Filtrate reducer is facing higher requirements and challenges in temperature and salt resistance. A novel polymer filtrate reducer was synthesized by free radical polymerization in aqueous solution. By filtration experiments, the results show that the polymer has good filtration loss performance under high temperature and saturated salt. Through the optimization with filtrate reducer and inhibitor, the optimum components of drilling fluids are water, 4.0wt% bentonite, 0.3wt% Na 2 CO 3 , 2.0wt% DAADS, 3.0wt% SMP-II, 3.0wt% SPNH, 3.0wt% SMC, 1.0wt% SDJA and 2.0wt% RH-3. The drilling fluid system has temperature resistance up to 220°C, salt resistance to saturation and calcium resistance up to 1.0%. The API fluid loss of the drilling fluids with the addition of saturated NaCl and 1wt% CaCl 2 respectively after aging at 220°C was 6.0 mL and 4.4 mL.

Sichuan Basin is one of the centers of pummelo cultivation, domestication and diversity. Also, as one of the main production areas, Sichuan Basin possessed abundant pummelo germplasm resources. In this study, genetic diversity analysis among 73 accessions of pummelo ( Citrus grandis Osbeck) and rootstocks from Sichuan Basin was assessed by using RAPD markers. A total of 156 bands were amplified by 15 RAPD primers, 93.59% (146) of which 146 were polymorphic with an average of 10.4 polymorphic bands per primer. The genetic similarity coefficients of 73 germplasms varied from 0.4511 to 0.9808 at the accession level. At the group level, the maximum GS coefficient index was observed between Wendan and Guanxi Miyou & bud mutants (0.8838), and the minimum GS coefficient was shown in Shatianyou and Putaoyou (0.6852). 73 accessions of pummelo and rootstocks were clustered into five groups with UPGMA method at distance coefficient of 0.6102, consisting of Shatian pummelo varieties group, Wendan pummelo varieties group, Guanxi Miyou & bud mutants group, Putao pummelo varieties group, and rootstocks of C. junos (Pujiang Xiangcheng and Ziyang Xiangcheng) and Poncirus trifoliata . In addition, Guanxi Miyou and bud mutants were clearly separated in our RAPD analysis. This study demonstrated abundant genetic variation among Guanxi Miyou and bud mutants, which could be used core germplasms in the future pummelo breeding program.

Plastic film mulching (PFM) around fruit trees could effectively improve fruit quality by promoting fruit coloration and sugar accumulation. 'Hongroumiyou' and 'Sanhongmiyou' are mutated from Citrus grandis cv. 'Guanximiyou' possessing attractive appearance, rich nutritional ingredients. When they are introduced into Sichuan Province, the fruits revealed lower sugar accumulation and higher acid content than that in Fujian Province. We compared the fruit quality by mulching at 55, 85, 115, 145, 175 days after flowering. The results showed that mulch treatment had no significant effect on the external quality of 'Hongroumiyou' and 'Sanhongmiyou'. While it could effectively improve the internal fruit quality, including promotion of total soluble solid and vitamin C, and decrease of total acid. The best effect on the improvement of fruit quality was mulched at 115 days after flowering for 'Hongroumiyou' and 145 days after flowering for 'Sanhongmiyou'. In addition, mulching cultivation also avoided tree death resulted from the rootrot atrophy because of a long-term flooding. It is important to promote film mulching cultivation in the pummelo production in Sichuan Province.

This paper is based on the ABAQUS finite element simulation software to study the seismic performance of the glass fiber reinforced polymer (GFRP) beam-column joint connected by the slotted-hole angle steel. Non-linear finite element analysis for the effect of slotted-hole on GFRP beams and different slotted-hole sizes on the seismic performance of joints were conducted. Four specimens D1, D2, D3 and D4 with different slotted-hole lengths were designed. The moment-rotation hysteretic curve, skeleton curve and energy dissipation curve of the specimen are obtained. The finite element analysis results show that: 1) the energy consumption of the slotted-hole joint is about 4%-21% higher than that of the ordinary circular hole joint. 2) The longer the slotted holes length is, the better the seismic energy dissipation performance is. The energy dissipation capacity increases by 3%-12% for each 2 mm increase in the slotted-hole length. 3) Although the larger the slotted-hole length is, the better the energy consumption is, the larger the deformation of the component will be caused. Therefore, according to the requirements of serviceability limit state, it is suggested that the slotted-hole length should be between 2 mm and 4 mm.