co-Mo-S" structures would create more coordinative unsaturated sites with high activity in situ during hydrodesulfurization (HDS) reaction, resulting in a higher HDS activity. Among the Co-Mo sulfides, since S-mew derived from methanol-water system possesses the smallest particle size and the most active sites, it naturally exhibits the highest HDS activity toward dibenzothiophene. (C) 2015 Elsevier B.V. All rights reserved
Effect of hierarchical crystal structures on the properties of cobalt catalysts for Fischer-Tropsch synthesis
No full textMesoporous ZSM-5 was synthesized using double-template method and its application in FischerTropsch synthesis (FTS) was studied. By comparison, ZSM-5 and SBA-15 were also prepared. The results demonstrated that the catalysts with bimodal structure and moderate acidity showed higher C5-18 selectivity with relatively lower CH4 selectivity, while higher C5-12 selectivity over Co/ZSM-5 catalyst and higher C12-18 selectivity over Co/SBA-15 catalyst were observed, respectively. Cobalt loaded on crystalline mesoporous ZSM-5 showed the lowest deactivated rate, which suggested that such bimodal structure was favor to the stabilization of cobalt particles. As a result of lower hydrothermal stability of mesopority, Co/SBA-15 catalyst had the fastest deactivation. (c) 2016 Elsevier Ltd. All rights reserved