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In this paper, an interference alignment (IA) algorithm is proposed for TD(time division) cognitive cellular networks with multiple primary users and secondary users. Considering the situations that a macrocell and two small cells coexist over the same spectrum and communicating using the same frequency at the same time, there are two primary users in the macrocell, and two secondary users in each small cell. The secondary users are divided into two types according to the application scene, and the primary receiver also participates in the IA algorithm by performing interference suppression. The IA algorithm is projected with Max-SINR( signal to interference and noise ratio) algorithm and solved by the iterative method. According to the simulation results, in the case of small capacity sacrifice of the primary users, the capacity of secondary users is improved, and the total capacity of the system is also improved. [ABSTRACT FROM AUTHOR]

To explore the influence of bionic texture coronary stents on hemodynamics, a type of bioabsorbable polylactic acid coronary stents was designed, for which a finite element analysis method was used to carry out simulation analysis on blood flow field after the implantation of bionic texture stents with three different shapes (rectangle, triangle and trapezoid), thus revealing the influence of groove shape and size on hemodynamics, and identifying the optimal solution of bionic texture groove. The results showed that the influence of bionic texture grooves of different shapes and sizes on the lower wall shear stress region had a certain regularity. Specifically, the improvement effect of grooves above 0.06 mm on blood flow characteristics was poor, and the effect of grooves below 0.06 mm was good. Furthermore, the smaller the size is, the better the improvement effect is, and the 0.02 mm triangular groove had the best improvement effect. Based on the results of this study, it is expected that bionic texture stents have provided a new method for reducing in-stent restenosis.

CRISPR/Cas9 has been widely used in engineering Saccharomyces cerevisiae for gene insertion, replacement and deletion due to its simplicity and high efficiency. The selectable markers of CRISPR/Cas9 systems are particularly useful for genome editing and Cas9-plasmids removing in yeast. In our previous research, GAL80 gene has been deleted by the plasmid pML104-mediated CRISPR/Cas9 system in an engineered yeast, in order to eliminate the requirement of galactose supplementation for induction. The maximum artemisinic acid production by engineered S. cerevisiae 1211-2 (740 mg/L) was comparable to that of the parental strain 1211 without galactose induction. Unfortunately, S. cerevisiae 1211-2 was inefficient in the utilization of the carbon source ethanol in the subsequent 50 L pilot fermentation experiment. The artemisinic acid yield in the engineered S. cerevisiae 1211-2 was only 20%-25% compared with that of S. cerevisiae 1211. The mutation of the selection marker URA3 was supposed to affect the growth and artemisinic acid production. A ura3 mutant was successfully restored by a recombinant plasmid pML104-KanMx4-u along with a 90 bp donor DNA, resulting in S. cerevisiae 1211-3. This mutant could grow normally in a fed-batch fermentor with mixed glucose and ethanol feeding, and the final artemisinic acid yield (> 20 g/L) was comparable to that of the parental strain S. cerevisiae 1211. In this study, an engineered yeast strain producing artemisinic acid without galactose induction was obtained. More importantly, it was the first report showing that the auxotrophic marker URA3 significantly affected artemisinic acid production in a pilot-scale fermentation with ethanol feeding, which provides a reference for the production of other natural products in yeast chassis.

Methanogens are unique microorganisms for methane production and the main contributor of the biogenic methane in atmosphere. Methyl-coenzyme M reductase (Mcr) catalyzes the last step of methane production in methanogenesis and the first step of methane activation in anaerobic oxidation of methane. The genes encoding this enzyme are highly conserved and are widely used as a marker in the identification and phylogenetic study of archaea. There has been a longstanding interest in its unique cofactor F430 and the underpinning mechanisms of enzymatic cleavage of alkane C-H bond. The recent breakthroughs of high-resolution protein and catalytic-transition-state structures further advanced the structure-function study of Mcr. In particular, the recent discovery of methyl-coenzyme M reductase-like (Mcr-like) enzymes that activates the anaerobic degradation of non-methane alkanes has attracted much interest in the molecular mechanisms of C-H activation without oxygen. This review summarized the advances on function-structure-mechanism study of Mcr/Mcr-like enzymes. Additionally, future directions in anaerobic oxidation of alkanes and greenhouse-gas control using Mcr/Mcr-like enzymes were proposed.

Objective: To study the effects of genes ste7-ste15 double disruption in biosynthesis of Ebosin., Methods: The ste7 gene was disrupted with a double crossover via homologous recombination in the mutant strain Streptomyces sp. The 139 (ste15-) and the mutant strain Streptomyces sp.139 (ste7- ste15-) were identified by Southern blot. Gene complementation of the knock-out mutant was done. Monosaccharide composition of the exopolysaccharides EPS15-7m, EPS15-7c producing by Streptomyces sp.139 (ste7- ste15-) and Streptomyces sp. 139 (pKC7-15c) separately were analyzed by Gas Chromatography,while their Mw and the antagonist activity for IL-1R were determined comparing with Ebosin., Results: The mutant strain Streptomyces sp.139 (ste7- ste15-) and complementary strain Streptomyces sp. 139 (pKC7-15c) were constructed respectively. The analysis results showed that both of fucose and glucose decreased remarkably in EPS15-7m and its Mw and the antagonist activity for IL-1R were much lower than Ebosin. The composition of fucose and glucose were recovered notablely in EPS15-7c compared with EPS15-7m., Conclusion: The genes ste7 and ste15 played essential roles in the synthesis process of sugar repeating unit during biosynthesis of Ebosin. The activities of Ebosin new derivative produced by the mutant will be studied further.