Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences
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近海生态系统碳汇过程、调控机制及增汇模式
No full text海洋是地球上最大的碳库,发挥着全球气候变化“缓冲器”的作用. 蓝色碳汇,简称“蓝碳”,即由海洋生
态系统捕获的碳(主要是有机碳),是海洋储碳的重要机制之一.蓝碳最初认识的形式是可见的海岸带植物固碳.
其实之前没有得到足够重视的、 看不见的微型生物(浮游植物、 细菌、 古菌、 病毒、 原生动物)占海洋生物量
90%以上,是蓝碳的主要贡献者. 中国陆架边缘海占国土总面积的1/3,碳汇潜力巨大,亟待研发. 本文以近海生
态系统碳汇过程、 调控机制及增汇模式为主线,论述了近海生态系统结构与碳循环功能特征、 碳汇形成过程
与机理,并结合近海碳汇在沉积记录中的地史过程演变探讨了自然过程和人类活动对碳汇的可能影响,展望
了碳汇工程在增加近海海洋储碳能力方面的应用前
Bidirectional Electron-Transfer in Polypeptides with Various Secondary Structures
No full textThe protein-mediated bidirectional electron transfer (ET) is the foundation of protein molecular wire, and plays an important role in the rapid detection of oxo-guanine-adenine DNA mismatches by MutY glycosylase. However, the influences of structural transitions on bidirectional ET are still not clear. In this work, the modified through-bond coupling (MTBC) model was further refined to correlate
Enhanced poly(3-hydroxypropionate) production via β-alanine pathway in recombinant Escherichia coli.
No full textPoly(3-hydroxypropionate) (P3HP) is a thermoplastic with great compostability and biocompatibility, and can be produced through several biosynthetic pathways, in which the glycerol
pathway achieved the highest P3HP production. However, exogenous supply of vitamin B12
was required to maintain the activity of glycerol dehydratase, resulting in high production
cost. To avoid the addition of VB12, we have previously constructed a P3HP biosynthetic
route with β-alanine as intermediate, and the present study aimed to improve the P3HP production of this pathway. L-aspartate decarboxylase PanD was found to be the rate-limiting
enzyme in the β-alanine pathway firstly. To improve the pathway efficiency, PanD was
screened from four different sources (Escherichia coli, Bacillus subtilis, Pseudomonas fluorescens, and Corynebacterium glutamicum). And PanD from C. glutamicum was found to
have the highest activity, the P3HP production was improved in flask cultivation with this
enzyme. To further improve the production, the host strain was screened and the culture
condition was optimized. Under optimal conditions, production and content of P3HP
reached to 10.2 g/L and 39.1% (wt/wt [cell dry weight]) in an aerobic fed-batch fermentation.
To date, this is the highest P3HP production without VB1
The miR156-SPL4 module predominantly regulates aerial axillary bud formation and controls shoot architecture.
No full textTwo Players Make a Formidable Combination: In Situ Generated Poly(acrylic anhydride-2-methyl-acrylic acid-2-oxirane-ethyl ester-methyl methacrylate) Cross-Linking Gel Polymer Electrolyte toward 5 V High-Voltage Batteries
No full text化学工程
No full textAbstract
Currently available fresh water is very scarce in global surface and groundwater.
Seawater desalination, collection and wastewater reuse are the only way to solve the
shortage of water resources. Membrane processes desalination technology has been
widely used in many fields and expanding, which has been widely applied process
including nanofiltration (NF) and reverse osmosis (RO), electrodialysis (ED), and
other technologies. Aiming at the deficiency of membrane technologies in water
desalination process, such as desalinating high salt and easily scaling water will arise
the problem of membrane fouling. This study not only from the aspects of technology,
put forward a new process: NF and ED combination (namely Fracsis) for ion
separation and recombinant, but also did a further research about the principle of ion
separation: preparing the functional membrane to improve the ion separation
performance of electrodialysis. First, the NF membrane can effectively separate
almost the bivalent ions into the condensed solution, then put the desalinated and
concentrated solution into the different chambers of ED. Under the electric field, the
ions of cations and anions were moving towards the opposite direction, so as to obtain
high salt solubility, improving the water recovery. After that, in the process of
preparation of ion exchange membrane, the traditional method for preparing
nanofiltration membrane, layer-by-layer self-assembly was used to modified
commercial anion exchange membrane surface, preparing the different layers of
polyelectrolyte membrane, to improve the ion selectivity of anion exchange
membrane. The following conclusions were got through this paper study:
(1) In Fracsis process, the NFS membrane obtained a high rejection for Ca
2+
, all
were above 98% in three pH systems, effective separation for bivalents. In ED
metathesis experiment, bivalent ions recombined with monovalent ions obtaining high
solubility salts. The water recovery rate after ED is higher than the theoretical value
no fouling in RO system, reached 80% in pH = 4 system. And through the theoretical calculation, the Fracsis system can reach the highest in the theoretical value of 98.5%.
The energy consumption of Fracsis system had carried on a simple calculation. The
energy consumption of the batch operation system was 4.2 to 4.8 RMB/m
3
. The
energy consumption is expected to further reduce through optimizing operation
parameters, expand the scale, installation of energy recovery device. Fracsis system
have prominent advantages for improving water recovery, reduce the sludge
production and the processing costs, which is expected to be applied to the synthesis
of organic or inorganic salt and the enrichment process.
(2) This research used simple and flexible method of layer-by-layer self-assembly
to modify the anion exchange membrane surface, prepared one kind of thin-film
composite anion exchange membrane with high ion selectivity for Cl
-
and SO 4
2-
. The
ion selectivity of base membrane was 1.0, and the increased with the layers number.
When modified by 5.5 layers, the selectivity was better than the commercial ACS
membrane with the value of 4.5.
Another hand, the modified anion exchange membranes were also evaluated by the
performance of separated organic acids. In the ED experiment, with the increase of
coating layers, the water contents and membrane resistance were gradually increasing,
but both lower than the ACS membrane. A trend was obviously observed that doping
graphene would reduce the membrane resistance. Layer-by-layer methods can
regulate the surface charge density of the membrane and the dense layer, thus
providing a simple and controllable preparation method to achieve the separation of
the ions, organic acids.
Due to the polyelectrolytes both were dissolved into water phase, making the
method as one kind of green environmental technology to modify the membrane
surface. This kind of TFC-AEM with monovalent ion selective separation for
monovalent and organic can be used in environmental protection, chemical industry,
separation and other fields.中
生物工程
No full textCyanobacteria are a kind of prokaryotes which can ultilize solar energy and convert carbon dioxide and water to biomass. With photosynthetic ability, fast growth rates and clear genetic backgrounds, cyanobacteria have been developed as a promising photo-bioreactor which can produce different biofuels and bio-chemicals by metabolic engineering. Glucosylglycerols (GGs) are known as compatible solutes accumulated by some bacteria including cyanobacteria for their adaptations to salt stresses. It was proved that GG can be used as cosmetic additives, protein staberlizers and in human healthcare. Previously, this group has reported their works on photosynthetic production of GG by metabolic engineering of the model cyanobacterium. This work proves the great potential of cyanobacterial photosynthetic production. It also pointed out the drawbacks of this novel route, namely, low environmental tolerances of model Synechocystis sp. PCC 6803, and accumulation of glycerol as byproducts. For exploring the resources of strains and genes which can be used in cyanobacterial GG production, we here performed systematic works and showed some interesting findings as follows:
First, we screened cyanobacterial strains before collected by their salt tolerances, growth rates and abilities to synthesize compatible solutes. And it was found that Gloeocapsa alpicola FACHB-400 and Nostoc spongiaeforme FACHB-130 show the highest and lowest tolerances to salt. 1B1,which was isolated from the salt lake in Yuncheng, Shanxi Province, showed the similar salt tolerance to Synechocystis sp. PCC 6803. Richelia sinica FACHB-800 and 1B1 were found to be best producers for sucrose and GG respectively. In addition, both of them synthesized only sucrose or GG, respectively.
Second, we analysized the morphorical and molecular characteriatics of the 1B1 strain by light microscope,transmission electron microscope and scanning electron microscope analyses and 16 S rRNA-based phylogenetic analysis.1B1 showed the similar mophorical characteriatics to the reported Cyanobacterium aponinum strain. And the 16S rRNA sequences of 1B1 are exactly same as that of Cyanobacterium aponinum PCC 10605. The neighbor-joining phylogenetic trees revealed that the 1B1 strain clustered with Cyanobacterium aponinum PCC 10605. These taxa were sister group to the clade including some other Cyanobacterium strains. The above results lead us to consider the 1B1 strain as a new species of Cyanobacterium and propose for its name as Cyanobacterium aponinum 1B1. For better assembling the genome sequences of the 1B1, we tried four different workflows and evaluated their assemblies. It was found that the k-mer value is the most important factor affecting the short reads assembly. And the draft genome of the 1B1 strain encodes 3659 proteins and 45 RNAs.
To confirm the genes responsible for GG biosynthesis, we obtained the candidate genes encoding glucosylglycerol phosphate synthase and glucosylglycerol phosphate phosphatase, expressed them in the corresponsing mutants of Synechocystis sp. PCC 6803, analyzed the salt tolerances and GG synthesis abilities of the resulting strains. It was found that both the ∆ggpS and ∆ggpP mutants were endowed tolerances to salts and abilities to synthesize GG by introducing the candidate genes of ggpS and ggpP from the 1B1 genome. The results confirmed the functions of the candidate genes from the 1B1 genome.中文；英
High performance chiral separation materials based on chitosan bis(3,5-dimethylphenylcarbamate)-(alkyl urea)s
No full textEnantioseparation plays an important role for many fields and for pharmaceutical industry in particular. Chiral stationary phase (CSP) is the core of chiral liquid chromatography that effectively implements enantioseparation. In order to develop coated type CSPs with excellent enantioseparation capability and high tolerance against mobile phases, in this work, a series of chitosan bis(3,5-dimethylphenylcarbamate)(alkyl urea)s were synthesized, which were coated on 3-aminopropyl silica gel to afford new CSPs. Owing to strong hydrogen bonds formed among the synthesized derivatives, the supra-structure of the derivatives should be highly ordered. Hence, these CSPs could provide excellent separation capability and could tolerate common organic solvents that are usually prohibited for coated type CSPs of cellulose and amylose derivatives. Therefore the newly prepared CSPs exhibited promising prospects for enantioseparation of chiral compounds. (C) 2016 Elsevier Ltd. All rights reserved
New small molecule gel electrolyte with high ionic conductivity for Li-S batteries
No full textA new small molecule gel electrolyte is developed by trapping an organic mixture of 1,3-dioxolane and dimethyl ether with lithium bistrifluoromethanesulfonimide (LiTFSI). The electrochemical properties of the resulting gel electrolyte are investigated. AC impedance spectroscopy reveals that the ionic conductivity of the as-prepared gel electrolyte containing 8.3 wt% small molecules displays a maximum value of 6.43 x 10(-3) S cm(-1) at room temperature. The possible interaction between molecule and LiTFSI was investigated by the NMR spectra and a speculated transmission mechanism was also discussed. The sulfur cathode with the as-prepared small molecule gel electrolyte displays the initial discharge specific capacity of 1008 mAh g(-1) (0.1 C). The Li-S cells assembled with the as-prepared electrolyte membrane display an excellent cycle performance and coulombic efficiency. The electrolyte membrane played an important role in restraining the shuttle effect of polysulfides. These experimental results demonstrate the possibility and potential as new solid electrolyte for Li-S batteries to replace the traditional polymer gel electrolyte
Vacancy-induced MnO6 distortion and its impacts on structural transition of Li2MnO3
No full textAs a new class of high-capacity cathode materials, the Li-rich Mn-based layer-structured xLi(2)MnO(3)center dot(1 x) LiMO2 (M = Ni, Co, Mn, etc.) is a promising candidate for constructing high energy-density Li-ion batteries. Unfortunately, drawbacks such as oxygen evolution, poor rate performance and potential fading during cycling hinder their commercial applications. Migration of the transition metal (Mn) into the Li layer of Li2MnO3 and the resultant irreversible structural transition are believed to be responsible for these issues. Therefore, it is essential to explore the driving force for the Mn migration. In this study, we show, starting from understanding the impact of O and Li vacancies on the migration of the Mn atoms by the first-principles molecular dynamics simulation, that Mn migration is closely involved in the breaking and forming of the Mn-O bonds of the MnO6 octahedron and its continuous distortion (MnOx, 4 <= x <= 6). In addition, Mn migration along with the generation of O vacancy lowers the delithiation potential. Inconsistent with conventional beliefs, Mn migration into the Li layer was found to promote, rather than block, Li diffusion in some cases. The mechanism for MnO6 distortion provides new insight into understanding the micro mechanism of the layered-to-spinel structural transition and revealing the designing of superior cathode materials