The determination of gas pressure before uncovering coal in cross-cuts and in shafts is one of the important steps in pre- dicting coal and gas outbursts. However, the time spent for testing gas pressure is, at presen...The determination of gas pressure before uncovering coal in cross-cuts and in shafts is one of the important steps in pre- dicting coal and gas outbursts. However, the time spent for testing gas pressure is, at present, very long, seriously affecting the ap- plication of outburst prediction techniques in opening coal seams in cross-cuts and shafts. In order to reduce the time needed in gas pressure tests and to improve the accuracy of tests, we analyzed the process of gas pressure tests and examined the effect of the length of boreholes in coal seams in tests. The result shows that 1) the shorter the borehole, the easier the real pressure value of gas can be obtained and 2) the main factors affecting the time spent in gas pressure tests are the length of the borehole in coal seams, the gas emission time after the borehole has been formed and the quality of the borehole-sealing. The longer the length of the bore- hole, the longer the gas emission time and the larger the pressure-relief circle formed around the borehole, the longer the time needed for pressure tests. By controlling the length of the borehole in a test case in the Huainan mining area, and adopting a quick sealing technique using a sticky liquid method, the sealing quality was clearly improved and the gas emission time as well as the amount of gas discharged greatly decreased. Before the method described, the time required for the gas pressure to increase during the pressure test process, was more than 10 days. With our new method the required time is only 5 hours. In addition, the accuracy of the gas pressure test is greatly improved.展开更多
Alginate is a widely used polymer matrix in food industry since it allows formation of spherical, soft, and strong membranes adequate for encapsulation of a large amount of products, including food. The flow rate of a...Alginate is a widely used polymer matrix in food industry since it allows formation of spherical, soft, and strong membranes adequate for encapsulation of a large amount of products, including food. The flow rate of alginate solutions and the permeability of the capsules were evaluated within an acidic-low acidic pH range and different alginate concentrations. In solutions adjusted at different pH （3.0 to 7.0） with concentrations of alginate of 0.8, 1.0, and 1.2% w/v, flow rates at 20 ℃ were 6.95 to 10.00, 4.54-5.35, and 2.60-2.80 mL sl, respectively. Permeability of the capsules was evaluated in terms of the diffusion of H＋ions （expressed as pH） and soluble solids （~Brix）. Meanwhile both diffusions were minor at 4.0 〈 pH 〈 7.0 and were significantly superior at more acidic pH （P 〈 0.05）, alginate concentration did not present significant effect. Yellow, purple, and red juices from Stenocereus spp. fruits （pitayas） were encapsulated using 1.0% of alginate and stored with isotonic solution （3 mL g^-1） at 4 ℃ in the dark. The capsules were spherical with diameter between 4.59 and 470 mm, weight from 82.60 to 97.50 rag, and volume of 0.075-0.098 mL. Pigment （total betalains content） diffusion reached equilibrium at 24 h of storage, at which point retentions of total betalains in the yellow, purple, and red capsules were 87.79, 96.13, and 85.13%, respectively. Also, changes in the color of the capsules were observed during storage.展开更多
基金supported by the National Basic Research Program of China (No.2006CB202204-3).
文摘The determination of gas pressure before uncovering coal in cross-cuts and in shafts is one of the important steps in pre- dicting coal and gas outbursts. However, the time spent for testing gas pressure is, at present, very long, seriously affecting the ap- plication of outburst prediction techniques in opening coal seams in cross-cuts and shafts. In order to reduce the time needed in gas pressure tests and to improve the accuracy of tests, we analyzed the process of gas pressure tests and examined the effect of the length of boreholes in coal seams in tests. The result shows that 1) the shorter the borehole, the easier the real pressure value of gas can be obtained and 2) the main factors affecting the time spent in gas pressure tests are the length of the borehole in coal seams, the gas emission time after the borehole has been formed and the quality of the borehole-sealing. The longer the length of the bore- hole, the longer the gas emission time and the larger the pressure-relief circle formed around the borehole, the longer the time needed for pressure tests. By controlling the length of the borehole in a test case in the Huainan mining area, and adopting a quick sealing technique using a sticky liquid method, the sealing quality was clearly improved and the gas emission time as well as the amount of gas discharged greatly decreased. Before the method described, the time required for the gas pressure to increase during the pressure test process, was more than 10 days. With our new method the required time is only 5 hours. In addition, the accuracy of the gas pressure test is greatly improved.
文摘Alginate is a widely used polymer matrix in food industry since it allows formation of spherical, soft, and strong membranes adequate for encapsulation of a large amount of products, including food. The flow rate of alginate solutions and the permeability of the capsules were evaluated within an acidic-low acidic pH range and different alginate concentrations. In solutions adjusted at different pH （3.0 to 7.0） with concentrations of alginate of 0.8, 1.0, and 1.2% w/v, flow rates at 20 ℃ were 6.95 to 10.00, 4.54-5.35, and 2.60-2.80 mL sl, respectively. Permeability of the capsules was evaluated in terms of the diffusion of H＋ions （expressed as pH） and soluble solids （~Brix）. Meanwhile both diffusions were minor at 4.0 〈 pH 〈 7.0 and were significantly superior at more acidic pH （P 〈 0.05）, alginate concentration did not present significant effect. Yellow, purple, and red juices from Stenocereus spp. fruits （pitayas） were encapsulated using 1.0% of alginate and stored with isotonic solution （3 mL g^-1） at 4 ℃ in the dark. The capsules were spherical with diameter between 4.59 and 470 mm, weight from 82.60 to 97.50 rag, and volume of 0.075-0.098 mL. Pigment （total betalains content） diffusion reached equilibrium at 24 h of storage, at which point retentions of total betalains in the yellow, purple, and red capsules were 87.79, 96.13, and 85.13%, respectively. Also, changes in the color of the capsules were observed during storage.
