Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences
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An in vitro synthetic biosystem based on acetate for production of phloroglucinol
No full textBackground: Phloroglucinol is an important chemical, and the biosynthesis processes which can convert glucose to phloroglucinol have been established. However, due to approximate 80% of the glucose being transformed into undesirable by-products and biomass, this biosynthesis process only shows a low yield with the highest value of about 0.20 g/g. The industrial applications are usually hindered by the low current productivity and yield and also by the high costs. Generally, several different aspects limit the development of phloroglucinol biosynthesis. The yield of phloroglucinol is one of the most important parameters for its bioconversion especially from economic and ecological points of view. The in vitro biosynthesis of bio-based chemicals, is a flexible alternative with potentially high-yield to in vivo biosynthetic technology
Biofilm Attached Cultivation of Chlorella pyrenoidosa Is a Developed System for Swine Wastewater Treatment and Lipid Production
No full textThis study showed the new potential of using soluble contents and heavy metals in swine wastewater as nutrient supplements for the algae Chlorella pyrenoidosa with biofilm attached method. Algae with biofilm attached cultivation grew well in unpasteurized wastewater reaching a biomass productivity of 5.03 g m(-2) d(-1), lipid content of 35.9% and lipid productivity of 1.80 g m(-2) d(-1). Chlorella grew in BG11 medium delivered lower values for each of the aforementioned parameters. The FAMEs compositions in the algae paste were mainly consisted of C16:0, C18:2, and C18:3. Algae removed NH4+-N, total phosphorus (TP), and COD by 75.9, 68.4, and 74.8%, respectively. Notably, Zn-2(+), Cu+, and Fe2+ were removed from wastewater with a ratio of 65.71, 53.64, and 58.89%, respectively. Biofilm attached cultivation of C. pyrenoidosa in swine wastewater containing heavy metals could accumulate considerable biomass and lipid, and the removal ratio of NH4+ -N, TP, COD, and as well as heavy metal were high. Treatment of wastewater with biofilmattached cultivation showed an increasingly popular for the concentration of microalgae and environmental sustainability
Phonon-Assisted Ultrafast Charge Transfer at van der Waals Heterostructure Interface
No full textThe van der Waals (vdW) interfaces of two-dimensional (2D) semiconductor are central to new device concepts and emerging technologies in light-electricity transduction where the efficient charge separation is a key factor. Contrary to general expectation, efficient electron-hole separation can occur in vertically stacked transition-metal dichalcogenide heterostructure bilayers through ultrafast charge transfer between the neighboring layers despite their weak vdW bonding. In this report, we show by ab initio nonadiabatic molecular dynamics calculations, that instead of direct tunneling, the ultrafast interlayer hole transfer is strongly promoted by an adiabatic mechanism through phonon excitation occurring on 20 fs, which is in good agreement with the experiment. The atomic level picture of the phonon-assisted ultrafast mechanism revealed in our study is valuable both for the fundamental understanding of ultrafast charge carrier dynamics at vdW heterointerfaces as well as for the design of novel quasi-2D devices for optoelectronic and photovoltaic applications
A redox responsive controlled release system using mesoporous silica nanoparticles capped with Au nanoparticles
No full textA novel redox responsive controlled release system based on the host-guest interaction between ferrocene modified mesoporous silica nanoparticles (MSN-Fc) and beta-cyclodextrin modified gold nanoparticles (Au@CD) was developed. FITC was used as the release molecule and it was loaded into the pores of MSN-Fc. With the addition of oxidant (H2O2), oxidized ferrocene leaves the hydrophobic cavity of b-CD, resulting in cargo controlled release. Due to the structural properties of the modified MSN, the continuously slow release behavior showed the prospect to be a sustained drug delivery system. This novel redox responsive system possessed stimuli-responsive controlled release and sustained release properties, and therefore has potential applications in sustained and targeted drug delivery
Enteromorpha prolifera-derived carbon as a high-performance cathode material for lithium-sulfur batteries
No full textA novel carbon material for use in lithium-sulfur batteries is fabricated from the seaweed Enteromorpha prolifera, a renewable source that grows rapidly in the sea near Qingdao, China, during the summer. The E. prolifera-derived carbon (EPC) possesses a multilevel micropore-mesopore structure and a certain amount of oxygen- and nitrogen-containing functional groups. In addition, the hierarchical porous carbon also possesses a high specific surface area of 3536.58 m(2) g(-1) and a large pore volume of 1.754 cm(3) g(-1). The carbon can thus be loaded with a high sulfur content (EPC/S, 74.8 wt%), making it a promising candidate for use as the cathode material in lithium-sulfur batteries. The EPC was characterized using field-emission scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, the Brunauer-Emmett-Teller method, and other methods. The EPC/S cathode exhibited superior electrochemical performance; the first discharge capacity was as high as 1328 mA h g(-1) at 0.1 C. Further, the capacity was 520 mA h g(-1) after 100 cycles at 0.5 C and 510 mA h g(-1) after 100 cycles at 1 C
Unraveling the Complex Delithiation and Lithiation Mechanisms of the High Capacity Cathode Material V6O13
No full textV6O13 is a promising Li-ion battery cathode material for use in the high temperature oil field environment. The material exhibits a high capacity, and the voltage profile contains several plateaus associated with a series of complex structural transformations, which are not fully understood. The underlying mechanisms are central to understanding and improving the performance of V6O13-based rechargeable batteries. In this study, we present in situ X-ray diffraction data that highlight an asymmetric six-step discharge and five step charge process, due to a phase that is only formed on discharge. The LixV6O13 unit cell expands sequentially in c, b, and a directions during discharge and reversibly contracts back during charge. The process is associated with change of Li ion positions as well as charge ordering in LixV6O13. Density functional theory calculations give further insight into the electronic structures and preferred Li positions in the different structures formed upon cycling, particularly at high lithium contents, where no prior structural data are available. The results shed light into the high specific capacity of V6O13 and are likely to aid in the development of this material for use as a cathode for secondary lithium batteries
Reduced Graphene Oxide/Alumina, A Good Accelerant for Cellulose-Based Artificial Nacre with Excellent Mechanical, Barrier, and Conductive Properties
No full textIn this article, a simple strategy was employed to fabricate bioinspired hybrid composite with carboxymethyl cellulose (CMC), graphene oxide, and reduced graphene oxide/alumina (rGO/Al) by a facile solution casting method. The tensile strength and toughness of rGO/Al-CMC-GO can reach 586.6 +/- 12 MPa, 12.1 +/- 0.44 MJm(-3), respectively, due to the interface strengthening of alumina, which is 1.43 and 12 times higher than steel and about 4.3 and 6.7 times that of nature nacre. The artificial nacre hybrid composite is conductive due to the introduction of rGO/Al on the surface. Interestingly this structure can also be coated on the surface of cotton thread to give the thread good mechanical performance and conductivity. Additionally, the artificial nacre has better fire shielding and gas barrier properties. The oxygen permeability (OP) for 1% rGO/Al-CMC decreased from 0.0265 to 0.003 mL mu m m(-2) day(-1) kpa(-1), the water vapor permeability (WVP) decreased from 0.363 to 0.205 gmmm(-2) day(-1) kpa(-1) when the concentration increased from 1% rGO/Al to 6% rGO/Al. It is believed this work provided a simple and feasible strategy to fabricate ultrastrong and ultratough graphene-based artificial nacre multifunctional materials
Research Progress on Polycarbonate-based Solid-state Polymer Electrolytes
No full textRechargeable lithium ion batteries become an very important technology in the contemporary society. They are expanding their application in electric vehicles and power grids. However, current lithium ion batteries with liquid electrolyte have been suffering from potential safety crisis mainly due to their highly flammable organic liquid carbonate organic electrolyte and explosion hazards. These potential risks (combustion and explosion) would retard the commercialization of electric vehicles or hybrid electric vehicles. Thus, the safety issue of lithium ion battery merits further study. Solid electrolytes have attracted ever-increasing interest owing to their enhanced safety issue and higher energy density of lithium battery. Solid electrolyte materials mainly include inorganic solid electrolytes (ISEs) and solid polymer electrolytes (SPEs). The ISEs are classified into oxide-based, sulfide-based and etc. However, in spite of the presence of highly ion conductive ISEs, there are still many undergoing issues that limit the practical application at the present stage, like the large interface impedance between electrode and ISEs and the difficulty of processing. More attention has been paid to solid polymer electrolytes due to their superior flexibility and processability, which are also subjected to thermal expansion at elevated temperature. Poly(ethylene oxide) (PEO) solid polymer electrolyte has undergone a sort of renaissance in the past few decades. However, the quintessential frailty of PEO solid polymer electrolyte is low ionic conductivity (in the order of 10(-7) S cm(-1)) at room temperature with a relatively narrow electrochemical window. Hence, it is essential to develop new solid polymer electrolytes with comprehensive performance in terms of high ionic conductivity, wide electrochemical window, superior mechanical strength, excellent thermal stability as well as good interfacial compatibility. In this review, a series of polycarbonate-based solid polymer electrolytes (such as PEC, PPC, PTMC and PVC et al.) are summarized. In addition, we also present a brief review on preparation, electrochemical property, modification, ionic transportation mechanism and future development direction for each of these solid polymer electrolytes
Boron-bridged RG-II and calcium are required to maintain the pectin network of the Arabidopsis seed mucilage ultrastructure
No full textThe structure of a pectin network requires both calcium (Ca2+) and boron (B). Ca2+ is involved in crosslinking pectic polysaccharides and arbitrarily induces the formation of an "egg-box" structure among pectin molecules, while B crosslinks rhamnogalacturonan II (RG-II) side chain A apiosyl residues in primary cell walls to generate a borate-dimeric-rhamnogalacturonan II (dRG-II-B) complex through a boron-bridge bond, leading to the formation of a pectin network. Based on recent studies of dRG-II-B structures, a hypothesis has been proposed suggesting that Ca(2+)is a common component of the dRG-II-B complex. However, no in vivo evidence has addressed whether B affects the stability of Ca2+ crosslinks. Here, we investigated the L-fucose-deficient dwarf mutant mur1, which was previously shown to require exogenous B treatment for phenotypic reversion. Imbibed Arabidopsis thaliana seeds release hydrated polysaccharides to form a halo of seed mucilage covering the seed surface, which consists of a water-soluble outer layer and an adherent inner layer. Our study of mur1 seed mucilage has revealed that the pectin in the outer layer of mucilage was relocated to the inner layer. Nevertheless, the mur1 inner mucilage was more vulnerable to rough shaking or ethylene diamine tetraacetic acid (EDTA) extraction than that of the wild type. Immunolabeling analysis suggested that dRG-II-B was severely decreased in mur1 inner mucilage. Moreover, non-methylesterified homogalacturonan (HG) exhibited obvious reassembly in the mur1 inner layer compared with the wild type, which may imply a possible connection between dRG-II-B deficiency and pectin network transformation in the seed mucilage. As expected, the concentration of B in the mur1 inner mucilage was reduced, whereas the distribution and concentration of Ca(2+)in the inner mucilage increased significantly, which could be the reason why pectin relocates from the outer mucilage to the inner mucilage. Consequently, the disruption of B bridges appears to result in the extreme sensitivity of the mur1 mucilage pectin complex to EDTA extraction, despite the reinforcement of the pectin network by excessive Ca2+. Therefore, we propose a hypothesis that B, in the form of dRG-II-B, works together with Ca(2+)to maintain pectin network crosslinks and ultimately the mucilage ultrastructure in seed mucilage. This work may serve to complement our current understanding of mucilage configuration
Efficient conversion of acetate into phloroglucinol by recombinant Escherichia coli
No full textPhloroglucinol, an important fine chemical, was attempted to be produced by a recombinant Escherichia coli, using acetate, a less costly feedstock, as a alternative carbon source. Phloroglucinol was significantly produced by assembling an acetate assimilation pathway and phloroglucinol biosynthetic pathway in an engineered Escherichia coli strain. Subsequently, the culture conditions were optimized to enhance phloroglucinol production with a maximum titer of 554 mg L-1. Finally, fed-batch fermentation of phloroglucinol was evaluated using the optimized culture conditions, and reached a maximum concentration of 1.20 g L-1. The productivity (0.74 g per g DCW) and yield (0.18 g per g acetate) increased by 3.20-fold and 1.64-fold, respectively, compared with the data using glucose as the carbon source. Therefore, the engineered E. coli cells can be directly emplored for phloroglucinol biosynthesis from acetate with better atom economy and lower cost