矿区土壤与地下水中铁锰菌群分布规律及成因解析

针对大量煤矿区地下水环境和土壤中铁锰富集的现象,采用16S rDNA联合DGGE分子生物学方法测定某矿区煤层-潜层地下水-土壤层微生物的垂向分布规律和生活区-矿区边界-核心采矿区中微生物的横向分布规律,与铁锰离子浓度分布进行对比分析,研究铁锰细菌不同种属在空间上的变化规律,揭示区域地下水环境和土壤环境质量铁锰超标的水文地质原因与变化规律。最后通过两个月的铁锰溶液室内驯化实验,全面分析矿区铁锰细菌的生物多样性与种属分类特征。结果显示,矿区地下水中铁锰细菌有硫细菌(Chloroflexi bacterium)、芽孢杆菌(Psychrodurans)、假单胞菌(Pseudomonas),微生物优势条带检出结果表明煤层品位越高的区域铁锰细菌所占比例越高,同时说明铁锰微生物的分布与铁锰元素的分布正向相关。煤层中铁锰细菌优势明显,占到84%左右。矿区土壤中铁锰细菌亦为优势种群,但占比远低于煤层中。非煤区土壤中铁锰细菌则优势不明显,仅占土壤优势菌群的20%。且在核心采区煤层水中发现了兼性菌——绿弯菌门(Chloroflexus),说明长期疏干煤层地下水改变了煤层微生物种群,使得微生物的多样性发生变化。室内驯化实验,得到4种均为芽孢杆菌菌属(Bacillus)的铁锰优势菌,对铁锰离子浓度耐受性较强并且能够进行生物富集,具有成为土壤修复工程菌的潜质。本研究可为矿区土壤与地下水铁锰污染治理提供一定的理论指导。

Study of the Combustion Process inside an Ethanol-Diesel Dual Direct Injection Engine Based on a Non-Uniform Injection Approach

The use of ethanol is a promising method to reduce the emissions of diesel engines.The present study has been based on the installation of a gasoline electronic injection system in a single-cylinder diesel engine to control the amount of ethanol entering the cylinder during the compression(while diesel has been injected into the cylinder by the original pump injection system).The injection time has been controlled by crank angle signal collected by an AVL angle indicator.In the tests ethanol and diesel each accounted for half of the fuel volume,and the total heat energy supply of the fuel was equivalent to that of the diesel under the operating conditions of the original engine.A three-dimensional combustion model of the diesel engine has been implemented by using the CFD software FIRE.Simulations have been carried out assuming uniform and non-uniform injections rate for the different holes and the different results have been compared.According to these results,a non-uniform injection rate can produce early ignition and cause an increase in the maximum in-cylinder pressure and the maximum average incylinder temperature.Moreover,in such conditions NO emissions are larger while soot emission is slightly lower.

Construction of Lactuca sativa Plastid Transformation Vector and High-level Expression of gfp Gene in Escherichia coli

Using genomic DNA of bolting-tolerant lettuce as a template,flanking fragments of lettuce plastid rpo A gene were amplified and cloned by PCR. Targeting the sites of these two fragments,homologous recombinant fragments of exogenous gene were integrated to construct lettuce plastid expression vector p Brpo AGFP,which harbored the expression cassette Prrn-gfp-aad A-Tpsb A. The results showed that the amplified flanking fragments were 1.2 and 1.1 kb in size. After sequencing,restriction digestion,ligation and transformation,lettuce plastid expression vector containing expression cassette Prrn-gfp-aad A-Tpsb A was constructed and confirmed by SDS-PAGE electrophoresis. The results of SDS-PAGE electrophoresis indicated that gfp gene was efficiently expressed under the regulation of plasmid specific promoter Prrn and terminator Tpsb A. GFP accounted for 45. 6% of total soluble proteins; inclusion bodies accounted for 47.5 % of bacterial proteins,which reached relatively high expression levels. The construction of lettuce plastid expression vector p Brpo A-GFP laid a solid foundation for establishment of subsequent lettuce plastid transformation system and genetic improvement of lettuce using various functional genes.

Cloning and Sequence Analysis of Polygalacturonase(PG) Promoter in Tomato

In this study, 1 500 bp PG gene promoter was amplified from leaves of tomato cultivar ＇ Zhongshu No. 4＇. The bioinformatic analysis of PG promoter sequences was conducted. PG promoter elements were predicted and analyzed by PLANTCARE and PLACE. The results showed that tomato PG promoter contained multiple c/s-acting regulatory elements such as typical basic elements TATA-Box and CAAT-Box, light responsive elements 3-AF1 binding site, ATl-motif, ATCT- motif, Box 4, Box I, GA-motif, GTl-motif, Spl and MRE, heat stress-responsive element HSE, ethylene-responsive element ERE, meristem-specifie regulatory element CCGTCC-box, endosperm expression-related regulatory elements GCN4_motif and Skn-l_motif, defense and stress responsiveness element TC-rich repeats, and circadian control-related element circadian, indicating that the expression of tomato PG gene is related to light, temperature, hormone, stress and other factors. This study laid the foundation for subsequent research about regulation of PG gene expression in plants.

响应面法优化黄檗中主要活性成分的超临界CO2萃取工艺研究

为研究黄檗中小檗碱的超临界CO2流体萃取工艺条件,以小檗碱提取量为指标,通过单因素及响应面实验设计分析,探讨萃取压力、萃取温度、萃取时间和夹带剂乙醇体积分数对小檗碱提取量的影响。同时应用响应面交互作用和建立回归方程,分析优化得出该方法的最佳提取条件是:提取压力为31.00 Mpa,提取温度为52.00℃,提取时间为90.00 min,乙醇体积分数为94.00%。在此条件下黄檗中小檗碱提取量为0.987 mg/g。

Interfacial microstructure evolution and bonding mechanisms of 14YWT alloys produced by hot compression bonding

Hot compression bonding was first used to join oxide-dispersion-strengthened ferrite steels(14 YWT)under temperatures of 750–1100℃ with a true strain range of 0.11–0.51. Subsequently, the microstructure evolution and mechanical properties of the joints were characterized, revealing that the 14 YWT steels could be successfully bonded at a temperature of at least 950℃ with a true strain of 0.22, without degrading the fine grain and nanoparticle distribution, and the presence of inclusions or micro-voids along the bonding interface. Moreover, the joints had nearly the same tensile properties at room temperature and exhibited a similar fracture morphology with sufficient dimples compared to that of the base material. An electron backscattered diffraction technique and transmission electron microscopy were systematically employed to study the evolution of hot deformed microstructures. The results showed that continuous dynamic recrystallization characterized by progressive subgrain rotation occurred in this alloy, but discontinuous dynamic recrystallization characterized by strain-induced grain boundary bulging and subsequent bridging sub-boundary rotation was the dominant nucleation mechanism. The nuclei will grow with ongoing deformation, which will contribute to the healing of the original bonding interface.

Dynamic recrystallization behavior and interfacial bonding mechanism of 14Cr ferrite steel during hot deformation bonding

In this study, hot compression bonding was first applied to join 14Cr ferrite steel at temperatures of 950–1200°C and strains of 0.11–0.51 under strain rates of 0.01–30 s^(-1).Subsequently, tensile tests were performed on the joints to evaluate the reliability of the joints formed.Detailed microstructural analyses suggest that two different competing dynamic recrystallization(DRX) mechanisms occur during the bonding process depending on the strain rate, and the joints obtained at different strain rate exhibits distinct healing effect.At a low strain rate(0.01 s^(-1)), continuous DRX occurs, as expected in high-stackingfault-energy materials, and is characterized by the progressive conversion of the sub-boundaries into larger-angle boundaries, which involves very limited grain boundaries migration.In addition, straininduced precipitation(SIP) is sufficient under this condition, further impeding the healing of bonding interface.Hence, the joints obtained at low strain rate fractured at the bonding interface easily.Whereas discontinuous DRX is activated at high strain rates(10 and 30 s^(-1)).Under this condition, the formation of sub-boundaries is severely suppressed, resulting in the piling-up of dislocations and hence the storage of a greater amount of stored energy for nucleation and subsequent nuclei growth via the long-distance grain boundaries migration.Meanwhile, the SIP process is sluggish, making the conditions much more favorable for grain boundaries migration which plays a key role in the healing of the original bonding interface.Thus, the joints can be successfully bonded when a high strain rate is applied, with the joints exhibiting tensile properties similar to that of the base material.

WTAP regulates postnatal development of brown adipose tissue by stabilizing METTL3 in mice

Brown adipocyte maturation during postnatal development is essential for brown adipose tissue(BAT)to protect animals against cold.Impaired maturation of brown adipocytes leads to cold intolerance.However,the molecular mechanisms that determine the maturation of brown adipocytes during postnatal development are not fully understood.Here,we identify Wilms’tumor 1-associating protein(WTAP)as an essential regulator in the postnatal development and maturation of BAT.BAT-specific knockout of Wtap(Wtap-BKO)severely impairs maturation of BAT in vivo by decreasing the expression of BAT-selective genes,leading to the whitening of interscapular BAT(iBAT).Single nucleus RNA-sequencing analysis shows the dynamic changes of cell heterogeneity in iBAT of Wtap-BKO mice.Adult mice with WTAP deficiency in BAT display hypothermic and succumb to acute cold challenge.Mechanistically,WTAP deficiency decreases m6A mRNA modification by reducing the protein stability of METTL3.BAT-specific overexpression of Mettl3 partially rescues the phenotypes observed in Wtap-BKO mice.These data demonstrate that WTAP/METTL3 plays an essential role in iBAT postnatal development and thermogenesis.

Research on the evolutionary dynamics of interdisciplinary collaboration from the perspective of co-authorship

Despite the growing interest in exploring the interdisciplinary collaboration patterns and the factors in relation to team assembly in the first place, the dynamics of interdisciplinary collaboration with time varying is hardly known. Based on the longitudinally co-authorship network perspective, the paper investigates the evolutionary dynamics of interdisciplinary collaboration using separable temporal exponential-family random graph model(STERGM). The results from STERGM show that structural properties, properties of researcher and link properties affect the evolution of interdisciplinary co-authorship network to varying degrees. Network transitivity and preferential attachment play a decisive role in formation of links and hamper dissolution of ties in the network. The number of collaborators of interdisciplinary researchers plays an active role in the formation of partnerships and hamper dissolution of partnerships in the initial stage;specialization of team members inhibits the establishment of collaborative relationship in the initial stage and promotes the dissolution of connections in the later stage of project;the large difference in specialization value between members is not conducive to the formation of relations in the initial stage, but conducive to the maintenance of collaborative relations after links establishment. The same discipline background is conducive to the formation of relations but not conducive to the maintenance of collaborative relationships in interdisciplinary co-author network.