我国农村养老金融发展态势、挑战与对策

从金融角度看,农村养老的关键在于农村金融生态状况和金融对农村生态环境的支持力度。农村振兴战略对农村养老金融的发展提出了内在要求。在农村地区,养老融资及其包容性发展存在瓶颈和困难。实现农村养老已成为农村振兴中亟待解决的现实问题,而这离不开金融的有力支持。文章提出要通过多种措施,进一步促进农村养老服务金融发展,全力支持农村养老事业。

Comparative analysis on microbial community associated with different gastrointestinal regions of wild northern snakehead Channa argus Cantor, 1842

Microbial communities in different gastrointestinal regions （stomach, foregut, midgut, and hindgut） of the northern snakehead Channa argus （Cantor, 1842） were compared by polymerase chain reaction and partial 16S rDNA sequencing. A total of 194, 140, 212, and 122 OTUs were detected in the stomach, foregut, midgut, and hindgut, respectively. Significant differences were found in the Sobs, ACE, Shannon, and Simpson indices among samples （P〈0.05）. The gastrointestinal microbial community of C. argus consisted predominantly of Proteobacteria with either Halomonas, Shewanella, Plesiomonas, or Sphingomonas. Fusobacteria, Firm!cutes, and Bacteroidetes also existed in the gastrointestinal tracts. However, significant＇differences were found in the compositions of microbial community among the four regions （P〈0.05）. Cyanobacteria and Spirochetes were significantly higher in the midgut and hindgut （P〈0.05）. Fusobacteria and Firmicutes were dominant in the hindgut and foregut, respectively （P〈0.05）. Proteobacteria was the lowest in the hindgut （P〈0.05）. At genus level, Cetobacterium and Plesiomonas were significantly higher in the hindgut than in the other three samples （P〈0.05）. Clostridium and Prevotella were the highest in the midgut （P〈0.05）. Halomonas, Shewanella, and Sphingomonas were the highest in the foregut （P〈0.05）. Paracoccus and Vibrio were the highest in the stomach. Several genera were only detected in certain regions, as follows： stomach, Paracoccus and Hbrio; foregut, Halomonas, Shewanella, and Sphingomonas; midgut, Clostridium and Prevotella; and hindgut, Cetobacterium and Plesiomonas （P〈0.05）. At the species level, Acinetobacter rhizosphaerae was only detected in the stomach. Prevotella copri and Clostridium perfring were not detected in the foregut and midgut, respectively, whereas Prevotella copri and Faecalibacterium pra were not detected in the hindgut. These findings provide valuable information on the microbial community in each gastrointestinal region of C. argus. Moreover, this study indicated that microbial community was not only related to rearing environment but also to the physico-chemical characteristics of each gastrointestinal region.

Selection of Extraction Solvents for Bitumen from Indonesian Oil Sands through Solubility Parameters

Indonesian oil sands were systematically separated to investigate their basic composition.The extraction effects of the solvents with different Hilderbrand solubility parameters(HSPs)on the bitumen of Indonesian oil sands were compared.Furthermore,the Hansen solubility combination parameter(HSCP)and Teas triangle were used to explore rules in the separation of oil sands bitumen via solvent extraction.Finally,the saturates,aromatics,resins,and asphaltenes(SARA)fractions of the bitumen from Indonesian oil sands were analyzed.The results showed that the Indonesian oil sands were oil-wet with a bitumen content of 24.93%.The solvent extraction for bitumen could be accurately and conveniently selected based on the solubility parameter.When the HSPs of the extraction solvent were around 18–19 and the HSCPs were closer to a certain range(δ_(d)=17.5–18.0,δ_(p)=1–3.5,and δ_(h)=2–6),the extraction effect of bitumen from Indonesian oil sands improved,and the primary component affecting the extraction rate of bitumen were asphaltenes.