Boosting lithium-ion storage performance by ultrafine bimetal carbides nanoparticles coupled with Hollow-like carbon composites.

Metallic carbides demonstrated tremendous application potential in energy conversion field deriving from their distinctive electrochemical activity and chemical stability. Herein, a molybdenum-based hybrid self-template strategy was adopted to confine ultrafine molybdenum carbides and tungsten carbides nanoparticles in N, P-codoped carbon nanotubes (MoC/WC@N, P-CNTs) for enhanced lithium-ion storage. Specifically, hierarchical MoW-polydopamine nanotubes were prepared via a self-template strategy, which employed Mo3O10(C6H8N)2·2H2O nanowires as the template. Ultrafine MoC and WC nanoparticles embedded in ultrathin carbon nanosheets could be obtained rationally after carbonization treatment, which could not only prevent carbides nanoparticles from agglomeration and oxidation, but also endow the rapid electron transfer rate. Thus, MoC/WC@N, P-CNTs displayed outstanding lithium storage abilities with great rate property and long-term cycling durability. The stable specific capacity of 475.0 mAh g-1 could be preserved at high current intensity of 5.0 A g-1 after 1000 cycles, which was one of the best performances for metal carbides anodes. Furthermore, the successful fabrication of lithium-ion hybrid capacitors (LIHCs) delivered the maximum energy density of 117 Wh kg-1 and power density of 6571 W kg-1. Moreover, the superior capacity retention of 89.7 % after 2000 cycles also indicated the excellent cycling stability. The present work highlights a self-template strategy for designing nanostructures toward efficient energy storage and conversion fields.

Large-scale production of ursodeoxycholic acid from chenodeoxycholic acid by engineering 7α- and 7ß-hydroxysteroid dehydrogenase.

7α- and 7ß-hydroxysteroid dehydrogenases (HSDHs) are key biocatalysts for the biotransformation of ursodeoxycholic acid (UDCA) from chenodeoxycholic acid (CDCA). Various researches focused on heterogeneously expressed engineering enzymes to epimerize CDCA for UDCA, however not yet applied to further industrial application. In this work, we present the large-scale production of UDCA from CDCA by 7α- and 7ß-HSDH enzymatic synthesis. Engineering enzymes were both successfully heterologous overexpressed in Escherichia coli BL21, and the effect of the enzymatic synthesis was investigated. The mass analysis (MS), IR spectrum, 1H NMR and 13C NMR were used to characterize the product. 500-L fermentor fermentation strategy producing a stable supply of HSDH and large-scale production process of UDCA in dozens kilogram class enabled industrial application.

Quantitative effects of amination degree on the magnetic iron oxide nanoparticles (MIONPs) using as adsorbents to remove aqueous heavy metal ions.

The hierarchical effect of amine-functionalization on nanoparticle properties, magnetism especially, and adsorption of Cu2+, Ni2+, Pb2+ and Zn2+ by aminated MIONPs were investigated elaboratively. The results reflected that the dispersibility and stability of nanoparticles in aqueous solution were both enhanced as MIONPs grafted with amine groups, while saturation magnetism and magnetic recovery conveniences had a negatively correlative relation with the amination degree. In addition, the adsorption performances of Cu2+, Ni2+, Pb2+ and Zn2+ by different aminated MIONPs were also studied comprehensively. The results showed that the initial adsorption rates and adsorption capacities of heavy metal ions increased with the amination degree. In addition, the quantitative correlation between amination degree and adsorption capacities of different heavy metal ions could be described well by a model built on basis of adsorption processes.

Fabrication of novel biodegradable porous bone scaffolds based on amphiphilic hydroxyapatite nanorods.

This paper describes a new synthetic strategy and biological application for novel amphiphilic hydroxyapatite (HAp) nanorods. The prepared HAp nanorods were able to be dispersed in water, ethyl alcohol and cyclohexane. The co-anchoring of the multidentate ligands of PEG 20000 and hydrophobic oleic acid (OA) on the rods' surfaces endowed them with excellent amphibious properties. Utilizing amphiphilic HAp nanorods with excellent biocompatibility as the inorganic phase, human-like collagen (HLC) as the organic phase and natural genipin as the cross-linker, optimal HLC/HAp porous scaffolds (HLC: HAp=1:4, w/w) were fabricated. The compression stress and three-point bending strength of the scaffolds with pore diameters of 150 to 200µm reached approximately 3.4MPa and 5.4MPa, respectively, and their porosity was 77.35±3.75%. Cytological tests showed that HLC/HAp scaffolds could contribute to cell proliferation and differentiation. The results indicated that these novel amphiphilic HAp nanorods can be expected to become recognized as an excellent inorganic material for the porous scaffolds used in repairing bone and related applications.

Monodisperse selenium-substituted hydroxyapatite: Controllable synthesis and biocompatibility.

Hydroxyapatite (HA) is the major inorganic component of natural bone tissue. As an essential trace element, selenium involves in antioxidation and anticancer of human body. So far, ion-doped hydroxyapatites (HAs) are widely investigated owing to their great applications in field of biomaterial, biological labeling. In this paper, series of monodisperse HA doped with SeO32- (SeHA) was successfully synthesized based on the liquid-solid-solution (LSS) strategy. The obtained samples were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and energy-dispersive spectrometer (EDS). The results indicated that the SeO32- doping level of the Se/(P+Se) molar ratio of 0-0.4 can be requisitely controlled, and the morphology of SeHA nanoparticles varied from nanorods to nanoneedles with increasing Se/(P+Se) molar ratio. Significantly, the as-synthesized SeHA nanocrystals exhibit a low cytotoxicity for osteoblastic cells, showing exciting potentials for application in artificial scaffold materials inhibiting of tumor growth in bone.

Comparison of bacterial community characteristics between complete and shortcut denitrification systems for quinoline degradation.

For quinoline-denitrifying degradation, very few researches focused on shortcut denitrification process and its bacterial community characteristics. In this study, complete and shortcut denitrification systems were constructed simultaneously for quinoline degradation. By calculation, specific quinoline removal rates were 0.905 and 1.123 g/(gVSS d), respectively, in the complete and shortcut systems, and the latter was 1.24 times of the former. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), high-throughput sequencing, and quantitative PCR (qPCR) techniques based on 16S rRNA were jointly applied to compare microbial community structures of two systems. Many denitrifying bacteria phyla, classes, and genera were detected in the two systems. Phylum Proteobacteria, Class Gammaproteobacteria, and Genus Alicycliphilus denitrificans were the dominant contributors for quinoline-denitrifying degradation. In the shortcut denitrification system, main and specific strains playing crucial roles were more; the species richness and the total abundance of functional genes (narG, nirS, nirK, and nosZ) were higher compared with the complete denitrification system. It could be supposed that inorganic-nitrogen reductase activity of bacterial community was stronger in the shortcut denitrification system, which was the intrinsic reason to result in higher denitrification rate.

Enhanced Promiscuity of Lipase-Inorganic Nanocrystal Composites in the Epoxidation of Fatty Acids in Organic Media.

In the present study, Candida antarctica lipase B (CALB) was encapsulated in inorganic nanocrystal composites with flower-like shapes, retaining 92% of its catalytic activity compared to that of native lipase. Surprisingly, CALB-inorganic crystal nanoflowers exhibited promiscuous activity at levels 25- and 4-fold higher than those of native lipase and the commercial immobilized lipase Novozym 435, respectively, as demonstrated by the chemoenzymatic epoxidation of fatty acids conducted in organic media. To the best of our knowledge, we showed for the first time that the promiscuity of enzymes can be significantly improved by enzyme immobilization, suggesting that the enzyme-inorganic nanocrystal composites are a very promising type of immobilized enzyme that can be used to address the challenge of the extremely low efficiency of enzymatic promiscuity.

Dewaterability of sludge conditioned with surfactant DDBAC pretreatment by acid/alkali.

The potential benefits of surfactant-conditioned sludge dewatering treatment with acid/alkali pretreatment were investigated in this study. The water content of dewatered sludge (W C) and specific resistance of filtration (SRF) were used to evaluate sludge dewaterability. Extracellular polymeric substance (EPS) content, bound water content, zeta potential, and rheological properties were measured to explain the change of dewaterability observed in the conditioning process. By introducing dodecyl dimethyl benzyl ammonium chloride (DDBAC), the EPS content of the sludge supernatant changed, and bound water content, charge strength, and apparent viscosity decreased simultaneously. Although DDBAC-conditioned sludge in strong alkaline had low bound water content, W C and SRF increased rapidly because of the dramatically increasing of EPS in sludge supernatant. Remarkable decrement was observed in bound water content and W C in DDBAC-conditioned sludge which was in weak acid environment for comparison. The results indicated that 75 mg/g of DDBAC at pH 4.84 was the optimum under which W C and SRF were at their lowest point in sludge, 58.22 % and 0.521 × 10(13) m/kg, respectively.

Impacts of sludge retention time on sludge characteristics and membrane fouling in a submerged anaerobic-oxic membrane bioreactor.

Anaerobic-oxic membrane bioreactor (AOMBR) has been proposed as a highly effective method in municipal and industrial wastewater treatment. In this study, according to the sewage treatment system in a campus, long-term experiments were conducted to assess the impacts of the sludge retention time (SRT) on sludge characteristics and membrane fouling, and the sludge parameters include biomass concentration, particle size distribution, extracellular polymeric substances (EPS), soluble microbial products (SMPs), and specific resistance to filtration (SRF). Our results clearly demonstrated that SRT was one of the most important factors influencing sludge characteristics, and different sludge characteristics resulted in different membrane fouling degrees. A better treatment and filtration performances were observed at the SRT of 30 days compared to two SRTs of 10 and 90 days. Among these parameters, SMP had the most significant correlation with the membrane fouling rate (dTMP/dt), and it had a negative impact on membrane filtration performance. The impact of SRT on membrane fouling process was discussed further by filtration models. At 10 days SRT, the complete-standard blocking model curve had a comparatively higher goodness-of-fit with the fouling process, and at 30 and 90 days SRT, the cake-standard blocking model curve had a relatively higher goodness-of-fit with respective fouling process.

Degradation of hexadecane by Enterobacter cloacae strain TU that secretes an exopolysaccharide as a bioemulsifier.

A Gram-negative rod-shaped bacterium, previously shown to utilize alkanes and polycyclic aromatic hydrocarbons (PAHs), was identified as Enterobacter cloacae (GenBank accession number, GQ426323) by 16S rRNA sequence analysis and was designated as strain TU. During growing on n-hexadecane as the sole carbon source, the strain TU extracellularly released an exopolysaccharide (EPS) exhibiting bioemulsifying activity into the surrounding medium. The EPS was found to be composed of glucose and galactose with molecular weight of 12.4+/-0.4 kDa. The structure of the EPS was postulated according to by 1D/2D NMR, as follows: -D-Glcp-(1 --> 3)-alpha-d-GlcpAc-(1 --> 3)-alpha-D-Galp-(1 --> 4)-alpha-D-Galp-(1 -->. While an enhanced emulsification and aqueous partitioning of n-hexadecane was displayed as functions of the EPS concentration, the EPS neutralized the zeta potential of E. cloacae TU cell and elevated the surface hydrophobicity of the cells, as determined by the microorganisms adhering to hydrocarbon assay (MATH). This was found to favor the bioavailability of n-hexadecane when it served as the sole carbon source for E. cloacae TU and thereby contributed to the accelerated degradation of this hydrocarbon.

[Process fundamentals and field demonstration of wheat straw enhanced salt leaching of petroleum contaminated farmland].

A new remediation method for petroleum-salt contaminated soil was proposed, in which wheat straw was applied to enhance salt leaching and meanwhile block salt upmovement along the soil capillary. It was shown that the existence of petroleum increased the surface hydrophobicity of soil and thus hindered the leaching process once the oil content was above 1.5% (mass fraction). The application of 5% (mass fraction) wheat straw into the soil increased the efficiency of salt leaching from 3% to 25%. The effectiveness of wheat straw layer in inhibiting the salt upmovement along the soil capillary was also proven. Field test of this method was carried out in an area of 6400 m2, in which wheat straw layer of 5 cm was distributed in the depth of 25 cm. After 50 days, 80% of the testing area showed a normal soil electronic conductivity (soil EC <5 mS x cm(-1)) in contrast to 17% before leaching process. The concentrations of Na+ and Cl- were decreased from 1642.5 mg x kg(-1) and 1 301.2 mg x kg(-1) to 499.3 mg x kg(-1) and 433.8 mg x kg(-1), respectively. The remediated land upon the implementation of wheat straw gave a 72% of the regular wheat production obtained from the normal farmland, while the control land without wheat straw gave 12%. These results demonstrated the effectiveness and the high potential of using wheat straw for the salt leaching in remediation of petroleum-salt contaminated soil.

[Process fundamentals and field demonstration of wheat straw enhanced biodegradation of petroleum].

A new bioaugmentation method utilizing wheat straw to enhance salt leaching and the subsequent petroleum biodegradation by consortia of bacteria and fungi was proposed. The present study aimed at the effects of wheat straw on the growth and the degradation behavior of E. cloacae and Cun. echinulata, the two species of the consortia. In the laboratory experiments, it was shown that the addition of 5% (mass fraction) straw led to an increase of biomass by 25- and 3-fold to the bacteria and fungi, respectively. The biodegradation ratio of total petroleum hydrocarbon (TPH) was elevated from 29.2% to 48.0% after 468 h treatment. The biodegradation ratio of alkane and aromatic hydrocarbons in petroleum were increased from 31.5% and 39.1%, to 55.7% and 55.9%, respectively. The field demonstration was carried in an area of 6400 m2, in which the bacteria and fungi were inoculated after salt leaching in the presence of wheat straw. The addition of wheat straw in the contaminated soil led to an increase by 158- and 9-fold to the bacteria and fungi, as compared to their counterpart in the controlland without wheat straw, at 25 days after the inoculation. The content of TPH was down to below 0.3% while the maximum biodegradation ratio of TPH reached 75% after 45 days treatment. These results demonstrated the effectiveness and high potential of the wheat straw enhanced bioaugmentation of petroleum-salt contaminated soil.

Enhanced bioaugmentation of petroleum- and salt-contaminated soil using wheat straw.

A new bioaugmentation method for petroleum- and salt-contaminated soil was presented, in which wheat straw was used to enhance salt leaching and subsequent petroleum degradation by a bacteria-fungi consortium of Enterobacter cloacae and Cunninghamella echinulata. The effectiveness of a coarse wheat straw layer in inhibiting capillary-induced upward salt movement and in enhancing growth of E. cloacae and C. echinulata was shown in the laboratory and a 7000-m(2) field study in Henan Province, China. In the field study, the Na(+) concentration in remediated soil at 1-25 cm depth decreased from 1597 ± 394 to 543 ± 217 mg kg(-1), while Cl(-) decreased from 1520 ± 922 to 421 ± 253 mg kg(-1). The wheat straw increased bacterial biomass by 170-fold and fungi 11-fold compared to control soil without wheat straw. The concentration of total petroleum hydrocarbons decreased from 6320 ± 1180 to 2260 ± 420 mg kg(-1) after 45 d of treatment. Wheat was cultivated on remediated soil and grain yield reached 72% of that obtained in normal farmland adjacent to the study site. The results demonstrated the effectiveness of wheat straw in enhancing bioaugmentation of the petroleum- and salt-contaminated soil and indicated a high application potential.