Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences
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Quinary Interactions Weaken the Electric Field Generated by Protein Side-Chain Charges in the Cell-like Environment
No full textThe intramolecular electric field (e-field) generated by protein GB3 side-chain charges K/E10, K/E19, and D/K40 was measured in the absence or presence of macromolecular crowding. The e-field responds differently to different crowding agents-dextran, Ficoll, BSA, and E. coli cell lysate. Dextran and Ficoll have no effect on the e-field. The lysate generally weakens the e-field but the amplitude of weakening varies greatly. For example, the e-field by K19 is reduced by 67% in the presence of 90 g/L lysate, corresponding to a charge change from 0.9 to 0.3 e for K19, whereas the e-fields by D/K40 are weakened only by, similar to 7% under the same lysate concentration. The extent of the e-field weakening by BSA is in between that by Ficoll (dextran) and lysate. Further investigations, suggest that the e-field weakening mechanism by lysate is similar to that by NaCl. That is, the e-field generated by a protein surface charge affects the distribution of lysate which creates a reaction field and weakens the protein e-field. Our study indicates that the protein electrostatic property can be changed significantly due to quinary interaction with the cell environment
Microwave-assisted one-pot conversion from deoiled asphalt to green fluorescent graphene quantum dots and their interfacial properties
No full textHigh-quality graphene quantum dots (GQDs) were prepared through a facile route of microwave-assisted one-step mild oxidation of cheap deoiled asphalt (DOA). The as-prepared DOA-derived GQDs dissolved in water with a much smaller and thinner size than most of the reported GQDs, and luminesced bright green light by excitation of 365nm. Furthermore, the GQDs possessed excellent properties of excitation-tuned fluorescence behavior with a high quantum yield up to 16.4%. In addition, the GQDs showed amphipathic properties and could significantly reduce the interfacial tension, which give them great potential as surfactants for asphalt emulsion
Improving the production of acetyl-CoA-derived chemicals in Escherichia coli BL21(DE3) through iclR and arcA deletion
No full textBackground: Acetyl-CoA-derived chemicals are suitable for multiple applications in many industries. The bio-production of these chemicals has become imperative owing to the economic and environmental problems. However, acetate overflow is the major drawback for acetyl-CoA-derived chemicals production. Approaches for overcoming acetate overflow may be beneficial for the production of acetyl-CoA-derived chemicals
Feasibility of attached cultivation for polysaccharides production by Porphyridium cruentum
No full textPorphyridium cruentum is one of the most valued microalgae species able to produce both pigments and exopolysaccharides. Conventional liquid suspended cultivation in ponds and photobioreactors show its disadvantages in lower cultivation efficiency and higher stirring power consumption due to the high viscosity of the medium by the accumulation of polysaccharides. In this work, a new method of culture (called attached cultivation) based on the growth of microalgae using a supporting surface was successfully applied to the cultivation of P. cruentum and the effect of the main influential parameters on its growth rate and polysaccharides production has been investigated. Higher values of these factors resulted in a faster growth rate and, in particular, optimum values of 6.98 g m(-2) for initial biomass density, 100 A mu mol m(-2) s(-1) for light intensity, continuous illumination, 2.0 % for CO2 concentration, and 0.1 v v(-1) min(-1) for aeration rate produced the best polysaccharide production of 42 % dry weight. The nutrition profile of P. cruentum obtained in attached and suspended cultivations was similar. Overall these results demonstrate that the attached cultivation is a promising technique which greatly improves the growth rate of P. cruentum as well as its production of polysaccharides and, therefore, it is worth enhancing to be exploited for commercial application
Effect of Zn/Al ratio of Ni/ZnO-Al2O3 catalysts on the catalytic deoxygenation of oleic acid into alkane
No full textNi-based catalysts supported on Zn-Al composite oxides have been prepared for the catalytic deoxygenation of oleic acid into diesel-ranged alkanes, and the effects of the Zn/Al ratio on the physico-chemical properties of the supports and the deoxygenation activity of the final catalyst were investigated in detail. The results showed that higher Zn/Al ratios led to lower specific surface area of the supports and weakening of the interaction between Ni species and supports thereby improving the reducibility of Ni species. However, higher Zn/Al ratios may limit the dispersion of Ni species, leading to a decrease in the exposure of metallic Ni. Because the conversion and deoxygenation of the reactants mainly depended on the hydrogenation capability of the catalysts which was controlled by the amount of exposed metallic Ni, the catalyst with a Zn/Al ratio of 2/1 showed the highest hydrogenation rate and alkane yield. Further decreasing the Zn/Al ratio led to strong metal-support interaction, making the Ni species difficult to reduce, which may also inhibit the formation of alkane products. In addition, the change in Zn/Al ratio affected intermediate type, which could affect the yield of alkane products. (C) 2016 Elsevier B.V. All rights reserved
Fabrication of transition metal selenides and their applications in energy storage
No full textElectrochemical energy storage devices (lithium ion batteries, sodium ion batteries, magnesium ion batteries, and super capacitors) with high power and energy densities are considered the most promising equipment for large-scale applications of portable electronic devices and electric vehicles. These devices can be realized by exploring nanostructured materials with high capacity, favorable cycling stability, and superior rate capability. Transition metal selenides (TMSs) are potential materials for electrochemical energy storage systems. In this paper, we summarized the nanostructured transition metal selenides and indicated their properties, preparation methods, and applications in electrochemical energy storage systems. We discussed the electronic properties of TMSs and showed that these materials have tunable electronic properties. We enumerated the 10 most-used preparation methods of TMSs as well as their composites with other functional materials. Subsequently, we systematically reviewed their applications in lithium ion batteries, sodium ion batteries, magnesium ion batteries, and super capacitors. Finally, we proposed the challenges and opportunities of their applications in energy storage. (C) 2016 Elsevier B.V. All rights reserved
Synergically Improving Light Harvesting and Charge Transportation of TiO2 Nanobelts by Deposition of MoS2 for Enhanced Photocatalytic Removal of Cr(VI)
No full textHerein, MoS2/TiO2 nanobelts heterojunction have been successfully synthesized by in situ growth method for photocatalytic reduction of Cr(VI). TiO2 nanobelts (NBs) with rough surface were prepared firstly by acidic treatment process, which is beneficial for deposition and growth of MoS2 to form heterojunctions. As a result of special energy level offset and nanostructure, MoS2/TiO2 NBs composite were endowed with higher light-harvesting capacity and charge transportation efficiency, which are indispensible merits for excellent photocatalytic activity. The photocatalytic reduction of Cr(VI) reveals that the synthesized MoS2/TiO2 NBs composite have superior photocatalytic ability than other samples. Meanwhile, a photoreduction mechanism is proposed based on the systematic investigation, where the photogenerated electrons are demonstrated as the dominant reductive species to reduce Cr(VI) to Cr(III)
Multifunctional porous organic polymers embedded with magnetic nanoparticles
No full textMultifunctional hybrid polycarbazoles were prepared with a novel core-spacer-shell structure. Magnetism, a conjugated system and an ultramicroporous structure are combined in one bulk material. SEM and TEM images show the obvious core@shell structure in the nano-region. Nitrogen gas sorption, magnetic and surface wettability analyses indicate the multifunctionality of the obtained materials. Their high efficiency dynamic adsorption (water treatment) and static separation (CH4/CO2 gas selectivity) allow these novel materials to be employed as facile tools for environmental treatment and in energy storage fields
Heavy metals in surface sediments along the Weihai coast, China: Distribution, sources and contamination assessment
No full textThe Weihai coast is a representative zone with fifty-year history of mariculture in China. Algae and shellfish are the main cultured species, other species including fish and sea cucumber are also cultivated. In this study, heavy metals in surface sediments, sampled along the Weihai coast during May yearly between 2009 and 2013 were investigated in terms of their contents and spatiotemporal variation. The contents of Zn, Cr, Cu, Cd, Pb and As showed different spatiotemporal variations and ranged between 11.6 and 115.9, 4.15-51.3, 5.2-21.9, 0.02-0.33, 6.0-54.2, and 2.9-18.7 mu g g(-1), respectively. Among them, Zn, Cu and As declined during the five years. Ecological risk assessment revealed that Cd posed a moderate risk, as compared to other five elements, which were relatively low risks in surface sediments. Source analysis revealed that Zn, Cr and Cd were mainly from lithogenic contribution, while As was likely from anthropogenic discharges. (C) 2016 Elsevier Ltd. All rights reserved
A Simple and Low-Cost Synthesis of Antibacterial Polyurethane with High Mechanical and Antibacterial Properties
No full textIn this paper, a simple and low-cost approach for the preparation of quaternary ammonium salt (QAS)-containing antibacterial polyurethane (APU) films is described. Epichlorohydrin (ECH), an inexpensive and commercially available chemical, is used to prepare the low-cost antimicrobial PECH-QAS. Then PECH-QAS, three-armed PPG, linear PPG, and diisocyanate are introduced for the synthesis of the APU prepolymer without any solvent in one pot for the first time. Water and three-armed PPG act as the cross-linking initiator and cross-linker in the preparation of the APU films. Using water as the initiator makes the preparation process more environment-friendly, and the cross-linked network guarantees the resistance of the film toward solvent corrosion. The influence of molecule weight of PECH-QAS, PECH-QAS concentration, cross-link density, and diisocyanate types on the mechanical properties and antibacterial properties of the APU films is extensively investigated. The optimized APU films exhibit high mechanical performance and excellent antibacterial properties