Superconductivity induced by La doping in Sr1-xLaxFBiS2 system

Through a combination of X-ray diffraction, electrical transport, magnetic susceptibility, and heat capacity measurements, we report the effect of La doping on Sr in the newly discovered SrFBiS2 system. Superconducting transition with critical temperature Tc of 2.8 K, developed from a semiconducting-like normal state, was found in Sr0.5La0.5FBiS2. A strong diamagnetic signal and a clear specific heat anomaly associated with this transition were observed, confirming bulk superconductivity. The upper critical field Hc2(0) was estimated to be 1 Tesla by using the Ginzburg-Landau approach. Our experiments therefore demonstrate that bulk superconductivity can be achieved by electron doping in the SrFBiS2 system.Comment: 4 pages,5 figure

Engineering a highly active thermophilic β-glucosidase to enhance its pH stability and saccharification performance

BACKGROUND: β-Glucosidase is an important member of the biomass-degrading enzyme system, and plays vital roles in enzymatic saccharification for biofuels production. Candidates with high activity and great stability over high temperature and varied pHs are always preferred in industrial practice. To achieve cost-effective biomass conversion, exploring natural enzymes, developing high level expression systems and engineering superior mutants are effective approaches commonly used. RESULTS: A newly identified β-glucosidase of GH3, Bgl3A, from Talaromyces leycettanus JCM12802, was overexpressed in yeast strain Pichia pastoris GS115, yielding a crude enzyme activity of 6000 U/ml in a 3 L fermentation tank. The purified enzyme exhibited outstanding enzymatic properties, including favorable temperature and pH optima (75 °C and pH 4.5), good thermostability (maintaining stable at 60 °C), and high catalytic performance (with a specific activity and catalytic efficiency of 905 U/mg and 9096/s/mM on pNPG, respectively). However, the narrow stability of Bgl3A at pH 4.0–5.0 would limit its industrial applications. Further site-directed mutagenesis indicated the role of excessive O-glycosylation in pH liability. By removing the potential O-glycosylation sites, two mutants showed improved pH stability over a broader pH range (3.0–10.0). Besides, with better stability under pH 5.0 and 50 °C compared with wild type Bgl3A, saccharification efficiency of mutant M1 was improved substantially cooperating with cellulase Celluclast 1.5L. And mutant M1 reached approximately equivalent saccharification performance to commercial β-glucosidase Novozyme 188 with identical β-glucosidase activity, suggesting its great prospect in biofuels production. CONCLUSIONS: In this study, we overexpressed a novel β-glucosidase Bgl3A with high specific activity and high catalytic efficiency in P. pastoris. We further proved the negative effect of excessive O-glycosylation on the pH stability of Bgl3A, and enhanced the pH stability by reducing the O-glycosylation. And the enhanced mutants showed much better application prospect with substantially improved saccharification efficiency on cellulosic materials. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13068-016-0560-8) contains supplementary material, which is available to authorized users

Chinese Investment in Central and Eastern European Countries – A Study of Motivations

China has started to engage in the overseas investment to obtain maximized profit and improve the competitiveness from 1990s since the government supportted and encouraged enterprises to ‘go out’. Moreover, the financial crisis and EU sovereign debt crisis as a windows opportunity attract more and more Chinese investment. Therefore, it becomes a hot debate in accordance with the motivations in which factors drive the Chinese investment in central and eastern Europe. The different opinions between western and eastern Europeans are mainly collected and analysed. The paper is going to answer the question that the motivations of Chinese investment in CEE countries from both the perspective of China and CEE countries to test the political and economic implications

Game Study on Collusion in the First-price Sealed-bid Reverse Auction

Collusion between suppliers in reverse auctions may damage buyers’ benifits and then lower efficiency of resource allocation. Under first-price sealed-bid reverse auction mechanism, suppliers\u27 equilibrium bidding strategy and buyers\u27 revenue loss was analyzed considering collusion. Then some general conclusions were given: suppliers\u27 bidding strategy is relevant to some factors such as valuation costs, the number of suppliers and Cartel; the number of suppliers and Carter can lead to buyers revenue loss. Finally, considering two different kinds of distribution function, the strategies of improving buyer’s revenue were discussed