After gas drainage, the outburst seam is dry and, consequently, during subsequent mechanized mining, unwanted dust production is extensive. Because the hard dustfall typically has a small particle size it contains a h...After gas drainage, the outburst seam is dry and, consequently, during subsequent mechanized mining, unwanted dust production is extensive. Because the hard dustfall typically has a small particle size it contains a high percentage of respirable dust. Considering these factors, this paper improved the efficiency of dustfall by reducing the surface tension of the liquid used as a wetting agent, then configuring five kinds of wetting agents by adopting various doses and types of surfactants, neutral inorganic salts and chemical additives, etc. After purchasing DA-85 and SRJ-1 wetting agent, the surface tension and critical micelle concentration of seven kinds of wetting agents were measured using the capillary rise method. Wetting agent A was confirmed to have the best comprehensive effect. The experiments were optimized by measuring and comparatively analyzing contact angles of pure water, SRJ-1 wetting agent and wetting agent A on the surface of different coal samples using a contact angle measurement instrument （HARKE- SPCA）. By comparative analysis, dust-proof effects of seam, dynamic pressure water infusion and high- pressure spray in the tunneling face at the Daning coal mine using pure water, wetting agent SRJ-1 and A, it was determined that after using wetting agent A, the average dust concentration in the place of the mining machine driver, 10 m and 110 m away from the tunneling front is approximately 300 rag/ m^3, 240 mg/m^3 and 100 mg/m^3, respectively, This practice increased the dust-proof efficiency dramati- cally and achieved a good comprehensive dust-proof effect.展开更多
Background:The uropygial gland is an exocrine gland located above the tail of birds that produces a diverse range of biochemicals.It has been hypothesized to be involved in chemical protection,water-proofing and maint...Background:The uropygial gland is an exocrine gland located above the tail of birds that produces a diverse range of biochemicals.It has been hypothesized to be involved in chemical protection,water-proofing and maintenance of plumage brightness.Although these not necessarily mutually exclusive functions have received some empirical support,there has been little empirical research on the function of water-proofing.Methods:Here we analyzed data for 229 individual eiders(Somateria mollissima)collected by Danish hunters during 2016-2018.Results:The Eider is a sea-duck that spends almost its entire life in sea water emphasizing water-proofing of the plumage.The size of the uropygial gland increased with body mass in males,but not in females,and it increased with age.The size of the uropygial gland decreased during winter. Eiders with small uropygial glands grew their feathers at a fast rate.Eiders with large wing areas had large uropygial glands. Conclusions:These findings are consistent with large uropygial glands playing a role in water-proofing during molt and foraging, but also that uropygial glands may play a role in chemical defense.展开更多
基金partly supported by the National Natural Science Foundation of China (No.51404263)the National Natural Science Foundation of Jiangsu Province (No.BK20130203)+3 种基金the Coal Mine Joint Funds of the National Natural Science Foundation of China (No.51134023)the State Key Laboratory Cultivation Base for Gas Geology and Gas Control (No.WS2013A05)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)the independent study for State Key Laboratory of Coal Resources and Safe Mining,China University of Mining and Technology (No.SKLCRSM09X04)
文摘After gas drainage, the outburst seam is dry and, consequently, during subsequent mechanized mining, unwanted dust production is extensive. Because the hard dustfall typically has a small particle size it contains a high percentage of respirable dust. Considering these factors, this paper improved the efficiency of dustfall by reducing the surface tension of the liquid used as a wetting agent, then configuring five kinds of wetting agents by adopting various doses and types of surfactants, neutral inorganic salts and chemical additives, etc. After purchasing DA-85 and SRJ-1 wetting agent, the surface tension and critical micelle concentration of seven kinds of wetting agents were measured using the capillary rise method. Wetting agent A was confirmed to have the best comprehensive effect. The experiments were optimized by measuring and comparatively analyzing contact angles of pure water, SRJ-1 wetting agent and wetting agent A on the surface of different coal samples using a contact angle measurement instrument （HARKE- SPCA）. By comparative analysis, dust-proof effects of seam, dynamic pressure water infusion and high- pressure spray in the tunneling face at the Daning coal mine using pure water, wetting agent SRJ-1 and A, it was determined that after using wetting agent A, the average dust concentration in the place of the mining machine driver, 10 m and 110 m away from the tunneling front is approximately 300 rag/ m^3, 240 mg/m^3 and 100 mg/m^3, respectively, This practice increased the dust-proof efficiency dramati- cally and achieved a good comprehensive dust-proof effect.
文摘Background:The uropygial gland is an exocrine gland located above the tail of birds that produces a diverse range of biochemicals.It has been hypothesized to be involved in chemical protection,water-proofing and maintenance of plumage brightness.Although these not necessarily mutually exclusive functions have received some empirical support,there has been little empirical research on the function of water-proofing.Methods:Here we analyzed data for 229 individual eiders(Somateria mollissima)collected by Danish hunters during 2016-2018.Results:The Eider is a sea-duck that spends almost its entire life in sea water emphasizing water-proofing of the plumage.The size of the uropygial gland increased with body mass in males,but not in females,and it increased with age.The size of the uropygial gland decreased during winter. Eiders with small uropygial glands grew their feathers at a fast rate.Eiders with large wing areas had large uropygial glands. Conclusions:These findings are consistent with large uropygial glands playing a role in water-proofing during molt and foraging, but also that uropygial glands may play a role in chemical defense.
